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Study design Radiology of the sacroiliac joint was investigated by obtaining different and multiple radiographs of cadaveric pelves marked with solder metal wire and radiopaque paint. Objectives To demonstrate the orientation of the sacroiliac joint on various, radiographic views. Summary of background data Interpretation of the sacroiliac joint projection on plain radiography is difficult. It requires an understanding and appreciation of its components and their orientation. Emphasizing the definition of the orientation of the plane of the joint on the different projection views of the sacroiliac joints can aid the orthopaedic surgeon in obtaining the proper radiographs and in the proper interpretation of the different radiographic views. Methods Nineteen sacroiliac joints from 10 cadaveric pelves, 5 male and 5 females were studied. Each joint was found to be composed of three portions: anterosuperior, middle, and posteroinferior portions, each lying in a different plane. Each sacroiliac joint was marked with solder wires and radiopaque paint to define the orientation of each of the three portions of the joint on radiographs. The following radiographic projection views were taken for each joint anteroposterior, lateral, inlet, craniocaudal axial, outlet, lithotomy and oblique views. For the oblique views, the angulation of the x-ray tube needed to view each portion of the joint tangentially was recorded. Results There was a wide variation in the orientation of the planes of the joint portions between the right and the left sides as well as between different pelves. Although the twisting of the plane of the whole joint produced by the successive examination of the portions could be either internal or external, it was the same bilaterally in a given specimen. The outlet and lithotomy views provided the best tangential representation of the two sacroiliac joints on one film. Conclusion The sacroiliac joint is composed of three portions oriented in different planes. To study the sacroiliac joints, it seems desirable to obtain an anteroposterior view of the pelvis with the patient in a lithotomy position; then, if needed, each joint can be radiographed separately by using oblique views. It is important to not that the plane of the articular portion of the joint can be directed from anterolateral to posteromedial, and therefore, the oblique views should be obtained accordingly.

Study design This study analyzed bony features of the posterior ilium and relevant vital structures using cadavers and dry ilium specimens. Objectives To determine quantitatively the safely zone of the posterior ilium and relevant vital structures with regard to bone graft harvesting. Summary of background data The most frequently used site for bone graft harvesting is the posterior ilium. However, complications related to posterior iliac bone harvesting, such as donor site pain, neurovascular injury, instability of the sacroiliac joint, and herniation of abdominal contents, are still major concerns. Very little research with regard to the quantitative study of the posterior ilium has been reported. Methods Six cadavers (four male, two female) were used for the first part of this study. The posterior superior iliac spine was determined as a reference landmark. The distances from the posterior superior iliac spine to the superior cluneal nerves, the gluteal line, and the superior gluteal vessels were measured. The second part of the study involved 30 adult, dry iliac bony specimens. The posterior iliac region (extra-articular portion) was divided into three zones, and the corresponding dimensions of these zones were measured. Results The average distances from the posterior superior iliac spine to the superior cluneal nerves, gluteal line, and superior gluteal vessels were 68.8, 26.6, and 62.4 mm, respectively. The average width, height, and maximum thickness for Zone 1 were 34, 27.8, and 17.1 mm, respectively; the measurements for Zone 2 were 16.5, 31.8, and 14.2 mm, respectively. The average height for Zone 3 was 20.4 mm, and the average maximum thickness was 16.8mm. Conclusion The ideal area of the posterior ilium for bone graft harvesting was found in Zone 1. Zones 2 or 3 may be considered it a greater quantity of cancellous bone graft is required; however, the risk of injury to the sacroiliac joint and superior gluteal vessels in these zones is increased.

This study analyzed the anatomic relationships between bony structures and soft tissues of the cervicothoracic junction.To provide composite reference data for intrasegmental and intersegmental gradients of anatomic variation within the cervical-thoracic junction.Because the risk of soft tissue damage during posterior spinal stabilization, an understanding of bony and soft tissue changes in the cervicothoracic junction is necessary.Three-hundred-twenty-four cross-sectional spinal segments from nine spines were analyzed to characterize cervicothoracic junctional anatomy.There were predictable cranial-to-caudal alterations in both bone and soft tissue anatomy of the cervicothoracic junction. Neural and vascular structures directly anterior to the lateral mass or transverse process and lateral to the pedicle tend to decrease in frequency, whereas measured parameters of the vertebrae increase in size from C5-T3, except for pedicle dimensions that tend to increase at the C7-T1 junction.The anatomic changes that occur within the cervicothoracic junction are consistent and predictable, and their recognition should lead to a better appreciation of their clinical implications.

Fractures of the body of the hamate are unusual. Eleven patients with coronal fractures of the hamate bone, all involving dislocation of the hamate-metacarpal joint, are reported. Routine roentgenograms were not helpful in delineating the presence of the injury in five patients; therefore, fracture diagnosis was not initially made in those patients. The average delay in diagnosis of this group was 10 days. A 30-degree pronated view, tomograms, and computed tomography scans may be necessary in the diagnosis of this injury. This fracture was found to be highly unstable. Ten patients underwent surgery for stabilization of their fractures and restoration of the congruity of the hamate-metacarpal joint. Four patients were treated with open reduction and internal fixation of the fracture. Six patients were treated with closed reduction and percutaneous pinning. All patients treated surgically had maintenance of reduction of their joints. One patient was treated with closed reduction and casting; reduction in this case was lost, and the patient developed residual subluxation of the hamate-metacarpal joint.

Study design Linear and angular measurements were performed on 128 vertebrae (16 spines) from C5 to T5. Objectives Vertebrae were studied to characterize vertebral shape and size changes in the cervico-thoracic region. Summary of background data Analysis of vertebral anatomy has been extensive and well characterized. Regions of transitional anatomy necessitate further study due to the often abrupt changes in anatomic relationships. Methods Two observers performed linear and angular measurements including pedicle width, height, and length, as well as pedicle-body, pedicle-lamina, lamina-transverse process, and pedicle-lamina angular measurements. Pedicle axis projection on the posterior aspect of the lamina was also calculated. Results The mean pedicle width ranged from 7.8 mm (T1) to 4.4 mm (T5). The body-pedicle angle decreased > 4 degrees per level in the transverse plane, from 50 degrees (C5) to 11 degrees (T5). The axial projection of the pedicle changed throughout the region (compared with level above) and was significant for T1. Conclusions Because of the complexities of the cervico-thoracic junction, additional characterization increases the knowledge of the anatomic relationships in this region.

Placement of screws in the sacrum is essential for assuring rigid fixation during instrumentation of the lumbosacral spine. However, the safest approach to obtaining sacral fixation has not been clearly delineated and is complicated by significant interpatient variation in sacral morphology. In the present study, CT evaluation of the S1 pedicle and sacral ala was performed in 10 cadavers and established "average" angles for screw placement. Placement of screws at the "averages" was undertaken and verified on CT. Violation, or near violation, of important anatomic landmarks was found in 4 of 10 specimens. As a result of this study, the authors contend that placement of screws in the sacrum at average angles presents unnecessary risks to important structures. The authors propose that each patient should undergo individualized preoperative CT evaluation to determine safe angles to minimize these risks.

Two-hundred-and-one patients with femoral shaft fractures were identified in a 5 year period at three institutions. Seven patients (3.5%) were found to have associated thoracic or lumbar fractures of various types. All resulted from high-velocity trauma. Four (57%) of these patients had thoracic or lumbar fractures that were undiagnosed on admission and before femoral fracture stabilization. A neurologic deficit persisted in four patients, and the possible contribution of femoral intramedullary rodding with positioning and traction must be considered. A high index of suspicion for thoracic and lumbar fractures is required when evaluating the high velocity trauma patient with a femoral shaft fracture. Presence of the thoracic or lumbar fracture may require initial spine stabilization or alter the method of femoral fracture treatment.

We studied the cases of 15 patients who underwent postoperative magnetic resonance imaging evaluation after being treated with metal spinal implants. Spine stabilization was required in traumatic injuries for eight patients, cancer destruction in four patients, late cervical subluxation in one patient, spondylosis in one patient, and spondylolisthesis in one patient. A variety of stainless steel and titanium spinal implants were used. The images were evaluated for spinal and implant positioning and artifact production. Both stainless steel and titanium implants were imaged safely and there was no evidence of implant migration of local tissue-heating effect. The titanium spinal implants allowed postoperative spine imaging without the significant image distortion characteristic of the stainless steel implants. The stainless steel implants created significant artifact that impaired the usefulness of the magnetic resonance imaging evaluation.

SummarySacral bar fixation is a well-recognized technique for the treatment of posteriorly unstable pelvic injuries, particularly sacral fractures. The sacral bars are placed in the illiac crest posterior to the sacrum. We reviewed 103 pelvic computed tomography (CT) scans and three cadaver pelves t

An 18-year-old woman involved in a motor vehicle accident sustained a vertical shear fracture of the sacrum accompanied by unilateral dislocation of the L5-S1 joint. Evaluation of the patient's injuries was defined by computed axial tomography. Through a posterior midline incision, open reductions of the dislocated L5-S1 joint and of the sacral fracture were performed. Reduction was followed by anterior stabilization of the symphysis pubis. The patient remained neurologically intact after surgery.

Summary Review of MRI, CT, and radiographic views of 21 intraarticular calcaneal fractures revealed eight cases of peroneal tendon subluxation or dislocation. Routine radiographs were nondiagnostic for the soft tissue injury in five of these eight patients. The anatomic relationships between the tendons, retinaculum, and fibular groove could typically be identified easily on MRI or CT scan. In this combined injury, recognition of the peroneal tendon subluxation or dislocation and its proper management may reduce subsequent tendon dysfunction; it may also alter the calcaneal fracture management.

A percutaneous computed tomography (CT) guided pinning of experimentally reproduced slipped capital femoral epiphysis in five cadavers and one patient - who had bilateral pinning for moderate and severe grade chronic slip - was conducted. Prior investigations of cadavers revealed that this procedure can be performed in selected cases. The details of the technique are illustrated in this article.

STUDY DESIGN This anatomic study tested placement of C2 pedicle screws using cadaver specimens. OBJECTIVES To further assess the safety of transpedicular screw placement in the axis by comparing two surgical techniques. SUMMARY OF BACKGROUND DATA Transpedicular screw fixation of traumatic spondylolisthesis of the axis has been described in the literature. Recently, anatomic studies and clinical applications of transpedicular screw fixation for traumatic lesions of middle and lower cervical spine have been described. No previous study assessing the safety of C2 pedicle screw placement is available. METHODS Sixteen embalmed cadaveric specimens were used for this study. In the first eight specimens (Method A), the point of entry for screw placement was chosen to be about 5 mm inferior to the superior border of C2 lamina and 7 mm lateral to the lateral border of the spinal canal. The screw direction was chosen to be about 30 degrees medial to the sagittal plane and 20 degrees cephalad to the transverse plane. A 3.5-mm cortical screw of appropriate length, determined with depth gauge, was placed bilaterally into the C2 pedicle. In the next eight specimens (Method B), the direction of the drill bit was guided directly by the medial and superior aspect of the individual C2 pedicle. Gross dissection was done to view violation of dura, nerve roots, vertebral artery, and penetration of medial, lateral, superior, and inferior cortex of the C2 pedicle. Radiographs and computed tomography scans were obtained to evaluate screw placement in the C2 pedicle. RESULTS In Method A, four screws had lateral violations into the vertebral artery. In Method B, only two cases of minimal penetration of pedicle cortex were found. No medial, superior, or inferior violation of the pedicle cortex was found in the present study. CONCLUSIONS The present anatomic study suggests that transpedicular screw fixation may be performed safely in the C2 pedicle by using the second technique. Using the first technique is not safe.

A proposed extensile medial approach to the medial surface of the shaft of the femur was studied on 30 cadaver thighs. The incision is made along a line extending from the mid inguinal point to a point one-third the distance from the adductor tubercle to the medial side of the patella. After mobilizing the sartorius muscle posteromedially, the medial femur is exposed by a three-step technique. Step I involves bluntly defining the internervous plane distally between the vastus medialis muscle and the adductor magnus tendon until limited proximally by the distal end of the vastoadductor membrane at an average of 9 cm from the adductor tubercle. In step II blunt dissection between the vastus medialis and the adductor longus muscles is carried from proximal to distal until limited by the proximal end of the vastoadductor membrane. Now the well-defined vastoadductor membrane area ("danger zone") measuring 6 cm in length on average is safely dealt with (step III) and the medial femur is exposed. Distal extension can be made to expose the knee joint. The approach can be extended proximally to the lesser trochanter between the vastus medialis and both the adductor brevis and pectineus muscles. Anatomic measurements in relation to the adductor tubercle and cross-sections of the thigh were made to better describe anatomic constants and variables in this rather unfamiliar medial thigh area.

Study design This study directly measured the dimensions of the first sacral vertebra based on dry bony specimens. Objectives To measure the dimensions of the S1 pedicle, vertebral body, and spinal canal, and determine the projections of the S1 pedicle on the posterior aspect of the sacrum. Summary of background data Sacral screw fixation remains a challenging clinical problem because of the unique anatomy of the first sacral vertebra. The anatomic data of S1 have rarely been described in the literature. Methods Sacrums from 50 carefully prepared bony spines were used. Linear measurements included the dimensions of the vertebral body, spinal canal, and pedicle. Pedicle width was measured in two segments, pedicle zones 1 and 2. Angular measurements of the pedicle relative to the sagittal plane were also included. Results In pedicle zone 1, the average medial angle of the pedicles was 10.2 degrees for men and 10.7 degrees for women, average width was 10.9 mm for men and 10.4 mm for women, average length of the pedicles was 34.6 mm for men and 34.9 mm for women. In pedicle zone 2, the average medial angle of the pedicles was 39.4 degrees for both men and women, average width was 15.6 mm for men and 14.7 mm for women, average length of the pedicles was 43.7 mm for men, and 41.7 mm for women. The projections of pedicle zones 1 and 2 on the posterior aspect of S1 were determined. Conclusions The investigators proposed the concept of pedicle zones 1 and 2. The safer area for S1 pedicle screw insertion was found in pedicle zone 2.

Twenty-eight patients with metaphyseal nonunion were evaluated retrospectively. Initially, all patients were thought to have healing of their fractures. Mild pain and/or instability with weightbearing or discomfort localized around the hardware were common symptoms of this nonunion; however, substantial pain was not a predominant feature. In the majority of cases, routine roentgenograms were not helpful in establishing the diagnosis. Overlapping hardware made visualization difficult; furthermore, the presence of a callus gave a false impression of fracture healing. Tomograms were done in 13 patients, but were not helpful in four patients. Stress views and examination under fluoroscopy were reliable means of making this diagnosis, particularly around the knee region. It was done, however, only in a few patients. Subtle changes in the position of hardware or the position of the fragments are also an indication of failure of union. The average time from the initial injury to the diagnosis of nonunion was 36 weeks. Five patients whose pain was attributed to the hardware were found to have a nonunion intraoperatively at time of attempted hardware removal. In one patient, the nonunion was diagnosed during a quadricepsplasty. In two patients, the diagnosis was missed a second time following revision of fixation and bone grafting. Diagnosis of metaphyseal nonunion requires a high index of suspicion, because it occurs among all age groups. It is not as rare as previously described and poses many difficulties. The authors recommend the use of additional studies, including tomograms or stress views, oblique to establish difficult diagrams.

Osteosynthesis with an anterior plate is indicated for stabilization of the cervical spine. It is used for reconstruction of the vertebral body following corpectomy and for cervical instability due to fractures, fracturedislocations, and post-laminectomy. In these situations, a well-keyed anterior graft or posterior fusion alone may be inadequate to attain stability. The authors retrospectively review 25 cases of osteosynthesis Of the cervical spine using the AO H-plate. All the patients were stable enough postoperatively to allow early mobilization with a cervicothoracic orthosis. Average follow up was 31.2 months. All the grafts fused; however, complications occurred in 36% of the cases. The majority of these complications did not affect the long-term clinical result. This method involves potential risks to the spinal cord, esophagus, carotid structures, and laryngeal nerve. It should therefore be used in carefully selected cases.

Nine patients with nonunion of the tibia associated with angular deformity were treated using the Ilizarov device. Eight of these went on to heal the nonunion and had acceptable correction of the angular deformity. One patient with an atrophic nonunion and severe bone loss received a below knee amputation. The authors recommend the use of circular ring fixation as an alternative in the treatment of selected cases of stiff nonunion of the tibia combined with angular deformity, particularly if there is active infection, prior use of an external fixator, or poor soft tissue coverage.

Coronal computed tomography (CT) scan was used in the evaluation of a fractured process of the talus in 10 patients. Because routine radiographs failed to determine either the size or comminution of the fractured process, CT imaging was used to accurately assess the size, displacement, and comminution of the fractured process. CT scans also showed the extent of subtalar joint involvement, any associated tendon pathology, or additional fractures. In two patients the nature of the injury was initially missed, and CT scan diagnosed a nonunion of the lateral process. In all patients, CT scan altered the management of the fracture or helped in selecting the surgical approach. The authors recommend that coronal CT scans be used in the evaluation of a fractured process of the talus.

Seventeen cases of fibular nonunion or delayed union were seen in our institution from 1985 to 1990. All but one of these cases were associated with nonunion of the tibia which was diagnosed radiologically and/or surgically. The fíbula characteristically heals before the tibia; therefore, if the fibula is slow in healing or showing nonunion, more intensive investigation of the tibia for occult nonunion, or delayed union, should be done to determine whether early surgical intervention would be necessary to avoid prolonging the course of treatment. Nonunion of the fibula may indicate instability of the fractured tibia. The authors have examined the relationship of this mutual nonunion and recommend careful observation of the fibular healing in associated fractures of the tibia and fibula.

Thirty patients underwent fixation of the thoracic and lumbar spine from 1986 to 1990 using the Roy-Camille pedicular screw fixation system. The spine was stabilized for a variety of pathologic entities including fracture, tumor, spondylolisthesis, postlaminectomy Instability, and pseudarthrosis. All but one patient obtained solid fusion based on radiographic and clinical criteria with an average foflow up of 19.5 months. All patients reported subjective Improvement in preoperative pain levels. There were no neurologic complications associated with the surgical procedure. Roy-Camille plate fixation appears to offer a stable surgical construct in the treatment of thoracic and lumbar spine instability.

Twenty-two low lumbar burst fractures (L3-L5) were treated, with an average follow up of 56.2 and 39.0 months in the conservative and surgically treated groups, respectively. Twenty patients were available for review; seven were treated conservatively and 13 were stabilized surgically. All patients were evaluated clinically for work status, activity level, residual pain, and subsequent development of neurologic symptoms. Roentgenograms were reviewed for severity of initial fracture, canal compromise, and maintenance of initial correction. In general, neurologically intact patients in both groups returned to similar postinjury employment levels. Persistent back pain was found to be more disabling in the surgically treated group, in which a fusion incorporating four or five lumbar segments was performed. There was no evidence of significant loss of initial reduction, and no patients experienced late neurological compromise in the surgical group. An average follow-up kyphosis of 9.2° and 31% loss of vertebral height were observed in the conservative group, while a follow-up lordosis of 1° and 19% loss of vertebral height were observed in the surgical group. Conservative treatment of low lumbar burst fracture is a viable option in neurologically intact patients, but loss of lordosis and vertebral height may persist. Biomechanical and anatomic characteristics of the low lumbar spine differ from the thoracolumbar region and may account for the inherent stability of these injuries. If surgery is chosen, a long fusion with distraction instrumentation should be avoided in the low lumbar spine. A short rigid fixation with pedicular instrumentation may be of greater benefit.

The danger zone of the acetabulum is defined by Marvin Tile as that part of the posterior wall and column at the mid-acetabulum lying above the ischial spine. Screws inserted in the danger zone are at risk of violating the hip joint. Unfortunately, this zone is frequently used in the fixation of posterior wall and column fractures. Cadaveric studies were performed analyzing 1-cm cross-sections through the acetabulum for the purpose of studying the anatomical configuration of the danger zone. The plane of the cross-section was perpendicular to the posterior column. Each cross-section had the medial boundary of the acetabulum projected onto the posterior column. The cross-sections were then assembled to form the original acetabulum. By analyzing the projections on the posterior column, the exact configuration of the danger zone was determined. Screws placed at the margin of the danger zone and directed perpendicular to the posterior column violated the hip joint. Through analysis of the cross-sections, safe anatomic pathways were developed for screw placement. Cortical screws (4.5 mm), placed at entry points of 2 cm and 3 cm medial to the lateral acetabular margin and angled medially 45 degrees and 15 degrees, respectively, did not violate the hip joint. The angulation was respective to the perpendicular to the posterior column. In this study, the average width of the posterior column at the mid-acetabular level was 4.8 cm. Computed tomography scan of the acetabulum yielded valuable information regarding screw placement in the posterior column.(ABSTRACT TRUNCATED AT 250 WORDS)

A motor vehicle accident victim presented with a fractured acetabulum and had apparent entrapped bony intraarticular fragments seen on computed tomography scanning. At surgery, these fragments were found to be a partially avulsed calcified ligamentum teres that was apparently caused by a previous injury of the same hip. Excision of the calcified ligament and surgical stabilization of the acetabulum were performed. A calcified ligamentum teres may be confused with entrapped bony fragments and therefore cause difficulty in the evaluation and management of acetabular fractures.

This report describes the successful treatment of a Grade IIIC open fracture of the tibia associated with vascular injury utilizing a bone graft paste injected percutaneously

We evaluated the anatomic structures at risk during posterior plating of the cervical spine and outlined a safe technique for screw insertion. Three cadaveric specimens were evaluated anatomically and radiographically. Screws and wires were inserted into the articular masses at different locations and angulations. The relationship of the neurovascular structures to the screws and wires was noted. To avoid injury to the nerve roots, vertebral artery, and spinal cord, the screw should be placed in the center of the articular masses perpendicular to the vertebral plane with 15 degrees lateral angulation.

Between June 8, 1985 and January 29, 1986, the authors performed five CT-guided needle biopsies of suspicious sacral lesions. In each of the five cases, these biopsies allowed the acquisition of specimens suitable for definitive pathologic diagnosis. Three cases of metastatic adenocarcinoma, one case of desmoplastic fibroma, and one case of chronic inflammatory changes were noted. In the case involving chronic inflammatory changes, subsequent open biopsy was performed, confirming the inflammatory changes and absence of neoplasm. The authors conclude that percutaneous CT-guided biopsy of sacral lesion can be performed safely and rapidly, and allows accurate diagnosis and treatment of sacral lesions.

Thirty-five to 45 degrees internal oblique radiographs were used in the assessment of tibial fracture healing. This view is particularly helpful when routine radiographic examinations (anteroposterior and lateral) are nondiagnostic in assessing tibial fracture healing. The technique was helpful in the diagnosis of four occult nonunions as well as in showing the position of a bone graft when used. The authors recommend this view when a decision about tibial fracture healing cannot be made from routine radiographs. They recommend this view before resorting to tomograms of the tibia.

The value of CT scanning for both preoperative and postoperative assessment of pelvic and acetabular fractures has been demonstrated. Previous attempts at our institution to obtain useful pelvic CT scans following internal fixation with stainless steel implants have been impaired by metal artifacts that degraded the transaxial CT images. Our use of titanium, instead of stainless steel implants, produced identical fixation and ultimate fracture healing, but yielded minimal artifacts. We recommend the use of titanium implants as substitutes for stainless steel implants in pelvic fixation to maximize the information obtained on subsequent CT exams.

This study describes the anatomy of the posterior interosseous nerve and proposes how to protect it during the different approaches to the proximal radius. Based on the findings presented here, the choice of the approach and the pitfalls that might cause posterior interosseous nerve injury were defined. Three surgical approaches were used on 30 cadaveric upper limbs : modified Henry's anterior approach, Thompson's posterior approach, and a modified Gordon-Boyd's approach. Important anatomic structures were localized, marked, and shown on radiographs. Plates and screws were applied through the different approaches to determine the relationship of the hardware to the posterior interosseous nerve. Measurements were taken between the humeroradial joint, as a reference point, and different important anatomic structures. It was concluded that the anterior approach to the proximal radius is relatively safe and offers the possibility of proximal and distal extension. Caution should be taken while applying screws, however, to avoid posterior interosseous nerve injury. The radius is superficial posteriorly, and many surgeons favor Thompson's approach for exposure of the proximal radius ; nonetheless, it carries the risk of posterior interosseous nerve injury with exposure of the most proximal portion of the radius. The modified Gordon-Boyd's approach offers the advantage of exposing both the radius and the ulna, but necessitates excessive muscle stripping.

Anatomic and radiographic studies were performed on three cadaveric pelves to define recommendations for better anterior pelvic external fixator pin placement. A thick zone of bone was identified for pin purchase beginning along the iliac crest 2-3 cm posterior to the anterior superior iliac spine (ASIS), and extending 6-8 cm posteriorly along the crest. This zone is hourglass-shaped, and follows the superior gluteal ridge to the superior acetabular region. This zone has a maximal thickness of 4 cm in the supra-acetabular region, and a minimum of 8 mm at the isthmus. Cortical pin penetration is more likely to occur if pin placement begins in the lateral third of the iliac crest, or if the pin is advanced beyond the isthmus of this zone, 5 cm from the crest. Acetabular penetration occurs when the pins are advanced farther than 10.5 cm. Radiographic evaluation demonstrates that only the pelvic outlet view gives the proper orientation of the iliac tables to guide the angle of the pin placement (24 degrees from vertical) and to confirm proper pin placement. Computed tomography (CT) evaluation with "inlet" positioning of the gantry gives complementary information for pin placement.

Magnetic resonance imaging (MRI) of the thoracolumbar spine is valuable in the diagnosis of acute and chronic spine injuries. It allows evaluation of the nerve roots, spinal cord, and the supporting bony and ligamentous structures. Magnetic resonance imaging can be used to detect sequelae of spinal cord injury and any mechanical impingement on the spinal cord or nerve roots. Pedicular screw fixation of the spine is becoming the procedure of choice for stabilization of the lumbar spine, yet it limits the postoperative use of MRI because of marked imaging artifacts arising from the ferromagnetic properties of the used stainless steel implants. The authors have compared extensive artifacts produced by the stainless steel implants with those produced by titanium implants. Titanium implants produced fewer artifacts in the spinal canal. The use of MRI compatible materials in thoracolumbar spine stabilization would permit detailed examinations by serial MR imaging.

Peroneal nerve impalement is a recognized complication of percutaneous placement of wires, which is gaining increased usage with the application of the techniques of Ilizarov, Monticelli, and Spinelli. Dissections of the peroneal nerve in the proximal tibia were performed in ten anatomic specimens (20 legs) to define (1) its relationship to palpable landmarks, (2) distribution of major branches to the musculature, and (3) safe zones of placement of percutaneous wires in the proximal tibia. The anterior recurrent tibial nerve was frequently in an area of risk where it courses proximally in the anterior compartment. A safe zone is located anterior to the palpable portion of the fibular head and up to 2 cm distal to the tip of the fibular head.

A 27-year-old manual laborer presented with dislocation of the right elbow, complete separation of the radial head at the neck level, and avulsion of the coronoid process. Closed reduction of the elbow resulted in ulnohumeral instability. As an alternative to silastic implant, the radial head was reduced, internally fixed, and used as a spacer to restore elbow stability. The radial head fracture healed with no sequelae. At two years follow-up examination, the patient had a stable elbow with nearly full range of motion.

The value of magnetic resonance imaging (MRI) for assessment of the hip has been demonstrated, particularly in cases of avascular necrosis. Magnetic resonance imaging can be used to provide anatomic evaluation of the femoral head, acetabulum, hip joint, joint fluid, and the surrounding structures. MR examinations of two patients with hip fractures fixed with stainless steel hip implants were compared with nine patients with hip fractures fixed with titanium hip implants, one of which showed avascular necrosis of the femoral head. The titanium implants resulted in less MRI artifacts, allowing for improved depiction of the femoral head and surrounding soft tissue. For this reason titanium fixation devices are recommended as a substitute for stainless steel in the hip joint region in a patient who may need future MR examination.

Transverse sacral fractures with sacral canal compression and neurologic deficit are rare sequelae of high falls. Nevertheless, a high index of suspicion is necessary as such an injury may present significant complications and may be missed on standard anteroposterior pelvic roentgenograms and pelvic computed tomography (CT) examinations obtained during the evaluation of multiple traumas. The saddle anesthesia, loss of bladder and sphincter function, and sexual dysfunction may be masked or unrecognized during the acute phase of polytrauma. Special attention must be directed to obtaining a lateral profile view of the sacrum, as this deformity may not be seen in any other view. Sagittal reconstruction images of the sacrum can be obtained during a pelvic CT examination if the initial lateral roentgenograms are technically inadequate because of the patient's obesity or limitations of portable radiographic equipment in the emergency department. The CT scoutview itself may show the acute sacral angulation if sufficient technique factors are employed. The roentgenographic suspicions can be confirmed with lateral multidirectional tomography or even with sagittal magnetic resonance imaging (MRI). Because this transverse sacral fracture is unstable in flexion, additional neurologic injury may result if the spine or hips are unwittingly manipulated in flexion.

A 34-year-old man was injured in a motorcycle accident and suffered both aortic rupture and thoracic spinal fracture, complicated by an underlying undetected ankylosing spondylitis. The latter disease can affect the integrity of vascular and spinal structure. Aortography is recommended as a high priority for the patient in an unstable cardiovascular condition requiring a definitive diagnosis. Aortic rupture and thoracic spine fracture may occur from high energy deceleration trauma. Motor vehicle passenger and pedestrian injuries are most commonly involved, although airline accidents and high falls also generate some cases. Mediastinal widening, displacement of esophagus and trachea, apical dissection of blood, and, especially, paravertebral pleural space widening are common to both injuries. Whereas most mediastinal hematomas are nonaortic in origin, a combined injury must be considered because clinical features may also overlap. These include hypotension (hypovolemic or spinal shock), paraplegia, and severe back pain. In light of the high mortality and time constraints associated with aortic rupture, immediate diagnostic resolution is necessary for appropriate management and priority of investigation.

There is added stability when plate fixation of the fibula supplements the external fixator used in treating tibial fractures associated with a segmental defect. An anatomic specimen model of a Grade III open fracture of the tibia with an associated fibular fracture was used in this study. Fibular internal fixation using an AO standard plate was performed on one of each of five matched pairs of legs. These were then subjected to identical loads in compression and torsion. The numeric values obtained during loading in all modes were converted to ratios between each of the tested pair to directly compare the effect of stabilization of the fibula. The final results showed that in each case, the preparation with fibular plating had improved resistance to deformation in axial loading. On average, the plated specimens were 2.2 times stiffer. In torsion, plating the fibula did not appear to affect the resistance of the construct to the applied load. Supplemental plate fixation of the fibula in fractures of the tibia with segmental defects may improve subsequent morbidity. The increased rigidity of the system may be sufficient to allow partial to full weight bearing immediately after surgery. This may have significant value in the management of the polytraumatized patient.

Dislocation of the radial head in an adult is an uncommon injury. The mechanism of injury is considered to be due to hyperpronation of the forearm. Fracture-dislocations of the forearm are well described and involve both the radius and the ulna. A dislocation of the head of the radius with an ipsilateral fracture of the shaft of the radius seems not to have been reported; the mechanism of injury can only be postulated.

The Bosworth fracture-dislocation is a rare fracture-dislocation of the ankle where the proximal fibular fragment lodges behind the tibia, rendering it irreducible by routine closed manipulations. Clinically the patient's foot is in severe external rotation. This external rotation makes the initial roentgenograms difficult to interpret. Consequently, the diagnosis is often overlooked, resulting in inappropriate treatment and a disastrous outcome. If properly recognized, these injuries can be successfully treated by closed or open techniques with return of near-normal ankle function. The problem is illustrated in a case involving a 40-year-old woman, as related to a review of the literature and discussion of the treatment rationale.

A series of 30 high-energy tibial diaphyseal fractures in 30 patients were treated with posterolateral bone grafting (1984-1987). All of the fractures were open, a majority being Gustillo Type III with significant soft-tissue injury, comminution, or segmental bone loss. The common mechanisms of injury included motorcycle, pedestrian versus automobile, and motor vehicle accidents. Nineteen of 30 fractures were treated with a posterolateral bone graft within six months of the initial injury, and 11 of 30 were grafted after established nonunion. Union was obtained in 29 of 30 fractures (97%). Healing time from the time of grafting ranged from three to 12 months, with an average of 4.7 months. One patient had a below-knee amputation because of uncontrolled chronic osteomyelitis, drainage, and nonunion. Posterolateral bone grafts consistently produced rapid healing of delayed union as well as established nonunion.

The authors performed percutaneous computed-tomography (CT)-guided stabilization of reproduced pelvic fractures in eight cadaver studies and in three additional clinical cases. The details of the technique are illustrated in this article. The authors conclude that percutaneous CT-guided stabilization of pelvic fractures in selected cases can be performed safely, rapidly, and with less associated morbidity than conventional open methods presently used. Clinical studies are currently being expanded.

The use of interventional angiography has been limited in the past to the angiography suite. Significant technical difficulties have been associated with transfer of the unstable patient from the operating room for this procedure. However, current radiographic sophistication now exists to allow rapid intraoperative digital subtraction angiography of uncompromised quality to be performed. An animal model using these techniques is presented.

A patient in the second trimester of pregnancy sustained a gunshot wound of the upper cervical spine with a partial Brown-Séquard syndrome. The patient's condition was evaluated by conventional roentgenography, computed axial tomography (CT), and magnetic resonance imaging (MRI). The MRI alone clearly demonstrated the relationship of the bullet and the spinal cord, whereas the CT image was obliterated by metal artifacts. The bullet was removed from the spinal canal by a posterior approach with the patient in the sitting position and in skeletal cervical traction. The neurological status of the patient improved markedly after the surgery.

Anterior stabilization with combined plate and bone fusion was performed after neural decompression on ten patients for spondylotic cervical myelopathy, and for radiculopathy or trauma in three patients. Medial corpectomy was performed at one to four levels. Iliac crest or fibular bone grafts were secured by plates anchored to the graft and adjacent vertebral bodies. All patients were placed in Minerva braces postoperatively. There was successful fusion in all cases, and no graft dislodgement or kyphosis. Early initiation of rehabilitation was achieved. Morbidity occurred in patients with severe spondylotic cervical myelopathy. This include respiratory depression requiring reintubation in 2/13 procedures, dysphagia (2/13) from loosening of the screws or prominent hardware and graft, and screw loosening (2/13). Neurological improvement was present in 85% (11/13) of patients. There was no deterioration of neurological function in any case. We conclude from this early follow-up that anterior bone fusion with supplemental plates provides effective stabilization for the unstable cervical spine. Greater morbidity risk exists in patients with severe spondylotic cervical myelopathy and spastic quadriparesis who required multilevel medial corpectomies and fusion.

Scapulothoracic (ST) dissociation is a closed complete traumatic forequarter amputation manifested by a flail pulseless arm and well-defined roentgenographic findings. These roentgenographic findings were previously reported to be lateral displacement of the scapula and either acromioclavicular separation (17) or displaced clavicular fracture (20). In this paper we present four patients with ST dissociation who had a previously unreported combination of roentgenographic findings: lateral displacement of the scapula and sternoclavicular separation. Polytrauma was present in all previously reported cases of patients with ST dissociation. We present one patient, however, in whom ST dissociation is an isolated finding. A review of the literature, and a review of treatment options that includes some combination of amputation, shoulder arthrodesis, prosthetic fitting, and reconstructive tendon transfers, are presented.

A 78-year-old white female presented with groin pain of 3 months' duration. Radiographs revealed an osteolytic lesion in the pubic bone, simulating a malignancy or infection. A closed needle biopsy was performed and pathological findings were consistent with posttraumatic osteolysis, showing avascular necrotic tissues. A review of the literature found 16 previous cases presenting with groin pain and a radiographic lesion in the pubic bone that appeared malignant. All of the patients reported in the literature were postmenopausal women most with a recent history of trauma or increased physical activity. All of the lesions were benign and, when treated conservatively, usually resolved within 6 months.

We reviewed 13 cases of unstable cervical spine treated by stabilization with posterior Roy-Camille plates and fusion. The patients were treated between 1985-1988. Six patients had acute traumatic episodes, three patients had posttraumatic instabilities, one patient had laminectomy for cervical spondylotic myelopathy, and three patients had metastatic bone disease. All had successful fusion in approximately 3 months without complications. The indications and techniques of posterior Roy-Camille plating are outlined.