Above-Knee (Transfemoral) Amputation

Indications

• Peripheral vascular disease (PVD) with critical limb ischemia, especially when the limb cannot be salvaged at a more distal level
• Diabetic foot with extensive tissue loss, osteomyelitis, or gangrene
• Failed transtibial amputation or below-knee wound breakdown
• Trauma with non-reconstructable limb injury above the knee
• Malignancy of the thigh/knee region
• Severe infection (necrotizing fasciitis, gas gangrene)
• Periprosthetic joint infection after total knee arthroplasty (recent systematic review PMID 39327266 shows high mortality and restricted mobility in this subset)
• Congenital limb deficiency

Amputation Levels

Preoperative Assessment

• Transcutaneous oxygen tension (TcPO2): <20 mmHg = high positive predictive value for wound healing failure
• Nutritional status: albumin ≥3 g/dL; lymphocyte count ≥1500/mL
• Preoperative medical frailty
• The most distal level with the best chance of healing should always be chosen in dysvascular limbs

Relevant Anatomy

• Quadriceps femoris (vastus lateralis, medialis, intermedius, rectus femoris), sartorius
• Bounded by lateral and anteromedial intermuscular septa

• Adductor longus, brevis, magnus; gracilis
• Contains the adductor canal with femoral vessels and nerve to vastus medialis

• Hamstrings (biceps femoris, semimembranosus, semitendinosus)
• Sciatic nerve (posteromedial to biceps femoris distally; divides into tibial nerve medially and common peroneal nerve laterally)

Surgical Technique (Standard - Campbell's Technique 18.5)

1. Patient supine; pneumatic tourniquet hemostasis
2. Equal anterior and posterior fish-mouth skin flaps - each flap length = ½ the anteroposterior diameter of the thigh at the level of bone section
3. Anterior incision from medial thigh at bone level, curving distally/laterally across the anterior thigh, then proximally to the lateral thigh
4. Posterior flap fashioned comparably
5. Incisions deepened through subcutaneous tissue and deep fascia; flaps reflected proximally
6. Quadriceps muscle + fascia divided along anterior incision line; reflected proximally
7. Femoral artery and vein identified, ligated, and divided
8. Femoral nerve identified, ligated proximally, divided
9. Femur transected at planned level; ends smoothed with a rasp
10. Sciatic nerve identified beneath hamstrings, ligated well proximal to bone end, divided distal to the ligature
11. Posterior muscles divided transversely so they retract to the bone level
12. All cutaneous nerve ends allowed to retract well proximal to stump end

1. Tourniquet released; meticulous hemostasis
2. Quadriceps "apron" brought over femoral end; fascial layer sutured to posterior thigh fascia
3. Drains placed; skin closed with interrupted nonabsorbable sutures

Gottschalk Modification (Technique 18.6)

• Long medial sagittal flap preferred
• Vastus medialis reflected off intermuscular septum
• Adductor magnus detached from adductor tubercle and reflected medially to expose femur
• Emphasizes adductor myodesis to the lateral femur to prevent the dominant deforming force of abduction and flexion

Why Myodesis Matters

Energy Cost of Walking

• Campbell's Key Point: Energy expenditure for bipedal locomotion rises to 90-100% above baseline for transfemoral amputees (vascular etiology = higher end)
• Bilateral transtibial amputation energy cost (~40-50%) is less than unilateral transfemoral amputation (65-75%) - a classic exam point
• Patients with TFA and PVD are unlikely to become efficient walkers
• A Syme amputation is more energy-efficient than the more distal Chopart (midfoot) amputation - important exception

Postoperative Care & Rehabilitation

• Rigid dressings are difficult to apply/maintain at the transfemoral level; elastic compression dressings are used, often suspended about the contralateral iliac crest
• Stump shaping and desensitization begin early
• Prosthetic fitting is delayed until stump maturation (weeks to months in vascular patients)
• Prosthetic components: Modern computer-assisted hydraulic or magnetic knee units (e.g., C-Leg, Rheo Knee) allow more natural gait and can accommodate longer femoral remnants
• Patients with dysvascular limbs, dialysis dependence, or short stumps are significantly less likely to successfully use a prosthesis

Complications

• Wound breakdown / non-healing - especially in vascular/diabetic patients; SSI incidence reviewed in PMID 38961561
• Phantom limb pain - nerve neuroma formation; regenerative peripheral nerve interfaces (RPNI) are an emerging technique to reduce long-term pain
• Flexion-abduction contracture of the stump (prevented by myodesis and postoperative positioning)
• Adductor roll - from inadequate myodesis
• Stump revision - for skin breakdown, bone prominence, or neuromas
• High perioperative mortality - especially in elderly vascular patients; AKA after periprosthetic TKA infection carries particularly high mortality (PMID 39327266)
• Weight-bearing asymmetry during sit-to-stand is common and has been systematically reviewed (PMID 39240037)

Key Principles Summary

• AK amputation should only be performed when transtibial level is not viable - every level saved dramatically improves function and energy economy
• Stump <5 cm distal to lesser trochanter = effectively a hip disarticulation prosthetically
• Adductor magnus myodesis is non-negotiable for functional outcome
• Sciatic nerve must be ligated well proximal to bone end and allowed to retract
• Vascular AK amputees have poor prosthetic ambulation prognosis; realistic goals must be set preoperatively