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Amsterdam-Zuidoost, Netherlands

Tuijthof G.J.M.,Technical University of Delft | Tuijthof G.J.M.,Orthopedic Research Center Amsterdam | Fruhwirt C.,Austrian Center for Medical Innovation and Technology | Kment C.,Austrian Center for Medical Innovation and Technology
Medical Engineering and Physics | Year: 2013

Minimally invasive surgery poses high demands on tool design. The goal was to measure the influence of drill bit geometry on maximum thrust forces required for drilling, and compare this relative to the known influence of feed rate and bone composition.Blind holes were drilled perpendicular to the iliac crest up to 10. mm depth in cadaveric pelvic bones of 20 pigs (adolescent) and 11 goats (full grown) with eight substantially different drill bits of ∅ 3-3.2. mm. Subsequently, boreholes were drilled perpendicular to the ilium with the same drill bits at three different feed rates (0.58. mm/s, 0.83. mm/s, 1.08. mm/s). The mean maximum thrust force ranges from 10 to 110. N for cortical bone, and from 3 to 65. N for trabecular bone. The results show that both drill bit geometry and feed rate have a significant influence on the maximum thrust forces, with a dominant influence of drill bit geometry in terms of shape of the flutes, sharpness of cutting edges and value of point angle. The differences in thrust forces between cortical and trabecular bone are substantial for all measured conditions. The measured values can be used for drill design. © 2012 IPEM. Source

Van Ooij B.,University of Amsterdam | Van Ooij B.,Orthopedic Research Center Amsterdam | Van Dijk C.N.,University of Amsterdam | Van Dijk C.N.,Orthopedic Research Center Amsterdam
Regional Anesthesia and Pain Medicine | Year: 2011

BACKGROUND AND OBJECTIVES: Continuous femoral nerve block in patients undergoing total knee arthroplasty (TKA) improves and shortens postoperative rehabilitation. The primary aim of this study was to investigate whether the addition of sciatic nerve block to continuous femoral nerve block will shorten the time-to-discharge readiness. METHODS: Ninety patients undergoing TKA were prospectively randomized to 1 of 3 groups: patient-controlled analgesia via femoral nerve catheter alone (F group) or combined with a single-injection (Fs group) or continuous sciatic nerve block (FCS group) until the second postoperative day. Discharge readiness was defined as the ability to walk and climb stairs independently, average pain on a numerical rating scale at rest lower than 4, and no complications. In addition, knee function, pain, supplemental morphine requirement, local anesthetic consumption, and postoperative nausea and vomiting (PONV) were evaluated. RESULTS: Median time-to-discharge readiness was similar: F group, 4 days (range, 2-16 days); Fs group, 4 days (range, 2-7 days); and FCS group, 4 days (range, 2-9 days; P = 0.631). No significant differences were found regarding knee function, local anesthetic consumption, or postoperative nausea and vomiting. During the day of surgery, pain was moderate to severe in the F group, whereas Fs and FCS groups experienced minimal pain (P < 0.01). Patients in the F group required significantly more supplemental morphine on the day of surgery and the first postoperative day. Until the second postoperative day, pain was significantly less in the FCS group (P < 0.01). CONCLUSIONS: A single-injection or continuous sciatic nerve block in addition to a femoral nerve block did not influence time-to-discharge readiness. A single-injection sciatic nerve block can reduce severe pain on the day of the surgery, whereas a continuous sciatic nerve block reduces moderate pain during mobilization on the first 2 postoperative days. Copyright © 2011 by American Society of Regional Anesthesia and Pain Medicine. Source

Van Engelen S.J.P.M.,VU University Amsterdam | Wajer Q.E.,VU University Amsterdam | Van Der Plaat L.W.,Orthopedic Research Center Amsterdam | Doets H.C.,Slotervaart Hospital | And 2 more authors.
Clinical Biomechanics | Year: 2010

Background: This study examined metabolic energy cost and external mechanical work for step-to-step transitions after tibiotalar arthrodesis, and the effect of MBT rocker bottom shoes. Methods: Oxygen uptake, forceplate and kinematic data were recorded in 18 controls and 15 patients while walking at a fixed speed of 1.25 m/s in three walking conditions: barefoot, normal walking shoes and MBT rocker bottom shoes. Metabolic energy cost, external mechanical work, and the roll-over shape of the ankle-foot complex were analyzed. Findings: Tibiotalar arthrodesis leads to higher metabolic energy cost during walking. During step-to-step transitions positive work during push-off with the impaired ankle was decreased but negative work during collision was not affected. The roll-over shape of the ankle-foot complex did not differ between groups and shoe conditions. However, both in patients and controls rocker bottom shoes did lead to decreased positive work at push-off and increased negative work at collision and consequently higher metabolic energy cost of walking. Interpretation: External mechanical work for step-to-step transitions is not different between patients and controls and could not account for the higher metabolic energy cost in patients. Apparently, patients adopt a different walking strategy that limits step-to-step transition cost but nevertheless induces a higher metabolic energy cost. Despite restricted ankle movement, patients retain a normal roll-over shape of the ankle-foot complex. MBT shoes do not affect roll-over shape and appear to have a counterproductive effect on step-to-step transition cost and walking economy. © 2010 Elsevier B.V. All rights reserved. Source

Kerkhoffs G.M.M.J.,Orthopedic Research Center Amsterdam | Van Dijk C.N.,Orthopedic Research Center Amsterdam
Foot and Ankle Clinics | Year: 2013

High-level athletes have significantly greater load and demand on their ankle joints than the average population. Therefore, treatment of acute lateral ankle ligament ruptures in the high-demanding athlete is a challenge. This article reviews the treatment of acute lateral ankle ruptures in athletes, with special emphasis on the role of surgical treatment. © 2013. Source

Tuijthof G.J.M.,Orthopedic Research Center Amsterdam | Tuijthof G.J.M.,Technical University of Delft | Visser P.,Orthopedic Research Center Amsterdam | Sierevelt I.N.,Orthopedic Research Center Amsterdam | And 2 more authors.
Clinical Orthopaedics and Related Research | Year: 2011

Background: Some commercial simulators are available for training basic arthroscopic skills. However, it is unclear if these simulators allow training for their intended purposes and whether the perception of usefulness relates to level of experience. Questions/purposes: We addressed the following questions: (1) Do commercial simulators have construct (times to perform tasks) and face validity (realism), and (2) is the perception of usefulness (educational value and user-friendliness) related to level of experience? Methods: We evaluated two commercially available virtual reality simulators (Simulators A and B) and recruited 11 and nine novices (no arthroscopies), four and four intermediates (one to 59 arthroscopies), and seven and nine experts (> 60 arthroscopies) to test the devices. To assess construct validity, we recorded the median time per experience group for each of five repetitions of one identical navigation task. To assess face validity, we used a questionnaire to judge up to three simulator characteristic tasks; the questionnaire asked about the realism, perception of educational value, and perception of user-friendliness. Results: We observed partial construct validity for Simulators A and B and considered face validity satisfactory for both simulators for simulating the outer appearance and human joint, but barely satisfactory for the instruments. Simulators A and B had equal educational value according to the participants. User-friendliness was judged better for Simulator B although both were graded satisfactory. The perception of usefulness did not differ with level of experience. Conclusions: Our observations suggest training on either simulator is reasonable preparation for real-life arthroscopy, although there is room for improvement for both simulators. These simulators provide training in surgical skills without compromising patient safety. © 2011 The Author(s). Source

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