Congenital Etiology Is an Independent Risk Factor for Complications in Adolescents Undergoing Corrective Scoliosis Surgery: Comparison of In-hospital Comorbidities Using Nationwide KID's Inpatient Database.

BACKGROUND: Congenital scoliosis (CS) is associated with more rigid, complex deformities relative to adolescent idiopathic scoliosis (AIS) which theoretically increases surgical complications. Despite extensive literature studying AIS patients, few studies have been performed on CS patients. The purpose of this study was to evaluate complications associated with spinal fusions for CS and AIS. METHODS: A retrospective review of the Kid's Inpatient Database (KID) years 2000 to 2009 was performed. Inclusion: patients under 20 years with ICD-9 diagnosis codes for idiopathic scoliosis (IS-without concomitant congenital anomalies) and CS, undergoing spinal fusion from the KID years 2000 to 2009. Two analyses were performed according to age below 10 years and 10 years and above. Univariate analysis described differences in demographics, comorbidities, intraoperative complications, and clinical values between groups. Binary logistic regression controlling for age, sex, race, and invasiveness predicted complications risk in CS (odds ratios; 95% confidence interval). RESULTS: In total, 25,131 patients included (IS, n=22443; CS, n=2688). For patients under age 10, CS patients underwent 1 level shorter fusions (P<0.001), had fewer comorbidities (P<0.001), and sustained similar complication incidence. In the 10 and over age analysis, CS patients similarly had shorter fusions, but greater comorbidities, and significantly more complications (odds ratio, 1.6; confidence interval, 1.4-1.8). CONCLUSIONS: CS patients have higher in-hospital complication rates. With more comorbidities, these patients have increased risk of sustaining procedure-related complications such as shock, infection, and Adult Respiratory Distress Syndrome. These data help to counsel patients and their families before spinal fusion. LEVEL OF EVIDENCE: Level III-retrospective review of a prospectively collected database.

Incidence of Congenital Spinal Abnormalities Among Pediatric Patients and Their Association With Scoliosis and Systemic Anomalies.

BACKGROUND: Congenital abnormalities when present, according to VACTERL theory, occur nonrandomly with other congenital anomalies. This study estimates the prevalence of congenital spinal anomalies, and their concurrence with other systemic anomalies. METHODS: A retrospective cohort analysis on Health care Cost and Utilization Project's Kids Inpatient Database (KID), years 2000, 2003, 2006, 2009 was performed. ICD-9 coding identified congenital anomalies of the spine and other body systems. OUTCOME MEASURES: Overall incidence of congenital spinal abnormalities in pediatric patients, and the concurrence of spinal anomaly diagnoses with other organ system anomalies. Frequencies of congenital spine anomalies were estimated using KID hospital-and-year-adjusted weights. Poisson distribution in contingency tables tabulated concurrence of other congenital anomalies, grouped by body system. RESULTS: Of 12,039,432 patients, rates per 100,000 cases were: 9.1 hemivertebra, 4.3 Klippel-Fiel, 56.3 Chiari malformation, 52.6 tethered cord, 83.4 spina bifida, 1.2 absence of vertebra, and 6.2 diastematomyelia. Diastematomyelia had the highest concurrence of other anomalies: 70.1% of diastematomyelia patients had at least one other congenital anomaly. Next, 63.2% of hemivertebra, and 35.2% of Klippel-Fiel patients had concurrent anomalies. Of the other systems deformities cooccuring, cardiac system had the highest concurrent incidence (6.5% overall). In light of VACTERL's definition of a patient being diagnosed with at least 3 VACTERL anomalies, hemivertebra patients had the highest cooccurrence of ≥3 anomalies (31.3%). With detailed analysis of hemivertebra patients, secundum ASD (14.49%), atresia of large intestine (10.2%), renal agenesis (7.43%) frequently cooccured. CONCLUSIONS: Congenital abnormalities of the spine are associated with serious systemic anomalies that may have delayed presentations. These patients continue to be at a very high, and maybe higher than previously thought, risk for comorbidities that can cause devastating perioperative complications if not detected preoperatively, and full MRI workups should be considered in all patients with spinal abnormalities. LEVEL OF EVIDENCE: Level III.

Fractures of the talus: Current concepts and new developments.

Fractures of the talus are challenging to manage, with historically poor outcomes and a high rate of complications. The rare nature of this injury limits the number of studies available to guide treatment. Fortunately, a number of advancements have been made in the last decade. There is increased recognition regarding the importance of anatomic reconstruction of the osseous injury. Advanced imaging is used to assess the subtalar joint, where even slight displacement may predispose to arthritis. Increasing use of dual anteromedial and anterolateral approaches, along with plate fixation, has improved our ability to accurately restore the anatomy of the talus. Modification of the original Hawkins classification can both guide treatment and allow us to better predict which patients will develop avascular necrosis. Lastly, improved reconstructive techniques help address the most common complications after talus fracture, including arthritis, avascular necrosis, and malunion.

Variation in Diagnoses for Hip Arthroplasty Among New York State Hospitals: Implications for the Comprehensive Care for Joint Replacement Model.

BACKGROUND: The Comprehensive Care for Joint Replacement model is designed to minimize costs and improve quality for Medicare patients undergoing joint arthroplasty. The cost of hip arthroplasty (HA) episode varies depending on the preoperative diagnosis and is greater for fracture than for osteoarthritis. Hospitals that perform a higher percentage of HA for OA may therefore have an advantage in the Comprehensive Care for Joint Replacement model. The purposes of this study are to (1) determine the variability in underlying diagnosis for HA in New York State hospitals, and (2) determine hospital characteristics, such as volume, associated with this. METHODS: The New York Statewide Planning and Research Cooperative System database was used to identify 127,206 primary HA procedures from 2010 to 2014. The data included underlying diagnoses, age, length of stay, and total charges. Hospitals were categorized by volume and descriptive statistics were used. RESULTS: OA was the underlying diagnosis for HA for 74.2% of all patients; this was significantly higher for high-volume (89.30%) and medium-volume (74.9%) hospitals than for low-volume hospitals (58.4%, P < .05). HA for fracture was significantly more common at low-volume hospitals (32.4%) compared to medium-volume (18.0%) and high-volume (4.7%) hospitals (P < .05). Length of stay was significantly greater at low-volume hospitals for all diagnoses. CONCLUSION: High-volume hospitals perform a higher ratio of HA cases for OA compared to fracture, which may lead to advantages in patient outcomes and cost. The variation in underlying diagnosis between hospitals has financial implications and underscores the need for HAs to be risk stratified by preoperative diagnosis.

Bone healing in 2016.

Delayed fracture healing and nonunion occurs in up to 5-10% of all fractures, and can present a challenging clinical scenario for the treating physician. Methods for the enhancement of skeletal repair may benefit patients that are at risk of, or have experienced, delayed healing or nonunion. These methods can be categorized into either physical stimulation therapies or biological therapies. Physical stimulation therapies include electrical stimulation, low-intensity pulsed ultrasonography, or extracorporeal shock wave therapy. Biological therapies can be further classified into local or systemic therapy based on the method of delivery. Local methods include autologous bone marrow, autologous bone graft, fibroblast growth factor-2, platelet-rich plasma, platelet-derived growth factor, and bone morphogenetic proteins. Systemic therapies include parathyroid hormone and bisphosphonates. This article reviews the current applications and supporting evidence for the use of these therapies in the enhancement of fracture healing.

Sports reporting: a comprehensive review of the medical literature regarding North American professional sports.

BACKGROUND: The increased physical demands of professional athletes predispose this patient population to a unique set of injuries typically not seen in the general population. This systematic literature review investigates the nature of injury reporting (both orthopedic and nonorthopedic conditions) in the medical literature of professional athletes in the National Football League (NFL), Major League Baseball (MLB), the National Basketball Association (NBA), and the National Hockey League (NHL). Rigorous reporting of sports injuries helps clinicians better understand disease mechanisms relevant to specific sports. HYPOTHESIS: The nature of injury reporting will differ within each professional sport and reflect the anatomic emphasis of each sport. METHODS: An electronic literature search of all publications addressing injuries and medical conditions among professional athletes in the NFL, MLB, NBA, and NHL was conducted using the Pubmed/Medline, Scopus, and Embase databases through January 2013. Retrieved publications were categorized by journal type, medical type, and area of focus. RESULTS: A total of 536 publications met all inclusion criteria. There were a higher number of articles regarding the NFL (n = 211) and MLB (n = 216) when compared with the NBA (n = 34) or NHL (n = 75). The NFL had significantly more articles addressing nonorthopedic injuries/medical issues than were found with the MLB, NBA, or NHL (109 vs 75, 14, 41, respectively). Both the NFL (33 of 109, 30%) and NHL (6 of 41, 15%) had a relatively high percentage of articles regarding concussions/neurology, and MLB had a relatively high percentage of articles dedicated to vascular medicine (13 of 65, 20%). The proportion of publications dedicated to the knee/lower leg were highest in the NFL (29 of 102, 28%) and NBA (9 of 20, 45%), those dedicated to the shoulder/elbow were highest in MLB (113 of 151, 75%), and those dedicated to the hip/pelvis were highest in the NHL (16 of 34, 47%). CONCLUSIONS: The number and type of publications vary among the 4 professional sports leagues, and generally reflect the nature of the sport being played.

Sports activity after total joint arthroplasty: recommendations for the counseling physician.

Sports activity after total joint arthroplasty (TJA) has become an increasingly important topic, as many younger patients seeking TJA have higher postoperative expectations with regard to return to athletic activity. Our current knowledge of this area is largely based on retrospective clinical studies and surveys of surgeon recommendations. The decision to participate in sports after TJA depends on the patient's general health, prior athletic experience, type of TJA, and desired sporting activity. Ultimately, patients should discuss these factors with their physician in order to make an educated decision regarding sports activity after TJA. This article summarizes the best available evidence to help guide physicians in their conversation with patients regarding safe and appropriate sports activity after TJA.

Predictors of Complication Severity Following Adult Spinal Deformity Surgery: Smoking Rate, Diabetes, and Osteotomy Increase Risk of Severe Adverse Events.

BACKGROUND: Given the physical and economic burden of complications in spine surgery, reducing the prevalence of perioperative adverse events is a primary concern of both patients and health care professionals. This study aims to identify specific perioperative factors predictive of developing varying grades of postoperative complications in adult spinal deformity (ASD) patients, as assessed by the Clavien-Dindo complication classification (Cc) system. METHODS: Surgical ASD patients ≥18 years were identified in the American College of Surgeons' National Surgical Quality Improvement Program from 2005 to 2015. Postoperative complications were stratified by Cc grade severity: minor (I, II, and III) and severe (IV and V). Stepwise regression models generated dataset-specific predictive models for Cc groups. Model internal validation was achieved by bootstrapping and calculating the area under the curve (AUC) of the model. Significance was set at P < 0.05. RESULTS: Included were 3936 patients (59 ± 16 years, 63% women, 29 ± 7 kg/m2) undergoing surgery for ASD (4.4 ± 4.7 levels, 71% posterior approach, 11% anterior, and 18% combined). Overall, 1% of cases were revisions, 39% of procedures involved decompression, 27% osteotomy, and 15% iliac fixation. Additionally, 66% of patients experienced at least 1 complication, 0% of which were Cc grade I, 51% II, 5% III, 43% IV, and 1% V. The final model predicting severe Cc (IV-V) complications yielded an AUC of 75.6% and included male sex, diabetes, increased operative time, central nervous system tumor, osteotomy, cigarette pack-years, anterior decompression, and anterior lumbar interbody fusion. Final models predicting specific Cc grades were created. CONCLUSIONS: Specific predictors of adverse events following ASD-corrective surgery varied for complications of different severities. Multivariate modeling showed smoking rate, osteotomy, diabetes, anterior lumbar interbody fusion, and higher operative time, among other factors, as predictive of severe complications, as classified by the Clavien-Dindo Cc system. These factors can help in the identification of high-risk patients and, consequently, improve preoperative patient counseling. CLINICAL RELEVANCE: The findings of this study provide a foundation for identifying ASD patients at high risk of postoperative complications .

Patient safety indicators from a spine surgery perspective: the importance of a specialty specific clinician working with the documentation team and the impact to your hospital.

BACKGROUND CONTEXT: The Hospital Acquired Conditions (HAC) Reduction Program supports the Centers for Medicare and Medicaid Services (CMS) effort to prevent harm to patients by providing a financial incentive to reduce HACs. HAC scores are impacted by Patient Safety Indicators (PSIs), potentially preventable hospital-related events associated with harmful patient outcomes. PSIs are identified using International Classification of Diseases (ICD) coding; however, ICD coding does not always reflect the patient's true medical course. PURPOSE: To evaluate the efficacy of and costs savings associated with a clinical documentation review process in tandem with clinician collaboration in identifying incorrectly generated PSIs. STUDY DESIGN: Retrospective chart review. PATIENT SAMPLE: All patients undergoing spine surgery at a single multi-surgeon tertiary spine center. OUTCOME MEASURES: Occurrence of PSI. METHODS: Over two 11-month periods, all PSIs attributable to spine surgery were determined. The number and type of spine related PSIs were compared before (Control) and after the implementation of a specialty specific clinical review (Intervention) to identify incorrectly generated PSIs. The financial impact of this intervention was calculated in the form of an annual cost savings to our hospital system. RESULTS: During the Control phase, 61 PSIs were reported in 3368 spine cases, representing a total of 3.6 PSIs/month. During Intervention phase, 26 PSIs in 4,482 spine cases, resulting in a statistically significant decrease of 1.5 PSIs per month. The percentage of PSIs across all surgical cases attributable to spine surgery had a statistically significant decrease during the Intervention period compared to the Control period (16% vs. 10%, p=.034), resulting in the avoidance of a 1% CMS cost reduction, an annual cost saving of approximately $3-4 million dollars per year. CONCLUSIONS: The implementation of a clinical documentation review process with clinician collaboration to ensure ICD-10 coding accurately reflects the patient's medical course leads to more accurate PSI reporting, with the potential for substantial cost-savings for hospitals from CMS reimbursement.

Robotic-assisted cortical bone trajectory (CBT) screws using the Mazor X Stealth Edition (MXSE) system: workflow and technical tips for safe and efficient use.

Robotic-assisted spine surgery has a number of potential advantages, including more precise pre-operative planning, a high degree of accuracy in screw placement, and significantly reduced radiation exposure to the surgical team. While the current primary goal of these systems is to improve the safety of spine surgery by increasing screw accuracy, there are a number of technical errors that may increase the risk of screw malposition. Given the learning curve associated with this technology, it is important for the surgeon to have a thorough understanding of all required steps. In this article, we will demonstrate the setup and workflow of a combined navigation and robotic spine surgery platform using the Mazor X Stealth Edition (MXSE) system to place cortical-based trajectory (CBT) screws, including a review of all technical tips and pearls to efficiently perform this procedure with minimal risk of screw malposition. In this article, we will review surgical planning, operating room setup, robotic arm mounting, registration, and CBT screw placement using the MXSE system.

Robotic Spine Surgery Where Did We Come From, And Where Are We Headed?

Robotic spine surgery has a number of potential advantages, including more precise preoperative planning, a high degree of accuracy in pedicle screw placement, and significantly reduced radiation exposure to the surgical team. Despite the potential advantages, many surgeons feel that it is still too early for the widespread adoption of this technology, citing increased cost, increased operating room time, and lack of necessity. Most spine surgeons will agree, however, that robotic technology is still in its infancy and that there will be a significant role for this technology in the future. Amidst this debate, it is important to understand the evolution of this technology from its initial inception to the present day, with a critical appraisal of the technology in its current form. It is important to consider the probable next steps in the development of this technology so that we may develop and shape this technology to most benefit our patients. This article reviews the history and development of robotic technology in spine surgery, critically assesses the technology in its current form, and explores the future directions.

Progranulin promotes diabetic fracture healing in mice with type 1 diabetes.

Type 1 diabetes mellitus (T1DM) is an autoimmune disease characterized by insulin deficiency, and patients with diabetes have an increased risk of bone fracture and significantly impaired fracture healing. Proinflammatory cytokine tumor necrosis factor-alpha is significantly upregulated in diabetic fractures and is believed to underlie delayed fracture healing commonly observed in diabetes. Our previous genetic screen for the binding partners of progranulin (PGRN), a growth factor-like molecule that induces chondrogenesis, led to the identification of tumor necrosis factor receptors (TNFRs) as the PGRN-binding receptors. In this study, we employed several in vivo models to ascertain whether PGRN has therapeutic effects in diabetic fracture healing. Here, we report that deletion of PGRN significantly delayed bone fracture healing and aggravated inflammation in the fracture models of mice with T1DM. In contrast, recombinant PGRN effectively promoted diabetic fracture healing by inhibiting inflammation and enhancing chondrogenesis. In addition, both TNFR1 proinflammatory and TNFR2 anti-inflammatory signaling pathways are involved in PGRN-stimulated diabetic fracture healing. Collectively, these findings illuminate a novel understanding concerning the role of PGRN in diabetic fracture healing and may have an application in the development of novel therapeutic intervention strategies for diabetic and other types of impaired fracture healing.

Bariatric Surgery Population at Significantly Increased Risk of Spinal Disorders and Surgical Intervention Compared With Morbidly Obese Patients.

INTRODUCTION: Obesity is associated with acceleration of musculoskeletal degenerative diseases and functional impairment secondary to spinal disorders. Bariatric surgery (BS) is an increasingly common treatment for severe obesity but can affect bone and mineral metabolism. The effect of BS on degenerative spinal disorders is yet to be fully described. The aim of our study was to analyze changes in bariatric patients' risk for spinal degenerative diseases and spinal surgery. METHODS: Retrospective analysis of the prospectively collected New York State Inpatient Database (NYSID) years (2004-2013) using patient linkage codes. The incidence of degenerative spinal diagnoses and spinal surgery was queried using International Classification of Diseases, Ninth Revision (ICD)-9 codes for morbidly obese patients (ICD-9 278.01) with and without a history of BS. The incidence of degenerative spinal diagnoses and spinal surgery was determined using χ tests for independence. Logistic testing controlled for age, sex, and comorbidity burden. RESULTS: A total of 18,176 patients were identified in the NYSID database with a history of BS and 146,252 patients were identified as morbidly obese without a history of BS. BS patients have a significantly higher rate of spinal diagnoses than morbidly obese patients without BS (19.3% vs. 8.1%, P<0.001). Bariatric patients were more likely to have spinal diagnoses and procedures than nonbariatric obese patients (P<0.001). This was mostly observed in lumbar spinal stenosis (5.0%), cervical disk herniation (3.3%), lumbar disk degeneration (3.4%), lumbar spondylolisthesis (2.9%), lumbar spondylosis (1.9%), and cervical spondylosis with myelopathy (2.0%). Spine procedure rates are higher for bariatric patients than nonbariatric overall (25.6% vs. 2.3, P<0.001) and for fusions and decompressions (P<0.001). When controlling for age, sex, and comorbidities (and diagnosis rate with regards to procedure rates), these results persist, with BS patients having a higher likelihood of spinal diagnoses and procedures. In addition, bariatric patients had a lower comorbidity burden than morbidly obese patients without a history of BS. CONCLUSIONS: Morbidly obese BS patients have a dramatically higher incidence of spinal diagnoses and procedures, relative to morbidly obese patients without BS. Further study is necessary to determine if there is a pathophysiological mechanism underlying this higher risk of spinal disease and intervention in bariatric patients, and the effect of BS on these rates following treatment. LEVEL OF EVIDENCE: Level III.

Predictors of Hospital-Acquired Conditions Are Predominately Similar for Spine Surgery and Other Common Elective Surgical Procedures, With Some Key Exceptions.

STUDY DESIGN: Retrospective review of a prospectively collected database. OBJECTIVE: To predict the occurrence of hospital-acquired conditions (HACs) 30-days postoperatively and to compare predictors of HACs for spine surgery with other common elective surgeries. METHODS: Patients ≥18 years undergoing elective spine surgery were identified in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2005 to 2013. Outcome measures included any HACs: superficial or deep surgical site infection (SSI), venous thromboembolism (VTE), urinary tract infection (UTI). Spine surgery patients were compared with those undergoing other common procedures. Random forest followed by multivariable regression analysis was used to determine risk factors for the occurrence of HACs. RESULTS: A total of 90 551 elective spine surgery patients, of whom 3021 (3.3%) developed at least 1 HAC, 1.4% SSI, 1.3% UTI, and 0.8% VTE. The occurrence of HACs for spine patients was predicted with high accuracy (area under the curve [AUC] 77.7%) with the following variables: female sex, baseline functional status, hypertension, history of transient ischemic attack (TIA), quadriplegia, steroid use, preoperative bleeding disorders, American Society of Anesthesiologists (ASA) class, operating room duration, operative time, and level of residency supervision. Functional status and hypertension were HAC predictors for total knee arthroplasty (TKA), bariatric, and cardiothoracic patients. ASA class and operative time were predictors for most surgery cohorts. History of TIA, preoperative bleeding disorders, and steroid use were less predictive for most other common surgical cohorts. CONCLUSIONS: Occurrence of HACs after spine surgery can be predicted with demographic, clinical, and surgical factors. Predictors for HACs in surgical spine patients, also common across other surgical groups, include functional status, hypertension, and operative time. Understanding the baseline patient risks for HACs will allow surgeons to become more effective in their patient selection for surgery.

Surgical Accuracy of an Early Intervention Knee Implant Instrumentation System.

Accuracy of component and limb alignment are critical parameters for the long-term success of unicompartmental knee implants. In this study, we performed a laboratory evaluation of an instrumentation system which was designed for an early intervention (EI) type of unicompartmental knee. The accuracy of fit was evaluated by implanting in 20 sawbones full leg models. The overall alignment of the limb was compared pre- and postoperatively. The accuracy of placement of each component on its bone was measured. The mean overall alignment angle in the frontal plane was within 1° of target with less than 1° standard deviation. The components were positioned in frontal and sagittal planes with maximum errors of 2°. The angular accuracy was better than in studies reported in the literature for manual instruments, and almost approached the accuracy of computer-assisted systems. The position of the femoral component in the recess was within 1 mm in most cases but the sagittal flexion angle was variable with a standard deviation of 6°. Evaluation of a surgical technique in this way was a valuable method for determining accuracy and for highlighting any deficiencies in the system which could then be corrected.

Topical vancomycin and its effect on survival and migration of osteoblasts, fibroblasts, and myoblasts: An in vitro study.

The purpose of this study was to examine the influence of topical vancomycin on cell migration and survival of tissue healing cells. Human osteoblasts, myoblasts and fibroblasts were exposed to vancomycin at concentrations of 1, 3, 6, or 12 mg/cm2 for either a 1-h or 48-h (continuous) duration. Continuous exposure to all vancomycin concentrations significantly reduced cell survival (<22% cells survived) and migration in osteoblasts and myoblasts (P < 0.001). 1-h vancomycin exposure reduced osteoblast and myoblast survival and migration only at 12 mg/cm2 (P < 0.001). Further in vivo studies are warranted to optimize the dosage of intrawound vancomycin.

Two-Year Results of the Prospective Spine Treatment Outcomes Study: Analysis of Postoperative Clinical Outcomes Between Patients with and without a History of Previous Cervical Spine Surgery.

OBJECTIVE: History of previous cervical spine surgery is a frequently cited cause of worse outcomes after cervical spine surgery. The purpose of this study was to determine any differences in clinical outcomes after cervical spine surgery between patients with and without a history of previous cervical spine surgery. METHODS: A multicenter prospective database was reviewed retrospectively to identify patients with cervical spondylosis undergoing surgery with a minimum 2-year follow-up. Patients were divided into 2 groups: patients with (W) or without (WO) previous history of cervical spine surgery. Statistical analyses of Health-Related Quality of Life scores were analyzed with statistical software to fit linear mixed models for continuous longitudinal outcome. RESULTS: A total of 1286 patients (377 W, 909 WO) met criteria for inclusion. Overall, patients in both groups experienced an improvement in their Health-Related Quality of Life scores. However, patients in the W group had significantly decreased improvement compared with WO patients in the Neck Disability Index score and the following SF-36 domain scores: Role Physical, Bodily Pain, General Health, Vitality, Social Functioning, Health Transition, and Physical Component Summary at all time points (P < 0.05). There was no statistically significant difference between the W and WO groups in operative time, estimated blood loss, length of stay, or complications (P > 0.05). CONCLUSIONS: Patients with a history of previous cervical spine surgery had inferior improvement in quality of life outcome scores. Patients with a history of previous surgical intervention who elect to undergo subsequent surgeries should be appropriately counseled about expected results.

Mechanisms of anterior-posterior stability of the knee joint under load-bearing.

The anterior-posterior (AP) stability of the knee is an important aspect of functional performance. Studies have shown that the stability increases when compressive loads are applied, as indicated by reduced laxity, but the mechanism has not been fully explained. A test rig was designed which applied combinations of AP shear and compressive forces, and measured the AP displacements relative to the neutral position. Five knees were evaluated at compressive loads of 0, 250, 500, and 750N, with the knee at 15° flexion. At each load, three cycles of shear force at ±100N were applied. For the intact knee under load, the posterior tibial displacement was close to zero, due to the upward slope of the anterior medial tibial surface. The soft tissues were then resected in sequence to determine their role in AP laxity. After anterior cruciate ligament (ACL) resection, the anterior tibial displacement increased significantly even under load, highlighting its importance in stability. Meniscal resection further increased displacement but also the vertical displacement increased, implying the meniscus was providing a buffering effect. The PCL had no effect on any of the displacements under load. Plowing cartilage deformation and surface friction were negligible. This work highlighted the particular importance of the upward slope of the anterior medial tibial surface and the ACL to AP knee stability under load. The results are relevant to the design of total knees which reproduce anatomic knee stability behavior.

The Regionalization of Total Ankle Arthroplasties and Ankle Fusions in New York State: A 10-Year Comparative Analysis.

BACKGROUND: Total ankle arthroplasty (TAA) provides an alternative to ankle fusion (AF). The purpose of this study is to (1) determine the extent of TAA regionalization, as well as examine the growth of TAA performed at high-, medium-, and low-volume New York State institutions and (2) compare this regionalization and growth with AF. METHODS: The New York Statewide Planning and Research Cooperative System (SPARCS) administrative data were used to identify 737 primary TAA and 7453 AF from 2005 to 2014. The volume of TAA and AF surgery in New York State was mapped according to patient and hospital 3-digit zip code. RESULTS: The number of TAA per year grew 1500% (from 11 to 177) from 2005 to 2014, while there was a 35.6% reduction (from 895 to 576) in yearly AF procedures. TAA recipients were widely distributed throughout the state, while TAA procedures were regionalized to a few select metropolitan centers. AF procedures were performed more uniformly than TAA. The number of TAA has continued to increase at high- (15 to 91) and medium-volume (14 to 67) institutions where it has decreased at low-volume institutions (44 to 19). CONCLUSION: The increased utilization of TAA is attributed to relatively few high-volume centers located in major metropolitan centers. LEVELS OF EVIDENCE: Level IV: well-designed case-control or cohort studies.

Surgically­induced mouse models in the study of bone regeneration: Current models and future directions (Review).

Bone regeneration has been extensively studied over the past several decades. The surgically­induced mouse model is the key animal model for studying bone regeneration, of the various research strategies used. These mouse models mimic the trauma and recovery processes in vivo and serve as carriers for tissue engineering and gene modification to test various therapies or associated genes in bone regeneration. The present review introduces a classification of surgically induced mouse models in bone regeneration, evaluates the application and value of these models and discusses the potential development of further innovations in this field in the future.