Anthropometric measurements of non-arthritic knees in an Egyptian population: an MRI-based study

Abstract

Background: Knee anthropometric characteristics were evaluated for different ethnicities; however, data from North African populations are deficient. The primary aim was to investigate the Egyptian knees' anthropometric characteristics as a representative of North African populations. Secondary aims are as follows: (1) to study the anthropometric gender difference, (2) to compare results with other ethnic groups, and (3) to study the mismatch in comparison to geometric characteristics of modern TKA implant designs.

Methods: Two hundred normal knee MRI scans (100 females and 100 males, aging from 18 to 60) were obtained for analysis. Linear measurements (anteroposterior (AP), mediolateral (ML), and aspect ratio (AR)) of the planned cut surface of the distal femur (f) and the proximal tibia (t) were evaluated.

Results: A significant difference between both sexes was found, males had larger measurements in anteroposterior [fAP: 60.97 ± 3.1 vs 54.78 ± 3.3 (P < 0.001), tAP: 46.89 ± 3.0 vs 41.35 ± 2.9 (P < 0.001)] and mediolateral [fML: 74.89 ± 3.2 vs 67.29 ± 3.7 (P < 0.001), tML: 76.01 ± 3.0 vs 67.26 ± 3.2 (P < 0.001)], the mean femoral and tibial AP and ML measurements were different from other ethnic groups. None of the seven studied TKA systems matched the largest ML or the smallest AP dimensions of the distal femur in the current study population.

Conclusion: A significant difference was found between males' and females' knee anthropometric characteristics. Some of the commonly used TKA implants in our area could not provide a perfect fit and coverage.

Trial registration: ClinicalTrials.gov identifier: NCT03622034 , registered on July 28, 2018.

Keywords: Anthropometric; Arab; North African; Total knee arthroplasty.

Fig. 1

Distal femoral measurements. a Identification of the trans-epicondylar axis (TEA). b Measuring the femoral mediolateral (fML) length. c Line 1 is drawn tangential to the lowest point of the lateral femoral condyle and parallel to the TEA in a corresponding axial cut. d Line 2 is drawn tangential to the highest point of the lateral distal femoral condyle (LDFC) and parallel to the TEA, measuring the femoral anteroposterior (fAP) length as the distance between Line 1 and Line 2

Fig. 2

Proximal tibial measurements: The tibial mediolateral (tML) length as the longest mediolateral diameter, the tibial anteroposterior (tAP) as the length of a line drawn perpendicular to the tML through the midpoint of the axial cut. (TEA, trans-epicondylar axis)

Fig. 3

Graph showing correlations between the femoral anthropometric measurements and modern knee implant designs (fML, femoral mediolateral; fAP, femoral anteroposterior)

Fig. 4

Graph showing correlations between the tibial anthropometric measurements and modern knee implant designs (tAP, tibial anteroposterior; tML, tibial mediolateral)