Principal component analysis of knee kinematics and kinetics after anterior cruciate ligament reconstruction

Comparative Study of Graft Healing in 2 Years after “Tension Suspension” Remnant-Preserving and Non-Remnant-Preserving Anatomical Reconstruction for Sherman Type II Anterior Cruciate Ligament Injury

Purpose: To evaluate the degree of graft healing after “tension suspension” reconstruction of “Sherman II” anterior cruciate ligament injuries versus non-remnant preserving anatomical reconstruction and to compare the clinical outcomes of the two procedures. Method: The clinical data of 64 patients were retrospectively included. There were 31 cases in the “tension suspension” remnant-preserving reconstruction group and 33 cases in the non-remnant-preserving anatomical reconstruction group. The International Knee Documentation Committee (IKDC) score, the Tegner score, and the Lysholm activity score were assessed preoperatively and at 6 months, 1 year, and 2 years postoperatively, respectively. The signal/noise quotient (SNQ) of the grafts was measured at 6 months, 1 year, and 2 years after surgery to quantitatively evaluate the maturity of the grafts after ACL reconstruction; the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the reconstructed ACL region of interest (ROI) were measured using DTI. Result: A total of 64 patients were included in the study. The mean SNQ values of the grafts in the 6 months, 1 year, and 2 years postoperative remnant-preserving reconstruction (RP) groups were lower than those in the non-remnant-preserving (NRP) reconstruction group, with a statistically significant difference (p < 0.05). At each postoperative follow-up, the SNQ values of the tibial and femoral sides of the RP group were lower than those of the NRP group; the SNQ values of the femoral side of the grafts in both groups were higher than those of the tibial side, and the differences were statistically significant (p < 0.05). At 6 months, 1 year, and 2 years postoperatively, the FA and ADC values of the grafts were lower in the RP group than in the NRP group, and the differences were statistically significant (p < 0.05); the IKDC score and Lysholm score of the RP group were higher than the NRP group, which was statistically significant (p < 0.05). Conclusion: For Sherman II ACL injury, the graft healing including ligamentization and revascularization at 2 years after the “tension suspension” remnant-preserving reconstruction was better than that of non-remnant-preserving anatomic reconstruction.

A Systematic Method for Outlier Detection in Human Gait Data

When it comes to observing and measuring human gait data for further analysis, determining whether the observed behavior is within the normal range of variability, or should be considered abnormal, is very challenging. Moreover, usually gait data are multivariate including motion capture, electromyography, force measurements, etc., each source having its own unique causes of irregularities and anomalies. This paper introduces a unique algorithm for outlier detection in periodic gait data using multiple sources and multiple procedures to improve the overall accuracy. The proposed algorithm's performance is evaluated using realistic synthetic gait data to gauge its accuracy to a truly objective known solution. It is shown that the proposed method is able to detect 91.2% of the true outliers in an extensive synthetic dataset, while only producing false positives at a rate of 0.1%, outperforming other procedures usually utilized in gait data outlier detection. The proposed method is a systematic way of removing outliers from gait data, with direct applications to human biomechanics, rehabilitation and robotics, and can be applied to other scientific fields dealing with periodic data.

Biomechanical Markers of Forward Hop-Landing After ACL-Reconstruction: A Pattern Recognition Approach

Biomechanical changes after anterior cruciate ligament reconstruction (ACLR) may be detrimental to long-term knee-joint health. We used pattern recognition to characterise biomechanical differences during the landing phase of a single-leg forward hop after ACLR. Experimental data from 66 individuals 12-24 months post-ACLR (28.2 ± 6.3 years) and 32 controls (25.2 ± 4.8 years old) were input into a musculoskeletal modelling pipeline to calculate joint angles, joint moments and muscle forces. These waveforms were transformed into principal components (features), and input into a pattern recognition pipeline, which found 10 main distinguishing features (and 8 associated features) between ACLR and control landing biomechanics at significance \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\alpha =0.05$$\end{document}α=0.05. Our process identified known biomechanical characteristics post-ACLR: smaller knee flexion angle; less knee extensor moment; lower vasti, rectus femoris and hamstrings forces. Importantly, we found more novel and less well-understood adaptations: smaller ankle plantar flexor moment; lower soleus forces; and altered patterns of knee rotation angle, hip rotator moment and knee abduction moment. Crucially, we identified, with high certainty, subtle aberrations indicating landing instability in the ACLR group for: knee flexion and internal rotation angles and moments; hip rotation angles and moments; and lumbar rotator and bending moments. Our findings may benefit rehabilitation and assessment for return-to-sport 12–24 months post-ACLR.

Effects of Postoperative Rehabilitation on Gait Parameters and Electromyography Variables in Acute and Chronic Anterior Cruciate Ligament Reconstruction Surgery in Football Players

Results

The results of the a-ACLR, c-ACLR, and control groups were compared. At 8 weeks following postoperative rehabilitation, the a-ACLR group shows more significant changes than the c-ACLR group (p < 0.001). At 6 and 12 months, there are normal values of kinematic and kinetic values in a-ACLR compared with the results of the control group (p < 0.001).

Conclusion

The study showed that postoperative rehabilitation provides significant effects in the kinematic, kinetic, and EMG gait parameters in acute ACLR than chronic ACLR subjects. Early surgical intervention and postrehabilitation are mandatory to get the significant effects in the clinical parameters in acute and chronic ACL injury.

Association between Kinesiophobia and Gait Asymmetry after ACL Reconstruction: Implications for Prevention of Reinjury

Gait asymmetries have been documented in individuals after anterior cruciate ligament (ACL) reconstruction (ACLR). The relationship between gait asymmetry and associated psychological factors, however, is not yet known. This study aimed to examine the relationship between kinesiophobia (fear of reinjury) and asymmetry of vertical ground reaction force (vGRF) and lower-extremity muscular activity in individuals after ACLR during gait. Twenty-eight males with a history of ACLR participated in the study. Force plate and surface electromyography was used to record peak vGRF and muscular activity. The Tampa Scale of Kinesiophobia (TSK-11) was used to measure kinesiophobia. Spearman’s rank correlations analysis was used to examine the relationship between TSK-11 scores and both gait asymmetry variables. There was a significant positive relationship between TSK-11 and asymmetry of the second peak of vGRF (r_s = 0.531, p = 0.002). In addition, there was a significant positive association between asymmetry of rectus femoris activity (r_s = 0.460, p = 0.007) and biceps femoris activity (r_s = 0.429, p = 0.011) in the contact phase. Results revealed a significant relationship between kinesiophobia and asymmetry in muscle activity and vGRF in different phases of the gait cycle. Interventions addressing kinesiophobia early in the rehabilitation after ACLR may support the restoration of gait symmetry, facilitate a more rapid return to sport, and reduce the risk of ACL reinjury.

Altered kinematics after anterior cruciate ligament reconstruction, and their role in the prevention of osteoarthritis

Background/Aims:

Anterior cruciate ligament injury is common, and anterior cruciate ligament reconstruction has become the standard of care that aims to restore knee stability, return to activity, and prevent secondary injury.

Methods:

A literature review was carried out using PubMed and Science Direct databases from 1998 through 2017. Search terms included: anterior cruciate ligament reconstruction and knee osteoarthritis; kinematics after anterior cruciate ligament reconstruction; and prevention of knee osteoarthritis. A total of 356 studies matched the search terms. After removing duplicates and any studies that were not relevant, 73 studies remained.

Findings:

Individuals usually have impaired neuromuscular control after reconstruction, and abnormal biomechanical patterns may lead to loading of cartilage areas that are not commonly loaded and that, longitudinally, can lead to osteoarthritis. The knee adduction moment indicates loading of the knee joint and has been associated with the development of osteoarthritis and altered gait mechanics have also been implicated in the increased rate of osteoarthritis after anterior cruciate ligament reconstruction, including differences in tibial rotation during walking. Furthermore, altered ankle joint mechanics may be the result of deviations in ankle joint alignment secondary to the structural changes at the knee. It is clear that abnormal mechanical stimulation may cause dysfunction of articular chondrocytes and breakdown of cartilage extracellular matrix, leading to articular cartilage degradation and chondrocyte death. The affected joint will progress to post-traumatic osteoarthritis.

Conclusions:

The restoration of normal knee anatomy and mechanics, such as returning the joint to normal function, improving muscle strength, functional movement prevention programmes, restoring gait symmetry and weight management are recommended.

Frontal Plane Knee Mechanics and Early Cartilage Degeneration in People With Anterior Cruciate Ligament Reconstruction: A Longitudinal Study

BACKGROUND

Abnormal frontal plane gait mechanics are known risk factors for knee osteoarthritis, but their role in early cartilage degeneration after anterior cruciate ligament reconstruction (ACLR) is not well understood. Hypothesis/Purpose: The objective was to evaluate the association of frontal plane gait mechanics with medial knee cartilage magnetic resonance (MR) relaxation times over 1 year in patients with ACLR and controls. It was hypothesized that (1) there will be an increase in frontal plane medial knee loading and medial knee MR relaxation times over time in the patients with ACLR, and (2) increases in frontal plane medial knee loading will be associated with an increase in medial knee MR relaxation times.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Patients with ACLR (n = 37) underwent walking gait analyses and bilateral quantitative MR imaging (MRI) before surgery and at 6 and 12 months after ACLR. Healthy control participants (n = 13) were evaluated at baseline and 12 months. Gait variables included peak knee adduction moment (KAM), KAM impulse, and peak knee adduction angle. MRI variables included medial femur and medial tibia whole compartment and subregional T_1ρ and T₂ relaxation times. Statistical analyses included a comparison of changes over time for gait and MRI variables, correlations between changes in gait and MRI variables over time, and differences in change in MRI variables in patients who showed an increase versus decrease in KAM impulse.

RESULTS

There were significant increases in medial T_1ρ (Δ 4%-11%) and T₂ (Δ 2%-10%) relaxation times from baseline to 6 months for both knees in the ACLR group and in KAM (Δ 13%) for the injured knee. From baseline to 6 months, patients who had an increase in KAM impulse in the injured knee had a greater increase in medial T_1ρ and T₂ relaxation times as compared with those who did not have an increase in KAM impulse. Longitudinal changes for the control group were not significant.

CONCLUSION

There is an increase in medial knee relaxation times over the first 6 months after ACLR. People with an increase in medial knee loading show an increase in medial knee relaxation times when compared with those who do not have an increase in medial knee loading over the first 6 months.

Gait analysis of young male patients diagnosed with primary bladder neck obstruction

Primary bladder neck obstruction (PBNO) represents an inappropriate or inadequate relaxation of the bladder neck during micturition. Based on the observation of an increased rate of postural imbalances in male patients with PBNO, we hypothesized a possible role of an unbalanced biomechanics of the pelvis on urethral sphincters activity. Our aim was to identify kinematic imbalances, usually disregarded in PBNO patients, and which could eventually be involved in the etiopathogenesis of the disease. Seven male adult patients (39.6±7.1years) were recruited; in all patients, PBNO was suspected at bladder diary and uroflowmetry, and was endoscopically confirmed with urethroscopy. Participants gait was recorded with a motion capture system (BTS Spa, Italy) to obtain three-dimensional joint angles and gait parameters. Multivariate statistics based on a Principal Component model allowed to assess the similarity of patients' gait patterns with respect to control subjects. The main finding is that patients with PBNO showed significant discordance in the observations at the ankle and pelvis level. Additionally, 6/7 patients demonstrated altered trunk positions compared to normal curves. We suggest that the identified postural imbalances could represent the cause for an anomalous activation of pelvic floor muscles (hypertonia). The consequent urinary sphincters hypercontraction may be responsible for the development of voiding dysfunction in male patients with no significant morphological alterations. Results reinforced the hypothesis of an etiopathogenetic role of postural imbalances on primary bladder neck obstruction in male patients.

Combined gait asymmetry metric

People with physical impairments often have asymmetric gait. To evaluate if their overall symmetry is improving during intervention, there needs to be a simple metric that can help classify gait patterns that includes multiple measures of gait asymmetry. The Combined Gait Asymmetry Metric presented here is based on the Mahalanobis distance of multiple step parameters. We tested able-bodied subjects with perturbations that involve a change in leg length, the addition of ankle weights, and a combination of both perturbations. The Mahalanobis distances are calculated from perfect symmetry to all points in the data to analyze the effects of the different perturbations. The metric demonstrates how an overall view of symmetry can give a better perspective of asymmetry than only looking at a few individual parameters. This metric is straightforward and can be extended to include large numbers of spatiotemporal, kinematic, and kinetic parameters that more completely evaluate a change in gait symmetry.

Three-dimensional kinematic analysis of ankle, knee, hip, and pelvic rotation during gait in patients after anterior cruciate ligament reconstruction - early results

Background

The goal of this study was to biomechanically assess tibial rotation in the knee joint simultaneous changes in rotation of large joints of the lower limbs and pelvis during gait in patients during early postoperative stages following anterior cruciate ligament (ACLR) reconstruction.

We hypothesized that tibial rotation is associated with changes in rotation of the large joints of the lower limbs and the pelvis during gait in patients after ACLR reconstruction.

Methods

The patients were divided into two groups. The ACLR group (n = 32 males) underwent primary ACLR in one leg and postoperative physiotherapy. The control group (n = 30 males) had no knee injuries. After clinical assessment in both groups, the values of kinematic parameters of foot, tibial, femoral, and pelvic rotation were measured during gait on a flat surface using the three-dimensional BTS Smart System. In the ACLR group, measurements were taken during the 4th, 9th, and 14th weeks of postoperative physiotherapy. The results of the ACLR group were compared with those of the control group.

Results

During gait, between the 9th and 14th weeks following ACLR, there are normal values of foot, tibia, and pelvic rotation in the operated legs compared with results obtained from un-operated legs and the control group.

Discussion

Analysis of rotations occurring only in knee joints does not reflect all of the multiarticular disorders of gait kinematics. The study also suggests that analyzing tibial rotation in the knee joint with simultaneous changes in rotation in large joints of the lower limbs provides better opportunities than singular analysis of rotation in the knee joint for the assessment of disorders in gait kinematics.

Conclusions

In gait, at the maximal extension of the knee during preparation for the stance phase, external hip rotation patterns have not been fully restored 14 weeks after ACLR.

Contralateral limb deficit seven months after ACL-reconstruction: an analysis of single-leg hop tests

BACKGROUND

Following ACL-reconstruction, the non-injured leg (NIL) is used as a reference to assess injured leg (IL) recovery. However, deficits have been reported in the NIL questioning its use as a reference. The aim of this study is to assess whether NIL deficits are present while jumping after ACL-reconstruction.

METHODS

Thirteen males who had undergone ACL-reconstruction and 16 healthy subjects took part in the experiment. Jumping performance was assessed during a single and a triple hop for distance. Jumping performance, kinematic and kinetic data were recorded during single leg squat jumps. Values for both the NIL and the IL were compared to those of a control group (CG).

RESULTS

Jumping performance for single and triple hop for distance and single leg squat jump was lower in the NIL than in the CG (p=0.004, p=0.002, and p=0.016, respectively). During the squat jump, the knee joint was more extended and the ankle plantar-flexion was greater at take-off while the peak total moment was 15% lower in the NIL than in the CG (p=0.002, p=0.002, and p=0.009, respectively). We found consistent evolutions in the NIL and the IL compared to the CG for jumping performance, initial joint angles, and peak total moment during the squat jump, but the opposite was found for the ankle and knee joint angles at squat jump take-off.

CONCLUSIONS

Jumping strategies are impaired in the NIL after ACL-R during jump tasks with some deficits matching those observed in the IL and some specific to the NIL.

LEVEL OF EVIDENCE

III, Case control study.

Infrared assessment of knee instability in ACL deficient patients

PURPOSE

Previous clinical studies have shown that anterior cruciate ligament (ACL) ruptures require reconstructive surgery. The main goal of this study is an objective test definition for unstable knee diagnosis based on real measurements by using infrared cameras and adequate software.

METHODS

In the study of gait analysis 35 males with deficient ACL's participated. Pathological parameters for anterior posterior translation (APT) and internal external rotation (IER) and their values of kinematic data were obtained from a gait analysis 3D system. Movement curves were obtained by recording the position of fluorescent markers over time. A machine learning algorithm was developed in order to support decisions on the severity of the ACL injury and its corresponding deficiency. The algorithm was based on logistic regression.

RESULTS

The value of APT, designated as exponentiation of the Ө coefficient (Exp (Ө)) of APT, showed that the likelihood of ACL-deficient knee occurrence due to higher values of APT is 1.1758 (95 % CI) times more frequent than that of the patients with lower values of APT. The value of IER, designated as Exp (Ө) of IER, showed that the patients with higher values of IER present 2.2516 (95 % CI) times higher values of ACL-deficient knee frequency than those with lower values.

CONCLUSION

This study showed that the creation of ordered pairs of pathological parameters gives a wider picture of ACL deficiency and that such an algorithm may improve both examination and treatment of patients.

Effects of isokinetic eccentric training on knee extensor and flexor torque and on gait of individuals with long term ACL reconstruction: A controlled clinical trial

This study investigated the effects of the isokinetic eccentric training (IET) on the knee extensor and flexor torque and kinematic gait parameters in individuals with ACL reconstruction. Sixteen men with ACL reconstructed (ACLr) whose torque and the gait were evaluated, before and after 12 weeks of IET, was compared to a control group (14 individuals). Student t, MANOVA and ANOVA tests were performed with 5% of significance. The training increased the isometric, concentric at 30 and 120º/s (p < .05) and eccentric at 30º/s (p < .01) extensor torque on the affected limb (AL), and eccentric at 30 and 120º/s (p < .01), on the non-affected limb (NAL). In the flexors, there was an increase on the torque: isometric, concentric at 30º/s and eccentric at 30 and 120º/s (p < .01) in AL and in eccentric at 30 (p < .05) and 120º/s (p< .01) in NAL. With respect to the angular and spatio-temporal variables gait, there was no difference between pre-and post-training in LCAr group. Compared to control group, the cycle time, in two members, was lower in LCAr group, and stride length and cadence were higher in the AL of the LCAr (p < .05). Moreover, the knee flexion-extension angles (minimum and maximum) remained lower in LCAr, pre- and post-training (p < .01). The torque gain associated with eccentric isokinetic training did not affect the kinematic parameters of gait in patients undergoing ACL reconstruction.

Frontal plane knee mechanics and medial cartilage MR relaxation times in individuals with ACL reconstruction: A pilot study

BACKGROUND

The objective of this pilot study was to evaluate cartilage T1ρ and T2 relaxation times and knee mechanics during walking and drop-landing for individuals with anterior cruciate ligament reconstruction (ACL-R).

METHODS

Nine patients (6 men and 3 women, age 35.8 ± 5.4 years, BMI 23.5 ± 2.5 kg/m(2)) participated 1.5 ± 0.8 years after single-bundle two-tunnel ACL reconstruction. Peak knee adduction moment (KAM), flexion moment (KFM), extension moment (KEM), and peak varus were calculated from kinematic and kinetic data obtained during walking and drop-landing tasks. T1ρ and T2 times were calculated for medial femur (MF), and medial tibia (MT) cartilage and compared between subjects with low KAM and high KAM. Biomechanical variables were compared between limbs.

RESULTS

The high KAM group had higher T1ρ for MT (p=0.01), central MT (p=0.05), posterior MF (p=0.04), posterior MT (p=0.01); and higher T2 for MT (p=0.02), MF (p=0.05), posterior MF (p=0.002) and posterior MT (p=0.01). During walking, ACL-R knees had greater flexion at initial contact (p=0.04), and lower KEM (p=0.02). During drop-landing, the ACL-R knees had lower KAM (p=0.03) and KFM (p=0.002).

CONCLUSION

Patients with ACL-R who have higher KAM during walking had elevated MR relaxation times in the medial knee compartments. These data suggest that those individuals who have undergone ACL-R and have higher frontal plane loading, may be at a greater risk of knee osteoarthritis.