Sigma CR150 Versus Sigma CR Knee RCT

Study Overview
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Brief Summary
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This study will compare two very similar designs of knee replacement device. One device (Sigma CR150) is a slightly modified version of the original (Sigma CR) and has been modified to enhance/accommodate higher flexion. The original device has been in widespread clinical use with excellent results since 1996 and this study will determine whether the design modifications of the newer device add further value. The newer device has been in clinical use with good short-term(unpublished) outcomes since becoming commercially available in January 2009. Achieving higher knee flexion may be required for cultural reasons or by the increasingly younger, more active patient population undergoing knee replacement today. In addition to promoting flexion, it is also possible that this design change may help the knee replacement to last longer than traditional implants in patients who achieve higher flexion. Therefore, the study will compare the two devices in terms of survivorship, flexion and other measures of the success of a total knee replacement (range of motion, knee-related quality of life, activity and generic quality of life) over the short-term. A minimum of one hundred and forty subjects (minimum 70 per group) with osteoarthritis and aged 50-75 years will be included at UK/international hospitals. Study duration is 2 years and patients will complete standard knee outcome scores plus radiological evaluation. Subjects would receive one of the study devices regardless of their involvement in the study, and apart from (possible)additional visits, x-rays and/or questionnaires, treatment and follow-up care will be as per the care they would receive outside of the study.

Official Title
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A Double-blinded Randomised Controlled Trial Comparing the Performance of the Sigma® CR150 and Sigma® CR Knee Systems, When Used in Fixed Bearing Primary Cruciate Retaining Total Knee Arthroplasty for the Treatment of Osteoarthritis

Conditions
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Osteoarthritis

Intervention / Treatment
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* Device: Sigma CR150
* Device: Sigma CR


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: i)Male or female subjects, aged between 50 and 75 years inclusive. ii)Subjects who are able to give voluntary, written informed consent to participate in this clinical investigation and from whom consent has been obtained. iii) Subjects who, in the opinion of the Clinical Investigator, are able to understand this clinical investigation, co-operate with the investigational procedures and are willing to return to the hospital for all the required post-operative follow-ups. iv) Subjects defined by the Investigator as ASA Grade I or II. v) Subjects with a primary diagnosis of osteoarthritis. vi) Subjects who require a primary total knee arthroplasty. vii) Subjects who can achieve active flexion of 90 degrees. Exclusion Criteria: i) Subjects who, in the opinion of the Clinical Investigator, have an existing condition that would compromise their participation and follow-up in this clinical investigation. ii) Subjects who are known drug or alcohol abusers or with psychological disorders that could affect follow-up care or treatment outcomes. iii) Subjects who have participated in a clinical investigation with an investigational product in the last month. iv) Subjects who are currently involved in any injury litigation claims. v) Subjects with an anatomical limb alignment of above 20 degrees varus or valgus. vi) Subjects with a fixed flexion deformity of over 20 degrees. vii) Subjects with recurvatum (definition: hyperextension ≥ 5 degrees). viii) Subjects who cannot flex their hip to 90 degrees. ix) Subjects with a BMI of 35 or above. x) Subjects defined by the Investigator as ASA Grade III-V. xi) Subjects who are identified pre-operatively as having bone defects which require augmentation. xii) Subjects who have previously undergone total or unicondylar knee arthroplasty, high tibial osteotomy, ligament reconstruction, ORIF or with previous fracture in the knee joint. xiii) Subjects with primary or secondary diagnosis of inflammatory or traumatic arthritis. xiv) Subjects who have undergone contralateral total knee arthroplasty during the previous 6 months. xv) Subjects who in the opinion of the Investigator require patellar resurfacing. Intra-operative exclusion criteria: i) Subjects who have uncontained bone defects or defects bigger than 8 mm3 and/or require augmentation. ii) Subjects who are not suitable to receive both the study and comparator devices. iii) Subjects who require patellar resurfacing

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Sigma CR150<br>Sigma CR150 femoral component used in combination with the Highly Polished Cobalt Chrome fixed bearing tibial tray and the Curved (XLK) polyethylene bearing (cemented, no patellar resurfacing). | Device: Sigma CR150<br>* Sigma CR150 femoral component used in combination with the Highly Polished Cobalt Chrome fixed bearing tibial tray and the Curved (XLK) polyethylene bearing (cemented, no patellar resurfacing).<br>* Other names: PFC Sigma CR150;|
| Active Comparator: Sigma CR<br>Sigma CR femoral component used in combination with the Highly Polished Cobalt Chrome fixed bearing tibial tray and the Curved (XLK) polyethylene bearing (cemented, no patellar resurfacing). | Device: Sigma CR<br>* Sigma CR femoral component used in combination with the Highly Polished Cobalt Chrome fixed bearing tibial tray and the Curved (XLK) polyethylene bearing (cemented, no patellar resurfacing).<br>* Other names: PFC Sigma CR;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Knees Who Survived at 2 Years Post-operative | The Kaplan-Meier success rate at 24-months post-operatively was calculated with Kaplan-Meier time-to-event methodology, where the time variable for patients who were successful (no components revised for any reason) was censored at the time of last follow-up. | 2 Years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline in Goniometer Measured Maximum Passive Flexion at 2 Years | Comparative evaluation of the change from baseline values in 2 year goniometer-measured passive flexion. A goniometer is an instrument used to measure angles in degrees and captures the change in angle between the upper and lower leg | Pre-operative baseline to 2 years | 
| Knee Injury and Osteoarthritis Outcome Pain Subscore - 1 Year | Comparative evaluation of the change from baseline values at 1 years in Knee Injury and Osteoarthritis Outcome Pain Subscore The subscore ranges from 0 (no pain) to 36 (extreme pain). The subscore is then transformed into a 0 (extreme pain) to 100 (no pain) scale. 100 - (score x 100) / 36 = transformed score | Pre-operative baseline to 1 year | 
| Knee Injury and Osteoarthritis Outcome Pain Subscore - 2 Years | Comparative evaluation of the change from baseline values at 2 years in Knee Injury and Osteoarthritis Outcome Pain Subscore The subscore ranges from 0 (no pain) to 36 (extreme pain). The subscore is then transformed into a 0 (extreme pain) to 100 (no pain) scale. 100 - (score x 100) / 36 = transformed score | 2 years | 
| Knee Injury and Osteoarthritis Outcome Symptoms Subscore - 1 Years | Comparative evaluation of the change from baseline values at 1 year in Knee Injury and Osteoarthritis Outcome Symptom Subscore The subscore ranges from 0 (no symptoms) to 36 (always have symptoms). The subscore is then transformed into a 0 (always have symptoms) to 100 (never have symptoms) scale. 100 - (score x 100) / 36 = transformed score | 1 years | 
| Knee Injury and Osteoarthritis Outcome Symptom Subscore - 2 Years | Comparative evaluation of the change from baseline values at 2 years in Knee Injury and Osteoarthritis Outcome Symptom Subscore The subscore ranges from 0 (never have symptoms) to 28 (always have symptoms). The subscore is then transformed into a 0 (always have symptoms) to 100 (never have symptoms) scale. 100 - (score x 100) / 28 = transformed score | 2 years | 
| Knee Injury and Osteoarthritis Outcome - Activities of Daily Living Subscore - 1 Years | Comparative evaluation of the change from baseline values at 1 years in Knee Injury and Osteoarthritis Outcome Symptom Subscore The subscore ranges from 0 (no difficulty) to 68 (extreme difficulty). The subscore is then transformed into a 0 (extreme difficulty) to 100 (no difficulty) scale. 100 - (score x 100) / 68 = transformed score | 1 year | 
| Knee Injury and Osteoarthritis Outcome - Activities of Daily Living Subscore - 2 Years | Comparative evaluation of the change from baseline values at 2 years in Knee Injury and Osteoarthritis Outcome Activities of Daily Living Subscore The subscore ranges from 0 (no difficulty) to 68 (extreme difficulty). The subscore is then transformed into a 0 (extreme difficulty) to 100 (no difficulty) scale. 100 - (score x 100) / 68 = transformed score | 2 year | 
| Knee Injury and Osteoarthritis Outcome - Sport and Recreation Subscore - 1 Years | Comparative evaluation of the change from baseline values at 1 years in Knee Injury and Osteoarthritis Outcome Activities of Daily Living Subscore The subscore ranges from 0 (no difficulty) to 20 (extreme difficulty). The subscore is then transformed into a 0 (extreme difficulty) to 100 (no difficulty) scale. 100 - (score x 100) / 20 = transformed score | 1 year | 
| Knee Injury and Osteoarthritis Outcome Sport and Recreation Subscore - 2 Years | Comparative evaluation of the change from baseline values at 2 years in Knee Injury and Osteoarthritis Outcome Activities of Daily Living Subscore The subscore ranges from 0 (no difficulty) to 20 (extreme difficulty). The subscore is then transformed into a 0 (extreme difficulty) to 100 (no difficulty) scale. 100 - (score x 100) / 20 = transformed score | 2 year | 
| Knee Injury and Osteoarthritis Outcome - Quality of Life Subscore - 1 Years | Comparative evaluation of the change from baseline values at 1 years in Knee Injury and Osteoarthritis Outcome Activities of Quality of life Subscore The subscore ranges from 0 (no difficulty) to 16 (extreme difficulty). The subscore is then transformed into a 0 (extreme difficulty) to 100 (no difficulty) scale. 100 - (score x 100) / 16 = transformed score | 1 year | 
| Knee Injury and Osteoarthritis Outcome - Quality of Life Subscore - 2 Years | Comparative evaluation of the change from baseline values at 2 years in Knee Injury and Osteoarthritis Outcome Quality of Life Subscore The subscore ranges from 0 (no difficulty) to 16 (extreme difficulty). The subscore is then transformed into a 0 (extreme difficulty) to 100 (no difficulty) scale. 100 - (score x 100) / 16 = transformed score | 2 years | 
| Change From Baseline in Goniometer Measured Maximum Passive Flexion at 1 Year. | Comparative evaluation of the change from baseline values in 1 year goniometer-measured passive Flexion. A goniometer is an instrument used to measure angles in degrees and captures the change in angle between the upper and lower leg. Passive flexion involves moving the leg through range of motion without active muscle contraction | 1 year | 
| Change From Baseline in Goniometer Measured Maximum Passive Extension at 1 Year | Comparative evaluation of the change from baseline values in 1 year goniometer-measured passive extension. A goniometer is an instrument used to measure angles in degrees and captures the change in angle between the upper and lower leg. Passive extension involves the leg being moved without active muscle contraction | 1 year | 
| Change From Baseline in Goniometer Measured Maximum Passive Extension at 2 Years | Comparative evaluation of the change from baseline values in 2 year goniometer-measured passive extension. A goniometer is an instrument used to measure angles in degrees and captures the change in angle between the upper and lower leg. Passive extension involves moving the leg without active muscle contraction | 2 year | 
| Change From Baseline in Goniometer Measured Maximum Total Range of Motion at 1 Year | Comparative evaluation of the change from baseline values in 1 year goniometer-measured total range of motion. A goniometer is an instrument used to measure angles in degrees and captures the change in angle between the upper and lower leg. Total range of motion is the full distance the lower leg travels in relation to the upper leg. | 1 year | 
| Change From Baseline in Goniometer Measured Maximum Total Range of Motion at 2 Years. | Comparative evaluation of the change from baseline values in 2 year goniometer-measured total range of motion. A goniometer is an instrument used to measure angles in degrees and captures the change in angle between the upper and lower leg. Total range of motion is the full distance the lower leg travels in relation to the upper leg. | 2 years | 
| Number of Participants With Flexion Contracture at 1 Year | Summary of flexion contracture at 1 year time point. Flexion contracture is a shortening of the muscles that prevents the leg from fully extending | 1 years | 
| Number of Participants With Flexion Contracture at 2 Years | Summary of flexion contracture at 2 year time point.Flexion contracture is a shortening of the muscles that prevents the leg from fully extending | 2 years | 
| Total Knee Society Score at 1 Year | Total Knee Society Knee Score change from baseline at 1 year The Total Knee Society Score is comprised of two scores: the Knee Score and the Function Score. Both have a 0-100 range. Sub-scales are combined to compute a total score of 100 The Total Knee Society Score is made up of pain, range of motion, alignment and stability subscores. An Excellent score is 80-100, a good score is 70-79, a fair score is 60-69 and a poor score is anything below 60. | 1 year | 
| Total Knee Society Knee Score at 2 Years | Total Knee Society Knee Score change from baseline at 2 years The Total Knee Society Score is comprised of two scores: the Knee Score and the Function Score. Both have a 0-100 range. Sub-scales are combined to compute a total score of 100 The Total Knee Society Score is made up of pain, range of motion, alignment and stability subscores. An Excellent score is 80-100, a good score is 70-79, a fair score is 60-69 and a poor score is anything below 60. | 2 years | 
| Anatomic Alignment Angle | Anatomic angle measured at 1 year time point. If one draws a line from the center of the hip joint to the center of the ankle joint this is considered to be the mechanical axis of the femur. A line drawn through the center of the femoral shaft is the anatomic axis. The angle created at the intersection of these lines is referred to as the anatomic alignment angle. A normal angle is approximately 7-9 degrees valgus or slightly knock-kneed. Varus angles are less common and are also referred to as bow-legged. | 1 year time point | 
| Anatomic Alignment Angle | Anatomic angle measured at 2 year time point. If one draws a line from the center of the hip joint to the center of the ankle joint this is considered to be the mechanical axis of the femur. A line drawn through the center of the femoral shaft is the anatomic axis. The angle created at the intersection of these lines is referred to as the anatomic alignment angle. A normal angle is approximately 7-9 degrees valgus or slightly knock-kneed. Varus angles are less common and are also referred to as bow-legged. | 2 year time point | 
| Alignment - Femoral Component to Anatomic Angle. | Femoral component angle measured at 1 year time point. This angle is measured between a line drawn from the center of the femoral head and a line across the bottom of the femoral implant (condyles). | 1 year time point | 
| Alignment - Femoral Component to Anatomic Angle | Femoral component angle measured at 2 year time point. This angle is measured between a line drawn from the center of the femoral head and a line across the bottom of the femoral implant (condyles). | 2 year time point | 
| Alignment - Tibial Component to Anatomic Angle | Tibial component angle measured at 1 year time point. This angle is measured between a line drawn from the center of the femoral head tibial implant. | 1 year time point | 
| Alignment - Tibial Component to Anatomic Angle | Tibial component angle measured at 2 year time point. This angle is measured between a line drawn from the center of the femoral head tibial implant. | 2 year time point | 
| Alignment - Femoral Component Flexion | Femoral Component Flexion measured at 1 year time point. This measures the angle between a line drawn though the center of the side of the femur and a line drawn across the top of the flat inner surface of the femoral component. | 1 year time point | 
| Alignment - Femoral Component Flexion | Alignment - Femoral Component Flexion measured at 2 year time point. This measures the angle between a line drawn though the center of the side of the femur and a line drawn across the top of the flat inner surface of the femoral component. | 2 year time point | 
| Alignment - Tibial Posterior Slope | Tibial Posterior Slope measured at 1 year time point. This angle is measured between a line through the center of the side of the tibia and the top flat surface of the tibial implant | 1 year time point | 
| Alignment - Tibial Posterior Slope | Alignment - Tibial Posterior Slope measured at 2 year time point. This angle is measured between a line through the center of the side of the tibia and the top flat surface of the tibial implant | 2 year time point | 
| Number of Subjects With Radiolucencies - Femoral Component | The bone-implant interface at the femoral components were examined radiographically and radiolucencies were measured in millimeters. Radiolucent lines (RLLs) greater than 2mm are considered to be clinically significant. | 6 to 12 week and 24 month intervals | 
| Number of Subjects With Radiolucencies - Tibial Component | The bone-implant interface at the tibial components were examined radiographically and radiolucencies were measured in millimeters. Radiolucent lines (RLLs) greater than 2mm are considered to be clinically significant. Radiolucent lines greater than 2mm are considered to be clinically significant. | 6 weeks to 24 months | 
| Radiographic Evaluation of Maximum Flexion | Maximum knee flexion measured radiographically at 1 year time point | 1 year time point | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Sigma, cruciate, retaining, fixed, primary, total, knee, arthroplasty, cemented, osteoarthritis