In partial fulfillment of the

(1)

RECONSTRUCTIVE STRATEGIES IN SOFT TISSUE COVERAGE OF LEG – A PROSPECTIVE DESCRIPTIVE

STUDY

In partial fulfillment of the

regulations for the award of the degree of

MASTER OF CHIRURGIE

(M.Ch.,) Degree

BRANCH – III – PLASTIC SURGERY

THE TAMILNADU

DR. M.G.R. MEDICAL UNIVERSITY CHENNAI, TAMIL NADU.

AUGUST 2011

(2)

DECLARATION

I solemnly declare that this dissertation “RECONSTRUCTIVE STRATEGIES IN SOFT TISSUE COVERAGE OF LEG – A PROSPECTIVE DESCRIPTIVE STUDY” was prepared by me under the able guidance and supervision of our Professor & HOD, Department of Plastic & Reconstructive Surgery, Thanjavur Medical College between August 2008 and April 2011.

This is submitted to The Tamil Nadu Dr. M.G.R. Medical University, Chennai, in partial fulfillment of the requirement for the award of MASTER OF CHIRURGIE, M.Ch., PLASTIC SURGERY, degree Examination to be held in AUGUST 2011.

Place : Thanjavur.

Date : 30.05.2011

Dr. B.K. MOHAMED IBRAHIM

(3)

CERTIFICATE

This is to certify that this dissertation entitled “RECONSTRUCTIVE STRATEGIES IN SOFT TISSUE COVERAGE OF LEG – A PROSPECTIVE DESCRIPTIVE STUDY” submitted by Dr. B.K. MOHAMED IBRAHIM , Post Graduate, Department of Plastic & Reconstructive Surgery, Thanjavur Medical College to The Tamil Nadu Dr. M.G.R. Medical University, Chennai, in partial fulfilment of the requirement in the award of degree of MASTER OF CHIRURGIE IN PLASTIC SURGERY, Branch – III, for the AUGUST 2011 examination is a bonafide research work carried out by him under our direct supervision and guidance during the years 2008 - 2011.

PROF. DR. V.DEVASENAN , M.S. M.Ch., Head of the Department,

Department of Plastic & Reconstructive Surgery, Thanjavur Medical College,

Thanjavur , TamilNadu, India.

(4)

ACKNOWLEDGEMENT

I thank our respected Dean of Thanjavur Medical College and Medical Superintendent of Thanjavur Medical College Hospital, Thanjavur for permitting me to use the hospital facilities for this study.

It is a privilege to express my deep sense of gratitude to my Dynamic, Patient, enthusiastic teacher, mentor and advisor PROF.

Dr.V.DEVASENAN,M.S.,M.Ch., Head of the Department of Plastic &

Reconstructive Surgery, who has not only inspired but also motivated, guided and helped me in completing this dissertation but also has been an inspiration during my entire course.

I express my respect and gratitude to PROF. R.SRIDHARAN M.S.,M.Ch., for his help

&

suggestions given during the study.

I am indebted to PROF. DR. C.BALASUBRAMANIAN M.S.,M.Ch.,

Professor and Head, Department of Plastic & Reconstructive Surgery,

Madurai Medical College for his comments during my study.

(5)

I deeply express my respect and gratitude to DR. P. RAVINDRAN M.S.,M.Ch.,FICS., Associate Professor for his guidance, suggestions and critical comments throughout the study.

I also express my indebtfulness to DR.U.PRABHAKAR M.S.,M.Ch., for his comments, assistance, criticism and continued help during this study.

I sincerely thank my colleagues and my patients without whom this study would not be possible.

Above all, I thank my parents and my wife for their

unconditional support in all the deeds of my life.

(6)

The lower extremity has borne the brunt of injuries which also accompanied man’s march towards the modern age ranging from the industrial accidents to road traffic injuries to warfare injuries to the present day problem of victims of mines and terrorist attacks. WHO estimates that 100% of severe, 50% of moderate and 10% of mildly injured persons need long term rehabilitation services.¹ Hospital-based studies reveal that disabilities persist for a long time with mean time taken to return to work ranges from 42 months to 120 months.^2,3 Census 2001 and the National Sample Survey Organization estimate that nearly 2% of the Indian population is disabled.⁴ Injuries are responsible for nearly one third of all disabilities and Road Traffic Injuries contribute nearly half of them.^5,6 It is estimated that nearly 3.5 million people in India have a disability from injuries with about 2 million being due to Road Trafffic related disability.

Treatment of high energy lower extremity trauma with soft tissue and bone injury remains a formidable problem. Treatment requires a team approach with the orthopedic, vascular and plastic surgeon. The goal in treatment of open tibial fractures and lower extremity salvage is to preserve a limb that will be more functional than an amputation.

There are many possible reconstructive options, which were developed or modified for reconstruction of defects in the lower limb. These include; skin grafts, local flaps, distant flaps, and free flaps. However, each of these techniques has its own limitations. The experience with the use of these reconstructive options is developing in various centers. The use of microsurgical techniques for these difficult problems revolutionized the field with literally limitless tissue available for transfer and defects deemed to be unsalvageable were suddenly salvageable but with the advent of newer techniques like perforator flaps and neurocutaneous flaps there is a

(8)

2

resurgence of interest in non microsurgical reconstructive options. However the indications and the criterion of selection of a particular technique for a particular defect is not well established and is rather a matter of personal judgment. Limb reconstruction is a long and complicated process in which unlike other surgical emergencies protocols are still evolving and evidence based guidelines are not available.

(9)

3

AIMS AND OBJECTIVES

1. The aim of the study is to evaluate the different reconstructive options for management of leg defects.

2. The study also aims to develop an algorithm for soft tissue coverage in different parts of the leg.

(10)

4

REVIEW OF LITERATURE

History

Sometime in stone age eyed needles were invented and bone needles became the standard that was not improved upon until the Renaissance. It is reasonable to assume that these needles were used to sew wounds together.

The history of lower extremity reconstruction began with an attempted morphologic restoration of the shape. The most ancient description is an Egyptian prosthesis found in a pharaoh's sarcophagus. The first written report on injuries of the lower extremity is found in Roman war surgery books, in which amputation is suggested as the elective treatment for serious damage.

Celsus (25 B.C-50 A.D.) introduced the principles of wound closure; removal of all foreign bodies, absolute hemostasis, and careful placing and spacing of sutures.⁷ After the fall of the Roman Empire the tenets of Greek medicine were forgotten, and Galen’s theory that suppuration was essential to healing characterized the treatment of lower extremity wounds.

Ambroise Pare (1509-1590) single handedly led medicine out of the middle ages. He recommended amputation through viable tissue and became the first surgeon to perfom a surgical revision of an amputation for better prosthetic fitting and introduced the concept of choosing the amputation site according to the plans for a prosthesis.⁸

Pierre-Joseph Desault (1744-1795), the chief surgeon at the Hotel Dieu in Paris, coined the term

“debridement”. The concept of immobilization was introduced by ollier (1825-1900) who developed the plaster cast.⁹ Orr from Nebraska treated open fractures of the lower extremity by incising the wound to ensure drainage, and then placing the leg in a plaster cast. Trueta took the idea one step farther, performing a true surgical debridement before placement of the cast.

Trueta observed that infection could be avoided if all devitalized tissue was excised.¹⁰

(11)

5

The introduction of antisepsis and analgesia and the anatomic studies of the leg improved surgical treatment. Lower extremity reconstruction began to be more accurate and sophisticated, as surgeons sought a proper functional reconstruction rather than a pure morphologic restoration of the shape.

The treatment of large defects had always remained remained a challenge until the middle of the 19th century when the focus shifted from amputation to reconstruction. Derived from the dutch word flappe, flaps which retained their blood supply throughout the process of transfer were described to provide coverage for difficult wounds which were not amenable for primary closure or skin grafting.

 In 1854, Hamilton described the cross-leg flap, introducing a new method to repair lower limb defects.

 Filatov, Gillies and Hugo Ganzer in 1920s described the tubed pedicled flap.^11,12,13

 Mcgregor and Morgan defined the distinction between axial and random pattern flaps in the 1950s led to the description of a host of flaps which still are in use today.¹⁴

 Ger in 1968 described the first muscle flap and the concept of musculocutaneous flap revolutionizing lower extremity reconstruction.¹⁵

 In 1973 O’Brien described the first free groin flap for reconstruction of the foot¹⁶ this opened up a whole new era in reconstructive surgery with a wide variety of flaps described but the work was restricted to centers with the necessary instrumentation and skilled operators

 The description by Ponten in 1981 of fasciocutaneous flaps started a new era in lower limb reconstructive surgery.¹⁷

(12)

6

 A further step in lower extremity reconstruction finally was achieved with the introduction of free osteocutaneous flaps such as the fibula flap.¹⁸

 The propeller flap concept described by Hyakusoku in 1991 for reconstruction of elbow defects in post burns contracture was extended by Teo to include flaps based on perforators which rotated 180° and could be used in lower extremities¹⁹ and Masquelat in 1992 described neurofasciocutaneous flaps, these elegant flaps provided an alternative approach to defects which usually required microsurgical reconstruction.²⁰

Inspite of the advances and the wide ranging options available to the surgeon reconstruction of lower extremity still poses a challenge and the ideal reconstructive approach still eludes the operating surgeon

ANATOMY

The structure of the lower limb is determined by its adaptations for weightbearing, locomotion and the maintenance of equilibrium. Functional requirements of a reconstructed lower extremity are a stable post with adequate soft tissue coverage and protective sensation.

The anatomical features relevant in the context of soft tissue reconstruction are discussed below.

CUTANEOUS BLOOD SUPPLY OF THE LOWER LEG

From the level of the tibial tuberosity to the ankle the lower leg is supplied by a combination of direction cutaneous, musculocutaneous and fasciocutaneous vessels. Anterior tibial, posterior tibial and peroneal arteries give off multiple fasciocutaneous perforators which reach the skin by passing along the intermuscular fascial septa. In addition there are musculocutaneous perforators from the surface of gastrocnemius and supplementary vessels superomedially where the saphenous artery extends below the knee, and posteriorly where cutaneous branches of the popliteal artery accompany the sural nerves.

(13)

7 Anterior tibial artery

The first cutaneous branch is the anterior tibial recurrent artery which is given off either anterior or posterior to the interosseous membrane and passes up through tibialis anterior to emerge between it and the tibia at the level of the upper border of the tibial tuberosity. There are usually two or three further perforators from the anterior tibial artery emerging in a row along the anterior border of the upper third of the tibia. Most of the perforators, however, pass along the anterior peroneal septum. There are on average six of these significantly sized fasiocutaneous perforators emerging between extensor digitorum longus and the peroneal compartment although in the lower two-thirds of the leg one or two may be displaced to lie between extensor digitorum longus and tibilalis anterior. Reliable perforators were found within two distinct 5-cm intervals: at 4 to 9 cm and 21 to 26 cm from the intermalleolar line.²¹

Peroneal artery

About five fasciocutaneous perforators arises from the peroneal artery and run along the posterior peroneal septum to spread out and anastomose longitudinally at the level of the deep fascia. A perforating branch pierces the interosseous membrane to appear on the front of the leg, anterior to the peroneal tendons, immediately above the superior extensor retinaculum. The terminal part of the peroneal artery gives of a lateral malloelar branch and then lies on the oscalcis giving off the lateral calcaneal branches. the peroneal perforators are concentrated on the middle third of leg. peroneal perforators are usually found at 3.6-10.8 cm, 14.4--18 cm and 21.6-25.2 cm from the knee joint line.²²

Posterior tibial artery

The most proximal part of the medial side of the lower leg is supplied by the saphenous artery. Below this the posterior tibial artery gives off four larger fasciocutaneous perforators

(14)

8

which emerge between flexor digitorum longus and soleus, give off periosteal vessels to the anterior surface of the tibia, and divide into anterior and posterior branches. The anterior branches run inferiorly over the subcutaneous surface of the tibia and anastomose with perforators from the anterior tibial artery. The posterior branches pass obliquely upwards and downwards anastomosing with each other over the medial side of the leg and in the facial surrounding the tendo calceneus. Distally, the posterior tibial artery gives off malleolar and calcaneal branches which supply skin. Posterior tibial perforators are seen at 3.6-10.8 cm;

14.4--21.6 cm and 25.2-28.8 cm from the knee joint.²²

The sural arteries

The medial sural artery is slightly greater in diameter than the lateral. Within each head of the muscle, each artery divides into two or three longitudinally running branches. These branches give off multiple small twigs to the muscle and several much larger branches which pierce the surface of the muscle to supply the overlying skin. The lateral sural artery may also give off superficial sural cutaneous branches before it enters the lateral head of gastrocnemius. One always accompanies the medial sural cutaneous nerves and its peroneal communicating branch.

The median superficial sural artery

The vessel running in the midline between the heads gastrocnemius will be referred to as the median superficial sural. It arises from the popliteal (48%) from the lateral sural (39%) from one of the inferior genicular arteries (13%) and pierces the popliteal fascia to accompany the medial sural cutaneous nerve and the short saphenous vein. The point at which the artery pierces the deep fascia bridging the groove between the two heads of gastrocnemius is variable but is usually about half-way down the lateral head of gastrocnemia. It follows the lateral edge of the Achilles tendon where it anastomoses with

(15)

9

branches of the peroneal artery and posterior tibial artery²³. Rare instances have been recorded in which the vessel was so well developed that it continued all the way down to the foot and communicated with the lateral tarsal artery.

The artery accompanying the superficial peroneal nerve

It arises from the anterior tibial artery and passes with the nerve between extensor digitorum longus and peroneus longus to become superficial. The anterior tibial origin is from the superior branch to the peroneal compartment in 30% of cases, from the inferior branch in 40% and from both in 30%.²⁴Occasionally it arises from the peroneal artery and winds specifically round the fibula. Various degrees of development of this vessel have been described, but it is generally very small, and does little more than supply the nerve which it accompanies.

Anatomical territories of cutaneous blood supply

The popliteal artery supplies an anatomical territory corresponding to the muscle bellies of gastrocnemius and is often extended downwards in a strip along the dorsal midline to the junction of middle and lower thirds of tibia by the artery accompanying the medial sural cutaneous nerve. The posterior tibial artery covers most of the remaining dorsomedial surface extending almost all the way round to the anterior subcutaneous border of the tibia.

This territory is encroached upon superiorly to a variable extent by the saphenous branch of the descending genicular artery. From the anterior subcutaneous surface of the dbia, around the front of the leg to a vertical line about 1.5 cm posterior to the anterior peroncal septum, the skin is supplied by the anterior tibial artery. The peroneal artery covers the remaining posterolateral part of the leg.

SOFT TISSUE Deep fascia

(16)

10

The deep fascia of the leg, the fascia cruris, is continuous with the fascia lata and is attached around the knee to the patella, the patellar tendon, the tuberosity and condyles of the tibia, and the head of the fibula. Posteriorly it forms the popliteal fascia, which covers the popliteal fossa and perforated by the short saphenous vein and sural nerve. It blends with the periosteum on the subcutaneous surface of the tibia and the head and malleolus of the fibula, and is continuous below with the extensor and flexor retinacula. It is thick and dense in the proximal and anterior part of the leg, and fibres of tibialis anterior and extensor digitorum longus are attached to its deep surface. It is thinner posteriorly where it covers gastrocnemius and soleus. On the lateral side it is continuous with the intermuscular septa of the lower leg, the anterior and posterior crural intermuscular septa, which are attached to the anterior and posterior borders of the fibula respectively.

Deep transverse fascia

The deep transverse fascia of the leg is a fibrous stratum between the superficial and deep muscles of the calf. It extends transversely from the medial margin of the tibia to the posterior border of the fibula. Proximally, where it is thick and dense, it is attached to the soleal ridge of the tibia and to the fibula, inferomedial to the attachment of soleus. At intermediate levels it is thin, but distally, where it covers the tendons behind the malleoli, it is again thick and continuous with the flexor and superior peroneal retinacula.

Interosseous membrane

The interosseous membrane connects the interosseous borders of the tibia and fibula, and separates the anterior and posterior muscles in the leg, some of which are attached to it. The anterior tibial artery passes forwards through a large oval opening near the proximal end of the membrane; distally the perforating branch of the peroneal artery pierces it. Its fibres are predominantly oblique, and most descend laterally.

(17)

11 Osteofascial compartments

The compartments of the leg are particularly well defined. There are three main compartments, anterior (extensor), lateral (peroneal) and posterior (flexor). The anterior compartment, is surrounded by the deep fascia, the tibia, the interosseous membrane and the anterior intermuscular septum. The lateral compartment lies between the intermuscular septa, bordered laterally by the deep fascia and medially by the fibula. The posterior compartment is bounded by the deep fascia, the posterior intermuscular septum, both bones and the interosseous membrane. Its relatively expansile superficial component is separated from the tenser deep component by the deep transverse fascia, reinforced by the deep aponeurosis of soleus.

MUSCLES

The muscles of the leg consist of an anterior group of extensor muscles, which produce dorsiflexion (extension) of the ankle; a posterior group of flexor muscles, which produce plantar flexion (flexion); and a lateral group of muscles derived from the extensors, the peronei.

ANTERIOR or EXTENSOR COMPARTMENT Tibialis anterior

It arises from the lateral condyle and proximal half to two-thirds of the lateral surface of the tibial shaft; the adjoining anterior surface of the interosseous membrane; the deep surface of the deep fascia; and the intermuscular septum between itself and extensor digitorum longus.

The muscle descends vertically and ends in a tendon on its anterior surface in the lower third of the leg. The tendon passes through the medial compartments of the superior and inferior retinacula, inclines medially, and is inserted into the medial and inferior surfaces of the medial cuneiform and the adjoining part of the base of the first metatarsal bone.

(18)

12

Vascular supply- The main body of tibialis anterior is supplied by a series of medial and anterior branches of the anterior tibial artery

Innervation- Tibialis anterior is innervated by the deep peroneal nerve, L4 and 5.

Actions- Tibialis anterior is a dorsiflexor of the ankle joint and invertor of the foot. Acting from below, it helps to counteract any tendency to overbalance backwards by flexing the leg forwards at the ankle. It has a role in supporting the medial longitudinal arch of the foot.

Extensor hallucis longus

It arises from the middle half of the medial surface of the fibula, medial to extensor digitorum longus, and to a similar extent from the adjacent anterior surface of the interosseous membrane. Its fibres run distally and end in a tendon that forms on the anterior border of the muscle. The tendon passes deep to the superior extensor retinaculum and through the inferior extensor retinaculum, crosses to the medial side of the anterior tibial vessels near the ankle, and is inserted into the dorsal aspect of the base of the distal phalanx of the hallux.

Vascular supply- Extensor hallucis longus is supplied by the anterior tibial artery via obliquely running branches, with a variable contribution from the perforating branch of the peroneal artery.

Innervation- Extensor hallucis longus is innervated by the deep peroneal nerve, L5.

Actions- Extensor hallucis longus extends the phalanx of the hallux and dorsiflexes the foot.

Extensor digitorum longus

It arises from the lateral condyle of the tibia, proximal three-quarters of the medial surface of the fibula, adjacent anterior surface of the interosseous membrane, deep surface of the deep fascia, anterior crural intermuscular septum, and the septum between itself and

(19)

13

tibialis anterior. Extensor digitorum longus becomes tendinous at about the same level as tibialis anterior, and the tendon passes behind the superior extensor retinaculum and within a loop of the inferior extensor retinaculum with peroneus tertius. It divides into four slips, which run forward on the dorsum of the foot. At the metatarsophalangeal joints the tendons to the second, third and fourth toes are each joined on the lateral side by a tendon of extensor digitorum brevis. The dorsal digital expansion receives contributions from the lumbrical and interosseous muscles. The expansion narrows as it approaches a proximal interphalangeal joint, and divides into three slips. These are an intermediate slip, attached to the base of the middle phalanx, and two collateral slips, which reunite on the dorsum of the middle phalanx and are attached to the base of the distal phalanx.

Vascular supply- The main blood supply to extensor digitorum longus is derived from anteriorly and laterally placed branches of the anterior tibial artery, supplemented distally from the perforating branch of the peroneal artery. Proximally there may also be a supply from the lateral inferior genicular, popliteal or anterior tibial recurrent arteries

Innervation- Extensor digitorum longus is innervated by the deep peroneal nerve, L5, S1.

Actions- Extensor digitorum longus extends the toes, and it dorsiflexes the ankle synergistically with tibialis anterior and extensor hallucis longus.

Peroneus tertius

It often appears to be part of extensor digitorum longus. The muscle fibres operating on this tendon arise from the distal third or more of the medial surface of the fibula, the adjoining anterior surface of the interosseous membrane, and the anterior crural intermuscular septum. The tendon passes behind the superior extensor retinaculum and within the loop of the inferior extensor retinaculum it shares with extensor digitorum longus.

It is inserted into the medial part of the dorsal surface of the base of the fifth metatarsal bone,

(20)

14

and a thin expansion usually extends forwards along the medial border of the shaft of the bone.

Vascular supply- Peroneus tertius is supplied by the same vessels as extensor digitorum longus.

Innervation- Peroneus tertius is innervated by the deep peroneal nerve, L5, S1.

Actions- During the swing phase of gait electromyographic studies show that peroneus tertius acts with extensor digitorum longus and tibialis anterior to produce dorsiflexion and eversion of the foot.²⁵ This levels the foot and helps the toes to clear the ground, an action that improves the economy of bipedal walking. Peroneus tertius is not active during stance phase, a finding that contradicts suggestions that it acts primarily to support the lateral longitudinal arch or to transfer the centre of pressure of the foot medially.

LATERAL (PERONEAL OR FIBULAR) COMPARTMENT The lateral compartment contains peroneus longus and peroneus brevis.

Peroneus longus

It arises from the head and proximal two-thirds of the lateral surface of the fibula, the deep surface of the deep fascia, the anterior and posterior crural intermuscular septa, and occasionally by a few fibres from the lateral condyle of the tibia. The muscle belly ends in a long tendon that runs distally behind the lateral malleolus in a groove it shares with the tendon of peroneus brevis. The groove is converted into a canal by the superior peroneal retinaculum, so that the tendon of peroneus longus, and that of peroneus brevis which lies behind it, are contained in a common synovial sheath. The peroneus longus tendon runs obliquely forwards across the lateral side of the calcaneus, below the peroneal trochlea and the tendon of peroneus brevis, and beneath the inferior peroneal retinaculum. It crosses the lateral side of the cuboid and then runs under the cuboid in a groove that is converted into a canal by the long plantar ligament. It crosses the sole of the foot obliquely and is attached by

(21)

15

two slips to the lateral side of the base of the first metatarsal bone and the medial cuneiform;

occasionally a third slip is extended to the base of the second metatarsal bone.

Vascular supply of lateral compartment

Usually the predominant supply of the lateral compartment muscles is derived from superior and inferior branches of the anterior tibial artery; the superior is much larger. There is also a lesser, variable, contribution from the peroneal artery in the distal part of the leg. A peroneal branch may replace the inferior anterior tibial branch; less often the peroneal artery provides the main supply to the whole compartment. The upper part of peroneus longus is also supplied by the circumflex fibular artery, which is usually a branch of the anterior tibial artery but sometimes arises more proximally.

Innervation- Peroneus longus is innervated by the superficial peroneal nerve, L5, S1.

Actions- Peroneus longus evert the foot and plantar flex the ankle, and possibly act on the leg from its distal attachments. The oblique direction of its tendon across the sole enable it to support the longitudinal and transverse arches of the foot.

Peroneus brevis

Peroneus brevis arises from the distal two-thirds of the lateral surface of the fibula, anterior to peroneus longus, and from the anterior and posterior crural intermuscular septa. It passes vertically downwards and ends in a tendon that passes behind the lateral malleolus together with, but anterior to, that of peroneus longus. The two tendons run deep to the superior peroneal retinaculum in a common synovial sheath. The tendon of peroneus brevis then runs forwards on the lateral side of the calcaneus above the peroneal trochlea and the tendon of peroneus longus, and is inserted into a tubercle on the base of the fifth metatarsal bone, on its lateral side.

(22)

16

Vascular supply- Discussed under peroneus longus.

Innervation- Peroneus brevis is innervated by the superficial peroneal nerve, L5, S1.

Actions- Peroneus brevis limits inversion of the foot. It participates in eversion of the foot and may help to steady the leg on the foot.

POSTERIOR (FLEXOR) COMPARTMENT

The muscles in the posterior compartment of the lower leg form superficial and deep groups, separated by the deep transverse fascia

Superficial flexor group

The superficial flexors gastrocnemius, plantaris and soleus form the bulk of the calf.

Gastrocnemius

It arises by two heads, connected to the condyles of the femur by strong, flat tendons.

The medial, larger, head is attached to a depression at the upper and posterior part of the medial condyle behind the adductor tubercle, and to a slightly raised area on the popliteal surface of the femur just above the medial condyle. The lateral head is attached to a recognizable area on the lateral surface of the lateral condyle and to the lower part of the corresponding supracondylar line. Both heads also arise from subjacent areas of the capsule of the knee joint. The tendinous attachments expand to cover the posterior surface of each head with an aponeurosis, from the anterior surface of which the muscle fibres arise. The fleshy part of the muscle extends to about midcalf. The muscle fibres of the larger medial head extend lower than those of the lateral head. As the muscle descends, the muscle fibres begin to insert into a broad aponeurosis that develops on its anterior surface; up to this point the muscular masses of the two heads remain separate. The aponeurosis gradually contracts and receives the tendon of soleus on its deep surface to form the calcaneal or Achilles

(23)

17

tendon. On occasion the lateral head, or the whole muscle, is absent. A more frequent variation is a third head, which arises from the popliteal surface of the femur.

The Achilles tendon, approximately 15 cm long, starts at the musculotendinous junction of the gastrocnemius and soleus in the middle of the calf and inserts into a rough area on the middle of the lower part of the posterior surface of the calcaneus. Initially flattened at its junction with the gastrocnemius, it subsequently becomes rounded. It flattens approximately 4 cm from its insertion and then expands to become cartilaginous. On its anterior surface, the tendon receives muscular fibers from the soleus almost to its insertion. Among humans, the gastrocnemius and soleus vary in their orientation, contribution to the Achilles tendon, and the extent of their fusion. In a study, the gastrocnemius contributed between 48% and 66.3%

of the bulk of the tendon. As the tendon descends through the calf, it twists through 90 degrees: the component contributed by the gastrocnemius is found mainly on the lateral and posterior part of the tendon. Some individuals exhibit a double spiral.²⁶

Vascular supply- Each head of gastrocnemius is supplied by its own sural artery. These arteries are branches of the popliteal artery. They arise variably, usually at the level of the tibiofemoral joint line. The medial sural artery almost always arises more proximally than the lateral: the medial may arise proximal to the joint line, the lateral sometimes distal to the line. Each sural artery enters the muscle head with its nerve of supply, the pedicle entering the muscle near its axial border at the level of the middle of the popliteal fossa. Minor accessory sural arteries arise from the popliteal or from the superior genicular vessels

Innervation- Gastrocnemius is innervated by the tibial nerve, S1 and 2.

Plantaris

It arises from the lower part of the lateral supracondylar line and the oblique popliteal ligament. Its small fusiform belly is 7-10 cm long and ends in a long slender tendon which

(24)

18

crosses obliquely between gastrocnemius and soleus, runs distally along the medial border of the calcaneal tendon, and fuses or inserts with it. The muscle is sometimes double, and is absent in 10% of cases.²⁷

Vascular supply- It is supplied superficially by the lateral sural and popliteal arteries, and deeply by the lateral superior genicular artery.

Innervation- Plantaris is innervated by the tibial nerve, often from the ramus that supplies the lateral head of gastrocnemius, S1 and 2.

Actions- In man it is almost vestigial and is normally inserted well short of the plantar aponeurosis, usually into the calcaneus. It is therefore presumed to act with gastrocnemius.

Soleus

It is a broad flat muscle situated immediately deep (anterior) to gastrocnemius. It arises from the posterior surface of the head and proximal quarter of the shaft of the fibula; the soleal line and the middle third of the medial border of the tibia; and from a fibrous band between the tibia and fibula that arches over the popliteal vessels and tibial nerve. This origin is aponeurotic: most of the muscular fibres arise from its posterior surface and pass obliquely to the tendon of insertion on the posterior surface of the muscle. Other muscle fibres arise from the anterior surface of the aponeurosis. They are short, oblique and bipennate in arrangement, and converge on a narrow, central intramuscular tendon that merges distally with the principal tendon. The latter gradually becomes thicker and narrower, and joins the tendon of gastrocnemius to form the calcaneal tendon.

Vascular supply- There are two main arteries of supply to soleus: the superior arises from the popliteal artery at about the level of the soleal arch, and the inferior from the proximal part of the peroneal artery or sometimes from the posterior tibial artery. A secondary supply comes from the lateral sural, peroneal or posterior tibial vessels. There is a venous plexus

(25)

19

within the muscle belly that is important physiologically as part of the muscle pump complex

Innervation- Soleus is innervated by two branches from the tibial nerve, S1 and 2.

Actions of triceps surae- The two heads of gastrocnemius, together with soleus, form a tripartite muscular mass sharing the calcaneal tendon and are sometimes termed the triceps surae. These muscles are the chief plantar flexors of the foot. Gastrocnemius is also a flexor of the knee. Gastrocnemius provides force for propulsion in walking, running and leaping.

Soleus, acting from below, is said to be more concerned with steadying the leg on the foot in standing. This postural role is also suggested by its high content of slow, fatigue-resistant (type 1) muscle fibres. In many adult mammals the proportion of this type of fibre in soleus approaches 100%.

Deep flexor group

The deep flexor group, lying beneath (anterior to) the deep transverse fascia, includes one muscle, popliteus, that acts on the knee joint; the others-flexor digitorum longus, flexor hallucis longus and tibialis posterior-are all plantar flexors of the ankle in addition to their specific actions on joints of the foot and digits.

Flexor digitorum longus

It arises from the posterior surface of the tibia medial to tibialis posterior from just below the soleal line to within 7 or 8 cm of the distal end of the bone; it also arises from the fascia covering tibialis posterior. The muscle ends in a tendon that extends along almost the whole of its posterior surface. The tendon gradually crosses tibialis posterior and passes behind the medial malleolus where it shares a groove with tibialis posterior, from which it is separated by a fibrous septum. It then curves obliquely forwards and laterally, in contact with the medial side of the sustentaculum tali, passes deep to the flexor retinaculum, and enters the

(26)

20

sole of the foot. Here it crosses superficial to the tendon of flexor hallucis longus and receives a strong slip from it. It continues across the sole to form the whole of the long flexor tendon of the fifth toe and contributes to those of the second, third and fourth toes. It may also send a slip to the tendon of flexor hallucis longus. The long flexor tendons of the lateral four digits are attached to the plantar surfaces of the bases of their distal phalanges: each passes between the slips of the corresponding tendon of flexor digitorum brevis at the base of the proximal phalanx.

Vascular supply- A series of transversely running branches of the posterior tibial artery enters the lateral border of flexor digitorum longus. There may be a secondary supply from peroneal branches to flexor hallucis longus.

Innervation- Flexor digitorum longus is innervated by branches of the tibial nerve, L5, S1 and S2.

Actions- discussed under flexor hallucis longus.

Flexor hallucis longus

Flexor hallucis longus arises from the distal two-thirds of the posterior surface of the fibula except for the lowest 2.5 cm; the adjacent interosseous membrane and the posterior crural intermuscular septum; and from the fascia covering tibialis posterior, which it overlaps to a considerable extent. Its fibres pass obliquely down to a tendon that occupies nearly the whole length of the posterior aspect of the muscle. This tendon grooves the posterior surface of the lower end of the tibia, then, successively, the posterior surface of the talus and the inferior surface of the sustentaculum tali of the calcaneus. Fibrous bands convert the grooves on the talus and calcaneus into a canal lined by a synovial sheath. In the sole of the foot, the tendon crosses flexor digitorum longus from lateral to medial, curving obliquely superior to it. At the crossing point the long digital flexor receives a fibrous slip

(27)

21

from the tendon of flexor hallucis longus. The tendon then crosses the lateral part of flexor hallucis brevis to reach the interval between the sesamoid bones under the head of the first metatarsal. It continues on the plantar aspect of the hallux, and runs in an osseo-aponeurotic tunnel to be attached to the plantar aspect of the base of the distal phalanx.

Vascular supply- It is supplied by numerous branches of the peroneal artery.

Innervation- It is innervated by branches of the tibial nerve, L5, S1 and 2 (mainly S1).

Actions of deep digital flexors- Both flexor hallucis longus and flexor digitorum longus can act as plantar flexors but this action is weak compared with gastrocnemius and soleus. When the foot is off the ground, both muscles flex the phalanges of the toes, acting primarily on the distal phalanges. When the foot is on the ground and under load, they act synergistically with the small muscles of the foot and, especially in the case of flexor digitorum longus, with the lumbricals and interossei to maintain the pads of the toes in firm contact with the ground, enlarging the weightbearing area and helping to stabilize the heads of the metatarsal bones, which form the fulcrum on which the body is propelled forwards.

Tibialis posterior

At its origin it lies between flexor hallucis longus and flexor digitorum longus, and is overlapped by both, but especially by the former. Its proximal attachment consists of two pointed processes, separated by an angular interval that is traversed by the anterior tibial vessels. The medial process arises from the posterior surface of the interosseous membrane, except at its most distal part, and from a lateral area on the posterior surface of the tibia between the soleal line above and the junction of the middle and lower thirds of the shaft below. The lateral part arises from a medial strip of the posterior fibular surface in its upper two-thirds. The muscle also arises from the deep transverse fascia, and from the intermuscular septa that separate it from adjacent muscles. In the distal quarter of the leg its

(28)

22

tendon passes deep to that of flexor digitorum longus, with which it shares a groove behind the medial malleolus, each enclosed in a separate synovial sheath. It then passes deep to the flexor retinaculum and superficial to the deltoid ligament to enter the foot. In the foot it is at first inferior to the plantar calcaneonavicular ligament, where it contains a sesamoid fibrocartilage. The tendon then divides into two. The more superficial and larger division, which is a direct continuation of the tendon, is attached to the tuberosity of the navicular, from which fibres continue to the inferior surface of the medial cuneiform. A tendinous band also passes laterally and a little proximally to the tip and distal margin of the sustentaculum tali. The deeper lateral division gives rise to the tendon of origin of the medial limb of flexor hallucis brevis, and then continues between this muscle and the navicular and medial cuneiform to end on the intermediate cuneiform and the bases of the second, third and fourth metatarsals; the slip to the fourth metatarsal is the strongest.

Vascular supply- Tibialis posterior is supplied by numerous branches of small calibre arising from the posterior tibial and peroneal arteries. The tendon is supplied by arteries of the medial malleolar network and by the medial plantar artery.

Innervation- Tibialis posterior is innervated by the tibial nerve, L4 and 5.

Actions- Tibialis posterior is the principal invertor of the foot, although it may assist in vigorous plantar flexion. By reason of its insertions into the cuneiform bones and the bases of the metatarsals, it has long been thought to assist in elevating the longitudinal arch of the foot,

NERVES OF THE LEG TIBIAL NERVE

The tibial nerve, the larger sciatic component, is derived from the ventral branches (anterior division) of the fourth and fifth lumbar and first to third sacral ventral rami. It

(29)

23

descends along the back of the thigh and popliteal fossa to the distal border of popliteus. It then passes anterior to the arch of soleus with the popliteal artery and continues into the leg.

In the leg the tibial nerve descends with the posterior tibial vessels to lie between the heel and the medial malleolus. Proximally it is deep to soleus and gastrocnemius, but in its distal third is covered only by skin and fasciae, overlapped sometimes by flexor hallucis longus. At first medial to the posterior tibial vessels, it crosses behind them and descends lateral to them until it bifurcates. It lies on tibialis posterior for most of its course except distally, where it adjoins the posterior surface of the tibia. The tibial nerve ends under the flexor retinaculum by dividing into the medial and lateral plantar nerves.

Branches

The branches of the tibial nerve are articular, muscular, sural, medial calcaneal and medial and lateral plantar.

Articular branches- Articular branches accompany the superior, inferior medial and middle genicular arteries to the knee joint. They form a plexus with a branch from the obturator nerve and supply the knee joint.

Muscular branches- Proximal muscular branches arise between the heads of gastrocnemius and supply gastrocnemius, plantaris, soleus and popliteus. Muscular branches in the leg, either independently or by a common trunk, supply soleus (on its deep surface), tibialis posterior, flexor digitorum longus and flexor hallucis longus. The branch to flexor hallucis longus accompanies the peroneal vessels.

COMMON PERONEAL NERVE

The common peroneal nerve (common fibular nerve) is approximately half the size of the tibial nerve and is derived from the dorsal branches of the fourth and fifth lumbar and

(30)

24

first and second sacral ventral rami. It descends obliquely along the lateral side of the popliteal fossa to the fibular head, medial to biceps femoris. It lies between the bicipital tendon, to which it is bound by fascia, and the lateral head of gastrocnemius. The nerve then passes into the anterolateral muscle compartment through a tight opening in the thick fascia overlying tibialis anterior. It curves lateral to the fibular neck, deep to peroneus longus, and divides into superficial and deep peroneal nerves.The course of the common peroneal nerve can be indicated by a line from the apex of the popliteal fossa, passing distally, medial to the biceps tendon, to the back of the head of the fibula, where the nerve can be rolled against the bone.

Branches

The common peroneal nerve has articular and cutaneous branches. It terminates as the superficial and deep peroneal nerves.

Articular branches- There are three articular branches. Two accompany the superior and inferior lateral genicular arteries, and may arise in common. The third, the recurrent articular nerve, arises near the termination of the common peroneal nerve.

Cutaneous branches- The two cutaneous branches, often from a common trunk, are the lateral sural and sural communicating nerves. The lateral sural nerve (lateral cutaneous nerve of the calf) supplies the skin on the anterior, posterior and lateral surfaces of the proximal leg. The sural communicating nerve arises near the head of the fibula and crosses the lateral head of gastrocnemius to join the sural nerve. It may descend separately as far as the heel.

SUPERFICIAL PERONEAL NERVE

The superficial peroneal nerve (superficial fibular nerve) begins at the common peroneal bifurcation. It is at first deep to peroneus longus, and passes anteroinferiorly between the peronei and extensor digitorum longus to pierce the deep fascia in the distal third of the leg,

(31)

25

where it divides into medial and lateral branches. Between the muscles it supplies peroneus longus, peroneus brevis and the skin of the lower leg.

Branches

The medial branch passes anterior to the ankle and divides into two dorsal digital nerves:

one supplies the medial side of the great toe, and the other supplies the adjacent sides of the second and third toes. The medial branch communicates with the saphenous and deep peroneal nerves. The smaller lateral branch traverses the dorsum of the foot laterally. It divides into dorsal digital branches that supply the contiguous sides of the third to fifth toes and the skin of the lateral aspect of the ankle, where it connects with the sural nerve. Both branches, especially the lateral, are at risk during the placement of portal incisions for arthroscopy. Branches of the superficial peroneal nerve supply the dorsal skin of all the toes except that of the lateral side of the fifth toe (supplied by the sural nerve) and the adjoining sides of the great and second toes (supplied by the medial terminal branch of the deep peroneal nerve).

DEEP PERONEAL NERVE

The deep peroneal nerve (deep fibular nerve) begins at the common peroneal bifurcation, between the fibula and the proximal part of peroneus longus. It passes obliquely forwards deep to extensor digitorum longus to the front of the interosseous membrane and reaches the anterior tibial artery in the proximal third of the leg. It descends with the artery to the ankle, dividing there into lateral and medial terminal branches. It is first lateral to the artery, then anterior, and again lateral at the ankle.

Branches

The deep peroneal nerve supplies muscular branches to tibialis anterior, extensor hallucis longus, extensor digitorum longus and peroneus tertius, and an articular branch to the ankle

(32)

26

joint. The lateral terminal branch crosses the ankle deep to extensor digitorum brevis, enlarges as a pseudoganglion and supplies extensor digitorum brevis.

The medial terminal branch runs distally on the dorsum of the foot lateral to the dorsalis pedis artery, and connects with the medial branch of the superficial peroneal nerve in the first interosseous space. It divides into two dorsal digital nerves, which supply adjacent sides of the great and second toes.

SAPHENOUS NERVE

The saphenous nerve is the largest cutaneous branch of the femoral nerve. It descends lateral to the femoral artery into the adductor canal,where it crosses anteriorly to become medial to the artery. At the distal end of the canal it leaves the artery and emerges through the aponeurotic covering with the saphenous branch of the descending genicular artery. As it leaves the adductor canal it gives off an infrapatellar branch that contributes to the peripatellar plexus and then pierces the fascia lata between the tendons of sartorius and gracilis, becoming subcutaneous to supply the prepatellar skin. It descends along the medial tibial border with the long saphenous vein and divides distally into a branch which continues along the tibia to the ankle and a branch which passes anterior to the ankle to supply the skin on the medial side of the foot, often as far as the first metatarsophalangeal joint.

SURAL NERVE

The sural nerve descends between the heads of gastrocnemius, pierces the deep fascia proximally in the leg, and is joined at a variable level by the sural communicating branch of the common peroneal nerve. The sural nerve descends lateral to the calcaneal tendon, near the short saphenous vein, to the region between the lateral malleolus and the calcaneus and supplies the posterior and lateral skin of the distal third of the leg. It then passes distal to the lateral malleolus along the lateral side of the foot and little toe, supplying the overlying skin.

(33)

27

The surface marking at the ankle is a line parallel to the calcaneal tendon half-way between the tendon and the lateral malleolus.

THE BLOOD SUPPLY OF THE LOWER LEG:

In 90% of cases the popliteal artery runs obliquely inferolaterally to the lower edge of popliteus where it divides into anterior and posterior tibial arteries. This course can be marked on the surface by a line drawn from the junction of the middle and lower thirds of the thigh 2.5 cm medial to the midline of the back of the limb, running downwards and slightly laterally to reach the midline between the femoral condyles. From here the course of the vessel continues inferolaterally along the same line to the level of the tibial tuberosity.

The anterior tibial artery passes forwards between the tibial and fibular heads of tibialis posterior to pass over the upper edge of the interosseous membrane and reach the anterior compartment. It descends on the front of the interosseous membrane and gradually approaches the tibia to lie on it in the lower third of the leg. The anterior tibial artery is initially medial to the deep peroneal nerve, but descends behind it to lie once more medial to it at the ankle. Near the ankle it is crossed by the extensor hallucis longus tendon and the superior extensor retinaculum, and gives origin to the medial and lateral malleolar arteries before passing midway between the malleoli onto the dorsum of the foot as the dorsalis pedis artery. The posterior tibial artery is the larger and more direct terminal branch of the popliteal. It passes downwards in the posterior compartment separated from the interosseous membrane by tibialis posterior, and lying beneath soleus though separated from it by a fascial layer. It gives a nutrient branch to the tibia and continues downward behind flexor digitorum longus and, becoming superficial, crosses the lower end of the tibia parallel to and 2.5cm in front of the medial border of the Achilles tendon. At the ankle joint it passes deep to the flexor retinaculum, midway between the medial malleolus and the medial tubercle of the calcaneus and divides, deep to abductor hallucis, into the medial and lateral plantar

(34)

28

arteries. The peroneal artery arises from the posterior tibial artery 2.5 cm below the lower edge of the poplitues muscle. It inclines laterally to descend along the medial crest of the fibula deep to or in the substance of flexor hallucis longus and ends behind the tibiofibular syndesmosis. It sends a nutrient artery to the fibula, and is linked to the posterior tibial artery by a communicating branch which lies on average 6.5 cm above the tip of the fibular malleolus. Nearer the ankle (approximately 5 cm above the fibular tip) it gives off a perforating branch which pierces the interosseous membrane and descends in front of the tibiofibular syndesmosis to the anastomosis round the ankle.

Variations

1. Variations occur in the location and manner of branching of the popliteal artery.

Persistence of the embryonic axial artery in the segment known as the deep popliteal artery results in the popliteal artery passing in front of the popliteus muscle. The classical description of the division of the popliteal is accurate in 90% of cases. The remainder show either a high division 5%, low division 1%, or a trifurcation 4%.

2. The anterior tibial artery is often diminished in caliber but never entirely absent. The middle portion may be greatly reduced in which case the perforating branch of the peroneal artery joins the distal portion (5% of 2458 cases). When greatly increased in size the anterior tibial supplies the plantar surface of the foot. The posterior tibial may reach only as far as the distal third of the leg where it is then reinforced by a large communicating branch from the peroneal. It may end as a nutrient vessel to the tibia or in supplying a muscle, or it may even be absent, in which case its territory is supplied by a particularly well-developed peroneal artery. Rarely it may be increased in caliber. The peroneal artery is never absent but is occasionally much reduced in size. Anatomically its size is inversely proportionally to that of the other arteries in the leg, and as described above it may feed the distal parts of the anterior or posterior

(35)

29

tibial arteries. Interestingly it is the vessel least affected by arteriosclerosis in the lower leg.²⁸

BONES AND JOINTS Tibia

The tibia lies medial to the fibula. It has two ends

Proximal end- The expanded proximal end is a bearing surface for body weight, which is transmitted through the femur. It has massive medial and lateral condyles, an intercondylar area and a tibial tuberosity.

Shaft- The shaft is triangular in section and has anteromedial, lateral and posterior surfaces separated by anterior, interosseous and medial borders. The anteromedial surface, between the anterior and medial borders, is broad, smooth and almost entirely subcutaneous. The lateral surface between the anterior and interosseous borders faces laterally in its proximal three-fourths and is transversely concave. Its distal fourth swerves anteriorly, because of the medial deviation of the anterior and distal interosseous borders. This part of the surface is somewhat convex. The posterior surface, between the interosseous and medial borders, is widest above, where it is crossed distally and medially by an oblique, rough soleal line.

Distal end- The slightly expanded distal end of the tibia has anterior, medial, posterior, lateral and distal surfaces. It projects inferomedially as the medial malleolus. The distal end of the tibia, when compared to the proximal end, is laterally rotated.

Vascular supply- The three different sources of tibial blood supply provides a framework in which to assess the vascularity and potential healing ability of any tibial fracture. The artery to the tibia, a branch of the posterior tibial artery enters the bone posteriorly at the junction of the proximal and middle thirds of the bone.²⁹ The nutrient artery occupies an oblique groove in tibial cortex, approximately 5 cm in length. Once inside the medullary cavity, the

(36)

30

nutrient artery gives off proximal and distal branches that supply the cortex from its endosteal surface. The second source of blood supply is the metaphyseal branches.

Neighboring arteries provide branches to the metaphysis of the tibia that anastamose within the medullary cavity with branches from the nutrient artery in the most proximal and distal aspects of the bone. The periosteal vessel provide the third source of tibial blood supply.

Unlike the endosteal blood vessels, which run longitudinally, the periosteal vessels are oriented perpendicular to the long axis of the bone. The periosteal circulation provides circulation to the outer one third of the tibial cortex, while the endosteal circumlation supplies the inner two thirds.

If the tibia is fractured and displaced, the longitudinally of oriented branches of the nutrient artery are disrupted. The bone distal to the fracture therefore is supplied by the transversely oriented periosteal blood supply, and the distal metaphyss by the metaphyseal arteries. The normal dominance of the endosteal circulation is interrupted when a displaced fracture occurs, and the periosteal circulation becomes the chief source of blood supply for the healing fracture site. Any interruption of the periosteal blood supply therefore compromises the healing fracture and necessitates coverage of the bone by healthy tissue that can provide neovascularization to the periosteal structures.

A nondisplaced fracture that is rigidly stabilized demonstrates direct osseous healing by blood supply from the medullary cavity. This situation provides the most rapid type of bone healing. If either the blood supply to the fracture is compromised or the stabilization is not perfect, direct osseous healing does not occur and wound repair must be accomplished via periosteal callus when the periosteum is damaged the surrounding soft issue becomes the source of blood supply.^30,31

(37)

31 Fibula

It has a proximal head, a narrow neck, a long shaft and a distal lateral malleolus.

Head- The head of the fibula projects in front, behind and laterally. A round facet on its proximomedial aspect articulates with a facet on the inferolateral surface of the lateral tibial condyle. The common peroneal nerve crosses posterolateral to the neck and can be rolled against bone there.

Shaft- The shaft has three borders and surfaces, The anterior, the posterior border and interosseous border.The lateral surface, between the anterior and posterior borders and associated with the peroneal muscles. The anteromedial surface, between the anterior and interosseous borders, usually faces anteromedially but often directly anteriorly. It is associated with the extensor muscles. The posterior surface, between the interosseous and posterior borders, is the largest and is associated with the flexor muscles. The anterior intermuscular septum is attached to its proximal three-fourth. The posterior border is proximally indistinct, and the posterior intermuscular septum is attached to all but its distal end.

Lateral malleolus- The distal end forms the lateral malleolus, which projects distally and posteriorly. Its lateral aspect is subcutaneous while its posterior aspect has a broad groove with a prominent lateral border. Its anterior aspect is rough, round and continuous with the tibial inferior border. The medial surface has a triangular articular facet which articulates with the lateral talar surface.

Vascular supply- A little proximal to the midpoint of the posterior surface, the fibular shaft is pierced by a nutrient foramen, directed distally, which receives a branch of the peroneal artery. The detailed anatomy of the peroneal artery in relation to the fibula is the key to raising osteofasciocutaneous free flaps incorporating segments of the bone. The proximal

(38)

32

and distal ends receive metaphyseal vessels from the genicular and ankle arterial anastomoses respectively.

Joints

The minimal range of knee motion that is associated with everyday activities is near-full extension to approximately 120 degrees of flexion. Walking on a flat surface requires 70 degrees of flexion, descending stairs 90 degrees of knee flexion, and normal sitting 100 degrees of Flexion. Consequently, near-normal motion of the knee joint is essential for comfortable function hence a prerequisite for complex reconstructions of the lower leg.

The ankle is a hinge joint allowing little side to side motion. The distal tibia and fibula form a mortise over the body of the talus. The tibia bears most of the weight, with the fibula bearing only one-sixth of the load placed on the leg. Stability of the ankle joint is dependent on the svndesmosis between the tibia and fibula consisting of the anterior and posterior tibiofibular ligaments and the interosseus membrane.

ASSESMENT AND TREATMENT OF LOWER EXTREMITY TRAUMA

The initial assessment and treatment of patients with lower extremity trauma should be in accordance with the Advanced Trauma Life Support (ATLS) guidelines.

The critical components of the initial extremity assessment involve the neurovascular status. The neurologic examination covers both motor and sensory components. A fixed neurologic deficit is probably related to the primary injury, whereas an evolving deterioration in the neurologic status is more likely related to ischemia or compartment syndrome. A rapid assessment of the distal pulses and vascular status of the fact is made. A sterile dressing is applied to the wound and appropriate radiographs are taken. Tetanus prophylaxis is administered.³² The second phase of management begins when the patient arrives in the operating room. Debridement is initiated with the pneumatic tourniquet

(39)

33

inflated and precise, examination of the wound in undertaken. All degloved skin is removed.

Crushed or devitalized muscle is methodically excised. All major neurovascular structures in the vicinity of the injury are explored. Large bone fragments with signigicant soft tissue attachments are maintained and small, free fragments are removed. In addition, in the setting of ischemia, fasciotomies are immediately performed on the lower leg. After the primary debridement, the tourniquet is deflated and hemostasis obtained. A second debridement is performed with the tourniquet deflated. Upon completion of the secondary debridement, the tourniquet is reinflated and the wound is irrigated. Immediate debridement of high energy wounds are considered to be the rule provided the general condition or the comorbid illnesses do not preclude early debridement to combat wound infection but recent studies show that rapid transfer to a trauma center that is capable of definitively treating severe high- energy lower extremity injuries might be associated with the possibility of decreasing infection rates after injury. This effect seems to be independent of any effect on time from the injury to the surgical debridement of the open fracture.³³

Open fractures of the tibia have been classified by Gustillo and Anderson in 1976 according to the degree of severity.³⁴ Infection rates of type I,II and III fractures are 0-12%, 9-55% and 2-12% respectively.³⁵

1. Type I fracture is an open fracture with a cutaneous wound less than I cm in length 2. Type II fracture cutaneous wound more than 1cm with moderate soft tissue damage 3. Type III fracture represents an open fracture or segmental fractures with extensive

soft tissue damage that may be require vascular repair A. Soft tissue cover adequate after debridement

B. Periosteal stripping present, soft tissue cover inadequate C. Arterial injury.

(40)

34

Byrd, spicer and Cierny enlarged the classification of open tibial fractures into four types in order in increasing energy of injury.³⁶

1. A Type I fracture represents low energy forces causing an oblique fracture of the tibia with a relatively clean cutaneous wound less than 2 cm length.

2. A Type II fracture indicated morderate energy forces causing either a displaced fracture or a comminuted tibia fracture with a skin wound greater than 2 cm in length, and accompanying modertake skin and muscle contusion without devitalized muscle.

3. A type III fracture results from high energy forces causing a significantly displaced or severely comminuted fracture or segmental fractures with extensive associated skin loss and devitalized muscle.

4. A Type IV fracture pattern indicates muscle extreme energy forces, a history of crush or degloving injury or vascular injury requiring repair.

As surgeons gained more experience in treating these complex injuries wounds the need to objectively asses and predict the functional outcome was felt and that led to the development of a wide variety of scoring systems, the notable of which are Mangled extremity severity score (MESS); the predictive salvage index (PSI); the Limb Salvage Index (LSI); the Nerve Injury, Ischemia, Soft tissue injury, Skeletal injury, Shock and Age of patient (NISSSA) score; The Hannover fracture scale-97 (HFS-97) and Ganga Hospital Open Injury Severity Score(GHOISS).

The mangled extremity severity score (MESS) was reported in 1990 by Johansen. A strong weightage was given for the presence of warm ischemia time and an age above 30 years. As the “vascular injury” was not clearly defined, the MESS has been used extensively for the evaluation of limbs with normal vascularity also. The MESS evaluates four important variables: degree of injury to the tissues, presence and duration of shock, age of the patient,

(41)

35

and the severity and duration of limb ischemia and a score of 7 or more predicted amputation with 100% accuracy.³⁷

The GHOISS assessed the severity of the injury to the limb separately to each of the three components of the limb: the covering tissues (skin and facia), the skeleton (bones and joints), and the functional tissues (muscles, tendons and nerve units). Seven systemic factors, which may influence, the treatment, and outcome were given two points each, and the final score is arrived by adding all the individual scores together. A score of 14 and below should be attempted for salvage, those with the score of 17 and above should be considered for primary amputation, and those in between must be assessed by an experienced team on a case-to-case basis.³⁸

LEAP study concludes that although the published scores were successful in predicting amputations, scoring systems are not predictive of functional recovery among patients who have undergone successful limb reconstruction. Practitioners should exercise caution when interpreting scores in the context of potential recovery from high-energy trauma.³⁹

After the debridement has been accomplished, bone fixation can be provided by one several techniques. For tibial factures with significant associated soft tissue injury, the external flxator is almost always used. The final step is the provision of soft tissue coverage.

If the defect calls for a flap, Godina favored immediate coverage⁴⁰, whereas other surgeons advocated serial debridement procedures, allowing marginal tissues to demarcate before microvascular free flap coverage.⁴¹Definitive closure within 72 hours is advantageous in terms of bone healing. If repeated debridements are performed over several days, bone fragments desiccate or become excessively contaminated, necessitation removal of all free fragments, including the large fragments. If immediate overage is applied, however, the large fragments with soft tissue attachments can be salvaged eliminating the need for a second bone grafting procedure of at least reducing the the bone defect. The advantage of acute

In partial fulfillment of the

RECONSTRUCTIVE STRATEGIES IN SOFT TISSUE COVERAGE OF LEG – A PROSPECTIVE DESCRIPTIVE

STUDY