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Biomedical subjects

Ronald A Lehman

Publications and source records attributed to Ronald A Lehman.

At least 19 recordsLinked to original sources
PubMed2006

Repair of the adult acetabular labrum.

Although hip arthroscopy is a new technique, indications for its use are rapidly expanding. With better utilization and understanding of both radiologic assessment of hip pathology and clinical examination, specific intra-articular derangement is being identified. Longitudinal, peripheral, and intrasubstance anterior hip labral tears can be repaired using anterior paratrochanteric and anterior portals with standard hip arthroscopy equipment. Repair of the torn labrum may help re-establish the anatomic function of the labrum, thereby preventing biomechanical compromise through surgical debridement, which may lead to degenerative changes associated with osteoarthritis. Although long-term results are still unknown, results of short-term follow-up are positive.

Acetabulum↗
PubMed2006

Iatrogenic cervical deformity.

Iatrogenic cervical deformity can develop after anterior or posterior procedures. Careful attention to detail can minimize the likelihood of creating a sagittal or coronal plane deformity. Strategies for the prevention and correction of postoperative cervical deformity are presented.

Bone Malalignment↗
PubMed2006

Surgical decision making for unstable thoracolumbar spine injuries: results of a consensus panel review by the Spine Trauma Study Group.

OBJECTIVES: The optimal surgical approach and treatment of unstable thoracolumbar spine injuries are poorly defined owing to a lack of widely accepted level I clinical literature. This lack of evidence-based standards has led to varied practice patterns based on individual surgeon preferences. The purpose of this study was to survey the leaders in the field of spine trauma to define the major characteristics of thoracolumbar injuries that influence their surgical decision making. In the absence of good scientific data, expert consensus opinions may provide surgeons with a practical framework to guide therapy and to conduct future research. METHODS: A panel of 22 leading spinal surgeons from 20 level I trauma centers in seven countries met to discuss the indications for surgical approach selection in unstable thoracolumbar injuries. Injuries were presented to the surgeons in a case scenario survey format. Preferred surgical approaches to the clinical scenarios were tabulated and comments weighed. RESULTS: All members of the panel agreed that three independent characteristics of thoracolumbar injuries carry primary importance in surgical decision making: the injury morphology, the neurologic status of the patient, and the integrity of the posterior ligaments. Six clinical scenarios based on the neurologic status of the patient (intact, incomplete, or complete) and on the status of the posterior ligamentous complex (intact or disrupted) were created, and consensus treatment approaches were described. Additional circumstances capable of altering the treatments were acknowledged. CONCLUSIONS: Decision making for the surgical treatment of thoracolumbar injuries is largely dependent on three patient characteristics: injury morphology, neurologic status, and posterior ligament integrity. A logical and practical decision-making process based on these characteristics may guide treatment even for the most complicated fracture patterns.

Algorithms↗
PubMed2006

Surgical treatment of acute lateral collateral ligament and posterolateral corner injuries.

Early surgical treatment of injuries to the posterolateral corner of the knee is recommended to promote rehabilitation for normal function of the knee. To optimize the chance at primary repair, surgery should be performed within 2 weeks; otherwise, reconstruction is the most viable option. During operative treatment, each component of the posterolateral corner is assessed individually, with primary repair performed if amenable to repair. Additional techniques, such as augmentation, advancement, or reconstruction may be needed if the primary repair is tenuous or the tissues damaged.

Collateral Ligaments↗
PubMed2006

Pectoralis major ruptures.

Although previously considered rare, ruptures of the pectoralis major muscle and tendon have become more common over the past 20 years with increasing participation in competitive sports and weight lifting. These injuries result from maximal eccentric contraction of the muscle with the arm held in an abducted, extended position. Most often, they occur near the tendon insertion. Complete ruptures are more common than partial tears, though many mild strains and partial tears likely go unreported or undiagnosed. Magnetic resonance imaging is the diagnostic study of choice when the diagnosis or extent of the injury is unclear. Partial tears and neglected complete tears with near complete restoration muscle strength after rehabilitation may be treated nonoperatively, with good results. Excellent results can be obtained with early anatomic repair for complete ruptures, though good results have also been reported with delayed repair of complete injuries. Early diagnosis and, when appropriate, anatomic surgical repair are the factors critical to optimizing patient outcomes after pectoralis major rupture.

Athletic Injuries↗
PubMed2005

A new classification of thoracolumbar injuries: the importance of injury morphology, the integrity of the posterior ligamentous complex, and neurologic status.

STUDY DESIGN: A new proposed classification system for thoracolumbar (TL) spine injuries, including injury severity assessment, designed to assist in clinical management. OBJECTIVE: To devise a practical, yet comprehensive, classification system for TL injuries that assists in clinical decision-making in terms of the need for operative versus nonoperative care and surgical treatment approach in unstable injury patterns. SUMMARY OF BACKGROUND DATA: The most appropriate classification of traumatic TL spine injuries remains controversial. Systems currently in use can be cumbersome and difficult to apply. None of the published classification schemata is constructed to aid with decisions in clinical management. METHODS: Clinical spine trauma specialists from a variety of institutions around the world were canvassed with respect to information they deemed pivotal in the communication of TL spine trauma and the clinical decision-making process. Traditional injury patterns were reviewed and reconsidered in light of these essential characteristics. An initial validation process to determine the reliability and validity of an earlier version of this system was also undertaken. RESULTS: A new classification system called the Thoracolumbar Injury Classification and Severity Score (TLICS) was devised based on three injury characteristics: 1) morphology of injury determined by radiographic appearance, 2) integrity of the posterior ligamentous complex, and 3) neurologic status of the patient. A composite injury severity score was calculated from these characteristics stratifying patients into surgical and nonsurgical treatment groups. Finally, a methodology was developed to determine the optimum operative approach for surgical injury patterns. CONCLUSIONS: Although there will always be limitations to any cataloging system, the TLICS reflects accepted features cited in the literature important in predicting spinal stability, future deformity, and progressive neurologic compromise. This classification system is intended to be easy to apply and to facilitate clinical decision-making as a practical alternative to cumbersome classification systems already in use. The TLICS may improve communication between spine trauma physicians and the education of residents and fellows. Further studies are underway to determine the reliability and validity of this tool.

Humans↗
PubMed2005

Reliability of end, neutral, and stable vertebrae identification in adolescent idiopathic scoliosis.

STUDY DESIGN: Analysis of radiographic interpretation and vertebral level identification. OBJECTIVES: To assess the intra- and interobserver reliability by observer training level used for selecting the end vertebra (EV), neutral vertebra (NV), and stable vertebra (SV) in adolescent idiopathic scoliosis patients. SUMMARY OF BACKGROUND DATA: Various radiographic and clinical factors are important in surgical planning. For adolescent idiopathic scoliosis, an analysis of the end, neutral, and stable vertebrae are of paramount importance for understanding spinal deformity management and determining the distal fusion level. Additionally, the development and comparison of optimal surgical techniques requires reliable, reproducible radiographic parameters. METHODS: One hundred consecutive radiographs of operative cases of adolescent idiopathic scoliosis were evaluated on three separate occasions by three surgeons (2700 data points) at various levels of training (fellowship-trained spine surgeon, fellow in-training, orthopedic surgery resident). For each iteration, the observers attempted to identify the distal structural Cobb curve EV, NV, and SV. The radiographs included preselected Lenke type 1, 3, and 5 curves in random order. The average main thoracic curve was 53 degrees (range, 30-82 degrees) with a T8-T9 average apex, whereas the average thoracolumbar curve was 33 degrees (range, 18-65 degrees). Intra- and interobserver reliability was assessed by means of Cohen's Kappa correlation coefficient, and raw percentages of agreement were recorded. RESULTS: Intraobserver reliability was good to excellent for determining the EV (kappaa = 0.69-0.88), good for determining the NV (kappaa = 0.65-0.73), and good to excellent for determining the SV (kappaa = 0.74-0.91) with 83.5, 72.2, and 85.6% intraobserver agreement, respectively. A trend was noted towards greater intraobserver reliability with increasing levels of observer experience. Interobserver reliability was poor (kappaa = 0.26-0.39) for each vertebral level, with interobserver agreement for only 48.7% of EV, 41.7% of NV, and 51.0% of SV. However, interobserver agreement increased significantly when concurrence within one vertebral level was assessed, with 91, 73, and 76% agreement for identifying the EV, NV, and SV, respectively. CONCLUSIONS: Radiographic determination of the EV, NV, and SV demonstrated good to excellent intraobserver, but poor interobserver, reliability. Interobserver agreement was fair to good when concurrence within one adjacent level was assessed. Observer experience level may be a factor. The difficulties in identifying these vertebral levels represent a potential obstacle to reproducible patient-specific fusion level determination and to the optimization and uniformity of patient care.

Adolescent↗
PubMed2005

Accuracy and efficacy of thoracic pedicle screws in curves more than 90 degrees.

STUDY DESIGN: Retrospective study of large-magnitude thoracic curves (> or =90 degrees ) treated with pedicle screw constructs. OBJECTIVE: To evaluate the results of pedicle screw constructs for thoracic curves > or = 90 degrees in terms of sagittal and coronal correction/efficacy, as well as accuracy and safety of thoracic pedicle screw placement. SUMMARY OF BACKGROUND DATA: Thoracic pedicle screw constructs continue to become increasingly more common; however, the debate continues about the safety and efficacy of these constructs because of their perceived increased risk of neurologic injury and the increased cost of spinal instrumentation. METHODS: Since 1998, all patients with adolescent idiopathic scoliosis, or adult progression of adolescent idiopathic scoliosis, a thoracic curve > or = 90 degrees and a minimum 2-year follow-up who were treated with pedicle screw constructs were included in this study. Standing anteroposterior (or posteroanterior), lateral and bending preoperative radiographs, and anteroposterior (or posteroanterior) and lateral postoperative radiographs were evaluated for curve magnitude, flexibility, and postoperative correction to assess the efficacy of these constructs in the immediate postoperative period and at latest follow-up. Postoperative CT scans were evaluated for screw accuracy using established 2-mm increments (intrapedicular, 0-2 mm breach, 2-4 mm breach, > 4 mm breach). Preoperative plans were also reviewed to evaluate the ability to place a pedicle screw at each planned level in these large-magnitude curves. RESULTS: Twenty patients with thoracic curves > or = 90 degrees and an average follow-up of 3.3 years (range, 2.0-5.2 years) were included in the study. All patients underwent a posterior spinal fusion with a pedicle screw only construct. The average preoperative main thoracic curve measured 100.2 degrees (range, 90 degrees -133 degrees ), with an average side-bender of 71.6 degrees (29% flexibility). The average postoperative main thoracic curve was 32.3 degrees (68% correction). A total of 352 thoracic screws were placed in the 20 cases (17.6 screws/case). Screw accuracy (either intrapedicular or <2 mm breach) was 96.3% (339 of 352 screws) by postoperative CT scanning. Ten screws were considered to have a breach between 2 and 4 mm (3 medial, 7 lateral), while three screws were > 4 mm (2 medial, 1 lateral). The two medial screws were the only placed screws that were removed (0.57%). Overall, 94% of planned screws (352 of 374 screws) were placed according to the preoperative plan. There were no incidences of screw or instrumentation failure. Of note, there was a temporary decrease in motor-evoked potentials during curve correction in 2 cases; however, there were no identifiable neurologic complications. CONCLUSIONS: Thoracic pedicle screw constructs can be safely used for large-magnitude curves. Curve correction (68%) is powerful for these curves, which are stiff and difficult to manage. Correction should be performed carefully with consideration given to convex compression for cases with concomitant hyperkyphosis for these "at risk" spinal cords. Screw accuracy (96.3%) was excellent in this review. The authors found that screws can consistently be placed according to the preoperative plan even in these large-magnitude curves.

Adolescent↗
PubMed2005

Standard and minimally invasive approaches to the spine.

With the advent of minimally invasive surgical approaches to the spine, the ability to adequately expose the desired anatomic structures while minimizing the disadvantages of excessive soft tissue stripping, dissection, and prolonged retraction has become increasingly popular. A minimally invasive one- or two-level posterior exposure of the spine is now safely attainable with the latest minimal-access systems that exploit the biomechanics of an adjustable blade retractor. As the clinical use of these developing systems escalates, more outcomes data will become available to determine the safety and value of these minimally invasive procedures.

Cervical Vertebrae↗
PubMed2005

Initial evaluation of the acute and chronic multiple ligament injured knee.

Despite the recent focus on the limited use of urgent arteriograms in the evaluation of acute knee dislocations, physical examination remains the cornerstone of assessment. Several clinical scenarios dictate an orthopedic emergency: vascular disruption, open wound, compartment syndrome, or an irreducible joint/dimple sign. In the acute setting, every attempt should be made to rule out associated injuries and the need for intervention. The multiple ligament knee injury or knee dislocation is a complex dilemma that requires close attention. Concomitant injuries about the knee often arise and must be addressed prior to ligamentous repair, and therefore the orthopedic surgeon must maintain a high index of suspicion for associated injuries in the evaluation of a multiple ligament knee injury.

Diagnosis, Differential↗
PubMed2005

Structures at risk following anterior instrumented spinal fusion for thoracic adolescent idiopathic scoliosis.

OBJECTIVES: With the increasing popularity of anterior instrumented spinal fusion for adolescent idiopathic scoliosis, there has also been a rising concern over the proximity of the descending aorta to the screw tips and the possibility of vessel wall erosion over time. This computed tomography (CT) study attempts to define the relative position of the thoracic aorta and other vital structures to the spine (preoperatively) and to the projected instrumentation (postoperatively) by level and curve magnitude in deformity patients. METHODS: Twenty consecutive patients (17 female, 3 male) with an average age of 14.5 years (range 12.4-18.5 years) and a right main thoracic/Lenke 1 curve (average 55.2 degrees , range 50-66 degrees ) underwent preoperative and postoperative CT scanning as part of their planned open anterior spinal fusion with instrumentation. All images were analyzed for proximity (distance from the midvertebral body) and position to (as defined relative to the center of the vertebral body in the axial plane) the spine preoperatively and the projecting screw tip postoperatively. As a control, 10 age-matched nondeformity thoracic CT scans were analyzed to assess the relative position of the thoracic aorta to the vertebral bodies by level. Preoperative and postoperative plain radiographs were also analyzed for curve magnitude, correction, and fusion levels to assess the possible effect of these variables on the various thoracic structures. RESULTS: The postoperative curve magnitude averaged 26.9 degrees (range 17-40 degrees ; 51% correction) using 151 screws (7.5 screws/patient) and an average follow-up of 4.1 years (range 3.2-7.0 years). Screw-to-spinal-canal distance averaged 5.3 mm (range 3.5-8.2 mm) at an average of +4.5 degrees (range -11 degrees to +15 degrees ) from the coronal axis. Screw tip extrusion (distance beyond the far cortex) averaged 2.8 mm (0-5 mm). The trachea, azygous vein, esophagus, and lungs/pleura were not found to be at risk from screw penetration. The postoperative screw-tip-to-descending-aorta distance varied by vertebra level, with the periapical and distal screws being positioned closer to the aorta (1.6-2.4 mm) (P < 0.05). Additionally, 23 of 151(15%) screws were thought to be adjacent (</=2 mm) to the aorta. This includes 4 of 60 (7%) of the proximal screws but 6 of 40 (15%) of the periapical screws and 13 of 51 (26%) of the distal screws (P < 0.05). There were no screws compressing the aorta and no perioperative or postoperative complications. CONCLUSIONS: The course of the thoracic aorta may vary in individuals; however, in deformity patients, it generally moves from a relatively anterolateral position proximally to a posteromedial position at the apex. Distally, it moves more anteriorly. Consequently, the aorta moves closer to the screw tips both at the apex and distally, whereas the distal screws are more frequently juxtaposed to the descending aorta (P < 0.05).

Adolescent↗
PubMed2005

Solitary epiphyseal enchondromas.

BACKGROUND: Enchondromas originating in the epiphyses of long bones are rare. The purpose of the present study was to evaluate the prevalence as well as the radiographic and clinical characteristics of epiphyseal enchondromas among patients who had been referred to the Armed Forces Institute of Pathology and Walter Reed Army Medical Center. METHODS: We performed a retrospective review of 761 patients who had been referred to our two institutions over an approximately fifty-five-year period and who received a final diagnosis of enchondroma. All lesions had been biopsied, and the pathological diagnosis had been confirmed. Lesions of the hands, feet, or axial skeleton (253 patients) as well as lesions that appeared to originate in the metaphysis or diaphysis (475 patients) were excluded. Only enchondromas of the long bones that originated in the epiphysis were analyzed. The study group included thirty-three patients (twenty male patients and thirteen female patients) with a mean age of 26.7 years, including eleven patients with open physes. We performed additional descriptive analyses with regard to patient age, gender, lesion location, clinical presentation, and treatment as well as an extensive radiographic analysis. RESULTS: The most common locations were the proximal part of the humerus (ten lesions; 30%) and the distal part of the femur (six lesions; 18%). The most common presenting symptom was pain (twenty-three patients). Radiographic analysis demonstrated extensive matrix mineralization in association with twenty-three lesions. Twenty-eight of the thirty-three lesions were geographically well defined; of these, twenty-one had sclerotic borders, and seven did not. Although all lesions were centered and were predominantly located within the epiphysis, twenty of the thirty-three lesions demonstrated radiographic evidence of metaphyseal extension, including four of the eleven lesions in patients with open physes. Twenty-four lesions extended into the subchondral bone. The mean size of the thirty-three enchondromas in greatest radiographic dimension was 2.7 cm (range, 1.1 to 4.9 cm). Twenty-six of the thirty-three lesions were amenable to surgical treatment with curettage with or without bone-grafting, with only one recurrence. With the limited follow-up available, no lesion underwent sarcomatous degeneration. CONCLUSIONS: Epiphyseal enchondromas are rare lesions. Although their biologic behavior appears to mirror that of conventional metaphyseal enchondromas, their proximity to the joint space may lead to more frequent painful symptoms, a propensity for physeal involvement, and the need for earlier definitive surgical intervention.

Adolescent↗
PubMed2005

The thoracolumbar injury severity score: a proposed treatment algorithm.

OBJECTIVE: Significant controversy exists regarding the optimal management of thoracolumbar injuries. This is in part due to the lack of understanding of the natural history of various injury subtypes and the absence of a universally accepted classification scheme that facilitates communication among care providers and assists in directing treatment. The Spine Trauma Study Group has developed an injury severity score based on three major variables: the mechanism of injury determined by radiographic appearance, the integrity of the posterior ligamentous complex, and the neurologic status of the patient. By systematically assigning specific point values within each category based on the severity of injury, a final severity score may be generated that can be used to help direct treatment. The goal of this work is to present a proposal of a detailed treatment algorithm to assist in the nonoperative or operative management of thoracolumbar injuries. METHODS: A detailed review of the world's spinal literature was performed to ascertain predictors of instability following thoracolumbar trauma. With use of known biomechanical and clinical outcome measures, an arbitrary assignment of point values to various injury descriptors was performed. The assessment of the validity of the severity score was compared retrospectively with a variety of selected cases representing the typical injury patterns under the three major injury groups: compression, translational/rotational, and distraction injuries. CONCLUSIONS: The proposed treatment algorithm is an attempt to assist physicians using best-evidence medicine in managing thoracolumbar spinal injuries. The final point flow chart with graduated treatment recommendations is only preliminary and needs to be validated through prospective cohort analysis. In addition, the importance of the chosen variables determining spinal stability must also be verified.

Algorithms↗
PubMed2004

Probing for thoracic pedicle screw tract violation(s): is it valid?

BACKGROUND: Preparation of the thoracic pedicle screw tract is a critical step prior to the placement of screws. The ability to detect pedicle wall violation(s) by probing prior to insertion of thoracic pedicles screws, however, has not been studied. The purpose of this study was to evaluate the inter- and intraobserver agreement and the accuracy in detecting thoracic pedicle screw tract violation(s) among surgeons at various levels of training. METHODS: With use of a straightforward trajectory, under direct visualization, 108 thoracic pedicle screw tracts (54 cadaveric thoracic vertebrae) were prepared in a standard fashion, followed by tapping with a 4.5-mm cannulated tap. A deliberate pedicle violation was randomly created by an independent investigator in either the anterior, the medial, or the lateral wall in 65 pedicles. Following this, four blinded, independent surgeons at various levels of training probed the specimens on three separate occasions to determine if a breach was present (1,296 discrete data points). Surgeon findings were then recorded as breach present or absent and, if present, breach location. The Cohen kappa correlation coefficient (kappa a) and 95% confidence interval were used to assess the accuracy of the observers and the inter- and intraobserver agreement. RESULTS: The mean accuracy over three iterations, the validity in detecting the breach location, and the intraobserver agreement varied by level of training and experience, with the most experienced observer (observer 1) scoring the best and the least experienced observer (observer 4) scoring the worst. The three most senior surgeons had good intraobserver agreement. Interobserver agreement was low between the four observers. CONCLUSIONS: An observer's ability to accurately detect the presence or absence of a pedicle tract violation and the breach location, if present, is dependent on the surgeon's level of training. Probing the pedicle tract prior to placement of pedicle screws in the thoracic spine is likely a learned skill that improves with repetition and experience.

Bone Screws↗
PubMed2003

Use of the anatomic trajectory for thoracic pedicle screw salvage after failure/violation using the straight-forward technique: a biomechanical analysis.

STUDY DESIGN: A biomechanical study of cadaver vertebrae to determine the feasibility of obtaining adequate thoracic pedicle screw fixation in a salvage situation. OBJECTIVE To investigate the ability to safely place a thoracic pedicle screw with adequate maximal insertional torque (MIT) using the anatomic trajectory (AT) (directed along the true anatomic axis of the pedicle) after purposeful failure/medial violation of the pedicle using the straight-forward trajectory (ST) (paralleling the vertebral endplate). SUMMARY AND BACKGROUND DATA: Failure to place a pedicle screw at an intended segment of the thoracic spine may theoretically render the level uninstrumented, because pedicle hook placement may be unsafe and the transverse process may be fractured. An alternative pedicle screw insertion technique, if biomechanically sound in this situation, may present an excellent alternative for critical instrumentation levels. MATERIALS AND METHODS: Fixed-head 5.0 mm stainless steel pedicle screws were placed using the ST and MIT was recorded after determination of bone mineral density (BMD) with dual-energy radiograph absorptiometry (DEXA) scanning. Purposeful screw malposition and critical pedicle wall failure were performed, followed by salvage placement of the screw using the AT. Insertional torque was recorded for each screw revolution with a digital torque wrench and MIT was again recorded to compare the MIT obtainable in the salvage situation. RESULTS: BMD for the vertebrae averaged 732 g/cm2 (620-884 g/cm2). The MIT for the straight-forward technique without pedicle violation was 2.61 +/- 0.19 (SE) inches per pound, whereas that of the salvage procedure after medial wall violation (AT) averaged 1.62 +/- 0.12 (SE) inches per pound. Therefore, the AT achieved 62% (P = 0.027) of the fixation strength (in terms of MIT) during salvage after failure/medial violation of the pedicle. MIT for both the ST* and AT trajectories correlated with both global BMD of the vertebrae (*P = 0.008; P = 0.004) and regional BMD of the vertebral body (*P = 0.044; P = 0.023). CONCLUSIONS: The AT achieved 62% (P = 0.027) of the MIT during salvage of a failed/violated pedicle. BMD correlated with both the initial and salvage techniques. The AT provides adequate fixation in a salvage situation and may be safely used to provide segmental fixation at critical levels.

Absorptiometry, Photon↗