New vs Old - How reliable is the new OTA/AO classification for trochanteric hip fractures?

OBJECTIVE: To evaluate the intra- and interobserver reliability of the 2018 OTA/AO trochanteric hip fracture (THF) classification, compared to the 1983 OTA/AO Muller classification system. To further delineate the reliability of classifying stable and unstable THF utilizing the two classification systems.

DESIGN: Radiographic observational study.

SETTING: Multi-center, one level one and one level two trauma centers.

PARTICIPANTS/PATIENTS: Seventy-three radiographic series of patients treated operatively for THF were evaluated by six orthopeadic surgeons.

INTERVENTION: The OTA/AO THF classification system was applied by each surgeon to 73 cases in 2 independent assessments performed 4 weeks apart. Once by the old classification followed by the new 2018 OTA/AO classification. Each radiographic series included lateral hip and anteroposterior initial radiographs. Eight random cases were duplicated in each of the surveys in order to evaluate the intraobserver reliability.

MAIN OUTCOME MEASUREMENTS: Intra- and interobserver of the group, subgroup and fracture stability classification determined by the interclass coefficient (ICC) and Cohens Kappa values.

RESULTS: The interobserver reliability for the group classification (31A1/A2/A3) was moderate using the new classification whereas substantial agreement was showing using the old classifications (0.49, 0.69 respectively). The reliability of the fracture stability classification was higher using the old classification (0.70 Vs 0.52). Subgroup classifications interobserver agreement was fair for both classification systems, although lower reliability was shown in the old classifications (0.34 Vs 0.31).

CONCLUSION: The new OTA/AO classification has a lower interobserver reliability for THF classification when compared to the old one.

LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.