Abstract
Knee extensor mechanism reconstruction after excision for bone or soft tissue tumors is a challenging procedure. When a resection of the patellar bone-tendon apparatus is required, an omologous graft can be used for its reconstruction to avoid knee arthrodesis and preserve a functional knee. Since 1996 we performed such a procedure in 15 cases in 14 patients. In 4 cases (Group 1) excision and reconstruction involved only the patella and the attached tendons together with the involved soft tissues. In the remaining 11 cases (Group 2) an extrarticular en-bloc knee resection was accomplished and reconstruction was obtained by a megaprosthesis to replace the distal femur and a composite allograft-prosthesis to replace proximal tibia and the extensor apparatus. One of the en-bloc knee resections was performed in a patient who had previously had an isolated extensor apparatus replacement, which was later converted to a complete knee resection and substitution after a local relapse.
A free flap (anterolateral thigh) was used in 4 patients.
Histotypes were as follows:
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Group 1: pleomorphic sarcoma 2, synovial sarcoma 1, myxofibrosarcoma 1.
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Group 2: osteosarcoma 3 (distal femur 2, proximal tibia 1), Ewing sarcoma 2 (proximal tibia 1, patella 1), giant cell tumor 1 (proximal tibia), chondroblastoma 1 (distal femur) synovial sarcoma 3, pleomorphic sarcoma 1.
One patient in group 2 was lost at follow-up after a few months. In the remaining patients follow-up ranged from 7 to 132 months.
In Group 1 two local and one distant (groin lymphnodes in one of the two patients affected by local recurrence) relapses occurred, in Group 2 one local and 4 distant relapses (lung) occurred. One of these latter distant relapses affected the patient at the beginning in Group 1 and later converted to Group 2.
Besides recurrences, 4 patients in Group 2 were affected by local complications:
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one deep infection;
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one extended resorption of the tibial allograft, which required a two-stage revision (extensor apparatus allograft could be saved);
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one rupture of the patellar tendon allograft after almost 9 years after the first procedure. The ruptured allograft was replaced by an achilles tendon allograft;
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one deep vein thrombosis.
Active extension was initially obtained in all patients and, when local complications did not occur, it was stable with time. Extension lag ranged from 0 to 30°. Maximum flexion ranged from 80 to 110°. Patients could walk without brace nor aids.
Allograft reconstruction after extensor apparatus excision, either alone or combined to a total knee resection, can be an efficacious option in the treatment of sarcomas of the knee.
Correspondence should be addressed to: EFORT Central Office, Technoparkstrasse 1, CH – 8005 Zürich, Switzerland. Email: office@efort.org
