Quantitative evaluation of meniscal healing process of degenerative meniscus lesions treated with hyaluronic acid. A clinical and MRI study

Background: The European Society of Sports Traumatology, Knee Surgery & Arthroscopy Meniscus Consensus stated that "arthroscopic partial meniscectomy (APM) shouldn't be proposed as a first line of treatment of degenerative meniscus lesions (DMLs)". However, there is "no evidence of which type/time of non-operative treatment should be proposed". Purpose: The purpose of this study was to evaluate clinical efficacy and healing effects of conservative management of DMLs with a hyaluronic acid (HA) hydrogel. The long-term goal is to be able to treat DMLs conservatively, to avoid APM and prevent the onset of early osteoarthritis. Methods: Patients were subjected to two HA injections two weeks apart. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Patient's Global Assessment (PtGA) and Clinical Observer Global Assessment (CoGA) of the disease were assessed at baseline, 30, and 60 days after treatment. Short Form (36) Health Survey (SF-36) was assessed at baseline and 60 days after treatment. One year after treatment, patients were called to know whether any of them had undergone APM. All patients underwent magnetic resonance imaging using a T2 mapping pulse sequence with multiple echoes, at baseline and 60 days after treatment. T2 measurements provide a quantitative evaluation of qualitative changes in the meniscus. The following meniscus compartments were analyzed according to International Society of Arthroscopy, Knee Surgery and Orthopedic Sports Medicine classification: anterior horn lateral meniscus (AHLAT), anterior horn medial meniscus (AHMED), posterior horn lateral meniscus (PHLAT), and posterior horn medial meniscus (PHMED). As the vascularity and cell profiling are different between the inner and outer meniscus, each compartment was divided into three zones: red, redwhite, white. Non-parametric tests (Fisher's and Wilcoxon test) were conducted to compare pre- and posttreatment data. P-values <0.05 were considered statistically significant. The relationship between clinical evaluation and meniscal healing was assessed using the Pearson's correlation test. Results: 40 patients were enrolled. Patient compliance to treatment was good as all patients completed it. WOMAC score, physical function subscale, PtGA, CoGA, and SF-36 physical functioning and pain score showed a statistically significant difference between baseline and follow-ups (p = 0.024 WOMAC 30 days, p = 0.04 physical function subscale 30 days, p = 0.024 WOMAC 60 days, p = 0.02 physical function subscale 60 days, p = 0.008 PtGA 30 days, p <0.001 CoGA 30 days, p = 0.001 PtGA 60 days, p <0.001 CoGA 60 days, p = 0.01 SF-36 physical functioning, p = 0.03 SF-36 pain score). One year after treatment, only one patient had undergone APM. A decrease in the T2 measurement was detected in the PHMED in 39% of cases in both the red and red–white zone, and in 60% of cases in the white zone; in the PHLAT in 55% of cases in both the red and white zones, and in 65% of cases in the red–white zone. Only for the latter, there was a statistically significant difference between baseline and posttreatment T2 measurements (p = 0.03). Correlation between clinical scores and T2 measurements was noted for some zones of the meniscus (pretreatment CoGA and AHMED red zone p = 0.030, red and white zone p = 0.020, white zone p = 0.054, pretreatment PtGA and AHMED red and white zone p = 0.067, pretreatment SF36 mental health score and PHMED red zone p = 0.036, red and white zone p = 0.018, pretreatment SF36 physical functioning score and PHMED white zone p = 0.048, posttreatment SF36 emotional role functioning and AHLAT white zone p = 0.047, posttreatment SF36 physical functioning score and PHLAT red zone p = 0.038). Conclusion: This is the first study to evaluate the healing of DMLs treated with HA injections in vivo with an objective method such as T2 mapping. This study supports the use of HA in the conservative management of DMLs as it is clinically effective and enhances meniscus healing as demonstrated by T2 measurements. Moreover, it reduces the need for APM at 1-year follow-up, representing a less invasive and cost-effective option compared to APM.