Abstract
BackgroundThe separate design concepts of dual-mobility cups and triple-taper femoral stems were developed to improve survivorship following total hip replacement (THR) by reducing instability/dislocation and enabling enhanced fixation. Successful outcomes at over two decades have been reported with earlier-generation devices based on these concepts. The current study aimed to provide the first long-term results with a unique pairing of later-generation dual-mobility cup and triple-taper cementless femoral stem after a decade of use in patients undergoing THR.MethodsIn this retrospective analysis, records were reviewed for all subjects implanted with this dual-mobility cup/cementless femoral stem combination at three centers between 2002 and 2005. Any subject who had not already had follow-up visit beyond 10 years, was not previously revised, and still living were invited for a single follow-up visit consisting of Merle d’Aubgine Scores, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index, and standard radiographs.ResultsThere were 244 THRs available for analysis. At a mean follow-up of 11.9 years, the Kaplan-Meier survivorship (endpoint: revision for any reason) was 99.1% (95% CI, 97.6–99.7) for the stem and 95.9% (95% CI, 93.1–97.6) for the cup. Merle d’Aubigne Scores were significantly improved from baseline and WOMAC scores were in the satisfactory range at the final follow-up. Radiographic analysis revealed no cases of stem subsidence, no cases of bone hypertrophy, 1 (0.4%) case of bone atrophy, and 3 (1.2%) cases of osteolysis around the stem. No subjects had radiolucent lines greater than 1 mm in any femoral Gruen zone. Evidence of cup migration was seen in 1 (0.4%) subject and 1 (0.4%) subject had evidence of osteolysis that was seen in Gruen zones I, II, IV, and V.ConclusionsThis combination of a later-generation dual-mobility cup and cementless triple-taper stem was associated with excellent survivorship and satisfactory functional outcomes at over 10 years follow-up.Trial registrationClinicalTrials.gov, NCT02648152. Date of registration: January 6, 2016. Retrospectively registered.
Highlights
Successful outcomes are routinely observed for total hip replacement (THR), with data from both case series and joint registries indicating that all-cause survivorship of > 85% can be achieved 15 years after primary surgery [1]
There were 502 THRs implanted during the period of interest that satisfied the inclusion/exclusion criteria, of which 106 refused to return and 152 were deceased, leaving 244 who agreed to return for a follow-up visit (Table 1)
At a mean follow-up time of 11.9 years, the Kaplan-Meier survivorship was 99.1% with revision of the femoral stem for any reason as the endpoint and 95.9% with revision of the acetabular component for any reason as the endpoint
Summary
Successful outcomes are routinely observed for total hip replacement (THR), with data from both case series and joint registries indicating that all-cause survivorship of > 85% can be achieved 15 years after primary surgery [1]. Dualmobility cups combine the foundational principles of low friction, which includes a mobile polyethylene liner locked on a femoral head articulating in a smooth metallic acetabular shell. This double articulating bearing with a large head-to-neck ratio results in enhanced joint mobility before the outer edges of the liner impinges against the femoral neck [4]. The separate design concepts of dual-mobility cups and triple-taper femoral stems were developed to improve survivorship following total hip replacement (THR) by reducing instability/dislocation and enabling enhanced fixation.
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