Inter- and intra-observer reliability of the new AO/OTA classification of proximal femur fractures. Issue 6 (June 2021)

• Record Type: Journal Article
• Authors: Chan, G.; Hughes, K.; Barakat, A.; Edres, K.; da Assuncao, R.; Page, P.; Dawe, E.
• Is Part Of: Injury. Volume 52:Issue 6(2021)
• Page Start: 1434
• Page End: 1437
• Publication Date: 2021-06
• Subjects: Hip fracture -- Classification -- Inter-observer -- Intra-observer; Wounds and injuries -- Surgery -- Periodicals; Accidents -- Periodicals; Wounds and Injuries -- surgery -- Periodicals; Lésions et blessures -- Chirurgie -- Périodiques; Electronic journals; Electronic journals; 617.1
• DOI: 10.1016/j.injury.2020.10.067
• Languages: English
• ISSNs: 0020-1383

Abstract

Highlights: The 2018 AO/OTA classification has a "moderate" inter-observer reliability at group (e.g. 31-A1) level, this reduces to "fair" reliability at sub-group (e.g. 31-A1.1) with sub-group classifications. Intra-observer reliability is comparably higher than inter-observer reliability being "substantial" to "moderate". Despite attempts to simplify and re-define inter-trochanteric fractures, the 2018 AO/OTA classification remains difficult to apply consistently and reliably. Abstract: Introduction: Hip fractures are a global health burden, with an incidence that is projected to increase from 66, 000/year currently in the United Kingdom to 100, 000/year by 2033. The classification of intertrochanteric fractures is key to the treatment algorithms advising on their surgical management. The AO/OTA classification is the most commonly used system, initially published in 1990 and subsequently shown to have poor inter- and intra-observer reliability, it was revised in 2018 with the main aim of re-classifying and further defining the 31-A2 group. Methods: 150 plain film anteroposterior and lateral plain film radiographs of intertrochanteric fractures from three hospitals were classified using the 2018 AO/OTA classification of intertrochanteric fractures by six Orthopaedic Surgeons (2 Consultants, 4 Trainees), all were blinded to the definitive surgical treatment for patients. Radiographs were re-classified after a minimum of 3-months, Cohen's Kappa for inter-observer reliability was calculated from first round classifications and intra-observer reliability from first and second classifications. Results: Mean Kappa for inter-observer reliability for AO group classification (e.g. 31-A1) was 0.479 (0.220 - 0.771, for sub-group classification (e.g. 31-A1.1) reliability reduced to 0.376 (0.276 - 0.613). Intra-observer reliability was comparable for both group and sub-group classifications, 0.661 and 0.587 respectively. Conclusions: The revised 2018 AO/OTA classification aimed to simply the classification of intertrochanteric fractures, however it remains unreliable with only a "moderate" inter-observer reliability at group level with this falling to "fair" when sub-group classifications are made. Identification of stable and unstable injuries using the new AO/OTA system remains fraught with difficulties and appears difficult to apply with consistent accuracy.