Correlation of radiological parameters with functional outcomes post fixation with proximal humerus locking plates

Proximal humerus fractures account for 4-5% of all fractures in adults and affect females more than males. With the advent of special locking plates, the treatment trend has shifted more towards a surgical approach. These methods have produced good results but very high complications rates have been reported in the literature. This study was undertaken to analyse the radiological parameters which reflect towards a favourable long term functional outcome in order to advance the surgical fixation skills for managing fractures of the proximal part of the humerus.

83 study participants with proximal humerus fracture fixed using proximal humerus locking plates were retrospectively analysed. The radiological parameters studied were neck shaft angle, head shaft angle, head diameter, head height, greater tuberosity to articular surface distance and reduction of the medial hinge with or without placement of calcar screw. The functional parameters assessed were the Constant Murley Score and range of movements of the shoulder joint. The patients were not followed further for the purpose of the study.

The mean Constant Murley Score for the participants was 80.75 ± 8.09 (range 60-90). The participants with good to excellent CM Score had a significantly higher neck shaft angle (107.47 ± 9.74 v/s 124.16 ± 10.68) and (-0.28 ± 0.85 v/s 2.37 ± 2.28), head shaft angle (23.09 ± 4.82 v/s 31.76 ± 7.76), head diameter (40.08 ± 8.63 v/s 45.15 ± 4.73), head height (18.77 ± 1.96 v/s 20.69 ± 2.76) and greater tuberosity to articular surface distance (-0.28±0.85 v/s 2.37±2.28) as compared to the patients with satisfactory and worse CM Score. The patients with a higher neck shaft angle and a maintained subacromial space had a better range of shoulder abduction. A higher rate of valgus collapse was seen with an inadequate medial hinge reduction.

The radiological parameters which can predict towards a good functional outcome are a higher neck shaft angle and head shaft angle, a larger head diameter and head height, a superior position of the greater tuberosity in relation to the articular surface and a good medial hinge reduction.