Double Fixation Technique for Acute Acromioclavicular Joint Dislocation Using the Two-Button Technique and Gracilis Autograft Reinforcement: A Case Report of an Elite Athlete Seeking a Rapid Return to Sports Activity.

Acromioclavicular joint dislocation is a relatively common injury in the general population, especially in younger ages. Although acromioclavicular injuries are a well-studied topic, there are many controversies concerning not only the best way to treat them by operative or conservative methods but also determining the most effective fixation methods, providing better functional outcomes, faster rehabilitation protocols, fewer complications, and lower recurrence rates. In this case report, we present a case of type III acromioclavicular dislocation in a young athlete who was treated operatively using a double fixation technique, aiming to address these controversies and offer insights into the optimal management of such injuries.

Single bundle hamstrings autograft preparation techniques for anterior cruciate ligament reconstruction: current concepts.

Anterior cruciate ligament reconstruction (ACLR) is one of the most common orthopedic procedures, and huge variation exists in the surgical technique. Single bundle hamstrings autograft reconstruction is a common method and has good clinical outcomes. A criticism of the hamstrings autograft is a small graft diameter, often less than 8-mm, which has been associated with increased re-rupture rates. Several graft preparation techniques for single bundle hamstrings autograft exist. Perioperative decisions include the number of tendons utilized, number of graft strands, graft configuration, and femoral and tibial fixation methods. Awareness of the minimum tendon and graft length required to produce each graft variation is necessary to avoid common pitfalls. However, intraoperative graft modification is possible to maximize graft diameter, and obtain proper fixation. The objective of this current concepts review is to describe the indications, surgical anatomy, technique, intraoperative tips, clinical outcomes, and complications for single bundle hamstrings autograft preparation techniques in ACLR.

Acute effects of Nordic hamstring exercise on hip and knee joints proprioception.

BACKGROUND AND OBJECTIVES: Nordic Hamstring Exercise (NHE) is one of the best exercises proposed for injury prevention of hamstring muscles. However, its effects on lower extremity proprioception are unclear. The aim of this study was to investigate the immediate effects of a single bout of NHE on hip and knee joints' proprioception. METHODS: Forty collegiate male soccer players participated in this study with a mean age of 22.85 ± 1.82 years and were randomized into either control (n = 20) or experimental (n = 20) groups. Each subject participated in pre-test measurements in which hip and knee active joints position sense (JPS) were assessed in standing and lying tasks using the image-capturing method. The experimental group then performed three sets of NHE with 10 repetitions in each set, while the control group rested for 10 min. Paired and independent t-tests were used for calculating the differences within and between groups on SPSS software, respectively. The level of significance was P ≤ 0.05. RESULTS: Hip JPS in the lying task and knee JPS in both of the standing and lying tasks were impaired significantly after performing a single bout of NHE (P ≤ 0.05). However, the effects of this exercise on hip JPS in the standing task were not significant (P ≥ 0.05). CONCLUSIONS: NHE performing with three sets of 10 repetitions can significantly impair hip and knee JPS immediately after exercise and reduce the proprioception acuity of the lower limbs. It is recommended to perform this exercise at a time rather than before training or match sessions.

Semitendinosus and biceps femoris long head activity during the single leg bridge test in healthy individuals.

INTRODUCTION: The single leg bridge test (SLBT) has been suggested as a clinical test to examine function, screen injury risk, and monitor the effectiveness of rehabilitation programes targeting the hamstring. This study aimed to determine the inter-day reliability and repeatability of both SLBT performance, semitendinosus (ST), and biceps femoris long head (BFlh) surface electromyography (sEMG) responses and characterise the BFlh and ST electrical activity during the SLBT performed until exhaustion in healthy individuals. METHODS: Twelve physically active young men without previous hamstring injury were tested for the number of repetitions attained, and sEMG signal median frequency and amplitude in both ST and BFlh of each lower limb, randomly in two sessions, with a seven-day interval between sessions. RESULTS: High reliability [ICC = 0.85] was found for the number of SLBT repetitions attained. Reliability of sEMG outcomes showed better results for ST (ICC = 0.62-0.91) than for BFlh (ICC = 0.39-0.81), and a high to very-high repeatability was found for both ST (ICC = 0.91-0.84) and BFlh (ICC = 0.91-0.85). sEMG median frequency decreased and amplitude increased for both BFlh (p ≤ 0.001) and ST (p ≤ 0.039) at the end of SLBT, suggesting localised fatigue. CONCLUSIONS: The SLBT performed by healthy individuals until exhaustion proved to be reliable and to induce fatigue in both BFlh and ST, where the sEMG median frequency and amplitude can be measured on different days with acceptable reliability and high repeatability, suggesting its potential future use in both practical and clinical settings.

Epidemiology of Non-Contact Muscle Injuries in the Italian Male Elite Under-19 Football (Soccer) Championship.

BACKGROUND: While extensive research exists on muscle injuries among adult football players, a notable gap persists in studies concerning younger footballers. The aim of the current study is to provide epidemiological data on the characteristics of time-loss muscle injuries in young football players participating in the Italian Under-19 male elite Championship ("Primavera 1"). RESULTS: Conducted as a multicentre, prospective, observational cohort study, this research gathered injury data from the 2022-23 season across 14 of the 18 Clubs in the first Italian Under-19 championship. The cohort comprised 391 players with a mean age (± standard deviation) of 18.0 ± 0.4 years. A total of 479 injuries were reported, resulting in 14,231 days of activity lost. Of these, muscle injuries were 209 (44%), accounting for 4,519 (32%) days lost. Overall muscle injuries incidence was 1.82/1000 hours, with a mean injury burden of 39.4 days lost/1000 hours. Almost all muscle injuries (206 out of 209: 98.5%) occurred in hamstrings, quadriceps, adductors, calf and iliopsoas. Hamstrings injuries were the most burdensome (18.8 days lost/1000 hours) accounting for nearly half of all days lost due to muscle injuries. Incidence and burden of adductors injuries (0.25 injuries and 4.1 days lost/1000 hours, respectively) were found to be comparable to calf injuries (0.24 injuries and 4.7 days lost/1000 hours, respectively). Iliopsoas injuries accounted for a noteworthy portion of the total, with an injury incidence of 0.16/1000 hours and a burden of 3.3 days lost/1000 hours. Injuries with myo-tendinous or myo-aponeurotic involvement demonstrated delayed return-to-football compared to those without such involvement (35.6 vs. 18.5 days, p < 0.0001). CONCLUSIONS: The study highlighted a peculiar distribution of non-contact muscle injuries among elite young football players. While hamstring injuries were confirmed as the most burdensome, incidence and burden of adductors and calf injuries were found to be similar. A significant incidence and burden of iliopsoas injuries were observed. These findings suggest potential implementations for targeted injury prevention strategies in the Italian male elite Under-19 football Championship.

A comparative video analysis of hamstring injuries mechanism and situational pattern in men's and women's football (soccer).

PURPOSE: To describe the injury mechanism and situational patterns of severe (absence >28 days) hamstring muscle injuries in professional male and female football (soccer) players. METHODS: The data for males were sourced from Serie A clubs participating in both national and international competitions from 2018 to 2021. For the female cohort, hamstring injuries were identified during matches of the top national/international competitions from 2017 to 2023. Video footage was obtained, and three raters categorised injury mechanisms and situational patterns. Injuries were also examined according to the month, minute and location. RESULTS: A total of 129 severe hamstring injuries were identified, with 64 occurring in females and 65 in males. Video analysis was possible for 29 (45%) female cases and 61 (94%) male cases. Female injuries had longer lay-off times (97.8 ± 77.1 days) than males (39.6 ± 20.9 days). Females had a higher proportion of indirect contact injuries (34%) than males (13%) and a lower proportion of non-contact injuries (66% vs. 87%). Four situational patterns were identified: running was the most common for both sexes, representing 59% of female injuries and 41% of male injuries. Over-stretching injuries were split across open and CKC scenarios but collectively explained nearly half (48%) of male injuries but only one in five (21%) female injuries. Kicking injuries had a higher proportion in females (17%) than males (10%). Injuries were more common in the second half for females and the first half for males. CONCLUSION: Females had a higher proportion of indirect contact, running and kicking injuries and a lower proportion of non-contact and stretch-type injuries than males. Understanding injury patterns can inform tailored prevention programs, considering sex-specific differences. LEVEL OF EVIDENCE: Level IV.

Operative Repair of Hamstring Injuries From the Jackling Position in Rugby.

Background: The jackling position within rugby has not been previously described as a mechanism for proximal hamstring injuries. Hypothesis: Acute surgical repair of proximal hamstring avulsion injuries sustained from the jackling contact position enables a return to a previous level of sporting activity with low risk of recurrence. Study Design: Case series; Level of evidence, 4. Methods: This study included 54 professional rugby players (mean age, 26 ± 4.8 years) who underwent acute primary surgical repair of complete, proximal hamstring avulsion injuries. The mean follow-up time was 17 months (range, 12-24 months). Mean isometric hamstring strength and function testing was performed at 3 months and 1 year after repair. Results: Of the 54 players, 51 (94.4%) returned to their preinjury level of sporting activity. The mean time from surgical repair to full sporting activity was 7 months (range, 4-12 months). No patients had recurrence of the primary injury. At 1 year postoperatively, patients had significantly restored mean isometric hamstring muscle strength when compared with the uninjured leg at 0° (98.4% ± 2.8%), 15° (95.9% ± 2.9%), and 45° (92.9% ± 4.1%); improved Lower Extremity Functional Score (78.0 ± 2.0); and improved Marx activity rating score (14.3 ± 1.5) (P < .001 for all). Conclusion: Acute surgical repair of proximal hamstring avulsion injuries caused by the contact jackling position produced a high return to preinjury level of sporting activity, increased muscle strength, and improved functional outcome scores, with a low risk of recurrence at short-term follow-up.

Reciprocal inhibition of the thigh muscles in humans: A study using transcutaneous spinal cord stimulation.

Evaluating reciprocal inhibition of the thigh muscles is important to investigate the neural circuits of locomotor behaviors. However, measurements of reciprocal inhibition of thigh muscles using spinal reflex, such as H-reflex, have never been systematically established owing to methodological limitations. The present study aimed to clarify the existence of reciprocal inhibition in the thigh muscles using transcutaneous spinal cord stimulation (tSCS). Twenty able-bodied male individuals were enrolled. We evoked spinal reflex from the biceps femoris muscle (BF) by tSCS on the lumber posterior root. We examined whether the tSCS-evoked BF reflex was reciprocally inhibited by the following conditionings: (1) single-pulse electrical stimulation on the femoral nerve innervating the rectus femoris muscle (RF) at various inter-stimulus intervals in the resting condition; (2) voluntary contraction of the RF; and (3) vibration stimulus on the RF. The BF reflex was significantly inhibited when the conditioning electrical stimulation was delivered at 10 and 20 ms prior to tSCS, during voluntary contraction of the RF, and during vibration on the RF. These data suggested a piece of evidence of the existence of reciprocal inhibition from the RF to the BF muscle in humans and highlighted the utility of methods for evaluating reciprocal inhibition of the thigh muscles using tSCS.

Comparison of Cross-Pin Versus Cortical Button Femoral Fixation in Anterior Cruciate Ligament Reconstruction With Hamstrings Autograft: A Long-Term Clinical Study and Review of the Literature.

Background Anterior cruciate ligament reconstruction (ACLR) is a common operative procedure and many options regarding the type of the selected graft and fixation technique have been described to date. Although many studies have addressed the issue of the optimal femoral fixation device during ACLR with a hamstring tendon (HT) autograft, no clear evidence to indicate one technique over another has been found. Objective The purpose of this study was to compare the long-term postoperative outcomes and complication rates between transfemoral Cross-pin (CP) and Endobutton-Cortical Button (CB) fixation techniques in patients undergoing ACLR with an HT autograft. Methods One hundred and seven consecutive patients underwent ACLR by using a quadruple HT autograft that was stabilized with either a CP (CP Group: 52 patients) or a CB (CB Group: 55 patients) fixation technique. The Lachman test (LT), the Pivot-shift test (PST), the side-to-side difference in anterior translation of the tibia, the International Knee Documentation Committee (IKDC), and the Lysholm knee scoring systems were evaluated before surgery and during long-term follow up. The femoral and tibial tunnel diameter was measured in the anteroposterior (AP) and lateral radiographs after surgery and at the final follow-up. A review of the literature was also carried out to identify any differences between both techniques. Results Study groups were comparable in terms of patient demographics. The mean follow-up was 10.4 ± 1.3 and 10.6 ± 1.3 years in the CP and CB Groups, respectively (p = 0.47). In the CP Group, improvements after surgery in LT and PST from grade 2 (n=34) or 3 (n=18) to grade 0 (n = 41) or 1 (n = 11) and from grade 2 (n=36) or 3 (n = 16) to grade 0 (n = 44) or 1 (n = 8), respectively, were observed. In the CB Group, similar improvements in LT and PST scores from grade 2 (n = 40) or 3 (n = 15) to grade 0 (n = 46) or 1 (n = 9) and from grade 2 (n = 41) or 3 (n = 14) to grade 0 (n = 47) or 1 (n = 8), respectively, were observed. However, no differences between the groups (p = 0.53 for LT and p = 0.90 for PST) were noted. The mean Lysholm scores were 89.7 ± 6.8 and 90.2 ± 7.2 in the CP and CB groups, respectively (p = 0.59). Side-to-side difference improved from 9.1 ± 2.8 to 1.7 ± 1.5 mm and from 8.6 ± 2.5 to 1.6 ± 1.4 mm in the CP and CB groups, respectively (p = 0.89 between groups). According to IKDC grades, 92.1% and 91.4% of knees in the CP and CB groups, respectively were reported to be Grade A (Normal) or B (Nearly Normal) with a p = 0.7. Femoral and tibial tunnel widening was found in the last follow-up in both groups. However, there was no difference in the degree of tunnel widening among the two techniques. With respect to LT, PST, anterior drawer test, and IKDC score, none of the 15 published comparative studies demonstrated any significant differences between the two techniques and only one study detected a difference regarding the Lysholm score in favor of CP fixation. Conclusion In the long term, both CB and CP femoral stabilization techniques were shown to be associated with similar functional outcomes and low complication rates. Further large multicenter random clinical trials are still required to identify the most effective method of femoral fixation for HT autograft during ACLR surgery.

S1 Radiculopathy Initially Presenting With Sole Knee Flexion Weakness: A Case Report.

Lumbar disc herniation can lead to low back pain and/or sciatica, as well as manifest with neurological symptoms in specific dermatomal/myotomal patterns due to nerve root irritation. S1 radiculopathy is the result of L5-S1 disc herniation and is usually presented with foot plantar flexion/eversion weakness and hypoesthesia in the lateral aspect of the foot. We present a case of S1 radiculopathy that initially presented with hamstring weakness and posterior knee pain as the only manifestations, leading to a delay in the initial diagnosis and treatment. To the best of our knowledge, no previous studies have reported this atypical presentation that resulted from S1 radiculopathy. This case report is of great clinical value, as it will help diagnosticians broaden the diagnostic range in patients with similar symptomatology and avoid diagnostical pitfalls.

Age-related effects of neuromuscular fatigue and acute recovery responses on maximal and rapid torque measures of the leg extensors and flexors.

PURPOSE: To examine the effects of neuromuscular fatigue and recovery on maximal and rapid torque characteristics in young and old men for the leg extensors and flexors. METHODS: Twenty-one young (age = 24.8 years) and 19 old (72.1 years) men performed maximal voluntary contractions (MVCs) before and at 0, 7, 15, and 30 min following an intermittent submaximal fatigue task. Outcome measures included endurance time, maximal (peak torque; PT) and rapid (absolute and normalized rate of torque development; RTD and nRTD) torque characteristics. RESULTS: The old men had greater endurance times than the young men. Differential recovery patterns were observed for PT, and early and late RTD phases between the leg extensor and flexor muscle groups such that the early rapid torque variables and the flexors demonstrated slower recovery compared to later rapid torque variables and the extensors. The normalized RTD variables were reduced less after the fatigue task and differential muscle and age effects were observed where the flexors were reduced more at the early phase (nRTD1/6) compared to the extensors, however, for the later phase (nRTD2/3) the young men exhibited a greater reduction compared to the old men. CONCLUSIONS: Dissimilar fatigue recovery patterns across different phases of RTD, lower limb muscles, and age groups may have important fatigue-related performance and injury risk implications across the adult lifespan.

Force Production and Electromyographic Activity during Different Flywheel Deadlift Exercises.

This study aimed to characterize and compare force production and muscle activity during four flywheel deadlift exercises (bilateral [Bi] vs. unilateral [Uni]) with different loading conditions (vertical [Ver] vs. horizontal [Hor]). Twenty-three team-sport athletes underwent assessments for exercise kinetics (hand-grip force), along with surface electromyography (sEMG) of the proximal (BFProx) and medial biceps femoris (BFMed), semitendinosus (ST), and gluteus medius (GM). Mean and peak force were highest (p < 0.001) in Bi + Ver compared with Bi + Hor, Uni + Ver, and Uni + Hor. Although no significant differences were observed between Bi + Hor and Uni + Ver, both variants showed higher (p < 0.001) average force and peak eccentric force when compared with Uni + Hor. The presence of eccentric overload was only observed in the vertically loaded variants. Bi + Ver and Uni + Ver showed higher (p < 0.05) sEMG levels in BFProx and BFMed compared with the Uni + Hor variant. In addition, Uni + Ver registered the largest GM and ST sEMG values. In conclusion, the vertical variants of the flywheel deadlift exercise led to higher muscle force production and sEMG compared with their horizontal counterparts. Both Bi + Ver and Uni + Ver may be effective in promoting an increase in hamstring muscles activity and muscle force at long muscle length, while the Uni + Ver variant may be more effective in promoting GM and ST involvement.

Innervation patterns of hamstring muscles, including morphological descriptions and clinical implication.

PURPOSE: The hamstrings muscles are innervated by sciatic nerve branches. However, previous studies assessing which and how many branches innervate each muscle have yielded discrepant results. This study investigated the innervation patterns of hamstrings. MATERIALS AND METHODS: Thirty-five cadaver limbs were investigated. The average age of subjects was 78.6 ± 17.2 years, with 48.6% male and 51.4% female, while 57.1% were right limbs and 42.9% left. The sciatic nerve, hamstrings and associated structures were dissected. The number of nerve branches for each muscle and the level where they penetrated the muscle were recorded. RESULTS: The sciatic nerve was connected by a fibrous band to the long head of the biceps femoris. This muscle was innervated by either one or two branches, which penetrated the muscle into its superior or middle third. The short head of the biceps femoris was innervated by a single nerve that usually penetrated its middle third, but sometimes inferiorly or, less commonly, superiorly. The semitendinosus was always innervated by two branches, the superior branch penetrating its upper third, the inferior mostly the middle third. The semimembranosus usually was innervated by a single nerve branch that penetrated the muscle at its middle or lower third. Four specimens revealed common nerves that innervated than one muscle. CONCLUSIONS: We have characterized hamstring innervation patterns, knowledge that is relevant to neurolysis, surgery of the thigh, and other procedures. Moreover, a mechanical connection between the sciatic nerve and biceps femoris long head was identified that could explain certain neuralgias.

Distal hamstrings tendons mechanical properties at rest and contraction using free-hand 3-D ultrasonography.

Tendon properties impact human locomotion, influencing sports performance, and injury prevention. Hamstrings play a crucial role in sprinting, particularly the biceps femoris long head (BFlh), which is prone to frequent injuries. It remains uncertain if BFlh exhibits distinct mechanical properties compared to other hamstring muscles. This study utilized free-hand three-dimensional ultrasound to assess morphological and mechanical properties of distal hamstrings tendons in 15 men. Scans were taken in prone position, with hip and knee extended, at rest and during 20%, 40%, 60%, and 80% of maximal voluntary isometric contraction of the knee flexors. Tendon length, volume, cross-sectional area (CSA), and anteroposterior (AP) and mediolateral (ML) widths were quantified at three locations. Longitudinal and transverse deformations, stiffness, strain, and stress were estimated. The ST had the greatest tendon strain and the lowest stiffness as well as the highest CSA and AP and ML width strain compared to other tendons. Biceps femoris short head (BFsh) exhibited the least strain, AP and ML deformation. Further, BFlh displayed the highest stiffness and stress, and BFsh had the lowest stress. Additionally, deformation varied by region, with the proximal site showing generally the lowest CSA strain. Distal tendon mechanical properties differed among the hamstring muscles during isometric knee flexions. In contrast to other bi-articular hamstrings, the BFlh high stiffness and stress may result in greater energy absorption by its muscle fascicles, rather than the distal tendon, during late swing in sprinting. This could partly account for the increased incidence of hamstring injuries in this muscle.

Does Pelvic Tilt Angle Influence the Isokinetic Strength of the Hip and Knee Flexors and Extensors?

The purpose of this study was to examine the effect of pelvic tilt angle on maximum hip and knee muscles' strength and antagonist/agonist strength ratios. Twenty-one young males and females performed maximum isokinetic concentric knee extension-flexion and hip extension-flexion efforts at 60°·s-1, 120°·s-1, and 180°·s-1 from three positions: anterior, neutral, and posterior pelvic tilt. Peak torques and knee flexor-to-extensor and hip flexor-to-extensor torque ratios were analyzed. An analysis of variance showed that peak hip extensor torque was significantly greater in the anterior pelvic tilt condition compared to either neutral or posterior pelvic tilt angles (p > 0.05). No effects of changing pelvic tilt angle on hip flexor, knee flexor, or knee extension values were found (p > 0.05). The hip flexor-to-extensor torque ratio decreased (p < 0.05) in the anterior pelvic tilt position relative to the other positions, while no difference in the knee flexor-to-extensor ratio between pelvic positions was observed (p > 0.05). This study shows that an increased anterior pelvic tilt affects the maximum isokinetic strength of the hip extensors, supporting previous suggestions regarding the link between pelvic position and hip and knee muscle function. Isokinetic testing from an anterior pelvic tilt position may alter the evaluation of hip flexion/extension strength.

Is muscle stiffness a determinant for range of motion in the leg muscles?

Previous training studies with comprehensive stretching durations have reported that an increase in range of motion (ROM) can be related to decreases in muscle stiffness. Therefore, the purpose of this study was to analyze the association between the passive muscle stiffness of three muscle groups (triceps surae, quadriceps, hamstrings) to the respective joint ROM. Thirty-six healthy male soccer players volunteered in this study. After a standardized warm-up, the muscle stiffness was tested via shear wave elastography in six muscles (gastrocnemius medialis and lateralis, rectus femoris, semitendinosus, semimembranosus, and biceps femoris long head). The hip extension, hip flexion, and ankle dorsiflexion ROM were also assessed with a modified Thomas test, a sit and reach test, and a standing wall push test, respectively. We found significant moderate to large correlations between hip flexion ROM and muscle stiffness for the semimembranosus (rP = -0.43; P = 0.01), biceps femoris long head (rP = -0.45; P = 0.01), and overall hamstring stiffness (rP = -0.50; P < 0.01). No significant correlations were found for triceps surae (rP = -0.12; P = 0.51 to 0.67) and rectus femoris muscle stiffness (rP = 0.25; P = 0.14) with ankle dorsiflexion and hip extension ROM, respectively. We conclude that muscle stiffness is an important contributor to hip flexion ROM, but less important for hip extension or ankle joint ROM. Additional contributors to ROM might be tendon stiffness or stretch/pain tolerance.

Individuals With Chronic Ankle Instability Show Abnormalities in Maximal and Submaximal Isometric Strength of the Knee Extensor and Flexor Muscles.

BACKGROUND: It has been shown that chronic ankle instability (CAI) leads to abnormalities in neuromuscular control of more proximal joints than the ankle. Although strength of the hip and the ankle muscles has been largely investigated providing concordant results, limited evidence with contrasting results has been reported regarding knee extensor and flexor muscles. PURPOSE: To investigate maximal and submaximal isometric muscle strength in individuals with CAI. STUDY DESIGN: Controlled laboratory study. METHODS: Fifteen participants with unilateral CAI and 15 healthy matched controls were recruited. To quantify maximal strength, peak forces were recorded during a maximal isometric voluntary contraction of knee extensor and flexor muscles at 30° and 90° of knee flexion and normalized by the body weight of each participant. At both angles, submaximal isometric contractions at 20%, 50%, and 80% of the maximal voluntary isometric contraction were performed to analyze strength steadiness, in terms of coefficient of variation, and strength accuracy, in terms of absolute error. During all the assessments, knee extensor and flexor muscle activation was recorded by means of surface electromyography. RESULTS: Knee flexor maximal isometric strength was significantly lower in the injured limb of individuals with CAI in comparison with healthy controls at both 30° (0.15 ± 0.05 vs 0.20 ± 0.05; P < .05) and 90° (0.14 ± 0.04 vs 0.18 ± 0.05; P < .05). Knee extensor and flexor steadiness was significantly lower (higher coefficient of variation) in both the injured and the noninjured limbs of individuals with CAI in comparison with healthy individuals at 90° and at 30° for knee flexor steadiness of the injured limb. Knee extensor and flexor accuracy was lower (higher absolute error) in both the injured and noninjured limbs of individuals with CAI in comparison with healthy individuals, mainly at 30°, while at 90° it was lower only in the injured limb. No differences between the 2 groups were found for maximal isometric strength of knee extensor muscles, as well as for muscle activations. CONCLUSION: Individuals with CAI show abnormalities in maximal and submaximal isometric strength of knee flexor muscles, and submaximal strength of the knee extensor muscles. Further studies should deeply investigate mechanisms leading to these abnormalities. CLINICAL RELEVANCE: Rehabilitation interventions should consider abnormalities of neuromuscular control affecting joints more proximal than the ankle in individuals with CAI. REGISTRATION: NCT05273177 (ClinicalTrials.gov identifier).

Investigating balance-related gait patterns and their relationship with maximum torques generated by the hamstrings and quadriceps in older adults - Results from the Baltimore longitudinal study of aging.

BACKGROUND: Balance-related gait patterns in older adults can be objectively discerned through the examination of gait parameters, maximum leg torques, and their interconnections. OBJECTIVE: To investigate the correlation between leg muscle strength and balance during gait concerning functional performance in healthy older adults. METHODS: Participants included 117 adults aged 60-95 years were recruited from the Baltimore Longitudinal Study of Aging (BLSA). They underwent evaluations of gait, balance, and maximum isometric leg torque (for both hamstrings and quadriceps). Analyses examined the association between leg torque and functional performance among those with higher and lower balances. RESULTS: Individuals with lower balance (n = 43) were older, more prone to experiencing a fear of falling, and exhibited lower functional performance (gait speeds and Generalized Gait Stability Scores (GGSS), ps < 0.001) compared to their counterparts with higher balance (n = 74). At a usual walking pace, the GGSS showed a positive association with concentric Quadriceps Maximum Torque (QMT) in participants with lower balance (p = 0.013). Conversely, it displayed a positive association with eccentric QMT in those with higher balance (p = 0.014). At a fast walking pace, only individuals with higher balance demonstrated a positive muscle torque association with both gait speed and GGSS, encompassing concentric and eccentric actions in both the quadriceps and hamstrings (ps < 0.050). CONCLUSION: Evaluating muscle strength capacity in both concentric and eccentric phases during dynamic high-effort events, along with investigating their associations with gait performance, can be beneficial for identifying subtle gait deficits. This comprehensive approach may assist in the early detection of gait deterioration among healthy older adults, given the intricate muscle activations involved in lower body functional performance.

Number of intra-operative cyclic knee motion required to achieve stable graft tension in anterior cruciate ligament reconstruction; a prospective clinical study.

BACKGROUND: Applying pretension by cyclic knee motion immediately before graft fixation in anterior cruciate ligament (ACL) reconstruction surgery decreases graft elongation during the postoperative course. However, the expected change in graft tension caused by cyclic knee motion remains unclear. We measured graft tension changes caused by cyclic knee motion during double-bundle ACL reconstruction. METHODS: We included 39 patients undergoing primary anatomical double-bundle ACL reconstruction with autologous hamstrings as graft sources, at multiple centers between February 2021 and August 2022. After securing the anteromedial (AM) and posterolateral (PL) bundle grafts to the femoral cortex, they were initially tensioned to 40 N per bundle. After 10 cycles of knee extension and flexion motion, ranging from 0 to 90-110°, tension was re-measured and re-tensioned to 40 N if the graft tension had decreased. This was repeated thrice for 10 cycles on each graft. Every 10 cycles, we recorded graft tension changes (ΔGT) and compared the mean ΔGT in the AM and PL bundles. Furthermore, we assessed relationships between total ΔGT in each bundle, age, sex, and graft diameter. RESULTS: Twenty-five women and 14 men with a mean age of 27.4 ± 12.4 years were included. The mean ΔGT in AM and PL bundles after every 10 cycles were 6.6 ± 3.7 N, 3.0 ± 2.3 N, 1.4 ± 1.5 N, and 9.9 ± 3.8 N, 4.9 ± 2.6 N, and 2.5 ± 1.9 N, respectively. There were significant differences in ΔGT in both bundles after every 10 cycles (p < 0.01). ΔGT in the AM bundle was significantly lower than in the PM bundle at the same number of cycles (p < 0.01). No correlation was observed between ΔGT in either bundle and age, sex, or graft diameter. CONCLUSIONS: The initially applied graft tension decreased by intra-operative cyclic knee movement, and the changes in graft tension decreased after retention and repeated cycles. Three sets of 10 cycles knee motion may avoid initial tension loss of the hamstring autograft in the early phase after double-bundle ACL reconstruction.