Comparative analysis of locking plate versus hook plate osteosynthesis of Neer type IIB lateral clavicle fractures.

INTRODUCTION: Controversy exists on optimal operative treatment of vertically unstable Neer IIB lateral clavicle fractures. Aim of this study was to analyse and compare clinical and radiological results and complications of locking plate osteosynthesis (LPO) versus hook plate osteosynthesis (HPO) with acromioclavicular joint (ACJ) stabilization. The hypothesis was, that HPO would recreate coracoclavicular stability more effectively and potentially lead to a superior outcome.

METHODS: This retrospective, observational cohort study included 32 patients (19 HPO, 13 LPO) with a mean age of 44.1 ± 14.2 years at surgery. The mean follow-up period was 54.2 months (range 25.2-111.4 months). Besides standard radiography, bilateral coracoclavicular distances were assessed by means of preoperative and follow-up stress radiographs after implant removal. Clinical outcome measures included the Constant score (CS), the Oxford shoulder score (OSS), the subjective shoulder value (SSV) and the Taft score (TS).

RESULTS: Bone union occurred in all but one patient and proved to occur delayed in five patients (15.6%). Radiographical healing required a mean of 4.2 ± 4.0 months irrespective of the type of osteosynthesis. At follow-up, mean coracoclavicular distance was increased by 34% (±36) without significant differences between both groups. HPO patients obtained a significantly lower TS (HPO: 9.5 ± 1.5 points, LPO: 11.1 ± 1.3 points; p = 0.005). Other mean score values did not differ (CS: 90.1 ± 7.4 points, OSS: 43.2 ± 9.2 points, SSV: 91.1 ± 14.7%). Sixteen patients (50.0%) experienced complications. Overall prevalence of complications was significantly higher in the HPO group (p = 0.014).

CONCLUSIONS: Both HPO and LPO were equally effective in relation to restoration of vertical stability, overall functional outcome and fracture consolidation in treatment of Neer IIB fractures. Contrary to our hypothesis, HPO was not associated with superior recreation of the coracoclavicular distance. Considerable drawbacks of HPO were an inferior ACJ-specific outcome (Taft-Score) and a higher overall complication rate. Level of evidence IV.