Reconstructing the chronically disrupted knee extensor mechanism after total knee arthroplasty: Hourglass variant of the original partial allograft technique.

Allograft reconstruction is a valuable treatment option for patients with chronic extensor mechanism disruption after total knee arthroplasty. Here, an hourglass variant of the original partial allograft technique is described. An hourglass-shaped patellar bone block is press-fit into the native patella. The graft is fixed to both the patella and the tibia then sutured with the knee fully extended. Outcomes of this technique were assessed in 5 patients after at least 24months' follow-up. The mean knee and function Knee Society Score values were 77.8 and 64.0, respectively. Extension lag was less than 10 in all 5 patients. This hourglass variant of the partial allograft technique is a useful treatment option that can be used even after patellar resurfacing.