The importance to including objective functional outcomes in the clinical follow up of total knee arthroplasty patients

Evaluating Knee Recovery Beyond Patient Reports: A Comparative Study of Smart Implantable Device-Derived Gait Metrics Versus Patient-Reported Outcome Measures in Total Knee Arthroplasty

BACKGROUND

Total Knee Arthroplasty (TKA) is frequently performed for advanced osteoarthritis, with patient-reported outcome measures (PROMs) traditionally reporting on efficacy. These subjective evaluations, although useful, may inaccurately reflect post-TKA activity levels. With technological advancements, smart implantable devices (SIDs) offer objective, real-time gait metrics, potentially providing a more accurate postoperative recovery assessment. This study compares these objective metrics with PROMs to evaluate TKA success more effectively.

METHODS

We conducted a retrospective cohort study with 88 participants undergoing TKA using a SID. Eligible patients were aged 18 years or older and had advanced osteoarthritis. We excluded those who had bilateral TKAs, joint infections, or neuromuscular disease. The SID system collected daily gait metrics, including step count, distance traveled, walking speed, stride length, cadence, and functional knee range of motion. The PROMs, including Knee Injury and Osteoarthritis Outcome Score-Joint Replacement, Veterans Rand 12 Physical Component Summary, and Veterans Rand 12 Mental Component Summary, were analyzed against SID gait metrics. Among the 88 patients, 80 provided continuous data over 12 weeks.

RESULTS

All gait metrics, except stride length, significantly increased at the 12-week point (P < .05). The PROMs also significantly improved postoperatively (P < .05). Initial low positive correlations between 12-week PROMs and SID metrics decreased after adjusting for demographic variables, leaving only weak correlations between the Veterans Rand 12 Physical Component Summary and Knee Injury and Osteoarthritis Outcome Score-Joint Replacement with functional knee range of motion (r = 0.389, P = .002; r = 0.311, P = .014, respectively), and Veterans Rand 12 Mental Component Summary with step count (r = 0.406, P = .001) and distance traveled (r = 0.376, P = .003).

CONCLUSIONS

This study indicates that both PROMs and SID gait metrics show significant improvements post-TKA, though they correlate weakly with each other, suggesting a possible discrepancy between perceived recovery and actual functional improvement. The SID gait metrics might provide a valuable addition to traditional PROMs by offering an objective representation of physical capabilities unaffected by patient compliance or subjective perceptions of recovery. Further research is needed to validate these findings in larger populations and to explore whether integrating SID metrics can enhance long-term functional outcomes.

Wearable sensor-based measures of step-up transfers are supplementary to patient-reported outcome measures following total joint arthroplasty

PURPOSE

This study investigated the longitudinal assessment of step-up performance in patients undergoing total joint arthroplasty (TJA) and correlation with subjective patient reported outcome measures (PROMs).

METHODS

In this sub-analysis of the ADAPT study, PROMs were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Block step-up (BS) transfers were assessed by wearable-derived measures of time. 76 patients undergoing TJA were included. Subgroups were formed isolating the worst performing quartile (low functioning (LF)) from the high functioning (HF), and outcomes were compared.

RESULTS

One-year post-surgery, WOMAC function demonstrated strong correlations to WOMAC pain (Pearson's r = 0.67-0.84) and moderate correlations to BS performance (Pearson's r = 0.31-0.54). Both WOMAC and BS significantly improved with a larger effect size for the HF subgroup (0.62 vs. 0.43; p < 0.05). Patients designated to the LF subgroup at 3 months had increased odds of representing the LF subgroup at 12 months (WOMAC = 19; BS = 4). WOMAC defined 18 LF patients at 12 months follow-up. BS performance identified 9 additional LF patients.

CONCLUSIONS

WOMAC function scores seem pain dominated. Measures of BS performance allow assessment of otherwise hidden residual functional impairment. Lower functioning 3 months post-surgery is predictive of longer-term impairment.

Advances in the application of wearable sensors for gait analysis after total knee arthroplasty: a systematic review

BACKGROUND

Wearable sensors have become a complementary means for evaluation of body function and gait in lower limb osteoarthritis. This study aimed to review the applications of wearable sensors for gait analysis after total knee arthroplasty (TKA).

METHODS

Five databases, including Web of Science Core Collection, Embase, Cochrane, Medline, and PubMed, were searched for articles published between January 2010 and March 2023, using predetermined search terms that focused on wearable sensors, TKA, and gait analysis as broad areas of interest.

RESULTS

A total of 25 articles were identified, involving 823 TKA patients. Methodologies varied widely across the articles, with inconsistencies found in reported patient characteristics, sensor data and experimental protocols. Patient-reported outcome measures (PROMs) and gait variables showed various recovery times from 1 week postoperatively to 5 years postoperatively. Gait analysis using wearable sensors and PROMs showed differences in controlled environments, daily life, and when comparing different surgeries.

CONCLUSION

Wearable sensors offered the potential to remotely monitor the gait function post-TKA in both controlled environments and patients' daily life, and covered more aspects than PROMs. More cohort longitudinal studies are warranted to further confirm the benefits of this remote technology in clinical practice.

Patient reported outcomes do not correlate to functional knee recovery and range of motion in total knee arthroplasty

Background

Many total knee arthroplasty (TKA) patients exhibit continued pain and limited function following surgery. Determining TKA outcomes is typically reliant on post-operative evaluations and completing patient-reported outcomes (PROMs). Due to low compliance rates, it is essential to identify new strategies for monitoring patients. The purpose of this analysis was to assess the correlations between gait kinematics, PROMs, and knee range of motion (ROM).

Methods

130 patients (75 female) received Persona IQ TKA (Zimmer Biomet, Warsaw, IN, USA) which includes a stem extension with embedded accelerometer and gyroscope. PROM scores were compared at baseline and 6 weeks post-TKA using a paired t-test. Gait kinematics were recorded daily via the Persona IQ stem extension. Pearson's correlation coefficients were derived between PROMs and average gait kinematics.

Results

Knee Injury and Osteoarthritis Outcome Score (KOOS Jr.) and Veterans RAND 12 (VR-12) physical scores improved following surgery (p ≤ 0.001, p = 0.003, respectively). Weak statistically significant correlations were found between PROMS and gait kinematics.

Conclusion

Weak correlations between PROMs and gait kinematics indicate patient perception of improvement and objectively measured functional status may not be interchangeable. Further, compliance with Persona IQ data reached 95.4-97.7% (depending on the parameter) at 6 weeks following surgery, a 20% higher compliance rate over PROMs. Daily functional measurements provide insight into the patient's progression and may be useful in detecting poor outcomes.

Evaluation of gait recovery after total knee arthroplasty using wearable inertial sensors: A systematic review

PURPOSE

This study aimed to conduct a systematic review of the recent research output to present more evidence of the current clinical applications of wearable sensors to determine the change and the recovery in gait function pre- and post-total knee arthroplasty (TKA).

METHODS

A systematic search of the PubMed, ScienceDirect, and Scopus databases was conducted in October 2022. Inclusion criteria consisted of applying acceleration wearable sensors for pre- and post-arthroplasty assessment of the gait cycle. Studies reporting gait analysis using wearable sensors in patients with knee osteoarthritis at any time after total or partial knee arthroplasty (KA) were also included. Each included study was assessed using the Joanna Briggs Institute Critical Appraisal Tool for Quasi-Experimental studies.

RESULTS

Twelve articles were finally considered. The extracted data included essential characteristics of participants, KA studies and their characteristics, sensor technology characteristics and the clinical protocols, gait parameter changes, and various clinical outcome scores at different follow up times after KA. Postoperative examinations were performed from 5 days to 1 year after KA. Clinical outcome scores and gait variables for all patient groups, with or without postoperative rehabilitation, showed various recovery profiles. A variety of wireless sensor devices for gait analysis were recorded. Also, different types of KA were found in the studies.

CONCLUSIONS

The study's findings showed that acceleration-based gait analysis has notable clinical use in monitoring patients after KA. This application provides objective information on the functional outcome beyond the use of clinical outcome scores. More extensive prospective studies are required to investigate gait function further with the help of wearable sensors in patients with knee osteoarthritis.

Objective gait assessment in individuals with knee osteoarthritis using inertial sensors: A systematic review and meta-analysis

BACKGROUND

Objective assessment of gait using inertial sensors has shown promising results for functional evaluations in individuals with knee osteoarthritis (OA). However, the large number of possible outcome measures calls for a systematic evaluation of most relevant parameters to be used for scientific and clinical purposes.

AIM

This systematic review and meta-analysis aimed to identify gait parameters derived from inertial sensors that reflect gait deviations in individuals with knee OA compared to healthy control subjects (HC).

METHODS

A systematic search was conducted in five electronic databases (Medline, Embase, Web of Science, CINAHL, IEEE) to identify eligible articles. Risk of bias was assessed using a modified version of the Downs and Black scale. Data regarding study population, experimental procedures, and biomechanical outcomes were extracted. When a gait parameter was reported by a sufficient number of studies, a random-effects meta-analysis was conducted using the inverse variance method.

RESULTS

Twenty-three articles comparing gait between 411 individuals with knee OA and 507 HC were included. Individuals with knee OA had a lower gait speed than HC (standardized mean difference = -1.65), driven by smaller strides with a longer duration. Stride time variability was slightly higher in individuals with knee OA than in HC. Individuals with knee OA walked with a lower range of motion of the knee during the swing phase, less lumbar motion in the coronal plane, and a lower foot strike and toe-off angle compared to HC.

SIGNIFICANCE

This review shows that inertial sensors can detect gait impairments in individuals with knee OA. Large standardized mean differences found on spatiotemporal parameters support their applicability as sensitive endpoints for mobility in individuals with knee OA. More advanced measures, including kinematics of knee and trunk, may reveal gait adaptations that are more specific to knee OA, but compelling evidence was lacking.

Objective monitoring of functional recovery after total knee and hip arthroplasty using sensor-derived gait measures

Background

Inertial sensors hold the promise to objectively measure functional recovery after total knee (TKA) and hip arthroplasty (THA), but their value in addition to patient-reported outcome measures (PROMs) has yet to be demonstrated. This study investigated recovery of gait after TKA and THA using inertial sensors, and compared results to recovery of self-reported scores of pain and function.

Methods

PROMs and gait parameters were assessed before and at two and fifteen months after TKA (n = 24) and THA (n = 24). Gait parameters were compared with healthy individuals (n = 27) of similar age. Gait data were collected using inertial sensors on the feet, lower back, and trunk. Participants walked for two minutes back and forth over a 6m walkway with 180° turns. PROMs were obtained using the Knee Injury and Osteoarthritis Outcome Scores and Hip Disability and Osteoarthritis Outcome Score.

Results

Gait parameters recovered to the level of healthy controls after both TKA and THA. Early improvements were found in gait-related trunk kinematics, while spatiotemporal gait parameters mainly improved between two and fifteen months after TKA and THA. Compared to the large and early improvements found in of PROMs, these gait parameters showed a different trajectory, with a marked discordance between the outcome of both methods at two months post-operatively.

Conclusion

Sensor-derived gait parameters were responsive to TKA and THA, showing different recovery trajectories for spatiotemporal gait parameters and gait-related trunk kinematics. Fifteen months after TKA and THA, there were no remaining gait differences with respect to healthy controls. Given the discordance in recovery trajectories between gait parameters and PROMs, sensor-derived gait parameters seem to carry relevant information for evaluation of physical function that is not captured by self-reported scores.

A Cadaveric Study Addressing the Feasibility of Remote Patient Monitoring Prosthesis for Total Knee Arthroplasty

BACKGROUND

Since the COVID-19 pandemic of 2020, there has been a marked rise in the use of telemedicine to evaluate patients after total knee arthroplasty (TKA). The purpose of our study was to assess a novel stem with an embedded sensor that can remotely and objectively monitor a patient's mobility after TKA.

METHODS

A single anatomically designed knee system was implanted in concert with an interconnected tibial stem extension containing 3D accelerometers, 3D gyroscopes, a power source, and a telemetry transmission capability in 3 cadaveric pelvis to toe specimens. The legs were moved by hand to preset tibial positions at full knee extension, midflexion, flexion, and back to midflexion and extension for a total of 16 trials across 6 knees.

RESULTS

Sensor data were successfully transmitted with good quality of signal to an external base station. Good correlation to the range of motion of the tibia was found (mean error 0.1 degrees; root mean square error 3.8 degrees). The signal from the heel drop tests suggests the sensor could detect heel strike during activities of daily living in vivo and the potential for additional signal processing to analyze vibratory and motion patterns detected by the sensors. A frequency domain analysis of a properly cemented and poorly cemented implant during the heel drop test suggests a difference in accelerometer signal in these implant states.

CONCLUSION

The results confirm signals generated from an embedded TKA sensor can transmit through bone and cement, providing accurate range of motion data and may be capable of detecting changes in prosthesis fixation remotely.

Analysis of characteristics required for gait evaluation of patients with knee osteoarthritis using a wireless accelerometer

BACKGROUND

Knee osteoarthritis (KOA) is associated with reduced quality of life due to knee pain and gait disturbance. However, the evaluation of KOA is mainly based on images and patient-reported outcome measures (PROMs), which are said to be insufficient for functional evaluation. Recently, gait analysis using an accelerometer has been used for functional evaluation of KOA patients. Nevertheless, evaluation of the entire body motion is insufficient. The aim of this study was to clarify the gait characteristics of KOA patients using the distribution of scalar products and the interval time of heel contact during spontaneous walking and to compare them with healthy subjects.

METHODS

Participants wore a three-axis accelerometer sensor on the third lumbar vertebra and walked for 6 min on a flat path at a free walking speed. The sum of a composite vector (CV) scalar product and a histogram for distribution were used for body motion evaluation. The CV consisted of a synthesis of acceleration data from three axes. In addition to the summation of the CV, a histogram can be created to evaluate in detail the magnitude of the waves. The amount of variation was measured in the left-right and front-back directions. Variability was evaluated from the distribution of heel contact duration between both feet measured from the vertical acceleration.

RESULTS

KOA patients showed a smaller sum of CV that converged to small acceleration in the distribution when compared with healthy subjects. In the KOA group, the amount of variation in the forward and backward directions was greater than that in the forward direction. The variability of heel-ground interval time was greater in the KOA group than in healthy subjects.

CONCLUSION

KOA patients walked with less overall body movement, with limited movable range of the knee joint and pain-avoiding motion. The gait of the KOA group was considered unstable, with long time intervals between peaks. The increase in the amount of forward variation was thought to be due to the effect of trunk forward bending during walking. The clinical relevance of this study is that it was possible to evaluate KOA patients' gait quantitatively and qualitatively.

Independent and sensitive gait parameters for objective evaluation in knee and hip osteoarthritis using wearable sensors

Background

Although it is well-established that osteoarthritis (OA) impairs daily-life gait, objective gait assessments are not part of routine clinical evaluation. Wearable inertial sensors provide an easily accessible and fast way to routinely evaluate gait quality in clinical settings. However, during these assessments, more complex and meaningful aspects of daily-life gait, including turning, dual-task performance, and upper body motion, are often overlooked. The aim of this study was therefore to investigate turning, dual-task performance, and upper body motion in individuals with knee or hip OA in addition to more commonly assessed spatiotemporal gait parameters using wearable sensors.

Methods

Gait was compared between individuals with unilateral knee (n = 25) or hip OA (n = 26) scheduled for joint replacement, and healthy controls (n = 27). For 2 min, participants walked back and forth along a 6-m trajectory making 180° turns, with and without a secondary cognitive task. Gait parameters were collected using 4 inertial measurement units on the feet and trunk. To test if dual-task gait, turning, and upper body motion had added value above spatiotemporal parameters, a factor analysis was conducted. Effect sizes were computed as standardized mean difference between OA groups and healthy controls to identify parameters from these gait domains that were sensitive to knee or hip OA.

Results

Four independent domains of gait were obtained: speed-spatial, speed-temporal, dual-task cost, and upper body motion. Turning parameters constituted a gait domain together with cadence. From the domains that were obtained, stride length (speed-spatial) and cadence (speed-temporal) had the strongest effect sizes for both knee and hip OA. Upper body motion (lumbar sagittal range of motion), showed a strong effect size when comparing hip OA with healthy controls. Parameters reflecting dual-task cost were not sensitive to knee or hip OA.

Conclusions

Besides more commonly reported spatiotemporal parameters, only upper body motion provided non-redundant and sensitive parameters representing gait adaptations in individuals with hip OA. Turning parameters were sensitive to knee and hip OA, but were not independent from speed-related gait parameters. Dual-task parameters had limited additional value for evaluating gait in knee and hip OA, although dual-task cost constituted a separate gait domain. Future steps should include testing responsiveness of these gait domains to interventions aiming to improve mobility.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04074-2.

Acceleration Gait Measures as Proxies for Motor Skill of Walking: A Narrative Review

In adults 65 years or older, falls or other neuromotor dysfunctions are often framed as walking-related declines in motor skill; the frequent occurrence of such decline in walking-related motor skill motivates the need for an improved understanding of the motor skill of walking. Simple gait measurements, such as speed, do not provide adequate information about the quality of the body motion's translation during walking. Gait measures from accelerometers can enrich measurements of walking and motor performance. This review article will categorize the aspects of the motor skill of walking and review how trunk-acceleration gait measures during walking can be mapped to motor skill aspects, satisfying a clinical need to understand how well accelerometer measures assess gait. We will clarify how to leverage more complicated acceleration measures to make accurate motor skill decline predictions, thus furthering fall research in older adults.

Wearable Inertial Sensors for Gait Analysis in Adults with Osteoarthritis-A Scoping Review

Our objective was to conduct a scoping review which summarizes the growing body of literature using wearable inertial sensors for gait analysis in lower limb osteoarthritis. We searched six databases using predetermined search terms which highlighted the broad areas of inertial sensors, gait, and osteoarthritis. Two authors independently conducted title and abstract reviews, followed by two authors independently completing full-text screenings. Study quality was also assessed by two independent raters and data were extracted by one reviewer in areas such as study design, osteoarthritis sample, protocols, and inertial sensor outcomes. A total of 72 articles were included, which studied the gait of 2159 adults with osteoarthritis (OA) using inertial sensors. The most common location of OA studied was the knee (n = 46), followed by the hip (n = 22), and the ankle (n = 7). The back (n = 41) and the shank (n = 40) were the most common placements for inertial sensors. The three most prevalent biomechanical outcomes studied were: mean spatiotemporal parameters (n = 45), segment or joint angles (n = 33), and linear acceleration magnitudes (n = 22). Our findings demonstrate exceptional growth in this field in the last 5 years. Nevertheless, there remains a need for more longitudinal study designs, patient-specific models, free-living assessments, and a push for "Code Reuse" to maximize the unique capabilities of these devices and ultimately improve how we diagnose and treat this debilitating disease.

Signatures of knee osteoarthritis in women in the temporal and fractal dynamics of human gait

BACKGROUND

Osteoarthritis of the knee is characterized by progressive cartilage deterioration causing pain and function loss. Symptoms develop late with limited disease-modifying opportunities. Osteoarthritis is a major cause of immobility, with a higher prevalence above 60 years. This age-related increase in prevalence is further amplified by the female gender. Imaging and biochemical analyses for detection of osteoarthritis of the knee are expensive and labor-intensive. Continuous movement tracking could aid in detecting onset and/or worsening of symptoms.

METHODS

We used portable technology to investigate kinematic differences in female patients with knee osteoarthritis, weight-matched healthy female volunteers and obese female patients with osteoarthritis of the knee. Knee osteoarthritis was established radiographically and corroborated using magnetic resonance imaging.

FINDINGS

The total amount, type and level of activity did not differ significantly between groups. The temporal activity pattern during the day was however significantly different with a bimodal signature in healthy volunteers only. Sequence analyses revealed more time to recuperate after dynamic activity in both patient groups. Analysis of walking bouts revealed significant differences in stride interval dynamics, indicative of gait naturalness, only in healthy volunteers. Temporal activity, sequence and walking patterns were independent of body weight.

INTERPRETATION

We thus provide for the first-time evidence of temporal specific kinematic signatures in amount and quality of movement also in stride interval dynamics between people with and without osteoarthritis of the knee independent of body weight. These findings could allow early and non-intrusive diagnosis of osteoarthritis enabling concordant treatment.

Modelling Patient Behaviour Using IoT Sensor Data: a Case Study to Evaluate Techniques for Modelling Domestic Behaviour in Recovery from Total Hip Replacement Surgery

The UK health service sees around 160,000 total hip or knee replacements every year and this number is expected to rise with an ageing population. Expectations of surgical outcomes are changing alongside demographic trends, whilst aftercare may be fractured as a result of resource limitations. Conventional assessments of health outcomes must evolve to keep up with these changing trends. Health outcomes may be assessed largely by self-report using Patient Reported Outcome Measures (PROMs), such as the Oxford Hip or Oxford Knee Score, in the months up to and following surgery. Though widely used, many PROMs have methodological limitations and there is debate about how to interpret results and definitions of clinically meaningful change. With the development of a home-monitoring system, there is opportunity to characterise the relationship between PROMs and behaviour in a natural setting and to develop methods of passive monitoring of outcome and recovery after surgery. In this paper, we discuss the motivation and technology used in long-term continuous observation of movement, sleep and domestic routine for healthcare applications, such as the HEmiSPHERE project for hip and knee replacement patients. In this case study, we evaluate trends evident in data of two patients, collected over a 3-month observation period post-surgery, by comparison with scores from PROMs for sleep and movement quality, and by comparison with a third control home. We find that accelerometer and indoor localisation data correctly highlight long-term trends in sleep and movement quality and can be used to predict sleep and wake times and measure sleep and wake routine variance over time, whilst indoor localisation provides context for the domestic routine and mobility of the patient. Finally, we discuss a visual method of sharing findings with healthcare professionals.

Minimum twelve-year follow-up of fixed- vs mobile-bearing total knee arthroplasty: Double blinded randomized trial

BACKGROUND

Total knee arthroplasty (TKA) with fixed-bearing (FB) implants have demonstrated impressive functional results and survival rates. Meanwhile, rotating-platform (RP) constructs have biomechanically shown to reduce polyethylene wear, lower the risk of component loosening, and better replicate anatomic knee motion. There is growing question of the clinical impact these design changes have long-term.Questions/purposes: The aim of this double-blinded prospective randomized trial was to compare function and implant survival in patients who received either FB or RP press-fit condylar Sigma (PFC Sigma, DePuy, Warsaw, IN) total knee replacements at a minimum follow-up of twelve years.

PATIENTS AND METHODS

Patient reported outcome measures used included the functional Knee Society Score, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores, Medical Outcomes Short Form-36 (SF-36) score, and satisfaction assessment on a four-point Likert scale. The data was collected from times preoperative, two-years, and final encounter (mean 13.95 years). A total of 28 RP and 19 FB knees (58.8%) were analyzed at the final follow-up.

RESULTS

Among all patients, KSS and WOMAC scores statistically improved from pre-op to 2-year, while KSS statistically worsened from 2-year to final follow-up. The RP group averaged better follow-up scores in all assessments at the final follow-up with exception of overall satisfaction. There was no statistically significant difference in the functional Knee Society Score, Short Form-36, WOMAC scores, patient satisfaction or implant survival between the two groups at any measured period.

CONCLUSIONS

The use of a fixed-bearing or rotating-platform design does not convey significant superiority in terms of function or implant longevity at a minimum twelve years after total knee arthroplasty.

LEVEL OF EVIDENCE

Level I, Experimental study, randomized controlled trial (RCT).

Current clinical utilisation of wearable motion sensors for the assessment of outcome following knee arthroplasty: a scoping review

OBJECTIVES

Wearable motion sensors are used with increasing frequency in the evaluation of gait, function and physical activity within orthopaedics and sports medicine. The integration of wearable technology into the clinical pathway offers the ability to improve post-operative patient assessment beyond the scope of current, questionnaire-based patient-reported outcome measures. This scoping review assesses the current methodology and clinical application of accelerometers and inertial measurement units for the evaluation of patient activity and functional recovery following knee arthroplasty.

DESIGN

This is a systematically conducted scoping review following Joanna Briggs Institute methodology for scoping reviews and reported consulting the Preferred Reporting Items for Systematic Review and Meta-Analyses extension for scoping reviews. A protocol for this review is registered with the Open Science Framework (https://osf.io/rzg9q).

DATA SOURCES

CINAHL, EMBASE, MEDLINE and Web of Science databases were searched for manuscripts published between 2008 and 2019.

ELIGIBILITY CRITERIA

We included clinical studies reporting the use of any combination of accelerometers, pedometers or inertial measurement units for patient assessment at any time point following knee arthroplasty.

DATA EXTRACTION AND SYNTHESIS

Data extracted from manuscripts included patient demographics, sensor technology, testing protocol and sensor-based outcome variables.

RESULTS

45 studies were identified, including 2076 knee arthroplasty patients, 620 patients with end-stage osteoarthritis and 449 healthy controls. Primary aims of the identified studies included functional assessment, physical activity monitoring and evaluation of knee instability. Methodology varied widely between studies, with inconsistency in reported sensor configuration, testing protocol and output variables.

CONCLUSIONS

The use of wearable sensors in evaluation of knee arthroplasty procedures is becoming increasingly common and offers the potential to improve clinical understanding of recovery and rehabilitation. While current studies lack consistency, significant opportunity exists for the development of standardised measures and protocols for function and physical activity evaluation.

Gait quality assessed by trunk accelerometry after total knee arthroplasty and its association with patient related outcome measures

BACKGROUND

With an increasingly younger population and more active patients, assessment of functional outcome is more important than ever in patients undergoing total knee arthroplasty. Accelerometers have been used successfully to objectively evaluate gait quality in other fields. The aim of this study was to assess gait quality with accelerometers before and after surgery, and to assess added value of resulting parameters to patient reported outcome measures scores.

METHODS

Sixty-five patients (mean age 65 years (range 41-75)) who underwent primary total knee arthroplasty were evaluated using a tri-axial trunk accelerometer preoperatively and 1 year after surgery. Gait quality parameters derived from the accelerometry data were evaluated in three dimensions at both time points. Factor analysis was performed on all outcome variables and changes from before to 1 year after surgery in the most representative variable for each factor were studied.

FINDINGS

Factor analysis identified three separate gait quality factors, with questionnaire and gait quality parameters loading on different factors. Both gait quality factor scores and questionnaire factor scores improved significantly 1 year after surgery. As expected based on the factor analysis, only weak to moderate associations were found between patient reported outcome measures and gait quality before surgery, after surgery and in change scores.

INTERPRETATION

The independence of patient reported outcome measures and gait quality parameters measured with trunk accelerometry indicates that gait quality parameters provide additional information on functional outcome after total knee arthroplasty. Providing caretakers with objectively measurable targets using accelerometry could help improve outcome of these patients.

Correlations between patient-perceived outcome and objectively-measured biomechanical change following Total Knee Replacement

BACKGROUND

Total Knee Replacement (TKR) surgery is being utilised in a younger, more active population with greater functional expectations. Understanding whether patient-perceived measures of function reflect objective biomechanical measures is critical in understanding whether functional limitations can be adequately captured within a clinical setting.

RESEARCH QUESTION

Do changes in objective gait biomechanics measures reflect patient-reported outcome measures at approximately 12 months following TKR surgery?

METHODS

Three-dimensional gait analysis was performed on 41 patients with OA who were scheduled for TKR surgery, 22 of which have returned for a (9-24 month) follow-up assessment. Principal Component Analysis was used to define features of variation between OA subjects and an additional 31 non-pathological control subjects. These were used to train the Cardiff Classifier, an objective classification technique, and subsequently quantify changes following TKR surgery. Patient-perceived changes were also assessed using the Oxford Knee Score (OKS), Knee Outcome Survey (KOS), and Pain Audit Collection System scores (PACS). Pearson and Spearman correlation coefficients were calculated to establish the relationship between changes in objectively-measured and perceived outcome.

RESULTS

Objective measures of biomechanical change were strongly correlated to changes in OKS(r=-0.695, p < 0.001) and KOS(r=-.810, p < 0.001) assessed outcomes. Pain (PACS) was only related to biomechanical function post-operatively (r=-.623, p = 0.003).

SIGNIFICANCE

In this biomechanics study, the relationship between changes in objective function and patient-reported measures pre to post TKR surgery is stronger than in studies which did not include biomechanics metrics. Quality of movement may hold more significance for a patient's perception of improvement than functional measures which consider only the time taken or distance travelled during functional activities.

Pre-operative sensor-based gait parameters predict functional outcome after total knee arthroplasty

BACKGROUND

Despite the general success of total knee arthroplasty (TKA) regarding patient-reported outcome measures, studies investigating gait function have shown diverse functional outcomes. Mobile sensor-based systems have recently been employed for accurate clinical gait assessments, as they allow a better integration of gait analysis into clinical routines as compared to laboratory based systems.

RESEARCH QUESTION

In this study, we sought to examine whether an accurate assessment of gait function of knee osteoarthritis patients with respect to surgery outcome evaluation after TKA using a mobile sensor-based gait analysis system is possible.

METHODS

A foot-worn sensor-based system was used to assess spatio-temporal gait parameters of 24 knee osteoarthritis patients one day before and one year after TKA, and in comparison to matched control participants. Patients were clustered into positive and negative responder groups using a heuristic approach regarding improvements in gait function. Machine learning was used to predict surgery outcome based on pre-operative gait parameters.

RESULTS

Gait function differed significantly between controls and patients. Patient-reported outcome measures improved significantly after surgery, but no significant global gait parameter difference was observed between pre- and post-operative status. However, the responder groups could be correctly predicted with an accuracy of up to 89% using pre-operative gait parameters. Patients exhibiting high pre-operative gait function were more likely to experience a functional decrease after surgery. Important gait parameters for the discrimination were stride time and stride length.

SIGNIFICANCE

The early identification of post-surgical functional outcomes of patients is of great importance to better inform patients pre-operatively regarding surgery success and to improve post-surgical management.

Evaluation of the Tinetti score and fall risk assessment via accelerometry-based movement analysis

Gait and balance disorders are among the main predisposing factors of falls in elderly. Clinical scales are widely employed to assess the risk of falling, but they require trained personnel. We investigate the use of objective measures obtained from a wearable accelerometer to evaluate the fall risk, determined by the Tinetti clinical scale. Seventy-nine patients and eleven volunteers were enrolled in two rehabilitation centers and underwent a full Tinetti test, while wearing a triaxial accelerometer at the chest. Tinetti scores were assessed by expert physicians and those subjects with a score ≤18 were considered at high risk. First, we analyzed 21 accelerometer features by means of statistical tests and correlation analysis. Second, one regression and one classification problem were designed and solved using a linear model (LM) and an artificial neural network (ANN) to predict the Tinetti outcome. Pearson's correlation between the Tinetti score and a subset of 9 features (mainly related with standing and walking) was 0.71. The misclassification error of high risk patient was 0.21 and 0.11, for LM and ANN, respectively. The work might foster the development of a new generation of applications meant to monitor the time evolution of the fall risk using low cost devices at home.

Normalized gait analysis parameters are closely related to patient-reported outcome measures after total knee arthroplasty

Up till now, only a weak connection could be shown between patient-related outcome measures (PROMs) and measurements obtained by gait analysis (e.g. speed, step length, cadence, ground reaction force, joint moments and ranges of motion) after total knee arthroplasty (TKA). This may result from the methodical problem that regression analyses are performed using data that are not normalized against a healthy population. It does appear reasonable to assume that patients presenting a physiological gait pattern are content with their joint. The more the gait parameters differ from a normal gait pattern the worse the clinical outcome measured by PROMs should be expected to be. In this retrospective study, 40 patients were enrolled who had received a gait analysis after TKA, and whose PROMs had been evaluated. A gender- and age-matched control group was formed out of a group of test persons who had already undergone gait analysis. Gait analysis was undertaken using the motion analysis system 3D Vicon with ten infrared cameras and three strength measuring force plates. The physiological gait analysis parameters were deduced from arithmetic mean values taken from all control patients. The deviances of the operated patients' gait analysis parameters from the arithmetic mean values were squared. From these values, the Pearson correlation coefficients for different PROMs were then calculated, and regression analyses were performed to elucidate the correlation between the different PROMs and gait parameters. In the regression analysis, the normalized cadence, relative gait speed of the non-operated side, and range of the relative knee moment of the operated side could be identified as factors which influence the Forgotten Joint Score (FJS-12). The explanation model showed an increase of the FJS-12 with minimisation of these normalized values corresponding to an approximation of the gait pattern seen in the healthy control group. The connection was strong, having a correlation coefficient of 0.708. A physiological gait pattern after TKA results in better PROMs, especially the FJS-12, than a non-physiological gait pattern does.

Are patients with knee osteoarthritis and patients with knee joint replacement as physically active as healthy persons?

Background

It is well documented that patients with knee osteoarthritis (KOA) suffer from reduced physical function and that function of the affected knee is improved after knee joint replacement (KJR). However, it remains uncertain whether patients with KOA are less physically active than healthy people and whether patients increase their level of physical activity after surgery to a level comparable with that of healthy people. The aim of this study was to examine whether patients with KOA are less physically active than healthy participants and whether patients who have undergone KJR show an increased activity and achieve the same level of physical activity as healthy participants 5 years postoperatively.

Methods

Fifty-four patients with KOA (29 women; mean age 62 ± 8.6; mean body mass index (BMI) 27 ± 5), 52 patients who had KJR due to KOA 5 years earlier (26 women; mean age 66 ± 7.2; mean BMI 30 ± 5) and 171 healthy participants (76 women, mean age 64 ± 9.7, mean BMI 26 ± 5) were included in this cross-sectional study. The level of physical activity was measured over a mean period of 5.5 days with a triaxial accelerometer mounted on the thigh. Number of daily steps, number of daily short walking bouts of <10 s duration and number of daily transfers from sitting to standing position were recorded. Data were analysed using two sample t tests and were adjusted for age, gender and BMI.

Results

Patients with KOA did not differ significantly from healthy participants regarding daily steps (+321, p = 0.50) or daily transfers from sitting to standing (+1.9, p = 0.52) but performed significantly less daily short walking bouts <10 s (-11.9, p = 0.02). Patients after KJR did not differ significantly from healthy participants regarding daily steps (-281, p = 0.60) of transfers from sitting to standing position (-3.2, p = 0.32) but performed significantly less daily short walking bouts <10 s (-21.7, p = 0.001).

Conclusion

Patients with KOA and KJR showed no significant reduction in number of daily step counts and transfers from sitting to standing position when compared with matched healthy controls. However, the number of short walking bouts was reduced in patients with KOA and by twice as much in patients with KJR. This indicates that KOA and treatment with KJR hardly affect health-related general activity but do affect specific physical activity behaviour potentially indicative of KOA or post-KJR functional limitations.

The translational potential of this article

Activity monitoring with an accelerometer-based method gives insights into health-related general activity levels such as total daily steps and specific parameters such as short walking bouts, which may serve as an objective outcome measure in clinical practice.

A Review on Accelerometry-Based Gait Analysis and Emerging Clinical Applications

Gait analysis continues to be an important technique for many clinical applications to diagnose and monitor certain diseases. Many mental and physical abnormalities cause measurable differences in a person's gait. Gait analysis has applications in sport, computer games, physical rehabilitation, clinical assessment, surveillance, human recognition, modeling, and many other fields. There are established methods using various sensors for gait analysis, of which accelerometers are one of the most often employed. Accelerometer sensors are generally more user friendly and less invasive. In this paper, we review research regarding accelerometer sensors used for gait analysis with particular focus on clinical applications. We provide a brief introduction to accelerometer theory followed by other popular sensing technologies. Commonly used gait phases and parameters are enumerated. The details of selecting the papers for review are provided. We also review several gait analysis software. Then we provide an extensive report of accelerometry-based gait analysis systems and applications, with additional emphasis on trunk accelerometry. We conclude this review with future research directions.

Clinical Evaluation and Gait Characteristics before and after Total Knee Arthroplasty Based on a Portable Gait Analyzer

OBJECTIVE

To evaluate the effects of surgery and rehabilitation on patients undergoing total knee arthroplasty (TKA).

METHODS

Twelve patients and 12 healthy controls were enrolled and their clinical scores evaluated by a doctor. Gait data, including walking velocity, stride length, single support time, foot fall and swing power, were collected using a portable gait analyzer from 12 patients before and 6 weeks and 6 months after surgery and from 12 healthy controls. The gait data and clinical scores at selected time points were compared and correlations between gait characteristics and clinical scores assessed.

RESULTS

Clinical knee and knee function scores increased significantly from before surgery to 6 weeks to 6 months after surgery (P < 0.001). The only significant differences identified were for single support time on the diseased side between before surgery and 6 months after surgery (P = 0.031) and for foot fall with the diseased side between 6 weeks and 6 months after surgery (P = 0.016). Foot fall and speed of the healthy or diseased sides were significantly different in patients at all time points from those of the healthy subjects (P < 0.05). Single support time on the diseased side was significantly different 6 months after surgery (P = 0.035) in patients than in healthy controls. Single support time on the healthy side before surgery was significantly different from that of healthy controls (P = 0.048) and 6 weeks after surgery (P = 0.042). Stride lengths differed significantly between patients and healthy subjects before surgery (healthy side: P = 0.007; diseased side: P = 0.008) and 6 weeks after surgery (healthy side: P = 0.001; diseased side: P = 0.001), but were not different at 6 months after surgery (healthy side: P = 0.088; diseased side: P = 0.077). The only significant correlations identified were between single support time with the diseased side of patients and their knee (r = 0.43, P = 0.032) and knee function scores (r = 0.493, P = 0.012).

CONCLUSIONS

A portable gait analyzer appears to be suitable for evaluating the effects of TKA. Single support time on the diseased side may be a sensitive quantitative index for determining the effect of TKA and rehabilitation.

Evaluating physical function and activity in the elderly patient using wearable motion sensors

Wearable sensors, in particular inertial measurement units (IMUs) allow the objective, valid, discriminative and responsive assessment of physical function during functional tests such as gait, stair climbing or sit-to-stand.

Applied to various body segments, precise capture of time-to-task achievement, spatiotemporal gait and kinematic parameters of demanding tests or specific to an affected limb are the most used measures.

In activity monitoring (AM), accelerometry has mainly been used to derive energy expenditure or general health related parameters such as total step counts.

In orthopaedics and the elderly, counting specific events such as stairs or high intensity activities were clinimetrically most powerful; as were qualitative parameters at the ‘micro-level’ of activity such as step frequency or sit-stand duration.

Low cost and ease of use allow routine clinical application but with many options for sensors, algorithms, test and parameter definitions, choice and comparability remain difficult, calling for consensus or standardisation.

Cite this article: Grimm B, Bolink S. Evaluating physical function and activity in the elderly patient using wearable motion sensors. EFORT Open Rev 2016;1:112–120. DOI: 10.1302/2058-5241.1.160022.

Outcome in total knee arthroplasty with a medial-lateral balanced versus unbalanced gap

PURPOSE

To evaluate the clinical outcome in 108 total knee arthroplasty (TKA) patients with a medial-lateral balanced versus unbalanced gap after a mean follow-up of 34 months.

METHODS

64 women and 44 men (mean age, 69.5 years) underwent computer-assisted TKA for osteoarthritis using a cemented fixed-bearing cruciate-retaining prosthesis. The medial-lateral gap difference (measured with the prosthesis in situ and the patella reduced) was balanced (≤2 mm) in 81 patients and unbalanced (>2 mm) in 27 patients. After a mean follow-up of 34 months, patients were assessed using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) questionnaire for pain, stiffness, and physical function. Scores were normalised to 0% (worst) to 100% (best).

RESULTS

The balanced and unbalanced gap groups were comparable in terms of age, severity of osteoarthritis, and proportion of pre- and post-operative mechanical alignment. Compared with the balanced gap group, the unbalanced gap group had a larger medial-lateral extension gap difference (0.75±0.57 vs. 2.02±1.15 mm, p=0.001) and medial-lateral flexion gap difference (0.79±0.63 vs. 2.98±2.13 mm, p=0.001) and lower normalised total WOMAC score (84.9±18 vs. 74.8±20.8, p=0.017).

CONCLUSION

WOMAC score is better in TKAs with a medial-lateral balanced (<2 mm) gap.

Frontal plane pelvic motion during gait captures hip osteoarthritis related disability

Gait analysis has widely been accepted as an objective measure of function and clinical outcome. Ambulatory accelerometer-based gait analysis has emerged as a clinically more feasible alternative to optical motion capture systems but does not provide kinematic characterisation to identify disease dependent mechanisms causing walking disability. This study investigated the potential of a single inertial sensor to derive frontal plane motion of the pelvis (i.e. pelvic obliquity) and help identify hip osteoarthritis (OA) related gait alterations. Patients with advanced unilateral hip OA (n = 20) were compared to patients with advanced unilateral knee OA (n = 20) and to a healthy control group (n = 20). Kinematic characterisation of frontal plane pelvic motion during gait demonstrated decreased range of motion and increased asymmetry for hip OA patients specifically.

Improving patients’ experience and outcome of total joint replacement: the RESTORE programme

Background

Total hip replacements (THRs) and total knee replacements (TKRs) are common elective procedures. In the REsearch STudies into the ORthopaedic Experience (RESTORE) programme, we explored the care and experiences of patients with osteoarthritis after being listed for THR and TKR up to the time when an optimal outcome should be expected.

Objective

To undertake a programme of research studies to work towards improving patient outcomes after THR and TKR.

Methods

We used methodologies appropriate to research questions: systematic reviews, qualitative studies, randomised controlled trials (RCTs), feasibility studies, cohort studies and a survey. Research was supported by patient and public involvement.

Results

Systematic review of longitudinal studies showed that moderate to severe long-term pain affects about 7–23% of patients after THR and 10–34% after TKR. In our cohort study, 10% of patients with hip replacement and 30% with knee replacement showed no clinically or statistically significant functional improvement. In our review of pain assessment few research studies used measures to capture the incidence, character and impact of long-term pain. Qualitative studies highlighted the importance of support by health and social professionals for patients at different stages of the joint replacement pathway. Our review of longitudinal studies suggested that patients with poorer psychological health, physical function or pain before surgery had poorer long-term outcomes and may benefit from pre-surgical interventions. However, uptake of a pre-operative pain management intervention was low. Although evidence relating to patient outcomes was limited, comorbidities are common and may lead to an increased risk of adverse events, suggesting the possible value of optimising pre-operative management. The evidence base on clinical effectiveness of pre-surgical interventions, occupational therapy and physiotherapy-based rehabilitation relied on small RCTs but suggested short-term benefit. Our feasibility studies showed that definitive trials of occupational therapy before surgery and post-discharge group-based physiotherapy exercise are feasible and acceptable to patients. Randomised trial results and systematic review suggest that patients with THR should receive local anaesthetic infiltration for the management of long-term pain, but in patients receiving TKR it may not provide additional benefit to femoral nerve block. From a NHS and Personal Social Services perspective, local anaesthetic infiltration was a cost-effective treatment in primary THR. In qualitative interviews, patients and health-care professionals recognised the importance of participating in the RCTs. To support future interventions and their evaluation, we conducted a study comparing outcome measures and analysed the RCTs as cohort studies. Analyses highlighted the importance of different methods in treating and assessing hip and knee osteoarthritis. There was an inverse association between radiographic severity of osteoarthritis and pain and function in patients waiting for TKR but no association in THR. Different pain characteristics predicted long-term pain in THR and TKR. Outcomes after joint replacement should be assessed with a patient-reported outcome and a functional test.

Conclusions

The RESTORE programme provides important information to guide the development of interventions to improve long-term outcomes for patients with osteoarthritis receiving THR and TKR. Issues relating to their evaluation and the assessment of patient outcomes are highlighted. Potential interventions at key times in the patient pathway were identified and deserve further study, ultimately in the context of a complex intervention.

Study registration

Current Controlled Trials ISRCTN52305381.

Funding

This project was funded by the NIHR Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 4, No. 12. See the NIHR Journals Library website for further project information.

The efficacy of early initiated, supervised, progressive resistance training compared to unsupervised, home-based exercise after unicompartmental knee arthroplasty: a single-blinded randomized controlled trial

Objective:

To examine if supervised progressive resistance training was superior to home-based exercise in rehabilitation after unicompartmental knee arthroplasty.

Design:

Single blinded, randomized clinical trial.

Setting:

Surgery, progressive resistance training and testing was carried out at Aarhus University Hospital and home-based exercise was carried out in the home of the patient.

Subjects:

Fifty five patients were randomized to either progressive resistance training or home-based exercise.

Intervention:

Patients were randomized to either progressive resistance training (home based exercise five days/week and progressive resistance training two days/week) or control group (home based exercise seven days/week).

Main measures:

Preoperative assessment, 10-week (primary endpoint) and one-year follow-up were performed for leg extension power, spatiotemporal gait parameters and knee injury and osteoarthritis outcome score (KOOS).

Results:

Forty patients (73%) completed 1-year follow-up. Patients in the progressive resistance training group participated in average 11 of 16 training sessions. Leg extension power increased from baseline to 10-week follow-up in progressive resistance training group (progressive resistance training: 0.28 W/kg, P= 0.01, control group: 0.01 W/kg, P=0.93) with no between-group difference. Walking speed and KOOS scores increased from baseline to 10-week follow-up in both groups with no between-group difference (six minutes walk test P=0.63, KOOS P>0.29).

Conclusions:

Progressive resistance training two days/week combined with home based exercise five days/week was not superior to home based exercise seven days/week in improving leg extension power of the operated leg.

Does the addition of hip strengthening exercises improve outcomes following total knee arthroplasty? A study protocol for a randomized trial

BACKGROUND

Total knee arthroplasty (TKA) is effective in reducing pain and improving function for end-stage knee osteoarthritis. However, muscle weakness and functional limitations persist despite assistance from post-operative rehabilitation programs that traditionally focus on quadriceps strengthening and range of movement exercises. Hip abductor muscle weakness is evident in knee osteoarthritis and hip muscle strengthening reduces knee pain in this group. Following TKA, people with weak hip abductor strength perform more poorly on measures of physical function. However, very little is known of the effectiveness of including hip abductor strengthening exercises in post-operative rehabilitation. The aim of this trial is to compare the effects of targeted hip abductor strengthening to those of traditional care in a TKA rehabilitation program on muscle strength, patient reported outcomes and functional performance measures.

METHODS/DESIGN

This protocol describes a single-blinded randomized controlled trial, where 104 participants referred for inpatient rehabilitation following TKA will be recruited. Participants will be randomized using computer-generated numbers to one of two groups: usual care or usual care with additional hip strengthening exercises. Participants will attend physiotherapy daily during their inpatient length of stay, and will then attend between six and eight physiotherapy sessions as an outpatient. Primary outcomes are isometric hip abductor strength and the Knee Injury and Osteoarthritis Outcome Score (KOOS). Secondary outcomes are stair climb test, 6 min walk test, timed up and go, 40 m fast-paced walk test, 30 second chair stand test, isometric quadriceps strength, Lower Extremity Functional Scale (LEFS) and SF-12. Outcome measures will be recorded at baseline (admission to inpatient rehabilitation), and then 3 weeks, 6 weeks and 6 months post admission to rehabilitation.

DISCUSSION

The findings of this study will determine whether the addition of targeted hip strengthening to usual care rehabilitation improves physical performance and patient reported outcomes following TKA when compared to usual care rehabilitation. This will then determine whether targeted hip strengthening exercises should be included in traditional rehabilitation programs to improve the outcomes following total knee arthroplasty.

TRIAL REGISTRATION

The trial protocol was registered with the Australian Clinical Trial Registry ( ACTRN12615000863538 ) on 18 August 2015.

Assessment of physical function following total hip arthroplasty: Inertial sensor based gait analysis is supplementary to patient-reported outcome measures

BACKGROUND

Functional outcome assessment after total hip arthroplasty often involves subjective patient-reported outcome measures whereas analysis of gait is more objective. The study's aims were to compare subjective and objective functional outcomes after total hip arthroplasty between patients with low and high self-reported levels of pre-operative physical function.

METHODS

Patients undergoing total hip arthroplasty (n=36; m/f=18/18; mean age=63.9; SD=9.8 years; BMI=26.3; SD=3.5) were divided into a low and high function subgroup, and prospective measures of WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) function score and gait were compared at baseline and 3 and 12 months post-operatively.

FINDINGS

WOMAC function scores significantly improved in both low and high function subgroups at 3 months post-operatively whereas gait parameters only improved in patients with a low pre-operative function. Between 3 and 12 months post-operatively, WOMAC function scores had not significantly further improved whereas several gait parameters significantly improved in the low function group. WOMAC function scores and gait parameters were only moderately correlated (Spearman's r=0.33-0.51).

INTERPRETATION

In a cohort of patients undergoing total hip arthroplasty, pre-operative differences in mean WOMAC function scores and gait parameters between low and high function subgroups disappeared by 3 months post-operatively. Gait parameters only improved significantly during the first 3 post-operative months in patients with a low pre-operative function, highlighting the importance of investigating relative changes rather than the absolute changes and the need to consider patients with high and low functions separately.

Validity of an inertial measurement unit to assess pelvic orientation angles during gait, sit-stand transfers and step-up transfers: Comparison with an optoelectronic motion capture system

An inertial measurement unit (IMU) allows kinematic evaluation of human motion with fewer operational constraints than a gold standard optoelectronic motion capture (MOCAP) system. The study's aim was to compare IMU and MOCAP measurements of dynamic pelvic orientation angles during different activities of daily life (ADL): gait, sit-to-stand (STS) transfers and block step-up (BS) transfers. A single IMU was attached onto the lower back in seventeen healthy participants (8F/9 M, age 19-31 years; BMI < 25) and optical skin markers were attached onto anatomical pelvic landmarks for MOCAP measurements. Comparisons between IMU and MOCAP by Bland-Altman plots demonstrated that measurements were between 2SD of the absolute difference and Pearson's correlation coefficients were between 0.85 and 0.94. Frontal plane pelvic angle estimations achieved a RMSE in the range of [2.7°-4.5°] and sagittal plane measurements achieved a RMSE in the range of [2.7°-8.9°] which were both lowest in gait. Waveform peak detection times demonstrated ICCs between 0.96 and 1.00. These results are in accordance to other studies comparing IMU and MOCAP measurements with different applications and suggest that an IMU is a valid tool to measure dynamic pelvic angles during various activities of daily life which could be applied to monitor rehabilitation in a wide variety of musculoskeletal disorders.

Patient-reported outcome measures versus inertial performance-based outcome measures: A prospective study in patients undergoing primary total knee arthroplasty

BACKGROUND

Outcome assessment of total knee arthroplasty (TKA) by subjective patient reported outcome measures (PROMs) may not fully capture the functional (dis-)abilities of relevance. Objective performance-based outcome measures could provide distinct information. An ambulant inertial measurement unit (IMU) allows kinematic assessment of physical performance and could potentially be used for routine follow-up.

AIM

To investigate the responsiveness of IMU measures in patients following TKA and compare outcomes with conventional PROMs.

METHODS

Patients with end stage knee OA (n=20, m/f=7/13; age=67.4 standard deviation 7.7 years) were measured preoperatively and one year postoperatively. IMU measures were derived during gait, sit-stand transfers and block step-up transfers. PROMs were assessed by using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Knee Society Score (KSS). Responsiveness was calculated by the effect size, correlations were calculated with Spearman's rho correlation coefficient.

RESULTS

One year after TKA, patients performed significantly better at gait, sit-to-stand transfers and block step-up transfers. Measures of time and kinematic IMU measures demonstrated significant improvements postoperatively for each performance-based test. The largest improvement was found in block step-up transfers (effect size=0.56-1.20). WOMAC function score and KSS function score demonstrated moderate correlations (Spearman's rho=0.45-0.74) with some of the physical performance-based measures pre- and postoperatively.

CONCLUSION

To characterize the changes in physical function after TKA, PROMs could be supplemented by performance-based measures, assessing function during different activities and allowing kinematic characterization with an ambulant IMU.

Improvements in knee biomechanics during walking are associated with increased physical activity after total knee arthroplasty

Total knee arthroplasty (TKA) in people with knee osteoarthritis increases knee-specific and general physical function, but it has not been established if there is a relationship between changes in these elements of functional ability. This study investigated changes and relationships between knee biomechanics during walking, physical activity, and use of time after TKA. Fifteen people awaiting TKA underwent 3D gait analysis before and six months after surgery. Physical activity and use of time were determined in free-living conditions from a high resolution 24-h activity recall. After surgery, participants displayed significant improvements in sagittal plane knee biomechanics and improved their physical activity profiles, standing for 105 more minutes (p=0.001) and performing 64 min more inside chores on average per day (p=0.008). Changes in sagittal plane knee range of motion (ROM) and peak knee flexion positively correlated with changes in total daily energy expenditure, time spent undertaking moderate to vigorous physical activity, inside chores and passive transport (r=0.52-0.66, p=0.005-0.047). Restoration of knee function occurs in parallel and is associated with improvements in physical activity and use of time after TKA. Increased functional knee ROM is required to support improvements in total and context specific physical activity.

Clinical evaluation of a mobile sensor-based gait analysis method for outcome measurement after knee arthroplasty

Clinical scores and motion-capturing gait analysis are today's gold standard for outcome measurement after knee arthroplasty, although they are criticized for bias and their ability to reflect patients' actual quality of life has been questioned. In this context, mobile gait analysis systems have been introduced to overcome some of these limitations. This study used a previously developed mobile gait analysis system comprising three inertial sensor units to evaluate daily activities and sports. The sensors were taped to the lumbosacral junction and the thigh and shank of the affected limb. The annotated raw data was evaluated using our validated proprietary software. Six patients undergoing knee arthroplasty were examined the day before and 12 months after surgery. All patients reported a satisfactory outcome, although four patients still had limitations in their desired activities. In this context, feasible running speed demonstrated a good correlation with reported impairments in sports-related activities. Notably, knee flexion angle while descending stairs and the ability to stop abruptly when running exhibited good correlation with the clinical stability and proprioception of the knee. Moreover, fatigue effects were displayed in some patients. The introduced system appears to be suitable for outcome measurement after knee arthroplasty and has the potential to overcome some of the limitations of stationary gait labs while gathering additional meaningful parameters regarding the force limits of the knee.

No clinical benefit of gender-specific total knee arthroplasty

BACKGROUND AND PURPOSE

There is no consensus regarding the clinical relevance of gender-specific prostheses in total knee arthroplasty (TKA). We summarize the current best evidence in a comparison of clinical and radiographic outcomes between gender-specific prostheses and standard unisex prostheses in female patients.

METHODS

We used the PubMed, Embase, Cochrane, Science Citation Index, and Scopus databases. We included randomized controlled trials published up to January 2013 that compared gender-specific prostheses with standard unisex prostheses in female patients who underwent primary TKAs.

RESULTS

6 trials involving 423 patients with 846 knee joints met the inclusion criteria. No statistically significant differences were observed between the 2 designs regarding pain, range of motion (ROM), knee scores, satisfaction, preference, complications, and radiographic results. The gender-specific design (Gender Solutions; Zimmer Inc, Warsaw, Indiana) reduced the prevalence of overhang. However, it had less overall coverage of the femoral condyles compared to the unisex group. In fact, the femoral prosthesis in the standard unisex group matched better than that in the gender-specific group.

INTERPRETATION

Gender-specific prostheses do not appear to confer any benefit in terms of clinician- and patient-reported outcomes for the female knee.

Clinimetric quality of the new 2011 Knee Society score: high validity, low completion rate

BACKGROUND

The demands of the younger and more active current total knee arthroplasty (TKA) patients are not in line with the current outcome assessments. Therefore, new questionnaires are developed or adjusted, as with the popular 1989 Knee Society Score (KSS). This study is the first to investigate the clinimetric parameters of the patient-reported outcome measurement (PROM) part of the 2011 KSS.

METHODS

Four-hundred-fifteen primary Dutch TKA patients were scored using the PROM part of the 2011 KSS. The scale is subdivided into an Objective (not evaluated), Satisfaction, Expectation and Function subscales. Clinimetric quality was evaluated by response and completion rate, test-retest reliability (n=29, intraclass correlation coefficient), internal consistency (n=172, Cronbach's alpha), construct validity (Pearson's correlations with 1989 KSS (n=75) and KOOS-PS (n=139)) and responsiveness (n=20, paired-samples t-test, effect sizes and floor and ceiling effects).

RESULTS

A response rate of 96% and completion rate of 43% were found. Reliability and internal consistency proved excellent with ICCs≥0.79 and Cronbach's alpha≥0.76 for all subscales. Strong correlations were found between the Function subscales of the 2011 KSS and KOOS-PS (r=-0.60 to -0.83). All subscales improved significantly after intervention, with exception of Walking & Standing and Discretionary Activities. 23% reached the maximum score postoperatively in Walking & Standing, indicating a ceiling effect.

CONCLUSIONS

The 2011 KSS is a reliable, internal consistent, construct valid and responsive questionnaire to assess the outcome of the Dutch TKA patients. Optimizations (e.g. shortening the scale, simplified design) are recommended to increase the disappointing completion rate.

CLINICAL RELEVANCE

The 2011 KSS is a reliable, internal consistent, construct valid and responsive questionnaire to assess the outcome of the Dutch TKA patients.

Osteoarthritis 2012 year in review: rehabilitation and outcomes

Recent scientific advances in the treatment of hip and knee osteoarthritis (OA) relating to education, exercise, weight control and passive non-pharmacological and non-surgical treatments such as manual therapy, orthoses/orthotics and other aids are described.

METHODS

A systematic literature search was performed in Medline from July 2011 to 10 April 2012 using the terms 'osteoarthritis, knee', 'osteoarthritis, hip' rehabilitation, physical therapy, exercise therapy and preoperative intervention; both as text words and as MeSH terms where possible. Trials evaluating rehabilitation interventions were included if they were randomized controlled trials (RCTs) or systematic reviews. Outcome papers were identified by combining the initial search with the terms 'outcome', 'measure*', 'valid*', 'reliabil*' or 'responsiveness'. Outcome studies were included if they contributed methodologically to advancing outcome measurement.

RESULTS

The literature search identified 550 potentially relevant papers. Seventeen RCTs on rehabilitation were selected and the results from these were supported by six systematic reviews. Sixteen outcomes papers were considered relevant, but did not add significantly to current knowledge about outcome measures in OA and so, were not included.

CONCLUSION

The current research focus on non-pharmacological and non-surgical treatments for hip and/or knee OA, when combined in systematic reviews, is improving the available evidence to identify best practice treatment. Education, exercise and weight loss are effective in the long term and supported as cost-effective first-line treatments.

Assessing function in patients undergoing joint replacement: a study protocol for a cohort study

BACKGROUND

Joint replacement is an effective intervention for people with advanced arthritis, although there is an important minority of patients who do not improve post-operatively. There is a need for robust evidence on outcomes after surgery, but there are a number of measures that assess function after joint replacement, many of which lack any clear theoretical basis. The World Health Organisation has introduced the International Classification of Functioning, Disability and Health (ICF), which divides function into three separate domains: Impairment, activity limitations and participation restrictions. The aim of this study is to compare the properties and responsiveness of a selection of commonly used outcome tools that assess function, examine how well they relate to the ICF concepts, and to explore the changes in the measures over time.

METHODS/DESIGN

Two hundred and sixty three patients listed for lower limb joint replacement at an elective orthopaedic centre have been recruited into this study. Participants attend the hospital for a research appointment prior to surgery and then at 3-months and 1-year after surgery. At each assessment time, function is assessed using a range of measures. Self-report function is assessed using the WOMAC, Aberdeen Impairment, Activity Limitation and Participation Restriction Measure, SF-12 and Measure Yourself Medical Outcome Profile 2. Clinician-administered measures of function include the American Knee Society Score for knee patients and the Harris Hip Score for hip patients. Performance tests include the timed 20-metre walk, timed get up and go, sit-to-stand-to-sit, step tests and single stance balance test. During the performance tests, participants wear an inertial sensor and data from motion analysis are collected. Statistical analysis will include exploring the relationship between measures describing the same ICF concepts, assessing responsiveness, and studying changes in measures over time.

DISCUSSION

There are a range of tools that can be used to assess function before and after joint replacement, with little information about how these various measures compare in their properties and responsiveness. This study aims to provide this data on a selection of commonly used assessments of function, and explore how they relate to the ICF domains.

Tibial component designs in primary total knee arthroplasty: should we reconsider all-polyethylene component?

PURPOSE

Despite the frequency with which total knee arthroplasties (TKAs) are performed, whether they are best performed using all-polyethylene or metal-backed tibial components remains a controversy. The aim of the present study was to determine the advantages and disadvantages of metal-backed compared with all-polyethylene tibial components during TKAs through an evaluation of current literature.

METHODS

A meta-analysis and systematic review of randomized and non-randomized comparative studies comparing metal-backed with all-polyethylene tibial components during TKAs were performed. The focus of the analysis was on the outcomes of knee score, range of motion (ROM), quality of life, implant alignment, tibial migration, radiolucent line, complication, reoperation, and implant survivorship.

RESULTS

A total of 10 randomized/quasi-randomized controlled trials and 13 non-randomized comparative studies assessing 19,767 TKAs were eligible. On the basis of these studies, no significant differences were found between the 2 groups with regard to knee score, ROM, quality of life, complication, and reoperation. The findings indicated that using all-polyethylene tibial components is associated with lower continuous migration rate compared with metal-backed tibial components. Only 13 studies provided adequate data on implant survivorship during intermediate or long-term follow-up. Of these, 9 found that no statistical significance existed between the 2 groups. The other 3 studies found that using all-polyethylene components yielded a higher survival rate than using metal-backed components.

CONCLUSIONS

Metal-backed tibial components had no obvious advantages over all-polyethylene tibial components in TKAs. However, this finding should be interpreted with caution due to publication bias, low methodological quality of the included studies, and different surgical interventions.

LEVEL OF EVIDENCE

Therapeutic study (systematic review and meta-analysis), Level III.

Accelerometry-based gait analysis, an additional objective approach to screen subjects at risk for falling

This study investigated whether the Tinetti scale, as a subjective measure for fall risk, is associated with objectively measured gait characteristics. It is studied whether gait parameters are different for groups that are stratified for fall risk using the Tinetti scale. Moreover, the discriminative power of gait parameters to classify elderly according to the Tinetti scale is investigated. Gait of 50 elderly with a Tinneti>24 and 50 elderly with a Tinetti≤24 was analyzed using acceleration-based gait analysis. Validated algorithms were used to derive spatio-temporal gait parameters, harmonic ratio, inter-stride amplitude variability and root mean square (RMS) from the accelerometer data. Clear differences in gait were found between the groups. All gait parameters correlated with the Tinetti scale (r-range: 0.20-0.73). Only walking speed, step length and RMS showed moderate to strong correlations and high discriminative power to classify elderly according to the Tinetti scale. It is concluded that subtle gait changes that have previously been related to fall risk are not captured by the subjective assessment. It is therefore worthwhile to include objective gait assessment in fall risk screening.