Demineralized cortical fibers are associated with a low pseudarthrosis rate in patients undergoing surgery for adult spinal deformity without three-column osteotomy

Introduction

Following surgical treatment for adult spinal deformity (ASD) there is an increased risk of revision surgery due to mechanical failure or pseudarthrosis. Demineralized cortical fibers (DCF) were introduced at our institution aiming to reduce the risk of pseudarthrosis after ASD surgery.

Research question

We wanted to investigate the effect of DCF on postoperative pseudarthrosis compared with allogenic bone graft in ASD surgery without three-column osteotomies (3CO).

Materials & Methods

All patients undergoing ASD surgery between January 1, 2010 to June 31, 2020 were included in this interventional study with historical controls. Patients with current or previous 3CO were excluded. Before February 1, 2017, patients undergoing surgery received auto- and allogenic bone graft (non-DCF group) whilst patients after received DCF in addition to autologous bone graft (DCF group). Patients were followed for at least two years. The primary outcome was radiographic or CT-verified postoperative pseudarthrosis requiring revision surgery.

Results

We included 50 patients in the DCF group and 85 patients in the non-DCF group for final analysis. Pseudarthrosis requiring revision surgery at two-year follow-up occurred in seven (14%) patients in the DCF group compared with 28 (33%) patients in the non-DCF group (p ​= ​0.016). The difference was statistically significant, corresponding to a relative risk of 0.43 (95%CI: 0.21-0.94) in favor of the DCF group.

Conclusion

We assessed the use of DCF in patients undergoing ASD surgery without 3CO. Our results suggest that the use of DCF was associated with a considerable decreased risk of postoperative pseudarthrosis requiring revision surgery.

Use of demineralized cortical fibers is associated with reduced risk of pseudarthrosis after pedicle subtraction osteotomy for adult spinal deformity

PURPOSE

To assess the effect of demineralized cortical fibers (DCF) on postoperative pseudarthrosis requiring revision surgery in patients undergoing pedicle subtraction osteotomy (PSO) for adult spinal deformity (ASD).

METHODS

The use of DCF was introduced across all procedures in 2017 and subsequent patients undergoing PSO surgery were prospectively and consecutively registered. Following sample-size estimation, a retrospective cohort was also registered undergoing the same procedure immediately prior to the implementation of DCF. The non-DCF group underwent surgery with ABG. Minimum follow-up was 2 years in both groups. The main outcome was postoperative pseudarthrosis, either CT-verified or verified intraoperatively during revision surgery due to rod breakage and assessed using Kaplan-Meier survival analyses.

RESULTS

A total of 48 patients were included in the DCF group and 76 in the non-DCF group. The DCF group had more frequently undergone previous spine surgery (60% vs 36%) and had shorter follow-up (32 ± 2 vs 40 ± 7 months). Pseudarthrosis occurred in 7 (15%) patients in the DCF group and 31 (41%) in the non-DCF group, corresponding to a relative risk increase of 2.6 (95%CI 1.3-2.4, P < 0.01). 1-KM survival analyses, taking time to event into account and thus the difference in follow-up, also showed increased pseudarthrosis in the non-DCF group (log-rank P = 0.022). Similarly, multivariate logistic regression adjusted for age, instrumented levels and sacral fusion was also with significantly increased odds of pseudarthrosis in the non-DCF group (OR: 4.3, 95%CI: 1.7-11.3, P < 0.01).

CONCLUSION

We found considerable and significant reductions in pseudarthrosis following PSO surgery with DCF compared to non-DCF.

LEVEL OF EVIDENCE

III.

[Spinefractures - diagnosis and treatment]

Acute onset back pain is a common reason for referral to primary health care or emergency departments. In this review, the different spine fracture types are highlighted, and a treatment algorithm is proposed. CT is the modality of choice when a spine fracture is suspected. MRI should be performed when disc or ligamentous lesions are suspected or in patients with known ankylosis or diffuse idiopathic skeletal hyperostosis. Treatment is mainly conservative with bracing, but unstable fractures and patients with neurological deficits should be treated surgically.

Reducing revision rates following Pedicle Subtraction Osteotomy surgery: a single-center experience of trends over 7 years in patients with Adult Spinal Deformity

STUDY DESIGN

This is a single-center, retrospective study.

OBJECTIVE

To assess if implemented changes to clinical practice have reduced mechanical complications following pedicle subtraction osteotomy (PSO) surgery. Adult spinal deformity (ASD) is increasing in prevalence with concurrent increasing demands for surgical treatment. The most extensive technique, PSO, allows for major correction of rigid deformities. However, surgery-related complications have been reported in rates up to 77% and especially mechanical complications occur at unsatisfactory frequencies.

METHODS

We retrospectively included all patients undergoing PSO for ASD between 2010 and 2016. Changes to clinical practice were introduced continuously in the study period, including rigorous patient selection; inter-disciplinary conferences; implant-material; number of surgeons; surgeon experience; and perioperative standardized protocols for pain, neuromonitoring and blood-loss management. Postoperative complications were recorded in the 2-year follow-up period. Competing risk survival analysis was used to assess cumulative incidence of revision surgery due to mechanical complications. The Mann-Kendall test was used for analysis of trends.

RESULTS

We included 185 patients undergoing PSO. The level of PSO changed over the study period (P < 0.01) with L3 being the most common level in 2010 compared to L4 in 2016. Both preoperative and surgical corrections of sagittal vertical axis were larger towards the end of the study period. The 2-year revision rate due to mechanical failure steadily declined over the study period from 52% in 2010 to 14% for patients treated in 2016, although without statistically significant trend (P = 0.072). In addition, rates of mechanical complications steadily declined over the study period and significant decreasing trends were observed in time trend analyses of overall complications, major complications and rod breakage.

CONCLUSIONS

We observed decreased risks of revision surgery due to mechanical complications following PSO in patients with ASD over a 7-year period. We attribute these improvements to advancements in patient selection, surgical planning and techniques, surgeon experience and more standardized perioperative care.

LEVEL OF EVIDENCE

III.

Minimal Access vs. Open Spine Surgery in Patients With Metastatic Spinal Cord Compression - A One-Center Randomized Controlled Trial

BACKGROUND/AIM

We conducted a randomized controlled trial to investigate whether minimally access spine surgery (MASS) is less morbid than open surgery (OS) in patients with metastatic spinal cord compression (MSCC).

PATIENTS AND METHODS

A total of 49 MSCC patients were included in the trial. The outcome measures were bleeding (L), operation time (min), re-operations and prolonged wound healing.

RESULTS

The median age was 67 years (range=42-85 years) and 40% were men. The peri-operative blood loss in the MASS-group was significantly lower than that in the OS-group; 0.175L vs. 0.500L, (p=0.002). The median operation time for MASS was 142 min (range=72-203 min) vs. 103 (range=59-435 min) for OS (p=0.001). There was no significant difference between the two groups concerning revision surgery or delayed wound healing.

CONCLUSION

The MASS technique in MSCC patients is associated with less blood loss, but a longer operation time when compared to the OS technique.

Spinopelvic Parameters Depending on the Angulation of the Sacral End Plate Are Less Reproducible Than Other Spinopelvic Parameters in Adult Spinal Deformity Patients

STUDY DESIGN

Reproducibility study.

OBJECTIVES

To report the agreement and reliability for commonly used sagittal plane measurements.

SUMMARY OF BACKGROUND DATA

Spinopelvic parameters and sagittal vertical axis (SVA) are commonly used parameters for preoperative planning and postoperative evaluation of patients with adult spinal deformity (ASD). Previous reproducibility studies have focused on describing the reliability using intraclass correlation coefficients (ICCs), thus quantifying the methods' ability to distinguish between individuals. To our knowledge, no previous study in patients with ASD has reported the measurement error in terms of limits of agreement. The current study aimed to report the agreement and reliability for measurements of pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and SVA in ASD patients.

METHODS

In a consecutive, one-center cohort of 64 patients referred for ASD evaluation, a blinded test-retest study was performed. Reliability was assessed using ICCs, whereas 95% limits of agreement (LOAs) were used to quantify agreement.

RESULTS

We found "excellent" (ICC > 0.9) results in all analyses of reliability except for interrater PI, which was classified as "good" (ICC = 0.89). However, considerable interrater measurement error was observed for parameters depending on the angulation of the sacral end plate (95% LOA of ±11° and ±14° for SS and PI, respectively) compared with ±5° for PT and ±7 mm for SVA, which depends on the location of the sacral end plate. Intrarater agreement was only slightly better.

CONCLUSION

These are to our knowledge the first estimates of measurement error for sagittal spinopelvic parameters in ASD patients. Despite near excellent ICCs, we found considerable measurement error for parameters depending on the angulation rather than the location of the sacral end plate.

LEVEL OF EVIDENCE

Level II.

Ability of the Global Alignment and Proportion Score to Predict Mechanical Failure Following Adult Spinal Deformity Surgery-Validation in 149 Patients With Two-Year Follow-up

STUDY DESIGN

Retrospective analysis of prospectively collected data.

OBJECTIVES

To validate the Global Alignment and Proportion (GAP) score in a single-center cohort of adult spinal deformity (ASD) patients.

SUMMARY OF BACKGROUND DATA

Surgical treatment for ASD is associated with a high risk of mechanical failure and consequent revision surgery. To improve prediction of mechanical complications, the GAP score was developed with promising results. Development was based on the assumption that not all patients would benefit from the same fixed radiographic targets as pelvic incidence is an individual, morphological parameter that greatly influences the sagittal curves of the spine.

METHODS

In a validation study of the GAP score, patients undergoing ASD surgery with four or more levels of instrumentation were consecutively included at a tertiary spine unit. Patients were followed for a minimum of two years. Pre- and postoperative GAP score and categories were calculated for all patients, and the association with mechanical failure and revision surgery was analyzed.

RESULTS

A total of 149 patients with a mean age of 57.4 years were included. Overall, the rates of mechanical failure and revision surgery were 51% and 35% respectively. The area under the curve (AUC) using receiver operating characteristic was classified as "no or low discriminatory power" for the GAP score in predicting either outcome (AUC = 0.50 and 0.49, respectively). Similarly, there were no significant associations between GAP categories and the occurrence of mechanical failure or revision surgery when using Cochran-Armitage test of trend (p = .28 for mechanical failure and p = .58 for revision surgery).

CONCLUSIONS

In a consecutive series of surgically treated ASD patients, we found no significant association between postoperative GAP score and mechanical failure or revision surgery. Despite minor limitations in similarities to the original study cohort, further validation studies or adjustments to the original scoring system are proposed.

LEVEL OF EVIDENCE

Level II.

Moderate Interrater and Substantial Intrarater Reproducibility of the Roussouly Classification System in Patients With Adult Spinal Deformity

STUDY DESIGN

Reproducibility study of a classification system.

OBJECTIVES

To provide the inter- and intrarater reproducibility of the Roussouly Classification System in a single-center prospective cohort of patients referred for Adult Spinal Deformity.

SUMMARY OF BACKGROUND DATA

The Roussouly Classification System was developed to describe the variation in sagittal spine shape in normal individuals. A recent study suggests that patients' spine types could influence the outcome following spinal surgery. The utility of a classification system depends largely on its reproducibility.

METHODS

Sixty-four consecutive patients were included in a blinded test-retest setting using digital radiographs. All ratings were performed by four spine surgeons with different levels of experience. There was a 14-day interval between the two reading sessions. Inter- and intrarater reproducibility was calculated using Fleiss Kappa and crude agreement percentages.

RESULTS

We found moderate interrater (κ = 0.60) and substantial intrarater (κ = 0.68) reproducibility. All 4 raters agreed on the Roussouly type in 47% of the cases. The most experienced rater had significantly higher intrarater reliability compared to the least experienced rater (κ = 0.57 vs 0.78). The two most experienced raters also had the highest crude agreement percentage (75%); however, they also had a significant difference in distribution of spine types.

CONCLUSION

The current study presents moderate interrater and substantial intrarater reliability of the Roussouly Classification System. These findings are acceptable and comparable to previous results of reproducibility for a classification system in patients with Adult Spinal Deformity. Additional studies are requested to validate these findings as well as to further investigate the impact of the classification system on outcome following surgery.

National clinical guidelines for non-surgical treatment of patients with recent onset neck pain or cervical radiculopathy

PURPOSE

To summarise recommendations about 21 selected non-surgical interventions for recent onset (<12 weeks) non-specific neck pain (NP) and cervical radiculopathy (CR) based on two guidelines from the Danish Health Authority.

METHODS

Two multidisciplinary working groups formulated recommendations based on the GRADE approach.

RESULTS

Twelve recommendations were based on evidence and nine on consensus. Management should include information about prognosis, warning signs, and advise to remain active. For treatment, guidelines suggest different types of supervised exercise and manual therapy; combinations of exercise and manual therapy before medicine for NP; acupuncture for NP but not CR; traction for CR; and oral NSAID (oral or topical) and Tramadol after careful consideration for NP and CR.

CONCLUSION

Recommendations are based on low-quality evidence or on consensus, but are well aligned with recommendations from guidelines from North America. The working groups recommend intensifying research relating to all aspects of management of NP and CR.

The semi-automatic nucleator

The nucleator is a well-established manual stereological method of estimating mean cell volume from observations on random cell transects through reference points of the cells. In this paper, we present an automated version of the nucleator that uses automatic segmentation of the boundaries of the cell transects. An expert supervises the process. If the segmentation is judged to be satisfactory, an estimate of the cell volume is calculated automatically on the basis of the whole cell transect. In the remaining cases, the expert intervenes and uses the classical nucleator. The resulting estimator is called the semi-automatic nucleator. In this paper, we study the statistical properties of the semi-automatic nucleator. Formulae for the bias and mean square error are derived. The semi-automatic nucleator may have a small bias but will still in most cases be more efficient than the classical nucleator. Procedures for estimating bias and mean square error from a pilot study are provided. The application of the semi-automatic nucleator is illustrated in a study of somatostatin positive inhibitory interneurons which were genetically labelled with green fluorescent protein (GFP). The cells were sampled with an optical disector. The centre of mass in a central cell transect was used as reference point. It is found in this study that the number of cells needed for obtaining, for instance, a 5% precision of the estimate of mean cell volume is 150 and 189 for the semi-automatic and the classical nucleator, respectively. Taking into account that the time spent analysing one cell is shorter for the semi-automatic nucleator than for the classical nucleator, the semi-automatic nucleator is superior to the classical nucleator.

Elemental composition of airborne dust in the Shale Shaker House during an offshore drilling operation

During 2 days of an offshore drilling operation in the North Sea, 16 airborne dust samples from the atmosphere of the Shale Shaker House were collected onto filters. During this operation, drilling mud composed of a water slurry of barite (BaSO4) together with minor amounts of additives, among them chrome lignosulphonate and chrome lignite, was circulated between the borehole and the Shale Shaker House. The concentration of airborne dust in the atmosphere was determined and the elemental composition of the particles analysed by both PIXE (proton-induced X-ray emission) and ICP-MS (inductively coupled plasma-mass spectrometry). The total amount of dust collected varied from 0.04 to 1.41 mg m-3 with barium (Ba) as the single most abundant element. The open shale shakers turned out to be the major cause of generation of dust from the solid components of the drilling mud.

Non-hydrolysed and hydrolysed soy protein. A human immunological study

Daily consumption of soy protein has increased during recent years. Twelve healthy subjects and 12 atopic patients were given 30 g non-hydrolysed soy protein (NHS) or 30 g hydrolysed soy protein (HS) daily during a 3-month period. There were no changes in the following immunological parameters: IgE with specificity for NHS or HS, IgG with specificity for NHS, crossed radioimmunoelectrophoresis with NHS and skin prick test using NHS or HS. Hypertrophy of the pancreas in rats exposed to excessive peroral intake of soy flour has been reported. In our study the size of the pancreas was measured before dosing began and at the end of the study by means of ultrasound. No change in size was shown. Daily intake of 30 g NHS and 30 g HS gave rise to gastrointestinal discomfort, while 15 g of both soy protein preparations were usually accepted.