Groin pain is a common complaint in the athletic population (1,2). It has a prevalence of 0.5% to 6.2% among all sports injuries, more prominently seen in sports involving the lower abdominal and proximal thigh muscles (1,2). Due to the anatomic and biomechanic complexity of the region, determining exact etiology of pain can be challenging (2).
A common cause of groin pain in athletes is osteitis pubis (3,4). It is an overuse injury, resulting in inflammation of the symphysis pubis and surrounding structures (1,4). Athletes who pivot, cut abruptly and frequently change speed have a higher prevalence (3). In comparison, osteomyelitis of the pubis is a rare cause of groin pain that may present with generalized symptoms, like fever, chills, and night sweats (1). Diagnostic evaluation and treatment are different for each ailment; thus, accurate diagnosis is essential.
A 41-year-old male elite long-distance runner presented to an outpatient sports medicine clinic with 6 years of low-level chronic groin pain which flared after a recent ultramarathon. He had previously been diagnosed with osteitis pubis and a large osteophyte of the pubic symphysis (Fig. A). He reported running an average of 80 to 90 miles·wk−1 for the last 19 years. On presentation, he described a sharp, throbbing pain in the right groin with radiation to the right thigh, worse with foot contact while walking and better with elevation and immobilization. On examination, the patient had an antalgic gait on the right without notable spinal or pelvic asymmetry. His active hip range of motion was symmetric and pain-free. He exhibited five of five strength in the L2 to S1 myotomes bilaterally and two of four symmetric reflexes in the lower extremities. He had downgoing toes, no clonus, and 2+ DP pulses bilaterally. Straight leg raise; flexion, abduction, external rotation; flexion, adduction, internal rotation; Gaenslen sign, femoral stretch; and reverse straight leg tests were pain-free and symmetric. He had substantial tenderness to palpation over the pubic symphysis just right of midline. The initial differential diagnosis included pelvic stress injury, osteitis pubis, and adductor strain. The patient was instructed to use crutches for 1 wk, then transition to level ground walking if pain-free.
At his 2-wk follow-up visit, the patient reported that he had been pain-free 2 d after his last visit and so had returned to running 6 to 10 miles·d−1 without pain. Two days before returning to the clinic, he had had a sudden recurrence of 8 out of 10 pain when he turned his legs while sitting on the couch. Examination was similar to his previous clinic visit, except he had tenderness over the proximal right adductor bulk. Emergent magnetic resonance imaging (MRI) of the pelvis demonstrated moderate-to-marked degenerative changes of the pubic symphysis and a grade 1 strain of the right adductor brevis (Fig. B). He was advised to use crutches and rest. One day later, he returned to the clinic and requested an adductor tendon sheath injection of corticosteroid so he could accompany his family to a theme park. After extensive discussion and receiving written and verbal consent, an ultrasound-guided peritendinous injection of 4 mL of 1% plain lidocaine, and 1 mg of topical triamcinolone was administered and tolerated well. The patient left without pain; however, 6 d later, he contacted the clinic to report recurrent pain and a low-grade fever. Laboratory examination revealed an erythrocyte sedimentation rate (ESR) of 17 and C-reactive protein (CRP) of 5.7. An updated MRI of his pelvis showed marked degenerative changes of the pubic symphysis and edema in the right adductor brevis without evidence of abscess. Two days later, the patient reported his pelvis felt like it was going to “explode,” and he went to a local emergency department. At the time of admission, his ESR and CRP were 44 and 190, respectively. Computed tomography of the pelvis did not show an abscess. He was placed on vancomycin and ceftriaxone; he defervesced, and his pain improved in 24 h. He was evaluated by an internist and an on-call orthopedist who believed he had osteitis pubis and a systemic cause of inflammation, and he was discharged in less than 48 h without further antibiotics. Within 48 h of discharge, he had recurrent pain in the groin. An Indium white cell scan was ordered, which showed no osteomyelitis but diminished marrow uptake in the pubic symphysis. Ten days after discharge, the patient's pain once again increased, and he developed occasional fevers. Repeat laboratory examination showed an ESR of 43 and CRP of 12.1. He was started on sulfamethoxazole and trimethoprim and was referred to an orthopedist who specializes in tumors and atypical orthopedic issues.
The patient was evaluated and taken off antibiotics for 2 wk for a diagnostic computed tomography-guided biopsy with cultures to rule out infectious process. Biopsy revealed a nonneoplastic, degenerative process with areas of osteonecrosis consistent with chronic osteomyelitis with osseous remodeling. Culture was positive for methicillin-sensitive Staphylococcus aureus. He underwent arthroscopic debridement and irrigation of the extensive heterotopic ossification of the pubic symphysis, then completed 6 wk of intravenous ceftriaxone 2 g daily. He was able to walk 380 ft with a standard walker and physical therapist supervision 24 h after surgery. The patient was progressing as expected at 4-wk and 3-month follow-up postsurgery, with a normal-appearing bony pelvis (Fig. C). We recommended he avoid high-impact activities for at least 3 months. The patient competed and won his next 100-mile race less than 3 months after his surgery (Fig. D). At the last follow-up, the patient had no pelvic pain or systemic symptoms.
To our knowledge, this is the first documented case of osteomyelitis pubis in an ultramarathon runner. This case demonstrates the difficulty of acute evaluation of patients with groin pain and the obstacles of differentiating osteitis pubis from osteomyelitis pubis. Early diagnosis is essential, since treatment of the two entities is very different (1).
Thorough evaluation must include description of symptoms, medical history, and functional limitations. Athletes with osteomyelitis pubis may present with insidious onset of pain in the pubic symphysis with adductor muscle and abdominal discomfort, similar to osteitis pubis (1). Since osteomyelitis pubis is an infectious process of the pubic symphysis, fever and other systemic symptoms must be inquired about (5). Our patient presented with delayed onset of fever, which made the diagnosis of osteomyelitis pubis more difficult.
On physical examination, patients with either diagnosis may present with tenderness to palpation of the superior and inferior pubic rami, but these symptoms may be more severe in those with osteomyelitis pubis (5). Pain may be present with resisted hip adduction and abdominal muscle activation related to the muscle insertions around the symphysis pubis (1). Patients also may present with waddling or antalgic gait (5). Our patient had exquisite tenderness to palpation over the right pubic symphysis with normal neurologic examination and hip provocation maneuvers.
Imaging studies can be helpful to rule out other pathologies, including inguinal disruption, adductor muscle tendinopathy, stress fracture, and referred pain from hip or back (1,3). MRI is the criterion standard for diagnosis of osteitis pubis. In acute osteitis pubis, MRI may reveal bone marrow edema and inflammation around the symphysis with chronic changes, such as subchondral sclerosis and osteophytes (6). The presence of symphyseal fluid on MRI should raise suspicion for osteomyelitis pubis (5). Clinicians should be aware that Indium tagged leukocyte scans are most accurate for infections of less than 2-wk duration and have a 27% false negative rate in chronic infections (7). Gallium-tagged leukocyte scans have only a 19% false negative rate for chronic infections and should be considered in this diagnosis if symptoms are chronic. Pubic symphysis aspirate, blood culture, and inflammatory markers (i.e., CRP, ESR, complete blood count) also can be useful in differentiating the two diagnoses (1).
The exact etiology of spontaneous and atraumatic osteomyelitis pubis in athletes is unclear (1). Currently, there are eight reports, including 10 patients, in the literature (1). All patients presented with fever and elevated ESR and CRP, with 60% presenting with elevated white blood cell count (>10,000/μL). Blood cultures may be helpful, and the most common organism is S. aureus (1).
The criterion standard for treatment of osteomyelitis is 6 wk of intravenous antibiotics. Our patient was initially placed on vancomycin and ceftriaxone for 24 h and experienced improvement of symptoms. However, he was taken off the antibiotics because he was incorrectly diagnosed with osteitis pubis. All reported cases of patients with osteomyelitis pubis include hospitalization and treatment with intravenous antibiotics for an average of 6 wk (1).
There are currently no return-to-play guidelines following osteomyelitis pubis (1). One patient reported a return to running at a 4-month follow-up (8). Individual factors, including general health, conditioning, and extent of surgical debridement, should guide return-to-play decisions. When treated appropriately, complete recovery and return to sport is expected. Our patient returned to running without deficit one month after his treatment, without medical clearance.
Osteomyelitis pubis is a rare cause of groin pain. It may be seen in athletes without surgical history or clear predisposing risk factors. Clinicians must consider this diagnosis in patients with groin pain and must order appropriate laboratory and imaging studies to confirm the diagnosis as soon as possible. Antibiotics and surgery are the standard of care and should be applied once diagnosis is confirmed.
The authors declare no conflict of interest and do not have any financial disclosures.
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