Locking plate fixation in comminuted coronoid fractures with partial loss of the articular cartilage - Of basal-1 type according to the O'Driscoll classification.

BACKGROUND: We have attempted to restore the arc of motion by considering trochlear-coronoid articulation as a complete circle during fixation of the coronoid, even for comminuted coronoid fractures with partial loss of articular cartilage (CCFPLAC), using various kinds of locking plates. Herein, we report the radiological and clinical outcomes after fixation of the basal-1 type of CCFPLAC (O'Driscoll classification) using our method.

METHODS: Thirty-one patients diagnosed with CCFPLAC were admitted between January 2012 and December 2020. Sixteen of these patients met the inclusion/exclusion criteria and were enrolled in this study. Surgically, the lost area (defect of articular cartilage) was never compressed or minimized, but the original height and shape of the coronoid were preserved as is. Provisionally, a few K-wires were used to maintain the original shape and position of the CCFPLAC, and various kinds of locking plates/screws were used to fix the fragment anatomically and firmly. If needed, the plate was bent to ensure stable compression of the coronoid according to its size. In a few cases, locking plates were adjusted by cutting extra screw holes.

RESULTS: Among the 16 patients, the mean age was 46.2 years, and the male:female ratio was 10:6. The mean follow-up period was 3.63 years. 8, 6, and 2 patients were designated as group 1 (isolated CCFPLAC), 2 [CCFPLAC in type 4 (terrible triad) injury), and 3 (CCFPLAC in type 5 posterior olecranon fracture-dislocations), respectively. Complete union was achieved after a mean of 8.94 weeks. The mean flexion-extension and pronation-supination arcs were 127.19 ± 4.46° and 135.31.59 ± 8.06°, respectively, which were significantly different from those on the contralateral (normal) side (p < 0.001); however, the arcs were within the functional ranges for ordinary daily living. Additionally, the functional status was satisfactory in all patients. However, Mayo Elbow Performance Score and the degree of arthritis were statistically poor in group 2.

CONCLUSIONS: CCFPLAC of the basal-1 type (O'Driscoll classification) can be treated satisfactorily if already designed and widely distributed locking plates are properly manipulated to maintain the original geometry of the coronoid according to the individual joint characteristics.

LEVEL OF EVIDENCE: Level IV, Retrospective case series.