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Introduction Reportedly, wearable robots, such as the hybrid assistive limb (HAL), are effective in the functional recovery of various locomotor disabilities, including disrupted walking, restricted range of motion, and muscle weakness. However, the effect of walking exercises with a HAL on the kinematic and kinetic variables of lower limb joint function is not yet fully understood. Therefore, the purpose of this study was to elucidate the effect of HAL on the kinematic and kinetic variables of lower limb function in patients 5 weeks after total knee arthroplasty (TKA). Materials and Methods Nine patients (ten knees) in the HAL training group and nine patients (nine knees) in the control group underwent TKA. HAL training was initiated 1–5 weeks after TKA, and general rehabilitation was performed in the control group. Gait analysis was performed on each patient using a motion analysis system at 5 weeks after TKA. We compared the effects of the joint angles of the walking cycle between groups, and investigated the effect of the walking cycle’s joint angles on step length. Results In the HAL group, the odds ratio of hip extension was as large as 1.741, while that of knee swing was as large as 1.501. These 2 variables were significant between the 2 groups. Knee swing and varus significantly affected step length. Conclusions Our results suggest that training by wearing HAL after TKA increased the mobility of the knee and hip joints during early postoperative walking, and that walking ability was improved by increasing the step length.

Fixation of posterior malleolar fractures with plates or screws is under debate. A fatigue loading system and a spatial motion capture system were used in this study to evaluate a posterior malleolar fracture model.Thirty-six below-knee specimens with a single posterolateral fragment (Haraguchi I) type posterior malleolar fracture models were randomly divided into 2 groups. Two parallel-placed 3.5-mm partially threaded titanium alloy screws were used in Group A to fix the fractures, while anatomical plates were used in Group B. According to the ratio (S) of the area between the fracture and the total articular surface, each group was subdivided into 3 subgroups. In group A1 and B1, S=1/4; in A2 and B2, S=1/3; and in A3 and B3, S=1/2. To simulate the gait cycle, each specimen was subjected to mechanical loading in 4 different ankle positions. A fatigue loading system was used for repeated loading. A spatial motion capture system was used to measure the displacement in the final loading stage.Despite the limited sample size and relatively low power, no significant difference was observed between A1 and B1, A2 and B2, and A3 and B3 in all 4 ankle positions after repeated loading.For a Haraguchi type I posterior malleolar fracture with an average height of 19 mm, fixation with a posterior malleolar anatomical plate failed to demonstrate a stronger strength than 2 parallel-placed 3.5-mm partially threaded screws, which indicates that plates may not be absolutely necessary for standard rehabilitation after posterior malleolar internal fixation.These findings may help guide surgeons with regard to fixation requirements for posterior malleolar fractures.

The micromotion distribution of a cementless stem relative to femoral bone and the stress transfer were calculated with a three dimensional model including bone non-homogeneity, anisotropy and discontinuity of the bone-implant interface. Two implant designs (anatomical, straight) were investigated to point out the geometry effects. Micromotion distributions were calculated over the entire interface during a complete gait cycle taking into account the hip musculature forces. Different loading levels (from 20% to 100% of total load) were stimulated. For the two implants, peak values of distractive and shear micromotions were maximal at the Single Limb Stance phase. The implant geometry had no sensible effects on distractive micromotion magnitude. Conversely, the implant design had noticeable influences on shear micromotions. Regarding the effects of loading levels, at 20% of the full load, interface shear micromotions were lower than 30μm over the entire interface allowing bony ingrowth and expected to ensure initial stability for both implants. At 40%, shear micromotions exceeding 30μm appeared and were located differently according to the stem design.

Background Functional ankle instability is a clinical syndrome that may develop after acute lateral ankle sprain. Although several causes of this functional instability have been suggested, it is still unclear what the activation pattern of the peroneus longus muscle is in patients with functional ankle instability. Hypothesis Peroneus longus activation patterns differ in the injured side and the uninjured side in subjects with functional ankle instability. Study Design Descriptive laboratory study. Methods The authors examined 14 subjects with functional ankle instability by using surface electromyography during walking. Activation time of the peroneus longus muscle was expressed as a percentage of the stance phase of the gait cycle. Results A statistically significant decrease in peroneus longus muscle activity was found in the injured side compared with the uninjured side (22.8% ± 4.25% vs 37.6% ± 3.5%, respectively). Conclusions Results obtained in this study show a change in peroneus longus muscle activation time after injury. Independent of the origin of this change, which could only be surmised, the decrease in peroneus longus muscle activity may result in reduced protection against lateral sprains. Clinical Relevance The assessment of peroneus longus activation pattern during gait is useful to design an appropriate rehabilitation program in athletes suffering from functional ankle instability.

The importance of clinical studies notwithstanding, the failure assessment of implant–bone structure has alternatively been carried out using finite element analysis. However, the accuracy of the finite element predicted results is dependent on the applied loading and boundary conditions. Nevertheless, most finite element–based evaluations on acetabular component used a few selective load cases instead of the eight load cases representing the entire gait cycle. These in silico evaluations often suffer from limitations regarding the use of simplified musculoskeletal loading regimes. This study attempts to analyse the influence of three different loading regimes representing a gait cycle, on numerical evaluations of acetabular component. Patient-specific computer tomography scan-based models of intact and resurfaced pelvises were used. One such loading regime consisted of the second load case that corresponded to peak hip joint reaction force. Whereas the other loading regime consisted of the second and fifth load cases, which corresponded to peak hip joint reaction force and peak muscle forces, respectively. The third loading regime included all the eight load cases. Considerable deviations in peri-acetabular strains, standard error ranging between 115 and 400 µε, were observed for different loading regimes. The predicted bone strains were lower when selective loading regimes were used. Despite minor quantitative variations in bone density changes (less than 0.15 g cm−3), the final bone density pattern after bone remodelling was found to be similar for all the loading regimes. Underestimations in implant–bone micromotions (40–50 µm) were observed for selective loading regimes after bone remodelling. However, at immediate post-operative condition, such underestimations were found to be less (less than 5 µm). The predicted results highlight the importance of inclusion of eight load cases representing the gait cycle for in silico evaluations of resurfaced pelvis.

Research on the relationship between gait asymmetry and the likelihood of slips are not clear, especially, for older adults. The present study evaluated the gait asymmetry among older adults and, further, evaluated effects of gait asymmetry on the likelihood of slips. Eighteen older adults (65 and older) participated in the study. HCV, horizontal force, and RCOF measured at non-dominant leg during heel contact phase of gait cycle were significantly higher than those at dominant leg. The results indicated that the likelihood of slips could increase when transitioning the whole body center-of-mass with left leg contacted on the ground while right leg was in swing phase. The results indicated that gait asymmetry or limb dominance could contribute to increasing the likelihood of slips.

The zero moment point (ZMP), foot rotation indicator (FRI) and centroidal moment pivot (CMP) are important ground reference points used for motion identification and control in biomechanics and legged robotics. In this paper, we study these reference points for normal human walking, and discuss their applicability in legged machine control. Since the FRI was proposed as an indicator of foot rotation, we hypothesize that the FRI will closely track the ZMP in early single support when the foot remains flat on the ground, but will then significantly diverge from the ZMP in late single support as the foot rolls during heel-off. Additionally, since spin angular momentum has been shown to remain small throughout the walking cycle, we hypothesize that the CMP will never leave the ground support base throughout the entire gait cycle, closely tracking the ZMP. We test these hypotheses using a morphologically realistic human model and kinetic and kinematic gait data measured from ten human subjects walking at self-selected speeds. We find that the mean separation distance between the FRI and ZMP during heel-off is within the accuracy of their measurement (0.1% of foot length). Thus, the FRI point is determined not to be an adequate measure of foot rotational acceleration and a modified FRI point is proposed. Finally, we find that the CMP never leaves the ground support base, and the mean separation distance between the CMP and ZMP is small (14% of foot length), highlighting how closely the human body regulates spin angular momentum in level ground walking.

A novel control algorithm for the foot placement of walking bipedal robots is proposed which can output the optimal step time and step location to obtain a desired walking gait from every feasible robot state. The step time and step location are determined by approximating the robot dynamics with the 3D linear inverted pendulum model and analytically solving the constraint equations. Intensive simulation studies are conducted to check the validity of the theoretical results. The results of this study show that the proposed control algorithm can get the system to a desired gait cycle from every feasible state within a finite number of steps.

The subtalar joint plays an important role in the biomechanics of walking and running. Inversion of the subtalar joint allows supination, which stabilizes the foot, and eversion allows pronation, which unlocks the foot during the gait cycle. Injuries to the subtalar joint are often improperly diagnosed and can be extremely detrimental to an athlete. Consequences of these injuries include not only pain but also an impaired ability to walk or run, especially on nonlevel surfaces, because of compromised subtalar motion. We report two cases of fracture in the subtalar joint in springboard divers. Both fractures occurred with a similar mechanism of injury. A computed tomography (CT) scan was essential to delineate the magnitude of injury. This injury has not been previously described in springboard divers.

This article investigates the relative effectiveness in the ways in which physiotherapy exercises are administered to patients with residual stroke. The exercises were designed to improve walking by increasing the ability of the affected limb to bear weight during the single support phase of the gait cycle and, therefore, to increase the duration of this phase, thereby making the gait pattern more symmetrical. Twenty patients were divided into four equal groups, one of which acted as a control, receiving no treatment. The other three groups received exercises for two 1-h sessions per week supervised by a physiotherapist in an outpatient facility (group A), by a spouse or companion at home (group B), or by a combination of these (group C). Treatment was given for 6 months with assessments at monthly intervals during and for 3 months posttreatment. Results from this study indicate that on any given visit there were no differences between any of the four groups with respect to increasing the duration of sing...

Isolated posterior ligamentous insufficiency of the knee frequently terminates an athlete's career and may even adversely affect the performance of tasks of daily living. Return to competitive athletics following surgical reconstruction for posterior instability is un usual. The pathophysiology of the lesion and a bio mechanical analysis are discussed. A case report of an athlete with a ruptured posterior cruciate ligament who is presently successfully competing in profes sional football is also presented. Rigorous quantitative techniques were employed to document the compen satory mechanisms involved. These consisted of ex tremely strong quadriceps muscles contracting much earlier than normal in the gait cycle. Earlier quadriceps contraction to increase dynamic stability in the knee is able to overcome the instability resulting from the incompetent posterior cruciate ligament.

Background: Controversy exists regarding the optimal bony fixation technique for lateral meniscal allografts. Purpose/Hypothesis: The objective was to quantify knee joint contact mechanics across the lateral plateau for keyhole and bone plug meniscal allograft transplant fixation techniques throughout simulated gait. It was hypothesized that both methods of fixation would improve contact mechanics relative to the meniscectomized condition, while keyhole fixation would restore the distribution of contact stress closer to that of the intact knee. Study Design: Controlled laboratory study. Methods: Six human cadaveric knees were mounted on a multidirectional dynamic simulator and subjected to the following conditions: (1) native intact meniscus, (2) keyhole fixation of the native meniscus, (3) bone plug fixation of the native meniscus, and (4) meniscectomy. Contact area, peak contact stress, and the distribution of stress across the tibial plateau were computed at 14% and 45% of the gait cycle, at which axial forces are at their highest. Translation of the weighted center of contact stress throughout simulated gait was computed. Results: Both bony fixation techniques improved contact mechanics relative to the meniscectomized condition. The keyhole technique was not significantly different from the intact condition for the following metrics: contact area, peak contact stress, distribution of force between the meniscal footprint and cartilage-to-cartilage contact, and the position of the weighted center of contact. In contrast, bone plug fixation resulted in a significant decrease of 21% to 28% in contact area at 14% and 45% of the simulated gait cycle, a significant increase in peak contact stresses of 34% at 45% of the gait cycle, and a shift in the weighted center of contact, which increased forces in the cartilage-to-cartilage contact area at 45% of the gait cycle. Conclusion: While both keyhole and bone plug fixation methods improved lateral compartment contact mechanics relative to the meniscectomized knee, keyhole fixation restored contact mechanics closer to that of the intact knee. Clinical Relevance: Method of meniscal fixation is under the direct control of the surgeon. From a biomechanics perspective, keyhole fixation is advocated for its ability to mimic intact knee joint contact mechanics.

Background. Clinical trials in spinal cord injury (SCI) primarily rely on simplified outcome metrics (ie, speed, distance) to obtain a global surrogate for the complex alterations of gait control. However, these assessments lack sufficient sensitivity to identify specific patterns of underlying impairment and to target more specific treatment interventions. Objective. To disentangle the differential control of gait patterns following SCI beyond measures of time and distance. Methods. The gait of 22 individuals with motor-incomplete SCI and 21 healthy controls was assessed using a high-resolution 3-dimensional motion tracking system and complemented by clinical and electrophysiological evaluations applying unbiased multivariate analysis. Results. Motor-incomplete SCI patients showed varying degrees of spinal cord integrity (spinal conductivity) with severe limitations in walking speed and altered gait patterns. Principal component (PC) analysis applied on all the collected data uncovered robust coherence between parameters related to walking speed, distortion of intralimb coordination, and spinal cord integrity, explaining 45% of outcome variance (PC 1). Distinct from the first PC, the modulation of gait-cycle variables (step length, gait-cycle phases, cadence; PC 2) remained normal with respect to regained walking speed, whereas hip and knee ranges of motion were distinctly altered with respect to walking speed (PC 3). Conclusions. In motor-incomplete SCI, distinct clusters of discretely controlled gait parameters can be discerned that refine the evaluation of gait impairment beyond outcomes of walking speed and distance. These findings are specifically different from that in other neurological disorders (stroke, Parkinson) and are more discrete at targeting and disentangling the complex effects of interventions to improve walking outcome following motor-incomplete SCI.

Objectives: Gait analysis is a proven method for assessing knee biomechanical adaptations in anterior cruciate ligament deficient (ACLD) patients and to quantify the impact of the reconstructive surgery (ACLR). In an adult population, ACLR has shown partial kinematic correction, as they remain in internal tibial rotation, putting them at risk of rotational instability and develop osteoartitis. ACLD adolescents likely adopt similar gait changes to reduce knee instability, but may show quicker or more return to the normal compared to adults. The purpose of this study is to compare the tridimensional (3D) knee kinematics before and after ACLR in adolescents. Methods: 25 ACLD patients aged between 13 and 19 years old on a waiting list for ACLR were recruited. Bilateral knee 3D kinematic data was gathered during treadmill walking at comfortable self-selected speed using the KneeKGTM System before and 6-9 months after ACLR. Each participant underwent the same surgical protocol (2-strand hamstring tendon graft, hamstring harvest proximally and kept distally, transphyseal tibial tunnel and transepiphyseal femoral tunnel) by the same experienced surgeon. Three analyses were done: ACLD knee pre vs. post-surgery, contralateral healthy knee pre vs. post-surgery, and ACLR knee vs. healthy contralateral knee. Results: In the sagittal and transverse planes, kinematic patterns remained similar to the pre-op; maintaining the characteristic knee flexion gait pattern during single support phase which is well documented in adult ACLD (hamstring facilitation strategy). The ACLR knee exhibited a more valgus dynamic alignment compared to pre-surgery throughout the gait cycle. The healthy contralateral knee kinematics displayed no significant changes in the frontal and sagittal planes after surgery compared to the pre-op pattern. In the transverse plane, post-op gait analysis showed significantly more external rotation at heel-strike and through weight acceptance. While looking at the gait symmetry post-surgery, ACLR knee revealed significantly more valgus while remaining in greater flexion during single limb support. In the transverse plane, an external rotation tendency is observed in the ACLR knee throughout the gait cycle, except during weight acceptance. Conclusion: This study shows that kinematic adaptations found in ACLD adolescents are likely to endure short term after surgery. For example, the greater knee flexion gait pattern used before surgery is still used after ACLR. Interestingly, adolescents used an external tibial rotation adaptation to limit internal tibial instability before the surgery and this pattern was still present post-surgery. Even if theses protection strategies are efficient, the increased dynamical valgus movement seen could place the graft under pressure while increasing patellofemoral stresses, a common complaint after ACLR. Lastly, post-surgery, the contralateral knee seems to mimic the external tibial rotation gait pattern strategy seen in ACL-knee. This study demonstrates that gait protective strategies are still present short term after the surgery. Biomechanical assessment helps ID these adaptations to optimize post-op rehabilitation and prevent secondary injuries.

The objectives of this pilot study were to develop a video fluoroscopy kinematics method for the assessment of the coxofemoral joint in cats with and without osteoarthritis (OA)-associated disability. Two non-OA cats and four cats affected by coxofemoral OA were evaluated by video fluoroscopy. Video fluoroscopic images of the coxofemoral joints were captured at 120 frames/s using a customized C-arm X-ray system while cats walked freely on a treadmill at 0.4 m/s. The angle patterns over time of the coxofemoral joints were extracted using a graphic user interface following four steps: (i) correction for image distortion; (ii) image denoising and contrast enhancement; (iii) frame-to-frame anatomical marker identification; and (iv) statistical gait analysis. Reliability analysis was performed. The cats with OA presented greater intra-subject stride and gait cycle variability. Three cats with OA presented a left–right asymmetry in the range of movement of the coxofemoral joint angle in the sagittal plane (two with no overlap of the 95% confidence interval, and one with only a slight overlap) consistent with their painful OA joint, and a longer gait cycle duration. Reliability analysis revealed an absolute variation in the coxofemoral joint angle of 2º–6º, indicating that the two-dimensional video fluoroscopy technique provided reliable data. Improvement of this method is recommended: variability would likely be reduced if a larger field of view could be recorded, allowing the identification and tracking of each femoral axis, rather than the trochanter landmarks. The range of movement of the coxofemoral joint has the potential to be an objective marker of OA-associated disability.

The effects of tears of the anterior cruciate ligament on knee kinematics and contact mechanics during dynamic everyday activities, such as gait, remains unclear. The objective of this study was to characterize anterior cruciate ligament–deficient knee contact mechanics and kinematics during simulated gait. Nine human cadaveric knees were each augmented with a sensor capable of measuring dynamic normal contact stresses on the tibial plateau, mounted on a load-controlled simulator, and subjected to physiological, multidirectional, dynamic loads to mimic gait. Using a mixed model with random knee identifiers, confidence intervals were constructed for contact stress before and after anterior cruciate ligament transection at two points in the gait cycle at which axial force peaked (14% and 45% of the gait cycle). Kinematic and contact mechanics changes after anterior cruciate ligament transection were highly variable across knees. Nonetheless, a statistically significant increase in contact stress in the posterior–central aspect of the medial tibial plateau at 45% of the gait cycle was identified, the location of which corresponds to the location of degenerative changes that are frequently found in patients with chronic anterior cruciate ligament injury. The variability in the contact stress in other regions of the medial plateau at 45% of the gait cycle was partly explained by the variations in osseous geometry across the nine knees tested. At 14% of gait, there was no significant change in peak contact stress after anterior cruciate ligament transection in any of the four quadrants, and none of the possible explanatory variables showed statistical significance. Understanding the variable effect of anterior cruciate ligament injury on contact mechanics based on geometric differences in osseous anatomy is of paramount clinical importance and may be invaluable to select the best reconstruction techniques and counsel patients on their individual risk of subsequent chondral degeneration.

Background: Prior studies reported improved gait after total ankle arthroplasty and better parameters of gait than those reported in earlier studies of patients after ankle arthrodesis. However, there are very limited data prospectively evaluating the effects on gait after ankle arthroplasty compared with ankle arthrodesis. Controversy remains regarding the relative advantages and disadvantages of these 2 treatments and especially the differences in function between them. Methods: We performed a prospective study involving 28 patients with posttraumatic and primary ankle osteoarthritis and a control group of 14 normal volunteers. We compared gait in 14 patients who had undergone ankle arthrodesis with the gait of 14 patients who had ankle arthroplasty preoperatively and at 1 year postoperatively. Three-dimensional gait analysis was performed with a 12-camera digital-motion capture system. Temporospatial measurements included stride length and cadence. The kinematic parameters that were measured included the sagittal plane range of motion of the ankle and the coronal plane range of motion of the ankle. Double force plates were used to collect kinetic parameters such as ankle coronal and plantar flexion–dorsiflexion moments and sagittal plane ankle power. Center of pressure (CoP) and its progression in gait cycle were calculated. Results: Baseline parameters showed comparability among the treatment and control groups. Temporospatial analysis, using time as the main effect, showed that compared with ankle arthrodesis, patients with total ankle arthroplasty had higher walking velocity attributable to both increases in stride length and cadence as well as more normalized first and second rockers of the gait cycle. Kinematic analysis, using time and intervention as the main effects, showed that patients who had ankle arthroplasty had better sagittal dorsiflexion ( P = .001), whereas those undergoing ankle arthrodesis had better coronal plane eversion ( P = .01). Neither ankle arthrodesis nor arthroplasty altered the CoP progression during stance phase. Total ankle arthroplasty produced a more symmetrical vertical ground reaction force curve, which was closer to that of the controls than was the curve of the ankle arthrodesis group. Conclusions: Patients in both the arthrodesis and arthroplasty groups had significant improvements in various parameters of gait when compared with their own preoperative function. Neither group functioned as well as the normal control subjects. Neither group was superior in every parameter of gait at 1 year postoperatively. However, the data suggest that the major parameters of gait after ankle arthrodesis in deformed ankle arthritis are comparable to gait function after total ankle arthroplasty in nondeformed ankle arthritis. Level of Evidence: Level II, prospective comparative study.

Category: Basic Sciences/Biologics Introduction/Purpose: Using computer-controlled electro-hydraulic servo technology, we studied the improved “four-dimensional six degrees-of-freedom” gait simulation system based on motor and hydraulic hybrid drive control and achieved the human body’s normal gait cycle with fresh cadavers Methods: Through the superimposed combination of a composite servo motor drive mechanism, a highly precise “four-dimensional six degrees-of-freedom” at the tibia could be achieved using fresh cadavers below the knee. At the same time, ten sets of independently controlled electro-hydraulic servo hydraulic cylinders were used to achieve the mechanical loading of the tendon and tibia to reproduce the dynamic and kinematic parameters of the normal gait cycle with the cadaver model Results: The time for the system to complete a gait cycle was controlled at approximately three seconds. The coordinate motion curve of the tibia in the six degrees-of-freedom space was consistent with the M curve of the normal gait cycle, and the measurement results of plantar stress were similar to the measurement curves of the normal gait cycle. Conclusion: The improved “four-dimensional six degrees-of-freedom” gait simulation system successfully reproduced a gait cycle that was the closest to the normal gait cycle among all existing research.

Category: Ankle, Trauma Introduction/Purpose: Purpose of this research is to biomechanically compare the screw-fixed and plate-fixed posterior malleolus fracture in osteoporosis patients with fatigue loading system and space motion system in simulation gait cycle. And to give a theory evidence on how to choose a internal fixation in osteoporosis patients with posterior malleolus fracture. Methods: 36 matched cadaveric pairs lower limbs (T＜-2.5) were prepared to simulate Haraguchi I posterior malleolus fracture and randomized into two groups. Models of group A were fixed with two paralleled 4.0 mm titanium partial thread cancellous screws from posterior to anterior. Models of group B were fixed with plate. Furthermore, 4 different conditions of gait cycle were simulated as follows:1. specimen was loaded with 3.2 body weight (BW) at dorsiflexion angle of 12°; 2. Start-up phase: dorsiflexion angle of 5°,3.6 BW; 3. neutral position,3.6 BW; 4. maximum plantar flexion, angle of 12°,4.5 BW. At the end of repeatedly, loading, the displacement of fracture fragment (X) was measureed with space motion system. Results: At 12°of dorsiflexion and 15°of plantar flexion, there was a significant difference of X between A and B group, no matter the S and H. When ankle was dorsiflexion of 5°, X of group A was more great than that of group B except A3a /B3a and A1b/B1b. At neutral positon, there was significant differenceof X in all the groups except group A2b and B2b. Conclusion: Compared with 2 paralleled 4.0 mm calcaneus screws from posterior to anterior, plate can provide stronger fixation for osteoporosis patients with posterior malleolus fracture. But both of the two methods cannot provide stable fixation for osteoporosis patients with posterior malleolus fragment S>1/3 and H>19.3 mm.

The purpose of this study was to determine whether peripheral arterial disease (PAD) subjects had impaired temporal and spatial gait characteristics compared to non-PAD controls at preferred and rapid self-selected walking paces. A total of 28 PAD subjects with intermittent claudication (age = 71 -1; mean -SEM) and 15 non-PAD controls with at least one cardiovascular risk factor but no ambulatory leg pain (age = 71 -1) were recruited. Gait parameters consisting of velocity, cadence, stride length, swing time, stance time, single-support time, double-support time, and base of support were recorded at the preferred and rapid walking paces. At the rapid walking pace, velocity was 22% slower (p, 0.001) in the PAD subjects compared with the non-PAD controls (99.9 - 3.3 vs. 117.5 - 5.3 cm/s) due to an 8% (p = 0.019) slower cadence (99.9 - 1.7 vs. 103.3 - 2.4 steps/min) and a 14% (p, 0.001) shorter stride length (119.8 - 2.9 vs. 135.8 - 4.2 cm/stride). The PAD subjects spent 5% less of the gait cycle in the swing phase (p = 0.006) and 3% more in stance (p = 0.006) than their non-PAD counterparts. During the stance phase, the PAD subjects spent 5% less of the gait cycle in single-stance (p = 0.004) and 16% more in double-stance (p = 0.007). Similar results were obtained at the preferred walking pace. In conclusion, compared with the controls, PAD subjects adopted an ambulatory pattern that favored greater gait stability at the expense of greater walking speed at either their preferred or rapid self-selected paces.

Background: The treatment strategies for meniscal injuries during anterior cruciate ligament (ACL) reconstruction remain a topic of debate. Hypothesis: After ACL reconstruction, knee kinematics would be affected by different medial meniscal treatment (partial medial meniscectomy [PMM] and medial meniscal repair [MMR]). Study Design: Controlled laboratory study. Methods: A total of 161 patients underwent primary single-bundle ACL reconstruction and simultaneous medial meniscal treatment. Of these, 32 patients were eligible to participate in the kinematic assessment at 24.8 ± 1.7 months after surgery. Patients were divided into 2 groups: (1) those who underwent MMR (Group MMR; n = 18) and (2) those who underwent PMM (Group PMM; n = 14). Twenty healthy participants (Group Intact) were recruited who were comparable in age, body mass index, and sex. The kinematic parameters were collected using an optical tracking system during treadmill gait. Range of motion and kinematic parameters at key events during the gait cycle were compared between the 3 groups. The primary outcomes were the differences in adduction/abduction and internal/external rotation. Results: Patients in Group PMM walked with increased adduction as compared with those in Group Intact during the early stance phase ( P = .003; η2 = 0.172) and midstance phase ( P = .003; η2 = 0.167). In terms of internal/external rotation, patients in Group PMM walked with significantly larger tibial external rotation when compared with Group MMR by approximately 3.4° to 3.7° (loading response: P = .026, η2 = 0.090; midstance: P = .035, η2 = 0.093) and Group Intact ( P = .028; η2 = 0.095) in the early stance phase. In addition, there was significantly increased anterior tibial translation in Groups MMR and PMM compared with Group Intact. Conclusion: ACL reconstruction (via transtibial technique) with concurrent PMM demonstrated larger adduction and external tibial rotation at 24 months of follow-up during level walking. Clinical Relevance: Patients undergoing different medial meniscal treatment strategies in the presence of ACL reconstruction showed distinct knee kinematics. These results suggest that MMR is strongly recommended during ACL reconstructive surgery to reduce the abnormal kinematics close to that of the ACL-intact condition.

Category: Basic Sciences/Biologics Introduction/Purpose: Hallux valgus (HV) is a common condition that may lead to considerable pain and disability. While a number of gait analyses of people with and without HV have been performed using planter pressures, the results to date are not in agreement. In the last two decades, several multi-segmental foot models (MFMs) have been introduced for the in vivo analysis of dynamic foot kinematics. Although there are some investigations about triplanar multisegmental of patients with HV, there were lack of age and gender matched comparison of inter-segmental foot motions in previous reports. The objective of this study was to find the effect of hallux valgus deformity on inter-segmental motion of the foot by comparisons with age and gender controlled healthy adults using a multi-segmental foot model (MFM) with 15-marker set. Methods: Eighteen female symptomatic hallux valgus patients (SHV group) and 50 female symptom-free older female participants who had normal function of the foot and ankle and no radiographic evidence of osteoarthritis were included in this study. Symptom-free participants were divided into asymptomatic hallux valgus group (AHV, n=14) and control group (CON, n=36). For radiographic examinations, hallux valgus angle was measured using standing anteroposterior radiograph of the foot. The temporal gait parameters such as the cadence, speed, stride length, step width, step time, and proportion of stance phase were calculated. Segmental foot kinematics evaluated using a 3D MFM of a 15-marker set (Foot3D model). Inter-segmental angles (ISA) (hindfoot relative to tibia, forefoot to hindfoot, and hallux to forefoot) were calculated at each time points (100 time points for whole gait cycle). The ISAs (position) at specific phases of gait cycle, the change of ISA (motion) between phases and range of ISAs during the whole gait cycle were calculated and compared among groups. Results: Basic demographic data was no significant difference among groups except HV angle and foot width. The speed, stride length were significantly lower in SHV group. The proportion of the stance phase in a gait cycle was longer SHV group. Range of motion (ROM) of sagittal plane of hallux and transverse plane of forefoot was lower in SHV group. Significantly different finding in SHV group included more dorsiflexed position of hallux segment, reduced forefoot abduction motion during terminal stance and loss of push off during preswing(Figure 1). However, when we compared AHV group and CON group, there was no difference in temporal gait parameters and ROM of inter-segmental motions of foot. Hallux segment was in more valgus position and the forefoot segment was in more pronated position in AHV group than in CON group. Conclusion: Symptomatic hallux valgus patients showed different gait parameters & inter-segmental motion during gait when compared with age-matched controls. Asymptomatic hallux valgus does not affect gait & inter-segmental motion during gait except that the hallux segment was in more valgus position and the forefoot segment was in more pronated position. The results of this study suggest that effect of moderate hallux valgus itself on foot kinematics might be limited while pain or arthritic change of the joint might cause changes in gait in patients with symptomatic HV.

The kinematics of stair climbing were examined to test the assertion that relative timing is an invariant feature of human gait. Six male and four female subjects were video-recorded (at 60 Hz) while they climbed a flight of stairs 10 times at each of three speeds. Each gait cycle was divided into three segments by the maximum and minimum angular displacement of the left knee and left foot contact. Gentner's (1987) analysis methods were applied to the individual subject data to determine whether the duration of the segments remained a fixed proportion of gait cycle duration across changes in stair-climbing speed. A similar analysis was performed using knee velocity maxima to partition the gait cycle. Regardless of how the gait cycle was divided, relative timing was not found to remain strictly invariant across changes in speed. This conclusion is contrary to previous studies of relative timing that involved less conservative analysis but is consistent with the wider gait literature. Strict invariant relative timing may not be a fundamental feature of movement kinematics.

Effectiveness of knee braces remains to be identified. Therefore, the purpose of this study was to investigate the effectiveness of bilateral single-hinged knee bracing in knee osteoarthritis (OA) using finite element (FE) method. A three-dimensional FE model consisted of main model (knee-brace structure) and submodel (strap-muscle system) was developed. The submodel was used to convert the elastic strap-muscle interaction into an equivalent stiffness value required by the main model. Adding 100 N · mm/rad torsion spring to the brace with 5 kPa strap pressure lowered maximum von Mises stress in the knee OA components at a flexion angle greater than or equal to 90°. Separately, employing 10% brace pre-tension to the brace with 5 kPa strap pressure started to reduce stresses at a flexion angle of 70°. The configuration involving a combination of 10% brace pre-tension and 300 N · mm/rad torsion spring with 30 kPa strap tightness produced stress reduction over the entire range from 0° to 100° flexion angle. The basic bilateral single-hinged knee brace has shown to reduce stresses in the knee OA at high flexion angles only. Compared to the torsion spring, the brace pre-tension has shown to provide more significant benefits (i.e. stress reduction at lower flexion angles). The most sophisticated effects were achieved when the torsion spring was used in combination with the brace pre-tension. These two features can be potentially used for the development of an active knee brace if they can be modulated at different flexion angles or during the gait cycle.

Objectives: Anterior cruciate ligament (ACL) reconstruction is among the most common procedures performed in orthopaedics. Patient reported outcomes (PRO) are widely utilized to evaluate symptoms, activity, and participation in sport after ACL reconstruction. Although altered in vivo knee kinematics after ACL reconstruction have been reported, the association with PRO has not been established. The purpose of this study was to determine the relationship between PRO and dynamic knee kinematics as tracked by a Dynamic Stereo X-ray system (DSX system). Methods: Fifty subjects (33 males, age: 24.2 years ± 7.6, BMI: 24.7 ± 2.97) participating in a randomized clinical trial to compare anatomic single- and double-bundle ACL reconstruction underwent surgery using quadriceps tendon bone block autograft. Six months post-operatively, patients performed downhill treadmill running (3.0 meters/second, 10° slope) within a DSX system (150 hertz). Knee kinematics, determined using a validated process of matching DSX images and subject-specific tibiofemoral bone models derived from computed tomography scans, were expressed as a function of the gait cycle. Involved limb and differences in side-to-side kinematics were analyzed from foot-strike to mid-stance phase (0-15% gait cycle corresponding to the loading phase). Subjects also completed the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF) and Knee Injury and Osteoarthritis Outcome Score (KOOS). Correlation coefficients were calculated to determine the associations between PRO and knee kinematics. Results: Greater post-operative knee flexion and more symmetric restoration of knee flexion and axial rotation in comparison to the contralateral knee had the highest correlations with the IKDC-SKF and KOOS Sports and Recreation and Knee-Related Quality of Life subscales (p < 0.05). Symmetry of anterior tibial translation and varus-valgus rotation of the surgical knee were less strongly associated with PRO. Conclusion: Knee kinematics when running 6 months after ACL reconstruction were associated with patient-reported symptoms, activity, and participation levels. Therefore, clinicians should strive for anatomic precision during ACL reconstruction to optimally restore knee kinematics so as to achieve optimal PRO.

Slips and falls are common injuries among restaurant and food service workers. It is estimated that food service workers have 60% higher rate of occupational injury or illness than workers in other industry. This study investigates effects of asymmetric load carriage at shoulder level on gait characteristics. Each participant walked with a service tray held at shoulder height. Each participant’s gait was analyzed under 3 different load walking conditions, no load walking (NLW), intermediate load walking (ILW) (2.5% BW), and maximum load walking (MLW) (5% BW). We found that participants walked significantly slower with gait cycle time 1.125s versus 1.150 s in MLW compared to NLW(p

Hip abductor tendon tear is a difficult problem to manage. The hip abductor mechanism is made up of the gluteus medius and minimus muscles, both of which contribute to stabilising the pelvis through the gait cycle. Tears of these tendons are likely due to iatrogenic injury during arthroplasty and chronic degenerative tendinopathy. Ultrasound and magnetic resonance imaging have provided limited clues regarding the pattern of disease and further work is required to clarify both the macro and microscopic pattern of disease. While surgery has been attempted over the last 2 decades, the outcomes are variable and the lack of high-quality studies have limited the uptake of surgical repair. Hip abductor tendon tears share many features with rotator cuff tears, hence, innovations in surgical techniques, materials and biologics may apply to both pathologies.

Background: Traditional running gait analysis is limited to artificial environments, but whether treadmill running approximates overground running is debated. This study aimed to compare treadmill gait analysis using fixed video with outdoor gait analysis using drone video capture. Hypothesis: Measured kinematics would be similar between natural outdoor running and traditional treadmill gait analysis. Study Design: Crossover study. Level of Evidence: Level 2. Methods: The study population included cross-country, track and field, and recreational athletes with current running mileage of at least 15 km per week. Participants completed segments in indoor and outdoor environments. Indoor running was completed on a treadmill with static video capture, and outdoor segments were obtained via drone on an outdoor track. Three reviewers independently performed clinical gait analysis on footage for 32 runners using kinematic measurements with published acceptable intra- and interrater reliability. Results: Of the 8 kinematic variables measured, 2 were found to have moderate agreement indoor versus outdoor, while 6 had fair to poor agreement. Foot strike at initial contact and rearfoot position at midstance had moderate agreement indoor versus outdoor, with a kappa of 0.54 and 0.49, respectively. The remaining variables: tibial inclination at initial contact, knee flexion angle initial contact, forward trunk lean full gait cycle, knee center position midstance, knee separation midstance, and lateral pelvic drop at midstance were found to have fair to poor agreement, ranging from 0.21 to 0.36. Conclusion: This study suggests that kinematics may differ between natural outdoor running and traditional treadmill gait analysis. Clinical Relevance: Providing recommendations for altering gait based on treadmill gait analysis may prove to be harmful if treadmill analysis does not approximate natural running environments. Drone technology could provide advancement in clinical running recommendations by capturing runners in natural environments.

Femoral neck prostheses have been developed for the treatment of osteoarthritis in young and active patients. The concept combines a bone-conserving and minimal invasive technique with proximal load transferring by metaphyseal anchoring, which results in a more physiological loading pattern. However, little is known about the morphology of periprosthetic fractures. Thus, the aim of this study was to describe fracture patterns and to determine patient-specific factors favoring periprosthetic fracture. This study was performed as a biomechanical experimental study using 10 fresh frozen femora and 10 Silent-Hip femoral neck implants (DePuy International Ltd., Leeds, UK). In order to simulate physiological loading, a static muscle reconstruction (abductor muscles and iliotibial band) and a dynamic simulation of the gait cycle were applied. During biomechanical testing (50% and 100% of normal weight-bearing), three periprosthetic fractures with two different morphologies occurred. The first pattern corresponds to an abrupt breakaway. The second type was of spiral configuration extending to the diaphyseal region and emerging from an initial fissure. Specimen-specific factors favoring periprosthetic fracture were body mass index and varus angle of the implant. Periprosthetic fractures may extend to the subtrochanteric/diaphyseal region and may be of spiral configuration. According to the finding of this study, body mass index and varus/valgus position of the implant are important factors influencing the risk of periprosthetic fractures. Furthermore, partial weight-bearing as part of the postoperative regimen may be favorable.

People suffering from neuromuscular diseases may also face certain abnormalities in their walking pattern. Patients with quadriceps muscle weakness suffer from flexion contracture as well as flexion instability during the gait cycle. In this article, a knee-ankle-foot orthosis design is proposed with two different mechanisms for the stance and swing phases, addressing the needs of patients with quadriceps muscle weakness. The stance phase mechanism locks the knee joint movement from the initial contact until the end of mid-swing and after mid-stance phase, the knee joint can flex freely. OpenSim was utilized to simulate patients with muscle weakness as well as calculating the required moment to mimic the stiffness of a normal knee joint. The super-elasticity of shape memory alloys was then used to reproduce the calculated moment for different levels of muscle weakness. It is shown that by designing patient-specific orthosis, the stiffness profile of normal joint for each patient with distinct level of muscle weakness can be reproduced.

Category: Basic Sciences/Biologics Introduction/Purpose: Stair walking is one of common activities of daily living. It is more demanding than level walking and can aggravate discomfort of the foot, such as Morton’s neuroma, plantar fasciitis, Achilles tendinitis, pressure related-ulcer, and etc. Therefore, analysis of increased pressure in specific plantar area at stair walking can be used as a risk assessment of foot discomfort and basic data in the clinical field. The purpose of this study is to analyze plantar pressure distribution and pressure patterns during gait cycle at stair walking compared to level walking. Methods: Fourty healthy male adults were recruited. Radiologic measurements and gait analysis were performed to check participants’ normality, and 35 healthy males with 20-28 years old were included. They performed level walking (18 meters walkway), stair (26 steps stair, height:16.7 cm, depth:29.8 cm) ascending, and descending in same type of running shoes. Measurements of in-shoe plantar pressure including peak pressure, pressure-time integral (PTI) were done by Pedar-X system. Only measurements of right steps were used to exclude the effect of the dominant foot. The sole was masked in 7 segments (hallux, 2nd-5th toes, medial forefoot, central forefoot, lateral forefoot, midfoot, heel region) to analyze properly. Percentages were assigned in relation to the size for each mask segment. Statistical analysis was performed using repeated measure ANOVA, and Bonferroni post hoc test was done. Results: Mean peak pressures in all regions except for the midfoot were higher during level walking than stair walking. During stair descent, mean peak pressures in all the regions except for the midfoot were generally lower than other types of walking, but it was the highest in the midfoot region. Pressure time integral (PTI) in the medial and central forefoot was higher during stair descent than level walking. PTI in the central and lateral forefoot, and the midfoot was higher when stair ascending than level walking. Pressure time integral (PTI) in the heel region was the highest during level walking, followed by stair ascent, stair descent. Conclusion: The risk of aggravation of discomfort in the midfoot area increases when stair descending. The medial region of forefoot bear high pressure load during stair descent, and the lateral region of forefoot and the midfoot region bear high pressure load during stair ascent. This is the first study to show plantar pressure patterns during level and stair walking in the large healthy gender-controlled population. We recommend that patients with pressure related foot lesions in the forefoot or midfoot avoid stair walking.

Background and Objective: Physical performance in older men has been reported in analyses with veterans and in disease-based cohort research. Studies examining gait performance among older monks, however, are narrow. The purpose of this study was to analyze the impact of a recent fall on gait ability in a cohort of Benedictine and Trappist monks in 4 US monastic communities. The second aim was to analyze physical activity and a recent fall as predictive markers of 2 constructs of gait performance. Methods: In this cross-sectional study, 53 Benedictine and Trappist monks over 60 ( x = 74.7 ± 7.6; range: 61-94 years) completed a basic sociodemographic and fall history profile, the Timed Up and Go (TUG) Test, Dynamic Gait Index (DGI) and the Physical Activity Scale for the Elderly (PASE). Results: Demographic profiles revealed that 10% of participants had fallen over the past 3 months; in addition, those who had fallen were more likely to limit activities because of fear of falling ( P = .005). Monks who had fallen over the past 3 months demonstrated significantly poorer TUG (12.6 ± 2.1 vs 10.5 ± 1.8; P = .01) and DGI (17.2 ± 5.3 vs 22.3 ± 2.3; P Conclusions: Gait performance is linked to a recent fall episode among older monks. Predictive determinants of functional mobility (TUG) and superimposing tasks on the gait cycle (DGI) include recent fall history and physical activity. Appropriate health promotion activities can be aligned with these lifestyle attributes in monastic communities.

Although poor walking is the most common symptom of peripheral artery disease (PAD), reported results are inconsistent when comparing gait parameters between PAD patients and healthy controls. This inconsistency may be due to frailty, which is highly prevalent among PAD patients. To address this hypothesis, 41 participants, 17 PAD (74±8 years) and 24 aged-matched controls (76±7 years), were recruited. Gait was objectively assessed using validated wearable sensors. Analysis of covariate (ANCOVA) tests were used to compare gait parameters between PAD and non-PAD groups, considering age, gender, and body mass index as covariates, while stratified based on frailty status. According to the Fried frailty index, 47% of PAD and 50% of control participants were non-frail and the rest were classified as pre-frail. Within non-frail participants, gait speed, body sway during walking, stride length, gait cycle time, double-support, knee range of motion, speed variability, mid-swing speed, and gait initiation were significantly different between PAD and control groups (effect size d = 0.75±0.43). In the pre-frail group, however, most of the gait differences were diminished except for gait initiation and gait variability. Results suggest that gait initiation is the most sensitive parameter for detecting gait impairment in PAD participants when compared to controls, regardless of frailty status ( d = 1.30–1.41; p

Background: Bone–patellar tendon–bone (BTB) grafts are generally believed to heal more quickly than soft tissue grafts after anterior cruciate ligament (ACL) reconstruction, but little is known about the time course of healing or motion of the grafts within the bone tunnels. Hypothesis: Graft-tunnel motion will be greater in hamstring (HS) grafts compared with BTB grafts and will be less at 1 year than at 6 weeks. Study Design: Controlled laboratory study. Methods: Twelve patients underwent anatomic single-bundle ACL reconstruction using HS or BTB autografts (6 per group) with six 0.8-mm tantalum beads embedded in each graft. Dynamic stereo x-ray images were collected at 6 weeks and 1 year during treadmill walking and stair descent and at 1 year during treadmill running. Tibiofemoral kinematics and bead positions were evaluated. Graft-tunnel motion was based on bead range of motion during the loading response phase (first 10%) of the gait cycle. Results: During treadmill walking, there was no difference in femoral tunnel or tibial tunnel motion between BTB or HS grafts at 6 weeks (BTB vs HS: 2.00 ± 1.05 vs 1.25 ± 0.67 mm [femoral tunnel]; 1.20 ± 0.63 vs 1.27 ± 0.71 mm [tibial tunnel]), or 1 year (BTB vs HS: 1.62 ± 0.76 vs 1.08 ± 0.26 mm [femoral tunnel]; 1.58 ± 0.75 vs 1.68 ± 0.53 mm [tibial tunnel]). During stair descent, there was no difference in femoral or tibial tunnel motion between BTB and HS grafts at 6 weeks or 1 year. With running, there was no difference between graft types at 1 year. For all results, P values were > .05. Knee kinematics were consistent with the literature. Conclusion: During walking and stair descent, ACL reconstruction using suspensory fixation yielded no difference between graft types in femoral or tibial tunnel motion at 6 weeks or 1 year. All subjects were asymptomatic with knee kinematics similar to that of the literature. The significance of persistent, small (1 to 3 mm) movements at 1 year for healing or graft performance is unknown. Clinical Relevance: These study results may have significant implications for graft choice, rehabilitation strategies, and timing for return to sports.

Background: Gait analysis constitutes an essential part of orthopedic rehabilitation assessment. Previous studies indicate that observational-based gait analysis lacks reliability and requires extensive clinical training. Therefore, gait analysis in the clinical practice heavily relies on technical aids. The aim of the present study is to develop a reliable gait analysis assessment tool that can accurately assess clinically relevant gait cycle parameters in daily clinical practice. Methods: In this pilot study, a new gait analysis and motion score (GAMS), comprising 10 observational and 5 technically measured (e.g. pressure plate) gait parameters, was developed. The parameters were dichotomously operationalized, reflecting pathological versus physiological manifestations of the parameters. The rating algorithm was administered by 12 raters using videotaped treadmill sessions of 10 orthopedic subjects ( n = 120 ratings). Inter-rater reliability was calculated using the intraclass correlation coefficient (ICC) and the percentage of rating agreement. Results: The mean (standard deviation (SD)) GAMS ratings ranged from 10.0 (1.1) to 21.5 (1.3) points. The overall GAMS ICC was 0.98 (95% confidence interval (CI) 0.96–1.00), whereas the ICC of observational parameters alone was 0.97 (95% CI 0.93–0.99). The mean (SD) percentage of rating agreement was 86.1% (3.3%). For the observational parameters, the mean (SD) rating agreement was 82.5% (4.5%). Conclusion: This new GAMS shows excellent overall inter-rater reliability for a continuum of functional gait statuses. The new score may be an appropriate clinical tool to objectively evaluate patients’ gait patterns. Furthermore, the GAMS may find application as a clinician-reported outcome measure in orthopedic rehabilitation. Further studies are required to verify the validity and accuracy of the new GAMS and its functionality in assessing clinical changes in gait patterns.

Leg loading and knee angle differences have been reported in total knee replacement individuals during straight gait; however, little is known about the impact on the knee during turning. Rotary motions may be difficult following total knee replacement surgery; therefore, some individuals may develop strategies or utilize pre-surgical strategies in order to maintain function. The primary aim of this study was to identify differences in individuals with a total knee replacement as compared to their healthy counterparts during stair descent followed by a cross-over turn. Ground reaction force, knee angle and moments were recorded on 10 total knee replacement and 12 healthy individuals during stair descent followed by a turn and compared to walking straight. Variables were analyzed for the affected, unaffected and healthy knees during the gait cycle. On initial contact, the total knee replacement group had less ground reaction force on the affected leg compared to the unaffected leg (p = 0.021) and had delayed contact (p = 0.044) and a slower loading rate (p = 0.020) compared to healthy group. During mid-stance, the affected leg had less ground reaction force compared to the healthy leg (p = 0.049). The affected stance leg had less knee flexion during mid-stance in both the straight trial (p = 0.002) and turn (p = 0.010). Moment differed between straight and turn trials but not between groups. Stair descent with or without a turn was approached in a precautionary manner by individuals with a total knee replacement. Slow approach, reduced impact and weight-bearing with a more extended knee on the affected leg may suggest a protective strategy to avoid risk of fall.

A functional linear discriminant analysis approach to classify a set of kinematic data (human movement curves of individuals performing different physical activities) is performed. Kinematic data, usually collected in linear acceleration or angular rotation format, can be identified with functions in a continuous domain (time, percentage of gait cycle, etc.). Since kinematic curves are measured in the same sample of individuals performing different activities, they are a clear example of functional data with repeated measures. On the other hand, the sample curves are observed with noise. Then, a roughness penalty might be necessary in order to provide a smooth estimation of the discriminant functions, which would make them more interpretable. Moreover, because of the infinite dimension of functional data, a reduction dimension technique should be considered. To solve these problems, we propose a multi-class approach for penalized functional partial least squares (FPLS) regression. Then linear discriminant analysis (LDA) will be performed on the estimated FPLS components. This methodology is motivated by two case studies. The first study considers the linear acceleration recorded every two seconds in 30 subjects, related to three different activities (walking, climbing stairs and down stairs). The second study works with the triaxial angular rotation, for each joint, in 51 children when they completed a cycle walking under three conditions (walking, carrying a backpack and pulling a trolley). A simulation study is also developed for comparing the performance of the proposed functional LDA with respect to the corresponding multivariate and non-penalized approaches., MTM2017-88708-P, Spanish Ministry of Economy and Competitiveness (also supported by the FEDER program) and IJCI-2017-34038, Agencia Estatal de Investigación, Ministerio de Ciencia, Innovación y Universidades.

Background: An Achilles tendon rupture (ATR) is known to cause persistent biomechanical deficits such as decreased muscle strength in end-range plantar flexion and reduced tendon stiffness. Purpose/Hypothesis: This study aimed to examine whether sustained asymmetries were present in dynamic stiffness and kinematic and kinetic variables in gait and single-leg balance at 4.5-year follow-up in conservatively treated patients recovering from an ATR. We hypothesized that patients who had recovered from ATRs exhibit a midterm increase in peak ankle dorsiflexion, a decrease in concentric work, and decreased dynamic stiffness during the stance phase of gait, along with increased single-leg standing sway in the injured leg compared with the uninjured leg. Study Design: Case series; Level of evidence, 4. Methods: This study was a cross-sectional medium-term follow-up of conservatively treated patients recovering from ATRs. A total of 34 patients who underwent nonoperative treatment were included for testing 4.5 years after a rupture. The Achilles tendon length was measured using ultrasound. Standard instrumented 3-dimensional (3D) gait analysis and single-leg standing balance were performed using 3D motion capture. Kinematic and kinetic ankle parameters were calculated during gait, and quasi-stiffness was calculated as the moment change per the change in the degree of dorsiflexion during the second (ankle) rocker of the gait cycle. Center of pressure displacement (sway length), along with rambling and trembling, was calculated for the single-leg balance task. Results: Peak dorsiflexion in stance was 13.4% larger in the injured leg than the uninjured leg (16.9° ± 3.1° vs 14.9° ± 0.4°, respectively; P ≤ .001). Peak dorsiflexion was not associated with the normalized Achilles tendon length (B = 0.052; P = .775). Total positive work in the plantar flexors was 23.9% greater in the uninjured leg than the injured leg (4.71 ± 1.60 vs 3.80 ± 0.79 J/kg, respectively; P = .001). Quasi-stiffness was greater in the uninjured leg than the injured leg during the initial (0.053 ± 0.022 vs 0.046 ± 0.020 N·m/kg/deg, respectively; P = .009) and late (0.162 ± 0.110 vs 0.139 ± 0.041 N·m/kg/deg, respectively; P = .005) phases of eccentric loading. No difference was found in sway length during single-leg stance between the injured and uninjured legs (1.45 ± 0.4 vs 1.44 ± 0.4 m, respectively; P = .955). Conclusion: Patients treated conservatively have a small increase in peak dorsiflexion, decreased total concentric plantar flexor power, and decreased quasi-stiffness in initial and end-range dorsiflexion in the injured leg. These deviations could not be directly associated with the measured tendon elongation. Registration: NCT02760784 ( ClinicalTrials.gov ).

Background: One of the rationales for total ankle arthroplasty (TAA) is that it may retard the changes of hypermobility and accelerated arthritis in the hindfoot after ankle arthrodesis. Until recently, it has not been possible to quantify or even objectively demonstrate biomechanical findings to substantiate the theory that postsurgical biomechanical changes in the ankle produce changes in the kinematics of the hindfoot. Standard gait analysis has treated the foot as a single biomechanical unit. This study was undertaken to describe the hindfoot motion following Scandinavian Total Ankle Replacement (STAR) TAA by using multisegment foot model gait analysis. Methods: Forty-six patients with a mean age of 66 years underwent a 3D gait analysis following TAR. Mean interval between surgery and gait analysis was 4.9 years (range 2 to 9). The contralateral limb was used as control for each patient. Temporospatial variables and kinematic parameters were studied. Results: Temporospatial results showed statistically significant differences. Stance time on the affected side was 61.1% ± 2.2% of the gait cycle compared to 63.2% ± 2.1% for the unaffected side. Step length was 55.6 cm ± 10 on the affected side compared to 53.9 cm ± 10 for the unaffected side. Kinematics results were statistically significant: Ankle range of motion (ROM) on the arthroplasty side was 16.8 ± 4.5 degrees compared to 23.6 ± 5.0 on the unaffected side. Sagittal plane ROM was 12.7 ± 4.2 degrees on the arthroplasty side and 17.3 ± 3.5 degrees on the unaffected side. Coronal plane ROM was 4.7 ± 2.4 degrees on the arthroplasty side and 7.5 ± 2.4 degrees on the unaffected side. Transverse plane ROM on the arthroplasty side was 4.1 ± 1.5 degrees and 4.9 ± 1.6 on the unaffected side. Conclusion: This study showed that, in addition to previously documented diminution in sagittal plane motion and gait velocity, some of the residual abnormalities of gait following TAR were comprised of differences in hindfoot function. These results relate to the growing recognition of the importance of understanding hindfoot mechanics apart from those of the tibiotalar joint. Level of Evidence: Level III, comparative case series.

The Win-Track platform is an instrument used to measure plantar pressures and gait parameters during barefoot walking. The objective of this study was to determine the test-retest reliability of the system in assessing plantar pressures and temporal gait variables between 1-step and 3-step gait protocols. A total of 30 healthy participants (18 women and 12 men; age 23.7 ± 4.75 years) were recruited for the study. The 1-step gait protocol exhibited good reliability in terms of single stance, step duration and swing duration of the left foot; stride duration of the right foot; stride length; and step length of the right foot, with intraclass correlation coefficients (ICCs) ranging from 0.75 to 0.88. The 3-step gait protocol showed good reliability, with ICC values ranging between 0.75 and 0.90 in cadence; step duration of the right foot; double-stance duration and swing duration of the right foot; stride length of the right foot; step length and gait cycle length of the right and the left foot; and the area covered by the first, second, and third foot. The authors concluded that the Win-Track platform provided reliable plantar pressures and temporal gait measures, and the 3-step gait protocol showed better reliability compared with the 1-step gait protocol. Level of Evidence: Diagnostic, Level IV

The process of adaptive bone remodeling can be simulated with a self-optimizing finite element method. The basic remodeling rules attempt to obtain a constant value for the strain energy per unit bone mass, by adapting density. The precise solution is dependent on the loads, initial conditions, and the parameters of the remodeling rule. While there are several investigations on developing algorithms leading to the bone density distribution in the proximal femur, these algorithms often require a large number of iterations. The aim of this study was to develop a more efficient adaptive bone remodeling algorithm, and to identify how the bone density distribution of the proximal femur was affected by parameters that govern the remodeling process. The forces at different phases of the gait cycle were applied as boundary conditions. The bone density distributions from these forces were averaged to estimate the density distribution in the proximal femur. The effect of varying the initial bone density, spatial influence function, non-linear order of the adaptive algorithm, and the influence range on the converged solution were investigated. The proposed procedure was shown to converge in a fewer number of iterations and requiring less computational time, while still generating a realistic bone density distribution. It was also shown that varying the identified parameters within reasonable upper and lower bounds had very little impact on the qualitative form of the converged solution. In contrast, the convergence rate was affected to a greater degree by variation of these parameters. In all cases, the solutions obtained are comparable with the actual density in the proximal femur, as measured by Dual-energy X-ray absorptiometry (DEXA) scans.

Background: Advances in the management of Achilles tendon rupture have led to the development of immediate weightbearing protocols. These vary regarding which ankle-foot orthoses (AFOs) are used and the number of inserted heel wedges used within them. Purpose: This study was conducted to evaluate plantar pressure measurements and temporal gait parameters within different AFOs, using different numbers of heel wedges. Study Design: Controlled laboratory study. Methods: Fifteen healthy participants were evaluated using 3 different AFOs, with 4 different levels of inserted heel wedges. Therefore, a total of 12 conditions were evaluated, in a sequence that was randomly allocated to each participant. Pressure and temporal gait parameters were measured using an in-shoe F-Scan pressure system, and range of movement was measured using an electrogoniometer. Results: Ankle-foot orthoses that were restrictive in design, combined with a higher number of inserted heel wedges, reduced forefoot pressures, increased heel pressures, and decreased the amount of time spent in the terminal stance and preswing phase of the gait cycle ( P = .029, .002, and .001). Conclusion: The choice of AFO design and the number of inserted heel wedges have a significant effect on plantar pressure measurements and temporal gait parameters. The implications of these changes need to be applied to the clinical management of acute Achilles tendon ruptures. This clinical management requires a balance between protected weightbearing and functional loading, requiring further research within a clinical context. Clinical Relevance: The biomechanical data from this research imply that a carbon-fiber AFO, with 1 heel raise, protects against excessive dorsiflexion while facilitating the restoration of near-normal gait parameters. This could lead to an accelerated return to function, avoiding the effects of disuse atrophy. This is in contrast to the rigid rocker-bottom AFO design with a greater number of heel-wedge inserts. However, research within a clinical context would be required to ascertain if these biomechanical advantages translate into a functional benefit for patients. The results should also be considered in relation to the amount of force a healing Achilles tendon can withstand.

Objective: To assess the effects of additional gait trainer assisted walking exercises on walking performance in children with hemiparetic cerebral palsy. Design: A randomized controlled study. Setting: Paediatric physical therapy outpatient clinic. Subjects: Thirty spastic hemiparetic cerebral palsied children of both sexes (10–13 years – 19 girls and 11 boys). Methods: Children were randomly assigned into two equal groups; experimental and control groups. Participants in both groups received a traditional physical therapy exercise programme. Those in the experimental group received additional gait trainer based walking exercises which aimed to improve walking performance. Treatment was provided three times per week for three successive months. Main measures: Children received baseline and post-treatment assessments using Biodex Gait Trainer 2 assessment device to evaluate gait parameters including: average step length, walking speed, time on each foot (% of gait cycle) and ambulation index. Results: Children in the experimental group showed a significant improvement as compared with those in the control group. The ambulation index was 75.53±7.36 (11.93 ± 2.89 change score) for the experimental group and 66.06 ± 5.48 (2.13 ± 4.43 change score) for the control group ( t = 3.99 and P = 0.0001). Time of support for the affected side was 42.4 ± 3.37 (7 ± 2.20 change score) for the experimental group and 38.06 ± 4.63 (3.33 ± 6.25 change score) for the control group ( t = 2.92 and P = 0.007). Also, there was a significant improvement in step length and walking speed in both groups. Conclusion: Gait trainer combined with traditional physiotherapy increase the chance of improving gait performance in children with spastic hemiparetic cerebral palsy.

Category: Midfoot/Forefoot Introduction/Purpose: Hallux rigidus (HR) is a degenerative disease of the first metatarsalphalangeal (MTP) joint, and the most common type of foot arthritis. It affects 2.5% of population aged over 50 years. During the gait cycle, the MTP joint normally carries a force of about 119% body weight. We hypothesize that the altered gait mechanics in patients with end stage ankle arthritis would increase the stress on the MTP joint resulting in hallux rigidus. The purpose of the study was to evaluate the prevalence of radiographic hallux rigidus in a population with ankle arthritis, its association with factors such as gender, age, and severity of the disease compared to the normal population. Methods: Patients from a prospectively-collected total ankle database were screened for the inclusion in the present study. All patients with ankle arthritis who underwent a primary total ankle arthroplasty (TAA) between November 2006 and November 2017 with anteroposterior and lateral views on foot x-rays within 3 months pre or postoperative were included. Foot x-rays were reviewed to assess the prevalence of radiographic hallux rigidus and to grade the severity of diagnosis according to Couglin and Shurnas Radiographic Classification. The association among the grades of severity, demographics, and bilateral involvement were evaluated. Results: A group of 870 patients out of 1044 patients who underwent TAA were included in the study. The mean age was 63 years (standard deviation 10.3). The prevalence of HR in the total group was 72.9% with a slightly higher proportion in males compared to females (51.7% versus 48.3%). The distribution among the grades of severity was grade 1, 58%; grade 2, 24%; and grade 3, 18%. Although, we did not find an association between prevalence and gender (P=0.2) or severity (P=0.37); HR grade 2 and grade 3 were higher in females. Bilateral involvement was found in 16.4% of patients with HR. Conclusion: The prevalence of radiographic hallux rigidus in a population with altered gait mechanics was significantly higher compared to that reported in the literature in the normal population. However, no association among demographic factors such as age or gender was found. Women tended to present a more severe diagnosis compared to men but the difference was no statistically significant.

Category: Hindfoot Introduction/Purpose: Posterior Tibial Tendon Dysfunction (PTTD) is common disorder that can lead to changes in function during the gait cycle due to decreased arch, increased hindfoot valgus, and forefoot abduction. These kinematic changes can have a structural impact on the joints throughout the foot. While previous studies have evaluated anatomical three-dimensional (3D) position of the subtalar joint, the purpose of this study was to perform morphological analysis of the anterior, middle and posterior facets in patients with stage II posterior tibial tendon dysfunction compared to normal controls. Methods: Clinical computed tomography images from 10 matched feet (i.e., 10 normal and 10 stage II PTTD) were obtained and used for 3D reconstruction in Mimics software (Materialise). From the3D reconstructions, morphometric evaluations of the subtalar joint were completed including 3D anatomic point placement and measurements of the length and width of the anterior, middle and posterior facets (Fig. 1) by 3 independent evaluators. Evaluators were blinded to experimental groups and to one another’s measurements. A linear mixed-effects model was used to assess the differences between control and PTTD subtalar joints with respect to morphometric measurements (mm). The concordance correlation coefficient (CCC) was used to assess the agreement between the 3 evaluators with respect to their recorded morphometric measurements per location (e.g., anterior, middle, posterior). Results: Although the mean distance of the length and width of the middle facet trended higher in the stage II PTTD compared to controls, this difference was not statistically significant (Table 1). Similarly, there was no difference detected between control and PTTD with respect to morphometric measurements in the anterior and posterior facets (Table 1). The agreement among the 3 evaluators with respect to morphometric measurements was the strongest in the length and width of the middle facets. Conclusion: Stage II posterior tibial tendon dysfunction has been shown to cause increase subtalar joint kinematics, joint contact pressure. Based on the results, there is a positive correlation involving morphologic changes of subtalar joint with the middle facet measurements being larger in the PTTD group. Further studies are needed with weight bearing CT scans in correlation with advance stages of posterior tibial tendon dysfunction.

We determined the effect of claudication pain on temporal and spatial gait characteristics, and on ambulatory symmetry at preferred and rapid self-selected walking paces in patients with unilateral peripheral arterial disease (PAD). Twenty-eight patients with PAD limited by intermittent claudication were studied. Patients ambulated at their preferred and rapid paces over a 7.3-meter portable gait mat system while they were pain-free and after experiencing claudication pain. The order of the pain-free and painful walking trials was randomized, and the following gait parameters were obtained: velocity, cadence, stride length, swing time, stance time, single-support time, and double-support time. During the self-selected rapid pace, patients walked 3% slower ( p = 0.020) while in pain due to a 3% shorter stride length ( p < 0.001), and they were in double-stance longer ( p = 0.024). Claudication pain in the symptomatic leg resulted in an increase in single-stance ( p = 0.007). Furthermore, gait became asymmetrical with pain, as the symptomatic leg spent a higher percentage of the gait cycle in the swing phase ( p < 0.01) and lower percentages in stance ( p < 0.01) and single-stance ( p < 0.01) than the asymptomatic leg. Ambulation was symmetrical for all measures during the pain-free trial. In conclusion, claudication pain slows ambulatory velocity at preferred and rapid paces, and increases asymmetry when ambulatory function is challenged with rapid walking. The reduced ambulatory speed with the development of claudication pain may be an adaptation to elicit a safer and less destabilizing gait pattern.

Background: Using clinical and cadaver studies, we examined the relationship between the location of Morton interdigital neuromas and the surrounding structures, including the deep transverse metatarsal ligament (DTML), which has been suspected as a major causative factor in neuroma formation. Methods: Seventeen fresh-frozen cadavers were evaluated to determine the relationship between the location of Morton interdigital neuromas and the DTML at two phases of the gait cycle with 60 degrees of metatarsophalangeal dorsiflexion and with 15 degrees of ankle dorsiflexion. We measured the distance from the bifurcation of the common digital nerve in the foot to the anterior margin of the DTML and also measured the length of the DTML itself. Clinically, we checked the location of the Morton interdigital neuroma and its length during surgery in 32 feet. Results: In the second and third webspace, the mean distance from the bifurcation of the common digital nerve of the foot to the anterior margin of the DTML was 16.7 mm, 15.1 mm in the mid-stance position, and 15.9 mm and 14.6 mm in the heel-off position. The length of the second and third DTML averaged 12.8 mm and 10.6 mm. Clinically, all of the cases of Morton interdigital neuroma started at the bifurcation area of the common digital nerve, and the mean neuroma length was 7.5 mm (6 to 11). Conclusions: Morton interdigital neuromas were located more distally than the DTML in both the mid-stance and the heel-off stage during walking. The main lesion was located between the metatarsal head and the metatarsophalangeal joint and more distal than the DTML, questioning previous studies suggesting that the DTML is the major causative factor in development of Morton interdigital neuroma.

Introduction. This study evaluated the influence of the degree of treadmill belt inclination for training of ambulatory patients with hemiparetic stroke. Methods. Twelve patients were instructed to walk at 5 different levels of inclination (0%-8%) while harness-secured on the treadmill. The gait velocity was kept constant during all conditions. Dependent variables were heart rate, gait cycle-dependent parameters, and electromyographic activation patterns of the weight-bearing muscles. Results. Heart rate increased across all inclination levels, stride length increased and cadence decreased, whereas swing symmetry improved due to shortening of the relative swing phase of the affected side at the 6% and 8% inclination levels. No change in the activation pattern of the leg muscles was found. Conclusion. An inclination up to at least 8% can be accommodated for treadmill training by ambulatory stroke patients. For a given belt speed, heart rate increased without exceeding critical levels and patients walked with a more symmetric pattern. This protocol appeared to be safe in this selected group of subjects.

BackgroundThe ankle joint requires very precise neuromuscular control during the transition from terminal swing to the early stance phase of the gait cycle. Altered ankle joint arthrokinematics and muscular activity have been cited as potential factors that may lead to an inversion sprain during the aforementioned time periods. However, to date, no study has investigated patterns of muscle activity and 3D joint kinematics simultaneously in a group of subjects with functional instability compared with a noninjured control group during these phases of the gait cycle.PurposeTo compare the patterns of lower limb 3D joint kinematics and electromyographic activity during treadmill walking in a group of subjects with functional instability with those observed in a control group.Study DesignControlled laboratory study.MethodsThree-dimensional angular velocities and displacements of the hip, knee, and ankle joints, as well as surface electromyography of the rectus femoris, peroneus longus, tibialis anterior, and soleus muscles, were recorded simultaneously while subjects walked on a treadmill at a velocity of 4 km/h.ResultsBefore heel strike, subjects with functional instability exhibited a decrease in vertical foot-floor clearance (12.62 vs 22.84 mm; P ConclusionThe altered kinematics observed in this study could explain the reason subjects with functional instability experience repeated episodes of ankle inversion injury in situations with only slight or no external provocation. It is hypothesized that the observed increase in peroneus longus activity may be the result of a change in preprogrammed feed-forward motor control.

The Berkeley Lower Extremity Exoskeleton is the first functional energetically autonomous load carrying human exoskeleton and was demonstrated at U.C. Berkeley, walking at the average speed of 0.9 m/s (2 mph) while carrying a 34 kg (75 lb) payload. The original published controller, called the BLEEX Sensitivity Amplification Controller, was based on positive feedback and was designed to increase the closed loop system sensitivity to its wearer’s forces and torques without any direct measurement from the wearer. This controller was successful at allowing natural and unobstructed load support for the pilot. This article presents an improved control scheme we call “hybrid” BLEEX control that adds robustness to changing BLEEX backpack payload. The walking gait cycle is divided into stance control and swing control phases. Position control is used for the BLEEX stance leg (including the torso and backpack) and a sensitivity amplification controller is used for the swing leg. The controller is also designed to smoothly transition between these two schemes as the pilot walks. With hybrid control, the controller does not require a good model of the BLEEX torso and payload, which is difficult to obtain and subject to change as payload is added and removed. As a tradeoff, the position control used in this method requires the human to wear seven inclinometers to measure human limb and torso angles. These additional sensors require careful design to securely fasten them to the human and increase the time to don and doff BLEEX.