Above-Knee Amputation (Transfemoral)

Indication. A transfemoral amputation is performed when the limb cannot be saved and a healthy, functional transtibial (below-knee) level is not achievable. The common scenarios are a dysvascular or diabetic limb with critical ischaemia or extensive tissue loss not amenable to a below-knee amputation, severe non-reconstructable trauma or failed limb salvage where the knee cannot be preserved, a life-threatening infection (necrotising soft-tissue infection or wet gangrene) extending proximal to a viable transtibial level, a tumour requiring proximal margins where limb-sparing surgery is not feasible, and a non-functional limb (fixed deformity, paralysis, intractable pain) where a transfemoral residual limb is more useful than the diseased limb. Relative indications include a failed transtibial amputation needing revision to a higher level, a severe knee flexion contracture that makes a transtibial prosthesis unworkable, and a multiply revised, chronically infected transtibial stump.

Preserve the knee whenever the tissue allows it. The single most important strategic decision is how proximal to amputate. Each level preserved below the knee dramatically improves function, so a transfemoral amputation is chosen only when a healed, functional transtibial stump is not achievable. Caution applies when a viable transtibial level is still possible, when the patient is a candidate for successful revascularisation (vascular assessment first), or when proximal disease will not heal at the transfemoral level and hip disarticulation may be needed. The level-selection trade-off. Losing the knee roughly doubles the metabolic cost of walking and slows comfortable walking speed. Waters' gait-laboratory work showed a stepwise rise in energy cost from transtibial to transfemoral amputation, with the dysvascular transfemoral amputee carrying the highest oxygen cost per metre and the slowest comfortable speed of all levels. In keeping with this, a substantial proportion of older dysvascular transfemoral amputees never achieve independent prosthetic ambulation, in contrast to the higher community-ambulation rates after transtibial amputation. The higher level heals more reliably in poorly perfused tissue — which is precisely why it is chosen when a below-knee amputation would fail — but that gain in healing is paid for in lost walking economy and independence. Predictors of successful prosthetic mobility include younger age, better cognition, absence of contralateral limb disease, and good cardiovascular reserve, and validated tools such as the AMPREDICT model help quantify the probability of prosthetic mobility to frame realistic counselling. Consent specifically for the realistic likelihood of household rather than community ambulation (or a wheelchair-based lifestyle), the high perioperative mortality that reflects the comorbid cardiac and diabetic population rather than the operation itself, stump and phantom limb pain, and the risk to the contralateral limb, which is often equally diseased. Setup. Supine with a sandbag or bump under the ipsilateral buttock to give access to the posterior thigh. Confirm the side and level against imaging and the vascular assessment, and mark the proposed bone level and flaps before draping. Prepare and drape for circumferential access to the thigh. A thigh tourniquet may be used in trauma or tumour but is generally avoided in dysvascular cases so that tissue bleeding and viability can be judged. Anaesthesia is general or regional (spinal or epidural), and pre-emptive multimodal analgesia (regional block, gabapentinoids) is started to reduce acute and persistent phantom limb pain.

The goal: design equal anterior-posterior (fish-mouth) flaps, divide the thigh at the planned bone level while protecting the major vessels and the sciatic nerve, transect and bevel the femur, and restore femoral adduction with an adductor magnus myodesis before a tension-free, well-padded closure. The exposure is built into the flap design and the layered muscle division below — there is no separate incision, the flaps ARE the approach.

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Rehabilitation | Phase | Timing | Focus | Positioning and therapy | |-------|--------|-------|--------------------------| | Immediate | 0 to 2 weeks | Wound protection, oedema control | Rigid or compressive dressing; hip in neutral extension and adduction; no pillow under the stump; drain out at 24 to 48 hours; sutures or staples out at about 2 to 3 weeks | | Intermediate | 2 to 6 weeks | Contracture prevention, strengthening | Daily prone lying; strengthen hip extensors and the remaining adductors; stump shrinker or compression once the wound has healed | | Rehabilitation | 6 weeks onward | Prosthetic fitting | Cast the socket once the stump has healed and matured (volume stabilised); ischial-containment or sub-ischial socket, a prosthetic knee unit and a foot or ankle matched to mobility goals | | Long-term | Months onward | Maintenance | Serial stump-volume and skin review, socket fit and gait; protect the contralateral limb; ongoing review for phantom or neuroma pain | Set realistic expectations from the outset. Many older dysvascular transfemoral amputees achieve household rather than community ambulation, and a frail patient may reasonably choose a wheelchair-based lifestyle; the energy cost of walking is substantially higher than with a transtibial prosthesis. Mobility, walking distance, prosthetic use and quality-of-life tools frame outcome assessment, and the contralateral limb — often equally at vascular and diabetic risk and now bearing extra load — needs active surveillance and protection (foot care, glycaemic and vascular control) to avoid bilateral amputation. Review for warning signs: a non-healing or breaking-down wound, increasing pain or discharge, a developing fixed hip posture, and new rest pain or tissue change in the contralateral limb. Complications

Epidemiology. Dysvascular disease (peripheral arterial disease and diabetes) is the dominant cause of major lower-limb amputation, so the amputee population is older and heavily comorbid with cardiac and diabetic disease. This comorbidity — not the operation itself — drives the high perioperative mortality after major dysvascular lower-limb amputation, and it must frame every pre-operative conversation. Cross-sectional anatomy of the thigh. - Anterior compartment (quadriceps) — rectus femoris and the three vasti, femoral nerve — provides the anterior myofascial flap folded over the bone end.

• Medial compartment (adductors) — adductor longus, brevis, magnus and gracilis, obturator nerve. Adductor magnus is the key muscle for myodesis to maintain femoral adduction.
• Posterior compartment (hamstrings) — biceps femoris, semitendinosus and semimembranosus, sciatic (tibial division) nerve — contributes to the posterior flap and hip extension.
• Femur — the shaft is transected at about 12 cm above the knee joint line; a longer femur improves the lever arm and prosthetic control, so length is preserved as much as healing permits while leaving room for the knee unit, and the anterior cortex is bevelled.
• Neurovascular — the superficial femoral artery and vein run in the adductor (Hunter's, subsartorial) canal on the medial side toward the popliteal fossa and are the principal vessels to ligate; the profunda femoris gives muscular perforators that must be controlled; the sciatic nerve lies deep in the posterior compartment with its arteria comitans; and cutaneous nerves (posterior femoral cutaneous, saphenous branches) cross the flaps and contribute to neuroma or scar sensitivity if handled roughly.

Hip muscle balance — why myodesis matters. Detaching the adductors and hamstrings leaves the abductors (gluteus medius and minimus) and flexors (iliopsoas, rectus femoris) relatively unopposed. Their pull drives the residual femur into abduction and flexion — the basis of the dreaded abduction-flexion contracture. Gottschalk's biomechanical work showed that losing the distal attachment of the adductor magnus strips away most of its adduction moment arm; re-anchoring it with a myodesis is the surgical antidote, restoring the adduction moment and a more neutral femoral position for prosthetic alignment. Energy expenditure and prosthetic mobility. Walking after amputation costs more oxygen and is slower at each more proximal level. Waters' gait-laboratory comparison established the stepwise rise in energy cost from transtibial to transfemoral amputation, with the dysvascular transfemoral amputee carrying the highest oxygen cost per metre and the slowest comfortable walking speed, and vascular amputees performing worse than traumatic amputees at every level. A substantial proportion of dysvascular transfemoral amputees never achieve independent prosthetic ambulation. Predictors of successful mobility include younger age, better cognition, the absence of contralateral limb disease and good cardiovascular reserve, and validated multivariable models such as AMPREDICT quantify the probability of prosthetic mobility to guide prescription and counselling. Healing and outcomes. Transfemoral amputation has a higher primary healing rate than transtibial amputation in poorly perfused limbs — precisely why it is chosen when a below-knee amputation would fail — but this gain in healing is offset by a markedly inferior functional outcome. Mortality after major dysvascular lower-limb amputation is high, reflecting the comorbid cardiac and diabetic population rather than the operation itself, and the contralateral limb is frequently also at risk.