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1.  Does Perception of Usefulness of Arthroscopic Simulators Differ with Levels of Experience? 
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.
Clinical Relevance
These simulators provide training in surgical skills without compromising patient safety.
doi:10.1007/s11999-011-1797-y
PMCID: PMC3094627  PMID: 21290203
2.  Does Perception of Usefulness of Arthroscopic Simulators Differ with Levels of Experience? 
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.
Clinical Relevance
These simulators provide training in surgical skills without compromising patient safety.
doi:10.1007/s11999-011-1797-y
PMCID: PMC3094627  PMID: 21290203
3.  Direction of the oblique medial malleolar osteotomy for exposure of the talus 
Introduction
A medial malleolar osteotomy is often indicated for operative exposure of posteromedial osteochondral defects and fractures of the talus. To obtain a congruent joint surface after refixation, the oblique osteotomy should be directed perpendicularly to the articular surface of the tibia at the intersection between the tibial plafond and medial malleolus. The purpose of this study was to determine this perpendicular direction in relation to the longitudinal tibial axis for use during surgery.
Materials and methods
Using anteroposterior mortise radiographs and coronal computed tomography (CT) scans of 46 ankles (45 patients) with an osteochondral lesion of the talus, two observers independently measured the intersection angle between the tibial plafond and medial malleolus. The bisector of this angle indicated the osteotomy perpendicular to the tibial articular surface. This osteotomy was measured relative to the longitudinal tibial axis on radiographs. Intraclass correlation coefficients (ICC) were calculated to assess reliability.
Results
The mean osteotomy was 57.2 ± 3.2° relative to the tibial plafond on radiographs and 56.5 ± 2.8 on CT scans. This osteotomy corresponded to 30.4 ± 3.7° relative to the longitudinal tibial axis. The intraobserver (ICC, 0.90–0.93) and interobserver (ICC, 0.65–0.91) reliability of these measurements were good to excellent.
Conclusion
A medial malleolar osteotomy directed at a mean 30° relative to the tibial axis enters the joint perpendicularly to the tibial cartilage, and will likely result in a congruent joint surface after reduction.
doi:10.1007/s00402-010-1227-8
PMCID: PMC3117279  PMID: 21165631
Medial malleolus; Osteotomy; Ankle; Radiography; Preoperative planning; Surgical approach
4.  Probing forces of menisci: what levels are safe for arthroscopic surgery 
Purpose
To facilitate effective learning, feedback on performance during arthroscopic training is essential. Less attention has been paid to feedback on monitoring safe handling of delicate tissues such as meniscus. The goal is to measure in vitro probing forces of menisci and compare them with a theoretical maximum probing force (TMPF).
Method
Menisci samples of ten cadavers were mounted on force platforms to measure probing forces up to 20 N in three directions. Nineteen subjects participated: six novices (experience <60 arthroscopies), ten intermediates (>60 arthroscopies), and three faculty (>250 a year). All had to perform three tasks on each meniscus sample with an arthroscopic probe: push three times on the superior meniscal surface, perform one continuous run on the superior meniscal surface, and push three times on the inferior meniscal surface. The absolute maximum probing force (AMPF) was determined for each condition. A multivariable linear regression analysis was performed to assess the influence of experience on the force magnitude (P < 0.05). AMPFs were compared to the TMPF (estimated to be 8.5 N).
Results
The AMPF of the push task was on average 2.8 N (standard deviation (SD) of 0.8 N), of the continuous run task 2.5 N (SD 0.9 N), and of the pull task 3.9 N (SD 2.0 N). Significant difference was present between experts and novices (P < 0.05). The AMPFs are in the same order of magnitude as the TMPF.
Conclusion
The results indicate the necessity of using a safety level for tissue manipulation when training arthroscopy and a value for is magnitude.
doi:10.1007/s00167-010-1251-9
PMCID: PMC3023859  PMID: 20814661
Safety; Force; Meniscus; Arthroscopy
5.  Measuring hindfoot alignment radiographically: the long axial view is more reliable than the hindfoot alignment view 
Skeletal Radiology  2010;39(11):1103-1108.
Background
Hindfoot malalignment is a recognized cause of foot and ankle disability. For preoperative planning and clinical follow-up, reliable radiographic assessment of hindfoot alignment is important. The long axial radiographic view and the hindfoot alignment view are commonly used for this purpose. However, their comparative reliabilities are unknown. As hindfoot varus or valgus malalignment is most pronounced during mid-stance of gait, a unilateral weight-bearing stance, in comparison with a bilateral stance, could increase measurement reliability. The purpose of this study was to compare the intra- and interobserver reliability of hindfoot alignment measurements of both radiographic views in bilateral and unilateral stance.
Materials and methods
A hindfoot alignment view and a long axial view were acquired from 18 healthy volunteers in bilateral and unilateral weight-bearing stances. Hindfoot alignment was defined as the angular deviation between the tibial anatomical axis and the calcaneus longitudinal axis from the radiographs. Repeat measurements of hindfoot alignment were performed by nine orthopaedic examiners.
Results
Measurements from the hindfoot alignment view gave intra- and interclass correlation coefficients (CCs) of 0.72 and 0.58, respectively, for bilateral stance and 0.91 and 0.49, respectively, for unilateral stance. The long axial view showed, respectively, intra- and interclass CCs of 0.93 and 0.79 for bilateral stance and 0.91 and 0.58 for unilateral stance.
Conclusion
The long axial view is more reliable than the hindfoot alignment view or the angular measurement of hindfoot alignment. Although intra-observer reliability is good/excellent for both methods, only the long axial view leads to good interobserver reliability. A unilateral weight-bearing stance does not lead to greater reliability of measurement.
doi:10.1007/s00256-009-0857-9
PMCID: PMC2939352  PMID: 20062985
Intra-observer; Interobserver; Reliability; Hindfoot alignment view; Long axial view
6.  Biomechanical evaluation of fixation of comminuted olecranon fractures: one-third tubular versus locking compression plating 
Introduction
New concepts in plate fixation have led to an evolution in plate design for olecranon fractures. The purpose of this study was to compare the stiffness and strength of locking compression plate (LCP) fixation to one-third tubular plate fixation in a cadaveric comminuted olecranon fracture model with a standardised osteotomy.
Materials and methods
Five matched pairs of cadaveric elbows were randomly assigned for fixation by either a contoured LCP combined with an intramedullary screw and unicortical locking screws or a one-third tubular plate combined with bicortical screws. Construct stiffness was measured by subjecting the specimens to cyclic loading while measuring gapping at the osteotomy site. Construct strength was measured by subjecting specimens to ramp load until failure.
Results
There was no significant difference in fixation stiffness and strength between the two fixation methods. All failures consisted of failure of the bone and not of the hardware.
Conclusion
Contoured LCP and intramedullary screw fixation can be used as an alternative treatment method for comminuted olecranon fractures as its stiffness and strength were not significantly different from a conventional plating technique.
doi:10.1007/s00402-009-0980-z
PMCID: PMC2826637  PMID: 19823857
Locking compression plate; Comminuted; Olecranon fracture; Biomechanics; Cyclic loading

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