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Periprosthetic osteolysis is a well known phenomenon caused by wear particle-induced bone resorption, particularly common and extensively reported in total hip arthroplasty. Its typical radiographic feature is a radiolucent area adjacent to an implant, sometimes associated with a soft tissue mass. Osteolytic changes may be caused by numerous other pathologic processes, including infection, metabolic disease, and neoplasia. Four cases of massive periprosthetic bone destruction associated with a large soft tissue mass around a failed total hip replacement are presented. In three cases, a diagnosis of periprosthetic osteolysis was correctly made and managed by revision surgery. However, in one case angiosarcoma of the ipsilateral hemipelvis went long unrecognized despite aggressive clinical course, requiring hind-quarter amputation and ultimately resulting in the patient's death. Periprosthetic malignancy in the form of either primary sarcoma or metastatic cancer is a very rare yet reported event in the setting of previous hip replacement, likely leading to catastrophic consequences when diagnosis is not established in a timely manner. The differential diagnosis of periprosthetic osteolysis should consider the entire spectrum of conditions that can present with radiolucent changes. Thorough review of patient's history and course of symptoms, along with careful evaluation of standard roentgenograms should be always performed and possibly integrated with imaging modalities such as CT, MRI, and bone scintigraphy in order to increase diagnostic accuracy. If uncertainty remains, biopsy should always be considered to rule out malignancy.

BACKGROUND:Phantom limb syndrome (PLS) is common after limb amputations, involving up to 90% of amputees. Although many different therapies have been evaluated, none has been found to be highly effective. Therefore, we evaluated the efficacy of a prolonged perineural infusion of a high concentration of local anesthetic solution in preventing PLS. METHODS:A perineural catheter was placed immediately before or during surgery in 71 patients undergoing lower extremity amputation. A continuous infusion of 0.5% ropivacaine was started intraoperatively at 5 mL/h using an elastomeric (nonelectronic) pump, and continued for 4 to 83 days after surgery. PLS was evaluated on the first postoperative day and then 1, 2, 3, and 4 weeks, and 3, 6, 9, and 12 months after surgery. To evaluate the presence and severity of PLS while the patient was receiving the ropivacaine infusion, it was discontinued for 6 to 12 hours before each assessment period (i.e., until the sensation in the extremity returned). The severity of phantom limb and stump pain was assessed using a 5-point verbal rating scale (VRS), with 0 = no pain to 4 = intolerable pain, and "phantom" sensations were recorded as present or absent. If the VRS score was >1 or significant phantom sensations were present, the ropivacaine infusion was immediately restarted at 5 mL/h. If the VRS score remained at 0 to 1 and the patient had not experienced phantom sensations for 48 hours, the infusion was permanently discontinued and the catheter was removed. RESULTS:Median duration of the local anesthetic infusion was 30 days (95% confidence interval, 25-30 days). On postoperative day 1, 73% of the patients complained of severe-to-intolerable pain (visual analog scale >2). However, the incidence of severe-to-intolerable phantom limb pain was only 3% at the end of the 12-month evaluation period. At the end of the 12-month period, the percentage of patients with VRS pain scores were 0 = 84%, 1 = 10%, 2 = 3%, 3 = 3%, and 4 = none. However, phantom limb sensations were present in 39% of patients at the end of the 12-month evaluation period. All patients were able to manage the elastomeric catheter infusion system at home. CONCLUSION/CONCLUSIONS:Use of a prolonged postoperative perineural infusion of ropivacaine 0.5% seems to be an effective therapy for the treatment of phantom limb pain and sensations after lower extremity amputation.