Pelvic osteomyelitis complicating Crohn ' s disease

WCP KWAN, HJ FREEMAN. Pelvic osteomyelitis complicating Crohn's disease. Can) Gastroenterol 1993;7(3):293-296. Although rhcumatologic complications of Crohn's disease are common, osteomyclitis associated with Crohn 's disease rare ly is described. In this report, a 29-ycar-o!J man with C rohn's disease was seen with ileorectal fistula, pelvic abscess and severe back pain. The abscess and fistu la were treated surgically but the patient had persistent fever and pain. Computed tomography scan showed destruction of the sacrum , and bone scan demonstrated increased sacral uptake. Osteomyeliris was suspected and confirmed on bone biopsy. Streptococcus viridans was isolated from bone culture. Treatment with parenteral penicillin was successful and follow-up revealed no recurrence of ostcomyelitis.

C OMMON MUSCULOSKELETA L   complications in pa tien ts with Crohn's disease incl ude peri pheral arthritis, spondyli tis and , less commonly, granulomatous hone or muscle disease as well as perinsteal new bone formation wid1 cluhhing.Despite the frequen t occurrence of inflammatory processes includ ing abscess or fis rula formation adj acent to pelvic bones, osteomye li tis h as been rarely recorded.T he present report describes a p.itient with Crohn 's disease compl icated by pelvic sepsis and sacral osteomye licis, a nd reviews the previous literature on this a pparentl y unusual complication.

CASE PRESENTATION
A 29-ycar-old man was admitted to Uni versity Hospital in July 1986 for evaluation of fever, weight loss and d ia rrhea.Crohn's d isease had been diagnosed at age 24 with involveme nt of the ileocecal region and sigmoid colon; improvement resulted fro m a course of prednisonc and sulpha alazine, but within several months he developed fever a nd inc reasing abdominal pain.Laparoto my revealed a rctrope ritoneal abscess char was dra ined with no intestinal resection done.
The patient remained we ll until April 1986 when he no ted lower ah- A barium enema revealed an increase in retrorectal space with changes of C rohn's disease present in the sigmo id colon, including a pelvic fistulous tract (Figure 1).A small bowe l fo llowthrough showed involvement of the terminal ileum, and early fil ling of the rectum consistent with an ileorectal fistula.Computed to mography (CT) scan of the abdomen showed tethered loops of il eum in Lhe pelvis with an associated inflammatory mass: no clear cut abscess cavity was defined.RaJiographs of the lumbosacral spine showed normal sacroiliac and hip joints, but a small bony fragment was seen a t the anterosupe rior aspect of S l together with spondylo lithesis of LS-Sl .
The patient was treated with total parenteral nutrition anJ antibiotics, including gentamicin and merronidazole.Laparotomy, revealed a large pelvic inflammatory mass involving the distal Figure 2) Com/ntted wmograf,hy scan view of S I showing a lytic lesion associared with sacral osteomyelitis.Subsequent biopsies confirmed the />resence of usteomyelitis and cultures 1'evealed ileum, cecum and recrosigmo iJ.Fistulous tracts were demonslrated between the ileum and rectum.ll eocecal resection a nd reanastomosis was done with a sigmoid resection a nd colostomy.
Postoperatively, the patient's condition improved and the a ntibiotics were discontinueJ.His ahdomi nal pain resolved and the colostomy functioned normally.I lowever, he continued to have low grade fever an<l complained of increasing bac k pain with radiation down his right leg and mild urinary hesitancy.Multiple blood cultures were nega tive.Repeat neurological assessment revealed no abnormality.CT scan of his spine now showed multiple bony fragments anlerior to the first sacral segment, with irregular resorption of the body of S I.These changes were consistent with sacral osteomyelitis (Figure 2 ).A bone scan demonstrated increased uptake in the upper sacrum and CT-guided neeJle biopsy of the sacrum showing histological changes of osteomycl itis but c ultures from the biopsy ma terial revealed no organism.A myelogram showed no ev idence of obstruction or epidural Jefect. The

DISCUSSION
Although many inflammatory Jisor-Jcrs of the intestinal tract develop close or adjacent to the bony pelvis, pyogenic nstcomyclitis involving the pelvic hone Jistinccly is uncommon.In a review of 616 cases of osteomyeliris, only 5% in-volveJ the pelvic bony structures (I).Usually, the infection is spread by contiguous extension frnm soft tbsue foci and, less commonly, from intra-abdominal or pelvic abscesses.The infection usually i,, lnca li:ed to the ileum smce it is the largest pelvic hone and hru, an abundant hloud supply.
Pelvic osteomyelitis appears to he an unusu.ilcomp I ication of Crohn's disease despite rhe frequent presence of an associated chronic inflammatory pelvic nrnss, abscess and/or fistulous tracts.This contrasts the frequency nf other musculoskeletal d isorders experienced by pat icnts with inllammatory bliwel Jrscasc which can he as high as 40 tll 50% (2).The prcctsc incidence of pelvic osteomyclitis in Crohn's disease is unknown; however, hascd on the clmical Jescriptions of this associated complication in the literature, it seems to be me.The fi rst two cases of pelvic ostcomyelitis in Crohn's disease were described in 1969 by Goldstein et al (3).Since that time, only 10 additional cases ha,•e been reported (Tahlc 1 ).
The majority of reported cases involved rhc right ileum.This undoubtedly is related w the fact that the coadj.1cemterminal ileum and cecum are 1he most uimmon sites of Crohn's dbcase.In most reported patients, an adjacent abscess or fistu la was present, suggesting that infccnon resulted from seeding to contiguous hone.The only exception was a case with osteomycl iris nf the lefr femur and Crohn's disease; the pmicnt described also had an E coli septicemia and was being treated for Crohn's disease with conicosterrnds and immunosuppressive agents ( 4 ).
The current pmicnt had ostcomyel itis 111vol\'ing thl• sacrum, likely as a scqucla oft he pelvic inflammatory mass with an ileorecrnl fistula: associated prcsacral infection and abscess format ion became evident.In all three prcvtously described cases with sacral nsteomyclitb in rhe setting of Crohn's dise,1se, presacrnl and pcrirectal abscesses were also present.In almost all instances the diagnosis of Crohn':, disease was made before osteomyelitis was discovered -this ts not surprising since ostcnmyclitis appears ro occur exclusively in the setting of complicated The significant cl inicnl feature that suggested nsteomyelatis in the present patient as well as in all reported cases to date, was severe ,md persbtent p::iin 111 the affected ;irca.Thb can somcumes be overlooked hccause the pacient is frequently chronically ill with orher complications of Crohn's disease.and the pain in the abdomen or affected areas associated with of either an ;ibsces:, or fistula is expected.Funhermore, sacroilcitis and spondylitis complicating chronic inflammatory bowel dis-ea~c can certain ly result in disabling and somet imes severe back pain.The plain radiographs of the lumhosacral spine in the current patient revealed progressive changes result ing in fun her evaluation with CT and hone scans that strongly suggested sacral ostcomyclitis.Subsequent definition of the typical pathological features combined with microbiological studies unequivocally demonstrated its presence.It is well known that typical radiographic osseous ch,rnges of osteomyel itis may not appear for days or even weeks (as illustrated in the patient described here).Bone scans may offer improved sensitivity approaching I 00%, and other imaging moda li ties, such as CT scan, may a id in detection of sequestra (6) an<l help del ineate an ato mical alterations.At the time the patien t was evaluated, magnetic resona nce imaging was not available in the a uth ors' h ospital.Recent literature has demonstrated that this imagi ng modality is indispensible to evaluate osteomyclitis -nor o nly is its specific ity reported to be superio r but it is useful in defining the extent of the inflammatory process and can distinguish osteomyclitis from ccllulitis (7).
Neurological complications of pelvic sepsis in Crohn 's disease were considered in the current patient, especially with the d evelopme nt o f radiating pain co his right thigh and urinary hesitancy.However, no obj ective neurological abnormality was evident a nd his myelogram was normal.. Al though n o penmment neurological deficit was seen, the development o ( pelvic sepsis, particularly if sacral osteomyelitis is documented , m ay result in fu rthe r exre nsio n of the inflammatory process in to the spinal cana l.Indeed, th ere arc a number of prior descriptio n s of Crohn 's d isease with fistula forma tion extendi ng to th e spinal ca nal causing serious complications, such as spinal epidural abscess.Aitken (8) first reported a case o f epidural abscess in a 36-year-old man with C rohn 's disease of th e terminal ileum and a pelvic inflammatory mass resulting in paraplegia.Sacher (9) described a case of spinal epidural abscess from L2 to S4 in an I I-year-old boy with C rohn's disease of th e distal colon and righ t psoas abscess.Hershkowitz ( 10) reported a 19-year-old man with epidural and subdural sp inal empyema originati ng fro m recta l fistula.
lt is a n ticipated that the organisms in volved in pelv ic osteomyelit is o riginate from the bowel fl ora; h owever, documentation of the offending path oge n often appears to be d ifficult a nd may be complicated by the frequent use of antib iotics to treat septic complications in these patients.C ulture from draining sinuses, adjacent abscesses o r in fected cavities may be misleading.A bone biopsy may offer th e best opportunity to document the bacteria invo lved.In a compre hensive review of osteomyclitis, the frequency of pos itive c ultures in re lation to the source of spec imens was 60% for ho ne aspirat e and 65% for bo ne pus ~)brained at surgery ( 11 ).There was a heavy growth of a single organism, Stre/) viridans, fro m the bo ne bi opsy and the present pmiem was treated successfully with penic illin.
In summary, d espite the many intraa bdo minal complications thnt occur in patients with C rohn's disease, ostcomyclitis is rare c1nd invaric1bly develops in the presence of a n intra-pelvic abscess or fistula with contiguous seeding of infec tion .Diagnosis may be made with appropriate radiographic imaging and bone scan methods a lon g with microbiological stud ies.Heigh tened suspic ion in th e patient with persi.stentback or bone pain, however, is most important as this likely will enhance detection and limit potential se rious morbidity due to osteomyeli tis a nd associated n eu rological complicatio ns.

Figure 1 )
Figure1) Barium enema showing a lateral view of the />elvis, including the sacrum .A marked increase in rhe retrorectal space is observed patient was treated with penicillin G anJ gentamicin.ln an effort to obtain a specific bacteriologic diagnosis, an open biopsy of the sacrum was Jone.Tissues from the sacrum yielded a heavy growth of Streptococcus viriclans a nd the histology demonstrated areas of osteonecrosis along with acute anJ c hronic inflammation consistent with osteomyelitis.No granuloma was seen and an acid fast stain was negative.A~ Strep viridans is a n unusual cause of pelvic bone osteomyelitis, the patient had furthe r blood c ultures an<l underwent an ech oca rdiogram to excl ude enJocarditis (these studies were negative).The patient received six weeks of parenteral penicillin G therapy with good clinical response.There was resolution of fever and back pain, an<l his e rythrocyte sedimentation ra te J e-creaseJ from 50 to 12 mm/h .A fo llowup bone scan nea r the conclusion of treatment showed only slight uptake in the sacrum with no appreciable change in plain ra<liographs.T he patient was discharged in October 1986 and his colostomy was closed in Novemher 1986.