James X. Liu

Intensive ketamine use for multiple years: A case report

Ketamine is known within the medical field for its anesthetic properties, yet its unique psychedelic and antidepressant properties are being increasingly recognized. We document the case of a patient with bipolar I disorder and an extensive history of substance dependence who used large doses of ketamine (1-3 g) on a daily basis over a period of 5 years, and described acute antidepressant effects as well as diminished cravings for alcohol. While his use was untenable and ultimately led to an inpatient admission, it is notable that he did not experience a withdrawal syndrome nor did he have any observable cognitive deficits upon cessation of use. Such a unique drug profile suggests that further exploration of its risks and therapeutic potential in treating mood and addiction disorders is warranted. (Am J Addict 2014;XX:1-3).

F-Spondin Deficient Mice Have a High Bone Mass Phenotype

F-spondin is a pericellular matrix protein upregulated in developing growth plate cartilage and articular cartilage during osteoarthritis. To address its function in bone and cartilage in vivo, we generated mice that were deficient for the F-spondin gene, Spon1. Spon1 − /− mice were viable and developed normally to adulthood with no major skeletal abnormalities. At 6 months, femurs and tibiae of Spon1 − /− mice exhibited increased bone mass, evidenced by histological staining and micro CT analyses, which persisted up to 12 months. In contrast, no major abnormalities were observed in articular cartilage at any age group. Immunohistochemical staining of femurs and tibiae revealed increased levels of periostin, alkaline phosphate and tartrate resistant acid phosphatase (TRAP) activity in the growth plate region of Spon1 − /− mice, suggesting elevated bone synthesis and turnover. However, there were no differences in serum levels of TRAP, the bone resorption marker, CTX-1, or osteoclast differentiation potential between genotypes. Knockout mice also exhibited reduced levels of TGF-β1 in serum and cultured costal chondrocytes relative to wild type. This was accompanied by increased levels of the BMP-regulatory SMADs, P-SMAD1/5 in tibiae and chondrocytes. Our findings indicate a previously unrecognized role for Spon1 as a negative regulator of bone mass. We speculate that Spon1 deletion leads to a local and systemic reduction of TGF-β levels resulting in increased BMP signaling and increased bone deposition in adult mice.

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.

Clinical Aspects of Fracture Healing: An Overview

The assessment, diagnosis, and management of fractures, particularly fractures that exhibit delayed healing, present considerable unique challenges to both patients and physicians. Fracture healing results from a complex series of biochemical events that may produce complete restoration of the anatomic and biochemical properties of the original osseous tissue. Fracture healing requires appropriate reduction, mechanical stability, and adequate vascularity to the fracture site; compromise of one of these elements may lead to delayed healing or nonunion. The patient’s history, physical examination, and findings based on radiographs or other imaging modalities allow for assessment and characterization of the progression of healing. If nonunion is recognized, it is important for the clinician to understand the current treatment options that are available to optimize healing. Physical stimulation therapies include electromagnetic stimulation and low-intensity pulsed ultrasonography. Osteogenic factors used locally to promote fracture healing include autologous bone marrow and peptide signaling molecules such as platelet-derived growth factors, fibroblast growth factors, and bone morphogenetic proteins. Systemic biological protein such as parathyroid hormone and factors that target the Wnt family of signaling molecules offers promising data regarding its abilities to promote healing. Large segmental defects must be managed depending on the type and severity of the injury and may require treatment with bone grafts, induced membrane techniques, acute shortening, or distraction osteogenesis. A systematic approach in evaluating fracture union and an understanding of the modern methods to promote fracture healing will allow clinicians to significantly improve the treatment of patients with these injuries.

Preoperative Bariatric Surgery and the Risk of Readmission Following Total Joint Replacement

The purpose of this study was to compare nonelective and all-cause readmission rates and to identify risk factors for readmission of total joint arthroplasty (TJA) patients who had preoperative bariatric surgery (BS) compared with TJA patients without preoperative BS. The New York Statewide Planning and Research Cooperative System database was queried to identify 343,710 TJA patients between 2005 and 2014. Three patient groups were evaluated: group 1 (patients with preoperative BS within 2 years of TJA [N=1478]); group 2 (obese patients without preoperative BS [N=60,259]); and group 3 (nonobese patients without preoperative BS [N=281,973]). Nonelective and all-cause readmission rates (30 days, 90 days, and 1 year) were compared, and multivariate analyses of readmission risk factors were performed. Group 1 had no significant difference in nonelective readmission rates compared with groups 2 and 3. However, when elective TJA readmissions were included, group 1 had significantly higher all-cause readmission rates at 30 days, 90 days, and 1 year compared with groups 2 and 3. Bariatric surgery was not a risk factor for nonelective readmissions at any time point. When elective TJA admissions were included, BS was an independent risk factor for all-cause readmission at all time points. Patients who have BS prior to TJA do not have higher nonelective readmission rates than obese TJA patients without BS. Bariatric surgery is not a risk factor for nonelective readmissions. However, BS is a significant predictor of elective TJA admissions up to 1 year following the index TJA. [Orthopedics. 2018; 41(2):107-114.].

Surgical Accuracy of an Early Intervention Knee Implant Instrumentation System

&NA; 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.

Cytotoxicity evaluation of chlorhexidine gluconate on human fibroblasts, myoblasts, and osteoblasts

Introduction: Chlorhexidine gluconate (CHX) is widely used as a preoperative surgical skin-preparation solution and intra-wound irrigation agent, with excellent efficacy against wide variety of bacteria. The cytotoxic effect of CHX on local proliferating cells following orthopaedic procedures is largely undescribed. Our aim was to investigate the in vitro effects of CHX on primary fibroblasts, myoblasts, and osteoblasts. Methods: Cells were exposed to CHX dilutions (0%, 0.002%, 0.02%, 0.2%, and 2%) for either a 1, 2, or 3-minute duration. Cell survival was measured using a cytotoxicity assay (Cell Counting Kit-8). Cell migration was measured using a scratch assay: a “scratch” was made in a cell monolayer following CHX exposure, and time to closure of the scratch was measured. Results: All cells exposed to CHX dilutions of ≥ 0.02% for any exposure duration had cell survival rates of less than 6% relative to untreated controls (p < 0.001). Cells exposed to CHX dilution of 0.002% all had significantly lower survival rates relative to control (p < 0.01) with the exception of 1-minute exposure to fibroblasts, which showed 96.4% cell survival (p = 0.78). Scratch defect closure was seen in < 24 hours in all control conditions. However, cells exposed to CHX dilutions ≥ 0.02% had scratch defects that remained open indefinitely. Conclusions: The clinically used concentration of CHX (2%) permanently halts cell migration and significantly reduces survival of in vitro fibroblasts, myoblasts, and osteoblasts. Further in vivo studies are required to examine and optimize CHX safety and efficacy when applied near open incisions or intra-wound application.

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