Subcapital hip fractures: the Garden classification should be replaced, not collapsed

Objectives: To evaluate rater agreement for a simple 2-category classification of subcapital hip fractures versus the 4-category Garden classification and to determine the effect of clinician experience on the level Of agreement. Setting: Sunnybrook and Women's Health Sciences Centre, Toronto, a level 1 trauma centre. Method: Eleven raters, with varying levels of clinical experience (3 fellowship-trained orthopedic surgeons, 4 clinical fellows and 4 residents), classified 34 pairs of anteroposterior and lateral radiographs of patients with subcapital hip fractures according to whether the fracture was stable (the fragments move as a unit) or unstable (the fragments move independently), and according to Garden's original 4-category classification. The exercise was repeated 1 month later. The radiographs were obtained from a fracture database to represent a wide spectrum of injury severity. Outcome measures: The level of agreement beyond chance, quantified by use of the SAV statistic of O'Connell and Dobson. Results: The most experienced raters demonstrated almost perfect inter- and intrarater agreement with respect to stable and unstable fractures (SAV > 0.80). The raters demonstrated only fair agreement for the Garden classification (mean SAV 0.64). Even junior clinicians demonstrated substantial agreement regarding fracture stability, with much lower scores for the Garden classification. Collapsing the Garden classification responses into 2 categories (stages I and II v. III and IV) was not synonymous with rater categorization of stable versus unstable. Conclusion: The Garden classification for subcapital hip fractures is unreliable and should be abandoned in favour of categorizing fractures as stable versus unstable.