SARS-CoV-2 antibodies protect against reinfection for at least 6 months in a multicentre seroepidemiological workplace cohort.

Identifying the potential for SARS-CoV-2 reinfection is crucial for understanding possible long-term epidemic dynamics. We analysed longitudinal PCR and serological testing data from a prospective cohort of 4,411 United States employees in 4 states between April 2020 and February 2021. We conducted a multivariable logistic regression investigating the association between baseline serological status and subsequent PCR test result in order to calculate an odds ratio for reinfection. We estimated an odds ratio for reinfection ranging from 0.14 (95% CI: 0.019 to 0.63) to 0.28 (95% CI: 0.05 to 1.1), implying that the presence of SARS-CoV-2 antibodies at baseline is associated with around 72% to 86% reduced odds of a subsequent PCR positive test based on our point estimates. This suggests that primary infection with SARS-CoV-2 provides protection against reinfection in the majority of individuals, at least over a 6-month time period. We also highlight 2 major sources of bias and uncertainty to be considered when estimating the relative risk of reinfection, confounders and the choice of baseline time point, and show how to account for both in reinfection analysis.

Second Harmonic Generation Microscopy as a Novel Intraoperative Assessment of Rat Median Nerve Injury.

PURPOSE: Nerves that are functionally injured but appear macroscopically intact pose the biggest clinical dilemma. Second Harmonic Generation (SHG) Microscopy may provide a real-time assessment of nerve damage, with the ultimate goal of allowing surgeons to accurately quantify the degree of nerve damage present. The aim of this study was to demonstrate the utility of SHG microscopy to detect nerve damage in vivo in an animal model. METHODS: Ten Sprague-Dawley rats were anesthetized and prepared for surgery. After surgical exposure and using a custom-made stretch applicator, the right median nerves were stretched by 20%, corresponding to a high strain injury, and held for 5 minutes. The left median nerve served as a sham control (SC), only being placed in the applicator for 5 minutes with no stretch. A nerve stimulator was used to assess the amount of stimulation required to induce a flicker and contraction of the paw. Nerves were then imaged using a multiphoton laser scanning microscope. RESULTS: Immediately after injury (day 0), SHG images of SC median nerves exhibited parallel collagen fibers with linear, organized alignment. In comparison with SC nerves, high strain nerves demonstrated artifacts indicative of nerve damage consisting of wavy, undulating fibers with crossing fibers and tears, as well as a decrease in the linear organization, which correlated with an increase in the mean stimulation required to induce a flicker and contraction of the paw. CONCLUSIONS: Second Harmonic Generation microscopy may provide the ability to detect an acute neural stretch injury in the rat median nerve. Epineurial collagen disorganization correlated with the stimulation required for nerve function. CLINICAL RELEVANCE: In the future, SHG may provide the ability to visualize nerve damage intraoperatively, allowing for better clinical decision-making. However, this is currently a research tool and requires further validation before translating to the clinical setting.

Outcomes of Arthroscopic Elbow Contracture Release: Improvement for Severe Prosupination and Flexion Contracture.

PURPOSE: The purpose of this study was to investigate outcomes following arthroscopic elbow contracture release to describe the use of arthroscopy for improvement in extension/flexion and pronation/supination arcs of motion at a single institution for degenerative and posttraumatic etiologies. METHODS: Consecutive arthroscopic elbow arthrolysis performed between 2003 and 2015 were retrospectively reviewed. Basic patient demographics, indications for surgery, preoperative and postoperative elbow range of motion, postoperative patient outcome score, and all complications were recorded and analyzed. RESULTS: Fifty-two patients were included with an average follow-up of 5.1 years (range 1.4 to 9.4). Severe contractures made up 50% of cases, followed by 23% moderate, and 27% mild. Average extension/flexion for the post-traumatic group (n = 30) increased by 63° ± 31 and by 29° ± 24 for the degenerative group (n = 22). Average gain in pronosupination was 38° ± 62 in the post-traumatic group and 13°±23 in the degenerative group. Postoperative DASH scores were 17.5 ± 18.4 for post-traumatic cases and 12.8 ± 19.3 for degenerative cases. CONCLUSION: Arthroscopic elbow contracture release is an effective intervention for degenerative and post-traumatic elbow contracture for both flexion/extension and pronosupination contracture. Furthermore, a two-stage release should be considered when both flexion and pronosupinaton contractures are present. LEVEL OF EVIDENCE: IV, case series, treatment study.

Casting Position for Distal Radius Fractures Changes Radiocarpal Joint Forces: A Cadaveric Study.

PURPOSE: Nonsurgical distal radius fracture treatment requires immobilization and classical teaching suggests varying cast positions. We investigated the effect of cast position on the force and pressure experienced by the articular cartilage in the scaphoid and lunate fossae. METHODS: Ten fresh-frozen cadaveric specimens were used. A standardized extra-articular distal radius fracture was made. Force sensors were affixed to the articular cartilage of the scaphoid and lunate fossae. Baseline data were obtained. Specimens were then placed into a short arm cast with the wrist either neutrally aligned or flexed and ulnarly deviated (FUD). Specimens had a standard load applied, and a force profile was obtained. The cast was removed and the other cast type was placed and measurements were repeated. Overall force and pressure values were compared between baseline data and the 2 cast types. Additionally, differences in volar and dorsal scaphoid and lunate fossa forces and pressures were compared pairwise within the 2 cast types. The relative force and pressure values across cast types were also compared. RESULTS: Both cast types significantly reduced the median force and pressure experienced by the radiocarpal joint compared with no cast. In the FUD cast, the volar and dorsal lunate fossa experienced significantly greater force, and the dorsal lunate fossa experienced significantly greater pressure compared with the dorsal scaphoid fossa. There were no differences for any fossae in the neutral cast. When comparing between casts, the volar lunate fossa experienced a significantly greater relative force in the FUD cast compared with the neutral cast. CONCLUSIONS: Casting a distal radius fracture decreases the forces and pressures in the radiocarpal joint. Placing the wrist in a FUD position results in greater forces and pressures on the lunate fossa compared with the scaphoid fossa. CLINICAL RELEVANCE: When immobilization is needed, we advocate for the placement of patients in a relatively neutral short-arm cast with minimal FUD to avoid this increased pressure.

An Analysis of Profundus Tendon Repairs After Distal Phalanx Amputation in a Cadaveric Model of Little Finger Superficialis Deficiency.

PURPOSE: The flexor digitorum superficialis tendon to the little finger (FDS-5) has been observed to have a higher degree of functional and structural variation than the FDS of other digits. FDS-5-deficient individuals necessarily rely on the flexor digitorum profundus tendon to the little finger (FDP-5) for flexion in their little fingers. FDS-5 deficient patients who experience a considerable injury to their FDP-5 are therefore at a risk of losing substantial little finger flexion. The purpose of this study was to evaluate the degree of flexion of the little finger at the metacarpophalangeal and proximal interphalangeal (PIP) joints in a cadaveric model of FDS-5 deficiency following amputation of the distal phalanx. METHODS: Ten fresh-frozen cadaveric upper extremities with no prior trauma were used. Loads were applied to the FDP-5. Flexion at the PIP and metacarpophalangeal joints was measured in degrees with a goniometer. Little finger flexion testing was conducted under 5 different conditions: "baseline," "FDS-deficient," "no repair," "bone anchor" repair, and "A4 pulley" repair. RESULTS: The results were as follows: (1) no significant differences in the flexion between baseline and FDS-deficient conditions; (2) a significant decline in PIP flexion in the no repair condition after FDP-5 division compared with the FDS-deficient condition; (3) a significant restoration in PIP flexion in both surgical repair groups compared with the no repair group; and (4) no significant differences in PIP flexion between the A4 pulley and bone anchor groups. CONCLUSIONS: The bone anchor repair and the A4 pulley repair demonstrate similar abilities to restore flexion of the little finger at the PIP joint to baseline levels in this cadaveric model. CLINICAL RELEVANCE: A clinical protocol is yet to be established for the surgical treatment in FDS-5-deficient patients requiring amputation of the distal phalanx of the little finger. This study aims to address this area of uncertainty by comparing the little finger flexion after 2 different approaches to profundus tendon reattachment that may be applicable in this clinical scenario.

Experience Level Influences Users' Interactions With and Expectations For Online Surgical Videos: A Mixed-Methods Study.

PURPOSE: Upper-extremity surgeons and trainees widely use online surgical videos, and the use of these videos can assist with procedural learning. The purpose of this study was to characterize online video use and understand the role videos play in the learning process of orthopedic residents and practicing surgeons. We hypothesized that the use of surgical videos and video content desired among orthopedic learners differs based on their experience level. METHODS: Four focus groups were conducted to discuss online surgical videos and their role in the learning process of orthopedic learners. Participants were separated based on their experience level. Three reviewers qualitatively analyzed the transcripts of the focus groups using constant comparative methods to identify overarching themes and categories. Findings regarding the participants' desires for video content and production quality were translated into a survey. The survey results were analyzed to assess their associations with experience level. RESULTS: The focus group analysis helped identify 4 overarching themes that reflected users' interactions with videos: prewatching experience, choosing a video, video use, and video design, with the users' comments differing based on their experience level. The survey results showed that the median ideal length for a video was 10 minutes and that all users, regardless of their experience level, ranked showing the surgical procedure as the most important part of a video. Junior residents more frequently desired background information and a written outline of surgical steps, whereas more senior learners placed greater emphasis on advanced surgical decision-making and the use of particular implants/devices. CONCLUSIONS: Experience level influences users' interactions with videos, including how they are chosen and used, and their expectations in terms of content and production. CLINICAL RELEVANCE: Video creators should specify their targeted audience's experience level and adjust content to meet users' needs. Our results can provide video creators and hosts a checklist for appropriate content and production standards.

Comparative strength of elbow splint designs: a new splint design as a stronger alternative to posterior splints.

BACKGROUND: Musculoskeletal injuries of the upper extremity are frequently treated with temporary external immobilization. Traditionally, long arm posterior splints have been used to limit flexion/extension of the elbow. However, long arm posterior splints have been observed to fail clinically, necessitating a stronger alternative. In this study, we assessed the biomechanical strength of the long arm posterior splint compared with a new spiral splint design. METHODS: One male and one female participant were placed 10 times in long arm posterior splints and 10 times in spiral splints. Both splint types were subjected to a downward mechanical load of 39.2 N (4 kg) and assessed for a change in both flexion/extension and pronation/supination. RESULTS: There was no significant difference in starting position or starting flexion/extension between the 2 splint designs. Posterior splints allowed significantly greater initial pronation/supination compared with spiral splints. Both splint groups had significant increases in flexion/extension and pronation/supination compared with their starting ranges of motion. There was no significant difference in the change in pronation/supination between the 2 splint groups. Finally, posterior splints allowed a significantly greater change in flexion/extension compared with spiral splints. CONCLUSION: Spiral splints offered less initial pronation/supination than long arm posterior splints. Furthermore, spiral splints are able to resist flexion/extension of the elbow after application of a downward mechanical load better than posterior splints, thus suggesting spiral splints are mechanically superior to long arm posterior splints.

Varus posteromedial rotatory instability: a biomechanical analysis of posterior bundle of the medial ulnar collateral ligament reconstruction.

BACKGROUND: Recently, there has been growing interest in the involvement of the posterior bundle of the medial ulnar collateral ligament (pMUCL) in varus posteromedial rotatory instability (PMRI). Varus PMRI has been observed clinically, but the degree of involvement of the pMUCL remains unclear. This study assessed the degree to which the pMUCL is involved in stabilizing the elbow and the feasibility of a pMUCL reconstruction to restore stability. METHODS: Movements simulating PMRI were performed in 8 cadaveric elbows. Joint gapping values were obtained by 3-dimensional motion capture for the proximal and distal aspects of the ulnohumeral joint. Specimens were assessed at "intact," "cut coronoid + pMUCL," "reconstruction," and "cut anterior aspect MUCL + reconstruction" conditions with mechanical testing at 30°, 60°, and 90° of elbow flexion. RESULTS: Proximal joint gapping significantly increased from intact to cut coronoid + pMUCL at 60° and 90°, and distal joint gapping significantly increased at 90°. In the reconstruction condition, joint gapping across the proximal joint at 60° and 90° significantly recovered, as did distal joint gapping at 90°. In the cut anterior aspect MUCL + reconstruction condition, no significant increase occurred in proximal or distal joint gapping. CONCLUSIONS: Transection of the pMUCL with a coronoid fracture leads to increased joint gapping, suggesting the presence of PMRI. PMRI can still occur with an intact lateral ligamentous complex. A pMUCL tendon graft reconstruction confers some elbow stability in this injury mechanism.

Epidemiological and Immunological Features of Obesity and SARS-CoV-2.

Obesity is a key correlate of severe SARS-CoV-2 outcomes while the role of obesity on risk of SARS-CoV-2 infection, symptom phenotype, and immune response remain poorly defined. We examined data from a prospective SARS-CoV-2 cohort study to address these questions. Serostatus, body mass index, demographics, comorbidities, and prior COVID-19 compatible symptoms were assessed at baseline and serostatus and symptoms monthly thereafter. SARS-CoV-2 immunoassays included an IgG ELISA targeting the spike RBD, multiarray Luminex targeting 20 viral antigens, pseudovirus neutralization, and T cell ELISPOT assays. Our results from a large prospective SARS-CoV-2 cohort study indicate symptom phenotype is strongly influenced by obesity among younger but not older age groups; we did not identify evidence to suggest obese individuals are at higher risk of SARS-CoV-2 infection; and remarkably homogenous immune activity across BMI categories suggests immune protection across these groups may be similar.

Discrete SARS-CoV-2 antibody titers track with functional humoral stability.

Antibodies serve as biomarkers of infection, but if sustained can confer long-term immunity. Yet, for most clinically approved vaccines, binding antibody titers only serve as a surrogate of protection. Instead, the ability of vaccine induced antibodies to neutralize or mediate Fc-effector functions is mechanistically linked to protection. While evidence has begun to point to persisting antibody responses among SARS-CoV-2 infected individuals, cases of re-infection have begun to emerge, calling the protective nature of humoral immunity against this highly infectious pathogen into question. Using a community-based surveillance study, we aimed to define the relationship between titers and functional antibody activity to SARS-CoV-2 over time. Here we report significant heterogeneity, but limited decay, across antibody titers amongst 120 identified seroconverters, most of whom had asymptomatic infection. Notably, neutralization, Fc-function, and SARS-CoV-2 specific T cell responses were only observed in subjects that elicited RBD-specific antibody titers above a threshold. The findings point to a switch-like relationship between observed antibody titer and function, where a distinct threshold of activity-defined by the level of antibodies-is required to elicit vigorous humoral and cellular response. This response activity level may be essential for durable protection, potentially explaining why re-infections occur with SARS-CoV-2 and other common coronaviruses.

Long head of biceps tenodesis at the superior aspect of the biceps groove: A biomechanical comparison of inlay and onlay techniques.

PURPOSE: Pathology involving the long head of the biceps tendon is a common source of shoulder pain. Biceps tenodesis has been successfully used in areas below the pectoralis, above the pectoralis, and above the biceps groove. However, clinical data are lacking for additional techniques for tenodesis at the superior aspect of the biceps groove. METHODS: A biomechanical comparison was completed examining six matched pairs of cadaveric shoulders. The ultimate load to failure was compared between an inlay and onlay biceps tenodesis at the superior aspect of the biceps groove. RESULTS: The results demonstrate an average construct strength of 215 N for the inlay technique and 210 N for the onlay technique. The difference between the two techniques was not significant. CONCLUSIONS: This study demonstrates similar biomechanical strength for both constructs.

Epidemiological and immunological features of obesity and SARS-CoV-2.

Obesity is a key correlate of severe SARS-CoV-2 outcomes while the role of obesity on risk of SARS-CoV-2 infection, symptom phenotype, and immune response are poorly defined. We examined data from a prospective SARS-CoV-2 cohort study to address these questions. Serostatus, body mass index, demographics, comorbidities, and prior COVID-19 compatible symptoms were assessed at baseline and serostatus and symptoms monthly thereafter. SARS-CoV-2 immunoassays included an IgG ELISA targeting the spike RBD, multiarray Luminex targeting 20 viral antigens, pseudovirus neutralization, and T cell ELISPOT assays. Our results from a large prospective SARS-CoV-2 cohort study indicate symptom phenotype is strongly influenced by obesity among younger but not older age groups; we did not identify evidence to suggest obese individuals are at higher risk of SARS-CoV-2 infection; and, remarkably homogenous immune activity across BMI categories suggests natural- and vaccine-induced protection may be similar across these groups.

A Novel Algorithmic Approach to Chronic Forearm Longitudinal Instability.

Essex-Lopresti Lesions are rare injuries that are often missed in the acute setting. Delayed intervention may lead to chronic wrist and elbow pain and overall poor outcomes. The literature currently supports treatments that involve shortening of the ulna to reduce the relative degree of ulnar impaction, followed by attempted reduction of the distal radioulnar joint. Although such techniques may help to temporarily reduce wrist pain secondary to ulnar impaction, they do not address the proximal migration of the radius and ipsilateral radial head dislocation at the elbow. Subsequent procedures are often needed to replace or resect the radial head. We present a novel approach to chronic Essex-Lopresti lesions resulting in anatomic restoration of forearm length with return of elbow and wrist flexion/extension as well as improved forearm pronation/supination.

Detecting structural and inflammatory response after in vivo stretch injury in the rat median nerve via second harmonic generation.

BACKGROUND: Second Harmonic Generation (SHG) microscopy is a promising method for visualizing the collagenous structure of peripheral nerves. Assessing collagen continuity and damage after a stretch injury provides inferential insight into the level of axonal damage present. NEW METHODS: This study utilizes SHG microscopy after a calibrated in vivo stretch injury of rat median nerves to evaluate collagen continuity at several time points throughout the recovery process. Endoneurial collagen was qualitatively assessed in nerves that were subjected to low strain (LS) and high strain (HS) injuries using SHG microscopy, conventional histology, and immunohistochemistry. RESULTS: Following an in vivo stretch injury, both LS and HS damaged nerves exhibit signs of structural collagen damage in comparison with sham control nerves (SC). Furthermore, LS nerves exhibit signs of full regeneration while HS nerves exhibited signs of only partial regeneration with lasting damage and intra-neural scar formation. COMPARISON WITH EXISTING METHODS: SHG observations of structural changes and inflammatory response due to stretch injury were validated upon comparison with conventional histological methods CONCLUSIONS: We propose that SHG microscopy can be utilized to visualize significant structural artifacts in sectioned median nerves following in vivo stretch injury. Based on the findings in this study, we believe that the in vivo application of SHG microscopy should be further investigated as a means for real-time, intra-operative, quantitative assessment of nerve damage.