An Inlay Patellofemoral Arthroplasty With An Enlarged Trochlear Component Design Results In Better Patient Reported Outcomes Measures And Lower Failure Rates Compared To A Traditional Design: A Two-Year Follow Up Study

An Inlay Patellofemoral Arthroplasty With An Enlarged Trochlear Component Design Results In Better Patient Reported Outcomes Measures And Lower Failure Rates Compared To A Traditional Design: A Two-Year Follow Up Study

Armin Runer, PD MD, GERMANY Jonas Pogorzelski, MD, PhD, MHBA, GERMANY Hugo Bothorel, MEng, SWITZERLAND Philippe Matthias Tscholl, MD, SWITZERLAND Matthias Cotic, MSc, GERMANY Sebastian Siebenlist, MD, MHBA, Prof., GERMANY Andreas B. Imhoff, MD, Prof. Emeritus, GERMANY

Department of Sports Orthopaedics, Technical University of Munich, Munich, GERMANY


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Anatomic Location

Diagnosis / Condition

Sports Medicine

Treatment / Technique


Summary: A trochlear inlay component featuring an enlarged trochlear design demonstrated superior improvement in patient-reported outcome measures, with both clinically and statistically significant differences, as well as a lower failure rate at 2-year follow-up compared to a conventional design.


To compare the two-year outcome after primary isolated patellofemoral inlay arthroplasty (PFIA) using two second-generation inlay trochlear component designs. We hypothesized that an enlarged trochlear component design (HemiCAP® Kahuna, Anika Therapeutics) would produce better patient reported outcome measures than a common design (HemiCAP® Wave, Anika Therapeutics).

Methods

This was a retrospective comparative study of primary isolated PFIA. Cases were retrieved from a prospective database and divided into two groups based on inlay trochlear component design (Wave/Kahuna). An independent observer collected the following data preoperatively and at two years postoperatively: The WOMAC, VAS for pain score, the Tegner scale and tibiofemoral osteoarthritis progression. A clinical failure was defined as an overall WOMAC score <43 at the end of follow-up but no revision surgery.

Results

Of the 157 PFIAs assessed for eligibility, 44 could be enrolled and divided into two groups of 22 patients. Five patients were subsequently excluded in each group, leaving finally 17 patients for the final analysis. Both groups had similar preoperative characteristics. VAS for pain improved significantly in both groups (p <0.05). Significant improvements were found in all WOMAC scores for the Kahuna group (p <0.05) but not for the Wave group (p >0.05). The overall WOMAC, function and pain subscores, were significantly better in the Kahuna group compared to the Wave group (p <0.05). No significant progression of tibiofemoral OA was observed in both groups (p <0.05). Overall failure rate for the Kahuna group (n=22) was 13.6% (3 revision arthroplasties) and 36.4% (3 revision arthroplasties, 5 overall WOMAC scores <43) for the WAVE group (n=22).

Conclusion

Both trochlear component designs reduced knee pain and prevented TFOA progression. However, a trochlear inlay component featuring an enlarged trochlear design demonstrated superior improvement in patient-reported outcome measures, with both clinically and statistically significant differences, as well as a lower failure rate at 2-year follow-up compared to a conventional design.