Summary

The Lateral Radial Head Offset is increased in patients with chronic epicondylopathy – A new indicative radiological parameter

Abstract

Objective

The aim of this study was to compare anatomical parameters on magnet resonance imaging (MRI) scans between patients with chronic lateral epicondylopathy (cER) and a healthy control group. It was hypothesized that the radial head would show an increased lateralization in patients with cER.

Material And Methods

Consecutive patients with cER (> 6 months) who underwent arthroscopic debridement of the extensor carpi radialis brevis (ECRB) at a single institution from 11/2020 to 07/2023 and had received preoperative MRI were included in this study. Patients were excluded if they had previous elbow surgeries, fractures, extensor or flexor muscle and tendon avulsions, previous elbow dislocations, or showed intraoperative signs of posterolateral instability (via arthroscopic rod technique). The MRIs of all included patients were compared to a control group of healthy individuals. Sample size calculation revealed the necessity of 26 patients per group (d = 0,7; β = 0,8, α = 0.05). Following radiological measurements were performed by 2 independent raters in millimeters (mm): lateral humeral epicondyle prominence (LHEP), radial head diameter (RHD), posterior radial offset (PRO), lateral radial head offset (LRHO), capitellum width (CW) and ulnohumeral incongruence (UI). The LRHO-ratio (LRHO/RHD; %) was calculated to express the lateralization of the radial head relative to its diameter. Group comparisons were performed using the Mann Whitney U Test. Intraclass correlation coefficients (ICC) were calculated to evaluate the interrater reliability of all measurements. Level of significance was set at p < 0.05.

Results

A total of 77 elbows (37 cER/ 40 healthy control) from 57 patients (37 male; age 39.3 ± 11.2 years; right 46, BMI 23.0 ± 7.6) were included. Mean duration of symptoms in the cER group was 16.8 ± 13.5 months. Significant group differences in cER vs. healthy controls were observed for LRHO (3.3 ± 1.2 vs. 1.5 ± 2.1 mm, p < 0.001), LRHO-ratio (21.1% vs. 9.1%; p < 0.001), and PRO (5.1+ 1.5 vs. 0.7 ± 1.2 mm, p < 0.001). There was no significant difference between groups in LHEP (11.7 ± 8.8 vs. 11.0 ± 1.6 mm, p = 0.051), RHD (22.2 ± 4.1 vs. 22.2 ± 3.7 mm, p = 0.779), CW (15.1 ± 5.8 vs. 16.4 ± 1.9 mm, p = 0.903) and UI (2.2 ± 0.6 vs. 2.4 ± 0.6 mm, p = 0.238). ICC showed satisfactory results for all measurements (r = .64, p < 0.001).

Conclusion

The LRHO, LRHO-ratio, and PRO were significantly higher in patients with cER compared to healthy controls. This indicates an increased lateralization and posteriorization of the radiohumeral joint complex, which may be the result of inadequate dynamic joint stabilization at the onset of cER with intraoperatively proven ligament stability.