Diagnostic and therapeutic approach to meniscal ossification: a systematic review

The purpose of this study was to systematically review case reports and case series about meniscal ossicle, to summarize existing evidence. Specifically, to identify the etiology, demographic characteristics, localization, clinical features, diagnostic procedures and treatment options of this rare entity. Although, case reports/ series are of low level of evidence, a systematic review of such studies can provide and help us to gain a better understanding and awareness of meniscal ossicle.

Two authors searched three online databases (MEDLINE, SCOPUS and GOOGLE SCHOLAR) from inception until March 2020 for the literature on meniscal ossicle. Inclusion criteria included case series, case reports and case-based reviews, available in full-text version, in English and that concern humans. Reports published in languages other than English were excluded, as well as articles with no electronic full text availability. Case reports using the term "meniscal ossicle" to describe an acute avulsion fracture of the tibial root of the meniscus, were also excluded.

Of 453 initial studies, 38 studies satisfied inclusion criteria. In total 169 patients were included of whom 107 (63%) were males and 62 (37%) were females. Mean age was 44 years (range 12-87). According to Magnetic resonance imaging findings, in 144 knees (86%) the ossicle was localized at the posterior root or horn of the medial meniscus. 60% of the patients had a history of trauma. The predominant symptom in 87% of patients was knee pain. In all patients was detected an intra-articular density structure in computed radiography. 76% had associated meniscal tear, 61% had intraarticular cartilage loss, 34% meniscal extrusion and 28% anterior cruciate ligament injury. Treatment modalities included conservative regimen in 40 patients, while 59 patients underwent surgical excision.

The most possible etiology of meniscal ossicle is posttraumatic heterotopic ossification and small occult bony avulsion fracture. It is commonly observed in individuals complaining about knee pain with history of antecedent trauma. The presence of a meniscal ossicle should alert the physician to the high likelihood of the patient having an associated meniscal tear, articular cartilage loss, ACL injury or meniscal extrusion. Along with the meniscal ossicle, the associated meniscal tear should be treated as well.