Conservative treatment for chronic coccydynia: a 36-month prospective observational study of 115 patients

Purpose To describe long-term outcomes of conservative treatment for chronic coccydynia. Methods We conducted a 36-month prospective observational study. Adults with chronic coccydynia (> 2 months) were included. The first-line treatment was coccygeal corticosteroid injection. The second-line treatment was either manual therapy or coccygectomy. The primary endpoint was the mean variation from baseline of coccydynia intensity at 6 and 36 months, using a numeric rating scale (0, no pain; 10, maximal pain). Evolution was considered unfavorable when coccydynia intensity was > 3 of 10 points at 36 months or coccygectomy had been performed. We carried out bivariate and multivariate analyses to identify variables associated with an unfavorable evolution. Results We included 115 participants. Mean (SD) age was 43.5 (12.3) years, duration of coccydynia 18.4 (21.6) months and coccydynia intensity 6.5 (2.0) of 10 points. Mean variations for coccydynia intensity were − 1.5 (3.0) at 6 months and − 2.8 (3.2) at 36 months. At 36 months, 59/115 (51%) participants had an unfavorable evolution. In bivariate analysis, posterior coccyx dislocations were numerically more frequent in participants with an unfavorable evolution compared to others (29/59 (48%) versus 17/56 (30%), p = 0.057). In multivariate analysis, longer duration of coccydynia was associated with an unfavorable evolution (OR = 1.04, 95% CI from 1.01 to 1.07, p = 0.023). Conclusion In adults with chronic coccydynia receiving conservative treatment, symptoms decrease overtime, but significantly persist at 36 months in more than half of them. For patients with posterior coccyx dislocation, coccygectomy may be considered rapidly.