Objective: The purpose of this study was to investigate the effect of hyaluronic acid (HA) in the tendon-bone healing process after rotator cuff repair in a rabbit model.
Methods: In vitro, rat bone marrow stromal cells (rBMSCs) were cultured in media for cartilage-related and inflammation-related gene expression levels examination at 1.0 mg/mL of HA. In vivo, 48 New Zealand white rabbits underwent rotator cuff repair surgery, and they were randomly divided into three groups: (1) control group (n = 16), (2) microfracture (MF) group accepting MF treatment (n = 16) and (3) MF/HA group accepting MF with HA treatment (n = 16). Four rabbits from each group were sacrificed at 6 and 12 weeks postoperatively for histological evaluation and biomechanical testing.
Results: In vitro experiments reveal that HA significantly decreased inflammation-related mRNA expression (IL-1, TNFα) compared with the control group. At 6 weeks after surgery, there was no significant difference of load-to-failure between groups. At 12 weeks after surgery, the mean failure load of the MF/HA group was significantly higher than that of the control group (100.5 ± 10.1 N vs. 68.0 ± 6.2 N; p = 0.0115). The mean failure load of the MF group appeared higher than that of the control group, whereas there was no significant difference (p > 0.05). Histologically, more chondrocytes were clustered at the tendon-bone interface, and more extracellular matrixes were produced in the MF/HA group. The interface of the MF/HA group appeared similar with the normal tendon-bone interface.
Conclusion: HA may play a crucial role in the acceleration of tendon-to-bone healing which might be through inhibiting inflammation. Rotator cuff repair using MF along with HA led to better tendon-bone healing and a subsequent increase of biomechanical strength at the repair site.
The translational potential of this article: HA injection is very common for patients with rotator cuff disease because of its antiinflammatory action and adhesion prevention preoperatively. The HA injection during surgery provides an antiinflammatory effect during tendon-bone healing process and leads to better tendon-bone healing postoperatively.
Keywords: BMSCs; Hyaluronic acid; Rotator cuff repair; Tendon bone healing.