Search

Objective: Changing Behavior through Physical Therapy (CBPT), a cognitive-behavioral-based program, has been shown to improve outcomes after lumbar spine surgery in patients with a high psychosocial risk profile; however, little is known about potential mechanisms associated with CBPT treatment effects. The purpose of this study was to explore potential mediators underlying CBPT efficacy after spine surgery., Methods: In this secondary analysis, 86 participants were enrolled in a randomized trial comparing a postoperative CBPT (n = 43) and education program (n = 43). Participants completed validated questionnaires at 6 weeks (baseline) and 3 and 6 months following surgery for back pain (Brief Pain Inventory), disability (Oswestry Disability Index), physical health (12-Item Short-Form Health Survey), fear of movement (Tampa Scale for Kinesiophobia), pain catastrophizing (Pain Catastrophizing Scale), and pain self-efficacy (Pain Self-Efficacy Questionnaire). Parallel multiple mediation analyses using Statistical Package for the Social Sciences (SPSS) were conducted to examine whether 3- and 6-month changes in fear of movement, pain catastrophizing, and pain self-efficacy mediate treatment outcome effects at 6 months., Results: Six-month changes, but not 3-month changes, in fear of movement and pain self-efficacy mediated postoperative outcomes at 6 months. Specifically, changes in fear of movement mediated the effects of CBPT treatment on disability (indirect effect = -2.0 [95% CI = -4.3 to 0.3]), whereas changes in pain self-efficacy mediated the effects of CBPT treatment on physical health (indirect effect = 3.5 [95% CI = 1.2 to 6.1])., Conclusions: This study advances evidence on potential mechanisms underlying cognitive-behavioral strategies. Future work with larger samples is needed to establish whether these factors are a definitive causal mechanism., Impact: Fear of movement and pain self-efficacy may be important mechanisms to consider when developing and testing psychologically informed physical therapy programs., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Physical Therapy Association. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background Context: Low back pain has an immense impact on the US economy. A significant number of patients undergo surgical management in order to regain meaningful functionality in daily life and in the workplace. Return to work (RTW) is a key metric in surgical outcomes, as it has profound implications for both individual patients and the economy at large., Purpose: In this study, we investigated the factors associated with RTW in patients who achieved otherwise favorable outcomes after lumbar spine surgery., Study Design/setting: This study retrospectively analyzes prospectively collected data from the lumbar module of national spine registry, the Quality Outcomes Database (QOD)., Patient Sample: The lumbar module of QOD includes patients undergoing lumbar surgery for primary stenosis, disc herniation, spondylolisthesis (Grade I) and symptomatic mechanical disc collapse or revision surgery for recurrent same-level disc herniation, pseudarthrosis, and adjacent segment disease. Exclusion criteria included age under 18 years and diagnoses of infection, tumor, or trauma as the cause of lumbar-related pain., Outcome Measures: The outcome of interest for this study was the return to work 12-month after surgery., Methods: The lumbar module of QOD was queried for patients who were employed at the time of surgery. Good outcomes were defined as patients who had no adverse events (readmissions/complications), had achieved 30% improvement in Oswestry disability index (ODI) and were satisfied (NASS satisfaction) at 3-month post-surgery. Distinct multivariable logistic regression models were fitted with 12-month RTW as outcome for a. overall population and b. the patients with good outcomes. The variables included in the models were age, gender, race, insurance type, education level, occupation type, currently working/on-leave status, workers' compensation, ambulatory status, smoking status, anxiety, depression, symptom duration, number of spinal levels, diabetes, motor deficit, and preoperative back-pain, leg-pain and ODI score., Results: Of the total 12,435 patients, 10,604 (85.3%) had successful RTW at 1-year postsurgery. Among patients who achieved good surgical outcomes, 605 (7%) failed to RTW. For both the overall and subgroup analysis, older patients had lower odds of RTW. Females had lower odds of RTW compared with males and patients with higher back pain and baseline ODI had lower odds of RTW. Patients with longer duration of symptoms, more physically demanding occupations, worker's compensation claim and those who had short-term disability leave at the time of surgery had lower odds of RTW independent of their good surgical outcomes., Conclusions: This study identifies certain risk factors for failure to RTW independent of surgical outcomes. Most of these risk factors are occupational; hence, involving the patient's employer in treatment process and setting realistic expectations may help improve the patients' work-related functionality., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Unlabelled: The purpose of this study was to determine the efficacy of a cognitive-behavioral-based physical therapy (CBPT) program for improving outcomes in patients after lumbar spine surgery. A randomized controlled trial was conducted on 86 adults undergoing a laminectomy with or without arthrodesis for a lumbar degenerative condition. Patients were screened preoperatively for high fear of movement using the Tampa Scale for Kinesiophobia. Randomization to either CBPT or an education program occurred at 6 weeks after surgery. Assessments were completed pretreatment, posttreatment and at 3-month follow-up. The primary outcomes were pain and disability measured by the Brief Pain Inventory and Oswestry Disability Index. Secondary outcomes included general health (SF-12) and performance-based tests (5-Chair Stand, Timed Up and Go, 10-Meter Walk). Multivariable linear regression analyses found that CBPT participants had significantly greater decreases in pain and disability and increases in general health and physical performance compared with the education group at the 3-month follow-up. Results suggest a targeted CBPT program may result in significant and clinically meaningful improvement in postoperative outcomes. CBPT has the potential to be an evidence-based program that clinicians can recommend for patients at risk for poor recovery after spine surgery., Perspective: This study investigated a targeted cognitive-behavioral-based physical therapy program for patients after lumbar spine surgery. Findings lend support to the hypothesis that incorporating cognitive-behavioral strategies into postoperative physical therapy may address psychosocial risk factors and improve pain, disability, general health, and physical performance outcomes., (Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.)

Background Context: A physician's role within a workers' compensation injury extends far beyond just evaluation and treatment with several socioeconomic and psychological factors at play compared with similar injuries occurring outside of the workplace. Although workers' compensation statutes vary among states, all have several basic features with the overall goal of returning the injured worker to maximal function in the shortest time period, with the least residual disability and shortest time away from work., Purpose: To help physicians unfamiliar with the workers' compensation process accomplish these goals., Study Design: Review., Methods: Educational review., Results: The streamlined review addresses the topics of why is workers' compensation necessary; what does workers' compensation cover; progression after work injury; impairment and maximum medical improvement, including how to use the sixth edition of American Medical Association's (AMA) Guides to the evaluation of permanent impairment (Guides); completion of work injury claim after impairment rating; independent medical evaluation; and causation., Conclusions: In the "no-fault" workers' compensation system, physicians play a key role in progressing the claim along and, more importantly, getting the injured worker back to work as soon as safely possible. Physicians should remain familiar with the workers' compensation process, along with how to properly use the AMA Guides., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background and Purpose: Fear of movement is a risk factor for poor postoperative outcomes in patients following spine surgery. The purposes of this case series were: (1) to describe the effects of a cognitive-behavioral-based physical therapy (CBPT) intervention in patients with high fear of movement following lumbar spine surgery and (2) to assess the feasibility of physical therapists delivering cognitive-behavioral techniques over the telephone., Case Description: Eight patients who underwent surgery for a lumbar degenerative condition completed the 6-session CBPT intervention. The intervention included empirically supported behavioral self-management, problem solving, and cognitive restructuring and relaxation strategies and was conducted in person and then weekly over the phone. Patient-reported outcomes of pain and disability were assessed at baseline (6 weeks after surgery), postintervention (3 months after surgery), and at follow-up (6 months after surgery). Performance-based outcomes were tested at baseline and postintervention. The outcome measures were the Brief Pain Inventory, Oswestry Disability Index, 5-Chair Stand Test, and 10-Meter Walk Test., Outcomes: Seven of the patients demonstrated a clinically significant reduction in pain, and all 8 of the patients had a clinically significant reduction in disability at 6-month follow-up. Improvement on the performance-based tests also was noted postintervention, with 5 patients demonstrating clinically meaningful change on the 10-Meter Walk Test., Discussion: The findings suggest that physical therapists can feasibly implement cognitive-behavioral skills over the telephone and may positively affect outcomes after spine surgery. However, a randomized clinical trial is needed to confirm the results of this case series and the efficacy of the CBPT intervention. Clinical implications include broadening the availability of well-accepted cognitive-behavioral strategies by expanding implementation to physical therapists and through a telephone delivery model.

Calcium phosphate (CaP)/polymer composites have been studied as an alternative graft material for the treatment of bone defects. In this study, lysine-triisocyanate-based polyurethane (PUR) composites were synthesized from both hydroxyapatite (HA) and β-tricalcium phosphate (TCP) to reduce the brittleness of CaP and increase the bioactivity of the polymer. The mechanical properties and in vitro cellular response were investigated for both HA/PUR and TCP/PUR composites. The composites were implanted in femoral defects in rats, and in vivo bioactivity was evaluated by X-rays, micro-computed tomography (μCT), and histological sections. In biomechanical testing, PUR improved the mechanical properties of the CaP, thus rendering it potentially suitable for weight-bearing applications. In vitro cell culture studies showed that CaP/PUR composites are biocompatible, with β-TCP enhancing the cell viability and proliferation relative to HA. CaP/PUR composites also supported the differentiation of osteoblastic cells on the materials. When implanted in rat femoral defects, the CaP/PUR composites were biocompatible and osteoconductive with no adverse inflammatory response, as evidenced by X-rays, μCT images, and histological sections. Additionally, a histological examination showed evidence of cellular infiltration and appositional remodeling. These results suggest that CaP/PUR composites could be potentially useful biomaterials for weight-bearing orthopaedic implants., (Copyright © 2011 Wiley Periodicals, Inc.)

Scaffolds prepared from biodegradable polyurethanes (PUR) have been investigated as a supportive matrix and delivery system for skin, cardiovascular, and bone tissue engineering. In this study, we combined reactive two-component PUR scaffolds with lovastatin (LV), which has been reported to have a bone anabolic effect especially when delivered locally, for effective bone tissue regeneration. To incorporate LV into PUR scaffolds, LV was combined with the hardener component before scaffold synthesis. The PUR scaffolds containing LV (PUR/LV) demonstrated a highly porous structure with interconnected pores, which supported in vitro cell attachment and proliferation and in vivo osteoconductive potential. The PUR/LV scaffolds showed sustained release of biologically active LV, as evidenced by the fact that LV releasates significantly enhanced osteogenic differentiation of osteoblastic cells in vitro. A study of bone formation in vivo using a rat plug defect model showed that the PUR/LV scaffolds were biocompatible. Further, locally delivered LV enhanced new bone formation in the PUR scaffolds at week 4, while there were no obvious effects at week 2. These results suggest that the sustained LV delivery system from PUR scaffolds is a potentially safe and effective device for bone regeneration.

Study Design: This is a retrospective study of 250 patients who describe low back pain with pain drawings. A computer application using artificial neural networks was designed to analyze pain drawings and evaluate the contribution of pain sensation to drawing classification., Objective: The primary goal of this study was to assess the contribution of patient recorded pain sensation marks in classifying pain drawings into one of five broadly defined categories. The hypothesis was that including pain sensation would improve classification., Summary of Background Data: With no perfect diagnostic test for patients with low back pain, many approaches have been proposed and are used. One common diagnostic tool is the pain drawing. Several quantitative methods have been proposed to score the drawings. Some methods use pain sensation in the scoring; however, the contribution of pain sensation has not been defined., Methods: A custom computer application classified the pain drawing. Data consisted of 250 pain drawings from patients with low back pain., Results: Patient recorded pain sensation is not necessary in computer-based scoring of pain drawings., Conclusion: Patient-reported pain sensation does not improve classification when quantitatively scoring pain drawings.

Purpose: Recently, MMP-7 and MMP-3 have been found to play a crucial role in the natural resorption process of herniated discs. We therefore examined the role of these recombinant human matrix metalloproteinases (rh MMPs) in the treatment of herniated discs., Methods: (a) Surgical samples of herniated disc were cultured in the presence or absence of rh MMPs, and wet weight was measured 24h later. (b) The rh MMPs were administered into normal rabbit intervertebral discs, and after 1 week spine samples were stained with Safranin O. (c) The rh MMPs were administered into canine herniated discs in vivo. Myelography and MRI were performed prior to and 1 week after administration. Spine samples were examined histologically. Whole disc tissue was collected, total protein was extracted, and Western blot analysis was performed., Results: (a) Proteoglycan degradation was found in MMP-7, MMP-3, and chymopapain-treated samples. MMP-7 and chymopapain-treated samples displayed a significant loss in wet weight (p<0.01). (b) Normal disc tissues after administration of rh MMP-7, MMP-3, and chymopapain showed an extensive loss of Safranin O staining. (c) The rh MMP-7-treated discs had a marked decrease in protruded herniation by MRI. Herniated discs after administration of MMP-7 and chymopapain showed a significant decrease in protruded mass 7 days after administration compared with saline-treated discs when evaluated by myelography (p<0.01). The rh MMP-7-treated discs displayed a clear loss of Safranin O staining in the nucleus pulposus. Proteoglycan expression was barely detectable in disc tissues after MMP-7 administration, whereas obvious expression was obtained in saline-treated or untreated disc tissues., Conclusions: Exposure to rh MMP-7 resulted in promising proteoglycan loss in human surgical samples, normal rabbit intervertebral discs, and natural canine herniated discs. Administration of rh MMP-7 may facilitate the resorption process of herniated discs.

Study Design: A retrospective review of patient outcomes after lumbar spinal fusion., Objective: To determine whether patients with a fusion ending adjacent to a "degenerated disc" (DDD group) had worse clinical outcomes than patients with fusions ending adjacent to "normal" discs (NL group)., Summary of Background Data: Although it has been suggested that creating a rigid motion segment adjacent to a degenerated segment may negatively impact clinical outcomes after lumbar fusion, this question has not been addressed to our knowledge in the English literature., Methods: Twenty-five consecutive patients treated with lumbar fusion for degenerative instability who had preoperative lumbar spine magnetic resonance imaging, who completed health status questionnaire Short Form 36 (SF-36), and were seen in the office for radiographic follow-up at least 2 years following surgical treatment formed the study group. The magnetic resonance images were reviewed independently by two spine surgeons and rated for the presence of any degenerative changes. Statistical analysis of the SF-36 data was performed with chi2 and Mann-Whitney U testing., Results: Of the 25 patients, 20 were fused adjacent to at least one degenerated level (DDD group), whereas 5 were fused adjacent to a normal level (NL group). At follow-up, SF-36 scores were higher for the DDD group in all eight subgroups, contrary to the research hypothesis. A power analysis demonstrated with at least 98% certainty that if patients in the DDD group had even a 10% lower score in any of the 8 SF-36 subgroups, this study would have detected it., Conclusion: This retrospective review of patients who underwent lumbar fusion for degenerative instability demonstrated no adverse impact on clinical outcomes when the lumbar fusion ended adjacent to a degenerative motion segment. Although a power analysis validated these results with 98% certainty, larger prospective studies are needed to confirm that there is no benefit to include degenerated adjacent segments in a lumbar fusion for degenerative instability.

Background Context: Many authors have evaluated the components responsible for ultimate pullout strength of pedicle screws. In these studies, one important variable has been the screw fixation. Because pedicle screw fixation has increased in popularity over recent years, so has the need for augmentation in difficult situations. Polymethylmethacrylate (PMMA) has been established as the gold standard in terms of strength of fixation but has the potential for severe complications when applied in spine surgery. Calcium sulfate is an alternative to PMMA, because it lacks the exothermic reaction, is potentially osteoconductive and is resorbed by the body in 30 to 60 days., Purpose: To determine the strength of a new calcium sulfate cement in terms of pedicle screw augmentation. The purpose was to evaluate calcium sulfate versus PMMA in terms of pullout strength. PMMA was considered the gold standard in terms of strength for this experiment., Study Design: Lumbar vertebrae implanted with pedicle screws were subjected to axial pullout tests. The force required to cause implant failure was measured and compared for three methods of fixation., Outcome Measures: Force to failure (Newtons) for each pedicle test was recorded and analyzed with results from similarly augmented pedicles., Methods: Lumbar vertebrae were harvested from four cadavers and implanted with pedicle screws. These screws were either placed in native bone or augmented with either calcium sulfate paste or PMMA. In those pedicles that had augmentation, the material was permitted to set for a minimum of 24 hours. Axial pullout tests were then performed using an MTS (Materials Testing System Corporation, Minneapolis, MN) testing machine. The screws were pulled out over a distance of up to 6 mm at 0.25 mm/sec. This rate and distance ensured failure in each case. The load to failure was recorded for each pedicle., Results: Calcium sulfate augmentation improved pedicle screw pullout strength significantly when compared with native bone (p=.0003). This represented an average increase of 167% over the native bone. Likewise, PMMA improved the pullout strength significantly over native bone (p<.0001) for an average increase of 199%. There were no significant differences between the calcium sulfate and PMMA augmentation (p=.0791), although the PMMA averaged 119% of the strength of calcium sulfate., Conclusions: Although PMMA is considered the gold standard in terms of fixation strength, its use around the spine has been limited because of concern over complications. The calcium sulfate bone paste tested in this study demonstrated strength similar to PMMA without the major risks to the spinal cord. In addition, the calcium sulfate paste allows for possible osteoconduction to aid in spinal fusion. Further study is needed to determine the applicability of this calcium sulfate paste in the clinical setting of spine surgery.

Summary: An in vivo murine experiment was conducted to measure the capacities of viable intervertebral disc cells to recruit inflammatory cells. The objective was to determine whether compounds secreted from viable cells induce inflammation or whether inflammation in disc herniation simply requires exposure to structural cell or matrix components. Three tissue preparations were inserted into the right lower peritoneal cavity of male mice: tissue with viable annulus fibrosus and nucleus pulposus cells, tissue with viable annulus fibrosus cells, or devitalized annulus fibrosus and nucleus pulposus tissue. Controls included sham-operated and nonoperated groups. Mice were killed 1, 2, or 7 days after surgery. Macrophage recruitment occurred after exposure to viable disc tissue but not after exposure to devitalized disc components; recruitment increased over time. Viable disc cells play a role in the etiology of inflammation in disc herniation.

As part of a program of research aimed at determining the role of mechanical forces in connective tissue differentiation, we have developed a model for investigating the effects of dynamic compressive loading on chondrocyte differentiation in vitro. In the current study, we examined the influence of cyclic compressive loading of chick limb bud mesenchymal cells to a constant peak stress of 9.25 kPa during each of the first 3 days in culture. Cells embedded in agarose gel were subjected to uniaxial, cyclic compression at 0.03, 0.15, or 0.33 Hz for 2 h. In addition, load durations of 12, 54, or 120 min were evaluated while holding frequency constant at 0.33 Hz. For a 2 h duration, there was no response to loading at 0.03 Hz. A significant increase in chondrocyte differentiation was associated with loading at 0.15 Hz, and an even greater increase with loading at 0.33 Hz. Holding frequency constant at 0.33 Hz, a loading duration of 12 min elicited no response, whereas chondrocyte differentiation was enhanced by loading for either 54 or 120 min. Although not statistically significant from the 120 min response, average cartilage nodule density and glycosaminoglycan synthesis rate were highest in the 54 min duration group. This result suggests that cells may be sensitive to the level of cumulative (nonrecoverable) compressive strain, as well as to the dynamic strain history.

Herniated disc (HD) is a common health problem that is resolved by surgery unless spontaneous resorption occurs. HD tissue contains abundant macrophage infiltration and high levels of matrix metalloproteinases (MMPs) MMP-3 and MMP-7. We developed a model system in which disc tissue or isolated chondrocytes from wild-type or MMP-null mice were cocultured with peritoneal macrophages and used this system to investigate the role of MMPs and chondrocyte/macrophage interactions in disc resorption. We observed a marked enhancement of MMP-3 protein and mRNA in chondrocytes after exposure to macrophages. Chondrocytic MMP-3, but not MMP-7, was required for disc resorption, as determined by assaying for a reduction in wet weight and proteoglycan content after 3 days of coculture. Surprisingly, chondrocyte MMP-3 was required for the generation of a macrophage chemoattractant and the subsequent infiltration of the disc tissue by proteolytically active macrophages. We conclude that macrophage induction of chondrocyte MMP-3 plays a major role in disc resorption by mechanisms that include the generation of a bioactive macrophage chemoattractant.

Herniated disc (HD), one of the major causes of low back pain, is often resolved spontaneously without surgical intervention. Resorption is associated with a marked increase in infiltrating macrophages, and the matrix metalloproteinases (MMP) MMP-3 and MMP-7 have been implicated in this phenomenon. We developed a murine organ culture model in which intact intervertebral discs were cocultured with peritoneal macrophages to investigate the role of MMPs in HD resorption. Using macrophages isolated from MMP-null mice, we report that macrophage-produced MMP-7 was required for proteoglycan degradation, loss of wet weight, and macrophage infiltration of cocultured discs. The inability of MMP-7-deficient macrophages to infiltrate discs could not be attributed to a defect in macrophage migration. MMP-7 was required for the release of the cytokine TNF-alpha from peritoneal macrophages. The generation of soluble TNF-alpha was essential for the induction of MMP-3 in disc cocultures, which in turn is required for the generation of a macrophage chemoattractant and subsequent macrophage infiltration. TNF-alpha release from macrophages was necessary but insufficient for disc resorption, which required macrophage infiltration. We conclude that there is extensive communication between macrophages and chondrocytes in HD resorption and that an essential component of this communication is the requirement for MMPs to release soluble bioactive factors.

We used the data from a retrospective case controlled study to identify risk factors for methicillin-resistant staphylococcal wound infection after spinal surgery. Thirty-five cases and 35 uninfected control patients were matched for indication for initial surgery and approximate operative date. Preoperative, intraoperative, and postoperative risk factors were examined. At our institution between 1989 and 1995, 35 adult patients developed spinal wound infection requiring operative debridement; 16 infections were caused by methicillin-resistant staphylococci (MRS). Significant risk factors for MRS infection were lymphopenia, history of chronic infections, alcohol abuse, recent hospitalization, and prolonged postoperative wound drainage. Patients with MRS infections were also somewhat less likely to have received vancomycin prophylaxis. In contrast, the only factor associated with infection caused by other pathogens was alcohol abuse. A number of preoperative risk factors were significantly associated with subsequent MRS spinal wound infection. Chemoprophylaxis with vancomycin should be targeted to patients at increased risk, because overuse may promote the emergence of vancomycin-resistant pathogens.

Spontaneous resorption of herniated nucleus pulposus (HNP) is commonly observed when there is substantial contact of the disc with the spinal canal. We already demonstrated the expression of matrix metalloproteinase (MMP)-3 (stromelysin-1) in the granulation tissues of HNP, suggesting its role in the resorption process of HNP. Recent studies of osteoarthritic cartilages reported an up-regulated expression of metalloproteinases including MMP-7 (matrilysin) and MMP-8 (neutrophil collagenase), suggesting their roles in the matrix degradation. To clarify the expression of MMP-7 and MMP-8 in HNP, immunohistological analysis of various types of HNP was performed. We found MMP-7 was expressed in infiltrated mononuclear cells and chondrocytes, whereas MMP-8 was specifically expressed in chondrocytes. The positive rate for both MMP-7 and MMP-8 significantly increased when HNP was exposed to the epidural space (p < 0.01). Our data suggest that not only MMP-3 but also MMP-7 and MMP-8 may play a role in the resorption process of HNP.

We compared the outcomes from lumbar discectomy for patients who were workers' compensation claimants and/or who were involved in active litigation with patients who underwent elective lumbar discectomy, but who were not involved with either compensation or litigation. Eighty-two consecutive patients who underwent elective lumbar discectomy by the senior author were identified from 1989 through 1994. Those patients who underwent a primary discectomy with a minimum of 6 months' follow-up were studied. Patients were excluded if a spinal fusion was performed or if a multilevel laminectomy procedure was required. Patients were classified as compensation patients if they were involved in either worker's compensation claims or active litigation at the time of the lumbar discectomy. The compensation group was further divided into three subsets of patients: those involved in active litigation without compensation, those involved in both compensation and litigation, and those pursuing workers' compensation claims without litigation. The control group was comprised of patients who were not in any way involved with compensation or litigation. Outcome assessment and ratings were determined independently by the coauthors, not the primary surgeon. Outcome was based on pain, employment status, analgesic use, and level of activity. Fifty-four patients met the inclusion criteria. Average follow-up for the compensation patients was 40 weeks. Follow-up for the noncompensation patients averaged 51 weeks. Eighty-one percent of our patients in the noncompensation group achieved a good result. Only 1 of 27 patients was categorized as having a poor outcome. Conversely, patients who were actively involved in the compensation and/or litigation process had significantly poorer outcomes, with only 29% of the patients receiving a good outcome evaluation (p = < 0.0002). Legal involvement was associated with poorer outcome in compensation patients (p = < 0.001).

Background: Percutaneous closed needle biopsy of musculoskeletal neoplasms has gained in popularity. However, it remains controversial whether or not to resect the needle tract for fear of a local recurrence. A single published case report exists, noting the lone tract recurrence of an extremity skeletal osteosarcoma., Methods: We report on three additional individuals who demonstrated that tract local recurrences may occur after a closed needle biopsy for nonosteosarcoma, nonextremity sarcomas. For perspective, the world literature is reviewed to identify tract recurrences for other malignancies and the results of needle biopsy in musculoskeletal neoplasms., Results: Eighty-nine percent of needle tract local recurrences occur when carcinomas are subjected to biopsy, as reported in the literature. Forty-seven cases since 1950 are described representing essentially all tumor types. The nature of musculoskeletal neoplasms makes closed biopsy more difficult than for softer, more homogeneous, and easier to access neoplasms., Conclusions: Local recurrences of sarcoma may occur in closed needle biopsy tracts. Strong consideration should be given to open biopsy and tract resection.

The anterior approach to the cervical spine, first described 40 years ago, has become a popular and widely used procedure by spine surgeons to expose the anterior vertebral bodies from C3 to T1. A significant complication of this procedure is transient or permanent ipsilateral recurrent laryngeal nerve paralysis. In a previous review at our institution of patients with hoarseness after an anterior cervical approach, 15 of 16 patients demonstrated right-sided paralysis. The asymmetry in the anatomic courses and lengths of the recurrent laryngeal nerves are proposed to place the right recurrent laryngeal nerve at an increased risk of stretch-related injury during this surgical procedure. We developed a cadaver model to evaluate the in-line stretch on the recurrent laryngeal nerve during the right- and left-sided approaches to the C4 and C7 vertebral bodies. To assess the difference in risk of injury to the two recurrent laryngeal nerves, we performed the anterior approach to the cervical spine in four anatomic positions: the left neck and right neck at the levels of C4 and C7 on 10 fresh human cadavers during the immediate postmortem period. The blades of a Cloward retractor were progressively spread to 2, 3, and 4 cm in the four anatomic positions while the corresponding degrees of ipsilateral recurrent laryngeal nerve stretch resulting from retraction were simultaneously measured. The left recurrent laryngeal nerve had sufficient redundancy in its course within the tracheoesophageal groove in 10 of 10 cadavers such that it exhibited no in situ stretch during the left-sided approach to either the C4 or C7 vertebrae. In contrast, the right recurrent laryngeal nerve has little redundancy in its course and is not protected within the tracheoesophageal groove. The right-sided approach to C7 resulted in an average in situ stretch on the ipsilateral recurrent laryngeal nerve of 12% and 24%, with 3 cm and 4 cm of Cloward retraction, respectively. The right-sided approach to C4 resulted in significant levels of stretch in 3 (30%) of 10 cadavers and no stretch in 7 (70%) of 10 cadavers. The relevance of these data is demonstrated by the review of numerous studies demonstrating the potential for significant neural damage with nerve stretch greater than 12%.

The broad objective was to develop an information system which integrates various sources of clinical data and facilities outcome assessment for patients evaluated in a lumbar spine service. During a patient encounter, the physician formulates a hypothesis regarding appropriate forms of treatment and he or she may then use this system to explore previous treatment outcomes for similar cases. The availability of a clinical tool that presents information in an outcome-oriented format may be highly relevant to the delivery of cost-efficient, high-quality health care and also create a formal mechanism for detecting practice variability.

A new method has been developed for the Department of Orthopaedics of Vanderbilt University Medical Center to access departmental clinical data. Previously this data was stored only in the medical center's mainframe DB2 database, it is now additionally stored in a departmental SQL database. Access to this data is available via any ODBC compliant front-end or a web client. With a small budget and no full time staff, we were able to give our department on-line access to many years worth of patient data that was previously inaccessible.

Study Design: Laminectomy was performed on cats to destroy the posterior epidural ligament. Evoked potentials and spinal cord blood flows quantified the spinal cord function before and after cervical flexion., Objectives: This work describes a relationship between the loss of the posterior epidural ligaments and cervical spinal cord injury., Summary of Background Data: The posterior epidural ligaments of the human cervical spine have been recently described. These ligaments theoretically prevent injury to the spinal cord by resisting collapse of the dura during cervical flexion., Methods: The animals were divided into three experimental groups: 1) control: no laminectomy and standard position, 2) flexion control: no laminectomy and known imposed flexion, 3) laminectomy (C3-C7) and flexion. Motor-evoked potentials and evoked spinal cord potentials were recorded to quantify the spinal cord functions. Radioactive microspheres were used to quantify ischemia in the spinal cord., Results: Control subjects showed blood flows of 36 mL/100 g/min (C3-C4) to 46 mL/100 g/min (C7-C8). Flexion control subjects did not experience significant reductions in blood flows or substantial change in evoked potentials. The laminectomy plus flexion group experienced reduced blood flows and substantial motor-evoked potentials and slight evoked spinal cord potential changes with 50 degrees, 60 degrees, and 70 degrees flexion. Blood flow reduction was greater in the anterior half of the C7-C8 segments compared with the posterior half at 60 degrees flexion. Evoked spinal cord potentials were less vulnerable than motor-evoked potentials., Conclusions: The role of the posterior cervical epidural ligaments is to anchor the posterior dura mater to the ligamentum flavum. Loss of the ligaments allows anterior displacement of the posterior dura mater in flexion. Abnormal distribution of or lack of the cervical posterior epidural ligaments may lead to flexion myelopathy.

The biomechanics of a new spinal implant were evaluated and its dependence on an anterior strut graft was determined. Six fresh-frozen adult porcine spines were used. An L3 corpectomy was created. The spinal nail was inserted intraosseously into the middle column of the L2-L4 vertebral bodies in a trough. Implant drill holes were made for proximal and distal locking bolts in L2 and L4. A locking plate bridged the L2 and L4 trough and anchored the exposed ends of the locking bolts. Testing was performed in axial compression, torsion, and flexion. The axial and torsional stability of the spine instrumented with the spinal nail are similar to results with other devices when used with anterior strut grafting. The axial and flexural stiffnesses of the instrumented spine are independent of strut grafting. This study suggests that this device may be useful for reconstruction of the anterior spine because of instability.

Study Design: Task-specific and subject-specific lumbar trunk muscle function, muscle geometry, and vertebral density data were collected from 16 men. A biomechanical model was used to determine muscle strength and the compressive forces acting on the lumbar spine., Objectives: To develop an anatomic biomechanical model of the low back that could be used to derive task-specific muscle function parameters and to predict compressive forces acting on the low back. Several model-specific constraints were examined, including the notion of bilateral trunk muscle anatomic symmetry, the influence of muscle lines of action, and the use of density-derived vertebral strength for model validation., Summary of Background Data: Clinical and basic science investigators are currently using a battery of diverse biomechanical techniques to evaluate trunk muscle strength. Noteworthy is the large variability in muscle function parameters reported for different subjects and for different tasks. This information is used to calculate forces and moments acting on the low back, but limited data exist concerning the assessment of subject-specific, multiaxis, isometric trunk muscle functions., Methods: A trunk dynamometer was used to measure maximum upright, isometric trunk moments in the sagittal (extension, flexion) and coronal (lateral flexion) planes. Task- and subject-specific trunk muscle strength or "gain" was determined from the measured trunk moments and magnetic resonance image-based muscle cross-sectional geometry. Model-predicted compressive forces obtained using muscle force and body force equilibrium equations were compared with density-derived estimates of compressive strength., Results: Individual task-specific muscle gain values differed significantly between subjects and between each of the tasks they performed (extension > flexion > lateral flexion). Significant differences were found between left side and right side muscle areas, and the lines of action of the muscles deviated significantly from the vertical plane. Model-predicted lumbar compressive forces were 38% (lateral flexion) to 73% (extension) lower that the L3 vertebral compressive strength estimated from vertebral density., Conclusion: The present study suggests that biomechanical models of the low back should be based on task-specific and subject-specific muscle function and precise geometry. Vertebral strength estimates based upon vertebral density appear to be useful for validation of model force predictions.

The purpose of this article is to clarify one mechanism of muscular atrophy of the distal upper extremity that we attribute to cervical compression (Hirayama-type amyotrophy) by medical imaging and anatomical studies of the cervical spine. Five young male patients (mean age: 22.6 years) with this disorder showed characteristic findings to include an abnormal anterior displacement of the posterior dura wall in flexion that resulted in an anteroposterior compression of the spinal cord segment from C7 to C8. To identify an anatomical relationship to this disorder, the lower cervical spine was studied using 11 embalmed adult human cadavers. Abundant posterior epidural ligaments were observed between the posterior dura mater and the ligamentum flavum. Posterior epidural ligaments in the cervical spine have not been reported previously. The anterior displacement of the dura mater may be attributed to a lack of and/or insufficiency of the posterior epidural ligaments.

A quantitative serial sectioning technique and a video-imaging procedure were used to obtain precise (20-microns voxels, in a 5 mm x 6 mm x 7 mm test volume) digital images of lumbar vertebral cancellous bone specimens. Conventional stereological image analyses were performed on this data to determine multiplanar (bulk) and surface planar variations in cancellous structural properties. Based upon an error analysis of subgroups of the complete serial planar images, our findings suggest that, for a plane resolution of 20 microns, sectioning at an increment < or = 100 microns along an axis is necessary to obtain accurate data of bulk structural properties of cancellous bone. Planar structural variations obtained from the serial sections of cancellous bone revealed a high degree of complexity and heterogeneity of the bone architecture. Bone area centers deviated from the section centroid and showed a helical variation along the primary or superior--inferior loading axis of samples. In comparison with the base planes (perpendicular to the superior-inferior axis), the lateral planes (parallel to the superior-inferior axis) of spine samples showed smaller mean values of structural indices and a more oriented structure. This structural anisotropy may be related to the functional mechanical anisotropy of the samples.

The influence of load-bearing surface layers on Young's modulus was determined for cancellous bone and polyurethane foam specimens of three different heights cut from each material: 16, 9, and 5 mm for bone specimens (cross-sectional area A = 81 mm2) ranging in density from 0.04 to 0.32 g cm-3; 20, 10, and 5 mm for foam specimens (A = 100 mm2) ranging in density from 0.064 to 0.64 g cm-3. The compressive elastic modulus of the 5 mm bone specimens was significantly smaller (42%) than that of the 16 mm bone specimens. A similar change in elastic modulus was also observed for the foam specimens, but the height effect diminished in a relatively linear manner as the foam density increased. For a height change from 20 to 5 mm, the foam modulus difference ranged from a 41% decrease for the lowest density specimens (p = 0.064 g cm-3) to an insignificant change (< 1.8%) for the highest foam density specimens (p = 0.64 g cm-3). The specimen height effect on elastic modulus was hypothesized to result from a higher deformation (compliance) of the cellular materials in the load-bearing or contacting surface layer than in the bulk. A mathematical formula was derived to predict the variation in measured elastic modulus (E) caused by the contacting surface layer modulus (Ecs) to bulk modulus (Eb) ratio (Y = Ecs/Eb) and contacting surface layer height (hcs) to sample height (h) ratio (t = hcs/h): E/Eb = Y/[Y(1-t)+t]. Predicted differences in the measured modulus associated with graduated specimen heights were verified experimentally by regional strain measurements of the foam and bone samples using an optical microscope. The influence of free-surface layers was also determined for the foam specimens with cross-sectional areas 1.21 and 10 times the load-bearing area of a load platen, but the measured differences were small (< 10%) compared to that of the load-bearing surface layer influence. In future compressive mechanical testing of cellular materials, specimens < 10 mm in height should be avoided, particularly specimens with low bulk density or high porosity.

A procedure for averaging trunk dynamometric positions, velocities, and torques is described which enables identification and parameterization of kinematic movement patterns. This technique is accurate and presents the data in a very compact way, which is ideal for storage and analysis. It can be applied to many types of movement analyses. Application of the technique to the analysis of flexion-extension movement patterns in two low back pain patients is described., (Copyright © 1993. Published by Elsevier Ltd.)

Burst fractures of the lumbar spine that are located below the thoracolumbar junction present a challenge when operative management is indicated. Short-segment instrumentation offers the advantage of incorporating fewer motion segments in the fusion, but may not provide adequate long-term stabilization. The goal of this study was to assess the axial stiffness and torsional rigidity of several short-segment instrumentation procedures. Compressive axial stiffness and torsional rigidity were measured in six intact porcine lumbar spines (L1-L5). A corpectomy was performed to simulate a burst fracture injury and decompression. Posterior instrumentation, posterior instrumentation with an anterior strut (a wood block), and anterior instrumentation with an anterior strut one level above and one level below the fracture site were applied as treatment strategies. VSP plates (Acromed, Cleveland, OH) for posterior instrumentation and the Kaneda system (Acromed, Cleveland, OH) for anterior instrumentation were used. Load-displacement and torque-angle plots were generated and used to calculate 144 estimates of axial stiffness and 144 estimates of torsional rigidity for these constructs. These analyses showed that, in comparison with the intact spine, posterior instrumentation alone was an average of 76% less stiff axially, posterior instrumentation with an anterior strut was 3% more stiff (not significantly different from intact), and anterior instrumentation with an anterior strut was 15% more stiff. Posterior instrumentation alone was an average of 30% less rigid in torsion, posterior instrumentation with an anterior strut was 26% less rigid, and anterior instrumentation with an anterior strut was 24% less rigid than the intact spine.(ABSTRACT TRUNCATED AT 250 WORDS)

Because of their prevalence in elderly patients, the clinical symptoms of acquired lumbar spinal stenosis and degenerative joint disease of the lower extremity can often be present in the same patient. This study reports 14 patients who had diagnoses of both lower extremity degenerative disease and acquired lumbar spinal stenosis. Five of the 14 patients presented with concomitant symptoms, while 9 of 14 patients presented with clinical symptoms of spinal stenosis an average of 9.3 months following joint arthroplasty surgery. Comparison of the preoperative hip and knee scores between the concomitant and sequential groups demonstrated no differences. Seven of the nine patients in the sequential group required subsequent decompression for their spinal stenosis. Stenosis of the lumbar spine must be considered in patients who complain of continuing symptoms of neurogenic claudication in the postoperative period. In addition, these patients should be specifically counseled before their arthroplasty procedures that subsequent spinal surgery may be necessary.

This study examines changes in stiffness in a three-level spinal construct utilizing transpedicular Cotrel-Dubousset instrumentation. In addition, we evaluated the effect of adding offset laminar hooks at the same level as the superior transpedicular fixation. Porcine lumbar spines (L-1 to L-5) were tested as: (a) intact spine, (b) intact spine with instrumentation, and (c) instrumented spine after L-3 corpectomy. Instrumented constructs were tested with and without laminar hooks placed at the level of superior transpedicular fixation. Constructs were tested in modes of axial compression and torsion in a MTS materials testing machine. The fully instrumented intact spines demonstrated a 28.0% stiffness increase over the intact spines in torsion (p < 0.005) and a 23.1% increase in the mode of axial compression (p < 0.0002). There was no statistically significant difference in axial or torsional stiffness in the instrumented intact spine constructs when hooks were added. In the corpectomy model, addition of the laminar hooks increased stiffness in axial compression an average of 26.9% (p < 0.002) and in torsion an average of 28.1% (p < 0.0005). This increase in stiffness may aid in preventing the postoperative progression of kyphosis noted in studies utilizing similar constructs in clinical application for the treatment of lumbar burst fractures.

A nondestructive mechanical testing technique was used to assess midsagittal plane variations in the mechanical properties of human lumbar vertebral bone adjacent to the intervertebral discs of normal and degenerated spines. Bone mechanical properties were compared with midsagittal plane measurements of intervertebral disc (IVD) physical-chemical properties. In the normal spine a heterogeneous midsagittal plane distribution of subdiscal bone stiffness, IVD hydration and fixed charge density was found. Segments with degenerated discs exhibited a lower amount of midsagittal variation in subdiscal bone and IVD properties. A positive linear correlation between subdiscal bone stiffness and IVD fixed charge density was also found, suggesting that an interdependence of IVD and bone properties exists. These results support previous findings and are hypothesized to be an adaptive response to changes in the stress environment in the IVD.

A new technique incorporating a motion analysis system and a materials testing machine was used to investigate regional differences in the tensile mechanical properties of the lumbar spine anterior longitudinal ligament (ALL). Bone-ALL-bone specimens were prepared from young human cadaveric motion segments with no disc or bony pathology. Each specimen was distracted until failure at a constant crosshead displacement rate of 2.5 mm s-1 (approximately 1.0% strain per second). Strains were evaluated from digitized video recordings of markers attached to the ALL at 12 sites along its length and width, including the ligament substance and insertions. The 'overall' strain in the ligament was calculated from the outermost pairs of markers along the ligament length. The average tensile strength, the 'overall' tensile modulus and the 'overall' strain of the ALL at failure were 27.4 MPa (S.D. 5.9), 759 MPa (S.D. 336) and 4.95% (S.D. 1.51), respectively. Large and significant variations in the strains were present along the width and length of the ALL. Peak substance strains were over twofold greater than peak strains at the ligament insertion sites, whereas across the ligament width, peak strains in the outer portion of the ligament were over 40% greater than in the central region. Failure consistently occurred in the ligament mid-substance and ultimate strains at the ligament failure site averaged 12.1% (S.D. 2.3). These results indicate that the strains are highly nonuniform in the normal ALL.

Preemployment screening methods have been ineffective in predicting those at risk, and in curbing the impact of back problems in industry. Such methods have centered on individual physical factors (capacities and clinical examination). This study evaluates commonly used physical examination measures and simple historical data for its ability to predict individuals at risk for future back injury reporting in the aircraft industry. In this study, once simple historical information about previous pain treatment was known, information gained from physical factors added no significant predictive value.