Coccydynia (coccyx pain) due to dynamic instability of the tailbone

Archives of Physical Medicine and Rehabilitation

2007 Sep; 88 (9): E36

Michael Rhee, MD, Patrick M. Foye, MD; David Tung, MD

Physical Medicine and Rehabilitation, UMDNJ-New Jersey Medical School, 90 Bergen Street, DOC-3100, Newark, NJ 07103-2499. tailbonedoctor.com/

Abstract

SETTING: Outpatient, academic physiatric practice.

PATIENT: A 53-year-old female with coccydynia (coccyx pain), worse with sitting.

CASE DESCRIPTION: The patient presented for physiatric pain management consultation for coccydynia. Previous work-up elsewhere had focused on imaging studies (including MRI) of the lumbosacral spine, ironically lacking any images that actually included the symptomatic tailbone.

ASSESSMENT/RESULTS: Upon consultation, the physiatrist ordered sacrococcygeal radiographs, specifically including coned-down lateral views of the coccyx in three positions: supine, standing, and seated. The supine and standing coccygeal radiographs appeared essentially within normal limits. However, the radiographs obtained with the patient seated (the position which reproduced her concordant pain) demonstrated a blatantly obvious posterior dislocation of the coccyx relative to the sacrum. In fact, in the seated position, approximately 75% of the coccygeal depth (in the anterior-posterior dimension) had dislocated posterior to the posterior aspect of the distal sacrum. Thus, while seated, most of the coccyx had actually dislocated to a position behind the sacrum, rather than remaining inferior to the sacrum. These "stress" views documented pathology that would have been missed by traditional coccygeal imaging studies. The dynamic instability visualized from these studies corroborated her concordant symptoms.

DISCUSSION (RELEVANCE): The etiology of coccydynia is sometimes elusive. Objective findings, when demonstrated, can have significant medicolegal implications. Objective findings can also help reassure patients that their tailbone pain is not "all in their head," as some patients have been told by their doctors. Such abnormalities can also form a basis for discussing with the patient an individualized approach to the various treatment options for coccydynia.

CONCLUSIONS: Diagnostic workup for coccydynia should often include adding coned-down lateral radiographs with the patient in the seated position. These seated views are particularly helpful in cases where more traditional radiographs have failed to document pathology that explains the patient's symptoms.

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