Slipped Capital Femoral Epiphysis (SCFE) is one of the most common hip disorders in children and is characterized by a proximal femoral deformity, resulting in early osteoarthritis. Several studies have suggested that SCFE patients after in situ fixation show an altered gait pattern. Early identification of gait alterations might lead to earlier intervention programs to prevent osteoarthritis. The aim of this study is to analyse gait alterations in SCFE patients after in situ fixation compared to typically developed children, using the Computer Assisted Rehabilitation Environment (CAREN) system. This is a cross-sectional, multi-center case-control study in the Netherlands. Eight SCFE patients and eight age- and sex-matched typically developed were included from two hospitals. Primary outcomes were kinematic parameters (absolute joint angles), studied with gait analysis using statistical parametric mapping (SPM). Secondary outcomes were spatiotemporal parameters, the Notzli alpha angle, muscle activation patterns (EMG), and clinical questionnaires (VAS, Borg CR10, SF-36, and HOOS), analyzed using non-parametric statistical methods.Introduction and Objective
Materials and Methods
The goal of total hip arthroplasty (THA) is to reduce pain, restore function but also activity levels for general health benefits or social participation. Thus evaluating THA patient activity can be important for diagnosis, indication, outcome assessment or biofeedback. Physical activity (PA) of n=100 primary THA patients (age at surgery 63 ±8yrs; 49M/51F; 170 ±8cm, 79.8 ±14.0kg) was measured at 8 ±3yrs follow-up. A small 3D accelerometer was worn for 4 successive days during waking hours at the non-affected lateral upper leg. Data was analysed using validated algorithms (Matlab) producing quantitative (e.g. #steps, #transfers, #walking bouts) and qualitative (e.g. cadence, temporal distribution of events) activity parameters. An age matched healthy control group (n=40, 69 ±8yrs, 22M/18F) served as reference.Background
Methods
In total knee arthroplasty (TKA), patient reported outcome on pain, function or satisfaction fails to differentiate treatment options. Activity, a consequence of pain-free, well functioning TKA and a satisfied patient, may be a discriminative surrogate metric, especially when objectively measured. Habitual activity was measured in TKA patients (n=32, F/M=20/12, age: 72 ±8yrs) at long-term follow-up (9 ±1yrs) and compared to healthy, age matched controls (n=32, F/M=20/12, age: 71 ±9yrs) using a popular questionnaire (SQUASH) and accelerometry. A small 3D accelerometer (X16-mini, GCD Dataconcepts) was worn for 4 successive days during waking hours at the non-affected lateral upper leg. Data was analysed using validated algorithms (Matlab) counting and timing walking bouts, steps, sitting periods and transfers. Stair climbing events or similar activities such as walking steep slopes were classified using the higher mean hip flexion angle as a feature.Background
Methods
Metal-on-metal hip implants can produce adverse tissue reactions to wear debris. Increased metal ion concentrations in the blood are measured as a proxy to wear and the complications it can trigger. Many studies have examined various factors influencing the metal ion concentrations. This is the first study to investigate the effect of physical activity level, as objectively measured in daily life, on blood ion levels, expecting higher concentrations for higher patient activity. Thirty-three patients (13F/20M, 55.8 ± 6.2 years at surgery) with a unilateral resurfacing hip prosthesis were included. At last follow-up (6.8 ± 1.5 years) cobalt and chromium concentrations in the blood were determined by inductively coupled plasma mass spectrometry. Physical activity was measured during 4 successive days using a 3D-acceleration-based activity monitor. Data was analysed using validated algorithms, producing quantitative and qualitative parameters. Acetabular cup position was measured radiographically. Correlations were tested with Pearson's r'.Background
Methods
The second generation metal-on-metal (MoM) prosthesis of the hip became a worldwide success in the 90s. However, after the placement of a MoM prosthesis the cobalt ion concentrations raise significantly. This may lead to systemic complaints and even cobalt toxicity. Sixty-one patients (26F/35M) with both an unilateral and bilateral resurfacing or large-head MoM (LHMoM) hip prosthesis were included. At last follow-up (5.77 ± 1.57 yrs) cobalt concentrations in the blood were determined by ICP-MS. Based on the known cobalt toxicity symptoms we developed a non-validated questionnaire. Analysis was done on two groups; a low cobalt concentration group and a high cobalt concentration group. We used 170 nmol/L as the upper limit of well functioning prosthesis as defined by the Dutch Orthopaedic Society (NOV). Independent samples T test and Pearson correlation coefficient were done.Background
Methods
The goal of total hip arthroplasty (THA) is to reduce pain, restore function but also activity levels for general health benefits or social participation. Thus evaluating THA patient activity can be important for diagnosis, indication, outcome assessment or biofeedback. Physical activity (PA) of n=100 primary THA patients (age at surgery 63 ±8yrs; 49M/51F; 170 ±8cm, 79.8 ±14.0kg) was measured at 8 ±3yrs follow-up. A small 3D accelerometer was worn for 4 successive days during waking hours at the non-affected lateral upper leg. Data was analyzed using validated algorithms (Matlab) producing quantitative (e.g. #steps, #transfers, #walking bouts) and qualitative (e.g. cadence, temporal distribution of events) activity parameters. An age matched healthy control group (n=40, 69 ±8yrs, 22M/18F) served as reference.Introduction
Methods
Physical activity monitoring using a single accelerometer works reliably in clinical practice and is of added value as clinical outcome tool, as it provides objective and more precise information about a patient's activity compared to currently used questionnaires. Standard clinical outcome tools do not comply with the new generation of patients who are younger and more active. To capture the high functional demands of these patients, current outcome scales have been optimised (e.g. New-Knee Society Score: New-KSS), new outcome scales have been developed (e.g. Knee disability and Osteoarthritis Outcome score: KOOS). Also objective measurement tools (e.g. activity monitors) have become increasingly popular. This study evaluates the pre- and postoperative TKA status of patients using such optimised and new outcome tools.Summary
Introduction
Upper extremity activity was similar in patients and healthy subjects, showing no significant asymmetry between arms within subjects. Further improvements (e.g. thresholds, filters, inclinometer function) are needed to show the clinical value of AM for patients suffering shoulder complaints. Activity monitoring is becoming a popular outcome tool especially in orthopaedics. The suitability of a single 3D acceleration-based activity monitor (AM) for patients with lower-extremity problems has been shown. However less is known about its feasibility to monitor upper-extremity activity. Insight into the amount and intensity of upper-extremity activity of the affected and non-affected arm (asymmetry) may be of added value for diagnostics, therapy choice and evaluating treatment effects. This study investigates the feasibility of a single AM to evaluate (asymmetry in) upper-extremity activity in daily life.Summary
Introduction
The ankle X-ray has moderate diagnostic power to identify syndesmotic instability, showing large sensitivity ranges between observers. Classification systems and radiographic measurements showed moderate to high interobserver agreement, with extended classifications performing worse. There is no consensus regarding the diagnosis and treatment of ankle fractures with respect to syndesmotic injury. The diagnosis of syndesmotic injury is currently based on intraoperative findings. Surgical indication is mainly made by ankle X-ray assessment, by several classification systems and radiographic measurements. Misdiagnosis of the injury results in suboptimal treatment, which may lead to chronic complaints, like instability and osteoarthritis. This study investigates the diagnostic power and interobserver agreement of three classification methods and radiographic measures, currently used to assess X-ankles and to identify syndesmotic injury.Summary
Introduction
Movement analysis (IMA) and activity monitoring (AM) using a body-fixed inertia-sensor can discriminate patients with ankle injuries from controls and between patients of different pathology or post-injury time. Weak correlations with PROMs show its added value in objectifying outcome assessment. Ankle injuries often result in residual complaints calling for objective methods to score outcome alongside subjective patient-reported outcome measures (PROMs). Inertial motion analysis (IMA) and activity monitoring (AM) using a body-fixed sensor have shown clinical validity in patients suffering knee, hip and spine complaints. This study investigates the feasibility of IMA and AM 1) to differentiate patients suffering ankle injuries from healthy controls, 2) to compare different ankle injuries, 3) to monitor ankle patients during recovery.Summary
Introduction
A single 3D accelerometer is accurate in measuring upper-extremity activity durations, rest periods and intensities, suggesting its feasibility for daily life measurements with patients. Further enhancements are feasible to reduce residual false classifications of intensity from certain activities. Physical activity is an important outcome measure in orthopaedics as it reflects how surgically restored functional capacity is used in daily life. Accelerometer-based activity monitors (AM) are objective, reliable and valid to determine lower extremity activity in orthopaedic patients. However the suitability of a single AM to monitor upper-extremity activity, in terms of quantity and intensity, has not been investigated. This study investigates the suitability and validity of a single AM to measure quantity and intensity of upper-extremity activity.Summary
Introduction
In orthopaedics, clinical outcome assessment (COA) is still mostly performed by questionnaires which suffer from subjectivity, a ceiling effect and pain dominance. Real life activity monitoring (AM) holds the promise to become the new standard in COA with small light weight and easy to use accelerometers. More and more activities can be identified by algorithms based on accelerometry. The identification of stair climbing for instance is important to assess the participation of patients in normal life after an orthopaedic procedure. In this study we validated a custom made algorithm to distinguish normal gait, ascending and descending stairs on a step by step basis. A small, lightweight 3D-accelerometer taped to the lateral side of the affected (patients) or non-dominant (healthy subjects) upper leg served as the activity monitor. 13 Subjects (9 patients, 4 healthy) walked a few steps before descending a flight stairs (20 steps with a 180o turn in the middle), walked some steps more, turned around and ascended the same stairs. Templates (up, down and level) were obtained by averaging and stretching the vertical acceleration in the 4 healthy subjects. Classification parameters (low pass (0.4 Hz) horizontal (front-back) acceleration and the Euclidian distance between the vertical acceleration and each template) were obtained for each step. Accuracy is given by the percentage of correctly classified steps.Introduction
Methods
Patient satisfaction becomes an important aspect in clinical practice causing a shift from clinician-administered scales (CAS) towards patient-administered measurement outcomes (PROMs). Besides, clinical outcome can objectively be evaluated using inertia-based motion analysis (IMA). This study evaluates different outcome measures by investigating the 1) effect of replacing CAS by PROMS on outcome assessment, 2) redundancy between scales, 3) additional value of IMA in outcome scoring. This cross-sectional study included 27 primary unilateral total knee arthroplasty patients (m/f=12/19; age=66.2 yrs), 6 weeks (n=12) and 6 months (n=15) postoperative, who covered a wide range of the scores. One CAS (Knee Society Score (KSS; knee and function subscore), two PROMs (Knee Injury and Osteoarthritis Outcome Score Physical Shortform (KOOS-PS), Visual Analogue Scale satisfaction (VAS)) and a functional test (IMA block step test) were completed. For IMA, patients stepped up and down a 20cm block starting with the affected and followed by the non-affected leg, while wearing an inertia-sensor (3D accelero- and gyrometer) at the lower back (fig. 1). IMA-parameters like performance time (s), bending angle (°), pelvic-obliquity angle (°), were calculated using self-designed algorithms. Differences between legs were determined by ratios (affected/non-affected leg). Pearson's correlations were done, considering r<0.4 poor, 0.4<r<0.7 moderate, r>0.7 strong.Introduction
Methods
In orthopaedics, clinical outcome assessment (COA) is mostly performed by questionnaires which suffer from subjectivity, a ceiling effect and pain dominance. Real life activity monitoring (AM) can objectively assess function and becomes now feasible as technology has become smaller, lighter, cheaper and easier to use. In this study we validated a custom made algorithm based on accelerometry using different orthopaedic patients with the aim to use AM in orthopaedic COA. A small, lightweight 3D-accelerometer taped to the lateral side of the affected upper leg served as the activity monitor. AM algorithms were programmed in Matlab to classify standing, sitting, and walking. For validation a common protocol was used; subjects were asked to perform several tasks for 5 or 10 seconds in a fixed order. An observer noted the starting time of each task using a stopwatch. Accuracy was calculated for the number of bouts per activity as well as total time per activity. 10 Subjects were chosen with different pathologies (e.g. post total knee/hip arthroplasty, osteoarthritis) since the difference in movement dynamics in each pathology poses a challenge to the algorithm.Introduction
Methods
Modern orthopaedics increasingly demands objective functional outcome assessment beyond classic scores and tests suffering from subjectivity, pain dominance and ceiling effects. Inertia based motion analysis (IMA) is a simple method and validated for gait in knee arthroplasty patients. This study investigates whether IMA assessed stair climbing can distinguish between healthy and pathological subjects and is able to diagnose a meniscal tear (MT). Following standard physical examination (McMurray, rotation pain), 37 patients (18–72yrs) received arthroscopy suspecting a meniscal tear resulting from trauma, degeneration or both. Arthroscopy identified the presence or absence of MT and the osteoarthritis level (Outerbridge). Prior to arthroscopy, the ascending and descending five stairs twice at preferred speed and without the use of handrails was measured using a triaxial accelerometer (62×41×18mm; m=53g; f=100Hz) taped to the sacrum. Based on peak detection algorithms, temporal motion parameters were derived such as step time up and down (Tup, Tdown), the difference between step time up and down (Tup-down), step irregularity (step time difference of subsequent steps) and step asymmetry (step time difference between affected and non-affected leg). Patients were compared to a control group of 100 healthy subjects (17–81yrs) without any known orthopaedic pathology. Using the results of arthroscopy, test sensitivity and specificity for differentiating healthy and pathologic subjects and for diagnosing MT were calculated based on threshold values. Sensitivity and specificity for detecting pathological motion was 0.68 (CI 0.50–0.81) and 0.92 for the most sensitive parameter (Tdown). Sensitivity and specificity to detect MT was 0.74 and 0.25 percent overall compared to 0.53 and 0.50 for the McMurray. Sensitivity increased to 1.00 when MT was combined with a chondropathy scale III or IV (McMurray 0.33). IMA assessed stair climbing can distinguish healthy and pathological subjects and detect the presence of MT with better sensitivity than classic scores especially when combined with severe chondropathy. IMA is a simple and fast clinical outcome measure suitable for routine follow-up and may support the diagnosis of meniscal tears prior to arthroscopy.
In orthopaedics new objective functional outcome tools are required to validate the benefits of new surgical techniques or implants for which classic scores such as the KSS, HHS or Womac have been shown not to be discriminative enough. Inertia based motion analysis (IMA) is a cheap, fast and simple technique which requires no gait lab or specialist personnel and thus is suitable for routine clinical outcome assessment. IMA on gait has been validated for total knee replacement (TKR) but normal gait was considered not demanding enough for certain orthopaedic differences. Sit-stand-Sit is a more demanding task of daily activity which can be assessed quickly during consultation. This study investigates whether an IMA assessed sit-stand-sit test can differentiate healthy subjects from pre-op TKR patients. Rising (sit-to-stand) from a chair and sitting down (stand-to-sit) at comfortable, self-selected speed was measured three time using a triaxial accelerometer (range: +/−2g, f=100Hz, 64×62×13mm, m=54g) taped to the sacrum. The chair (no armrests) was height adjustable (legs at 90deg flexion) to level the effort for different body heights. 70 healthy volunteers (f/m=48/22, age range: 17–81yrs) were compared to a pathological group of 20 patients with knee osteoarthritis indicated for unilateral TKR (Biomet Vanguard) measured at 1–10 days pre-op (f/m=11/9; mean age: 65.6yrs, range: 45–79; KSS: 43.5, range: 5–65). The healthy group was split into two subgroups, an age-matched “Old” group (>
50yrs: n1=28, mean age: 65.2yrs) and a “Young” group (<
50yrs: n2=32, mean age: 28.0yrs). Motion parameters derived were the time to stand up (Tup), time to sit down (Tdwn), the time difference between rising and sitting down (Tu−d) and the combined time of rising and sitting down (tu+d) as mean values and per individual repetition. All motion parameters were sign. slower with higher variance for the pre-TKR versus the healthy subjects, even when compared to the age-matched subgroup (except Tu−d). Threshold values could be defined to delineate healthy from pathological performance, e.g. Tup>
220ms (6/70=9% vs 17/20=85%, p<
0.01) or Tdwn>
240ms (4/70=6% vs 18/20=90%, p<
0.01) producing high test sensitivity (90%, C.I. 72–98) and specificity (94%, C.I. 89–97). In some false positives (3/6) originally unknown orthopaedic problems were identified in retrospect. The simple IMA assessed sit-stand-sit test produced motion parameters comparable to values reported for smaller subject groups using methods unsuitable for routine clinical application (e.g. electrogoniometry). Healthy and pathological motion could be distinguished with high sensitivity and specificity even versus age matched controls supporting the validity to use the IMA assessed sit-stand-sit test to complement classic outcome scores with an objective functional component.
To clinically diagnose and postoperatively monitor the younger or more demanding orthopaedic patients it becomes increasingly important to measure function beyond the capacity of classic scores suffering from subjectivity, pain dominance and ceiling effects. This study investigates whether a stair climbing test with accelerometer derived motion parameters in a group of healthy subjects is clinically feasible and valid to distinguish between demographic differences. The ascending and descending of stairs (preferred speed, no handrails) was measured in 46 healthy subjects (19m/27f, no orthopaedic pathology) using a triaxial accelerometer attached with a belt to the sacrum. The study group was divided in two age groups: young group (15m/16f; age: 25 [21–38]) and old group (4m/11f; age: 67 [54–74]). Motion parameters were derived by acceleration peak detection algorithms based on step times: tup, tdown, tup-tdown,, step irregularity: irrup, irrdown and asymmetry: asymup, asymdown. Step times were slightly higher ascending (tup=606ms) than descending (tdown=575ms, p<
0.05). The step time difference between ascending and descending (tup-tdown=31ms) showed a significant difference between the young (47ms) and elderly (−7ms). All subjects with descending times ≥20ms slower than ascending (6/46) were elderly. Irregularity and asymmetry were similar between stepping direction and age groups. Asymmetry identified the dominant leg with equal or faster steps than the non-dominant leg in 43/46 cases. Motion parameters were not correlated to gender, height or BMI. Slower step times down than up seem a promising parameter to detect general or bilateral orthopaedic pathologies. Asymmetry identifying the dominant leg shall detect unilateral pathologies. The accelerometer assessed stair test seems suitable for routine clinical follow-up complementing classic scores.
In joint arthroplasty the currently used patient assessment scores suffer from subjectivity, a low ceiling effect and pain dominance. These effects mask functional differences which are important for today’s demanding patients. Functional assessment tools are needed which can objectively monitor patient outcome. This study investigates whether an acceleration based gait test is able to assess TKR patients. A cohort of 24 patients (11m, 13f) operated for osteoarthritis receiving unilateral TKR (Stryker Scorpio) were monitored for 3 months post-operative. Classic scores including subscores (KSS, Womac, VAS, PDI) and a gait test were measured pre-operative, at 2 weeks, 6 weeks and 3 months post-operative. Gait was analyzed using a triaxial accelerometer fixed to the sacrum while walking 6 times a 20m distance at preferred speed. Movement parameters like step frequency, step time, step number, vertical displacement, asymmetry and irregularity were calculated based on a peak detection algorithm. All classic scores were significantly intercorrelated (e.g. KSS and Womac, R=−0.73) indicating a degree of redundancy. Significant correlations were shown between several gait parameters and the KSS, PDI and VAS. Most correlations between gait parameters and a classical score were found for the KSS function subscore indicating it as the most objective functional assessement amongst the classic scores. In contrast Womac did not correlate with any gait parameter. This lack WOMAC capturing objective function was reported before using functional tests. The classic scales and the gait test cover different dimensions of surgical outcome supporting their combined use to follow up patients The accelerometer based gait test is clinically valid for the follow-up of TKR patients.
Patients were clinically assessed for 2 years using the Knee Society Score (KSS). At final follow-up patients were assessed once using two accelerometer based motion tests (Dynaport Knee Test and Minimod Gait Test; McRoberts, Netherlands). The knee score is composed of four sub scores (Locomotion, Rise &
Descend, Transfers, Lift &
Move). The gait test records walking parameters such as step frequency, length and speed plus various parameters of step asymmetry, irregularity and efficiency. Statistical analysis was performed using the van Elteren’s test (KSS data) and a stratified regression analysis (Dynaport and Minimod data)
The Dynaport knee test showed a significant functional advantage for patella resurfacing (RS=44.1+/−12.1, NR=39.7+/−19.2, p=0.04). The sub score Rise &
Descend showed the largest advantage for patella resurfacing (RS=44.7, NR=39.7, p=0.04). The other sub scores also favored resurfacing but were not significant. The Minimod Gait test favoured RS in most parameters but at non-significant levels.
The advantage of patella resurfacing may be less due to pain relief but due to a functional benefit during demanding motion tasks for which standard clinical scores and low demanding tests do not account for sufficiently and objectively enough. We recommend complementing the classic evaluation tools with demanding functional tests.
