Posterior Dislocation of Coccyx: A Rare Cause of Coccydynia

A 35-yr-old woman was admitted to the emergency department because of coccydynia after a fall onto her buttocks. Physical examination revealed localized tenderness over the coccygeal region. Sagittal view of computed tomography (Fig. 1A) and three-dimensional volume-rendering computed tomography images (Fig. 1B) showed posterior dislocation of the coccyx. Her coccygeal dislocation was managed conservatively with nonsteroidal anti-inflammatory drug. The pain was resolved 6 hrs later after intramuscular injection of diclofenac (75 mg). She was discharged and did not have a follow-up afterward.

FIGURE 1: Sagittal (A) and three-dimensional (B) images of 35-yr-old woman. Posterior dislocation of coccyx indicated with white arrows.

Coccydynia is a painful condition that may be idiopathic or related to trauma or childbirth or that may occur without any identifiable cause. Patients may also be related to chronic injuries sustained in childhood.¹ The following conditions can cause pain in the coccyx region: coccygeal dislocation, pilonidal cyst with abscess or sinus, sciatica, hemorrhoids, piriformis syndrome, etc. The most common reason for a coccygeal dislocation is acute trauma from a fall onto the buttocks. Two types of dislocations are described. Anterior dislocations are more common and posterior dislocations are rare. Coccygeal dislocation has no standard treatment guidelines. Treatment options include nonsteroidal anti-inflammatory drugs, physical therapy, intra-articular steroid injections, coccyx manipulations, tension band fixation, surgical pinning of the sacrum and coccyx, and coccygectomy.² Cushions on the patient’s chair can make sitting more comfortable. A cushion with a wedge-shaped cutout beneath the coccyx can result in the coccyx hovering over the empty area, thus resulting in less coccygeal weight-bearing and less coccygeal pain. Pelvic floor physical therapy can be beneficial for coccydynia, including in patients who have persistent pain despite coccygectomy. Coccygectomy involves the amputation of the coccyx. This treatment is usually reserved for the small percentage of patients who fail to get sufficient relief from nonsurgical care. Partial or total coccygectomy has been reported to be helpful for cases of traumatic coccydynia after all conservative measures were failed. Postoperative complications after coccygectomy consist of local infection, pelvic floor prolapse, retained coccygeal fragments, and ongoing pain despite the surgery.² Hamoud et al.³ stated in their research findings that fracture dislocation of the sacrococcygeal joint in the growing child is a rare injury, and it should be treated conservatively, as the potential of healing and anatomical modeling is high. Clinicians should understand the wide variety of options convenient to diagnose and treat coccydynia.

LEARNING POINTS

• Posterior dislocation of coccyx is a rare cause of coccydynia.
• X-ray and computed tomography imaging are diagnostic methods for posterior dislocation of coccyx.
• Nonsteroidal anti-inflammatory drugs, physical therapy, steroid injections into the joint, coccyx manipulations, tension band fixation, and surgery are treatment options for posterior dislocation of coccyx.