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Objective: To determine clinical outcome and graft survivorship in patients undergoing autologous chondrocyte implantation (ACI) for the repair of chondral defects of the knee., Design: Prospective cohort study., Setting: 19 centers in the United States., Patients: 50 patients (37 males, 13 females). Mean age was 36 years (range: 19-53). Defects were grade III or IV with a mean size of 4.2 cm 2. All patients had a minimum of 36 months postoperative follow-up., Main Outcome Measurements: Clinician and patient evaluation based on the modified Cincinnati Knee Rating System. Graft failure was defined as replacement or removal of the graft due to mechanical symptoms or pain., Results: Clinician and patient evaluation indicated median improvements of 4 and 5 points, respectively, at 36 months following ACI (p < 0.001). Previous treatment with marrow stimulation techniques and size of defect did not impact the results with ACI. The most common adverse events reported were adhesions and arthrofibrosis and hypertrophic changes. Three patients had graft failure and required reimplantation or treatment with alternative cartilage repair techniques. Kaplan-Meier estimated freedom from graft failure was 94% at 36 months postoperatively (95% CI = 88-100%)., Conclusions: These results of this study indicate excellent graft survivorship using ACI as well as substantial improvement in functional outcome.

Objective: To study risk factors for injury in karate and to establish safety recommendations., Design: Cross-sectional survey of karate injuries., Setting: Shotokan karate clubs in Boston, Massachusetts, Dallas, Texas, and Winnipeg, Manitoba, Canada., Participants: All athletes training at each club received surveys. A total of 114 surveys were analyzed (74% response rate)., Main Outcome Measures: Presence of injuries (requiring any time off from practice), major injuries (requiring at least 7 days off), and multiple injuries (3 or more injuries)., Results: No statistically significant differences were found with respect to sex. For all outcomes, karateka younger than 18 years of age had fewer injuries. The number of karateka with injuries and with multiple injuries increased with belt rank until brown belt, then reached a plateau. Brown and black belts had a greater frequency of major injuries than the lower ranks. Training more than 3 hours per week correlated with an increase in injuries, major injuries, and multiple injuries., Conclusion: Shotokan karate appears to be a safe sport, especially for those younger than 18 years of age. Risk of injury increases significantly when younger karateka of any rank or older karateka of lower ranks train more than 3 hours per week; therefore, to reduce the risk of injury to less than 50%, weekly training should be limited to a maximum of 3 hours in these groups.