Summary

Reliable and reproducible anatomical references optimize the harvest of hamstring graft. This observational study identified that the neck of the fibula is the reference with the least variability and the highest interobserver agreement to guide the identification of pes anserinus versus other commonly used anatomical references.

Abstract

Introduction

The hamstring graft (semitendinosus and gracilis) is frequently used in knee surgery. Reliable and reproducible anatomical references optimize the harvest, allowing a smaller incision, with better cosmetic results, less risk of injury to the infrapatellar branch of the saphenous nerve, pain and hematoma. To date, the references used are based on cadaveric studies, with small sample sizes, which only report the relationship with the medial edge of the tibial plateau and the anterior tibial tuberosity (TAT).

OBJECTIVES
1) To measure the distances, in magnetic resonance imaging (MRI), between the proximal edge of the pes anserinus (PA) and adjacent anatomical landmarks: medial plateau, TAT, neck and head of the fibula, 2) To determine the correlation of these measurements between two independent observers.

Method

Cross-sectional observational design study, approved by the ethics committee.
A correlative convenience sample of knee MRI performed in a center between May-June 2022 was performed. Inclusion criteria: patients between 15-49 years of age. Exclusion: medial structures injury, previous surgeries, fractures, tumors or infections. Sample size calculation: n=50 for 80% power. Two trained orthopedic surgeons made the following measurements: M1) Longitudinal distance from the proximal edge of the medial endplate to the proximal edge of the PA M2) Transverse distance from the most prominent point of the TAT to the insertion of the PA M3) Longitudinal distance from the neck of the fibula to the proximal edge of the PA M4) Longitudinal distance from the most prominent point of the fibula to the proximal edge of the PA. For the statistical analysis, Mann Whitney and Chi2 tests were used to compare variables, considering a statistical significance of p<0.05 (STATA v.16). To evaluate the correlation between the orthopedic surgeons, the intraclass correlation coefficient (ICC) was used.

Results

50 MRI of 50 patients were obtained, 50% female, 50% right-side, with a mean age of 31.5 years (±9.6). The measurements means were: M1 38.5mm (SD 3.6; range 31-47], M2 24.1mm (SD 4.1;17-36], M3 1.7mm (SD 1.8; -1-6] and M4 12 .4mm (SD 2.5; 8-19]. In M1 measurement there were statistically significant differences between sex being greater in men (40.7±2.7) versus women (36.4±3 .1). There were no differences between the measurements according to age or laterality. The correlation between both orthopedic surgeons in the four measurements was excellent: ICC=0.85 (95% CI 0.73-0.91), 0.86 (95% CI 0.75-0.92), 0.92 (95% CI 0.86-0.96) and 0.87 (95% CI 0.78-0.93) respectively.

Conclusions

The neck of the fibula is the reference with the least variability and the highest interobserver agreement to guide the identification of PA versus other commonly used anatomical references. The distance to the medial plateau has greater variability and significant differences between sex.