Degenerative Joint Disease
Conditions
Keywords
knee arthroplasty
Brief summary
Pain, weakness, instability, and progressive dysfunction are the hallmarks of arthritis of the knee. Total knee replacement may frequently be the only therapeutic intervention to provide adequate improvement in pain and function. Both fixed bearing and mobile bearing knees have a long track record of clinical success. Mobile bearing designs have theoretical advantages of decreased contact stresses on the tibial tray, decreased polyethylene wear, and improved range of motion relative to fixed bearing designs. These theoretical advantages may become especially important in the young patient who requires a knee arthroplasty. This study will attempt to see if there is a clinical difference in outcome between mobile bearing and fixed bearing knee arthroplasties in patients who require total knee replacement.
Detailed description
This prospective, randomized, single-blinded clinical trial compared a mobile-bearing total knee system with two types of fixed-bearing total knee systems in patients undergoing cemented total knee arthroplasty. The devices to be used are FDA approved: the Sigma Knee System (mobile-bearing), the Sigma, Pressfit Condylar posterior cruciate substituting (fixed-bearing) system with a metal backed tibial tray, and the Sigma press-fit condylar posterior cruciate substituting system (fixed bearing) with an all polyethylene tibial tray. The surgical procedures were performed by 4 experienced orthopedic surgeons with a subspecialty interest in total knee arthroplasty. A midline skin incision and medial parapatellar arthrotomy were used to expose the knee. The distal femoral resection was performed with an intramedullary alignment guide, and the proximal tibial resection was performed with an extramedullary alignment guide. Knees with fixed deformities had a surgical release of the contracted tissues on the medial or lateral side, as appropriate, to obtain symmetric balance of the total knee replacement in both flexion and extension. The flexion and extension gaps and the medial and lateral soft-tissue structures were balanced in accordance with standard techniques. Patients began progressive weight-bearing on the first postoperative day, and active knee range of motion was initiated with 24 hours after surgery. Patients were typically discharged on the fourth or fifth postoperative day after obtaining the ability to walk with a walker, to ascend several stairs, and to flex the knee 290 degrees. Patients were asked to return for examination and radiographs at 3 months, 1 year, 2 years, and 5 years after surgery.
Interventions
DEVICESigma Knee System
Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)
DEVICESigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray
Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray)
DEVICESigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Sigma Pressfit Condylar Posterior Cruciate Substituting System (fixed bearing with an all polyethylene tray)
Sponsors
Mayo Clinic
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
40 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
* Patients undergoing unilateral primary knee surgery for degenerative joint disease (DJD).
Exclusion criteria
* Severe deformity greater than or equal to 20 degrees varus, valgus malalignment * Osteomyelitis, septicemia, or other active infections that may spread to other areas of the body * The presence of infections, highly communicable diseases, e.g., AIDS, active tuberculosis, venereal disease, hepatitis * Significant neurological or musculoskeletal disorders or disease that may adversely affect normal gait or weight bearing * Metastatic disease * Any congenital, developmental, or other bone disease or previous knee surgery that may, in the surgeon's judgement, interfere with total knee prosthesis survival or success, e.g., Paget's disease, Charcot's disease secondary to diabetes, severe osteoporosis, previous high tibial osteotomy, etc. * Presence of previous prosthetic knee replacement device (any type) * Arthrodesis of the affected knee * Patients not requiring patella resurfacing.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Maximum Knee Flexion | 2 years post-surgery, 5 years post-surgery | The range of knee motion was measured clinically with use of a goniometer. Measurements were performed by physician assistants in the Department of Orthopedic Surgery who were blinded to the type of implant used. The subject was positioned supine on the examination table, and maximum active flexion was measured. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Knee Society Function Score | 5 years post surgery | The Knee Society Function Score considers only walking distance and stair climbing, with deductions for walking aids. The maximum function score, which is 100, is obtained by a patient who can walk an unlimited distance and go up and down stairs normally. The minimum function score is 0. |
| Knee Society Pain Score | 5 years post-surgery | The Knee Society Pain Score includes walking and climbing stairs. The maximum score per knee is 50 indicating no pain, and 0 indicates severe pain. Therefore the total score (for both knees) could range from 0 to 100. |
| Knee Society Stair Climbing Score | two years post-surgery, five years post-surgery | The stair-climbing portion of the Knee Society clinical rating system assigns a maximum score of 50 points for patients able to ascend and descend stairs in a normal fashion, 40 points for patients needing a rail to descend, 30 points for patients using a rail in both directions, 15 points for patients able to ascend but not descend at all, and 0 points for patients unable ascend or descend. Because stair ascent and descent put substantial demands on the patellofemoral joint, we used that portion of the Knee Society clinical rating system as a proxy for patellofemoral function in this study. |
| Percentage of Knees Surviving at 5 Years | 5 years post-surgery | Kaplan-Meier analysis of five-year implant survival rate |
Countries
United States
Participant flow
Recruitment details
Enrollment in the study began on March 1, 2001, and continued through March 1, 2003.
Pre-assignment details
397 subjects were assessed for eligibility and 157 were excluded prior to randomization because they either declined to participate (n=53), or did not meet inclusion criteria (n=104).
Participants by arm
| Arm | Count |
|---|---|
| Mobile-Bearing Knee Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert) | 80 |
| Modular-Metal-Backed Knee Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray) | 80 |
| All-Polyethylene Knee Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray | 80 |
| Total | 240 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 | FG002 |
|---|---|---|---|---|
| Overall Study | Death | 3 | 3 | 4 |
| Overall Study | Lost to Follow-up | 1 | 1 | 1 |
Baseline characteristics
| Characteristic | Mobile-Bearing Knee | Modular-Metal-Backed Knee | All-Polyethylene Knee | Total |
|---|---|---|---|---|
| Age Continuous | 69.0 years | 68.5 years | 69.0 years | 68.5 years |
| Region of Enrollment United States | 80 participants | 80 participants | 80 participants | 240 participants |
| Sex: Female, Male Female | 56 Participants | 56 Participants | 55 Participants | 167 Participants |
| Sex: Female, Male Male | 24 Participants | 24 Participants | 25 Participants | 73 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — | — / — |
| other Total, other adverse events | 5 / 76 | 4 / 76 | 2 / 75 |
| serious Total, serious adverse events | 0 / 76 | 0 / 76 | 0 / 75 |
Outcome results
Primary
Maximum Knee Flexion
The range of knee motion was measured clinically with use of a goniometer. Measurements were performed by physician assistants in the Department of Orthopedic Surgery who were blinded to the type of implant used. The subject was positioned supine on the examination table, and maximum active flexion was measured.
Time frame: 2 years post-surgery, 5 years post-surgery
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Mobile-Bearing Knee | Maximum Knee Flexion | 5 years post-surgery | 109.0 degrees | Full Range 15.27 |
| Mobile-Bearing Knee | Maximum Knee Flexion | 2 years post-surgery | 110 degrees | — |
| Modular-Metal-Backed Knee | Maximum Knee Flexion | 5 years post-surgery | 109 degrees | Full Range 14.28 |
| Modular-Metal-Backed Knee | Maximum Knee Flexion | 2 years post-surgery | 111 degrees | — |
| All-Polyethylene Knee | Maximum Knee Flexion | 2 years post-surgery | 111 degrees | — |
| All-Polyethylene Knee | Maximum Knee Flexion | 5 years post-surgery | 110.0 degrees | Full Range 13.75 |
Comparison: P-value for the difference between the mean maximum flexion between the three groups at 2 years post-surgery.p-value: 0.64ANOVA
Comparison: P-value for the difference between the mean maximum flexion between the three groups at 5 years post-surgery.p-value: 0.8ANOVA
Secondary
Knee Society Function Score
The Knee Society Function Score considers only walking distance and stair climbing, with deductions for walking aids. The maximum function score, which is 100, is obtained by a patient who can walk an unlimited distance and go up and down stairs normally. The minimum function score is 0.
Time frame: 5 years post surgery
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Mobile-Bearing Knee | Knee Society Function Score | 69.2 units on a scale | Standard Deviation 23.44 |
| Modular-Metal-Backed Knee | Knee Society Function Score | 77.4 units on a scale | Standard Deviation 23.44 |
| All-Polyethylene Knee | Knee Society Function Score | 69.7 units on a scale | Standard Deviation 26.09 |
Comparison: P-value for the difference for the Knee Society Function Score between the three groups at 5 years post-surgery.p-value: 0.06ANOVA
Secondary
Knee Society Pain Score
The Knee Society Pain Score includes walking and climbing stairs. The maximum score per knee is 50 indicating no pain, and 0 indicates severe pain. Therefore the total score (for both knees) could range from 0 to 100.
Time frame: 5 years post-surgery
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Mobile-Bearing Knee | Knee Society Pain Score | 87.8 units on a scale | Standard Deviation 12.17 |
| Modular-Metal-Backed Knee | Knee Society Pain Score | 88.7 units on a scale | Standard Deviation 9.93 |
| All-Polyethylene Knee | Knee Society Pain Score | 88.3 units on a scale | Standard Deviation 11.58 |
Comparison: P-value for the difference for the Knee Society Pain Score between the three groups at 5 years post-surgery.p-value: 0.87ANOVA
Secondary
Knee Society Stair Climbing Score
The stair-climbing portion of the Knee Society clinical rating system assigns a maximum score of 50 points for patients able to ascend and descend stairs in a normal fashion, 40 points for patients needing a rail to descend, 30 points for patients using a rail in both directions, 15 points for patients able to ascend but not descend at all, and 0 points for patients unable ascend or descend. Because stair ascent and descent put substantial demands on the patellofemoral joint, we used that portion of the Knee Society clinical rating system as a proxy for patellofemoral function in this study.
Time frame: two years post-surgery, five years post-surgery
| Arm | Measure | Group | Value (MEAN) |
|---|---|---|---|
| Mobile-Bearing Knee | Knee Society Stair Climbing Score | Two years post-surgery | 39 units on a scale |
| Mobile-Bearing Knee | Knee Society Stair Climbing Score | Five years post-surgery | 36 units on a scale |
| Modular-Metal-Backed Knee | Knee Society Stair Climbing Score | Two years post-surgery | 40 units on a scale |
| Modular-Metal-Backed Knee | Knee Society Stair Climbing Score | Five years post-surgery | 40 units on a scale |
| All-Polyethylene Knee | Knee Society Stair Climbing Score | Two years post-surgery | 39 units on a scale |
| All-Polyethylene Knee | Knee Society Stair Climbing Score | Five years post-surgery | 37 units on a scale |
Comparison: P-value for the difference between the Knee Society Stair Climbing Score between the three groups at 2 years post-surgery.p-value: 0.44ANOVA
Comparison: P-value for the difference between the Knee Society Stair Climbing Score between the three groups at 5 years post-surgery.p-value: 0.08ANOVA
Secondary
Percentage of Knees Surviving at 5 Years
Kaplan-Meier analysis of five-year implant survival rate
Time frame: 5 years post-surgery
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Mobile-Bearing Knee | Percentage of Knees Surviving at 5 Years | With revision for any reason as end point | 98.7 percentage of knees |
| Mobile-Bearing Knee | Percentage of Knees Surviving at 5 Years | With revision for aseptic loosening as end point | 100 percentage of knees |
| Modular-Metal-Backed Knee | Percentage of Knees Surviving at 5 Years | With revision for any reason as end point | 97.4 percentage of knees |
| Modular-Metal-Backed Knee | Percentage of Knees Surviving at 5 Years | With revision for aseptic loosening as end point | 97.4 percentage of knees |
| All-Polyethylene Knee | Percentage of Knees Surviving at 5 Years | With revision for any reason as end point | 98.7 percentage of knees |
| All-Polyethylene Knee | Percentage of Knees Surviving at 5 Years | With revision for aseptic loosening as end point | 98.7 percentage of knees |
Comparison: P-value for the difference between the percentage of knees surviving between the three groups at 5 years post-surgery.p-value: 0.92ANOVA