Somatosensory evoked potential monitoring in the surgical management of acute acetabular fractures

Sciatic nerve injury after acetabular fractures: a meta-analysis of incidence and outcomes

PURPOSE

To investigate the incidence and the outcome of post-traumatic and iatrogenic sciatic nerve palsy (SNP) associated with fractures of the acetabulum. The results of sciatic nerve grafting for treatment were also investigated.

METHODS

PUBMED, SCOPUS and COCHRANE databases were searched for longitudinal observational studies reporting sciatic nerve palsy related to acetabular fractures in adult patients over the last 20 years. Data regarding patients demographics, type of acetabular fracture, rate of post traumatic and iatrogenic sciatic nerve palsies as well as recovery rate are reported. Studies were assessed for their quality. Random effects meta-analyses were carried out to pool overall proportions of SNP incidence and complete recovery. Variations in SNP incidence by main study characteristics were assessed by subgroup analysis and meta-regression. A narrative review of sciatic nerve grafting was also conducted.

RESULTS

Twenty studies reporting 44 post-operative and 18 iatrogenic SNPs in 651 patients were reviewed. The pooled incidence of posttraumatic SNP was 5.1% (95% CI 2.7-8.2%). The pooled incidence of iatrogenic SNP was 1.4% (95% CI 0.3-2.9%). Complete recovery of post-traumatic and iatrogenic SNP occurred in 64.7% (95% CI 41.7-85.4%) and 74.1% (95% CI 31.5-100%), respectively.

CONCLUSION

A favorable outcome of both post-traumatic and iatrogenic SNP related to acetabular fractures has been found. Due to the poor results of sciatic nerve grafting, a "wait and see" approach may be the best option, in cases of a contused but anatomically intact sciatic nerve.

Is intraoperative neuromonitoring effective in hip and pelvis orthopedic and trauma surgery? A systematic review

INTRODUCTION

Sciatic nerve injury is an uncommon but potentially devastating complication in hip and pelvis surgery. Intraoperative nerve monitoring (IONM) was applied since the seventies in neurosurgery and spine surgery. Nowadays, IONM has gained popularity in other surgical specialities including orthopaedic and trauma surgery. Aim of this systematic review is to resume the literature evidences about the effectiveness of intraoperative monitoring of sciatic nerve during pelvic and hip surgery.

METHODS

Two reviewers (GC and MD) independently identified studies by a systematic search of PubMed and Google Scholar from inception of database to 10 January 2021. Inclusion criteria were: (a) English written papers, (b) use of any type of intraoperative nerve monitoring during traumatic or elective pelvic and hip surgery, (c) comparison of the outcomes between patients who underwent nerve monitoring and patient who underwent standard procedures, (d) all study types including case reports. The present review was conducted in accordance with the 2009 PRISMA statement.

RESULTS

The literature search produced 224 papers from PubMed and 594 from Google Scholar, with a total amount of 818 papers. The two reviewer excluded 683 papers by title or duplicates. Of the 135 remaining, 72 were excluded after reading the abstract, and 31 by reading the full text. Thus, 32 papers were finally included in the review.

CONCLUSIONS

The use of IONM during hip and pelvis surgery is debated. The review results are insufficient to support the routine use of IONM in hip and pelvis surgery. The different IONM techniques have peculiar advantages and disadvantages and differences in sensitivity and specificity without clear evidence of superiority for any. Results from different studies and different interventions are often in contrast. However, there is general agreement in recognizing a role for IONM to define the critical maneuvers, positions or pathologies that could lead to sciatic nerve intraoperative damage.

LEVEL OF EVIDENCE

Level 2.

Utility of Intraoperative Neuromonitoring during Minimally Invasive Fusion of the Sacroiliac Joint

Study Design. Retrospective case series. Objective. To document the clinical utility of intraoperative neuromonitoring during minimally invasive surgical sacroiliac joint fusion for patients diagnosed with sacroiliac joint dysfunction (as a direct result of sacroiliac joint disruptions or degenerative sacroiliitis) and determine stimulated electromyography thresholds reflective of favorable implant position. Summary of Background Data. Intraoperative neuromonitoring is a well-accepted adjunct to minimally invasive pedicle screw placement. The utility of intraoperative neuromonitoring during minimally invasive surgical sacroiliac joint fusion using a series of triangular, titanium porous plasma coated implants has not been evaluated. Methods. A medical chart review of consecutive patients treated with minimally invasive surgical sacroiliac joint fusion was undertaken at a single center. Baseline patient demographics and medical history, intraoperative electromyography thresholds, and perioperative adverse events were collected after obtaining IRB approval. Results. 111 implants were placed in 37 patients. Sensitivity of EMG was 80% and specificity was 97%. Intraoperative neuromonitoring potentially avoided neurologic sequelae as a result of improper positioning in 7% of implants. Conclusions. The results of this study suggest that intraoperative neuromonitoring may be a useful adjunct to minimally invasive surgical sacroiliac joint fusion in avoiding nerve injury during implant placement.

Sciatic nerve injury associated with acetabular fractures

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.

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

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.

Functional Outcome after Operative Treatment of Displaced Fractures of the Acetabulum: A 12-month to 5-year Follow-up Investigation

PURPOSE

To review our experience with 82 surgically treated displaced acetabular fractures over a 4-year period.

PATIENTS AND METHODS

Ninety-three consecutive displaced acetabular fractures were consecutively operated on at Level I Trauma Center from January 1, 2000 through December 31, 2003, and 82 were available for review with a minimum of 12-month follow-up. Clinical (Merle D'Aubigné modified by Matta et al.) and radiographic (Matta) outcomes were evaluated. Complications and secondary operative procedures were documented.

RESULTS

Anatomical reduction was achieved in 89% of the patients. At follow-up examination 12-60 months postoperatively (mean 32 months), clinical results were satisfactory in 65 patients (79.2% of the cases), with 14 excellent and 51 good results, and roentgenographic results were satisfactory in 70 patients (85.4% of the cases). Complications included a 12.2% incidence of sciatic nerve palsy (10 patients, two postoperative and eight posttraumatic), a 2.4% incidence of intraoperative vascular lesion (one external iliac artery and one external iliac vein), a 1.2% incidence of postoperative loss of reduction, a 1.2% incidence of infection, a 1.2% incidence of Brooker et al. class IV heterotopic ossification, a 2.4% incidence of posttraumatic osteoarthritis, and a 2.4% incidence of osteonecrosis of the femoral head.

CONCLUSIONS

Operative treatment is an effective method for the management of displaced acetabular fractures. Clinical and roentgenographic results correlate closely with an anatomic reduction. Low complication rate can be expected if adequate preoperative assessment and planning is performed. Strategies to minimize the risk of thromboembolism and heterotopic ossification on the basis of mechanical pneumatic compression and antiinflammatory nonsteroidal drugs, respectively, are reliable techniques for these injuries.

Surgical treatment of displaced fractures of posterior column and posterior wall of the acetabulum

We evaluated the results of open reduction and internal fixation of displaced posterior wall and posterior column fractures of the acetabulum. This was a prospective clinical evaluation of such cases where the main surgical strategy was open reduction and internal fixation with interfragmentary screws and reconstruction plates. Data on 11 patients treated by open reduction (all via Kocher-Langenbech approach)/internal fixation with interfragmentary screws and reconstruction plates were collected. The follow-up period was 61 (18-102) months. Reduction with a fracture gap of less than 2mm without articular stepping was achieved in all 11 cases. Postoperative complications developed in five patients, including subcutaneous haematoma in one, avascular necrosis of the femoral head (AVNFH) in one and heterotopic ossification (HO) in three. All but the patient with AVNFH, had anatomic radiological reduction, and good to excellent functional results. Open reduction and internal fixation with interfragmentary screws and reconstruction plates is the treatment of choice in displaced posterior wall and posterior column fractures of the acetabulum.

Iatrogenic nerve injury in acetabular fracture surgery: a comparison of monitored and unmonitored procedures

OBJECTIVES

To review our experience with iatrogenic nerve injuries and to evaluate the efficacy of intraoperative monitoring in a large consecutive series of operatively treated acetabular fractures.

DESIGN

Retrospective, nonrandomized.

SETTING

Level I Trauma Center, January 1, 1992 through December 31, 1998.

PATIENTS/PARTICIPANTS

A total of 256 consecutive acetabular fractures were operatively treated at our institution; 140 unmonitored procedures and 112 monitored procedures were available for review. The decision to use monitoring was at the discretion of the treating surgeon.

INTERVENTION

Open reduction and internal fixation of the acetabular fracture.

MAIN OUTCOME MEASUREMENT

Preoperative and postoperative neurologic examinations, fracture type, use of traction, dislocation, operative approach, and complications were analyzed. Motor strength, sensation, the need for gait aids, orthoses, and extent of recovery were evaluated.

RESULTS

Traumatic nerve palsies were present in eleven of 140 (7.9 percent) unmonitored and thirteen of 112 (11.6 percent) monitored fractures (p = 0.314). There were fourteen iatrogenic sciatic nerve palsies in 252 cases (5.6 percent). There were four iatrogenic sciatic palsies (2.9 percent) in the unmonitored group and ten iatrogenic palsies (8.9 percent) in the monitored group (p = 0.037). In the unmonitored group one of eighty-one Kocher-Langenbeck approaches (1.2 percent), two of fifty-two ilioinguinal (3.9 percent), and one of three extended iliofemoral approaches developed a sciatic palsy. In the monitored group six of seventy-seven Kocher-Langenbeck approaches (7.8 percent), three of twenty-five ilioinguinal (12 percent), and one of six combined approaches (16.7 percent) developed a sciatic palsy. In seven of the ten iatrogenic palsies in the monitored group, the intraoperative monitoring was normal. Seventy-six patients were monitored with somatosensory evoked potential alone, and nine had iatrogenic injuries (11.8 percent). Thirty-six patients were monitored with somatosensory evoked potential and electromyography, and one had an iatrogenic injury (2.8 percent) (p = 0.164). Clinical follow-up was available for three of the four patients with iatrogenic injuries in the unmonitored group, with a mean follow-up of twenty-seven months (range 8 to 60 months). Two patients had full motor recovery at a mean of six months, and one had no recovery at fourteen months.

CONCLUSIONS

The use of intraoperative monitoring did not decrease the rate of iatrogenic sciatic palsy. Further study involving larger prospective, randomized methodology appears warranted. Sciatic nerve injury was more common in ilioinguinal approaches in both groups, likely due to reduction techniques for the posterior column performed with the hip flexed, placing the sciatic nerve under tension.

Perioperative complications associated with operative treatment of acetabular fractures

BACKGROUND

Perioperative complications in a large number of consecutive patients with displaced acetabular fractures treated operatively were evaluated in an effort to elucidate potentially preventable complications.

METHODS

Perioperative complications were identified and evaluated in 131 consecutive patients with displaced acetabular fractures treated operatively using the Kocher-Langenbeck surgical exposure. The perioperative complications were identified using a registry.

RESULTS

There were a total of 76 complications related to the acetabular fracture and patient polytrauma. Eighteen complications resulted from technical errors and the patient's postoperative course. Obese patients frequently had unusual perioperative complications.

CONCLUSION

Perioperative complications occur commonly in patients with displaced acetabular fractures treated operatively using a Kocher-Langenbeck surgical exposure. Some of these complications may be avoidable, and are related to polytrauma. Most technical complications should be avoidable. Unusual complications were identified, especially in obese patients.

Cerclage wiring in displaced both-column fractures of the acetabulum

We evaluated the effect of cerclage wiring in the open reduction and internal fixation of displaced both-column fractures of the acetabulum. This was a prospective clinical evaluation of such cases where the main surgical strategy was open reduction and internal fixation with cerclage wire and supplemental reconstruction plates. Data on 35 cases treated by open reduction (all via the triradiate approach)/internal fixations with cerclage wire and reconstruction plates were collected. The follow-up period was 40 months (18-69). Reduction with a fracture gap of less than 2 mm without articular stepping was achieved in all 35 cases. Postoperative complications developed in seven cases, including subcutaneous haematoma in two, wound infection in two and heterotopic ossification in three. All the complications had no adverse effect on the clinical outcome, and all the cases had good to excellent final results. Cerclage wiring is very useful and effective in the reduction and fixation of displaced both-column fractures of the acetabulum, and supplemental fixation with reconstruction plates and screws is necessary.

Monitoring of somatosensory and motor evoked potentials during open reduction and internal fixation of pelvis and acetabular fractures

Monitoring of motor and somatosensory evoked potentials provides instantaneous intraoperative assessment of a patient's neurologic status. Monitoring of the sciatic nerve through motor and somatosensory evoked potentials can be used during open reduction and internal fixation of pelvic and acetabular fractures. A review of 12 pelvic and acetabular fractures treated with open reduction and internal fixation was conducted and assessed with a combination of intraoperative motor and somatosensory evoked potential monitoring. Results revealed intraoperative motor evoked potential monitoring was 100% sensitive and 100% specific in predicting postoperative sciatic nerve deficits, whereas somatosensory evoked potentials were not accurate in predicting postoperative sciatic nerve deficits. Combined monitoring of the sciatic nerve with motor and somatosensory evoked potentials is beneficial at predicting postoperative sciatic nerve deficits during open reduction and internal fixation of pelvic and acetabular fractures.

A review of the treatment of hip dislocations associated with acetabular fractures

Traumatic dislocation of the hip is an extremely severe injury. Although previously considered an uncommon lesion, it now is seen more often as a result of motor vehicle accidents. In most cases, dislocation of the hip is associated with fractures of the acetabulum, which ultimately can result in a higher incidence of complications than the complications observed in pure simple dislocations. Early recognition and prompt closed reduction of the dislocated hip constitute the cornerstone of proper treatment of this injury. Once the dislocation is reduced, definitive treatment of the acetabular fracture can be delayed to obtain a precise diagnostic evaluation. If surgical reconstruction of the acetabular fracture is indicated, it is done best in the first 10 days after the injury. A few patients in whom nonconcentric reduction, failed closed reduction, or impaired neurologic status occurs after reduction will require early open reduction and internal fixation of the fracture. Complications can be caused by the initial injury or by the treatment. Avascular necrosis of the femoral head, degenerative osteoarthritis, and heterotopic ossification are the main complications encountered in patients with unsatisfactory final results. Despite a perfect reduction of the hip dislocation and anatomic reduction of the acetabular fracture, a significant degenerative process of the hip is expected when the patient is assessed at long-term followup.

Intraneural sciatic nerve pressures relative to the position of the hip and knee: a human cadaveric study

OBJECTIVES

To determine the effects of ipsilateral hip and knee position on intraneural sciatic nerve pressures.

DESIGN

Intraneural sciatic nerve pressures measured in intact, fresh cadaveric specimens relative to ipsilateral hip and knee positions.

LOCATION

Medical school anatomy laboratory.

SUBJECTS

Randomly acquired adult cadavers.

INTERVENTION

Pressure transducer placed within the sciatic nerve distal to the femoral attachment of the gluteus maximus. Intraneural pressures measured with the hip placed in 0, 45, and 90 degrees of flexion while the knee was positioned in 90, 45, and 0 degrees of flexion.

MAIN OUTCOME MEASUREMENTS

Tissue fluid pressures within the sciatic nerve relative to the position of the ipsilateral hip and knee. Tissue fluid pressure within the sciatic nerve exceeded previously defined critical thresholds for alteration of neural microcirculation and function. Although increased intraneural pressures were realized as the hip was positioned in greater flexion and the knee was extended, clinically relevant pressures were realized only when the hip was flexed to 90 degrees and the knee was fully extended. Pressures with the limbs in these positions were fifty-five millimeters of mercury (range 38 to 74 millimeters of mercury).

RESULTS

With the hip held flexed to 90 degrees, statistically significantly increased intraneural pressures were measured as the knee was extended from 90 to 45 degrees of flexion (p = 0.048) and again from 45 to 0 degrees of flexion (p < or = 0.01). With the knee positioned in 45 degrees of flexion, statistically significantly increased intraneural pressures were measured as the hip was flexed from 45 to 90 degrees (p < or = 0.0062). When the knee was held fully extended, statistically significantly increased intraneural pressures were measured as the hip was flexed from 0 to 45 degrees of flexion (p = 0.0006) and again when the hip was brought from 45 to 90 degrees of flexion (p < or = 0.01).

CONCLUSIONS

Intraneural sciatic nerve pressures are influenced by the position of the ipsilateral hip and knee. The magnitude of the pressure elevation appears to be related to the excursion of the nerve as the linear distance between the greater sciatic notch and the distal aspect of the leg increases. Intraneural tissue fluid pressures measured within a localized section of the sciatic nerve appeared to exceed published critical thresholds for alterations of blood flow and neural function only when the hip was flexed to 90 degrees and the knee was fully extended.

Electromyography monitoring for percutaneous placement of iliosacral screws

OBJECTIVE

To report our experience with the use of continuous electromyography (EMG) for placement of iliosacral screws.

DATA SOURCES

Concurrently acquired data as well as patient charts, intraoperative EMG records, x-rays, and pelvic computed tomography (CT) scans.

DESIGN

The monitored group of twenty-nine patients was studied prospectively. The control group consisted of twenty-two patients studied retrospectively.

SETTING

Level One trauma center.

METHODS

Continuous electromyograms were recorded for twenty-nine patients and compared with those from a group of twenty-two antecedent patients who were not monitored. The primary parameter of interest of this study was the presence or absence of neurologic change after iliosacral screw placement. This information was obtained prospectively in the study group and by retrospective review in the historical control.

RESULTS

Four patients in the control group had postoperative and/or sensory motor changes prompting a postoperative CT scan; in each of these patients, a misdirected screw was identified and subsequently removed in a second procedure. There were no neurologic changes subsequent to placement in the twenty-nine patients who were monitored (7.5 percent versus 0 percent; p = 0.029, Fisher's exact test). All monitored patients had postoperative CT scans and showed the screw in a safe position with no significant violations of the S1 tunnel.

CONCLUSION

Continuous EMG monitoring during iliosacral screw placement may be a useful neuroprotective tool.

Surgical treatment of displaced acetabular fractures - 72 cases followed for 10 (6-14) years

Seventy-two displaced acetabular fractures managed surgically were evaluated retrospectively. The follow-up period was 10 (6-14) yr. The commonest fractures were posterior wall (28) and both columns (10). The surgical approaches were Kocher-Langenbeck (47), ilioinguinal (19) and extended iliofemoral (6). No neural monitoring was used in operations and no preventive agents for heterotopic ossification or thromboembolism were used perioperatively. Reduction was rated congruent in 59 (81.9%) and noncongruent in 13 (18.1%). The early postoperative complications were 1 vascular injury, 1 iatrogenic sciatic nerve injury, 1 deep vein thrombosis and 2 wound infections. The late complications were heterotopic ossification in 20 patients, avascular necrosis of the femoral head in 4 and symptomatic arthritis in 10. Functional outcomes were rated as excellent in 31, good in 23, fair in 7 and poor in 11. Our results show that traditional management is effective enough for displaced acetabular fractures.

Evaluation of intraoperative nerve-monitoring during insertion of an iliosacral implant in an animal model

BACKGROUND

The use of continuous electromyographic and somatosensory-evoked-potential monitoring systems has been advocated to assist in avoiding nerve-root injury during operations on the pelvic ring. More recently, it was suggested that stimulus-evoked electromyographic monitoring may further decrease the risk of iatrogenic nerve-root injury during posterior pelvic fixation by enabling the surgeon to determine the actual distance of an implant from a nerve root. The purpose of the current study was to evaluate the relative efficacy of these three methods of monitoring for minimizing the risk of neural injury during the placement of iliosacral implants.

METHODS

While the function of the first sacral nerve root was monitored with the use of stimulus-evoked electromyographic, continuous electromyographic, and somatosensory-evoked-potential monitoring techniques, a 2.0-millimeter stainless-steel Kirschner wire was progressively inserted, guided by a high-speed computerized tomographic scanner, into the first sacral body of seventeen hemipelves in nine dogs. The end point was contact with the nerve as demonstrated by the computerized tomographic images. It was expected that this end point would be heralded by a burst of spontaneous electromyographic activity and an abnormal somatosensory-evoked-potential signal. Anatomical dissection at the completion of the study documented the final position of the Kirschner wire.

RESULTS

Anatomical dissection demonstrated compression or penetration of the nerve root in sixteen of the seventeen specimens. A spontaneous burst of electromyographic activity was not recorded for any specimen on continuous electromyographic monitoring; this finding was significantly different from what had been expected (p<0.001). Because of technical problems, somatosensory evoked potentials could be recorded for only twelve hemipelves that had nerve-root compression or penetration, and abnormal somatosensory evoked potentials were recorded for only one of the twelve; this finding was significantly different from what had been expected (p<0.001). A total of 113 stimulus-evoked electromyographic data points were obtained. The correlation coefficient for the relationship between the current threshold recorded with stimulus-evoked electromyographic monitoring and the distance of the wire from the nerve was 0.801 (p<0.001). The actual measured current thresholds were of an observed proportion not different from what had been expected (p = 0.48).

CONCLUSIONS

Continuous electromyographic and somatosensory-evoked-potential monitoring techniques failed to indicate contact with the nerve root reliably in this animal model. However, stimulus-evoked electromyographic monitoring consistently provided reliable information indicating the proximity of the implant to the nerve root.

Operative treatment of acetabular fractures through the extensile Henry approach

OBJECTIVE

The purpose of this study was to evaluate the previously unreported application of the extensile Henry approach to the operative treatment of acetabular fractures.

METHODS

Thirty-one cases were retrospectively reviewed at an average follow-up of 18.5 months.

RESULTS

There were 8 simple and 23 complex associated fracture patterns. The average operative time was 4.5 hours, and the average blood loss was 1,160 mL. Reduction was anatomic in 26 patients (84%), satisfactory in 4 patients (13%), and unsatisfactory in 1 patient (3%). Radiographic results at follow-up were 25 excellent results, 4 good results, and 2 poor results. Twenty-six patients reported no limitation of ordinary activities, whereas five patients had to modify their activities because of pain. No heterotopic ossification occurred in 24 patients (77%). In the seven patients with heterotopic ossification, only one patient had a significant decrease in hip range of motion. Additional complications were two cases of superficial wound infection, one case of hardware failure, and two cases of avascular necrosis of the femoral head. There were no iatrogenic injuries to the sciatic nerve, nor was there any development of flap necrosis.

CONCLUSION

The extensile Henry approach is a versatile approach offering an excellent exposure for surgical treatment of acetabular fractures. The rate of complications is comparable with or lower than that of other surgical approaches. By providing a direct exposure of the posterior pelvis, the extensile Henry approach has the advantage of minimizing the risk of iatrogenic injury to the sciatic nerve. In addition, the incidence of clinically significant heterotopic ossification may be reduced through the use of low-dose radiation prophylaxis.

Evaluation of inferior alveolar nerve function during distraction osteogenesis in the dog

PURPOSE

A series of electrophysiologic studies were performed in a canine model to evaluate inferior alveolar nerve (IAN) function during distraction osteogenesis of the mandible.

MATERIALS AND METHODS

Fourteen dogs, including two controls, were used in the study. Twelve dogs underwent a 10-mm bilateral mandibular lengthening with an intraoral bone-borne appliance and midbody osteotomy. By using sensory nerve action potentials, IAN function was assessed before and immediately after surgery, before and at the completion of distraction, and before necropsy after 4, 6, or 8 weeks of fixation.

RESULTS

Twelve of the 24 nerves showed a complete loss of evoked potential after surgery without recovery at any point throughout the study. Acute nerve injury caused by either the osteotomy or screw encroachment was identified at necropsy. The other 12 nerves showed reproducible responses after surgery. Eight of these nerves had significant amplitude attenuation of the evoked potentials, which was identified at necropsy as a result of acute injury. The remaining four nerves did not show significant evoked potential abnormalities and appeared to be grossly normal at necropsy. During distraction, the amplitude of evoked potentials in all 12 nerves remained at the postoperative level, whereas latency showed a significant delay. In 7 of these 12 nerves, various degrees of evoked potential recovery were identified at the completion of the study.

CONCLUSIONS

The high incidence of acute IAN injury in the current study was primarily related to device construction and osteotomy technique. If acute nerve injury is avoided at surgery, distraction osteogenesis with 10 mm mandibular lengthening appears to produce minimal deleterious effect on IAN function.

Controversies in acetabular fractures

Open reduction and internal fixation has become the standard of care for the treatment of most displaced acetabular fractures. As surgical techniques have become refined, long term results of surgical fixation have improved. During the past 10 to 15 years, several controversies have surfaced in the orthopaedic literature regarding the treatment of acetabular fractures. The recent literature regarding acetabular fixation was reviewed. Controversies include the most efficacious surgical approach for complex acetabular fractures; the effectiveness of intraoperative sciatic nerve monitoring; the most effective method of prophylaxis against deep vein thrombosis; and the indications for and method of prophylaxis against heterotopic bone formation.

Incidence of sciatic nerve injury in operatively treated acetabular fractures without somatosensory evoked potential monitoring

OBJECTIVE

The authors investigated the incidence of sciatic nerve injury associated with the operative repair of acetabular fractures without somatosensory evoked potential (SSEP) monitoring.

DESIGN

Retrospective case review of prospectively documented pre- and postoperative physical examinations.

SETTING

A level I trauma hospital.

PATIENTS

All the cases were reviewed of patients with open reduction and internal fixation of acetabular fractures who underwent posterior or extensile approaches (129) performed by the three senior authors from January 1991 through March 1995.

INTERVENTION

Intraoperative SSEP monitoring was not used during any of the procedures. The procedures included sixty-five Kocher-Langenbeck approaches, thirty-four combined Kocher-Langenbeck and iliofemoral approaches, four extended iliofemoral approaches, and four triradiate approaches.

RESULTS

One case of iatrogenic nerve injury resulted in a sensory deficit. No patient suffered an exacerbation of a preexisting nerve injury.

CONCLUSION

The results of this study indicate that open reduction and internal fixation of acetabular fractures, using current techniques with visualization and protection of the sciatic nerve, can reduce the incidence of neurologic injury to a negligible level. There does not appear to be justification for the addition of SSEP or electromyograph modalities to the operative routine of experienced surgeons.

Intraoperative monitoring of motor pathways during operative fixation of acute acetabular fractures

OBJECTIVE

To determine whether intra-operative spontaneous electromyography (EMG) was superior to somatosensory evoked potentials (SSEP) in the prevention of iatrogenic sciatic nerve injury.

DESIGN

Prospective, consecutive.

SETTING

Tertiary referral, teaching Hospital in New York City.

PATIENTS

Seventy-four patients with acutely displaced acetabular fractures.

MAIN OUTCOME MEASURE

Group A consisted of 24 patients who underwent intraoperative sciatic nerve monitoring using SSEP only. Group B consisted of 50 patients who underwent monitoring using both SSEP and spontaneous EMG. Motor potentials were recorded from the tibialis anterior, peroneus longus, abductor hallucis, and flexor hallucis longus muscles. All patients had independent preoperative and postoperative evaluations by the same neurologist.

RESULTS

One iatrogenic sciatic nerve injury occurred in group A and none in group B. Prolonged sciatic nerve compromise, demonstrated by significant intraoperative SSEP changes, occurred 2.4 times per case in group A and only 0.8 times per case in group B. In group B, spontaneous EMG noted compromise an average of 3.6 times per case (p < 0.0001).

CONCLUSIONS

The results of this study support spontaneous EMG as feasible and superior to SSEP monitoring in detecting intraoperative sciatic nerve comprise in acute acetabular fracture surgery. Spontaneous EMG permits earlier detection of intraoperative sciatic nerve comprise, allowing a more rapid response of the surgical team to noxious nerve stimuli. This may prevent permanent neurologic sequellae.

Acute Pelvic Fractures: II. Principles of Management

The past two decades have seen many advances in pelvic-trauma surgery. Provisional fixation of unstable pelvic-ring disruptions and open-book fractures with a pelvic clamp or an external frame with a supracondylar pin has proved markedly beneficial in the resuscitative phase of management. In the completely unstable pelvis, external clamps and frames can act only as provisional fixation and should be combined with skeletal traction. The traction pin is usually used only until a definitive form of stabilization can be applied to keep the pelvic ring in a reduced position. If the patient is too ill to allow operative intervention, the traction pin can remain in place with the external frame as definitive treatment. Symphyseal disruptions and medial ramus fractures should be plated at the time of laparotomy. Lateral ramus fractures can usually be controlled with external frames. A role has been suggested for percutaneous retrograde fixation of the superior pubic ramus; however, the benefits to be gained may not be enough to outweigh the serious risks of penetrating the hip, and this technique should therefore be used only by surgeons trained in its performance. The techniques for posterior fixation are becoming more standardized, but all still carry significant risks, especially to neurologic structures.

Fractures of posterior wall of acetabulum

Fractures of the posterior wall of the acetabulum form a special group in acetabular fractures. This study aims to evaluate the results in the management of such fractures. Thirty-two patients with fractures of posterior wall of acetabulum were reviewed retrospectively. The follow-up period was 7 (range 3-10) years. Twenty-four were associated with initial posterior dislocations. Twenty-seven were managed with open reduction and internal fixation, while the remainder were managed conservatively. Reductions were rated as congruent in 30 cases and as noncongruent in 2. The functional results were excellent in 16 cases, good in 10, fair in 2, and poor in 4. Two early complications were met, namely 1 iatrogenic sciatic nerve injury and 1 superficial wound infection. Sixteen late complications were noted, including 10 heterotopic ossifications, 3 avascular necroses of femoral head, and 3 symptomatic arthritides. The incidence of late complications was high, but the functional results were generally satisfactory. Congruent reduction was the key in obtaining satisfactory results in the management of these fractures.