Factors influencing prognosis of shoulder manipulation under ultrasound-guided cervical nerve root block for frozen shoulder: A retrospective cohort study

Abstract

Background: Although successful clinical outcomes of manipulation under ultrasound-guided cervical nerve root block (MUC) for frozen shoulder have been reported, some cases remain refractory. This study aimed to investigate the prognostic factors of MUC for frozen shoulder. Methods: We retrospectively reviewed 126 frozen shoulders in 113 patients (mean age 52.5±6.7 years) who underwent MUC. We defined frozen shoulder as a limited shoulder range of motion (ROM) (passive forward flexion < 120°, external rotation [ER] < 30°, or internal rotation [IR] lower than L3). Patients fulfilling any one criteria were considered to have frozen shoulder. The ROM, Japanese Orthopaedic Association (JOA) shoulder score, Constant Shoulder (CS) score, and University of California, Los Angeles (UCLA) score were evaluated before and 12 months after MUC. We defined as the refractory clinical outcome (refractory group) included patients who fulfilled any one of the criteria for frozen shoulder 12 months after MUC. We compared patients in the refractory group with those who did not fulfill any criteria (success group). Multiple logistic regression analysis was performed to identify risk factors using the following variables: sex, age, symptom duration before MUC, body mass index, diabetes mellitus (DM), affected side, initial ROM, and initial functional score. Results: Patients who underwent MUC were retrospectively enrolled and divided into a success group (n=112 frozen shoulders in 100 patients) and a refractory group (n=14 frozen shoulders in 13 patients) based on their clinical outcome following MUC. Both the success and refractory groups showed significantly improved ROM and functional scores 12 months after MUC (P<.05). Although all ROM and functional scores before MUC showed no significant difference between the two groups, patients in the refractory group showed significantly inferior outcomes than those in the success group 12 months after MUC (P<.01). Age and the presence of DM were significantly higher in the refractory group (P<.05). Multiple logistic regression analysis revealed that age and the presence of DM were independent risk factors for refractory clinical outcomes after MUC (age; odds ratio 1.1, 95% confidence interval 1.0–1.2. P=.04, DM; odds ratio 9.6, 95% confidence interval 2.0–45.4. P=.004). Conclusions: Higher age and the presence of DM are negative prognostic factors for MUC in frozen shoulder. These results may be useful when counselling patients with higher age and diabetes regarding the outcomes after MUC for frozen shoulder. Level of evidence: Level III retrospective comparison study.