Bisphosphonate-related complete atypical subtrochanteric femoral fractures: diagnostic utility of radiography.

OBJECTIVE: The objective of our study was to evaluate the diagnostic utility of conventional radiography for diagnosing bisphosphonate-related atypical subtrochanteric femoral fractures. MATERIALS AND METHODS: Retrospective interpretation of 38 radiographs of complete subtrochanteric and diaphyseal femoral fractures in two patient groups-one group being treated with bisphosphonates (19 fractures in 17 patients) and a second group not being treated with bisphosphonates (19 fractures in 19 patients)-was performed by three radiologists. The readers assessed four imaging criteria: focal lateral cortical thickening, transverse fracture, medial femoral spike, and fracture comminution. The odds ratios and the sensitivity, specificity, and accuracy of each imaging criterion as a predictor of bisphosphonate-related fractures were calculated. Similarly, the interobserver agreement and the sensitivity, specificity, and accuracy of diagnosing bisphosphonate-related fractures (i.e., atypical femoral fractures) were determined for the three readers. RESULTS: Among the candidate predictors of bisphosphonate-related fractures, focal lateral cortical thickening and transverse fracture had the highest odds ratios (76.4 and 10.1, respectively). Medial spike and comminution had odd ratios of 3.8 and 0.63, respectively. Focal lateral cortical thickening and transverse fracture were also the most accurate factors for detecting bisphosphonate-related fractures for all readers. The sensitivity, specificity, and overall accuracy for diagnosing bisphosphonate-related fractures were 94.7%, 100%, and 97.4% for reader 1; 94.7%, 68.4%, and 81.6% for reader 2; and 89.5%, 89.5%, and 89.5% for reader 3, respectively. The interobserver agreement was substantial (κ > 0.61). CONCLUSION: Radiographs are reliable for distinguishing between complete femoral fractures related to bisphosphonate use and those not related to bisphosphonate use. Focal lateral cortical thickening and transverse fracture are the most dependable signs, showing high odds ratios and the highest accuracy for diagnosing these fractures.

Correlation of MRI Appearance of Autologous Chondrocyte Implantation in the Ankle with Clinical Outcome.

The objective of this study was to characterize magnetic resonance imaging (MRI) findings and correlate with clinical results in patients who underwent autologous chondrocyte implantation (ACI) of osteochondral lesions of the talus (OLT). METHODS: Twenty-four grafts were evaluated at a mean 65.8 months after ACI for OLT. MRI was performed on a 1.5-T GE scanner using multiple sequences. Graft appearance was compared with preoperative MRI and evaluated for 6 criteria: defect fill, surface regularity, signal pattern, bone marrow edema, subchondral plate irregularity, and presence of cystic lesions. Clinical outcome was measured with the American Orthopaedic Foot and Ankle Society (AOFAS) clinical outcome score. RESULTS: Of 24 grafts, 22 (92%) demonstrated >75% defect fill. Eighteen (75%) had a mildly irregular and 6 (25%) had a moderately irregular articular surface. The signal pattern of the repair tissue was heterogenous in 23 (96%); 14 (58%) layered and 9 (38%) mottled. Fourteen grafts (58%) showed decreased amount of bone marrow edema while 4 (17%) had no change and 5 (21%) had an increase in the amount of bone marrow edema. The subchondral bone plate was abnormal in most grafts, with focal defects seen in 10, slight depression in 7, and both in 5. Seven had an increase in cystic lesions while the others had no change, decrease or no cysts seen. Mean postoperative AOFAS score was 87.5 with mean improvement of 39.4. CONCLUSIONS: At 66-month mean follow-up, MRI appearance of the ACI grafts show imaging abnormalities but demonstrate good clinical results. While MRI is an important tool in the postoperative assessment of ACI grafts, the various variations from a normal/nonoperative ankle must be interpreted with caution.