Abstract
Background
Secondary osteonecrosis of the knee (SOK) generally occurs in relatively young patients in their working years; at advanced stages of SOK, the only viable surgical option is total knee arthroplasty (TKA). We conducted a retrospective study to investigate implant survivorship, clinical and radiographic outcomes, and complications of cemented TKA with/without patellar resurfacing for SOK.
Methods
Thirty-eight cemented TKAs in 27 patients with non-traumatic SOK with a mean age 43 years (range 17–65) were retrospectively reviewed. Twenty-one patients (78%) were female. Mean body mass index was 31 kg/m2 (range 20–48); 11 patients (41%) received bilateral TKAs. Twenty patients (74%) had a history of corticosteroid use and 18% had a history of alcohol abuse. Patellar osteonecrosis was coincidentally found in six knees (16%), all of which had no anterior knee pain and had no patellofemoral joint collapse. The mean follow-up was 7 years (range 2–12). Knee Society Score (KSS) and radiographic outcomes were evaluated at 6 weeks, 1 year, then every 2–3 years thereafter.
Results
Ninety-two percent had implant survivorship free from revision with significant improvement in KSS. Causes of revision included aseptic tibial loosening (one), deep infection (one), and instability with patellofemoral issues (one). Four of six cases also with patellar osteonecrosis received resurfacing, including one with a periprosthetic patellar fracture after minor trauma, with satisfactory clinical results after conservative treatment. None of the unrevised knees had progressive radiolucent lines or evidence of loosening. Non-resurfacing of the patella, use of a stem extension or a varus-valgus constrained prosthesis constituted 18%, 8% and 3% of knees, respectively.
Conclusion
Cemented TKAs with selective stem extension in patients with SOK had satisfactory implant survivorship and reliable outcomes at a mean of 7 years. Patellar resurfacing is unnecessary in younger patients with no symptoms of anterior knee pain and no patellar collapse radiographically.
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