Acute hip pain and inability to ambulate: a rare presentation for perirectal abscess.

A patient with acute hip pain out of proportion to physical findings and inability to weight bear despite negative plain films warrants further in-depth evaluation. Correctly diagnosing the cause of hip pain, a common emergency department (ED) complaint, may be a challenge in the geriatric population (Perron A, Miller M, Brady W. Orthopedic pitfalls in the ED: radiographically occult hip fracture. Am J Emerg Med 2002; 20: 234-7; Cannon J, Silvestri S, Munro M. Imaging choices in occult hip fracture. J Emerg Med 2009; 37: 144-52; Kiu A, Khan S. Radiology of acute hip and femoral injuries. Br J Hosp Med (London) 2010; 71: M22-M24; Zacher J, Gursche A. Regional musculoskeletal conditions: hip pain. Best Pract Res Clin Rheumatol 2003; 17: 71-85). A perirectal abscess as a cause of acute hip pain and inability to ambulate, with gluteus muscle inflammation but no evidence for bone or joint infection, has not been described, to the authors' knowledge. An 82-year-old woman with a history of diabetes, previously ambulatory, presented to the ED after being found on her apartment floor by a visiting health aide, complaining of acute pain in her left hip. Pain was exacerbated by palpation and range of motion testing, and she was unable to bear weight. There was no report of fever, rectal or abdominal pain, bleeding, or painful defecation. Plain films were negative for fracture or lytic lesion. Computerized tomography (CT) of the hip and pelvis was then obtained, which was negative for boney abnormality but revealed a 5-cm ischiorectal abscess with inflammation of the adjacent gluteus muscle. This case illustrates the potentially subtle nature of a deep perirectal abscess in an elderly patient. The CT imaging, useful for investigating the possibility of occult femoral neck fracture, was fortuitous in leading to the diagnosis. One must consider the possibility of visceral processes causing referred pain, when evaluating the patient with an acutely painful hip (Perron A, Miller M, Brady W. Orthopedic pitfalls in the ED: radiographically occult hip fracture. Am J Emerg Med 2002; 20: 234-7; Zacher J, Gursche A. Regional musculoskeletal conditions: hip pain. Best Pract Res Clin Rheumatol 2003; 17: 71-85).