Feasibility of an osteochondral allograft for biologic glenoid resurfacing

Concerns regarding insufficient press fit and glenoid vault cortical blowout make glenoid osteochondral allografting uncommon. We used 3-dimensional computed tomography modeling to test glenoid osteochondral allografting feasibility.

Sixteen cadaveric shoulders without osteoarthritis underwent computed tomography scans to create 3-dimensional models. The diameter of circular center-based reaming reaching the medial endosteal surface at depths of 4, 6, and 8 mm and the clock face position of the most shallow points were calculated. Demographic factors associated with graft diameter were analyzed by step-wise multiple regressions.

Shallower graft depths allowed larger graft diameters (P < .001). With a graft depth of 4 mm, 56% of glenoids allowed 20-mm-diameter grafts and 94% accommodated 16-mm grafts versus 31% and 75%, respectively, for a graft depth of 6 mm and 13% and 38%, respectively, for a graft depth of 8 mm. Increasing graft depth decreased graft glenoid coverage: mean coverage was 51.9% ± 12.2%, 36.3% ± 12.9%, and 23.8% ± 14.2% for 4-, 6-, and 8-mm depths, respectively. The glenoid's most shallow point was between the 1:30 clock face position and 3-o'clock position in reference to a right shoulder in 69%, 75%, and 44% of glenoids for 4-, 6-, and 8-mm depths, respectively. Although female gender, patient height, and glenoid height and width were associated with graft diameter, multiple regression analysis showed that patient height was the only independent variable associated with accommodated graft diameter at depths of 4, 6, and 8 mm (P = .001, P = .001, and P = .003, respectively).

Most glenoids support center-based grafts of 16 to 20 mm in diameter at a depth of 4 mm, covering an average of 51.9% of the glenoid. Accommodated graft size decreases as reaming depth increases.