Incidence of post-traumatic osteoarthritis in olecranon fractures and the role of instability and comminution in its development: a systematic review

Olecranon fractures are common fractures of the elbow and may lead to symptomatic post-traumatic osteoarthritis (OA). The incidence and risk factors for ulnohumeral OA after an olecranon fracture remain uncertain. Therefore, this review aimed to: (1) determine the incidence of OA following isolated olecranon fractures, (2) assess the role of instability and comminution in the development of OA, and (3) assess the impact of OA on patient-reported outcome measures. Multiple medical databases were searched for studies containing the terms "olecranon", "osteoarthritis", and "fracture". Studies were screened for predetermined inclusion and exclusion criteria, including a minimum follow-up of 24 months and radiographic assessment of OA. Patient and treatment characteristics were collected alongside clinical and functional outcomes. The studies' methodological quality was assessed using the Methodological Index for Non-randomized Studies (MINORS) criteria. The Mayo classification was used to assess olecranon fractures for comminution and instability, categorizing them into 3 types: type 1 (nondisplaced, stable), type 2 (displaced, stable), and type 3 (displaced, unstable). Each type is subdivided into A (noncomminuted) or B (comminuted). Due to a high degree of heterogeneity, pooling of the data was avoided; instead, results were summarized using ranges, medians, and interquartile ranges. Eleven studies were included, comprising a total of 362 patients with a median follow-up of 41 months (range: 27-240; interquartile range [IQR]: 29-74). The MINORS scores for these studies ranged from poor to moderate. The median OA incidence across these studies was 19% (range: 0%-35%; IQR: 3%-26%). The median OA incidence was 25% (range: 0%-50%; IQR: 13%-38%) for Mayo type 1 fractures, 16% (range: 0%-30%; IQR: 0%-25%) for type 2, and 50% (range: 40%-100%; IQR: 45%-75%) for type 3. For noncomminuted fractures (type 2A), the median OA incidence was 16% (range: 0%-28%; IQR: 0%-18%), while for comminuted fractures (type 2B), the median was 24% (range: 0%-38%; IQR: 17%-30%). Mayo Elbow Performance Scores for patients with OA were reported in 3 studies with a median score of 93 (range: 83-94). The median Mayo Elbow Performance Score across all included studies was 92 (range: 86-98; IQR: 90-96). This review identified a median OA incidence of 19% at a median follow-up of 41 months following isolated olecranon fractures. However, final patient-reported outcome measures ranged from good to excellent regardless of fracture type or the presence of OA. Given that all studies were heterogeneous and of poor to moderate quality, additional larger studies with preferably prospective designs are needed to assess if comminution or instability affects the development of ulnohumeral OA even after appropriate surgical treatment.