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Objective:
Osteomyelitis (OM) and septic arthritis (SA) of the pubic symphysis (PS) are rare but severe infectious processes. The purpose of this study is to determine the type, if any, and timing of prostate interventions relative to the imaging diagnosis of OM/SA of the PS.

Materials and Methods:
An IRB-exempt, HIPPA compliant retrospective review of men patients with pelvic CT or MR across multiple sites of a single institution over a 10-year period (2012-2022) was performed. The radiology report database was searched with 13 key phrases such as “pubic symphyseal osteomyelitis” to maximize yield of infected PS cases; this yielded 218. Duplicate medical record numbers were removed and cases without imaging and pediatric patients were excluded. Medical records were reviewed to identify the initial date and imaging modality demonstrating an infectious process of the PS. The year and type of prostate intervention(s) such as radiation therapy, prostatectomy, photoselective vaporization of prostate (PVP), transuretheral resection of prostate, other pelvic surgery, was extracted from the medical record. The images were reviewed by two musculoskeletal radiologists (each with over 10 years of post-fellowship experience) and evaluated for OM, urosymphyseal fistula, and adductor myositis. Descriptive statistics, nonparametric t-test, and Kruskal-Wallis test were performed.

Results:
116 patients met criteria for inclusion. 113 (median age = 73 yrs) had imaging features of PS infection on MR (n = 70) or CT (n = 43). 107/113 (95%) patients had a prior prostate intervention including radiation 88/113 (78%), surgical procedure 85/113 (75%; n = 15 PVP), or both 66/113 (58%). Of the 6 patients without prior prostate intervention, 4 had other pelvic surgeries. 17/113 had prior bladder intervention and 18/113 had prior urethral intervention. There was a significant difference in length of time between prostate/pelvic intervention and the development of infection (p < 0.0001). The elapsed time between radiation and PS infection [median 10 yr (range 0-30 yr, IQR 6-13 yr)] was significantly longer than surgical prostate interventions [3 yr (0-31 yr, 1-9yr)], bladder interventions [1 yr (0-13 yr, 0-2 yr)] and urethral interventions [1 yr (0-7 yr, 0-3 yr)]. The time between surgical prostate interventions and infection was also significantly longer than bladder or urethral interventions (p < 0.05). For patients with both prior radiation and prostate surgery, those with bladder/urethral surgery developed infection sooner than those who did not (median 1 yr vs 5 yr, p < 0.001). There was no significant association between the presence of urosymphyseal fistula and prior radiation, combined radiation and surgery, or PVP. The presence of adductor myositis was also not associated with prior radiation or combined radiation and surgery.

Conclusion:
Most men patients with an imaging diagnosis of PS OM had a history of prior prostate radiation and/or prostatic surgical intervention and these should be considered risk factors for the development of PS infection.