This thesis contributes to the evidence-base of the influence of patient factors, surgical approach and implant design on outcomes after total hip replacement (THA).A systematic review (SR) shows... Show moreThis thesis contributes to the evidence-base of the influence of patient factors, surgical approach and implant design on outcomes after total hip replacement (THA).A systematic review (SR) shows that there is strong evidence for BMI, age, comorbidity, preoperative functioning and mental health as predictors of physical functioning. A predictive model based on data from this thesis emphasizes preoperative functioning, mental health and pain as predictors.To treat hip fractures, the posterolateral (PLA) and direct lateral surgical approach (DLA) are the most commonly used. The PLA may cause more dislocations, but seems to result in less walking problems and abductor insufficiency than the DLA. All investigated surgical approaches for primary THA resulted in a significant improvement in patient reported outcome measures (PROMs). The anterior and posterolateral approaches provided greater improvement in physical function and pain, but clinical differences were small.A multicenter randomized trial comparing two hip stems is described. No significant difference has been demonstrated between the Collum Femoris Preserving (CFP) and Zweymüller stem in physical function at 5 years or implant survival at 12 years, although CFP may be inferior in cup revisions. A SR suggests lower dislocation rates and revisions for dual mobility cups in THA, but high quality evidence is lacking. Therefore, we designed an RCT comparing dual mobility cups with unipolar cups in older patients.In addition to providing insights into the influence of patient, surgical and implant characteristics on outcome after (total) hip arthroplasty, this thesis provides suggestions for the design of future clinical trials. Show less
Hypothesis: Insertion speed during cochlear implantation determines the risk of cochlear trauma. By slowing down insertion speed tactile feedback is improved. This is highly conducive to control... Show moreHypothesis: Insertion speed during cochlear implantation determines the risk of cochlear trauma. By slowing down insertion speed tactile feedback is improved. This is highly conducive to control the course of the electrode array along the cochlear contour and prevent translocation from the scala tympani to the scala vestibuli. Background: Limiting insertion trauma is a dedicated goal in cochlear implantation to maintain the most favorable situation for electrical stimulation of the remaining stimulable neural components of the cochlea. Surgical technique is one of the potential influencers on translocation behavior of the electrode array. Methods: The intrascalar position of 226 patients, all implanted with a precurved electrode array, aiming a mid-scalar position, was evaluated. One group (n = 113) represented implantation with an insertion time less than 25 seconds (fast insertion) and the other group (n = 113) was implanted in 25 or more seconds (slow insertion). A logistic regression analysis studied the effect of insertion speed on insertion trauma, controlled for surgical approach, cochlear size, and angular insertion depth. Furthermore, the effect of translocation on speech performance was evaluated using a linear mixed model. Results: The translocation rate within the fast and slow insertion groups were respectively 27 and 10%. A logistic regression analysis showed that the odds of dislocation increases by 2.527 times with a fast insertion, controlled for surgical approach, cochlear size, and angular insertion depth (95% CI = 1.135, 5.625). We failed to find a difference in speech recognition between patients with and without translocated electrode arrays. Conclusion: Slowing down insertion speed till 25 seconds or longer reduces the incidence of translocation. Show less
