Persistent Unilateral Lumbosacral Pain in a Female Adolescent Athlete

Abstract

HISTORY: 18-year-old high school senior presents with a two-year history of L sided low back pain. She is an active athlete participating in volleyball, basketball and softball and noticed the pain during basketball season. She denies any acute trauma. Her pain is worse with prolonged sitting and at night, frequently awakening her. Her pain is better with recumbency, heat, and naproxen. She relates occasional pain in the right calf, but otherwise denies numbness, tingling, muscle spasm, bowel, or bladder dysfunction. She underwent a course of physical therapy, chiropractic treatment, epidural steroid injections, and osteopathic manipulation without improvement. Her pain is gradually getting worse and interfering with her participation in sports. PHYSICAL EXAMINATION: She is an alert, oriented, cooperative, slender athletic young woman, with normal general medical exam. Musculoskeletal exam reveals normal spine but pelvic asymmetry, with left PSIS and iliac crest 1 cm lower than right. Her thoracolumbar spine is rotated to the left and lumbosacral spine to the right. She has pinpoint tenderness to palpation localized at the left S1 level with overlying muscle spasm and underlying rib dysfunction. Her overlying skin is intact. There is no palpable mass. She has normal lumbar flexion and side bending but extension produces immediate discomfort in the left lumbosacral junction, reproducing the pain. Her neurovascular exam reveals normal strength, sensation, reflexes, and distal pulses of the bilateral lower extremities. Her stance and gait are normal. Provocative testing of the hip, knee, and ankle is normal. DIFFERENTIAL DIAGNOSIS: Posterior element pain. Pars interarticularis stress reaction or stress fracture Facet cyst or synovitis Discogenic pain Sacroiliac pain or inflammation Somatic Dysfunction Spondyloarthropathy Tumor TEST AND RESULTS: Plain Films: sacral ala: contusion vs. fracture, spina bifida occulta at S1 level CT: focal concavity of L posterior S1 sacral wing, consistent with benign osteolysis Bone Scan: Increased uptake on L side of LS junction, corresponding with previous CT MRI: rounded 10–12mm signal focus within medial LS1, intermediate on T1, IR, and T2, with slight enhancement. Repeat CT: 13 × 10mm lucent well marginated expansile lesion of the anterior lateral aspect of L S1 lamina, with erosion through anterior and posterior cortex, contiguous with exiting LS1 nerve root FINAL WORKING DIAGNOSIS: Left S1 Osteoblastoma with non-aggressive features TREATMENT AND OUTCOMES: Surgical excision of Osteoblastoma with hemilaminectomy Pain free at 10-week post-op check Resumption of previous sports activity