Custom rotating-hinge total knee replacement in patients with spina bifida and severe neuromuscular dysfunction.

Spina bifida (SB) is a congenital disorder which may result in a number of musculoskeletal problems. Total knee replacement (TKR) in this patient group is technically demanding due to bone deformity, soft tissue contracture, muscle tone abnormality and ligament insufficiency. This is a retrospective review of three patients with SB and disabling knee arthritis who were managed with a custom rotating-hinge (RHK) total knee system. All patients reported an improvement in knee pain and stability at mean follow-up 47 months (43-53). Mean Oxford Knee score improved from 21 preoperatively to 32 at final follow-up. One patient required revision of tibial and patella components at 37 months for lateral patella instability and excessive wear. Custom RHK for patients with SB, severe neuromuscular dysfunction and bone deformity relieves pain, restores stability and improves early knee function; however there is a significant risk of extensor mechanism complications and functional outcome is worse than primary TKR in the general population.