Objective To explore the diagnosis and treatment of anterior cruciate l igament (ACL) cysts of the knees. Methods The cl inical data were retrospectively analysed from 13 patients with ACL cysts between December 2000 and August 2007. The patients included 7 males and 6 females with an average age of 46.3 years (range, 32-55 years). The locationswere the left knee in 6 cases and the right knee in 7 cases. Seven cases had an obvious history of trauma, 4 cases had a history of chronic injury, and 2 cases had no obvious incentive factor. The disease duration was from 6 to 29 months (mean, 20 months). Anterior drawer test was positive in 1 case, pivot shift test was positive in 1 case, and McMurray test was positive in 3 cases. Six cases were preoperatively diagnosed by MRI. The cysts located near the tibial insertion in 6 cases, between the ACL and the posterior cruciate l igament in 3 cases, and near the femoral attachment in 4 cases. All cysts were arthroscopically resected and had the pathohistological examination. Results The pathohistological examination showed mucoid degeneration of collagen and connective tissues, and the diagnosis result was ACL cyst. All incisions healed by first intention, and no compl ication occurred. Thirteen patients were followed up 2 to 5 years (mean, 2 years and 6 months). The symptoms of arthralgia, swell ing, and interlocking of the affected knees disappeared. At 24 months postoperatively, the anterior drawer test was positive in 1 case, the pivot shift test was positive in 1 case, and McMurray test was positive in 4 cases. There was no recurrence during the follow-up. There were significant differences in the range of motion and Lysholm score between pre- and post-operation (P lt; 0.01). Conclusion ACL cysts may be indicated by simple knee pain, especially when accompanied by l imitation of joint motion without imaging evidence of osteoarthritis. The MRI finding is very important in the diagnosis of ACL cysts, and arthroscopic resection and debridement is the first choice in the treatment of ACL cysts.
Objective To review the recent anatomy and biomechanical research progress of knee posteromedial corner, to analyze deficient aspect, and to predict future research directions. Methods Domestic and international l iterature about the anatomy and function of knee posteromedial corner in recent years was reviewed extensively, at the same time, the biomechanics of corresponding structure was summarized and analyzed. Results The anatomical structures ofknee posteromedial corner included the static stabil ity structures and the dynamic stabil ity structures. The dynamic stabil ity structures were more important, including posterior root of medial meniscus, posterior obl ique l igament, semimembranosus extensions, meniscotibial l igament and obl ique popl iteal l igament. The posterior obl ique l igament was most important structure to contribute to stabil ization of valgus, anterior internal rotation of knee and posterior movement of tibia. Conclusion Anatomical reconstruction of knee posteromedial corner especially the posterior obl ique l igament is the key to the reconstruction of knee posteromedial function stabil ity.