gms | German Medical Science

Objectives: The MRI follow up after cartilage reconstruction using a collagen membrane often shows extended bone marrow edema (BME), sometimes effusion and synovitis. The MRI report frequently causes irritation by the patient, as well by the treating physician. The purpose of the study was to investigate the correlation of the findings in imaging with the clinical outcome.

Methods: 25 consecutive patients (17 male, 8 female, average age 32, range 21 to 58) were included in a prospective cohort study. All patients were treated with an autologous, matrix induced chondrogenesis (AMIC) due to a cartilage defect of the talus larger than 1.5 cm².

The patients were reevaluated at 12 months and between 18 and 48 months postoperative with 3.0 Tesla and 1.5 Tesla (Pdw fat sat, 2 mm slice, high resolution ankle coil, 15 channel). BME was graded from 1 to 4 by two independent MRI radiologists. If clinical symptoms were present, Gadolinium was used as contrast agent. The clinical assessment included the AOFAS score as well as the FFI prior surgery and during the follow up.

Results and Conclusion: During the first year after surgery, a remarkable bone edema was visible in MRI images, which did not show any correlation to clinical symptoms. After 18 months, the bone marrow edema decreased. In 21 of the patients we saw moderate effusion. Partial detachment of the collagen membrane (2 patients) showed a high correlation with increased pain scores in FFI and AOFAS in all follow up examinations. Synovitis in the joint did also show a significant correlation with clinical symptoms (Spearman Rho 0.73). In all patients, independent of symptoms, the area of the reconstructed cartilage was still visible at the last follow up.

1.

Bone marrow edema is a common finding after cartilage reconstruction with a collagen membrane. Especially during the first 12 months the clinical value of the bone marrow edema in MRI should not be overestimated. The correlation with the clinical outcome was poor (Spearman Rho 0.17) .

2.

A partial detachment of the collagen membrane, delamination of cartilage at the edge to the membrane, as well as synovitis are clinical findings in MRI which show a high correlation with pain in the clinical scores.

3.

A normal bone and cartilage signal cannot be expected after cartilage reconstruction, even if clinical scores are excellent.