Knee Joint Motion Research Articles

Bioreactor mimicking knee-joint movement for the regeneration of tissue-engineered cartilage

Efforts to minimize the sacrifice of laboratory animals have become a recent worldwide trend. This trend has triggered a number of studies toward developing effective methods to replace the animal experiments. In this study, we developed a biomimetic bioreactor system that simulates the movements of the human knee joint. The system consists of a knee-joint drive and a unit capable of culturing cells at the joint surface. The knee-joint drive is designed to apply dynamic stimulation similar to the real bending motion of the knee joint. We employed a commercial incubator for comparative evaluation and validation of our laboratory-made cell-culture unit mounted in a bioreactor. The results revealed that the ability of the proposed system in culturing cells was similar to that of the commercial incubator. The cell culture was evaluated by dividing the knee joint into zones according to the size of the stimulus. The results confirmed that the cell assessment stimulated by the knee-joint movement was two times higher than that having no stimulation. Overall, the study helped establish that the cell characteristics is more effective when an appropriate external stimulus is applied according to the target tissue. The study is also expected to form the basis for implementing an ex-vivo environment that can potentially replace animal and cadaver experiments in the future. In the future, follow-up studies will be conducted on the in-vivo environment and the characteristics of each organ and tissue for effective tissue regeneration.

Clinical observation of C3-type patellar fractures treated by operation methods with or without a turned-over patella

ObjectiveTo evaluate the clinical efficacy of operation methods with or without a turned-over patella for treatment of C3-type patellar fractures. MethodsA total of 68 patients with C3-type patellar fractures undergoing open reduction and internal fixation were retrospectively selected and treated with a turned-over patella surgery (turned-over patella group, n = 30) or conventional therapy without turning over the patella (conventional group, n = 38). The intraoperative and postoperative indicators of the two groups were assessed and comparatively analyzed. ResultsThe bedridden time was significantly shorter in the turned-over patella group than in the conventional group (P = 0.002), while the range of motion (ROM) of knee joint was significantly higher in the turned-over patella group (P = 0.044). The Lysholm score was slightly higher in the turned-over patella group than in the conventional group, but the difference was not statistically significant (P = 0.055). No significant difference was observed between the two groups in terms of the operation time (P = 0.096), intraoperative blood loss (P = 0.543), time of weight bearing (P = 0.312), fracture healing time (P = 0.272), or complications (P = 1). ConclusionThe turned-over patella operation method exhibited some superiority to conventional reduction-fixation approach for treatment of C3-type patellar fractures in terms of efficacy and safety by enlarging the ROM of the knee joint and promoting functional recovery.

Hybrid impedance control of a knee joint orthosis

Purpose This paper aims to deal with the design of new hybrid approach for the assistance of the flexion extension movement of the knee joint. Design/methodology/approach The control approach combines the use of a knee joint orthosis along with functional electrical stimulation (FES) within an assist-as-needed paradigm. An active impedance controller is used to assist the generation of muscular stimulation patterns during the extension sub-phase of the knee joint movement. The generated FES patterns are appropriately tailored to achieve flexion/extension movement of the knee joint, which allows providing the required assistance by the subject through muscular stimulation. The generated torque through stimulation is tracked by a non-linear disturbance observer and fed to the impedance controller to generate the desired trajectory that will be tracked using a standard proportional derivative controller. Findings The approach was tested in experiments with two healthy subjects. Results show satisfactory performances in terms of estimating the knee joint torque, as well as in terms of cooperation between the FES and the orthosis actuator during the execution of the knee joint flexion/extension movements. Originality/value The authors designed a new hybrid approach for the assistance of the flexion extension movement of the knee joint, which has not been studied yet. The control approach combines the use of a knee joint orthosis along with FES within an assist-as-needed paradigm.

A preclinical method for evaluating the kinematics of knee prostheses

The primary intent of anatomical knee implants is to replicate the motions of a normal knee joint. In developing such designs, a preclinical evaluation of kinematic behavior is needed. This study introduces an in vitro testing method for recording movements of the knee joint. A novel testing jig was developed and incorporated into a knee simulator setup alongside a motion capture system to directly track the medial and lateral movements of a knee prosthesis. The test system developed in this study required a number of factors to be validated; (i) gait inputs to the knee simulator (result: 0.37–1.575% error), (ii) validity of global coordinate system in the motion capture system, (iii) the position of flexion facet centers (FFCs) detected by the motion capture system (result: a maximum error of 0.08 mm in AP direction and 0.3 mm in SI direction), (iv) local coordinate system in the motion capture system (result: 1.09% error for the measurement of flexion angle), (v) that FFC results were in good agreement with inputs. In conclusion, the system developed in this study for recording FFC is a direct and reliable in vitro test method for analyzing the kinematics of a knee prosthesis.

Design of wireless device to measure plantar pressure and gait analysis

Foot plantar pressure is the pressure field that acts between the plantar region of the foot and supporting ground. The pressure exerted on the variable region of the foot can be determined using discrete pressure sensors. Information obtained from these sensors is useful in the measurement of gait and posture for diagnosing various problems associated with a lower limb, footwear design, and sports biomechanics. This project is aimed to design a portable in-shoe plantar pressure and gyroscope-based gait angle measurement system. Six Force Sensitive Resistor (FSR) placed in the sole (hallux, 1st, 5th metatarsal, midfoot lateral, midfoot medial and heel respectively) detects the plantar pressure and gyroscope placed at the ankle, knee and hip help measure the orientation and angle of joint movement during various phases of gait. The study among 16 male and 16 female subjects illustrated the significant pressure variation (p<0.0001, t=5.17 with α=95%). Similarly, there was a significant difference in pressure between normal and fast walking speed (p<0.0001, t=5.88) with mean values of 353Kpa and 426Kpa respectively. The mean pressure value for slow walking speed was 423Kpa while there was no significant variation between slow and normal walking speeds (p=0.62, t=1.98). Plantar pressure increased linearly with an increase in the body weight of a person as well. The mean pressure for the 45-50 age group was 313.25Kpa and that for 70-75 was 449Kpa. The study among 10 diabetics and 10 non-diabetic subjects illustrated significantly higher pressure on 1st and 5th metatarsal on diabetic subjects (p=0.0207 and t=2.536). The movement of ankle, knee and hip joint is visualized using the 3D model of a lower limb through processing software. The study illustrated the range of ankle joint movement between -60(dorsiflexion) to 200(plantarflexion), for knee joint was 00 to 300 (flexion) and that for hip joint was -50(extension) to 400(flexion). There was a significant difference in angular values for all three joints while climbing up and down the staircase as compared to walk in a level surface.

Comparisons of Accuracy of Knee Joint Motion During Closed verse Open Kinetic Chain Tasks in Subjects with Flexible Flatfeet

Purpose: This study examined the effects of flexible flatfeet on the accuracy of knee joint motions in closed and open kinetic chain tasks. Methods: Twenty-four healthy participants were recruited for this study. The subjects were divided into two groups using a navicular drop (ND) test: flexible flatfoot group (n=12, male: 6, aged 22.00±2.22 years) and age-matched control group (n=12, males: 6, aged 22.17±1.53 years). The accuracy of knee motion was measured quantitatively by tracing through the flexion and extension motion of the knee joints in the closed kinetic chain and the open kinetic chain. Results: There was a significant difference in the accuracy index between the groups in closed kinetic chain task, but there was no significant difference in the open kinetic chain task. In addition, there was a significant difference in the accuracy index between the closed kinetic chain and the open kinetic chain task in the flexible flatfoot group. In addition, a significant negative correlation was observed between the ND and accuracy index in the closed kinematic chain task, but there was no significant relationship between the ND and accuracy index in the open kinematic chain task. Conclusion: Flexible flatfeet can affect the accuracy of the adjacent joints, such as the knee joint in the closed kinematic chain.

Assessing Foot Loads in Continuous Passive Motion (CPM) and Active Knee Joint Motion Devices.

Continuous passive motion (CPM) and active knee joint motion devices are commonly applied after various surgical procedures. Despite the growing use of active motion devices, there is a paucity of data comparing plantar loads between the different mobilization techniques. The aim of this study was to investigate foot loads during knee joint mobilization in continuous passive and active knee joint motion devices and to compare this data to the physiological load of full weight-bearing. Fifteen healthy participants (7 women and 8 men, 25 ± 3 years, 66 ± 6 kg, 175 ± 10 cm, BMI 21.9 ± 2) were recruited. Plantar loads were measured via dynamic pedobarography using a continuous passive motion device (ARTROMOT-K1, ORMED GmbH, Freiburg, Germany) and an active motion device (CAMOped, OPED AG, Cham, Switzerland), each with a restricted range of motion of 0-0-90° (ex/flex) and free ROM for the knee joint. For the active motion device, cycles were performed at four different resistance levels (0-III). Data were assessed using the pedar® X system (Novel Inc., Munich, Germany), which monitors loads from the foot-sole interface. Force values were compared between motion devices and normal gait, which served as the reference for conditions of full weight-bearing. P-values of < 0.05 were considered statistically significant. Normal gait revealed peak forces of 694 ± 96 N, defined as 100 %. The CPM device produced plantar forces of less than 1.5 N. Using the active motion device in the setting of 0-0-90° produced foot loads of < 1.5 N (resistance 0-II) and 3.4 ± 9.3 N with a resistance of III (p < 0.001). Conditions of free ROM resulted in foot loads of 4.5 ± 4.5 N (resistance 0), 7.7 ± 10.7 N (resistance I), 6.7 ± 10.4 (resistance II) and 6.7 ± 6.9 N with a resistance of III (p < 0.001), corresponding to 0.6 %, 1.1 %, 1.0 % and 1.0 % of full weight-bearing, respectively. Motion exercises of the knee joint can be performed both with passive and active devices in accordance with strict weight-bearing restrictions, which are often recommended by surgeons. Also, active motion devices can be used when the ankle joint or foot have to be offloaded. Further studies assessing intraarticular joint load conditions have to be performed to confirm the findings obtained in this study.

Knee implant kinematics are task-dependent.

Although total knee arthroplasty (TKA) has become a standard surgical procedure for relieving pain, knowledge of the in vivo knee joint kinematics throughout common functional activities of daily living is still missing. The goal of this study was to analyse knee joint motion throughout complete cycles of daily activities in TKA subjects to establish whether a significant difference in joint kinematics occurs between different activities. Using dynamic videofluoroscopy, we assessed tibio-femoral kinematics in six subjects throughout complete cycles of walking, stair descent, sit-to-stand and stand-to-sit. The mean range of condylar anterior–posterior translation exhibited clear task dependency across all subjects. A significantly larger anterior–posterior translation was observed during stair descent compared to level walking and stand-to-sit. Local minima were observed at approximately 30° flexion for different tasks, which were more prominent during loaded task phases. This characteristic is likely to correspond to the specific design of the implant. From the data presented in this study, it is clear that the flexion angle alone cannot fully explain tibio-femoral implant kinematics. As a result, it seems that the assessment of complete cycles of the most frequent functional activities is imperative when evaluating the behaviour of a TKA design in vivo.

A Charge-Depletion Study of an Electrostatic Generator With Adjustable Output Voltage

Micro-scale generators are becoming more popular for harvesting energy to power bio-implantable devices and sensor networks. Most electrostatic generators (ESGs) use constant capacitors as storage or reservoir components in conjunction with a variable capacitor. The main issue with some existing ESG topologies is that these capacitors deplete and discharge over time. This paper studies a typical ESG and derives the charge depletion problem mathematically. Subsequently, a new ESG capable of circumventing this problem is proposed. Closed-form formulas expressing the output voltage and generated power are derived and validated. The proposed ESG harvests 25% of the power that the mechanical energy source generates by actuating the variable capacitor when the maximum-to-minimum capacitance ratio of the variable capacitor is optimized. In the presented case study, the ESG generates 9.75 mW optimally when a variable capacitor with a maximum/minimum capacitance ratio of 39/9.75μF is used for energy harvesting from a 1-Hz knee joint movement of a walking person. The overall volume of the ESG is estimated to be 125 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , and the variable capacitor is charged to 5 V at its maximum capacitance. A control mechanism and a self-starting circuit are presented for this ESG architecture, which allows it to generate any desired output voltage. This capability can be used to harvest the maximum available kinetic energy and compensate load variations.

An instrument for inducing continuous passive motion after fracture of the tibial plateau in rabbits

Objective To design and develop intelligent rehabilitation equipment for administering continuous passive motion (CPM) of a rabbit′s knee joint after tibial plateau fracture. Methods The equipment constructed had three main parts: the core machinery, electronic control and a control program designed based on bionics principles. Twenty six-month-old New Zealand White male rabbits were randomly divided into sedentary (SED) and CPM groups after their knees had been fractured. The rabbits in the CPM group were given 30 min of early joint rehabilitation once a day for 4 weeks using the CPM equipment, while those in the SED group were kept in their cages and allowed free activity without any special exercise program. The body weight, range of motion and swelling of the affected knee joint were measured before the fracture and on the 3rd, 7th, 14th, 21st and 28th days after the fracture. On the 28th day after the fracture the pathological structure of the articular cartilage on the operative side was observed under a light microscope. Results The equipment ran safely and reliably, and drove the rabbits to move synchronously. It could accurately and conveniently adjust the knee flexion angle, movement speed and movement time. The intelligence of the equipment met the experimental requirements. On the 3rd day after the operation the average range of motion in the joints of both groups had changed significantly compared to that before the fracture. On the 28th day after the fracture the average degree of swelling and range of motion in the CPM group were significantly different from those of the SED group. On the 28th day, deformity and the smoothness of the fracture line in the CPM group were superior to those in the SED group. Moreover, the dominant tissues in the defect area of the CPM group were mainly hyaline cartilage while those in the SED group were mainly repair fibrocartilage. The defect area and its adjacent articular cartilages, chondrocyte regeneration and arrangement, layers of cells and subchondral tidal line recovery of the CPM group were better than in the SED group on average. Conclusion The equipment for knee joint manipulation is convenient to use, reliable and effective for the early rehabilitation of tibial plateau fracture, at least in rabbits. It promotes remodeling of the fracture and cartilage repair after tibial plateau fracture, and also improves range of motion in the knee and reduces swelling. Key words: Passive motion; Tibial plateau fracture; Rehabilitation equipment

Treatment for posterior root tear of lateral meniscus through bone tunnel suture under arthroscopy

To evaluate clinical effects of posterior root tear of lateral meniscus through bone tunnel suture under arthroscopy. From January 2012 to December 2014, 23 patients with posterior root tear of lateral meniscus repaired through bone tunnel suture under arthroscopy, including 15 males and 8 females, aged from 19 to 48 years old with an average age of (25.0±4.7) years old; 10 knees on the left side and 13 knees on the right side. Complications were observed, Lysholm score before and after operation at 12 months were used to evaluate clinical results, and VAS score was applied to assess pain relief. MRI was used to check recovery outcomes of lateral meniscus injury. All patients were followed up from 13 to 24 months with an average of (17.0±4.3) months. No injury of vessels, nerve and incision infection occurred. Motion of knee joint of 19 patients reached normal, 4 patients manifested limited activity of knee joint at12 months after operation. Postoperative Lysholm score 88.52±6.48 at 12 months was higher than that of before operation 46.12±7.35; Postoperative VAS score 0.8±0.7 at 12 months was lower than that of before operation 4.3±1.6. Bone tunnel suture under arthroscopy for the treatment of posterior root tear of lateral meniscus could relieve pain, decrease postoperative complications and obtain good clinical efficacy.

Relations between external moment and movement of the knee joint during the stance phase in patients with severe knee osteoarthritis

BackgroundThe relations between external knee moment and the knee joint movement during stance phase of the patients with knee osteoarthritis is unknown well. This study try to clarify the relations between external knee moment and the knee joint movement during stance phase of the patients with knee osteoarthritis. MethodsSubjects comprised 15 patients who had 23 knees with severe osteoarthritis. The knee joint movements and external knee moments while walking were measured using a motion analysis system and a floor-mounted force plate. We then calculated the change in knee joint angles, first and second peak external knee adductions, and maximum flexion−extension moments during the stance phase. Pearson's product−moment correlation coefficient was used to confirm the relation between the external moments and knee movements. ResultsThe first peak external knee adduction moment was moderately positively correlated with the maximum knee varus angle at the early stance phase and was moderately negatively correlated with the amount of change in the knee valgus direction angle at mid-stance. The peak external knee extension moment at the early stance phase was strongly positively correlated with the knee flexion angle at foot-strike and the maximum knee flexion angle at the early stance phase and was negatively correlated with the external rotation angle at foot-strike. ConclusionAn effective rehabilitation approach to decrease the load of knee joint must combine both to strength the muscles around the knee joint, particularly quadriceps, and to device for controlling the knee movement.

Surface Electromyography Based Estimation of Knee Joint Angle by Using Correlation Dimension of Wavelet Coefficient

In this paper, we propose a regression model to establish a relationship between surface electromyography (sEMG) and knee joint angles. In this model, the correlation dimension of wavelet coefficient (WCCD) and an Elman network are developed for the model estimation. In our experiment, the sEMG signals were recorded from five muscles concerned with knee joint motion, and knee joint angles were simultaneously recorded by a Codamotion system. First, we used a feature extraction method based on WCCD to extract optimal feature vectors from multichannel sEMG signals. Then, the Elman network was used to map the optimal sEMG features to the knee joint angles. The results show that the features extracted from the multichannel sEMG signals using the WCCD method proposed in this paper outperform the time-domain and frequency-domain methods. Our method is expected to be applied to intelligent prosthetics, exoskeleton robots, and medical rehabilitation robots.

A prospective study of treatment of intertrochanteric fractures of femur by fixation with dynamic hip screw or proximal femur nailing

Purpose: Fractures of the proximal femur are more than ever, an important challenge in the field of traumatology. An anatomical reduction obtained at the expense of total devascularisation of the fracture is not a well-planned or well-executed procedure. One must always remember that any form of fixation is at best a splinting device with a definite life span and there is always a race between fracture union and failure of implant. Aims & Objectives: The aim is to study the clinical and radiological outcomes in case of reduction and stabilization of intertrochanteric femur fractures through DHS or PFN. The objectives are to study the advantages and principles of reduction and stabilization methods by DHS or PFN fixation for the treatment of intertrochanteric fractures of femur, to study the range of motion of hip and knee joints and functional outcome, to study complications of the technique. Material &Methods: After ethics committee clearance, subject recruitment procedure was followed. The sample size is total 100 cases with age between 18 to 100 years. The inclusion criteria include 1.Unstable intertrochanteric fractures with posteromedial comminution. 2. Patients with co-morbid conditions like diabetes, hypertension and ischemic heart disease. 3. All patients were ambulatory before the injury. The exclusion criteria include fractures other than intertrochanteric femur and non-ambulatory patients. Standard lateral approach was followed for the fixation of intertrochanteric femur fractures using dynamic hip screw or proximal femur nailing. Results: Out of 100 patients (48 males and 52 females), we have follow up of 67 patients with intertrochanteric femur fracture between July 2013 to May 2016. Majority of the patients in our series were male (53.7%) compared to females (46.3%). The average of male patient was 56 years and that of female patients was 69.9 years. Discussion: The mean Harris Hip Score of DHS is 89.07 and PFN is 89.00. Thus, there was no statistical significance for using DHS or PFN in per-trochanteric femur fractures. Conclusion: Implant selection for the patients must be based on the ability of the implant to withstand long term cyclical loading, the implant should splint the entire femur to bridge other potential areas of unrecognized or future metastatic disease. One must develop mastery over the usage of the implant in a particular fracture and then one can convert that implant as Gold standard for that fracture.

Incidence of anterior cruciate ligament injury in a rural tertiary care hospital.

Introduction:Knee is the largest joint in the human body with a very complex anatomy. It is a mobile trochoginglymus (i.e. a pivotal hinge joint), which permits flexion and extension as well as a slight medial and lateral rotation. Since the knee supports nearly the whole weight of the body, it is vulnerable to both acute injury and the development of osteoarthritis. The anterior cruciate ligament (ACL) is an important ligament for the proper movement of knee joint. ACL injury commonly causes knee instability than injury to other knee ligaments.Conclusion:In our study, we found the following: 1. Patients suffering from road traffic accidents have the highest rate of development of ACL injury department of Jawaharlal Nehru medical collage sawangi. 2. Twisting injuries/trivial fall injuries/injuries from fall on ground give the second highest numbers of ACL injuries in rural population. 3. Men are more prone to have ACL injury than women in rural population. 4. Patients falling in the age group of 16-25 years of age are more prone to have ACL injuries in rural population.

Electrostimulation has a positive effect on the knee function after knee arthroscopic surgery: A randomized trial.

There is a wide range of rehabilitation protocols after knee arthroscopic procedures, mainly based on specialist exercises. They comprise of specific stages and key moments but should also be individualized and adjusted to the patient's needs. The aim of the study was to evaluate the BodyFlow device impact on physical and psychological functioning of the subjects after knee arthroscopy. Ninety three patients were randomly divided into the study and control group. Each study group subject performed mild electrostimulation using the BodyFlow device for three weeks, five times a day for 20 minutes along with the standard rehabilitation protocol. Control group subjects were treated according to the standard rehabilitation protocol after knee arthroscopy. Healthy and operated lower limb size, a range of the knee joint motion, and the flexor and extensor strength were measured 3, 6, and 9 weeks after arthroscopy. At each measurement, the SF-36 and KOOS surveys were collected. On study day 21, a positive, statistically significant, difference in the knee joint size, range of flection and extension, flexor and extensor strength as well as all KOOS survey subscales and physical functioning categories included in the SF-36 survey was observed. On study day 63, positive effects persisted and significant differences in other categories included in the SF-36 survey were observed. Application of mild electrostimulation using the BodyFlow device has a positive impact on the swelling in the knee joint region, range of motion, extensor and flexor strength as well as physical, psychological, and social functioning.

LATERAL INSTABILITY OF THE KNEE JOINT AND DISORDER OF THE ANKLE JOINT EXTENSION DISORDER IN MEN

Introducion: The flexion of the knee joints in the movement of the squat may be accompanied by physiological varus deformity that increases smoothly with the lowering of the center of gravity, followed by a return to the starting position. Observing the disturbances of the physiological movement of the knee joints in the frontal plane, the authors correlated them with the mobility of the ankles in the sagittal plane. The aim: To show the relationship of knee joint motion disorders in the frontal plane with the movement of the ankle joints in the sagittal plane in the movement of the squat. The authors asked themselves about the number of subjects with the physiological mobility of both joints in the given planes and in what part of the subjects there are disorders and whether they relate to the ipsi or the contralateral part of the body. There was also the question of whether and in which group there are deviations not meeting the above criteria. Materials and methods: 20 healthy right-handed men aged 25-35 were examined with physiological mobility of lower limb joints, confirmed in a physiotherapeutic study. Exclusion criteria included: polyarticular laxity, systemic diseases, rheumatoid arthritis, osteoarthritis. The subjects performed a three-time squat after putting in the Biomech measuring system inertial sensors on the lower limbs and the pelvis. Assessment was related to the movement of the knee joint in the frontal plane with the movement of the ankle joint in the sagittal plane. Results: Alternating deformity with right knee valgus occurred in 16 people in the right knee joint (80% of subjects) and in 6 men in the left knee joint (30% of subjects). Three subjects (15%) had a degenerative disorder in both knee joints. The others presented physiological mobility or single (not correlating) disturbances in the mobility of selected joints. Conclusions: The tests confirmed that the ankle joint is functionally connected to the dysfunctional knee joint on the opposite side, despite various surfaces of mutual movement. Dysfunction of the knee joint is about 10 ° reduction of varus deformity during squat during maximum flexion of the knee joint and again varus deformation when lifting the center of gravity, which ends in distortion until the starting position. These deflections are accompanied by a decrease in the opposite ankle extension at the time of knee valgus deformity in the maximum flexion. The above dysfunctions occurred in 100% instability of the non-dominant knee joint, and on the dominant side in 63%.

What are the biomechanical consequences of a structural leg length discrepancy on the adolescent spine during walking?

BackgroundStructural leg length discrepancy (LLD) is a common phenomenon. However, its effect on spinal gait kinematics remains unclear. Research questionHow does LLD affect spinal gait kinematics in patients with structural LLD and what is the immediate effect of a shoe lift?. Methods10 adolescents with structural LLD (20–60 mm) and 14 healthy controls were included. All of whom were fitted with a trunk marker set and requested to walk barefoot as well as with an orthotic shoe lift (only patients). Data were collected using a 12-camera motion capture system. Group comparisons were conducted using one-dimensional Statistical Parametric Mapping (SPM). ResultsPatients with LLD showed statistically significant increased frontal plane lumbar bending angles to the longer side (p = 0.007), increased pelvic drop on the shorter side (p < 0.001) and increased hip adduction angles on the longer leg (p < 0.001) compared to the healthy controls. In the sagittal plane, patients demonstrated changed knee (shorter leg) and ankle joint (longer leg) motion. All gait deviations observed in patients with LLD could immediately be altered by correcting the LLD using a shoe lift. SignificanceDue to the LLD, patients showed a lateral pelvic drop on the shorter side, which appeared to be compensated for by a contralateral bending in the lumbar spine and a lateral shift of the pelvis towards the longer side. In addition, the use of an orthotic correction seems to be a suitable option to instantly normalize gait kinematics in patients with mild to moderate LLD.

Knee Angle Measurement Device Using Fiber Bragg Grating Sensor

Human joint kinematics has established its capacity as a vital tool for joint pathology and gait analysis. Range of motion (ROM) of a knee joint performed by flexion and extension is an essential tool to assess the efficacy of surgical interventions or therapeutic assessment. This paper proposes a novel wearable device for dynamic measurement of knee joint angle using fiber Bragg grating (FBG) sensor. The proposed knee angle measurement device (KAMD) can transduce the angular movement between the shin and the thigh into strain variations on a cantilever, which is acquired by the FBG sensor over it. The KAMD is also facilitated with tuneable sensitivity with three modes of high sensitivity mode, medium sensitivity mode, and low sensitivity mode, which can be opted based on application specific resolution and range of measurement. The ROM data obtained from the KAMD are validated against ROM obtained from commercially available Polhemus Sensors. Furthermore, the synchronization of the knee joint movement of both legs during walking along with stance and swing phase is illustrated, which shows the ability of KAMD to perform gait analysis. Employment of KAMDs on both legs eliminating the time synchronization complexity makes the proposed FBG-based KAMD an efficient means to evaluate the knee angle from both legs simultaneously.

Side-to-Side Differences in Varus Thrust and Knee Abduction Moment in High-Functioning Individuals With Chronic Anterior Cruciate Ligament Deficiency

Background: There is evidence that frontal plane knee joint motion plays a crucial role in the pathogenesis of knee osteoarthritis, yet investigation of individuals with chronic anterior cruciate ligament–deficient (ACLD) knees remains sparse. Purpose: To investigate (1) if individuals with chronic ACLD knees demonstrate higher biomechanical measures of medial knee load as compared with their anterior cruciate ligament–intact (ACLI) knees, (2) if differences in static knee alignment of the ACLD knee will demonstrate a difference in the magnitude of biomechanical measures of medial knee load when compared with the ACLI knee, and (3) the side-to-side concordance of varus thrust among individuals with chronic ACLD knees. Study Design: Descriptive laboratory study. Methods: Participants were sourced from a metropolitan orthopaedic surgeon group. Those who met the inclusion criteria and agreed to participate underwent a 3-dimensional gait analysis assessment to measure knee adduction moment (KAM), knee flexion moment (KFM), KAM peaks, KAM impulse, and varus thrust. Frontal plane knee static alignment was measured with a digital inclinometer fixed to medical calipers. The participants were divided according to their static knee alignment (neutral, varus, and valgus) for subgroup analysis. Peak knee angular velocity and frontal plane knee angle were used to establish if a participant was walking with a knee thrust. An individual was deemed to have knee thrust during gait if the largest frontal plane knee movement coincided with the peak knee angular velocity that occurred within the first 30% of stance phase. Results: Forty-five participants were recruited. The mean (SD) time from injury was 34.5 (55.6) months. ACLD knees did not demonstrate higher mean KAM and KFM (P > .5) or early-stance peak KAM (P = .3-.8) and KAM impulse (P = .3-.9) as compared with ACLI knees as a whole group or when the varus, neutral, and valgus alignment subgroups were investigated separately. Twenty-three percent (n = 9) of the participants had a varus thrust at the ACLD or ACLI knee, 44% (n = 4) had a varus thrust at the ACLD knee, and 22% (n = 2) had varus thrust at both knees. Conclusion: There were no side-to-side differences in mean KAM and KFM and early-stance peak KAM and KAM impulse among high-functioning individuals with chronic unilateral ACLD knees. There was a low prevalence of varus thrust among high-functioning individuals with chronic unilateral ACLD knees.