CASE REPORT Bilateral Spontaneous Periacetabular Fracture An Unusual Complication of Multiple Sclerosis Ajay Aggarwal, MB, BS, Javad Parvizi, MD, FRCS, and Reinhold Ganz, MD Abstract: We describe an unusual case of a 43-year-old woman who had developed bilateral spontaneous periacetabular fractures second- ary to severe myoclonic contractions. The absence of antecedent his- tory of trauma and detection of muscular spasticity at presentation prompted neurologic investigations that led to the diagnosis of mul- tiple sclerosis in this patient. The fractures were treated successfully by open reduction and internal fixation initially. Since fracture reduc- tion was delayed for almost 1 year, a special distraction frame had to be used. Deterioration in the medical condition of the patient with return of severe spasticity caused a dramatic failure of the fixation on one side 2 years later. This case report confirms that fractures, usually requiring high-impact trauma, can and do develop spontaneously in patients with sustained myoclonic contractions, and these fractures can be the presenting indication of an underlying neuromuscular dis- order. Key Words: multiple sclerosis, spasm, periacetabular, fracture (J Orthop Trauma 2004;18:182–185) CASE REPORT A 43-year-old woman was seen initially in May 1999 for evaluation of groin and low back pain that had started 6 months previously. She had delivered her fifth child uneventfully 1 year before, and except for occasional mild back pain, her past medical history was insignificant. There was no antecedent history of trauma. The groin pain was constant and became worse on ambulation. Radiographs of the pelvis ordered by an orthopaedic surgeon in her native country at the time of pre- sentation revealed a periacetabular fracture of all three bones with gross deformity due to medial and superior migration of the periacetabular complex (Fig. 1). The patient underwent an extensive diagnostic workup, including bone biopsy, magnetic resonance imaging (MRI) of the pelvis and spine, isotope bone scan, and serologic tests. All investigations were negative, pre- senting a diagnostic dilemma for the treating surgeons. The patient was referred to our institution for surgical management of her fracture and further investigations. At the time of presentation to our institution in April 2000, the patient was complaining of bilateral groin pain of worsening intensity. She was confined mainly to a wheelchair with limited ability to walk a few steps. On examination, she was found to have tenderness to compression of the pelvis with reduced and painful bilateral hip range of motion. The patient had marked flexion and internal rotation contracture of both hips. Neurovascular examination revealed asymmetric hyper- tonic reflexes and spasm of periarticular muscles around both hips and the entire lower extremities, especially the ham- strings, and the left upper extremity. Radiographs of the pelvis at this stage, in addition to the initial fracture, showed involve- ment of the contralateral pelvis with an identical periacetabular fracture pattern (Fig. 2). In view of the neurologic findings and the lack of history of trauma to explain the fractures, the patient was referred for further neurologic investigations. MRI of the spine and cerebral cortex disclosed signs suggestive of demy- elinating disease, which later was confirmed to be multiple sclerosis. Medical treatment of the condition was initiated with high-dose corticosteroids and muscle relaxants. When the dis- ease was stabilized with adequate resolution of the spasticity, surgical treatment of the periacetabular fractures was insti- tuted. A bilateral ilioinguinal approach was used to expose the fractures. Because of the delayed presentation and complex nature of the deformity, particularly severe medialization of both hips, conventional reduction methods could not be used. A special technique involving placement of distractor pins for transverse and diagonal distraction was used (Fig. 3). Two pins were placed in the stable ilium near the inferior end of the sac- roiliac joint. Two additional pins, originally planned to be placed from the anterior-inferior quadrilateral plate into the ischium, could not be positioned due to the pubis fracture ex- tending into that area. Because the surgical approach did not allow pin placement into the trochanteric region, the pins were introduced into the femoral head through the capsule. Sequen- tial distraction in both directions was applied using these pins. Reduction was carried out under fluoroscopic guidance and Accepted for publication March 18, 2003. From the Department of Orthopedic Surgery, University of Berne, Inselspital, Berne, Switzerland. No financial support of this project has occurred. The authors have received nothing of value. This article does not contain information about medical devices. Reprints: Reinhold Ganz, MD, Department of Orthopedic Surgery Inselspital, CH-3010 Berne, Switzerland (e-mail: reinhold.ganz@insel.ch). Copyright © 2004 by Lippincott Williams & Wilkins 182 J Orthop Trauma • Volume 18, Number 3, March 2004