Hybrid TKA: retrospective analysis of clinical and radiographic outcomes at average 10-year follow-up
Richard Illgen, MD Jonathan Tueting, MD M.E. Hagenauer T. Enright A. McBeath J. Heiner DOI:https://doi.org/10.1016/j.arth.2003.12.009Knee
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) Despite the reported success of cemented total knee arthroplasty, late loosening has remained an area of concern.(
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) In response to this concern, cementless implants were introduced as an alternative mode of fixation. Unfortunately, many implant designs have demonstrated higher rates of loosening, particularly of the tibial component, compared with cemented designs at similar follow-up intervals.(
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) Interestingly, the incidence of aseptic loosening of the femoral component in these cementless designs has been low. Hybrid total knee arthroplasty was introduced in the 1980s in the hopes of gaining the theoretical advantages of osseous ingrowth of the femoral component, while avoiding problematic tibial fixation often seen in cementless systems. Published clinical results with hybrid TKA have been variable depending on the length of follow-up evaluation and the type of implant system utilized.(
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) The majority of reports demonstrate excellent results in the short term,(
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) but others have noted higher rates of failure with hybrid TKA compared with cemented TKA at intermediate follow-up intervals.(
) The purpose of this paper is to review the durability of hybrid fixation in TKA at average 10-year follow-up at our institution (The University of Wisconsin-Madison). We retrospectively reviewed the outcomes of 112 hybrid TKA’s (Howmedica PCA – N= 67, and Howmedica Duracon – N=45) performed between 1987 and 1995 by two surgeons (JH and AM). Forty-nine patients had died, 9 patients could not be found, and 54 were alive and available for followup. Clinical and radiographic outcomes were determined and Knee Society Scores (KSS) were calculated. At average 10-year follow-up, the overall revision rate was 4.5 percent (5 of 112); four were performed in patients with metal backed patellae and one for infection. No revisions were performed for aseptic loosening of the femoral component, and all femoral components were well fixed at the time of revision. Aseptic loosening and radiographic failure rates were zero percent if patients with metal backed patellae were excluded. The average Knee Society Scores in our series were similar to other published cemented TKA series in well functioning implants at similar follow-up intervals.(
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) In our study, the clinical and functional KSS increased from 32.0 and 46.7 preoperatively to 84.5 and 65.6 postoperatively, respectively. These findings suggest that hybrid TKA with these implant designs provides durable fixation with excellent clinical and radiographic performance at 10 years comparable to cemented series if metal backed patellae were not used. Potential advantages of hybrid TKA include decreased operative time, bone preservation, and avoidance of adverse reactions to polymethylmethacrylate. Additionally, hybrid TKA may provide a more suitable approach for minimally invasive techniques compared with cemented fixation. In our opinion, the continued use of hybrid fixation with the Duracon knee system is warranted and the durability of hybrid fixation beyond 10 years deserves further study.
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