Identification of factors related to pain from musculoskeletal injections.

Background: Musculoskeletal injections are a common clinical procedure, often intended to reduce joint or muscular pain in patients. Further identification is warranted to identify additional clinical variables that may lead to increased or decreased pain perception with musculoskeletal injections.

Objective: To examine clinical, demographic, and injection-related factors with patient-perceived pain during musculoskeletal injections, which expands upon prior studies.

Design: Cross-sectional study.

Setting: Retrospective study involving outpatient orthopedic clinics. Consecutive adult patients (age ≥ 18 years) undergoing musculoskeletal injections were reviewed.

Patients: A total of 1371 injections from 935 patients were eligible for the analysis. Exclusion criteria included cognitive disability, non-English-speaking patients, and aphasia.

Interventions: N/A.

Main outcome measures: Patients reported their pre-, intra-, and postprocedural pain on a numerical scale from 0 to 10. Pain scores, demographics, and injection specifics were analyzed after retrospective chart review for their effect on intraprocedural pain.

Results: A total of 1371 injections (62.4% female, mean age 58.6 ± 16.1 years, body mass index 29.6 ± 7.3 kg/m²) were included for analysis. The median intraprocedure pain score was 2. According to the multivariate linear regression model, female gender (B = 0.42; 95% confidence interval [CI] = 0.15-0.69; p < .01), ultrasound image guidance (B = 0.66; 95% CI = 0.22-1.10; p < .01), presence of a trainee (B = 0.44; 95% CI = 0.15-0.73 p < .01), and body mass index (B = 0.04; 95% CI = 0.01-0.06; p < .01) were significantly associated with greater intraprocedure pain score, whereas use of sodium bicarbonate (B = -0.68; 95% CI = -1.01 to -0.35; p < .01), age (B = -0.01; 95% CI = -0.02 to -0.01; p = .04), and injectate volume (B = -0.06; 95% CI = -0.13 to -0.01; p = .04) had significant, inverse associations with intraprocedure pain score. The logistic regression model showed the significant association of presence of trainee (odds ratio = 1.86; 95% CI = 1.23-2.83; p < .01) to intraprocedure pain score of ≥1 (vs. 0).

Conclusions: This study identified clinical and demographic variables associated with worsened injection pain that may improve the counseling and expectations of patients and ideally lead to reduction in experienced procedural pain. Lower pain scores were associated with use of sodium bicarbonate, absence of a trainee, palpation guidance, and male gender of the patient.