Resolution of Historically Discordant Ames Test Negative / Rodent Carcinogenicity Positive N-nitrosamines using a Sensitive, OECD-aligned Design.

The in vitro Bacterial Reverse Mutation (Ames) Test is crucial for evaluating the mutagenicity of pharmaceutical impurities. For N-nitrosamines (NAs) historical data indicated that for certain members of this chemical class the outcomes of the Ames Test did not correlate with their associated rodent carcinogenicity outcomes. This has resulted in negative outcomes in an OECD aligned Ames Test alone (standard or enhanced) no longer being considered sufficient by regulatory authorities to assess potential carcinogenic risk of NAs if present as impurities in drug products.

Vascular complications after a multiligament knee reconstruction: A case report highlighting the role of preoperative imaging.

Vascular injuries are serious complications of multiligament knee injuries and can result in catastrophic outcomes. These injuries can range from intimal flaps with no compromise of the distal perfusion to a complete occlusion or transection requiring emergent vascular intervention. Several diagnostic tests, including the measurement of the ankle-brachial index (ABI), conventional angiography, and computed tomography angiography (CTA), are commonly used as diagnostic tools to identify vascular injuries in the context of a multiligament knee injury.

Should my recommendation letter be written by artificial intelligence?

Letters of recommendation are increasingly important for the residency match. We assessed whether an artificial intelligence (AI) tool could help in writing letters of recommendation by analyzing recommendation letters written by 3 academic staff and AI duplicate versions for 13 applicants. The preferred letters were selected by 3 blinded orthopedic program directors based on a pre-determined set of criteria.

N-Nitrosodimethylamine investigations in Muta™Mouse define point-of-departure values and demonstrate less-than-additive somatic mutant frequency accumulations.

The N-nitrosamine, N-nitrosodimethylamine (NDMA), is an environmental mutagen and rodent carcinogen. Small levels of NDMA have been identified as an impurity in some commonly used drugs, resulting in several product recalls. In this study, NDMA was evaluated in an OECD TG-488 compliant Muta™Mouse gene mutation assay (28-day oral dosing across seven daily doses of 0.

Ames test study designs for nitrosamine mutagenicity testing: qualitative and quantitative analysis of key assay parameters.

The robust control of genotoxic N-nitrosamine (NA) impurities is an important safety consideration for the pharmaceutical industry, especially considering recent drug product withdrawals. NAs belong to the 'cohort of concern' list of genotoxic impurities (ICH M7) because of the mutagenic and carcinogenic potency of this chemical class. In addition, regulatory concerns exist regarding the capacity of the Ames test to predict the carcinogenic potential of NAs because of historically discordant results.

Arthroscopic management of synovial chondromatosis of the shoulder: a systematic review of literature.

Background: Synovial chondromatosis (SC) of the shoulder is rare, with limited literature on its management. This systematic review of literature aimed to characterize common arthroscopic techniques for the treatment of shoulder SC and patient outcomes. We hypothesized that arthroscopy is an effective operative modality for the management of shoulder SC.

A Prediction Model for Primary Anterior Cruciate Ligament Injury Using Artificial Intelligence.

Background: Supervised machine learning models in artificial intelligence (AI) have been increasingly used to predict different types of events. However, their use in orthopaedic surgery has been limited.

Hypothesis: It was hypothesized that supervised learning techniques could be used to build a mathematical model to predict primary anterior cruciate ligament (ACL) injuries using a set of morphological features of the knee.

Arthroscopic Management for Bipartite Patella: A Systematic Review.

Background: Bipartite patella is a rare congenital condition that becomes painful following direct trauma or an overuse injury. If it remains painful despite nonoperative treatment, surgery may be warranted. The current gold standard is open fragment excision or lateral release; however, arthroscopic management is also possible.

Endoscopic fasciotomy for chronic exertional compartment syndrome of the forearm: Systematic review of outcomes and complications.

Background: Endoscopic fasciotomy of the forearm for chronic exertional compartment syndrome (CECS) has gained popularity recently.

Aim: To systematically review the literature of endoscopic fasciotomy for CECS of the forearm, aiming to assess the outcomes and complications of the different endoscopic fasciotomy techniques described in the literature.

Methods: On January 18, 2021, PubMed and EMBASE were searched by 3 reviewers independently, and all relevant studies published up to that date were considered based on predetermined inclusion/exclusion criteria.

A Quantifiable Risk Factor for ACL Injury: Applied Mathematics to Model the Posterolateral Tibial Plateau Surface Geometry.

Background: The mechanism for traumatic ruptures of the native anterior cruciate ligament (ACL) is frequently a noncontact injury involving a valgus moment with internal rotation of the tibia. The abnormal rotation and translation of the lateral femoral condyle posteroinferiorly relative to the lateral tibial plateau is thought to be related to the geometry of the tibial plateau.

Purpose/hypothesis: The purpose of the study was to mathematically model the posterior tibial plateau geometry in patients with ACL injuries and compare it with that of matched controls.

Lateral Meniscus Height and ACL Reconstruction Failure: A Nested Case-Control Study.

Previous work has shown that the morphology of the knee joint is associated with the risk of primary anterior cruciate ligament (ACL) injury. The objective of this study is to analyze the effect of the meniscal height, anteroposterior distance of the lateral tibial plateau, and other morphological features of the knee joint on risk of ACL reconstruction failure. A nested case-control study was conducted on patients who underwent an ACL reconstruction surgery during the period between 2008 and 2015.

An Arthroscopic Procedure for Restoration of Posterolateral Tibial Plateau Slope in Tibial Plateau Fracture Associated With Anterior Cruciate Ligament Injuries.

High-energy anterior cruciate ligament (high-energy ACL) injury, occurring in high-energy rotatory trauma of the knee, can accompany a unique fracture pattern that involves depression of the slope of the posterolateral tibial plateau (PLTP). These injuries are challenging to manage due to the lack of a gold-standard arthroscopic procedure that addresses both ACL deficiency and depressed PLTP slope. In such injuries, a one-stage approach may be used to (1) reconstruct the ACL or (2) reduce and fix the avulsed tibial spine, while concomitantly performing an arthroscopy-assisted reduction of a PLTP fracture that restores the anatomic slope of the tibial plateau.

Can Surgeons Identify ACL Femoral Ridges Landmark and Optimal Tunnel Position? A 3D Model Study.

Purpose: To examine the ability of surgeons to identify the osseous landmarks associated with the femoral anterior cruciate ligament (ACL) footprint and locate optimal tunnel placement on 3-dimensional (3D) printed models compared with intraoperative placement.

Methods: Twelve sports fellowship-trained orthopaedic surgeons were asked to identify a femoral landmark and an ACL footprint on 10 different 3D printed knees. The 3D models were made based on 20 real patients with different anatomical morphology who later received ACL reconstructive surgery using independent drilling.

Three-Dimensional Magnetic Resonance Imaging for Guiding Tibial and Femoral Tunnel Position in Anterior Cruciate Ligament Reconstruction: A Cadaveric Study.

Background: Femoral and tibial tunnel malposition for anterior cruciate ligament (ACL) reconstruction (ACLR) is correlated with higher failure rate. Regardless of the surgical technique used to create ACL tunnels, significant mismatches between the native and reconstructed footprints exist.

Purpose: To compare the position of tunnels created by a standard technique with the ones created based on preoperative 3-dimensional magnetic resonance imaging (3D MRI) measurements of the ACL anatomic footprint.

Effect of Teaching Session on Resident Ability to Identify Anatomic Landmarks and Anterior Cruciate Ligament Footprint: A Study Using 3-Dimensional Modeling.

Background: Femoral tunnel positioning in anterior cruciate ligament reconstruction (ACLR) is an intricate procedure that requires highly specific surgical skills.

Purpose: To report the ability of residents to identify femoral landmarks and the native ACL footprint before and after a structured formal teaching session as a reflection of overall surgical skill training for orthopaedic surgery residents in Canada.

Study Design: Controlled laboratory study.

Evaluating the Accuracy of Tibial Tunnel Placement After Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction.

Background: Anatomic anterior cruciate ligament (ACL) reconstruction improves knee kinematics and joint stability in symptomatic patients who have ACL deficiency. Despite a concerted effort to place the graft within the ACL's native attachment sites, the accuracy of tunnel placement using contemporary techniques is not well established.

Purpose: To use 3-dimensional magnetic resonance imaging (3D MRI) to prospectively evaluate the accuracy of tibial tunnel placement after anatomic ACL reconstruction.

Knee Arthroscopy for the Treatment of Lipoma Arborescens: A Systematic Review of the Literature.

Background: Lipoma arborescens is a rare, intra-articular benign lesion characterized by hyperplastic formation of villous projections that commonly presents as nonspecific mechanical knee pain. The treatment of choice for lipoma arborescens of the knee is open or arthroscopic synovectomy. However, data are lacking on the success of arthroscopic treatment, despite its increasingly widespread use.

Comparing external and internal validation methods in correcting outcome misclassification bias in logistic regression: A simulation study and application to the case of postsurgical venous thromboembolism following total hip and knee arthroplasty.

Purpose: We assessed the validity of postsurgery venous thromboembolism (VTE) diagnoses identified from administrative databases and compared Bayesian and multiple imputation (MI) approaches in correcting for outcome misclassification in logistic regression models.

Methods: Sensitivity and specificity of postsurgery VTE among patients undergoing total hip or knee replacement (THR/TKR) were assessed against chart review in six Montreal hospitals in 2009 to 2010. Administrative data on all THR/TKR Quebec patients in 2009 to 2010 were obtained.

A Prospective Evaluation of Femoral Tunnel Placement for Anatomic Anterior Cruciate Ligament Reconstruction Using 3-Dimensional Magnetic Resonance Imaging.

Background: The recent emphasis on anatomic reconstruction of the anterior cruciate ligament (ACL) is well supported by clinical and biomechanical research. Unfortunately, the location of the native femoral footprint can be difficult to see at the time of surgery, and the accuracy of current techniques to perform anatomic reconstruction is unclear.

Purpose: To use 3-dimensional magnetic resonance imaging (3D MRI) to prospectively evaluate patients with torn ACLs before and after reconstruction and thereby assess the accuracy of graft position on the femoral condyle.

Drill wobble - effect on femoral tunnel aperture during anterior cruciate ligament reconstruction.

Background: In anterior cruciate ligament reconstruction performed using cortical button fixation on the femur, we have observed a "wobble" effect that can occur when a cannulated femoral drill is used over a guide pin that is not securely fixed in bone. Our study assessed the effect of drill "wobble" on femoral tunnel aperture in sawbones.

Methods: Femoral tunnels were drilled in sawbones, which had been divided in two groups of 10 each, per drilling technique.

Joint line fullness and meniscal pathology.

Background: Meniscal tears have been associated with meniscal cysts and fullness of the knee joint line on physical examination.

Hypothesis: Joint line fullness is an accurate, sensitive, and specific test to detect meniscal tears.

Study Design: Prospective cohort study.

The effects of chlorhexidine graft decontamination on tendon graft collagen and cell viability.

Background: Chlorhexidine (CLX) has been reported as a popular and effective disinfectant of contaminated tendon grafts with no biomechanical sequelae; however, its biochemical effects on tendon collagen and fibroblasts remain unknown.

Purpose: To determine whether CLX disinfection of contaminated tendon grafts has deleterious effects on tendon collagen or a toxic effect on fibroblast function.

Study Design: Controlled laboratory study.

Isolated supraspinatus muscle atrophy and fatty infiltration associated with recurrent anterior shoulder instability: A case report and review of the literature.

Supraspinatus muscle atrophy and fatty infiltration are two distinct muscle abnormalities which can be seen after a chronic massive tear or suprascapular neuropathy. Isolated supraspinatus muscle denervation due to suprascapular nerve injury after shoulder dislocation is extremely rare. We report on a patient who developed isolated supraspinatus muscle atrophy and fatty infiltration after traumatic anterior shoulder instability.