Total Knee Replacement
Conditions
Keywords
Total Knee Replacement, Patellar Resurfacing, Health Related Quality of Life
Brief summary
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.
Interventions
DEVICEPatellar Replacement Prosthesis
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
DEVICEProfix TKR with Patellar Retention
All subjects received a Profix TKR. Subjects in the Patellar Retention group retained their native patellar surface.
Sponsors
Smith & Nephew, Inc.
University of Alberta
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
40 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
* scheduled for primary TKA to treat non-inflammatory arthritis * age 40- 75 years of age
Exclusion criteria
* history of knee sepsis * previous patellectomy * previous high tibial osteotomy * knee flexion contracture of \>20 degrees * varus or valgus deformity of \> 20 degrees * \< 90 degrees of knee flexion * tibial or femoral bone deficiency requiring augmentation
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Western Ontario MacMaster (WOMAC) Osteoarthritis Index Pain Score From Preoperative to 5 Years Postoperative | 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. |
| Change in WOMAC Osteoarthritis Index Function Score From Preoperative to 5 Years Postoperative | 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. |
| Change in WOMAC Osteoarthritis Index Stiffness Score From Preoperative to 5 Years Postoperative | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in WOMAC Osteoarthritis Index Stiffness Score From Preoperative to 1 Year Postoperative | 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. |
| Change in WOMAC Osteoarthritis Index Pain Score From 5 Years Postoperative to 10 Years Postoperative | 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. |
| Number of Revision Surgeries | 10 years | This measure examined the number of reoperation in the two groups of subjects |
| Change in WOMAC Osteoarthritis Index Stiffness Score From 5 Years Postoperative to 10 Years Postoperative | 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. |
| Change in WOMAC Osteoarthritis Index Function Score From 5 Years Postoperative to 10 Years Postoperative | 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. |
| Change in WOMAC Osteoarthritis Index Pain Score From Preoperative to 1 Year Postoperative | 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. |
| Change in WOMAC Osteoarthritis Index Function Score From Preoperative to 1-year Postoperative | 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. |
Countries
Canada
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Patellar Resurfacing Subjects received patellar resurfacing. | 21 |
| Patellar Retention Subjects retained their native patella. | 17 |
| Total | 38 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Death | 4 | 2 |
| Overall Study | Lost to Follow-up | 5 | 4 |
Baseline characteristics
| Characteristic | Patellar Retention | Patellar Resurfacing | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 4 Participants | 12 Participants | 16 Participants |
| Age, Categorical Between 18 and 65 years | 13 Participants | 9 Participants | 22 Participants |
| Age, Continuous | 62.0 years STANDARD_DEVIATION 5.6 | 64.9 years STANDARD_DEVIATION 4 | 63.6 years STANDARD_DEVIATION 4.9 |
| Region of Enrollment Canada | 17 participants | 21 participants | 38 participants |
| Sex: Female, Male Female | 10 Participants | 16 Participants | 26 Participants |
| Sex: Female, Male Male | 7 Participants | 5 Participants | 12 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 21 | 0 / 17 |
| serious Total, serious adverse events | 0 / 21 | 0 / 17 |
Outcome results
Primary
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
Population: One subject in the patellar retention group missed too many responses on the WOMAC questionnaire and was not included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in Western Ontario MacMaster (WOMAC) Osteoarthritis Index Pain Score From Preoperative to 5 Years Postoperative | 34.7 units on a scale | Standard Deviation 20.9 |
| Patellar Retention | Change in Western Ontario MacMaster (WOMAC) Osteoarthritis Index Pain Score From Preoperative to 5 Years Postoperative | 39.2 units on a scale | Standard Deviation 19.6 |
p-value: 0.59t-test, 2 sided
Primary
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
Population: One subject in the patellar retention group missed too many responses on the WOMAC questionnaire and was not included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in WOMAC Osteoarthritis Index Function Score From Preoperative to 5 Years Postoperative | 21.8 units on a scale | Standard Deviation 17.9 |
| Patellar Retention | Change in WOMAC Osteoarthritis Index Function Score From Preoperative to 5 Years Postoperative | 27.5 units on a scale | Standard Deviation 15.6 |
p-value: 0.39t-test, 2 sided
Primary
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
Population: One subject in the patellar retention group missed too many responses on the WOMAC questionnaire and was not included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in WOMAC Osteoarthritis Index Stiffness Score From Preoperative to 5 Years Postoperative | 38.2 units on a scale | Standard Deviation 32 |
| Patellar Retention | Change in WOMAC Osteoarthritis Index Stiffness Score From Preoperative to 5 Years Postoperative | 29.2 units on a scale | Standard Deviation 26.3 |
p-value: 0.43t-test, 2 sided
Secondary
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
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in WOMAC Osteoarthritis Index Function Score From 5 Years Postoperative to 10 Years Postoperative | 14.2 units on a scale | Standard Deviation 17.7 |
| Patellar Retention | Change in WOMAC Osteoarthritis Index Function Score From 5 Years Postoperative to 10 Years Postoperative | 14.4 units on a scale | Standard Deviation 13.6 |
p-value: 0.98t-test, 2 sided
Secondary
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
Population: Two subjects, one in the patellar retention group and one in the patellar resurfacing group missed too many responses on the WOMAC questionnaire and was not included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in WOMAC Osteoarthritis Index Function Score From Preoperative to 1-year Postoperative | 24.1 units on a scale | Standard Deviation 16.6 |
| Patellar Retention | Change in WOMAC Osteoarthritis Index Function Score From Preoperative to 1-year Postoperative | 19.5 units on a scale | Standard Deviation 16.9 |
Secondary
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
Population: Two subjects, one in the patellar retention group and one in the patellar resurfacing group missed too many responses on the WOMAC questionnaire and was not included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in WOMAC Osteoarthritis Index Pain Score From 5 Years Postoperative to 10 Years Postoperative | 12.7 units on a scale | Standard Deviation 20 |
| Patellar Retention | Change in WOMAC Osteoarthritis Index Pain Score From 5 Years Postoperative to 10 Years Postoperative | 10.0 units on a scale | Standard Deviation 12 |
p-value: 0.71t-test, 2 sided
Secondary
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
Population: Two subjects, one in the patellar retention group and one in the patellar resurfacing group missed too many responses on the WOMAC questionnaire and was not included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in WOMAC Osteoarthritis Index Pain Score From Preoperative to 1 Year Postoperative | 32.9 units on a scale | Standard Deviation 18.2 |
| Patellar Retention | Change in WOMAC Osteoarthritis Index Pain Score From Preoperative to 1 Year Postoperative | 34.3 units on a scale | Standard Deviation 21.5 |
p-value: 0.83t-test, 2 sided
Secondary
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
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in WOMAC Osteoarthritis Index Stiffness Score From 5 Years Postoperative to 10 Years Postoperative | 3.4 units on a scale | Standard Deviation 33.6 |
| Patellar Retention | Change in WOMAC Osteoarthritis Index Stiffness Score From 5 Years Postoperative to 10 Years Postoperative | 15.0 units on a scale | Standard Deviation 19.4 |
p-value: 0.35t-test, 2 sided
Secondary
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
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Patellar Resurfacing | Change in WOMAC Osteoarthritis Index Stiffness Score From Preoperative to 1 Year Postoperative | 24.4 units on a scale | Standard Deviation 24.5 |
| Patellar Retention | Change in WOMAC Osteoarthritis Index Stiffness Score From Preoperative to 1 Year Postoperative | 8.3 units on a scale | Standard Deviation 32.3 |
p-value: 0.1t-test, 2 sided
Secondary
Number of Revision Surgeries
This measure examined the number of reoperation in the two groups of subjects
Time frame: 10 years
Population: All participants were analyzed.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Patellar Resurfacing | Number of Revision Surgeries | 3 participants |
| Patellar Retention | Number of Revision Surgeries | 1 participants |
p-value: 0.31Chi-squared