PMC4897555_01
62-year-old man on bisphosphonate therapy for osseous metastases. Tc99m-MDP anterior and posterior whole body bone scan demonstrates a subtle region of focal uptake at the lateral subtrochanteric aspect of the right femur (arrow). Additional findings include metastatic spine lesions and prior nephrectomy.
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A Tc99m-MDP bone scan demonstrated mildly increased focal uptake in the lateral cortex of the subtrochanteric femoral shaft (Fig. 1).
62-year-old man on bisphosphonate therapy for osseous metastases. AP radiograph of the right femur with a 1 cm bony excrescence projecting from the lateral aspect of the femoral cortex in the subtrochanteric region (arrow), corresponding with the abnormality seen on radionuclide bone scan.
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Subsequent radiographs of the right femur demonstrated mild, diffuse cortical thickening and a triangularly shaped focal ridge or beak projecting from the lateral cortex (Fig. 2).
62-year-old man on bisphosphonate therapy for osseous metastases. Pre-fracture MRI. Ultrafast gradient sequence following administration of gadolinium, performed to re-stage abdominal disease, yields a fortuitous glimpse of abnormally increased marrow signal at the level of the cortical ridge (arrow).
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The lateral cortex was slightly thickened and had a focus of abnormal high signal (Fig. 3), which was thought to be consistent with a metastatic deposit.
62-year-old man on bisphosphonate therapy for osseous metastases. Subtrochanteric femur fracture which extends through the center of the cortical ridge seen on the prior radiographs. The distal component is posteromedially displaced and medially angulated.
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Radiographs of the fracture site showed a simple, transverse, subtrochanteric femoral shaft fracture that extended through the middle of the triangular cortical ridge seen on the earlier radiograph (Fig. 4).
62-year-old man on bisphosphonate therapy for osseous metastases. Subtrochanteric femur fracture MR images A-B. Increased T2 signal consistent with edema at the fracture site and slight cortical thickening at the lateral aspect of the fracture (arrow). No focal lesion or enhancement to suggest neoplasm.
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The MRI demonstrated marrow edema related to the fracture and hemorrhage in the surrounding soft tissues as would be expected following an acute fracture (Fig. 5), but no evidence of an enhancing mass lesion or tumor at the fracture site.
62-year-old man on bisphosphonate therapy for osseous metastases. Postoperative radiograph. Reduced subtrochanteric femur fracture, bridged by a Stryker Gamma 11 x 40 nail that has been locked with a hip screw. Cortical thickening and characteristic ridge at the lateral aspect of the simple, transverse fracture are demonstrated (arrow).
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The patient underwent surgical reduction and internal fixation with a Stryker gamma nail (Fig. 6).
62-year-old man on bisphosphonate therapy for osseous metastases. Subtrochanteric femur fracture 6 weeks after fixation. Calcified callus is present at the fracture site (arrow).
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Follow up radiographs of the fracture site showed exuberant fracture callus (Fig. 7).
62-year-old man on bisphosphonate therapy for osseous metastases. Curettage specimens from fracture site at (A) 20x, and (B) 40x demonstrate fragments of cortex. No osteoclasts are seen in any of the high powered fields reviewed for this patient. No evidence of abnormal bone remodeling or tumor was seen.
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No osteoclasts were evident in any high power field (Fig. 8); a finding thought to be consistent with bisphosphonate therapy.