Coming dissertations at Uppsala university
-
Peroneus longus to brevis tendon transfer – a feasible procedure?
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-543748
The peroneus (also termed fibularis) longus and brevis muscles stabilize the lateral side of the ankle during gait. Both tendons can be injured through ankle supination trauma. In cases of more extensive damage to the tendons, a direct repair is not possible, and surgery with a peroneus longus to brevis tendon transfer has been suggested with an added lateral ankle ligament reconstruction, and sometimes a calcaneal osteotomy, in the case of hindfoot varus. This thesis explores the outcome after this surgery:
- Sixteen patients (17 feet) had a follow-up 2-6.5 years after surgery, that also included an osteotomy to the first metatarsal. The results showed good patient-reported and clinical outcome, but slight residual hindfoot varus.
- The difference in anatomic structure between the two muscles was studied and sixteen cadaver legs dissected. Both muscles are pennate, but the peroneus longus had longer fibre length and is 1.4-4.6 times larger in volume than peroneus brevis. The good holding power of peroneus brevis is not attributable to muscle anatomy.
- Thirty-two patients filled out the Foot and Ankle Outcome Score (FAOS) and SF-36 and conducted a gait analysis before, and at six and 12 months after surgery. The FAOS improved significantly, and the three physical domains in SF-36 improved. In the gait, the peak pressure under the first metatarsophalangeal joint diminished. Compared to a healthy control group, there was no other significant difference in the gait kinematics. The FAOS had a moderate correlation to the velocity.
Drawing on the evidence presented in this thesis we demonstrate that the peroneus longus to brevis tendon transfer, with a lateral ankle ligament reconstruction and additional calcaneal osteotomy, is a surgical procedure that achieves good outcomes in terms of patient-reported outcome and gait in patients with irreparable tears of the peroneus tendons.
-
Design and optimization of a microchip biosensor utilizing streaming current
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-543575
Biosensors are devices used for detecting biomolecules. They have wide applications including clinical diagnosis, drug discovery, fundamental biological investigation, and personalized medicine. This thesis introduces a novel biosensing platform leveraging streaming current for detecting small extracellular vesicles (sEVs) and single-stranded DNA (ss-DNA). First, fundamental electrokinetic theories are outlined to establish the relationship between streaming current and key parameters influencing the sensing performance. A silicon-based microfluidic device and a robust experimental setup are designed to enable multiplexed detection. The microchip achieves an improved limit of detection (LoD) of 1 × 104 sEVs/mL. Using this LoD, clinically relevant biomarkers for early-stage lung cancer are detected, demonstrating the platform’s diagnostic potential. Additionally, two novel labeling techniques are introduced to address sEV heterogeneity and amplify streaming current for improved detection sensitivity and specificity. The former uses secondary antibodies tagged with charged molecules to engineer surface charges and profile sEV surface proteins. Results demonstrate the capability of the microchips in multimarker profiling of sEVs. The latter uses an innovative nanoparticle-mediated sandwich assay to introduce new charges on the interface and amplify streaming current signal, enabling ss-DNA detection at picomolar concentrations. This method, benefiting from analyte size and charge, improves the LoD by four orders of magnitude over prior reports. Finally, the thesis advances toward a standalone EV analyzer by developing two modules. The first is a microfluidic system for sEV isolation and enrichment based on surface protein expression levels, pre-selecting and enriching sEVs before membrane protein profiling. The second is a picoammeter designed on a printed circuit board (PCB) to replace bulky and costly measurement units. Together, these innovations contribute to the creation of a highly sensitive and versatile biosensing platform.
-
Structure and hygroelastic properties of conifer branch wood : A multiscale approach
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-543259
Studies of structure-property relationship of compression (CW) and opposite wood (OW) formed in conifer branches are rare, mostly due to their lack of application in construction. Instead most branch wood is today being used as fuel. However, utilising branches as material can contribute to a more efficient and sustainable use of forest biomass and reduce the demand of stem wood for engineered wood products. Furthermore, deeper insight in compression and opposite wood might inspire toward new engineering solutions by using principles prevalent in the tree branch.
This thesis investigates hygroelastic properties of compression and opposite wood in branches by modelling and experimental techniques at several hierarchical material levels.
First, mechanical optimisation of tree branches for bending by using compression and opposite wood in a beam model is analysed. One weakness of the analytical model is the lack of elastic properties of compression and opposite wood of branches. Hence, hygroelastic properties for these are determined by mechanical testing and micro-computed tomography.
Following that, swelling behaviour of CW and OW lignin is studied by Molecular Dynamics (MD) simulations and wide-angle X-ray scattering to understand the effect of their chemically distinct structure.
Lastly, a hierarchical multiscale model is established to study the effect of previously determined lignin swelling coefficient, as well as lignin content and microfibril angle on swelling properties of cell walls. Swelling coefficients and elastic properties obtained by MD simulations are used as an input for Finite Element modelling.
The branches composition of compression wood and a opposite wood indicates that it is optimised for bending resistance. The hygroelastic properties of the comprising tissues are obtained. The swelling of CW is much less anisotropic than CW. The structural differences in lignin of compression and opposite wood and their resulting different swelling coefficient do not lead to different swelling of the compression and opposite wood cell walls.
The experimental and modelling approaches in this thesis are not specific to branch wood and can be of interest in wood science in general to gain more insight into the effect of structural changes on moisture-wood interaction and hygroelastic properties.