Development of dynamic knee stability after acute ACL injury

Adaptive Adjustments in Lower Limb Muscle Coordination during Single-Leg Landing Tasks in Latin Dancers

Previous research has primarily focused on evaluating the activity of individual muscles in dancers, often neglecting their synergistic interactions. Investigating the differences in lower limb muscle synergy during landing between dancers and healthy controls will contribute to a comprehensive understanding of their neuromuscular control patterns. This study enrolled 22 Latin dancers and 22 healthy participants, who performed a task involving landing from a 30 cm high platform. The data were collected using Vicon systems, force plates, and electromyography (EMG). The processed EMG data were subjected to non-negative matrix factorization (NNMF) for decomposition, followed by classification using K-means clustering algorithm and Pearson correlation coefficients. Three synergies were extracted for both Latin dancers and healthy participants. Synergy 1 showed increased contributions from the tibialis anterior (p < 0.001) and medial gastrocnemius (p = 0.024) in Latin dancers compared to healthy participants. Synergy 3 highlighted significantly greater contributions from the vastus lateralis in healthy participants compared to Latin dancers (p = 0.039). This study demonstrates that Latin dancers exhibit muscle synergies similar to those observed in healthy controls, revealing specific adjustments in the tibialis anterior and medial gastrocnemius muscles among dancers. This research illustrates how dancers optimize control strategies during landing tasks, offering a novel perspective for comprehensively understanding dancers' neuromuscular control patterns.

The effect of perturbation training with and without applying the dry needling on leg muscles in patients with chronic ankle sprain

INTRODUCTION

Ankle sprain is a common musculoskeletal injury that leads to recurrent instability. Repeated ankle sprain can be a mechanism for creating trigger point. Proper treatment of trigger points, in addition to preventing recurrence of sprains, may reduce pain and improve muscle function. This improvement can be the result of preserving the surrounding tissues from excessive pressure.

OBJECTIVE

Investigate the added value of dry needling into perturbation training protocol for chronic ankle sprain.

DESIGN

Randomized clinical trial; assessor-blind; before and after comparison.

SETTING

Treatment of patients referred to the institutional rehabilitation clinics.

MAIN OUTCOME MEASURE(S)

Functional assessment with FAAM questionnaire score, Pain with NPRS scale, ankle instability severity with Cumberland tool.

METHODS

Twenty-four patients with chronic ankle instability participated in this clinical trial and were randomly divided into two groups. Intervention was 12 sessions in which one group received only perturbation training and the other group received perturbation training along with dry needling. Repeated measures ANOVA was used to investigate the effect of treatment.

RESULTS

Data Analysis showed significant difference in NPRS and FAAM and Cumberland score before and after treatment in each group (P < 0.001). Comparison of the results between the groups did not show any significant difference (P > 0.05).

CONCLUSION

The findings showed that adding dry needling technique to the perturbation training does not have greater effects on the pain and function of patients with chronic ankle instability.

Hip Abductor and External Rotator Strengths Correlate With Hop Symmetry in Men Athletes 2 Years After Anterior Cruciate Ligament Reconstruction

CONTEXT

Hip muscle strength and hop performance limb symmetries after anterior cruciate ligament reconstruction (ACLR) are not well studied. This study aimed to determine the differences in hip abductors' (ABD) and external rotators' (ER) muscle strength measures between limbs, and the relationship between hip ABD and ER muscle strengths and hop performance limb symmetry indices (LSIs) 2 years after ACLR.

DESIGN

Cross-sectional study.

METHODS

Forty (level I/II) men athletes 2 years after unilateral ACLR completed 4 single-legged hop tests and involved hip ABD and ER strength testing (maximum voluntary isometric contraction [MVIC]; isokinetic peak torque [PKTQ] at 60°, 180°, and 300°/s; and isotonic peak velocity at 75% of their MVICs). Muscle strength measures were normalized to body mass, and hop performances were reported as LSIs. Paired t test was used to determine strength differences between limbs, and the Pearson correlation coefficient was used to assess the relationship between involved hip muscle strength measures and hop performance LSIs.

RESULTS

Hip ER-MVIC (involved: 60.26 [12.01], uninvolved: 63.68 [13.17] N·m/kg) and ER eccentric PKTQ at 60°/s (involved: 32.59 [9.28]; uninvolved: 35.73 [10.50] N·m/kg) were significantly different between limbs (P ≤ .018). Single-hop LSI correlated with hip ER-PKTQ at 180°/s (r = .354) and 300°/s (r = .324, P ≤ .041), while triple-hop LSI correlated with hip ER-MVIC (r = .320), concentric ER-PKTQ at 180°/s (r = .355), eccentric ER-PKTQ at 60°/s (r = .314), and hip ABD-PKTQ at 60°/s (r = .364) and 300°/s (r = .336, P ≤ .049).

CONCLUSIONS

Men athletes demonstrated symmetrical hop performance and hip muscle strengths, except for ER hip's MVIC and isokinetic eccentric peak torque at 60°/s 2 years after ACLR. Hop performance LSIs had a few, yet positive moderate relationships with involved hip ABDs and ER strength measures. This may indicate that hip ABD and ER muscle strength measures contribute to athletes' hop performances 2 years after ACLR. Post-ACLR rehabilitation programs might incorporate hip muscle strengthening training to improve athletes' functional performances.

Priming Effects of Anodal Transcranial Direct Current Stimulation on the Effects of Conventional Physiotherapy on Balance and Muscle Performance in Athletes With Anterior Cruciate Ligament Injury

CONTEXT

In athletes, postural control impairment and knee muscle dysfunction are the most common disorders following anterior cruciate ligament (ACL) injury. Because of functional changes in the motor cortex following ACL injury, physiotherapy (PT) is not enough for treatment and using neuromodulators, such as trans-cranial direct current stimulation (tDCS) may be necessary. The present study focused on the effects of anodal tDCS (a-tDCS) over the primary motor cortex (M1) concurrent with PT on postural control and muscular performance in the athletes with ACL injury.

DESIGN

In this study, 34 athletes with ACL injury were randomly assigned in 2 groups of intervention group (active M1 a-tDCS concurrent with PT, n = 16) and control group (sham M1 a-tDCS concurrent with PT, n = 16).

METHODS

The participants of all groups received 20-minute 2 mA M1 a-tDCS with PT during 10 sessions, while tDCS was turned off after 30 seconds in the sham group. Before, immediately following, and 1 month after the interventions, the center of pressure and the average of power of flexor and extensor muscles at 2 velocities of 30°/s and 60°/s were measured by force plate and isokinetic devices, respectively.

RESULTS

One month after treatment, the displacement of center of pressure was decreased in the intervention group (P < .05), while there were no changes in the control group. Y-axis of center of pressure decreased in the intervention group relative to the control group, although average of power of flexor and extensor muscles increased immediately in both groups, but the rise in the intervention group was larger than that in the control group (P < .05).

CONCLUSION

The findings indicated that M1 a-tDCS can induce the efficacy of PT, which has a lasting effect on the improvement of the postural control in athletes with ACL injury.

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.

Comparison of muscle strength and neuromuscular control up to 1 year after anterior cruciate ligament reconstruction between patients with dominant leg and non-dominant leg injuries

BACKGROUND

There has not been an investigation to determine whether leg dominance affects the recovery of quadriceps and hamstring strength, muscle reaction time (acceleration time, AT), and postural stability after anterior cruciate ligament (ACL) reconstruction in recreational-level athletic patients.

METHODS

A total of 100 patients with isolated ACL injuries (58 patients had dominant leg injuries; 42 patients had non-dominant leg injuries) participated. All patients received an anatomical single-bundle ACL reconstruction using an auto-hamstring tendon graft without preoperative rehabilitation. Leg dominance was defined as the kicking leg. The quadriceps and hamstring strength, AT, and postural stability (overall stability index (OSI)) of both legs were assessed at three different time points (preoperative, 6 months, 12 months), using an isokinetic dynamometer and postural stabilometry system.

RESULTS

All patients in both groups showed gradual improvement in quadriceps and hamstring muscle strength in the operated legs up to 1 year postoperatively. However, the mean value of quadriceps strength was lower in the operated non-dominant leg than the operated dominant leg 6 months postoperatively (P = 0.048). The AT and OSI of the operated legs in both groups recovered significantly 6 months postoperatively compared with their preoperative values; however, the AT and OSI values after 6 and 12 months were similar.

CONCLUSION

Quadriceps strength of the operated non-dominant leg was lower than that of the operated dominant leg 6 months postoperatively; however, the strength of the quadriceps and hamstring muscles was not different after 12 months between the operated dominant and non-dominant legs. Clinicians and physical therapists should consider these results during early rehabilitation and identify effective protocols to enhance quadriceps strength, especially in patients with non-dominant leg injuries.

Poorer dynamic postural stability in patients with anterior cruciate ligament rupture combined with lateral meniscus tear than in those with medial meniscus tear

Background

Only limited data are available regarding postural stability between anterior cruciate ligament (ACL)-injured patients with medial meniscus (MM) tear and those with lateral meniscus (LM) tear. The purpose of this study was to compare preoperative postural stability for both involved and uninvolved knees in ACL rupture combined with MM and LM tears. It was hypothesized that there would be a significant difference in postural stability between these two groups.

Methods

Ninety-three ACL-injured patients (53 combined with MM tears vs. 40 combined with LM tears) were included. Static and dynamic postural stability were evaluated with the overall stability index (OSI), anterior–posterior stability index (APSI), and medial–lateral stability index (MLSI) using stabilometry. Knee muscle strength was evaluated using an isokinetic testing device.

Results

In the static postural stability test, none of the stability indices showed significant differences between the two groups for both knees (p > 0.05). In the dynamic postural stability test for involved side knees, the OSI and APSI were significantly higher in the LM tear group compared to the MM tear group (OSI: 2.0 ± 0.8 vs. 1.6 ± 0.5, p = 0.001; APSI: 1.5 ± 0.6 vs. 1.3 ± 0.5, p = 0.023), but not the MLSI (p > 0.05). In the static and dynamic postural stability tests in each group, there were no significant differences between the involved and uninvolved side knees (p > 0.05). There was no significant difference in the knee muscle strength between the two groups (p > 0.05). All postural stability showed no significant correlation with knee muscle strength (p > 0.05).

Conclusion

Dynamic postural stability was poorer in patients with ACL rupture combined with LM tear than in those with MM tear. Therefore, close monitoring for postural stability would be necessary during preoperative and postoperative rehabilitation, especially for patients with ACL rupture combined with LM tear.

Level of evidence: Level III

Quadriceps-hamstrings intermuscular coherence during single-leg squatting 3-12 years following a youth sport-related knee injury

The purpose of this study was to determine the degree of co-contraction as per electromyographic gamma-band intermuscular coherence of the quadricep (Q) and hamstring (H) muscles during single-leg squatting (SLS), and to assess the influence of sex and self-reported knee complaints on the association between knee injury history and medial and lateral Q-H intermuscular coherence. Participants included 34 individuals who suffered a youth sport-related intra-articular knee injury 3-12 years previously, and 37 individuals with no knee injury history. Surface electromyographic signals were recorded from medial and lateral thigh muscles bilaterally to determine the gamma-band (30-60 Hz) intermuscular coherence between medial and lateral Q-H muscle pairs during SLS. Multivariable linear regression (α = 0.05) was performed to investigate the relationship between knee injury history (main exposure) and medial and lateral Q-H coherence (outcome) while accounting for the influence of sex and self-reported knee pain and symptoms (covariates). The median age of participants was 25 (range 18-30) and 67% were female. Q-H gamma-band coherence was present for 60-90% of legs. Medial and lateral Q-H coherence was higher in females compared to males. There was no evidence for an association between medial Q-H coherence, knee injury history, knee pain, or symptoms. There was evidence for an association between knee injury history and lateral Q-H coherence, which was modified by sex such that previously injured males demonstrated reduced Q-H coherence compared to uninjured males. These finding suggest that females demonstrate a more pronounced Q-H co-contraction strategy during a SLS than males regardless of knee injury history. Further, that male who suffered a youth sport-related knee injury 3-12 years previously demonstrate less Q-H co-contraction during a SLS than uninjured males. The mechanisms behind differences in neuromuscular control between males and females as well as previously injured and uninjured males require further investigation.

Objective parameters to measure (in)stability of the knee joint during gait: A review of literature

BACKGROUND

Instability of the knee joint during gait is frequently reported by patients with knee osteoarthritis or an anterior cruciate ligament rupture. The assessment of instability in clinical practice and clinical research studies mainly relies on self-reporting. Alternatively, parameters measured with gait analysis have been explored as suitable objective indicators of dynamic knee (in)stability.

RESEARCH QUESTION

This literature review aimed to establish an inventory of objective parameters of knee stability during gait.

METHODS

Five electronic databases (Pubmed, Embase, Cochrane, Cinahl and SPORTDiscuss) were systematically searched, with keywords concerning knee, stability and gait. Eligible studies used an objective parameter(s) to assess knee (in)stability during gait, being stated in the introduction or methods section. Out of 10717 studies, 89 studies were considered eligible.

RESULTS

Fourteen different patient populations were investigated with kinematic, kinetic and/or electromyography measurements during (challenged) gait. Thirty-three possible objective parameters were identified for knee stability, of which the majority was based on kinematic (14 parameters) or electromyography (12 parameters) measurements. Thirty-nine studies used challenged gait (i.e. external perturbations, downhill walking) to provoke knee joint instability. Limited or conflicting results were reported on the validity of the 33 parameters.

SIGNIFICANCE

In conclusion, a large number of different candidates for an objective knee stability gait parameter were found in literature, all without compelling evidence. A clear conceptual definition for dynamic knee joint stability is lacking, for which we suggest : "The capacity to respond to a challenge during gait within the natural boundaries of the knee". Furthermore biomechanical gait laboratory protocols should be harmonized, to enable future developments on clinically relevant measure(s) of knee stability during gait.

Impaired neuromuscular control up to postoperative 1 year in operated and nonoperated knees after anterior cruciate ligament reconstruction

The current study was performed to assess serial changes in neuromuscular control until 1 year postoperatively in nonathletic patients undergoing anterior cruciate ligament reconstruction (ACLR).Ninety-six patients were included. Serial neuromuscular control tests were performed preoperatively, at 6 months, and 1 year postoperatively. Neuromuscular control was evaluated using acceleration time (AT) and dynamic postural stability (overall stability index, OSI). Functional activity levels were assessed using the Tegner activity-level scale.Preoperative AT of quadriceps and hamstrings in operated knees was 78.9 ± 6.4 and 86.5 ± 6.2 ms, respectively, which significantly reduced to 56.9 ± 2.0 and 62.5 ± 2.8 ms at 1 year (P = 0.006 and 0.002, respectively). In nonoperated knees, preoperative AT of quadriceps and hamstrings was 47.6 ± 1.7 and 56.5 ± 1.7 ms, respectively, which was significantly prolonged to 54.3 ± 2.0 and 67.9 ± 2.7 ms at 1 year (P = 0.02 and 0.001, respectively). Preoperative OSI of nonoperated knees was 1.2 ± 0.0°. It significantly increased to 1.5 ± 0.1° at 1 year (P < 0.001). In operated knees, preoperative OSI was 1.8 ± 0.1°. It significantly decreased to 1.4 ± 0.1° at 1 year (P = 0.001). Tegner scale at 6 months and 1 year were significantly lower than pre-operative scale (P < 0.001). AT and OSI on both knees showed significant negative correlation with Tegner scale at 6 months and 1 year.Neuromuscular control in both knees was not restored to preoperative levels of the nonoperated knees until 1 year after ACLR. Therefore, clinicians and physical therapists should attempt to enhance neuromuscular control in both nonoperated and operated knees.

A comparative study of the neuromuscular response during a dynamic activity after anterior cruciate ligament reconstruction

BACKGROUND

Injury to the anterior cruciate ligament (ACL) not only causes mechanical instability but also produces proprioceptive deficit with an altered neuromuscular response. After ACL reconstruction, patients in general continue to complain of a feeling of knee instability. The objective of our study was to assess patient proprioception and its evolution over time by measuring the muscle latency time during a dynamic activity.

METHODS

Twenty-five patients with an ACL tear following sports injuries were included in a prospective, comparative, matched controlled study. The study group consisted of the injured knees in those patients, while the control group consisted of the contralateral non-injured knee in the same patients. The neuromuscular response in five leg muscles (vastus medialis, vastus lateralis, rectus femoris, semitendinosus and biceps femoris) was measured during a dynamic activity through the muscle latency time via the use of electromyography.

RESULTS

The comparison of the reaction time in the vastus medialis showed that time in the injured knee was longer at pre-op, but it reduced over time reaching a value at 6 months post-op that was close to the reaction time in the non-injured knee group. In the rectus femoris, biceps femoris and semitendinosus muscles, the reaction times in the injured knee group were similar to those in the non-injured knee group at pre-op and post-op visits.

CONCLUSION

Before ACL surgery, the muscle latency time of the vastus medialis was significantly longer in the injured knee group than in the non-injured knee group. 'Muscle reflex reaction' as a response during a dynamic task improved in the ACL reconstructed patients at 6 months post-op.

LEVEL OF EVIDENCE

Prospective, comparative, matched controlled study.

Co-activation patterns of gastrocnemius and quadriceps femoris in controlling the knee joint during walking

Muscular co-activation is a well-known mechanism for lower limb joint stabilization in both healthy and pathological individuals. This muscular feature appears particularly important for the knee joint, not only during challenging motor tasks such as cutting and landing but also during walking, due to knee cyclic loading. Gastrocnemius acts on the knee joint with a flexor activity and co-activations with quadriceps muscles lead to greater knee ligament strain with respect to an isolated burst of either muscle. Thus, this study aimed to assess possible co-activations between gastrocnemius and quadriceps muscles during walking. Five co-activation periods were assessed: during early stance (identified in 5.7 ± 5.1% of total strides), early and late foot-contact (88.9 ± 8.9% and 8.9 ± 8.2%), push-off (23.9 ± 12.2%) and late swing (29.0 ± 16.1%). Outcomes showed that late foot-contact and swing co-activations could deserve particular attention: in both cases the knee joint was close to the full extension (around 3.5° and 6°, respectively) and thus, considering also the anterior tibia translation due to the quadriceps activity, the simultaneous gastrocnemius burst could lead to an enhanced knee ligaments elongation. Findings of this study represent the first attempt to provide a reference knee joint co-activation framework, useful also for further evaluation in cohorts with knee failures.

Non-operative Care of the Patient with an ACL-Deficient Knee

PURPOSE OF REVIEW

The purpose of this review is to provide an update to the most objective, evidence-based path through a non-operative course of rehabilitation after anterior cruciate ligament injury for those hoping to return to pivoting and cutting sports.

RECENT FINDINGS

Anterior cruciate ligament (ACL) injuries are prevalent in pivoting and cutting athletes with many of these patients electing to pursue surgical reconstruction in hopes of returning to prior levels of function. Despite many athletes pursing ACL reconstruction, some may elect to pursue a non-operative course of care. Success with this treatment plan should be defined as the ability to return to sport without subsequent giving way episodes. Identification of those most likely to successfully return to sport with a non-operative course begins with completion of an evidence-based screening tool. If the patient has no concomitant injury and successfully passes the screening, they may proceed to a systematic, evidence-based progression through rehabilitation. Finally, the patient must complete a return to sport program and meet appropriate objective criteria, prior to return to sport.

The Advantages of Normalizing Electromyography to Ballistic Rather than Isometric or Isokinetic Tasks

Isometric tasks have been a standard for electromyography (EMG) normalization stemming from anatomic and physiologic stability observed during contraction. Ballistic dynamic tasks have the benefit of eliciting maximum EMG signals for normalization, despite having the potential for greater signal variability. It is the purpose of this study to compare maximum voluntary isometric contraction (MVIC) to nonisometric tasks with increasing degrees of extrinsic variability, ie, joint range of motion, velocity, rate of contraction, etc., to determine if the ballistic tasks, which elicit larger peak EMG signals, are more reliable than the constrained MVIC. Fifteen subjects performed MVIC, isokinetic, maximum countermovement jump, and sprint tasks while EMG was collected from 9 muscles in the quadriceps, hamstrings, and lower leg. The results revealed the unconstrained ballistic tasks were more reliable compared to the constrained MVIC and isokinetic tasks for all triceps surae muscles. The EMG from sprinting was more reliable than the constrained cases for both the hamstrings and vasti. The most reliable EMG signals occurred when the body was permitted its natural, unconstrained motion. These results suggest that EMG is best normalized using ballistic tasks to provide the greatest within-subject reliability, which beneficially yield maximum EMG values.

Use of a portable motion analysis system for knee dynamic stability assessment in anterior cruciate ligament deficiency during single-legged hop landing

Background/objective

Anterior cruciate ligament (ACL) rupture results in knee instability, and patients are often unable to return to their previous level of activity. Current assessments rely on passive laxity tests, which do not correlate with function. Dynamic stability may be a better indicator for return to sport. However, equipment for measuring dynamic stability is ill suited for clinical use. The purpose of this study is to evaluate knee kinematics in ACL-deficient patients with a single-legged hop task using a portable motion analysis system. We hypothesize that the assessment task is able to differentiate ACL-deficient knees from healthy knees.

Methods

Ten ACL-deficient patients and 10 healthy controls were recruited. Participants were instructed to perform a single-legged hop, while kinematics was measured using a portable motion capture system (Opti-Knee; Shanghai Innomotion Inc., Shanghai, China). Kinematic changes after initial contact were examined. Repeatability of the results was examined by calculating the coefficient of variations of the pooled standard deviation of the tibiofemoral displacements. Side-to-side differences were calculated and compared between the two groups.

Results

One patient could not perform the task. Intraindividual variability was small after initial contact; the coefficient of variation in this region was 13-26%. ACL-deficient knees demonstrated lower flexion range of motion (p = 0.008) and increased internal/external rotation range of motion after landing (p = 0.038), while no significant differences were detected in the healthy group. Only the side-to-side difference in flexion was significantly different between the two groups (p = 0.002).

Conclusion

The altered knee kinematics in ACL-deficient patients can be revealed by a portable motion capture system, which may enable the clinical application of kinematic assessment in the evaluation of ACL deficiency.

Gait analysis of national athletes after anterior cruciate ligament reconstruction following three stages of rehabilitation program: Symmetrical perspective

This study aimed to objectively evaluate changes in gait kinematics, kinetics and symmetry among anterior cruciate ligament (ACL) reconstructed athletes during rehabilitation. Twenty-two national athletes with ACL reconstruction and 15 healthy athletes were recruited for the study. Gait data were collected between the weeks 4-5, 8-9, and 12-13 post-operation using three-dimensional motion analysis system. Five separate components, including knee range of motion (ROM), vertical ground reaction force (VGRF), their symmetries and knee extension moment were evaluated. One way and repeated measure multivariate analysis of variance (MANOVA) were used to analyze the knee ROMs. The VGRF and extension moment were tested using repeated measure ANOVA and independent sample t-test. Findings indicated significant alterations in all measured components between patients' Test 1 and control group. Repeated measure analysis revealed significant effect for time in components of knee angular and VGRF (P<0.001), their symmetry index (P=0.03) and knee extension moment (P=0.045). Univariate outcomes demonstrated significant improvement in the injured limb's stance and swing (P<0.001), and single-stance (P=0.005) ROMs over time. Symmetry indexes of stance and swing ROM, and VGRF reduced significantly by 26.3% (P=0.001), 17.9% (P<0.001), and 31.9% (P=0.03) respectively. After three months, symmetry indexes of single-stance ROM and VGRF along with operated knee extension moment were the only variables which showed significant differences with control group. The rehabilitation program allowed national athletes to restore the operated limb's gait parameters except knee extension moment by 12-13 weeks post-reconstruction; however, more time is required to normalize single-stance ROM and VGRF asymmetries.

Motion Task Selection for Kinematic Evaluation After Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To examine the different motion tasks and the protocols used to objectively quantify dynamic stability in terms of knee kinematics at different stages of anterior cruciate ligament reconstruction (ACLR) recovery.

METHODS

A systematic search was done using OVID in Embase, Cochrane Central Register of Controlled Trials, Medline, PsychINFO, and AMED. A combination of the following keywords and their variations were used: anterior cruciate ligament, motion tasks (e.g., jump, hop, gait), and stability. The inclusion criteria were as follows: (1) ACLR subjects were recruited, (2) at least 1 motion task was performed and kinematics data were recorded, and (3) uninjured subjects or the contralateral uninjured limbs were included as a control group. Exclusion criteria were as follows: (1) non-English language publications, (2) retrospective studies and review articles, (3) animal studies, and (4) cadaveric studies.

RESULTS

The search returned 2,195 studies, and 56 were included in this review according to the criteria. A total of 1,086 ACLR subjects were included. Pivoting, landing, walking, running, stair negotiation, and squats were assessed using optoelectronic motion capture, electrogoniometry, or video-radiography.

CONCLUSIONS

The appropriate selection of motion tasks is an integral factor in dynamic stability testing as it evokes different kinematic outcomes in relation to the different stages of ACLR recovery. Stair negotiation and landing tasks are best performed during the early stages of recovery, and landing and pivoting are recommended 6 months after ACLR surgery.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Three-dimensional kinematic and kinetic gait deviations in individuals with chronic anterior cruciate ligament deficient knee: A systematic review and meta-analysis

BACKGROUND

Altered joint motion that occurs in people with an anterior cruciate ligament deficient knee is proposed to play a role in the initiation of knee osteoarthritis, however, the exact mechanism is poorly understood. Although several studies have investigated gait deviations in individuals with chronic anterior cruciate ligament deficient knee in the frontal and transverse planes, no systematic review has summarized the kinematic and kinetic deviations in these two planes.

METHODS

We searched five electronic databases from inception to 14th October 2013, with key words related to anterior cruciate ligament, biomechanics and gait, and limited to human studies only. Two independent reviewers assessed eligibility based on predetermined inclusion/exclusion criteria and methodological quality was evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology statement checklist.

FINDINGS

We identified 16 studies, totaling 183 subjects with anterior cruciate ligament deficient knee and 211 healthy subjects. Due to the variability in reported outcomes, we could only perform meta-analysis for 13 sagittal plane outcomes. The only significant finding from our meta-analysis showed that individuals with anterior cruciate ligament deficient knee demonstrated a significantly greater external hip flexor angular impulse compared to control (P=0.03).

INTERPRETATION

No consensus about what constitutes a typical walking pattern in individuals with anterior cruciate ligament deficient knee can be made, nor can conclusions be derived to explain if gait deviations in the frontal and transverse plane contributed to the development of the knee osteoarthritis among this population.

Static and dynamic tibial translation before, 5 weeks after, and 5 years after anterior cruciate ligament reconstruction

PURPOSE

To evaluate static and dynamic tibial translation before, 5 weeks after, and 5 years after anterior cruciate ligament (ACL) reconstruction. To explore whether static and dynamic tibial translation are correlated.

METHODS

Ten patients undergoing quadruple hamstring tendon graft ACL reconstruction were evaluated before, 5 weeks after, and 5 years after ACL reconstruction. Sagittal tibial translation was measured during the Lachman test (static translation) and during gait (dynamic translation) using a CA-4000 electrogoniometer.

RESULTS

Five years after ACL reconstruction, static tibial translation did not differ between knees (Lachman test 90 N and 134 N n.s.). In contrast, there was greater maximal anterior tibial translation during gait in ACL-reconstructed knees than in uninjured knees (5.5 ± 1.4 vs. 4.5 ± 1.6 mm, P = 0.028). There were no differences in static or dynamic tibial translation between the 5-year follow-up and before ACL reconstruction or between the 5-year follow-up and the 5-week follow-up. There were no correlations between static and dynamic tibial translation.

CONCLUSION

Although static tibial translation did not differ between knees 5 years after ACL reconstruction, dynamic tibial translation during gait was greater in ACL-reconstructed knees than in uninjured knees. Neither static nor dynamic tibial translation changed 5 years after ACL reconstruction as compared to before surgery and 5 weeks after surgery. Static tibial translation did not correlate with dynamic tibial translation.

CLINICAL RELEVANCE

This study indicates that although the knee is stable during static measurements, kinematics during gait is impaired 5 years after ACL reconstruction. This may affect the return to sport and risk of osteoarthritis.

LEVEL OF EVIDENCE

Case series, Level IV.

Lower extremity muscle activation onset times during the transition from double-leg stance to single-leg stance in anterior cruciate ligament injured subjects

The goal of this study was to evaluate muscle activation onset times (MAOT) of both legs during a transition task from double-leg stance (DLS) to single-leg stance (SLS) in anterior cruciate ligament injured (ACLI) (n=15) and non-injured control subjects (n=15) with eyes open and eyes closed. Significantly delayed MAOT were found in the ACLI group compared to the control group for vastus lateralis, vastus medialis obliquus, hamstrings medial, hamstrings lateral, tibialis anterior, peroneus longus and gastrocnemius in both vision conditions, for gluteus maximus and gluteus medius with eyes open and for tensor fascia latae with eyes closed. Within the ACLI group, delayed MAOT of tibialis anterior with eyes open and gastrocnemius with eyes closed were found in the injured leg compared to the non-injured leg. All other muscles were not significantly different between legs. In conclusion, the ACLI group showed delayed MAOT not only around the knee, but also at the hip and ankle muscles compared to the non-injured control group. No differences between both legs of the ACLI group were found, except for tibialis anterior and gastrocnemius. These findings indirectly support including central nervous system re-education training to target the underlying mechanisms of these altered MAOT after ACL injury.

The Effects of Balance Training on Static and Dynamic Postural Stability Indices After Acute ACL Reconstruction

Background:

Proprioception and postural stability play an important role in knee movements. However, there are controversies about the overall recovery time of proprioception following knee surgery and onset of balance and neuromuscular training after ACL reconstruction. Therefore, it is necessary to evaluate the effect of balance training in early stage of knee rehabilitation after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the effect of balance exercises on postural stability indices in subjects with anterior cruciate ligament (ACL) reconstruction.

Methods:

The study was a controlled randomized trial study. Twenty four patients who had ACL reconstructed (balance training group) and twenty four healthy adults without any knee injury (control group) were recruited in the study. The balance exercises group performed balance exercises for 2 weeks. Before and after the interventions, overall, anteroposterior, and mediolateral stability indices were measured with a Biodex Balance System in bilateral and unilateral stance positions with the eyes open and closed. T-tests were used for statistical analysis (p<0.05).

Results:

Results showed that amount of static stability indices did not change after training and there were not significant differences in static stability indices before and after balance training (p>0.05). Although amount of dynamic stability indices decreased, there were not significant differences in dynamic stability indices before and after balance training (p>0.05). Amount of dynamic stability indices were decreased in balance training group, however, there were not significant differences between groups (p>0.05).

Conclusion:

These results support that balance exercise could partially improved dynamic stability indices in early stage of ACL reconstruction rehabilitation. The results of this study suggest that balance exercises should be part of the rehabilitation program following ACL reconstruction.

Sex-specific gait adaptations prior to and up to 6 months after anterior cruciate ligament reconstruction

STUDY DESIGN

Controlled longitudinal laboratory study.

OBJECTIVES

To compare sagittal plane gait mechanics of men and women before and up to 6 months after anterior cruciate ligament reconstruction (ACLR).

BACKGROUND

Aberrant gait patterns are ubiquitous after anterior cruciate ligament (ACL) rupture and persist after ACLR despite skilled physical therapy. Sex influences postoperative function and second-ACL injury risk, but its influence on gait adaptations after injury has not been investigated.

METHODS

Sagittal plane knee and hip joint excursions during midstance and internal knee and hip extension moments at peak knee flexion were collected in 12 women and 27 men using 3-D gait analysis before (screening) and after preoperative physical therapy (presurgery), and 6 months after ACLR (6 months postsurgery). Repeated-measures analysis-of-variance models were used to determine whether limb asymmetries changed differently over time in men and women.

RESULTS

Significant time-by-limb-by-sex interactions were identified for hip and knee excursions and internal knee extension moments (P ≤.007). Both sexes demonstrated smaller knee excursions on the involved limb compared to the uninvolved limb at each time point (P ≤.007), but only women demonstrated a decrease in the involved knee excursion from presurgery to 6 months postsurgery (P = .03). Women also demonstrated smaller hip excursions (P<.001) and internal knee extension moments (P = .005) on the involved limb compared to the uninvolved limb at 6 months postsurgery. Men demonstrated smaller hip excursions and knee moments on the involved limb compared to the uninvolved limb (P<.001) regardless of time.

CONCLUSION

The persistence of limb asymmetries in men and women 6 months after ACLR indicates that current postoperative rehabilitation efforts are inadequate for some individuals following ACLR.

Association between long-term quadriceps weakness and early walking muscle co-contraction after total knee arthroplasty

INTRODUCTION

Quadriceps weakness is one of the primary post-operative impairments that persist long term for patients after total knee arthroplasty (TKA). We hypothesized that early gait muscle recruitment patterns of the quadriceps and hamstrings with diminished knee performance at 3months after surgery would be related to long-term quadriceps strength at 1year after TKA.

METHODS

Twenty-one subjects who underwent primary unilateral TKA and 14 age-matched healthy controls were analyzed. At 3months after TKA, the maximum voluntary isometric contraction of the quadriceps and a comprehensive gait analysis were performed. Quadriceps strength was assessed again at 1year after surgery.

RESULTS

Quadriceps muscle recruitment of the operated limb was greater than the non-operated limb during the loading response of gait (p=0.03), but there were no significant differences in hamstring recruitment or co-contraction between limbs (p>0.05). There were significant differences in quadriceps muscle recruitment during gait between the non-operated limbs of the TKA group and the healthy control group (p<0.05). The TKA group showed a significant inverse relationship between one year quadriceps strength and co-contraction (r=-0.543) and hamstring muscle recruitment (r=-0.480) during loading response at 3months after TKA.

CONCLUSIONS

The results revealed a reverse relationship where stronger patients tended to demonstrate lower quadriceps recruitment at 3months post-surgery that was not observed in the healthy peer group. The altered neuromuscular patterns of the quadriceps and hamstrings during gait may influence chronic quadriceps strength in individuals after TKA.

LEVEL OF EVIDENCE

III.

The role of muscle activation in cruciate disease

Traditional investigations into the etiopathogenesis of canine cranial cruciate ligament (CCL) disease have focused primarily on the biological and mechanical insults to the CCL as a passive stabilizing structure of the stifle. However, with recent collaboration between veterinarians and physical therapists, an increased focus on the role of muscle activity and aberrant motor control mechanisms associated with anterior cruciate ligament (ACL) injuries and rehabilitation in people has been transferred and applied to dogs with CCL disease. Motor control mechanisms in both intact and cruciate-deficient human knees may have direct translation to canine patients, because the sensory and motor components are similar, despite moderate anatomic and biomechanical differences. Components of motor control, such as muscle recruitment and the coordination and amplitudes of activation are strongly influenced by afferent proprioceptive signaling from peri- and intra-articular structures, including the cruciate ligaments. In people, alterations in the timing or amplitude of muscle contractions contribute to uncoordinated movement, which can play a critical role in ACL injury, joint instability and the progression of osteoarthritis (OA). A better understanding of motor control mechanisms as they relate to canine CCL disease is vitally important in identifying modifiable risk factors and applying preventative measures, for development of improved surgical and rehabilitative treatment strategies. The purpose of this review article is to analyze the influence of altered motor control, specifically pelvic limb muscle activation, in dogs with CCL disease as evidenced by mechanisms of ACL injury and rehabilitation in people.

The effect of early whole-body vibration therapy on neuromuscular control after anterior cruciate ligament reconstruction: a randomized controlled trial

BACKGROUND

Despite rehabilitation training, deficiency in knee joint position sense, muscular performance, postural control, and functional ability is common after anterior cruciate ligament reconstruction (ACLR). Whole-body vibration therapy (WBVT), which is initiated from 3 months postoperatively, has proven benefits. However, the effect of earlier WBVT is unknown.

PURPOSE

To investigate the effect of early WBVT on neuromuscular control after ACLR.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 48 patients with unilateral complete isolated ACL tears were recruited. Single-bundle hamstring ACLR was performed in all patients. After surgery, they were randomly assigned to either the reference or treatment group. Reference group patients received conventional ACL rehabilitation, while treatment group patients received 8 weeks of WBVT in addition to conventional rehabilitation, starting from 1 month postoperatively. Joint position sense, postural control, and knee isokinetic performance were assessed before surgery and at 1, 3, and 6 months postoperatively using the Biodex dynamometer, Biodex Stability System, and Cybex NORM, respectively. Knee range of motion (ROM), stability (manual testing and KT-1000 arthrometer), and functional ability (single-legged hop test, triple hop test, shuttle run test, and carioca test) were also examined. Two-way repeated-measures analysis of variance and the Mann-Whitney U test were used for statistical analysis.

RESULTS

There was no complication throughout the rehabilitation. All patients achieved full knee ROM and stable knee joints at 6 months after surgery. The WBVT group demonstrated significantly better postural control, muscle performance, single-legged hop, and shuttle run (P < .05) than the reference group, but there was no significant difference in knee joint position sense, triple hop, carioca, ROM, and stability (P > .05).

CONCLUSION

Early WBVT started from 1 month postoperatively was an effective training method without compromising knee ROM and stability. It improved postural control, isokinetic performance, single-legged hop, and shuttle run but not knee joint position sense, triple hop, and carioca.

The effect of anterior cruciate ligament rupture on the timing and amplitude of gastrocnemius muscle activation: a study of alterations in EMG measures and their relationship to knee joint stability

Changes in hamstring and quadriceps activity are well known in individuals with anterior cruciate ligament deficiency (ACLD) to potentially compensate for knee joint instability. However, few studies have explored gastrocnemius activity or its relationship to knee stability. The purpose of this study was therefore to examine the activation characteristics of medial gastrocnemius (MG) in ACLD subjects and relate any changes to knee joint laxity. Two subject cohorts were assessed: those with unilateral ACLD (n=15) and uninjured control subjects (n=11). Surface EMG of the left and right MG were recorded during a controlled single leg hop on each limb. Onset and offset of MG activation relative to take-off, during flight and landing were calculated as well as muscle activity (RMS). Passive antero-posterior knee laxity was measured with a KT1000 arthrometer during a maximal manual displacement test. Medial gastrocnemius activity on the injured side of ACLD participants demonstrated significantly prolonged activation in preparation to hop, minimal muscle inactivity prior to take-off, and increased duration of overall muscle activity when compared to the uninjured side and control subjects (p<0.05). Significant positive correlations were found between passive knee joint laxity and prolonged activation prior to knee bend. RMS of the muscle signal was not significantly different between limbs. Overall, MG on the ACLD side demonstrated longer activation, with minimal rest during the hop test, which may be an attempt to maintain knee stability. Furthermore, the strong relationship between knee laxity and prolonged muscle activation suggests that individuals with a loss of knee stability are more reliant on active control of the gastrocnemius muscle.

Human movement variability, nonlinear dynamics, and pathology: is there a connection?

Fields studying movement generation, including robotics, psychology, cognitive science, and neuroscience utilize concepts and tools related to the pervasiveness of variability in biological systems. The concept of variability and the measures for nonlinear dynamics used to evaluate this concept open new vistas for research in movement dysfunction of many types. This review describes innovations in the exploration of variability and their potential importance in understanding human movement. Far from being a source of error, evidence supports the presence of an optimal state of variability for healthy and functional movement. This variability has a particular organization and is characterized by a chaotic structure. Deviations from this state can lead to biological systems that are either overly rigid and robotic or noisy and unstable. Both situations result in systems that are less adaptable to perturbations, such as those associated with unhealthy pathological states or absence of skillfulness.

Different knee joint loading patterns in ACL deficient copers and non-copers during walking

PURPOSE

Rupture of the anterior cruciate ligament (ACL) causes changes in the walking pattern. ACL deficient subjects classified as copers and non-copers have been observed to adopt different post-injury walking patterns. How these different patterns affect the knee compression and shear forces is unresolved. Thus, the aim of the present study was to investigate how different walking patterns observed between copers, non-copers, and controls affect the knee compression and shear forces during walking.

METHODS

Three-dimensional gait analyses were performed in copers (n = 9), non-copers (n = 10), and control subjects (n =19). The net knee joint moment, knee joint reaction forces, and the sagittal knee joint angle were input parameters to a biomechanical model that assessed the knee compression and shear forces.

RESULTS

The results showed that the non-copers walked with significantly reduced knee compression and shear forces than the controls. The overall knee compression force pattern was similar between the copers and controls, although this variable was significantly increased at heel strike in the copers compared to both non-copers and controls. The peak shear force was significantly dependent on the peak knee extensor moment. This covariance was significantly different between groups meaning that at a given knee extensor moment the shear force was significantly reduced in the copers compared to controls.

CONCLUSION

The different knee joint loading patterns observed between non-copers and copers reflected the different walking strategies adopted by these groups, which may have implications for the knee joint stability. The strategy adopted by the copers may resemble an effective way to stabilize the knee joint during walking after an ACL rupture and that the knee kinematics may play a key role for this strategy. It is clinically relevant to investigate if gait retraining would enable non-copers to walk as copers and thereby improve their knee joint stability.

Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sport

BACKGROUND

Athletes who return to sport participation after anterior cruciate ligament reconstruction (ACLR) have a higher risk of a second anterior cruciate ligament injury (either reinjury or contralateral injury) compared with non-anterior cruciate ligament-injured athletes.

HYPOTHESES

Prospective measures of neuromuscular control and postural stability after ACLR will predict relative increased risk for a second anterior cruciate ligament injury.

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

Fifty-six athletes underwent a prospective biomechanical screening after ACLR using 3-dimensional motion analysis during a drop vertical jump maneuver and postural stability assessment before return to pivoting and cutting sports. After the initial test session, each subject was followed for 12 months for occurrence of a second anterior cruciate ligament injury. Lower extremity joint kinematics, kinetics, and postural stability were assessed and analyzed. Analysis of variance and logistic regression were used to identify predictors of a second anterior cruciate ligament injury.

RESULTS

Thirteen athletes suffered a subsequent second anterior cruciate ligament injury. Transverse plane hip kinetics and frontal plane knee kinematics during landing, sagittal plane knee moments at landing, and deficits in postural stability predicted a second injury in this population (C statistic = 0.94) with excellent sensitivity (0.92) and specificity (0.88). Specific predictive parameters included an increase in total frontal plane (valgus) movement, greater asymmetry in internal knee extensor moment at initial contact, and a deficit in single-leg postural stability of the involved limb, as measured by the Biodex stability system. Hip rotation moment independently predicted second anterior cruciate ligament injury (C = 0.81) with high sensitivity (0.77) and specificity (0.81).

CONCLUSION

Altered neuromuscular control of the hip and knee during a dynamic landing task and postural stability deficits after ACLR are predictors of a second anterior cruciate ligament injury after an athlete is released to return to sport.

Effect of knee flexion angle on ground reaction forces, knee moments and muscle co-contraction during an impact-like deceleration landing: implications for the non-contact mechanism of ACL injury

Investigating landing kinetics and neuromuscular control strategies during rapid deceleration movements is a prerequisite to understanding the non-contact mechanism of ACL injury. The purpose of this study was to quantify the effect of knee flexion angle on ground reaction forces, net knee joint moments, muscle co-contraction and lower extremity muscles during an impact-like, deceleration task. Ground reaction forces and knee joint moments were determined from video and force plate records of 10 healthy male subjects performing rapid deceleration single leg landings from a 10.5 cm height with different degrees of knee flexion at landing. Muscle co-contraction was based on muscle moments calculated from an EMG-to-moment processing model. Ground reaction forces and co-contraction indices decreased while knee extensor moments increased significantly with increased degrees of knee flexion at landing (all p<0.005). Higher ground reaction forces when landing in an extended knee position suggests they are a contributing factor in non-contact ACL injuries. Increased knee extensor moments and less co-contraction with flexed knee landings suggest that quadriceps overload may not be the primary cause of non-contact ACL injuries. The results bring into question the counterbalancing role of the hamstrings during dynamic movements. The soleus may be a valuable synergist stabilizing the tibia against anterior translation at landing. Movement strategies that lessen the propagation of reaction forces up the kinetic chain may help prevent non-contact ACL injuries. The relative interaction of all involved thigh and lower leg muscles, not just the quadriceps and hamstrings should be considered when interpreting non-contact ACL injury mechanisms.

The long-term effect of 2 postoperative rehabilitation programs after anterior cruciate ligament reconstruction: a randomized controlled clinical trial with 2 years of follow-up

BACKGROUND

There is no consensus regarding the optimal postoperative rehabilitation program after anterior cruciate ligament (ACL) reconstruction.

PURPOSE

The purpose of this study was to examine the long-term outcome of a 6-month neuromuscular exercise (NE) training program versus a traditional strength exercise (SE) training program after ACL reconstruction.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Seventy-four patients were randomly assigned to either a NE program or a SE program and tested preoperatively and at 6 months, 1 year, and 2 years after ACL reconstruction. Outcome measurements were as follows: Cincinnati knee score, visual analog scale for pain and global function, Short Form 36, functional knee tests, and isokinetic muscle strength tests.

RESULTS

There were no significant differences between the NE and SE programs 1 and 2 years after ACL reconstruction for the primary outcome measurement (Cincinnati knee score). There were significantly improved knee function (global function) and reduced pain during activity for the NE group, compared with the SE group, and significantly improved hamstring muscle strength for the SE group, compared with the NE group, 2 years after ACL reconstruction.

CONCLUSION

On the basis of these results, a postoperative program combining both NE and SE should be included after ACL reconstruction to improve knee function.

Periarticular muscle stimulation controls anterior tibial laxity after experimental ACL section: an experimental study

BACKGROUND AND PURPOSE

Besides current strategies to treat potentially disabling anterior cruciate ligament (ACL) injury, a new and innovative approach was designed based on electrical stimulation of the muscle to prevent unwanted displacement of the tibia relative to the femur. Our aim was to measure muscular strain and anterior tibial translation (ATT) in a controlled study using an animal model of ACL-deficient knee undergoing muscular electric stimulation.

METHODS

Seventeen cat knees under tibial anterior traction of 24.5 N were studied before and after ACL transection. Muscular fiber length variation was obtained by ultrasonomicrometry and ATT by video recordings at the beginning, during, and at the end of the movement. Square pulses of 0.2 ms with 5 V were applied in trains of 500, 100, and 20 ms simultaneously to both the quadriceps and hamstrings before and immediately after traction.

RESULTS

Electric stimulation of ACL-deficient knees normalized muscular strain to values of control knees. An increased resistance to muscular lengthening was observed in stimulated knees. Stimulation before traction maintained similar ATT than control knees during the subsequent traction.

DISCUSSION

Electric muscular stimulation in the ACL-deficient knee provoked periarticular muscle contraction, controlling ATT when time-adjusted stimulus (before traction) was used. This suggested that artificially inducing the muscular response could help to control anterior knee laxity after ACL injury.

Perturbation training prior to ACL reconstruction improves gait asymmetries in non-copers

We investigated whether preoperative perturbation training would help anterior cruciate ligament (ACL) deficient individuals who complain of knee instability ("non-copers") regain quadriceps strength and walk normally after ACL reconstruction. Nineteen non-copers with acute ACL injury were randomly assigned into a perturbation group (PERT) or a strengthening group (STR). The PERT group received specialized neuromuscular training and progressive quadriceps strength training, whereas the STR group received progressive quadriceps strength training only. We compared quadriceps strength indexes and knee excursions during the mid-stance phase of gait preoperatively to data collected 6 months after ACL reconstruction. Analyses of Variance with repeated measures (time/limb) were conducted to compare quadriceps strength index values over time (time x group) and differences in knee excursions in limbs between groups over time (limb x time x group). If significance was found, post hoc analyses were performed using paired and independent t-tests. Quadriceps strength indexes before intervention (Pert: 87.2%; Str: 75.8%) improved 6 months after ACL reconstruction in both groups (Pert: 97.1%; Str: 94.4%). Non-copers who received perturbation training preoperatively had no differences in knee excursions between their limbs 6 months after ACL reconstruction (p = 0.14), whereas those who received just strength training continued to have smaller knee excursions during the mid-stance phase of gait (p = 0.007). Non-copers strength and knee excursions were more symmetrical 6 months postoperatively in the group that received perturbation training and progressive quadriceps strength training than the group who received strength training alone.

Rehabilitation after anterior cruciate ligament injury influences joint loading during walking but not hopping

OBJECTIVE

The purpose of this study was to identify changes in clinical outcome and lower extremity biomechanics during walking and hopping in ACL-injured subjects before and after a 20-session neuromuscular and strength training programme.

STUDY DESIGN

Pre and post experimental design.

SETTING

Outpatient clinic, primary care.

PATIENTS

32 subjects with unilateral ACL injury, mean 60 (SD 35) days after injury, with a mean age of 26.2 (5.4) years.

INTERVENTION

The rehabilitation programme consisted of neuromuscular and strength exercises.

MAIN OUTCOME MEASUREMENTS

Outcome measurements assessed before and after a 20-session rehabilitation programme were: self-assessment questionnaires (KOS-ADL, IKDC2000, Global function), four single-leg hop tests, and isokinetic muscle strength tests. Lower extremity kinematics and kinetics were captured during the stance phase of gait and landing after a single leg hop, synchronised with three force plates.

RESULTS

These ACL-injured individuals significantly improved their clinical outcome after rehabilitation. Gait analysis disclosed a significantly improved knee extension moment after rehabilitation, but no change in hip or knee excursions. During landing after hop no change in knee excursion or knee moment was recorded.

CONCLUSION

After rehabilitation the ACL-injured subjects showed a significantly improved clinical outcome, but lower extremity biomechanics were still significantly impaired during both walking and hopping. The rehabilitation programme influenced knee joint loading during walking, but not during hopping. Longer rehabilitation should be considered before ACL-injured individuals return to jumping activities.

Isokinetic Dynamometry in Anterior Cruciate Ligament Injury and Reconstruction

The use of isokinetic dynamometry has often been criticised based on the face-validity argument that isokinetic movements poorly resemble the everyday multi-segmented, dynamic activities of human movements. In the anterior cruciate ligament (ACL) reconstruction or deficiency population where muscle deficits are ubiquitous, this review paper has made a case for using isokinetic dynamometry to isolate and quantify these deficits in a safe and controlled manner. More importantly, the usefulness of isokinetic dynamometry, as applied in individuals with ACL reconstruction or deficiency, is attested by its established known-group and convergent validity. Known-group validity is demonstrated by the extent to which a given isokinetic measure is able to identify individuals who could and could not resume pre-morbid athletic or strenuous activities with minimal functional limitations following an ACL injury. Convergent validity is demonstrated by the extent to which a given isokinetic measure closely associates with self-report measures of knee function in individuals with ACL reconstruction. A basic understanding of the measurement properties of isokinetic dynamometry will guide the clinicians in providing reasoned interventions and advancing the clinical care of their clients. Key words: Biomechanics, Knee, Validity

Neuromuscular training versus strength training during first 6 months after anterior cruciate ligament reconstruction: a randomized clinical trial

BACKGROUND AND PURPOSE

The purpose of this study was to determine the effect of a 6-month neuromuscular training (NT) program versus a traditional strength training (ST) program following anterior cruciate ligament (ACL) reconstruction.

SUBJECTS

Seventy-four subjects with ACL reconstruction participated in the study.

METHODS

The study was a randomized, single-blinded, controlled trial. The NT and ST groups were tested preoperatively and at 3 and 6 months. The main outcome measure was the Cincinnati Knee Score. Secondary outcome measures were visual analog scales (VASs) for pain and function, the 36-Item Short-Form Health Survey (SF-36), hop tests, isokinetic muscle strength, proprioception, and static and dynamic balance tests.

RESULTS

The NT group demonstrated significantly improved Cincinnati Knee Scores and VAS scores for global knee function compared with the ST group at the 6-month follow-up. There were no significant differences between the groups for the other outcome measures (ie, hop, balance, proprioception, and muscle strength tests).

DISCUSSION AND CONCLUSION

The results of this study suggest that exercises included in the NT program should be part of the rehabilitation program following ACL reconstruction.

Influence of anticipation on movement patterns in subjects with ACL deficiency classified as noncopers

STUDY DESIGN

Two-factor, mixed experimental design.

OBJECTIVES

To compare movement patterns of subjects who are anterior cruciate ligament (ACL) deficient and classified as noncopers to controls during early stance of anticipated and unanticipated straight and cutting tasks.

BACKGROUND

Altered neuromuscular control of subjects that are ACL deficient and noncoper theoretically influences movement patterns during unanticipated tasks.

METHODS AND MEASURES

The study included 16 subjects who are ACL deficient, classified as noncopers, and 20 healthy controls. Data were collected using an Optotrak Motion Analysis System and force plate integrated with Motion Monitor Software to generate knee joint angles, moments, and power. Each testing session included anticipated tasks, straight walking task (ST), and 45 degrees side-step cutting tasks (SSC), followed by a set of unexpected straight walking (STU) and unexpected sidestep cutting (SSCU) tasks in a random order. For all tasks speed was maintained at 2 m/s. Peak knee angle, moment, and power variables during early stance were compared using 2-way mixed-effects ANOVA models.

RESULTS

For both the straight and sidestep tasks, the noncoper group did not show a dependence on whether the task was anticipated or unanticipated (group-by-condition interaction) for the knee angle (straight, P = .067; side-step cutting, P = .103), moment (straight, P = .079; side-step cutting, P = .996), and powers (straight, P = .181; side-step cutting, P = .183) during the loading response phase. However, during both straight and side-step cutting tasks, the subjects in the noncoper group used significantly lower knee flexion angles (straight, P = .002; side-step cutting, P = .019), knee moments (straight, P = .005; side-step cutting, P < .001), and knee powers (straight, P = .013; side-step cutting, P <.001).

CONCLUSIONS

This study suggests subjects that are ACL deficient and classified as noncopers use a common abnormal movement pattern of lower knee extensor loading even during unanticipated tasks.

Análise da freqüência mediana do sinal eletromiográfico de indivíduos com lesão do ligamento cruzado anterior em exercícios isométricos de cadeia cinética aberta e fechada

Indivíduos com lesão do ligamento cruzado anterior (LCA) possuem importantes alterações funcionais na musculatura periarticular do joelho. Sendo assim, é de suma importância caracterizar tais alterações, bem como enfatizar um efetivo protocolo de reabilitação para esses indivíduos, com conseqüente retorno às atividades físicas. O objetivo deste estudo foi analisar o comportamento da freqüência mediana (Fmed) em indivíduos com lesão do LCA durante contrações isométricas em exercícios de cadeia cinética aberta (CCA) e fechada (CCF). Entre lesados e não lesados, 40 indivíduos realizaram a extensão do joelho através da contração isométrica voluntária máxima (CIVM) nos aparelhos leg extension e leg press a 30°, 60° e 90° de flexão do joelho. Os resultados revelaram valores da Fmed menores para indivíduos com lesão do LCA quando comparados com o membro contralateral e grupo controle em CCA (p < 0,05). Já exercícios em CCF não apresentaram diferença estatística significativa (p > 0,05) na comparação entre os grupos, não evidenciando esse tipo de lesão. Portanto, a Fmed parece ser uma ferramenta eletromiográfica eficaz na caracterização da lesão crônica do LCA. Além disso, exercícios em CCF parecem ser os mais indicados para a reabilitação desses indivíduos.

Tibial Rotation in Anterior Cruciate Ligament (ACL)-Deficient and ACL-Reconstructed Knees

Excessive tibial rotation has been documented in anterior cruciate ligament (ACL) deficiency during walking. ACL reconstruction has been unable to correct this abnormality in activities that are more demanding than walking and involve both anterior and rotational loading of the knee. These findings persist regardless of graft selection for the ACL reconstruction (bone-patellar tendon-bone or semitendinosus gracilis). Based on this research work, we propose a theoretical perspective for the development of osteoarthritis in both the ACL-deficient and the ACL-reconstructed knee. We propose that excessive tibial rotation will lead to abnormal loading of the cartilage areas that are not commonly loaded in the healthy knee. Over time, this abnormal loading will lead to osteoarthritis. We hypothesise that the development of new surgical procedures and grafts, such as a more horizontally oriented femoral tunnel or a double-bundle ACL reconstruction, could possibly restore tibial rotation to normal levels and prevent future knee pathology. However, in vivo gait analysis studies are needed to examine the effects of these surgical procedures on tibial rotation. Prospective in vivo and in vitro studies are also necessary to verify or refute our theoretical proposition for the development of osteoarthritis.

Muscular compensation and lesion of the anterior cruciate ligament: contribution of the soleus muscle during recovery from a forward fall

BACKGROUND

Knee stability following an anterior cruciate ligament lesion has been widely studied. Only recent studies focused on the contribution of the soleus muscle. Our purpose was to characterize the dynamic and muscular activity of balance recovery in healthy subjects and patients with an anterior cruciate ligament rupture. The role of the soleus was investigated in the ipsilateral compensation developed to stabilize the knee and in the contralateral compensation to recover balance.

METHODS

Twelve anterior cruciate ligament deficient patients, ten anterior cruciate ligament repaired patients and 14 control subjects were recorded during a forward fall involving stepping to recover balance.

FINDINGS

The dynamic of the centre of gravity remained normal when compared to the control group regardless of the treatment, suggesting an adapted compensation to knee instability in this situation. A bilateral increase in soleus activity was related to an increased duration in the balance recovery process in all patients. Patients used one of two strategies to recover balance regardless of the treatment: reducing the step length, involving an early recruitment of the soleus before heel contact, or anticipating braking with a similar step length requiring a predominant activity of the hamstrings.

INTERPRETATIONS

These results suggest that bilateral activity of the soleus is involved to compensate for instability and highlight the contribution of the soleus to rehabilitation after an anterior cruciate ligament lesion, not only as a compensatory muscle acting at the knee level but also at a higher level in the bilateral control of stance.

Anterior cruciate ligament injuries in female athletes: Part 1, mechanisms and risk factors

The mechanism underlying gender disparity in anterior cruciate ligament injury risk is likely multifactorial in nature. Several theories have been proposed to explain the mechanisms underlying the gender difference in anterior cruciate ligament injury rates. These theories include the intrinsic variables of anatomical, hormonal, neuromuscular, and biomechanical differences between genders and extrinsic variables. Identification of both extrinsic and intrinsic risk factors associated with the anterior cruciate ligament injury mechanism may provide direction for targeted prophylactic treatment to high-risk individuals.

Measurement and Evaluation of Dynamic Joint Stability of the Knee and Ankle After Injury

Injuries to the lower extremity, specifically the knee and ankle joints of the human body can occur in any athletic event and are most prevalent in sports requiring cutting and jumping manoeuvres. These joints are forced to rely on the dynamic restraints to maintain joint stability, due to the lack of bony congruence and the inability of the static restraints to handle the forces generated during functional tasks. Numerous variables (proprioception, postural control, electromyography, kinetics/kinematics, dynamic stability protocols) have been measured to better understand how the body maintains joint stability during a wide range of activities from static standing to dynamic cutting or landing from a jump. While the importance of dynamic restraints is not questioned, a recent impetus to conduct more functional or sport-specific testing has emerged and placed a great deal of emphasis on dynamic joint stability and how it is affected by lower extremity injuries. Evidence suggests that surgery and aggressive rehabilitation will not necessarily restore the deficits in dynamic joint stability caused by injury to the anterior cruciate ligament or lateral ankle ligaments. In today's athletic society, there is a major push to return athletes to play as quickly as possible. However, the ramifications of those decisions have not been fully grasped. If an athlete is not fully recovered, a quick return to play could start a vicious cycle of chronic injuries or permanent disability.

Elucidation of a potentially destabilizing control strategy in ACL deficient non-copers

PURPOSE

The purpose was to differentiate the dynamic knee stabilization strategies of potential copers (individuals who have the potential to compensate for the absence of an ACL without episodes of giving way after return to pre-injury activities) and non-copers (those who have knee instability following ACL rupture with return to pre-injury activities).

METHODS

Twenty subjects with ACL rupture were assigned to potential coper (n=10) and non-coper (n=10) groups via a screening examination. Ten active people without lower extremity injury were also tested. Knee angle, tibial position and muscle activity data were collected while subjects stood in unilateral stance on a platform that moved horizontally in an anterior direction. Analysis included the preparation for platform movement; and monosynaptic, intermediate reflex and voluntary response intervals after platform movement.

RESULTS

Non-copers showed greater knee flexion than uninjured subjects, and had a posterior tibial position and altered hamstring recruitment compared to the other groups. Potential copers demonstrated greater medial quadriceps activity while maintaining knee kinematics similar to uninjured subjects. Both potential copers and non-copers had greater co-contraction between medial hamstrings and quadriceps than uninjured subjects. All excitatory muscle activation occurred in the intermediate reflex interval.

DISCUSSION AND CONCLUSIONS

Non-copers displayed aberrant muscle recruitment that may contribute to knee instability. Potential copers maintained normal tibial position using a strategy that permits quadriceps activation without excessive anterior tibial translation. Muscle recruitment in the intermediate reflex interval suggests neuromuscular training may influence the strategies.

Evidence for differential control of tibial position in perturbed unilateral stance after acute ACL rupture

Functional outcomes in anterior cruciate ligament-deficient "potential copers" and "non-copers" may be related to their knee stabilization strategies. Therefore, the purpose of this study was to differentiate dynamic knee stabilization strategies of potential copers and non-copers through analysis of sagittal plane knee angle and tibia position during disturbed and undisturbed unilateral standing. Ten uninjured potential coper and non-coper subjects stood in unilateral stance on a platform that translated anteriorly, posteriorly and laterally. Knee angle and tibia position with reference to the femur were calculated before and after platform movement. During perturbation trials, potential copers maintained kinematics that were similar to uninjured subjects across conditions. Conversely, non-copers stood with greater knee flexion than uninjured subjects and a tibia position that was more posterior than the other groups. Both non-copers and potential copers demonstrated small changes in tibia position following platform movement, but direction of movement was not similar. The similarities between the knee kinematics of potential copers and uninjured subjects suggest that potential copers compensated well from their injury by utilizing analogous dynamic knee stabilization strategies. In comparison to the other groups, by keeping the knee in greater flexion and the tibia in a more posterior position, non-copers appear to constrain the tibia in response to a challenging task, which is consistent with a "stiffening strategy". Based on the poor functional outcomes of non-copers, a stiffening strategy does not lead to dynamic knee stability, and the strategy may increase compressive forces which could contribute to or exacerbate articular cartilage degeneration.

Differences in normal and perturbed walking kinematics between male and female athletes

OBJECTIVE

To identify differences in lower extremity kinematic movement patterns between genders during walking through the application of an expected perturbation.

DESIGN

Randomized limb kinematics were compared between healthy active males and females.

BACKGROUND

Lower extremity kinematics during jump landing and cutting have been implicated as a potential source of the discrepancy in anterior cruciate ligament injury rates between genders. Kinematic differences between genders have been identified during tasks that are not provocative of anterior cruciate ligament injury but do result in increased ligament strain. Repetition of movement patterns that increase anterior cruciate ligament strain may increase the likelihood they will be reproduced during athletic tasks that produce force loads that exceed anterior cruciate ligament tensile strength.

METHODS

Twenty subjects (10 women, 10 men) classified as a level I or II athlete underwent motion analyses while performing self-paced walking trials. Five trials were undisturbed, and five each with a platform translating either laterally or anteriorly at heel contact. Sagittal, frontal, and transverse hip angles as well as sagittal and frontal knee angles were collected during stance.

RESULTS

Excursions in the frontal and transverse planes were greater at the hip and knee for females compared to males in each walking condition. The rate of these excursions also occurred more rapidly for females than males. There was no difference for joint angles at initial contact between genders, and there was no difference in the amount of sagittal plane excursion for the hip and knee when comparing genders.

CONCLUSIONS

Females demonstrate characteristics during both normal and perturbed gait that may potentially contribute to increased anterior cruciate ligament strain. Repetition of these potentially harmful movement patterns during provocative athletic maneuvers may lead to anterior cruciate ligament injury.

RELEVANCE

Females exhibit lower extremity kinematic patterns that differ from males. Female kinematic patterns may contribute to an increased risk for anterior cruciate ligament injury.