Image Quiz
A Two-Week History of Hip Pain Ten Years after Total Hip Arthroplasty1
A sixty-two-year-old man presented with a two-week history of intermittent pain in the right hip that occurred primarily with weight-bearing. Ten years previously, he had undergone a right total hip arthroplasty with use of a collarless, cast cobalt-chromium stem (Osteonics, Allendale, New Jersey) that had been inserted with cement. At the time of surgery, he was 170 cm tall and weighed 100 kg. To accommodate the dimensions of the femoral canal, one of the smaller stem sizes (number 5) had been used with a 28-mm-diameter head with a +10-mm neck length. The postoperative course had been uncomplicated, and he was satisfied with the result until the pain developed in the thigh. He reported no known inciting trauma and first noted the pain after walking eighteen holes of golf.
On physical examination, the patient walked with a mild limp. Pain could not be elicited when the limb was moved through an unrestricted functional range of motion or during active straight-leg raising. The wound was unremarkable. On plain radiographs, the component appeared to be well fixed and in good position (Fig. 1). A minimal amount of osteolysis was apparent in acetabular zone 3 of the system described by DeLee and Charnley, but there was very little radiographically discernible polyethylene wear. Our impression was that the patient had soft-tissue irritation, and he was given methylprednisolone (Medrol Dose-Pak; Upjohn, Kalamazoo, Michigan), as he was intolerant of oral nonsteroidal antiinflammatory drugs.
Fig. 1 |
Fig. 1 Anteroposterior (A) and frog-leg lateral (B) radiographs of the hip demonstrate good position of the components and no evidence of focal loosening..
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Approximately three weeks later, the patient returned with the same symptoms. At that time, we performed an aspiration under fluoroscopic control, a bone scan, and a computerized tomography scan of the osteolytic region of the acetabulum. The aspirate from the right hip was negative for infection, and no abnormalities of the construct were noted during fluoroscopy. The computerized tomography scan was not diagnostic of a loss of implant fixation, and no large areas of osteolysis were seen. The bone scan was interpreted by an orthopaedic radiologist, who found no evidence of loosening or stress fracture involving the femur. However, there did appear to be a slight yet perceptible increase in uptake in the metaphyseal region of the right femur.
Therefore, partly on the basis of the investigational work being performed at our institution, we ordered a magnetic resonance imaging scan of the right hip. The imaging was performed with use of a clinical 1.5-T magnetic resonance unit (Signa Horizon LX; General Electric Medical Systems, Milwaukee, Wisconsin). Initial images were made with a body coil with use of an initial coronal fast inversion recovery sequence with a 35-cm field of view, repetition time of 4500 to 5000 msec, effective-echo time of 17 msec, receiver bandwidth of 31.2 to 62.5 kHz (over the entire frequency range), and slice thickness of 5 mm with no interslice gap. Additional coronal, sagittal, and axial fast-spin-echo sequences (Fast Spin Echo XL; General Electric Medical Systems) were made with use of a surface coil (shoulder phased array; Medrad, Indianola, Pennsylvania), with a time to repetition of 3800 to 4000 msec, an echo time of 32 to 37 msec, and a wide receiver bandwidth of 62.5 kHz (Figs. 2 and 3). The field of view ranged from 18 to 20 cm, the slice thickness was 3 to 4 mm with no gap, and the matrix was 512 by 320 to 384 at four excitations, yielding a maximum inplane resolution of 351 µm. Tailored radiofrequency (Tailored RF; General Electric Medical Systems) was performed to further reduce interecho spacing.
Fig. 2 |
Fig. 3 |
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