Background: 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.
Methods: 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.
Results: 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.
Conclusions: 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.
Level of Evidence: Therapeutic Level I. See Instructions
to Authors for a complete description of levels of evidence.