Content area
Full text
The authors are from the Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota.
Dr Amanatullah is a 2-time Blue Ribbon Article Award recipient (Orthopedics, November/December 2016). Dr Taunton is a previous Blue Ribbon Article Award recipient (Orthopedics, November/December 2016).
Dr Vasileiadis, Dr Itoigawa, Dr Pulido-Sierra, Dr Crenshaw, Ms Huyber, and Dr Kaufman have no relevant financial relationships to disclose. Dr Amanatullah is a paid consultant for Omni, Exactech, Sanofi, and Blue Jay Mobile Health and has received grants from Acumed, Stryker, and Blue Jay Mobile Health. Dr Taunton is a paid consultant for and receives royalties from DJO Global.
Heterotopic ossification is the formation of mature lamellar bone in nonosseous tissues. It is a common complication after total hip arthroplasty (THA), occurring in 15% to 90% of cases. 1 There are 24 different radiologic classification systems for heterotopic ossification, such as the Brooker, Arcq, DeLee, and Hamblen systems. The Brooker scale ( Figure 1 ) is used in 47% of published research studies. 2,3 However, the Brooker scale does not have adequate intra- or interobserver reliability. 4 The amount of heterotopic ossification that interferes with hip range of motion, classified as Brooker grades III and IV, varies from 7% to 63%. 5-7 Some authors argue that small amounts of heterotopic ossification lead to significant restriction of hip mobility, whereas most believe that only a significant amount of heterotopic ossification interferes with hip mobility. 1,5,8,9
In an attempt to reduce inconsistencies in grading and increase the correlation of radiographic appearance with clinical significance, Della Valle et al 4 proposed a simplified classification system for heterotopic ossification after THA to increase intraobserver reliability and interobserver agreement ( Figure 2 ). However, the reliability of the Della Valle classification has not been independently evaluated. Toom et al 10 attempted to evaluate the interobserver agreement of the Della Valle, Arcq, Brooker, and DeLee classification systems, but their study was grossly under-powered. The current retrospective clinical study compared the reliability of the classic Brooker scale and the Della Valle classification. The Della Valle classification system consists of 3 grades, whereas the Brooker scale consists of 4 grades. The Della Valle classification system provides important information on the size of islands of heterotopic ossification, whereas the Brooker scale does not. The...