Antibody gene transfer with adeno-associated viral vectors as a method for HIV prevention.

Broadly neutralizing antibodies (bNAbs) against human immunodeficiency virus (HIV) show great promise in HIV prevention as they are capable of potently neutralizing a considerable breadth of genetically diverse strains. Passive transfer of monoclonal bNAb proteins can confer protection in animal models of HIV infection at modest concentrations, inspiring efforts to develop an HIV vaccine capable of eliciting bNAb responses. However, these antibodies demonstrate high degrees of somatic mutation and other unique characteristics that may hinder the ability of conventional approaches to consistently and effectively produce bNAb analogs. As an alternative strategy, we and others have proposed vector-mediated gene transfer to generate long-term, systemic production of bNAbs in the absence of immunization. Herein, we review the use of adeno-associated virus (AAV) vectors for delivery of HIV bNAbs and antibody-like proteins and summarize both the advantages and disadvantages of this strategy as a method for HIV prevention.

Cerebral organoids derived from Sandhoff disease-induced pluripotent stem cells exhibit impaired neurodifferentiation.

Sandhoff disease, one of the GM2 gangliosidoses, is a lysosomal storage disorder characterized by the absence of ß-hexosaminidase A and B activity and the concomitant lysosomal accumulation of its substrate, GM2 ganglioside. It features catastrophic neurodegeneration and death in early childhood. How the lysosomal accumulation of ganglioside might affect the early development of the nervous system is not understood. Recently, cerebral organoids derived from induced pluripotent stem (iPS) cells have illuminated early developmental events altered by disease processes. To develop an early neurodevelopmental model of Sandhoff disease, we first generated iPS cells from the fibroblasts of an infantile Sandhoff disease patient, then corrected one of the mutant HEXB alleles in those iPS cells using CRISPR/Cas9 genome-editing technology, thereby creating isogenic controls. Next, we used the parental Sandhoff disease iPS cells and isogenic HEXB-corrected iPS cell clones to generate cerebral organoids that modeled the first trimester of neurodevelopment. The Sandhoff disease organoids, but not the HEXB-corrected organoids, accumulated GM2 ganglioside and exhibited increased size and cellular proliferation compared with the HEXB-corrected organoids. Whole-transcriptome analysis demonstrated that development was impaired in the Sandhoff disease organoids, suggesting that alterations in neuronal differentiation may occur during early development in the GM2 gangliosidoses.

Anisometry of Medial Patellofemoral Ligament Reconstruction in the Setting of Increased Tibial Tubercle-Trochlear Groove Distance and Patella Alta.

PURPOSE: To assess the impact elevated tibial tubercle-trochlear groove (TT-TG) distance and patella height, as measured by the Caton-Deschamps Index (CDI), have on the isometry of a reconstructed medial patellofemoral ligament (MPFL). METHODS: Nine fresh-frozen cadaveric knees were placed on a custom testing fixture, with a fixed femur and a mobile tibia. A suture fixed to the MPFL origin on the patella and free to move at the Schöttle point on the femur represented a reconstructed MPFL. A local coordinate system was established, and retroreflective markers attached to the suture quantified MPFL length changes by use of a 3-dimensional motion capture system. The tubercle was transferred to create TT-TG distances of 20 mm and 25 mm and CDIs of 1.2 and 1.4 (patella alta). Recordings of the MPFL suture length change as the knee was brought through a range of motion were made using all combinations of tubercle anatomy in a randomized order for each specimen. A generalized estimating equation modeling technique was used to analyze and control for the clustered nature of the data. RESULTS: Knees with native tibial tubercle anatomy showed MPFL isometry through 20° to 70° range of motion. Tibial tubercle lateralization (increased TT-TG distance) significantly altered MPFL isometry with a TT-TG distance of 20 mm (P < .0001). Patella alta significantly altered MPFL isometry with a CDI of 1.2 (P = .0182). The interaction of tibial tubercle lateralization combined with patella alta significantly increased the amount of anisometry seen in the reconstructed MPFL (P < .001). CONCLUSIONS: Increased tibial tubercle lateralization and patella alta produce anisometry in an MPFL reconstruction using currently recommended landmarks, leading to potentially increased graft tension and potential failure. CLINICAL RELEVANCE: Tibial tubercle transfer should be considered when performing an MPFL reconstruction for recurrent patellofemoral instability in the setting of significant patella alta and an elevated TT-TG distance-especially when both are present-because an isolated MPFL reconstruction will be prone to failure given the anisometry shown in this study.

Magnetic Resonance Imaging Validation of Tibial Tubercle Transfer Distance in the Fulkerson Osteotomy: A Clinical and Cadaveric Study.

PURPOSE: To validate the medialization and anteriorization distances, and the osteotomy angle of anteromedialization tibial tubercle osteotomies using postoperative axial imaging. METHODS: From March 2004 to August 2015, 117 consecutive patients who underwent anteromedialization osteotomies of the tibial tubercle by a single surgeon were identified. Only patients with pre- and postoperative magnetic resonance imaging (MRI) studies were included. Using MRI multiplanar reformats, distances that the tibial tubercle was translated medially (medialization) and anteriorly (anteriorization) were measured. In addition, the osteotomy angle was measured on the postoperative MRI. The measured values were compared with intraoperative estimates. Tibial tubercle osteotomies were then performed on 3 cadaveric knee specimens and imaged with pre- and postprocedure MRIs to correlate intraoperative measurements with MRI findings. RESULTS: A total of 40 patients (41 knees) (34.2%) had both pre- and postoperative MRIs and were included. Compared with intraoperative assessment, MRI measured medialization values average 94.7% (standard deviation [SD] 37.7) of dictated values (P = .1). MRI measured anteriorization averaged less than half of dictated values (48.9%, SD 18.2%, P < .0001). MRI measured osteotomy angles averaged 67.2% of dictated values (SD 50.3%, P < .0001). The steepest osteotomy angle that could be performed without violating the posterior cortex and/or endangering the posterior neurovascular structures was 46.3°. CONCLUSIONS: Surgeons often overestimate both the anteriorization distance and the osteotomy angle in anteromedialization tibial tubercle osteotomies. The steepest osteotomy angle is less than the 60° described in the literature. Modifications should be considered when more anteriorization is desired with tubercle transfers. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Wearable Inertial Sensors Allow for Quantitative Assessment of Shoulder and Elbow Kinematics in a Cadaveric Knee Arthroscopy Model.

PURPOSE: To develop a model using wearable inertial sensors to assess the performance of orthopaedic residents while performing a diagnostic knee arthroscopy. METHODS: Fourteen subjects performed a diagnostic arthroscopy on a cadaveric right knee. Participants were divided into novices (5 postgraduate year 3 residents), intermediates (5 postgraduate year 4 residents), and experts (4 faculty) based on experience. Arm movement data were collected by inertial measurement units (Opal sensors) by securing 2 sensors to each upper extremity (dorsal forearm and lateral arm) and 2 sensors to the trunk (sternum and lumbar spine). Kinematics of the elbow and shoulder joints were calculated from the inertial data by biomechanical modeling based on a sequence of links connected by joints. Range of motion required to complete the procedure was calculated for each group. Histograms were used to compare the distribution of joint positions for an expert, intermediate, and novice. RESULTS: For both the right and left upper extremities, skill level corresponded well with shoulder abduction-adduction and elbow prono-supination. Novices required on average 17.2° more motion in the right shoulder abduction-adduction plane than experts to complete the diagnostic arthroscopy (P = .03). For right elbow prono-supination (probe hand), novices required on average 23.7° more motion than experts to complete the procedure (P = .03). Histogram data showed novices had markedly more variability in shoulder abduction-adduction and elbow prono-supination compared with the other groups. CONCLUSIONS: Our data show wearable inertial sensors can measure joint kinematics during diagnostic knee arthroscopy. Range-of-motion data in the shoulder and elbow correlated inversely with arthroscopic experience. Motion pattern-based analysis shows promise as a metric of resident skill acquisition and development in arthroscopy. CLINICAL RELEVANCE: Wearable inertial sensors show promise as metrics of arthroscopic skill acquisition among residents.

The Tibial Tubercle-to-Trochlear Groove Distance Is Reliable in the Setting of Trochlear Dysplasia, and Superior to the Tibial Tubercle-to-Posterior Cruciate Ligament Distance When Evaluating Coronal Malalignment in Patellofemoral Instability.

PURPOSE: To determine best practices for consistent and accurate evaluation of coronal alignment in patients with patellofemoral (PF) instability. METHODS: Six reviewers examined 239 knee magnetic resonance images (MRIs) in patients with PF instability and anterior cruciate ligament (ACL) rupture. Measurements included tibial tubercle-to-trochlear groove (TT-TG) distance measured at the most proximal and distal portions of the trochlea, tibial tubercle-to-PCL (TT-PCL) distance, and Dejour classification of trochlear dysplasia. RESULTS: Interrater reliability was low for Dejour classification (k = 0.289), but improved to moderate (k = 0.448) when patients were separated into normal/Dejour A and Dejour B/C/D. Interrater reliability was high for proximal and distal TT-TG measurements (interclass correlation coefficients [ICCs] = 0.807 and 0.936, respectively). TT-PCL was moderately reliable (ICC = 0.625), and correlated with TT-TG (r = 0.457, P < .001 proximal and r = 0.451, P < .001 distal). No significant difference was found between the proximal and distal measurements of TT-TG in each patient, though the PF group exhibited higher values than the ACL group (P < .001 for both). TT-PCL was significantly higher for the PF group than the ACL group (P = .015), but this difference lost significance when the group was divided by the TT-PCL cutoff of 24 mm (P = .371). CONCLUSIONS: The proximal and distal techniques for measuring the TT-TG distance are similar to each other, and reliable despite level of reviewer training or presence of dysplasia. The TT-TG distance was predictive of patellofemoral instability. The TT-PCL distance was found to be less reliable than either method of measuring the TT-TG distance. Thus, this study demonstrated TT-TG to be superior to TT-PCL as a measurement of coronal malalignment. Given the variability in Dejour classification in this and other studies, a more reliable classification system for trochlear dysplasia as defined on cross-sectional imaging is warranted. LEVEL OF EVIDENCE: Level III, retrospective clinical trial.

MED23-associated intellectual disability in a non-consanguineous family.

Intellectual disability (ID) is a heterogeneous condition arising from a variety of environmental and genetic factors. Among these causes are defects in transcriptional regulators. Herein, we report on two brothers in a nonconsanguineous family with novel compound heterozygous, disease-segregating mutations (NM_015979.3: [3656A > G];[4006C > T], NP_057063.2: [H1219R];[R1336X]) in MED23. This gene encodes a subunit of the Mediator complex that modulates the expression of RNA polymerase II-dependent genes. These brothers, who had profound ID, spasticity, congenital heart disease, brain abnormalities, and atypical electroencephalography, represent the first case of MED23-associated ID in a non-consanguineous family. They also expand upon the clinical features previously reported for mutations in this gene.

A Curricular Model for Simulation Within Orthopaedic Residency Training.

Introduction: American Board of Orthopaedic Surgery/American Council on GraduateMedical Education Residency Review Committee training requirements have necessitated the need for the adoption of simulation education into existing programmatic requirements. Current guidelines focus only on interns at a potentially significant cost to programs; both in total dollar amount and time. Methods: The authors aim to provide a model that can maximize utility for all resident levels, manage cost by maximizing the use of cadaveric material, and allow integration of varied industry support. Results: The Oregon Health & Science University Orthopaedic education program has developed a high-fidelity training curriculum that (1) is applicable to both junior and senior residents (2) has minimized the cost per resident with the reuse of cadaveric specimens and (3) has nurtured partnerships with industry stakeholders to reduce bias in training by collaborating with most major industry representatives. Conclusion: The simulation curriculum outlined in this manuscript may serve as a reference for other programs and institutions to develop their own residency educational curriculum models.

Resident Performance on the Fundamentals of Arthroscopic Surgery Training (FAST) Workstation Does Not Predictably Improve With Postgraduate Year.

Purpose: To identify differences in performance on the Fundamentals of Arthroscopic Surgery Training (FAST) workstation between residents across different postgraduate years and training sites. Methods: During the 2018-2019 academic year, 102 orthopaedic surgery residents from 4 training sites completed 6 FAST modules. Failure was defined as either completion time exceeding benchmark time or commission of task-specific errors. With the exception of knot tying, each module was completed by participants twice-once with each hand serving as the camera hand. Time to completion (except for knot tying) and errors were recorded for each of the modules. Completion times and failure rates were compared between postgraduate years, seniority groups, and training sites. Results: In all modules for which time was recorded, except for the suture-passage module, there was no significant difference in time to completion based on seniority (P < .01 for suture passage and P > .05 for all others). Significant differences in completion time were observed between sites for all modules except for the suture-passage module (P = .957 for suture passage and P < .05 for all others). Site predicted failure by at least 1 measure (time or technical error) for all modules (P < .05) except for number probing and suture passage. Failure rate across training years varied for each module. Conclusions: Time to completion and rate of failure did not predictably decrease with level of training. Training site proved to be a significant predictor of performance. Factors such as hand dominance and familiarity with the equipment proved to be important considerations for some modules. Clinical Relevance: Objective assessment of arthroscopic skills among orthopaedic trainees is difficult. Using reproducible methodology to assess trainees on specific skills at all postgraduate years and at multiple training sites may provide important information about orthopaedic training.

Antibody-mediated prevention of vaginal HIV transmission is dictated by IgG subclass in humanized mice.

HIV broadly neutralizing antibodies (bNAbs) are capable of both blocking viral entry and driving innate immune responses against HIV-infected cells through their Fc region. Vaccination or productive infection results in a polyclonal mixture of class-switched immunoglobulin G (IgG) antibodies composed of four subclasses, each encoding distinct Fc regions that differentially engage innate immune functions. Despite evidence that innate immunity contributes to protection, the relative contribution of individual IgG subclasses is unknown. Here, we used vectored immunoprophylaxis in humanized mice to interrogate the efficacy of individual IgG subclasses during prevention of vaginal HIV transmission by VRC07, a potent CD4-binding site-directed bNAb. We find that VRC07 IgG2, which lacks Fc-mediated functionality, exhibited substantially reduced protection in vivo relative to other subclasses. Low concentrations of highly functional VRC07 IgG1 yielded substantial protection against vaginal challenge, suggesting that interventions capable of eliciting modest titers of functional IgG subclasses may provide meaningful benefit against infection.

Orthopaedic Resident Arthroscopic Knot-Tying Skills Are Improved Using a Training Program and Knot-Tying Workstation.

PURPOSE: To quantify an orthopaedic trainee's ability to tie arthroscopic knots before and after a short cadaveric-based arthroscopy training period using a commercially available knot-tying workstation. METHODS: During a weeklong cadaveric arthroscopic training camp, 15 third- and fourth-year orthopaedic residents were evaluated using a commercially available benchtop knot-tying workstation. At the beginning of the week (baseline), each participant was asked to tie 3 knots of his or her choice backed up by 3 half-hitches using nonabsorbable suture. Successful knots fit the sizer and elongated less than 3 mm after application of a 15-lb load. Afterward, residents watched a video demonstrating a sample knot and were encouraged to practice over the ensuing days. At the end of the week (post-training), residents were asked to tie 3 knots. The time to completion and success of each knot were recorded. To compare baseline and post-training knot success, t tests and χ2 analysis were performed. RESULTS: During baseline testing, residents successfully tied 26.7% of their knots (12 of 45 knots) in 352 ± 116 seconds (mean ± standard deviation). During post-training testing, residents successfully tied 66.7% of knots (30 of 45 knots, P = .00014) in 294 ± 63 seconds (P = .023), showing significant improvement in the time and ability to tie arthroscopic knots. CONCLUSIONS: With a short cadaveric-based training period, orthopaedic trainees showed a significant improvement in their ability to tie arthroscopic knots on a commercially available benchtop knot-tying workstation. Given the initial low percentage of successfully tied knots and the limited opportunities for trainees to improve, trainees should be encouraged to practice and improve their skills. CLINICAL RELEVANCE: With training, residents can improve arthroscopic knot-tying abilities, which may allow them to successfully perform this critical task in the operating room.

Female Residents Give Themselves Lower Scores Than Male Colleagues and Faculty Evaluators on ACGME Milestones.

OBJECTIVE: Orthopedic surgery is one of the specialties with the lowest number of women residents and practicing surgeons. The gender discrepancy in orthopedic residency training may drive a competency bias. We asked whether female orthopedic surgery residents score themselves lower on the Accreditation Council for Graduate Medical Education (ACGME) Milestones than their male counterparts, and lower than their faculty evaluators. DESIGN: We conducted a retrospective review of ACGME Milestone data from faculty and residents over a 4-year period. The data were analyzed using a snapshot of PGY2 (n = 20 residents) and PGY4 (n = 19 residents) scores, and using a Generalized Estimation Equation (GEE) to account for additional data points from the same residents over the 4-year data collection period. SETTING: Assessment scores were compiled from a single orthopedic surgery residency at Oregon Health & Science University from 2014 to 2017. PARTICIPANTS: The residency program has 5 residents in each program year (PGY1 through PGY5); a total of 25 residents during each year of the study were included. RESULTS: On average, female residents scored themselves lower than both their male counterparts and their faculty mentors. Female PGY2 self-evaluation scores were lower than males in both patient care (p = 0.005) and medical knowledge (p < 0.001). When the GEE model was applied to 99 responses from 41 residents over a 4-year period, there were no gender-related differences in resident self-evaluation scores and in faculty scores of male and female residents, with the exception of meniscal tear. For this milestone, faculty rated female residents lower than males. Furthermore, the differences between faculty evaluation scores and resident self-evaluation scores were significantly lower for males than for females for 4 of the clinical domains, as well as the systems-based practice domains of cost and communication. CONCLUSIONS: Our results indicate female residents are at risk for a competency bias during training, as reflected by evaluations using the ACGME Milestones.

Development of a Multivariable Model Based on Individual Risk Factors for Recurrent Lateral Patellar Dislocation.

BACKGROUND: Nonoperative treatment after first-time patellar dislocation is the standard of care. There is evidence that certain patients may be at high risk for recurrent instability. The aim of this study was to develop a multivariable model to guide management of patients based on their individual risk of recurrent dislocation. METHODS: A multivariable model was developed using 291 patients from 4 institutions to identify which patients were at higher risk for recurrent patellar dislocation within 2 years. This model was informed by a univariable logistic regression model developed to test factors based on the patient's history, physical examination, and imaging. The discriminatory ability of the model to classify who will or will not have a recurrent dislocation was measured using the area under the receiver operating characteristic curve (AUC). RESULTS: Age, a history of a contralateral patellar dislocation, skeletal immaturity, lateral patellar tilt, tibial tubercle-trochlear groove (TT-TG) distance, Insall-Salvati ratio, and trochlear dysplasia were the most important factors for recurrent patellar dislocation. Sex, mechanism of injury, Caton-Deschamps ratio, sulcus angle, inclination angle, and facet ratio were not factors for recurrent dislocation. The overall AUC for the multivariable model was 71% (95% confidence interval [CI]: 64.7% to 76.6%). CONCLUSIONS: Optimizing the management of lateral patellar dislocation will improve short-term disability from the dislocation and reduce the long-term risk of patellofemoral arthritis from repeated chondral injury. This multivariable model can identify patients who are at high risk for recurrent dislocation and would be good candidates for early operative treatment. Further validation of this model in a prospective cohort of patients will inform whether it can be used to determine the optimal treatment plan for patients presenting with an initial patellar dislocation. Until validation of the model is done with new patients, it should not be used in clinical practice. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

When Is an Orthopedic Intern Ready to Take Call?

OBJECTIVE: While orthopedic residency training varies among programs, an inevitable phenomenon is a transition for interns from consistent oversight to independent call with indirect supervision. It is therefore crucial to reliably assess trainees' ability to perform basic procedures. The objective of the study was to evaluate the utility of a novel Orthopaedic Intern Skills Assessment (OISA) to assess skill level. DESIGN: In a cohort study, participants were evaluated on their ability to complete eleven skills in a simulated environment. Using a standardized patient and/or cadaveric specimen, we assessed skeletal traction, joint aspiration, joint injection, laceration repair, ankle brachial index measurement, compartment pressure monitoring, upper and lower extremity splinting, informed consent, spine trauma exam, and cervical spine clearance abilities. SETTING: The assessment took place in a medical simulation lab at the Oregon Health & Science University in Portland, Oregon. PARTICIPANTS: Third- or fourth-year medical students interested in orthopedics, incoming interns (preinterns), and residents within 1 month of completing their intern year (postinterns) were invited to participate in the study. All interested individuals were included. Of the 20 individuals contacted, 14 (70%) consented: 4 medical students (40%), 5 preinterns (100%), and 5 postinterns (100%). All consenting individuals finished their participation in the research. RESULTS: Postintern skill completion rate was significantly higher than preinterns (p = 0.006) and medical students (p < 0.001). Completion rates for preinterns were also significantly higher rate than medical students (p = 0.035). CONCLUSIONS: Our OISA found that postinterns had reached a basic orthopedic skill level expected of a junior resident without in-house supervision. Our OISA also highlighted areas of training that needed further attention, which will help orthopedic training programs verify an appropriate level of skill as trainees' progress from a supervised intern year to taking indirectly supervised junior resident call, and help identify areas where increased training is needed.

Reliability of Radiologic Assessments of Clinically Relevant Growth Remaining in Knee MRI of Children and Adolescents With Patellofemoral Instability: Data From the JUPITER Cohort.

BACKGROUND: Surgical decision making and preoperative planning for children and adolescents with patellofemoral instability rely heavily on a patient's skeletal maturity. To be clinically useful, radiologic assessments of skeletal maturity must demonstrate acceptable interrater reliability and accuracy. PURPOSE: The purpose of this study was to examine the interrater reliability among surgeons of varying experience levels and specialty training backgrounds when evaluating the skeletal maturity of the distal femur and proximal tibia of children and adolescents with patellofemoral instability. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Six fellowship-trained orthopaedic surgeons (3 pediatric orthopaedic, 2 sports medicine, and 1 with both) who perform a high volume of patellofemoral instability surgery examined 20 blinded knee radiographs and magnetic resonance images in random order. They assessed these images for clinically relevant growth (open physis) or clinically insignificant growth (closing/closed physis) remaining in the distal femoral and proximal tibial physes. Fleiss' kappa was calculated for each measurement. After initial ratings, raters discussed consensus methods to improve reliability and assessed the images again to determine if training and new criteria improved interrater reliability. RESULTS: Reliability for initial assessments of distal femoral and proximal tibial physeal patency was poor (kappa range, 0.01-0.58). After consensus building, all assessments demonstrated almost-perfect interrater reliability (kappa, 0.99 for all measurements). CONCLUSION: Surgical decision making and preoperative planning for children and adolescents with patellofemoral instability rely heavily on radiologic assessment of skeletal maturity. This study found that initial interrater reliability of physeal patency and clinical decision making was unacceptably low. However, with the addition of new criteria, a consensus-building process, and training, these variables became highly reliable.

COVID-19 in Australia: Impacts on Separated Families, Family Law Professionals, and Family Courts.

Around the globe, many families are experiencing significant anxieties linked to COVID-19. These include health concerns and economic pressures, both of which are frequently taking place against a backdrop of various levels of social isolation. In addition, many parents have been juggling home schooling requirements in the face of radically different work arrangements including the loss of employment altogether. Unsurprisingly, additional challenges and stresses are emerging for separated families, family law professionals, and family courts. In this article - written at a point-in-time in a rapidly evolving COVID-19 context - we reflect on key challenges for separated families in Australia, and some of the emerging professional responses.

Surgical Simulation Maximizing the Use of Fresh-Frozen Cadaveric Specimens: Examination of Tissue Integrity Using Ultrasound.

BACKGROUND: Arthroscopic surgical simulation, including the use of cadaveric tissue, is valuable for training orthopedic surgery residents. However, it is unclear how often fresh-frozen cadaveric tissue can be reused to provide a reproducible model for developing arthroscopic skills. OBJECTIVE: We determined the usefulness of ultrasound in evaluating tissue degradation in fresh-frozen shoulder and knee joints used for surgical simulation. METHODS: Between February 7 and April 11, 2017, orthopedic residents participated in 6 wet lab sessions during 1 rotation. Knee and shoulder specimens were subjected to ultrasound using a SonoSite Edge machine and a linear probe after each freeze-and-thaw cycle. Degradation of each structure was determined based on standards created for living tissue and comparisons to previous images of the same tissue before initial use. RESULTS: Ultrasonographic assessment of the 2 knee and 2 shoulder specimens revealed lost integrity in subcutaneous fat and muscle with evidence of increased hypoechoicity and loss of normal fiber orientation and density in all specimens examined. Tendons, ligaments, cartilage, iliotibial band, and bone did not lose integrity during freezing and thawing. Ultrasonographic assessment revealed no loss of joint structure integrity. However, the intra-articular work assigned for the simulation curriculum had been carried out to a degree that by the third use, little opportunity remained for further arthroscopic practice on that specimen. CONCLUSIONS: In this study, ultrasound findings showed that fresh-frozen shoulder and knee specimens maintained structural integrity useful for simulation training after 3 cycles of freezing.

Comparison of Ligament Isometry and Patellofemoral Contact Pressures for Medial Patellofemoral Ligament Reconstruction Techniques in Skeletally Immature Patients.

BACKGROUND: Adult medial patellofemoral ligament (MPFL) reconstruction techniques are not appropriate for the skeletally immature patient given the proximity of the distal femoral physis. Biomechanical consequences of reconstructions aimed at avoiding the physis have not been adequately studied. PURPOSE: To quantify the biomechanical effects of MPFL reconstruction techniques intended for skeletally immature patients. STUDY DESIGN: Controlled laboratory study. METHODS: Four MPFL reconstruction techniques were evaluated using a computationally augmented cadaveric model: (1) Schoettle point: adult-type reconstruction; (2) epiphyseal: socket distal to the femoral physis; (3) adductor sling: graft wrapped around the adductor tendon; (4) adductor transfer: adductor tendon transferred to patella. A custom testing frame was used to cycle 8 knees for each technique from 10° to 110° of flexion. Patellofemoral kinematics were recorded using a motion camera system, contact stresses were recorded using Tekscan pressure sensors, and MPFL length was computed using an inverse kinematics computational model. Change in MPFL length, patellar facet forces, and patellar kinematics were compared using generalized estimating equation modeling. RESULTS: Schoettle point reconstruction was the most isometric, demonstrating isometry from 10° to 100°. The epiphyseal technique was isometric until 60°, after which the graft loosened with increasing flexion. The adductor sling and adductor transfer techniques were significantly more anisometric from 40° to 110°. Both grafts tightened with knee flexion and resulted in significantly more lateral patellar tilt versus the intact state in early flexion and significantly higher contact forces on the medial facet versus the epiphyseal technique in late flexion. CONCLUSION: In this cadaveric simulation, the epiphyseal technique allowed for a more isometric ligament until midflexion, when the patella engaged within the trochlear groove. The adductor sling and adductor transfer grafts became tighter in flexion, resulting in potential loss of motion, pain, graft stretching, and failure. Marginal between-condition differences in patellofemoral contact mechanics and patellar kinematics were observed in late flexion. CLINICAL RELEVANCE: In the skeletally immature patient, using an epiphyseal type MPFL reconstruction with the femoral attachment site distal to the physis results in a more isometric graft compared with techniques with attachment sites proximal to the physis.

MPFL in First-Time Dislocators.

PURPOSE OF REVIEW: Historically, the standard of care for patients with an acute patella dislocation has been non-operative with the exception being those with a loose body or osteochondral fracture requiring fixation or removal. RECENT FINDINGS: Recent literature has brought into question this standard of care approach and defined a higher risk subset of first-time dislocators who may benefit from early operative treatment. In addition, these studies suggest that operative treatment not only reduces the risk of recurrence but may improve outcomes overall and specifically in the pediatric population. Though the "high risk" population of first-time dislocators has been more clearly defined, how we treat them remains controversial. We continue to need more evidence-based guidelines to help us manage who we should be fixing and how we should be fixing them. We currently have several multi-center studies in progress, including one specifically looking at the question of medial patellofemoral ligament reconstruction in first-time pediatric and adolescent dislocators.

Comparison of fluoroscopic techniques for assessment of femoral rotational alignment.

OBJECTIVES: Anatomic rotational reduction of diaphyseal femur fractures is essential in restoring limb mechanics. Errors in reproducing anteroposterior (AP) or lateral knee reference radiographs of the contralateral limb could result in inaccuracies during rotational reduction. The objective of this study was to examine whether fluoroscopic rotational variation can be observed with the same degree of precision with AP and lateral distal femur projections. METHODS: AP and lateral radiographs were obtained from intact knees of 7 cadaveric specimens using fluoroscopy. The lateral condylar width and coronal femoral width from the AP images and the posterior condylar offset and sagittal femoral width from the lateral images were measured by 3 reviewers. Interclass correlation coefficients (ICCs) among the 3 reviewers were calculated. The mean data from all reviewers were plotted against angle of rotation, and the slope (M) and regression of the line were then determined. RESULTS: ICCs were 0.997 (lateral) and 0.994 (AP), demonstrating excellent interobserver agreement. The mean (±SD) M value for lateral images was 0.016 ±â€Š0.001 and for AP images was 0.009 ±â€Š0.001 (P < .0001). The higher lateral M value represents a more appreciable difference in size of the measured segment for the same rotational change. CONCLUSIONS: The observed rotational change was 1.76 times greater on lateral images compared to AP images; thus, the lateral images may be more precise as a reference for rotation. The routine use of lateral knee radiographs to guide intraoperative rotational alignment of the femur may therefore be justified.