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Background: The National Hockey League (NHL) saw an unprecedented disruption to the competitive calendar due to the COVID-19 pandemic in March of 2020. Returning to play following an abrupt cessation of activity is a known risk factor for athletes., Purpose: To analyze the occurrence and severity of events (injury and illness) in the NHL and to understand any differences in occurrence and severity between pre-pandemic seasons and seasons that immediately followed., Study Design: Descriptive Epidemiology Study., Methods: Using a retrospective cohort inclusive of all players on active rosters in the NHL between 2016-2023, public access injury and illness data were collected. Outcome measures included event incidence, period prevalence, and severity (mean days lost; MDL), as well as incidence rate ratio (IRR) comparing pre- and post-pandemic seasons., Results: IRR for illness peaked in December 2021 (IRR = 62.46; 95% CI 13.65 to 285.91). Incidence of upper body injuries was significantly higher in 2020-21 (IRR = 1.70, p = 0.001) and 2021-22 (IRR = 1.40, p = 0.044) compared to pre-pandemic seasons (Incidence = 17.58 injuries / 1000 player-hours). Injury incidence increased as the 2022-23 season progressed (p = 0.004); injury incidence was stable across all other seasons. Mean days lost (MDL) to injury was higher in 2020-21 (MDL = 18.12, p < 0.001), 2021-22 (MDL = 18.46, p = 0.015), and 2022-23 (MDL = 18.12, p < 0.001) compared to pre-pandemic seasons (MDL = 17.34)., Conclusion: Incidence of upper body injuries increased in the 2020-21 and 2021-22 NHL regular seasons while it decreased significantly in the 2022-23 regular season compared with the four pre-pandemic seasons. This suggests a need to examine if modifiable risk factors exist for determining optimal return to play strategies following an abrupt cessation of play., Level of Evidence: 3., (© The Author(s).)

Collagenase digestion (d) and cellular outgrowth (og) are the current modalities of meniscus fibrochondrocytes (MFC) isolation for bioengineering and mechanobiology-related studies. However, the impact of these modalities on study outcomes is unknown. Here, we show that og- and d-isolated MFC have distinct proliferative capacities, transcriptomic profiles via RNA sequencing (RNAseq), extracellular matrix (ECM)-forming, and migratory capacities. Our data indicate that microtissue pellet models developed from og-isolated MFC display a contractile phenotype with higher expressions of alpha-smooth muscle actin (ACTA2) and transgelin (TAGLN) and are mechanically stiffer than their counterparts from d-MFC. Moreover, we introduce a novel method of MFC isolation designated digestion-after-outgrowth (dog). The transcriptomic profile of dog-MFC is distinct from d- and og-MFC, including a higher expression of mechanosensing caveolae-associated caveolin-1 (CAV1). Additionally, dog-MFC were superior chondrogenically and generated larger-size microtissue pellet models containing a higher frequency of smaller collagen fibre diameters. Thus, we demonstrate that the modalities of MFC isolation influence the downstream outcomes of bioengineering and mechanobiology-related studies., (© 2024 The Author(s). Cell Proliferation published by Beijing Institute for Stem Cell and Regenerative Medicine and John Wiley & Sons Ltd.)

Background: Mechanical unloading of the knee articular cartilage results in cartilage matrix atrophy, signifying the osteoarthritic-inductive potential of mechanical unloading. In contrast, mechanical loading stimulates cartilage matrix production. However, little is known about the response of meniscal fibrocartilage, a major mechanical load-bearing tissue of the knee joint, and its functional matrix-forming fibrochondrocytes to mechanical unloading events., Methods: In this study, primary meniscus fibrochondrocytes isolated from the inner avascular region of human menisci from both male and female donors were seeded into porous collagen scaffolds to generate 3D meniscus models. These models were subjected to both normal gravity and mechanical unloading via simulated microgravity (SMG) for 7 days, with samples collected at various time points during the culture., Results: RNA sequencing unveiled significant transcriptome changes during the 7-day SMG culture, including the notable upregulation of key osteoarthritis markers such as COL10A1, MMP13, and SPP1, along with pathways related to inflammation and calcification. Crucially, sex-specific variations in transcriptional responses were observed. Meniscus models derived from female donors exhibited heightened cell proliferation activities, with the JUN protein involved in several potentially osteoarthritis-related signaling pathways. In contrast, meniscus models from male donors primarily regulated extracellular matrix components and matrix remodeling enzymes., Conclusion: These findings advance our understanding of sex disparities in knee osteoarthritis by developing a novel in vitro model using cell-seeded meniscus constructs and simulated microgravity, revealing significant sex-specific molecular mechanisms and therapeutic targets., (© 2024. The Author(s).)

Purpose: Comprehensive understanding of force plate parameters distinguishing individuals postprimary anterior cruciate ligament reconstruction (ACLR) from healthy controls during countermovement jumps (CMJ) and/or drop jumps (DJ) is lacking. This review addresses this gap by identifying discriminative force plate parameters and examining changes over time in individuals post-ACLR during CMJ and/or DJ., Methods: We conducted a systematic review and meta analyses following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Nine databases were searched from inception to March 2022. We included cross-sectional papers comparing post-ACLR with healthy controls or longitudinal studies of individuals at least 6 months postprimary ACLR while performing CMJ and/or DJ on force plates. The methodological quality was appraised using the Modified Downs and Black Checklist., Results: Thirty-three studies including 1185 (50.38%) participants post-ACLR, and 1167 (49.62%) healthy controls, were included. Data were categorised into single-leg CMJ, double-leg CMJ, single-leg DJ, and double-leg DJ. Jump height was reduced in both single (mean difference [MD] = -3.13; p  < 0.01; 95% confidence interval [CI]: [-4.12, -2.15]) and double-leg (MD = -4.24; p  < 0.01; 95% CI: [-5.14, -3.34]) CMJs amongst individuals with ACLR. Similarly, concentric impulse and eccentric/concentric impulse asymmetry could distinguish between ACLR (MD = 3.42; p  < 0.01; 95% CI: [2.19, 4.64]) and non-ACLR (MD = 5.82; p  < 0.01; 95% CI: [4.80, 6.80]) individuals. In double-leg DJs, peak vertical ground reaction forces were lower in the involved side (MD = -0.10; p  = 0.03; 95% CI: [-0.18, -0.01]) but higher in the uninvolved side (MD = 0.15; p  < 0.01; 95% CI: [0.10, 0.20]) when compared to controls and demonstrated significant changes between 6 months and 3 years post-ACLR., Conclusion: This study identified discriminative kinetic parameters when comparing individuals with and without ACLR and also monitored neuromuscular function post-ACLR. Due to heterogeneity, a combination of parameters may be required to better identify functional deficits post-ACLR., Level of Evidence: Level III., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Journal of Experimental Orthopaedics published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Context: Clinical guidelines support the use of testing batteries to assess athlete readiness for return to sport (RTS) and risk of reinjury after anterior cruciate ligament (ACL) reconstruction (ACL-R). There is no consensus on the composition of the testing batteries. Test selection is based mainly on commonality in research, personal preference, and equipment availability. Including athletic performance assessments (APA) used in the athlete's sport may assist RTS decision-making for stakeholders., Objective: To determine whether APA for speed, agility, strength, or cardiovascular endurance are (1) used in ACL-R RTS literature and (2) indicative of RTS or reinjury rates., Data Sources: A systematic search was performed in MEDLINE, EMBASE, CINAHL, SPORTDiscus, Scopus, Web of Science, and ProQuest Dissertations and Theses Global., Study Selection: Eligibility criteria were as follows: (1) athletes between 6 months and 2 years post-ACL-R, (2) commonly used APA, (3) peer-reviewed primary study with original published data., Study Design: Scoping Review., Level of Evidence: Level 4., Data Extraction: A total of 17 studies included 24 instances of APA with a high degree of heterogeneity for both tests and protocols., Results: Agility makes up 75% of the APA. Only 17.6% of studies reported RTS or reinjury rates, none of which reported a significant relationship between these rates and APA outcomes., Conclusion: Speed, strength, and cardiovascular endurance tests are underrepresented in ACL-R RTS literature. Compared with healthy controls, deficits in APA results for ACL-R athletes were common; however, many studies reported significant improvements in results for ACL-R athletes over time. There is some evidence that well-trained ACL-R athletes can match the performance of uninjured athletes in high-level sports., Competing Interests: The authors report no potential conflicts of interest in the development and publication of this article.

Background: Despite the ongoing opioid epidemic, most patients are still prescribed a significant number of opioid medications for pain management after arthroscopic surgery. There is a need for consensus among orthopaedic surgeons and solutions to aid providers in analgesic strategies that reduce the use of opioid pain medications., Purpose: This position statement was developed with a comprehensive systematic review and meta-analysis of exclusively randomized controlled trials (RCTs) to synthesize the best available evidence for managing acute postoperative pain after arthroscopic surgery., Study Design: Position statement., Methods: The Embase, MEDLINE, PubMed, Scopus, and Web of Science databases were searched from inception until August 10, 2022. Keywords included arthroscopy , opioids , analgesia , and pain , and associated variations. We included exclusively RCTs on adult patients to gather the best available evidence for managing acute postoperative pain after arthroscopic surgery. Patient characteristics, pain, and opioid data were extracted, data were analyzed, and trial bias was evaluated., Results: A total of 21 RCTs were identified related to the prescription of opioid-sparing pain medication after arthroscopic surgery. The following recommendations regarding noninvasive, postoperative pain management strategies were made: (1) multimodal oral nonopioid analgesic regimens-including at least 1 of acetaminophen-a nonsteroidal anti-inflammatory drug-can significantly reduce opioid consumption with no change in pain scores; (2) cryotherapy is likely to help with pain management, although the evidence on the optimal method of application (continuous-flow vs ice pack application) is unclear; (3) and (4) limited RCT evidence supports the efficacy of transcutaneous electrical nerve stimulation and relaxation exercises in reducing opioid consumption after arthroscopy; and (5) limited RCT evidence exists against the efficacy of transdermal lidocaine patches in reducing opioid consumption., Conclusion: A range of nonopioid strategies exist that can reduce postarthroscopic procedural opioid consumption with equivalent vocal pain outcomes. Optimal strategies include multimodal analgesia with education and restricted/reduced opioid prescription., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: O.R.A. has received nonconsulting fees from CONMED. I.W. has received consulting fees from DePuy Mitek, Smith & Nephew, COMED, and Bioventus. J.W. has received research support from Arthrex, CONMED, Linvatec, Ossur, Smith & Nephew, and Zimmer Biomet; and education payments from Arthrex, CONMED, Linvatec, Ossur, Smith & Nephew, and Zimmer Biomet. J.G. has received research support from JRF Ortho, Arthrex, MiMedX, and InGeneron; education payments from Arthrex; and consulting fees from JRF Ortho, Vericel, Arthrex, and Tactile Orthopaedics. M.P. has received consulting fees from Arthrex and CONMED. R.D. has received research support from Smith & Nephew and honoraria from Sanofi. R.M. has received education payments from Arthrex, Gemini Medical, Smith & Nephew, and Linvatec; and consulting fees from Smith & Nephew. M.E.L. has received research support from Arthrex, CONMED, Linvatec, Ossur, Smith & Nephew, and Zimmer Biomet; and education payments from Arthrex, CONMED, Linvatec, Ossur, Smith & Nephew, and Zimmer Biomet. B.M. has received consulting fees from Arthrex and honoraria from Pendopharm. R.K.M has received a grant from Smith & Nephew; consulting fees from Smith & Nephew and Arthrex; nonconsulting fees from Tactile Orthopaedics; royalties from Tactile Orthopaedics; stock from Tactile Orthopaedics; and is on the Board for Tactile Orthopaedics. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2023.)

Posterolateral corner knee injuries are clinically significant, and often require surgical reconstruction. The optimal knee brace following posterolateral corner reconstructions has not yet been determined via clinical nor biomechanical study. We sought to evaluate the stiffness of six types of knee braces to determine the ideal brace type for reducing varus forces, which may have clinical utility for posterolateral corner knee reconstruction rehabilitation. Six different groups of knee braces underwent mechanical testing: cruciate braces, cruciate braces with a valgus bend, medial unloaders, articulating sleeves, hinged braces, and tri-panel immobilizers. Each brace was fitted to the same fiberglass leg model and was secured to the testing apparatus. Force was applied under four-point bending to generate a varus moment about the artificial knee. The stiffness in Newtons per millimeter (N/mm) of each brace was calculated from the slope of the force-displacement curve. The cruciate brace with a valgus bend had the highest average stiffness at 192.61 N/mm (SD 28.53). The articulating sleeve was the least stiff with an average stiffness of 49.86 N/mm (SD 8.99). Stiffness of the cruciate brace was not statistically different compared to cruciate valgus ( p  = 0.083) or medial unloader ( p  = 0.098). In this experimental design, a cruciate brace with a valgus bend was shown to have the highest overall stiffness, while an articulating sleeve had the lowest stiffness. Future work will investigate whether this translates into clinical performance.

There is a limited data on epidemiology of primary and recurrent anterior cruciate ligament reconstruction (ACLR) in Canada. The objectives of this study were to examine the incidence and factors associated with recurrent ACLR (revision and contralateral ACLR) in a western Canadian province of Alberta. We conducted a retrospective cohort study with an average follow up of 5.7 years. Albertans aged 10 to 60 years with a history of primary ACLR between 2010/11 to 2015/16 were included in the study. Participants were followed up until March 2019 to observe outcomes: Ipsilateral revision ACLR and contralateral ACLR. Kaplan Meir approach was used to estimate event free survival and Cox proportional hazard regression analysis was conducted to identify associated factors. Of the total participants with a history of primary ACLR on a single knee (n = 9292), n = 359, 3.9% (95% confidence interval: 3.5-4.3) underwent a revision ACLR. A similar proportion among those having primary ACLR on either knee (n = 9676), n = 344, 3.6% (95% confidence interval: 3.2-3.9) underwent a contralateral primary ACLR. Young age (<30 years) was associated with increased risk of contralateral ACLR. Similarly, young age (<30 years), having initial primary ACLR in winter and having allograft were associated with a risk of revision ACLR. Clinicians can use these findings in their clinical practice and designing rehabilitation plans as well as to educate patients about their risk for recurrent anterior cruciate ligament tear and graft failure., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)

Purpose: Anterior cruciate ligament (ACL) injuries are one of the most frequently studied injuries in orthopedic care and research. However, limited epidemiological data are available in Canada regarding trend and distribution of anterior cruciate ligament reconstruction (ACLR). In this paper, our purpose was to assess trends of ACLR between 2002/03 and 2018/19 by age, sex, season of surgery, and location (inpatient vs outpatient) of surgery., Methods: In this descriptive epidemiological study of retrospective data available from Alberta Ministry of Health, we report annual incidence of ACLR between 2002/03 until 2018/19 among Albertans aged 10 years and older. Information was collected by authors from physician claims database for primary ACLR and revision ACLR and linked with other databases. Incidence proportions (number of ACLR/100,000 population) were calculated and compared by age category and gender over the study period., Results: A total of 28,401 primary ACLR and 2085 revision ACLR were identified during the study period. Age-standardized annual incidence of primary ACLR increased from 40.6 to 51.2 per 100,000 population aged 10 years and older. Average annual increase in ACLR incidence was higher among females (1.8% per years) compared to males (0.96% per year). The overall peak incidence and peak incidence among males was observed in 20-29 year age group, whereas peak incidence in females was observed in 10-19 years of age. The number of ACLR in females outnumbers those among males for 10-19 year age group. Generally, a lower proportion of ACLR were conducted in summer compared to other seasons. Primary ACLR conducted in outpatient setting increased from 72% in 2002/03 to 97% in 2018/19., Conclusion: The incidence of ACLR is increasing in Alberta, especially among females and among younger cohorts under 20 years of age. This information can help clinicians to provide patient education and policy-makers to design and implement targeted ACL injury prevention programs., Level of Evidence: Level III., (© 2022. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Osteoarthritis (OA) primarily affects mechanical load-bearing joints, with the knee being the most common. The prevalence, burden and severity of knee osteoarthritis (KOA) are disproportionately higher in females, but hormonal differences alone do not explain the disproportionate incidence of KOA in females. Mechanical unloading by spaceflight microgravity has been implicated in OA development in cartilaginous tissues. However, the mechanisms and sex-dependent differences in OA-like development are not well explored. In this study, engineered meniscus constructs were generated from healthy human meniscus fibrochondrocytes (MFC) seeded onto type I collagen scaffolds and cultured under normal gravity and simulated microgravity conditions. We report the whole-genome sequences of constructs from 4 female and 4 male donors, along with the evaluation of their phenotypic characteristics. The collected data could be used as valuable resources to further explore the mechanism of KOA development in response to mechanical unloading, and to investigate the molecular basis of the observed sex differences in KOA., (© 2022. The Author(s).)

Background: The use of particulated articular cartilage for repairing cartilage defects has been well established, but its use is currently limited by the availability and short shelf life of donor cartilage. Vitrification is an ice-free cryopreservation technology at ultralow temperatures for tissue banking. An optimized vitrification protocol has been developed for particulated articular cartilage; however, the equivalency of the long-term clinical efficacy of vitrified particulated articular cartilage compared with fresh articular cartilage has not yet been determined., Hypothesis: The repair effect of vitrified particulated cartilage from pigs would be equivalent to or better than that of fresh particulated cartilage stored at 4°C for 21 days., Study Design: Controlled laboratory study., Methods: A total of 19 pigs were randomly divided into 3 experimental groups: fresh particulated cartilage group (n = 8), vitrified particulated cartilage group (n = 8), and negative control group (no particulated cartilage in the defect; n = 3). An additional pig was used as the initial cartilage donor for the first set of surgical procedures. Pigs were euthanized after 6 months to obtain femoral condyles, and the contralateral condyle was used as the positive (no defect) control. Samples were evaluated for gross morphology using the Outerbridge and Osteoarthritis Research Society International (OARSI) scoring systems, histology (safranin O, collagen type I/II, DAPI), and chondrocyte viability using live-dead membrane integrity staining., Results: There were no infections after surgery, and all 19 pigs were followed for the duration of the study. The OARSI grades for the fresh and vitrified particulated cartilage groups were 2.44 ± 1.35 and 2.00 ± 0.80, respectively, while the negative control group was graded significantly higher at 4.83 ± 0.29. Analysis of histological and fluorescent staining demonstrated that the fresh and vitrified particulated cartilage groups had equivalent regeneration within cartilage defects, with similar cell viability and densities and expression of proteoglycans and collagen type I/II., Conclusion: The implantation of fresh or vitrified particulated cartilage resulted in the equivalent repair of focal cartilage defects when evaluated at 6 months after surgery., Clinical Relevance: The vitrification of particulated cartilage is a viable option for long-term storage for cartilage tissue banking and could greatly increase the availability of donor tissue for transplantation.

Background: - Chronic exertional compartment syndrome (CECS) is an exertional pain syndrome that typically affects the lower legs of participants involved in high-intensity running or marching activities. Surgical open fasciotomy is the standard treatment for recalcitrant cases of CECS. Alternative, minimally invasive fasciotomy techniques are emerging which may reduce rates of procedural complications and expedite recovery. The standard fasciotomy procedure for CECS may be improved by looped thread release with additional image guidance. The aim of this study was to describe and evaluate a novel technique of ultrasound-guided, minimally invasive looped thread fasciotomy for release of anterior and lateral compartments of the leg in a cadaveric model. We hypothesized that a fasciotomy of this type would be effective in achieving a target fasciotomy length of 80% of the length of a muscle compartment while avoiding injury to neurovascular structures., Materials and Methods: - We conducted a controlled laboratory study. Two proceduralists performed anterior and lateral compartment fasciotomies on ten lightly embalmed cadaveric legs. A total of twenty compartment releases were completed, using an ultrasound-guided, percutaneous looped cutting thread technique. The specimens were evaluated for length and completeness of fasciotomy, as well as any inadvertent injury to muscle, tendon, or neurovascular structures. Completeness of fasciotomy was compared between the anterior and lateral compartments., Results: - Eighteen of twenty (90%) fasciotomies were continuous. Fasciotomy length was consistently under target (72% complete). Completeness of lateral compartment release was significantly more likely to be under target compared to anterior compartment release (65% vs. 79%, p ​= ​0.014). Sixteen of twenty (80%) fasciotomies incurred no iatrogenic soft tissue injury; no injuries to nerves or vessels were observed., Discussion –: Ultrasound-guided, minimally invasive looped thread fasciotomy of the anterior and lateral leg compartments is feasible and can be successfully performed in a cadaveric model with low risk to neurovascular structures. However, further investigation is needed to improve completeness of release prior to recommendation for clinical use., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

Purpose: Our primary objectives were to (1) describe current approaches for kinetic measurements in individuals following anterior cruciate ligament reconstruction (ACLR) and (2) suggest considerations for methodological reporting. Secondarily, we explored the relationship between kinetic measurement system findings and patient-reported outcome measures (PROMs)., Methods: We followed the PRISMA extension for scoping reviews and Arksey and O'Malley's 6-stage framework. Seven electronic databases were systematically searched from inception to June 2020. Original research papers reporting parameters measured by kinetic measurement systems in individuals at least 6-months post primary ACLR were included., Results: In 158 included studies, 7 kinetic measurement systems (force plates, balance platforms, pressure mats, force-measuring treadmills, Wii balance boards, contact mats connected to jump systems, and single-sensor insoles) were identified 4 main movement categories (landing/jumping, standing balance, gait, and other functional tasks). Substantial heterogeneity was noted in the methods used and outcomes assessed; this review highlighted common methodological reporting gaps for essential items related to movement tasks, kinetic system features, justification and operationalization of selected outcome parameters, participant preparation, and testing protocol details. Accordingly, we suggest considerations for methodological reporting in future research. Only 6 studies included PROMs with inconsistency in the reported parameters and/or PROMs., Conclusion: Clear and accurate reporting is vital to facilitate cross-study comparisons and improve the clinical application of kinetic measurement systems after ACLR. Based on the current evidence, we suggest methodological considerations to guide reporting in future research. Future studies are needed to examine potential correlations between kinetic parameters and PROMs., (© 2021. The Author(s).)

Bone marrow-derived mesenchymal stem cells (BMSCs) have the potential to form the mechanically responsive matrices of joint tissues, including the menisci of the knee joint. The purpose of this study is to assess BMSC's potential to engineer meniscus-like tissue relative to meniscus fibrochondrocytes (MFCs). MFCs were isolated from castoffs of partial meniscectomy from nonosteoarthritic knees. BMSCs were developed from bone marrow aspirates of the iliac crest. All cells were of human origin. Cells were cultured in type I collagen scaffolds under normoxia (21% O 2 ) for 2 weeks followed by hypoxia (3% O 2 ) for 3 weeks. The structural and functional assessment of the generated meniscus constructs were based on glycosaminoglycan (GAG) content, histological appearance, gene expression, and mechanical properties. The tissues formed by both cell types were histologically positive for Safranin O stain and appeared more intense in the BMSC constructs. This observation was confirmed by a 2.7-fold higher GAG content. However, there was no significant difference in collagen I ( COL1A2 ) expression in BMSC- and MFC-based constructs ( p  = 0.17). The expression of collagen II ( COL2A1 ) and aggrecan ( ACAN ) were significantly higher in BMSCs than MFC ( p  ≤ 0.05). Also, the gene expression of the hypertrophic marker collagen X ( COL10A1 ) was 199-fold higher in BMSCs than MFC ( p  < 0.001). Moreover, relaxation moduli were significantly higher in BMSC-based constructs at 10-20% strain step than MFC-based constructs. BMSC-based constructs expressed higher COL2A1 , ACAN , COL10A1 , contained higher GAG content, and exhibited higher relaxation moduli at 10-20% strain than MFC-based construct. Impact statement Cell-based tissue engineering (TE) has the potential to produce functional tissue replacements for irreparably damaged knee meniscus. But the source of cells for the fabrication of the tissue replacements is currently unknown and of research interest in orthopedic TE. In this study, we fabricated tissue-engineered constructs using type I collagen scaffolds and two candidate cell sources in meniscus TE. We compared the mechanical properties of the tissues formed from human meniscus fibrochondrocytes and bone marrow-derived mesenchymal stem cells (BMSCs). Our data show that the tissues engineered from the BMSC are mechanically superior in relaxation modulus.

Background: Exercise is widely regarded to improve pain and function in patients with knee osteoarthritis (OA) through building supportive muscle mass, facilitating weight loss, and through the other beneficial effects associated with it., Purpose: To explore literature that presents clinical guidelines for the use of exercise in the treatment of knee OA to inform an evidence-based position statement for the Arthroscopy Association of Canada., Study Design: Position statement., Methods: PubMed, MEDLINE, Embase, and Cochrane databases were searched for guidelines commenting on the role of exercise for knee OA. The search was limited to guidelines published in the last 10 years. Articles were screened for relevance, focusing on recently published research with clinical guidelines. Inclusion criteria involved all articles providing clinical guidelines for exercise and knee OA., Results: Eight guidelines were identified. All eight recommended exercise as an important component of treatment for knee OA, with 6/8 strongly recommending it., Conclusion: Exercise is an effective and important component of the non-pharmacological management of knee OA. The Arthroscopy Association of Canada strongly recommends the use of exercise in the management of knee OA., (© The Author(s) 2021.)

Background: The all-inside anterior cruciate ligament reconstruction (ACLR) procedure uses a single hamstring tendon folded twice and secured to itself to form a 4-stranded graft. There are several possible configurations for preparing the graft., Purpose: To investigate the biomechanical properties of a new graft preparation technique in comparison with 2 commonly used configurations., Study Design: Controlled laboratory study., Methods: Five porcine flexor tendons were prepared into the test graft configuration: side-to-side fixation with a backup fixation at the button loop (graft M). The test configuration was compared with the results of a previous study that included grafts with simple interrupted sutures (graft A; n = 5) and end-to-end fixation (graft C; n = 5). All grafts were subjected to the same mechanical testing protocol to determine the mean failure load, stiffness, rate of elongation, and total elongation during both cyclic loading and pull to failure. Differences between groups were evaluated., Results: Graft A had a significantly lower failure load (637 ± 99 N) compared with graft M (883 ± 66 N; P = .002) and graft C (846 ± 26 N; P = .002). Graft A also had significantly lower stiffness (166 ± 12 N/mm) compared with graft M (215 ± 8 N/mm; P < .001) and graft C (212 ± 11 N/mm; P < .001). Graft C had a significantly lower elongation during cyclic loading (3.42 ± 0.24 mm) compared with graft M (4.37 ± 0.74 mm; P = .026) and graft A (4.90 ± 0.88 mm; P = .006). The unsecured fixation was the weakest graft, with the lowest failure load and stiffness. The new side-to-side configuration and end-to-end configuration were equally strong., Conclusion: The new side-to-side configuration was not biomechanically superior to the end-to-end configuration; however, they were both stronger than unsecured fixation., Clinical Relevance: As the all-inside ACLR is gaining popularity, this study provides surgeons with a new method of preparing grafts and evaluates the method with respect to currently used configurations., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: Support for this study was received from the Edmonton Civic Employees Charitable Fund. The adjustable button-loop devices used were contributed by Arthrex. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2021.)

Background: All-inside anterior cruciate ligament reconstruction (ACLR) is an emerging technique used to treat ACL injuries. The all-inside technique uses a 4-stranded graft made from a single tendon that is looped on itself. The 4 strands of the graft must be secured to each other to become a closed-loop structure. Various suture configurations exist to secure the graft to adjustable loop devices, and there is a lack of data to support one technique over another. In addition to the primary sutures used to fasten the graft together, accessory sutures can be tied over the button as secondary fixation., Purpose: To evaluate biomechanical properties of 4-stranded grafts prepared in 5 different configurations., Study Design: Controlled laboratory study., Methods: Porcine flexor tendons (N = 25) were prepared in 5 different configurations (n = 5 tendons per group): simple-interrupted sutures (unsecured fixation), side-to-side fixation with and without secondary fixation, and end-to-end fixation with and without secondary fixation. The grafts were put through the same mechanical testing protocol (cyclic loading, pull to failure) to measure average load at graft failure, average displacement at failure, average stiffness, and average elongation rate. Differences between graft preparation techniques were investigated using 1-way analyses of variance (ANOVAs) with post hoc t tests ( P < .05)., Results: Significant 1-way ANOVAs for each biomechanical property were found. Unsecured fixation was the weakest graft preparation with the lowest stiffness (167 ± 12 N/mm), lowest ultimate failure load (637 ± 99 N), and highest elongation rate (0.0033 ± 0.0007 mm/s). End-to-end fixation without secondary fixation showed the highest ultimate failure load (846 ± 26 N), highest stiffness (212 ± 10 N/mm), and lowest rate of elongation (0.0025 ± 0.0001 mm/s). End-to-end fixation, both with and without secondary fixation, as well as side-to-side fixation with secondary fixation showed significantly higher ultimate failure loads than grafts with unsecured fixation. End-to-end fixation performed better than side-to-side fixation; however, for most variables, the difference was not statistically significant. Secondary fixation did not provide significant improvement., Conclusion: The all-inside ACL graft with simple-interrupted sutures is biomechanically inferior to a graft that has its free ends secured to the adjustable tibial loop. Adding secondary fixation to the tibial button does not significantly change the biomechanical properties. Further clinical studies are required to determine whether these findings translate into differences in clinical outcome., Clinical Relevance: All-inside ACLR is gaining popularity in hamstring ACL reconstructive techniques. These results provide surgeons with guidance on the best graft preparation method when using a single quadrupled hamstring tendon graft., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: Funding for this study was received from the Edmonton Civic Employees Charitable Fund. The adjustable-loop buttons used in this study were donated by Arthrex. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2020.)

Background: Treatment of patients with anterior cruciate ligament (ACL) injuries is often complicated by secondary damage to the meniscus and cartilage., Purpose: To assess the association between time from ACL tear to ACL reconstruction (ACLR) and the presence of intra-articular injuries at the time of ACLR, including meniscal tears, irreparable meniscal tears, chondral damage, and knee compartment degenerative changes., Study Design: Cross-sectional study; Level of evidence, 3., Methods: Consecutive patients undergoing primary ACLR performed by a single surgeon in a Canadian health system over a 5.5-year period were included. Age at ACLR, activity level prior to injury, time from injury to ACLR (TFI), presence and degree of radiographic osteoarthritic features (International Knee Documentation Committee [IKDC] score by tibiofemoral and/or patellofemoral compartment), and surgeon-recorded meniscal lesions (presence and treatment [repair or excision]) and chondral lesions (International Cartilage Repair Society [ICRS] scale grade >2) at time of ACLR were extracted from medical records. The association between TFI (in quartiles: first quartile [0-36 wk] through fourth quartile [110-1000 wk]) and each outcome was assessed with multivariable logistic regression adjusted for age at ACLR and activity level., Results: A total of 860 individual patient records were included. The median patient age was 27.0 years (range, 12-63 years), 47.5% were female (403/849), and 47.2% were classified as playing competitive or professional sports versus recreational sport (337/714). After adjustment for age and activity level, TFI was associated with presence of medial meniscal tear (odds ratio [OR] of fourth-quartile vs first-quartile patients, 3.86; 95% CI, 2.38-6.24; P < .001), medial meniscal tear requiring greater than two-thirds meniscectomy (OR, 5.64; 95% CI, 2.99-10.67; P < .001), medial femoral condyle chondral damage (OR, 3.42; 95% CI, 1.96-5.95; P < .001), and medial tibiofemoral radiographic osteoarthritic features (OR, 22.03; 95% CI, 5.17-93.86; P < .001). TFI was not associated with adverse outcomes in the lateral tibiofemoral or patellofemoral compartments., Conclusion: Increases in TFI are associated with medial meniscal tears, including irreparable medial meniscal tears, medial femoral condyle chondral damage, and early medial tibiofemoral compartment degenerative changes at time of ACLR. These findings highlight the importance of establishing a timely diagnosis and implementing an appropriate treatment plan for patients with ACL injuries. This approach may prevent further instability episodes that place patients at risk of sustaining additional intra-articular injuries in the affected knee. Further research is required to understand the implications of TFI and to determine whether decreasing the TFI alters the natural history after an ACL injury., Competing Interests: The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Background: Delayed anterior cruciate ligament (ACL) reconstruction may be associated with increased risk of subsequent knee joint damage and osteoarthritis (OA). The relationship between recurrent instability episodes and meniscal or cartilage damage after first-time ACL injury is unknown., Purpose: To assess the association between recurrent knee instability episodes and prevalence of meniscal lesions, cartilage damage, and OA after first-time ACL injury., Study Design: Systematic review; Level of evidence, 4., Methods: Six electronic databases were systematically searched using keywords and Medical Subject Heading terms. Studies selected were of English language, included original data, had a prospective design, and provided an outcome of recurrent instability and meniscal lesions, cartilage damage, or OA after first-time ACL injury. Adjusted odds ratios (ORs) were extracted or unadjusted ORs (95% CI) were calculated. PRISMA guidelines were followed, and 2 independent raters assessed study quality using Downs and Black criteria., Results: Of 905 potentially relevant studies, 7 were included. Sample sizes ranged from 43 to 541, and Downs and Black scores ranged from 2 to 12. Clinical and methodological heterogeneity precluded meta-analysis. Six studies reported a positive association between recurrent instability episodes and medial meniscal damage (OR range, 3.46 [95% CI, 1.24-9.99] to 11.56 [1.37-521.06]). The association between instability episodes and lateral meniscal or cartilage damage was inconsistent. No studies examined the association between instability episodes and OA., Conclusion: This systematic review provides preliminary evidence that recurrent instability episodes after first-time ACL injury may be associated with increased odds of medial meniscal damage. This highlights the importance of early diagnosis, education, and treatment for individuals with ACL injury, all of which must include a specific focus on the prevention and management of instability episodes. High-quality, prospective cohort studies are needed that assess the effects of diagnostic and treatment delay, recurrent instability episodes on secondary meniscal and cartilage damage, and OA after an initial ACL injury., Competing Interests: The authors declared that they have no conflicts of interest in the authorship and publication of this contribution.

Background: Evidence-based guidelines on the use of immobilization in the management of common acute soft-tissue knee injuries do not exist. Our objective was to explore the practice patterns of emergency physicians (EPs), sports medicine physicians (SMPs) and orthopedic surgeons (OS) regarding the use of early immobilization in the management of these injuries., Methods: We developed a web-based survey and sent it to all EPs, SMPs and OS in a Canadian urban centre. The survey was designed to assess the likelihood of prescribing immobilization and to evaluate factors associated with physicians from these 3 disciplines making this decision., Results: The overall response rate was 44 of 112 (39%): 17 of 58 (29%) EPs, 7 of 15 (47%) SMPs and 20 of 39 (51%) OS. In cases of suspected meniscus injuries, 9 (50%) EPs indicated they would prescribe immobilization, whereas no SMPs and 1 (5%) OS would immobilize (p = 0.002). For suspected anterior cruciate ligament injuries, 13 (77%) EPs, 2 (29%) SMPs and 5 (25%) OS said they would immobilize (p = 0.005). For lateral collateral ligament injuries, 9 (53%) EPs, no SMPs and 6 (32%) OS would immobilize (p = 0.04). All respondents would prescribe immobilization for a grossly unstable knee., Conclusion: We found that EPs were are more likely to prescribe immobilization for certain acute soft-tissue knee injuries than SMPs and OS. The development of an evidenced- based guideline for the use of knee immobilization after acute soft-tissue injury may reduce practice variability.

In an approach toward the identification of hitherto unknown proteins involved in the function of the blood-brain barrier, we constructed a pig brain microvessel-derived cDNA library that is enriched in blood-brain barrier specific sequences by means of subtractive cloning. Sequence analysis of selected clones revealed that one of the cDNAs encoded porcine apolipoprotein (apo) A-1. The identity of apo A-1 mRNA was further confirmed by in vitro translation of RNA from brain microvascular endothelial cells and subsequent immunoprecipitation with an antibody against human apo A-1. We further investigated the expression of apo A-1 mRNA in several tissues and in endothelial cells of the pig. It is shown that cultured brain microvascular endothelial cells provide an in vitro model to study the expression and function of apo A-1 in the microvasculature of the brain.