Contemporary Primary Total Knee Arthroplasty is Durable in Patients Diagnosed With Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a seronegative spondyloarthropathy affecting the axial spine and peripheral joints. Despite innovations in medical management, patients with AS experience two-fold the lifetime risk of total knee arthroplasty (TKA) compared to the general population. Moreover, recent data have indicated a correlation between spinal pathology and outcomes of TKAs.

Our institutional total joint registry identified 19 patients (28 knees) with a diagnosis of AS treated with primary TKA from 2000 to 2016. The mean age at TKA was 68 years, and 84% of patients were men. The mean follow-up period was 6 years. Outcomes included implant survivorship, clinical outcomes, and complications.

Survivorship free from any revision was 88% at 10 years. A single patient required revision at 8 years for aseptic loosening. Survivorship free from any reoperation was 77% at 10 years. Reoperations included 2 manipulations under anesthesia and 1 superficial wound irrigation and debridement. Mean Knee Society score improved from 46 preoperatively to 89 postoperatively (P < .0001). The mean arc of motion improved from 108^o preoperatively to 116° postoperatively (P = .01). There were 6 complications that did not require reoperation.

Primary TKAs in patients with AS resulted in significant improvement in clinical outcomes with excellent 10-year implant survivorship. Although 2 manipulations under anesthesia were required, the range of motion was restored postoperatively. These data suggest that the contemporary primary TKA can achieve durable and reliable outcomes in patients with axial skeletal disease resulting from AS.

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