Daniel J. Blizzard

Is It Possible to Train Patients to Limit Weight Bearing on a Lower Extremity

Orthopedic patients are often instructed on how much weight to bear on an injured or postoperative extremity. Although specific weight-bearing instructions are given to a majority of lower-extremity orthopedic patients, the ability of patients to comply with these instructions is questioned in the medical literature. This study compared the effectiveness of new forms of clinical interventions designed to train patients on weight bearing, focusing on the use of biofeedback devices designed to offer real-time feedback to partial weight-bearing patients. Twenty healthy patients aged 20 to 30 years completed 3 interventions: (1) verbal instructions on weight bearing, (2) training with a bathroom scale, and (3) training with a biofeedback device.Patients given touchdown weight-bearing instructions (25 lb) initially bore an average of 63.57±6.24 lb when given verbal instructions. This was reduced to 44.75±5.69 lb after training with a bathroom scale (P<.001), and was further reduced to 26.2±1.57 lb with biofeedback training (P=.011). Likewise, patients given partial weight-bearing instructions (75 lb) initially bore an average of 92.28±7.85 lb. No improvement occurred with the use of a bathroom scale (at 75 lb), which showed an average of 90.82±7.19 lb (P=1.000). Training with a biofeedback device improved the average weight bearing to 69.67±3.18 lb (P=.014).Biofeedback training led to superior compliance with touchdown and partial weight-bearing instructions. Because partial weight-bearing instructions are commonly given to orthopedic patients, training with such a device may be appropriately considered.

Interrater and intrarater agreements of magnetic resonance imaging findings in the lumbar spine: significant variability across degenerative conditions

BACKGROUND CONTEXT Magnetic resonance imaging (MRI) is frequently used in the evaluation of degenerative conditions in the lumbar spine. The relative interrater and intrarater agreements of MRI findings across different pathologic conditions are underexplored, as most studies are focused on specific findings. PURPOSE The purpose of this study was to characterize the interrater and intrarater agreements of MRI findings used to assess the degenerative lumbar spine. STUDY DESIGN A retrospective diagnostic study at a large academic medical center was undertaken with a panel of orthopedic surgeons and musculoskeletal radiologists to assess lumbar MRIs using standardized criteria. PATIENT SAMPLE Seventy-five subjects who underwent routine lumbar spine MRI at our institution were included. OUTCOME MEASURES Each MRI study was assessed for 10 lumbar degenerative findings using standardized criteria. Lumbar vertebral levels were assessed independently, where applicable, for a total of 52 data points collected per study. METHODS T2-weighted axial and sagittal MRI sequences were presented in random order to the four reviewers (two orthopedic spine surgeons and two musculoskeletal radiologists) independently to determine interrater agreement. The first 10 studies were reevaluated at the end to determine intrarater agreement. Images were assessed using standardized and pilot-tested criteria to assess disc degeneration, stenosis, and other degenerative changes. Interrater and intrarater absolute percent agreements were calculated. To highlight the most clinically important MRI disagreements, a modified agreement analysis was also performed (in which disagreements between the lowest two severity grades for applicable conditions were ignored). Fleiss kappa coefficients for interrater agreement were determined. RESULTS The overall absolute and modified interrater agreements were 76.9% and 93.5%, respectively. The absolute and modified intrarater agreements were 81.3% and 92.7%, respectively. Average Fleiss kappa coefficient was 0.431, suggesting moderate overall agreement. However, when stratified by condition, absolute interrater agreement ranged from 65.1% to 92.0%. Disc hydration, disc space height, and bone marrow changes exhibited the lowest absolute interrater agreements. The absolute intrarater agreement had a narrower range, from 74.5% to 91.5%. Fleiss kappa coefficients ranged from fair-to-substantial agreement (0.282-0.618). CONCLUSIONS Even in a study using standardized evaluation criteria, there was significant variability in the interrater and intrarater agreements of MRI in assessing different degenerative conditions of the lumbar spine. Clinicians should be aware of the condition-specific diagnostic limitations of MRI interpretation.

Lower-extremity Weight-bearing Compliance Is Maintained Over Time After Biofeedback Training

Previous studies have shown immediate compliance with weight-bearing instructions to be better after biofeedback training than after verbal or scale training. This study assessed retention of biofeedback training to determine potential clinical applicability. Twelve participants were enrolled in a prospective clinical study at an academic orthopedic center. Participants were trained with a biofeedback device to comply with touch-down weight-bearing instructions (25 lb). Immediately following the training session, weight bearing was assessed for each participant. The retention of this training was then reassessed at 2 to 4, 6 to 8, and 22 to 24 hours. Two control participants were given no biofeedback training (verbal instructions only) and were followed similarly. Following initial biofeedback training at 25 lb, participants bore an average of 20.4±2.12 lb. Retention tests during the 24-hour period showed no significant difference from the original testing, with 2- to 4-hour retention of 19.98±4.75 lb, 6- to 8-hour retention of 25.07±6.60 lb, and 22- to 24-hour retention of 21.75±4.58 lb. Participants who only received verbal instructions consistently bore several-fold greater weight than instructed. Biofeedback training has previously been shown to have a strong immediate effect on partial weight-bearing compliance. This study demonstrated that this effect lasts up to 24 hours. This maintained weight-bearing compliance after biofeedback training suggests that this method may be an effective way to train patients to comply with given instructions for limited weight bearing.

3D-FSE Isotropic MRI of the Lumbar Spine: Novel Application of an Existing Technology.

Study Design: Retrospective diagnostic trial. Objective: To determine the diagnostic performance of 3-dimensional isotropic fast/turbo spin-echo (3D-TSE) in routine lumbar spine magnetic resonance imaging (MRI). Summary of Background Data: Conventional 2-dimensional fast spin-echo (2D-FSE) MRI requires independent acquisition of each desired imaging plane. This is time consuming and potentially problematic in spine imaging, as the plane of interest varies along the vertical axis due to lordosis, kyphosis, or possible deformity. 3D-TSE provides the capability to acquire volumetric data sets that can be dynamically reformatted to create images in any desired plane. Methods: Eighty subjects scheduled for routine lumbar MRI were included in a retrospective trial. Each subject underwent both 3D-TSE and conventional 2D-FSE axial and sagittal MRI sequences. For each subject, the 3D-TSE and 2D-FSE sequences were separately evaluated (minimum 4 wk apart) in a randomized order and read independently by 4 reviewers. Images were evaluated using specific criteria for stenosis, herniation, and degenerative changes. Results: The intermethod reliability for the 4 reviewers was 85.3%. Modified intermethod reliability analysis, disregarding disagreements between the lowest 2 descriptors for appropriate criteria (equivalent to “none” and “mild”), revealed average overall agreement of 94.6%. Using the above, modified criteria, interobserver variability for 3D-TSE was 89.1% and 88.3% for 2D-FSE (P=0.05), and intraobserver variability for 3D-TSE was 87.2% and 82.0% for 2D-FSE (P<0.01). The intermethod agreement between 3D-TSE and 2D-FSE was statistically noninferior to intraobserver 2D-FSE variability (P<0.01). Conclusions: This systematic evaluation showed that there is a very high degree of agreement between diagnostic findings assessed on 3D-TSE and conventional 2D-FSE sequences. Overall, intermethod agreement was statistically noninferior to the intraobserver agreement between repeated 2D-FSE evaluations. Overall, this study shows that 3D-TSE performs equivalently, if not superiorly to 2D-FSE sequences. Reviewers found particular utility for the ability to manipulate image planes with the 3D-TSE if there was greater pathology or anatomic variation.

Effect of Age on Partial Weight-bearing Training

Biofeedback devices are increasingly used to train orthopedic patients to comply with partial weight-bearing instructions for an injured or postoperative extremity. In a previous study, the authors showed that biofeedback was effective in training young participants. However, because many partial weight-bearing orthopedic patients are of advanced age, the current study was designed to test the effect of age on partial weight-bearing training. Fifty asymptomatic participants aged between 20 and 78 years completed 3 interventions: (1) verbal instructions on weight bearing, (2) training with a bathroom scale, and (3) training with a biofeedback device. Participants given only verbal touchdown weight-bearing instructions (25 lb) initially bore an average of 61.25±4.80 lb. This was reduced to 51.50±4.47 lb after training with a bathroom scale and further reduced to 30.01±2.33 lb after biofeedback training. Likewise, participants given verbal partial weight-bearing instructions (75 lb) initially bore an average of 89.06±5.58 lb. No improvement was observed with the use of a bathroom scale (average, 88.47±4.75 lb). After training with the biofeedback device, weight bearing improved to an average of 68.11±2.46 lb. Mixed-model analysis revealed that age was not a significant predictor of compliance. However, a higher body mass index and male sex were predictive of worse compliance and heavier weight bearing. Biofeedback training leads to superior compliance to weight-bearing instructions compared with verbal instructions or training with a bathroom scale. Because partial weight-bearing instructions are commonly given to orthopedic patients, biofeedback training may be appropriately considered in any age group with similar effect.

Extreme lateral interbody fusion with posterior instrumentation for spondylodiscitis

The purpose of this study was to evaluate our initial experience utilizing extreme lateral interbody fusion (XLIF; NuVasive, San Diego, CA, USA) with percutaneous posterior instrumentation to treat 11 spondylodiscitis patients between January 2011 and February 2014. Although medical management is the first line treatment for spondylodiscitis, many patients fail antibiotic therapy and bracing, or present with instability, neurologic deficits, or sepsis, requiring operative debridement and stabilization. High rates of fusion and infection clearance have been reported with anterior lumbar interbody fusion (ALIF), but this approach requires a morbid exposure, associated with non-trivial rates of vascular and peritoneal complications. XLIF is an increasingly popular interbody fusion technique which utilizes a fast and minimally invasive approach, sparing the anterior longitudinal ligament, and allowing sufficient visualization of the intervertebral discs and bodies to debride and place a large, lordotic cage. The outcome measures for this study included lumbar lordosis, sagittal balance, subsidence, fusion, pain, neurological deficit, and microbiology/laboratory evidence of infection. The mean follow-up time was 9.3 months. All patients had improvements in pain and neurological symptoms. The mean lordosis change was 11.0°, from 23.1° preoperatively to 34.0° postoperatively. Fusion was confirmed with CT scans in five of six patients. At the last follow-up, all patients had normalization of inflammatory markers, no symptoms of infection, and none required repeat surgical treatment for spondylodiscitis. XLIF with percutaneous posterior instrumentation is a minimally invasive technique with reduced morbidity for lumbar spine fusion which affords adequate exposure to the vertebral bodies and discs to aggressively debride necrotic and infected tissue. This study suggests that XLIF may be a safe and effective alternative to ALIF for the treatment of spondylodiscitis.

C5 palsy after cervical laminectomy and fusion: does width of laminectomy matter?

BACKGROUND CONTEXT A common complication of cervical laminectomy and fusion with instrumentation (CLFI) is development of postoperative C5 nerve palsy. A proposed etiology is excess nerve tension from posterior drift of the spinal cord after decompression. We hypothesize that laminectomy width will be significantly increased in patients with C5 palsy and will correlate with palsy severity. PURPOSE The purposes of this study were to evaluate laminectomy width as a risk factor for C5 palsy and to assess correlation with palsy severity. STUDY DESIGN/SETTING This is a retrospective, single-institution clinical study. PATIENT SAMPLE Patient population included all patients with cervical spondylotic myelopathy who underwent CLFI between 2007 and 2014 by a single surgeon. Patients who underwent CLFI for trauma, infection, or tumor or had previous or circumferential cervical surgery were excluded. All patients with a new C5 palsy received a postoperative magnetic resonance imaging. An additional computed tomography (CT) scan was ordered to assess hardware. All control patients received a CT scan at 6 months postoperatively to evaluate fusion. OUTCOME MEASURES The association between width of laminectomy and development of postopeative C5 palsy was measured. METHODS Patient comorbidities including obesity, smoking history, and diabetes were recorded in addition to preopertaive and postoperative deltoid and biceps motor strength. Sagittal alignment was measured with C2-C7 Cobb angle preopertaive and postoperative radiographs. The width of laminectomy was measured in a blinded fashion on the postoperative CT scan by two observers. RESULTS Seventeen patients with C5 nerve palsy and 12 controls were identified. There were no baseline differences in age, sex, diabetes, smoking history, number of surgical levels, or sagittal alignment. Body mass index was significantly higher in the control cohort. There was no significant increase in the C3-C7 laminectomy width in patients with postoperative C5 palsy. The width of laminectomy measurments were highly similar between the two observers. There was no correlation between laminectomy width and palsy severity. CONCLUSIONS This is the largest series of C5 palsies after laminectomy documented with CT imaging. Laminectomy width was not associated with an increased risk of postoperative C5 palsy at any level. Reduction in laminectomy width may not reduce rate of postoperative nerve palsy.

Routine Imaging for Anterior Cervical Decompression and Fusion Procedures: A Survey Study Establishing Current Practice Patterns

The number of anterior cervical decompression and fusion procedures performed annually in the United States rose 8-fold from 1990 to 2004. Imaging for anterior cervical decompression and fusion procedures contributes to health care costs and exposes patients and staff to radiation. Despite this, no standard of care for such imaging has been defined, and imaging practices have remained largely uncharacterized. The authors distributed a questionnaire at the 2011 Spine Study Group meeting. They received 72 responses (80% response rate) and included 67 in the analysis. All participants were attending spine surgeons practicing in the United States, 97% of whom had completed spine surgery fellowships. Median practice duration was 8 years. Practice type was evenly split between private and academic, and the median annual number of anterior cervical decompression and fusion procedures was 50. Intraoperatively, 68% of surgeons use fluoroscopy and 32% use plain radiographs; 60% take at least 1 image prior to incision; 78% place the localizer in the disk, whereas 22% place it in the vertebral body, and 45% always save these localizer images; 100% take images of the final construct before leaving the operating room, and 74% always save the final-construct images. Postoperatively but before discharge, 12% of surgeons take images in the recovery room, 33% take images in the radiology suite, and 2% take images in both locations. After discharge, surgeons follow their patients for a mean of 1.6 years, 96% with lateral views, 96% with anteroposterior views, 46% with flexion-extension radiographs, and 14% with computed tomography scans.

Optimal aspiration volume of vertebral bone marrow for use in spinal fusion

BACKGROUND CONTEXT Bone marrow aspirate (BMA) has shown promise as a bone graft option in spinal fusion. The vertebral body is a convenient source for marrow aspirate as it is accessed in routine course of pedicle screw instrumentation. Studies have relied on data from the iliac crest to determine optimal aspiration volume from the vertebral body. PURPOSE This study is designed to determine the optimal aspiration volume for BMA taken from the vertebral body. STUDY DESIGN Prospective clinical study. PATIENT SAMPLE Data are drawn from 18 pedicles and 180 aspirations. The average age of the subjects was 50.3 years, and the subject pool comprised five men and seven women. OUTCOME MEASURES Nucleated cell count and alkaline phosphatase staining colony forming units. METHODS Ten 1 mL aliquots of BMA were incrementally aspirated through a cannulated pedicle tap for each instrumented vertebral body. The numbers of nucleated cells per mL of BMA were analyzed with a hemocytometer, and the percentage of osteoprogenitor cells per mL aspirate were estimated by an alk phos production assay. The study was funded through departmental funds, and none of the authors have any conflicts of interest to report related to the study. RESULTS Nucleated cell count decreased with increasing aspirate number (p<.001). The average cell count for the first mL was 45.8 million cells. Cell counts did not differ by age or sex (p=.943 and p=.685, respectively). Likewise, osteoprogenitor cell percentage decreased with increasing aspirate number (p<.001). CONCLUSIONS The 2 mL aspirate volume has been defined as ideal for the iliac crest, but there has been no analogous assessment of the effect of aspiration volume for other sources such as the vertebral body. This information is important for the clinical implementation of vertebral body aspirations if volume, cells, and presumably performance, of this potential bone graft option are to be optimized for spine cases. Our data show a direct relationship between increasing aspiration number and decreasing osteoprogenitor cellular concentration, with a drop to 50% of the original aspirate cell count by the 4th mL aspirate. The vertebral body is a potentially exciting source of osteoprogenitor cells that can be implemented for a variety of spinal uses.

Routine anteroposterior radiographs have limited utility for patients after anterior cervical decompression and fusion.

Study Design. A retrospective case series. Objective. To assess the diagnostic utility of sequential anteroposterior (AP) radiographs for following patients with postoperative anterior cervical decompression and fusion (ACDF). Summary of Background Data. There are currently no widely accepted standards for radiographical follow-up after ACDF. Many spine surgeons routinely obtain at least AP and lateral films at serial follow-up visits. It is generally accepted that lateral films are of utility to assess overall alignment, evaluate union, and detect any potential construct-related issues. It is our perception that the AP view adds little or no clinical value after documentation of alignment on an initial film. Methods. All follow-up imaging series were evaluated for 100 patients who underwent ACDF. Variables thought to be potentially detected on the AP film were evaluated on both the AP and lateral films (visualization of the implant and instrumented vertebral bodies and any construct-related issues). In addition, angulation of the implant relative to the vertebral axis of the instrumented levels was measured on the AP film. Results. For the 100 patients evaluated, the follow-up period was 1.2 ± 0.5 months (mean ± SD), with 4.39 ± 1.52 imaging series obtained per patient. Instrumented vertebral bodies were fully visualized in 99.5% of AP and 86.7% of lateral films obtained at follow-up visits. The entire implant was visualized in 100% of AP films and 95.6% of lateral films. No hardware-related issues were seen (screw disengagement, pullout, breakage, etc.). No patients were found to have progression of coronal plate angulation beyond 3° at their last follow-up series relative to the first follow-up visit. Conclusion. Using rigorous evaluation methods, we found no significant incremental utility of AP films obtained in addition to lateral films. Therefore, given the inherent cost, time, and radiation exposure associated with each additional view, we propose that AP films should not be part of routine follow-up imaging after ACDF.