ObjectiveTo compare the effectiveness between modified Brostrom method repair and anatomical reconstruction anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) with single fibular tunnel for chronic lateral ankle instability. MethodsTwenty ankle specimens of fresh cadaver were dissected to provide the anatomic data of ATFL and CFL and to observe the neurovascular distribution. Between January 2008 and December 2011, 48 patients (48 ankles) with chronic lateral ankle instability were randomly divided to groups A and B (n=24). The direct repair of ATFL and CFL by modified Brostrom method was performed in group A, and anatomic doublebundle reconstruction of ATFL and CFL with free semitendinosus tendon autograft in group B. There was no significant difference in sex, age, body mass index, injury side, the causes of injury, interval of injury and operation, talar tilt angle, talus forward shift, ankle plantar flexion, dorsiflexion, valgus, varus, American Orthopaedic Foot and Ankle Society (AOFAS) score, and visual analogue score (VAS) between 2 groups (P>0.05). The image parameters and range of motion were compared between 2 groups after operation; AOFAS and VAS scores were used to evaluate the effectiveness. ResultsAll the incisions healed by first intention in 2 groups; no complication of nerve injury, infection, or skin necrosis was observed. All the patients were followed up 2-5 years (mean, 3.4 years); no subtalar stiffness or recurrent instability occurred during follow-up. The talar tilt angle, talus forward shift, AOFAS score, and VAS score were significantly improved at 2 years after operation when compared with preoperative ones in 2 groups (P<0.05). There was no significant difference in range of motion of ankle plantar flexion, dorsiflexion, and ankle valgus, and VAS score between 2 groups (P>0.05), but group B was significantly better than group A in the range of motion of ankle varus, talar tilt angle, talus forward shift, and AOFAS score (P<0.05). In the each item of AOFAS score, there was no significant difference in pain, abnormal gait, support and autonomic function, ankle flexion and extension, hind foot motion, and alignment between 2 groups (P>0.05), but group B was significantly better than group A in walking, maximum walking distance, and ankle stability (P<0.05). ConclusionThe described technique, which involves anatomic double-bundle reconstruction of the ATFL and CFL with single fibular tunnel and modified incision, is a viable option for treating lateral ankle instability, especially for young patients who need high stability and revision.