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Purpose: Autologous chondrocyte implantation (ACI) in the ankle has become an established procedure to treat osteochondral lesions. However, a non-invasive method able to provide information on the nature of the repair tissue is needed. Recently, MRI T2 mapping was identified as a method capable of qualitatively characterizing articular cartilage. The aim of this study was to evaluate the mid-term results of a series of patients arthroscopically treated by ACI and investigate the nature of the repair tissue by MRI T2 mapping. Methods: Twenty patients, aged 35 ± 8 years, with an osteochondral lesion of the talus, underwent ACI and were evaluated at 5 ± 1 years' follow-up clinically (AOFAS score) and by the MRI T2-mapping sequence. MRI images were acquired using a protocol proposed by the International Cartilage Repair Society, evaluated by the MOCART score and completed by the T2-mapping sequence. Healthy volunteers, mean age 29 ± 6 years, were enrolled, and their T2 map values were used as a control. Their MRI results were then correlated with the clinical score. Results: The AOFAS score increased from 59 ± 16 pre-operatively to 84 ± 18 at follow-up (P < 0.0005). Patients with more than 4 years' follow-up were found to have the most satisfactory results. On the basis of the controls, healthy hyaline cartilage tissue showed a T2 map value of 35-45 ms. A mean T2 map value compatible with normal hyaline cartilage was found in all the cases treated, covering a mean percentage of 69% ± 22 of the repaired lesion area. Conclusions: ACI was able to provide durable results that improved over time. Because of its ability to detect cartilage quality, the MRI T2-mapping sequence integrated with the Mocart score is a valid, non-invasive technique in evaluating the nature of the repair tissue in the ankle joint. Level of evidence: Therapeutic study, Level IV.

Platelet-rich plasma (PRP) is a natural concentrate of autologous blood growth factors experi- mented in different fields of medicine in order to test its potential to enhance tissue regeneration. The aim of our study is to explore this novel approach to treat degenerative lesions of articular cartilage of the knee. One hundred con- secutive patients, affected by chronic degenerative condi- tion of the knee, were treated with PRP intra-articular injections (115 knees treated). The procedure consisted of 150-ml of venous blood collected and twice centrifugated: 3 PRP units of 5 ml each were used for the injections. Patients were clinically prospectively evaluated before and at the end of the treatment, and at 6 and 12 months follow-up. IKDC, objective and subjective, and EQ VAS were used for clinical evaluation. Statistical analysis was performed to evaluate the significance of sex, age, grade of OA and BMI. A sta- tistically significant improvement of all clinical scores was obtained from the basal evaluation to the end of the therapy and at 6-12 months follow-up (P \ 0.0005). The results remained stable from the end of the therapy to 6 months follow up, whereas they became significantly worse at 12 months follow up (P = 0.02), even if still significantly higher respect to the basal level (P \ 0.0005). The pre- liminary results indicate that the treatment with PRP injec- tions is safe and has the potential to reduce pain and improve knee function and quality of live in younger patients with low degree of articular degeneration.

To determine the tibio-femoral and bearing motions in well functioning mobile bearing total knee arthroplasties, a quantitative analysis by means of fluoroscopy was carried out during stair ascending, chair rising-sitting and step up-down motor tasks. Femoral and tibial component positions were obtained using a CAD-model-based shape matching technique. Direct measurement of mobile bearing motion was carried out by tracking previously inserted tantalum beads. A relatively small motion of the bearing was observed. The advantage of self-alignment claimed for the mobile bearing arthroplasty seems to be confirmed by subject-specific ranges of motion exhibited by these patients. It has also been demonstrated that these total knee arthroplasties, which are not fully conforming in flexion, provide little constraint to antero-posterior motion, leading to a kinematic pattern very similar to an ACL deficient knee.