Wearable Sensors in Other Medical Domains with Application Potential for Orthopedic Trauma Surgery-A Narrative Review.

The use of wearable technology is steadily increasing. In orthopedic trauma surgery, where the musculoskeletal system is directly affected, focus has been directed towards assessing aspects of physical functioning, activity behavior, and mobility/disability. This includes sensors and algorithms to monitor real-world walking speed, daily step counts, ground reaction forces, or range of motion. Several specific reviews have focused on this domain. In other medical fields, wearable sensors and algorithms to monitor digital biometrics have been used with a focus on domain-specific health aspects such as heart rate, sleep, blood oxygen saturation, or fall risk. This review explores the most common clinical and research use cases of wearable sensors in other medical domains and, from it, derives suggestions for the meaningful transfer and application in an orthopedic trauma context.

Wearable activity data can predict functional recovery after musculoskeletal injury: Feasibility of a machine learning approach.

Delayed functional recovery after injury is associated with significant personal and socioeconomic burden. Identification of patients at risk for a prolonged recovery after a musculoskeletal injury is thus of high relevance. The aim of the current study was to show the feasibility of using a machine learning assisted model to predict functional recovery based on the pre- and immediate post injury patient activity as measured with wearable systems in trauma patients. Patients with a pre-existing wearable (smartphone and/or body-worn sensor), data availability of at least 7 days prior to their injury, and any musculoskeletal injury of the upper or lower extremity were included in this study. Patient age, sex, injured extremity, time off work and step count as activity data were recorded continuously both pre- and post-injury. Descriptive statistics were performed and a logistic regression machine learning model was used to predict the patient's functional recovery status after 6 weeks based on their pre- and post-injury activity characteristics. Overall 38 patients (7 upper extremity, 24 lower extremity, 5 pelvis, 2 combined) were included in this proof-of-concept study. The average follow-up with available wearable data was 85.4 days. Based on the activity data, a predictive model was constructed to determine the likelihood of having a recovery of at least 50 % of the pre-injury activity state by post injury week 6. Based on the individual activity by week 3 a predictive accuracy of over 80 % was achieved on an independent test set (F1=0,82; AUC=0,86; ACC=8,83). The employed model is feasible to assess the principal risk for a slower recovery based on readily available personal wearable activity data. The model has the potential to identify patients requiring additional aftercare attention early during the treatment course, thus optimizing return to the pre-injury status through focused interventions. Additional patient data is needed to adapt the model to more specifically focus on different fracture entities and patient groups.

1st EFORT European Consensus "Medical & Scientific Research Requirements for the Clinical Introduction of Artificial Joint Arthroplasty Devices": Background, Delphi Methodology & Consensus process.

The objectives of the 1st EFORT European Consensus on 'Medical and Scientific Research Requirements for the Clinical Introduction of Artificial Joint Arthroplasty Devices' were foremost to focus on patient safety by establishing performance requirements for medical devices. The 1st EFORT European Consensus applied an a priori-defined, modified Delphi methodology to produce unbiased, high-quality recommendation statements, confirmed by consensus voting of a European expert panel. Intended key outcomes are practical guidelines justified by the current stage of knowledge and based on a broad European Expert Consensus, to maintain innovation and optimisation of orthopaedic devices within the boundaries of MDR 2017/745. Twenty-one main research areas of relevance were defined relying on input from the EFORT IPSI WG1 'Introduction of Innovation' recommendations and a related survey. A modified Delphi approach with a preparatory literature review and work in small groups were used to prepare answers to the research questions in the form of 32 draft Consensus statements. A Consensus Conference in a hybrid format, on-site in the Carl Gustav Carus University of Dresden was organised to further refine the draft statements and define consensus within the complete group of participants by final voting, intended to further quantify expert opinion knowledge. The modified Delphi approach provides practical guidelines for hands-on orientation for orthopaedic surgeons, research institutes and laboratories, orthopaedic device manufacturers, patient representatives, Notified Bodies, National Institutes and authorities. For the first time, initiated by the EFORT IPSI (WG1 'Introduction of Innovation'), knowledge of all related stakeholders was combined in the 1st EFORT European Consensus to develop guidelines and result in a comprehensive set of recommendations.

Best practice in digital orthopaedics.

Digitization in orthopaedics and traumatology is an enormously fast-evolving field with numerous players and stakeholders. It will be of utmost importance that the different groups of technologists, users, patients, and actors in the healthcare systems learn to communicate in a language with a common basis. Understanding the requirements of technologies, the potentials of digital application, their interplay, and the combined aim to improve health of patients, would lead to an extraordinary chance to improve health care. Patients' expectations and surgeons' capacities to use digital technologies must be transparent and accepted by both sides. The management of big data needs tremendous care as well as concepts for the ethics in handling data and technologies have to be established while also considering the impact of withholding or delaying benefits thereof. This review focuses on the available technologies such as Apps, wearables, robotics, artificial intelligence, virtual and augmented reality, smart implants, and telemedicine. It will be necessary to closely follow the future developments and carefully pay attention to ethical aspects and transparency.

"Bring Your Own Device"-A New Approach to Wearable Outcome Assessment in Trauma.

Background and Objectives: Outcome data from wearable devices are increasingly used in both research and clinics. Traditionally, a dedicated device is chosen for a given study or clinical application to collect outcome data as soon as the patient is included in a study or undergoes a procedure. The current study introduces a new measurement strategy, whereby patients' own devices are utilized, allowing for both a pre-injury baseline measure and ability to show achievable results. Materials and Methods: Patients with a pre-existing musculoskeletal injury of the upper and lower extremity were included in this exploratory, proof-of-concept study. They were followed up for a minimum of 6 weeks after injury, and their wearable outcome data (from a smartphone and/or a body-worn sensor) were continuously acquired during this period. A descriptive analysis of the screening characteristics and the observed and achievable outcome patterns was performed. Results: A total of 432 patients was continuously screened for the study, and their screening was analyzed. The highest success rate for successful inclusion was in younger patients. Forty-eight patients were included in the analysis. The most prevalent outcome was step count. Three distinctive activity data patterns were observed: patients recovering, patients with slow or no recovery, and patients needing additional measures to determine treatment outcomes. Conclusions: Measuring outcomes in trauma patients with the Bring Your Own Device (BYOD) strategy is feasible. With this approach, patients were able to provide continuous activity data without any dedicated equipment given to them. The measurement technique is especially suited to particular patient groups. Our study's screening log and inclusion characteristics can help inform future studies wishing to employ the BYOD design.

Continuous Shoulder Activity Tracking after Open Reduction and Internal Fixation of Proximal Humerus Fractures.

Postoperative shoulder activity after proximal humerus fracture treatment could influence the outcomes of osteosynthesis and may depend on the rehabilitation protocol. This multi-centric prospective study aimed at evaluating the feasibility of continuous shoulder activity monitoring over the first six postoperative weeks, investigating potential differences between two different rehabilitation protocols. Shoulder activity was assessed with pairs of accelerometer-based trackers during the first six postoperative weeks in thirteen elderly patients having a complex proximal humerus fracture treated with a locking plate. Shoulder angles and elevation events were evaluated over time and compared between the two centers utilizing different standard rehabilitation protocols. The overall mean shoulder angle ranged from 11° to 23°, and the number of daily elevation events was between 547 and 5756. Average angles showed longitudinal change <5° over 31 ± 10 days. The number of events increased by 300% on average. Results of the two clinics exhibited no characteristic differences for shoulder angle, but the number of events increased only for the site utilizing immediate mobilization. In addition to considerable inter-patient variation, not the mean shoulder angle but the number of elevations events increased markedly over time. Differences between the two sites in number of daily events may be associated with the different rehabilitation protocols.

Disability and physical activity in people with chronic disease receiving physiotherapy. A prospective cohort study.

Chronic disease affects patients' disability and participation in activities of daily living. Longitudinal information on disability and physical activity is generally scarce in patients with chronic disease. The current study aimed to investigate if self-reported disability and physical activity changed in patients with chronic disease receiving physiotherapy. Furthermore, the aim was to assess if an improvement in self-reported disability was related to an increase in objectively measured physical activity and if an aggravation in self-reported disability was related to a decrease in physical activity. Seventy patients with either multiple sclerosis, Parkinson's disease, rheumatoid arthritis or stroke receiving free of charge physiotherapy were tested at baseline and 1 year later. Disability was measured with the self-reported modified Ranking Scale-9 Questionnaire and physical activity was objectively measured using tri-axial accelerometry. Neither self-reported disability nor physical activity changed among patients receiving 1 year of free of charge physiotherapy at group level. Furthermore, self-reported change of disability was not expressed with changes in objectively measured physical activity, indicating that the two measures represent two different constructs.

Use of Wearable Technology to Measure Activity in Orthopaedic Trauma Patients: A Systematic Review.

Background: Patient-Reported Outcome Measures (PROMs) are widely used for measurement of functional outcomes after orthopaedic trauma. However, PROMs rely on patient collaboration and suffer from various types of bias. Wearable Activity Monitors (WAMs) are increasingly used to objectify functional assessment. The objectives of this systematic review were to identify and characterise the WAMs technology and metrics currently used for orthopaedic trauma research. Methods: PubMed and Embase biomedical literature search engines were queried. Eligibility criteria included: Human clinical studies published in the English language between 2010 and 2019 involving fracture management and WAMs. Variables collected from each article included: Technology used, vendor/product, WAM body location, metrics measured, measurement time period, year of publication, study geographic location, phase of treatment studied, fractures studied, number of patients studied, sex and age of the study subjects, and study level of evidence. Six investigators reviewed the resulting papers. Descriptive statistics of variables of interest were used to analyse the data. Results: One hundred and thirty-six papers were available for analysis, showing an increasing trend of publications per year. Accelerometry followed by plantar pressure insoles were the most commonly employed technologies. The most common location for WAM placement was insoles, followed by the waist. The most commonly studied fracture type was hip fractures followed by fragility fractures in general, ankle, "lower extremity", and tibial fractures. The rehabilitation phase following surgery was the most commonly studied period. Sleep duration, activity time or step counts were the most commonly reported WAM metrics. A preferred, clinically validated WAM metric was not identified. Conclusions: WAMs have an increasing presence in the orthopaedic trauma literature. The optimal implementation of this technology and its use to understand patients' pre-injury and post-injury functions is currently insufficiently explored and represents an area that will benefit from future study. Systematic review registration number: PROSPERO ID:210344. Supplementary Information: The online version contains supplementary material available at 10.1007/s43465-022-00629-0.

Generalizability of deep learning models for predicting outdoor irregular walking surfaces.

Observations from laboratory-based gait analysis are difficult to extrapolate to real-world environments where gait behavior is modulated in response to complex environmental conditions and surface profiles. Inertial measurement units (IMUs) permit real-world gait analysis; however, automatic detection of surfaces encountered remains largely unexplored. The aims of this study are to quantify for machine learning models the effect of (1) random and subject-wise data splitting and (2) sensor location and count on surface classification performance. Thirty participants walked on nine surface conditions (flat-even, slope-up, slope-down, stairs-up, stairs-down, cobblestone, grass, banked-left, banked-right) wearing IMUs (wrist, trunk, bilateral thighs, bilateral shanks). Data were separated into gait cycles, normalized to 101 samples, and spilt into train and test sets (85 and 15%, respectively). For random splitting, trials were randomly assigned to the train or test set. In subject-wise splitting, all trials from 4 random participants were selected for testing. Linear discriminant analysis extracted features from the IMUs. Features were delivered to a neural network. F1-score evaluated model performance. Models achieved F1 scores of 0.96 and 0.78 using random and subject-wise splitting, respectively. Random splitting performance was mainly invariant to sensor location/count; however, subject-wise splitting showed best performance using lower-limb sensors. In general, stairs and sloped surfaces were easily predicted (F1 > 0.85) while banked surfaces were challenging, especially for subject-wise models (F1 ≈ 0.6). Neural networks can detect surfaces based on subtle changes in walking behavior captured by IMUs. Data splitting approaches and sensor location/count (subject-wise) have a non-negligible effect on model performance.

Wearable technology in orthopedic trauma surgery - An AO trauma survey and review of current and future applications.

The use of wearable sensors to track activity is increasing. Therefore, a survey among AO Trauma members was conducted to provide an overview of their current utilization and determine future needs and directions. A cross sectional expert opinion survey was administered to members of AO Trauma. Respondents were surveyed concerning their experience, subspeciality, current use characteristics, as well as future needs concerning wearable technology. Three hundred and thirty-three survey sets were available for analysis (Response Rate 16.2%). 20.7% of respondents already use wearable technology as part of their clinical treatment. The most prevalent technology was accelerometry combined with smartphones (75.4%) to measure general patient activity. To facilitate the use of wearable technology in the future, the most pressing issues were cost, patient compliance and validity of results. Wearable activity monitors are currently being used in trauma surgery. Surgeons employing these technologies mostly measure simple activity or activity associated parameters. Cost was the greatest perceived barrier to implementation. Further research, especially concerning the interpretation of the outcome values obtained, is required to facilitate wearable activity monitoring as an objective patient outcome measurement tool.

EntropyHub: An open-source toolkit for entropic time series analysis.

An increasing number of studies across many research fields from biomedical engineering to finance are employing measures of entropy to quantify the regularity, variability or randomness of time series and image data. Entropy, as it relates to information theory and dynamical systems theory, can be estimated in many ways, with newly developed methods being continuously introduced in the scientific literature. Despite the growing interest in entropic time series and image analysis, there is a shortage of validated, open-source software tools that enable researchers to apply these methods. To date, packages for performing entropy analysis are often run using graphical user interfaces, lack the necessary supporting documentation, or do not include functions for more advanced entropy methods, such as cross-entropy, multiscale cross-entropy or bidimensional entropy. In light of this, this paper introduces EntropyHub, an open-source toolkit for performing entropic time series analysis in MATLAB, Python and Julia. EntropyHub (version 0.1) provides an extensive range of more than forty functions for estimating cross-, multiscale, multiscale cross-, and bidimensional entropy, each including a number of keyword arguments that allows the user to specify multiple parameters in the entropy calculation. Instructions for installation, descriptions of function syntax, and examples of use are fully detailed in the supporting documentation, available on the EntropyHub website- www.EntropyHub.xyz. Compatible with Windows, Mac and Linux operating systems, EntropyHub is hosted on GitHub, as well as the native package repository for MATLAB, Python and Julia, respectively. The goal of EntropyHub is to integrate the many established entropy methods into one complete resource, providing tools that make advanced entropic time series analysis straightforward and reproducible.

Only limited correlations between patient-reported outcomes and objectively monitored physical activity 10-years after THA.

In orthopaedics, patient reported outcomes (PROMs) are designed to quantify changes in pain and to assess physical function, most often after joint arthroplasty. However, PROMs have some disadvantages, most important is their subjective nature. The aim was to investigate how patient-self-reported-outcomes of general health, disease-specific outcome and physical function, joint-awareness and self-perceived activity- levels are correlated with objectively-measured physical-activity (PA) parameters derived from wearable activity-monitors (AM) in subjects with a hip-arthroplasty. A prospective cohort study was conducted in a group of 32 patients, with a mean follow-up of 10 years after total hip arthroplasty. To assess different domains, the SF-36 (general health), HOOS-PS (pain/functional outcome), FJS-12 (joint awareness) and SQUASH (physical activity) were chosen. Activity-monitoring was performed using a 3-axis accelerometer, gyroscope and magnetometer. No significant correlations between PA-parameters and the FJS-12 and SQUASH were found. The HOOS- PS was significant correlated with BMI, the daily time walking and total-time active and the amount of daily steps. The physical functioning-subscale of the SF-36 was significant negative correlated with BMI and time sitting, but significant positive correlated with time walking, total-time active and the amount of daily steps. Considering the value of PA for maintaining general health, the value of using sensor-based AMs to assess efficacy of treatments in this health related dimension or use it as a tool for patient education, awareness and communication, seems very high.

Development of a dynamic fall risk profile in elderly nursing home residents: A free field gait analysis based study.

Falls in nursing home residents are associated with a significant individual and socioeconomic burden of disease. To trigger and tailor individual intervention programs, solid early detection measures of residents at risk are needed. Aim of this study was thus to test the capability of a free field gait analysis insole to determine its usefulness in determining fall risk. In an observational study gait data of 22 nursing home residents over the age of 75 years was collected over one week with a measuring insole. Clinical scores were performed at baseline (POMA; DGI, TUG). For 6 months before and after the insole measurement, the fall events per resident were recorded. Correlation analysis as well as receiver operating characteristic curve analysis were performed. The average resident age was 88.2 years (range 78-99), 15 had at least one fall event. There was no significant correlation between clinical assessment and fall risk. Moderate correlations between different temporospatial parameters and fall risk were seen. Pressure distribution during gait was markedly changed in fallers. Differences between fallers and non-fallers as well as cut off values for increased fall risk in the ROC analysis could be determined. The introduced measurement protocol suggests that patients at risk for falling can be detected without any additional office visits. Based on the introduced protocol in a limited patient setting, further large scale studies should now determine the effect of prevention measures triggered by gait analysis, the specific risk reduction and the associated personal and socioeconomic advantages.

Finding NEEMO: towards organizing smart digital solutions in orthopaedic trauma surgery.

There are many digital solutions which assist the orthopaedic trauma surgeon. This already broad field is rapidly expanding, making a complete overview of the existing solutions difficult.The AO Foundation has established a task force to address the need for an overview of digital solutions in the field of orthopaedic trauma surgery.Areas of new technology which will help the surgeon gain a greater understanding of these possible solutions are reviewed.We propose a categorization of the current needs in orthopaedic trauma surgery matched with available or potential digital solutions, and provide a narrative overview of this broad topic, including the needs, solutions and basic rules to ensure adequate use in orthopaedic trauma surgery. We seek to make this field more accessible, allowing for technological solutions to be clearly matched to trauma surgeons' needs. Cite this article: EFORT Open Rev 2020;5:408-420. DOI: 10.1302/2058-5241.5.200021.

Patients with hip resurfacing arthroplasty are not physically more active than those with a stemmed total hip.

Background and purpose - Hip resurfacing arthroplasty (HRA) was designed for the highly active patient because of the various theoretical advantages compared with stemmed total hip arthroplasty (THA), but has shown high failure rates. Physical activity (PA) after arthroplasty is frequently determined with the use of questionnaires, which are known for their subjective nature, recall bias, and ceiling effect. These disadvantages are not applicable to physical activity monitoring (AM) using sensors. We compared objectively measured PA at long-term follow-up in a matched cohort of HRA and stemmed THA subjects.Patients and methods - We compared 2 groups of 16 patients (12 males) in each group, one having received unilateral HRA (median age 56 years at surgery) and a matched group having received unilateral stemmed THA with a small diameter femoral head (28 mm) on conventional polyethylene (median age 60 years at surgery) with osteoarthritis as indication for surgery, 10 years after surgery. Groups were matched by sex, age at surgery, and BMI. The daily habitual PA was measured over 4 consecutive days in daily living using a 3-axis accelerometer, gyroscope, and magnetometer. Both quantitative parameters (time standing, sitting, walking, number of steps, and sit-stand transfers) and qualitative parameters (walking cadence) were determined.Results - The AM was worn for a median 13 (11-16) hours per day. The median daily step count was 5,546 (2,274-9,966) for the HRA group and 4,583 (1,567-11,749) for the stemmed THA-group with 39 (21-74) versus 37 (24-62) daily sit-stand transfers respectively. The other PA parameters were also similar in both groups.Interpretation - We found similar median PA levels and also identical ranges. While short-term effects may exist, ageing and related behavioral adaptations or other effects seem to render the theoretical activity benefits from HRA irrelevant at longer follow-up.

Self-reported systemic complaints in patients with metal-on-metal hip arthroplasty.

INTRODUCTION: An increase in blood serum metal ion levels is seen after implantation of all metal-on-metal (MoM) hip prosthesis. Systemic complaints contributed to raised cobalt ion concentrations in patients with MoM arthroplasty may lead to a variety of symptoms. The aim of this study is to investigate self-reported systemic complaints in association with cobalt ion concentrations in patients with any type of MoM hip prosthesis. METHODS: A cohort study was conducted. Patients with both unilateral and bilateral, resurfacing and large head metal on metal total hip arthroplasties (LHMoM THA) were included. Cobalt ion concentrations were measured by inductively coupled plasma mass spectrometry. Based on the known cobalt toxicity symptoms of case-reports and toxicology reports a new non-validated questionnaire was developed. Analysis was performed on two groups; a low cobalt ion concentration group and a high cobalt ion concentration group. RESULTS: A total of 62 patients were included with a mean age at surgery of 60.8 ± 9.3 years and a mean follow up of 6.3 ± 1.4 years. Mean cobalt ion concentrations were 104 ± 141 nmol/L (9-833). Based on the different thresholds (120-170 or 220 nmol/L) the low cobalt ion concentration group consisted of 44 (71%), 51 (82%) or 55 (89%) subjects respectively. In the 120 nmol/L and 170 nmol/L thresholds a significant difference in age was found. The composite score for OVS increased from 54% to 57%-68% with rising threshold value, a hint at the correlation between ion concentration and symptom prevalence. DISCUSSION: Ocular-vestibular symptoms were more common in high cobalt ion concentration groups for the three threshold levels tested and with increasing prevalence for higher threshold values. With regards to proactively inquired, self-reported symptoms the threshold where effects may be present could be lower than values currently applied in clinical follow-up.

Quality, but not quantity of physical activity is associated with metal ion concentrations in unilateral hip resurfacing.

Little is known about the influence of physical activity (PA) on metal ion concentrations in subjects with metal-on-metal hip arthroplasty. Implant wear is thought to be a function of use and thus of patient activity levels. It is hypothesized that daily habitual PA of patients with hip resurfacing arthroplasty (HRA) is associated with metal ion concentrations. Therefore a study was conducted in patients with a unilateral HRA at 10-years follow-up. Blood metal ion concentrations were determined. An acceleration-based activity monitor was used to measure PA in daily life. The cohort consisted of 12 males (75%) and 4 females (25%) with a median age at surgery of 55.5 ± 9.7 years [43.0-67.9] and a median follow-up of 9.9 ± 1.0 years [9.1-10.9]. The median cobalt and chromium ion concentrations were 25 ± 13 and 38 ± 28 nmol/L. A significant association between sit-stand transfers and high-intensity peaks with cobalt ion concentrations were found. Regarding PA and metal ion concentrations as a proxy of wear in HRA, specific activities like transfers or qualitative aspects of activity behavior like intensity, seem to matter more than the quantity of low-intensity activities like walking or cycling. This suggests that patients may safely engage in such activities to achieve important general health benefits and quality of life.

The association of leg length and offset reconstruction after total hip arthroplasty with clinical outcomes.

BACKGROUND: Restoring native hip anatomy and biomechanics is important to create a well-functioning hip arthroplasty. This study investigated the association of hip offset and leg length after hip arthroplasty with clinical outcomes, including patient reported outcome measures, the Trendelenburg Test and gait analysis. METHODS: In 77 patients undergoing primary hip arthroplasty for osteoarthritis (age mean = 65 SD = 11 years; BMI mean = 27 SD = 5 kg/m2), hip offset and leg length discrepancy were measured on anteroposterior radiographs. The Western Ontario & McMaster Universities Osteoarthritis Index, the Trendelenburg Test and gait were assessed preoperatively, and at 3 and 12 months postoperatively. An inertial measurement unit was used to derive biomechanical parameters, including spatiotemporal gait parameters and tilt angles of the pelvis. Relationships between radiographic and functional outcomes were investigated, and subgroups of patients with >15% decreased and increased femoral offset were analysed separately. FINDINGS: Patient-reported function scores and clinical tests demonstrated a few significant, weak correlations with radiographic outcomes (Spearman's ρ range = 0.26-0.32; p < 0.05). Undercorrection of femoral offset was associated with lower patient-reported function scores and with more step irregularity as well as step asymmetry during gait. Postoperative leg length inequality was associated with increased frontal plane tilt angle of the pelvis during the Trendelenburg Test and increased sagittal plane motion of the pelvis during gait. Femoral offset subgroups demonstrated no significant differences for patient-reported function scores and outcomes of the Trendelenburg Test and gait analysis. INTERPRETATION: Reduced hip offset and leg length discrepancy following hip arthroplasty seem to be marginally associated with worse clinical outcomes.

Assessing Gait in Parkinson's Disease Using Wearable Motion Sensors: A Systematic Review.

: Parkinson's disease (PD) is a progressive neurodegenerative disorder. Gait impairments are common among people with PD. Wearable sensor systems can be used for gait analysis by providing spatio-temporal parameters useful to investigate the progression of gait problems in Parkinson disease. However, various methods and tools with very high variability have been developed. The aim of this study is to review published articles of the last 10 years (from 2008 to 2018) concerning the application of wearable sensors to assess spatio-temporal parameters of gait in patients with PD. We focus on inertial sensors used for gait analysis in the clinical environment (i.e., we do not cover the use of inertial sensors to monitor walking or general activities at home, in unsupervised environments). Materials and Methods: Relevant articles were searched in the Medline database using Pubmed. Results and Discussion: Two hundred ninety-four articles were initially identified while searching the scientific literature regarding this topic. Thirty-six articles were selected and included in this review. Conclusion: Wearable motion sensors are useful, non-invasive, low-cost, and objective tools that are being extensively used to perform gait analysis on PD patients. Being able to diagnose and monitor the progression of PD patients makes wearable sensors very useful to evaluate clinical efficacy before and after therapeutic interventions. However, there is no uniformity in the use of wearable sensors in terms of: number of sensors, positioning, chosen parameters, and other characteristics. Future research should focus on standardizing the measurement setup and selecting which spatio-temporal parameters are the most informative to analyze gait in PD. These parameters should be provided as standard assessments in all studies to increase replicability and comparability of results.