Which factors prognosticate rotational instability following lumbar laminectomy?

Purpose

Reduced strength and stiffness of lumbar spinal motion segments following laminectomy may lead to instability. Factors that predict shear biomechanical properties of the lumbar spine were previously published. The purpose of the present study was to predict spinal torsion biomechanical properties with and without laminectomy from a total of 21 imaging parameters.

Method

Radiographs and MRI of ten human cadaveric lumbar spines (mean age 75.5, range 59–88 years) were obtained to quantify geometry and degeneration of the motion segments. Additionally, dual X-ray absorptiometry (DXA) scans were performed to measure bone mineral content and density. Facet-sparing lumbar laminectomy was performed either on L2 or L4. Spinal motion segments were dissected (L2–L3 and L4–L5) and tested in torsion, under 1,600 N axial compression. Torsion moment to failure (TMF), early torsion stiffness (ETS, at 20–40 % TMF) and late torsion stiffness (LTS, at 60–80 % TMF) were determined and bivariate correlations with all parameters were established. For dichotomized parameters, independent-sample t tests were used.

Results

Univariate analyses showed that a range of geometric characteristics and disc and bone quality parameters were associated with torsion biomechanical properties of lumbar segments. Multivariate models showed that ETS, LTS and TMF could be predicted for segments without laminectomy (r ² values 0.693, 0.610 and 0.452, respectively) and with laminectomy (r ² values 0.952, 0.871 and 0.932, respectively), with DXA-derived measures of bone quality and quantity as the main predictors.

Conclusions

Vertebral bone content and geometry, i.e. intervertebral disc width, frontal area and facet joint tropism, were found to be strong predictors of ETS, LTS and TMF following laminectomy, suggesting that these variables could predict the possible development of post-operative rotational instability following lumbar laminectomy. Proposed diagnostic parameters might aid surgical decision-making when deciding upon the use of instrumentation techniques.     

Which factors may effect urinary leakage following percutaneous nephrolithotomy?

Objective  

To evaluate the factors that may effect urinary leakage following percutaneous nephrolithotomy (PCNL).     

Does increasing age impact clinical and radiographic outcomes following lumbar spinal fusion?

Background ContextDespite the growing senior population within the United States, there is a lack of consensus regarding the safety and efficacy of performing lumbar spinal fusion for this population.PurposeTo evaluate the clinical and radiographic outcomes in different age cohorts following lumbar spinal fusion.Study DesignRetrospective cohort analysis.Patient SampleAnalysis of 1,184 patients who underwent posterolateral lumbar fusion from 2011 to 2018. Surgery was indicated after failure of conservative treatment to address radiculopathy and/or neurogenic claudication. Patients were excluded if they were under 18 years of age at the time of surgery, had a lumbar fracture, tumor, or infection, or had fusions involving the thoracic spine, high-grade spondylolisthesis, or concomitant deformity. Of the 1,184 patients, 850 patients were included. Patients were divided into three roughly equal groups for analysis: young (18–54 years), middle-aged (55–69 years), and senior (≥70 years).Outcome MeasuresVisual Analog Scale Back/Leg pain, and Oswestry Disability Index (ODI) were collected, and achievement of minimal clinically important difference was evaluated. Lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), and PI-LL difference were measured on radiographs. Rates of postoperative complications were analyzed.MethodsSeveral radiographic parameters were measured using plain radiographs obtained at preoperative, immediately postoperative (standing radiographs performed on postoperative day 1), and most recent follow-up visits. Preoperative and final patient-reported outcomes, along with demographic information, were obtained all patients. Binary outcome variables were compared between groups with multivariate logistic regression, and continuous outcome variables were compared using multivariate linear regression, with age 18 to 54 years used as the reference. Multivariate regressions were used to compare outcomes between cohorts while controlling baseline characteristics.ResultsA total of 850 patients were included; 330 young (38.80%), 317 middle-aged (37.30%), and 203 senior (23.90%). Seniors had higher postoperative length of stay compared to younger patients (p<.001). Younger patients had worse final ODI scores compared to middle-aged patients (p=.002). Seniors had higher rates of proximal ASD (p=.002) compared to young patients. There was no difference in achievement of minimal clinically important differences (MCID) between all three groups.ConclusionsSenior patients have significant improvement in patient-reported clinical outcomes, despite having greater comorbidities, and longer length of stay. However, given a general lack of achievement of MCID across all cohorts, these findings suggest the need for a critical re-evaluation of the role of lumbar spinal fusion in the management of patients with refractory radiculopathic and/or neurogenic claudication symptoms.     

Does pre-operative magnetic resonance imaging of the lumbar multifidus muscle predict clinical outcomes following lumbar spinal decompression for symptomatic spinal stenosis?

Purpose

To investigate whether pre-operative magnetic resonance imaging (MRI) of the lumbar multifidus muscle (LMM) would predict clinical outcomes following lumbar spinal decompression for symptomatic spinal stenosis.

Methods

A prospective cohort of patients with symptomatic neurogenic claudication, documented spinal stenosis on pre-operative MRI underwent spinal decompression. All subjects completed standardised outcome measures (Core Outcome Measures Index (COMI), Oswestry Disability Index (ODI v2.1) pre-operatively, 1 and 2 years post-surgery. Surgery was performed using a standardised lumbar spinous process osteotomy for access, followed by a decompression of the central canal, lateral recess and foraminal zones as indicated by the pre-operative MRI. Lumbar MRI scans were evaluated by two independent observers who assessed the axial CSA of the LMM bilaterally and the degree of muscle atrophy according to the Kader classification (2000). Changes in COMI and ODI scores at 1 and 2 years were investigated for statistically significant correlations with CSA of LMM and Kader grading. Statistical analyses utilised Student’s t test, kappa coefficient for inter-observer agreement and Bland–Altman Limits of Agreement (BALOA).

Results

66 patients (41 female) aged between 29 and 86 years underwent single-level decompression in 44, two-level decompression in 16 and three-level decompression in 6 cases. No significant correlation was observed between improvements in ODI and COMI relative to age, degree of stenosis, posterior fat thickness or psoas CSA. Those subjects with the greatest LMM atrophy relative to psoas CSA and L5 vertebral body area on pre-operative MRI had the least absolute improvement in both ODI and COMI scores (p = 0.006).

Conclusions

Reduced LMM CSA (<8.5 cm²) and muscle atrophy were associated with less favourable outcomes following lumbar spinal decompression. Pre-operative CSA of LMM appeared to be a more reliable predictor of post-operative clinical outcomes compared to the Kader Grading Score. This is the first study to investigate the prognostic value of pre-operative MRI appearance and CSA of LMM with respect to post-operative outcome following lumbar decompression surgery. Healthy pre-operative LMM is associated with better outcomes following lumbar spinal decompression.

     

Which traumatic spinal injury creates which degree of instability? A systematic quantitative review

BACKGROUND CONTEXTTraumatic spinal injuries often require surgical fixation. Specific three-dimensional degrees of instability after spinal injury, which represent criteria for optimum treatment concepts, however, are still not well investigated.PURPOSEThe aim of this review therefore was to summarize and quantify multiplanar instability increases due to spinal injury from experimental studies.STUDY DESIGN/SETTINGSystematic review.METHODSA systematic review of the literature was performed using keyword-based search on PubMed and Web of Science databases in order to detect all in vitro studies investigating the destabilizing effect of simulated and provoked traumatic injury in human spine specimens. Together with the experimental designs, the instability parameters range of motion, neutral zone and translation were extracted from the studies and evaluated regarding type and level of injury.RESULTSA total of 59 studies was included in this review, of which 43 studies investigated the effect of cervical spine injury. Range of motion increase, which was reported in 58 studies, was generally lower compared to the neutral zone increase, given in 37 studies, despite of injury type and level. Instability increases were highest in flexion/extension for most injury types, while axial rotation was predominantly affected after cervical unilateral dislocation injury and lateral bending solely after odontoid fracture. Whiplash injuries and wedge fractures were found to increase instability equally in all motion planes.CONCLUSIONSSpecific traumatic spinal injuries produce characteristic but complex three-dimensional degrees of instability, which depend on the type, level, and morphology of the injury. Future studies should expand research on the cervicothoracic, thoracic, and lumbosacral spine and should additionally investigate the destabilizing effects of the injury morphology as well as concomitant rib cage injuries in case of thoracic spinal injuries. Moreover, neutral zone and translation should be measured in addition to the range of motion, while mechanical injury simulation should be preferred to resection or transection of structures to ensure high comparability with the clinical situation.     

Can a machine learning model accurately predict patient resource utilization following lumbar spinal fusion?

BACKGROUND CONTEXTWith the increasing emphasis on value-based healthcare in Centers for Medicare and Medicaid Services reimbursement structures, bundled payment models have been adopted for many orthopedic procedures. Immense variability of patients across hospitals and providers makes these models potentially less viable in spine surgery. Machine-learning models have been shown reliable at predicting patient-specific outcomes following lumbar spine surgery and could, therefore, be applied to developing stratified bundled payment schemes.PURPOSE(1) Can a Naïve Bayes machine-learning model accurately predict inpatient payments, length of stay (LOS), and discharge disposition, following dorsal and lumbar fusion? (2) Can such a model then be used to develop a risk-stratified payment scheme?STUDY DESIGNA Naïve Bayes machine-learning model was constructed using an administrative database.PATIENT SAMPLEPatients undergoing dorsal and lumbar fusion for nondeformity indications from 2009 through 2016 were included. Preoperative inputs included age group, gender, ethnicity, race, type of admission, All Patients Refined (APR) risk of mortality, APR severity of illness, and Clinical Classifications Software diagnosis code.OUTCOME MEASURESPredicted resource utilization outcomes included LOS, discharge disposition, and total inpatient payments. Model validation was addressed via reliability, model output quality, and decision speed, based on application of training and validation sets. Risk-stratified payment models were developed according to APR risk of mortality and severity of illness.RESULTSA Naïve Bayes machine-learning algorithm with adaptive boosting demonstrated high reliability and area under the receiver-operating characteristics curve of 0.880, 0.941, and 0.906 for cost, LOS, and discharge disposition, respectively. Patients with increased risk of mortality or severity of illness incurred costs resulting in greater inpatient payments in a patient-specific tiered bundled payment, reflecting increased risk on institutions caring for these patients. We found that a large range in expected payments due to individuals’ preoperative comorbidities indicating an individualized risk-based model is warranted.CONCLUSIONSA Naïve Bayes machine-learning model was shown to have good-to-excellent reliability and responsiveness for cost, LOS, and discharge disposition. Based on APR risk of mortality and APR severity of illness, there was a significant difference in episode costs from lowest to highest risk strata. After using normalized model error to develop a risk-adjusted proposed payment plan, it was found that institutions incur significantly more financial risk in flat bundled payment models for patients with higher rates of comorbidities.     

Which factors determine subjective improvement following pelvic organ prolapse 1?year after surgery?

Introduction and hypothesis  

The factors influencing a patient’s subjective improvement 1 year after pelvic organ prolapse (POP) surgery were studied.     

Do silver-impregnated dressings limit infections after lumbar laminectomy with instrumented fusion?

BACKGROUND: Silver has been used to reduce infection for centuries. This study retrospectively analyzed whether the introduction of silver-impregnated dressing (SD; Silverlon, Argentum Medical, LLC, Lakefront, GA) rather than RD (iodine- or alcohol-based swab and dry 4 x 4 gauze) would reduce the risk of superficial or deep infection after lumbar laminectomy with instrumented fusion. METHODS: The first 128 patients had RD applied postoperatively, whereas the second population of 106 patients received SD. These dressings were used for the first 2 weeks after surgery. Other clinical, surgical, and outcome data were comparable for both groups. RESULTS: Three of 128 patients who underwent multilevel laminectomies with instrumented fusions receiving RD developed deep postoperative wound infections (culture confirmed). All were successfully managed with 6 weeks of postoperative antibiotics, and none required secondary surgery. In addition, 11 patients who had RD developed superficial infection/irritation; 7 required oral antibiotics (7-10 days) alone, whereas 4 were referred to plastic surgeons for superficial wound revision. Alternatively, there were neither deep nor superficial wound infections/irritation among the 106 patients who received SD. Although the number of cases in each series was small, there appeared to be a positive trend toward a reduction in postoperative wound infection using SD. CONCLUSIONS: Use of SD for application on lumbar wounds after laminectomies with instrumented fusions appeared to limit/reduce the incidence of both postoperative deep and superficial wound infections.     

What are the reliable radiological indicators of lumbar segmental instability?

We examined the reliability of radiological findings in predicting segmental instability in 112 patients (56 men, 56 women) with a mean age of 66.5 years (27 to 84) who had degenerative disease of the lumbar spine. They underwent intra-operative biomechanical evaluation using a new measurement system. Biomechanical instability was defined as a segment with a neutral zone > 2 mm/N. Risk factor analysis to predict instability was performed on radiographs (range of segmental movement, disc height), MRI (Thompson grade, Modic type), and on the axial CT appearance of the facet (type, opening, vacuum and the presence of osteophytes, subchondral erosion, cysts and sclerosis) using multivariate logistic regression analysis with a forward stepwise procedure. The facet type was classified as sagittally orientated, coronally orientated, anisotropic or wrapped. Stepwise multivariate regression analysis revealed that facet opening was the strongest predictor for instability (odds ratio 5.022, p = 0.009) followed by spondylolisthesis, MRI grade and subchondral sclerosis. Forward stepwise multivariate logistic regression indicated that spondylolisthesis, MRI grade, facet opening and subchondral sclerosis of the facet were risk factors. Symptoms evaluated by the Short-Form 36 and visual analogue scale showed that patients with an unstable segment were in significantly more pain than those without. Furthermore, the surgical procedures determined using the intra-operative measurement system were effective, suggesting that segmental instability influences the symptoms of lumbar degenerative disease.     

Meningitis following spinal anaesthesia - a coincidental infection?

We report a case of meningitis developing a number of days after a subarachnoid block for caesarean section. No organisms were grown but the clinical picture was suggestive of bacterial meningitis, the clinical course of which had been modified by the administration of antibiotics for presumed wound infection. The possible aetiology is discussed.     

Which procedure is better for lumbar interbody fusion: anterior lumbar interbody fusion or transforaminal lumbar interbody fusion?

Introduction

Both anterior lumbar interbody fusion (ALIF) and transforaminal lumbar interbody fusion (TLIF) surgeries are performed to obtain a solid fusion to treat lumbar spondylosis. This systematic review investigated whether surgical complications, nonfusion rate, radiographic outcome, and clinical outcome of ALIF were significantly different from those of TLIF.

Method

A computerized search of the electronic databases MEDLINE was conducted. Only therapeutic studies with a prospective or retrospective comparative design were considered for inclusion in the present investigation. Two reviewers independently extracted relevant data from each included study. Statistical comparisons were made when appropriate.

Results

Nine studies were determined to be appropriate for the systematic review, and all studies were retrospective comparative studies. Blood loss and operative time in ALIF was greater than in TLIF. There was no significant difference in the complication rate between ALIF and TLIF. The restoration of disc height, segmental lordosis, and whole lumbar lordosis in ALIF was superior to TLIF. However, clinical outcomes in ALIF were similar with TLIF, and there was no significant difference in nonfusion rate between the two techniques. Costs of ALIF were greater than those of TLIF.

Conclusion

Clinical outcomes and nonfusion rate in ALIF were similar to TLIF. However, the restoration of disc height, segmental lordosis, and whole lumbar lordosis in ALIF were superior to those in TLIF, while blood loss, operative time, and costs in ALIF were greater than in TLIF.     

Back pain and disability after lumbar laminectomy: is there a relationship to muscle retraction?

OBJECTIVE: Preliminary studies have suggested that prolonged retraction of the paraspinal muscle during spinal surgery may produce ischemic damage. We report the continuous measurement of intramuscular pressure (IMP) during decompressive lumbar laminectomy and its relationship to subsequent back pain and disability. METHODS: Twenty patients undergoing two-level decompressive lumbar laminectomy for lumbar canal stenosis were recruited. Back pain and disability were assessed by use of the Visual Analog Score (VAS), Oswestry Disability Index (ODI), and Short-Form 36 (SF-36) Health Survey. During surgery, IMP was recorded continuously from the multifidus muscle by use of a pressure transducer. The intramuscular perfusion pressure (IPP) was estimated as the difference between the patient's mean arterial pressure and IMP. RESULTS: Two muscle retractors were used: the Norfolk and Norwich (n = 10) and the McCulloch (n = 10). The mean duration of deep muscle retraction was 62.7 +/- 8 minutes (range, 19-133 min). On application of deep muscle retraction, there was a rapid and sustained increase in IMP (P < 0.001), and overall, the calculated mean IPP approached 0 mm Hg or less during this period (P < 0.001). On release of deep muscle retraction, there was a rapid decrease in IMP to preoperative levels. The IPP was greater with the Norfolk and Norwich than the McCulloch retractor (P < 0.001). Compared with preoperative values, there was a decrease in ODI (P < 0.001) and VAS for back pain (P < 0.001) at discharge and 4 to 6 weeks and 6 months after surgery. In addition, there was a decrease in SF-36 scores at 6 months compared with preoperative values (P < 0.001). Total duration of muscle retraction greater than 60 minutes was associated with worse VAS scores for back pain and ODI and SF-36 scores for disability at 6 months after surgery (P < 0.05). There was no relationship between the VAS, ODI, and SF-36 scores and other parameters measured, including the mean IPP, retractor type, operating surgeon, and wound length. CONCLUSION: The McCulloch retractor generates a higher IMP than the Norfolk and Norwich retractor. However, postoperative improvement in VAS, ODI, and SF-36 scores in these patients was associated with a shorter duration of muscle retraction and not the degree of IMP or IPP generated. In this respect, periodic relaxation of the paraspinal muscle retractors during surgery to allow muscle perfusion may help to reduce postoperative back pain and disability.     

Fully endoscopic lumbar spinal surgery: Is it time to change?

Spinal surgery is becoming safer and progressively less invasive with advances in optical and instrument technology. The amount of decompression achievable with endoscopic approaches is now comparable to open approaches with the advantage of much less tissue trauma. This review aims at examining the status of endoscopic approaches in lumbar decompressive surgery.