Summary

Chilean Population Study: Anatomical Distances Between Femoral Insertions of LCL and PT and Their Clinical Relevance

Abstract

Introduction

The posterolateral corner (PLC) plays a crucial role in stabilizing and restricting varus and external rotation of the knee in both static and dynamic conditions. The anatomical structures include primarily the lateral collateral ligament (LCL), the popliteal tendon (PT), and the popliteofibular ligament (PFL). The anatomical descriptions of the PLC, particularly the distance between the anatomical insertions of the LCL and the PT, exhibit significant variations based on the studied population and the technique employed.

Objective

The purpose of this study is to describe the anatomy of the femoral insertions of the LCL and PT in patients without PLC injuries or other types of associated knee ligament injuries in the Chilean population, specifically focusing on the distance between these insertions.

Methods

A cross-sectional observational imaging study was conducted at a single center involving patients over 18 years old. Exclusion criteria comprised a history of knee osteoarthritis, previous knee surgeries, fractures around the knee, and diagnosed associated knee ligament injuries. Knee magnetic resonance imaging (MRI) reconstructions were obtained using a 1.5 Tesla MRI scanner, with isotropic voxels of 0.65 x 0.65 x 0.65 millimeters (mm).
The distance between the central point of the LCL and PT insertion footprints (centroid) was then measured by 2 musculoskeletal radiologists.
An intraclass correlation coefficient (ICC) concordance analysis was performed and their 95% confidence intervals were calculated. Subsequently, a paired t-test was conducted to compare the means of the measurements taken by the two evaluators. A p-value < 0.05 was considered indicative of statistical significance. Based on the average centroid distance previously reported, a sample size of 40 patients was calculated.

Results

A total of 43 patients were included, 22 males (51.2%) and 21 right knees (48.8%). The average values were as follows: age 50.4 years (SD 11.7), height 1.66 m (SD 0.09), weight 77.7 kg (SD 12.5), and body mass index 28.3 kg/m² (SD 4.8). The average distances between the femoral insertion centroids of the LCL and PT were 11.5 mm (range 8.6-16.6) for observer 1 and 11.8 mm (range 7.6-17.1) for observer 2. No statistically significant differences were found between the average measured distances (p = 0.326), and the ICC was 0.83 (95% CI 0.69-0.91), which was considered a good correlation. The final average distance was 11.7 mm (SD 1.65).

Discussion

The average distance in our population differs from both the minimum (8.18 mm) and maximum (18.5 mm) values previously described in the literature, which were reported in ethnically distinct populations. This has important implications for both the diagnosis and the surgical management of these injuries.

Conclusion

The average distance between the centroids of the femoral insertions of the LCL and PT was 11.7 mm in our population. These data should be considered when planning the treatment of PLC injuries.