Cysts of the anterior horn lateral meniscus and the ACL: is there a relationship?

Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). The common insertion of the anterior cruciate ligament (ACL) and the AHLM root may provide a pathway for disease. The purpose of our study was to determine if cysts of the ACL are the origin of cysts adjacent to the AHLM. Materials and methods Radiology reports of all magnetic resonance (MR) examinations of the knee over a 7-year period were searched for “cyst”, “ganglion”, and “ganglia”. Two fellowship-trained musculoskeletal radiologists independently reviewed those MR examinations reported to have a possible cyst of the AHLM and/or the ACL. The study group consisted of those patients with a cyst located adjacent to the AHLM but no meniscal tear of the adjacent meniscus. The ACL in each of these patients was evaluated for the presence of a cyst. Comparison with age- and gender-matched controls was performed. Results Of 708 cases that contained the word “cyst”, “ganglion”, or “ganglia”, 121 reports indicated a possible cyst of the ACL or AHLM. Twelve individuals had a cyst located adjacent to the AHLM with no meniscal tear. Six (50%) of these individuals had a cyst of the ACL; no ACL cysts were identified in the control group ( p = 0.014). Interreader agreement for AHLM parameniscal cysts and AHLM tears was substantial. Conclusions Our results suggest that cysts adjacent to the AHLM may in part be explained by cysts or ganglia of the ACL.