The patient presented with a suspected tear of the medial meniscus of the right knee, with a diffuse pain. Plain radiographs revealed a large ossified body within the knee. MRI examinations were also performed.
The patient presented with a suspected tear of the medial meniscus of the right knee, with a diffuse pain. Plain radiographs revealed a large ossified body projected in the posterior-medial aspect of the knee. MRI examinations were performed on a transmit-receive extremity coil on a 0.5T system.
The tear of the medial meniscus was confirmed. Furthermore, two rounded bodies were identified in the posterior-medial aspect of the knee, with smooth edges and signal equivalent to bone. During arthroscopic examination, the presence of two meniscal ossicles was demonstrated.
Meniscal ossicles represent a rare skeletal abnormality of the knee constituted by an area of ossification in the meniscus. The patients affected are generally young and male. The maximum diameter of the meniscal ossicles ranged from 7 to 10 mm and they are most frequently single and located within the posterior horn of medial meniscus [1,2]. Four principal theories have been proposed to explain their etiology: the result of a degenerative phenomenon due to a weak nutrition of the fibro-cartilage; the outcome of an acquired lesion of the meniscus; the persistence of vestigial structures or the result of an avulsion of the tibial plateau in the attachment point of meniscal posterior horn [3,4]. They are rarely asymptomatic; most frequently they associate to intense and diffuse pain, swelling and articular locking; instead, some Authors suggest that meniscal ossicles are symptomatic only when they alter the meniscal profile, determining longitudinal tears. The therapy is controversial. Some Authors [1] propose, if the patient is symptomatic, arthroscopy or arthrotomy, others suggests a conservative approach; meniscal ossicles, instead, should not be resected if the patient is asymptomatic [4]. Therefore, to plan an appropriate therapy and to avoid unecessary surgery, is important to make a correct diagnosis. Standard, antero-posterior and lateral conventional radiographs are the initial imaging modality for the diagnostic assessment of patients with knee pain. Meniscal ossicles appears as rounded or triangular calcific densities with trabecular structure of cancellous bone, which is useful to distinguish them from the most common pathologic conditions more often present within the meniscus ( meniscal calcifications in calcium pyrophosphate dihydrate crystal deposition disease, osteochondral loose bodies and osteochondritis dissecans ) [3,5]. When plain radiographs shows a defect on the femoral articular cartilage, also intra-articular loose bodies and osteochondritis dissecans have to be distinguished from meniscal ossicles. In previous reports, some Authors [1,3,4] consider that fluoroscopic examination is useful. May be difficult to diffentiate the meniscal ossicle from other pathologic meniscal calcification if the cartilaginous or osseous defect is not detectable; in this cases is helpful the tunnel projection, with 30-40° flexion of the knee. In MR images the meniscal ossicles appear as structures with variable shape and size, smooth and regular edges, within the meniscus, with signal characteristics identical to those of medullary bone: high signal intensity on T1 weighted, moderately high signal intensity on T2 weighted images that decreased on fat saturation sequences. In some cases, like the one mentioned above, meniscal ossicle may show low signal intensity on Gradient-echo T2W images, this is presumably due to susceptibility perhaps on account of increased trabeculation within the ossicle compared to the normal bone. In agreement with some Authors we suggest that MRI is useful in differential diagnosis between meniscal ossicles and loose bodies, osteochondritis dissecans, meniscal calcification and semimembranous and popliteal tendon avulsions because, in these entities, bony fragments are located outside of meniscal fibro-cartilage. MRI is also useful in detecting meniscal tears and eventually ligamental lesions, associated with meniscal ossicles, without specific symptoms [2,5].
Meniscal ossicles
Based on the X-ray anteroposterior and lateral views and MRI examination, the main findings are as follows:
Taking into account the patient’s age, symptoms (diffuse knee pain), and imaging findings (a smooth-edged, bony lesion within the posterior horn of the medial meniscus), the following differential diagnoses should be considered:
Integrating the patient’s age, clinical presentation (pain on the medial side of the right knee, possible history of meniscal injury), and imaging findings (X-ray and MRI showing a small bony density within the posterior horn of the medial meniscus, with signal characteristics resembling normal cancellous bone and well-defined borders), the most likely diagnosis is:
Meniscal Ossicle.
Arthroscopic evaluation or histopathological examination could provide further confirmation. It is also important to rule out any concomitant meniscal tear or ligament injury.
A treatment strategy should be developed based on the severity of the patient’s symptoms, the stability of the meniscus, and the degree of mechanical irritation caused by the ossicle.
Rehabilitation Exercises (Based on the FITT-VP Principle):
Throughout the rehabilitation program, monitor for pain and swelling. If acute symptoms worsen, reduce or pause training intensity and seek medical evaluation.
Disclaimer:
This report is for medical reference only and cannot replace a face-to-face consultation or the advice of a qualified healthcare provider. The patient’s specific treatment and rehabilitation protocols should be determined by specialist physicians or professional medical teams based on individual circumstances and additional diagnostic results.
Meniscal ossicles
