Plantar heel pain is commonly encountered by clinicians. Various conditions, such as plantar fasciopathy, myofascial syndrome and entrapment of the tibial, plantar and calcaneal nerves at the tarsal tunnel can cause plantar heel pain. This diversity in aetiology makes the diagnosis and treatment challenging. There are limited studies on pain mechanisms in patients with planter heel pain. There is no gold criterion standard for the diagnosis. Although various interventions have been reported, no specific treatment approach has yet been identified as being most effective. The first aim of this thesis was to critically appraise the literature on plantar heel pain of neural origin. Various databases were searched for peer-reviewed articles that predominantly focused on neurogenic plantar heel pain or that discussed relevant biomechanics of the tibial, plantar and calcaneal nerves. This review revealed inconsistency in the literature regarding the diagnosis and treatment of neurogenic plantar heel pain. There also was a lack of evidence for treatment approaches although the majority of patients with plantar heel pain are reported to improve with conservative treatment. The second aim of this thesis was to examine the biomechanical effects of clinical tests and combination of movements on various structures associated with plantar heel pain. This aim was achieved through cadaver studies (Study 1–3), in which strain in the plantar fascia and the nerves of the lower limb, and excursion of the nerves were measured during various movements and positions of the lower limb. Study 1 examined the Dorsiflexion-eversion test used to diagnose tarsal tunnel syndrome (TTS) and the Windlass test for plantar fasciopathy given the similarity between both tests. Both the Dorsiflexion-eversion and Windlass tests significantly increased strain in the structures that are commonly associated with plantar heel pain (the tibial and plantar nerves and plantar fascia). This suggests that the usefulness of the Dorsiflexion-eversion and Windlass tests in the differential diagnosis of plantar heel pain might be limited. Study 2 investigated the influence of different positions in adjacent joints on nerve biomechanics during ankle and toe movement. Increased strain in the tibial nerve at the ankle and plantar nerves associated with ankle and toe movement was significantly higher when the nervous system was pre-tensioned at a more proximal joint. Strain was even higher when the nerve bed was pre-tensioned at two joints. Study 3 examined a modified straight leg raising (SLR) test in which ankle dorsiflexion is performed before hip flexion. This test has been suggested to diagnose distal neuropathies such as TTS. During the modified SLR, the excursion and strain in the sciatic nerve associated with hip flexion were transmitted distally along the nerve from the hip to the foot. As a result, the strain in the nerves around the foot and ankle increased significantly during hip flexion. This movement did not affect plantar fascia strain. Consequently, the modified SLR may be a useful test to differentially diagnose plantar heel pain. This test warrants future research to evaluate its clinical use in patients with neurogenic plantar heel pain. The third aim of this thesis was to determine the reliability of high-resolution ultrasound for measuring the cross-sectional area of the tibial nerve at the tarsal tunnel and to compare the tibial nerve size between people with and without plantar heel pain. Study 4 investigated intra and intertester reliability in 10 participants without plantar heel pain by calculating intraclass correlation coefficients, measurement error and smallest detectable difference (SDD). Intra and intertester reliability were excellent, with very small measurement error and SDD. Tibial nerve enlargement in an individual patient by as little as 1.8 mm2 can be detected reliably with high-resolution ultrasound. The use of average value of three scans is recommended to compare between the involved and uninvolved side. Differences in the nerve size between 26 patients with plantar heel pain and 20 control participants were also analysed. There was no significant difference in tibial nerve size between both groups. Future research is needed to investigate the tibial nerve size in patients with proven TTS using ultrasonography. The fourth aim of this thesis was to investigate the characteristics of plantar heel pain through Study 5 for the same group of patients and control participants as in Study 4. Several self-report measures on pain and quality of life were used. Clinical tests and quantitative sensory tests (QST) were performed at local and remote sites on the involved and uninvolved side in the patients and on one side in the control participants. In the patients, mechanical hyperalgesia was the main finding as demonstrated by changes in palpation and pressure pain threshold. Other findings were changes in current thresholds, vibration threshold and thermal perception thresholds. These results suggest the existence of sensory changes that likely indicates change in peripheral and central pain processing. It is recommended to utilise a multidimensional pain assessment for patients with plantar heel pain. The findings in this thesis are important for the diagnosis and treatment of plantar heel pain. For future research, the results suggest to use fresh cadavers when investigating biomechanics of the clinical tests and nerve gliding exercises that are used for patients with plantar heel pain. It is also suggested to evaluate the cross-sectional area of the tibial nerve at the tarsal tunnel, the QSTs and all other diagnostic measurements in this thesis in patients with neurogenic plantar heel pain or patients with TTS.

 ABSTRACT  Background: Since its first mention by Kirk et al. in 1967 and its recognition as a full- fledged rheumatologic disorder, the hypermobility syndrome (HMS) has been increasingly investigated and reported in the scientific literature. Expeditiously renamed benign joint hypermobility syndrome in the patent absence of life-threatening complications, its relatively innocuous character has been progressively reconsidered. In fact, the HMS tends to date to be considered analogous to the Ehlers-Danlos syndrome-hypermobility type, a heritable disease of connective tissue, and therefore emerges as a chiefly rheumatologic disorder with possible widespread reverberations in practically all organs and systems. The condition thence goes beyond the sole involvement of the musculoskeletal system and is recurrently associated with seemingly-unrelated and more or less severe conditions (cardiovascular, pulmonary, gastro- intestinal…). However, neurologic implications of the hypermobility syndrome remain poorly documented, particularly those regarding the peripheral nervous system. Ranking amongst the afflictions of the latter, nerve entrapment syndromes (NES) comprehend a multitude of categories, notably the thoracic outlet syndrome (TOS). And if their pathological mechanisms are generally apprehended...

För att undersöka misstänkt tillklämningsneuropati i peroneus communis (PC) används elektroneurografi, där elektrisk stimulering möjliggör undersökning av nervledningshastigheter, svarsamplitud och överledningstid. Vid opålitlig registrering på extensor digitorium brevis (EDB), görs registreringen på tibialis anterior (TA). I dagsläget finns dock inga normalvärden eller standardiserad metod för registrering på TA. Syftet med studien var därför att ta fram dessa normalvärden och utveckla en metod för TA-registrering, och samtidigt jämföra de båda registreringspunkterna gällande nervledningshastighet, undersöka sidoskillnaderna vid registrering på TA och undersöka hur kroppslängden påverkade överledningstiden. Det undersöktes om s.k. F-waves kunde påvisas vid registrering på TA och i så fall hur hög svarsandelen och svarslatensen var. 22 deltagare mellan 23-59 år gamla och 154-190 cm i kroppslängd undersöktes. TA undersöktes med den aktiva registreringselektroden på muskeln där den var som störst och med referenselektroden på fotleden. Stimuleringar gjordes på laterala poplitea fossa och 110 mm ned distalt om caput fibula. EDB undersöktes enligt metodbeskrivning. Normalvärdena för TA var 2,2-5,4 mV gällande amplitud, 55-73 m/s gällande nervledningshastighet och 3,8-5,9 ms gällande överledningstid. Sidoskillnaderna var 0-1,4 mV gällande amplitud, 0-8 m/s gällande hastighet och 0-0,8 ms gällande överledningstid. De beräknade gränsvärdena visar på de små sidoskillnaderna som krävs för en klinisk betydelse. Överledningstiden kunde till 23 % förklaras av kroppslängden. Resultaten var likvärdiga med tidigare studier. Jämförelsen av nervledningshastigheten mellan registrering på TA och EDB visade en statistiskt, men inte nödvändigtvis kliniskt signifikant skillnad, med bias + 5 m/s. F-waves återfanns hos samtliga deltagare, med svarsandelen 94-100 %. F-wave svarslatensen kunde till 41 % förklaras av kroppslängden. / Electroneurography is used to examine a suspected entrapmentneuropathy in peroneus communis (PC), where an electric stimulus enables the evaluation of nerve conduction velocity, muscle response amplitude and latency. If registration from the extensor digitorum brevis (EDB) provides unreliable results, the registration can be made from tibialis anterior (TA). Currently there are no normal values available in our laboratory and no standard method regarding the registration on TA. The purpose of this study was therefore to retrieve normal values for this registration and to develop and establish a method, and also compare the different registration sites, to examine the side differences from the registrations on TA, and how the height affected the latency. It was also examined if so called F-waves could be recorded from TA, and if so, determine the response rate and latency. 22 participants between 23-59 years an 154-190 cm were examined. TA was examined with the active registration electrode on the site where the muscle was the largest and the reference electrode on the ankle. Stimulations were made on lateral poplitea fossa and 110 mm lower on distal caput fibula. EDB were examined according to established methods. Normal values for the registration on TA were 2,2-5,4 mV regarding amplitude, 55-73 m/s regarding nerve conduction velocity and 3,8-5,9 ms regarding latency. Side differences were 0-1,4 mV regarding amplitude, 0-8 m/s regarding nerve conduction velocity and 0-0,8 ms regarding latency. The calculated limits show that it only takes small side differences to have a clinical significance. The method gave equivalent results to previous studies. 23 % of the latency could be explained by height. The comparing of the nerve conduction velocity from the different registrations showed a significant statistical, but not necessarily clinical, difference, with the bias 5 m/s. F-waves were retrieved from all participants with a response rate of 94-100 %. 41 % of the F-wave latency could be explained by height.