Randomized controlled trial of osteoconductive fixation screws for anterior cruciate ligament reconstruction: a comparison of the Calaxo and Milagro screws.

PURPOSE: To compare the outcome of 2 bioabsorbable screws for tibial interference fixation in anterior cruciate ligament reconstruction with reference to rate of absorption, osteoconductive properties, and clinical outcome. METHODS: Patients undergoing primary anterior cruciate ligament reconstruction with hamstring autograft in a single unit were invited to participate in this study. Patients were randomized to receive either the Calaxo screw (Smith & Nephew, Andover, MA) or Milagro screw (DePuy Mitek, Raynham, MA) for tibial fixation. Patients were reviewed with subjective and objective evaluation by use of the International Knee Documentation Committee form, Lysholm score, KT-1000 arthrometry (MEDmetric, San Diego, CA), and clinical examination. Magnetic resonance imaging was performed at 1 year and computed tomography scanning at 1 week and at 6, 12, and 24 months. RESULTS: Sixty patients agreed to participate in the study, with 32 patients randomized to the Calaxo screw and 28 to the Milagro screw for tibial fixation. There was no significant difference in subjective or objective clinical outcome between the 2 groups. At 24 months, 88% of Calaxo screws showed complete screw resorption compared with 0% of Milagro screws (P < .001). Tibial cysts were present in 88% of the Calaxo group and 7% of the Milagro group (P = .001). At 24 months, the mean volume of new bone formation for the Calaxo group was 21% of original screw volume. Ossification of the Milagro screw was unable to be accurately assessed as a result of incomplete screw resorption. CONCLUSIONS: Both screws showed similar favorable objective and subjective outcomes at 2 years. The Calaxo screw resorbed completely over a period of 6 months and was associated with a high incidence of intra-tunnel cyst formation. The Milagro screw increased in volume over a period of 6 months, followed by a gradual resorption, which was still ongoing at 2 years. Both screws were associated with tunnel widening, and neither showed evidence of significant tunnel ossification. We conclude that, despite satisfactory clinical outcomes, the addition of "osteoconductive" materials to bioabsorbable screws is not associated with bone formation at the screw site at 2 years. LEVEL OF EVIDENCE: Level I, randomized controlled trial.

Long-term survival of high tibial osteotomy for medial compartment osteoarthritis of the knee.

BACKGROUND: The management of degenerative arthritis of the knee in the younger, active patient presents a challenge to the orthopaedic surgeon. Surgical treatment options include high tibial osteotomy (HTO), unicompartmental knee arthroplasty, and total knee arthroplasty. PURPOSE: To examine the long-term survival of closing wedge HTO in a large series of patients up to 19 years after surgery. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Four hundred fifty-five consecutive patients underwent lateral closing wedge HTO for medial compartment osteoarthritis between 1990 and 2001. Between 2008 and 2009, patients were contacted via telephone, and assessment included incidence of further surgery, current body mass index (BMI), Oxford Knee Score, and British Orthopaedic Association Patient Satisfaction Scale. Failure was defined as the need for revision HTO or conversion to unicompartmental knee arthroplasty or total knee arthroplasty. Survival analysis was completed using the Kaplan-Meier method. RESULTS: High tibial osteotomy survival was determined in 413 patients (91%). Of the 397 remaining living patients at the time of final review, 394 (99%) were contacted for follow-up via telephone interview. The probability of survival for HTO at 5, 10, and 15 years was 95%, 79%, and 56%, respectively. Multivariate regression analysis showed that age under 50 years (P = .001), BMI less than 25 (P = .006), and ACL deficiency (P = .03) were associated with better odds of survival. Mean Oxford Knee Score was 40 of 48 (range, 17-48). Overall, 85% of patients were enthusiastic or satisfied, and 84% would undergo HTO again at a mean 12 years of follow-up. CONCLUSION: High tibial osteotomy can be effective for periods longer than 15 years; however, results do deteriorate over time. Age less than 50 years, normal BMI, and ACL deficiency were independent factors associated with improved long-term survival of HTO.