Clinical trial NCT01481896: A Five-Year Metal-on-Metal Retrospective Clinical Study
Official title: A Five-Year Metal-on-Metal Retrospective Clinical Study
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Osteoarthritis
Keywords: Hip replacement
Metal-on-metal bearings
Osteolysis
Metal ion levels
Outcome
Lead sponsor: Anderson Orthopaedic Research Institute
Sponsor class: OTHER
Collaborators: name: DePuy Orthopaedics
First posted: 2011-11-30
Enrollment: 126
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: RETROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: A consecutive series of patients who had primary total hip arthroplasties performed at the Anderson Clinic using DePuy Pinnacle cups, Ultamet metal liners and 36-mm cobalt-chromium alloy femoral heads.

Brief summary: This retrospective study will review the Anderson Orthopaedic Institute's initial experience among a consecutive series of 126 patients who had primary total hip arthroplasty using a metal-on-metal articulation consisting of a DePuy Pinnacle cup with an Ultamet liner coupled with a 36-mm cobalt-chrome alloy femoral head. The relationship between metal ion levels, cup orientation, osteolysis, radiographic implant stability and clinical outcome measures including component revision, complications, patient satisfaction and Harris Hip Scores will be evaluated.

Detailed description: Metal-on-metal bearings for total hip arthroplasty are an alternative to traditional polyethylene bearing surfaces and hip simulators studies have shown that metal-on-metal bearings have lower wear than metal-on-polyethylene bearings. In addition, simulator studies indicate that the amount of wear decreases as head size increases allowing the use of larger head diameters than possible with other bearing surfaces. Since dislocation is currently the most common reason for reoperation in the United States, representing 22.5% of hip revisions, the combination of low wear and larger head sizes to reduce dislocation hold the promise of improving outcome among total hip arthroplasty patients. While there are potential advantages to metal-on-metal bearings, a few concerns have been noted in the literature. Although the total volume of wear is low with these bearings, the articulation generates metal debris that may be related to patient and surgical factors such as implant positioning. Despite a reduced wear volume, there is also the possibility that an increased bioreactivity associated with metal debris might induce an osteolytic response or local tissue hypersensitivity reaction.

This study will retrospectively review the outcome of a consecutive series of 126 patients who had 131 primary THAs performed between April 2001 and November 2002 at the Anderson Clinic with a Pinnacle acetabular cup, an Ultamet insert and a 36-mm cobalt-chrome alloy femoral head. These total hip arthroplasties represent the Anderson Orthopaedic Institute's in initial experience with this implant. The relationship between metal ion levels, cup orientation, osteolysis, radiographic implant stability and clinical outcome measures including component revision, complications, patient satisfaction and Harris Hip Scores will be evaluated. The outcome data from our analysis will also be compared with the data from other published series with metal-on-metal bearing surfaces. Serial radiographs obtained as part of routine post-operative care will be used to evaluate osteolysis, implant stability and radiographic complications such as periprosthetic fracture. The area of each osteolytic region will be measured on the AP pelvic x-ray using Martell's Hip Analysis Suite. Computed tomography (CT) scans obtained as part of routine follow-up will be also analyzed to identify regions of acetabular osteolysis. The volume and location of each osteolytic defect identified on CT will be evaluated using three-dimensional image analysis software (Analyze, Biomedical Imaging Resource, Rochester, MN). A three-dimensional (3D) reconstruction of the pelvis, cup and acetabular osteolytic lesions will also be generated from the CT image data. This reconstruction will be oriented to simulate the AP pelvic radiographic view. Cobalt and chromium ion level data will be compiled for patients who had blood drawn to evaluate metal ion levels. The mean and median blood metal-ion levels for these patients will be calculated and the results will be compared to the metal-ion levels reported in the literature.

Eligibility criteria: Inclusion Criteria:

* Primary total hip arthroplasty patients who had surgery between April 2001 and November 2002 who were implanted with a Pinnacle acetabular cup, an Ultamet metal-on-metal insert and a 36mm cobalt-chrome alloy femoral head

Exclusion Criteria:

* Revision total hip arthroplasties
* Primary total hip arthroplasties using Ultamet liners coupled with 28-mm femoral heads

Primary outcomes:
measure: Metal Ion Levels Per Participant
timeFrame: At a mean of 4.2 years after primary total hip arthroplasty
Secondary outcomes:
measure: Cup Orientation Per Hip
timeFrame: On the first post-operative anteroposterior pelvic radiograph after primary total hip arthroplasty
measure: Harris Hip Score Per Hip
timeFrame: At a mean of 5.6 years after primary total hip arthroplasty
measure: Osteolysis Per Hip
timeFrame: At a mean of 5.6 years after primary total hip arthroplasty
measure: Implant Stability Per Hip
timeFrame: At a mean of 5.6 years after primary total hip arthroplasty
measure: Component Revision Per Hip
timeFrame: At a mean of 6.7 years after primary total hip arthroplasty
measure: Patient Satisfaction Per Hip
timeFrame: At a mean of 5.6 years after primary total hip arthroplasty
Other outcomes:
Locations:
city: Alexandria
country: United States
facility: Anderson Orthopaedic Research Institute
state: Virginia
Study officials:
affiliation: Anderson Orthopaedic Research Institute
name: Robert H Hopper, Jr., PhD
role: PRINCIPAL_INVESTIGATOR
References:
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