Abstract
Abstract
Objectives
The need for gender specific knee arthroplasty is debated. This research aimed to establish whether gender differences in patellar tendon moment arm (PTMA), a composite measure that characterises function of both the patellofemoral and tibiofemoral joints, are a consequence of knee size or other variation.
Methods
PTMA about the instantaneous helical axis was calculated from positional data acquired using optical tracking. First, data post-processing was optimised, comparing four smoothing techniques (raw, Butterworth filtered, generalised cross-validation cubic spline interpolated and combined filtered/interpolated) using a fabricated knee. Then PTMA was measured during open-chain extension for N=24 (11 female) fresh-frozen cadaveric knees, with physiologically based loading and extension rates (420°/s) applied. Gender differences in PTMA were assessed before and after accounting for knee size with epicondylar width.
Results
Combined smoothing enabled sub-mm accuracy (root-mean-squared (RMS) error 0.16mm, max error 0.47mm), whereas large errors were measured for raw (RMS 3.61mm, max 23.71mm), filtered-only (RMS 1.19mm, max 7.38mm) and interpolated-only (RMS 0.68mm, max 1.80mm) techniques. Before scaling, average PTMA throughout knee flexion was 46mm and mean, maximum, and minimum absolute values of PTMA were larger in males (mean differences >8mm, p<0.001), as were the PTMAs at terminal extension and flexion, and the change in PTMA from peak to terminal extension (differences >4mm, p<0.05). After scaling, the PTMA in deep flexion and the change in PTMA from peak to terminal extension were still larger in male knees (differences >2mm, p<0.05). The flexion angle of peak PTMA, unaffected by scaling, was closer to terminal extension for female knee (female 15°, male 29°, p<0.05).
Conclusion
Gender differences in PTMA were identified both before and after accounting for knee size, with implications for gender-specific arthroplasty and musculoskeletal models. The developed measurement framework could also be applied in vivo for accurate measurement of the PTMA.
Declaration of Interest
(b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
