Use of Tekscan pressure sensors for measuring contact pressures in the human knee joint

Herregodts, Stijn; Baets, Patrick De; Victor, Jan; Verstraete, Matthias

doi:10.21825/scad.v6i2.1123

Cited by 10 publications

(6 citation statements)

References 32 publications

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“…Compared to the formerly popular ink-based pressure sensitive film technology (e.g. Fuji film), the lower thickness of the Tek-Scan sensor film allows better adaptation to ball-shaped contact surfaces, and accuracy and reproducibility are much higher [28,34]. The former tended to severely underestimate the contact area at lower pressures and delivered unsatisfactory results especially for congruent joints [28], what might have contributed to the conclusion that the lateral knee compartment is less congruent than the medial one [3].…”

Section: A2 Medial Compartment Force Ratio (Mfr) Required For Equal C...mentioning

confidence: 99%

Towards planning of osteotomy around the knee with quantitative inclusion of the adduction moment: a biomechanical approach

et al. 2021

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Purpose Despite practised for decades, the planning of osteotomy around the knee, commonly using the Mikulicz-Line, is only empirically based, clinical outcome inconsistent and the target angle still controversial. A better target than the angle of frontal-plane static leg alignment might be the external frontal-plane lever arm (EFL) of the knee adduction moment. Hypothetically assessable from frontal-plane-radiograph skeleton dimensions, it might depend on the leg-alignment angle, the hip-centre-to-hip-centre distance, the femur- and tibia-length. Methods The target EFL to achieve a medial compartment force ratio of 50% during level-walking was identified by relating in-vivo-measurement data of knee-internal loads from nine subjects with instrumented prostheses to the same subjects’ EFLs computed from frontal-plane skeleton dimensions. Adduction moments derived from these calculated EFLs were compared to the subjects’ adduction moments measured during gait analysis. Results Highly significant relationships (0.88 ≤ R2 ≤ 0.90) were found for both the peak adduction moment measured during gait analysis and the medial compartment force ratio measured in vivo to EFL calculated from frontal-plane skeleton dimensions. Both correlations exceed the respective correlations with the leg alignment angle, EFL even predicts the adduction moment’s first peak. The guideline EFL for planning osteotomy was identified to 0.349 times the epicondyle distance, hence deducing formulas for individualized target angles and Mikulicz-Line positions based on full-leg radiograph skeleton dimensions. Applied to realistic skeleton geometries, widespread results explain the inconsistency regarding correction recommendations, whereas results for average geometries exactly meet the most-consented “Fujisawa-Point”. Conclusion Osteotomy outcome might be improved by planning re-alignment based on the provided formulas exploiting full-leg-radiograph skeleton dimensions.

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Section: A2 Medial Compartment Force Ratio (Mfr) Required For Equal C...mentioning

confidence: 99%

Towards planning of osteotomy around the knee with quantitative inclusion of the adduction moment: a biomechanical approach

et al. 2021

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“…However, the contrasting results from Lee-Shee et al could be a result of the constraint of the varus-valgus and internal-external rotations of the joints during their testing. The results of this study may also provide a closer representation of the peak contact pressures in the joint given that Tekscan pressure mats, such as those used by Fischenich et al and Heckelsmiller et al, are relatively stiffer making them less suitable and less repeatable in small and substantially curved surfaces such as those of the ovine stifle joint ( Brand, 2005 ; Herregodts et al, 2015 ). Furthermore, Tekscan pressure mats have a lower spatial resolution than pressure sensitive films and require averaging across sensor nodes due to artefactual recordings ( Brand, 2005 ).…”

Section: Discussionmentioning

confidence: 86%

An ovine knee simulator: description and proof of concept

Bartolo,

Newman,

Dandridge

et al. 2024

Front. Bioeng. Biotechnol.

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AimsThe ovine stifle is an established model for evaluation of knee treatments, such as meniscus replacement. This study introduces a novel ovine gait simulator for pre-testing of surgical treatments prior to in vivo animal trials. Furthermore, we describe a pilot study that assessed gait kinematics and contact pressures of native ovine stifle joints and those implanted with a novel fiber-matrix reinforced polyvinyl alcohol-polyethylene glycol (PVA-PEG) hydrogel meniscus to illustrate the efficacy of the simulator.MethodsThe gait simulator controlled femoral flexion-extension and applied a 980N axial contact force to the distal tibia, whose movement was guided by the natural ligaments. Five right ovine stifle joints were implanted with a PVA-PEG total medial meniscus replacement, fixed to the tibia via transosseous tunnels and interference screws. Six intact and five implanted right ovine stifle joints were tested for 500 k gait cycles at 1.55 Hz. Implanted stifle joint contact pressures and kinematics in the simulator were compared to the intact group. Contact pressures were measured at 55° flexion using pressure sensitive film inserted sub-meniscally. 3D kinematics were measured optically across two 30-s captures.ResultsPeak contact pressures in intact stifles were 3.6 ± 1.0 MPa and 6.0 ± 2.1 MPa in the medial and lateral condyles (p < 0.05) and did not differ significantly from previous studies (p > 0.4). Medial peak implanted pressures were 4.3 ± 2.2 MPa (p > 0.4 versus intact), while lateral peak pressures (9.4 ± 0.8 MPa) were raised post medial compartment implantation (p < 0.01). The range of motion for intact joints was flexion/extension 37° ± 1°, varus/valgus 1° ± 1°, external/internal rotation 5° ± 3°, lateral/medial translation 2 ± 1 mm, anterior/posterior translation 3 ± 1 mm and distraction/compression 1 ± 1 mm. Ovine joint kinematics in the simulator did not differ significantly from published in vivo data for the intact group, and the intact and implanted groups were comparable (p > 0.01), except for in distraction-compression (p < 0.01).ConclusionThese findings show correspondence of the ovine simulator kinematics with in vivo gait parameters. The efficacy of the simulator to evaluate novel treatments was demonstrated by implanting a PVA-PEG hydrogel medial meniscal replacement, which restored the medial peak contact pressures but not lateral. This novel simulator may enable future work on the development of surgical procedures, derisking subsequent work in live animals.

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“…The low thickness and continuous measurement are major advantages, but numerous factors make pressure mapping challenging. Herregodts et al describe wrinkling of the sensor, uneven test surfaces, and the lack of reliable fixation methods as contributing large effects on the accuracy of the sensor [46]. All three of these factors were experienced while using Tekscan sensors in this study, though care was taken to minimize the effects of these factors.…”

Section: Discussionmentioning

confidence: 88%

Methods for Testing Meniscal Repair Using a 3D-Printed Meniscus

Nelson,

Voinier,

Tran

et al. 2024

Applied Biosciences

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Torn and damaged menisci resulting from trauma are very common knee injuries, which can cause pain and mobility limitations and lead to osteoarthritis. Meniscal injuries can require surgery to repair the tissue damage and restore mobility. Here we describe the biomechanical testing of a 3D-printed meniscus to illustrate methods to determine if it has the strength and durability to effectively repair meniscal tears and restore knee biomechanics. This work was designed to demonstrate the steps needed to test novel meniscus repair devices prior to moving toward animal testing. The first testing step determined the ability of the 3D-printed meniscus to withstand surgical fixation by measuring the suture pull-out force. We show that vertical 2/0 silk or Fiberwire sutures need an average of 1.4 or 1.8 N, respectively, to pull through the meniscus, while horizontal sutures need only 0.7 and 1.2 N, respectively. The next step measured the compressive strength of normal, damaged, and repaired porcine meniscus tissue. Here, we show that meniscectomy decreased the stiffness of meniscus tissue from 26.7 ± 0.85 N to 7.43 ± 0.81 N at 25% strain. Menisci repaired with the 3D-printed tissue restored 66% of the measured force at 25% strain. The final step measured the contact pressures and areas in an ex vivo porcine knee before and after meniscal repair was made with the 3D-printed meniscus tissue. The example 3D-printed meniscus was successfully sutured into the porcine knee joint but failed to restore normal knee contact pressures. This work demonstrates the need for an iterative biomechanical testing process of biomaterial development, 3D-printing optimization, and knee kinematics to develop a durable and functional meniscus repair device. In summary, the methods described here serve as a guide for the functional evaluation of novel meniscus repair devices.

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Use of Tekscan pressure sensors for measuring contact pressures in the human knee joint

Cited by 10 publications

References 32 publications

Towards planning of osteotomy around the knee with quantitative inclusion of the adduction moment: a biomechanical approach

Towards planning of osteotomy around the knee with quantitative inclusion of the adduction moment: a biomechanical approach

An ovine knee simulator: description and proof of concept

Methods for Testing Meniscal Repair Using a 3D-Printed Meniscus

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