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Prof. Dr., PhD Annegret Mündermann

Department of Biomedical Engineering
Profiles & Affiliations

Projects & Collaborations

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A randomized controlled trial on the effectiveness of remote app assisted physiotherapy in patients with non-specific low back pain

Research Project  | 4 Project Members

In Switzerland, 1.5 million people suffer from low back pain (LBP), which is often the cause of disability [1]. Non-specific LBP is a major cause of high healthcare costs in developed countries and often leads to early retirement [2]. The development of musculoskeletal assessment through remote app-assisted therapeutic home training may be useful for individuals with non-specific LBP, providing initial support for its implementation in primary care in the patient's home [3]. App-supported therapeutic solutions allow healthcare professionals to prescribe and monitor rehabilitation programs remotely. These innovative solutions have the potential to reduce healthcare costs and provide clinical outcomes comparable or even better than conventional physiotherapy (PT), especially for patients in remote areas [4]. Akina Cloud, a digital health application developed by an ETH spin-off to support therapeutic exercises in people with musculoskeletal disorders, is the first remote app-assisted therapeutic home training solution available in Switzerland. It provides patients with exercise and educational content and facilitates communication between patients and therapists via the application. The aim of this study is to show the efficacy of the remote app-assisted physiotherapy through Akina Cloud in patients with non-specific LBP. 

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CADENCE - Clinical Biomechanics and Ergonomics Engineering Equipment

Research Project  | 5 Project Members

In December 2021, the new research unit ‘Clinical Biomechanics and Ergonomics Engineering’ (CADENCE) was formed at Department of Biomedical Engineering (DBE) at the University of Basel (https://dbe.unibas.ch/en/research/biomechanics-and-biomaterials/cadence/) comprising the research groups ‘Functional Biomechanics’, ‘Robot-assisted Theragnostics’, ‘Paediatric Orthopaedic Biomechanics and Musculoskeletal Modelling’, and ‘Spine Biomechanics’. CADENCE facilitates innovative and groundbreaking interdisciplinary research in biomedical engineering and biomechanics and serves as teaching facility for courses on diagnostic and therapeutic technologies within the new Master of Science program and the PhD programs at the DBE. The R`Equip grant supports CADENCE in the purchase of a range of state-of-the-art sensor technologies and the world’s first 3D gait rehabilitation robot ‘The FLOAT’. This investment is critical for the unique and internationally leading role of the research groups in the research and innovation ecosystem in the Basel region.

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HamRepair: Clinical and functional outcomes at least 2 years after hamstring muscle repair – a pilot study

Research Project  | 5 Project Members

Several studies from the past 10 years have shown a significant subjective benefit after a surgical treatment in comparison to a conservative treatment of a proximal hamstring rupture.4-7 There is also a strong evidence of about 10% decrease in muscle strength in comparison to the non operated site4,13. Similar muscle strength between the operated and contralateral side was observed up to 10 years after repair.14 However, to the best of our knowledge there is a lack of evidence in possible development of biomechanical and functional limb asymmetries including muscle activity caused by these postoperative muscular imbalances. Our project will therefore concentrate on the biomechanics of gait and daily activity tasks and investigate differences between the operated and contralateral limb. Primarily we will quantify potential muscular deficits between limbs and compare these to the findings of the gait pattern. If proven right and limping does occur, it can, on the long run, cause earlier onset of skeletal degeneration and osteoarthritis.8-10 As the mean age of the patients examined in the studies with hamstring rupture is usually about 40 to 45 years6 and the average life expectancy is above 80 years11, potential muscular deficits may manifest as pathological gait that may predispose these patients to premature and potentially more severe degenerative processes. For instance, it is possible that the risk of hip osteoarthritis and/or lower back or iliosacral joint osteoarthritis is higher in patients after a hamstring rupture. Therefore, improving the understanding of biomechanical and functional outcome after hamstring repair is critical, and potential deficits may be prevented with additional physiotherapy addressing muscular imbalances. In the proposed pilot study, we will compile outcome data on the outcome of a new, intraoperative lateral positioning of the anchors on the tuber ischiadicum, as was used in all of our patients, in comparison to regular anatomical anchoring direct on top of the tuber ischiadicum.12 Based on our clinical experience many patients describe a local discomfort in seated position with traditional anchor positioning, and a lateral positioning could potentially prevent this complaint as the lateral area of os ischi is not exposed to the pressure when seated. With this pilot study we will not only provide new insights into the postoperative function of the hamstrings with corresponding gait pattern for the current patients, but also possibly prevent the discomfort while sitting by changing anchor placement in future patients. Further, the data obtained in this study will facilitate proper sample size calculations for future clinical trials.

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Klinische und funktionelle Resultate 2 Jahre nach VKB Naht mit Internal Brace Augmentation im Vergleich zur VKB Rekonstruktion unter Berücksichtigung sozioökonomischer Aspekte und Rückkehr zur Arbeitsfähigkeit

Research Project  | 4 Project Members

Der Stellenwert des Erhaltes des vorderen Kreuzbandes nach VKB Ruptur wird kontrovers diskutiert - insbesondere spielt dabei das Internal Bracing, also die Ligament Augmentation zusätzlich zur Naht, eine zentrale Rolle. In unserer Klinik haben wir mittlerweile über 60 Patienten mit dieser Technik operiert mit sehr guten klinischen Resultaten. Allerdings bleibt die Literatur bis dato objektive funktionelle und biomechanische Resultate dieses Verfahrens schuldig, die jedoch auch prognostisch, v.a. im Hinblick auf die Entstehung einer sekundären Kniegelenksarthrose, höchst relevant sind. Basierend auf den sehr erfreulichen klinischen Resultaten ist das Ziel der vorliegenden Studie daher, erstmalig eine umfassende objektive und quantitative klinische und funktionelle Untersuchung bei Patienten nach VKB Naht in direktem Vergleich mit der Goldstandard Technik, der VKB Rekonstruktion, und einem Kniegesunden Kontrollkollektiv durchzuführen. Die hier durchgeführten Tests werden somit wichtige neue Erkenntnisse liefern über den Funktionszustand sowie die Mechanik der Kniegelenke nach Internal Bracing und ob diese Patienten im direkten Vergleich zur Rekonstruktion ein geringeres Muskelkraftdefizit und eine verbesserte Gangfunktion aufgrund der erhaltenen Anatomie des genähten VKBs aufweisen, die als protektive Faktoren der Arthroseentstehung anzusehen sind. Die Studie bildet somit die Grundlage für weitere Untersuchungen zur Optimierung der Behandlung künftiger Patienten (inklusive einer optimierten Patientenselektion) und wird wichtige Erkenntnisse für die Optimierung der Rehabilitation nach primärer VKB Naht sowie nach Rekonstruktion liefern mit Relevanz im Kontext der Gonarthrose.

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Clinical and functional outcomes 2 years after ACL repair and InternalBraceTM ligament augmentation in comparison with ACL reconstruction and healthy controls

PhD Project  | 5 Project Members

For patients with proximal anterior cruciate ligament (ACL) tears, primary ACL repair

with additional suture tape augmentation (ACL-IB, InternalBraceTM) has been introduced as an

alternative procedure to ACL reconstruction (ACL-R). The advantages of ACL repair over

ACL-R include preservation of the native ligament and lack of tendon harvesting. However,

evidence on the outcome of ACL-IB has only started to emerge. First studies on ACL-IB after

proximal ACL tears have reported promising results in patient-reported outcome measures and

in clinical knee examination comparable to ACL-R. Although ACL repair is thought to restore

proprioception and natural knee mechanics, evidence for such functional and biomechanical

benefits in patients after ACL-IB is limited or absent in the literature. In addition, there is insufficient

information on the extent of potential limitations after ACL-IB compared to healthy

subjects. Knowledge of these aspects is essential to understand the role of ACL-IB alongside

ACL-R and to establish this procedure as an alternative treatment option for proximal ACL

tears in orthopaedic surgery.

The aim of this thesis was to provide evidence on clinical and functional-biomechanical

outcomes 2 years after ACL-IB, and to directly compare these outcomes to sex- and agematched

patients 2 years after ACL-R using hamstring tendon autograft, and sex- and agematched

healthy controls. For this purpose, we assessed our participants in a comprehensive

test protocol, including patient-reported outcome measures and a clinical leg examination (clinical

outcomes); as well as functional tests of leg performance in knee muscle strength, knee

proprioception, dynamic postural control, and single-leg hops; as well as analyses of leg joint

kinematics and kinetics and leg muscle activation during walking and during forward singleleg

hop landing (functional-biomechanical outcomes). The clinical and functional-biomechanical

outcomes were compared between the legs within each group and between the involved

(operated) leg of patients and the non-dominant leg of controls.

Two years after ACL-IB, we found good results in clinical outcomes. Leg asymmetries

remained in performance and knee joint mechanics during single-leg hops. All outcomes were

comparable between ACL-IB and ACL-R. Patients after both ACL-IB and ACL-R did not return

to healthy levels. Compared to controls, they subjectively perceived functional impairments

of their injury, had a reduced quadriceps strength and altered knee biomechanics during

walking. Furthermore, only patients after ACL-IB had different knee mechanics during hop

landing and only patients after ACL-R had different semitendinosus muscle activation during

walking than controls.

Our study demonstrated that 2 years after surgery, patients undergoing less invasive ACLIB

can expect a comparable clinical and functional-biomechanical outcome to that of patients

undergoing ACL-R, without risking comorbidities of graft removal or changes in hamstrings

function. These results support ACL-IB as an alternative surgery to ACL-R for a subset of ACL

patients representing our cohort (i.e., proximal rupture, moderate knee-loading activity level).

In addition, we have shown that even preservation of native ACL fibres does not result in a

healthy clinical and functional-biomechanical outcome level. This suggests that the initial ACL

rupture causes changes that cannot be restored with surgery alone.

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Dose-response relationship of in vivo ambulatory load and cartilage biomarkers: the role of age, tissue health and inflammation

Research Project  | 4 Project Members

Articular cartilage is an avascular and aneural tissue that facilitates joint motion with minimal friction. Osteoarthritis (OA) is a joint disease that affects the whole joint resulting in severe articular cartilage degeneration with a prevalence worldwide of more than 10%. Although the molecular mechanisms that trigger the pathological changes in OA are largely unknown, the ability of chondrocytes to respond to load is believed to play a critical role in maintaining healthy tissue and in the initiation of OA. Different modes of ambulation have resulted in increases of specific blood markers, and immobilization during bed-rest lead to reductions in the same blood markers. However, the dose-response relationship between ambulatory load and mechanosensitive blood markers, its biological variation in healthy persons and in patients with a high risk of developing OA (e.g. with increasing age or after joint injury), and its relevance for cartilage degeneration are unknown. Based on reported differences in the magnitude of load-induced changes in blood markers of articular cartilage depending on the type of physical activity, we have previously tested an experimental framework of a systematic and controlled modulation of weight bearing during a walking stress test that we propose to employ in this study. We will address the following specific aims: Specific Aim 1: Investigate the in vivo dose-response relationship between ambulatory load and mechanosensitive blood markers of articular cartilage using controlled weight bearing during a walking stress test and age, tissue status and the presence of inflammation as experimental paradigms. Specific Aim 2: Investigate the prognostic ability of the individual in vivo dose-response relationship between ambulatory load and mechanosensitive blood markers of articular cartilage for articular cartilage degeneration. Healthy subjects and subjects with previous anterior cruciate ligament (ACL) injury aged 20 to 50 years will be clinically assessed, undergo magnetic resonance imaging (MRI) of both knees, and complete questionnaires on physical function and physical activity. Participants will wear an activity monitor for the 7 days before and during the experiment to record their physical activity level. Each participant will complete three walking stress tests (30 minutes walking) on separate days with repeated blood sampling to assess load-induced changes in levels of mechanosensitive blood markers (COMP, MMP-3, PRG-4, ADAMTS-4). In each test, one of three different ambulatory loads will be applied (80, 100 and 120% body weight (BW)). Inflammation will be assessed as IL-6 serum concentration. Tissue status of articular knee cartilage will be assessed as MRI T2 relaxation time and cartilage thickness at baseline and at 24-month follow-up. This study can be considered as proof-of-concept of a potential diagnostic test (walking stress test) for cartilage mechanosensitivity and will provide first evidence of the role of age, tissue status and presence of inflammation on the dose-response relationship between in vivo ambulatory load and mechanosensitive blood markers of articular cartilage and its relevance for prognosing cartilage degeneration. These results will allow to judge the importance of mechanosensitive blood markers for in vivo mechanobiology of articular cartilage. The results of this study will reveal if the proposed experimental framework may be suitable in the area of cartilage engineering and transplantation and for testing pharmacologic agents and load-modifying interventions aimed at changing tissue metabolism in the context of OA pathomechanics that can be further investigated in ex vivo, in situ and in animal models of OA.

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Muscle function and dynamic and postural stability in patients receiving hip or knee arthroplasty

Research Project  | 5 Project Members

Despite of reported strength deficits and the importance of balance, to date the potential contribution of strength deficits in patients before and after THA or TKA to compromised balance ability is unknown. Furthermore, the role of preoperative muscle function on functional outcome of THA and TKA is poorly understood. A correlation between compromised preoperative muscular function and postoperative outcome would suggest that preoperative physical therapy may be critical for preserving the muscular status and may help explain reported poorer outcome after late treatment when muscular function has already deteriorated. Answers to these questions are highly relevant for developing and improving preoperative treatment schemes and postoperative rehabilitation programs. In particular, understanding the role of strength deficits of specific muscles on dynamic and postural stability will be critical for defining optimal rehabilitation scheme, specifically targeting the muscles responsible for the balance ability and ultimately reducing the risk of falls. The project includes two studies differing in design and primary and secondary objectives but with overlapping patient populations.

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Influence of additional weight carrying on load-induced changes in glenohumeral translation in patients with rotator cuff tear - a translational approach

Research Project  | 4 Project Members

The shoulder is a unique joint: the primary stabilization by the rotator cuff muscles facilitates a large range of motion that is a prerequisite for many daily, occupational and recreational activities. Accordingly, injury to the rotator cuff greatly affects joint function and limits the patients' activities. Rotator cuff tears are a common shoulder injury that sometimes remain undiagnosed because of limited symptoms. However, altered shoulder biomechanics because of injury - even when only subtle - can lead to secondary damage and degeneration including tendinopathy or osteoarthritis. Because of the overlying soft tissue, measuring shoulder biomechanics is complex. Motion of the healthy shoulder primarily comprises rotation with very small to no translation because of stabilization through muscle activity and is affected by muscle cross sectional area (MCSA) and shoulder anatomy including the critical shoulder angle (CSA) and glenoid inclination (GI). Although often clinically observed, inconclusive changes in shoulder translation have been reported in patients with rotator cuff tear. However, to date it is unknown how additional handheld weight similar to situations during daily, occupational or recreational activities affects glenohumeral translation in patients with rotator cuff tear. Based on previous methods for assessing glenohumeral translation, we have developed an in vivo, simulation and ex vivo experimental framework for systematically modulating additional weight during a loading shoulder abduction test that we propose to employ in this study. This framework allows us to assess the dose-response relationship between additional weight and glenohumeral translation termed load-induced glenohumeral translation (liTr). We will address the following specific aims in in vivo, simulation and ex vivo experiments: understanding the biological variation in liTr; understanding the influence of disease pathology on liTr; understanding the potential compensation of rotator cuff tear by muscle activation and muscle size; and understanding the association of liTr and patient outcomes. Patients with rotator cuff tears and asymptomatic persons with similar age and sex distribution will be clinically assessed and complete a loading shoulder abduction test while collecting single plane fluoroscopy images. The same test will be repeated while 3-dimensional (3D) motion data and electromyographic data is collected. In the motion analysis test and in the fluoroscopy test, handheld weight will be applied. LiTr will be calculated as the slope of a regression of the negative distance of the glenohumeral centre of rotation (GHJC) to the acromion and studied in relation to patient's functional scores, MCSA, tear size and type, and the CSA and GI. Moreover, we will extent a previously developed shoulder simulator to integrate glenoid specimen, anterior and posterior aspects of the deltoid muscle and facilitate simulation of individual tendon rupture. Subsequently, we will use this shoulder simulator in simulation and ex vivo experiments to systematically study the effect of tear size and type, CSA and GI in sawbones and human cadaveric specimen. Finally, we will compare results of in vivo, simulation and ex vivo experiments and formulate specific recommendation for clinic and rehabilitation. This study can be considered as proof-of-concept of a potential diagnostic test (loading shoulder abduction test) for glenohumeral translation and will provide first evidence of a dose-response relationship between additional weight and glenohumeral translation. Moreover, the simulation and ex vivo experiments using a shoulder simulator allow the systematic investigation of mechanical compensation for injury to one or more rotator cuff muscles. The results of this study are relevant for diagnostics, treatment and rehabilitation planning in this population.