75-year-old male consults for disabling pain in pubic region and hypogastrium of 3 weeks of evolution, since he was hospitalised one month ago for urinary tract infection (UTI). Laboratory tests showed elevated CRP (17.4 mg/dL) and leucocytosis (12.3x103/μL; 81% of neutrophils). Blood cultures were negative, while E. coli was identified in urine cultures.
The imaging tests performed during his admission for UTI one month ago were reviewed (abdominopelvic CECT) with no significant alterations (Figure 1a).
The study was completed with simple (Figures 2a and 2b) and contrast-enhanced pelvic MRIs (Figures 3a and 3b) that showed bone oedema in the symphysis pubis, with mild joint effusion, and bilaterally and symmetrically in the iliac and ischiopubic branches, with intense enhancement after administration of gadolinium. Extensive inflammatory changes in the musculature of the internal compartment of both thighs and in the proximal insertion of the adductors, and small bilateral collections in the adductor musculature were seen. There is also hyperenhancement of the bladder floor wall and paravesical fat after contrast administration, suggesting the persistence of bladder and pelvic inflammatory changes.
Then, a CT-guided biopsy of the pubis was performed. During the procedure, we could observe extensive lytic involvement of both iliac and ischiopubic branches that were not seen in the previous study.
Background
Infectious osteomyelitis of the pubis is an uncommon condition, and it can be mistaken for pubic osteitis, an aseptic inflammation usually caused by shearing forces. Differentiating these two conditions is crucial due to their therapeutic and prognostic implications.
The exact pathogenesis is unclear. Concomitant infections can serve as a microbiological entry point, leading to bacterial arthritis through haematogenous dissemination or, more rarely, by contiguity, such as a UTI in our patient. This condition, often referred to as septic arthritis of the pubic symphysis, is more accurately described as osteomyelitis because the infection primarily originates in the pubic bone next to the joint. Initially, the infection begins in one pubic bone and then spreads across the joint to involve the opposite pubic bone [1].
Clinical Perspective
Pubic osteomyelitis predominantly affects young adults. The main predisposing factors include a history of recent surgery or genitourinary manipulations. Other favourable factors, such as repetitive local microtrauma, neoplastic processes, intravenous drug users (IDUs), and the puerperal period could facilitate infection due to greater ligamentous laxity [2].
The aetiology varies according to risk groups, with Staphylococcus aureus and Pseudomonas aeruginosa being the most prevalent microorganisms. However, almost any pathogen capable of causing primary or secondary bacteraemia can cause a haematogenous infection in the pelvic bone. S. aureus predominates in athletes and IDUs, while polymicrobial flora is common in malignancies and pelvic surgery [2].
The most frequent symptom is pubic pain, which also manifests in the inguinal region, hip, and thigh. Other common findings include fever and local inflammatory changes. Leukocytosis and elevated acute-phase reactants appear in approximately one-third of cases, and cultures are positive in a high percentage [2].
Imaging Perspective
Imaging techniques alone offer little specificity and can be normal in the early stages. Simple radiology presents a high rate of false negatives, showing morphological changes in advanced stages with marked osteolysis or diastasis of the pubic symphysis, suggesting the presence of a joint abscess. Positivity in scintigraphic studies is suggestive in suspicious cases, but it does not differentiate the condition from aseptic osteitis [1]. CT is more sensitive as the process progresses, and MRI provides more precise information. They can assess the presence of lytic lesions, fluid accumulation in the symphysis, joint widening, and muscle oedema. The most frequent complications, evaluable by imaging, are abscess formation and extension to adjacent structures such as the sacroiliac joint, ischial tuberosity, or adductor muscles [1,3,4].
Outcome
Multidisciplinary management, supported by radiological tests and microbiological evidence, whether through positive blood cultures or histological samples (bone biopsy or aspirated collections), is essential for an accurate diagnosis. Treatment involves a prolonged course of antibiotics, no less than 4–6 weeks, along with early debridement in case of complications to avoid subsequent joint instability [2,4].
Pubic osteomyelitis
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1. The provided CT and MR images reveal bony destruction or sclerosis around the pubic symphysis, with localized abnormal bone density indicating lesion-like changes.
2. There is an irregular or widened pubic symphysis space in some instances, and certain cases show articular surface destruction.
3. On the T2-weighted MRI images, hyperintense signals are observed near the pubic symphysis, indicating soft tissue edema, and in some areas, small effusions or abscess formation may be suspected.
4. Inflammatory infiltration is visible in the surrounding soft tissue, spreading along both sides of the pubic symphysis, suggesting involvement of the adjacent soft tissues.
Considering the patient’s age, recent history of urinary tract infection (positive E. coli culture), clinical presentation (pubic and lower abdominal pain), laboratory findings (elevated CRP and leukocyte count), and imaging results (bony destruction and soft tissue edema around the pubic symphysis), the most likely diagnosis is:
Infectious Osteomyelitis of the Pubic Symphysis (Pubic Symphysis Region Infection).
If feasible, further CT-guided aspiration or histopathological examination may be performed to confirm the causative pathogen and optimize antibiotic treatment.
1. Pharmacological and Surgical Treatment
- Once the bacterial etiology is confirmed, administer effective broad-spectrum or targeted antibiotics for at least 4–6 weeks; extend the course as required.
- In cases of significant abscess formation, severe local destruction, or progressive soft tissue infection, early surgical debridement and decompression should be considered to prevent joint instability or persistent infection.
2. Principles of Rehabilitation and Exercise Prescription
(1) Early Stage (Acute Phase, significant inflammation):
- Focus on immobilization or reduced activity; avoid additional stress to the pubic symphysis.
- Engage in gentle lower-limb exercises, such as bed-based range-of-motion training (ankle pumps, knee flexion and extension), to maintain basic muscle function and promote circulation.
- Refrain from weight-bearing exercises, squats, lunges, or similar movements.
(2) Subacute to Recovery Phase:
- Once local pain subsides and inflammatory markers decrease, introduce mild weight-bearing exercise gradually, such as simple sit-to-stand practice or short-distance walking.
- Incorporate pelvic stability exercises, including core workouts (e.g., planks, bridges), starting at low intensity for short durations, then progressively increasing over time.
- Monitor pain and fatigue closely; if significant discomfort arises, adjust the training intensity promptly.
(3) Late Functional Recovery Phase (Stable Phase):
- Further develop lower-limb strength and core resistance training, such as resistance band exercises or seated equipment.
- Gradually return to normal daily activities by incrementally increasing walking distance and velocity. Under professional supervision, low-impact aerobic exercises (e.g., elliptical, stationary bike) may be incorporated.
- Follow the FITT-VP principles (Frequency, Intensity, Time, Type, Progression, Personalization). Exercise frequency may start at three times per week and gradually increase to five or more, while intensity is increased according to heart rate and RPE (Rate of Perceived Exertion).
- Rest and apply ice packs promptly after training to alleviate activity-induced stress responses.
3. Special Considerations
- For elderly patients, closely monitor cardiopulmonary function and bone health to prevent cardiovascular events or fractures caused by excessive exercise.
- Training under the guidance of professional rehabilitation therapists and clinicians is recommended, ensuring continuous assessment of infection control and joint stability.
Disclaimer: This report is for reference only and does not replace an in-person consultation or professional medical advice. If you have any concerns or discomfort, please seek timely evaluation and care at a qualified healthcare facility.
Pubic osteomyelitis
