Anatomy of the Leg:

Thigh: there are 3 major compartments (anterior, medial, and posterior)

THIGH	MUSCLES	NERVE	VASCULAR
Anterior	Vastus lateralis, rectus femoris, vastus medialis, vastus intermedius sartorius	Femoral	SFA/Profunda
Medial	Gastrocnemius, adductor magnus, adductor longus, adductor brevis	Obturator
Medial	Semitendinous, semimembranous, biceps femoris	Sciatic

Lower Leg: there are 4 major compartments (anterior, lateral, superficial and deep posterior)

LOWER LEG	MUSCLES	NERVE	VASCULAR
Anterior	Tib Ant, extensor hallicus longus, extensor digitorum longus, peroneus tertius	Deep peroneal nerve	Anterior tibial
Lateral	Peroneus longus, peroneus brevis	Superficial Peroneal
Superficial Posterior	Gastrocnemius, soleus, plantaris	Sural Nerve
Deep Posterior	Flexor hallicus longus, flexor digitorum longus, tibialis posterior, popliteus	Posterior Tibial	Peroneal (lives in the transverse intramuscular septum, covered by the soleus proximally and the FHL distally

Vasculature 

• There are three major vessels that supply the ankle and foot: anterior tibial, posterior tibial, and peroneal. Prior to performing a lower extremity reconstruction you need to know the status of these three vessels for preoperative planning 
• Assessment of perfusion to the foot:
• ankle-brachial indexes or toe-brachial indexes (used to assess perfusion of LE) 
• toe >0.7 is normal 
• ankle <0.9 = PAD, <0.70 = wound healing problems, <0.5 = rest pain 
• BI <0.7 predicts wound healing abnormalities post-operatively 
• CTA: this provides good assessment of the status of vessels preoperative or after reduction/fixation of fractures by orthopedics prior to plastic surgery reconstruction
• Angiogram: this is done in an angio suite or OR and requires direct intubation of the vessels and assessment of the flow in real time  
• Key Landmarks for access to the vessels: 
• Posterior tibial artery – between the medial malleolus and the Achilles tendon 
• Anterior tibial artery – between tib ant and EHL 
• Peroneal – transverse intramuscular septum behind the fibula and often covered completely by FHL 
• Greater saphenous vein: medial the medial mal and EHL 

 Innervation: 

• Common peroneal (femoral): 
• Anatomy: Common peroneal nerve lies between the biceps femoris and gastrocnemius (courses around fibular neck)
• Branches: 
• Superficial peroneal – innervates the lateral compartment
• Provides lateral leg sensation and innervates the peroneus longus/brevis leading to foot eversion  
• Deep peroneal – innervates the anterior compartment
• Provides tib ant, EHL, EDL/B, peroneus and sensation to the first web space leading to dorsiflexion 
• Compression: 
• Most common compression of the lower leg. The fibular head usually by knee dislocations 

• Posterior Tibial  
• Anatomy: lies in the posterior compartment between FHL and FDL, runs with the posterior tibial artery  
• Innervation: 
• Muscle innervation – posterior compartment innervation to the astric, soleus, plantaris, popliteus; FDL, TP, FHL; medial and lateral plantar nerves (plantarflexion) 
• Sensation: sensation to the plantar foot 
• Branches:
Medial Plantar Nerve: 
motor: abductor hallucis, flexor digitorum brevis, flexor hallicus brevis sensory: medial foot

Lateral plantar nerve: 
motor: adductor hallicus, flexor digiti minimi 
• Sural 
• Anatomy: lies in the midline between the two heads of the gastrocnemius in the midleg. At the ankle it lies 1-2cm posterior to the lateral malleolus 
• Innervation: provides sensation to the lateral foot 
• Uses: is often harvested as a nerve graft given its superficial position and that it is purely a sensory nerve
• Thigh Nerves: 
• Femoral nerve: provide innervation to the anterior compartment 
• Obturator: provides innervation to the adductors and cutaneous sensation to the middle thigh 

 
Injury scoring for Lower Extremity Injuries: 
  Gustillo Classification System: 

• I – clean, wound <1cm 
• II – contaminated, wound 1-10cm, moderate soft tissue damage
• IIIA – contaminated wound, >10cm, extensive comminution of the bone with periosteal stripping
• IIIB – contaminated wound, > 10cm, extensive comminution of the bone with periosteal stripping, free flap or rotational flap needed for coverage. 
• IIIC – vascular repair needed 

*Note: need for vascular repair (regardless of the underlying bony and soft tissue injuries) automatically upgrades the injury to a Gustillo 3C
 Compartment syndrome: 

• Definition: compartment pressure >30mmHg or difference between compartment pressure and diastolic <20-30–> fasciotomy 
• Presentation: Remember 5 Ps: pain, pallor, paresthesia, pulselessness, paralysis 
• Treatment: fasciotomies 

Antibiotic guidelines for LE fractures: 

• For Grade I and II open fractures: a first-generation cephalosporin (eg, cefazolin) within 3 hours of initial injury and be continued for 24 hours after initial injury. 
• Grade III open fracture:  aminoglycoside in addition to a first-generation cephalosporin within 3 hours of initial injury, and antibiotics should be continued for 48–72 hours after initial injury but no more than 24 hours after wound closure
• If a fracture is at risk of contamination with clostridium species, such as a farm-related injury, penicillin should be added to the antibiotic regimen 

Bony Reconstruction: 

• Size Limitations: 
• <6cm – nonvascularized cancellous bone graft or limb shortening. Bone shortening >10cm results in abnormal gait 
• >6cm – distraction (ilizarov technique), free osseocutaneous flap, masquelet technique
• >10cm – free flap + allograft (Capanna technique), or distraction osteogenesis 1mm/day starting 7d after injury which usually takes a year 

• Masquelet Technique: use of an antibiotic spacer with staged bone grafting for treatment of bony defects 
• Cappana technique: FVFG with bone allograft for segmental reconstruction of LE. Used frequently after sarcoma resection 

 Vascular recon 

• In cold leg –> temporary shunt should be placed followed by bony stabilization –> then vascular repair 
• >5.5cm defect –> interposition vein grafting. If in a very clean wound can consider a prosthetic graft

Nerve reconstruction: 

• If nerve was transected: repair technique by distance of nerve missing: 
• primary repair if possible 
• <3cm – conduit 
• 3-11cm – cable graft (autologous preferred) with epineurial repair 
• >12cm – no recovery expected 
• If nerve undergoes significant crush, wait three weeks and perform baseline EMG, and then three months and perform repeat EMG. In general – you have to wait for the nerve to regenerate and this takes months 

Osteomyelitis or Soft Tissue Infections: 

• Soft Tissue Infections: 
• For heavily contaminated wounds: recommend serial debridement prior to soft tissue reconstruction 
• Osteo: 
• MRI is the best imaging to diagnosis osteo 
• Needs bony debridement for acute osteo if soft tissue coverage is being considered 

Amputations 

• Always in the conversation when discussing traumatic injuries to the lower extremity Contraindications for lower extremity replantation include crush mechanism of injury, ischemia time over 8 hours, multiple-level injury, poor baseline health, and a patient of advanced age 

Reconstruction (general principles and flaps) 

• Timing: 
• Long standing wounds should be biopsied first to rule out Marjolin’s ulcer 
• Ideal timing: within 72 hours or delay 3 months. Those performed between 72hours-90 days have the worst outcomes. This data however can out prior to the widespread use of wound vac therapy and therefore the data on this may be different given newer wound technologies 
• Reconstruction:
• Upper 1/3 of the lower leg: local flap 
• Middle 1/3 of the lower leg: free flap vs local flap 
• Lower 1/3 of the lower leg: free flap 

Lower Extremity Flaps:
Sartorius Flap: 

• Artery: type IV flap with segmental perforators from the SFA 
• Origin/Insertion: ASIS to anteriomedial tibia 
• Uses: groin coverage 

Gracilis Flap: 

• Artery: MFCA off the profunda 
• Nerve: obturator nerve 
• Markings: the axis of the muscle is about 2-3 cm posterior to the adductor longus tendon. The MFCA enters the flap about 8-10cm distal to the ischium 
• Uses: local flap – groin flap, vaginal recon/perineal recon. Free flap – innervated free flap for facial reanimation, use for upper extremity reconstruction, other coverage 

ALT: (fasciocutaneous flap) 

• Artery: descending branch of the lateral circumflex femoral artery 
• Nerve: lateral femoral cutaneous 
• Markings: along the line for the ASIS to the lateral patella – which closely follows the septum between the vastus lateralis and the rectus femoris. Most of the perforators are located within a 3cm circle at the mid-point of this line. The underlying muscle vastsus lateralis (anterior compartment). 

Posterior thigh 

• Artery: inferior gluteal artery 
• Design: fasciocutaneous – VY, or superiorly based tongue flap. However this flap severs all connections from semitendinosus/semimembranosus/biceps femoris to skin so cannot use any of those as musculocutaneous flaps 

Gastrocneiums Flap:  

• Artery: lateral and medial sural 
• Nerve: Tibial 
• Origin/insertion: femoral condyle (lateral and medial) to the calcaneus via the achilles tendon 
• Markings: Make your incision along the median raphe of the gastrocnemius muscle 
• Uses: medial upper 1/3 leg defects — the medial muscle is generally used because it it longer and does not risk the peroneal nerve 
• Note: the medial gastroc is more commonly used for two reasons (1) it has a larger muscle belly and therefore can generally get more proximal reach (2) does not risk injury to the common peroneal nerve 

Soleus muscle flap

• Artery: 
• Antegrade: popliteal artery 
• Retrograde: posterior tibial artery or peroneal artery 
• Origin/insertion: fibula to calcaneus through the achilles tendon 
• Use: 
• Proximal: for middle 1/3 defects
• Distally based: for distal 1/3 defects 

Reverse Sural artery flap:

• Artery: off the peroneal artery perforators / superficial sural artery 
• Nerve: sural nerve 
• Markings: the flap is marked along the posterior aspect of the lower leg. The pivot point is 5cm proximal to the lateral malleolus. The fascial flap should extend beyond the skin paddle and should be about 7cm. The sural nerve and lesser saphenous vein run in the midline between the two heads of the gastroc and are ligated proximally and should be included into the flap 
• Common issue: venous congestion 
• Treatment:
• Leeches
• Delay: Delayed reverse sural flap based on dividing proximal lesser saphenous vein; other delay is raising and setting back or raising distal portion leaving proximal 

*Side note on Leeches: they work because they secrete hirudin into the wound which is a natural anticoagulant. While treating with leeches patients should be on Bactrim or cipro to prevent leech associated bacterial infection. The most common bug that leeches carry is aeromonas. 
Medial plantar artery flap 

• Artery: medial plantar off the posterior tibial artery lies between the flexor hallucis and  adbuctor hallucis 
• Nerve: medial plantar 
• Use: reliable sensate flap with glabrous skin for coverage of the plantar calcaneus

Bony Flaps that Can be Harvested From the Leg: 
Free Fibula Flap 

• Artery: peroneal 
• Markings: Leave at least 5cm from the fibular head and 5-6cm proximal to the lateral malleolus. The majority of skin perforators are on the distal part of the fibula and come through the posterior intramuscular septum 
• Uses: reconstruction of long bones and mandible 

Medial femoral condyle flap:

• Artery: descending genicular (branch of the SFA) 
• Provides both bone and skin 
• Common uses: scaphoid non-union and talar non-union