coverage of thigh ian maxwell. gastocnemius flap mathes and nahai type i muscle flap indications –...

Coverage of Thigh

Ian Maxwell

Gastocnemius Flap

• Mathes and Nahai type I muscle flap• Indications– Most commonly upper third of leg defects and

knee• Exposed bone, tendon, metal

– Can be advanced on its pedicle as a V-Y for achilles coverage

– Can be used as a functional muscle free flap• Lateral or medial heads can be taken

Mathes and Nahai muscle flap classification

Muscle Anatomy

• Origin:– Lateral head: Lateral epicondyle of femur– Medial head: Superior to medial epicondyle– Posterior to insertion of adductor magnus

• Insertion– Calcaneal epiphysis via achilles tendon

Vascular Anatomy

• Medial head: Medial sural artery from popliteal artery (1cm proximal to knee joint)– 4-5cm from origin of artery to muscle insertion

• Lateral head: Lateral Sural artery– Pedicle length of 4cm (arises more distally)

• Venous drainage via venae comitantes

Innervation

• Tibial nerve

Flap dissection

• Midcalf longitudinal or straight incision beginning a few centimeters proximal to popliteal crease

• Sural vein and saphenous nerve retracted laterally

• Medial and lateral heads dissected in popliteal fossa and continued distally to achilles tendon

Flap dissection

• Medial head is cut from Achilles tendon• Dissect through loose areolar plane proximally

between soleus and medial head of gastroc• Dissect pedicle• If necessary proximally divide origin• Tunnel subcutaneously to defect

Lateral head

• More difficult• Common peroneal nerve at increased risk• Shorter pedicle length• Sometimes necessary of medial head flap

can’t reach defect

Anterolateral thigh Flap

• A type B and C (septocutaneous and musculocutaneous perforators) fasciocutaneous flap

• Useful for local or distant defect reconstruction• Flap size up to 8cm X 25cm with primary closure• Indications:– Free: anywhere– Local: Thin flap, large surface area wounds

• Groin, knee, abdomen, trochanteric region

Arterial Supply

• Lateral femoral circumflex artery– Arises from lateral side of profunda femoris– Runs obliquely in septum between vastis lateralis

and rectus femoris– Pedicle length is 12-16 cm

• For retrograde, distally based flaps can base it off of the lateral superior geniculate artery

Venous drainage

• From venae comitantes accompanying artery

Innervation

• Lateral femoral cutaneous nerve of thigh• Can harvest as a sensate flap

Flap elevation

• Mark ASIS and lateral patella– This is the central axis of the flap

• Draw a circle of radius 3cm in the middle of the line

• This is where the perforators are– Doppler them

• Base your flap around these perforators

Flap dissection

• Dissect anteriorly first down to deep fascia• Dissect subfascial anterior to posterior• Vessels near or approaching the septum are

preserved• Dissect posterior to anterior

Flap dissection

• If vessels are perforators are all septocutaneous then elevate on these

• If musculocutaeous then these must be dissescted out

• Follow pedicle proximally and ligate if free or preserve if pedicled

• If bulk is needed can preserve branches to VL or RF and take muscle with the flap

References

• Microsurgeon.org• Serafin, d. Atlas of microsurgical tissue

transplantation• Wei, Mardini. Flaps and reconstructive surgery