Trial Outcomes & Findings for Comparison of A Mobile-Bearing Total Knee System With A Fixed-Bearing Total Knee System In Cemented Total Knee Arthroplasty (NCT NCT00589108)

Results Overview

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.

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

240 participants

Primary outcome timeframe

2 years post-surgery, 5 years post-surgery

Results posted on

2013-01-16

Participant Flow

Enrollment in the study began on March 1, 2001, and continued through March 1, 2003.

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).

Participant milestones

Participant milestones
Measure	Mobile-Bearing Knee Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	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)	All-Polyethylene Knee Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Overall Study STARTED	80	80	80
Overall Study COMPLETED	76	76	75
Overall Study NOT COMPLETED	4	4	5

Reasons for withdrawal

Reasons for withdrawal
Measure	Mobile-Bearing Knee Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	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)	All-Polyethylene Knee Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Overall Study Lost to Follow-up	1	1	1
Overall Study Death	3	3	4

Baseline Characteristics

Comparison of A Mobile-Bearing Total Knee System With A Fixed-Bearing Total Knee System In Cemented Total Knee Arthroplasty

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Mobile-Bearing Knee n=80 Participants Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	Modular-Metal-Backed Knee n=80 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray)	All-Polyethylene Knee n=80 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray	Total n=240 Participants Total of all reporting groups
Age Continuous	69.0 years n=5 Participants	68.5 years n=7 Participants	69.0 years n=5 Participants	68.5 years n=4 Participants
Sex: Female, Male Female	56 Participants n=5 Participants	56 Participants n=7 Participants	55 Participants n=5 Participants	167 Participants n=4 Participants
Sex: Female, Male Male	24 Participants n=5 Participants	24 Participants n=7 Participants	25 Participants n=5 Participants	73 Participants n=4 Participants
Region of Enrollment United States	80 participants n=5 Participants	80 participants n=7 Participants	80 participants n=5 Participants	240 participants n=4 Participants

PRIMARY outcome

Timeframe: 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.

Outcome measures

Outcome measures
Measure	Mobile-Bearing Knee n=76 Participants Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	Modular-Metal-Backed Knee n=76 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray)	All-Polyethylene Knee n=75 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Maximum Knee Flexion 2 years post-surgery	110 degrees Interval 90.0 to 130.0	111 degrees Interval 90.0 to 130.0	111 degrees Interval 90.0 to 140.0
Maximum Knee Flexion 5 years post-surgery	109.0 degrees Full Range 15.27 • Interval 40.0 to 140.0	109 degrees Full Range 14.28 • Interval 60.0 to 140.0	110.0 degrees Full Range 13.75 • Interval 80.0 to 140.0

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome measures
Measure	Mobile-Bearing Knee n=76 Participants Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	Modular-Metal-Backed Knee n=76 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray)	All-Polyethylene Knee n=75 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Knee Society Function Score	69.2 units on a scale Standard Deviation 23.44	77.4 units on a scale Standard Deviation 23.44	69.7 units on a scale Standard Deviation 26.09

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome measures
Measure	Mobile-Bearing Knee n=76 Participants Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	Modular-Metal-Backed Knee n=76 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray)	All-Polyethylene Knee n=75 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Knee Society Pain Score	87.8 units on a scale Standard Deviation 12.17	88.7 units on a scale Standard Deviation 9.93	88.3 units on a scale Standard Deviation 11.58

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome measures
Measure	Mobile-Bearing Knee n=76 Participants Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	Modular-Metal-Backed Knee n=76 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray)	All-Polyethylene Knee n=75 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Knee Society Stair Climbing Score Two years post-surgery	39 units on a scale Interval 0.0 to 50.0	40 units on a scale Interval 0.0 to 50.0	39 units on a scale Interval 0.0 to 50.0
Knee Society Stair Climbing Score Five years post-surgery	36 units on a scale Interval 0.0 to 50.0	40 units on a scale Interval 0.0 to 50.0	37 units on a scale Interval 0.0 to 50.0

SECONDARY outcome

Timeframe: 5 years post-surgery

Kaplan-Meier analysis of five-year implant survival rate

Outcome measures

Outcome measures
Measure	Mobile-Bearing Knee n=76 Participants Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	Modular-Metal-Backed Knee n=76 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray)	All-Polyethylene Knee n=75 Participants Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Percentage of Knees Surviving at 5 Years With revision for any reason as end point	98.7 percentage of knees	97.4 percentage of knees	98.7 percentage of knees
Percentage of Knees Surviving at 5 Years With revision for aseptic loosening as end point	100 percentage of knees	97.4 percentage of knees	98.7 percentage of knees

Adverse Events

Mobile-Bearing Knee

Serious events: 0 serious events

Other events: 5 other events

Deaths: 0 deaths

Modular-Metal-Backed Knee

Serious events: 0 serious events

Other events: 4 other events

Deaths: 0 deaths

All-Polyethylene Knee

Serious events: 0 serious events

Other events: 2 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Other adverse events
Measure	Mobile-Bearing Knee n=76 participants at risk Sigma Knee System (mobile-bearing knee with the P.S. polyethylene insert)	Modular-Metal-Backed Knee n=76 participants at risk Sigma Pressfit Condylar Posterior Cruciate Substituting System with a metal back tibial tray (fixed-bearing knee with the metal backed tray)	All-Polyethylene Knee n=75 participants at risk Sigma Pressfit Condylar Posterior Cruciate Substituting System all polyethylene tray
Musculoskeletal and connective tissue disorders Aseptic loosening	0.00% 0/76 • Adverse events were collected for the 5 years that the subjects were on the study.	2.6% 2/76 • Number of events 2 • Adverse events were collected for the 5 years that the subjects were on the study.	1.3% 1/75 • Number of events 1 • Adverse events were collected for the 5 years that the subjects were on the study.
Musculoskeletal and connective tissue disorders Infection	1.3% 1/76 • Number of events 1 • Adverse events were collected for the 5 years that the subjects were on the study.	0.00% 0/76 • Adverse events were collected for the 5 years that the subjects were on the study.	0.00% 0/75 • Adverse events were collected for the 5 years that the subjects were on the study.
Musculoskeletal and connective tissue disorders Patellar crepitus	1.3% 1/76 • Number of events 1 • Adverse events were collected for the 5 years that the subjects were on the study.	0.00% 0/76 • Adverse events were collected for the 5 years that the subjects were on the study.	1.3% 1/75 • Number of events 1 • Adverse events were collected for the 5 years that the subjects were on the study.
Musculoskeletal and connective tissue disorders Knee stiffness	3.9% 3/76 • Number of events 3 • Adverse events were collected for the 5 years that the subjects were on the study.	2.6% 2/76 • Number of events 2 • Adverse events were collected for the 5 years that the subjects were on the study.	0.00% 0/75 • Adverse events were collected for the 5 years that the subjects were on the study.

Additional Information

Dr. Robert T. Trousdale

Mayo Clinic

Phone: 507-284-3663

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place