JSES - 2026-05-12 - Journal Article
The Osborne-Cotterill Lesion: A Radiographic Analysis of Morphology & Clinical Impact.
Howse LS, Virani S, Syed L, Khin C, Phadnis J
Topics
Key Takeaway
The Osborne-Cotterill lesion is present in 66% of acute elbow instability cases (120/181), with posterior impaction morphology comprising 86.6% of lesions and avulsion subtype showing stronger association with instability requiring operative treatment.
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Summary
This study quantified OCL incidence and morphology across elbow instability patterns using standardized CT reconstruction with a circle-of-best-fit technique applied to 181 acute elbow instability cases. OCLs were identified in 66% overall, with significantly lower incidence in valgus instability (41%) versus PLRI (72%) and PMRI (71%) patterns (p=0.046). Three anatomical patterns (anterior 1.7%, intermediate 11.7%, posterior 86.6%) and two morphological subtypes (impaction 93.3%, avulsion 6.7%) were defined; only 9 OCLs required direct operative treatment, and no complications were attributable to untreated OCLs.
Key Limitation
The absence of functional outcome data and defined follow-up prevents any conclusion about whether untreated posterior impaction OCLs contribute to recurrent instability or functional deficit over time.
Original Abstract
INTRODUCTION
The Osborne-Cotterill lesion (OCL) is an osseoligamentous injury of the posterolateral capitellum associated with elbow instability. Its contribution to instability remains unclear, and evidence guiding management is limited. This study aimed to quantify the incidence and anatomy of OCLs and to correlate these findings with patterns of elbow instability, treatment, and outcome.
METHODS
A database of acute elbow instability cases was reviewed. After application of exclusion criteria, 181 elbow CT scans were available for analysis. A standardised method was developed to reconstruct scans in the plane of the distal humerus. Data were collected on injury pattern, surgical intervention, and complications. A circle-of-best-fit technique was applied to sagittal cross-sections to template normal capitellar anatomy. Measurements were oriented to the anterior humeral line to describe the OCL. Variables recorded included area of bone loss, angle of involvement, anterior and posterior exit points, and lesion width.
RESULTS
An OCL was identified in 120 elbows (66%), while 61 elbows (34%) demonstrated no bone loss consistent with an OCL. By instability pattern, OCLs were present in 61/85 posterolateral rotatory instability (PLRI) cases (72%), 25/35 posteromedial rotatory instability (PMRI) cases (71%), 25/39 axial instability cases (64%), and 9/22 valgus instability cases (41%). The incidence was significantly lower in valgus injuries (p = 0.046). OCLs were most commonly located in the posterolateral capitellum. Relative to the anterior humeral line, three anatomical patterns were identified: anterior (1.7%), intermediate (11.7%), and posterior (86.6%). Two pathological subtypes were defined by morphology: impaction (93.3%) and avulsion (6.7%). Overall, 114 cases were treated surgically, of which 9 OCLs (7 avulsion, 2 impaction) underwent operative treatment directed at the lesion itself. There were 17 complications, including recurrent instability in 7 patients. No complications were directly attributable to an untreated OCL.
CONCLUSION
This is the first study to quantify the incidence and morphological characteristics of OCLs in a large cohort. Based on these findings, three anatomical patterns (anterior, intermediate, and posterior) and two pathological subtypes (avulsion and impaction) are proposed. Most OCLs were posterior impaction lesions treated non-operatively. Avulsion lesions, and OCLs located anteriorly or intermediately, were less common but appeared more strongly associated with instability and may warrant consideration for surgical treatment.