Abstract: BACKGROUND: Anterior cruciate ligament (ACL) reconstruction can restore the stability of knee joint, reduce the mechanical stress on meniscus and cartilage, and avoid the occurrence and development of secondary injury including traumatic arthritis. However, some studies have shown that ACL reconstruction cannot completely prevent the occurrence and development of osteoarthritis, and significant changes in osteoarthritis can be found in the long-term imaging examination after operation. Therefore, there is still controversy about the role of ACL reconstruction in preventing secondary cartilage damage and secondary osteoarthritis, and the changes in cartilage after ACL reconstruction, especially at early stage after ACL reconstruction, have not been fully elucidated. 
OBJECTIVE: To analyze articular cartilage changes during arthroscopic anterior cruciate ligament reconstruction and second-look arthroscopic evaluation.
METHODS: From July 2015 to July 2016, 50 cases of ACL reconstruction with hamstring tendon and second-look arthroscopic exploration were analyzed retrospectively. The cartilage damage and healing between the ACL reconstruction and second-look exploration were recorded. At the same time, the influence of age on articular cartilage was analyzed. The study protocol was approved by the Ethics Committee of Foshan TCM Hospital with an approval No. 20160315.
RESULTS AND CONCLUSION: No infection, graft absorption and other complications occurred in all patients. During the second-look exploration, the Lysholm score, International Knee Documentation Committee evaluation score, Tegner score and KT-1000 lateral difference were significantly improved compared with those before operation (P < 0.05). During the second-look exploration, the articular cartilage of all patients had a trend of deterioration; except for the medial tibial platform and the lateral femoral condyle, subpatellar, trochlear, medial femoral condyle and tibial lateral platform articular cartilage tissues were significantly worsened compared with those after the initial ACL reconstruction (P < 0.05). There was no significant difference in the condition of articular cartilage between the patients under 30 years and over 30 years old in the initial ACL reconstruction (P > 0.05). During the second-look exploration, the patients with anterior cruciate ligament reconstruction who were 30 years old and above had significantly worse subpatellar, trochlear, medial femoral condyle, lateral femoral condyle and tibial lateral platform cartilage tissues than those under 30 years (P < 0.05). The results suggest that the reconstruction of ACL with autogenous hamstring tendon can achieve better stability and function of the knee joint. However, even in the early postoperative period, osteoarthritis is still progressing. Therefore, it is necessary for patients with ACL reconstruction to pay attention to the progression of osteoarthritis and the appearance of knee joint symptoms.

Key words: arthroscopy,  anterior cruciate ligament,  articular cartilage,  second look,  knee,  age