Metastatic Disease of Long Bones Critical Evaluation of Mirels’ Rating System for Impending Pathologic Fractures Timothy A. Damron, MD*; Hannah Morgan, MD*; Dave Prakash, BS*; William Grant, EdD*; Jesse Aronowitz, MD*; and John Heiner, MD** This project examined the hypothesis that Mirels’ rating system for impending pathologic fractures is reproducible, valid, and applicable across va- rious experience levels and training backgrounds. Twelve true clinical histories and corresponding radiographs for patients with femoral metastatic lesions were reviewed by 53 participants from five experience levels: orthopaedic residents, mus- culoskeletal radiologists, orthopaedic attendings, fellowship-trained practicing orthopaedic oncolo- gists, and radiation or medical oncologists. Each examiner provided individual and total Mirels’ scores and independent determination of impend- ing fracture using clinical judgment. A subset of seven histories without prophylactic fixation pro- vided a natural history group. There was highly significant agreement across experience categories for overall Kappa and for the concordance for individual and overall scores. Kappa analysis showed good agreement for site, moderate agree- ment for type, and fair agreement for size and pain. There was no significant difference in overall scores across experience levels. The pooled odds ratio favored Mirels rating system over clinical judgment regardless of experience level. Overall sensitivity was 91% and specificity was 35%. Mi- rels’ system seems to be reproducible, valid, and more sensitive than clinical judgment across ex- perience levels. However, although the system is a valuable screening tool, more specific parameters are needed. Annually in the United States, more than one million new cases of invasive cancer are diag- nosed. Of these, approximately 50% eventually metastasize to bone. 4 Metastatic lesions and destructive bone lesions caused by myeloma and lymphoma, increase the risk of pathologic fractures in affected patients. Because patholo- gic fracture in these already compromised pa- tients can be particularly debilitating, predicting which bones may fracture is a necessary goal. In high risk bones, prevention of fracture may be achieved with radiotherapy, surgery, or medical intervention (bisphosphonates). Prediction of impending pathologic fracture may be challenging. The often quoted classic guidelines for treating lower extremity bone metastases have been attributed to Harrington. 4 CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Number 415S, pp. S201–S207 B 2003 Lippincott Williams & Wilkins, Inc. S201 From the *Departments of Orthopaedics, Radiation Oncolo- gy, and Graduate Medical Education, SUNY-Health Science Center at Syracuse; **Department of Orthopaedics, Univer- sity of Wisconsin. Reprint requests to Timothy A. Damron, MD, Department of Orthopaedic Surgery, Suite #130, 550 Harrison Street, Syracuse, NY 13202. Phone: 315-464-4472; Fax: 315-464- 6446; E-mail: damront@upstate.edu. DOI: 10.1097/01.blo.0000093842.72468.73 Copyr ight © Lippincott Williams & Wilkins. Unauthor iz ed reproduction of this article is prohibited.