An alphanumeric classification of osteoporotic pelvic ring injuries.

INTRODUCTION: Classification and management of osteoporotic pelvic ring injuries (OPRI) continue to pose a considerable challenge to orthopaedic traumatologists. The currently used fragility fractures of the pelvis (FFP) classification of OPRI has recently been shown to have significant weaknesses. The aim of this study therefore was to propose a new, simple, yet comprehensive alphanumeric classification (ANC) of OPRI and to assess its intra- and interobserver reliability. Furthermore, its potential advantages over the FFP classification are discussed. MATERIALS AND METHODS: One hundred consecutive CT scans from patients with OPRI were evaluated by three orthopaedic traumatologists with varying levels of experience and one musculoskeletal radiologist. Intra- and interobserver reliability of the proposed classification system was assessed using weighted kappa (κ) statistics and percentage agreement. In addition, the Fleiss' kappa statistic was computed to assess interobserver agreement among all four raters. RESULTS: Overall intraobserver reliability of the proposed ANC was substantial [κ ranging from 0.71 to 0.80; percentage agreement: 70% (range, 67-76%)]. Overall interobserver reliability between pairs of raters was substantial as well [κ ranging from 0.61 to 0.68; percentage agreement: 58% (range, 53-61%)]. For ANC types, groups and subgroups, intra- and interobserver reliability were substantial to almost perfect. Interobserver agreement among all four raters was moderate to substantial, with Fleiss' kappa values of 0.48, 0.69, 0.71 and 0.52 for ANC overall, types, groups and subgroups, respectively. CONCLUSION: The proposed ANC of OPRI demonstrated overall reliability comparable to that of the FFP classification. The ANC, however, is simple, more comprehensive, and consistently relates to injury severity.

Inter- and intraobserver reliability and critical analysis of the FFP classification of osteoporotic pelvic ring injuries.

INTRODUCTION: The classification and management of osteoporotic pelvic ring injuries (OPRI) remain challenging. The fragility fractures of the pelvis (FFP) classification system proposed by Rommens and Hofmann constitutes the first comprehensive classification system of OPRI and may contribute to a more thorough assessment and grading of these injuries. The reliability of the FFP classification system, however, has not been evaluated yet. The purpose of this study therefore was to determine the inter- and intraobserver reliability of the FFP classification system and to critically analyse its strengths and weaknesses. MATERIALS AND METHODS: One-hundred pelvic CT scans obtained from a consecutive series of patients aged 70 years and older who sustained a low-energy pelvic ring injury were included in this study. Three orthopaedic traumatologists of varying levels of experience (one experienced pelvic surgeon, one consultant, one resident) and one musculoskeletal radiologist independently classified each OPRI according to the FFP classification in two different sessions. Intra- and interobserver reliability were determined using percentage agreement and Cohen's Kappa coefficients. RESULTS: The observed relative distribution of FFP fracture types was comparable to that reported in the original study by Rommens and Hofmann. Overall interobserver reliability for all 100 cases was moderate with Kappa values from 0.42 to 0.59 (mean percentage agreement: 61% (54%-68%)), while intraobserver reliability was substantial with Kappa values from 0.68 to 0.72 (mean percentage agreement: 77% (76%-78%)). Subgroup analysis revealed lowest reliability for the classification of Type IIc, IIIc and IVb injuries (32 cases). Within this subgroup of combined anterior and posterior OPRI involving a complete nondisplaced or displaced (uni- or bilateral) sacral fracture, Kappa values for interobserver reliability ranged from 0.10 to 0.52, while those for intraobserver reliability ranged from 0.29 to 0.66. CONCLUSION: Overall interobserver reliability of the FFP classification system was moderate, while intraobserver reliability was substantial. Despite the acceptable overall reliability, classification of FFP subtypes involving a complete nondisplaced or displaced sacral fracture showed relatively poor reliability. The latter limits the usefulness of the FFP classification for both clinical and research purposes and needs to be addressed in future studies.