Using Double-Contrast CT Arthrography to Confirm Suspected Dissociation of a Cemented Polyethylene Liner in the Setting of Revision Total Hip Arthroplasty: A Case Report.

CASE: A 67-year-old woman who underwent a re-revision of a total hip arthroplasty with a cemented polyethylene liner fell 14 months after surgery. The patient had symptoms of pain and weakness; however, clinical, laboratory, and radiographic evaluation did not disclose fracture, infection, osteolysis, or component migration. Liner dissociation was suspected, and a double-contrast computed tomography (CT) arthrogram confirmed failure at the cement-liner interface. She underwent additional revision surgery and was doing well at the 3-year follow-up. CONCLUSION: Double-contrast CT arthrography confirmed failure at the cement-liner interface and is an effective diagnostic tool in identifying suspected dissociations of cemented polyethylene liners.

CT-guided iliosacral screw placement.

Computed tomography (CT)-guided iliosacral screw placement for posttraumatic instability of that joint is a safe procedure that may be performed in a radiology department. CT guidance allows more accurate screw placement than traditional fluoroscopic imaging in the operating room. This article describes the technique for placing cannulated surgical screws percutaneously across the iliosacral joint in patients with unstable pelvic fractures using CT for guidance. We also discuss the pitfalls of the procedure and the complications.

Results of a computed tomography protocol evaluating distal third tibial shaft fractures to assess noncontiguous malleolar fractures.

BACKGROUND: Intra-articular tibia fractures are reported to occur in 1% to 25% of tibia diaphyseal fractures. The objective of this study was to create a standard protocol to evaluate noncontiguous malleolar fractures associated with distal third tibial diaphyseal fractures using computed tomography (CT). METHODS: Sixty-six patients with 67 distal third tibia fractures were treated at a level one trauma center from December 2005 to November 2007. These patients were then evaluated using a CT protocol to assess the ankle joint. There were 45 men and 21 women with average age of 44 years (range 18-69 years). All films were independently examined by two orthopedic traumatologists and one musculoskeletal radiologist. RESULTS: Twenty-nine of 67 (43%) distal third tibial shaft fractures had associated intra-articular fractures determined by CT scan. There were 23 posterior malleolus fractures, 3 anterolateral fragments, and 3 medial malleolus fractures. Twenty-seven of 29 fractures (93%) were associated with spiral type fracture patterns (p = 0.001). Seventeen of 29 (59%) intra-articular fractures required operative fixation. Seventy-six percent were noncontiguous fractures. The radiologist detected 20 of 29 (69%) intra-articular fractures using high-resolution monitors, and the orthopedic surgeons averaged 13 of 29 (45%) using initial injury radiographs in the emergency department. CONCLUSION: Plain radiographs are often insufficient for detecting posterior malleolus fractures in conjunction with ipsilateral distal third diaphyseal tibia fractures. Using a preoperative CT protocol for tibial shaft fractures can significantly improve the ability to diagnose associated intra-articular fractures that may not be evident on plain radiographs. Knowledge of these associated intra-articular fractures may prompt fracture stabilization and can prevent displacement during intramedullary nailing of tibia shaft fractures.

CT-guided iliosacral screw placement: technique and clinical experience.

OBJECTIVE: The purpose of this study was to describe the technique of and experience in using CT guidance for percutaneous iliosacral screw placement in patients with unstable pelvic fractures. CONCLUSION: CT-guided iliosacral screw placement is a safe and accurate procedure that can be performed by radiologists in a radiology suite.

Fatigue fracture of the sacrum in an adolescent.

There are relatively few reports of sacral stress fractures in children. In adolescents, sacral stress fractures have been reported in patients involved in vigorous athletic activity. Recognition of these fractures is important to avoid unnecessary biopsy if the findings are confused with tumor or infection. We report a sacral fatigue fracture in a 15-year-old without a history of athletic participation or trauma.

Correlation of joint fluid and internal derangement on knee MRI.

OBJECTIVE: To test the hypothesis that in symptomatic patients, knees in which MRI examinations demonstrate no significant effusion will also be free of internal derangement. DESIGN AND PATIENTS: One hundred and fifteen knee MRI examinations performed between March 2002 and June 2002 at our institution were retrospectively reviewed, evaluating for both the presence of knee effusions and concurrent internal derangement. The amount of joint fluid was measured quantitatively by obtaining anteroposterior measurements in the midline and lateral aspects of the suprapatellar pouch using sagittal MR images. These measurements were then correlated with presence or absence of MRI-demonstrated internal derangement and statistical analysis was performed. RESULTS: Of the 115 knee MRI examinations evaluated, 47 (41%) were negative for internal derangement and 68 (59%) were positive for internal derangement. Thirty-six of 115 (31%) examinations showed joint fluid with anteroposterior measurement of 10 mm or less in the lateral aspect of the suprapatellar pouch. Of these, 31 (86%) showed no concurrent internal derangement. Statistical analysis was also performed using other lateral suprapatellar pouch cutoff values. CONCLUSION: While knees in which MRI examinations demonstrate no significant effusion are most often free of internal derangement, there remain a significant number which will exhibit internal derangement. An anteroposterior measurement of 10 mm or less in the lateral aspect of the suprapatellar pouch is a reasonable threshold value for distinguishing a physiologic from a pathologic amount of joint fluid.

MRI of tibialis anterior tendon rupture.

Ruptures of the tibialis anterior tendon are rare. We present the clinical histories and MRI findings of three recent male patients with tibialis anterior tendon rupture aged 58-67 years, all of whom presented with pain over the dorsum of the ankle. Two of the three patients presented with complete rupture showing discontinuity of the tendon, thickening of the retracted portion of the tendon, and excess fluid in the tendon sheath. One patient demonstrated a partial tear showing an attenuated tendon with increased surrounding fluid. Although rupture of the tibialis anterior tendon is a rarely reported entity, MRI is a useful modality in the definitive detection and characterization of tibialis anterior tendon ruptures.