Humeral capitellum fracture combined with humeral lateral column injury: A novel classification system and treatment algorithm.

BACKGROUND

Shear humeral capitellum fracture (CF) treatment can be complicated by comminution of the distal lateral humeral column (LHC). Although treatment with a 3.5 mm posterolateral distal humerus plate with support (PDHPWS) has been proposed, its indications have not yet been outlined. The purpose of this study was to describe a classification system for this fracture pattern and provide a therapeutic algorithm to avoid complications associated with PDHPWS fixation.

METHODS

Thirty-four patients who underwent surgical treatment for CF with LHC comminution were enrolled. The humeral capitellum angle (α angle) measured on the sagittal view of computed tomography reconstructions corresponded to the height of the LHC fracture line; based on this height, the severity of LHC injury was categorized as subtype L (low fracture line, 60° < α < 90°), subtype M (moderate fracture line, 45° < α < 60°) or subtype H (high fracture line, α < 45°). The therapeutic algorithm was countersunk compression screws for subtype L, lateral buttressing combined with/without an anterior antiglide mini-fragment plate for subtype M and a dorsolateral anatomical locking plate for subtype H. At the end of the follow-up period, the treatment outcome was evaluated by radiography and an assessment of the range of motion. A functional assessment was carried out using the Mayo Elbow Performance Score (MEPS) and Disabilities of the Arm, Shoulder and Hand (DASH) score.

RESULTS

The mean age of patients in this cohort was 49.6 ± 14.6 years, and the mean follow-up duration was 48.9 ± 34.6 months. There were 10 cases classified as subtype L, with a mean α angle of 80.6 ± 8.8°. The mean α angle for the 13 cases classified as subtype M was 52.1 ± 4.6° and that for the 11 cases classified as subtype H was 24.1 ± 22.4°. All fractures healed uneventfully, and implant removal was required in 8 cases (one subtype M and seven subtype H). The average MEPS in the three subgroups was 84.5 (subtype L), 87.3 (subtype M) and 78.2 (subtype H), while the average DASH score was 13.9 (subtype L), 11.6 (subtype M) and 21.5 (subtype H). Compared with the other subtypes, subtype H showed the smallest improvement in mean elbow function (112.7° in flexion, 13.6° in extension, 66.4° in pronation and 71.4° in supination). No cases of heterotopic ossification or avascular necrosis of the capitellum developed in any group.

CONCLUSION

By analyzing the fracture morphology, a substantial portion of CFs with mild to moderate LHC comminution could be successfully managed by a simpler and less aggressive method with fewer complications than PDHPWS.

LEVELS OF EVIDENCE

Level IV; Case Series; Treatment Study.