[Clinical multicenter investigation and analysis of the adverse events after primary anterior cruciate ligament reconstruction using the ligament advanced reinforcement system]

Objective: To investigate the postoperative adverse events after primary anterior cruciate ligament reconstruction (ACLR) using the ligament advanced reinforcement system (LARS) for establishing grounds to standardize the clinical use of artificial ligaments. Methods: The China Artificial Ligament Study Group (CALSG) was organized to follow up the cases of ACLR using the LARS(LARS-ACLR) at 20 orthopedic sports medicine centers in China between July 1, 2004 and December 31, 2010. Adverse events, including cumulative failures and complications, were identified through follow-up study and case screening. The cumulative failure was classified as graft rupture and clinical failure, with graft rupture confirmed by arthroscopy and clinical failure confirmed by either limited knee range of motion (>5° in extension and/or >15° in flexion, contralateral knee as control) or joint laxity (Lachman test ≥Ⅱ, pivot shift test ≥Ⅱ, side-to-side difference>5 mm). The demographic information and clinical data of cumulative failure cases were collected, and the cumulative failure rate, the complication rate, the composition ratio of different degrees of joint symptoms among cumulative failure cases, and the composition ratio of failure causes were statistically analyzed. Results: A total of 1 705 cases of LARS-ACLR were collected at 20 centers, of which 1 393 met the inclusion criteria of the study. Of the included cases, 1 146 completed the follow-up, with a follow-up rate of 83.3% (1 146/1 393) and a median follow-up time [M (Q₁, Q₃)] of 87.1 (68.2, 116.0) months. Ninety-eight adverse events were identified, including 51 cumulative failures and 47 complications, with a cumulative failure rate of 4.5% (51/1 146) and a complication rate of 4.1% (47/1 146). The median cumulative failure time [M (Q₁, Q₃)] was 12 (7, 24) months after surgery, with 44 patients (86.3%, 44/51) presenting with joint instability, 39 patients (76.5%, 39/51) with joint pain, 31 patients (60.8%, 31/51) with joint swelling, 25 patients (49.0%, 25/51) feeling knee catching and locking, 10 patients with flexion restriction greater than 15° (19.6%, 10/51), and 1 patients with extension restriction greater than 10° (2.0%, 1/51). The incorrect bone tunnel position were confirmed in 32 patients (62.7%, 32/51) and reinjury in 25 patients (49.0%, 25/51). The graft rupture was confirmed under arthroscopy in 21 patients (41.2%, 21/51) and screw loosening occurred in 8 patients(15.7%, 8/51). Complications were detected in 47 patients, with screw-related problems confirmed in 20 patients (1.7%, 20/1 146), synovitis in 18 patients (1.6%, 18/1 146), stiffness in 6 patients (0.5%, 6/1 146), and infection in 3 patients (0.3%, 3/1 146). Conclusions: The long-term cumulative failure rate is 4.5% and the complication rate is 4.1% after LARS-ACLR. Joint instability and pain are the main joint symptoms in cumulative failure cases of LARS-ACLR. Incorrect bone tunnel positioning is the primary cause of failure and should be of great concern to clinicians.

[Comparison of multislice spiral CT and MRI in diagnosis of occult fracture of knee joint with meniscus and ligament injury]

OBJECTIVE

To investigate the diagnostic value of multislice spiral CT (MSCT) and MRI in occult fracture of knee joint with meniscus and ligament injury.

METHODS

From January 2020 to March 2021, 63 patients with knee occult fracture with meniscus and ligament injury, including 41 males and 22 females, aged from 21 to 67 years old, with an average of (44.35±8.77) years old, the course of disease ranged from 1 to 6 days, with an average of (4.64±1.75) days, the body mass index (BMI) was (19.85±2.78) kg/m². MSCT and MRI data of 63 patients were collected and statistically analyzed to evaluage their diagnist value.

RESULTS

The detection of MRI for occult knee fravtures with meniscus and ligament injury, joint cavity effusion, bone marrow edema, and articular surface injury were 100.00% (63/63), 95.24% (60/63), 42.86% (27/63) and 36.51% (23/63), respectively. The detection rates of MSCT were 49.21% (31/63), 41.27% (26/63), 0.00% (0/63) and 1.59% (1/63), respectively, significantly lwver than that of MRI (P<0.05). The diagnostic sensitivity, specificity and accuracy of MRI were significantly higher than those of MSCT(P<0.05).

CONCLUSION

The sensitivity, specificity and accuracy of magnetic resonance imaging in the diagnosis of occult fracture of knee joint with meniscus and ligament injury are significantly better than that of MSCT. MRI has higher accuracy in the diagnosis of peripheral tissue diseases such as joint cavity, articular surface and bone marrow, and can reduce the risk of clinical misdiagnosis.

Effect of Sex and Maturation on Knee Extensor and Flexor Strength in Adolescent Athletes

BACKGROUND

Despite knee extensor and flexor strength reportedly being associated with injury risk, including rupture of the anterior cruciate ligament in girls, there is limited evidence for the longitudinal changes in lower extremity strength.

PURPOSE

To investigate the sex-specific relationship with longitudinal changes of knee extensor and flexor strength associated with maturation.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Adolescent boys and girls (N = 257; 208 adolsecent girls) participating in high school basketball, volleyball, and soccer were assessed longitudinally in at least 2 different pubertal stages. Pubertal status (prepubertal, pubertal, and postpubertal) was determined with the modified Pubertal Maturation Observation Scale questionnaire. After a warm-up of 5 submaximal repetitions, participants were tested for concentric peak isokinetic strength for knee extension and flexion at 300 deg/s over 10 repetitions and normalized to body weight. Linear mixed models were used to test for the effect of pubertal stage, sex, and their interaction.

RESULTS

Significant interactions were identified that indicated different maturational trajectories for knee muscle strength for adolescent boys and girls, particularly between prepubertal and pubertal stages, in which boys demonstrated greater mass normalized knee extensor increases than girls (right, +12% vs +5%; left, +13% vs +7%; P < .001). For knee flexors, boys demonstrated increased strength, while girls demonstrated decreased relative knee flexor strength (right, +4% vs -1%, P = .03; left, +3 vs -3%, P = .009).

CONCLUSION

The findings of this study support a differential effect of sex and maturation on important knee strength outcomes that may have implications for knee injury reduction, particularly in adolescent girls as they mature.

Evaluation of an injury prevention programme (Prep-to-Play) in women and girls playing Australian Football: design of a pragmatic, type III, hybrid implementation-effectiveness, stepped-wedge, cluster randomised controlled trial

INTRODUCTION

Due to the increase in participation and risk of anterior cruciate ligament (ACL) injuries and concussion in women's Australian Football, an injury prevention programme (Prep-to-Play) was codesigned with consumers (eg, coaches, players) and stakeholders (eg, the Australian Football League). The impact of supported and unsupported interventions on the use of Prep-to-Play (primary aim) and injury rates (secondary aim) will be evaluated in women and girls playing community Australian Football.

METHODS AND ANALYSIS

This stepped-wedge, cluster randomised controlled trial will include ≥140 teams from U16, U18 or senior women's competitions. All 10 geographically separated clusters (each containing ≥14 teams) will start in the control (unsupported) phase and be randomised to one of five dates (or 'wedges') during the 2021 or 2022 season to sequentially transition to the intervention (supported Prep-to-Play), until all teams receive the intervention. Prep-to-Play includes four elements: a neuromuscular training warm-up, contact-focussed football skills (eg, tackling), strength exercises and education (eg, technique cues). When transitioning to supported interventions, study physiotherapists will deliver a workshop to coaches and player leaders on how to use Prep-to-Play, attend team training at least two times and provide ongoing support. In the unsupported phase, team will continue usual routines and may freely access available Prep-to-Play resources online (eg, posters and videos about the four elements), but without additional face-to-face support. Outcomes will be evaluated throughout the 2021 and 2022 seasons (~14 weeks per season).

PRIMARY OUTCOME

use of Prep-to-Play will be reported via a team designate (weekly) and an independent observer (five visits over the two seasons) and defined as the team completing 75% of the programme, two-thirds (67%) of the time.

SECONDARY OUTCOMES

injuries will be reported by the team sports trainer and/or players. Injury definition: any injury occurring during a football match or training that results in: (1) being unable to return to the field of play for that match or (2) missing ≥ one match. Outcomes in the supported and unsupported phases will be compared using a generalised linear mixed model adjusting for clustering and time. Due to the type III hybrid implementation-effectiveness design, the study is powered to detect a improvement in use of Prep-to-Play and a reduction in ACL injuries.

ETHICS AND DISSEMINATION

La Trobe University Ethics Committee (HREC 20488) approved. Coaches provided informed consent to receive the supported intervention and players provided consent to be contacted if they sustained a head or knee injury. Results will be disseminated through partner organisations, peer-reviewed publications and scientific conferences.

TRIAL REGISTRATION NUMBER

NCT04856241.

Analysis of Functional Arch Support Insoles on the Biomechanics and Performance in Right-Forward Lunging Step of Badminton Players

The purpose of this study was to examine the differences in biomechanical parameters and sports-specific performance of lower limbs between arch support insoles (ASI) and flat insoles (FLI) when performing net strides. After installing the MVN IMU system, 18 college badminton team members were asked to take the following tests: (1) Consecutive net stride tests; (2) Six-point footwork tests; (3) Retrieve/stroke the ball at the left and right net; (4) Smash and retrieve/stroke the ball at the net; (5) Smash at the front and back crossover step. The joint angle of the lower limbs and ground reaction force during the support phase was collected. The results demonstrated that the peak right hip flexion angle was significantly greater with ASI than FLI (63.09 ± 10.70; 60.08 ± 13.82; p = 0.028), while the peak right foot inversion angle was significantly smaller with ASI than FLI (20.68 ± 7.87; 23.85 ± 8.11; p = 0.013). The principal conclusion was that the arch support insole avoids the decrease in the hip flexion angle and the increase in the foot inversion angle during the net stride tests.

A Review of Neuromuscular Training and Biomechanical Risk Factor Screening for ACL Injury Prevention Among Female Soccer Players

Anterior cruciate ligament (ACL) injuries are a highly prevalent and costly injury to treat, both financially and regarding its long-term detrimental effects on those injured. Adolescent female soccer players appear to be particularly vulnerable, possibly due to various biomechanical risk factors, such as knee valgus loading and imbalanced hamstrings-quadriceps (H/Q) ratio. Many studies support the benefits of generic neuromuscular training programs in mitigating this heightened injury risk. Despite this, ACL injuries remain pervasive within this population. This review aims to highlight the current tools available to assess athletes for biomechanical risk factors at an individual level, including three-dimensional motion analysis, the Landing Error Scoring System (LESS), and the Cutting Movement Assessment Score (CMAS). Utilization of these analyses could facilitate developing and implementing more individualized training programs, thereby identifying high-risk athletes, reducing sports-related ACL injuries, and lessening the economic burden of these injuries on both the patient and the health care system.

Preliminary Report on the Train the Brain Project, Part I: Sensorimotor Neural Correlates of Anterior Cruciate Ligament Injury Risk Biomechanics

CONTEXT

Anterior cruciate ligament injury commonly occurs via noncontact motor coordination errors that result in excessive multiplanar loading during athletic movements. Preventing motor coordination errors requires neural sensorimotor integration activity to support knee-joint neuromuscular control, but the underlying neural mechanisms driving injury-risk motor control are not well understood.

OBJECTIVE

To evaluate brain activity differences for knee sensorimotor control between athletes with high or low injury-risk mechanics.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Of 38 female high school soccer players screened, 10 were selected for analysis based on magnetic resonance imaging compliance, injury-risk classification via 3-dimensional biomechanics during a drop vertical jump, and matching criteria to complete neuroimaging during knee motor tasks.

MAIN OUTCOME MEASURE(S)

Peak knee-abduction moment during landing was used for group allocation into the high (≥21.74 newton meters [Nm], n = 9) or low (≤10.6 Nm, n = 11) injury-risk classification (n = 11 uncategorized, n = 7 who were not compliant with magnetic resonance imaging). Ten participants (5 high risk, 5 low risk) with adequate data were matched and compared across 2 neuroimaging paradigms: unilateral knee-joint control and unilateral multijoint leg press against resistance.

RESULTS

Athletes with high injury-risk biomechanics had less neural activity in 1 sensory-motor cluster for isolated knee-joint control (precuneus, peak Z score = 4.14, P ≤ .01, 788 voxels) and greater brain activity for the multijoint leg press in 2 cognitive-motor clusters: the frontal cortex (peak Z score = 4.71, P < .01, 1602 voxels) and posterior cingulate gyrus (peak Z score = 4.43, P < .01, 725 voxels) relative to the low injury-risk group.

CONCLUSIONS

The high injury-risk group's lower relative engagement of neural sensory resources controlling the knee joint may elevate demand on cognitive motor resources to control loaded multijoint action. The neural activity profile in the high injury-risk group may manifest as a breakdown in neuromuscular coordination, resulting in elevated knee-abduction moments during landing.

Reducing Knee Joint Load during a Golf Swing: The Effects of Ball Position Modification at Address

As the modern golf swing has changed, the incidence of knee pain in professional golfers is increasing. For those with previous knee injuries, developing a golf-swing modification that reduces knee loading may be necessary to recover performance after injury. The purpose of this study was to test whether ball position modification reduces knee joint load in a golf swing. Thirteen male professional golfers participated in the study. Golf swings were captured using a three-dimensional motion capture system and two force platforms, with conditions for self-selected ball position and eight additional ball positions. Knee internal rotation and adduction moments were calculated. The length of one golf ball (4.27 cm) backward ball position (closer to the golfer) significantly reduced the peak internal rotation moment of the lead knee (- 13.8%) (p &lt; 0.001) and the length of one golf ball (4.27 cm) away from the target ball position significantly reduced the peak adduction moment of the lead knee (- 11.5%) (p &lt; 0.001) compared with that of the self-selected ball position. Based on these observations, we conclude that the backward ball position modification might be suggested for golfers with anterior cruciate ligament injuries, and the away from the target modification might be suggested for golfers with medial compartment knee osteoarthritis.

Osteoporosis in Light of a New Mechanism Theory of Delayed Onset Muscle Soreness and Non-Contact Anterior Cruciate Ligament Injury

Osteoporosis is a disorder, with a largely unknown pathomechanism, that is often marked as a “silent thief”, because it usually only becomes undisguised when fractures occur. This implies that the pathological damage occurs earlier than the sensation of pain. The current authors put forward a non-contact injury model in which the chronic overloading of an earlier autologously microinjured Piezo2 ion channel of the spinal proprioceptor terminals could lead the way to re-injury and earlier aging in a dose-limiting and threshold-driven way. As a result, the aging process could eventually lead the way to the metabolic imbalance of primary osteoporosis in a quad-phasic non-contact injury pathway. Furthermore, it is emphasised that delayed onset muscle soreness, non-contact anterior cruciate injury and osteoporosis could have the same initiating proprioceptive non-contact Piezo2 channelopathy, at different locations, however, with different environmental risk factors and a different genetic predisposition, therefore producing different outcomes longitudinally. The current injury model does not intend to challenge any running pathogenic theories or findings, but rather to highlight a principal injury mechanism.

Can the Eight Hop Test Be Measured with Sensors? A Systematic Review

Rehabilitation aims to increase the independence and physical function after injury, surgery, or other trauma, so that patients can recover to their previous ability as much as possible. To be able to measure the degree of recovery and impact of the treatment, various functional performance tests are used. The Eight Hop Test is a hop exercise that is directly linked to the rehabilitation of people suffering from tendon and ligament injuries on the lower limb. This paper presents a systematic review on the use of sensors for measuring functional movements during the execution of the Eight Hop Test, focusing primarily on the use of sensors, related diseases, and different methods implemented. Firstly, an automated search was performed on the publication databases: PubMed, Springer, ACM, IEEE Xplore, MDPI, and Elsevier. Secondly, the publications related to the Eight-Hop Test and sensors were filtered according to several search criteria and 15 papers were finally selected to be analyzed in detail. Our analysis found that the Eight Hop Test measurements can be performed with motion, force, and imaging sensors.

Understanding the Relationship between Sport Courage and Female Soccer Performance Variables

The purpose of this study was to examine the relationships between female soccer players’ courage and key performance variables (level of participation, injury past, being selected or non-selected by a national team, being starter or substitute). Methods: The Sport Courage Scale-31, by Konter and Ng (2012) and key performance variables were collected from 210 female soccer players aged 12 to 27 (M = 17.97 ± 3.34 years old). Spearman correlations and Mann−Whitney U tests were used to analyse the collected data. Results: The correlations between mastery (r = 0.196), determination (p = 0.239), assertiveness (r = 0.325), sacrifice behaviour (r = 0.182), total sport courage (r = 0.265) and age of female soccer players were found to be significant (p < 0.05). Female soccer players who have sustained an injury in the past scored significantly higher on the venturesome scale (p = 0.006) than those who have not sustained an injury in the past. In comparison, female soccer players who have not sustained an injury in the past or who have not been substituted had significantly more mastery than female soccer players who have sustained an injury in the past or who have been substituted (p = 0.017, p = 0.002, respectively). Conclusions: This study indicates that sport courage is related to key performance variables among female soccer players. Mastery and age seem to be related to courageous behaviour, whereas increasing venturesomeness might cause injuries in female soccer. Some relevant implications for practitioners can be drawn from the present findings.

Reliability of a Qualitative Instrument to Assess High-Risk Mechanisms during a 90° Change of Direction in Female Football Players

Sidestep cuts between 60° and 180° and one-leg landings have been identified as the main mechanisms of ACL injuries in several sports. This study sought to determine intra- and inter-rater reliability of a qualitative tool to assess high-risk movements in a 90° change of direction when the test is applied in a real framework of sport practice. Female footballers from two teams (n = 38) participated in this study and were asked to perform 90° cutting trials to each side, which were simultaneously filmed from a frontal and a sagittal view. A total of 61 cases were selected for 2D qualitative observational analysis by three raters. Poor reliability was found among each pair of raters as well as moderate reliability when the Cutting Movement Assessment Score (CMAS) was given by the same rater at different moments, but with too high a minimum detectable change. On the other hand, raters presented a significant, as well as moderate-to-good intra-rater reliability for most items of the CMAS tool. There was, however, non-significant reliability between observers in rating most check-points of the tool. For these reasons, more objective guidelines and clearer definitions for each criterion within the CMAS, as well as a longer, standardised training period for novel observers, would be highly recommended to improve the reliability of this tool in an applied context with female footballers.

Bench to Bedside: A Multidisciplinary Approach toward the Unknowns after ACL Injuries to Drive Individual Success

ACL injury and surgery are increasing in prevalence. Several challenges exist that can be obstacles to an individual achieving success after ACL surgery. A knowledge of these risk factors alongside a multidisciplinary collaborative team approach can result in a greater likelihood of achieving individual success after ACL surgery.

A Meta-Analysis of Systemic Evaluation of Knee Ligament Injury or Intervention of Knee Proprioceptive Function Recovery

OBJECTIVE

The knee ligaments, as a passive knee joint stability device, provide protection for the knee joint and ensure its functional integrity. This role has long been known and recognized by people. The original purpose of knee ligament reconstruction after knee ligament injury is to restore its anatomical structure and mechanical stability mechanism.

METHODS

Taking athletes as the research object, randomized controlled trials (RCTs) on improving ankle joint function of athletes related to proprioception training at home and abroad were included. The search time was from the establishment of the database to December 31, 2019, and the references of related documents were traced. Two researchers independently screened the literature, extracted data, and evaluated the quality of the literature. RevMan 5.3 software was used for data analysis.

RESULTS

The extensor strength, flexor strength, and flexor strength/extensor strength of the affected limb were higher than before the operation one year after surgery (P < 0.01). The Lysholm score, Lysholm instability score, and one-foot jump distance were all higher than those before surgery (P < 0.05); the difference of KT-2000 for both knees was smaller than that before surgery (P < 0.05).

CONCLUSION

In maintaining the anterior stability of the knee joint, the knee ligament provides 85% static resistance to prevent the tibia from moving forward, so knee ligament injury will cause knee instability. The proprioceptive feedback mechanism plays an important role in maintaining the functional stability of joints.

Injectable recombinant block polymer gel for sustained delivery of therapeutic protein in post traumatic osteoarthritis

Protein-based biomaterials offer several advantages over synthetic materials, owing to their unique stimuli-responsive properties, biocompatibility and modular nature. Here, we demonstrate that E5C, a recombinant protein block polymer, consisting of five repeats of elastin like polypeptide (E) and a coiled-coil domain of cartilage oligomeric matrix protein (C), is capable of forming a porous networked gel at physiological temperature, making it an excellent candidate for injectable biomaterials. Combination of E5C with Atsttrin, a chondroprotective engineered derivative of anti-inflammatory growth factor progranulin, provides a unique biochemical and biomechanical environment to protect against post-traumatic osteoarthritis (PTOA) onset and progression. E5C gel was demonstrated to provide prolonged release of Atsttrin and inhibit chondrocyte catabolism while facilitating anabolic signaling in vitro. We also provide in vivo evidence that prophylactic and therapeutic application of Atsttrin-loaded E5C gels protected against PTOA onset and progression in a rabbit anterior cruciate ligament transection model. Collectively, we have developed a unique protein-based gel capable of minimally invasive, sustained delivery of prospective therapeutics, particularly the progranulin-derivative Atsttrin, for therapeutic application in OA.

Distal posterolateral corner injury in the setting of multiligament knee injury increases risk of common peroneal palsy

PURPOSE

The purpose of this study was to identify if the location of posterolateral corner (PLC) injury was predictive of clinical common peroneal nerve (CPN) palsy.

METHODS

A retrospective chart review was conducted of patients presenting to our institution with operative PLC injuries. Assessment of concomitant injuries and presence of neurologic injury was completed via chart review and magnetic resonance imaging (MRI) review. A fellowship-trained musculoskeletal radiologist reviewed the PLC injury and categorized it into distal, middle and proximal injuries with or without a biceps femoral avulsion. The CPN was evaluated for signs of displacement or neuritis.

RESULTS

Forty-seven operatively managed patients between 2014 and 2019 (mean age-at-injury 29.5 ± 10.7 years) were included in this study. Eleven (23.4%) total patients presented with a clinical CPN palsy. Distal PLC injuries were significantly associated with CPN palsy [9 (81.8%) patients, (P = 0.041)]. Nine of 11 (81.8%) patients with CPN palsy had biceps femoral avulsion (P = 0.041). Of the patients presenting with CPN palsy, only four (36.4%) patients experienced complete neurologic recovery. Three of 7 patients (43%) with an intact CPN had full resolution of their clinically complete CPN palsy at the time of follow-up (482 ± 357 days). All patients presenting with a CPN palsy also had a complete anterior cruciate ligament (ACL) rupture in addition to a PLC injury (P = 0.009), with or without a posterior cruciate ligament (PCL) injury. No patient presenting with an isolated pattern of PCL-PLC injury (those without ACL tears) had a clinical CPN palsy.

CONCLUSION

Distal PLC injuries have a strong association with clinical CPN palsy, with suboptimal resolution in the initial post-operative period. Specifically, the presence of a biceps femoris avulsion injury was highly associated with a clinical CPN palsy. Additionally, CPN palsy in the context of PLC injury has a strong association with concomitant ACL injury. Furthermore, the relative rates of involvement of the ACL vs. PCL suggest that specific injury mechanism may have an important role in CPN palsy.

LEVEL OF EVIDENCE

IV.

"When you're down, stay down": A lesson for all competitive alpine skiers supported by an ACL rupture measured in vivo

BACKGROUND

During an experiment, a ski racer equipped with various measurement devices suffered an anterior cruciate ligament (ACL) rupture in his right knee. The aim of this study was to describe the underlying injury mechanism from a functional perspective.

METHODS

Eight giant slalom turns (i.e., 4 left turns), followed by 1 left turn at which the ACL injury occurred, were recorded by 2 video cameras, electromyography of 4 relevant muscle groups, inertial measurement units to measure knee and hip angles, and pressure insoles to determine ground reaction forces.

RESULTS

Due to a loss of balance, the ski racer began to slide sideways at the apex of a left turn. During sliding, his right (outside) leg was actively abducted upward without touching the ground. The ski racer then attempted to stand up again by dropping his leg back towards the snow surface. The end of this dropping was accompanied by a decrease in electromyographic activity in the knee stabilizing muscles. Once the inside edge of the outer ski caught the snow surface, a rapidly increasing peak force, knee flexion, and an aggressive sudden activation of the vastus medialis muscle were observed, while biceps femoris and rectus femoris further decreased their activation levels. This likely resulted in excessive anterior translation of the tibia relative to the femur, causing damage to the ACL.

CONCLUSION

Our example emphasizes that ski racers should not get up until they stop sliding. Remember: "When you're down, stay down."

Reliability and Repeatability of ACL Quick Check®: A Methodology for on Field Lower Limb Joint Kinematics and Kinetics Assessment in Sport Applications

Anterior cruciate ligament (ACL) lesion represents one of the most dramatic sport injuries. Even though clinical screenings aiming at identifying subjects at risk of injuries are gaining popularity, the use of sophisticated equipment still represents a barrier towards their widespread use. This study aimed to test both reliability and repeatability of a new methodology to assess lower limb joints kinematics and kinetics directly on field with the aid of video cameras and plantar pressure insoles. Ten athletes and one case study (post ACL surgery) were assessed in a gait laboratory, while performing double leg squats, through the simultaneous acquisition of stereophotogrammetry, force plates, commercial video cameras and plantar pressure insoles. Different sources of errors were investigated and both reliability and repeatability analysis performed. Minimum and maximum RMSE values of 0.74% (right knee joint center trajectory) and 64.51%, respectively (ankle dorsi-plantarflexion moment), were detected. Excellent to good correlation was found for the majority of the measures, even though very poor and inverse between-trials correlation was found on a restricted number of trials especially for the ankle dorsi-plantarflexion moment. These findings could be used in combination with already available screening tools in order to provide more repeatable results.

Twelve Weeks of a Staged Balance and Strength Training Program Improves Muscle Strength, Proprioception, and Clinical Function in Patients with Isolated Posterior Cruciate Ligament Injuries

Ligament reconstruction is indicated in patients with an isolated posterior cruciate ligament (PCL) injury who fail conservative treatment. To eliminate the need for PCL reconstruction, an ideal rehabilitation program is important for patients with an isolated PCL injury. The purpose of this study was to investigate the improvement in functional outcome, proprioception, and muscle strength after a Both Sides Up (BOSU) ball was used in a balance combined with strength training program in patients with an isolated PCL injury. Ten patients with isolated PCL injuries were recruited to receive a 12 week training program as a study group. In the control group (post-PCL reconstruction group), ten subjects who had undergone isolated PCL reconstruction for more than 2 years were enrolled without current rehabilitation. The Lysholm score, IKDC score, proprioception (active and passive), and isokinetic muscle strength tests at 60°/s, 120°/s, and 240°/s, were used before and after training on the injured and normal knees in the study group, and in the post-PCL reconstruction group. The results were analyzed with a paired t-test to compare the change between pre-training, post-training, and the normal leg in the study group, and with an independent t-test for comparisons between the study and post-PCL reconstruction groups. Both the Lysholm and IKDC scores were significantly improved (p < 0.01) after training, and no difference was observed compared to the post-PCL reconstruction group. The active and passive proprioception was improved post-training compared to pre-training, with no difference to that in the post-PCL reconstruction group. Isokinetic knee quadriceps muscle strength was significantly greater post-training than pre-training in PCL injured knees at 60°/s, 120°/s, and 240°/s, and in hamstring muscle strength at 60°/s and 120°/s. Muscle strength in the post-training injured knee group showed no significant difference compared to that in the post-training normal leg and the post-PCL reconstruction group. The post-training improvement of muscle strength was higher in the PCL injured leg compared to the normal leg and there was no difference between the dominant and non-dominant injured leg in the study group. After 12 weeks of BOSU balance with strength training in patients with an isolated PCL injury, the functional outcome, proprioception, and isokinetic muscle strength were significantly improved, and comparable to the contralateral normal leg and the post-PCL reconstruction group. We suggest that programs combining BOSU balance and strength training should be introduced in patients with a PCL injury to promote positive clinical results.

Cannabinoid receptor type 2 is upregulated in synovium following joint injury and mediates anti-inflammatory effects in synovial fibroblasts and macrophages

OBJECTIVE

Joint injury-induced perturbations to the endocannabinoid system (ECS), a regulator of both inflammation and nociception, remain largely uncharacterized. We employed a mouse model of ACL rupture to assess alterations to nociception, inflammation, and the ECS while using in vitro models to determine whether CB2 agonism can mitigate inflammatory signaling in macrophages and fibroblast-like synoviocytes (FLS).

DESIGN

Mice underwent noninvasive ACL rupture (ACLR) via tibial compression-based loading. Nociception was measured longitudinally using mechanical allodynia and knee hyperalgesia testing. Synovitis was assessed using histological scoring and histomorphometry. Gene and protein markers of inflammation were characterized in whole joints and synovium. Immunohistochemistry assessed injury-induced alterations to CB1+, CB2+, and F4/80+ cells in synovium. To assess whether CB2 agonism can inhibit pro-inflammatory macrophage polarization, murine bone marrow-derived macrophages (mBMDM) were stimulated with IL-1β or conditioned medium from IL-1β-treated FLS and treated with vehicle (DMSO), the CB2 agonist HU308, or cannabidiol (CBD). Macrophage polarization was assessed as the ratio of M1-associated (IL1b, MMP1b, and IL6) to M2-associated (IL10, IL4, and CD206) gene expression. Human FLS (hFLS) isolated from synovial tissue of OA patients were treated with vehicle (DMSO) or HU308 following TNF-α or IL-1β stimulation to assess inhibition of catabolic/inflammatory gene expression.

RESULTS

ACLR induces synovitis, progressively-worsening PTOA severity, and an immediate and sustained increase in both mechanical allodynia and knee hyperalgesia, which persist beyond the resolution of molecular inflammation. Enrichment of CB2, but not CB1, was observed in ACLR synovium at 3d, 14d, and 28d, and CB2 was found to be associated with F4/80 (+) cells, which are increased in number in ACLR synovium at all time points. The CB2 agonist HU308 strongly inhibited mBMDM M1-type polarization following stimulation with either IL-1β or conditioned medium from IL-1β-treated mFLS, which was characterized by reductions in Il1b, Mmp1b, and Il6 and increases in Cd206 gene expression. Cannabidiol similarly inhibited IL-1β-induced mBMDM M1 polarization via a reduction in Il1b and an increase in Cd206 and Il4 gene expression. Lastly, in OA hFLS, HU308 treatment inhibited IL-1β-induced CCL2, MMP1, MMP3, and IL6 expression and further inhibited TNF-α-induced CCL2, MMP1, and GMCSF expression, demonstrating human OA-relevant anti-inflammatory effects by targeting CB2.

CONCLUSIONS

Joint injury perturbs the intra-articular ECS, characterized by an increase in synovial F4/80(+) cells, which express CB2, but not CB1. Targeting CB2 in murine macrophages and human FLS induced potent anti-inflammatory and anti-catabolic effects, which indicates that the CB2 receptor plays a key role in regulating inflammatory signaling in the two primary effector cells in the synovium. The intraarticular ECS is therefore a potential therapeutic target for blocking pathological inflammation in future disease-modifying PTOA treatments.

Self-Healing of Hyaluronic Acid to Improve In Vivo Retention and Function

Convergent advances in the field of soft matter, macromolecular chemistry, and engineering have led to the development of biomaterials that possess autonomous, adaptive, and self-healing characteristics similar to living systems. These rationally designed biomaterials can surpass the capabilities of their parent material. Herein, the modification of hyaluronic acid (HA) to exhibit self-healing properties is described, and its physical and biological function both in vitro and in vivo is studied. The in vitro findings showed that self-healing HA designed to undergo self-repair improves lubrication, enhances free radical scavenging, and attenuates enzymatic degradation compared to unmodified HA. Longitudinal imaging following intraarticular injection of self-healing HA shows improved in vivo retention despite its low molecular weight. Concomitant with these functions, intraarticular injection of self-healing HA mitigates anterior cruciate ligament injury-mediated cartilage degeneration in rodents. This proof-of-concept study shows how incorporation of functional properties such as self-healing can be used to surpass the existing capabilities of biolubricants.

Increasing Concentration of Sinovial: Effect on Cartilage Protection in a Rabbit ACLT Model

OBJECTIVE

This study aimed to test the hypothesis that administration of increasing doses of Sinovial (hyaluronic acid [HA]), would exhibit a dose-dependent effect on the prevention of cartilage degradation, without local and systemic toxicity.

METHODS

Twenty-seven adult rabbits were subjected to anterior cruciate ligament transection (ACLT). Two Sinovial products containing HA concentrations of 1.6% and 2.4% were used as active treatment, and 0.9% saline was used as control and injected intra-articularly 7 days post ACLT. Radiographs were taken prior to surgery, at injection and sacrifice times. After euthanasia, 8 weeks postsurgery, knee joints were observed macroscopically using India ink staining with OARSI (Osteoarthritis Research Society International) scoring and histologically using modified Mankin scoring. The synovial membranes were analyzed using Cake classification.

RESULTS

No intraoperative complications were observed. One week postinjection, 4 animals in the HA 2.4% group developed subcutaneous nodules that disappeared spontaneously. No inflammation of the synovial membrane was ever observed. The control group exhibited the maximum uptake of India ink 2.22 ± 0.14. HA groups exhibited a dose-dependent (P = 0.02) reduction in India ink uptake: 1.75 ± 0.17 for HA 1.6% and 1.58 ± 0.14 for HA 2.4%. The most marked dose-dependent effect of this study was a reduction of modified Mankin score for HA groups, with the 2.4% treatment achieving a statistically significant improvement as compared with the control group (7.19 ± 0.85 for saline, 4.65 ± 0.66 for HA 1.6%, and 3.53 ± 0.59 for HA 2.4%; P = 0.005).

CONCLUSIONS

A dose-dependent protective effect on cartilage was observed after injection of both HA solutions.

[Posterior meniscus root tears]

Meniscus root tears are radial tears in the region of the posterior insertion zones. Medial root injuries usually occur in individuals > 50 years of age without adequate trauma and are associated with obesity and varus deformities. The root lesion leads to a loss of ring tension, which results in extrusion of the meniscus and a strong increase in joint pressure that is biomechanically equivalent to a complete meniscectomy. When indicating arthroscopic transosseous refixation of the medial root lesion, factors such as accompanying cartilage damage, osteoarthritis, obesity and varus deformity must be taken into account. Injuries to the root of the lateral meniscus are mostly observed in younger patients in combination with a rupture of the anterior cruciate ligament. Arthroscopic transosseous refixation in combination with cruciate ligament surgery is therefore also recommended for type I and type II lesions. In summary, both the medial and the lateral root lesions of the menisci are injuries with high biomechanical relevance.

Leg-ligament-thigh-trunk Dynamic Model to Describe Posture Recovery after Double-leg Landing Task

One of the most common injuries in athletes is that of the Anterior Cruciate Ligament (ACL). This type of injury is commonly analyzed by observing the dynamics of the body in the sagittal plane. ACL injury can be indicated by a the small knee flexion angle and a small angular position of the trunk at start of leg-landing task. In this article a 4 Degrees of Freedom (DOF) dynamic model of the human body restricted to the sagittal plane is presented. The model represents the movement of the legs, an equivalent ligament between the tibia and femur, thighs and trunk. It is used to represent the recovery of vertical posture during a double leg landing task. Initial conditions in velocity are calculated as those resulting from a free fall from a height H. The results obtained from the simulation were satisfactory since the recovery of the vertical posture is achieved and it is possible to approximate the deformation suffered by the equivalent ligament. In conclusion, this model can be very useful in determining the behavior of the ligament and eventually, the possibility of injury after a double-leg landing task.