Outcomes of knee arthrodesis in proximal femoral focal deficiency.

Treatment options for patients with severe forms of proximal femoral focal deficiency include limb salvage procedures or foot ablation and use of a prosthesis. In patients with amputation, an ipsilateral knee arthrodesis can provide an efficient lever arm that is easy to contain in a prosthetic socket. We performed a retrospective review of proximal femoral focal deficiency patients treated at a single institution with knee arthrodesis. From 1986 to 2018, 26 patients (18 males, eight females) met study inclusion criteria (mean follow-up 13.2 years). Aitken C or D deformities were present in 65% of extremities. Ten patients had concomitant knee fusion with foot ablation (mean age 4.3 years). Fifteen patients had staged procedures with initial foot ablation (mean age 1.3 years) followed by a knee arthrodesis (mean age 4.7 years). One patient was managed with knee arthrodesis and retention of a three-ray foot. Subsequent realignment osteotomies were required in six patients to correct progressive malalignment with growth, often due to retained physis or incomplete physeal resection during the arthrodesis. In severe forms of proximal femoral focal deficiency, a straight residual limb can be achieved with foot ablation and knee arthrodesis to improve weight-bearing alignment in an above knee prosthesis. Progressive deformity, which may interfere with prosthetic fitting and require repeat osteotomy, may occur if complete excision of the physis is not achieved.