A Novel Tripod Percutaneous Reconstruction Technique in Periacetabular Lesions Caused by Metastatic Cancer.

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Metastatic lesions in the periacetabular region can cause pain and immobility. Symptomatic patients are often treated surgically with a total hip replacement using various modified Harrington methods. These open surgical procedures confer inherent risks. Prolonged recovery and potential complications may delay adjuvant radiation and systemic therapy. We describe a novel technique for acetabular reconstruction. Three large-bore cannulated screws are placed percutaneously under fluoroscopy in a tripod configuration to reinforce the mechanical axes of the acetabulum. Increased stability improves pain control and permits weight-bearing. Twenty consecutive patients with periacetabular metastases were treated using the tripod technique. Eighteen patients (90%) had Harrington class-III lesions, and 2 patients had Harrington class-II lesions. The mean surgical time was 2.3 hours. Sixteen patients (80%) were able to get out of bed on postoperative day 1. At 3 months postoperatively, there was significant improvement in pain as documented on their visual analog scale (p < 0.01) and in functionality as measured by the Eastern Cooperative Oncology Group score (p < 0.01). The mean follow-up time was 7 months (range, 0.6 to 20 months). At the most recent follow-up, only 3 among the 16 surviving patients were using opioids chronically for pain. Total hip arthroplasty was performed in 4 patients (20%) in a staged fashion using the previously placed screws as support for a cemented cup and obviating the need for a cage device. Of the 16 patients, 15 could walk either independently (6 patients) or using an ambulatory aid (9 patients). Eight patients with the primary tripod reconstruction survived >6 months postoperatively. They were found to have either new bone formation filling the defects or healing of the pathological fractures. There has been no implant loosening or failure. The tripod technique is a novel application to provide safe and effective pain relief in the context of periacetabular metastatic disease. It can be easily converted to support a cemented acetabular cup for a total hip replacement should disease progression occur. This technique provides an alternative to open surgery as currently practiced in these patients. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.