Hips Don't Lie: A Case of Low Back Pain due to Osteitis Condensans Ilii

Case Diagnosis: Osteitis Condensans Ilii

Case Description or Program Description: The patient is a 28-year-old female with a history of scoliosis who presented for low back pain evaluation. Pain has been present for 5-6 weeks, without inciting event or trauma. The pain shifts sides but is worse on the right, radiating to the hips and anterior thighs. She was referred to physical therapy by her internist, but was unable to tolerate it due to pain. Heat helps the pain. Sit to stand and stair negotiation are especially difficult, and there is pain with each step she takes. She denies weakness.

Setting: Outpatient Sports Medicine Clinic

Assessment/Results: Lumbar X-ray showed mild levoscoliosis without acute findings. Physical exam revealed bilateral lumbar paraspinal and left SI joint tenderness with lumbar flexion limited to 15 degrees. Motor strength and sensation were intact bilaterally. ANA was positive, but all other inflammatory markers were negative. MRI showed subchondral sclerosis along the iliac portions of the anterior SIJ bilaterally without bony erosions, consistent with osteitis condensans ilii (OCI). She was seen by rheumatology and diagnosed with non-radiographic axial spondyloarthritis. She was treated with a Medrol dose pack, Flexeril, and physical therapy. Recommended to try methotrexate but treatment pending due to fertility course.

Discussion (relevance): Differentials for back pain in young females include mechanical causes, inflammatory arthropathies, infection, metabolic conditions, and sacroiliitis. Evaluation involves inflammatory markers, imaging, and clinical assessment. Here, persistent pain and concern for inflammation prompted MRI, confirming OCI. Though often asymptomatic, OCI can mimic inflammatory conditions requiring exclusion. Conservative treatment aims to reduce inflammation, pain flares, and muscle spasms while using physical therapy to relieve mechanical stress and improve biomechanics.

Conclusions: OCI should be included on the differential for SIJ and low back pain in young adults. Most cases are managed conservatively, although there is evidence to support corticosteroid injections and radiofrequency ablation for pain relief.