Arthroplasty, Replacement, Hip
Conditions
Brief summary
The primary objective of the study is to demonstrate the linear wear rates of the Trident® X3 polyethylene insert are superior to a polyethylene control group wear rate at 5 years postoperative. This measurement will be evaluated by comparing digitized images of serial radiographs obtained over a follow-up period of 5-years.
Detailed description
The study is a prospective, multi-center, historical-controlled clinical evaluation of the Trident® X3 Polyethylene insert. The device is commercially available in the United States where the study is being conducted. The study device, the Stryker Orthopaedics Trident® X3 polyethylene insert, is used for the replacement of the bearing surface of the acetabulum to relieve pain, instability, and the restriction of motion due to degenerative bone disease, including osteoarthritis, rheumatoid arthritis, trauma, or failure of other devices. The control device, the Stryker Orthopaedics N2VAC polyethylene insert, is also used for the replacement of the bearing surface of the acetabulum to relieve pain, instability, and the restriction of motion due to degenerative bone disease, including osteoarthritis, rheumatoid arthritis, trauma, or failure of other devices.
Interventions
DEVICETrident® X3 Polyethylene Insert
Trident® X3 Polyethylene Insert
Sponsors
Stryker Orthopaedics
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
21 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
1. The patient has signed an IRB-approved, study specific Patient Informed Consent Form. 2. The patient is a candidate for a primary total hip replacement with cementless acetabular and femoral components. 3. The patient has a primary diagnosis of Non-Inflammatory Degenerative Joint Disease (NIDJD). Patient must have diagnosis of osteoarthritis (OA), traumatic arthritis (TA), avascular necrosis (AVN), slipped capital epiphysis, pelvic fracture, femoral fracture, failed fracture fixation, or diastrophic variant. 4. The patient is a male or non-pregnant female patient ages 21 to 75. 5. The patient is willing and able to comply with postoperative scheduled clinical and radiographic evaluations and rehabilitation.
Exclusion criteria
1. The patient has an active infection with the affected hip joint. 2. The patient requires revision surgery of a previously implanted total hip arthroplasty or hip fusion to the affected joint. 3. The patient has a BMI \>45. 4. The patient has a neuromuscular or neurosensory deficiency, which limits ability to evaluate the safety and efficacy of the device. 5. The patient has diagnosed systemic disease (i.e. Paget's disease, renal osteodystrophy). 6. The patient is immunologically suppressed or receiving chronic steroids in excess of 5mg per day. 7. The patient has a recent history of substance dependency that may result in deviations from the evaluation schedule. 8. The patient is a prisoner.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Mean Linear Wear Rate at 5 Years | 5 years | Linear wear rates are defined as the annual rate of removal of the polyethylene from the polyethylene insert determined by comparing digitized images of serial radiographs obtained over the follow-up period of 5 years |
| Rate of Incidence of Revision of Component for Any Reason | 5 year | Revision of any component is defined as surgical removal and replacement of the femoral component, acetabular shell, acetabular insert and/or femoral head. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Radiographic Stability | 1,2,3,4 and 5 years | Radiographic stability is defined as having all of the following: no radiographic indication of progressive radiolucent lines greater than or equal to 2 mm around the entire acetabular cup, no radiographic indication of acetabular cup migration of greater than or equal to 3 mm, no radiographic indication of progressive radiolucent lines greater than or equal to 2 mm around the entire femoral component, and no radiographic indication of progressive subsidence of the femoral component of greater than or equal to 5 mm. Radiographs are evaluated at 1,2,3,4 and 5 years. |
| Mean Harris Hip Score (HHS) to Assess Change | pre-operative, 1,3 and 5 years | The change in HHS is reported by comparing the mean preoperative, 1, 3 and 5 year postoperative scores that assess pain, function, joint deformity and range of motion. Scores can range from 0 to 100 with 0 being the worst and 100 being the best score. A score of 80-100 is considered good-excellent and a score less than or equal to 79 is considered fair-poor. 90 - 100 = excellent 80 - 89 = good 70 - 79 = fair 0 - 69 = poor |
| Mean Harris Hip Score (HHS) Pain Score to Assess Change | pre-operative, 1,3, and 5 years | The change in HHS Pain is reported by comparing the mean preoperative, 1, 3 and 5 year postoperative pain scores. Scores can range from 0 to 44, with 0 indicating totally disabling pain and 44 indicating no pain or pain that is ignored. * None or ignores it = 44 points * Slight, occasional, no compromise in activities = 40 points * Mild pain, no effect on average activities, rarely moderate pain with unusual activity;may take aspirin = 30 points * Moderate pain, tolerable, but makes concessions to pain. Some limitation of ordinary activity or work. May require occasional pain medication stronger than aspirin = 20 points * Marked pain, serious limitation of activites = 10 points * Totally disabled, crippled, pain in bed, bedridden = 0 points |
| Linear Wear Rate of the Trident X3 Polyethylene Insert | 2, 3 and 4 year films collected; 3 and 4 year wear assessed | Linear wear rates are defined as the annual rate of removal of the polyethylene from the polyethylene insert determined by comparing digitized images of serial radiographs obtained over the follow-up period. NOTE: 2 year linear and volumetric wear was not calculated for the following reason: To determine polyethylene wear, the total femoral head penetration is first calculated from the radiographs.The femoral head penetration has two components namely wear and creep (or bedding-in). It is not possible to separate the total penetration in to two components. The creep of the polyethylene starts from the date of surgery and continues up to 12-24 months. Therefore, the head penetration value at 2-years is dominated by Creep rather than wear. |
| Mean SF-12 Health Survey Score to Assess Change | pre-operative, 1,3 and 5 years | Change in the SF-12 score is reported by comparing the mean preoperative, 1,3 and 5 year postoperative scores.The SF-12 Health Survey is a 12-item patient completed questionnaire to measure general health and well-being. It includes a physical and mental status component score; each ranging from 0-100. Low values represent a poor health state and high values represent a good health state. |
| Mean Lower Extremity Activity Scale (LEAS) Score to Assess Change | pre-operative, 1,3 and 5 years | Change in the LEAS is reported by comparing the mean preoperative, 1,3 and 5 year scores. The LEAS is completed by the participant to assess activity level. Activity levels are ordered in terms of intensity from 1 to 18, with 18 indicating the highest activity level. |
| Implant Survivorship | 10 years | Implant survivorship is determined using the Kaplan-Meier method. |
| Mean Harris Hip Score (HHS) Range of Motion (ROM) Score to Assess Change | pre-operative, 1,3 and 5 years | The change in HHS ROM is reported by comparing the mean preoperative, 1, 3 and 5 year postoperative scores. Scores can range from 0 (worst) to 5 (best). The degrees of motion are measured for hip flexion, abduction, adduction, external rotation and internal rotation. The measured values are added to determine a combined value that is associated with a score from 0 to 5. * 211-300 degrees = 5 points * 161 to 210 degrees = 4 points * 101 to 160 degrees = 3 points * 61 to 100 degrees = 2 points * 31 to 60 degrees = 1 points * 0 to 30 degrees = 0 points |
| Volumetric Wear Rate of the Trident X3 Polyethylene Insert | 2, 3, 4 and 5 year films collected; 3, 4 and 5 year wear assessed | Volumetric wear rate is calculated using a formula based on the cylindrical wear pattern perpendicular to the face of the cup and the mean linear wear rate. NOTE: 2 year linear and volumetric wear was not calculated for the following reason: To determine polyethylene wear, the total femoral head penetration is first calculated from the radiographs.The femoral head penetration has two components namely wear and creep (or bedding-in). It is not possible to separate the total penetration in to two components. The creep of the polyethylene starts from the date of surgery and continues up to 12-24 months. Therefore, the head penetration value at 2-years is dominated by Creep rather than wear. |
Countries
United States
Participant flow
Recruitment details
For bilateral hip replacement participants, if one hip completed primary endpoint #1 the participant is counted as completed. If one hip was censored, but the other hip was not, the hip is counted as censored, but the participant is not.
Pre-assignment details
250 participants/271 hips enrolled - 29 participants/31 hips censored= 221 participants/240 hips followed. There were 5 revisions, but one bilateral participant had one hip revised and the other hip completed the primary endpoint. This participant is counted as completed and not in the revision category.
Participants by arm
| Arm | Count |
|---|---|
| Trident® X3 Polyethylene Insert All subjects who recieved the Trident X3 insert. | 221 |
| Total | 221 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | Death | 4 |
| Overall Study | Inadequate 5 yr x-ray quality | 10 |
| Overall Study | Lost to Follow-up | 5 |
| Overall Study | No 5 yr x-rays | 56 |
| Overall Study | Revision of study device | 4 |
| Overall Study | Site termination | 11 |
| Overall Study | Unable/Unwilling to Return/Withdrawal | 21 |
Baseline characteristics
| Characteristic | Trident® X3 Polyethylene Insert |
|---|---|
| Age, Continuous | 62.04 years STANDARD_DEVIATION 8.74 |
| Region of Enrollment United States | 221 Participants |
| Sex: Female, Male Female | 116 Participants |
| Sex: Female, Male Male | 105 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 62 / 240 | 65 / 221 |
| serious Total, serious adverse events | 12 / 240 | 33 / 221 |
Outcome results
Primary
Mean Linear Wear Rate at 5 Years
Linear wear rates are defined as the annual rate of removal of the polyethylene from the polyethylene insert determined by comparing digitized images of serial radiographs obtained over the follow-up period of 5 years
Time frame: 5 years
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Trident® X3 Polyethylene Insert | Mean Linear Wear Rate at 5 Years | 0.016 mm/year | Standard Deviation 0.068 |
Primary
Rate of Incidence of Revision of Component for Any Reason
Revision of any component is defined as surgical removal and replacement of the femoral component, acetabular shell, acetabular insert and/or femoral head.
Time frame: 5 year
Population: Difference of 5 participants from the participant flow completed (=110): 4 participants are included in the revision category of the participant flow and one participant had revision of only the femoral head \& stem but later withdrew from the study \& is included in the withdrawal category of the participant flow.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Trident® X3 Polyethylene Insert | Rate of Incidence of Revision of Component for Any Reason | 4.84 percentage of hips undergoing revision |
Secondary
Implant Survivorship
Implant survivorship is determined using the Kaplan-Meier method.
Time frame: 10 years
Population: Participants with available data. The population includes all 240 cases who were initially consented to 5 year study.~There are 127 cases who consented to continue in the 10 year study.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Trident® X3 Polyethylene Insert | Implant Survivorship | Kaplan-Meier Estimate (based on 10 year cases) | 98.37 percentage of hips |
| Trident® X3 Polyethylene Insert | Implant Survivorship | Kaplan-Meier Estimate (based on 5 year cases) | 95.79 percentage of hips |
Secondary
Linear Wear Rate of the Trident X3 Polyethylene Insert
Linear wear rates are defined as the annual rate of removal of the polyethylene from the polyethylene insert determined by comparing digitized images of serial radiographs obtained over the follow-up period. NOTE: 2 year linear and volumetric wear was not calculated for the following reason: To determine polyethylene wear, the total femoral head penetration is first calculated from the radiographs.The femoral head penetration has two components namely wear and creep (or bedding-in). It is not possible to separate the total penetration in to two components. The creep of the polyethylene starts from the date of surgery and continues up to 12-24 months. Therefore, the head penetration value at 2-years is dominated by Creep rather than wear.
Time frame: 2, 3 and 4 year films collected; 3 and 4 year wear assessed
Population: Participants/hips with available data. Overall number of participants and units analyzed is based upon the 3 year population.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Trident® X3 Polyethylene Insert | Linear Wear Rate of the Trident X3 Polyethylene Insert | 3 year mean wear rate | 0.022 mm/year | Standard Deviation 0.133 |
| Trident® X3 Polyethylene Insert | Linear Wear Rate of the Trident X3 Polyethylene Insert | 4 year mean wear rate | 0.024 mm/year | Standard Deviation 0.087 |
Secondary
Mean Harris Hip Score (HHS) Pain Score to Assess Change
The change in HHS Pain is reported by comparing the mean preoperative, 1, 3 and 5 year postoperative pain scores. Scores can range from 0 to 44, with 0 indicating totally disabling pain and 44 indicating no pain or pain that is ignored. * None or ignores it = 44 points * Slight, occasional, no compromise in activities = 40 points * Mild pain, no effect on average activities, rarely moderate pain with unusual activity;may take aspirin = 30 points * Moderate pain, tolerable, but makes concessions to pain. Some limitation of ordinary activity or work. May require occasional pain medication stronger than aspirin = 20 points * Marked pain, serious limitation of activites = 10 points * Totally disabled, crippled, pain in bed, bedridden = 0 points
Time frame: pre-operative, 1,3, and 5 years
Population: Participants/hips with available data. Overall number of participants and units analyzed is based upon the preoperative population.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) Pain Score to Assess Change | HHS Pain Mean Preoperative Score | 16.73 units on a scale | Standard Deviation 8.24 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) Pain Score to Assess Change | HHS Pain Mean 1 Year Score | 41.52 units on a scale | Standard Deviation 5.64 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) Pain Score to Assess Change | HHS Pain Mean 3 Year Score | 42.50 units on a scale | Standard Deviation 4.89 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) Pain Score to Assess Change | HHS Pain Mean 5 Year Score | 41.75 units on a scale | Standard Deviation 5.99 |
Comparison: Change in Harris Hip Pain Score from pre-op to 1 yearp-value: <0.0001Sign test
Comparison: Change in Harris Hip Pain Score from pre-op to 3 yearsp-value: <0.0001Sign test
Comparison: Change in Harris Hip Pain Score from pre-op to 5 yearsp-value: <0.0001Sign test
Secondary
Mean Harris Hip Score (HHS) Range of Motion (ROM) Score to Assess Change
The change in HHS ROM is reported by comparing the mean preoperative, 1, 3 and 5 year postoperative scores. Scores can range from 0 (worst) to 5 (best). The degrees of motion are measured for hip flexion, abduction, adduction, external rotation and internal rotation. The measured values are added to determine a combined value that is associated with a score from 0 to 5. * 211-300 degrees = 5 points * 161 to 210 degrees = 4 points * 101 to 160 degrees = 3 points * 61 to 100 degrees = 2 points * 31 to 60 degrees = 1 points * 0 to 30 degrees = 0 points
Time frame: pre-operative, 1,3 and 5 years
Population: Participants/hips with available data. Overall number of participants and units analyzed is based upon the preoperative population.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) Range of Motion (ROM) Score to Assess Change | HHS ROM Mean Preoperative Score | 3.90 units on a scale | Standard Deviation 0.95 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) Range of Motion (ROM) Score to Assess Change | HHS ROM Mean 1 Year Score | 4.99 units on a scale | Standard Deviation 0.12 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) Range of Motion (ROM) Score to Assess Change | HHS ROM Mean 3 Year Score | 4.99 units on a scale | Standard Deviation 0.11 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) Range of Motion (ROM) Score to Assess Change | HHS ROM Mean 5 Year Score | 4.93 units on a scale | Standard Deviation 0.31 |
Comparison: Change in Harris Hip ROM score from pre-op to 1 yearp-value: <0.0001Sign test
Comparison: Change in Harris Hip ROM score from pre-op to 3 yearsp-value: <0.0001Sign test
Comparison: Change in Harris Hip ROM score from pre-op to 5 yearsp-value: <0.0001Sign test
Secondary
Mean Harris Hip Score (HHS) to Assess Change
The change in HHS is reported by comparing the mean preoperative, 1, 3 and 5 year postoperative scores that assess pain, function, joint deformity and range of motion. Scores can range from 0 to 100 with 0 being the worst and 100 being the best score. A score of 80-100 is considered good-excellent and a score less than or equal to 79 is considered fair-poor. 90 - 100 = excellent 80 - 89 = good 70 - 79 = fair 0 - 69 = poor
Time frame: pre-operative, 1,3 and 5 years
Population: Participants/hips with available data. Overall number of participants and units analyzed is based upon the preoperative population.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) to Assess Change | HHS Mean 1 Year Score | 94.41 units on a scale | Standard Deviation 8.75 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) to Assess Change | HHS Mean 3 Year Score | 95.32 units on a scale | Standard Deviation 8.32 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) to Assess Change | HHS Mean 5 year Score | 94.05 units on a scale | Standard Deviation 8.7 |
| Trident® X3 Polyethylene Insert | Mean Harris Hip Score (HHS) to Assess Change | HHS Mean Preoperative Score | 53.01 units on a scale | Standard Deviation 13.68 |
Comparison: Change in HHS from pre-op to 1 yearp-value: <0.0001Sign test
Comparison: Change in HHS from pre-op to 3 yearsp-value: <0.0001Sign test
Comparison: Change in HHS from pre-op to 5 yearsp-value: <0.0001t-test, 2 sided
Secondary
Mean Lower Extremity Activity Scale (LEAS) Score to Assess Change
Change in the LEAS is reported by comparing the mean preoperative, 1,3 and 5 year scores. The LEAS is completed by the participant to assess activity level. Activity levels are ordered in terms of intensity from 1 to 18, with 18 indicating the highest activity level.
Time frame: pre-operative, 1,3 and 5 years
Population: Participants/hips with available data. Overall number of participants and units analyzed is based upon the preoperative population.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Trident® X3 Polyethylene Insert | Mean Lower Extremity Activity Scale (LEAS) Score to Assess Change | Mean LEAS score Preoperative | 8.95 units on a scale | Standard Deviation 2.54 |
| Trident® X3 Polyethylene Insert | Mean Lower Extremity Activity Scale (LEAS) Score to Assess Change | Mean LEAS score 1 year | 11.65 units on a scale | Standard Deviation 3.01 |
| Trident® X3 Polyethylene Insert | Mean Lower Extremity Activity Scale (LEAS) Score to Assess Change | Mean LEAS score 3 years | 11.69 units on a scale | Standard Deviation 2.95 |
| Trident® X3 Polyethylene Insert | Mean Lower Extremity Activity Scale (LEAS) Score to Assess Change | Mean LEAS score 5 years | 10.92 units on a scale | Standard Deviation 2.92 |
Comparison: Change in LEAS Score from preop to 1 yearp-value: <0.0001Sign test
Comparison: Change in LEAS Score from preop to 3 yearp-value: <0.0001Sign test
Comparison: Change in LEAS Score from preop to 5 yearp-value: <0.0001t-test, 2 sided
Secondary
Mean SF-12 Health Survey Score to Assess Change
Change in the SF-12 score is reported by comparing the mean preoperative, 1,3 and 5 year postoperative scores.The SF-12 Health Survey is a 12-item patient completed questionnaire to measure general health and well-being. It includes a physical and mental status component score; each ranging from 0-100. Low values represent a poor health state and high values represent a good health state.
Time frame: pre-operative, 1,3 and 5 years
Population: Participants/hips with available data. Overall number of participants and units analyzed is based upon the preoperative population.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Trident® X3 Polyethylene Insert | Mean SF-12 Health Survey Score to Assess Change | Mean SF-12 Physical Score Preoperative | 32.11 units on a scale | Standard Deviation 8.86 |
| Trident® X3 Polyethylene Insert | Mean SF-12 Health Survey Score to Assess Change | Mean SF-12 Physical Score 1 year | 49.90 units on a scale | Standard Deviation 8.51 |
| Trident® X3 Polyethylene Insert | Mean SF-12 Health Survey Score to Assess Change | Mean SF-12 Physical Score 3 years | 49.97 units on a scale | Standard Deviation 8.74 |
| Trident® X3 Polyethylene Insert | Mean SF-12 Health Survey Score to Assess Change | Mean SF-12 Physical Score 5 years | 49.08 units on a scale | Standard Deviation 8.38 |
| Trident® X3 Polyethylene Insert | Mean SF-12 Health Survey Score to Assess Change | Mean SF-12 Mental Score Preoperative | 53.75 units on a scale | Standard Deviation 10.91 |
| Trident® X3 Polyethylene Insert | Mean SF-12 Health Survey Score to Assess Change | Mean SF-12 Mental Score 1 year | 55.72 units on a scale | Standard Deviation 7.83 |
| Trident® X3 Polyethylene Insert | Mean SF-12 Health Survey Score to Assess Change | Mean SF-12 Mental Score 3 years | 55.78 units on a scale | Standard Deviation 8.13 |
| Trident® X3 Polyethylene Insert | Mean SF-12 Health Survey Score to Assess Change | Mean SF-12 Mental Score 5 years | 54.88 units on a scale | Standard Deviation 7.76 |
Comparison: Change in SF-12 Phyiscal Component Score from preop to 1 yearp-value: <0.0001Sign test
Comparison: Change in SF-12 Phyiscal Component Score from preop to 3 yearp-value: <0.0001t-test, 2 sided
Comparison: Change in SF-12 Phyiscal Component Score from preop to 5 yearp-value: <0.0001Sign test
Comparison: Change in SF-12 Mental Component Score from preop to 1 yearp-value: 0.0242Sign test
Comparison: Change in SF-12 Mental Component Score from preop to 3 yearp-value: 0.0247Sign test
Comparison: Change in SF-12 Mental Component Score from preop to 5 yearp-value: 0.1372Sign test
Secondary
Radiographic Stability
Radiographic stability is defined as having all of the following: no radiographic indication of progressive radiolucent lines greater than or equal to 2 mm around the entire acetabular cup, no radiographic indication of acetabular cup migration of greater than or equal to 3 mm, no radiographic indication of progressive radiolucent lines greater than or equal to 2 mm around the entire femoral component, and no radiographic indication of progressive subsidence of the femoral component of greater than or equal to 5 mm. Radiographs are evaluated at 1,2,3,4 and 5 years.
Time frame: 1,2,3,4 and 5 years
Population: Participants/hips with available data. Overall number of participants and units analyzed is based upon the 1 year population.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Trident® X3 Polyethylene Insert | Radiographic Stability | Radiographically unstable at 1 year | 0 hips evaluated as unstable on radiograph |
| Trident® X3 Polyethylene Insert | Radiographic Stability | Radiographically unstable at 2 years | 0 hips evaluated as unstable on radiograph |
| Trident® X3 Polyethylene Insert | Radiographic Stability | Radiographically unstable at 3 years | 0 hips evaluated as unstable on radiograph |
| Trident® X3 Polyethylene Insert | Radiographic Stability | Radiographically unstable at 4 years | 0 hips evaluated as unstable on radiograph |
| Trident® X3 Polyethylene Insert | Radiographic Stability | Radiographically unstable at 5 years | 0 hips evaluated as unstable on radiograph |
Secondary
Volumetric Wear Rate of the Trident X3 Polyethylene Insert
Volumetric wear rate is calculated using a formula based on the cylindrical wear pattern perpendicular to the face of the cup and the mean linear wear rate. NOTE: 2 year linear and volumetric wear was not calculated for the following reason: To determine polyethylene wear, the total femoral head penetration is first calculated from the radiographs.The femoral head penetration has two components namely wear and creep (or bedding-in). It is not possible to separate the total penetration in to two components. The creep of the polyethylene starts from the date of surgery and continues up to 12-24 months. Therefore, the head penetration value at 2-years is dominated by Creep rather than wear.
Time frame: 2, 3, 4 and 5 year films collected; 3, 4 and 5 year wear assessed
Population: Participants/hips with available data. Overall number of participants and units analyzed is based upon the 3 year population.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Trident® X3 Polyethylene Insert | Volumetric Wear Rate of the Trident X3 Polyethylene Insert | 3 year volumetric wear rate | 17.9 cubic mm/year |
| Trident® X3 Polyethylene Insert | Volumetric Wear Rate of the Trident X3 Polyethylene Insert | 4 year volumetric wear rate | 19.1 cubic mm/year |
| Trident® X3 Polyethylene Insert | Volumetric Wear Rate of the Trident X3 Polyethylene Insert | 5 year volumetric wear rate | 13.3 cubic mm/year |