A Study to Compare the NexGen CR and CR-Flex Knee Implants

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00761956
Recruitment Status : Completed
First Posted : September 30, 2008
Results First Posted : July 16, 2012
Last Update Posted : July 16, 2012
Information provided by (Responsible Party):
Zimmer Biomet

Brief Summary:
The purpose of this study is to test for significant differences in functional outcomes, specifically pre-operative ROM and post-operative ROM obtained by using a NexGen CR versus a NexGen CR-Flex knee implant. Specifically, it is predicted that an increase in post-operative range of motion will be experienced by patients treated with the NexGen CR-Flex knee implant.

Condition or disease Intervention/treatment
Total Knee Arthroplasty Osteoarthritis Device: NexGen CR-Flex Fixed Bearing Knee Device: NexGen CR Knee

Detailed Description:
This study will compare the clinical results of the NexGen CR femoral component with the higher flexion potential of the NexGen CR-Flex femoral component in all patients with degenerative joint disease that require total knee arthroplasty. The primary variable of interest is post-operative range of motion achieved with the two devices, which are implanted with slightly different surgical techniques in patients who may also be subjected to different rehabilitation programs depending on the device they are assigned.

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 189 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single (Participant)
Primary Purpose: Treatment
Official Title: Prospective Randomized Multicenter Study of NexGen CR-Flex Knee
Study Start Date : September 2004
Primary Completion Date : December 2010
Study Completion Date : December 2010

Resource links provided by the National Library of Medicine

U.S. FDA Resources

Arm Intervention/treatment
Active Comparator: 1
Study arm will consist of patients that are treated with the NexGen CR-Flex Fixed Bearing Knee.
Device: NexGen CR-Flex Fixed Bearing Knee
NexGen CR-Flex Fixed Bearing femoral component
Other Name: CR-Flex Knee
Active Comparator: 2
Study arm will consist of patients that are treated with the NexGen CR Knee.
Device: NexGen CR Knee
NexGen Complete Knee Solution Cruciate Retaining femoral component
Other Name: CR Knee

Primary Outcome Measures :
  1. Postoperative Range of Motion (ROM) [ Time Frame: 24 Months ]
    The subject will have the operative joint's range of motion/movement assessed through a series of exercises and bends. The assessor will measure how far the joint bends/moves in each direction by degrees. The measurements are taken at each visit interval and recorded.

Secondary Outcome Measures :
  1. Return to Function (RtF) Via Knee Scoiety Score (Modified) [ Time Frame: 24 Months ]

    Scores were calculated from responses on a modified Knee Society Score by the enrolled subjects for the stated visit intervals.

    Grading for the Knee Society Score is based on a scale from 0-100 and results are estabalished follows: 80-100 = Excellent; 70-79 = Good; 60-69 = Fair; and Below 60 = Poor.

Information from the National Library of Medicine

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Ages Eligible for Study:   21 Years to 80 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Age, 21-80 years
  • Sex, Male and Females will be included
  • BMI less than or equal to 39
  • Stable Health, the patient would be able to undergo surgery and participate in a follow-up program based on physical examination and medical history.
  • Patient is willing and able to cooperate in follow-up therapy.
  • Patient exhibits pre-operative radiographic evidenced of joint degeneration consistent with TKA that cannot be treated in non-operative fashion.
  • Patient has stable and functional posterior cruciate and collateral ligaments.
  • Patient has potential to perform higher than average range of motion activities.
  • Operative side range of motion flexion greater than or equal to 120 degrees.
  • Severe knee pain and disability due to degenerative joint disease.
  • Patient or patient's legal representative has signed the Informed Consent form.

Exclusion Criteria:

  • Previous history of infection in the affected joint.
  • Previously failed knee endoprosthesis of any kind.
  • Charcot joint disease or other severe neurosensory deficits.
  • Previous patellectomy
  • Patient is skeletally immature.
  • Grossly insufficient femoral or tibial bone stock.
  • Patient is pregnant.
  • Varus or valgus deformity greater than 20 degrees.
  • Fixed flexion deformity greater than 15 degrees.
  • Previous high tibial osteotomy.
  • Previous femoral osteotomy.
  • Patient is a poor compliance risk, currently treated for ethanol or drug abuse, physical or mental handicap, etc.
  • Loss of musculature or absence of musculoligamentous supporting structures required for adequate soft tissue balance.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00761956

United States, Delaware
Dickinson Medical Group, LLC
Milford, Delaware, United States, 19963
United States, Illinois
University of Chicago Hospital
Chicago, Illinois, United States, 60637
Rockford Orthopedic Associates
Rockford, Illinois, United States, 61107
United States, Massachusetts
University of Massachusetts Memorial Medical Center
Worcester, Massachusetts, United States, 01605
United States, Michigan
Orthopaedic Associates of Grand Rapids, PC
Grand Rapids, Michigan, United States, 49525
United States, North Carolina
Pinehurst Surgical Center
Pinehurst, North Carolina, United States, 28374
United States, Oregon
Slocum Orthopedics, PC
Eugene, Oregon, United States, 97401
United States, Pennsylvania
The Orthopedic Group
Clairton, Pennsylvania, United States, 15025
Sponsors and Collaborators
Zimmer Biomet

Responsible Party: Zimmer Biomet Identifier: NCT00761956     History of Changes
Other Study ID Numbers: 04-300
First Posted: September 30, 2008    Key Record Dates
Results First Posted: July 16, 2012
Last Update Posted: July 16, 2012
Last Verified: June 2012

Keywords provided by Zimmer Biomet:
Total Knee Arthroplasty

Additional relevant MeSH terms:
Joint Diseases
Musculoskeletal Diseases
Rheumatic Diseases