Lisa C. Howard MD1 and Jason W. Pollock MD2 1Department of Orthopaedics, University of British Columbia, Vancouver, BC, Canada 2University of Ottawa, Ottawa, ON, Canada The AMF is an important structure to varus posteromedial elbow stability. Understanding the evidence‐based indications for operative and nonoperative treatment is important in properly managing these fractures. AMF fractures can be difficult injuries to diagnose and treat. They are often associated with ligamentous injuries that also often require surgical management. If not appropriately treated, they may be associated with poor outcomes, including ulnohumeral arthritis, with limited options for future management. Nonoperative management, however, can be considered in patients that meet specific injury criteria.1,2 Understanding the implications of operative and nonoperative treatment is essential. O’Driscoll classification separates coronoid fractures into three types with subdivisions. Type I fractures involve the tip, type II fractures involve the AMF while type III involve the base. Type II fractures are further subdivided into those involving the rim, the rim and AMF, and those involving the sublime tubercle.3 No level I or II evidence was found, and only one study, a retrospective cohort classified as level III,4 while the remainder of the literature are case series with low patient numbers or biomechanical studies.1,5–8 Doornberg et al. followed 18 patients with AMF fractures (O’Driscoll subtype I in one case, subtype II in three cases and subtype III in 13 cases).4 Fifteen of the cases had associated LCL injuries with two medial collateral ligament (MCL) injuries. Nine patients were treated with coronoid fixation and LCL reconstruction. Functional results were good or excellent in all but one patient with an average Bryan–Morrey elbow score of 97 and range of movement (ROM) of 131° (range 108–145°) and without instability. The other nine patients were characterized with either non‐ or tenuous fixation of the AMF. Average ROM of this group was 99° (30–140°) with an average score of 83. Seven of these patients had persistent instability in which six developed arthrosis. The authors concluded that all AMF fractures should be addressed surgically, even when small. Pollock et al. biomechanically tested the stability of 10 cadaver elbows under varus and valgus gravitational loading with simulated type II (all subtypes) AMF fractures.8 They found isolated LCL repair did stabilize the elbow with subtype I factures 2.5 mm or smaller. However, in the presence of 5 mm subtype I fractures, LCL repair alone did not achieve stability in the varus position (6.2° ± 4.5° internal rotation compared to 3.3° ± 3.1° normal elbow; p <0.05). The authors recommended fixation of AMF fractures larger than 2.5 mm and that LCL repair alone cannot restore normal kinematics in the majority of cases. Park et al. followed 11 patients with isolated AMF fractures consisting of subtypes I–III for an average of 31 months all of which were associated with an LCL injury, while six cases (mostly subtype I and II) also had a concurrent MCL injury.7 Two patients with subtype I were treated with isolated LCL repair while the nine patients with subtypes II and III were treated with buttress plating. They documented a mean ROM of 128° and an average Mayo Elbow Performance Score (MEPS) of 89. Outcomes were classified as good or excellent in 10 patients. Rhyou et al. followed 18 patients with O’Driscoll type II AMF fractures (all subtypes) with or without LCL repair for a mean of 37 months.6 Both cases of subtype I had fragments <5 mm and were treated with isolated LCL repair. Five of the subtype II fractures had open reduction and internal fixation (ORIF) and LCL repair, while six had only ORIF as they were deemed stable to varus and pronation testing after fixation. Two cases had fragments <5 mm and had isolated LCL repairs. Both subtype III fractures were managed with ORIF, while one also had LCL repair. The mean MEPS and Disabilities of the Arm, Shoulder, and Hand (DASH) scores were 98 and 5.6, respectively. There was no statistically significant difference between the outcomes scores, subtype, fixation method, or whether the LCL was repaired. Authors concluded that fragments <5 mm could be treated with isolated LCL repair. They also suggested that even fractures >5 mm with fixation stable to varus testing did not require LCL reconstruction. Chan et al. specifically looked at fracture patterns that could be treated nonoperatively.1 Nonoperative treatment was considered if there was concentric joint location, no block to mechanical rotation, a small coronoid fracture and a stable ROM arc to 30° of extension. Nine were classified as subtype II, while one was subtype III with an average size and displacement of 5 and 3 mm, respectively. Early ROM was performed and all outcomes were reported as good to excellent. There was no significant difference between ROM and strength to the contralateral side at a mean follow‐up of 50 months (range 12–81 months). The authors did caution, however, that the nonoperative approach required careful supervision and also cautioned the reliability of proper varus testing in acute elbow injuries.
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Elbow Dislocations
Clinical scenario
Top three questions
Question 1: In patients with AMF fractures, does operative management result in improved outcomes compared to nonoperative management?
Rationale
Clinical comment
Available literature and quality of the evidence
Findings
Resolution of clinical scenario
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