Although excellent long-term results have been reported with cemented tibial fixation, cementless fixation as a means to improve the longevity of total knee prostheses continues to be of interest to clinicians. The purpose of this study was to compare outcomes between cementless tibial fixation with hydroxyapatite and cemented tibial fixation in the first five years following primary total knee arthroplasty.
We performed a prospective, randomized clinical trial that included eighty-one patients with noninflammatory knee arthritis who underwent primary total knee arthroplasty when they were less than seventy years of age. The subjects were randomized at the time of surgery to be treated with either cementless tibial fixation with hydroxyapatite or cemented tibial fixation. Evaluations were performed preoperatively and at six months, one year, and five years postoperatively by a physical therapist who was blinded to group allocation. Self-reported pain and function, the primary outcomes, were measured with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the RAND 36-Item Health Survey (RAND-36). Complications and revision rates were determined through a review of hospital records and at each patient evaluation. The Knee Society radiographic score was used to evaluate plain radiographs at each assessment.
Seventy subjects (86%) completed the five-year assessment. Slightly more pain was reported in the hydroxyapatite group at six months as measured with both the WOMAC and the RAND-36, a difference that disappeared by one year postoperatively. No differences were seen in function, radiographic findings, or complications. No subject required revision of the tibial prosthesis during the study.
At five years postoperatively, there is no difference between cementless tibial fixation with hydroxyapatite and cemented tibial fixation in terms of self-reported pain, function, health-related quality of life, postoperative complications, or radiographic scores.