The Effect of Intra-articular Injection of Hyaluronic Acid in Frozen Shoulder: a Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND: Frozen shoulder (FS) is a common progressive disorder that causes restricted motion and refractory pain undermining quality of life. Intra-articular hyaluronic acid (HA) injection is a widely adopted conservative therapy relieving symptomatic FS, whereas the effect of which were contradictory and unclear in current literatures. The aim of the present study is to investigate whether intra-articular HA administration facilitates symptomatic pain relief and functional improvements in patients diagnosed with shoulder FS. METHODS: The PubMed, Embase, Cochrane Library electronic databases and Google scholar were searched, from inception to 15th Jan 2022. Randomized controlled trials (RCTs) comparing intra-articular HA administration with any other non-surgical treatment in patients with FS were included. Risk of bias was evaluated using the Cochrane risk-of-bias tool and meta-analyses were undertaken to pool the data of visual analog scale for pain, range of motion (ROM) in external rotation, abduction, and flexion, as well as Shoulder Pain and Disability Index (SPADI), Constant score and American Shoulder and Elbow Surgeons (ASES). RESULTS: The present study included 7 RCTs involving 504 patients. The results provided no support for superior pain control in patients undergoing HA injection compared with any other treatment (p = 0.75). Furthermore, HA group failed to exert superior improvements to other treatments in ROM concerning abduction (p = 0.69) and flexion (p = 0.33). However, HA injection was observed to facilitate functional recovery in external rotation (p = 0.003). In addition, the pooled data showed a significant higher SPADI score in control group than in HA group (p = 0.01), while no statistical significance between two groups was observed in Constant score (p = 0.36) and ASES (p = 0.76). CONCLUSIONS: The current meta-analysis suggested that HA is a beneficial treatment procedure in improving the ROM of the shoulder for patients with FS, whereas the effect in relieving pain may be equal to the existing therapy. In conclusion, Intra-articular HA injection is recommended for FS patients.