Patellar lateral facet allograft as a potential graft source in glenoid bone reconstructions for anterior shoulder instability: an MRI-based morphometric analysis

Recurrent anterior shoulder instability with glenoid bone loss often requires bony augmentation. Traditional graft sources-coracoid transfer, iliac crest autograft, and distal tibial allograft-carry limitations such as nonanatomic reconstruction, donor-site morbidity, and variable graft morphology. We hypothesized that the radius of curvature (ROC) of the patellar lateral facet approximates the native glenoid ROC, supporting its use as an osteochondral allograft for anatomic glenoid reconstruction. MRI scans from 609 adults (324 female, 285 male; mean age 39.0 &#xb1; 12.8 years) were analyzed. ROC measurements included glenoid coronal and axial, patella axial and sagittal, and distal tibia sagittal planes. Patellar dimensions were also recorded. Statistical analyses comprised repeated-measures ANOVA with post-hoc tests, Bland-Altman agreement analyses, multiple linear regression, and threshold-based matching to determine ROC congruence. Mean ROCs were as follows: glenoid coronal 24.6 &#xb1; 2.6 mm, glenoid axial 25.0 &#xb1; 2.6 mm; patella axial 24.8 &#xb1; 2.8 mm, patella sagittal 24.6 &#xb1; 3.0 mm, and distal tibia sagittal 23.9 &#xb1; 2.6 mm. ANOVA revealed significant differences among parameters (P < .001; &#x3b7;= .120), with no difference between glenoid coronal and patella sagittal ROC (P = .999). Gender significantly influenced both axial and sagittal patellar ROC (P < .001 and P = .006, respectively), with larger patellae demonstrating greater ROC variability. Regression models explained &#x223c;26% of ROC variance based on gender and patellar dimensions. Bland-Altman plots showed small biases (<1 mm) but wide limits of agreement (&#xb1;7 mm). Threshold analysis demonstrated &#x2265;20% matching within 1.0 mm for glenoid coronal vs. patella sagittal, with &#x2265;50% matching achieved at 3.0 mm tolerance. The patellar lateral facet ROC closely matches native glenoid curvature, indicating its potential as an allogenous osteochondral graft for glenoid reconstruction. However, substantial individual variability necessitates patient-specific evaluation and preoperative planning.