Does obesity affect surgical outcomes in degenerative scoliosis?

Impact of obesity on complications and surgical outcomes after adult degenerative scoliosis spine surgery

OBJECTIVE

To compare perioperative outcomes of obese versus non-obese adult patients who underwent degenerative scoliosis spine surgery.

METHODS

235 patients who underwent thoracolumbar adult spinal deformity (ASD) surgery (≥4 levels) were identified and categorized into two cohorts based on their body mass indices (BMI): obese (BMI ≥30 kg/m²; n = 81) and non-obese (BMI <30 kg/m²; n = 154). Preoperative (demographics, co-morbidities, American Society of Anesthesiologists (ASA) score and modified frailty indices (mFI-5 and mFI-11)), intraoperative (estimated blood loss (EBL) and anesthesia duration), and postoperative (complication rates, Oswestry Disability Index (ODI) scores, discharge destination, readmission rates, and survival) characteristics were analyzed by student's t, chi-squared, and Mann-Whitney U tests.

RESULTS

Obese patients were more likely to be Black/African-American (p < 0.05, OR:4.11, 95% CI:1.20-14.10), diabetic (p < 0.05, OR:10.18, 95% CI:4.38-23.68) and had higher ASA (p < .01) and psoas muscle indices (p < 0.0001). Furthermore, they had greater pre- and post-operative ODI scores (p < 0.05) with elevated mFI-5 (p < 0.0001) and mFI-11 (p < 0.01). Intraoperatively, obese patients were under anesthesia for longer time periods (p < 0.05) with higher EBL (p < 0.05). Postoperatively, while they were more likely to have complications (OR:1.77, 95% CI:1.01 - 3.08), had increased postop days to initiate walking (p < .05) and were less likely to be discharged home (OR:0.55, 95% CI:0.31-0.99), no differences were found in change in ODI scores or readmission rates between the two cohorts.

CONCLUSIONS

Obesity increases pre-operative risk factors including ASA, frailty and co-morbidities leading to longer operations, increased EBL, higher complications and decreased discharge to home. Pre-operative assessment and systematic measures should be taken to improve peri-operative outcomes.

Role of obesity in less radiographic correction and worse health-related quality-of-life outcomes following minimally invasive deformity surgery

OBJECTIVE

Minimally invasive surgery (MIS) for adult spinal deformity (ASD) can offer deformity correction with less tissue manipulation and damage. However, the impact of obesity on clinical outcomes and radiographic correction following MIS for ASD is poorly understood. The goal of this study was to determine the role, if any, that obesity has on radiographic correction and health-related quality-of-life measures in MIS for ASD.

METHODS

Data were collected from a multicenter database of MIS for ASD. This was a retrospective review of a prospectively collected database. Patient inclusion criteria were age ≥ 18 years and coronal Cobb angle ≥ 20°, pelvic incidence-lumbar lordosis mismatch ≥ 10°, or sagittal vertical axis (SVA) > 5 cm. A group of patients with body mass index (BMI) < 30 kg/m2 was the control cohort; BMI ≥ 30 kg/m2 was used to define obesity. Obesity cohorts were categorized into BMI 30-34.99 and BMI ≥ 35. All patients had at least 1 year of follow-up. Preoperative and postoperative health-related quality-of-life measures and radiographic parameters, as well as complications, were compared via statistical analysis.

RESULTS

A total of 106 patients were available for analysis (69 control, 17 in the BMI 30-34.99 group, and 20 in the BMI ≥ 35 group). The average BMI was 25.24 kg/m2 for the control group versus 32.46 kg/m2 (p < 0.001) and 39.5 kg/m2 (p < 0.001) for the obese groups. Preoperatively, the BMI 30-34.99 group had significantly more prior spine surgery (70.6% vs 42%, p = 0.04) and worse preoperative numeric rating scale leg scores (7.71 vs 5.08, p = 0.001). Postoperatively, the BMI 30-34.99 cohort had worse Oswestry Disability Index scores (33.86 vs 23.55, p = 0.028), greater improvement in numeric rating scale leg scores (-4.88 vs -2.71, p = 0.012), and worse SVA (51.34 vs 26.98, p = 0.042) at 1 year postoperatively. Preoperatively, the BMI ≥ 35 cohort had significantly worse frailty (4.5 vs 3.27, p = 0.001), Oswestry Disability Index scores (52.9 vs 44.83, p = 0.017), and T1 pelvic angle (26.82 vs 20.71, p = 0.038). Postoperatively, after controlling for differences in frailty, the BMI ≥ 35 cohort had significantly less improvement in their Scoliosis Research Society-22 outcomes questionnaire scores (0.603 vs 1.05, p = 0.025), higher SVA (64.71 vs 25.33, p = 0.015) and T1 pelvic angle (22.76 vs 15.48, p = 0.029), and less change in maximum Cobb angle (-3.93 vs -10.71, p = 0.034) at 1 year. The BMI 30-34.99 cohort had significantly more infections (11.8% vs 0%, p = 0.004). The BMI ≥ 35 cohort had significantly more implant complications (30% vs 11.8%, p = 0.014) and revision surgery within 90 days (5% vs 1.4%, p = 0.034).

CONCLUSIONS

Obese patients who undergo MIS for ASD have less correction of their deformity, worse quality-of-life outcomes, more implant complications and infections, and an increased rate of revision surgery compared with their nonobese counterparts, although both groups benefit from surgery. Appropriate counseling should be provided to obese patients.

Obesity and Spine Surgery: A Qualitative Review About Outcomes and Complications. Is It Time for New Perspectives on Future Researches?

STUDY DESIGN

Literature review.

OBJECTIVES

An increasing number of obese patients requires operative care for degenerative spinal disorders. The aim of this review is to analyze the available evidence regarding the role of obesity on outcomes after spine surgery. Peri-operative complications and clinical results are evaluated for both cervical and lumbar surgery. Furthermore, the contribution of MIS techniques for lumbar surgery to play a role in reducing risks has been analyzed.

METHODS

Only articles published in English in the last 10 years were reviewed. Inclusion criteria of the references were based on the scope of this review, according to PRISMA guidelines. Moreover, only paper analyzing obesity-related complications in spine surgery have been selected and thoroughly reviewed. Each article was classified according to its rating of evidence using the Sacket Grading System.

RESULTS

A total number of 1636 articles were found, but only 130 of them were considered to be relevant after thorough evaluation and according to PRISMA checklist. The majority of the included papers were classified according to the Sacket Grading System as Level 2 (Retrospective Studies).

CONCLUSION

Evidence suggest that obese patients could benefit from spine surgery and outcomes be satisfactory. A higher rate of peri-operative complications is reported among obese patients, especially in posterior approaches. The use of MIS techniques plays a key role in order to reduce surgical risks. Further studies should evaluate the role of multidisciplinary counseling between spine surgeons, nutritionists and bariatric surgeons, in order to plan proper weight loss before elective spine surgery.

Impact of Obesity on Complications and Surgical Outcomes of Adult Degenerative Scoliosis with Long- Segment Spinal Fusion

INTRODUCTION

The relationship between obesity and outcome of spine surgery has been controversial. The impact of obesity on surgical outcomes of patients undergoing long- segment (6 vertebrae or more) spinal fusion have not been studied. This study was designed to define the influence of obesity on the outcomes of patients undergoing long-segment spinal fusion.

METHODS AND MATERIALS

A retrospective study of patients undergoing long-segment (6 vertebrae or more) spinal fusion was realized. Patients were divided into non-obese group and obese group. Variables such as blood loss, operative time, length of stay, complications, reoperation rates, and clinical outcome were compared between the two groups.

RESULTS

Thirty-four non-obese patients (BMI: 26.43 ± 0.87) and 27 obese ones (BMI: 35.35 ± 1.81) were recruited. Number of fused levels in non-obese group was not significantly different from obese group (9.06±0.57 vertebrae vs 8.85±0.68 vertebrae, p=0.65). There was no significant difference between non-obese group and obese group in the blood loss during surgery (p= 0.12), the operating time (p=0.46) and the length of hospitalization (p=0.64). Similarly, no significant difference was found in surgical complications (p= 0.76) and medical complications (p=0.82) between the two groups. The rate of ambulatory improvement is similar between non-obese group and obese group (p=0.64).

CONCLUSION

Our study showed that there was no relationship between obesity and adverse surgical outcomes in ADS surgery with long-segment (6 vertebrae or more) spinal fusion.

Impact of body mass index on surgical outcomes and complications in adult spinal deformity

BACKGROUND

Several studies have reported that overweightness and obesity are associated with higher complication rates in lumbar spine surgery. However, little is known about the effect of obesity on postoperative complications in adult spinal deformity (ASD) surgery, especially in the elderly. This study aimed to examine the effect of body mass index (BMI) on surgical outcomes and postoperative complications in elderly ASD patients undergoing surgical correction in Japan.

METHODS

We conducted a retrospective, multicenter, observational study of 234 consecutive patients diagnosed with ASD who underwent corrective surgery. Patients were divided into two groups according to BMI, BMI <25 (153 patients, mean age 71.9 years) and BMI ≥ 25 (overweight/obese, 81 patients, mean age 73.3 years). Radiographic results and perioperative complications were compared between the two groups.

RESULTS

Surgical complications occurred in approximately 20% of patients in each group; complications did not significantly differ between the two groups. A greater proportion of patients in the BMI ≥ 25 group experienced mechanical failure and DJK, although the difference was not significant. Preoperative mean lumbar lordosis (LL), pelvic incidence (PI) minus LL, sacral slope (SS) and sagittal vertical axis (SVA) were similar in the BMI < 25 and BMI ≥ 25 groups. However, the BMI ≥25 group had lower mean LL (p = 0.015) and higher PI minus LL (p = 0.09) postoperatively. The BMI ≥25 groups also had significantly smaller LL (p = 0.026), smaller SS (p = 0.049) and higher SVA (p = 0.041) at the final follow-up, compared to the BMI < 25 group.

CONCLUSIONS

In the present study, no difference in medical or surgical complications after ASD surgery was found between overweight/obese patients (BMI ≥ 25) and those with BMI < 25. However, correction of LL and SVA was smaller in patients with overweight/obese patients.

Postoperative Complication Burden, Revision Risk, and Health Care Use in Obese Patients Undergoing Primary Adult Thoracolumbar Deformity Surgery

STUDY DESIGN

This is a retrospective cohort study using a nationally representative administrative database.

OBJECTIVE

To identify the impact of obesity on postoperative outcomes in patients undergoing thoracolumbar adult spinal deformity (ASD) surgery.

BACKGROUND

The obesity rate in the United States remains staggering, with approximately one-third of all Americans being overweight or obese. However, the impact of elevated body mass index on spine surgery outcomes remains unclear.

METHODS

We queried the MarketScan database to identify patients who were diagnosed with a spinal deformity and underwent ASD surgery from 2007 to 2016. Patients were then stratified by whether or not they were diagnosed as obese at index surgical admission. Propensity score matching (PSM) was then utilized to mitigate intergroup differences between obese and nonobese patients. Patients <18 years and those with any prior history of trauma or tumor were excluded from this study. Baseline demographics and comorbidities, postoperative complication rates, and short- and long-term reoperation rates were determined.

RESULTS

A total of 7423 patients met the inclusion criteria of this study, of whom 597 (8.0%) were obese. Initially, patients with obesity had a higher 90-day postoperative complication rate than nonobese patients (46.1% vs 40.8%, P < .05); however, this difference did not remain after PSM. Revision surgery rates after 2 years were similar across the 2 groups following primary surgery (obese, 21.4%, vs nonobese, 22.0%; P = .7588). Health care use occurred at a higher rate among obese patients through 2 years of long-term follow-up (obese, $152 930, vs nonobese, $140 550; P < .05).

CONCLUSION

Patients diagnosed with obesity who underwent ASD surgery did not demonstrate increased rates of complications, reoperations, or readmissions. However, overall health care use through 2 years of follow-up after index surgery was higher in the obesity cohort.

Somatic determinants of changes in selected body posture parameters in younger school-age children

Background

The aim of this study was to describe changes in selected parameters of body posture in children between 5 and 9 years old with diversified somatic structures.

Methods

The study was carried out in 2015 and then repeated in 2018 among 67 participants who had previously been observed to have scoliotic posture. Basic body weight and height measurements were taken, which were then used to calculate the body mass index. Posture tests were conducted using the photogrammetric method.

Results

Girls and boys were not significantly different in body dimensions. With age, the number of overweight boys and children with normal growth-weight proportions increased. Temporary differences in posture variables indicating abnormalities were small.

Conclusions

There were no significant differences in somatic parameters between the girls and the boys. Those children with a slender body structure had the most abnormalities in the coronal plane. On the other hand, changes in spinal position in the sagittal plane were more frequent in overweight children. Relations were noted between the compensation index in the sagittal plane and deviation of the trunk inclination, the maximum deviation of the line of the spinous processes, and the angle of the shoulder line in the coronal plane and body mass index values were noted.

The Role of Potentially Modifiable Factors in a Standard Work Protocol to Decrease Complications in Adult Spinal Deformity Surgery: A Systematic Review, Part 1

STUDY DESIGN

Structured Literature Review.

OBJECTIVES

We sought to evaluate the peer-reviewed literature for potentially modifiable patient and surgical factors that could be incorporated into a Standard Work protocol to decrease complications in adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Lean Methodology uses Standard Work to improve efficiency and decrease waste and error. ASD is known to have a high surgical complication rate. Several patient and surgical potentially modifiable factors have been suggested to affect complications, including preoperative hemoglobin, bone density, body mass index (BMI), age-appropriate realignment, preoperative albumin/prealbumin, and smoking status. We sought to evaluate the literature for evidence supporting these factors to include in a Standard Work protocol to decrease complications.

METHODS

Each of these six factors was developed into an appropriate clinical question that included the patient population, surgical intervention, a comparison group, and outcomes measure (PICO question). A comprehensive literature search was then performed. The authors reviewed abstracts and analyzed data from included studies. From 456 initial citations with abstract, 173 articles underwent full-text review. The best available evidence for clinical questions regarding the influence of these factors was provided by 93 included studies.

RESULTS

We found fair evidence supporting a low preoperative hemoglobin level associated with increased transfusion rates and decreased BMD and increased BMI associated with increased complication rates. Fair evidence supported low albumin/prealbumin associated with increased complications. There was fair evidence associating smoking exposure to increased reoperations, but conflicting evidence associating it with increased complications. There was no evidence in the literature evaluating age-appropriate realignment and complications.

CONCLUSION

Preoperative hemoglobin, bone density, body mass index, preoperative albumin/prealbumin, and smoking status all are potentially modifiable risk factors that are associated with increased complications in the adult spine surgery population. Developing a Standard Work Protocol for patient evaluation and optimization should include these factors.

LEVEL OF EVIDENCE

Level II.

Surgical Risk Assessment and Prevention in Elderly Spinal Deformity Patients

Introduction:

Prevalence of adult deformity surgery in the elderly individuals continues to increase. These patients have additional considerations for the spine surgeon during surgical planning. We perform an informative review of the spinal and geriatric literature to assess preoperative and intraoperative factors that impact surgical complication occurrences in this population.

Significance:

There is a need to understand surgical risk assessment and prevention in geriatric patients who undergo thoracolumbar adult deformity surgery in order to prevent complications.

Methods:

Searches of relevant biomedical databases were conducted by a medical librarian. Databases searched included MEDLINE, Web of Science, CINAHL, IPA, Cochrane, PQ Health and Medical, SocINDEX, and WHO’s Global Health Library. Search strategies utilized Medical Subject Headings plus text words for extensive coverage of scoliosis and surgical technique concepts.

Results:

Degenerative scoliosis affects 68% of the geriatric population, and the rate of surgical interventions for this pathology continues to increase. Complications following spinal deformity surgery in this patient population range from 37% to 62%. Factors that impact outcomes include age, comorbidities, blood loss, and bone quality. Using these data, we summarize multimodal risk prevention strategies that can be easily implemented by spine surgeons.

Conclusions:

After evaluation of the latest literature on the complications associated with adult deformity surgery in geriatric patients, comprehensive perioperative management is necessary for improved outcomes. Preoperative strategies include assessing physiological age via frailty score, nutritional status, bone quality, dementia/delirium risk, and social activity support. Intraoperative strategies include methods to reduce blood loss and procedural time. Postoperatively, development of a multidisciplinary team approach that encourages early ambulation, decreases opiate use, and ensures supportive discharge planning is imperative for better outcomes for this patient population.

What Should an Ideal Adult Spinal Deformity Classification System Consist of?: Review of the Factors Affecting Outcomes of Adult Spinal Deformity Management

This literature review aims to determine potential clinical factors or comorbidities besides radiological parameters that affect the outcome of adult spinal deformity (ASD) management and review existing classifications associated with ASD. ASD is a multifactorial disease that comprises pathologies like radiological spine deformity, coexistence of spinal canal stenosis, radiculopathy, and multiple comorbidities. The available classification systems of ASD are predominantly based on radiological parameters and do not consider related clinical conditions. ASD patients with different combinations of these parameters behave differently and need different management strategies. We conducted a narrative literature review with search limited to English language of PubMed/MEDLINE using Medical Subject Heading (MeSH) terms. The terms specific to the review were ASD and several other related terminologies. We analyzed the information of the selected papers including factors affecting surgical outcomes for degenerative scoliosis. We reviewed 614 citations. Based on the inclusion criteria, 39 citations were selected for full-text retrieval; of these, 28 were excluded because of not fulfilling the inclusion criteria. Thus, 11 studies were selected and included for the final analysis. The presence of leg pain, spinal stenosis, obesity, osteoporosis, smoking, and age of patients were major influencing factors. Furthermore, the factors included in the available classifications, such as the Scoliosis Research Society–Schwab classifications, were reviewed and results were tabulated. This review highlights the significance of neurological symptoms, spinal stenosis, osteoporosis, obesity, age, and smoking, which markedly affect the management of ASD. With increasing number of patients being diagnosed and treated with ASD, there has been a growing need to comprehensively classify these patients into clinicoradiological subgroups.

Do Overweight Adolescent Idiopathic Scoliosis (AIS) Patients Have an Increased Perioperative Risk for Posterior Spinal Fusion (PSF) Surgery?: A Propensity Score Matching Analysis of 374 AIS Patients

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to compare the perioperative outcome of posterior spinal fusion (PSF) between overweight (OW) adolescent idiopathic scoliosis (AIS) patients and the healthy-weight (HW) patients using propensity score matching analysis.

SUMMARY OF BACKGROUND DATA

Obesity was found to increase postoperative surgical complications compared with the nonobese group. In scoliosis correction surgery, association of OW and perioperative risks had been explored, but most studies were retrospective in nature.

METHODS

From 374 patients, two comparable groups were matched using propensity score matching analysis with one-to-one nearest neighbor matching and a caliper of 0.2. There were 46 HW and OW patients in each group. The main outcome measures were intraoperative blood loss, use of allogeneic blood transfusion, operative time, duration of hospital stay post-surgery, total patient-controlled analgesia (PCA) morphine usage, perioperative complications, side bending flexibility (SBF), and correction rate (%).

RESULTS

The mean age was 13.3 ± 1.7 and 13.2 ± 1.7 years for HW and OW groups, respectively. The majority of the patients were Lenke 1 curves; 32.6% (HW) and 26.1% (OW) with an average Cobb angle of 69.0 ± 19.1° and 68.8 ± 18.4° for each group, respectively. The two groups were comparable. The operation time was 145.2 ± 42.2 and 154.4 ± 48.3 minutes for HW and OW groups, respectively (P > 0.05). The intraoperative blood loss was almost similar in both groups; 955.1 ± 497.7 mL (HW group) and 1011.8 ± 552.7 mL (OW group) (P > 0.05). Total PCA morphine used was higher in OW group (30.4 ± 22.7 mg) than in the HW group (16.2 ± 11.3 mg). No complication was observed in HW group, while in OW group, one patient (2.2%) developed intraoperative seizure.

CONCLUSION

OW AIS patients (≥85th percentile) had similar mean operative time, intraoperative blood loss, allogeneic transfusion rate, length of stay, and perioperative complications compared with HW AIS patients.

LEVEL OF EVIDENCE

3.

Thoracolumbar Fusion in Extreme Obesity: Complications and Patient-Reported Outcomes

Background

Extreme obesity (class III) is defined by the Centers for Disease Control as a body mass index (BMI) value ≥40. Recent studies suggest that obese patients have poor outcomes after thoracolumbar spinal fusions. The objective of this study was to analyze 30-day adverse events and patient-reported outcomes (PROs) for this population.

Patients and Methods

A retrospective chart review of spinal fusion surgeries performed at a single institution from 2006 to 2016 was executed. All patients had a preoperative BMI ≥40. Patient characteristics, including age, sex, BMI, American Society of Anesthesiologists (ASA) score, Charlson Comorbidity Index (CCI), and others, were collected. Thirty-day adverse events (complications, readmissions, reoperations, and mortality) and PROs (Oswestry Disability Index [ODI] and visual analog scale [VAS]) were recorded.

Results

Fifty-six patients were identified, including 30 men (54%). Mean age was 55.7 years (range, 31-74 years). Mean BMI was 44.2 (range, 40.0-54.7). Mean ASA was 2.7 (range, 2-3), and mean CCI was 1.1 (range, 0-6). Mean number of fused levels was 2.3 (range, 1-14). Mean length of stay was 4.4 ± 2.1 days. Mean number of complications was 0.7 ± 1.1, with 30.4% of patients having had at least 1 complication. The 30-day all-cause readmission rate was 5.4%, and 30-day reoperation rate was 3.6%. For 30 patients (54%) with 1-year PROs, mean preoperative ODI was 65.2 ± 11.1, and mean preoperative VAS was 6.6 ± 1.6. Mean ODI change was -19.9 ± 20.1 (P < .001), and mean VAS change was -2.6 ± 2.3 (P < .001). A total of 15 patients (50%) achieved the minimum clinically important difference in ODI (12.8), with a mean follow-up of 18.9 months.

Conclusions

Patients with extreme obesity who undergo thoracolumbar fusion have acceptable 30-day adverse events and potentially can achieve significant improvement in pain and disability.

Increasing Body Mass Index is Associated With Worse Perioperative Outcomes and Higher Costs in Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective review.

OBJECTIVE

To investigate associations of obesity with outcomes and costs of adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Increasing body mass index (BMI) is a risk factor for complications after nondeformity spine surgery, but its effect on ASD surgery is unknown.

METHODS

We reviewed records of 244 ASD patients who underwent spinal arthrodesis of ≥5 levels from 2010 to 2014 and categorized them by World Health Organization BMI groups: BMI < 30, nonobese (64%); BMI = 30-34.99, class-I obese (21%); and BMI ≥ 35, class-II/III obese (15%). We used multivariate logistical regression to determine odds of transfusion, inpatient complications, prolonged intensive care unit (ICU) stay (>2 days), prolonged total length of hospital stay (LOS) (>1 week), and high episode-of-care costs (>$80,000).

RESULTS

Preoperative characteristics were similar among groups, except sex, preoperative hemoglobin concentration, and performance/type of osteotomy (all, P = 0.01). On univariate analysis, the groups differed in rates of prolonged ICU stay (P < 0.001), prolonged total LOS (P = 0.016), and high episode-of-care costs (P = 0.013). Inpatient complication rates were similar among groups (P = 0.218). On multivariate analysis, compared with nonobese patients, class I obese patients had greater odds of prolonged ICU stay (odds ratio [OR] = 2.24, 95% confidence interval [CI]: 1.06, 4.71). Class II/III obese patients also had greater odds of prolonged total LOS (OR = 2.21, 95% CI: 1.03, 4.71), and high episode-of-care costs (OR = 2.91, 95% CI: 1.31, 6.50).

CONCLUSION

In ASD surgery, BMI ≥35 is associated with significantly worse perioperative outcomes and higher costs compared with those of nonobese patients.

LEVEL OF EVIDENCE

3.

Quantifying the ‘law of diminishing returns’ in magnetically controlled growing rods

Aims

Magnetically controlled growing rods (MCGRs) allow non-invasive correction of the spinal deformity in the treatment of early-onset scoliosis. Conventional growing rod systems (CGRS) need repeated surgical distractions: these are associated with the effect of the ‘law of diminishing returns’. The primary aim of this study was to quantify this effect in MCGRs over sequential distractions.

Patients and Methods

A total of 35 patients with a maximum follow-up of 57 months were included in the study. There were 17 boys and 18 girls with a mean age of 7.4 years (2 to 14). True Distraction (TD) was determined by measuring the expansion gap on fluoroscopy. This was compared with Intended Distraction (ID) and expressed as the ‘T/I’ ratio. The T/I ratio and the Cobb angle were calculated at several time points during follow-up.

Results

The mean follow-up was 30 months (6 to 57). There was a significant decrease in the mean T/I ratio over time (convex rod at 3 months 0.81, sd 0.58 vs 51 months 0.17, sd 0.16, p = 0.0001; concave rod at 3 months 0.93, sd 0.67 vs 51 months 0.18, sd 0.15, p = 0.0001). A linear decline of the mean T/I ratios was noted for both convex rods (r2 = 0.90, p = 0.004) and concave rods (r2 = 0.81, p = 0.015) over 51 months. At the 24-month follow-up stage, there was a significant negative correlation between the mean T/I ratio of the concave rod with weight (r = -0.59, p = 0.01), age (r = -0.59, p = 0.01), and BMI of the child (r = -0.54, p = 0.01).

Conclusions

The ‘law of diminishing returns’ is also seen after serial distraction using MCGR. Compared to previously published data for CGRS, there is a gradual linear decline rather than a rapid initial decline in lengthening. In older, heavier children a reduced distraction ratio in the concave rod of the MCGR device is noted over time. Cite this article: Bone Joint J 2017;99-B:1658–64.

Effect of body mass index on patient outcomes of surgical intervention for the lumbar spine

BACKGROUND

Conflicting findings exist on the effect of obesity on outcomes of lumbar spine surgery; results depend on the diagnosis studied, procedure evaluated, definition of obesity, and specific outcomes measured. The purpose of this retrospective cohort study is to examine the effect of increasing body mass index (BMI) on surgical-related, health-related, and long-term outcomes of lumbar spine surgery in a single representative patient sample.

METHODS

Using a surgical registry from an integrated health care system, 8,049 instrumented lumbar spine cases were identified between 1/1/2009 and 09/30/2013. The sample was stratified into five BMI categories. Outcomes of interest included: (I) surgical-related factors and complications; (II) health-related complications; and (III) long-term complications. Mixed linear models, conditional logistic regressions, and survival analysis using a Cox regression model were conducted controlling for surgeon effects. Age, gender, diabetes status, smoking status, admitting diagnosis, and surgical approach were included as covariates.

RESULTS

Every 5 kg/m2 increase in BMI was associated with a significant increase in surgical time (7.8 minutes), estimated blood loss (EBL) (36.5 mL), risk of deep infection (OR =1.7 times), and deep vein thrombosis (DVT) (OR =1.5). BMI was not associated with increased incidence of other intraoperative or health-related complications. Rate of re-operation was 1.1 times higher with every 5 kg/m2 increase in BMI, but rate of re-operation due to adjacent segment disease (ASD) was not associated with BMI.

CONCLUSIONS

Obesity had an adverse effect on certain surgical-related, health-related and long-term surgical outcomes. The magnitude of this effect increased with increasing levels of obesity, which increases the medical burden associated with obesity.

Analysis of Relationship between the Body Mass Composition and Physical Activity with Body Posture in Children

Introduction. Excessive body mass in turn may contribute to the development of many health disorders including disorders of musculoskeletal system, which still develops intensively at that time. Aim. The aim of this study was to assess the relationship between children's body mass composition and body posture. The relationship between physical activity level of children and the parameters characterizing their posture was also evaluated. Material and Methods. 120 school age children between 11 and 13 years were enrolled in the study, including 61 girls and 59 boys. Each study participant had the posture evaluated with the photogrammetric method using the projection moiré phenomenon. Moreover, body mass composition and the level of physical activity were evaluated. Results. Children with the lowest content of muscle tissue showed the highest difference in the height of the inferior angles of the scapulas in the coronal plane. Children with excessive body fat had less slope of the thoracic-lumbar spine, greater difference in the depth of the inferior angles of the scapula, and greater angle of the shoulder line. The individuals with higher level of physical activity have a smaller angle of body inclination. Conclusion. The content of muscle tissue, adipose tissue, and physical activity level determines the variability of the parameter characterizing the body posture.

Impact of obesity on complications, infection, and patient-reported outcomes in adult spinal deformity surgery

OBJECT

Adult spinal deformity (ASD) surgery is known for its high complication rate. This study examined the impact of obesity on complication rates, infection, and patient-reported outcomes in patients undergoing surgery for ASD.

METHODS

This study was a retrospective review of a multicenter prospective database of patients with ASD who were treated surgically. Patients with available 2-year follow-up data were included. Obesity was defined as having a body mass index (BMI) ≥ 30 kg/m2. Data collected included complications (total, minor, major, implant-related, radiographic, infection, revision surgery, and neurological injury), estimated blood loss (EBL), operating room (OR) time, length of stay (LOS), and patient-reported questionnaires (Oswestry Disability Index [ODI], Short Form-36 [SF-36], and Scoliosis Research Society [SRS]) at baseline and at 6 weeks, 1 year, and 2 years postoperatively. The impact of obesity was studied using multivariate modeling, accounting for confounders.

RESULTS

Of 241 patients who satisfied inclusion criteria, 175 patients were nonobese and 66 were obese. Regression models showed that obese patients had a higher overall incidence of major complications (IRR 1.54, p = 0.02) and wound infections (odds ratio 4.88, p = 0.02). Obesity did not increase the number of minor complications (p = 0.62), radiographic complications (p = 0.62), neurological complications (p = 0.861), or need for revision surgery (p = 0.846). Obesity was not significantly correlated with OR time (p = 0.23), LOS (p = 0.9), or EBL (p = 0.98). Both groups experienced significant improvement overtime, as measured on the ODI (p = 0.0001), SF-36 (p = 0.0001), and SRS (p = 0.0001) questionnaires. However, the overall magnitude of improvement was less for obese patients (ODI, p = 0.0035; SF-36, p = 0.0012; SRS, p = 0.022). Obese patients also had a lower rate of improvement over time (SRS, p = 0.0085; ODI, p = 0.0001; SF-36, p = 0.0001).

CONCLUSIONS

This study revealed that obese patients have an increased risk of complications following ASD correction. Despite these increased complications, obese patients do benefit from surgical intervention; however, their improvement in health-related quality of life (HRQL) is less than that of nonobese patients.