SACRAL STRESS FRACTURE IN A POST PARTUM RUNNER

Abstract

HISTORY S.S. is a 30 yo. female runner who presented to sports medicine clinic with the chief complaint of hip pain for 5 weeks. Her PMH is significant for sciatica diagnosed clinically in 1995, and two tibial stress fractures. Her history also included amenorrhea three times throughout her life. First at age 13–14 years, second at age 15–16 years, and third in college. Menstruation resumed each time with activity modification only. She had no history of diagnosed eating disorders. The current pain began while running in the third trimester of her pregnancy (30–35 miles per week). The symptoms lessened, but were persistent, one month prior to delivery with discontinuation of running. The pain increased in severity one month after delivery when she began running. ultimately to 40–45 miles per week over a six week time period. The pain was located over the left lower back and sacral area, spread laterally to her left hip, and occasionally radiated to her left buttock. The ROS was negative for fevers, neurologic symptoms, and change in bowel/bladder function. PHYSICAL EXAMINATION Clinical examination findings included diffuse tenderness in the upper gluteal and low back area with focal tenderness along the sacrum. The Patrick (FABER) test was positive on the left. The straight leg raise test was negative. The neurological examination was normal, as was the hip examination. There was no leg length discrepancy. The physical examination was otherwise unremarkable. DIFFERENTIAL DIAGNOSIS The differential diagnosis for this athlete included muscle strain, radiculopathy, stress fracture (pars interarticularis/femoral neck/pelvis), insufficiency fracture (oncologic/metabolic process), osteomyelitis, arthritis, and sacroileitis. TESTS AND RESULTS The initial evaluation included plain films of the hips and pelvis, which were negative for bony lesions. The leading diagnoses at this time included stress fracture versus lumbar disc herniation/nerve impingemen:. The next diagnostic test was an MRI of the lumbosacral spine and pelvis. In the interim a physical therapy program was started targeting core muscle strengthening, specifically the abdominal, peripelvic and lumbar paraspinous muscles. Cross training was encouraged including swimming, stationary bike, and elliptical machine. The T2 weighted fat suppressed coronal MR image of the sacrum revealed a large area of high signal intensity consitent with the history and presentation. The diagnosis for this female distance runner in her post partum course is sacral stress fracture. TREATMENT Conservative management with activity modification and physical therapy were central to her treatment. Changes in strength and body mechanics before and after delivery including peripelvic and abdominal muscle relaxation, increased ligametous laxity, increased frontal weight and alteration in pelvic alignment may have contributed injury development. Serial clinical examinations were followed including lumbosacral palpation and the Patrick test. OUTCOME Clinical follow up at four weeks revealed minimal focal tenderness with palpation over the left sacrum. The Patrick test was negative. The neurologic examination remained normal. Evaluation at six weeks was entirely normal and the patient was cleared to begin running with instructions to increase mileage ≤ 10% per week. CONCLUSION Low back and buttock pain in runners can be frustrating for athletes and diagnostically challenging for sports medicine physicians. Sacral stress fractures can resemble neuropathic processes. They should be considered in all distance runners experiencing low back, hip, and buttock pain. Prenatal and early post partum status may contribute to sacral stress fracture injury occurrence in distance runners.