Establishing Experimental Sample Uniformity Prior to Patella Component Fixation Testing

Purpose: It is imperative to perform quality control studies to validate experimental sample quality prior to testing. Due to the inherent inconsistency when using cadaveric bone as a means to test clinically relevant hypotheses, one such quality check is to geometrically study the variability present in the bone samples. Thus, as a quality control step prior to investing resources to undertake the overall aim of studying patella component fixation in total knee arthroplasty (TKA), this study aims to establish sample uniformity by analyzing patella length, width, and depth. Methods: Ten random pairs of patellae were harvested from a possible 39 embalmed cadavers. Each patella was then prepared by an orthopaedic surgeon, as if performing an intraoperative TKA, for fixation of a patella implant component. After preparation but before adding a patellar component and cement, the surgeon visually inspected each patella and separated each pair with the better bone quality sample as part of the control group and the other as part of the treatment group. Measurements were then taken by two independent observers using a caliper to determine the superior-inferior patellar length (SIL), medial-lateral width (MLW), and the sectioned patellar thickness (TH). T-tests were performed to establish interobserver measurement reliability and the geometric uniformity between the control and treatment groups and between the left and right samples. Results: There was no significant difference between readers in the SIL (p=0.48), MLW (p=0.58) and TH (p=0.23) measurements. No significant differences were found when comparing between the control and experimental groups for any of the three measures (SIL p=0.21, MLW p=0.44, TH p=0.90). There was however, a significant difference observed in the sectioned preparation TH (p=0.007) when comparing left and right knee patellae. Conclusions: Based on the geometric outcomes measured (SIL, MLW, TH) the results of this study validate the sample uniformity when comparing patellae based on control and treatment groups rather than right verses left. Doing so helps control sample quality for completing the overall aim to study cement fixation methods of the patellar component in TKA.