Mid-term results of minimally invasive deltoid-split versus standard open deltopectoral approach for PHILOS™ (proximal humeral internal locking system) osteosynthesis in proximal humeral fractures.

PURPOSE: Only a few reports compare the mid- and long-term outcome of the minimally invasive deltoid split (MIDS) with the classic anterior deltopectoral (DP) approach for osteosynthesis in proximal humeral fractures. This study compared the mid-term functional and the radiological results in patients with proximal humeral fractures undergoing osteosynthesis with the proximal humeral internal locking system (PHILOS™).

METHODS: All patients undergoing osteosynthesis between 2008 and 2015 were clinically and radiologically examined with a minimal follow-up period of 1 year. Functional outcomes were analyzed using the DASH- and Constant Shoulder Scores (CSS). Radiological results were analyzed using a newly developed score.

RESULTS: Thirty-nine patients underwent PHILOS™ osteosynthesis with the MIDS and twenty-three with the DP approach. Follow-up time was 41 months in the MIDS group and 62 months in the DP group, respectively. The median CSS was similar with 79 points in the MIDS group and 82 points in the DP group (p = 0.17). The MIDS group showed a significant lower power measurement in the CSS. In four-part fractures, a substantially lower CSS in absolute numbers in the MIDS group was detected. The median DASH score was 26.7 points in the MIDS group and 25.8 points in the DP group (p = 0.48). There was no difference in the radiological score. More patients with partial avascular necrosis (AVN) were found in the MIDS group, most with three- and four-part fractures. However, this was not statistically significant. Morbidity was similar between groups.

CONCLUSION: The results of the two surgical approaches are statistically comparable. Some differences such as a lower power measurement in the MIDS group, a higher partial AVN frequency and more plate removals are observed. In four-part fractures, the CSS was lower in the MIDS compared to the DP cohort. The MIDS technique might not be a solution for all fracture types, and the surgeon should be careful to analyze the morphology of the fracture before deciding upon the approach. Four-part fractures might be better treated with a DP approach.