Background: Despite the excellent results of total knee replacement, also known as total knee arthroplasty (TKA) there is persistent controversy over whether or not to replace the surface of the kneecap. Anterior knee pain, which occurs with variable and unpredictable frequency, continues to be a problem in a subset of TKA patients. Some clinicians replace the surface of all kneecaps during TKA to avoid repeat surgery, which occurs in approximately 10% of cases. However, others cite the complications attributed to replacing the surface of kneecap as reasons to avoid this procedure. This study prospectively randomized patients receiving TKA into two groups, those receiving replacement of the kneecap surface and those left without replacement of the kneecap surface to determine clinical outcomes and revisions over the first 5-10 postoperative years. Objectives: The primary objective of this work was to compare pain, stiffness and function between groups at five years postoperatively. Secondarily, we compared pain, stiffness and function at one and 10 years postoperatively. Finally, we examined the number of reoperations following TKR over 10 years in the 2 groups of subjects. The investigators hypothesized that there would be no difference between the two groups of subjects in the measured outcomes. Methods: Patients receiving TKA were prospectively enrolled before surgery and randomized intraoperatively to either receive a replacement of the kneecap surface or have no kneecap intervention. The Smith and Nephew Profix TKA system was implanted in all cases; the post-operative regimen was standardized. Subjects were assessed pre-operatively and at 1 and 5 years postoperatively for pain, function, and stiffness using a disease-specific (Western Ontario and MacMaster Osteoarthritis Index \[WOMAC\]) and generic health status (Short Form 36 \[SF-36\]) questionnaire. At the end of the five year follow-up, the study was extended to a 10-year followup and the same outcomes were assessed. The revision rate was also compared between the two groups at the end of the 10-year follow-up.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
38
The Profix™ Total Knee System, a posterior cruciate retaining prosthesis manufactured by Smith and Nephew, Inc. was utilized in all subjects. Subjects randomized to the Resurfaced group received an all polyethylene patellar implant
All subjects received a Profix TKR. Subjects in the Patellar Retention group retained their native patellar surface.
University of Alberta Hospital
Edmonton, Alberta, Canada
Change in Western Ontario MacMaster (WOMAC) Osteoarthritis Index Pain Score From Preoperative to 5 Years Postoperative
This index assesses pain as reported by the patient. The WOMAC Pain scale has a minimum value of 0 (worst pain) to a maximum value of 100 (no pain). The change score was calculated by subtracting the preoperative score from the five year score.
Time frame: Preoperative to 5 years postoperative
Change in WOMAC Osteoarthritis Index Function Score From Preoperative to 5 Years Postoperative
This measures the change in patients' reported function from preoperative to 5 years postoperative. The WOMAC Function scale has a minimum value of 0 (worst function) to a maximum value of 100 (no functional limitations). The change score was calculated by subtracting the preoperative score from the five year score.
Time frame: Preoperative to 5 years postoperative
Change in WOMAC Osteoarthritis Index Stiffness Score From Preoperative to 5 Years Postoperative
This is the change in the patients' perceived pain between preoperative and 5 years postoperative. The WOMAC stiffness scale has a minimum value of 0 (maximal stiffness) to a maximum value of 100 (no stiffness). The change score was calculated by subtracting the preoperative score from the five year score.
Time frame: Preoperative to 5 years postoperative
Change in WOMAC Osteoarthritis Index Pain Score From Preoperative to 1 Year Postoperative
This index assesses pain as reported by the patient. The WOMAC Pain scale has a minimum value of 0 (worst pain) to a maximum value of 100 (no pain). The change score was calculated by subtracting the preoperative score from the one year score.
Time frame: Preoperative to 1 year postoperative
Change in WOMAC Osteoarthritis Index Function Score From Preoperative to 1-year Postoperative
This index assesses function as reported by the patient. The WOMAC function scale has a minimum value of 0 (worst function) to a maximum value of 100 (no functional limitations). The change score was calculated by subtracting the preoperative score from the one year score.
Time frame: Preoperative to 1 year postoperative
Change in WOMAC Osteoarthritis Index Stiffness Score From Preoperative to 1 Year Postoperative
This index assesses stiffness as reported by the patient. The WOMAC stiffness scale has a minimum value of 0 (worst stiffness) to a maximum value of 100 (no stiffness). The change score was calculated by subtracting the preoperative score from the one year score.
Time frame: Preoperative to 1 year postoperative
Change in WOMAC Osteoarthritis Index Pain Score From 5 Years Postoperative to 10 Years Postoperative
This index assesses pain as reported by the patient. The WOMAC Pain scale has a minimum value of 0 (worst pain) to a maximum value of 100 (no pain). The change score was calculated by subtracting the five year score from the 10 year score.
Time frame: 5 years postoperative to 10 years postoperative
Change in WOMAC Osteoarthritis Index Function Score From 5 Years Postoperative to 10 Years Postoperative
This index assesses function as reported by the patient. The WOMAC function scale has a minimum value of 0 (worst pain) to a maximum value of 100 (no pain). The change score was calculated by subtracting the five year score from the 10 year score.
Time frame: 5 years postoperative to 10 years postoperative
Change in WOMAC Osteoarthritis Index Stiffness Score From 5 Years Postoperative to 10 Years Postoperative
This index assesses stiffness as reported by the patient. The WOMAC stiffness scale has a minimum value of 0 (worst stiffness) to a maximum value of 100 (no stiffness). The change score was calculated by subtracting the five-year score from the 10 year score.
Time frame: 5 years postoperative to 10 years postoperative
Number of Revision Surgeries
This measure examined the number of reoperation in the two groups of subjects
Time frame: 10 years
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