Biomechanical evidence supporting a differential response to acute ACL injury

Brain functional connectivity alterations in patients with anterior cruciate ligament injury

Recent advancements in neuroimaging have illustrated that anterior cruciate ligament (ACL) injuries could impact the central nervous system (CNS), causing neuroplastic changes in the brain beyond the traditionally understood biomechanical consequences. While most of previous functional magnetic resonance imaging (fMRI) studies have focused on localized cortical activity changes post-injury, emerging research has suggested disruptions in functional connectivity across the brain. However, these prior investigations, albeit pioneering, have been constrained by two limitations: a reliance on small-sample participant cohorts, often limited to two to three patients, potentially limiting the generalizability of findings, and an adherence to region of interest based analysis, which may overlook broader network interactions. To address these limitations, our study employed resting-state fMRI to assess whole-brain functional connectivity in 15 ACL-injured patients, comparing them to matched controls using two distinct network analysis methods. Using Network-Based Statistics, we identified widespread reductions in connectivity that spanned across multiple brain regions. Further modular connectivity analysis showed significant decreases in inter-modular connectivity between the sensorimotor and cerebellar modules, and intra-modular connectivity within the default-mode network in ACL-injured patients. Our results thus highlight a shift from localized disruptions to network-wide dysfunctions, suggesting that ACL injuries induce widespread CNS changes. This enhanced understanding has the potential to stimulate the development of strategies aiming to restore functional connectivity and improve recovery outcomes.

What Are the Criteria for an Acute Form of Anterior Cruciate Ligament Tear for the Severity of the Process by Gait Analysis Data?

PURPOSE

There is still controversy over the criteria for acute ACL tear. In this paper, knee joint function and walking were considered possible ones.

METHOD

The study included 21 subjects with acute ACL tear and 20 healthy volunteers as a control group. Biomechanical gait analysis was performed using the inertial sensor system including EMG recording. All subjects (but for controls) were divided into two groups: Group 1-"up to 4 weeks" and Group 2-"from 4 weeks to 3 months".

RESULTS

Temporal gait parameters in subjects from Group 1 demonstrate the asymmetry of 4% and more in terms of the gait cycle with a decrease in the affected limb, and are within normal range in Group 2. The amplitudes at the hip and knee joints in the affected limb are reduced which is especially pronounced in Group 1 (2-4 and 6-10 degrees, respectively). The affected knee joint shows a decrease in the range of motion by up to 5 degrees in the first half of the stance phase and flexion by less than 40 degrees in the swing phase. The tibialis anterior and quadriceps femoris muscle function is decreased in the affected limb only in Group 1 (72% and 78% from normal, respectively).

CONCLUSIONS

The severity of the condition after an ACL tear is largely determined by functional changes. The time factor is of secondary importance.

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.

Influences of Partial Anterior Cruciate Ligament Injury On Anterior Cruciate Ligament Tensional Force and Kinematic Stability During Walking

Injuries in the anterior cruciate ligament (ACL), including partial tear and lengthening of the ACL, change the dynamic function of the knee. However, there is a lack of information on the effect of ACL partial tear on knee kinematics during walking. This study aimed to investigate the effects of different levels of ACL injuries on the knee stability and ACL tensional force to identify the critical injury level. Motion data of five normal subjects were acquired along with the ground reaction force. A knee model with 14 ligaments was developed using cadaveric specimen data. The initial length and stiffness of the ACL were changed to develop ACL-injured knee models. Musculoskeletal simulations of the knee models were performed using the measured gait data. The average tibial anterior translation increased significantly by 2.6 ± 0.7 mm when the ACL stiffness decreased to 25% of its original stiffness. The average tibial anterior translation increased significantly by 2.6 ± 0.3 mm at an increase in initial length of 10%. The knee with partial ACL tear had a non-linear decrease in ACL forces owing to the increase in the level of ACL injury, while the knee with ACL lengthening had linear decreased ACL forces. The partial tear of the ACL caused translational instability, while the complete tear caused both rotational and translational instabilities during the musculoskeletal walking simulation. This study presents the effects of partial ACL injuries on joint kinematics and ACL tensional force during the dynamic motion of walking.

The correlation between posterior tibial slope and dynamic anterior tibial translation and dynamic range of tibial rotation

Purpose

The amount of passive anterior tibial translation (ATT) is known to be correlated to the amount of posterior tibial slope (PTS) in both anterior cruciate ligament-deficient and reconstructed knees. Slope-altering osteotomies are advised when graft failure after anterior cruciate ligament (ACL) reconstruction occurs in the presence of high PTS. This recommendation is based on studies neglecting the influence of muscle activation. On the other hand, if dynamic range of tibial rotation (rTR) is related to the amount of PTS, a “simple” anterior closing-wedge osteotomy might not be sufficient to control for tibial rotation. The purpose of this study was to evaluate the correlation between the amount of PTS and dynamic ATT and tibial rotation during high demanding activities, both before and after ACL reconstruction. We hypothesized that both ATT and rTR are strongly correlated to the amount of PTS.

Methods

Ten subjects were studied both within three months after ACL injury and one year after ACL reconstruction. Dynamic ATT and dynamic rTR were measured using a motion-capture system during level walking, during a single-leg hop for distance and during a side jump. Both medial and lateral PTS were measured on MRI. A difference between medial and lateral PTS was calculated and referred to as Δ PTS. Spearman’s correlation coefficients were calculated for the correlation between medial PTS, lateral PTS and Δ PTS and ATT and between medial PTS, lateral PTS and Δ PTS and rTR.

Results

Little (if any) to weak correlations were found between medial, lateral and Δ PTS and dynamic ATT both before and after ACL reconstruction. On the other hand, a moderate-to-strong correlation was found between medial PTS, lateral PTS and Δ PTS and dynamic rTR one year after ACL reconstruction.

Conclusion

During high-demand tasks, dynamic ATT is not correlated to PTS. A compensation mechanism may be responsible for the difference between passive and dynamic ATT in terms of the correlation to PTS. A moderate-to-strong correlation between amount of PTS and rTR indicates that such a compensation mechanism may fall short in correcting for rTR. These findings warrant prudence in the use of a pure anterior closing wedge osteotomy in ACL reconstruction.

Trial registration

Netherlands Trial Register, Trial 7686. Registered 16 April 2016—Retrospectively registered.

Level of evidence

Level 2, prospective cohort study

Operative and nonoperative management of anterior cruciate ligament injury: Differences in gait biomechanics at 5 years

Gait biomechanics after anterior cruciate ligament (ACL) injury are associated with functional outcomes and the development of posttraumatic knee osteoarthritis. However, biomechanical outcomes between patients treated nonoperatively compared with operatively are not well understood. The primary purpose of this study was to compare knee joint contact forces, angles, and moments during loading response of gait between individuals treated with operative compared with nonoperative management at 5 years after ACL injury. Forty athletes treated operatively and 17 athletes treated nonoperatively completed gait analysis at 5 years after ACL reconstruction or completion of nonoperative rehabilitation. Medial compartment joint contact forces were estimated using a previously validated, patient-specific electromyography-driven musculoskeletal model. Knee joint contact forces, angles, and moments were compared between the operative and nonoperative group using mixed model 2 × 2 analyses of variance. Peak medial compartment contact forces were larger in the involved limb of the nonoperative group (Op: 2.37 ± 0.47 BW, Non-Op: 3.03 ± 0.53 BW; effect size: 1.36). Peak external knee adduction moment was also larger in the involved limb of the nonoperative group (Op: 0.25 ± 0.08 Nm/kg·m, Non-Op: 0.32 ± 0.09 Nm/kg·m; effect size: 0.89). No differences in radiographic tibiofemoral osteoarthritis were present between the operative and nonoperative groups. Overall, participants treated nonoperatively walked with greater measures of medial compartment joint loading than those treated operatively, while sagittal plane group differences were not present. Statement of clinical relevance: The differences in medial knee joint loading at 5 years after operative and nonoperative management of ACL injury may have implications on the development of posttraumatic knee osteoarthritis.

FUNCTIONAL MEASURES DO NOT DIFFER IN LATE STAGE REHABILITATION AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION ACCORDING TO MECHANISM OF INJURY

Background

Anterior cruciate ligament injuries are among the most common knee injuries. Mechanism of injury is classified as contact or non-contact. The majority of anterior cruciate ligament ruptures occur through a non-contact mechanism of injury. Non-contact anterior cruciate ligament ruptures are associated with biomechanical and neuromuscular risk factors that can predispose athletes to injuries and may impact future function. Non-contact mechanism of injury may be preceded by poor dynamic knee stability and therefore those with a non-contact mechanism of injury may be prone to poor dynamic knee stability post-operatively. Understanding how mechanism of injury affects post-operative functional recovery may have clinical implications on rehabilitation.

Purpose

The purpose of this study was to determine if mechanism of injury influenced strength, functional performance, patient-reported outcome measures, and psychological outlook in athletes at four time points in the first two years following anterior cruciate ligament reconstruction.

Study Design

Secondary analysis of a clinical trial.

Methods

Seventy-nine athletes underwent functional testing at enrollment after impairment resolution. Quadriceps strength, hop testing, and patient-reported outcome measures were evaluated post-operatively at enrollment, following return-to-sport training and one year and two years after anterior cruciate ligament reconstruction. Participants were dichotomized by mechanism of injury (29 contact, 50 noncontact). Independent t-tests were used to compare differences between groups.

Results

There were no meaningful differences between contact and non-contact mechanism of injury in any variables at enrollment, post-training, one year, or two years after anterior cruciate ligament reconstruction.

Conclusion

Function did not differ according to mechanism of injury during late stage rehabilitation or one or two years after anterior cruciate ligament reconstruction.

Level of Evidence

III.

Recurrent patellar dislocations in adolescents result in decreased knee flexion during the entire gait cycle

PURPOSE

To evaluate the kinematics/kinetics of the ankle, knee, hip in the sagittal plane in adolescents with recurrent patellar dislocation in comparison to a healthy control.

METHODS

Case-control study. Eighty-eight knees (67 patients) with recurrent patellar dislocation (mean age 14.8 years ± 2.8 SD) were compared to 54 healthy knees (27 individuals, 14.9 years  ± 2.4 SD). Kinematics/kinetics of ankle, knee, hip, and pelvis were captured using 3D-gait analysis (VICON, 12 cameras, 200 Hz, Plug-in-Gait, two force plates). One cycle (100%) consisted of 51 data-points. The mean of six trials was computed.

RESULTS

The loading-response increased by 0.02 s ± 0.01SE (10.8%) with dislocations (0.98% of total gait, P < 0.01). The mid-stance-phase decreased equally (P < 0.01). Dislocation decreased knee flexion during the entire gait cycle (P < 0.01), with the largest difference during mid-stance (9.0° ± 7.2 SD vs. 18.5° ± 6.7 SD). Dislocation increased plantar-flexion during loading response 4.1° ± 0.4 SE with (P < 0.01), afterward, the dorsal-extension decreased 3.2° ± 0.3 SE, (P < 0.01). Dislocation decreased hip flexion during all phases (P < 0.01). Maximal difference: 7.5° ± 0.5 SE during mid-stance. 80% of all patients developed this gait pattern. Internal moments of the ankle increased, of the knee and hip decreased during the first part of stance.

CONCLUSION

Recurrent patellar dislocation decreases knee flexion during the loading-response and mid-stance phase. A decreased hip flexion and increased plantar-flexion, while adjusting internal moments, indicate a compensation mechanism.

LEVEL OF EVIDENCE

III.

Characterizing healthy knee symmetry using the finite helical axis and muscle power during open and closed chain tasks

Understanding healthy joint movement and muscle control, and injurious alterations, is important to determine musculoskeletal contributions to post-injury joint instabilities or altered dynamic joint function. The contralateral limb is often used as a point of reference to determine the effects of knee joint injury. However, it is currently difficult to interpret within subject variability between limbs as this is not well established in the healthy population. There is a continuing need to characterize healthy knee joint mechanics and neuromuscular control to determine the degree of symmetry within healthy individuals. The current study quantified limb symmetry in healthy individuals using the finite helical axis with a unique reference position (rFHA) and electromyography (EMG) approaches, for a closed-chain single leg squat (SLS) and an open-chain seated leg swing. Muscle power and FHA translation, orientation and dispersion were similar between limbs. However, the FHA was located significantly more anterior in the dominant limb relative to the contralateral during both tasks. These between-limb differences in FHA location could be attributed to differences in joint geometry and strength between limbs. This finding provides evidence that healthy knees have asymmetries which have implications for selection of control limbs in studies comparing conditions within and between individuals. Differences identified in dynamic joint function between tasks suggest that the SLS is useful for revealing joint asymmetries due to altered muscular control strategies, while the swing task is expected to highlight asymmetries in joint motion due to altered knee structures following injury.

Clinical and Biomechanical Efficacies of Mechanical Perturbation Training After Anterior Cruciate Ligament Rupture

CONTEXT

Manual perturbation training improves knee functional performance and mitigates abnormal gait in patients with anterior cruciate ligament (ACL) rupture. However, manual perturbation training is time- and labor-intensive for therapists.

OBJECTIVE

To investigate whether perturbation training administered using a mechanical device can provide effects similar to manual training on clinical measures and knee biomechanics after ACL rupture.

DESIGN

Prospective cohort (therapeutic) study. A 2 × 2 analysis of variance was used for statistical analysis.

SETTING

A clinical and biomechanical laboratory.

PATIENTS

Eighteen level I/II patients with acute ACL ruptures participated in this preliminary study.

INTERVENTION

Nine patients received mechanical perturbation training on an automated mechanical device (mechanical group), and 9 patients received manual perturbation training (manual group).

OUTCOME MEASURES

Patients completed performance-based testing (quadriceps strength and single-legged hop tests), patient-reported questionnaires (Knee Outcome Survey-Activities of Daily Living Scale, Global Rating Score, and International Knee Documentation Committee 2000), and 3-dimensional gait analysis before (pretesting) and after (posttesting) training.

RESULTS

There was no significant group-by-time interaction found for all measures (P ≥ .18). Main effects of time were found for International Knee Documentation Committee 2000 (pretesting: 69.10 [10.95], posttesting: 75.14 [7.19]), knee excursion during weight-acceptance (pretesting: 16.01° [3.99°]; posttesting: 17.28° [3.99°]) and midstance (pretesting: 14.78° [4.13°]; posttesting: 16.92° [4.53°]) and external knee-flexion moment (pretesting: 0.43 [0.11] N m/kg/m; posttesting: 0.48 [0.11] N m/kg/m) (P ≤ .04). After accounting for pretesting groups' differences, the mechanical group scored significantly higher on triple hops (mechanical: 96.73% [6.65%]; manual: 84.97% [6.83%]) and 6-m timed hops (mechanical: 102.07% [9.50%]; manual: 91.21 [9.42%]) (P ≤ .047) compared with manual group.

CONCLUSION

The clinical significance of this study is the mechanical perturbation training produced effects similar to manual training, with both training methods were equally  effective at improving patients' perception of knee function and increasing knee excursion and external flexion moment during walking after acute ACL rupture. Mechanical perturbation training is a potential treatment to improve patients' functional and biomechanical outcomes after ACL rupture.

Predicting post-operative functional ability from pre-operative measures in ACL-injured individuals

PURPOSE

This study aimed to quantify the relationship between objective and subjective measures of functional ability and determine if measures in the deficient (ACLd) state were correlated to, and capable of predicting a patient's objective and subjective measures in the reconstructed (ACLr) state.

METHODS

Twenty ACL-injured participants completed hop and side cut movements prior to and 10 months post-reconstruction. Their subjective measures (Tegner, Lysholm, IKDC, KOOS, and KNEEs) were related to objective measures of functional ability (peak knee flexion, peak knee extensor moment, stiffness, knee joint center excursion (KJCE), and knee joint center boundary). Correlations were used to determine relationships between variables whereas regressions were used to identify ACLd score's predictive ability of an ACLr score.

RESULTS

Relationships between objective and subjective measures were task and ACL status dependent with KJCE and stiffness most commonly being related to subjective scores. The greatest correlation was between knee stiffness and Tegner in the ACLr group during the side cut (r = 0.69). Peak knee flexion angle (adj. R²  = 0.4-0.66) was the best objective predictor between ACLd and ACLr states while KOOS-ADL had the strongest correlations (r = 0.70-0.77) and Tegner had the greatest predictive power (odds ratio: 1.46-1.86) between states in both tasks.

CONCLUSION

Objective measures show a wide range of correlation to subjective measures with some being quite strong. Furthermore, objective measures in the ACLd state are more correlated and more often capable of predicting ACLr scores than the subjective measures of functional ability.

Sagittal and Frontal Plane Gait Initiation Kinetics in Healthy, Young Subjects

The study purposes were to record the lower extremity sagittal and frontal joint moments and powers during gait initiation (GI); evaluate GI support moments in both planes; and analyze planar energy patterns in a group of 15 healthy, young adults. 3D motion and ground reaction force data were used to calculate support moments (SM) and joint moments and powers as well as center of mass (COM) kinematics. STEP1 had no visible SM. It appeared in STEP2 and, by STEP3, resembled that seen in steady-state gait. Joint moments demonstrated a similar development towards typical patterns over the three steps. Correlations of moment data between planes indicate that the frontal plane component of the SM acts to keep the COM centered. It is suggested that Winter’s 1980 SM definition be extended to include both a support (sagittal) component and a centering (frontal) component. Energy was calculated for individual bursts of joint powers in both planes and each step had characteristic patterns in each plane, with patterns resembling steady-state gait appearing in the third step. Test-retest reliability (ICC range: 0.796 – 0.945) was high with CV values in the sagittal plane (36.6 – 37.5%) being less variable than in the frontal plane (39.0 – 82.0%). COM kinematics revealed that acceleration peaked in STEP2 (ICC range: 0.950 – 0.980, CV < 20.0%). Data supported hypotheses regarding the dominance of the frontal plane power in STEP1, with substantial power coming from hip flexors. As well, powers in the sagittal plane were generally of larger magnitude than in the frontal plane.

Assessment of objective dynamic knee joint control in anterior cruciate ligament deficient and reconstructed individuals

BACKGROUND

There is a lack of objective dynamic knee joint control measures that can be related to the status of the anterior cruciate ligament (ACL). The purpose of this study was to introduce two novel measures and apply a third to determine how dynamic knee joint control changes in relation to ACL status during dynamic movements.

METHODS

Twenty patients (13 male) were tested pre- (ACLd) and 10-months post- (ACLr) ACL reconstructive surgery and matched to an uninjured participant (CON). Kinetic and kinematic data were synchronously recorded with a force platform and motion capture system. Three objective control measures including dynamic angular stiffness, knee joint center excursion (KJCE), and knee joint center boundary (KJCB) were assessed for each participant when completing the side cut and hop tasks.

RESULTS

During the side cut, stiffness was found to be significantly lower in ACLd (0.06 ± 0.01 Nm/kg/°) and ACLr (0.07 ± 0.02 Nm/kg/°) compared to CON (0.08 ± 0.02 Nm/kg/°), while there were no differences in stiffness during the hop. No significant differences were observed in the KJCE during the side cut, while KJCE was significantly greater (p = 0.006) during the hop in CON compared to the ACLd. There were no differences in KJCB.

CONCLUSIONS

These high-functioning ACL injured in both ACLd and ACLr phases, aside from reduced stiffness, were able to complete both tasks with similar dynamic control as the CON. Although improvements in self-perceived control between ACLd and ACLr have been observed, this lack of improvement in objective control demonstrates a gap between a patient's self-efficacy and the level of control.

Electronically augmented gait abnormality assessment following lower extremity trauma

Background:

Objective evaluation of patient outcomes has become an essential component of patient management. Along with patient-reported outcomes, performance-based measures (PBMs) such as gait analysis are an important part of this evaluation. The purpose of this study was to evaluate the validity of utilizing a wearable inertial measurement unit (IMU) in an outpatient clinic setting to assess its ability to provide clinically relevant data in patients with altered gait resulting from lower extremity trauma.

Methods:

Five orthopaedic trauma patients with varying degrees of gait pathologies were compared to 5 healthy control subjects. Kinematic data were simultaneously recorded by the IMU and a gold standard Vicon video motion analysis system (Vicon Motion Systems Ltd, Oxford, UK) during a modified 10-m walk test. Raw data captured by the IMU were directly compared to Vicon data. Additionally, 5 objective gait parameters were compared for controls and the 5 trauma patients.

Results:

The IMU data streams strongly correlated with Vicon data for measured variables used in the subsequent gait analysis: vertical acceleration, vertical displacement, pitch angular velocity, and roll angular velocity (Pearson r-value > 0.9 for all correlations). Quantitative kinematic data in post-trauma patients significantly differed from control data and correlated with observed gait pathology.

Conclusions:

When compared to the gold standard motion capture reference system (Vicon), an IMU can reliably and accurately measure clinically relevant gait parameters and differentiate between normal and pathologic gait patterns. This technology is easily integrated into clinical settings, requires minimal time, and represents a performance-based method for quantifiably assessing gait outcomes.

Level of Evidence:

Diagnostic Level 1.

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.

Coper Classification Early After Anterior Cruciate Ligament Rupture Changes With Progressive Neuromuscular and Strength Training and Is Associated With 2-Year Success: The Delaware-Oslo ACL Cohort Study

BACKGROUND

Some athletes demonstrate excellent dynamic stability after anterior cruciate ligament (ACL) rupture and return to sport without ACL reconstruction (ACLR) (copers). Others demonstrate persistent instability despite rehabilitation (noncopers) and require surgical stabilization. Testing to determine coper classification can identify potential copers early after rupture. It is unclear how coper classification changes after a brief intervention and how early classification relates to long-term outcomes.

PURPOSE

(1) To evaluate the consistency of early coper classification (potential coper vs noncoper) before and after progressive neuromuscular and strength training (NMST) among athletes early after acute ACL rupture and (2) to evaluate the association of early coper classification with 2-year success after ACL rupture.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This was a prospective analysis from the Delaware-Oslo ACL Cohort Study, composed of athletes consecutively enrolled early after ACL rupture. Participants (n = 271) were tested and classified as potential copers or noncopers according to established criteria before and after a 10-session NMST program. Success 2 years after ACLR or nonoperative rehabilitation was defined as meeting or exceeding sex- and age-matched norms for knee function, no ACL graft rupture, and ≤1 episode of giving way within the previous year. The McNemar test evaluated changes in coper classification pre- to posttraining. Logistic regression adjusted for baseline characteristics was used to evaluate the association of early coper classification and surgical status with 2-year success.

RESULTS

Of 300 athletes enrolled, 271 (90%) completed the posttraining data collection, and 219 (73%) returned for the 2-year follow-up. The coper classifications were different between time points: nearly half of those classified initially as noncopers became potential copers ( P < .001). At the 2-year follow-up, 66% of the ACLR group and 74% of the nonoperative group were successful. Athletes who were potential copers posttraining and chose ACLR or nonoperative rehabilitation had 2.7 (95% CI, 1.3-5.6) and 2.9 (95% CI, 1.2-7.2) times the odds of success, respectively, as compared with noncopers who chose ACLR.

CONCLUSION

Coper classification improved after NMST; more athletes became potential copers. Athletes who were potential copers after NMST were more likely to succeed 2 years later regardless of whether they had surgery, strongly supporting the addition of NMST before ACLR. Persistent noncopers fared poorly, indicating that more intensive rehabilitation may be needed.

Anterior cruciate ligament reconstruction improves subjective ability but not neuromuscular biomechanics during dynamic tasks

PURPOSE

The purpose of this study was to identify high-functioning anterior cruciate ligament-deficient patients and assess the effects of reconstruction on their self-reported functionality, muscle activations and biomechanical properties.

METHODS

Twenty young and active patients participated pre- (11.5 ± 14.3 months post-injury) and again 10.5 ± 1.7 months post-reconstruction and were individually matched to 20 healthy controls. Participants completed hop and side cut movements while patient-related outcome measures, lower limb electromyography, kinetic, and whole body kinematic data were collected. One-dimensional statistical parametric mapping was used to test for group differences (healthy vs deficient; deficient vs reconstructed; reconstructed vs healthy).

RESULTS

When comparing healthy to anterior cruciate ligament-deficient participants, all questionnaires indicated significant lower subjective function while the only substantial biomechanical difference between these participants was a decreased knee extensor moment in both the hop (peak difference: 0.63 Nm/kg, p < 0.001) and side cut (peak difference: 0.76 Nm/kg, p < 0.001). When comparing patients' pre- and post-reconstruction, no biomechanical differences were observed whereas only half of the questionnaires (Tegner, Lysholm, KNEES-ADL, KNEES-Slackness, KNEES-Looseness, KNEES-Sport Behaviour, IKDC, and KOOS-QoL) indicated higher function in the reconstructed state. When comparing the reconstructed patients to the healthy participants, all questionnaires were still significantly higher in the healthy controls. The reconstructed group also had a smaller flexion angle (peak difference: 14.5°, p = 0.007) and knee extensor moment (peak difference: 0.62 Nm/kg, p < 0.001) during the hop and a smaller knee extensor moment (peak difference: 0.90 Nm/kg, p < 0.001) during the side-cut task.

CONCLUSION

At 10-months post-reconstruction, the current results indicate that in high-functioning anterior cruciate ligament-deficient patients, reconstruction had little impact on objective measures of functional ability during dynamic tasks although self-reported function was improved.

LEVEL OF EVIDENCE

Therapeutic prospective cohort study, Level II.

A Review of the Evolution of Vision-Based Motion Analysis and the Integration of Advanced Computer Vision Methods Towards Developing a Markerless System

BACKGROUND

The study of human movement within sports biomechanics and rehabilitation settings has made considerable progress over recent decades. However, developing a motion analysis system that collects accurate kinematic data in a timely, unobtrusive and externally valid manner remains an open challenge.

MAIN BODY

This narrative review considers the evolution of methods for extracting kinematic information from images, observing how technology has progressed from laborious manual approaches to optoelectronic marker-based systems. The motion analysis systems which are currently most widely used in sports biomechanics and rehabilitation do not allow kinematic data to be collected automatically without the attachment of markers, controlled conditions and/or extensive processing times. These limitations can obstruct the routine use of motion capture in normal training or rehabilitation environments, and there is a clear desire for the development of automatic markerless systems. Such technology is emerging, often driven by the needs of the entertainment industry, and utilising many of the latest trends in computer vision and machine learning. However, the accuracy and practicality of these systems has yet to be fully scrutinised, meaning such markerless systems are not currently in widespread use within biomechanics.

CONCLUSIONS

This review aims to introduce the key state-of-the-art in markerless motion capture research from computer vision that is likely to have a future impact in biomechanics, while considering the challenges with accuracy and robustness that are yet to be addressed.

Effect of foot progression angle adjustment on the knee adduction moment and knee joint contact force in runners with and without knee osteoarthritis

BACKGROUND

Knee adduction moment (KAM) is often used as a surrogate marker of knee contact force (KCF) during walking. Previous studies have reported potential benefits to reduce KAM in patients with knee osteoarthritis (OA) by foot progression angle adjustment. However, KAM is an external moment and it does not consider any muscle contribution to the joint loading, which should pose a greater influence in running than walking.

RESEARCH QUESTION

This study used a computational model to compare KAM and KCF between runners with and without knee OA during running. In addition, we evaluated the KAM and KCF when runners adjusted to an out-toe running style.

METHODS

Kinematic, kinetic, and lower limb EMG data were collected from 9 runners with knee OA and 10 healthy counterparts. They were asked to run at their usual speed with standard shoes on an instrumented treadmill.

RESULTS

We found no significant difference in the KAM during running between OA and the healthy group (p > 0.376). However, runners with knee OA exhibited a greater total KCF than the healthy counterparts (p < 0.041). We did not observe any reduction in KAM after foot progression angle adjustment (p > 0.346). Surprisingly, an increase in the longitudinal KCF and total KCF were found with adjustment of foot progression angle (p < 0.046).

SIGNIFICANCE

Unlike the findings reported by the previous walking trials, our findings do not support the notion that foot progression angle adjustment would lead to a lower joint loading during running.

Hip joint biomechanics in those with and without post-traumatic knee osteoarthritis after anterior cruciate ligament injury

BACKGROUND

Anterior cruciate ligament injury results in altered kinematics and kinetics in the knee and hip joints that persist despite surgical reconstruction and rehabilitation. Abnormal movement patterns and a history of osteoarthritis are risk factors for articular cartilage degeneration in additional joints. The purpose of this study was to determine if hip joint biomechanics early after anterior cruciate ligament injury and reconstruction differ between patients with and without post-traumatic knee osteoarthritis 5years after reconstruction. The study's rationale was that individuals who develop knee osteoarthritis after anterior cruciate ligament injury may also demonstrate large alterations in hip joint biomechanics.

METHODS

Nineteen athletes with anterior cruciate ligament injury completed standard gait analysis before (baseline) and after (post-training) extended pre-operative rehabilitation and at 6months, 1year, and 2years after reconstruction. Weightbearing knee radiographs were completed 5years after reconstruction to identify medial compartment osteoarthritis.

FINDINGS

Five of 19 patients had knee osteoarthritis at 5years after anterior cruciate ligament reconstruction. Patients with knee osteoarthritis at 5years walked with smaller sagittal plane hip angles (P: 0.043) and lower sagittal (P: 0.021) and frontal plane (P: 0.042) external hip moments in the injured limb before and after reconstruction compared to those without knee osteoarthritis.

INTERPRETATION

The current findings suggest hip joint biomechanics may be altered in patients who develop post-traumatic knee osteoarthritis. Further study is needed to confirm whether the risk of non-traumatic hip pathology is increased after anterior cruciate ligament injury and if hip joint biomechanics influence its development.

Hamstring Activity in the Anterior Cruciate Ligament Injured Patient: Injury Implications and Comparison With Quadriceps Activity

PURPOSE

To investigate the potential causes of diminished knee extension after acute anterior cruciate ligament (ACL) injury using both surface electromyography (sEMG) analysis of the quadriceps and hamstrings, and gait analysis to assess muscle action and tone.

METHODS

Consecutive patients with an acute ACL tear underwent sEMG and gait analysis within 2 weeks of injury, before ACL reconstruction. Standard motion analysis techniques were used and sEMG data were collected simultaneously with gait data. T-tests were used to determine differences between the ACL-deficient and control subjects in knee flexion angles, peak external knee joint moments, and total time that a muscle was activated ("on") during gait. External knee moments were expressed as a percentage of body weight times height.

RESULTS

Ten patients (mean age 24 ± 4 years) were included at a mean 10.2 days between injury and analysis; 10 uninjured, matched control subjects were included for comparison. There were significant increases in minimum flexion angle at heel strike (5.92 ± 3.39 v -3.49 ± 4.55, P < .001) and midstance (14.1 ± 6.23 v 1.20 ± 4.21, P < .001) in the injured limb compared with controls. There were significantly lower maximum external extension moments at heel strike (-0.99 ± 0.46 v -2.94 ± 0.60, P < .001) and during the second half of stance in the injured limb compared with controls (-0.56 ± 1.14 v -3.54 ± 1.31, P < .001). The rectus femoris was "on" significantly less during gait in the injured leg compared with controls (49.1 ± 7.76% v 61.0 ± 14.8%, P = .044). There were no significant differences in hamstring activity "on" time during gait (P > .05).

CONCLUSIONS

In patients with acute ACL injury, the ACL-deficient limb does not reach as much extension as controls. Although the rectus femoris is "on" for shorter periods during the gait cycle, there is no difference in hamstring time on during gait. This information may help clinicians better understand muscle function and gait patterns in the acute time period after ACL injury.

LEVEL OF EVIDENCE

Level III, case control study.

Mapping current research trends on anterior cruciate ligament injury risk against the existing evidence: In vivo biomechanical risk factors

BACKGROUND

Whilst many studies measure large numbers of biomechanical parameters and associate these to anterior cruciate ligament injury risk, they cannot be considered as anterior cruciate ligament injury risk factors without evidence from prospective studies. A review was conducted to systematically assess the in vivo biomechanical literature to identify biomechanical risk factors for non-contact anterior cruciate ligament injury during dynamic sports tasks; and to critically evaluate the research trends from retrospective and associative studies investigating non-contact anterior cruciate ligament injury risk.

METHODS

An electronic literature search was undertaken on studies examining in vivo biomechanical risk factors associated with non-contact anterior cruciate ligament injury. The relevant studies were assessed by classification; level 1 - a prospective cohort study, level 2 - a retrospective study or level 3 - an associative study.

FINDINGS

An initial search revealed 812 studies but this was reduced to 1 level 1 evidence study, 20 level 2 evidence studies and 175 level 3 evidence studies that met all inclusion criteria. Level 1 evidence showed that the knee abduction angle, knee abduction moment and ground reaction force were biomechanical risk factors. Nine level 2 studies and eighty-three level 3 studies used these to assess risk factors in their study. Inconsistencies in results and methods were observed in level 2 and 3 studies.

INTERPRETATION

There is a lack of high quality, prospective level 1 evidence related to biomechanical risk factors for non-contact anterior cruciate ligament injury. More prospective cohort studies are required to determine risk factors and provide improved prognostic capability.

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.

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.

Analysis of muscle synergies and activation-deactivation patterns in subjects with anterior cruciate ligament deficiency during walking

BACKGROUND

The knowledge of muscle activation patterns when doing a certain task in subjects with anterior cruciate ligament deficiency could help to improve their rehabilitation treatment. The goal of this study is to identify differences in such patterns between anterior cruciate ligament-deficient and healthy subjects during walking.

METHODS

Electromyographic data for eight muscles were measured in a sample of eighteen subjects with anterior cruciate ligament deficiency, in both injured (ipsilateral group) and non-injured (contralateral group) legs, and a sample of ten healthy subjects (control group). The analysis was carried out at two levels: activation-deactivation patterns and muscle synergies. Muscle synergy components were calculated using a non-negative matrix factorization algorithm.

FINDINGS

The results showed that there was a higher co-contraction in injured than in healthy subjects. Although all muscles were activated similarly since all subjects developed the same task (walking), some differences could be observed among the analyzed groups.

INTERPRETATION

The observed differences in the synergy components of injured subjects suggested that those individuals alter muscle activation patterns to stabilize the knee joint. This analysis could provide valuable information for the physiotherapist to identify alterations in muscle activation patterns during the follow-up of the subject's rehabilitation.

Combination of eccentric exercise and neuromuscular electrical stimulation to improve biomechanical limb symmetry after anterior cruciate ligament reconstruction

BACKGROUND

We have previously reported that an eccentrically-based rehabilitation protocol post-ACLr induced greater quadriceps activation and strength than a neuromuscular electrical stimulation (NMES) intervention and was just as effective as a combined NMES and eccentric intervention. However, the effect an eccentrically-based intervention has on restoring normal knee mechanics during a single-legged landing task remains unknown.

METHODS

Thirty-six individuals post-injury were placed into four treatment groups: NMES and eccentrics, eccentrics-only, NMES-only, standard of care, and healthy controls participated. NMES and eccentrics received a combined NMES and eccentric protocol post-reconstruction (each treatment 2× per week for 6 weeks), whereas groups NMES-only and eccentric-only received only the NMES or eccentric therapy, respectively. To evaluate knee mechanics limb symmetry, the area under the curve for knee flexion angle and extension moment was derived and then normalized to the contralateral limb. Quadriceps strength was evaluated using the quadriceps index.

FINDINGS

Compared to healthy, reduced sagittal plane knee limb symmetry was found for groups NMES-only, ECC-only and standard of care for knee extension moment (P<0.05). No difference was detected between healthy and NMES and eccentrics (P>0.06). No difference between groups was detected for knee flexion angle limb symmetry (P>0.05). Greater knee flexion angles and moments over stance were related to quadriceps strength.

INTERPRETATION

The NMES and eccentrics group was found to restore biomechanical limb symmetry that was most closely related to healthy individuals following ACL reconstruction. Greater knee flexion angles and moments over stance were related to quadriceps strength.

Clinically-relevant measures associated with altered contact forces in patients with anterior cruciate ligament deficiency

BACKGROUND

Knee joint contact forces are altered after anterior cruciate ligament injury during walking and may be related to clinically-relevant measures of impairments or self-reported function. The purpose of this study was to investigate the association of several clinically-relevant measures with altered knee contact forces in patients with anterior cruciate ligament injury.

METHODS

Data for this study represent a cross-sectional observational analysis of thirty-seven (23 M, 14 F) patients with complete unilateral anterior cruciate ligament injury. Gait analysis with electromyography was used to obtain estimates of tibiofemoral joint contact force using an electromyography-driven musculoskeletal model. Multivariable linear regression was used to identify measures associated with tibiofemoral joint contact force.

FINDINGS

Involved knee extensor muscle strength and patient-reported knee function on the Global Rating Scale of perceived function were significantly associated with peak tibiofemoral contact force for the involved limb. Patients who were stronger and who perceived higher knee function walked with greater contact forces on their involved knees. After controlling for walking speed, involved extensor strength explained 8.9% of the variance in involved peak tibiofemoral contact force and score on the Global Rating Scale explained an additional 9.4% of the variance.

INTERPRETATION

Improvements in involved quadriceps strength and overall function as measured by patient self-report may be important for increasing involved limb contact forces, thereby restoring loading symmetry in these patients who demonstrate decreased involved limb loading after injury. These results highlight the potential value of studying the recovery of strength, self-reported function and joint loading symmetry in patients with anterior cruciate ligament injury.

Differences in neuromuscular control and quadriceps morphology between potential copers and noncopers following anterior cruciate ligament injury

STUDY DESIGN

Prospective cross-sectional study.

OBJECTIVES

To compare knee muscle morphology and voluntary neuromuscular control in individuals who sustained an anterior cruciate ligament (ACL) injury and were identified as being capable of avoiding surgery (potential copers) and those who were recommended for surgery (noncopers), within 6 months of injury.

BACKGROUND

Quadriceps atrophy and poor neuromuscular control have been found in noncopers. However, the reasons why some noncopers may be able to avoid surgery remain elusive.

METHODS

Twenty participants (10 ACL-deficient noncopers and 10 ACL-deficient potential copers) were included in this study. Axial spin-echo, T1-weighted magnetic resonance imaging data of the lower extremities were captured. The volume and maximum cross-sectional area (CSA) of each muscle of the quadriceps and hamstrings were calculated following digital reconstruction. In addition, voluntary neuromuscular control was evaluated using an established target-matching task that required participants to produce static isometric loads across the knee joint. Electromyography was acquired from 5 muscles as participants performed the target-matching task. Circular statistics were used to calculate a specificity index to describe how well focused each muscle was activated toward its primary direction of muscle action. The ACL-deficient limb was then compared to the uninvolved limb of the noncopers and potential copers.

RESULTS

The vasti (vastus medialis and vastus intermedius) of the involved limb of the noncopers were significantly smaller (P<.031) in comparison to those of their uninvolved limb. The potential copers' vastus lateralis maximum CSA (P = .047), total quadriceps muscle volume (P = .020) and maximum CSA (P = .015), and quadriceps-hamstring ratio volume (P = .021) and maximum CSA (P = .007) demonstrated quadriceps atrophy. However, only the ACL-deficient limb of the older (mean ± SD age, 27.4 ± 11.4 versus 19.9 ± 3.3 years; P = .032) and lower-activity-level (3.3 ± 0.5 versus 3.6 ± 0.5; P = .098) noncoper group demonstrated reduced rectus femoris (P = .057) and lateral hamstring (P = .064) neuromuscular control in comparison to their uninvolved limb.

CONCLUSION

These findings suggest that quadriceps and hamstring muscle function, rather than muscle size, may be an important factor in the varied response early after ACL injury.

Kinesiophobia after anterior cruciate ligament rupture and reconstruction: noncopers versus potential copers

STUDY DESIGN

Secondary-analysis, longitudinal cohort study.

OBJECTIVES

To compare kinesiophobia levels in noncopers and potential copers at time points spanning pre- and post-anterior cruciate ligament (ACL) reconstruction and to examine the association between changes in kinesiophobia levels and clinical measures.

BACKGROUND

After ACL injury, a screening examination may be used to classify patients as potential copers or noncopers based on dynamic knee stability. Quadriceps strength, single-leg hop performance, and self-reported knee function are worse in noncopers. High kinesiophobia levels after ACL reconstruction are associated with poorer self-reported knee function and lower return-to-sport rates. Kinesiophobia levels have not been examined before ACL reconstruction, across the transition from presurgery to postsurgery, or based on potential coper and noncoper classification.

METHODS

Quadriceps strength indexes, single-leg hop score indexes, self-reported knee function (Knee Outcome Survey activities of daily living subscale, global rating scale), and kinesiophobia (Tampa Scale of Kinesiophobia [TSK-11]) scores were compiled for potential copers (n = 50) and noncopers (n = 61) from 2 clinical trial databases. A repeated-measures analysis of variance was used to compare TSK-11 scores between groups and across 4 time points (before preoperative treatment, after preoperative treatment, 6 months post-ACL reconstruction, and 12 months post-ACL reconstruction). Correlations determined the association of kinesiophobia levels with other clinical measures.

RESULTS

Presurgery TSK-11 scores were significantly higher in noncopers than in potential copers. Postsurgery, no group differences existed. TSK-11 scores in both groups decreased across all time points; however, TSK-11 scores decreased more in noncopers in the interval between presurgery and postsurgery. In noncopers, the decreases in TSK-11 scores from presurgery to postsurgery and after surgery were related to improvements in the Knee Outcome Survey activities of daily living subscale, whereas the association was only present in potential copers after surgery.

CONCLUSION

Kinesiophobia levels were high in both noncopers and potential copers preoperatively. Restoration of mechanical knee stability with surgery might have contributed to decreased kinesiophobia levels in noncopers. Kinesiophobia is related to knee function after surgery, regardless of preoperative classification as a potential coper or noncoper.

Neuromuscular training to target deficits associated with second anterior cruciate ligament injury

SYNOPSIS

Successful return to previous level of activity following anterior cruciate ligament (ACL) reconstruction is not guaranteed, and the prevalence of second ACL injury may be as high as 30%. In particular, younger athletes who return to sports activities within the first several months after ACL reconstruction may be at significantly greater risk of a second ACL rupture compared to older, less active individuals. Significant neuromuscular deficits and functional limitations are commonly identified in athletes following ACL reconstruction, and these abnormal movement and neuromuscular control profiles may be both residual of deficits existing prior to the initial injury and exacerbated by the injury and subsequent ACL reconstruction surgery. Following ACL reconstruction, neuromuscular deficits are present in both the surgical and nonsurgical limbs, and accurately predict second-ACL injury risk in adolescent athletes. While second ACL injury in highly active individuals may be predicated on a number of modifiable and nonmodifiable factors, clinicians have the greatest potential to address the modifiable postsurgical risk factors through targeted neuromuscular interventions. This manuscript will (1) summarize the neuromuscular deficits commonly identified at medical discharge to return to sport, (2) provide the evidence underlying second-ACL injury risk factors, (3) propose a method to assess the modifiable deficits related to second-ACL injury risk, and (4) outline a method of intervention to prevent second ACL injury. The program described in this clinical commentary was developed with consideration for the modifiable factors related to second-injury risk, the principles of motor learning, and careful selection of the exercises that may most effectively modify aberrant neuromuscular patterns. Future validation of this evidence-based, late-phase rehabilitation program may be a critical factor in maximizing return-to-activity success and reduction of second-injury risk in highly active individuals.

LEVEL OF EVIDENCE

Therapy, level 5.

Unilateral stance strategies of athletes with ACL deficiency

Aberrant movement strategies are characteristic of ACL-deficient athletes with recurrent knee instability (noncopers), and may instigate premature or accelerate joint degradation. Biomechanical evaluation of kinematic changes over time may elucidate noncopers' responses to neuromuscular intervention and ACL reconstruction (ACLR). Forty noncopers were randomized into a perturbation group or a strength training only group. We evaluated the effects of perturbation training, and then gender on knee angle and tibial position during a unilateral standing task before and after ACLR. No statistically significant interactions were found. Before surgery, the strength training only group demonstrated knee angle asymmetry, but 6 months after ACLR, both groups presented with similar knee flexion between limbs. Aberrant and asymmetrical tibial position was found only in females following injury and ACLR. Neither treatment group showed distinct unilateral standing strategies following intervention; however, males and female noncopers appear to respond uniquely to physical therapy and surgery.

Altered loading in the injured knee after ACL rupture

Articular loading is an important factor in the joint degenerative process for individuals with anterior cruciate ligament (ACL) rupture. Evaluation of loading for a population that exhibits neuromuscular compensation for injury requires an approach which can incorporate individual muscle activation strategies in its estimation of muscle forces. The purpose of this study was to evaluate knee joint contact forces for patients with ACL deficiency using an EMG-driven modeling approach to estimate muscle forces. Thirty athletes with acute, unilateral ACL rupture underwent gait analysis after resolving range of motion, effusion, pain, and obvious gait impairments. Electromyography was recorded bilaterally from 14 lower extremity muscles and input to a musculoskeletal model for estimation of muscle forces and joint contact forces. Gait mechanics were consistent with previous reports for individuals with ACL-deficiency. Our major finding was that joint loading was altered in the injured limb after acute ACL injury; patients walked with decreased contact force on their injured knee compared to their uninjured knee. Both medial and lateral compartment forces were reduced without a significant change in the distribution of tibiofemoral load between compartments. This is the first study to estimate medial and lateral compartment contact forces in patients with acute ACL rupture using an approach which is sensitive to individual muscle activation patterns. Further work is needed to determine whether this early decreased loading of the injured limb is involved in the development of osteoarthritis in these patients.

Management of the athlete with acute anterior cruciate ligament deficiency

Background:

Identification of highly active individuals early after acute anterior cruciate ligament deficiency who are good candidates for nonoperative management is a clinical challenge. The University of Delaware has developed and validated a treatment algorithm and screening examination to distinguish between nonoperative and surgical candidates.

Study Design:

Review.

Evidence Acquisition:

A description of the decision-making rules and rehabilitation protocol for highly active individuals with anterior cruciate ligament deficiency is provided. Results from clinical trials, outcome studies, and biomechanical investigations conducted using the treatment algorithm and screening examination are also reviewed.

Results:

Patients identified as nonoperative rehabilitation candidates using these clinical guidelines have a far greater success rate than what has been reported when patients self-select nonoperative management. Furthermore, nonoperative outcomes are improved when patients participate in a perturbation-enhanced rehabilitation protocol. Divergent lower extremity movement patterns are consistent with the different functional abilities of the dichotomous patient groups identified with the screening examination.

Conclusion:

Given the differential patient response to anterior cruciate ligament injury, implementation of the decision-making guidelines discussed in this review offers clinicians the opportunity to provide individualized patient care rather than continuing with a blanket surgical treatment strategy.

Unloader braces for medial compartment knee osteoarthritis: implications on mediating progression

Background:

For persons with unicompartment knee osteoarthritis (OA), off-unloader braces are a mechanical intervention designed to reduce pain, improve physical function, and possibly slow disease progression. Pain relief is thought to be mediated by distracting the involved compartment via external varus or valgus forces applied to the knee. In so doing, tibiofemoral alignment is improved, and load is shifted off the degenerative compartment, where exposure to potentially damaging and provocative mechanical stresses are reduced.

Objectives:

To provide a synopsis of the evidence documented in the scientific literature concerning the efficacy of off-loader knee braces for improving symptomatology associated with painful disabling medial compartment knee OA.

Search Strategy:

Relevant peer-reviewed publications were retrieved from a MEDLINE search using the terms with the reference terms osteoarthritis, knee, and braces (per Medical Subject Headings), plus a manual search of bibliographies from original and review articles and appropriate Internet resources.

Results:

For persons with combined unicompartment knee OA and mild to moderate instability, the strength of recommendation reported by the Osteoarthritis Research Society International in the ability of off-loader knee braces to reduce pain, improve stability, and diminish the risk of falling was 76% (95% confidence interval, 69%-83%). The more evidence the treatment is effective, the higher the percentage.

Conclusions:

Given the encouraging evidence that off-loader braces are effective in mediating pain relief in conjunction with knee OA and malalignment, bracing should be fully used before joint realignment or replacement surgery is considered. With the number of patients with varus deformities and knee pain predicted to increase as the population ages, a reduction of patient morbidity for this widespread chronic condition in combination with this treatment modality could have a positive impact on health care costs and the economic productivity and quality of life of the affected individuals.

The impact of quadriceps femoris strength asymmetry on functional performance at return to sport following anterior cruciate ligament reconstruction

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To investigate the impact of quadriceps femoris (QF) muscle strength asymmetry at the time of return to sport on self-reported function and functional performance of individuals following anterior cruciate ligament reconstruction (ACLR).

BACKGROUND

Evidence-based QF strength guidelines for return-to-sport decision making are lacking. Objective guidelines necessitate understanding the impact of QF strength deficits at the time of return to sport on function and performance.

METHODS

Fifty-five individuals (mean age, 17.3 years) who were cleared for return to sport following primary ACLR (ACLR group) and 35 uninjured individuals (mean age, 17.0 years) in a control group participated in the study. QF strength (maximum voluntary isometric contraction) was assessed, and the quadriceps index (QI) was calculated [(involved strength/uninvolved strength) × 100%]. The ACLR group was further subdivided into 2 groups, based on the QI: high quadriceps (QI of 90% or greater) and low quadriceps (QI of less than 85%). The International Knee Documentation Committee Subjective Knee Evaluation Form score was used to assess self-reported function, and hop tests were used to assess functional performance. Multivariate analysis of variance and hierarchical regression analyses were performed.

RESULTS

The individuals in the ACLR group were weaker, reported worse function, and performed worse on hop tests compared to those in the control group (P<.05). The low-quadriceps group demonstrated worse performance on the hop tests compared to the high-quadriceps group and the control group (P ≤.016). Hop test performance did not differ between the high-quadriceps and control groups (P ≥.14). QF strength predicted performance on the hop tests beyond graft type, presence of meniscus injury, knee pain, and knee symptoms.

CONCLUSION

At the time of return to sport, individuals post-ACLR who had weaker QF (QI of less than 85%) demonstrated decreased function, whereas those with minimal QF strength deficits (QI of 90% or greater) demonstrated functional performance similar to uninjured individuals. QF strength deficits predicted hop test performance beyond the influences of graft type, presence of meniscus injury, knee pain, and knee symptoms.

Identifying individuals with an anterior cruciate ligament-deficient knee as copers and noncopers: a narrative literature review

STUDY DESIGN

Narrative literature review.

OBJECTIVES

First, to explore the differences and outcomes between individuals who have had anterior cruciate ligament (ACL) reconstruction and those who did not undergo surgical intervention, following a tear of the ACL. Second, to review the evidence related to the ability to identify individuals who may or may not need surgery after an ACL rupture. Finally, to describe the differences between copers and noncopers.

BACKGROUND

ACL rupture may result in increased tibiofemoral laxity and impaired neuromuscular function, which ultimately may lead to knee instability and dysfunction. Individuals who opt to choose surgery due to these changes may be defined as "noncopers." Conversely, those individuals who have an ACL-deficient knee without functional impairment and instability and successfully resume preinjury activity levels without surgical intervention may be defined as "copers."

METHODS

An electronic search was conducted up to April 2011, using medical subject headings and free-text words. The subject-specific search was based on the terms "anterior cruciate ligament reconstruction versus conservative treatment," "copers," "noncopers."

RESULTS

A similar percentage of copers and noncopers return to sporting activity. Three papers used an algorithm and screening examination involving individuals with ACL injuries. Evidence suggests that, as opposed to copers, noncopers have deficits in quadriceps strength, vastus lateralis atrophy, quadriceps activation deficits, altered knee movement patterns, reduced knee flexion moment, and greater quadriceps/hamstring cocontraction.

CONCLUSION

ACL screening examination showed preliminary evidence for detecting potential copers. Objective differences exist between copers and noncopers. Individuals with ACL injury should be informed of the possibility of good knee function following a nonoperative rehabilitation program.

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.

Postural orientation in subjects with anterior cruciate ligament injury: development and first evaluation of a new observational test battery

Anterior cruciate ligament (ACL) injury is associated with mechanical instability and defective neuromuscular function, and can lead to further injury, increased joint loading and osteoarthritis. Patients with ACL injury demonstrate altered postural orientation, manifested as observable "substitution patterns" (SPs) but no one has applied a clinically useful method to systematically study postural orientation in these patients. Here, we investigated the presence of such patterns in 24 adults with ACL injury and in 49 controls, in parallel with the development and a first evaluation of a new test battery, test for SPs. The rationale behind the test for SPs was to characterize postural orientation as the ability to maintain appropriate relationships between body segments and environment during weight-bearing movements. In this first study, patients displayed SPs more frequently and/or more clearly on their injured, but also their uninjured side than did controls. Inter-rater and intra-rater reproducibility was good at a group level. Future studies of validity, responsiveness and including other subgroups of patients with ACL injury will have to prove if the test for SPs can be used in the diagnostics of defective neuromuscular function following knee injury, when planning and carrying out training and rehabilitation and when deciding appropriate time to return to activity and sports after ACL injury.

Sagittal plane knee joint moments following anterior cruciate ligament injury and reconstruction: a systematic review

BACKGROUND

Gait adaptations in persons with anterior cruciate ligament (ACL) injuries have been debated. Many studies examine high speed, 3-dimensional video gait analysis to compare knee joint torques during simulated activities of daily living.

METHODS

We performed a systematic review of the literature for published clinical papers that reported sagittal plane knee joint kinetics in ACL deficient or reconstructed individuals. We calculated weighted effect sizes (Cohen's d) to evaluate the magnitude of differences between the injured limb and the contralateral limb and healthy, uninjured limbs in control subjects.

FINDINGS

Ten published papers reported kinetic data in ACL deficient subjects while walking for comparisons to the contralateral side (weighted average d=-0.83, range: -3.21, 1.07), and to healthy control knees (weighted average d=-1.0, range: -3.36, 0.17); four papers reported data during jogging compared to the contralateral side (weighted average d=-0.94, range: -4.15, 0.17), and to controls (weighted average d=-1.42, range: -3.83,-0.2). Four papers reported data for ACL-reconstructed patients compared to healthy controls during walking (weighted average d=-0.94, range: -0.4, -1.77) and jogging (weighted average d=-1.18).

INTERPRETATION

Effect sizes comparing knee joint moments in injured vs. healthy control subjects appear to be slightly higher while jogging than walking, and higher in ACL-deficient patients compared to reconstructions. However, magnitudes are all large. Few studies report stair climbing. Consequently, it is difficult to make inferences with confidence during these tasks.

Adaptations of gait and muscle activation in chronic ACL deficiency

The purpose was to investigate whether deviations in gait parameters or muscular activity patterns can be detected in the injured and healthy leg of chronic ACL-deficient subjects. Sixteen medium-level active chronic ACL-deficient patients classified as "copers" (injury duration: 12-240 months, age 17-52 years) and 15 healthy subjects (age 20-33 years) walked at self-selected speed along a 10-m runway with a level force-plate. Gait specific data, ground reaction forces, knee and ankle angles, and EMG were documented. Knee laxity was increased and the functional scores (Lysholm, KOOS) decreased in the ACL- deficient subjects, whereas the Tegner activity level score was normal. Gait speed, stride length and stance time did not differ between ACL-deficient subjects and controls. Ground reaction forces (magnitude and times), as well as knee and ankle angles at selected points during stance and swing phases were normal in the ACL-deficient subjects compared to controls. The total duration of m. tibialis anterior (TA) activity was longer in ACL-deficient subjects than in controls (ACL-deficient injured leg vs. controls, P < 0.05). In addition, the onset of lateral gastrocnemius (LG) muscle activity occurred earlier in ACL-deficient patients (P < 0.03), resulting in a TA-LG cocontraction in the ACL-deficient but not in the control group. In conclusion, chronic, medium-level active ACL-deficient patients showed abnormalities in muscular activity patterns during gait compared to control subjects, whereas there were no detectable changes in ground reaction forces and 3D kinematic data. As the aberrant muscular activity pattern may be of importance for an even gait, it is proposed that EMG recordings may give additional information in the evaluation and rehabilitation of gait when the ACL is absent.

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.

Hamstrings co-activation in ACL-deficient subjects during isometric whole-leg extensions

It has been reported that anterior cruciate ligament (ACL)-deficient subjects increase the level of hamstrings activation and this has been interpreted as a means to cope with increased anterior tibial laxity in the knee. This study aimed to establish to what extent co-activation strategies in ACL-deficient subjects are load level and knee angle dependent. Eleven chronic ACL-deficient and 15 control subjects were positioned in a range of postures and asked to exert a feedback controlled vertical ground reaction force (GRF; 30, 60% and maximum), while horizontal forces were not constrained. Surface electromyography of the leg muscles and GRF were measured. In postures with the knee over and in front of the ankle, ACL-deficient subjects generated, respectively, 2.4 and 5.1% MVC more hamstrings activation than control subjects. Enhanced hamstrings co-activation in ACL-deficient subjects was more apparent in extended than in flexed knee angles. For both ACL-deficient and control subjects, hamstrings co-activation was larger in males than in females. It is concluded that ACL-deficient subjects show a task dependent increase in hamstrings co-activation, but its clinical significance remains to be shown.

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.

Instability, laxity, and physical function in patients with medial knee osteoarthritis

BACKGROUND AND PURPOSE

Studies have identified factors that contribute to functional limitations in people with knee osteoarthritis (OA), including quadriceps femoris muscle weakness, joint laxity, and reports of knee instability. However, little is known about the relationship among these factors or their relative influence on function. The purpose of this study was to investigate self-reported knee instability and its relationships with knee laxity and function in people with medial knee osteoarthritis (OA).

PARTICIPANTS

Fifty-two individuals with medial knee OA participated in the study.

METHODS

Each participant was classified into 1 of 3 groups based on reports of knee instability. Limb alignment, knee laxity, and quadriceps femoris muscle strength (force-generating capacity) were assessed. Function was measured with the Knee Injury and Osteoarthritis Outcome Score (KOOS) and a stair-climbing test (SCT). Group differences were detected with one-way analyses of variance, and relationships among variables were assessed with the Eta(2) statistic and hierarchical regression analysis.

RESULTS

There were no differences in alignment, laxity, or strength among the 3 groups. Self-reported knee instability did not correlate with medial laxity, limb alignment, or quadriceps femoris muscle strength. Individuals reporting worse knee instability scored worse on all subsets of the KOOS. Self-reported knee instability scores significantly contributed to the prediction of all measures of function above that explained by quadriceps femoris muscle force, knee laxity, and alignment. Neither laxity nor alignment contributed to any measure of function.

DISCUSSION AND CONCLUSION

Self-reported knee instability is a factor that is not directly associated with knee laxity and contributes to worse function. Further research is necessary to delineate the factors that contribute to self-reported knee instability and reduced function in this population.

Reliability and validity of videotaped functional performance tests in ACL-injured subjects

BACKGROUND AND PURPOSE

In clinical practice, visual observation is often used to determine functional impairment and to evaluate treatment following a knee injury. The aim of this study was to evaluate the reliability and validity of observational assessments of knee movement pattern quality during five functional tests in subjects with an anterior cruciate ligament (ACL) injury.

METHOD

Twelve ACL-injured men, mean age 40 years, were video filmed before and after 12 weeks of knee-specific training when performing five different functional tests: walking, knee bending, step activity, crossover hop on one leg and one-leg hop. The videos were observed by four physiotherapists, and the knee movement pattern quality, a feature of the loading strategy of the lower extremity, was scored on an 11-point rating scale. To assess the criterion validity, the observational rating was correlated with the maximum knee flexion angle in landing during the crossover hop determined by a three-dimensional motion analysis system (VICON).

RESULTS

Inter-observer agreement between the four physiotherapists was moderate to good, ICC(1,2) 0.57-0.76 for the four test situations. Fair to good correlations were obtained between the observers' assessment and knee flexion angle, r = 0.37-0.61. The crossover hop test or one-leg hop test was ranked as the most useful test in 172 of 192 occasions (90%) when assessing knee function.

CONCLUSION

The moderate to good inter-observer reliability and the moderate criterion validity found indicate that the knee movement pattern quality in ACL-injured subjects can be determined by visual observation of more demanding functional tests such as crossover hop on one leg and one-leg hop for distance.

Individuals with an anterior cruciate ligament-deficient knee classified as noncopers may be candidates for nonsurgical rehabilitation

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

First, to classify a group of individuals with an anterior cruciate ligament (ACL)-deficient knee as potential copers or potential noncopers, based on an established screening examination. Second, to prospectively follow a cohort of individuals with an ACL injury and characterize the nonoperatively treated subjects as true copers and true noncopers 1 year after injury, and evaluate the outcomes in operatively treated individuals 1 year after ACL reconstruction. Finally, to calculate the predictive value of the screening examination based on a 1-year follow-up of the group of subjects with ACL tears treated nonoperatively.

BACKGROUND

A screening examination has been developed for early classification of individuals with ACL injuries. Potential copers have successfully been identified as rehabilitation candidates and have shown that they are able to continue preinjury activities without ACL reconstruction (true copers). However, the potential of individuals identified as noncopers to become true copers has not been studied.

METHODS AND MEASURES

One hundred and twenty-five subjects with ACL injury were evaluated using a screening examination consisting of 4 single-legged hop tests, the Knee Outcome Survey activities of daily living scale, the global rating of knee function, and the numbers of episodes of giving way. Knee laxity measurements, the international knee documentation committee subjective knee form (IKDC2000), and return to sport were included as outcome measurements.

RESULTS

Thirty-seven percent (n = 46) of the subjects with ACL injury were classified as potential copers at the screening examination. Of the 102 subjects examined at follow-up, 51% (n = 52) had undergone nonoperative treatment. Sixty-five percent (n = 34) of the nonoperated subjects were classified as true copers at the 1 year follow-up. Among the potential copers, 60% were true copers, while 70% of the subjects initially classified as potential noncopers were true copers at the 1 year follow-up. The positive predictive value for correctly classifying true copers at the screening examination was 60% (95% confidence interval: 41%-78%), while the negative predictive value was 30% (95% confidence interval: 16%-49%).

CONCLUSION

A majority (70%) of subjects classified as potential noncopers were true copers after 1 year of nonoperative treatment. Individuals with nonoperative treatment and ACL reconstruction showed excellent knee function and were highly active at the 1 year follow-up. The prognostic accuracy of this screening examination for correctly classifying true copers was poor.

Clinically assessed knee joint laxity as a predictor for reconstruction after an anterior cruciate ligament injury: a prospective study of 100 patients treated with activity modification and rehabilitation

BACKGROUND

The association of early knee joint laxity with the need for later reconstruction of the anterior cruciate ligament has not been extensively studied.

HYPOTHESIS

The grade of knee laxity can be used as an early predictor of the need for later reconstruction.

STUDY DESIGN

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

METHODS

One hundred consecutive patients with an acute arthroscopically verified total anterior cruciate ligament rupture were followed prospectively for 15 years. Lachman and pivot-shift tests were performed with the patient under general anesthesia before arthroscopy. After 3 months, the tests were repeated in an ordinary clinical setting. All patients underwent rehabilitation as the first choice of treatment. Anterior cruciate ligament reconstruction was performed only in cases of significant reinjuries (n = 16) or reparable meniscal lesions (n = 6) at a mean of 4 years after injury (range, 4 months-11 years). After 15 years, 94 patients were available for follow-up.

RESULTS

Of the later reconstructed patients (n = 18), 82% had a high-grade Lachman test under anesthesia compared with 63% of the nonreconstructed patients (n = 45; P = .048). At 3 months, 44% of the nonreconstructed patients (n = 32) had a high-grade Lachman test compared with 82% of the reconstructed patients (n = 18; P = .007). Twenty-five patients displayed a normal pivot-shift test at 3 months, of whom 1 underwent later reconstruction (P = .009). A high-grade pivot-shift test at 3 months was associated with an 11.4 relative risk for reconstruction.

CONCLUSION

A positive pivot-shift test at 3 months after injury in an awake patient is the strongest predictor for the future need for reconstruction. Furthermore, a normal pivot-shift test at 3 months indicates a low risk for reconstruction and is characteristic for copers.