Gait adaptations by patients who have a deficient anterior cruciate ligament

Changes in gait patterns after anterior cruciate ligament reconstruction in children

PURPOSE

Anterior cruciate ligament reconstruction (ACLR) in children is indicated to reduce recurrent knee instability and further damage to the joint. Postoperative modified gait pattern was reported in the adult population after ACLR. The aim of this study was to analyse gait abnormalities, and especially knee and ankle adaptations during gait in children after ACLR.

METHODS

A prospective study was performed between 2018 and 2022 on 50 children, aged nine to 15 years with unilateral ACL deficiency. Changes in gait pattern were evaluated by gait analysis before surgery and at the latest follow-up of 24 months. Kinematic data of ACL-deficient limb were compared to contralateral limb and to those of a matched control group of healthy children.

RESULTS

Compared to control group, knee flexion was decreased for both ACL-deficient and contralateral knee before surgery. Decreased knee flexion during gait cycle persisted at latest follow-up. Ankle kinematics showed decreased dorsal flexion for both ACL-deficient and contralateral limb before surgery. At latest follow-up, ankle kinematics were modified for ACL-reconstructed limbs only at initial contact and showed no significant difference for contralateral limb compared to the control group.

CONCLUSION

In children with ACL injury, abnormal gait patterns persist two years after ligament reconstruction, in spite of extensive rehabilitation and no clinical complaints. These findings might guide neuromuscular training to improve clinical outcomes and reduce the rerupture rate.

Muscle dynamics analysis by clustered categories during jogging in patients with anterior cruciate ligament deficiency

BACKGROUND

Patients with anterior cruciate ligament (ACL) deficiency (ACLD) tend to have altered lower extremity dynamics. Little is known about the changes in dynamic function and activation during jogging in patients with ACLD.

METHODS

Twenty patients with an injured ACL before ACL reconstruction (ACLD group) and nine healthy male volunteers (control group) were recruited. Each volunteer repeated the jogging experiment five times. Based on the experimental data measured, a musculoskeletal multibody dynamics model was employed to simulate the tibiofemoral joint dynamics during jogging. Eighteen muscles were used for analysis. The obtained dynamics data were used for clustering and curve difference analysis.

RESULTS

The 18 muscles studied were divided into 3 categories. All the quadriceps, the soleus, the gastrocnemius, and the popliteus were classified as label 1. All the hamstrings were classified as label 2, and the sartorius muscles were classified as label 3. Among them, the classification of the short head of the biceps femoris was significantly different between the two groups (P < 0.001). The force curves of all 18 muscles and the between-group differences were studied according to clustered categories. Most muscle force in label 1 was approaching zero in the terminal stance phase, which was significantly lower than that in the control group (P < 0.05). The muscle force in label 2 had areas with significant differences in the stance phase. Muscle force in label 3 was significantly lower than that in the control group in the pre-swing phase.

CONCLUSIONS

This study showed that there are various changes of muscle function and activation in patients with ACLD. Through clustering and curve analysis, the joint reactions and changes of different muscle forces in the gait cycle between the ACLD and control groups could be further clarified.

Pain Early After Anterior Cruciate Ligament Reconstruction is Associated With 6-Month Loading Mechanics During Running

BACKGROUND

Anterior cruciate ligament reconstruction (ACLR) results in persistent altered knee biomechanics, but contributing factors such as pain or patient function, leading to the altered loading, are unknown.

HYPOTHESIS

Individuals with worse self-reported pain after ACLR would have poorer biomechanics during running, and poor loading mechanics would be present in the ACLR limb compared with contralateral and control limbs.

STUDY DESIGN

Cohort pilot study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 20 patients after ACLR (age, 18.4 ± 2.7 years; height, 1.7 ± 0.1 m; mass, 84.2 ± 19.4 kg) completed visual analog scale and Knee Injury and Osteoarthritis Outcomes Score (KOOS) at 1 and 6 months postsurgery. At 6 months postsurgery, patients underwent biomechanical testing during running. A total of 20 control individuals also completed running biomechanical analyses. Associations between patient outcomes and biomechanics were conducted, and differences in running biomechanics between groups were analyzed.

RESULTS

KOOS pain score 1 month after surgery was associated with peak ACLR knee abduction moment (R2 = 0.35;P = 0.01). At 6-months, KOOS sport score was related to peak abduction moment in the ACLR limb (R2 = 0.23; P = 0.05). For change scores, the improvement in pain scores related to ACLR limb peak knee abduction moment (R2 = 0.55; P = 0.001). The ACLR limb had lower knee excursion, extension moments, and ground-reaction forces compared with the uninvolved and control limb. The uninvolved limb also had higher ground-reaction forces compared with the ACLR limb and control limb.

CONCLUSION

These results suggest that patient-reported outcomes 1 and 6 months after surgery are associated with running mechanics 6 months after ACLR. Further, the underloading present in the ACLR limb and overloading in the uninvolved limb indicates greater need for running rehabilitation after ACLR.

CLINICAL RELEVANCE

Understanding pain and how it may be linked to movement dysfunction is important for improving long-term outcomes.

Neuromuscular activity of the lower-extremities during running, landing and changing-of-direction movements in individuals with anterior cruciate ligament reconstruction: a review of electromyographic studies

PURPOSE

Running, jumping/landing and cutting/change of direction (CoD) are critical components of return to sport (RTS) following anterior cruciate ligament reconstruction (ACLR), however the electromyographic (EMG) activity patterns of the operated leg during the execution of these tasks are not clear.

METHODS

A systematic review was conducted to retrieve EMG studies during running, jumping/landing and cutting/(CoD) in ACLR patients. MEDLINE, PubMed, SPORTDiscus and Web of Science databases were searched from 2000 to May, 2022 using a combination of keywords and their variations: "anterior cruciate ligament reconstruction" OR "ACLR", "electromyography" OR "EMG", "running", "jumping" OR "landing", "cutting" OR "change-of-direction" OR "CoD". The search identified studies comparing EMG data during running, landing and cutting/(CoD) between the involved limb and contralateral or control limbs. Risk of bias was assessed and quantitative analyses using effect sizes were performed.

RESULTS

Thirty two studies met the inclusion criteria. Seventy five percent (24/32) of the studies reported altered EMG activity pattern of the ACLR leg during running, jumping/landing and cutting/(CoD) when compared with either the healthy control leg or the contra-lateral leg. Twelve studies showed decreased, delayed or earlier onset and delayed peak in quadriceps EMG activity with small to large effect sizes and 9 studies showed increased, delayed or earlier onset and delayed peak in hamstrings EMG activity with small to large effect sizes. Four studies showed a "hamstrings-dominant" strategy i.e. decreased quadriceps coupled with increased hamstrings EMG activity in both running and jumping/landing irrespective of graft type. One study reported that on the grounds of decreased quadriceps activity, lower hamstrings EMG activity was predictive of ipsilateral re-injury in ACLR patients.

CONCLUSION

This systematic review of Level III evidence showed that the ACLR leg displays decreased quadriceps or increased hamstrings EMG activity or both despite RTS. Simultaneous decreased quadriceps and increased hamstrings EMG activity was shown for both running and jumping/landing. From a clinical perspective this "hamstrings dominant" strategy can serve as a protective mechanism against graft re-injury.

LEVEL OF EVIDENCE

III.

Leveraging Multivariable Linear Regression Analysis to Identify Patients with Anterior Cruciate Ligament Deficiency Using a Composite Index of the Knee Flexion and Muscle Force

Patients with anterior cruciate ligament (ACL) deficiency (ACLD) tend to have altered lower extremity kinematics and dynamics. Clinical diagnosis of ACLD requires more objective and convenient evaluation criteria. Twenty-five patients with ACLD before ACL reconstruction and nine healthy volunteers were recruited. Five experimental jogging data sets of each participant were collected and calculated using a musculoskeletal model. The resulting knee flexion and muscle force data were analyzed using a t-test for characteristic points, which were the time points in the gait cycle when the most significant difference between the two groups was observed. The data of the characteristic points were processed with principal component analysis to generate a composite index for multivariable linear regression. The accuracy rate of the regression model in diagnosing patients with ACLD was 81.4%. This study demonstrates that the multivariable linear regression model and composite index can be used to diagnose patients with ACLD. The composite index and characteristic points can be clinically objective and can be used to extract effective information quickly and conveniently.

Native knee kinematics is not reproduced after sensor guided cruciates substituting total knee arthroplasty

PURPOSE

Gait analysis was used to evaluate knee kinematics in patients who underwent successful primary total knee arthroplasty (TKA) using two modern bi-cruciate substituting designs. The knee joint was balanced intraoperatively using real-time sensor technology, developed to provide dynamic feedback regarding stability and tibiofemoral load. The authors hypothesized that major differences exist in gait parameters between healthy controls and post-TKA patients.

METHODS

Ten patients who underwent successful TKA using bi-cruciate substituting designs were evaluated at a minimum of 9 months postoperatively using three-dimensional knee kinematic analysis; a multi-camera optoelectronic system and a force platform were used. Sensor-extracted kinematic data included knee flexion angle at heel-strike (KFH), peak midstance knee flexion angle (MSKFA), maximum and minimum knee adduction angle (KAA) and knee rotational angle at heel-strike. Multiple gait analysis data from the study group were compared to a group of ten healthy controls who were matched by age, sex and BMI. Clinical outcome in the TKA group was also measured using the Knee injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

Clinically, at final follow-up, a statistically significant difference in pain, general symptoms, and activities of daily living was seen between the groups. From a gait analysis standpoint, TKA patients had significantly less rotation at heel strike (p = 0.04), lower late stance peak extension moments (p = 0.02), and less Knee Adduction Angle excursion during swing phase (p = 0.04) compared to the control group. No statistically significant difference was observed for knee flexion angle at heel strike, knee adduction moment, or peak knee flexion moment between the groups.

CONCLUSIONS

Modern bi-cruciate substituting TKA designs failed to reproduce normal knee kinematics. The lack of full knee extension during the stance phase, absence of the "screw-home mechanism" typical of an ACL functioning knee, and the reduced fluctuation in knee adduction angle during the swing phase still represent major proprioceptive and muscular recruitment differences between normal and replaced knees.

Tolerable degree of muscle sacrifice when harvesting a vastus lateralis or myocutaneous anterolateral thigh flap

The myocutaneous anterolateral thigh (ALT) and vastus lateralis (VL) flaps include a large muscle mass and a sufficient vascular pedicle, and they have been used for decades to reconstruct traumatic and acquired defects of the head and neck and extremities. In spite of these benefits, musculoskeletal dysfunction was reported in nearly 1 out of 20 patients at follow-up. It is unclear whether the recently proposed muscle-sparing flap-raising approach could preserve VL muscle function and whether patients at increased risk could benefit from such an approach. Therefore, we performed a predictive dynamic gait simulation based on a biological motion model with gradual weakening of the VL during a self-selected and fast walking speed to determine the compensable degree of VL muscle reduction. Muscle force, joint angle, and joint moment were measured. Our study showed that VL muscle reduction could be compensated up to a certain degree, which could explain the observed incidence of musculoskeletal dysfunction. In elderly or fragile patients, the VL muscle should not be reduced by 50% or more, which could be achieved by muscle-sparing flap-raising of the superficial partition only. In young or athletic patients, a VL muscle reduction of 10%, which corresponds to a muscle cuff, has no relevant effect. Yet, a reduction of more than 30% leads to relevant weakening of the quadriceps. Therefore, in this patient population with the need for a large portion of muscle, alternative flaps should be considered. This study can serve as the first basis for further investigations of human locomotion after flap-raising.

Identification of Kinetic Abnormalities in Male Patients after Anterior Cruciate Ligament Deficiency Combined with Meniscal Injury: A Musculoskeletal Model Study of Lower Limbs during Jogging

There is little known about kinetic changes in anterior cruciate ligament deficiency (ACLD) combined with meniscal tears during jogging. Therefore, 29 male patients with injured ACLs and 15 healthy male volunteers were recruited for this study to investigate kinetic abnormalities in male patients after ACL deficiency combined with a meniscal injury during jogging. Based on experimental data measured by an optical tracking system, a subject-specific musculoskeletal model was employed to estimate the tibiofemoral joint kinetics during jogging. Between-limb and interpatient differences were compared by the analysis of variance. The results showed that decreased knee joint forces and moments of both legs in ACLD patients were detected during the stance phase compared to the control group. Meanwhile, compared with ACLD knees, significantly fewer contact forces and flexion moments in ACLD combined with lateral and medial meniscal injury groups were found at the mid-stance, and ACLD with medial meniscal injury group showed a lower axial moment in the loading response (p < 0.05). In conclusion, ACLD knees exhibit reduced tibiofemoral joint forces and moments during jogging when compared with control knees. A combination of meniscus injuries in the ACLD-affected side exhibited abnormal kinetic alterations at the loading response and mid-stance phase.

Impact Analysis of Basketball Exercise Strength Based on Machine Learning in the Mental Health of College Students

In the current environment of globalization, the communication between people is gradually getting closer, and the society is becoming more and more complex. With the continuous development and progress of science and technology, people are more skilled in applying science and technology to their own concerns. College students are about to enter the society, will feel multiple pressure from family, school, and society, study and life problems will gradually convert into mental health problems, and we need to use machine learning basketball exercise to positively affect the mental health quality of college students. The improvement of living conditions makes people pay more attention to their physical and mental health, and learn to use machine learning sports reasonably, not only basketball exercise, to improve mental health diseases. However, we need to use machine learning to identify the different effects of different basketball exercise intensity on mental health, in order to ensure that the most appropriate basketball exercise intensity brings good aspects to the mental health of college students. Through the investigation and data sampling, it can be concluded that the machine learning-based basketball exercise intensity has a positive impact on the mental health of college students.

Quadriceps Muscle Action and Association With Knee Joint Biomechanics in Individuals with Anterior Cruciate Ligament Reconstruction

Insufficient quadriceps force production and altered knee joint biomechanics after anterior cruciate ligament reconstruction (ACLR) may contribute to a heightened risk of osteoarthritis. Quadriceps muscle lengthening dynamics affect force production and knee joint loading; however, no study to our knowledge has quantified in vivo quadriceps dynamics during walking in individuals with ACLR or examined correlations with joint biomechanics. Our purpose was to quantify bilateral vastus lateralis (VL) fascicle length change and the association thereof with gait biomechanics during weight acceptance in individuals with ACLR. The authors hypothesized that ACLR limbs would exhibit more fascicle lengthening than contralateral limbs. The authors also hypothesized that ACLR limbs would exhibit positive correlations between VL fascicle lengthening and knee joint biomechanics during weight acceptance in walking. The authors quantified VL contractile dynamics via cine B-mode ultrasound imaging in 18 individuals with ACLR walking on an instrumented treadmill. In partial support of our hypothesis, ACLR limb VL fascicles activated without length change on average during weight acceptance while fascicle length on the contralateral limb decreased on average. The authors found a positive association between fascicle lengthening and increase in knee extensor moments in both limbs. Our results suggest that examining quadriceps muscle dynamics may elucidate underlying mechanisms relevant to osteoarthritis.

Gait Pathology in Subjects with Patellofemoral Instability: A Systematic Review

Identifying potential gait deviations in patellofemoral instability (PI) can help with the development of effective rehabilitation strategies. The purpose of this systematic review was to examine whether there are specific gait alterations in subjects with PI. The present review followed the PRISMA guidelines and was initially registered at PROSPERO (CRD42021236765). The literature search was carried out in the databases of PubMed, the Cochrane library, Web of Science, ClinicalTrials.gov, and Medline. The search strategy resulted in the identification of seven relevant publications. Subjects with PI show decreased walking speed, stride length, and cadence. Some studies reported changes not only in knee kinematics and kinetics but also in hip and ankle kinematics and kinetics. There is evidence that most subjects with PI walk with a quadriceps avoidance gait and show increased genu valgum posture, but there is still great variability in the coping responses within individuals with PI. The discrepancy among the study results might underpin the fact that PI is a multifactorial problem, and subjects cope with the different underlying morphological as well as functional deficits using a variety of gait strategies, which makes the interpretation and understanding of the gait of subjects with PI a clinically challenging task.

Effect of Time After Injury on Tibiofemoral Joint Kinematics in Anterior Cruciate Ligament-Deficient Knees During Gait

Background:

Anterior cruciate ligament (ACL) injury can lead to changes in tibiofemoral kinematics during gait, but the detailed short-term kinematic changes after ACL injury are still unknown.

Purpose:

To measure tibiofemoral kinematics during gait in ACL-deficient (ACLD) knees over time after ACL injury.

Study Design:

Controlled laboratory study.

Methods:

The authors categorized 76 patients with unilateral ACLD knees into 4 groups based on the time from injury: <3 months (group 1), 3 to 6 months (group 2), >6 to 12 months (group 3), and >12 months (group 4). The controls were 20 participants with ACL-intact knees. Changes in the knee kinematics and range of motion during gait were compared among ACLD groups and those with ACL-intact knees.

Results:

Compared with controls, the range of motion of flexion in group 1 was significantly lower (6°; P = .033), and the mean knee flexion was significantly increased (0.7°-3.4°) in groups 1 to 4 (all P ≤ .004). There was more internal tibial rotation (2.9°-4.3°) in group 1 and 2, and more anterior tibial translation (4.3 mm) in group 1 during the stance or swing phases than in controls (P ≤ .049 for all). The mean internal tibial rotation and anterior tibial translation significantly decreased from group 1 to group 4 (P < .001 for both). Compared with controls, the mean medial tibial translation was significantly greater (1.2-2.5 mm) in all groups, and more medial tibial translations (2.4-3.7 mm) were observed during the stance phase in groups 1, 3, and 4 (P ≤ .047 for all).

Conclusion:

ACLD knees displayed a motion impairment walking strategy within 3 months, and a higher-flexion walking strategy increased with time after injury. Excessive anterior translation and internal rotation of the tibia tended to return to normal, while excessive medial translation of the tibia increased in ACLD knees after 6 months postinjury. These results may provide new insight into the compensatory mechanisms and risk factors for premature osteoarthritis in ACLD knees.

Impact of Rehabilitation on Gait Kinematic following Grade II Anterior Cruciate Ligament Injury among Wrestlers

Background

Anterior cruciate ligament (ACL) injuries are among the most common injuries in wrestling. Even though there are several studies available in the literature about the changes in gait kinematics following ACL injury and ACL reconstruction surgery, none of these studies investigated the changes in gait kinematics following nonoperative rehabilitation protocol. So, this study is aimed at investigating the changes in gait kinematic following a supervised ACL rehabilitation protocol among wrestlers following a grade II ACL injury.

Methods

Fifteen male professional wrestlers with recent grade II ACL injury with mean age: 19.93 ± 2.01 years, weight: 72.33 ± 7.46 kg, and height: 173 ± 4.95 cm volunteered for this single-arm pretest-posttest study. Kinematic parameters during walking pre- and postrehabilitation were examined by two-dimensional (2D) video graphic analysis. Paired sample t-test and Cohen's d were used to determine significant differences and effect size of segmental angle, cadence, step length, stride length, etc.

Results

Injured wrestlers after the rehabilitation program walked significantly faster and had a 10.13% higher cadence, a 10.89% faster gait velocity, a 05% greater step length, and a 4.69% longer stride length, compared with a prerehabilitation program of injured wrestlers. Furthermore, joint angles at the hip, knee, and ankle were significantly different between pre- and postrehabilitation.

Conclusion

Research findings suggest that rehabilitation programs significantly impact the gait pattern of injured wrestlers. A 19-week supervised rehabilitation protocol can increase gait velocity and related parameters in ACL injured wrestlers.

Comparison of the knee joint reaction force between individuals with and without acute anterior cruciate ligament rupture during walking

Background

Anterior cruciate ligament plays a significant role in knee joint stability. It is claimed that the incidence of knee osteoarthritis increases in individuals with anterior cruciate ligament (ACL) rupture. The aim of this study was to evaluate the knee joints reaction force in ACL rupture group compared to normal subjects.

Method

Fifteen patients with acute ACL rupture and 15 healthy subjects participated in this study. The ground reaction force (GRF) and kinematic data were collected at a sampling rate of 120 Hz during level-ground walking. Spatiotemporal parameters, joint angles, muscle forces and moments, and joint reaction force (JRF) of lower extremity were analyzed by OpenSIM software.

Results

The hip, knee and ankle joints reaction force at loading response and push-off intervals of the stance phase during walking was significantly higher in individuals with ACL rupture compared to healthy controls (p value < 0.05). Walking velocity (p value < 0.001), knee (p value = 0.065) and ankle (p value = 0.001) range of motion in the sagittal plane were significantly lower in the patients with ACL rupture compared to healthy subjects. The mean value of vertical GRF in the mid-stance, the peak of the hip adduction moment in loading response and push-off phases, the hip abductor, knee flexor and vastus intermedius part of quadriceps muscle forces were significantly higher compared to healthy subjects (p < 0.05) while vastus medialis and vastus lateralis produced significantly lower force (p < 0.001).

Conclusions

Based on results of this study, lower limb JRF was higher in those with ACL rupture compared to healthy subjects may be due to the compensatory mechanisms used by this group of subjects. An increase in knee JRF in patients with ACL rupture may be the reason for the high incidence of knee OA.

Effect of knee joint loading on chondrocyte mechano-vulnerability and severity of post-traumatic osteoarthritis induced by ACL-injury in mice

Objective

The objective of this study is to understand the role of altered in vivo mechanical environments in knee joints post anterior cruciate ligament (ACL)-injury in chondrocyte vulnerability against mechanical stimuli and in the progression of post-traumatic osteoarthritis (PT-OA).

Methods

Differential in vivo mechanical environments were induced by unilateral ACL-injury (uni-ACL-I) and bilateral ACL-injury (bi-ACL-I) in 8-week-old female C57BL/6 mice. The gait parameters, the mechano-vulnerability of in situ chondrocytes, Young's moduli of cartilage extracellular matrix (ECM), and the histological assessment of OA severity (OARSI score) were compared between control and experimental groups at 0∼8-weeks post-ACL-injury.

Results

We found that bi-ACL-I mice experience higher joint-loading on their both injured limbs, but uni-ACL-I mice balance their joint-loading between injured and uninjured hind limbs resulting in a reduced joint-loading during gait. We also found that at 4- and 8-week post-injury the higher weight-bearing hind limbs (i.e., bi-ACL-I) had the increased area of chondrocyte death induced by impact loading and higher OARSI score than the lower weight-bearing limbs (uni-ACL-I). Additionally, we found that at 8-weeks post-injury the ECM became stiffer in bi-ACL-I joints and softer in uni-ACL-I joints.

Conclusions

Our results show that ACL-injured limbs with lower in vivo joint-loading develops PT-OA significantly slower than injured limbs with higher joint-loading during gait. Our data also indicate that articular chondrocytes in severe PT-OA are more fragile from mechanical impacts than chondrocytes in healthy or mild PT-OA. Thus, preserving physiologic joint-loads on injured joints will reduce chondrocyte death post-injury and may delay PT-OA progression.

Anterior knee pain independently alters landing and jumping biomechanics

Background Biomechanical effects of anterior knee pain are difficult to distinguish from effects of other factors also related to knee injury (e.g., joint effusion). The purpose of this study was to evaluate independent effects of anterior knee pain on landing and jumping biomechanics. Methods Thirteen healthy participants performed a land and jump movement task, under three experimental conditions (pre-pain, pain, and post-pain), during one data collection session. One 1-ml injection of hypertonic saline into the infrapatellar fat pad was used to induce experimental anterior knee pain during the pain condition. Participant-perceived anterior knee pain was measured every 2 min throughout data collection. Landing and jumping biomechanics were measured and compared between the experimental conditions using a functional statistical approach. Findings The aforementioned injection increased mean participant-perceived anterior knee pain, from zero during the pre-pain condition to 2.6 ± 0.71 cm during the pain condition. Vertical ground reaction force, knee flexion angle, and internal knee extension moment decreased by approximately 0.100 body weights, 3°, and 0.010 Nm/body weight × body height, respectively, between the pre-pain and pain conditions. Conversely, hip flexion angle and internal hip extension moment increased by approximately 3° and 0.006 Nm/body weight × body height, respectively, between the pre-pain and pain conditions. Several biomechanical changes persisted after anterior knee pain abatement (the post-pain condition). Interpretation Anterior knee pain alters landing and jumping biomechanics, independent of other injury-related factors. These altered biomechanics likely change knee joint loading patterns and might increase risk for chronic knee joint injury and/or pathology.

Are there different gait profiles in patients with advanced knee osteoarthritis? A machine learning approach

BACKGROUND

Determine whether knee kinematics features analyzed using machine-learning algorithms can identify different gait profiles in knee OA patients.

METHODS

3D gait kinematic data were recorded from 42 patients (Kellgren-Lawrence stages III and IV) walking barefoot at individual maximal gait speed (0.98 ± 0.34 m/s). Principal component analysis, self-organizing maps, and k-means were applied to the data to identify the most relevant and discriminative knee kinematic features and to identify gait profiles.

FINDINGS

Four different gait profiles were identified and clinically characterized as type 1: gait with the knee in excessive varus and flexion (n = 6, 14%, increased knee adduction and increased maximum and minimum knee flexion, p < 0.01); type 2: gait with knee external rotation, either in varus or valgus (n = 11, 26%, excessive maximum and minimum external rotation, p < 0.001); type 3: gait with a stiff knee (n = 17, 40%, decreased knee flexion range of motion, p < 0.001); and type 4: gait with knee varus 'thrust' and decreased rotation (n = 8, 19%, increased and reduced range of motion in the coronal and transverse plane, respectively, p < 0.05).

INTERPRETATION

In a group of patients with homogeneous Kellgren-Lawrence classification of knee OA, gait kinematics data permitted to identify four different gait profiles. These gait profiles can be a valuable tool for helping surgical decisions and treatment. To allow generalization, further studies should be carried with a larger and heterogeneous population.

In vivo three-dimensional knee kinematics in goats with unilateral anterior cruciate ligament transection

Although the goat is an established animal model in anterior cruciate ligament (ACL) research, in vivo kinematics associated with ACL deficiency have not been previously described in this species. Three-dimensional knee kinematics were determined before and after unilateral ACL transection in eight goats. Fluoroscopic imaging of the knees during treadmill walking and force-platform gait analysis during over-ground walking were performed prior to ACL transection, and 2 weeks, 3 months, and 6 months after ACL transection. Transient lameness of the ACL-transected limb was noted in all goats but resolved by 3 months post-ACL transection. Increased extension of 8.7° to 17.0° was noted throughout the gait cycle in both the ACL-transected and the contralateral unaffected knees by 3 months post-ACL transection, in a bilaterally symmetric pattern. Peak anterior tibial translation increased by 3 to 6 mm after ACL transection and persisted over the 6-month study period. No changes in axial rotation or abduction angle were observed after ACL transection. Unilateral ACL deficiency in goats resulted in persistent kinematic alterations, despite the resolution of lameness by 3 months post-ACL transection.

Evaluation of the Asymmetry of Leg Muscles Forces in the Subjects with Anterior Cruciate Ligament Reconstruction

Running asymmetry has not been assessed among patients with anterior cruciate ligament (ACL) deficiency. The aim of this study was to evaluate the spatiotemporal and muscle force asymmetry indexes in the subjects with ACL reconstruction (ACLR) compared with normal subjects. Eight individuals with a reconstructed ACL and eight individuals with intact ACLs were participated in this study. A Vicon motion analysis system and two Kistler force plates were used to record data. Muscle forces analysis was done by the use of OpenSim software. The results of this study showed that ACLR group had a significant weakness in hip abductor, extensor, and adductor muscles of the affected limb compared with healthy subjects (p < 0.05). In ACLR group, asymmetry of gluteus minimus muscle force was significantly greater than that of healthy group (p = 0.04). After the reconstruction of the ACL, there is still a significant asymmetry in muscle force as well as a reduction in force production of ACLR group especially in reconstructed side which put a person at high risk of reinjuries. Thus, strengthening of these muscles on the affected side to increase running performance of ACLR group is recommended.

Knee flexion angle and muscle activations control the stability of an anterior cruciate ligament deficient joint in gait

Anterior cruciate ligament (ACL) is a primary structure and a commonly injured ligament of the knee joint. Some patients with ACL deficiency (ACLD) experience joint instability and require a reconstructive surgery to return to daily routines, some can adapt by limiting their activities while others, called copers, can return to high-level activities with no instability. We investigated the effects of alterations in the knee flexion angle (KFA) and muscle force activations on the stability and biomechanics of ACLD joints at 25, 50, and 75% periods of gait stance. ACLD joint stability is controlled by variations in both KFA and knee muscle forces. For the latter, a parameter called activity index is defined as the ratio of forces in ACL antagonists (quadriceps and gastrocnemii) to those in ACL agonists (hamstrings). Under a greater KFA (2-6° beyond the mean of reported values in healthy subjects), an ACLD joint regains its pre-injury stability levels. The ACLD joint stability also markedly improves at smaller quadriceps and larger hamstrings forces (activity indices of 2.0-3.6 at 25%) at the first half of stance and smaller gastrocnemii and larger hamstrings forces (activity indices of 0.1-1.1 at 50% and 0.1-1.2 at 75%) at the second half of stance. Activity index and KFA are both crucial when assessing the dynamic stability of an ACLD joint. These results are helpful in our understanding of the biomechanics and stability of ACLD joints towards improved prevention and treatment strategies.

Quadriceps Oxygenation During Exercise in Patients With Anterior Cruciate Ligament Reconstruction

CONTEXT

The causes of persistent muscle weakness after anterior cruciate ligament reconstruction (ACLR) are not well known. Changes in muscle oxygenation have been proposed as a possible mechanism.

OBJECTIVE

To investigate changes in quadriceps muscle oxygenation during knee extension in ACLR-involved and ACLR-uninvolved limbs.

DESIGN

Case-control study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 20 individuals: 10 patients with primary, unilateral ACLR (7 women, 3 men; age = 22.90 ± 3.45 years, height = 170.81 ± 7.93 cm, mass = 73.7 ± 15.1 kg) and 10 matched control individuals (7 women, 3 men; age = 21.50 ± 2.99 years, height = 170.4 ± 10.7 cm, mass = 68.86 ± 9.51 kg).

INTERVENTION(S)

Each participant completed a single data-collection session consisting of 5-second isometric contractions at 25%, 50%, and 75% of the volitional maximum followed by a 30-second maximal isometric knee-extension contraction.

MAIN OUTCOME MEASURE(S)

Oxygenated hemoglobin (O2Hb) measures in the reconstructed thigh were continuously recorded (versus the uninvolved contralateral limb as well as the nondominant thigh of healthy control individuals) using 3 wearable, wireless near-infrared spectroscopy units placed superficially to the vastus medialis, vastus lateralis, and rectus femoris muscles. Relative changes in oxygenation were ensemble averaged and plotted for each contraction intensity with associated 90% confidence intervals (CIs). Statistical significance occurred where portions of the exercise trials with confidence intervals on the O2Hb graph did not overlap. Effect sizes (Cohen d, 90% CI) were determined for statistical significance.

RESULTS

We observed less relative change in O2Hb in patients with ACLR than in healthy control participants in the rectus femoris at 25% (d = 2.1; 90% CI = 1.5, 2.7), 50% (d = 2.8; 90% CI = 2.6, 2.9), and 75% (d = 2.0; 90% CI = 1.9, 2.2) and for the vastus medialis at 75% (d = 1.5; 90% CI = 1.4, 1.5) and 100% (d = 2.6; 90% CI = 2.5, 2.7). Less relative change in O2Hb was also noted for the vastus medialis in ACLR-involved versus ACLR-uninvolved limbs at 100% (d = 2.62; 90% CI = 2.54, 2.70).

CONCLUSIONS

Quadriceps muscle oxygenation during exercise differed between patients with ACLR versus healthy control individuals. However, not all portions of the quadriceps were affected uniformly across contraction intensities.

The influence of body mass index and sex on frontal and sagittal plane knee mechanics during walking in young adults

BACKGROUND

Obesity and female sex are independent risk factors for knee osteoarthritis and also influence gait mechanics. However, the interaction between obesity and sex on gait mechanics is unclear, which may have implications for tailored gait modification strategies.

RESEARCH QUESTION

The purpose of this study was to examine the influence of obesity and sex on sagittal and frontal plane knee mechanics during gait in young adults.

METHODS

Forty-eight individuals with (BMI = 33.03 ± 0.59; sex:50 % female; age:21.9 ± 2.6 years) and 48 without obesity (BMI:21.59 ± 0.25; sex:50 % female; age:22.9 ± 3.57 years) matched on age and sex completed over-ground gait assessments at a self-selected speed. Two (BMI) by two (sex) analysis of variance was used to compare knee biomechanics during the first half of stance in the sagittal (knee flexion moment [KFM] and excursion [KFE]) and frontal plane (first peak knee adduction moment [KAM], knee varus velocity [KVV]).

RESULTS

We observed a BMI by sex interaction for normalized KFM (P = 0.03). Females had smaller normalized KFM compared to males (P = 0.03), but only in individuals without obesity. Males without obesity had larger normalized KFM compared to males with obesity (P = 0.01), while females did not differ between BMI groups. We observed main effects of sex and BMI group, where females exhibited greater normalized KAM (P < 0.01) and KVV (P < 0.01) compared to males, and individuals with obesity walked with greater KVV compared to those without obesity (P < 0.01). All absolute joint moments were greater in individuals with obesity (all P<0.01) and males had greater absolute KFM compared to females (P < 0.01).

SIGNIFICANCE

We observed sex differences in gait mechanics, however, KFM differences between males and females were only evident in individuals without obesity. Further, females and individuals with obesity had a larger KAM and KVV, which may contribute to larger medial compartment joint loading.

Autograft type affects muscle strength and hop performance after ACL reconstruction. A randomised controlled trial comparing patellar tendon and hamstring tendon autografts with standard or accelerated rehabilitation

PURPOSE

To evaluate and compare changes in quadriceps and hamstring strength and single-leg-hop (SLH) test performance over the first 24 postoperative months in patients who underwent anterior cruciate ligament reconstruction (ACLR) with bone-patellar tendon-bone (BPTB) or hamstring tendon (HT) autografts and followed either a standard or an accelerated rehabilitation protocol.

METHODS

A total of 160 patients undergoing ACLR were randomised in four groups depending on the graft that was used and the rehabilitation protocol (40 BPTB/standard rehab, 40 BPTB/accelerated rehab, 40 HT/standard rehab, 40 HT/accelerated rehab). Isokinetic concentric quadriceps and hamstring strength at 90°/s and the SLH test performance were assessed preoperatively and 4,6,8,12 and 24 months postoperatively. The results were reported as the limb symmetry index (LSI) at the same time point. Linear mixed models were used to compare the groups at the different time points.

RESULTS

An average quadriceps strength LSI of 78.4% was found preoperatively. After ACLR, the LSI first decreased at 4 months and then increased from 6 to 24 months, reaching an overall value of 92.7% at the latest follow-up. The BPTB group showed a significantly decreased LSI at 4, 6, 8 and 12 months compared with the HT group. No significant differences between the graft groups were found at 24 months. An average hamstring strength LSI of 84.6% was found preoperatively. After ACLR, the LSI increased from 4 to 24 months in the BTPB group. In the HT group, the LSI first decreased at 4 months and then increased from 6 to 24 months. An LSI of 97.1% and 89.1% was found at the latest follow-up for the BPTB and the HT group, respectively. The HT group showed a significantly decreased LSI at all follow-ups compared with the BPTB group. An average SLH test LSI of 81% was found preoperatively. After ACLR, the LSI increased from 4 to 24 months, reaching 97.6% overall at the latest follow-up. The BPTB group showed a significantly decreased LSI only at 4 months postoperatively compared with the HT group. No significant differences in any of the three tests were found between the standard and accelerated rehabilitation groups for either of the graft groups at any time point.

CONCLUSION

Muscle strength and SLH test performance recovered progressively after ACLR overall, but they did not all fully recover, as the injured leg performed on average less than 100% compared with the uninjured leg even 24 months postoperatively. After ACLR, inferior quadriceps strength and a poorer SLH test performance were found at 4, 6, 8 and 12 months and at 4 months, respectively, for the BTPB group compared with the HT group. Persistent, inferior hamstring strength was found at all postoperative follow-ups in the HT group. Rehabilitation, standard or accelerated, had no significant impact on the recovery of muscle strength and SLH test performance after ACLR in any of the graft groups.

LEVEL OF EVIDENCE

Level I.

Altered Neuromuscular Activity of the Lower-Extremities During Landing Tasks in Patients With Anterior Cruciate Ligament Reconstruction: A Systematic Review of Electromyographic Studies

CONTEXT

Altered lower-limb biomechanics have been observed during landing task in patients with anterior cruciate ligament reconstruction (ACLR), which increases the risk of secondary anterior cruciate ligament injury. However, the alteration in neuromuscular activity of the lower-extremity during landing task is not clear.

OBJECTIVE

To compare the muscle activity pattern assessed by electromyography between the involved limb of patients with ACLR and the contralateral limb or control limb of matched healthy subjects during landing task.

EVIDENCE ACQUISITION

Database of PubMed, Ovid, Scopus, and Web of Science from the inception of the databases until July 2019, using a combination of keywords and their variations: (anterior cruciate ligament OR ACL) AND (electromyography OR EMG) AND (landing OR land). Studies that assessed lower-extremity muscle activity patterns during landing task in patients with ACLR and compared them either with the contralateral side or healthy controls were included.

EVIDENCE SYNTHESIS

Of the 21 studies, 16 studies reported altered muscle activity pattern during landing tasks when compared with either the healthy controls or the contralateral side. For the specific muscle activity patterns, the majority of the studies showed no significant difference in reactive muscle activity, and comparisons across studies revealed a possible trend toward the early onset of quadriceps and hamstring activity and increased cocontraction of the involved limb. There are inconsistent findings regarding the alteration in muscle timing and preparatory muscle activity.

CONCLUSIONS

Patients with ACLR displayed an altered muscle activity pattern during landing tasks, even though they were considered to be capable for sport return. Nevertheless, a firm conclusion could not be drawn due to great heterogeneity in the subject selection and study methods.

Kinematics and center of axial rotation during walking after medial pivot type total knee arthroplasty

PURPOSE

In recent years, the medial pivot (MP) type total knee arthroplasty (TKA) implant has been developed and marketed for achieving more natural kinematics with MP. However, little is known about the pivot pattern during walking after MP type TKA. This study aimed to determine the kinematics and center of axial rotation during walking after MP type TKA.

METHODS

This randomized prospective study enrolled 40 patients with MP type TKA, 20 with cruciate-substituting TKA (MP-CS group), 20 with posterior-stabilized TKA (MP-PS group), and 10 healthy volunteers (control group). The kinematics and center of axial rotation during overground walking were measured by a three-dimensional motion analysis system. The six-degrees-of-freedom kinematics of the knee were calculated by the point cluster method.

RESULTS

The amount of change in knee flexion in early stance phase was significantly lower in the MP-CS and MP-PS groups than in the control group. The femur showed anterior translation during early stance phase in all three groups. The median center of axial rotation in the transverse plane was predominantly on the lateral side of the knee during stance in all groups.

CONCLUSIONS

Kinematics during gait are thought to be determined by physical posture, the kinetic chain during weight-bearing, and the kinematic features of adjacent structures, such as the behavior of the biarticular muscles. MP-CS and MP-PS did not necessarily induce rotational motion centered on the medial ball-in-socket component during walking; translational and lateral pivoting movements were also observed. Long-term follow-up is needed to monitor for polyethylene wear and implant loosening.

Use of the normalcy index for the assessment of abnormal gait in the anterior cruciate ligament deficiency combined with meniscus injury

The normalcy index (NI) has been implemented by several studies as a simple index for quantitatively analyzing diffident gait abnormalities, such as children with cerebral palsy and idiopathic toe-walkers. However, whether the NI can be used in anterior cruciate ligament (ACL) deficiency with different types of meniscus injuries or not, has not been reported yet. In this study, 25 patients who combined different types of ACL and meniscus injuries were evaluated by the NI analysis. 12 healthy subjects were used to define the normal range of NI. The result showed that NI values of patients were significantly larger than the control group (P < 0.05). Meanwhile, the tendency of increasing NI values associated with increasing pathology were significant with only 5 subjects in the smallest group (Jonkheere-Terpsta test: P < 0.001). These results indicated that the NI was a concise yet effective tool to evaluate combined ACL and meniscus injury patients. Increasing severity degree of meniscus tears in ACL rupture patients is corresponded to increasing NI values. It also demonstrates that the proposed NI can be applied as a robustness factor to detect the discrepancy between healthy and patient subjects clinically, and has the potential in the quantitative evaluation of pre- or post-surgery and rehabilitation.

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.

Trochleoplasty improves knee flexion angles and quadriceps function during gait only if performed bilaterally

PURPOSE

To investigate if a trochleoplasty increases knee flexion angles and extensor moments in the gait of patients with patellar instability and to compare postoperative gait to a healthy control group.

METHODS

A bilateral dislocation group (6 patients) and a unilateral dislocation group (14 patients) were treated with bilateral and unilateral trochleoplasty, respectively. Kinematics and kinetics of the lower extremity were captured using 3D-gait analysis (VICON, 12 cameras, 200 Hz, plug-in-gait, two force plates). The mean of six trials was computed. The gait cycles were compared pre to postoperatively for each group. The gait of the two groups was compared to each other and the gait of a healthy population (54 knees).

RESULTS

After trochleoplasty, the knee flexion angles and knee extensor moments only increased in the bilateral dislocation group, whereas the gait pattern of the unilateral dislocation group remained unchanged. Compared to the healthy population, the postoperative gait pattern of the bilateral dislocation group did not differ. In contrast, knee flexion angles and extensor moments of the unilateral dislocation group were still lower.

CONCLUSION

In adolescents with bilateral recurrent patellar dislocations, trochleoplasty of both knees increases knee flexion angles and knee extensor moments comparable to normal gait. Unilateral symptomatic patients undergoing a unilateral trochleoplasty did not achieve normal walking. These findings point out that patellar instability should be considered as a bilateral problem, even in patients with unilateral dislocations.

LEVEL OF EVIDENCE

III.

Biomechanical effects of manipulating peak vertical ground reaction force throughout gait in individuals 6-12 months after anterior cruciate ligament reconstruction

BACKGROUND

We aimed to determine the effect of cueing an increase or decrease in the vertical ground reaction force impact peak (peak in the first 50% of stance) on vertical ground reaction force, knee flexion angle, internal knee extension moment, and internal knee abduction moment waveforms throughout stance in individuals 6-12 months after an anterior cruciate ligament reconstruction.

METHODS

Twelve individuals completed 3 conditions (High, Low, and Control) where High and Low Conditions cue a 5% body weight increase or decrease, respectively, in the vertical ground reaction force impact peak compared to usual walking. Biomechanics during High and Low Conditions were compared to the Control Condition throughout stance.

FINDINGS

The High Condition resulted in: (a) increased vertical ground reaction forces at each peak and decreased during mid-stance, (b) greater knee excursion (i.e., greater knee flexion angle in early stance and a more extended knee in late stance), (c) greater internal extension moment for the majority of stance, and (d) lesser second internal knee abduction moment peak. The Low Condition resulted in: (a) vertical ground reaction forces decreased during early stance and increased during mid-stance, (b) decreased knee excursion, (c) increased internal extension moment throughout stance, and (d) decreased internal knee abduction moment peaks.

INTERPRETATION

Cueing a 5% body weight increase in vertical ground reaction force impact peak resulted in a more dynamic vertical ground reaction force loading pattern, increased knee excursion, and a greater internal extension moment during stance which may be useful in restoring gait patterns following anterior cruciate ligament reconstruction.

Osteoarthritis year in review 2019: mechanics

Mechanics play a critical - but not sole - role in the pathogenesis of osteoarthritis, and recent research has highlighted how mechanical constructs are relevant at the cellular, joint, and whole-body level related to osteoarthritis outcomes. This review examined papers from April 2018 to April 2019 that reported on the role of mechanics in osteoarthritis etiology, with a particular emphasis on studies that focused on the interaction between movement and tissue biomechanics with other clinical outcomes relevant to the pathophysiology of osteoarthritis. Studies were grouped by themes that were particularly prevalent from the past year. Results of the search highlighted the large exposure of knee-related research relative to other body areas, as well as studies utilizing laboratory-based motion capture technology. New research from this past year highlighted the important role that rate of exerted loads and rate of muscle force development - rather than simply force capacity (strength) - have in OA etiology and treatment. Further, the role of muscle activation patterns in functional and structural aspects of joint health has received much interest, though findings remain equivocal. Finally, new research has identified potential mechanical outcome measures that may be related to osteoarthritis disease progression. Future research should continue to combine knowledge of mechanics with other relevant research techniques, and to identify mechanical markers of joint health and structural and functional disease progression that are needed to best inform disease prevention, monitoring, and treatment.

Foot and ankle compensation for anterior cruciate ligament deficiency during gait in children

BACKGROUND

Anterior cruciate ligament (ACL) injuries are common in adults and cause knee instability, pain, and an increased risk of osteoarthritis. Previous studies demonstrated changed gait patterns in adult patients with ACL deficiency. In paediatric patients, ACL injuries were once thought to be rare but are being increasingly diagnosed due to greater involvement of children in contact sports and to the introduction of more effective diagnostic tools such as magnetic resonance imaging (MRI). However, little is known about gait adaptation in children with ACL deficiency. The objective of this study was to look for compensatory foot and ankle behaviours during gait in paediatric patients with symptomatic ACL deficiency.

HYPOTHESIS

Compensation for ACL deficiency during gait occurs at the foot and ankle in children, because compensation at the hip and pelvis would require greater energy expenditure.

MATERIAL AND METHODS

We included 47 patients, 33 males and 14 females, ranging in age from 9 to 17 years (mean, 14.1 years). The patients had a history of unilateral ACL injury documented by MRI and initially treated by immobilisation and physical therapy. They were allowed to walk with full weight-bearing on the affected limb and were not taking medications at the time of the study. All patients had pain, knee instability, or functional limitation. The physical examination showed joint laxity indicating surgical ACL reconstruction. None had neurological conditions, congenital musculoskeletal abnormalities, or a history of knee surgery. Gait analysis (GA) was performed using a Vicon 460 system. Kinematic data for the ankle and foot were compared to those in a control group of 37 healthy children. Ankle angular positions were calculated for each group at the following stance time points: initial contact (0% of gait cycle [GC]), mid-stance (25% GC), terminal stance (60% GC), and swing (83% GC). Foot progression data were recorded at mid-stance (25% GC) and swing (70% GC). Student's t test was applied to compare the results to reference values obtained at our laboratory and to data from the control group.

RESULTS

Compared to the reference values, the ankle was in plantar flexion at initial contact in 41 patients, and ankle dorsiflexion during the stance phase was diminished in 39 patients. The external foot progression angle was increased in 23 patients during the stance phase and 38 patients during the swing phase. Compared to the control group (mean age, 9.1 years), the patients had plantar flexion of the ankle at initial contact (3.43°±3.5° vs. 0.74°±3.6°, p<0.05) and decreased dorsiflexion during the stance phase (3.43°±3.5° vs. 0.74°±3.6°, p<0.05). No significant differences were found for any of the other parameters.

DISCUSSION

Children with ACL deficiency developed compensatory foot and ankle behaviours during gait that improved knee stability. Understanding these compensations may guide treatment optimisation.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Anterior cruciate ligament deficiency combined with lateral and/or medial meniscal injury results in abnormal kinematics and kinetics during level walking

Anterior cruciate ligament injuries are commonly combined with meniscal tears. This study was performed to analyze the kinematics and kinetics of knees with anterior cruciate ligament deficiency with or without a combined medial or/and lateral meniscal injury during level walking. In all, 29 patients with unilateral anterior cruciate ligament deficiency and 15 healthy male volunteers were recruited. Among these patients, 12 had isolated unilateral anterior cruciate ligament injuries (ACLD group), 5 had combined anterior cruciate ligament and lateral meniscal injuries (ACLDL group), 5 had combined anterior cruciate ligament and medial meniscal injuries (ACLDM group), and 7 had combined anterior cruciate ligament and medial/lateral meniscal injuries (ACLDML group). A subject-specific musculoskeletal multibody dynamics model was utilized to estimate the tibiofemoral joint kinematic and kinetic behaviors based on the experimental data measured by using an optical tracking system. Regardless of the presence or absence of meniscal injury, the knees with anterior cruciate ligament deficiency exhibited significantly less extension than the control knees at the terminal stance (range of extension: ACLD, 4.84° ± 4.31°; ACLDL, 6.65° ± 5.73°; ACLDM, 5.21° ± 4.77°; ACLDML, 6.91° ± 4.30°; control, 12.35° ± 5.52°; P < 0.05). A lower extension moment and adduction moment in all anterior cruciate ligament deficiency affected knees were detected during the terminal stance when compared with control knees (P < 0.05). The ACLDML group showed significantly lower proximal-distal compressive forces and anterior-posterior shear forces (approximately 0.5-1.5 body weight; P < 0.05) compared to the other 4 groups, while the anterior-posterior and medial-lateral shear forces tended to increase in the ACLD, ACLDL, and ACLDM groups at the mid to terminal stance. Significant lower adduction-abduction and internal-external moment peaks were observed in ACLDML groups, but not in the ACLD, ACLDL and ACLDM groups. These results indicate that the combination of an anterior cruciate ligament injury and meniscal injury could alter the kinematics and kinetics of anterior cruciate ligament deficiency affected knees depending on the presence and type of the meniscal tear.

Knee joint biomechanics in transtibial amputees in gait, cycling, and elliptical training

Transtibial amputees may experience decreased quality of life due to increased risk of knee joint osteoarthritis (OA). No prior studies have compared knee joint biomechanics for the same group of transtibial amputees in gait, cycling, and elliptical training. Thus, the goal of this study was to identify preferred exercises for transtibial amputees in the context of reducing risk of knee OA. The hypotheses were: 1) knee biomechanics would differ due to participant status (amputee, control), exercise, and leg type (intact, residual) and 2) gait kinematic parameters would differ due to participant status and leg type. Ten unilateral transtibial amputee and ten control participants performed exercises while kinematic and kinetic data were collected. Two-factor repeated measures analysis of variance with post-hoc Tukey tests and non-parametric equivalents were performed to determine significance. Maximum knee compressive force, extension torque, and abduction torque were lowest in cycling and highest in gait regardless of participant type. Amputee maximum knee extension torque was higher in the intact vs. residual knee in gait. Amputee maximum knee flexion angle was higher in the residual vs. intact knee in gait and elliptical. Gait midstance knee flexion angle timing was asymmetrical for amputees and knee angle was lower in the amputee residual vs. control non-dominant knees. The results suggest that cycling, and likely other non-weight bearing exercises, may be preferred exercises for amputees due to significant reductions in biomechanical asymmetries and joint loads.

Relative Surface Velocity of the Tibiofemoral Joint and Its Relation to the Development of Osteoarthritis After Joint Injury

The relative velocity of the tibiofemoral surfaces during gait before and after partial-ACL and full MCL transection (p-ACL/MCL Tx) was examined in an ovine model (N = 5) and the relation between the variation in the relative sliding velocity component and gross morphological damage was investigated. We defined the in vivo kinematics of the tibiofemoral joints by using an instrumented spatial linkage and then determining the relative velocity components on the reconstructed femoral condyle surfaces. One major finding was that the magnitude of the relative velocity components was relatively high during the initial stance period of the gait and oscillated with a decaying envelope. Interestingly, for most subjects, the highest value of relative sliding velocity occurred during the stance phase, and not swing. The magnitude of the relative velocity components was increased in 3/5 subjects during stance after an injury. For the lateral compartment, there was a significant correlation (p value = 0.005) between the joint gross morphological damage and the increase in the maximum relative sliding velocity during stance. For the medial compartment, there was a trend (p value < 0.1) between the joint gross morphological score and the increase in the maximum relative sliding velocity during stance, 20 weeks after injury. In conclusion, a connection between an increase in the relative surface velocity and gross morphological damage might be due to an increase in the normal stress and the plowing friction between the surfaces.

Longitudinal Effects of Acute Anterior Cruciate Ligament Tears on Peri-Articular Bone in Human Knees Within the First Year of Injury

Anterior cruciate ligament (ACL) tears are common sports-related knee injuries that increase the risk of developing post-traumatic osteoarthritis. ACL tears are rarely an isolated injury but are often associated with traumatic bone marrow lesions (BMLs). While early loss of bone mass following the ACL injury has been previously described, to date, microarchitectural information has not been reported due to the limited resolution of clinical imaging systems. In this study, we provide the first evidence of detailed bone mass and microarchitectural changes in the first 10 months following an acute ACL tear, and localized to traumatic BMLs. Fifteen participants with an acute unilateral ACL tear were assessed at four-time points using dual-energy X-ray absorptiometry and high-resolution peripheral quantitative computed tomography, and traumatic BMLs were identified with magnetic resonance imaging. Loss of bone mass was localized to the injured knee (-4.6% to -15.8%, depending on bone and depth) and was accelerated immediately following the injury before suggesting a recovery phase. This loss of bone was accelerated even greater in traumatic BMLs (-18.2% to -20.6%, depending on bone). Bone loss was accompanied by microstructural degeneration of trabecular bone. For example, in the lateral femur of the injured knee, the subchondral bone plate decreased in thickness (-9.0%). This study confirmed loss of bone mass in the months following ACL tears and described the underlying bone microstructural changes. The presented bone changes were accelerated in regions of traumatic BMLs. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2325-2336, 2019.

The effects of intensive dietary weight loss and exercise on gait in overweight and obese adults with knee osteoarthritis. The Intensive Diet and Exercise for Arthritis (IDEA) trial

The Intensive Diet and Exercise for Arthritis (IDEA) trial was an 18-month randomized controlled trial that enrolled 454 overweight and obese older adults with symptomatic and radiographic knee osteoarthritis (OA). Participants were randomized to either exercise (E), intensive diet-induced weight loss (D), or intensive diet-induced weight loss plus exercise (D + E) interventions. We previously reported that the clinical benefits of D + E were significantly greater than with either intervention alone (e.g., greater pain reduction, and better function, mobility, and health-related quality of life). We now test the hypothesis that D + E has greater overall benefit on gait mechanics compared to either intervention alone. Knee joint loading was analyzed using inverse dynamics and musculoskeletal modeling. Analysis of covariance determined the interventions' effects on gait. The D + E group walked significantly faster at 18-month follow-up (1.35 m s^-1) than E (1.29 m s^-1, p = 0.0004) and D (1.31 m s^-1, p = 0.0007). Tibiofemoral compressive impulse was significantly lower (p = 0.0007) in D (1069 N s) and D + E (1054 N s) compared to E (1130 N s). D had significantly lower peak hip external rotation moment (p = 0.01), hip abduction moment (p = 0.0003), and peak hip power production (p = 0.016) compared with E. Peak ankle plantar flexion moment was significantly less (p < 0.0001) in the two diet groups compared with E. There also was a significant dose-response to weight loss; participants that lost >10% of baseline body weight had significantly (p = 0.0001) lower resultant knee forces and lower muscle (quadriceps, hamstring, and gastrocnemius) forces than participants that had less weight loss. Compared to E, D produces significant load reductions at the hip, knee, and ankle; combining D with E attenuates these reductions, but most remain significantly better than with E alone.

In vivo attachment site to attachment site length and strain of the ACL and its bundles during the full gait cycle measured by MRI and high-speed biplanar radiography

The purpose of this study was to measure in vivo attachment site to attachment site lengths and strains of the anterior cruciate ligament (ACL) and its bundles throughout a full cycle of treadmill gait. To obtain these measurements, models of the femur, tibia, and associated ACL attachment sites were created from magnetic resonance (MR) images in 10 healthy subjects. ACL attachment sites were subdivided into anteromedial (AM) and posterolateral (PL) bundles. High-speed biplanar radiographs were obtained as subjects ambulated at 1 m/s. The bone models were registered to the radiographs, thereby reproducing the in vivo positions of the bones and ACL attachment sites throughout gait. The lengths of the ACL and both bundles were estimated as straight line distances between attachment sites for each knee position. Increased attachment to attachment ACL length and strain were observed during midstance (length = 28.5 ± 2.6 mm, strain = 5 ± 4%, mean ± standard deviation), and heel strike (length = 30.5 ± 3.0 mm, strain = 12 ± 5%) when the knee was positioned at low flexion angles. Significant inverse correlations were observed between mean attachment to attachment ACL lengths and flexion (rho = -0.87, p < 0.001), as well as both bundle lengths and flexion (rho = -0.86, p < 0.001 and rho = -0.82, p < 0.001, respectively). AM and PL bundle attachment to attachment lengths were highly correlated throughout treadmill gait (rho = 0.90, p < 0.001). These data can provide valuable information to inform design criteria for ACL grafts used in reconstructive surgery, and may be useful in the design of rehabilitation and injury prevention protocols.

Mean Three-Year Survivorship of a New Bicruciate-Retaining Total Knee Arthroplasty: Are Revisions Still Higher Than Expected?

BACKGROUND

Given the need for continued post-market surveillance, especially on novel implants, the present study attempts to determine the 3-year survivorship and patient-reported outcomes of a contemporary bicruciate-retaining total knee arthroplasty design, and to determine if a learning curve existed which could explain previously reported revision rates.

METHODS

We performed a retrospective review on a consecutive series of 141 bicruciate-retaining total knee arthroplasties performed at our institution between May 2013 and October 2015. Thirty-four knees (19%) missing 2-year follow-up were excluded. Mean follow-up was 3 years (range 0.34-4.9). Patients who died (n = 5) or were revised prior to 2 years (n = 6) were included. A Kaplan-Meier analysis was used to evaluate revision-free survival.

RESULTS

Survivorship at 3 years was 88% (82%-93%). Revisions were for isolated tibial loosening (5/19), anterior cruciate ligament (ACL) impingement (3/19), pain (4/19), unknown reasons (3/19), femoral and tibial loosening (2/19), ACL deficiency (1/19), and arthrofibrosis (1/19). The mean physical function computerized adaptive test T-score was 45 units (range 23-63). The mean T-scores for Patient-Reported Outcomes Measurement Information System Global measures were 49 (range 27-68) for physical health, 50 (range 28-68) for mental health, and a median 3 (interquartile range 1-8) on the numeric pain scale.

CONCLUSION

Revision-free survival of 88% at 3 years was lower than existing traditional TKA designs. The primary failure mechanisms were tibial loosening, ACL impingement, and pain. In the setting of higher than anticipated revision rates, despite patient-reported outcomes that are not different than seen in the general population, it is possible that further refinement in implant design or surgical technique may be needed prior to widespread use of this, or similar implant designs.

Large Animal Models for Anterior Cruciate Ligament Research

Large animal (non-rodent mammal) models are commonly used in ACL research, but no species is currently considered the gold standard. Important considerations when selecting a large animal model include anatomical differences, the natural course of ACL pathology in that species, and biomechanical differences between humans and the chosen model. This article summarizes recent reports related to anatomy, pathology, and biomechanics of the ACL for large animal species (dog, goat, sheep, pig, and rabbit) commonly used in ACL research. Each species has unique features and benefits as well as potential drawbacks, which are highlighted in this review. This information may be useful in the selection process when designing future studies.

Longitudinal Changes in the Total Knee Joint Moment After Anterior Cruciate Ligament Reconstruction Correlate With Cartilage Thickness Changes

This study investigated associations between changes in the total joint moment (TJM) at the knee and changes in cartilage thickness after anterior cruciate ligament reconstruction (ACLR). Seventeen subjects (five males; age: 29.6 ± 7.3 years) with unilateral ACLR underwent gait analysis and magnetic resonance imaging at baseline (2.2 ± 0.3 years post-ACLR) and at long-term follow-up (7.7 ± 0.7 years post-ACLR). Knee loading was assessed using the TJM, and differences in loading were analyzed using repeated measures analysis of variance. Pearson correlation coefficients assessed associations between changes in TJM and changes in (medial-to-lateral) M/L femoral cartilage thickness ratios in the ACLR limb. Bilaterally, there was no significant change in the magnitude of the TJM first peak (TJM1), however, there was a significant increase in the percent contribution of the knee flexion moment (KFM) (p < 0.001) and decrease in the percent contribution of the knee adduction moment (KAM) to TJM1 (p < 0.001). The change in the percent contributions of KFM and KAM to TJM1 were associated with changes in M/L femoral cartilage thickness in the ACLR limb. Specifically, subjects with smaller increases in KFM contribution (R = 0.521, p = 0.032) and smaller decreases in KAM contribution (R = -0.521, p = 0.032) had a reduction in the M/L ratio in the central femoral subregion over the follow-up period, with similar trends in the external femoral subregion. The study results provide new insight into changes in the loading environment at the knee joint prospectively following ACL reconstruction and give evidence that there are modifiable gait metrics that are associated with cartilage changes after ACLR. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1546-1554, 2019.

Classification of gait muscle activation patterns according to knee injury history using a support vector machine approach

Abnormal muscle activation patterns during gait following knee injury that persist past the acute injury and rehabilitation phase (>three years) are not well characterized but may be related to post-traumatic knee osteoarthritis. The aim was to characterize the abnormal muscle activity from electromyograms of five leg muscles that were recorded during treadmill walking for young adults with and without a previous knee injury 3-12 years prior. The wavelet transformed and amplitude normalized electromyograms yielded intensity patterns that reflect the muscle activity of these muscles resolved in time and frequency. Patterns belonging to the affected or unaffected leg in previously injured participants and patterns belonging to a previously injured vs. uninjured participant were grouped and then classified using a principal component analysis followed by a support vector machine. A leave-one-out cross-validation was used to test the model significance and generalization. The results showed that trained classifiers could successfully recognize whether muscle activation patterns belonged to the affected or unaffected leg of previously injured individuals. Classification rates of 83% were obtained for all subjects, 100% for females only, indicating sex-specific knee injury effects. In contrast, it was not possible to discriminate between patterns belonging to the previously injured legs or dominant legs of control subjects. For females, the injured leg showed a stronger muscle activity for hamstring muscles and a lower activity for the vastus lateralis. In conclusion, systematic knee injury effects on the neuromuscular control of the knee during gait were present 3-12 years later.

Muscular Force Patterns during Level Walking in ACL-Deficient Patients with a Concomitant Medial Meniscus Tear

Background

The abnormal knee joint motion patterns caused by anterior cruciate ligament (ACL) deficiency are thought to be associated with articular cartilage degeneration. High rates of meniscus tear combined with ACL rupture are observed, and these knees suffer a higher risk of early cartilage degeneration.

Research Question

This study investigated lower limb muscular force patterns of ACL-deficient knees with a concomitant medial meniscus tear.

Methods

12 volunteers and 22 patients were recruited, including 12 patients with isolated ACL deficiency (ACLD) and 10 ACL-deficient patients with a concomitant medial meniscus tear (ACLDM). Level walking data at a self-selected speed were collected before surgery. Then, a musculoskeletal dynamic analysis system, AnyBody, was applied to simulate tibiofemoral flexion moments and muscle forces.

Results

Our results indicate that the tibiofemoral peak flexion and extension moments in ACLDM patients are significantly lower than in controls. The rectus femoris force in ACLDM patients was significantly lower than in isolated ACL-deficient patients and the controls during mid and terminal stance phase, while no significant difference was found in hamstring and vastus force. Additionally, the gastrocnemius force in ACL-deficient patients both with and without a medial meniscus tear was lower than in controls during mid-stance phase.

Significance

The ACLDM patients had lower peak tibiofemoral flexion moment, lower gastrocnemius force in mid-stance phase, and lower rectus femoris force during the mid and terminal stance phase. These results may help clinicians to better understand the muscle function and gait pattern in ACL-deficient patients with a concomitant medial meniscus tear.