Intraoperative monitoring of motor pathways during operative fixation 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.

Medium-Term Patient-Reported Quality of Life and Activities of Daily Living in Surgically Treated Trauma Patients With Pelvic, Acetabular or Combined Pelvic and Acetabular Fractures in a Retrospective Single-Center Study

OBJECTIVE

To gain more insights in the medium-term patient-reported quality of life (QoL), activities of daily living (ADL), and number of complications in trauma patients with an acetabular fracture (AF), a pelvic fracture (PF), and those with a surgically combined pelvic and AF (PAF).

DESIGN

Retrospective single-center study.

SETTING

Level I academic trauma center.

PATIENTS/PARTICIPANTS

51 trauma patients with PF, AF, or PAF who were surgically treated between 2014 and 2017.

INTERVENTION

Open reduction and internal fixation.

MAIN OUTCOME MEASUREMENTS

Primary outcome measures are patient-reported outcome questionnaire, which includes 2 items, the QoL, as measured with the Short Form-12, and the ADL, as measured with the Lower Extremity Functional Scale. The secondary outcome parameter was the occurrence of complications during a follow-up of at least 2 years.

RESULTS

The mean physical component score (PCS) of the QoL (P = 0.03) and the ADL (P = 0.03) were significantly higher in patients with AF compared with patients with PF. The incidence of the overall postoperative complications did not significantly differ between the PF, AF, and PAF groups (P = 0.28).

CONCLUSIONS

This study found that the PCS of the QoL and the ADL in surgically treated trauma patients with PF were significantly lower compared with patients with AF. No significant differences were found in overall complication rate between the PF, AF, and PAF groups.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Case report: ischial stress fracture non-union in a college football player

Stress fractures are common injuries associated with repetitive high-impact activities, often in high-level athletes and military recruits. Although predominantly occurring in the lower extremities, stress fractures may occur wherever there is a sudden increase in frequency or intensity of activity, thereby overloading the yield point of the local bone environment. Ischial stress fractures are a rarely diagnosed cause of pain around the hip and pelvis. Often, patients present with buttock pain with activity, which can be misdiagnosed as proximal hamstring tendonitis or avulsion. Here, we report a case of a college football player who was diagnosed with an ischial stress fracture which went on to symptomatic non-union after extensive conservative management. We treated his ischial non-union with open reduction internal fixation utilizing a tension band plate and screws. This interesting case highlights an uncommon cause of the relatively common presentation of posterior hip pain and describes our technique for addressing a stress fracture non-union in the ischium.

Surgical Approaches to the Acetabulum and Modifications in Technique

Acetabular injuries are often difficult to treat because the acetabulum is surrounded by many important structures, making access difficult and sometimes dangerous. Surgical exposures of the acetabulum are complex and require significant skill and in-depth knowledge of pelvic anatomy. Each approach has its limitations, and the potential morbidity associated with these exposures can be daunting. Recent modifications to traditional acetabular approaches have been developed to address these issues. Knowledge of the ilioinguinal, Kocher-Langenbeck, and extended iliofemoral surgical exposures and the potential drawbacks associated with each approach are essential to optimize treatment and minimize morbidity.

Reducing the risk of nerve injury during Bernese periacetabular osteotomy

The modified Smith–Petersen and Kocher–Langenbeck approaches were used to expose the lateral cutaneous nerve of the thigh and the femoral, obturator and sciatic nerves in order to study the risk of injury to these structures during the dissection, osteotomy, and acetabular reorientation stages of a Bernese peri-acetabular osteotomy.

Injury of the lateral cutaneous nerve of thigh was less likely to occur if an osteotomy of the anterior superior iliac spine had been carried out before exposing the hip.

The obturator nerve was likely to be injured during unprotected osteotomy of the pubis if the far cortex was penetrated by > 5 mm. This could be avoided by inclining the osteotome 45° medially and performing the osteotomy at least 2 cm medial to the iliopectineal eminence.

The sciatic nerve could be injured during the first and last stages of the osteotomy if the osteotome perforated the lateral cortex of ischium and the ilio-ischial junction by > 10 mm.

The femoral nerve could be stretched or entrapped during osteotomy of the pubis if there was significant rotational or linear displacement of the acetabulum. Anterior or medial displacement of < 2 cm and lateral tilt (retroversion) of < 30° were safe margins. The combination of retroversion and anterior displacement could increase tension on the nerve.

Strict observation of anatomical details, proper handling of the osteotomes and careful manipulation of the acetabular fragment reduce the neurological complications of Bernese peri-acetabular osteotomy.

Cite this article: Bone Joint J 2015;97-B:636–41.

Gait and function as tools for the assessment of fracture repair - the role of movement analysis for the assessment of fracture healing

Assessment of gait and function might be as sensitive tool to monitor the progress of fracture healing. Currently available assessment tools for function use instrumented three dimensional gait analysis or pedobarography. The analysis is focused on gait or movement parameters and seeks to identify abnormalities or asymmetries between legs or arms. The additional inclusion of muscle function by electromyography can further elucidate functional performance and its temporal development. Alternative approaches abstain from directly assessing function in the laboratory but rather determine the amount of activities of daily living or the mere ability to perform defined tasks such as walking, stair climbing or running. Some of these methods have been applied to determine recovery after orthopaedic interventions including fracture repair. The combination of lab-based functional measurements and assessment of physical activities in daily live may offer a valuable level of information about the gait quality and quantity of individual patients which sheds light on functional limitations or rehabilitation of gait and mobility after a disease or injury and the respective conservative, medical or surgical treatment.

Neurophysiologic monitoring can predict iatrogenic injury during acetabular and pelvic fracture fixation

BACKGROUND

Nerve injury during acetabular and pelvic fracture fixation can have devastating consequences for trauma patients already in a compromised situation.

QUESTIONS/PURPOSES

This study aims to evaluate the efficacy of multimodality intraoperative neurophysiologic monitoring during acetabular and pelvic fracture fixation in identifying emerging iatrogenic nerve injury.

METHODS

Sixty patients were retrospectively identified after surgical fixation following acetabular or pelvic fracture. Neuromonitoring during surgery was performed using three different modalities, transcranial electric motor evoked potential (tceMEP), somatosensory evoked potential (SSEP), and electromyographic (EMG) monitoring. Each modality was evaluated for sensitivity and specificity of detecting an intraoperative nerve injury.

RESULTS

tceMEP monitoring was found to be 100% sensitive and 86% specific at detecting an impending nerve injury. The sensitivity and specificity of SSEP were 75% and 94%, while EMG sensitivity was unacceptably low at 20% although specificity was 93%.

CONCLUSIONS

Multimodality neuromonitoring of transcranial electric motor and peroneal nerve somatosensory evoked potentials with or without spontaneous EMG monitoring is a safe and effective method for detecting impending nerve injury during acetabular and pelvic surgery.

Operative treatment of acetabular fractures in an older population through a limited ilioinguinal approach

OBJECTIVES

To compare treatment of acetabular fractures in elderly patients through a limited approach versus a standard ilioinguinal approach and assess changes in outcome and morbidity.

DESIGN

Retrospective cohort comparison analysis.

SETTING

Tertiary referral center.

PATIENTS/PARTICIPANTS

Between January 1992 and January 2006, 143 patients 55 years of age or older were treated for acetabular fractures. Of these, 41 were treated through either a traditional or limited ilioinguinal approach. Patients with unilateral surgeries and a minimum follow-up of 2 years were included.

INTERVENTION

Open reduction and internal fixation of acetabular fractures through a limited (lateral two windows) approach versus traditional three window ilioinguinal approach.

OUTCOME MEASURES

Radiographic assessment of healing, reduction quality, progression to arthritis and total hip arthroplasty, operative time, length of stay, complications, SF-36, Musculoskeletal Functional Assessment, and the Short Musculoskeletal Functional Assessment.

RESULTS

The two groups were equivalent in terms of preinjury comorbidities, mechanism of injury, type and severity of fracture pattern, time to surgery, length of hospitalization, and incidence of postoperative complications. The overall rate of secondary total hip arthroplasty was 26.8% and was equivalent between the two groups. Functional outcome scores were comparable. The use of the lateral two windows was associated with a significant reduction in both blood loss and operative time.

CONCLUSIONS

The limited ilioinguinal approach to certain fracture patterns commonly seen in the elderly was associated with a decreased blood loss and surgical time. Moreover, there was no negative impact on outcomes in our cohort. The benefits of decreased blood loss and shorter operative time have a potential positive impact on management of these injuries.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Outcomes of acetabular fracture fixation with ten years' follow-up

We report the outcome of 161 of 257 surgically fixed acetabular fractures. The operations were undertaken between 1989 and 1998 and the patients were followed for a minimum of ten years. Anthropometric data, fracture pattern, time to surgery, associated injuries, surgical approach, complications and outcome were recorded. Modified Merle D'Aubigné score and Matta radiological scoring systems were used as outcome measures. We observed simple fractures in 108 patients (42%) and associated fractures in 149 (58%). The result was excellent in 75 patients (47%), good in 41 (25%), fair in 12 (7%) and poor in 33 (20%). Poor prognostic factors included increasing age, delay to surgery, quality of reduction and some fracture patterns. Complications were common in the medium- to long-term and functional outcome was variable. The gold-standard treatment for displaced acetabular fractures remains open reduction and internal fixation performed in dedicated units by specialist surgeons as soon as possible.

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.

Intraoperative electromyographic monitoring during periacetabular osteotomy

Periacetabular osteotomy has become the procedure of choice in many centers for the treatment of symptomatic hip dysplasia. Intraoperative real-time nerve monitoring has been advocated during acetabular fracture repair and complex total hip arthroplasties to prevent iatrogenic sciatic nerve injury. To the authors' knowledge there is no information concerning the use of intraoperative electromyographic monitoring during periacetabular osteotomy. The purpose of the current study was to investigate the use of intraoperative continuous electromyographic monitoring during periacetabular osteotomy in a relatively large consecutive series of patients as a mechanism to prevent nerve injury during surgery and as a prognostic indicator of neurologic function after periacetabular osteotomy. From September 1992 to July 1999, 140 consecutive periacetabular osteotomies were done in 127 patients at the authors' institution. There were 96 females and 31 males, with an average age of 32 years at the time of surgery. All patients had intraoperative electromyographic monitoring of femoral and sciatic innervated muscles. All patients were followed up for a minimum of 1 year, until complete resolution of neurologic deficits, or both. Thirty-six patients (26%) had abnormal electromyographic activity recorded during surgery. Seven patients (5%) had peroneal nerve deficits postoperatively including extensor hallucis longus and tibialis anterior weakness with loss of sensation in the first web space. Abnormal electromyographic activity was observed intraoperatively in five of the seven patients with postoperative deficits. Six of the seven injuries resolved completely. One patient with intraoperative electromyographic activity (0.7%) had a postoperative foot drop that persisted for greater than 1 year. There were no femoral, tibial, or obturator nerve deficits observed. Electromyographic monitoring appears to provide prediction of postoperative neurologic deficit.

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.

Spinal cord and nerve root monitoring during surgical treatment of lumbar stenosis

The author describes application of intraoperative neurophysiologic monitoring to surgical treatment of lumbar stenosis. Benefits of somatosensory and motor evoked potential studies during surgical correction of spinal deformity are well known and documented. Free-running and evoked electromyographic studies during pedicle screw implantation is an accepted practice at many institutions. However, the functional integrity of spinal cord, cauda equina, and nerve roots should be monitored throughout every stage of surgery including exposure and decompression. Somatosensory evoked potentials monitor overall spinal cord function. Intraoperative electromyography provides continuous assessment of motor root function in response to direct and indirect surgical manipulation. Electromyographic activities observed during exposure and decompression of the lumbosacral spine included complex patterns of bursting and neurotonic discharge. In addition, electromyographic activities at distal musculature were elicited by impacting a surgical instrument or graft plug against bony elements of the spine. All electromyographic events provided direct feedback to the surgical team and were regarded as a cause for concern. Simultaneously monitored evoked potential and electromyographic studies protect spinal cord and nerve roots during seemingly low-risk phases of a surgical procedure when neurologic injury may occur and the patient is placed at risk for postoperative myelopathy or radiculopathy.

Displaced acetabular fractures: indications for operative and nonoperative management

Displaced acetabular fractures are a challenging problem. In contradistinction to most conditions in which surgery is based on specific operative indications, displaced acetabular fractures should be considered an operative problem unless specific criteria for nonoperative management are met. These include a congruent hip joint on the anteroposterior and oblique (Judet) radiographs, an intact weight-bearing surface (as defined by roof arc and subchondral arc measurements on computed tomographic scans), and a stable joint. The final decision about the treatment method must also consider the patients functional demands, expectations, and physical condition and the physicians experience and institutional support for dealing with this type of injury. Displaced both-column fractures with secondary congruence may have better results than other displaced fractures. In older patients, nonoperative management may be effectively utilized. Understanding the current criteria for effective use of nonoperative treatment will help the surgeon make these difficult decisions.

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.

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.

Surgical treatment of acetabular fractures in elderly patients with osteoporotic bone

The incidence of acetabular fractures in the elderly has recently shown a marked increase due to the combination of greater longevity for the population as a whole and a relative decrease in the incidence of alcohol-related trauma in younger adults. The compromised physiologic reserve and the diminished healing capacity of the typical elderly patient have an adverse effect on the potential for a favorable clinical outcome. The presence of osteopenic bone or degenerative arthritis and the effects of previous radiation therapy to the hip and pelvis hamper diagnostic imaging and the utility of some treatment alternatives that were designed primarily for younger patients. The diverse clinical presentations include major polytrauma, minor trauma, and insufficiency fractures. An assessment of the prior health and functional status of the patient is crucial in determining the optimal therapeutic protocol. Treatment options vary according to the clinical presentation and include conservative methods, percutaneous fixation in situ, open reduction, and acute total hip arthroplasty. The feasibility of acute total hip arthroplasty rests on the use of newly developed techniques for minimally invasive stabilization of the acetabular fracture with cables and the application of morselized or structural autograft harvested from the femoral head. Whichever surgical method is chosen, the objective is rapid mobilization of the patient on a walker or crutches. Late complications that may occur after nonoperative or operative treatment include posttraumatic arthritis, nonunion, wound infection, and heterotopic bone formation.

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.