Heterotopic Ossification Prophylaxis After Total Hip Arthroplasty: Randomized Trial of 400 vs 700 cGy.

BACKGROUND: Heterotopic ossification (HO) is a known complication following total hip arthroplasty. Radiation is an effective prophylaxis, but an optimal protocol has yet to be determined. We performed a randomized, double-blinded clinical trial in high-risk patients to determine the efficacy of 400 vs 700 cGy doses of radiation. METHODS: One hundred forty-seven patients undergoing total hip arthroplasty and at high risk for HO at an urban medical center were randomized to receive either a single 400 or 700 cGy dose of radiation postoperatively. High risk was defined as a diagnosis of diffuse idiopathic skeletal hyperostosis, hypertrophic osteoarthritis, ankylosing spondylitis, or history of previous HO. Radiation was administered on the first or second postoperative day. A single blinded reviewer graded radiographs taken immediately postoperatively and at a minimum of 6 months postoperatively using the Brooker classification. Progression was defined as an increase in Brooker classification. Operative data including surgical approach, implant fixation, revision surgery, and postoperative range of motion data were also collected. RESULTS: A significantly greater portion of patients who received the 400 cGy dose demonstrated progression of HO than patients who received the 700 cGy dose. There were no wound complications. No preoperative factors were associated with a higher rate of progression. Patients who progressed had less flexion on physical examination than patients who did not progress, but this was not clinically significant. CONCLUSION: Seven hundred centigray was superior to 400 cGy in preventing HO formation following total hip arthroplasty in high-risk patients and may be the more effective treatment in this population. Further studies comparing 700 cGy to dosages between 400 and 700 cGy may help to clarify if a more optimal dose can be identified.

Isolated revision of the patellar component in total knee arthroplasty.

BACKGROUND: Problems with the patellofemoral articulation are the most common causes of failure after total knee arthroplasty. However, there are few reports describing outcomes following isolated revision of the patellar component. METHODS: Forty knees with a Miller-Galante I prosthesis underwent isolated patellar revision (with or without lateral retinacular release). The Hospital for Special Surgery knee scores were collected prospectively, and radiographs made preoperatively and at the time of the final follow-up were analyzed with respect to alignment, component position, and patellar tracking. Particular attention was given to patients who had a reoperation or repeat revision and who had clinical or radiographic evidence of failure of the patellar revision. RESULTS: At a mean follow-up of sixty-two months, fifteen (38%) of the forty knees that had had an isolated revision of the patellar component failed a second time. Eight of them required a total of twelve additional operations at a mean of forty-nine months after the patellar revision. Three of the failures were severe enough to require revision of two or more of the components. Of the twenty-five knees that had not failed, the average Hospital for Special Surgery knee score at the time of the final follow-up was 87 points. Of the seven knees that did not undergo reoperation but were deemed to be failures on the basis of the patients' symptoms, the average Hospital for Special Surgery knee score at the time of the final follow-up was 72 points. CONCLUSIONS: Isolated patellar revision, with or without concurrent lateral retinacular release, was associated with a high rate of reoperation and a relatively low rate of success. Elements of the implant design and component alignment contributed to the patellar component failure; both should be scrutinized carefully in patients who are seen with this problem, prior to proceeding with isolated revision of the patellar component of a total knee arthroplasty. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.