Neurologic injury often accompanies traumatic dislocation and fracture-dislocation of the hip. A review of the literature reveals an incidence of approximately 10% in adults and 5% in children. The sciatic nerve, usually the peroneal branch, is most often injured, and this complication can be seen after all types of posterior fracture-dislocations and simple posterior dislocations. The sciatic nerve can be acutely lacerated, stretched, or compressed, or later encased in heterotopic ossification. Neurologic examination at the time of injury often is difficult but is extremely important. Once a nerve injury is discovered, prompt closed reduction must be attempted to relieve distortion of the nerve from a dislocated femoral head or displaced acetabular fracture. Considerable controversy surrounds the recommendations for additional treatment of nerve injury once the hip has been reduced. At least partial recovery of nerve function occurs in 60% to 70% of patients, with no clear correlation with injury or treatment type. Rehabilitation of patients with sciatic nerve injury must begin as early as possible and should focus on the prevention of an equinus foot deformity. Magnetic resonance neurography may become useful in the future for initial evaluation of patients with this injury.

Nerve injury in traumatic dislocation of the hip.

Background
Heterotopic ossification (HO) is common after combat-related amputations and surgical excision remains the only definitive treatment for persistently symptomatic HO. There is no consensus in the literature regarding the timing of surgery, and recurrence frequency, reexcision, and complications have not been reported in large numbers of patients.

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What Risk Factors Predict Recurrence of Heterotopic Ossification After Excision in Combat-related Amputations?

Sciatic nerve injuries associated with acetabular fractures may be a result of the initial trauma or injury at the time of surgical reconstruction. Patients may present with a broad range of symptoms ranging from radiculopathy to foot drop. There are several posttraumatic, perioperative, and postoperative causes for sciatic nerve palsy including fracture–dislocation of the hip joint, excessive tension or inappropriate placement of retractors, instrument- or implant-related complications, heterotopic ossification, hematoma, and scarring. Natural history studies suggest that nerve recovery depends on several factors. Prevention requires attention to intraoperative limb positioning, retractor placement, and instrumentation. Somatosensory evoked potentials and spontaneous electromyography may help minimize iatrogenic nerve injury. Heterotopic ossification prophylaxis can help reduce delayed sciatic nerve entrapment. Reports on sciatic nerve decompression are not uniformly consistent but appear to have better outcomes for sensory than motor neuropathy.

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Sciatic Nerve Injury Associated with Acetabular Fractures

Currently, there is no animal model in which to evaluate the underlying physiological processes leading to the heterotopic ossification (HO) which forms in most combat-related and blast wounds. We sought to reproduce the ossification that forms under these circumstances in a rat by emulating patterns of injury seen in patients with severe injuries resulting from blasts. We investigated whether exposure to blast overpressure increased the prevalence of HO after transfemoral amputation performed within the zone of injury. We exposed rats to a blast overpressure alone (BOP-CTL), crush injury and femoral fracture followed by amputation through the zone of injury (AMP-CTL) or a combination of these (BOP-AMP). The presence of HO was evaluated using radiographs, micro-CT and histology. HO developed in none of nine BOP-CTL, six of nine AMP-CTL, and in all 20 BOP-AMP rats. Exposure to blast overpressure increased the prevalence of HO.

This model may thus be used to elucidate cellular and molecular pathways of HO, the effect of varying intensities of blast overpressure, and to evaluate new means of prophylaxis and treatment of heterotopic ossification.

Cite this article: Bone Joint J 2015;97-B:572–6

The development of a rat model to investigate the formation of blast-related post-traumatic heterotopic ossification

BACKGROUND: Sciatic neuropathy associated with acetabular fractures can result in disabling long-term symptoms. The purpose of this retrospective study was to evaluate the effect of sciatic nerve release on sciatic neuropathy associated with acetabular fractures and reconstructive acetabular surgery.

METHODS: Between 2000 and 2004, ten patients with sciatic neuropathy associated with an acetabular fracture were treated with release of the sciatic nerve from scar tissue and heterotopic bone. Additional surgical procedures included open reduction and internal fixation of the acetabulum (five patients), removal of hardware and total hip arthroplasty (three patients), and removal of hardware alone (one patient). The average age of the patients was forty-three years. All patients were followed with serial examinations and assessments for a minimum of one year (average, twenty-six months).

RESULTS: All patients had partial to complete relief of radicular pain, of diminished sensation, and of paresthesias after the nerve release. Four of seven patients with motor loss and two of five patients with a footdrop demonstrated improvement in function after the nerve release. No patient had evidence of worsening on neurologic examination after the release.

CONCLUSIONS: Sciatic nerve release during reconstructive acetabular surgery can decrease the sensory symptoms of preoperative sciatic neuropathy associated with a previous acetabular fracture. Motor symptoms, however, are less likely to resolve following nerve release.

LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

ORIGINAL ABSTRACT CITATION: “Sciatic Nerve Release Following Fracture or Reconstructive Surgery of the Acetabulum” (2007;89:[1432-7][1], July 2007

 [1]: /lookup/volpage/89/1432

Sciatic nerve release following fracture or reconstructive surgery of the acetabulum.

:A complete temporary sciatic nerve interruption occurred after a posterior fracture-dislocation of the hip joint. Ectopic new bone formation accounted for the interruption in nerve conduction. Neurolysis was done two months after the initial injury. Partial recovery of motor power and sensa

Paul Derian

Papers

Sciatic nerve entrapment by ectopic bone after posterior fracture-dislocation of the hip.