Toward subtalar joint axis-driven computer-aided design and computer-aided manufacturing foot orthoses: Reliability of a noninvasive clinical scanning protocol.

BACKGROUND: The subtalar joint axis (STJA) occupies a key role in the dynamics of the lower limb kinetic chain, and its location has a wide interindividual variability. It has been suggested that considering the STJA location when designing foot orthoses may help to apply the required mechanical dose. However, the evidence is more anecdotal than empirical. OBJECTIVE: This study aimed to evaluate the reliability of the STJA digitization, a procedure combining the clinical determination of the functional STJA location and its subsequent 3-dimensional (3D) scanning. STUDY DESIGN: Two examiners identified the posterior and anterior exit points of the functional STJA on the skin of 15 healthy participants using a clinical method in a repeated-measure design. METHODS: A handheld 3D scanner was used to scan the feet and the skin markers. The 3D coordinates of the skin markers were subsequently quantified and (1) STJA digitization intratester within-session, (2) STJA digitization intratester between-session, and (3) STJA digitization intertester between-session reliabilities were evaluated. RESULTS: When pooling all skin marker 3D coordinates, intraclass correlation coefficients (ICCs) for the STJA intratester within-session reliability ranged from 0.74 to 0.98. ICCs for the STJA digitization intratester between-session reliability ranged from 0.58 to 0.94. ICCs for the STJA digitization intertester reliability ranged from 0.56 to 0.81. Standard error of measurement for the mediolateral position of the talus marker (anterior exit point of the STJA) was substantially higher than that for the other coordinates. CONCLUSIONS: Overall, the STJA digitization demonstrated a good intratester between-session reliability and may be used in a computer-aided design and computer-aided manufacturing workflow to create foot orthoses. However, further efforts should be considered to improve the scanning process and intertester reliability.

Restoration of the native tibial joint line obliquity in total knee arthroplasty with inverse kinematic alignment does not increase knee adduction moments.

PURPOSE: Patient-specific alignment in total knee arthroplasty (TKA) has shown promising patient-reported outcome measures; however, the clinical and biomechanical effects of restoring the native knee anatomy remain debated. The purpose of this study was to compare the gait pattern between a mechanically aligned TKA cohort (adjusted mechanical alignment-aMA) and a patient-specific alignment TKA cohort (inverse kinematic alignment-iKA). METHODS: At two years postoperatively, the aMA and iKA groups, each with 15 patients, were analyzed in a retrospective case-control study. All patients underwent TKA with robotic assistance (Mako, Stryker) through an identical perioperative protocol. The patients' demographics were identical. The control group comprised 15 healthy participants matched for age and gender. Gait analysis was performed with a 3D motion capture system (VICON). Data collection was conducted by a blinded investigator. The primary outcomes were knee flexion during walking, knee adduction moment during walking and spatiotemporal parameters (STPs). The secondary outcomes were the Oxford Knee Score (OKS) and Forgotten Joint Score (FJS). RESULTS: During walking, the maximum knee flexion did not differ between the iKA group (53.0°) and the control group (55.1°), whereas the aMA group showed lower amplitudes of sagittal motion (47.4°). In addition, the native limb alignment in the iKA group was better restored, and although more in varus, the knee adduction moments in the iKA group were not increased (225 N mm/kg) compared to aMA group (276 N mm/kg). No significant differences in STPs were observed between patients receiving iKA and healthy controls. Six of 7 STPs differed significantly between patients receiving aMA and healthy controls. The OKS was significantly better in patients receiving iKA than aMA: 45.4 vs. 40.9; p = 0.05. The FJS was significantly better in patients receiving iKA than aMA: 84.8 vs. 55.5; p = 0.002. CONCLUSION: At two years postoperatively, the gait pattern showed greater resemblance to that in healthy controls in patients receiving iKA rather than aMA. The restoration of the native coronal limb alignment does not lead to increased knee adduction moments due to the restoration of the native tibial joint line obliquity. LEVEL OF EVIDENCE: Level III.

Inverse kinematic alignment accommodates native coronal knee alignment better in comparison to adjusted mechanical alignment and restricted kinematic alignment.

PURPOSE: The purpose was to determine the proportion of native non-arthritic knees that fit within the target zones of adjusted mechanical alignment (aMA), restricted kinematic alignment (rKA), and inverse kinematic alignment (iKA), and to estimate adjustments in native coronal alignment to bring outlier knees within the respective target zones. The hypothesis was that the target zone of iKA, compared to the target zones of aMA and rKA, accommodates a higher proportion of native non-arthritic knees. METHODS: The study used measurements obtained from a computed tomography (CT) scan database (SOMA, Stryker) of 972 healthy knees (Caucasian, 586; Asian, 386). Hip knee ankle (HKA) angle, medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) were used to estimate the proportions of knees within the patient-specific alignment target zones; and to estimate theoretical adjustments of MPTA, LDFA and soft tissue balance (HKA) to bring outlier knees within target zones. Theoretical adjustments to bring outlier knees within the alignment target zones of aMA, rKA and iKA were calculated by subtracting the native coronal alignment angles (MPTAnative, LDFAnative and HKAnative) from angles on the nearest target zone border (MPTAtarget, LDFAtarget and HKAtarget). RESULTS: Patients were aged 59.8 ± 15.8 years with a BMI of 25.0 ± 4.4 kg/m2. The HKA angles were between 168° and 186°, MPTA between 78° and 98° and LDFA between 79° and 93°. Of the 972 knees, 81 (8%) were in the aMA target zone, 530 (55%) were in the rKA target zone, and 721 (74%) were in the iKA target zone. Adjustments of MPTA, LDFA and HKA angle to bring outlier knees within the target zones, were, respectively, 90, 91 and 28% for aMA, 45, 28 and 25% for rKA, and 25, 23 and 7% for iKA. CONCLUSIONS: There is considerable variability in native knee coronal alignment that corresponds to different proportions of the restricted patient-specific alignment target zones for TKA. Although extension of the MPTA and LDFA target zones with rKA accommodate native knee alignment better than aMA, up to 25% would require adjustment of native HKA angle. By also extending the HKA angle target zone into varus, iKA accommodates a greater proportion (93%) of native limb alignment. LEVEL OF EVIDENCE: IV.

ActiveHip+: A feasible mHealth system for the recovery of older adults after hip surgery during the COVID-19 pandemic.

Objective: Half of older adults undergoing hip surgery do not recover their previous functional status. mHealth is a promising tool for rehabilitating older adults after hip surgery. This study aimed to test the feasibility of the ActiveHip+ mHealth system in older adults after hip surgery. Methods: Sixty-nine older adults who had undergone hip surgery and their family caregivers were recruited from hospitals in Spain and Belgium and used the ActiveHip+ mHealth system for 12 weeks. Assessments were made during hospital stay and 3 months after surgery. Feasibility assessment included: adoption (participation proportion), usage (access to the app), satisfaction with the app (Net Promoter Score) and user perception of the quality of the app (Mobile App Rating Scale). Clinical assessment included: patient-reported outcomes, such as functional status (Functional Independence Measure) and performance-based outcomes, such as physical fitness (Short Physical Performance Battery). Results: The ActiveHip+ mHealth system obtained satisfactory feasibility results in both countries. In Spain, we observed 85% adoption, 64% usage, 8.86/10 in satisfaction with the app and 4.42/5 in perceived quality of the app. In Belgium, we observed 82% adoption, 84% usage, 5.16/10 in satisfaction with the app and 3.52/5 in app's perceived quality. The intervention had positive effects on levels of functional status, pain and physical fitness. Conclusions: The ActiveHip+ mHealth system is a feasible tool to conduct the rehabilitation in older adults after hip surgery. Although the intervention seemed beneficial clinically, we do not recommend its implementation in clinical settings until appropriately designed randomised clinical trials confirm these results.

Total hip arthroplasty with a superior approach and in situ preparation of the femoral stem: technique and feasibility in a prospective series of 80 cases.

We report on the feasibility of a technique for total hip replacement with in situ preparation of the femoral stem through a superior approach and with the use of standard instruments. From December 2017 to august 2018, 100 patients were recruited for total hip replacement. 80 patients underwent THA through a superior approach with femoral broaching before femoral neck cut. We evaluated feasibility, complications and early functional outcome. There were no major complications. Postoperative leg length discrepancy was on average +0.6mm and offset -0.5mm. The mean acetabular cup inclination was 42.0° and the mean anteversion was 14.5°. The mean WOMAC score was 46 before, 76 at 1 month and 86 at 3 months after surgery. Functional scores (OARSI) were significantly improved at 3 months. Superior in situ total hip replacement is a reliable and reproducible technique with an excellent clinical outcome. It is an iteration to the posterior approach, hence the learning curve is steep and if needed, conversion to a standard posterior approach is possible.

Inverse Kinematic Alignment for Total Knee Arthroplasty.

Patient specific alignment might improve clinical outcomes in total knee arthroplasty (TKA). Different alignment concepts are described, each providing specific features with theoretical benefits or possible disadvantages. Inverse kinematic alignment (iKA) is a new patient specific alignment concept with excellent reported clinical outcome and patient satisfaction at short-term follow-up. iKA is a tibia-first, gap balancing technique restoring the native tibial joint line obliquity (JLO). In each patient, within boundaries, equal medial and lateral tibial resections are performed, compensating for cartilage and bone loss. We describe the surgical technique of iKA using a robotic assisted system (Mako, Stryker, Kalamazoo, USA). A case series of 100 consecutive iKA cases is assessed and the bony resections and resection angles are reported. Both in the coronal plane and axial plane, iKA might offer advantages over existing alignment strategies, possibly providing optimal clinical outcome and durable long-term survival, regardless of the alignment is varus, neutral or valgus.

Trunk control, motion and alignment after total knee arthroplasty: a systematic review and meta-analysis.

BACKGROUND: Trunk control improves mobility, balance and quality of life early after total knee arthroplasty (TKA) and is therefore considered an important parameter during the recovery process. However, little is known about trunk control, motion and alignment after TKA. Increasing our understanding aids in optimizing treatment strategies to enhance functional mobility after TKA. RESEARCH QUESTION: Does trunk control, motion and alignment return to normal after TKA and is this related to functional mobility? METHODS: Five scientific databases were searched until July 2021. Eligibility criteria consisted of outcomes assessing trunk control and alignment in a population of adults undergoing TKA. Two reviewers independently screened studies and risk of bias was assessed by Mixed Methods Appraisal Tool (MMAT). Meta-analysis was performed for subgroups gait and alignment. RESULTS: Of the 362 studies retrieved, 24 were included. Study designs were cohorts with mixed methods (pre-post treatment, case-control and case-case) and three randomized controlled trials. The mean MMAT score was 75%, corresponding to low bias. In total 1178 patients and 197 controls were included. Results showed that pre-operative trunk motion was characterized by increased amplitudes in all three planes and altered alignment which did not all return to normal after TKA. Frontal plane motion and alignment recovered faster than the sagittal and transversal plane. Although pelvic tilt improved after surgery, sagittal imbalance (anteriorly shifted trunk position) was still present. SIGNIFICANCE: Recovery of trunk motion after TKA is time-, speed- and technique-dependent. The observed differences in trunk motion with the healthy controls persisted after TKA. This indicates that incorporating a full biomechanical chain approach, including trunk motion and gait-retraining exercises with a strong focus on postural alignment could improve functional mobility after TKA. Limited studies are available assessing trunk control and trunk motion during functional tasks besides walking which warrant further investigation.

A Detailed Comparison of Preoperative Complaints in Severe Carpal Tunnel Syndrome versus Recurrent Carpal Tunnel Syndrome Using the Boston Carpal Tunnel Questionnaire.

Background: The Boston Carpal Tunnel Questionnaire (BCTQ) has a symptom severity scale (SSS) with 11 questions and a functional status scale (FSS) with 8 questions. The final score for each scale is the sum divided by the number of questions and ranges between 1 and 5. A score of 1 indicates they have no complaints and 5 indicates high severity and functional loss. Unfortunately, this single digit score does not permit a detailed analysis of the symptoms and functional status. The aim of this study is to conduct an in-depth comparison of preoperative complaints using the BCTQ between patients with severe carpal tunnel syndrome (SCTS) and recurrent carpal tunnel syndrome (RCTS). Methods: This is a retrospective cohort study on the preoperative status of 37 patients with SCTS and 18 patients with RCTS using the BCTQ. The questions in the SSS and FSS were classified into four groups based on the responses of patients, namely a low complaint (LC) (1-1.99), moderate complaint (MC) (2-2.99), high complaint (HC) (3-3.99), and severe complaint (SC) (4-5) groups. The patients in the SCTS and RCTS groups were compared to find differences in age, gender, hand dominance, and responses to questions in the SSS and FSS. Results: The age of patients in the SCTS group (76.06 years) was significantly higher compared to the RCTS group (51.11 years). There was no significant difference between the two groups with regard to gender or hand dominance. The top question with SC or HC response in the SCTS group was problems in grasping small objects (SSS) and fastening buttons (FSS) and in the RCTS group was tingling in the hand (SSS) and difficulty with opening a jar (FSS). Conclusions: An in-depth analysis of the BCTQ allowed us to compare and understand differences in symptoms and function between patients with SCTS and RCTS. Level of Evidence: Level III (Therapeutic).

Higher satisfaction after total knee arthroplasty using restricted inverse kinematic alignment compared to adjusted mechanical alignment.

PURPOSE: Various alignment philosophies for total knee arthroplasty (TKA) have been described, all striving to achieve excellent long-term implant survival and good functional outcomes. In recent years, in search of higher functionality and patient satisfaction, a shift towards more tailored and patient-specific alignment is seen. The purpose of this study was to describe a restricted 'inverse kinematic alignment' (iKA) technique, and to compare clinical outcomes of patients that underwent robotic-assisted TKA performed by restricted iKA vs. adjusted mechanical alignment (aMA). METHODS: The authors reviewed the records of a consecutive series of patients that received robotic-assisted TKA with restricted iKA (n = 40) and with aMA (n = 40). Oxford Knee Score (OKS) and satisfaction on a visual analogue scale (VAS) were collected at a follow-up of 12 months. Clinical outcomes were assessed according to patient acceptable symptom state (PASS) thresholds, and uni- and multivariable linear regression analyses were performed to determine associations of OKS and satisfaction with six variables (age, sex, body mass index (BMI), preoperative hip-knee-ankle (HKA) angle, preoperative OKS, alignment technique). RESULTS: The restricted iKA and aMA techniques yielded comparable outcome scores (p = 0.069), with OKS, respectively, 44.6 ± 3.5 and 42.2 ± 6.3. VAS Satisfaction was better (p = 0.012) with restricted iKA (9.2 ± 0.8) compared to aMA (8.5 ± 1.3). The number of patients that achieved OKS and satisfaction PASS thresholds was significantly higher (p = 0.049 and p = 0.003, respectively) using restricted iKA (98% and 80%) compared to aMA (85% and 48%). Knees with preoperative varus deformity, achieved significantly (p = 0.025) better OKS using restricted iKA (45.4 ± 2.0) compared to aMA (41.4 ± 6.8). Multivariable analyses confirmed better OKS (ß = 3.1; p = 0.007) and satisfaction (ß = 0.73; p = 0.005) with restricted iKA. CONCLUSIONS: The results of this study suggest that restricted iKA and aMA grant comparable clinical outcomes at 12-month follow-up, though a greater proportion of knees operated by restricted iKA achieved the PASS thresholds for OKS and satisfaction. Notably. in knees with preoperative varus deformity, restricted iKA yielded significantly better OKS and satisfaction than aMA. LEVEL OF EVIDENCE: Level III, comparative study.

In-vitro validation of inertial-sensor-to-bone alignment.

A major shortcoming in kinematic estimation using skin-attached inertial sensors is the alignment of sensor-embedded and segment-embedded coordinate systems. Only a correct alignment results in clinically relevant kinematics. Model-based inertial-sensor-to-bone alignment methods relate inertial sensor measurements with a model of the joint. Therefore, they do not rely on properly executed calibration movements or a correct sensor placement. However, it is unknown how accurate such model-based methods align the sensor axes and the underlying segment-embedded axes, as defined by clinical definitions. Also, validation of the alignment models is challenging, since an optical motion capture ground truth can be prone to disturbances from soft tissue movement, orientation estimation and manual palpation errors. We present an anatomical tibiofemoral ground truth on an unloaded cadaveric measurement set-up that intrinsically overcomes these disturbances. Additionally, we validate existing model-based alignment strategies. Modeling the degrees of freedom leads to the identification of rotation axes. However, there is no reason why these axes would align with the segment-embedded axes. Relative inertial-sensor orientation information and rich arbitrary movements showed to aid in identifying the underlying joint axes. The first dominant sagittal rotation axis aligned sufficiently well with the underlying segment-embedded reference. The estimated axes that relate to secondary kinematics tend to deviate from the underlying segment-embedded axes as much as their expected range of motion around the axes. In order to interpret the secondary kinematics, the alignment model should more closely match the biomechanics of the joint.

Reference in-vitro dataset for inertial-sensor-to-bone alignment applied to the tibiofemoral joint.

Skin-attached inertial sensors are increasingly used for kinematic analysis. However, their ability to measure outside-lab can only be exploited after correctly aligning the sensor axes with the underlying anatomical axes. Emerging model-based inertial-sensor-to-bone alignment methods relate inertial measurements with a model of the joint to overcome calibration movements and sensor placement assumptions. It is unclear how good such alignment methods can identify the anatomical axes. Any misalignment results in kinematic cross-talk errors, which makes model validation and the interpretation of the resulting kinematics measurements challenging. This study provides an anatomically correct ground-truth reference dataset from dynamic motions on a cadaver. In contrast with existing references, this enables a true model evaluation that overcomes influences from soft-tissue artifacts, orientation and manual palpation errors. This dataset comprises extensive dynamic movements that are recorded with multimodal measurements including trajectories of optical and virtual (via computed tomography) anatomical markers, reference kinematics, inertial measurements, transformation matrices and visualization tools. The dataset can be used either as a ground-truth reference or to advance research in inertial-sensor-to-bone-alignment.

Effect of knee arthroplasty on sports participation and activity levels: a systematic review and meta-analysis.

OBJECTIVE: Desires and expectations of patients in regard to resume participation in sport activities after knee arthroplasty strongly increased in recent years. Therefore, this review systematically reviewed the available scientific literature on the effect of knee arthroplasty on sports participation and activity levels. DESIGN: Systematic review and meta-analysis. DATA SOURCES: PubMed, Embase, SPORTDiscus and reference lists were searched in February 2019. STUDIES ELIGIBILITY CRITERIA: Inclusion of knee osteoarthritis patients who underwent total knee arthroplasty (TKA) and/or unicondylar knee arthroplasty. Studies had to include at least one preoperative and one postoperative measure (≥1 year post surgery) of an outcome variable of interest (ie, activity level: University of California, Los Angeles and/or Lower Extremity Activity Scale; sport participation: type of sport activity survey). RESULTS: Nineteen studies were included, consisting data from 4074 patients. Knee arthroplasty has in general a positive effect on activity level and sport participation. Most patients who have stopped participating in sport activities in the year prior to surgery, however, do not seem to reinitiate their sport activities after surgery, in particular after a TKA. In contrast, patients who continue to participate in sport activities until surgery appear to become even more active in low-impact and medium-impact sports than before the onset of restricting symptoms. CONCLUSIONS: Knee arthroplasty is an effective treatment in resuming sports participation and physical activity levels. However, to achieve the full benefits from knee arthroplasty, strategies and guidelines aimed to keep patients capable and motivated to participate in (low-impact or medium-impact) sport activities until close before surgery are warranted.

High Levels of Kinesiophobia at Discharge from the Hospital May Negatively Affect the Short-Term Functional Outcome of Patients Who Have Undergone Knee Replacement Surgery.

BACKGROUND: Kinesiophobia is a psycho-cognitive factor that hampers recovery after orthopedic surgery. No evidence exists on the influence of kinesiophobia on the short-term recovery of function in patients with knee replacement (KR). Therefore, the aim of the present study is to investigate the impact of kinesiophobia on short-term patient-reported outcomes (PROMs) and performance-based measures (PBMs). METHODS: Forty-three KR patients filled in the Tampa scale for kinesiophobia (TSK) at time of discharge. Patients with TSK ≥ 37 were allocated to the kinesiophobia group (n = 24), others to the no-kinesiophobia group (n = 19). Patients were asked to complete PROMs and to execute PBMs at discharge and at 6-weeks follow-up. An independent samples t-test was used to compare group differences for PROMs and PBMs at both measurement sessions. Multiple linear regression analysis models were used to model PBM outcomes from age, pain and TSK scores. RESULTS: Significant differences were observed between groups for PROMs and PBMs. Kinesiophobia significantly contributed to the reduced functional outcomes. CONCLUSION: At discharge from the hospital, 55.8% of KR patients demonstrated high levels of kinesiophobia (TSK ≥ 37). This may negatively influence short-term recovery of these patients, by putting them at higher risk for falling and reduced functionality.

A Novel Method to Estimate the Full Knee Joint Kinematics Using Low Cost IMU Sensors for Easy to Implement Low Cost Diagnostics.

Traditional motion capture systems are the current standard in the assessment of knee joint kinematics. These systems are, however, very costly, complex to handle, and, in some conditions, fail to estimate the varus/valgus and internal/external rotation accurately due to the camera setup. This paper presents a novel and comprehensive method to infer the full relative motion of the knee joint, including the flexion/extension, varus/valgus, and internal/external rotation, using only low cost inertial measurement units (IMU) connected to the upper and lower leg. Furthermore, sensors can be placed arbitrarily and only require a short calibration, making it an easy-to-use and portable clinical analysis tool. The presented method yields both adequate results and displays the uncertainty band on those results to the user. The proposed method is based on an fixed interval smoother relying on a simple dynamic model of the legs and judicially chosen constraints to estimate the rigid body motion of the leg segments in a world reference frame. In this pilot study, benchmarking of the method on a calibrated robotic manipulator, serving as leg analogue, and comparison with camera-based techniques confirm the method's accurateness as an easy-to-implement, low-cost clinical tool.

Inertial Sensor-Based Lower Limb Joint Kinematics: A Methodological Systematic Review.

The use of inertial measurement units (IMUs) has gained popularity for the estimation of lower limb kinematics. However, implementations in clinical practice are still lacking. The aim of this review is twofold-to evaluate the methodological requirements for IMU-based joint kinematic estimation to be applicable in a clinical setting, and to suggest future research directions. Studies within the PubMed, Web Of Science and EMBASE databases were screened for eligibility, based on the following inclusion criteria: (1) studies must include a methodological description of how kinematic variables were obtained for the lower limb, (2) kinematic data must have been acquired by means of IMUs, (3) studies must have validated the implemented method against a golden standard reference system. Information on study characteristics, signal processing characteristics and study results was assessed and discussed. This review shows that methods for lower limb joint kinematics are inherently application dependent. Sensor restrictions are generally compensated with biomechanically inspired assumptions and prior information. Awareness of the possible adaptations in the IMU-based kinematic estimates by incorporating such prior information and assumptions is necessary, before drawing clinical decisions. Future research should focus on alternative validation methods, subject-specific IMU-based biomechanical joint models and disturbed movement patterns in real-world settings.

Lower extremity gait kinematics outcomes after knee replacement demonstrate arthroplasty-specific differences between unicondylar and total knee arthroplasty: A pilot study.

BACKGROUND: The aim of the present study is to compare sagittal gait kinematics of ankle, knee and hip joints between subjects with unicondylar and total knee arthroplasty and age matched healthy controls. Since unicondylar knee replacement is a less invasive procedure, which more closely preserves knee joint anatomy, we hypothesized that one year post unicondylar knee arthroplasty patients would demonstrate more normal gait patterns than patients with total knee arthroplasty. RESEARCH QUESTION: Do unicondylar and total knee arthroplasty patients display similar gait kinematics one year after surgery? METHODS: Fourteen subjects (8 posterior stabilized and 6 medial unicondylar knee replacements) that were one year post surgery, and 6 healthy control subjects underwent a 3D gait analysis and a physical examination (range of motion, muscle strength). Statistical parametric mapping was used to compare gait kinematics of the lower limbs between groups. Additionally, differences in peak angles and clinical outcomes were assessed using a one-way ANOVA between subjects analysis. RESULTS: Both knee replacement groups showed reduced knee flexion range of motion and reduced muscle strength at the operated leg compared to the control group. Subjects with TKA demonstrated reduced knee flexion at loading response and midstance of the gait cycle. Both UKA and TKA demonstrated significantly less knee flexion during swing. SIGNIFICANCE: The results of this study demonstrate arthroplasty-specific differences in muscle strength, range of motion and gait kinematics of the lower limb one year after knee surgery. Future planning of post-surgery follow-up should addresses these arthroplasty-specific weaknesses and gait deviations.

Hip and knee kinematics of the forward lunge one year after unicondylar and total knee arthroplasty.

Patients with unicondylar knee arthroplasty (UKA) report higher functionality compared to those with total knee arthroplasty (TKA). However, these patients should also be assessed during more demanding tasks in order to appreciate their true functionality. The forward lunge (FL) is a motor task commonly used in clinics to evaluate functional recovery after knee replacement surgery. Unfortunately, clear evidence comparing FL kinematics between patients with UKA and TKA is still missing. The purpose of this study was to compare hip and knee joint kinematics during the FL between patients with UKA, TKA and controls. Twenty subjects (8 TKA, 6 UKA, 6 controls) underwent 3D motion analysis during a FL. Differences in hip and knee kinematics between groups were identified using statistical parametric mapping. We concluded that patients with TKA demonstrated reduced knee and hip flexion angles during the loaded phase of the FL, which could have been an attempt to unload the knee joint. This is in contrast to patients with UKA, who showed similar knee and hip joint kinematics compared to controls throughout the entire FL. It seems that retaining the cruciate ligaments is beneficial for the execution of a complex motor task such as the FL.

Estimation and validation of temporal gait features using a markerless 2D video system.

BACKGROUND AND OBJECTIVE: Estimation of temporal gait features, such as stance time, swing time and gait cycle time, can be used for clinical evaluations of various patient groups having gait pathologies, such as Parkinson's diseases, neuropathy, hemiplegia and diplegia. Most clinical laboratories employ an optoelectronic motion capture system to acquire such features. However, the operation of these systems requires specially trained operators, a controlled environment and attaching reflective markers to the patient's body. To allow the estimation of the same features in a daily life setting, this paper presents a novel vision based system whose operation does not require the presence of skilled technicians or markers and uses a single 2D camera. METHOD: The proposed system takes as input a 2D video, computes the silhouettes of the walking person, and then estimates key biomedical gait indicators, such as the initial foot contact with the ground and the toe off instants, from which several other temporal gait features can be derived. RESULTS: The proposed system is tested on two datasets: (i) a public gait dataset made available by CASIA, which contains 20 users, with 4 sequences per user; and (ii) a dataset acquired simultaneously by a marker-based optoelectronic motion capture system and a simple 2D video camera, containing 10 users, with 5 sequences per user. For the CASIA gait dataset A the relevant temporal biomedical gait indicators were manually annotated, and the proposed automated video analysis system achieved an accuracy of 99% on their identification. It was able to obtain accurate estimations even on segmented silhouettes where, the state-of-the-art markerless 2D video based systems fail. For the second database, the temporal features obtained by the proposed system achieved an average intra-class correlation coefficient of 0.86, when compared to the ``gold standard" optoelectronic motion capture system. CONCLUSIONS: The proposed markerless 2D video based system can be used to evaluate patients' gait without requiring the usage of complex laboratory settings and without the need for physical attachment of sensors/markers to the patients. The good accuracy of the results obtained suggests that the proposed system can be used as an alternative to the optoelectronic motion capture system in non-laboratory environments, which can be enable more regular clinical evaluations.

The implementation of inertial sensors for the assessment of temporal parameters of gait in the knee arthroplasty population.

BACKGROUND: The use of inertial measurement units for the evaluation of temporal parameters of gait has been studied in many populations. However, currently no studies support the use of inertial measurement units for this purpose in the knee arthroplasty population. The objective of the present study was to investigate the agreement between an inertial measurement and camera based system for the assessment of temporal gait parameters in a knee arthroplasty population. METHODS: Sixteen knee arthroplasty patients performed 3 gait trials at a self-selected speed along a 6 m walk-way. During the gait trials, gyroscope data from shank-worn inertial measurement units and motion data from optoelectronic cameras were collected simultaneously. A custom-made peak detection algorithm was used to identify gait events from gyroscope data, in order to compute cycle time, stance time and swing time. A marker and coordinate based algorithm was used to calculate temporal gait parameters from kinematical data derived from the camera system. Temporal variables were compared between both methods by calculating intra-class correlation coefficients, mean errors and root mean squared errors. Furthermore, Bland-Altman plots were constructed to assess the agreement between both methods. FINDINGS: Overall good to excellent intra-class correlation values (0.826-0.972) were found. Root mean square errors between both methods ranged from 0.036 to 0.055 s. High levels of agreement were observed for all variables. INTERPRETATION: These findings suggest that inertial measurement units can be used for outside laboratory assessment (e.g. in a hospital environment) of temporal gait parameters in the knee arthroplasty population.

Sagittal evaluation of usual standing and sitting spinal posture.

Postural rehabilitation often plays an important role in the management of non-specific low back pain. While cervical and lumbar correlations have been demonstrated previously, the different role of the pelvis and the thoracic spine for postural control in sitting and standing remains unclear. The aim of this study was to investigate postural correlations between all spinal regions in standing and sitting. Based on digital photographs eight postural angles were analyzed in 99 young healthy persons. Pearson correlations between different postural angles were calculated. In sitting pelvic tilt demonstrated mostly medium correlations with five out of seven other postural angles, compared to three in standing. In standing trunk angle showed five out of seven mostly medium correlations with other regions compared to four out of seven in usual sitting. The low and different correlations suggest a large between-subject variability in sagittal spinal posture, without the existence of any optimal sagittal posture.