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Reumann MK, Hillrichs H, Menger MM, Herath SC, Rollmann MFR, Stuby F, Histing T, Braun BJ. [Nonunions after intertrochanteric and subtrochanteric femoral fractures]. UNFALLCHIRURGIE (HEIDELBERG, GERMANY) 2024; 127:356-363. [PMID: 38224360 DOI: 10.1007/s00113-023-01402-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/05/2023] [Indexed: 01/16/2024]
Abstract
INTRODUCTION The overall frequency of proximal femoral fractures means that we are repeatedly confronted with failed healing and implant failure, despite a relatively low nonunion rate especially in intertrochanteric fractures (< 5%). The aim of this paper is to present our approach to treating these nonunions of the proximal femur and discuss the treatment results. MATERIAL AND METHODS Between 2009 and 2023, patients with nonunion of the proximal femur were retrospectively identified and analyzed. Age, gender, time to revision, the Weber-Cech classification of pseudarthrosis and radiographic imaging before and after revision were analyzed. RESULTS A total of 66 patients were analyzed. The mean age was 58 years (range 25-88 years). The overall healing rate was 88% with a mean consolidation time of 8 months (range 2-29 months). The main osteosynthesis procedures were plate osteosynthesis (n = 45, of which 44 were blade plates), and nail replacement (n = 12). Other procedures included augmentative plate osteosyntheses (n = 4), isolated cancellous bone graft (n = 2), nail dynamization (n = 2), and the use of a dynamic hip screw (n = 1). DISCUSSION The analysis of our treatment data as well as the current literature, revealed a trend towards intramedullary revision procedures. Implants that can be used to correct the CCD angle, such as the blade plate, remain a predictable option to achieve correction, especially in nonunions with an increased degree of varus. Particularly in the subtrochanteric region, fractures can also be treated in a targeted manner by a combination of mechanical and biological methods with a reamed nail change to a larger caliber implant.
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Affiliation(s)
- Marie K Reumann
- Klinik für Unfall- und Wiederherstellungschirurgie, BG Klinik Tübingen, Eberhard Karls Universität Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Deutschland
| | - Hauke Hillrichs
- Klinik für Unfallchirurgie, Orthopädie und Allgemeinchirurgie, BG Unfallklinik Murnau, Murnau, Deutschland
| | - Maximilian M Menger
- Klinik für Unfall- und Wiederherstellungschirurgie, BG Klinik Tübingen, Eberhard Karls Universität Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Deutschland
| | - Steven C Herath
- Klinik für Unfall- und Wiederherstellungschirurgie, BG Klinik Tübingen, Eberhard Karls Universität Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Deutschland
| | - Mika F R Rollmann
- Klinik für Unfall- und Wiederherstellungschirurgie, BG Klinik Tübingen, Eberhard Karls Universität Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Deutschland
| | - Fabian Stuby
- Klinik für Unfallchirurgie, Orthopädie und Allgemeinchirurgie, BG Unfallklinik Murnau, Murnau, Deutschland
| | - Tina Histing
- Klinik für Unfall- und Wiederherstellungschirurgie, BG Klinik Tübingen, Eberhard Karls Universität Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Deutschland
| | - Benedikt J Braun
- Klinik für Unfall- und Wiederherstellungschirurgie, BG Klinik Tübingen, Eberhard Karls Universität Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Deutschland.
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Nayak GS, Roland M, Wiese B, Hort N, Diebels S. Influence of implant base material on secondary bone healing: an in silico study. Comput Methods Biomech Biomed Engin 2024:1-9. [PMID: 38613482 DOI: 10.1080/10255842.2024.2338121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/28/2024] [Indexed: 04/15/2024]
Abstract
The implant material at the fracture site influences fracture healing not only from biological perspective but also from mechanical perspective. Biodegradable implants such as magnesium (Mg) based alloys have shown faster secondary bone healing properties as compared to bioinert implants such as titanium (Ti). The general reasoning behind this is the benefit of Mg from biocompatibility perspectives. We studied the effect of Ti and Mg as base materials for implants from mechanical perspectives, where we focused on the displacements at the fracture site of the tibia and their influence on the stimulus for bone healing. We found out that in comparison to Ti, Mg implants have minimal stress shielding problem, only which led to better mechanical stimulus at the fracture site.
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Affiliation(s)
| | - Michael Roland
- Chair of Applied Mechanics, Saarland University, Saarbrücken, Germany
| | - Björn Wiese
- Institute of Metallic Biomaterials, Geesthacht, Germany
| | - Norbert Hort
- Institute of Metallic Biomaterials, Geesthacht, Germany
- Leuphana University Lüneburg, Institute of Product and Process Innovation, Lüneburg, Germany
| | - Stefan Diebels
- Chair of Applied Mechanics, Saarland University, Saarbrücken, Germany
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Wickert K, Roland M, Andres A, Diebels S, Ganse B, Kerner D, Frenzel F, Tschernig T, Ernst M, Windolf M, Müller M, Pohlemann T, Orth M. Experimental and virtual testing of bone-implant systems equipped with the AO Fracture Monitor with regard to interfragmentary movement. Front Bioeng Biotechnol 2024; 12:1370837. [PMID: 38524192 PMCID: PMC10958423 DOI: 10.3389/fbioe.2024.1370837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 02/21/2024] [Indexed: 03/26/2024] Open
Abstract
Introduction: The management of fractured bones is a key domain within orthopedic trauma surgery, with the prevention of delayed healing and non-unions forming a core challenge. This study evaluates the efficacy of the AO Fracture Monitor in conjunction with biomechanical simulations to better understand the local mechanics of fracture gaps, which is crucial for comprehending mechanotransduction, a key factor in bone healing. Through a series of experiments and corresponding simulations, the study tests four hypotheses to determine the relationship between physical measurements and the predictive power of biomechanical models. Methods: Employing the AO Fracture Monitor and Digital Image Correlation techniques, the study demonstrates a significant correlation between the surface strain of implants and interfragmentary movements. This provides a foundation for utilizing one-dimensional AO Fracture Monitor measurements to predict three-dimensional fracture behavior, thereby linking mechanical loading with fracture gap dynamics. Moreover, the research establishes that finite element simulations of bone-implant systems can be effectively validated using experimental data, underpinning the accuracy of simulations in replicating physical behaviors. Results and Discussion: The findings endorse the combined use of monitoring technologies and simulations to infer the local mechanical conditions at the fracture site, offering a potential leap in personalized therapy for bone healing. Clinically, this approach can enhance treatment outcomes by refining the assessment precision in trauma trials, fostering the early detection of healing disturbances, and guiding improvements in future implant design. Ultimately, this study paves the way for more sophisticated patient monitoring and tailored interventions, promising to elevate the standard of care in orthopedic trauma surgery.
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Affiliation(s)
- Kerstin Wickert
- Applied Mechanics, Saarland University, Saarbrücken, Germany
| | - Michael Roland
- Applied Mechanics, Saarland University, Saarbrücken, Germany
| | | | - Stefan Diebels
- Applied Mechanics, Saarland University, Saarbrücken, Germany
| | - Bergita Ganse
- Werner Siemens Endowed Chair of Innovative Implant Development (Fracture Healing), Saarland University, Homburg, Germany
| | - Dorothea Kerner
- Clinic of Diagnostic and Interventional Radiology, Saarland University Hospital, Homburg, Germany
| | - Felix Frenzel
- Clinic of Diagnostic and Interventional Radiology, Saarland University Hospital, Homburg, Germany
| | - Thomas Tschernig
- Institute of Anatomy and Cell Biology, Saarland University, Homburg, Germany
| | - Manuela Ernst
- AO Research Institute Davos (ARI), Davos, Switzerland
| | | | - Max Müller
- Department of Trauma, Hand and Reconstruction Surgery, Saarland University Hospital, Homburg, Germany
| | - Tim Pohlemann
- Department of Trauma, Hand and Reconstruction Surgery, Saarland University Hospital, Homburg, Germany
| | - Marcel Orth
- Department of Trauma, Hand and Reconstruction Surgery, Saarland University Hospital, Homburg, Germany
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Roland M, Diebels S, Orth M, Pohlemann T, Bouillon B, Tjardes T. Reappraisal of clinical trauma trials: the critical impact of anthropometric parameters on fracture gap micro-mechanics-observations from a simulation-based study. Sci Rep 2023; 13:20450. [PMID: 37993727 PMCID: PMC10665421 DOI: 10.1038/s41598-023-47910-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 11/20/2023] [Indexed: 11/24/2023] Open
Abstract
The evidence base of surgical fracture care is extremely sparse with only few sound RCTs available. It is hypothesized that anthropometric factors relevantly influence mechanical conditions in the fracture gap, thereby interfering with the mechanoinduction of fracture healing. Development of a finite element model of a tibia fracture, which is the basis of an in silico population (n = 300) by systematic variation of anthropometric parameters. Simulations of the stance phase and correlation between anthropometric parameters and the mechanical stimulus in the fracture gap. Analysis of the influence of anthropometric parameters on statistical dispersion between in silico trial cohorts with respect to the probability to generate two, with respect to anthropometric parameters statistically different trial cohorts, given the same power assumptions. The mechanical impact in the fracture gap correlates with anthropometric parameters; confirming the hypothesis that anthropometric factors are a relevant entity. On a cohort level simulation of a fracture trial showed that given an adequate power the principle of randomization successfully levels out the impact of anthropometric factors. From a clinical perspective these group sizes are difficult to achieve, especially when considering that the trials takes advantage of a "laboratory approach ", i.e. the fracture type has not been varied, such that in real world trials the cohort size have to be even larger to level out the different configurations of fractures gaps. Anthropometric parameters have a significant impact on the fracture gap mechanics. The cohort sizes necessary to level out this effect are difficult or unrealistic to achieve in RCTs, which is the reason for sparse evidence in orthotrauma. New approaches to clinical trials taking advantage of modelling and simulation techniques need to be developed and explored.
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Affiliation(s)
- Michael Roland
- Chair of Applied Mechanics, Saarland University, Campus A4 2, 1. OG, 66123, Saarbrücken, Germany.
| | - Stefan Diebels
- Chair of Applied Mechanics, Saarland University, Campus A4 2, 1. OG, 66123, Saarbrücken, Germany
| | - Marcel Orth
- Department of Trauma, Hand and Reconstructive Surgery, Saarland University, Kirrberger Strasse 100, 66421, Homburg, Germany
| | - Tim Pohlemann
- Department of Trauma, Hand and Reconstructive Surgery, Saarland University, Kirrberger Strasse 100, 66421, Homburg, Germany
| | - Bertil Bouillon
- Chair for Orthopedic Surgery, Trauma Surgery and Sportstraumatology, Department of Orthopedic Surgery, Trauma Surgery and Sportstraumatology, Cologne Merheim Medical Center, University Witten/Herdecke, Ostmerheimerstrasse 200, 51109, Cologne, Germany
| | - Thorsten Tjardes
- Chair for Orthopedic Surgery, Trauma Surgery and Sportstraumatology, Department of Orthopedic Surgery, Trauma Surgery and Sportstraumatology, Cologne Merheim Medical Center, University Witten/Herdecke, Ostmerheimerstrasse 200, 51109, Cologne, Germany
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Orth M, Ganse B, Andres A, Wickert K, Warmerdam E, Müller M, Diebels S, Roland M, Pohlemann T. Simulation-based prediction of bone healing and treatment recommendations for lower leg fractures: Effects of motion, weight-bearing and fibular mechanics. Front Bioeng Biotechnol 2023; 11:1067845. [PMID: 36890916 PMCID: PMC9986461 DOI: 10.3389/fbioe.2023.1067845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 02/10/2023] [Indexed: 02/22/2023] Open
Abstract
Despite recent experimental and clinical progress in the treatment of tibial and fibular fractures, in clinical practice rates of delayed bone healing and non-union remain high. The aim of this study was to simulate and compare different mechanical conditions after lower leg fractures to assess the effects of postoperative motion, weight-bearing restrictions and fibular mechanics on the strain distribution and the clinical course. Based on the computed tomography (CT) data set of a real clinical case with a distal diaphyseal tibial fracture, a proximal and a distal fibular fracture, finite element simulations were run. Early postoperative motion data, recorded via an inertial measuring unit system and pressure insoles were recorded and processed to study strain. The simulations were used to compute interfragmentary strain and the von Mises stress distribution of the intramedullary nail for different treatments of the fibula, as well as several walking velocities (1.0 km/h; 1.5 km/h; 2.0 km/h) and levels of weight-bearing restriction. The simulation of the real treatment was compared to the clinical course. The results show that a high postoperative walking speed was associated with higher loads in the fracture zone. In addition, a larger number of areas in the fracture gap with forces that exceeded beneficial mechanical properties longer was observed. Moreover, the simulations showed that surgical treatment of the distal fibular fracture had an impact on the healing course, whereas the proximal fibular fracture barely mattered. Weight-bearing restrictions were beneficial in reducing excessive mechanical conditions, while it is known that it is difficult for patients to adhere to partial weight-bearing recommendations. In conclusion, it is likely that motion, weight bearing and fibular mechanics influence the biomechanical milieu in the fracture gap. Simulations may improve decisions on the choice and location of surgical implants, as well as give recommendations for loading in the postoperative course of the individual patient.
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Affiliation(s)
- Marcel Orth
- Department of Trauma, Hand and Reconstructive Surgery, Saarland University, Saarbrücken, Germany
| | - Bergita Ganse
- Department of Trauma, Hand and Reconstructive Surgery, Saarland University, Saarbrücken, Germany.,Werner Siemens Endowed Chair of Innovative Implant Development (Fracture Healing), Saarland University, Saarbrücken, Germany
| | | | - Kerstin Wickert
- Chair of Applied Mechanics, Saarland University, Saarbrücken, Germany
| | - Elke Warmerdam
- Werner Siemens Endowed Chair of Innovative Implant Development (Fracture Healing), Saarland University, Saarbrücken, Germany
| | - Max Müller
- Department of Trauma, Hand and Reconstructive Surgery, Saarland University, Saarbrücken, Germany
| | - Stefan Diebels
- Chair of Applied Mechanics, Saarland University, Saarbrücken, Germany
| | - Michael Roland
- Chair of Applied Mechanics, Saarland University, Saarbrücken, Germany
| | - Tim Pohlemann
- Department of Trauma, Hand and Reconstructive Surgery, Saarland University, Saarbrücken, Germany
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Histing T, Braun BJ. [Pseudarthrosis-new techniques and trends]. UNFALLCHIRURGIE (HEIDELBERG, GERMANY) 2022; 125:587-588. [PMID: 35922527 DOI: 10.1007/s00113-022-01203-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/02/2022] [Indexed: 02/07/2023]
Affiliation(s)
- Tina Histing
- Klinik für Unfall- und Wiederherstellungschirurgie an der Eberhard Karls Universität Tübingen, BG Klinik Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Deutschland.
| | - Benedikt J Braun
- Klinik für Unfall- und Wiederherstellungschirurgie an der Eberhard Karls Universität Tübingen, BG Klinik Tübingen, Schnarrenbergstr. 95, 72076, Tübingen, Deutschland.
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7
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Braun BJ, Histing T, Herath SC, Rollmann MFR, Reumann M, Menger MM, Springer F, Andres A, Diebels S, Roland M. [Movement analysis and musculoskeletal simulation in non-union treatment-Experiences and first clinical results]. UNFALLCHIRURGIE (HEIDELBERG, GERMANY) 2022; 125:619-627. [PMID: 35737004 DOI: 10.1007/s00113-022-01208-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND The mechanical boundary conditions of the non-union and osteosynthetic construct are a key determinant of fracture healing after revision surgery. Aim of this study was to introduce a movement analysis and simulation workflow to determine the mechanical conditions during non-union healing in vivo. MATERIAL AND METHODS On an individual case basis after non-union revision surgery we performed an accelerometry-based movement analysis. The results were then used as input for a musculoskeletal simulation of the non-union, osteosynthetic construct as well as adjacent joints mechanical boundary conditions. RESULTS A total of 13 patients were analyzed with our new workflow. The introduced protocol allows an in vivo determination of the mechanical boundary conditions. On clinical follow-up all patients showed radiographic consolidation of the non-union. CONCLUSION The introduced workflow allows a clinically applicable determination of the mechanical boundary conditions of fracture and non-union healing. Further studies can now determine the effect of the introduced technique for mechanically optimized postoperative aftercare regimes as well as biomechanically adapted surgical treatment.
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Affiliation(s)
- Benedikt J Braun
- Klinik für Unfall- und Wiederherstellungschirurgie, Eberhard Karls Universität Tübingen, BG Klinik Tübingen, Schnarrenbergstr. 95, 72072, Tübingen, Deutschland.
| | - Tina Histing
- Klinik für Unfall- und Wiederherstellungschirurgie, Eberhard Karls Universität Tübingen, BG Klinik Tübingen, Schnarrenbergstr. 95, 72072, Tübingen, Deutschland
| | - Steven C Herath
- Klinik für Unfall- und Wiederherstellungschirurgie, Eberhard Karls Universität Tübingen, BG Klinik Tübingen, Schnarrenbergstr. 95, 72072, Tübingen, Deutschland
| | - Mika F R Rollmann
- Klinik für Unfall- und Wiederherstellungschirurgie, Eberhard Karls Universität Tübingen, BG Klinik Tübingen, Schnarrenbergstr. 95, 72072, Tübingen, Deutschland
| | - Marie Reumann
- Klinik für Unfall- und Wiederherstellungschirurgie, Eberhard Karls Universität Tübingen, BG Klinik Tübingen, Schnarrenbergstr. 95, 72072, Tübingen, Deutschland
| | - Maximilian M Menger
- Klinik für Unfall- und Wiederherstellungschirurgie, Eberhard Karls Universität Tübingen, BG Klinik Tübingen, Schnarrenbergstr. 95, 72072, Tübingen, Deutschland
| | - Fabian Springer
- Klinik für Diagnostische und Interventionelle Radiologie, Eberhard Karls Universität Tübingen, Tübingen, Deutschland
| | - Annchristin Andres
- Lehrstuhl für Technische Mechanik, Universität des Saarlandes, Saarbrücken, Deutschland
| | - Stefan Diebels
- Lehrstuhl für Technische Mechanik, Universität des Saarlandes, Saarbrücken, Deutschland
| | - Michael Roland
- Lehrstuhl für Technische Mechanik, Universität des Saarlandes, Saarbrücken, Deutschland
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Ganse B, Orth M, Roland M, Diebels S, Motzki P, Seelecke S, Kirsch SM, Welsch F, Andres A, Wickert K, Braun BJ, Pohlemann T. Concepts and clinical aspects of active implants for the treatment of bone fractures. Acta Biomater 2022; 146:1-9. [PMID: 35537678 DOI: 10.1016/j.actbio.2022.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/24/2022] [Accepted: 05/02/2022] [Indexed: 12/17/2022]
Abstract
Nonunion is a complication of long bone fractures that leads to disability, morbidity and high costs. Early detection is difficult and treatment through external stimulation and revision surgery is often a lengthy process. Therefore, alternative diagnostic and therapeutic options are currently being explored, including the use of external and internal sensors. Apart from monitoring fracture stiffness and displacement directly at the fracture site, it would be desirable if an implant could also vary its stiffness and apply an intervention to promote healing, if needed. This could be achieved either by a predetermined protocol, by remote control, or even by processing data and triggering the intervention itself (self-regulated 'intelligent' or 'smart' implant). So-called active or smart materials like shape memory alloys (SMA) have opened up opportunities to build active implants. For example, implants could stimulate fracture healing by active shortening and lengthening via SMA actuator wires; by emitting pulses, waves, or electromagnetic fields. However, it remains undefined which modes of application, forces, frequencies, force directions, time durations and periods, or other stimuli such implants should ideally deliver for the best result. The present paper reviews the literature on active implants and interventions for nonunion, discusses possible mechanisms of active implants and points out where further research and development are needed to build an active implant that applies the most ideal intervention. STATEMENT OF SIGNIFICANCE: Early detection of delays during fracture healing and timely intervention are difficult due to limitations of the current diagnostic strategies. New diagnostic options are under evaluation, including the use of external and internal sensors. In addition, it would be desirable if an implant could actively facilitate healing ('Intelligent' or 'smart' implant). Implants could stimulate fracture healing via active shortening and lengthening; by emitting pulses, waves, or electromagnetic fields. No such implants exist to date, but new composite materials and alloys have opened up opportunities to build such active implants, and several groups across the globe are currently working on their development. The present paper is the first review on this topic to date.
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Braun BJ, Grimm B, Hanflik AM, Richter PH, Sivananthan S, Yarboro SR, Marmor MT. Wearable technology in orthopedic trauma surgery - An AO trauma survey and review of current and future applications. Injury 2022; 53:1961-1965. [PMID: 35307166 DOI: 10.1016/j.injury.2022.03.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/11/2022] [Accepted: 03/12/2022] [Indexed: 02/02/2023]
Abstract
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.
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Affiliation(s)
- Benedikt J Braun
- University Hospital Tuebingen on Behalf of the Eberhard-Karls-University Tuebingen, BG Hospital, Schnarrenbergstr. 95, Tuebingen 72076, Germany.
| | - Bernd Grimm
- Human Motion, Orthopaedics, Sports Medicine and Digital Methods Group, Luxembourg, Institute of Health, Transversal activities, Luxembourg, Luxembourg
| | - Andrew M Hanflik
- Department of Orthopaedic Surgery, Southern California Permanente Medical Group, Downey Medical Center, Kaiser Permanente Downey, CA, United States
| | - Peter H Richter
- Department of Orthopaedic Surgery, University of Ulm, Ulm, Germany
| | | | | | - Meir T Marmor
- Orthopaedic Trauma Institute (OTI), San Francisco General Hospital, University of California, San Francisco, San Francisco, CA, United States
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