Safety and Effectiveness of a Perturbation-based Neuromuscular Training Program on Dynamic Balance in Adolescent Females: A Randomized Controlled Trial.

BACKGROUND: Adolescent females are at much greater risk for ACL injury than their male counterparts when participating in the same sports. Preventative and pre-operative rehabilitation neuromuscular (NM) exercise programs are often recommended to improve knee function and reduce injury rates. The effectiveness of perturbation-based NM training program has been established in an adult population but has yet to be investigated in the at-risk adolescent female population. PURPOSE: To determine the effectiveness of a perturbation-based NM exercise program in a group of physically active adolescent females. STUDY DESIGN: Prospective randomized trial. METHODS: Twenty-four healthy and an exploratory group of 10 ACL-injured females (ages 12-18) were equally randomized into a perturbation-based NM training or control group and evaluated before and after a five-week intervention period. The primary outcome of dynamic balance was measured using the Y-Balance test (YBT); secondary outcome measures included lower limb strength, proprioception, and flexibility. RESULTS: The perturbation-based NM training intervention was safely completed by all participants but had no significant effect on YBT scoring, lower limb strength, proprioception or flexibility in either the healthy or ACL-injured groups. CONCLUSIONS: Perturbation-based NM training is safe, but may offer little preventative benefit for healthy or pre-operative rehabilitation benefit for ACL-injured adolescent females. Future research should examine whether the effectiveness of perturbation-based NM training is influenced by the length of the training intervention, training intensity, or when it is combined with other forms of prophylactic or pre-surgical rehabilitation frequently used with at-risk adolescent females who regularly participate in sport. LEVEL OF EVIDENCE: Level 3.

Lower Extremity Kinematics of the Y-Balance Test in Healthy and ACL Injured Adolescent Females.

BACKGROUND: Adolescent females are at significant risk for sustaining an ACL injury. The Y-Balance Test (YBT) is frequently used to evaluate neuromuscular control and lower extremity function. However, few studies have quantified 2D lower extremity kinematics during performance of the YBT, and there is an absence of kinematic data specific to at-risk adolescent females. PURPOSE: To examine lower extremity joint kinematics during execution of the YBT by healthy and ACL-injured adolescent females. STUDY DESIGN: Prospective cohort. METHODS: Twenty-five healthy and ten ACL-injured (mean time from injury 143 days) adolescent females were assessed using the YBT. Sagittal and frontal plane knee and ankle motion was video recorded during execution of the YBT anterior reach movement. Ankle dorsi-flexion, knee flexion, and knee valgus angles were quantified via kinematic analysis. ANOVAs with a post hoc Bonferroni correction were used to compare YBT scoring (%LL) and kinematic data between groups. Pearson product-moment correlations determined the relationship between kinematic data and YBT scoring. RESULTS: Healthy and ACL-injured subjects demonstrated similar YBT scores and lower extremity kinematic data. Healthy subjects demonstrated a weak positive correlation between ankle dorsiflexion and YBT scoring, and a weak negative correlation between knee valgus and YBT scoring. These relationships did not exist for ACL-injured subjects. Kinematic data for both groups also demonstrated a large degree of variability, regardless of YBT score. CONCLUSIONS: Adolescent females frequently utilize a variety of lower extremity movement strategies when performing a functional movement task, and scoring on the YBT offers limited insight regarding lower extremity joint kinematics and ACL-injury risk in a physically active adolescent female population. LEVEL OF EVIDENCE: Level 3.

Perceived vs. true glenoid anchor placement: a cadaveric comparison of the beach chair and lateral position.

PURPOSE: To explore whether patient position influences a surgeon's ability to accurately judge anchor position on the glenoid. MATERIALS AND METHODS: Two anchors were inserted into the glenoid of 8 shoulders. Arthroscopic videos were taken from 3 views (posterior beach chair [pBC], posterior lateral decubitus [pLD], and anterosuperolateral decubitus [asLD]). The shoulders were disarticulated to identify "true" anchor position. Seventeen shoulder surgeons reviewed the videos and indicated anchor positions using the "clock face" method. Accuracy was measured within tolerances, ranging from zero (exact), 0.5 (half-hour), 1.0, and 1.5 hours of "true" position. Intra- and inter-rater agreement was calculated. Post hoc analyses explored for bias dependent on surgical side. RESULTS: The overall accuracy was 34.0%. At tolerances of 0.5, 1.0, and 1.5 hours, accuracy increased to 82.4%, 95.4%, and 98.0%. With a 30° scope, identification of exact position was more accurate in pBC than pLD (odds ratio [OR] = 1.397; P = .029) but not asLD (OR =1.341; P = .197). At a tolerance of 0.5 hour, the 30° scope was more accurate in pBC than both pLD (OR = 1.444; P = .011) and asLD (OR = 1.728; P = .009). In left shoulders, anchors were perceived as more inferior than true position in asLD and pLD. In right shoulders, anchors were perceived as more superior than true position from pBC and pLD. Inter- and intrarater agreement were highest in pBC with a 30° scope (30° scope weighted kappa = 0.783 and 70° scope weighted kappa = 0.853, respectively). CONCLUSION: Judgment of anchor position on video is most accurate in a pBC view. Inter- and intrarater reliability were also highest from a pBC view.

Associations between concussion and risk of diagnosis of psychological and neurological disorders: a retrospective population-based cohort study.

OBJECTIVE: To investigate associations between concussion and the risk of follow-up diagnoses of attention-deficit hyperactivity disorder (ADHD), mood and anxiety disorders (MADs), dementia and Parkinson's disease. DESIGN: A retrospective population-based cohort study. SETTING: Administrative health data for the Province of Manitoba between 1990-1991 and 2014-2015. PARTICIPANTS: A total of 47 483 individuals were diagnosed with a concussion using International Classification of Diseases (ICD) codes (ICD-9-CM: 850; ICD-10-CA: S06.0). All concussed subjects were matched with healthy controls at a 3:1 ratio based on age, sex and geographical location. Associations between concussion and conditions of interest diagnosed later in life were assessed using a stratified Cox proportional hazards regression model, with adjustments for socioeconomic status and pre-existing medical conditions. RESULTS: 28 021 men (mean age ±SD, 25±18 years) and 19 462 women (30±21 years) were included in the concussion group, while 81 871 men (25±18 years) and 57 159 women (30±21 years) were included in the matched control group. Concussion was associated with adjusted hazard ratios of 1.39 (95% CI 1.32 to 1.46, p<0.001) for ADHD, 1.72 (95% CI 1.69 to 1.76; p<0.001) for MADs, 1.72 (95% CI 1.61 to 1.84; p<0.001) for dementia and 1.57 (95% CI 1.41 to 1.75; p<0.001) for Parkinson's disease. CONCLUSION: Concussion was associated with an increased risk of diagnosis for all four conditions of interest later in life.

The Effects of Acute Anaerobic Exercise on the Cardiovascular and Metabolic Response to the Cold Pressor Test in Healthy Adult Males.

Little is known about the physiological response to the cold pressor test (CPT) when in a clinically-induced state of autonomic nervous system (ANS) imbalance, despite its utility in various disease- and injury-states. To date, research in this area is limited to acute aerobic and isometric exercise, with a paucity of research investigating the effects of anaerobic exercise on the physiological response to the CPT. Therefore, the purpose of our study was to assess the effects of the Wingate anaerobic cycle test (WAT) on cardiovascular (CV) and metabolic recovery following the CPT in a group of healthy adult males. A pre-post intervention study was conducted, whereby 10 healthy adult males (age = 29 ± 4 years, height = 182 ± 7 cm, mass = 83 ± 9 kg) completed a baseline cold pressor test (CPT-only) and a follow-up cold pressor test preceded by a Wingate anaerobic exercise test (WAT+CPT). Recovery slopes for various CV and metabolic variables, including heart rate (HR), blood pressure (BP), and relative oxygen consumption (V̇O2) were analyzed using single-subject analysis, with celeration line slopes calculated for all participants in the CPT-only and WAT+CPT testing sessions. Celeration line slopes were compared between testing sessions using paired t-tests. No differences were identified for recovery slopes for HR (p = .295), diastolic BP (p = .300), and relative V̇O2 (p = .176) when comparing CPT-only and WAT+CPT testing sessions. Our results suggest that the CPT elicits a CV and metabolic response beyond that elicited solely by an acute bout of anaerobic exercise. As such, the CPT may be able to serve as a surrogate test for anaerobic exercise for individuals where high-intensity exercise may be contraindicated. Future research is warranted however, as the specific physiological mechanisms governing the observed responses have yet to be elucidated.

Evaluation of Early Submaximal Exercise Tolerance in Adolescents with Symptomatic Sport-related Concussion.

PURPOSE: This study aimed to compare cardiorespiratory response to a graded aerobic exercise challenge between adolescents with symptomatic sport-related concussion (SSRC) and healthy control subjects. METHODS: A quasiexperimental nonrandomized study at a multidisciplinary pediatric concussion program was conducted. Thirty-four adolescents with SSRC (19 males and 15 females) and 40 healthy control subjects (13 males and 27 females) completed the Buffalo Concussion Treadmill Testing (BCTT) until either symptom exacerbation or volitional fatigue. Main outcome measures included heart rate (HR), oxygen consumption (V˙O2), carbon dioxide production (V˙CO2), and minute ventilation (V˙E) at rest and at test termination, and change from rest in variables (ΔHR, ΔV˙O2, ΔV˙CO2, and ΔV˙E) during the first five stages of the BCTT. Main outcomes were analyzed using three-way mixed-model ANOVA, with group status (control vs SSRC) and sex (male vs female) as between-subject factors, and time (BCTT stage) as the within-subject factor. RESULTS: No group differences in resting HR, systolic and diastolic blood pressure, ΔV˙O2, V˙CO2, and V˙E were observed. During the first five stages of the BCTT, no group differences in ΔV˙O2, V˙CO2, and V˙E were observed; however, SSRC patients demonstrated higher RPE (P < 0.0005) compared with control subjects. No sex-based differences were observed among SSRC patients on measures collected at rest and during early stages of BCTT. CONCLUSIONS: Although SSRC patients exhibited higher RPE during a graded aerobic exercise challenge, no differences in cardiorespiratory response were observed compared with control subjects exercising at equivalent workloads. Further work is needed to elucidate the physiological mechanisms underlying exercise intolerance after SSRC.

Three-Year Longitudinal Fitness Tracking in Top-Level Competitive Youth Ice Hockey Players.

Cordingley, DM, Sirant, L, MacDonald, PB, and Leiter, JR. Three-year longitudinal fitness tracking in top-level competitive youth ice hockey players. J Strength Cond Res 33(11): 2909-2912, 2019-The purpose of this retrospective review was to report the physical and physiological development of top-level competitive male youth hockey players for 3 consecutive years (13, 14, and 15 years of age). Before each hockey season, the athletes (n = 103) underwent a fitness testing combine to assess aerobic, anaerobic, and musculoskeletal fitness. The tests performed included the height, body mass, body fat percentage determined by skinfolds, push-ups, chin-ups, plank, broad jump, grip strength 20-m shuttle run, Wingate bike test, and 5-10-5 shuttle test. Height and body mass increased with each consecutive year (p < 0.05) with no change in body fat percentage. Chin-ups, broad jump, and grip strength all improved with age (p < 0.001). However, push-ups only improved from 13 to 14 years of age (p < 0.001), whereas maximal plank duration decreased from 14 to 15 years of age (p < 0.05). The total distance covered during the 20-m shuttle run decreased from 14 to 15 years of age (p < 0.05). Absolute peak and average power increased with each age increase (p < 0.001), but relative peak and average power only increased from 13 to 14 years of age (p < 0.05). There was no change in the fatigue index with age. The 5-10-5 shuttle test improved with each age increase (p < 0.05). Over a 3-year period (13-15 years of age), there are many physical and physiological changes that occur in top-level competitive male hockey players. Having a better understanding of how these athletes develop could aid in the implementation of specific on- and off-ice training programs.

Physical fitness of medical residents: Is the health of surgical residents at risk?

Background: Postgraduate medical residency programs are laborious and timeintensive, and can be physically, intellectually and emotionally demanding. These working conditions may lead to the neglect of personal health and well-being. The objective of this study was to compare the anthropometric and fitness characteristics of surgical and nonsurgical medical residents. We hypothesized that there is a difference in physical health between these 2 groups. Methods: Medical residents completed a demographic information questionnaire and were assessed by trained staff for height, weight, body fat percentage, muscular strength and endurance, and peak oxygen consumption (V̇ᴏ2peak). The average number of working hours per week was also documented. Results: Forty-five residents (21 surgical and 24 nonsurgical; 31 men and 14 women) participated in the study. Surgical residents worked more hours per week on average than nonsurgical residents (p = 0.02) and had a higher body mass index (BMI) (p = 0.04) and lower V̇ᴏ2peak (p = 0.01). Conclusion: Surgical residents worked more hours than nonsurgical residents, which may have contributed to their higher BMI and lower aerobic fitness levels. Despite a heavy workload, it is important for all medical residents to find strategies to promote a healthy lifestyle for both themselves and their patients to ensure long-term well-being.

Contexte: En médecine, les programmes de résidence postdoctoraux sont fastidieux et chronovores; et ils peuvent être exigeants physiquement, intellectuellement et émotivement. De telles conditions de travail forcent parfois les résidents à négliger leur santé et leur bien-être personnels. L'objectif de cette étude était de comparer les caractéristiques anthropométriques et la forme physique des résidents de chirurgie et d'autres spécialités médicales. Selon notre hypothèse, ces 2 groupes ne présentent pas le même état de santé physique. Méthodes: Les résidents ont répondu à un questionnaire démographique et des assistants dument formés ont mesuré leur taille, leur poids, leur pourcentage de graisse corporelle, leur force musculaire, leur endurance et leur consommation d'oxygène maximale (V̇ᴏ2max). Le nombre d'heures de travail hebdomadaires a aussi été pris en compte. Résultats: Quarante-cinq résidents (21 de chirurgie et 24 d'autres spécialités; 31 hommes et 14 femmes) ont participé à l'étude. Les résidents en chirurgie travaillaient en moyenne plus d'heures par semaine que les autres résidents (p = 0,02) et présentaient un indice de masse corporelle (IMC) plus élevé (p = 0,04) et une V̇ᴏ2max plus basse (p = 0,01). Conclusion: résidents en chirurgie travaillaient plus d'heures que les autres résidents, ce qui peut avoir contribué à leur IMC plus élevé et à leur moins bonne capacité aérobique. Malgré la lourdeur de leur fardeau de travail, il est important que tous les résidents en médecine trouvent des stratégies pour adopter de saines habitudes de vie pour eux-mêmes et leurs patients, et assurer leur mieux-être à long terme.

Development of Anaerobic Fitness in Top-Level Competitive Youth Ice Hockey Players.

Leiter, JR, Cordingley, DM, and MacDonald, PB. Development of anaerobic fitness in top-level competitive youth ice hockey players. J Strength Cond Res 32(9): 2612-2615, 2018-Ice hockey is a physiologically complex sport involving both the anaerobic and aerobic energy systems. The purpose of this study was to evaluate the anaerobic power output (PO) of top-level competitive youth hockey players. It was hypothesized that with each successive increase in age, there would be an associated change in anaerobic PO. Two hundred and fifty-one male hockey players between the ages of 13-17 years participated in this study. All athletes completed a 30-second Wingate test as part of a preseason physiological and fitness combine. A 1-way analysis of variance was performed to compare peak PO (POpeak), average PO (POavg), and fatigue index between all age groups. A Tukey's post hoc test was used to determine changes in immediately successive age groups for all variables. Age categories were grouped as 13 years old (yrs) (n = 72), 14 yrs (n = 68), 15 yrs (57) and 16 yrs (n = 54, including 11 athletes 17 yrs). Absolute POpeak significantly increased with all age increases. Relative POpeak, absolute POavg, and relative POavg increased between the ages of 13 and 14 years, and 14 and 15 years, but not between the ages 15 and 16 years. There were no changes in fatigue index between any successive age groups. Anaerobic PO increases with an increase in age with no associated change in fatigue index. Athletes, coaches, and parents can use this normative data to help prepare the player for upcoming seasons in which there may be an increase in level or age class.

Radiostereometric analysis of keeled versus pegged glenoid components in total shoulder arthroplasty: a randomized feasibility study.

BACKGROUND: This study aimed to assess differences in the fixation and functional outcomes between pegged and keeled all-polyethylene glenoid components for standard total shoulder arthroplasty. METHODS: Patients were randomized to receive a keeled or pegged all-polyethylene glenoid component. We used model-based radiostereometric analysis (RSA) to assess glenoid fixation and subjective outcome measures to assess patient function. Follow-up examinations were completed at 6 weeks and 6, 12 and 24 months after surgery. Modifications to the RSA surgical, imaging and analytical techniques were required throughout the study to improve the viability of the data. RESULTS: Stymied enrolment resulted in only 16 patients being included in our analyses. The RSA data indicated statistically greater coronal plane migration in the keeled glenoid group than in the pegged group at 12 and 24 months. Functional outcome scores did not differ significantly between the groups at any follow-up. One patient with a keeled glenoid showed high component migration after 24 months and subsequently required revision surgery 7 years postoperatively. CONCLUSION: Despite a small sample size, we found significant differences in migration between glenoid device designs. Although clinically these findings are not robust, we have shown the feasibility of RSA in total shoulder arthroplasty as well as the value of a high-precision metric to achieve objective results in a small group of patients.

CONTEXTE: Cette étude avait pour objet d'évaluer les différences sur le plan de la fixation et des résultats fonctionnels entre les composants glénoïdiens à plots et à quille, tous deux en polyéthylène, dans une arthroplastie totale traditionnelle de l'épaule. MÉTHODES: La répartition des composants glénoïdiens en polyéthylène à plots et à quille a été faite de façon aléatoire. Nous nous sommes servis de modèles d'analyses radiostéréométriques (ARS) pour évaluer la fixation glénoïdienne et les indicateurs de résultats subjectifs, ce qui nous a ainsi permis d'évaluer les résultats fonctionnels des patients. Quatre examens de suivi ont été réalisés après la chirurgie : à 6 semaines, puis à 6 mois, à 12 mois et à 24 mois. Tout au long de l'étude, des ajustements ont été apportés aux modèles d'ARS de la chirurgie, de l'imagerie et des analyses afin d'améliorer la viabilité des données. RÉSULTATS: Des problèmes liés au recrutement ont fait en sorte que nous n'avons retenu que 16 patients dans le cadre de nos analyses. Les données d'ARS ont montré une migration statistiquement plus grande du plan frontal dans le groupe quille que dans le groupe plots à 12 et à 24 mois. Les résultats fonctionnels étaient sensiblement les mêmes d'un groupe à l'autre, peu importe le moment du suivi. Un patient du groupe quille a présenté une migration très importante du composant après 24 mois; il a dû subir une chirurgie de révision 7 ans après la chirurgie initiale. CONCLUSION: Malgré la petite taille de l'échantillon, nous avons observé des différences significatives dans la migration des composants, selon le type utilisé. Même si ces observations ne permettent pas d'arriver à des conclusions robustes d'un point de vue clinique, nous avons montré qu'il est possible d'avoir recours aux ARS en contexte d'arthroplastie totale de l'épaule et démontré la valeur associée à l'utilisation de mesures de haute précision pour l'obtention de résultats objectifs chez un petit groupe de patients.

Fibrosis, low vascularity, and fewer slow fibers after rotator-cuff injury.

INTRODUCTION: Rotator-cuff injury (RCI) represents 50% of shoulder injuries, and prevalence increases with age. Even with successful tendon repair, muscle and joint function may not return. METHODS: To explore the dysfunction, supraspinatus and ipsilateral deltoid (control) muscles were biopsied during arthroscopic RCI repair for pair-wise histological and protein-expression studies. RESULTS: Supraspinatus showed fiber atrophy (P < 0.0001), fibrosis (by Sirius Red, P = 0.05), reduced vascular density (P < 0.001), and a lower proportion of slow fibers (P < 0.0001) compared with the ipsilateral control muscle. There were also higher levels of atrogin-1 (P = 0.05), vascular endothelial growth factor (VEGF, P < 0.01), and dystrophin (P < 0.008, relative to fiber diameter) versus control. CONCLUSIONS: Adaptive changes in vascular endothelial growth factor and dystrophin were likely associated with reduced vascular supply, fatigue resistance, and fibrosis, accompanied by disuse atrophy from mechanical unloading of supraspinatus after tendon tear. Treatment to promote growth and vascularity in atrophic supraspinatus muscle may help improve functional outcome after surgical repair. Muscle Nerve 55: 715-726, 2017.

Altered Satellite Cell Responsiveness and Denervation Implicated in Progression of Rotator-Cuff Injury.

BACKGROUND: Rotator-cuff injury (RCI) is common and painful; even after surgery, joint stability and function may not recover. Relative contributions to atrophy from disuse, fibrosis, denervation, and satellite-cell responsiveness to activating stimuli are not known. METHODS AND FINDINGS: Potential contributions of denervation and disrupted satellite cell responses to growth signals were examined in supraspinatus (SS) and control (ipsilateral deltoid) muscles biopsied from participants with RCI (N = 27). Biopsies were prepared for explant culture (to study satellite cell activity), immunostained to localize Pax7, BrdU, and Semaphorin 3A in satellite cells, sectioning to study blood vessel density, and western blotting to measure the fetal (γ) subunit of acetylcholine receptor (γ-AchR). Principal component analysis (PCA) for 35 parameters extracted components identified variables that contributed most to variability in the dataset. γ-AchR was higher in SS than control, indicating denervation. Satellite cells in SS had a low baseline level of activity (Pax7+ cells labelled in S-phase) versus control; only satellite cells in SS showed increased proliferative activity after nitric oxide-donor treatment. Interestingly, satellite cell localization of Semaphorin 3A, a neuro-chemorepellent, was greater in SS (consistent with fiber denervation) than control muscle at baseline. PCAs extracted components including fiber atrophy, satellite cell activity, fibrosis, atrogin-1, smoking status, vascular density, γAchR, and the time between symptoms and surgery. Use of deltoid as a control for SS was supported by PCA findings since "muscle" was not extracted as a variable in the first two principal components. SS muscle in RCI is therefore atrophic, denervated, and fibrotic, and has satellite cells that respond to activating stimuli. CONCLUSIONS: Since SS satellite cells can be activated in culture, a NO-donor drug combined with stretching could promote muscle growth and improve functional outcome after RCI. PCAs suggest indices including satellite cell responsiveness, atrogin-1, atrophy, and innervation may predict surgical outcome.

Aerobic Development of Elite Youth Ice Hockey Players.

Ice hockey is a physiologically complex sport requiring aerobic and anaerobic energy metabolism. College and professional teams often test aerobic fitness; however, there is a paucity of information regarding aerobic fitness of elite youth players. Without this knowledge, training of youth athletes to meet the standards of older age groups and higher levels of hockey may be random, inefficient, and or effective. Therefore, the purpose of this study was to determine the aerobic fitness of elite youth hockey players. A retrospective database review was performed for 200 male AAA hockey players between the ages of 13 and 17 (age, 14.4 ± 1.2 years; height, 174.3 ± 8.5 cm; body mass, 67.2 ± 11.5 kg; body fat, 9.8 ± 3.5%) before the 2012-13 season. All subjects performed a graded exercise test on a cycle ergometer, whereas expired air was collected by either a Parvo Medics TrueOne 2400 or a CareFusion Oxycon Mobile metabolic cart to determine maximal oxygen consumption (V[Combining Dot Above]O2max). Body mass, absolute V[Combining Dot Above]O2max, and the power output achieved during the last completed stage increased in successive age groups from age 13 to 15 years (p ≤ 0.05). Ventilatory threshold (VT) expressed as a percentage of V[Combining Dot Above]O2max and the heart rate (HR) at which VT occurred decreased between the ages of 13 and 14 years (p ≤ 0.05), whereas the V[Combining Dot Above]O2 at which VT occurred increased from the age of 14-15 years. There were no changes in relative V[Combining Dot Above]O2max or HRmax between any successive age groups. The aerobic fitness levels of elite youth ice hockey players increased as players age and mature physically and physiologically. However, aerobic fitness increased to a lesser extent at older ages. This information has the potential to influence off-season training and maximize the aerobic fitness of elite amateur hockey players, so that these players can meet standards set by advanced elite age groups.

Atrophy, inducible satellite cell activation, and possible denervation of supraspinatus muscle in injured human rotator-cuff muscle.

The high frequency of poor outcome and chronic pain after surgical repair of shoulder rotator-cuff injury (RCI) prompted this study to explore the potential to amplify muscle regeneration using nitric oxide (NO)-based treatment. After preoperative magnetic resonance imaging (MRI), biopsies of supraspinatus and ipsilateral deltoid (as a control) were collected during reparative surgery for RCI. Muscle fiber diameter, the pattern of neuromuscular junctions observed with alpha-bungarotoxin staining, and the γ:ε subunit ratio of acetylcholine receptors in Western blots were examined in tandem with experiments to determine the in vitro responsiveness of muscle satellite cells to activation (indicated by uptake of bromodeoxyuridine, BrdU) by the NO-donor drug, isosorbide dinitrate (ISDN). Consistent with MRI findings of supraspinatus atrophy (reduced occupation ratio and tangent sign), fiber diameter was lower in supraspinatus than in deltoid. ISDN induced a significant increase over baseline (up to 1.8-fold), in the proportion of BrdU+ (activated) Pax7+ satellite cells in supraspinatus, but not in deltoid, after 40 h in culture. The novel application of denervation indices revealed a trend for supraspinatus muscle to have a higher γ:ε subunit ratio than deltoid (P = 0.13); this ratio inversely with both occupancy ratio (P < 0.05) and the proportion of clusters at neuromuscular junctions (P = 0.05). Results implicate possible supraspinatus denervation in RCI and suggest NO-donor treatment has potential to promote growth in atrophic supraspinatus muscle after RCI and improve functional outcome.

Long-term follow-up of ACL reconstruction with hamstring autograft.

PURPOSE: To investigate the differences in the incidence and severity of knee osteoarthritis (OA), joint space narrowing, knee laxity, and knee flexion and extension strength between an anterior cruciate ligament (ACL)-reconstructed knee and the contralateral non-reconstructed limb. METHODS: Retrospective case series of patients from a single surgeon that had an ACL reconstruction with a semitendinosus/gracilis autograft more than 12 years ago. Outcome measures included radiographic analysis, International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC), KT-1000, Tegner Activity Level Scale, Lysholm Knee Score, ACL quality of life score (ACL-QOL) and knee flexor/extensor strength. RESULTS: Seventy-four patients consented and sixty-eight (43 male, 25 female) were included for analysis. Average age (SD) at the time of surgery was 31.2 (±9.1) years. At follow-up of 14.6 (1.9) years, 9% had re-ruptured their ACL, whereas 5% ruptured the contralateral ACL. Reconstructed knees had a greater incidence and severity of OA (P < 0.01). Medial meniscus surgery was a strong predictor of OA. Seventy-five per cent scored a normal or nearly normal knee on the IKDC. The mean Lysholm score was 75.8% and Tegner Activity Level Scale scores decreased (P < 0.001) from the time of surgery. Knee extension strength was greater in the contralateral knee at speeds of 60°/s (P = 0.014) and 150°/s (P = 0.012). CONCLUSIONS: Reconstructed knees have a greater incidence and severity of OA than non-reconstructed knees, which suggests degenerative changes are secondary to ACL rupture. Medial meniscus surgery is a strong predictor of OA. Despite this, 75% of patients reported good outcomes.

Accuracy and reliability of determining the isometric point of the knee for multiligament knee reconstruction.

PURPOSE: To compare the accuracy and reliability of the anatomic and radiographic techniques for identifying the isometric point of the knee. METHODS: Only four specimens were used; however, eight experienced multiligament knee injury surgeons were recruited to address this limitation. Surgeons estimated the isometric point (EIP) on the medial and lateral sides using an anatomic and radiographic method. The x and y coordinates of the EIP were compared to the true isometric point (TIP). T-tests and interclass correlation coefficients (ICC) were performed to determine the accuracy and reliability between the methods. RESULTS: There was no difference in placement of the EIP on the medial side of the knee in the anterior/posterior (x; p = n.s.) and superior/inferior direction (y; p = n.s). The EIP was anterior (p = 0.001) to the TIP with the radiographic method on the lateral side and approached significance (p = 0.05) in the superior/inferior direction. The ICC (95% CI) for identifying the EIP on the medial side in the anterior/posterior direction using the anatomic method was 0.64 (0.28-0.96) and 0.11 (-0.06 to 0.77) in the superior/inferior direction. Using the radiographic method, the ICC in the anterior/posterior and superior/inferior direction was 0.49 (0.14-0.94) and 0.15 (-0.47 to 0.81), respectively. On the lateral side, the ICC for the anatomic method was 0.84 (0.56-0.99) in the anterior/posterior direction and 0.36 (0.05-0.90) in the superior/inferior direction. Using the radiographic method, the ICC in the anterior/posterior and superior/inferior direction was 0.61 (0.26-0.96) and 0.89 (0.67-0.99), respectively. CONCLUSIONS: There was no difference in accuracy on the medial side of the knee. On the lateral side, the anatomic method was more accurate in the anterior/posterior direction. Reliability was greater in the anterior/posterior direction on both sides of the knee. Surgeons were most likely to place the isometric point anterior and superior to the TIP on both the medial and lateral sides of the knee with either method which has the potential to cause graft lengthening. This should be taken into consideration during reconstruction/repair of the MCL/PMC and LCL/PLC.

The internal validity of arthroscopic simulators and their effectiveness in arthroscopic education.

PURPOSE: The purpose of this systematic review was to identify standard procedures for the validation of arthroscopic simulators and determine whether simulators improve the surgical skills of users. METHODS: Arthroscopic simulator validation studies and randomized trials assessing the effectiveness of arthroscopic simulators in education were identified from online databases, as well as, grey literature and reference lists. Only validation studies and randomized trials were included for review. Study heterogeneity was calculated and where appropriate, study results were combined employing a random effects model. RESULTS: Four hundred and thirteen studies were reviewed. Thirteen studies met the inclusion criteria assessing the construct validity of simulators. A pooled analysis of internal validation studies determined that simulators could discriminate between novice and experts, but not between novice and intermediate trainees on time of completion of a simulated task. Only one study assessed the utility of a knee simulator in training arthroscopic skills directly and demonstrated that the skill level of simulator-trained residents was greater than non-simulator-trained residents. CONCLUSIONS: Excessive heterogeneity exists in the literature to determine the internal and transfer validity of arthroscopic simulators currently available. Evidence suggests that simulators can discriminate between novice and expert users, but discrimination between novice and intermediate trainees in surgical education should be paramount. International standards for the assessment of arthroscopic simulator validity should be developed to increase the use and effectiveness of simulators in orthopedic surgery.

Lower body positive pressure: an emerging technology in the battle against knee osteoarthritis?

BACKGROUND: Knee osteoarthritis (OA) is the most prevalent medical condition in individuals over the age of 65 years, and is a progressive joint degenerative condition with no known cure. Research suggests that there is a strong relationship between knee pain and loss of physical function. The resulting lifestyle modifications negatively impact not only disease onset and progression but also overall health, work productivity, and quality of life of the affected individual. PURPOSE: The goal of this investigation was to examine the feasibility of using an emerging technology called lower body positive pressure (LBPP) to simulate weight loss and reduce acute knee pain during treadmill walking exercise in overweight individuals with radiographically confirmed symptomatic knee OA. DESIGN: Prospective case series. METHODS: Twenty-two overweight individuals with knee OA completed two 20-minute treadmill walking sessions (one full weight bearing and one LBPP supported) at a speed of 3.1 mph, 0% incline. Acute knee pain was assessed using a visual analog scale, and the percentage of LBPP support required to minimize knee pain was evaluated every 5 minutes. Knee Osteoarthritis Outcome Scores were used to quantify knee pain and functional status between walking sessions. The order of testing was randomized, with sessions occurring a minimum of 1 week apart. RESULTS: A mean LBPP of 12.4% of body weight provided participants with significant pain relief during walking, and prevented exacerbation of acute knee pain over the duration of the 20-minute exercise session. Patients felt safe and confident walking with LBPP support on the treadmill, and demonstrated no change in Knee Osteoarthritis Outcome Scores over the duration of the investigation. CONCLUSION: Results suggest that LBPP technology can be used safely and effectively to simulate weight loss and reduce acute knee pain during weight-bearing exercise in an overweight knee OA patient population. These results could have important implications for the development of future treatment strategies used in the management of at-risk patients with progressive knee OA.

Validation of a global assessment of arthroscopic skills in a cadaveric knee model.

PURPOSE: The purpose of this study was to determine whether a global assessment of arthroscopic skills was valid for blinded assessment of cadaveric diagnostic knee arthroscopy. METHODS: A global skills assessment for arthroscopy was created using a published theory of the development of expertise. Faculty surgeons, fellows, and residents were consented and enrolled in this institutional review board-approved validation study. All participants were oriented to the equipment and procedures for diagnostic arthroscopy of the knee. After reviewing the anatomic structures to be visualized, participants were allowed 10 minutes to complete a diagnostic arthroscopy of the knee. The hands and arthroscopic view were recorded during this attempt. Resident participants completed a second filmed diagnostic arthroscopy 1 week after the initial attempt. Five blinded reviewers watched the synchronized videos and assessed arthroscopic skills with a procedure-specific checklist and the newly developed global skills assessment. The agreement between reviewers was determined by intraclass correlation coefficient. Internal consistency was determined with Cronbach's α. Test-retest reliability was measured by correlating repeated arthroscopies by residents. The ability of the global assessment to discriminate skill levels was determined with between-group Mann-Whitney U tests. RESULTS: The agreement between global assessment scores was strong (I.C.C. = 0.80, 95% C.I. 0.68-0.92). The internal consistency of evaluations was excellent (Cronbach's α = 0.97), and the test-retest reliability was strong (r = 0.52). The global assessment score was shown to be able to discriminate between skill levels by an analysis of variance indicating the difference in means among the various levels of training (P < .0001). CONCLUSIONS: The Objective Assessment of Arthroscopic Skills is a useful adjunct to arthroscopic educators and learners and could be used for in-training evaluations. CLINICAL RELEVANCE: The Objective Assessment of Arthroscopic Skills is an instrument that can be employed to measure the impact of skills curricula, including but not limited to simulation.

Intrinsic stresses on bone and cartilage in the normal and anterior cruciate ligament-reconstructed knee before and after a half marathon: a magnetic resonance imaging analysis.

OBJECTIVE: To investigate intrinsic changes of the anterior cruciate ligament-reconstructed and control (contralateral) knees after a half marathon. DESIGN: Prospective case series. SETTING: Sports Medicine Clinic. PARTICIPANTS: Eight runners were included in the analysis. INTERVENTIONS: Magnetic resonance imaging (MRI) of both knees within 48 hours before and after competition. Participants completed the Tegner Activity Level Scale and a Knee Demographic Questionnaire before the preevent MRI scan. MAIN OUTCOME MEASURES: The incidence of MRI-identified cartilage, ligament, bone, and meniscus pathology in the ACL-reconstructed and control knees. RESULTS: The control knees of 5 runners (63%) demonstrated cartilage lesions, but no change was evident on postevent MRI. Preevent MRI in ACL-reconstructed knees demonstrated Grade IV meniscal lesions (4 of 8), Grades II (2 of 8) and IV cartilage lesions (4 of 8), and Type I bony edema (4 of 8). Although not significant, ACL-reconstructed knees demonstrated a strong trend (P = 0.01) toward a greater incidence of bone marrow edema on postevent MRIs compared with control knees. CONCLUSIONS: This is the first study to compare the effects of running on intrinsic structures of a normal and ACL-reconstructed knee. Reconstructed knees demonstrated a greater incidence of bone marrow edema on postevent scans, but knee pathology evident on preevent scans did not progress in either control or ACL-reconstructed knees.