Julio Contreras; Claus Ogrodnik2 & Pablo Khek

Glenoid fossa bone loss has been associated with recurrence and failure after glenoid labrum repair for shoulder instability. Quantification of glenoid fossa bone loss is critical for the successful treatment of glenohumeral instability. The aim of this paper was to estimate a linear regression model based on glenoid height in CT scan adjusted for age and sex to calculate glenoid fossa width in a healthy Chilean sample. CT scans of 101 shoulders were reviewed. The mean age was 51.96 years (SD 19.16; range, 15–88 years) with 53 females and 48 male patients. Studies with signs of bone loss, instability, fracture, or arthritis were excluded. After 3D-CT reconstruction, the height and width of each glenoid fossa was measured using the Owens methodology. All landmarks for the 2 measurements were placed on the most lateral surface of the glenoid fossa margin. Measurements for all shoulders were recorded by 3 observers and repeated on a subset (n = 20) of shoulders, under blinded conditions, by the same observer, at least 2 weeks after the initial measurements. Descriptive statistics, intraclass correlation and regression coefficients were calculated with Stata BE 17® software. A p- value of 0.05 was considered significant. A linear regression model was estimated resulting in the formula “Width = 10.97 + 0.02 * Age + 0.41 * Height - 1.95 * Sex (1=Female, 0=Male)”. This model presented all coefficients with p <0.05 and an adjusted R2 of 0.73. Furthermore, it fulfilled the assumption of linearity, normal distribution of errors, independence of errors, and homoscedasticity. Regarding the intraobserver correlation, ICC was 0.76 for height and 0.91 for width; the interobserver ICC was 0.93 for height and 0.86 for width. A 3D-CT specific formula was developed to predict glenoid fossa width based on height with sufficient accuracy to be clinically valuable.

KEY WORDS: Shoulder joint; Glenoid fossa; Anatomy; Shoulder dislocation.

CONTRERAS, J.; OGRODNIK, C. & KHEK, P. Estimating glenoid fossa width for instability-related bone loss with CT scan in a Chilean sample. Int. J. Morphol., 39(5):1487-1492, 2021.