Higher contact pressure of the lateral tibiofemoral joint in lateral extra-articular tenodesis with tensioned graft in external rotation than in neutral rotation: a biomechanical study.

OBJECTIVE: To determine the mean contact pressure, peak contact pressure, and mean contact area of the lateral tibiofemoral joint in lateral extra-articular tenodesis (LET) with tension on the graft in tibial neutral and external rotation. METHODS: A total of eight Thiel's embalmed cadaveric knees were prepared and divided into two groups (4 knees in each group): the LET-NR group (lateral extra-articular tenodesis tension in neutral rotation) and (2) the LET-ER group (lateral extra-articular tenodesis tension in external rotation). Each knee was prepared according to the corresponding technique. A hydraulic testing system (E10000, Instron) simulates an axial load of 735 N for 10 seconds in each group. RESULTS: The LET-ER group exhibited a statistically significant higher peak contact pressure compared to the LET-NR group. The peak contact pressure values in the LET-NR and LET-ER groups were 702.3 ± 233.9 kPa and 1,235.5 ± 171.4 kPa, respectively (p = 0.010, 95% CI, -888.0--178.5). The mean contact pressure values in the LET-NR and LET-ER groups were 344.9 ± 69.0 kPa and 355.3 ± 34.9 kPa, respectively (p = 0.796, 95% CI, -105.1-84.2). The mean contact area values in the LET-NR and LET-ER groups were 36.8 ± 3.1 mm2 and 33.3 ± 6.4 mm2, respectively (p = 0.360, 95% CI, -5.2-12.2). CONCLUSIONS: The peak contact pressure of the lateral tibiofemoral joint is greater in LET when the graft is tensioned in external rotation than in neutral rotation. However, no statistically significant difference in the mean contact pressure or the mean contact area was observed between the two groups. LEVEL OF EVIDENCE: III.

Traditional suture tape versus multiple high-strength sutures for augmentation of anterior cruciate ligament primary repair: A time-zero biomechanical study.

Background/objective: During the initial stages of rehabilitation after anterior cruciate ligament (ACL) surgery, a pivotal role is played in ensuring effective recuperation and averting complications. An often-employed strategy to tackle ACL laxity during this period involves the incorporation of synthetic materials for reinforcement. The objective of this study is to compare the effectiveness of conventional suture tape and multiple high-strength sutures as augmentation techniques for ACL repair. Methods: Ten preserved cadaveric knees embalmed using the Thiel method were segregated into two groups, each containing five knees. In one group, traditional suture tape was employed for augmentation, while the other group utilized multiple high-strength sutures. Each knee underwent a cyclic load of 1000 sine wave cycles, succeeded by an axial distraction load until failure ensued. The resultant displacement and ultimate load at failure were assessed to contrast the efficacy of the two augmentation techniques. Results: The group utilizing multiple high-strength sutures exhibited a significantly higher load to failure at time-zero (1690.7 N) compared to the suture tape group (987.6 N) (P = .003). Furthermore, the multiple high-strength sutures group demonstrated significantly reduced displacement after 1000 cyclic loads (6.6 mm) in comparison to the suture tape group (16.3 mm) (P < .001). Conclusions: Multiple high-strength sutures show better biomechanical properties for the augmentation of ACL repair at time-zero. Both suture tape and multiple high-strength sutures had ultimate load-to-failure values higher than the natural ACL loads. Therefore, these substances might serve as augmentation options to prevent the ACL's gradual elongation, a critical concern particularly in the initial stages of rehabilitation.

Development of four-bar polycentric knee joint with stance-phase knee flexion.

A conventional 4-bar polycentric knee and solid ankle cushion heel foot (SACH foot) have been commonly used in developing countries. However, they cannot perform stance-phase knee flexion, which makes a person with an amputation walk unnaturally and with less stability. This research proposes a novel design of a 4-bar polycentric knee with stance-phase knee flexion ability (4BSF), which can perform both stance and swing-phase knee flexion, like able-bodied gait. In the proposed conceptual design, the instantaneous center of rotation (ICR) path is repositioned during the stance phase. The ICR was placed in front of the ground reaction force (GRF) to initiate knee flexion during the loading response. The prototype was validated by a single-subject pilot study at the Gait analysis laboratory. The results showed that a person with an amputation walks with stance-phase knee flexion using the proposed 4BSF. The maximum knee flexion angle is more than 10° during the stance phase. Furthermore, when the 4BSF was used with a SACH foot, the amount of time to achieve the foot flat was shorter, and the foot flat duration time was twice as long as the conventional 4-bar polycentric knee.

Cortical suspensory button fixation has superior biomechanical properties to knotless anchor suture in anterior cruciate ligament repair: a biomechanical study.

The purpose of our biomechanical study was to assess load-to-failure, stiffness, gap formation following cyclic loading, and the failure mechanism for anterior cruciate ligament (ACL) repair comparing the cortical suspensory button and knotless anchor suture. Eight Thiel's embalmed paired cadaveric knees from four cadavers were dissected. The specimens were assigned to undergo ACL repair either with cortical suspensory button or with knotless anchor suture. The Instron machine replicates cyclic loading and then determines the gap formation. Traction was applied until failure. The load-to-failure, stiffness, and modes of failure in both groups were recorded. The load-to-failure, stiffness, and gap formation were compared between the two groups using the student's t-test. The mean load-to-failure in the cortical suspensory button group was significantly higher than the knotless anchor suture group (212.96 ± 54.57 vs 44.57 ± 20.80, p value < 0.01). No statistically significant difference was found regarding gap formation following cyclic loading and stiffness between the cortical suspensory button group and the knotless anchor suture group. This biomechanical study showed a higher load-to-failure for the ACL repair with cortical suspensory button compared to ACL repair with knotless anchor suture, while no statistically significant difference was found regarding the gap formation following cyclic loading and the stiffness. The load-to-failure in both cortical suspensory button and knotless anchor suture are below regular daily activity load. Thus, an internal brace or external support is recommended during rehabilitation.

3D reconstruction of proximal femoral fracture from biplanar radiographs with fractural representative learning.

A femoral fracture is a severe injury occurring in traumatic and pathologic causes. Diagnosis and Preoperative planning are indispensable procedures relying on preoperative radiographs such as X-ray and CT images. Nevertheless, CT imaging has a higher cost, radiation dose, and longer acquisition time than X-ray imaging. Thus, the fracture 3D reconstruction from X-ray images had been needed and remains a challenging problem, as well as a lack of dataset. This paper proposes a 3D proximal femoral fracture reconstruction from biplanar radiographs to improve the 3D visualization of bone fragments during preoperative planning. A novel Fracture Reconstruction Network (FracReconNet) is proposed to retrieve the femoral bone shape with fracture details, including the 3D Reconstruction Network (3DReconNet), novel Auxiliary class (AC), and Fractural augmentation (FA). The 3D reconstruction network applies a deep learning-based, fully Convolutional Network with Feature Pyramid Network architecture. Specifically, the auxiliary class is proposed, which refers to fracture representation. It encourages network learning to reconstruct the fracture. Since the samples are scarce to acquire, the fractural augmentation is invented to enlarge the fracture training samples and improve reconstruction accuracy. The evaluation of FracReconNet achieved a mIoU of 0.851 and mASSD of 0.906 mm. The proposed FracReconNet's results show fracture detail similar to the real fracture, while the 3DReconNet cannot offer.

High-Level Mobility of Trans-Tibial Prosthesis Users Wearing Commercial and sPace Energy-Storing Prosthetic Feet.

Outcomes of users provided with a commercial ESR Vari-Flex foot (Össur, Reykjavik, Iceland) and a locally designed sPace foot were investigated. Step activity with users' own prosthetic foot compared to the sPace foot was explored. METHODS: Eleven individuals with unilateral trans-tibial amputation participated and were provided with an sPace and Vari-Flex foot. Ten- and twenty-meter walk tests (10/20MWT) at comfortable and fast walking speeds (CWS/FWS), the two-minute walk test (2-MWT) and Comprehensive High-Level Activity Mobility Predictor (CHAMP) were administered. A subgroup was provided a pedometer to record their steps over a 7-day period in their own foot and later the sPace. RESULTS: The sPace foot performed well in a battery of high-level mobility outcome measures. On CHAMP, participants scored 16.94 ± 5.41 and 16.72 ± 6.09 with the sPace and Vari-Flex feet, respectively. Subgroup testing of step activity showed 4490 ± 3444 steps in users' own feet and 3115 ± 1967 in the sPace foot, p = 0.176. CONCLUSIONS: Participants using the sPace foot were capable of performing walking, high-level mobility and activity outcome measures.

Design and evaluation of a hydraulic mechanism with available components for passive knee prostheses.

BACKGROUND: Hydraulic knee prosthesis can provide stance phase control and swing phase control suitable for active persons with an amputation. However, typical commercial hydraulic knees are costly and require frequent maintenance making them inaccessible for persons with an amputation in low-income countries. The objective of this article is to present a new design for a low-cost hydraulic knee prosthesis. METHOD: The prototype hydraulic knee is made of simple hydraulic components. The hydraulic system was designed to provide flexion locking during the stance phase and damping during the swing phase of gait. RESULTS: The prototype was tested and results show that the hydraulic knee can prevent flexion of the knee at stance phase when the highest external knee flexion moment in the gait cycle occurs. The prototype mechanism is capable of resisting flexion torque of 60 N-m. CONCLUSIONS: The prototype hydraulic knee can be assembled from available hydraulic components for low cost and ease of maintenance which is feasible for persons with an amputation in low-income countries.IMPLICATIONS FOR REHABILITATIONA new design hydraulic knee which assembled from simple hydraulic components which provide both stance control and swing control.The use of simple hydraulic components makes the knee feasible for low-income country where service and maintenance staff is inadequate.

A performance study of a wearable balance assistance device consisting of scissored-pair control moment gyroscopes and a two-axis inclination sensor.

Excessive postural sway while standing can lead to falls and injuries. A designed wearable balance assistance device which consists of scissored-pair control moment gyroscopes and a two-axis inclination sensor is introduced to reduce fall risk from excessive sway among the elderly. The prototype has dimensions of H50cm × W44cm × D30cm and weighs 15.03 kg. This study aims to investigate the effects of generated torque of the prototype on human subjects and aims to determine if the two-axis inclination sensor can detect sway amplitude and sway direction during an occurrence of excessive sway. Two healthy male subjects participated in the study. According to the results, the detected body incline angle related to the acquired sway amplitude of COP trajectories with correlation factors of 0.92 and 0.88 for the two subjects. The detected sway angle related to the acquired sway direction of COP trajectories with the correlation factors of 0.99 and 0.98 for the two subjects. The maximum-allowable generated torque of the prototype with an assigned actuating angle varying within ±15.6° from the acquired sway direction of COP trajectories was able to drive the COP of 60-kilogram-weighted healthy subject maintaining balance at posterolateral limits of stability with an average body incline angle of 5.74° to pass his standing secure zone. The results indicate that the prototype has the potential of being a wearable balance assistance device which can reduce fall risk from excessive sway among the elderly; however, some improvements are still required in regards to shape, size, mass, generated torque, and strength.

An application of scissored-pair control moment gyroscopes in a design of wearable balance assistance device for the elderly.

Impaired balance control ability and degraded functional mobility increases the risk of falling in elderly people. The elderly show more postural sway when standing compared with young people. A sway fall occurs when the center of gravity moves outside the limit of stability. In order to reduce the fall risk from the excessive sway, this study presents the design of wearable balance assistance device for the elderly. Scissored-pair control moment gyroscopes were selected as a torque actuator. A two-axis inclination sensor was used to detect the inclined angle of the wearer's body. The direction of sway was calculated from the detected inclined angle. The designed device weighs 8.2 kg with a height of 32 cm × width of 40 cm × depth of 22 cm. A multi-segment model of a standing human was used to investigate the device's performance for balance recovery. According to the simulations, balance recovery in any direction was successfully accomplished with the appropriate initial angle. The relationship between the effective initial angle and detected inclined angle was subsequently established. The stability provided by activation of the device was able to limit the unstable user's sway boundary. The designed device shows promise for use as a balance assistance device for the elderly.

Design of Multi-Grip Patterns Prosthetic Hand With Single Actuator.

In hand prosthesis design, the important characteristics that directly affect hand performance are the ability to grasp various type of objects, grasping force that provides stability for holding objects, and cosmetic appearance that resembles the human hand. The presence of all of these characteristics is currently a challenging task for prosthesis design. This paper presents the design of a five-fingered prosthetic hand that has multiple grip patterns with the use of only one actuator in order to perform important tasks in daily life and which achieves significant grip force from the large size of the actuator. The prosthetic hand is capable of performing one neutral position and two grip patterns that are dominant in daily life tasks. Different move patterns are achieved through the use of multiple sets of rigid four-bar linkages which provide different motions to fingers and thumb when the mechanism is actuated to the opposite direction. This paper describes the design of the prosthesis, mechanism synthesis, and achieved performance. The prosthetic hand developed here, having one degree of freedom, is an improvement from conventional single-actuator hands, which can only perform open/close motion. Whereas achieved grip force (34.5 N) is higher than multiple-actuator hands in market. Thus, this design could be an alternative answer of improvement between conventional and multiple degree of freedom prosthetic hands.

The reversible adjustable coupling: A lightweight and low-cost alignment component for the lower limb prosthesis.

BACKGROUND: The alignment of the lower limb prosthesis is an integral part of the prosthetic fitting. A properly aligned prosthesis contributes to optimal gait and overall function of the patient. The current offering of alignment componentry is expensive for low-income countries. The purpose of this study was to develop a lightweight and low-cost alignment coupler for the lower limb prosthesis. METHODS: An alignment coupler called the reversible adjustable coupling was designed and manufactured. Measurements of total anterior/posterior and medial/lateral and rotation in prostheses were recorded and mechanical testing performed. Swiftness and difficulty of use was also recorded. RESULTS: The reversible adjustable coupling permitted acceptable ranges of anterior/posterior and medial/lateral translation and 30° of internal and external rotation of prosthetic componentry. Repetitive loading of the coupling at a speed of 1 Hz under 1.28 kN load for 2000 cycles was successful, as were static and strength tests. DISCUSSION: The coupler provided acceptable ranges of anterior/posterior and medial/lateral and rotation adjustment and is acceptable for potential use in the alignment of both exoskeletal and endoskeletal prosthesis. The final weight of the component was 166 g and cost of $55.00 USD is affordable for low-income countries for use in clinical and educational settings.

A biomechanical cadaveric study of a modified U-shaped interspinous distraction device.

STUDY DESIGN: An experimental study. OBJECTIVE: To analyze the effects of a modified U-shape interspinous distraction device (IDD) on the stability of a destabilized lumbar spine model. SUMMARY OF BACKGROUND DATA: The use of IDD for treatment of lumbar spine pathology remains a subject of debate. A modified design of an IDD consisted of a titanium (Ti) U-shape dynamic stabilizer and a Ti tensioning wire loop was biomechanically tested. MATERIALS AND METHODS: Six sets of cadaveric lumbar vertebrae levels 1-5 (L1-L5) were subjected to loads in flexion, extension, and lateral bending in the 4 following sequences: intact specimen, unilateral facetectomy and discectomy at L3-L4, insertion of the modified U-shape IDD at L3-L4, and pedicle screw fixation at L3-L4. The range of motion (ROM) of L3-L4 following modified U-shape IDD insertion was compared with that of the intact specimen. The ROM of the adjacent vertebrae (L2-L3 and L4-L5) following modified U-shape IDD insertion was compared with that after pedicle screw fixation. Statistical analysis was performed using the Wilcoxon signed-rank test. RESULTS: The modified U-shape IDD decreased the ROM of a destabilized L3-L4 in all testing load (P<0.05). The stability of L3-L4 following the modified U-shape IDD insertion was restored to that of the intact specimen (P>0.05). The ROM at adjacent vertebrae after the modified U-shape IDD placement was similar to the ROM obtained after pedicle screw fixation at L3-L4. CONCLUSIONS: The modified version of a U-shape IDD is effective in stabilizing an unstable segment of the lumbar spine. The device does not create deleterious effects on the adjacent vertebrae.