Sex-Based Differences in Optimal Tunnel Placement for Acromioclavicular Joint Reconstruction

Abstract

Background: Tunnel placement is important for outcomes after acromioclavicular (AC) joint reconstruction, yet little has been written on sex-based differences in optimal tunnel positioning. Hypothesis: No sex-based or anatomic differences will be found in ideal tunnel position based on radiographic measurements. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The records of 2382 patients were retrospectively examined for clavicle radiographs over a 20-year period. A random set of radiographs were reviewed until 200 radiographs from each sex met inclusion criteria per a priori power analysis. Anteroposterior clavicle radiographs were used to collect (1) length from lateral clavicle to lateral coracoid (LCLC), (2) length from lateral clavicle to medial coracoid (LCMC), (3) clavicle length (CL), and (4) clavicular depth at the midcoracoid (MCCD). The Student t test was used to compare differences between male and female patients. The Pearson correlation coefficient was used to measure linear correlations. Variables with a P < .1 were included in a multiple regression model. Results: The cohort included 200 men and 200 women. LCLC and LCMC were significantly greater for men than for women ( P < .0001). Clavicle length was significantly correlated with LCLC ( r = 0.63; P < .0001) and LCMC ( r = 0.74; P < .0001). MCCD was significantly correlated with LCLC ( r = 0.32; P < .0001) and LCMC ( r = 0.43; P < .0001). The approximate placement for the trapezoid tunnel was found to be 22.1 mm in women and 26.6 mm in men. The approximate placement for the conoid tunnel was found to be 40 mm in women and 46.6 mm in men. The ratios (LCLC:CL and LCMC:CL) were also significantly different between female and male patients. The LCLC:CL was 0.144 in women and 0.154 in men ( P < .0001). The LCMC:CL was 0.261 in women and 0.271 in men ( P < .0006). Conclusion: Significant sex-based differences are found in the position of the coracoid relative to the lateral edge of the clavicle. Coracoid position relative to the lateral edge of the clavicle is correlated with anatomic parameters, most strongly with clavicle length.