Comparison of parallel and orthogonal plating techniques and the predictive role of Hounsfield unit values in AO/OTA type 13-C distal humerus fractures in patients over 50.

Abstract

Background/objectives: This study aimed to compare the clinical outcomes of parallel and orthogonal plating in the surgical treatment of AO/OTA type 13-C distal humerus fractures in patients over 50 years of age and to evaluate the predictive role of local bone quality, measured using Hounsfield Unit (HU), on these outcomes.

Methods: In this retrospective study, 80 patients over the age of 50 who underwent surgery for AO/OTA type 13-C distal humerus fractures between 2012 and 2022 were analyzed. Patients were categorized into two groups according to the plating technique: parallel(n = 33) or orthogonal(n = 47). Functional and radiological outcomes were compared, including elbow range of motion, Mayo Elbow Performance Score (MEPS), QuickDASH, time to union, complication and reoperation rates, and presence of post-traumatic osteoarthritis. Bone quality was stratified based on HU measurements obtained from preoperative CT scans, specifically from the largest intact slice of the capitellum and trochlea in the sagittal view and from the axial slice just above the proximal fracture line, using a threshold value of 124.5 HU corresponding to the median HU value of the patient cohort. MEPS and QuickDASH were evaluated at the 12-month postoperative follow-up.

Results: Orthogonal plating was associated with longer union times (p < 0.001), higher complication rates (p = 0.008), and greater incidence of post-traumatic arthrosis (p = 0.027) compared to parallel plating. Subgroup analysis revealed that in patients with HU ≤ 124.5, orthogonal plating was linked to significantly increased nonunion risk (p = 0.03) and longer union times (p < 0.001), whereas parallel plating yielded more consistent results regardless of bone quality. Nonunion was significantly higher in the HU ≤ 124.5 subgroup (p = 0.031), and particularly more frequent in orthogonal plating within this group (p = 0.04).

Conclusion: While both plating techniques provided comparable functional outcomes, orthogonal plating was associated with higher complication and nonunion rates, especially in patients with poor bone quality. This may be attributed to the reduced mechanical stability of orthogonal constructs in osteoporotic bone, which may compromise fixation strength and lead to higher failure rates. HU assessment from routine CT scans may aid in preoperative decision-making to optimize surgical outcomes.