Geometric analysis of pedicle subtraction osteotomy (PSO) for Kyphosis correction: anterior lengthening may occur at the osteotomized body as well as at the discs above and below.

OBJECTIVE: To validate the authors kyphosis correction formula for pedicle subtraction osteotomy (PSO) cases. Additionally, to use the formula to evaluate the safety of PSO by determining if there is anterior lengthening. METHODS: Twenty-two patients with primarily kyphosis corrected by PSO and with clear landmarks on preoperative and postoperative x-rays were selected. Several anatomical lines and angle measurements were utilized as depicted previously in the Vertebral Column Resection formula (see below). Two approximations were calculated: the geometric approximation (G) = (tanG°*2 + 1)*15° and the rough approximation (R) which is about the same amount of actual shortening (x), if parallel length (y) ≥ 40; twice of x, if y < 40. For each patient, the change of segmental kyphosis angle (K°) was measured and compared with G° and R°, and the correlation between each value was analyzed. RESULTS: The absolute Mean ± SE for K - G and K - R was 2.33° ± 0.34 and 6.09° ± 0.58, respectively. K - G is < 3° (p = 0.03). K - R is < 8° (p = 0.001). In other words, K was close to G and R and thus can be predicted by these approximations. Average posterior shortening, anterior shortening, and kyphosis correction at each level were 20.8 ± 2.0 mm, - 3.64 ± 1.5 mm (which equates to anterior lengthening), and 31.05° ± 2.0, respectively. Anterior lengthening occurred in 13 cases (in 4 cases, both at the body as well as at the disc above and below.) The correlation between posterior and anterior shortening was 0.03 (p = 0.88). There were 3 cage insertion cases: 1 had anterior lengthening, while 2 had anterior shortening even with the cage. CONCLUSION: This study validated the geometric and rough approximations originally used in PVCR patients, for PSO patients. Additionally, this study found that anterior lengthening may occur in PSOs usually at the discs, but occasionally at the osteotomized body.

Acute Cholecystitis: An Emerging Complication in Spinal Cord Injury Patients in the United States.

BACKGROUND: Spinal cord injury (SCI) is a significant medical condition associated with various secondary complications, including cholelithiasis. Cholelithiasis can cause biliary duct obstruction and result in acute cholecystitis. The development of acute cholecystitis in SCI patients has been well studied in the Taiwanese population, showing an increased risk of acute cholecystitis in patients with SCI. The development of cholecystitis has not been well studied in the United States. MATERIALS AND METHODS: A retrospective review was performed on 3,939 propensity score-matched patients aged 18 to 85 years who had SCI/surgery from 2000 to 2019. Patients were divided based on the development of postoperative complications, specifically cholecystitis with cholecystectomy. RESULTS: SCI consisted of quadriplegia (42%), paraplegia (53%), unspecified lesion of cervical spinal cord (3%), and thoracic spinal cord (2%). All groups were comparable regarding age, gender, body mass index, smoking status, and Charlson comorbidity Index. The incidence of acute cholecystitis with subsequent cholecystectomy among patients with SCI was 43.0 per 10,000 person-years (95% confidence interval: 41.51-44.49). Median follow-up was 36 months. The development of cholecystitis was comparable among females (54.5%) and males (45.5%), and among African Americans (52.5%) and Caucasians (47.5%). CONCLUSION: There is an association between SCI and development of acute cholecystitis among U.S. PATIENTS: As SCI patients do not present with the classic signs of biliary colic, risk assessment for the development of acute cholecystitis will guide patient management and allow neurosurgeons to weigh the risks and benefits of prophylactic treatment for gallbladder complications.

Modic Change: An Emerging Complication in the Aging Population.

STUDY DESIGN: This was a literature review. OBJECTIVE: The objective of this study was to review the pathogenesis, prevalence, clinical associations, diagnostic modalities, and treatment options for patients with lower back pain (LBP) associated with Modic change (MC). SUMMARY OF BACKGROUND DATA: Vertebral body endplates are located between the intervertebral disk and adjacent vertebral body. Despite their crucial roles in nutrition and biomechanical stability, vertebral endplates are extremely susceptible to mechanical failure. Studies examining the events leading to disk degeneration have shown that failure often begins at the endplates. Endplate degeneration with subchondral bone marrow changes were originally noticed on magnetic resonance imaging. These magnetic resonance imaging signal changes were classified as MC. METHODS: A literature review was conducted on the history, etiology, risk factors, diagnostic modalities, and treatment of LBP with MC. RESULTS: Type 1 MC refers to the presence of increased vascularization and bone marrow edema within the vertebral body. Type 2 MC involves fatty marrow replacement within the vertebral body. Type 3 MC reflects subchondral bone sclerosis. Despite the original classification, research has supported the notion that MCs possess a transitional nature. Furthermore, type 1 MCs have been strongly associated with inflammation and severe LBP, while types 2 and 3 tend to be more stable and demonstrate less refractory pain. With a strong association to LBP, understanding the etiology of MC is crucial to optimal treatment planning. Various etiologic theories have been proposed including autoimmunity, mechanics, infection, and genetic factors. CONCLUSIONS: With the aging nature of the population, MC has emerged as an extremely prevalent issue. Research into the pathogenesis of MC is important for planning preventative and therapeutic strategies. Such strategies may include rehabilitation, surgical fixation, stabilization, steroid or cement injection, or antibiotics. Improved diagnostic methods in clinical practice are thus critical to properly identify patients suffering from MC, plan early intervention, and hasten return to functioning.

Racial Differences in Iliac Crest Cancellous Bone Composition: Implications for Preoperative Planning in Spinal Fusion Procedures.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: The objective of this study was to determine whether race, specifically American white and American black, correlates with the ratio of cancellous to total bone at the iliac crest. SUMMARY OF BACKGROUND DATA: Studies have demonstrated higher proximal femur bone density in American blacks than American whites. However, whether differences occur at the iliac crest, a common site for autologous graft material in spinal fusion surgery, is not well studied. Understanding such differences could aid orthopedic surgeon decision-making regarding graft options. MATERIALS AND METHODS: A retrospective review was performed on 133 sequential patients ages 18-75 who underwent computed tomography scan of the pelvis, at a single academic medical center from January 1, 2014, to January 1, 2016. The cohort included 46 American white (21 females, 25 males) and 87 American black participants (40 females, 37 males), an average age of 51.8 years. Groups were matched regarding age, sex, body mass index, and Charlson Comorbidity Score. Measurements of cortical and cancellous bone thickness in the right and left iliac crests were performed using bone window protocol on computed tomography scans. Statistical significance was determined using a 2-tailed t test. RESULTS: The interobserver interclass correlation coefficient reliability (N=2) for measurements at the right iliac crest is 0.895 (95% confidence interval, 0.852-0.925), and the interclass correlation coefficient for the left iliac crest is 0.912 (95% confidence interval, 0.877-0.938). A statistically significant difference in the mean cancellous bone ratio was found between American black (0.667±0.065) and American white (0.750±0.051) groups (P<0.001). CONCLUSIONS: At the iliac crest, American black patients had a lower mean ratio of cancellous to the total bone as compared with American white patients. This population may benefit from alternative graft options. While iliac crest autograft remains the first option for fusion surgeries, alternative options should be considered to ensure that each patient receives the best-personalized care.

Infra-adjacent Segment Disease After Lumbar Fusion: An Analysis of Pelvic Parameters.

STUDY DESIGN: Cross-sectional observational cohort study. OBJECTIVE: The aim of this study was to determine the incidence and risk factors associated with the development of sacroiliac joint (SIJ) dysfunction following lumbosacral fusion. SUMMARY OF BACKGROUND DATA: Adjacent segment degeneration to both proximal and distal areas of spinal fusion is a postoperative complication of lumbar fusion. Various studies examined supra-adjacent degeneration following lumbar fusion, but few focused on infra-adjacent degeneration. In lumbosacral fusion, fusion extends to the sacrum, placing increased stress on the SIJ. METHODS: A total of 2069 sequential patients who underwent lumbosacral fusion surgery from 2008 to 2018 at a single academic medical center were retrospectively reviewed. Patients who subsequently developed SIJ dysfunction were identified. SIJ dysfunction was defined as patients who met the diagnostic criteria with physical examination and received an SIJ injection with clinical evidence of improvement. Controls, without subsequent SIJ dysfunction, were matched with cases based on levels of fusion, age, sex, and body mass index. Pre-and postoperative pelvic parameters were measured, including pelvic incidence, pelvic tilt (PT), sacral slope, lumbar lordosis, lumbosacral angle, L4 incidence and L5 incidence. RESULTS: Of 2069 patients who underwent lumbosacral fusion, 81 patients (3.9%) met criteria for SIJ dysfunction. Measurements were made for 47 of 81 patients who had SIJ dysfunction, that had both pre- and post-operative imaging. Measurements for 44 matched controls were taken. Postoperative PT was significantly lower in SIJ dysfunction patients compared to controls (20.82°â€Š±â€Š2.19° vs. 27.28°â€Š±â€Š2.30°; P < 0.05), as was L5 incidence (28.64°â€Š±â€Š3.38° vs. 37.11°â€Š± 3.50°; P < 0.05). CONCLUSION: Incidence of the SIJ dysfunction after lumbosacral fusion surgery was 3.9% and these patients had a significantly lower PT and L5 incidence compared to the control group. Significantly low PT may be derived from weak hamstring muscles, predisposing a patient to SIJ dysfunction. Therefore, hamstring muscle strengthening exercise for patients with decreased PT after lumbosacral fusion may decrease the incidence of SIJ dysfunction.Level of Evidence: 3.

Sacroiliac joint dysfunction: pathophysiology, diagnosis, and treatment.

PURPOSE: To review the anatomy and function of the sacroiliac joint (SIJ), as well as the pathophysiology, clinical presentation, diagnostic criteria, and treatment options for SIJ dysfunction. METHODS: The SIJ serves an extremely crucial function in mobility, stability, and resistance against shear forces. Joint mobility becomes increasingly limited with age-related cartilaginous changes that begin in puberty and continue throughout life. Pain can also be localized to the SIJ itself, known as SIJ dysfunction. A literature review was performed on the anatomy, etiology, risk factors, diagnostic modalities, and treatment options for SIJ dysfunction. RESULTS: SIJ dysfunction is an under-recognized source of low back pain. Dysfunction can result from various clinical conditions, as well as abnormal motion or malalignment of the joint. Diagnosis and evaluation of SIJ dysfunction are difficult, with use of physical maneuvers and image-guided anesthetic injection. Non-operative treatment options are considered first-line due to high surgical complication rates. Such options include conservative management, radiofrequency treatment, nerve blocks, and articular injections. Surgical management involves open and percutaneous approaches. CONCLUSION: With the aging nature of the population, SIJ dysfunction has emerged as an extremely prevalent issue. Current research into the pathophysiology and risk factors of SIJ dysfunction is extremely important for planning preventative and therapeutic strategies. Various treatment options exist including conservative management, radiofrequency, nerve blocks, intra-articular or peri-articular injections, and surgical fixation. Improved diagnostic methods in clinical practice are thus critical to properly identify patients suffering from SIJ dysfunction, plan early intervention, and hasten return to function. LEVEL OF EVIDENCE I: Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Overview and Spinal Implications of Leg Length Discrepancy: Narrative Review.

Leg length discrepancy (LLD) is an underrecognized and prevalent condition among the U.S. population, with effects varying depending on the cause and size of the discrepancy. LLD occurs when the paired lower extremities are unequal in length and can be etiologically classified as functional or structural. Length differences are typically less than 10 mm and asymptomatic or easily compensated for by the patient through self-lengthening or shortening of the lower extremities. Literature review of the etiology, diagnostic modalities, clinical complications, and treatment option for patients with LLD. LLD can be assessed directly through tape measurements or indirectly through palpation of bony landmarks. Imaging modalities, specifically radiography, are more precise and help identify coexistent deformity. Once LLD has been diagnosed, evaluation for potential adverse complications is necessary. Discrepancies greater than 20 mm can alter biomechanics and loading patterns with resultant functional limitations and musculoskeletal disorders, such as functional scoliosis. Functional scoliosis is nonprogressive and involves a structurally normal spine with an apparent lateral curvature, which regresses fully or partially when the LLD is corrected. Long-standing LLD and functional scoliosis often result in permanent degenerative changes in the facet joints and intervertebral discs of the spine. Further understanding of the contribution of LLD in the development of scoliosis and degenerative spine disease will allow for more effective preventative treatment strategies and hasten return to function.

Comparative outcome analysis of spinal anesthesia versus general anesthesia in lumbar fusion surgery.

INTRODUCTION: Spinal anesthesia (SA) has been shown in several studies to be a viable alternative to general anesthesia (GA) in laminectomies, discectomies, and microdiscectomies. However, the use of SA in spinal fusion surgery has been very scarcely documented in the current literature. Here we present a comparison of SA to GA in lumbar fusion surgery in terms of perioperative outcomes and cost. METHODS: The authors retrospectively reviewed the charts of all patients who underwent 1- or 2-level minimally invasive transforaminal lumbar interbody fusion (TLIF) surgery by a single surgeon, at a single institution, from 2015 to 2018. Data collected included demographics, operative and recovery times, nausea/vomiting, postoperative pain, and opioid requirement. Costs were included in the analysis if they were: 1) non-fixed; 2) incurred in the operating room (OR); and 3) directly related to patient care. All cost data represents net costs and was obtained from the hospital revenue cycle team. Patients were grouped for statistical analysis based on anesthetic modality. RESULTS: A total of 29 patients received SA and 46 received GA. Both groups were similar in terms of age, gender, BMI, number of levels operated upon, preoperative diagnosis, and medical comorbidities. The SA group spent less time in the OR (163.86 ± 9.02 vs. 195.63 ± 11.27 min, p < 0.05), PACU (82.00 ± 7.17 vs. 102.98 ± 8.46 min, p < 0.05), and under anesthesia (175.03 ± 9.31 vs. 204.98 ± 10.15 min, p < 0.05) than the GA group. Post-surgery OR time was significantly less with SA than with GA (6.00 ± 1.09 vs. 17.26 ± 3.05 min, p < 0.05); however, pre-surgery OR time was similar between groups (50.17 ± 3.08 vs. 56.17 ± 5.34 min, p = 0.061). The SA group also experienced less maximum postoperative pain (3.31 ± 1.41 out of 10 vs. 5.96 ± 0.84/10, p < 0.05) and required less opioid analgesics (2.38 ± 1.37 vs. 5.39 ± 0.84 doses, p < 0.05). Both groups experienced similar nausea or vomiting rates and adverse events postoperatively. Net operative cost was found to be $812.31 (5.6%) less with SA than with GA, although this difference was not significant (p = 0.225). DISCUSSION/CONCLUSION: To our knowledge, SA is almost never used in lumbar fusion, and a cost-effectiveness comparison with GA has not been recorded. In this retrospective study, we demonstrate that the use of SA in lumbar fusion surgery leads to significantly shorter operative and recovery times, less postoperative pain and opioid usage, and slight cost savings over GA. Thus, we conclude that this anesthetic modality represents a safe and cost-effective alternative to GA in lumbar fusion.

Establishing the validity of surface topography for assessment of scoliosis: a prospective study.

STUDY DESIGN: Descriptive survey. OBJECTIVES: Compare radiographic parameters measured using surface topography (ST) with those obtained radiographically to determine the validity of ST for scoliotic assessment. METHODS: While anterior-posterior radiography is the gold standard for diagnosing scoliosis, repeated radiographic use is associated with increased carcinogenicity. Studies have thus focused on radiation-free systems, including ST, to calculate the scoliotic angle. Seventeen patients ages 25-76 were included. Each patient received one AP radiograph and three repeated ST measurements over two months. Values were analyzed by two raters to determine comparability between ST and radiographic measurements. Interobserver reliability (ICC) was calculated and statistical significance was determined by the p-value of a paired two-tailed t-test. RESULTS: ICC showed excellent reliability (> 0.90). There was no significant difference (p > 0.40) in apical vertebral deviation/translation between conventional radiography (0.9 ± 0.8) and ST (1.2 ± 1.0). There was no significant difference (p > 0.30) in sagittal balance radiographic (4.0 ± 3.1) and ST (4.4 ± 3.3), and coronal balance radiographic (1.4 ± 1.3) and ST (1.1 ± 1.1) measurements. Significant difference (p < .001) was found between lumbar lordosis radiographic (52.6 ± 18.4) and ST (37.9 ± 16.6), kyphotic angle radiographic (35.1 ± 16.0) and ST (50.0 ± 11.9), and scoliotic angle radiographic (11.3 ± 12.4) and ST (17.7 ± 10.2) measurements. CONCLUSIONS: No significant difference was observed between various ST and radiographic measurements, including apical vertebral deviation, sagittal balance, and coronal balance. While a larger prospective study is needed to further assess the validity of ST, these initial measurements suggest the possibility of an effective and radiation-free adjunctive method of assessing balance in the coronal plane.

Understanding breast asymmetry and its relation to AIS.

STUDY DESIGN: Literature Review. OBJECTIVE: Review the pathophysiology, causes, and treatment of breast asymmetry in patients with adolescent idiopathic scoliosis (AIS), as well as postoperative patient assessment and health-related quality of life. BACKGROUND DATA: Female breast development begins at 35-day gestation and continues 2-4-year post-thelarche to achieve final volume and shape. During the post-pubertal period, errors in growth and development may result in breast asymmetry. Breast asymmetry typically attenuates with time, but can be pronounced in individuals with AIS. During adolescence, there is rapid development and, thus AIS patients are increasingly sensitive, physically and emotionally, to breast changes. While breast asymmetry can be monitored through radiographic measures and surface topography, pre- and postoperative patient assessment is also critical in determination of optimal patient treatment. METHODS: A comprehensive literature review was performed on the pathophysiology, causes, and treatment of breast asymmetry. The advantages and limitations of various treatment options based on patient satisfaction were also investigated. RESULTS: Various treatment options exist for breast asymmetry correction in AIS patients. Surgical correction involves an aesthetic outcome, as well as social, physical, and psychological impact on the patient. Despite the benefit of correction surgery, in terms of function and self-image, patient-reported outcomes still appear lower postoperatively in the domains of pain and mental health. CONCLUSION: Breast asymmetry is very common, especially among AIS patients, and is often corrected with surgical augmentation. AIS correction surgery has been shown to aggravate breast asymmetry and negatively affect patient-reported outcomes. Other treatment modalities should thus be considered when presented with an adolescent patient. Understanding patient concerns and their relation to quality of life will help guide surgical and medical interventions in correction of AIS deformities. Long-term follow-up studies are necessary to determine whether such interventions are successful and if patients remain healthy. LEVEL OF EVIDENCE: N/A.