An age and sex matched study on the effect of obesity on the functional outcomes and complication rates in patients with adult spinal deformity undergoing primary multi-level thoracolumbar spinal fusion.

Background: The objective of this study was to determine the effect of obesity on the functional outcomes and complication rates of patients with adult spinal deformity (ASD) undergoing multi-level thoracolumbar fusion. Methods: An age and sex matched comparison of functional outcomes [Numeric Rating Scale (NRS) back and leg scores, Core Outcome Measurement Index (COMI) back scores, Scoliosis Research Society 22 (SRS22) satisfaction and total scores, Short Form 36 (SF36) general health scores, Physical Component Score (PCS), Mental Component Score (MCS), Oswestry Disability Index (ODI) (including all domains)] at 6 months, 1, 2, 3 and 4 years and the complication rates at final follow-up between obese [body mass index (BMI) >30] and normal BMI (18.5-24.9) patients undergoing more than 3 levels of thoracolumbar fusion with a minimum 2-year follow-up. Patients who had undergone any previous spinal surgery were excluded. Results: Thirty patients were included in each arm of the study. Baseline demographics, including the number of levels fused, were similar between the groups. Estimated blood loss (EBL) was higher in obese patients (1,916 vs. 1,099 mL, P=0.001), but operative time was similar (282 vs. 320 min, P=0.351). The functional outcomes and satisfaction scores were consistently poorer in the obese group at all time-points, but their satisfaction scores were similar. Obese patients had a higher complication rate (OR 3.05, P=0.038) predominantly due to dural tears and nerve root injuries, but a similar reoperation rate. Conclusions: In patients with ASD undergoing multi-level thoracolumbar fusion, obesity results in a higher blood loss, poorer sagittal correction, poorer post-operative functional scores and higher complication rates than patients with a normal BMI. However, obesity does not affect operative times, length of hospital stay or reoperation rates. Furthermore, patients with obesity have similar post-operative satisfaction scores to patients with normal BMIs.

Clinical Performance and Concurrent Validity of the Adult Spinal Deformity Surgical Decision-making Score.

STUDY DESIGN: Multicenter, retrospective study. OBJECTIVE: The aim of this study was to examine the performance and concurrent validity of the adult spinal deformity surgical decision-making (ASD-SDM) score compared to decision-making factors in the ASD population. SUMMARY OF BACKGROUND DATA: The ASD-SDM score, which has been recently proposed, is a scoring system to guide the selection of treatment modality for the ASD population. To secure the justification for its clinical use, it is necessary to verify its clinical performance and concurrent validity. METHODS: A multicenter prospective ASD database was retrospectively reviewed. The data were analyzed separately in younger (≤40 years) and older (≥41 years) age groups. The discriminating capacity of the ASD-SDM score in cases who selected surgical and nonsurgical management was compared using area under the receiver operator characteristic curves (AUROC). Concurrent validity was examined using Spearman correlation coefficients, comparing factors that are reported to be associated with the decision-making process for ASD, including baseline symptomatology, health-related quality of life measures, and the severity of radiographic spinal deformity. RESULTS: There were 338 patients (mean age: 26.6 years; 80.8% female; 129 surgical and 209 nonsurgical) in the younger age group and 750 patients (mean age: 63.5 years; 84.3% female; 410 surgical and 340 nonsurgical) in the older age group. In both younger and older patients, the ASD-SDM score showed a significantly higher performance for discriminating the surgical and nonsurgical cases (AUROC: 0.767, standard error [SE]: 0.026, P < 0.001, 95% confidence interval [CI]: 0.712-0.813; AUROC: 0.781, SE: 0.017, P < 0.001, 95% CI: 0.747-0.812, respectively) compared to the decision-making factors analyzed. In addition, the ASD-SDM showed significant correlations with multiple decision-making factors. CONCLUSION: The ASD-SDM score alone can effectively grade the indication for surgical management whilst considering multiple decision-making factors. LEVEL OF EVIDENCE: 3.

Adult spinal deformity surgical decision-making score. Part 2: development and validation of a scoring system to guide the selection of treatment modalities for patients above 40 years with adult spinal deformity.

PURPOSE: We aimed to develop and internally validate a scoring system, the adult spinal deformity surgical decision-making (ASD-SDM) score, to guide the decision-making process for ASD patients aged above 40 years. METHODS: A multicentre prospective ASD database was retrospectively reviewed. The scoring system was developed using data from a derivation set and was internally validated in a validation set. The performance of the ASD-SDM score for predicting surgical management was assessed using the area under the receiver operating characteristic curve (AUC). RESULTS: A total of 702 patients were included for analysis in the present study. The scoring system developed based on 562 patients, ranging from 0 to 12 points, included five parameters: leg pain scored by the numerical rating scale; pain and self-image domains in the Scoliosis Research Society-22 score; coronal Cobb angle; and relative spinopelvic alignment. Surgical indication was graded as low (score 0 to 4), moderate (score 5 to 7), and high (score 8 to 12) groups. In the validation set of 140 patients, the AUC for predicting surgical management according to the ASD-SDM score was 0.797 (standard error = 0.037, P < 0.001, 95% confidence interval = 0.714 to 0.861), and in the low, moderate, and high surgical indication groups, 23.7%, 43.5%, and 80.4% of the patients, respectively, were treated surgically. CONCLUSIONS: The ASD-SDM score demonstrated reliability, with higher scores indicating a higher probability of surgery. This index could aid in the selection of surgery for ASD patients in clinical settings. These slides can be retrieved under Electronic Supplementary Material.

Adult spinal deformity surgical decision-making score : Part 1: development and validation of a scoring system to guide the selection of treatment modalities for patients below 40 years with adult spinal deformity.

PURPOSE: We aimed to develop and internally validate a simple scoring system: the adult spinal deformity (ASD) surgical decision-making (ASD-SDM) score, which is specific to the decision-making process for ASD patients aged below 40 years. METHODS: A multicentre prospective ASD database was retrospectively reviewed. The scoring system was developed using data from a derivation cohort and was internally validated in a validation cohort. The accuracy of the ASD-SDM score was assessed using the area under the receiver operating characteristic curve (AUC). RESULTS: A total of 316 patients were randomly divided into derivation (253 patients, 80%) and validation (63 patients, 20%) cohorts. A 10-point scoring system was created from four variables: self-image score in the Scoliosis Research Society-22 score, coronal Cobb angle, pelvic incidence minus lumbar lordosis mismatch, and relative spinopelvic alignment, and the surgical indication was graded into low (score 0-4), moderate (score 5-7), and high (score 8-10) surgical indication groups. In the validation cohort, the AUC for selecting surgical management according to the ASD-SDM score was 0.789 (SE 0.057, P < 0.001, 95% CI 0.655-0.880). The percentage of patients treated surgically were 21.1%, 55.0%, and 80.0% in the low, moderate, and high surgical indication groups, respectively. CONCLUSIONS: The ASD-SDM score, to the best of our knowledge, is the first algorithm to guide the decision-making process for the ASD population and could be one of the indices for aiding the selection of treatment for ASD. These slides can be retrieved under Electronic Supplementary Material.

Cerebral ischaemia following anterior upper thoracic spinal surgery utilizing a partial manubrial resection.

PURPOSE: Firstly, to describe two cases of cerebral ischaemia complicating anterior upper thoracic spinal surgery and define the likely cause of this complication. Secondly, to describe preventative measures and the effect these have had in reducing this complication within our institution. METHODS: Firstly, a review of two cases of cerebral ischaemia complicating anterior upper thoracic spinal surgery utilizing a partial manubrial resection. Secondly, cadaveric dissections of the carotid arteries to determine the effect of neck positioning and aortic arch retraction during a simulated procedure. Thirdly, a retrospective review of 65 consecutive cases undergoing this procedure and assessment of the rate of this complication before and after the adoption of preventative measures. RESULTS: Two cases of carotid artery territory cerebral ischaemia, without radiographic evidence of carotid or cardiac pathology were identified in 50 consecutive cases prior to the implementation of preventative measures. These patients revealed fluctuating hemodynamic instability after placement of the inferior retractor. Cadaveric dissection reveals significant carotid artery traction particularly with neck extension. Since the adoption of preventative measures, no cases of cerebral ischaemia have been encountered. CONCLUSIONS: Cerebral ischaemia is a potential complication of anterior upper thoracic spinal surgery requiring retraction of the aortic arch. This most likely occurs from carotid stenosis due to aortic retraction and therefore, may be reduced by positioning the patient with neck flexion. Continuous non-invasive monitoring of cerebral saturation, as well as actively monitoring for hemodynamic instability and reduced carotid pulsation after retractor placement, allows for early detection of this complication. If detected, perfusion can be easily restored by reducing the retraction of aortic arch.

Anterior Bone Loss in Cervical Disc Arthroplasty.

STUDY DESIGN: Retrospective, longitudinal observational study. PURPOSE: To describe the natural history of anterior bone loss (ABL) in cervical disc arthroplasty (CDA) and introduce a classification system for its assessment. OVERVIEW OF LITERATURE: ABL has recently been recognized as a complication of CDA, but its cause and clinical effects remain unknown. METHODS: Patients with non-keeled CDA (146) were retrospectively reviewed. X-rays were examined at 6 weeks, 3, 6, 9, 12, 18, and 24 months, and annually thereafter for a minimum of 5 years. These were compared with the initial postoperative X-rays to determine the ABL. Visual Analog Scale pain scores were recorded at 3 months and 5 years. Neck Disability Index was recorded at postoperative 5 years. The natural history was determined and a classification system was introduced. RESULTS: Complete radiological assessment was available for 114 patients with 156 cervical disc replacements (CDRs) and 309 endplates (average age, 45.3 years; minimum, 28 years; maximum, 65 years; 57% females). ABL occurred in 57.1% of CDRs (45.5% mild, 8.3% moderate, and 3.2% severe) and commenced within 3 months of the operation and followed a benign course, with improvement in the bone stock after initial bone resorption. There was no relationship between ABL degree and pain or functional outcome, and no implants were revised. CONCLUSIONS: ABL is common (57.1%). It occurs at an early stage (within 3 months) and typically follows a non-progressive natural history with stable radiographic features after the first year. Most ABL cases are mild, but severe ABL occurs in approximately 3% of CDAs. ABL does not affect the patients' clinical outcome or the requirement for revision surgery. Surgeons should thus treat patients undergoing CDA considering ABL.

The effect of increasing body mass index on the pain and function of patients with adult spinal deformity.

BACKGROUND: Both adult spinal deformity (ASD) and obesity are growing concerns internationally. This study therefore aims to determine the effect of increasing body mass index (BMI) on the pain and function of patients with ASD. METHODS: A retrospective review of prospectively collected data from a multicentre European database was undertaken. Initially a univariate analysis was performed on the effect of BMI on the initial presentation of functional scores in patients with ASD. The functional scores included the Numerical Rating Scale (NRS) back and leg score, Core Outcome Measures Index (COMI) back score, SRS22 total score, Short Form 36 (SF-36) [general health, physical component score (PCS) and mental component score (MCS)] and Oswestry Disability Index (ODI) score (including all domains). Subsequently a multivariate analysis controlling for age, sex, comorbidities, employment status, smoking status and radiological parameters [coronal cobb, coronal balance, sagittal balance, global tilt, and pelvic incidence minus lumbar lordosis (PI - LL) mismatch] was performed. RESULTS: A total of 1,004 patients were included in this study (166 male, 838 female). On univariate analysis a statistically significant (P<0.05) moderate correlation between NRS leg pain, ODI (walking, standing, sex life, social life and total score), SF-36 (physical component), sagittal balance, global tilt and age were recognised (P<0.05). A statistically significant low correlation was identified for all other outcomes, except coronal balance (P=0.640). On multivariate analysis BMI remained significantly related to all functional outcomes except ODI-pain and ODI-travelling (P>0.05). CONCLUSIONS: Increasing BMI has a significant adverse effect on the pain and functioning of patients with ASD. Clinicians should recognise this association and treat patients accordingly.

Risk factors for anterior bone loss in cervical disc arthroplasty.

OBJECTIVE The objective of this study was to identify the risk factors of anterior bone loss (ABL) in cervical disc arthroplasty (CDA) and the subsequent effect of this phenomenon. METHODS The authors performed a retrospective radiological review of 185 patients with a minimum 5-year follow-up after CDA (using Bryan, Discocerv, Mobi-C, or Baguera C). Postoperative radiographs were examined and compared to the initial postoperative films to determine the percentage of ABL. The relationship of ABL to potential risk factors was analyzed. RESULTS Complete radiological assessment was available in 145 patients with 193 CDRs and 383 endplates (average age 45 years, range 25-65 years, 54% women). ABL was identified in 63.7% of CDRs (48.7% mild, 11.9% moderate, 3.1% severe). Age (p = 0.770), sex (p = 0.200), postoperative alignment (p = 0.330), midflexion point (p = 0.509), maximal flexion (p = 0.080), and extension (p = 0.717) did not relate to ABL. There was no significant difference in the rate of severe ABL between implants. Multilevel surgery conferred an increased risk of any and severe ABL (p = 0.013 for both). The upper endplate, defined as superior to the CDA, was more commonly involved (p = 0.008), but there was no significant difference whether the endplate was between or not between implants (p = 0.226). The development of ABL did not affect the long-term range of movement (ROM) of the CDA, but did increase the overall risk of autofusion. ABL was not associated with pain or functional deficits. No patients required a reoperation or revision of their implant during the course of this study, and there were no cases of progressive ABL beyond the first year. CONCLUSIONS ABL is common in all implant types assessed, although most is mild. Age, sex, postoperative alignment, ROM, and midflexion point do not relate to this phenomenon. However, the greater the number of levels operated, the higher the risk of developing ABL. The development of ABL has no long-term effect on the mechanical functioning of the disc or necessity for revision surgery, although it may increase the rate of autofusion.

Decision-making factors in the treatment of adult spinal deformity.

PURPOSE: We aimed to elucidate the factors for the decision-making process in the treatment of adult spinal deformity (ASD), including sagittal parameters, that impact health-related quality of life (HRQOL). METHODS: A multicenter prospective ASD database was retrospectively reviewed. The demographic data, HRQOL, and radiographic measures were analyzed using multivariate analyses in younger (≤ 50 years) and older (> 50 years) age groups. RESULTS: This study included 414 patients (134 surgical and 280 nonsurgical; mean age 30.7 years) in the younger age group and 575 patients (323 surgical and 252 nonsurgical; mean age 65.8 years) in the older age group. Worse HRQOL measures drove surgical treatment, both in younger and older patients. The SRS-22 self-image score was the most differentiating domain, both in the younger and older age groups, and an additional significant factor in the older age group was pain and disability. Coronal deformity drove surgical treatment for the younger age group; however, older surgical patients were less likely to have coronal malalignment. Sagittal parameters were associated with the decision-making process. Greater pelvic incidence minus lumbar lordosis mismatch in the younger age group and smaller lumbar lordosis index in the older age group were most correlated with the decision to undergo surgery. CONCLUSIONS: Aside from the HRQOL measures and coronal deformity, sagittal parameters were identified as significant factors for the decision-making process in the ASD population, and the lack of lumbar lordosis in relation to pelvic incidence was a strong driver to pursue surgical treatment. These slides can be retrieved under Electronic Supplementary Material.

Spondylolisthesis adjacent to a cervical disc arthroplasty does not increase the risk of adjacent level degeneration.

PURPOSE: To understand whether a spondylolisthesis in the sub-axial spine cranial to a cervical disc arthroplasty (CDA) construes a risk of adjacent level disease (ALD). METHODS: A retrospective review of 164 patients with a minimum 5-year follow-up of a cervical disc arthroplasty was performed. Multi-level surgeries, including hybrid procedures, were included. Multiple implant types were included. The two inter-vertebral discs (IVD) cranial of the CDA were monitored for evidence of radiologic degeneration using the Kettler criteria. RESULTS: The rate of ALD in CDA found in this series was 17.8%, with most affecting the immediately adjacent IVD (27.4 and 7.6%, respectively p = 0.000). Pre-operative mild spondylolisthesis adjacent to a planned CDA was not found to be a risk factor for ALD within 5 years. Those with a degenerative spondylolisthesis are at higher risk of ALD (33%) than those with a non-degenerative cause for their spondylolisthesis (11%). Post-operative CDA alignment, ROM or induced spondylolisthesis do not affect the rate of ALD in those with an adjacent spondylolisthesis. Patients with ALD experience significantly worse 5-year pain and functional outcomes than those unaffected by ALD. CONCLUSIONS: A pre-operatively identified mild spondylolisthesis in the sub-axial spine cranially adjacent to a planned CDA is not a risk factor for ALD within 5 years. These slides can be retrieved under Electronic Supplementary Material.

Outcomes of the Bryan cervical disc replacement: fifteen year follow-up.

BACKGROUND: The CTDR is a technique that treats cervical disc degenerative disease. Initial shorter-term studies showed good clinical and radiological results. PURPOSE: To assess the clinical and radiological results of Bryan cervical disc replacement (Medtronic Sofamor Danek Inc., Memphis, TN) at 15-year follow-up. RESULTS: This prospective study included 20 patients who underwent 22 CTDR, comprising a single-level procedure in 14 patients and two-level procedures in six patients. The mean follow-up period was 15.5 years. The mean age at the intervention was 46.2 years (range: 26-65 years). Two patients needed re-operation for recurrence of symptoms. According to Odom's criteria, 80.0% (16 of 20 patients) had excellent outcomes, VAS for neck pain was 2.6 (0-10), for shoulder/arm pain it was 1.8 (0-7), and NDI at the final follow up was 14.9. The SF-12 PCS was 46.1, and SF-12 MCS was 51.9. Mobility was maintained in 15 of the 22 (68.2%) operated segments, range of motion (ROM) of prostheses were 9° ± 3.9° (range 4-15°). The prostheses were positioned in kyphosis in 14 of 22 levels (63.6%). There was a positive correlation between the kyphosis of the prosthesis and the occurrence of heterotopic ossification (HO), and their grade (ρ = 0.36, CI 95%[-0.68; 0.07]). HO had developed at 12 of the 22 levels (54.5%) and upper adjacent segment degeneration in 11 of 18 of patients (64.7%). All these results were not significantly different to outcomes at 8 years follow-up. CONCLUSION: In a cohort of 20 patients with 15-year clinical and radiological follow-up, the Bryan CTDR has demonstrated a sustained clinical improvement and implant mobility over time, despite a moderate progression of degenerative processes at the prosthetic and adjacent levels.

Identifying the superior and inferior gluteal arteries during a sacrectomy via a posterior approach.

BACKGROUND: Identifying the gluteal vessels during a posterior sacrectomy can be challenging. This study defines anatomical landmarks that can be used to approximate the location of the superior and inferior gluteal arteries (SGA and IGA) during a posterior sacrectomy. METHODS: Cadaveric dissection of six fresh adult pelvises to determine the location of the SGA and IGA in relation to the posterior-inferior aspect of the sacroiliac joint (PISIJ), lateral sacral margin and sacrococcygeal joint (SCJ). RESULTS: The anatomical landmarks are easily palpable. The position of the SGA to the PISIJ is relatively constant as it is tethered by a posterior branch of the artery, which runs inferior to the PISIJ. The IGA position is also relatively constant below the mid-point of the PISIJ and SCJ. The vessels are separated from the sacrospinous/sacrotuberous ligament complex (SSTL) in the perisacral region and as a result an anatomical plane exists anterior to the SSTL, which affords protection of the vessels during SSTL transection. The distance between the vessels and the SSTL increases the more medial the dissection. CONCLUSIONS: The described anatomical landmarks can be used to predict the location of the SGA and IGA during posterior sacrectomy. An anatomical plane exists anterior to the SSTL, which provides protection to the vessels during SSTL transection. Furthermore, the distance between the vessels and the SSTL increases the more medial the dissection, thus, resection of the SSTL as close to the lateral sacral margin as the pathology permits, is advocated.