Reevaluating isolated polyethylene revision for instability after total knee arthroplasty

Instability is a common mode of failure after primary total knee arthroplasty (TKA). Surgical management includes total revision and isolated polyethylene exchange. This study aimed to evaluate outcomes after isolated polyethylene exchange for instability in one of the largest cohorts reported to date.

This is a retrospective study of 87 patients and 93 cases of isolated polyethylene exchange after TKA for instability at a tertiary academic center. Preoperative and postoperative Knee Society Scores were compared using paired T-testing with a significance level set at p = .05. Secondary outcomes included satisfaction, complications, rates of additional surgery, and recurrent instability.

Of the 87 patients, 61 patients had both pre and post-operative KSS-Knee scores and 60 with matched KSS-Functional scores. KSS-Knee scores significantly increased from 63.78 to 83.13 (p < .05), and KSS-Functional scores increased from 63.80 to 84.00 (p < .05). Seven of 93 cases (7.78%) cases required additional surgery at an average of 3.8 years, including two for recurrent instability. Nine (10%) cases were initially satisfied but developed recurrent instability at an average of 27.6 months.

Isolated polyethylene exchange after TKA for instability resulted in significantly increased reported clinical outcome scores. Isolated polyethylene exchange after TKA for recurrent instability may be a viable option but surgeons should consider the rate of complications requiring surgery as well as high rate of recurrent instability. More studies with longer-term follow-up are required to further identify which patients may benefit the most from isolated polyethylene exchange after TKA for recurrent instability.