Heterotopic ossification in patients with post-traumatic elbow stiffness: 3D analysis of regional distribution features and associated risk factors.

Abstract

The development of heterotopic ossification (HO) is a common yet debilitating complication after elbow injuries and related surgical procedures. We intend to evaluate the regional distribution features of HO around the elbow joint in patients with post-traumatic elbow stiffness (PTES), and explore the independent risk factors for HO development in different regions. Patients who presented with PTES attributed to HO from January 2018 to December 2019 were consecutively enrolled. The pattern of HO distribution was analyzed using Mimics software (Mimics 21.0, Materialise NV, Leuven, Belgium) and classified into 8 distinct regions: anteromedial (AM), anterolateral (AL), posteromedial (PM), posterolateral (PL), posterior (P), medial (M), lateral (L), and proximal radioulnar (PRU) regions. The initial injuries were further categorized based on the presence or absence of 5 fundamental injury types: distal humerus fracture, olecranon fracture, radial head fracture, coronoid fracture, and elbow dislocation. With the occurrence of HO in a specific region as the dependent variable and the initial injury patterns and baseline clinical data as independent variables, logistic regression analyses were conducted to identify the associated independent risk factors for HO development in different regions. A total of 170 patients were included. We identified PM HO in 166 patients (97.6%), P HO in 135 patients (79.4%), PL HO in 128 patients (75.3%), AM HO in 92 patients (54.1%), AL HO in 57 patients (33.5%), PRU HO in 32 patients (18.2%), M HO in 12 patients (7.1%), and L HO in 11 patients (6.5%). The results of logistic regression analyses: (1) AM HO: time interval between the initial injury and this admission ≥1 year (odds ratio [OR] = 2.338), the presence of elbow dislocation (OR = 3.193) and olecranon fracture (OR = 0.305); (2) AL HO: high energy trauma (OR = 2.073) and the presence of olecranon fracture (OR = 0.367); (3) P HO: immobilization for more than 2 weeks after the initial injury or subsequent surgical procedures (OR = 2.466); (4) PL HO: the presence of radial head fracture (OR = 2.805); (5) PRU HO: the presence of radial head fracture (OR = 8.186); (6) PM + P + PL HO: the presence of radial head fracture (OR = 2.235). The regional distribution of HO in patients with PTES exhibits distinct features, and PM HO is observed in almost all patients. The type of initial injury and its subsequent management are closely related to the occurrence and development of HO in different regions. Our findings provide valuable insights and serve as a useful reference for the clinical assessment of HO in patients with PTES.