Matthew J. DiPaola

Reliability of a novel classification system for thoracolumbar injuries: the Thoracolumbar Injury Severity Score.

Study Design. Prospective study of 5 spine surgeons rating 71 clinical cases of thoracolumbar spinal injuries using the Thoracolumbar Injury Severity Score (TLISS) and then re-rating the cases in a different order 1 month later. Objective. To determine the reliability of the TLISS system. Summary of Background Data. The TLISS is a recently introduced classification system for thoracolumbar spinal column injures designed to simplify injury classification and facilitate treatment decision making. Before being widely adopted, the reliability of the TLISS must be studied. Methods. A total of 71 cases of thoracolumbar spinal trauma were distributed on CD-ROM to 5 attending spine surgeons, including clinical/radiographic data, details of the TLISS, and a scoring sheet in which cases would be scored using the system. The surgeons were later assigned the task with the cases reordered. Intraobserver and interobserver reliability was calculated for TLISS components, total score, and surgeons treatment decision using the Cohen unweighted kappa coefficients and Spearman rank-order correlation. Results. Interrater reliability assessed by generalized kappa coefficients was 0.33 ± 0.03 for injury mechanism, 0.91 ± 0.02 for neurologic status, 0.35 ± 0.03 for posterior ligamentous complex status, 0.29 ± 0.02 for TLISS total, and 0.52 ± 0.03 for treatment recommendation. Respective results using the Spearman correlation were 0.35 ± 0.04, 0.94 ± 0.01, 0.48 ± 0.04, 0.65 ± 0.03, and 0.51 ± 0.04. Surgeons agreed with the TLISS recommendation 96.4% of the time. Intrarater kappa coefficients were 0.57 ± 0.04 for injury mechanism, 0.93 ± 0.02 for neurologic status, 0.48 ± 0.04 for posterior ligamentous complex status, 0.46 ± 0.03 for TLISS total, and 0.62 ± 0.04 for treatment recommendation. Respective results using the Spearman correlation were 0.70 ± 0.04, 0.95 ± 0.02, 0.59 ± 0.05, 0.77 ± 0.04, and 0.59 ± 0.05. Conclusions. The TLISS has good reliability and compares favorably to other contemporary thoracolumbar fracture classification systems.

Cervical spine motion in manual versus Jackson table turning methods in a cadaveric global instability model.

Study Design A study of spine biomechanics in a cadaver model. Objective To quantify motion in multiple axes created by transfer methods from stretcher to operating table in the prone position in a cervical global instability model. Summary of the Background Data Patients with an unstable cervical spine remain at high risk for further secondary injury until their spine is adequately surgically stabilized. Previous studies have revealed that collars have significant, but limited benefit in preventing cervical motion when manually transferring patients. The literature proposes multiple methods of patient transfer, although no one method has been universally adopted. To date, no study has effectively evaluated the relationship between spine motion and various patient transfer methods to an operating room table for prone positioning. Methods A global instability was surgically created at C5-6 in 4 fresh cadavers with no history of spine pathology. All cadavers were tested both with and without a rigid cervical collar in the intact and unstable state. Three headrest permutations were evaluated Mayfield (SM USA Inc), Prone View (Dupaco, Oceanside, CA), and Foam Pillow (OSI, Union City, CA). A trained group of medical staff performed each of 2 transfer methods: the “manual” and the “Jackson table” transfer. The manual technique entailed performing a standard rotation of the supine patient on a stretcher to the prone position on the operating room table with in-line manual cervical stabilization. The “Jackson” technique involved sliding the supine patient to the Jackson table (OSI, Union City, CA) with manual in-line cervical stabilization, securing them to the table, then initiating the tables lock and turn mechanism and rotating them into a prone position. An electromagnetic tracking device captured angular motion between the C5 and C6 vertebral segments. Repeated measures statistical analysis was performed to evaluate the following conditions: collar use (2 levels), headrest (3 levels), and turning technique (2 levels). Results For all measures, there was significantly more cervical spine motion during manual prone positioning compared with using the Jackson table. The use of a collar provided a slight reduction in motion in all the planes of movement; however, this was only significantly different from the no collar condition in axial rotation. Differences in gross motion between the headrest type were observed in lateral bending (Foam Pillow<Prone View, P=0.045), medial lateral translation (Foam Pillow<Mayfield, P=0.032), and anterior posterior translation (Prone View<Mayfield, P=0.030). Conclusions The data suggest that the manual transfer technique produces 2 to 3 times more cervical spine angular motion than the Jackson table method of transfer. The use of a collar provides significant benefit in limiting spine motion that is only observed in axial rotation. Choice of headrest does have a significant effect on the amount of motion allowed during turning, with the Foam Pillow and Prone View generally providing more effective stabilization compared with the Mayfield.

Transferring patients with thoracolumbar spinal instability: are there alternatives to the log roll maneuver?

Study Design. Using a cadaveric model, the amount of spinal motion generated during the execution of various prehospital transfer techniques was evaluated using a crossover study design. Objective. To assess the quantity of segmental motion generated across a globally unstable thoracolumbar spine during the execution of the log roll (LR), lift-and-slide, and 6-plus-person (6+) lift. Summary of Background Data. The LR has been reported to be inappropriate for transferring patients with thoracolumbar injuries. Although potentially safer methods have been identified for use with cervical spine injuries, alternatives to the LR have not been recognized in the case of thoracolumbar injuries. Methods. Three-dimensional angular motion was recorded across the T12–L2 vertebrae during execution of 3 transfer techniques using cadavers with intact spines and then repeated following an L1 corpectomy. Using a three-dimensional electromagnetic tracking device, the maximum angular motion was measured 3 times for each technique, and the mean value from the 3 trials was included in the statistical analysis. Results. Statistical tests revealed that there was a significant difference in axial rotation between the LR and lift-and-slide (P = 0.008) but only when these were executed in the presence of a destabilized T12–L1 segment. In addition, analysis of lateral flexion data identified a main effect for technique with the LR generating greater motion than either lifting technique. Finally, no significant difference was noted for flexion-extension among techniques. Conclusion. The execution of the LR maneuver tends to generate more motion than either of the lifting methods examined in this investigation. More research is needed to identify the safest possible method for transferring or moving patients with thoracolumbar instability.

The impact of scapular notching on reverse shoulder glenoid fixation

BACKGROUND Scapular notching is a well-documented complication of reverse shoulder arthroplasty. The effect of scapular notching on glenoid fixation is unknown. MATERIALS AND METHODS This study dynamically evaluated reverse shoulder glenoid baseplate fixation and assessed the effect of scapular notching on fixation in composite scapulae. A cyclic test was conducted to simulate 55° of humeral abduction in the scapular plane as a 750-N axial load was continuously applied to induce a variable shear and compressive load. Before and after cyclic loading, a displacement test was conducted to measure glenoid baseplate displacement in the directions of the applied static shear and compressive loads. RESULTS For the scapulae without a scapular notch, glenoid baseplate displacement did not exceed the generally accepted 150-μm threshold for osseous integration before or after cyclic loading in any component tested. For the scapulae with a scapular notch, glenoid baseplate displacement exceeded 150 μm in 2 of the 7 samples before cyclic loading and in 3 of the 7 samples after cyclic loading. The average pre-cyclic glenoid baseplate displacement in the direction of the shear load was significantly greater in scapulae with a scapular notch than those without a scapular notch both before (P = .003) and after (P = .023) cyclic loading. CONCLUSIONS Adequate glenoid baseplate fixation was achievable in most cases in scapulae with a severe scapular notch; however, the fact that this micromotion threshold was not met in all scapulae with a notch is concerning and implies that severe notching may play a role in initial glenoid baseplate stability.

Comparison of Thoracolumbar Motion Produced by Manual and Jackson-table-turning Methods: Study of a Cadaveric Instability Model

BACKGROUND Patients who have sustained a spinal cord injury remain at risk for further neurologic deterioration until the spine is adequately stabilized. To our knowledge, no study has previously addressed the effects of different bed-to-operating room table transfer techniques on thoracolumbar spinal motion in an instability model. We hypothesized that the conventional logroll technique used to transfer patients from a supine position to a prone position on the operating room table has the potential to confer significantly more motion to the unstable thoracolumbar spine than the Jackson technique. METHODS Three-column instability was surgically created at the L1 level in seven cadavers. Two protocols were tested. The manual technique entailed performing a standard logroll of a supine cadaver to a prone position on an operating room Jackson table. The Jackson technique involved sliding the supine cadaver to the Jackson table, securing it to the table, and then rotating it into a prone position. An electromagnetic tracking device measured motion--i.e., angular motion (flexion-extension, lateral bending, and axial rotation) and linear translation (axial, medial-lateral, and anterior-posterior) between T12 and L2. RESULTS The logroll technique created significantly more motion than the Jackson technique as measured with all six parameters. Manual logroll transfers produced an average of 13.8 degrees to 18.1 degrees of maximum angular displacement and 16.6 to 28.3 mm of maximum linear translation. The Jackson technique resulted in an average of 3.1 degrees to 5.8 degrees of maximum angular displacement (p < 0.001) and 4.0 to 10.0 mm of maximum linear translation (p < 0.05). CONCLUSIONS Compared with the logroll, the Jackson-table transfer method provides superior immobilization of an unstable thoracolumbar spine during transfer of supine cadavers to a prone position on the operating room table. CLINICAL RELEVANCE This study addresses in-hospital patient safety. Performing the Jackson turn requires approximately half as many people as required for a manual logroll. This study suggests that the Jackson technique should be considered for supine-to-prone transfer of patients with known or suspected instability of the thoracolumbar spine.

Comparing Cervical Spine Motion With Different Halo Devices in a Cadaveric Cervical Instability Model

Study Design. Biomechanical evaluation of conventional and noninvasive halos in cadaveric C1–C2 and C5–C6 instability models. Objective. To compare the ability of a conventional halo and noninvasive halo (NIH) to immobilize the unstable cervical spine at the C1–C2 and C5–C6 levels. Summary of Background Data. Many successful outcomes have been reported in cervical spine injury treatment with the conventional halo (CH); however, complications related to pin sites have been reported. The NIH was designed to overcome these complications. To date, no investigation has compared the biomechanical efficacy of the NIH with that of the CH in restricting three-dimensional cervical spine motion. Methods. A global instability was created at the C1–C2 level in 4 cadavers and at C5–C6 in 4 others. Relative motion was measured between the superior and inferior vertebrae during the donning process, execution of the log roll technique, and during the process of sitting up. This testing sequence was followed for all treatment conditions. Results. During the application of the orthoses there was a significant increase in motion at C1–C2 instability and a trend toward increased motion at the C5–C6 instability with CH compared with NIH. In the log roll maneuver, the CH and NIH restrict motion to a similar degree at the C1–C2 instability level, except in frontal plane translation, where CH immobilizes the segment to a greater extent. For the C5–C6 instability the CH provides significantly better immobilization for lateral bending and axial translation. No significant differences were found between the NIH and CH for the sit-up maneuver at either of the levels. Conclusion. Donning of the NIH generates significantly less cervical spine motion than application of the CH. The CH provides superior immobilization for a C5–C6 instability during the log roll maneuver and a C1–C2 instability in the frontal plane during the log-roll maneuver. The CH and NIH immobilize the C1–C2 and C5–C6 instability to a similar degree during the sit-up maneuver.

Comparison of the Flat Torso Versus the Elevated Torso Shoulder Pad Removal Techniques in a Cadaveric Cervical Spine Instability Model

Study Design. Controlled laboratory study in a cadaveric model. Objective. To determine if removing shoulder pads using the elevated torso technique generated less spinal segment motion than using the flat torso method. Summary of Background Data. Guidelines for care of the injured football player with a suspected spinal injury recommend initial immobilization with shoulder pads and helmet in place. There is a need to develop a safe protocol, for shoulder pad removal that maintains optimum cervical stability. Methods. Five lightly embalmed cadavers were studied before and after a globally unstable segment was created at C5–C6. A trained group of medical staff conducted repeated measures trials for 2 pad removal protocols. The elevated torso technique, outlined by the NATA Inter-Association Task Force, is the same as the flat torso except an additional assistant is employed to lift the patient’s shoulders 30° to 40° off the ground while the head holder maintains spinal alignment as the pads are removed. An electromagnetic tracking device captured angular and linear motions in 3 planes between the C5–C6 segments. Results. The elevated torso technique generated significantly less C5–C6 motion in flexion/extension (P = 0.015) and lateral bending (P = 0.001), with a trend toward decreased cervical motion in axial rotation (P = 0.052). When moving the spine-injured cadavers, linear translation was also slightly, but not significantly less when the elevated torso technique was used. In the intact spine, significantly less motion was seen in 5 of 6 measures when the elevated torso technique was used. However, the differences were not large enough to be clinically significant in an intact spine. Conclusion. These findings support use of the elevated torso method to minimize cervical spine motion during shoulder pad removal when neither thoracic nor lumbar spinal injury is a concern.

Minimal Incision Technique Using a Two-Hole Plate for Fixation of Stable Intertrochanteric Hip Fractures

This article presents a minimally invasive adaptation of the sliding hip screw technique. This two-hole side plate construct for the repair of intertrochanteric hip fractures minimizes blood loss and soft-tissue dissection.

Cervical spine motion generated with manual versus jackson table turning methods in a cadaveric c1-c2 global instability model.

Study Design. Cadaveric biomechanical study. Objective. To quantify spinal motion created by transfer methods from supine to prone position in a cadaveric C1–C2 global instability model. Summary of Background Data. Patients who have sustained a spinal cord injury remain at high risk for further secondary injury until their spine is adequately stabilized. To date, no study has evaluated the effect of patient transfer methods from supine to prone position in the operating room, on atlantoaxial cervical spine motion. Methods. A global instability was surgically created at the C1–C2 level in 4 fresh cadavers. Two transfer protocols were tested on each cadaver. The log-roll technique entailed performing a standard 180° log-roll rotation of the supine patient from a stretcher to the prone position onto the operating room Jackson table (OSI, Union City, CA). The “Jackson technique” involved sliding the supine patient to the Jackson table, securing them to the table, and then rotating them into a prone position. An electromagnetic tracking device registered motion between the C1 and C2 vertebral segments. Three different head holding devices (Mayfield, Prone view, and blue foam pillow) were also compared for their ability to restrict C1–C2 motion. Six motion parameters were tracked. Repeated measures statistical analysis was performed to evaluate angular and translational motion. Results. For 6 of 6 measures of angulation and translation, manual log-roll prone positioning generated significantly more C1–C2 motion than the Jackson table turning technique. Out of 6 motion parameters, 5 were statistically significant (P < 0.001–0.005). There was minimal difference in C1–C2 motion generated when comparing all 3 head holding devices. Conclusion. The data demonstrate that manual log-roll technique generated significantly more C1–C2 motion compared to the Jackson table technique. Choice of headrest has a minimal effect on the amount of motion generated during patient transfer, except that the Mayfield device demonstrates a slight trend toward increased C1–C2 motion.

Initial glenoid fixation using two different reverse shoulder designs with an equivalent center of rotation in a low-density and high-density bone substitute.

BACKGROUND Numerous glenoid implant designs have been introduced into the global marketplace in recent years; however, little comparative biomechanical data exist to substantiate one design consideration over another. MATERIALS AND METHODS This study dynamically evaluated reverse shoulder glenoid baseplate fixation and compared the initial fixation associated with 2 reverse shoulder designs having an equivalent center of rotation in low-density and high-density bone substitute substrates. RESULTS Significant differences in fixation were observed between implant designs, where the circular-porous reverse shoulder was associated with approximately twice the micromotion per equivalent test than the oblong-grit-blasted design. Additionally, 6 of the 7 circular-porous reverse shoulders failed catastrophically in the low-density bone model at an average of 2603 ± 981 cycles. None of the oblong-grit-blasted designs failed in the low-or high-density bone models and none of the circular-porous designs failed in the high-density bone models after 10,000 cycles of loading. CONCLUSION These results demonstrate that significant differences in initial fixation exist between reverse shoulder implants having an equivalent center of rotation and suggest that design parameters, other than the position of the center of rotation, significantly affect fixation in low-density and high-density polyurethane bone substitutes. Subtle changes in glenoid baseplate design can dramatically affect fixation, particularly in low-density bone substitutes that are intended to simulate the bone quality of the recipient population for reverse shoulders.