Rotationplasty (Van Nes) for Distal Femoral / Knee Tumours

Indication. A skeletally immature child (classically 6 to 14 years, with significant growth remaining) with a resectable high-grade malignant bone sarcoma — osteosarcoma or Ewing sarcoma — of the distal femur or proximal tibia, in whom wide margins are achievable, the sciatic nerve is free of tumour, the vessels are either uninvolved or reconstructable, there is no uncontrolled metastatic disease, and an adequate soft-tissue envelope remains. First described by Borggreve in 1930 for an ankylosed tuberculous knee, applied by Van Nes in 1950 to congenital femoral deficiency, and adapted to bone sarcomas by Salzer and Kotz in the 1980s. Contraindications. Sciatic nerve encasement; femoral/popliteal vessels unreconstructable; a contaminated field (a poorly placed biopsy tract or infection); inadequate soft tissue; a foot or ankle that cannot power a prosthesis; uncontrolled widespread metastases; and — critically — a patient or family who, after thorough counselling, cannot accept the cosmetic outcome. Very young age (under about 6 years) is a relative concern because of rotation drift with growth. The one decision that matters. For the same tumour a child can be reconstructed three ways. Each trades function, cosmesis, durability and revision burden differently:

Counsel specifically for the cosmetic appearance of a rotated foot, the need for a lifelong below-knee-style prosthesis, the small risk of vascular failure (which can force a secondary amputation), progressive rotation drift during growth, nonunion at the femorotibial junction, and phantom sensation. Arrange for the family to meet a patient who has had the procedure and to see the prosthesis in use. Setup. Supine on a radiolucent table, the whole limb and the contralateral leg draped free so the rotated ankle can be matched to the opposite knee. General anaesthesia with a regional adjunct for post-operative pain, an arterial line and a urinary catheter, prophylactic antibiotics, a cell saver, and the image intensifier for the osteotomies and fixation. Have a vascular surgeon on standby and microvascular capability available. A tourniquet is rarely used — the vessels must be dissected and assessed throughout.

The goal: resect the tumour-bearing distal femur (or proximal tibia) together with the knee with a wide margin, preserving a sensate, well-perfused distal leg; rotate that leg through 180 degrees; fix the tibia to the femoral stump with the ankle at the level of the contralateral knee; and place the preserved nerve and vessels without kink or tension. Done well, the patient leaves with a biological "knee" powered by their own gastrocnemius-soleus.

Rehabilitation | Phase | Timing | Activity and immobilisation | Milestone | |-------|--------|------------------------------|-----------| | 1 | 0 to 2 weeks | Bulky splint, ankle neutral; hourly neurovascular checks; non-weight-bearing; coordinate with chemotherapy | Wound healing, perfusion stable | | 2 | 2 to 6 weeks | Removable splint; gentle ankle range; bed-to-chair; ongoing vascular surveillance | Soft-tissue healing, drains out | | 3 | 6 to 12 weeks | Protected weight-bearing as union appears on radiograph; ankle and hip strengthening | Radiographic union at about 8 to 12 weeks | | 4 | 3 to 6 months | First then definitive below-knee-style prosthesis; gait training (plantarflexion equals knee extension) | Independent ambulation | | Ongoing | Years | Growth and rotation monitoring; prosthesis revisions; graded return to sport | Community ambulator, sport participation | Most children walk independently in their definitive prosthesis by 3 to 6 months and can run, cycle and swim; long-term series report durable function with high satisfaction once adaptation is complete. Ankle range translates into only modest prosthetic knee excursion, but it is active and well controlled. Complications

Epidemiology. Osteosarcoma is the commonest primary malignant bone tumour of childhood, with an incidence of roughly 3 to 4 cases per million children per year and a peak in the second decade; the distal femur and proximal tibia together account for the majority of lower-limb cases — precisely the rotationplasty territory. Ewing sarcoma is rarer (about 1 to 3 per million) with a male predominance. Because rotationplasty is reserved for selected skeletally immature patients in whom the sciatic nerve is spared, it represents only a small fraction of all sarcoma reconstructions and is concentrated in specialist paediatric sarcoma centres. Pathoanatomy. A high-grade sarcoma destroys the distal femoral (or proximal tibial) metaphysis and threatens the knee. Rotationplasty converts the problem into a solution: rather than discard the distal limb, the tumour-bearing segment and the knee are removed and the remaining leg is rotated 180 degrees so that the ankle joint, with its intact motor and sensory nerve supply, becomes the new knee. The gastrocnemius-soleus becomes the quadriceps equivalent; the tibialis anterior becomes the hamstring equivalent. The open distal tibial and foot physes continue to grow, so the reconstruction lengthens with the child.

Key evidence. Rotationplasty is oncologically safe — survival is equivalent to amputation and to other limb-salvage options when margins are clear. Kotz and Salzer (1982) established the technique in four children with distal femoral osteosarcoma, with no local recurrence and no wound-healing failure despite chemotherapy. Long-term series confirm durable function: Gradl and colleagues (2015) reported a mean MSTS score of about 64 percent at a mean 14-year follow-up, with quality-of-life domains matching or exceeding population norms, and Veenstra and colleagues (2000) found psychosocial functioning and overall quality of life approaching those of healthy peers — while honestly recording that body-image and intimacy concerns persist in a substantial minority. The principal failure mode is vascular: Sawamura and colleagues (2008) found that secondary amputation for vascular compromise clustered in patients who needed a vascular anastomosis, had less than 95 percent chemotherapy-induced tumour necrosis, or presented with a pathological fracture.