Stress fracture of the first metatarsal in a fencer: typical appearance on bone scan and pinhole imaging

Low Positive Predictive Value of Bone Scan to Predict Impending Complete Fracture among Incomplete Atypical Femoral Fracture

BACKGROUND

Although bone scan might be useful to detect incomplete atypical femoral fractures (AFFs) earlier than radiographs, there is no study on predicting further progression to a complete fracture among incomplete AFFs. Our purposes are to determine whether bone scan detects impending complete fracture among incomplete AFFs.

METHODS

We reviewed 18 patients (20 AFFs) who underwent bone scan at the diagnosis of incomplete AFF and were not treated with prophylactic fixation. A diagnosis of impending complete fracture was made, when the femur completely fractured within 6 months after the scan. We correlated radioisotope uptake with the impending complete fracture to calculate sensitivity, specificity, positive predictive value and negative predictive value of bone scan.

RESULTS

Thirteen AFFs (65%, 13/20) showed a positive uptake in bone scan. Among the 13, only one femur was completely fractured within 6 months. None of the 7 femurs without uptake in bone scan fractured. In diagnosing impending complete fracture, the sensitivity of bone scan was 100% and negative predictive value was 100%. However, the specificity (36.8%) and positive predictive value (7.7%) were quite low.

CONCLUSION

Bone scan has no significant role in detecting the impending complete fracture, and a positive uptake does not mean the necessity of prophylactic fixation of incomplete AFF.

(99m)Tc-methylene diphosphonate bone scintigraphy findings in posttransplant distal limb syndrome

We report a case of posttransplant distal limb syndrome (PTDLS) representing a rare complication in kidney transplant recipients characterized by a pain syndrome of the distal extremities. A 68-year-old man with a history of kidney transplantation presented with symmetrical and incapacitating pain in the feet and knees and underwent whole-body Tc-methylene diphosphonate (MDP) scintigraphy for further evaluation. Planar scintigraphy demonstrated marked tracer uptake in the distal femoral and tibial epiphyses, and magnetic resonance imaging showed corresponding osteoedema. Tc-MDP scintigraphy is a valuable tool for evaluation of the etiology of musculoskeletal pain and may demonstrate typical findings in case of PTDLS.