In this retrospective study, we assessed the outcome in 99 patients who underwent reconstruction of the lateral ligaments of the ankle for chronic anterolateral instability with a minimum follow-up of 15 years. Two techniques were compared: 54 patients had an anatomical reconstruction (AR group) and 45 had an Evans tenodesis (ET group). They were followed up for 19.9 ± 3.6 years and 21.8 ± 4.6 years, respectively. During follow-up, seven patients in the AR group and 17 in the ET group required a further operation (p = 0.004). At follow-up, significantly more patients (n = 15) in the ET group had limited dorsiflexion than in the AR group (n = 6, p = 0.007) and 18 in the ET group had a positive anterior drawer test compared with seven in the AR group (p = 0002). In the ET group 27 had tenderness on palpation of the ankle compared with 15 in the AR group (p = 0.001). Stress radiographs showed ligamentous laxity significantly more often in the ET group (n = 30) than in the AR group (n = 13, p < 0.001). The mean values for talar tilt and anterior talar translation were significantly higher in the ET group than in the AR group (p < 0.001, p = 0.007, respectively). There were degenerative changes on standard radiographs in 32 patients in the AR group and 35 in the ET group (p = 0.05). Four patients in the ET group had developed severe osteoarthritis compared with none in the AR group (p = 0.025). Assessment of functional stability revealed a mean Karlsson score of 83.7 ± 10.4 points in the AR group and 67.0 ± 15.8 points in the ET group (p < 0.001). According to the Good rating system, 43 patients in the AR group had good or excellent results compared with 15 in the ET group (p < 0.001). Compared with anatomical reconstruction, the Evans tenodesis does not prevent laxity in a large number of patients. Long-standing ligamentous laxity leads to degenerative change in the ankle, resulting in chronic pain, limited dorsiflexion and further operations. The functional result deteriorates more rapidly after the Evans tenodesis than after anatomical reconstruction