[Application of channel-assisted minimally invasive repair system in Myerson types Ⅰand Ⅱ chronic Achilles tendon rupture].

Objective To investigate the effectiveness of channel-assisted minimally invasive repair system (CAMIR) in treatment of the Myerson types Ⅰ and Ⅱchronic Achilles tendon rupture. Methods Between May 2016 and August 2017, 19 patients with Myerson types Ⅰ and Ⅱchronic Achilles tendon ruptures were treated with CAMIR. There were 14 males and 5 females, aged from 21 to 48 years, with an average age of 34.5 years. The disease duration was 5-9 weeks (mean, 7.5 weeks). The preoperative Thompson tests of affected ankles showed positive. There were 11 cases of Myerson type Ⅰwith the gaps of Achilles tendon defect of 1-2 cm (mean, 1.58 cm), and 8 cases of Myerson type Ⅱwith the gaps of Achilles tendon defect of 2.5-4.0 cm (mean, 3.16 cm). The ankle dorsiflexion and plantarflexion range of motion were measured before and after operation; the American Orthopedic Foot and Ankle Society (AOFAS) ankle and hindfoot score was used to assess the patients' ankle joint function. Results No major blood vessels, nerves, and other tissue structures were damaged during the operation; 3 cases of Myerson type Ⅰ were converted to Myerson type Ⅱ according to the gaps of the defect after the scar tissue was removed during the operation. After operation, the depressed part of the Achilles tendon disappeared, the continuity of the tendon was restored, and the Thompson tests were negative. All 19 patients were followed up 12-25 months, with an average of 14 months. All incisions healed by first intention, and no infection and skin necrosis occurred; all the pre-injury activities and exercise were restored at 6 months after operation. During the follow-up period, no heel pain or re-rupture occurred. At last follow-up, except that there was no significant difference in ankle dorsiflexion range of motion of Myerson type Ⅰ patients ( t=2.118, P=0.071), the AOFAS ankle and hindfoot score, ankle plantarflexion range of motion of Myerson types Ⅰ and Ⅱ patients, and ankle dorsiflexion range of motion of Myerson type Ⅱ patients were significantly improved when compared with preoperative values ( P<0.05). According to AOFAS ankle and hindfoot function score, the ankle joint function of type Ⅰ patients was excellent in 7 cases and good in 1 case, and of type Ⅱ patients were excellent in 8 cases, good in 2 cases, and fair in 1 case. Conclusion CAMIR is safe and effective in the treatment of Myerson types Ⅰ and Ⅱ chronic Achilles tendon rupture with fewer complications and better functional recovery of ankle joint.