Comparison of effective factors in loss of reduction after locking plate-screw treatment in humerus proximal fractures

BACKGROUND: In proximal humerus fractures, loss of reduction can occur following surgical fixation. The factors that affect loss of reduction in cases treated with locking plates as well as their relationship with the degree of loss of reduction were investigated in this study. METHODS: The study included 48 patients who underwent surgical treatment with a locking plate for a displaced proximal humerus fracture and experienced loss of reduction during follow-up. According to the degree of reduction loss, patients were divided into two groups as low grade and severe loss of reduction. The following parameters were investigated: Head-neck angle, loss of head height, degree of medial support displacement, screw penetration, implant-to-screw ratio, graft use, calcar screw application for medial support, delayed union/nonunion, arthrosis, and avascular necrosis findings. RESULTS: In the early period, in Group I (n=27) and Group II (n=21) patients, the mean head-neck angle was 133°±9.9° (118°–141°) and 131°±11.2° (114°–143°), the distance between the head-plate end points was 8.08±2.8 mm and 11.5±3.1 mm, and the displacement between the medial support fracture fragment was 1.19±0.9 mm and 1.69±1.8 mm, respectively. Furthermore, in the late period, the mean head-neck angle was 120°±11.8° (106°–136°) and 112°±13.1° (98°–120°), the distance between the head-plate end points was 5.6±3.2 mm and 6.3±3.3 mm, and the displacement between the medial support fracture fragment was 2.79±1.9 mm and was 6.79±1.9 mm in Group I and Group II patients, respectively. While there was a significant relationship between the amount of medial displacement and changes in neck-shaft angle (p=0.0313) and humeral head height (p=0.0272), there was no significant relationship between the groups in terms of screw ratios, fracture type, and age. CONCLUSION: Many factors influence loss of reduction in proximal humerus fractures after surgical treatment with a locking plate. Supporting the medial region is particularly critical for maintaining reduction in the post-operative period. Furthermore, a relationship was revealed between the amount of medial displacement and the values of head-neck angle and head height.