Abstract
BackgroundOur objective was to obtain normal patellofemoral measurements to analyse sex and individual differences. In addition, the absolute values and indices of tibial tuberosity-trochlear groove (TT-TG) distances are still controversial in clinical application. A better method to enable precise prediction is still needed.MethodsSeventy-eight knees of 78 participants without knee pathologies were included in this cross-sectional study. A CT scan was conducted for all participants and three-dimensional knee models were constructed using Mimics and SolidWorks software. We measured and analysed 19 parameters including the TT-TG distance and dimensions and shapes of the patella, femur, tibia, and trochlea. LASSO regression was used to predict the normal TT-TG distances.ResultsThe dimensional parameters, TT-TG distance, and femoral aspect ratio of the men were significantly larger than those of women (all p values < 0.05). However, after controlling for the bias from age, height, and weight, there were no significant differences in TT-TG distances and anterior-posterior dimensions between the sexes (all p values > 0.05). The Pearson correlation coefficients between the anterior femoral offset and other indexes were consistently below 0.3, indicating no relationship or a weak relationship. Similar results were observed for the sulcus angle and the Wiberg index. Using LASSO regression, we obtained four parameters to predict the TT-TG distance (R2 = 0.5612, p < 0.01) to achieve the optimal accuracy and convenience.ConclusionsNormative data of patellofemoral morphology were provided for the Chinese population. The anterior-posterior dimensions of the women were thicker than those of men for the same medial-lateral dimensions. More attention should be paid to not only sex differences but also individual differences, especially the anterior condyle and trochlea. In addition, this study provided a new method to predict TT-TG distances accurately.
Highlights
Our objective was to obtain normal patellofemoral measurements to analyse sex and individual differences
The exclusion criteria were as follows: (1) pregnant women or those who plan to conceive within the year; (2) history of poliomyelitis, rickets, dwarfism, rheumatoid arthritis, or other diseases that affect lower limbs; (3) a congenital deformity in either lower limb; (4) history of patellar instability, patellar dislocation, or the patellar apprehension test was positive on physical examination; (5) osteoarthritis of either hip or knee confirmed by previous imaging or by current Computed tomography (CT) scan; (6) fracture caused by injury to femur, tibia, hip, or knee; (7) joint arthroplasty, arthroscopic surgery or other surgery on the hip or knee
After controlling the bias from age, height, and weight, there were no significant differences in tuberosity-trochlear groove (TT-TG) distances, longitudinal length of the articular surface of the patella, or anterior-posterior dimensions including patella thickness, patella facet thickness, anteroposterior size of the femur, and posterior femoral offset between the sexes
Summary
Our objective was to obtain normal patellofemoral measurements to analyse sex and individual differences. Total knee arthroplasty (TKA) has proven to be a successful surgical procedure for alleviating pain and improving function in patients with knee osteoarthritis, patient satisfaction rates after TKA vary between 75 and 89 % [1]. An increasing number of researchers have observed mismatches of the patellofemoral joints after TKA. Kalichman et al suggested that increased trochlear angles were associated with exacerbated functional impairments [4]. Jan et al highlighted that the patellofemoral geometry was of great importance in TKA, but was often overlooked [5]. Increasing attention has been devoted to the modified design of patellofemoral joint prostheses in the field of TKA [6], among which the study of patellofemoral morphology is the basic research focus
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