Morphometric Study of Lower End Femur by Using Helical Computed Tomography

Morphology characters of resected femoral and tibial surface in chinese population: intraoperative anthropometric study in patients at a tertiary hospital

BACKGROUNDS

Mismatch between knee surface and prosthesis components is related to postoperative complications. Morphological differences between ethnicity and gender may affect prosthesis coverage. The purpose of this study is to describe morphological characters of resected knee surface (distal femur, proximal tibia) in the Chinese population, analyze the influence of gender and other demographical factors, and validate the effect of ethnic difference by calculating the coverage of Western-designed knee prostheses on Chinese knee surface.

METHODS

Intraoperative anthropometries were performed during total knee arthroplasty performed by one single team. After screening out severe deformities and bone defects, data were separated via prosthesis system. Multiple linear regression and partial correlation analysis of morphological parameters on age, gender, height, weight were used to find out independent factors influencing morphology. Based on the 5 mm-tolerance in the prosthesis, simulation on scatter plots was brought out to calculate the prosthesis coverage to the resected bone surface.

RESULTS

A total of 865 cases of total knee arthroplasty were involved in this study. Though gender differences were found in all knee morphological parameters regardless of the type of prosthesis, significant association was only found between gender and mediolateral width of femoral surface after adjusting demographical factors (p < 0.001). The two included prosthesis systems, Genesis-II and Scorpio NRG covered most cases in at least one dimension. Males had lower complete coverage and higher no coverage rate on femurs. Asymmetry prostheses had higher lateral coverage on tibiae.

CONCLUSIONS

Based on our analysis, the only confirmed demographical factor in knee morphology is gender on femoral mediolateral length. Wider femoral prostheses for males may improve results of gender-specific prostheses. The overall fitness between Western-designed prostheses and Chinese knee surface is appliable, but the ratio of complete coverage is low. Further modification of prostheses systems can aim at the number of sizes and geometrical shapes.

Sexual dimorphism and racial diversity render bone-implant mismatch inevitable after off-the-shelf total knee arthroplasty: a systematic review and meta-analysis

PURPOSE

The purpose of this systematic review and meta-analysis was to investigate the variability in femoral geometric ratios among knees of different sexes and races, and to appreciate whether the observed variability is accommodated by commonly implanted total knee arthroplasty (TKA) components. The hypothesis was that the anthropometric studies report considerable variability of femoral geometric ratios among sexes and races.

METHODS

This systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) criteria. Two authors independently conducted an electronic search using MEDLINE^® and Embase^® on 6 July 2020 for clinical studies reporting on femoral geometric ratios among sexes and races. Femoral geometric ratios were graphically represented as means and 2 standard deviations, and compared to those of 13 commonly implanted femoral components.

RESULTS

A total of 15 studies were identified that reported on a combined total of 2627 knees; all reported the aspect ratio, and 2 also reported the asymmetry ratio and trapezoidicity ratio. Men had wider knees than women, and compared to Caucasian knees, Arabian and Indian knees were wider, while East Asian were narrower. There were no differences in asymmetry ratio between men and women, nor among Caucasian and East Asian knees. Men had more trapezoidal knees than women, and East Asian knees were more trapezoidal than Caucasian knees. The commonly implanted femoral components accommodated less than a quarter of the geometric variability observed among sexes and races.

CONCLUSION

Anthropometric studies reported considerable sexual dimorphism and racial diversity of femoral geometric ratios. Since a surgeon generally only uses one or a few TKA brands, bone-implant mismatch remains unavoidable in a large proportion of knees. These findings support the drive towards personalized medicine, and accurate bone-implant fit may only be achievable through customisation of implants, though the clinical benefits of custom TKA remain to be confirmed.

LEVEL OF EVIDENCE

IV.

Morphologic Features of the Distal Femur and Proximal Tibia: A Cross-Sectional Study

Background

The asymmetric medial and lateral condyles of the distal femur and proximal tibia have a direct influence on the biomechanics of knee joint and prostheses design. This study aimed to determine the morphologic data, that is., anteroposterior (AP) and mediolateral (ML) widths, and the radius of curvature (ROC) of the geometric arcs of the distal femur and proximal tibia.

Methods

One hundred and seventeen adult dry bones (57 femurs and 60 tibias) were studied. Aspect ratios (AP/ML) were calculated. The AP and ML widths were measured using digital Vernier Caliper with a measuring range of 0-150 mm, resolution of 0.01 mm, and accuracy ± 0.02 mm. The geometric arcs of femoral and tibial condyles were divided into three parts namely anterior 1/3rd, distal (femur) or middle (tibia) 1/3rd and posterior 1/3rd and were estimated in the sagittal plane for the femur and transverse plane for tibia using the ROC gauges.

Results

For the femur, the mean AP length for medial and lateral condyles was 55.62 mm and 57.93 mm, respectively, while the mean ML width was 73.45 mm. For the tibia, the mean AP length for medial condyle (MC) and lateral condyle (LC) was 47.74 mm and 43.46 mm, respectively. The mean aspect ratios for the distal femur and proximal tibia were 1.26 and 1.45, respectively. The mean aspect ratios for MC and LC of the femur were 0.50 and 0.52, respectively, whereas, for tibia, they were 0.61 and 0.71, respectively. The mean ROC for femoral MC - 20.77 mm, 31.42 mm, and 19.68 mm and for LC - 21.48 mm, 64.40 mm and 19.06 mm for the anterior, distal and posterior arcs, respectively. The mean ROC for tibial MC - 22.42 mm, 22.49 mm and 19.94 mm, and LC - 19.92 mm, 21.79 mm and 20.95 mm for the anterior, middle and posterior arcs, respectively.

Conclusions

The morphologic data accumulated in this study for both the distal femur as well as the proximal tibia would provide guidelines and help the manufacturers of joint prostheses to address the potential for compromised implant fit and re-design and make available ‘anatomic’ knee prostheses appropriate for the local population which would not only improve function but also prolong the longevity of the prostheses.