Publications by authors named "Martina Feierabend"

7 Publications

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Evaluation of braking performances of patients with osteoarthritis of the knee or hip: Are there alternatives to a brake simulator?

Acta Orthop Traumatol Turc 2021 Jan;55(1):42-47

Department of Orthopaedic Surgery, University Hospital of Tübingen, Tübingen, Germany.

Objective: This study aims to develop and evaluate a simple tool for daily practice that might allow a rough estimate of individual braking performance (brake response time, BRT) of patients with osteoarthritis or those with arthroplasty of the knee or hip.

Methods: In this cross-sectional study, we examined 162 patients (72 men, 90 women; mean age = 64±12.8 years) who suffered from osteoarthritis of the knee (n=45) or hip (n=64) or who underwent a total hip (n=37) or knee (n=16) arthroplasty. BRT of each patient was measured in a brake simulator. The results were compared to demographic data, various clinical tests, and pain surveys. From these data, a multiple linear regression model was developed.

Results: From the observed correlations, the regression model consisted of age (correlation with BRT τ=0.176, p=0.001), sex (τ=0.361, p<0.001), Hau's step test (τ=-0.345, p<0.001), and the pain dimension of the Hip disability/Knee injury and Osteoarthritis Outcome Score (τ=-0.265, p<0.001). We, therefore, suggested the following formula: BRTest = 634.8 - (8.8 x Hau) + 119.2 (for women) + (3.0 x age) - (1.3 x H/KOOS Pain). The above-mentioned variables contributed significantly to the prediction of BRT and could achieve a multiple R² adj of 0.31. The model leaves a residual standard error (i.e., SD of the residuals) of 158.4 ms, which is superior to a model without predictors; F (4.140)=16.8, p<0.001.

Conclusion: Our evaluated regression model offers an uncertainty which is comparable to the one based on a fixed time period after surgery or a defined pathologic condition. The high variability even within a single patient over several brake simulator measurements makes it unlikely for a model to be generated solely based on clinical testing. Taking the available data in literature into account, we advise caution when formulating a real-time- or condition-based recommendation. We rather suggest being aware of risk factors that might lead to impaired BRT to sensitize patients to their impaired ability to drive. We identify such risk factors, namely old age, female sex, impaired musculoskeletal function, as tested in Hau's step test, and high levels of pain.

Level Of Evidence: Level III, Therapeutic Study.
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http://dx.doi.org/10.5152/j.aott.2021.19041DOI Listing
January 2021

Different vacuum levels, vacuum reduction during low milk flow, and different cluster detachment levels affect milking performance and teat condition in dairy cows.

J Dairy Sci 2020 Oct 31;103(10):9250-9260. Epub 2020 Jul 31.

Veterinary Physiology, Vetsuisse Faculty, University of Bern, 3001 Bern, Switzerland. Electronic address:

Traditionally, machine milking is performed at a constant vacuum supply. The system vacuum has to be set high enough to allow a sufficiently high vacuum at the teat end, despite the inevitable vacuum drop caused by milk flow. This leads to an increased vacuum load on the teat, especially when milk flow ceases at the end of milking. We tested the hypothesis that a milk flow-controlled adaptation of vacuum settings during milking allows even higher vacuum levels than are usually recommended during the period of high milk flow if the vacuum is reduced during low milk flow. Combined with a high cluster detachment flow rate level, increased milking performance is expected without an increased effect on teat tissue. Ten Holstein dairy cows were milked with a bucket milker with the claw vacuum adjusted in the absence of milk flow at a regular (43 kPa) and high (48 kPa) claw vacuum, with and without vacuum reduction during low milk flow (<2 kg/min), and combined with different cluster detachment levels (0.2, 0.6, and 1 kg/min). Each treatment was applied in each cow during 4 subsequent milkings in a randomized crossover design. Both claw vacuum and milk flow were continuously recorded throughout milking. Teat tissue thickness was measured using a cutimeter and teat wall diameter was measured by B-mode ultrasonography at 5 min after the end of milking. Milk yield was not affected by either vacuum settings or detachment levels. Machine-on time in treatments with vacuum reduction was shorter at high than at low vacuum and decreased with increasing detachment levels. Average milk flow was higher at high than at low vacuum and reached highest values in milkings without vacuum reduction at both vacuum levels. The average milk flow was higher at a cluster detachment of 1 kg/min than at 0.2 kg/min. However, both teat tissue thickness and (as a tendency) teat wall diameter at 5 min after cluster detachment were higher in milkings at high vacuum without vacuum reduction compared with all other treatments. In conclusion, high claw vacuum up to 48 kPa increases milking performance because of higher milk flow and reduced machine-on time. Negative effects of high vacuum on teat tissue are prevented by reducing vacuum during low milk flow (<2 kg/min) at the start and end of milking. Additionally, using a high cluster detachment level reduces machine-on time without a loss of harvested milk.
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http://dx.doi.org/10.3168/jds.2020-18677DOI Listing
October 2020

Auditory Space Perception in the Blind: Horizontal Sound Localization in Acoustically Simple and Complex Situations.

Perception 2019 Nov 28;48(11):1039-1057. Epub 2019 Aug 28.

Department of Cognitive Psychology, Faculty of Psychology, Ruhr University Bochum, Germany; Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany.

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http://dx.doi.org/10.1177/0301006619872062DOI Listing
November 2019

Estimating Braking Performance in Osteoarthritis of the Knee or Hip with a Reaction Timer.

Orthop Surg 2019 Apr 3;11(2):248-254. Epub 2019 Apr 3.

Department of Orthopaedic Surgery, University Hospital of Tübingen, Tübingen, Germany.

Objective: To investigate if testing in a brake simulator can be replaced by a simple reaction timer setup imitating the ergonomic conditions of emergency braking when evaluating the ability to drive in patients with musculoskeletal problems of the lower extremities.

Methods: A cross-sectional survey was performed in the Department of Orthopaedic Surgery in our University Hospital from October 2014 until May 2015. Patients attending our department with either osteoarthritis or arthroplasty of the knee or hip were asked to participate in the study if they had a valid driving license. The age limit was from 18 to 85 years. Both women and men were included. Registered demographic data were patient age, height, sex, body weight, and body mass index. Braking performance (brake response time [BRT]) was evaluated in a brake simulator that was embedded into a real car cabin (10 measurements). The values obtained were compared with those registered when simply testing (5 measurements) those patients with a normal reaction timer setup that imitated the sitting position in a car. Kendall's tau correlation coefficient was calculated between the values obtained from the brake simulator with those from the reaction timer setup.

Results: Altogether, 137 patients (median age 67 years [range, 24-89 years]) with either osteoarthritis of the knee (n = 55) or hip (n = 82) were tested. Age was comparable in both collectives (P = 0.807). The mean body height was 1.70 m in both groups. Knee patients presented with a higher body weight of approximately 5 kg (P = 0.014) and consequently also had a higher body mass index (P = 0.023). The median BRT in the brake simulator was 628 ms (range, 390-1444 ms) for all subjects: 592 ms (range, 418-1146 ms) in the hip group and 696 ms (range, 390-1444 ms) in the knee group. Measurement values obtained by the reaction timer were significantly (P < 0.001) higher by approximately 15% (SD, 22%) than those measured in the brake simulator. A moderate correlation was found between the reaction timer and the brake simulator, with a Kendall's tau of 0.449 (P < 0.001) for all patients. Interestingly, hip patients showed a higher correlation (τ = 0.471) than knee patients (τ = 0.263).

Conclusion: Even though the measured correlations do not allow us to make a definite statement concerning braking performance, especially in knee patients, a simple reaction timer test can provide a low-cost first estimate of BRT for patients and their treating physicians. For forensic statements, the brake simulator will, however, remain the gold standard.
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http://dx.doi.org/10.1111/os.12446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6594540PMC
April 2019

Influence of spine surgery on the ability to perform an emergency stop while driving a car.

J Back Musculoskelet Rehabil 2018 Feb;31(1):29-36

Department of Orthopaedic Surgery, University Hospital of Tübingen, Tübingen, Germany.

Background: Spinal surgeries have strongly increased in number over the past decade. The question of when it is safe to resume driving is thereby one the most frequently asked questions that patients ask of their treating physician.

Objective: The aim of this study was to assess braking performance before and after spine surgery.

Methods: Reaction time, foot transfer time (together brake response time [BRT]), and brake force (BF) were evaluated in a drive simulator. A longitudinal patient cohort (n= 27) was tested preoperatively and at the first follow-up. A cross-sectional cohort (n= 27) was tested at > 1 year postoperatively. The values from these groups were compared with a healthy age-matched control group of 24 volunteers.

Results: No significant improvement in BRT was seen in lumbar fusion three months postoperatively (p= 0.597); BF was even weaker than it was preoperatively (p= 0.044). In comparison to the control group (median BRT 479 ms), preoperative BRT was already impaired in lumbar fusion patients (median 560 ms), representing an increased braking distance of 2.25 m at 100 km/h.

Conclusion: Although most patients performed adequately, about one third presented critical braking performance. Risk factors for impaired braking may include scheduled multisegmental fusion surgery, female sex, and pain.
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http://dx.doi.org/10.3233/BMR-169570DOI Listing
February 2018

Radiographic Hip or Knee Osteoarthritis and the Ability to Drive.

Orthopedics 2017 Jan 21;40(1):e82-e89. Epub 2016 Sep 21.

The question of whether patients with musculoskeletal disorders are fit to drive is of paramount importance for them and frequently is directed to the treating orthopedic specialist. Although perioperative braking performance has been increasingly investigated in recent years, scientific data on braking safety in individuals with osteoarthritis (OA) are scarce. This study analyzed the braking performance of 158 patients with OA of the right or left knee or hip and compared the results with radiographic OA grading according to the Kellgren-Lawrence classification scale. Reaction time and foot transfer time (together called brake response time [BRT]) and brake force were measured in a real car cabin, and the values were compared with measurements obtained from young (n=34) and age-matched (n=36) control groups. Although the majority of BRTs in both control groups remained below 600 milliseconds, patients with both hip and knee OA, whether on the right or left side, had significantly worse values (P<.001) and frequently exceeded this limit. A stronger impact was observed on the right side and in knee OA, with the worst results found in patients with bilateral OA (median BRT for bilateral hip OA, 656 milliseconds [range, 468-1459 milliseconds]; median BRT for bilateral knee OA, 696 milliseconds [range, 527-772 milliseconds]), leading to an increased total stopping distance of up to 32 m at 100 km/h. No correlation of braking performance with radiographic OA manifestation was observed (Kendall tau for BRT: τ=0.007, P=.92; Kendall tau for brake force: τ=-0.014, P=.82), which makes radiographs an inadequate tool for medical driving recommendations. [Orthopedics. 2017; 40(1):e82-e89.].
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http://dx.doi.org/10.3928/01477447-20160915-05DOI Listing
January 2017