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The California Hospital Outcomes Project: using administrative data to compare hospital performance.

BACKGROUND: The California Hospital Outcomes Project was created by an act of the state legislature in 1991. The California Office of Statewide Health Planning and Development (OSHPD) publishes annual reports on risk-adjusted hospital outcomes for medical, surgical, and obstetric patients. These outcomes indicators were chosen: in-hospital mortality within 30 days (acute myocardial infarction [AMI]), reported post-operative complications (diskectomy, delivery), post-operative length of stay (diskectomy), and readmission within 6 weeks (delivery). Project reports are based on discharge abstracts submitted by hospitals and edited by OSHPD. For each outcome, two risk adjustment models were used to estimate expected and risk-adjusted hospital outcome rates, along with p values representing the likelihood that the observed number of adverse outcomes occurred by chance. RESULTS: The first hospital outcomes report was distributed to hospitals in June 1993 and released to the public in December 1993. The total number of hospitals labeled as "better than expected" was 14 for AMI, 5 for cervical diskectomy, and 25 for lumbar diskectomy. The second hospital outcomes report was distributed to hospitals in June 1995. RESPONSE AND CONCLUSIONS: Letters submitted for 168 hospitals in response to the 1993 report demonstrated that hospitals had studied and used project results to evaluate their coding practices and quality of care. Media coverage of the 1993 report was balanced but sometimes critical of OSHPD's failure to identify "worse" hospitals. In response to providers' concerns, OSHPD has undertaken a validation study to explore whether differences in coding, unmeasured risk factors, or processes of care explain the reported differences in risk-adjusted outcome rates.

California↗

[Microsurgery of lumbar disc prolapse. Superior results of microsurgery as compared to standard- and percutaneous procedures (review of literature)].

In a meta-analysis of 69 prospective and retrospective studies, we investigated the value of various surgical techniques in the treatment of lumbar disk herniations. This analysis includes standard diskectomy (5080 patients from nine series), microdiskectomy (5354/23), and comparison of both techniques (2494/10) and furthermore chemonucleolysis (2729/16), laser therapy (881/3), percutaneous nucleotomy (3506/18), comparisons of percutaneous techniques (942/5) with microdiskectomies (561/5) and standard diskectomies (1020/6). Outcomes were rated according to Macnab's criteria: I "excellent", II "good", III "improved", IV "same as before", V "worse", I/II "markedly improved", III "partially improved", IV/V "not improved", I-III "successful", and IV/V "unsuccessful". Results after microdiskectomy were "successful" more often (90% vs. 95%), "good/excellent" more often (82% vs. 73%), and patients left the hospital sooner than with standard diskectomy. Recurrence rates were comparable (4%). Results of both open techniques were clearly superior to those from any type of percutaneous treatment: chemonucleolysis und laser therapy were "successful" in 69% and 70% of cases respectively, with recurrence rates of 17% and 18%, endoscopic nucleotomy was "successful" in 84% of cases, and recurrence rate was 14%. Please ask the author for the reference database.

Diskectomy↗

Surgical vs nonoperative treatment for lumbar disk herniation: the Spine Patient Outcomes Research Trial (SPORT) observational cohort.

CONTEXT: For patients with lumbar disk herniation, the Spine Patient Outcomes Research Trial (SPORT) randomized trial intent-to-treat analysis showed small but not statistically significant differences in favor of diskectomy compared with usual care. However, the large numbers of patients who crossed over between assigned groups precluded any conclusions about the comparative effectiveness of operative therapy vs usual care. OBJECTIVE: To compare the treatment effects of diskectomy and usual care. DESIGN, SETTING, AND PATIENTS: Prospective observational cohort of surgical candidates with imaging-confirmed lumbar intervertebral disk herniation who were treated at 13 spine clinics in 11 US states and who met the SPORT eligibility criteria but declined randomization between March 2000 and March 2003. INTERVENTIONS: Standard open diskectomy vs usual nonoperative care. MAIN OUTCOME MEASURES: Changes from baseline in the Medical Outcomes Study Short-Form Health Survey (SF-36) bodily pain and physical function scales and the modified Oswestry Disability Index (American Academy of Orthopaedic Surgeons/MODEMS version). RESULTS: Of the 743 patients enrolled in the observational cohort, 528 patients received surgery and 191 received usual nonoperative care. At 3 months, patients who chose surgery had greater improvement in the primary outcome measures of bodily pain (mean change: surgery, 40.9 vs nonoperative care, 26.0; treatment effect, 14.8; 95% confidence interval, 10.8-18.9), physical function (mean change: surgery, 40.7 vs nonoperative care, 25.3; treatment effect, 15.4; 95% CI, 11.6-19.2), and Oswestry Disability Index (mean change: surgery, -36.1 vs nonoperative care, -20.9; treatment effect, -15.2; 95% CI, -18.5. to -11.8). These differences narrowed somewhat at 2 years: bodily pain (mean change: surgery, 42.6 vs nonoperative care, 32.4; treatment effect, 10.2; 95% CI, 5.9-14.5), physical function (mean change: surgery, 43.9 vs nonoperavtive care 31.9; treatment effect, 12.0; 95% CI; 7.9-16.1), and Oswestry Disability Index (mean change: surgery -37.6 vs nonoperative care -24.2; treatment effect, -13.4; 95% CI, -17.0 to -9.7). CONCLUSIONS: Patients with persistent sciatica from lumbar disk herniation improved in both operated and usual care groups. Those who chose operative intervention reported greater improvements than patients who elected nonoperative care. However, nonrandomized comparisons of self-reported outcomes are subject to potential confounding and must be interpreted cautiously. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00000410.

Adult↗

Technical note: unilateral posterior resection of cervical disc and spondylostenosis with contralateral fusion for instability.

BACKGROUND: Posterior cervical unilateral diskectomy and decompression for stenosis with instability may be successfully stabilized with contralateral diskectomy and fusion. METHODS: A 49-year-old male with a left-sided C8 radiculopathy had dynamic X-ray, MR, and CT studies that documented an old anterior diskectomy and fusion at the C5-C6 level, and a new left-sided foraminal disc herniation at the C7-T1 level with instability, accompanied by C6-T1 spondylostenosis. Following left-sided C6-T1 laminectomies with excision of C7-T1 disc, a contralateral right-sided C5-T2 fusion was performed with fibula strut allograft wired to the spinous processes using titanium cable and iliac crest autograft. RESULTS: X-ray and 2D CT studies performed 3 and 6 months postoperatively confirmed adequate unilateral decompression of stenosis with disc removal and contralateral fusion. Within three weeks of surgery, the patient had no residual neurological deficit. Three years later, he remained intact, and X-ray studies continued to demonstrate spinal stability. CONCLUSIONS: A unilateral C7-T1 disc herniation with instability accompanied by C6-T1 spondylostenosis were successfully managed with unilateral decompression and disc excision followed by contralateral fusion.

Cervical Vertebrae↗

Single versus multiple dose antibiotic prophylaxis in lumbar disc surgery.

STUDY DESIGN: Retrospective review. OBJECTIVES: To determine the efficacy of preoperative antibiotics alone in preventing wound infections following lumbar diskectomy. SUMMARY OF BACKGROUND DATA: It is well documented that antibiotics given perioperatively reduce the rate of postoperative wound infections in lumbar disc surgery. At our institution, the current protocol for patients undergoing lumbar diskectomy is a single preoperative antibiotic dose. This study was conducted to compare the rate of postoperative wound infection incurred for single versus multiple perioperative antibiotic doses. It was hypothesized that no significant difference in infection rates would be identified. METHODS: This retrospective chart review compared the rates of postoperative wound infections incurred when single versus multiple perioperative antibiotic doses were given to patients having lumbar laminotomy for herniated discs. The procedures were performed between 1993 and March 1999. There were 434 patients in the multiple dose group and 201 in the single dose group. The multiple dose group received one preoperative and at least three postoperative doses of antibiotics. The single dose group received one preoperative dose of antibiotics. A postoperative infection was deemed present by either clinical diagnosis or culture results. The medical records were reviewed for 6 weeks after surgery for all patients. RESULTS: There were 5 out of 435 (1.15%) infections in the multiple dose group and 3 out of 201 (1.49%) in the single dose group. Statistical analysis showed no significant difference between the two study groups. CONCLUSION: These results support the use of single preoperative dose of antibiotics in lumbar disc surgery. This is relevant as many lumbar diskectomy patients are candidates for early hospital discharge. At our institution, no increased risk of infection occurred for the single dose group.

Adult↗

Use of a bioabsorbable anterior cervical plate in the treatment of cervical degenerative and traumatic disk disruption.

Anterior cervical diskectomy and fusion is a widely accepted treatment for anterior management of degenerative or traumatic instability of the cervical spine. To reduce or eliminate complications such as implant migration and failure, imaging degradation, and fusion stress shielding that are occasionally associated with spinal instrumentation, attention has been given to the use of bioresorbable anterior cervical plating devices. This paper is a preliminary report of a retrospective series in which a resorbable mesh and screw system (OS Reconstructive Mesh, MacroPore Biosurgery Inc, San Diego, Calif) was used for graft containment in single-level anterior cervical diskectomy and fusion. A review of patient charts and imaging studies was conducted to determine functional outcome, fusion success, and potential soft-tissue reaction to implant resorption. Nine patients with a diagnosis of cervical degenerative disk disease or traumatic disk disruption were treated between October 2001 and March 2002. Follow-up averaged 206 days. Eight patients were found to have an excellent result, one patient had a good result, and no patients had a satisfactory or poor result. At the time of follow-up, 77% of patients (7/9) were found to have a radiographically solid fusion. The two patients without a solid fusion were only on average 8 months out from their fusion procedure and manifested no symptoms related to fusion nonhealing. No significant soft-tissue reaction was noted clinically or radiographically in any of the patients. The results of this preliminary study indicate that bioresorbable anterior cervical plating for single-level anterior cervical diskectomy and fusion is both safe and effective.

Absorbable Implants↗

[Surgical treatment of multileveled diskogenic compression of the cervical spine and its roots].

The authors studied 54 patients with diskogenic compression of the cervical spine and nervous roots, who had undergone interventions including diskectomy, anterior cervical spondylodesis, and plate fixation. The purpose of the study was to provide rationale for choice of a surgical treatment for multileveled diskogenic compression of the cervical spine. Twenty-seven patients with multileveled lesion underwent diskectomy at 2-3 levels with and without vertebral body resection. Preference was given to the mini-invasive technique involving diskectomy, anterior cervical spondylodesis, by using osteoinductor blocks, and plate fixation. A control group consisted of 27 patients with one-leveled lesion who had undergone conventional surgical treatment. 0.5-3-year follow-ups showed positive results in 84% in the study group and in 89% in the control one. Fusion was successful in 89 and 96% in the study and control groups, respectively. The rate of complications and the level of successful professional and social rehabilitation were similar in both groups.

Adult↗

Surgical treatment of temporomandibular joints in patients with chronic arthritic disease: preoperative findings and one-year follow-up.

Twenty-nine temporomandibular joints (TMJs) in 19 patients with chronic arthritic disease were surgically treated. Nine patients had rheumatoid arthritis (including two with juvenile type), six had ankylosing spondylitis and four had psoriatic arthropathy. Using a preauricular approach, diskectomies with synovectomies were performed in 23 joints (14 patients) with chronic arthritic abnormalities. Diskectomies without synovectomies were performed in six joints (five patients), which proved to have internal derangements unrelated to their chronic arthritic disease. Joints with chronic arthritis showed considerable variation in inflammatory reactions, but were characterized by increased vascularization, synovial proliferation to the articulating surfaces and mostly pannus formation and bone resorption. A response in pain relief was seen in 85% of the patients three months postoperatively and in 79% of the patients 12 months postoperatively, indicating that diskectomy with synovectomy may be favorable in patients with severe TMJ problems due to involvement of chronic arthritic disease.

Adolescent↗

Risk factors and initial surgical failures of TMJ arthrotomy and arthroplasty: a four to nine year evaluation of 303 surgical procedures.

Studies exist which support the efficacy of TM joint arthrotomy, arthroplasty and arthroscopic surgery. Few, if any, studies have evaluated failures of arthroplasty and/or diskectomy and specific risk factors that might invite initial surgical failure. This paper is a retrospective review of 210 patients operated with arthrotomy/arthroplasty for painful and dysfunctional TM joint derangement. There were 303 surgical procedures evaluated over a follow-up period of 4-9 years. Patient ages ranged from 16-72 years. There was no age correlation seen with degree of joint derangement. All cases were operated by one surgeon. There were no cases of alloplastic materials in this group of patients. There were no cases of autograph such as auricular cartilage for dermal grafting or other disc substitution materials. Operations consisted of capsular arthroplasty in Wilkes' stage II, III, and IV. Diskectomy was performed in Wilkes' stages IV and V. Comparisons are made among staged groups and operation performed. Two hundred seventy-three of 303 operated joints met the criteria for surgical success for a technical success rate of 90.1%. Potential risk factors of missing molar teeth, preoperative joint collapse, and skeletal malocclusion were evaluated. The frequency of their presence in successful and non-successful surgical outcomes is noted. Patients with imaging confirmed osteoporosis were evaluated as group with potential systemic disease or a result of systemic disease that may influence long term surgical outcome. Predictable preoperative risk factors that may influence initial surgical outcome do appear to be significant in long term success. There were 30 cases of failure to evaluate. It is concluded that reconstructive arthroplasty is a stage specific operation with excellent results in Wilkes' stage II and good results in stage III derangement. Attempted arthroplasty failed significantly (50%) in a small number of attempts in stage IV cases. However, diskectomy was successful in stage IV and V cases. Osteoporosis may be the most significant risk factor and the presence of risk factors studied may jeopardize initial surgical outcomes. Preoperative staging of joint derangement is strongly suggested and evaluation of risk factors may necessitate selection of specific initial surgical procedures that minimize the influence of concomitant risk factors to long term success.

Adolescent↗

Surgical treatment of temporomandibular joint luxation.

Eminectomy with or without diskectomy was performed in 19 patients with temporomandibular joint luxation. Three of them were long-standing luxations (duration between three months and one year). The remaining 16 patients had recurrent luxations. The follow-up period was three years. No complications such as infection or permanent palsy of the facial nerve occurred. However, transient palsy of the temporal branch of the facial nerve, which resolved within three months was seen in 4 patients (21%). After treatment two patients had recurrent luxations. In the remaining 17 patients, two developed painful clicking of one TMJ, requiring additional surgery (one patient had arthroscopic lysis and lavage and the other one diskectomy). If these two are also regarded as unsuccessful cases, the overall long-term success rate was 79%. A comparison of the subgroups who underwent eminectomy alone and eminectomy with diskectomy showed that all unsuccessful cases occurred in the former group.

Adult↗

On surgical intervention in the temporomandibular joint.

The aim of this thesis was to evaluate the indications for and the results of temporomandibular joint (TMJ) surgery in patients with long-standing severe orofacial pain and dysfunction as well as in patients with fractures of the condylar neck. The patients with long-standing pain and dysfunction had had symptoms for a mean time of 4 years, had been treated conservatively for a mean time of 2.5 years, and had undergone numerous conservative treatment methods without improvement except for a minor increase in mouth opening capacity. The indications for surgery were strict; only 1% or less of all the patients referred to the departments with a diagnosis of temporomandibular disorder (TMD) were prescribed surgery, which was considered to be the only remaining option. The TMJ surgery reduced pain, sleeping problems, and analgesic consumption and improved mouth opening capacity. The procedure showed low morbidity except for a facial nerve disturbance in three patients. Postoperatively, the bite force was observed to be normalised, and the radiographic examination showed moderate to severe osteoarthrotic changes. These changes, though extensive, were considered to be the normal outcome of diskectomy and without clinical significance, even though they resembled degenerative joint disease. In study V, surgery was performed on patients with a clear diagnosis of anterior disk displacement (ADD) with or without reduction. The preoperative pain and mouth opening capacity were markedly improved as well as other subjective symptoms. Although surgical morbidity was low, some radiographic changes were clearly detectable. In agreement with earlier reports, patients with a distinct diagnosis of ADD with or without reduction were clearly helped by diskectomy. In cases of ADD with or without reduction, it can be concluded that unsuccessful conservative treatment should not exceed 3-6 months but be discontinued in favour of the documented advantages of surgery in these cases. Patients with ankylosis should be treated surgically without delay. Unclear diagnoses such as arthralgia and osteoarthrosis with symptoms should be excluded from surgery unless overlapping muscular hyperactivity has been excluded as a major cause of the patients problem. Diskectomy is a useful surgical procedure for patients with severe long-standing TMD. It was shown in study VI that patients with dislocated fractures of the condylar neck can be successfully treated with open surgical reduction when the dislocation is large and associated with symptoms and limited function. When cognitive-behavioural profiles were measured psychometrically in study VII, a dysfunctional profile was more common in patients with myofascial pain and pain with an obscure origin than in other patients diagnosed with TMD. The dysfunctional profile was also common in patients in whom treatment of a conservative or surgical nature had failed. Among TMD patients with disk displacement, adaptive copers were most common in successfully diskectomized patients and least common in patients about to undergo invasive treatment.

Adaptation, Psychological↗

Surgical vs nonoperative treatment for lumbar disk herniation: the Spine Patient Outcomes Research Trial (SPORT): a randomized trial.

CONTEXT: Lumbar diskectomy is the most common surgical procedure performed for back and leg symptoms in US patients, but the efficacy of the procedure relative to nonoperative care remains controversial. OBJECTIVE: To assess the efficacy of surgery for lumbar intervertebral disk herniation. DESIGN, SETTING, AND PATIENTS: The Spine Patient Outcomes Research Trial, a randomized clinical trial enrolling patients between March 2000 and November 2004 from 13 multidisciplinary spine clinics in 11 US states. Patients were 501 surgical candidates (mean age, 42 years; 42% women) with imaging-confirmed lumbar intervertebral disk herniation and persistent signs and symptoms of radiculopathy for at least 6 weeks. INTERVENTIONS: Standard open diskectomy vs nonoperative treatment individualized to the patient. MAIN OUTCOME MEASURES: Primary outcomes were changes from baseline for the Medical Outcomes Study 36-item Short-Form Health Survey bodily pain and physical function scales and the modified Oswestry Disability Index (American Academy of Orthopaedic Surgeons MODEMS version) at 6 weeks, 3 months, 6 months, and 1 and 2 years from enrollment. Secondary outcomes included sciatica severity as measured by the Sciatica Bothersomeness Index, satisfaction with symptoms, self-reported improvement, and employment status. RESULTS: Adherence to assigned treatment was limited: 50% of patients assigned to surgery received surgery within 3 months of enrollment, while 30% of those assigned to nonoperative treatment received surgery in the same period. Intent-to-treat analyses demonstrated substantial improvements for all primary and secondary outcomes in both treatment groups. Between-group differences in improvements were consistently in favor of surgery for all periods but were small and not statistically significant for the primary outcomes. CONCLUSIONS: Patients in both the surgery and the nonoperative treatment groups improved substantially over a 2-year period. Because of the large numbers of patients who crossed over in both directions, conclusions about the superiority or equivalence of the treatments are not warranted based on the intent-to-treat analysis. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00000410.

Adult↗

The relation between expectations and outcomes in surgery for sciatica.

OBJECTIVE: To describe the expectations that patients and their physicians have for outcomes after surgical treatment for sciatica and to examine the associations between expectations and outcomes. DESIGN: Prospective cohort study. SETTING/PATIENTS: We recruited 273 patients, from the offices of orthopedic surgeons, neurosurgeons, and occupational medicine physicians in Maine, who had diskectomy for sciatica. MEASUREMENTS AND MAIN RESULTS: Patients' and physicians' expectations were measured before surgery. Satisfaction with care and changes in symptoms and functional status were measured 12 months after surgery. More patients who expected a shorter recovery tJgie after surgery were "delighted," "pleased," or "mostly satisfied" with their outcomes 12 months after surgery than patients who expected a longer recovery tJgie (odds ratio [OR] 2.2; 95% confidence interval [CI] 1.1, 4.4). Also, more patients who preferred surgery after learning that sciatica could get better without surgery had good symptom scores 12 months after surgery than patients who did not prefer surgery (OR 2.9; 95% CI 1.2, 7.0). When physicians predicted a "great deal of Jgiprovement" after surgery, 39% of patients were not satisfied with their outcomes and 25% said their symptoms had not Jgiproved. CONCLUSIONS: More patients with favorable expectations about surgery had good outcomes than patients with unfavorable expectations. Physicians' expectations were overly optJgiistic. Patient expectations appear to be Jgiportant predictors of outcomes, and eliciting them may help physicians identify patients more likely to benefit from diskectomy for sciatica.

Adult↗

Can administrative data be used to compare postoperative complication rates across hospitals?

BACKGROUND: Several quality assessment systems use administrative data to identify postoperative complications, with uncertain validity. OBJECTIVES: To determine how accurately postoperative complications are reported in administrative data, whether accuracy varies systematically across hospitals, and whether serious complications are more consistently reported. DESIGN: Retrospective cohort. SUBJECTS: Nine hundred ninety-one randomly sampled adults who underwent elective lumbar diskectomies at 30 nonfederal acute care hospitals in California in 1990 to 1991. Hospitals with especially low or high risk-adjusted complication rates, and patients who experienced complications, were over sampled. MEASURES: Postoperative complications were specified by reviewing medical literature and consulting clinical experts; each complication was mapped to ICD-9-CM. Hospital-reported complications were compared with our independent recoding of the same records. RESULTS: The weighted sensitivity, specificity, and positive and negative predictive values for reported complications were 35%, 98%, 82%, and 84%, respectively. The weighted sensitivity was 30% for serious, 40% for minor, and 10% for questionable complications. It varied from 21% among hospitals with fewer complications than expected to 45% among hospitals with more complications than expected. Only reoperation, bacteremia/sepsis, postoperative infection, and deep vein thrombosis were reported with at least 60% sensitivity. Half of the difference in risk-adjusted complication rates between low and high outlier hospitals was attributable to reporting variation. CONCLUSIONS: ICD-9-CM complications were underreported among diskectomy patients, especially at hospitals with low risk-adjusted complication rates. The validity of using coded complications to compare provider performance is questionable, even with careful efforts to identify serious events, although these results must be confirmed using more recent data.

California↗

Minimally invasive techniques for the treatment of intervertebral disk herniation.

Hemilaminectomy with diskectomy, the original surgical option to address intervertebral disk herniation, was superseded by open microdiskectomy, a less invasive technique recognized as the surgical benchmark with which minimally invasive spine surgery techniques have been compared as they have been developed. These minimally invasive surgical techniques for patients with herniated nucleus pulposus and radiculopathy include laser disk decompression, arthroscopic microdiskectomy, laparoscopic techniques, foraminal endoscopy, and microendoscopic diskectomy. Each has its own complications and requires a long learning curve to develop familiarity with the technique. Patient selection, and especially disk morphology, are the most important factors in choice of technique. The optimal candidate has a previously untreated single-level herniation with limited migration or sequestration of free fragments.

Decompression, Surgical↗

Chiropractic care of a patient with vertebral subluxations and unsuccessful surgery of the cervical spine.

OBJECTIVE: The chiropractic care of a patient with vertebral subluxations, neck pain, and cervical radiculopathy after a cervical diskectomy is described. CLINICAL FEATURES: A 55-year-old man had neck pain and left upper extremity radiculopathy after unsuccessful cervical spine surgery. INTERVENTION AND OUTCOME: Contact-specific, high-velocity, low-amplitude adjustments (i.e., Gonstead technique) were applied to sites of vertebral subluxations. Rehabilitation exercises were also used as adjunct to care. The patient reported a decrease in neck pain and left arm pain after chiropractic intervention. The patient also demonstrated a marked increase in range of motion (ROM) of the left glenohumeral articulation. CONCLUSION: The chiropractic care of a patient with neck pain and left upper extremity radiculopathy after cervical diskectomy is presented. Marked resolution of the patient's symptoms was obtained concomitant with a reduction in subluxation findings at multiple levels despite the complicating history of an unsuccessful cervical spine surgery. This is the first report in the indexed literature of chiropractic care after an unsuccessful cervical spine surgery.

Accidents, Traffic↗

[Comparative study of vertebral body stress distribution following insertion of artificial lumbar intervertebral disc].

OBJECTIVE: To study vertebral body stress distribution of normal disc, post-Diskectomy and artificial disk respectively by 3-D finite element methods, and to explore artificial intervertebral disk insertion impact on stress distribution of vertebral body. METHODS: Models of normal disk, post-Diskectomy, artificial disk and L(4 - 5) motion segment were established by using finite element software MSC. MARK, then vertebral body stress was analyzed through model of L(4 - 5) motion segment respectively. RESULTS: The vertebral body's stress was the smallest after insertion of artificial intervertebral disk (AID), and its stress distributed equally. But the stress under post-discectomy was bigger than the normal disc's in all the motion state. On the other hand, the stress distribution state of the post-discectomy changed while the spine were in different motion state, during the spine flexion, the stress in the anterior of vertebral body was the biggest; While extension, in the posterior and in right flexion state, the biggest stress was in the right. While vertical compression and rotation, the stress distributed equally. CONCLUSION: The results illustrate that the vertebral body's stress is the smallest after insertion of AID in 3 groups of all motion state, and its stress distributes equally. But the level of vertebral body stress increases after discectomy comparing with the normal group. In generally, it is much more reasonable that the disc is reconstructed with AID because of the biomechanical effect on vertebral body made by AID insertion.

Diskectomy↗

Biomechanics of the thoracolumbar vertebral column of dogs during lateral bending.

OBJECTIVE: To study biomechanical characteristics of the normal and surgically altered canine thoracolumbar vertebral column to determine the effects of surgery and trauma on lateral stability. ANIMALS: The T13-L1 vertebral motion units of 48 mixed-breed dogs were dissected free of surrounding musculature and prepared for biomechanical testing by cross-pinning the vertebral bodies and mounting in polymethylmethacrylate. PROCEDURE: Normal and surgically altered spinal specimens were subjected to lateral bending. The mean slope of the bending moment versus angular displacement curve and the load to failure were compared between treatment groups and significance was determined by the method of least squares (P < 0.05). Specimens were surgically altered by facetectomy, lateral fenestration, diskectomy, and combinations of these procedures. Each specimen was subjected to lateral bending to failure at a rate of 2.5 cm/min in a swing arm bending jig designed to simulate 4-point bending and subject the specimen to pure bending. RESULTS: Only specimens undergoing diskectomy had a significant decrease in slope and load at failure. Unilateral and bilateral facetectomies and fenestration induced a nonsignificant decrease in stiffness, compared with control specimens. CONCLUSIONS: Fenestrations and facetectomies do not appear to increase the risk of injury to the canine thora-columbar spinal cord during lateral bending. CLINICAL RELEVANCE: Fenestrations and facetectomies, as used in routine laminectomies, may be performed without concern for significant destabilization of the spine in lateral bending; however, it is possible that thoracolumbar spinal fractures involving only the vertebral body may significantly destabilize the spine in all modes of bending.

Animals↗