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BackgroundHigh tibial osteotomy is a valuable option for patients with varus gonarthrosis. To avoid difficulties with closing-wedge osteotomies, medial opening-wedge high tibial osteotomies have been advocated.HypothesisOpening-wedge high tibial osteotomy is a good option in highly active patients with varus gonarthrosis who would like to delay or prevent progression to total knee arthroplasty without activity restrictions.Study DesignCase series; Level of evidence, 4.MethodsTwenty consecutive patients with varus gonarthrosis were treated with a medial opening-wedge high tibial osteotomy using the Puddu plate and allograft bone graft for a prospective study (14 men and 6 women; average age, 49.4 years [range, 36-67 years]). Gait analysis was performed preoperatively and at 6 months postoperatively. Preoperative radiographs, subjective ratings, and knee scores (Lysholm and Hospital for Special Surgery [HSS] scores) were obtained. At 2 years postoperatively and at the latest follow-up visit (average, 8.3 years), the subjective ratings and knee scores were repeated.ResultsGait analysis revealed an abnormal weightbearing pattern preoperatively with the vertical ground-reaction force. The postoperative vertical ground-reaction force revealed a normal double peak pattern. The preoperative adduction moment was 29% greater than the 6-month postoperative adduction moment. The preoperative varus averaged 3.6° and was corrected to an average of 7.5° of valgus postoperatively. All patients subjectively rated their preoperative knee as poor. At 2 years postoperatively, most patients (14) rated their knee as good, with 5 excellent and only 1 fair rating. The average preoperative Lysholm and HSS knee scores were 54.2 and 75.9, respectively, compared with the 2-year postoperative averages of 89.1 and 92.7, respectively. At 8 years postoperatively, there was 70% survivorship with 42% of patients rating their knees as good or excellent. Five patients (25%) had undergone total knee arthroplasty. Lysholm and HSS knee scores were 83.0 and 86.8, respectively, for the surviving knees at 8 years postoperatively.ConclusionMedial opening-wedge high tibial osteotomy produces good results in the midterm. After the osteotomy, a more normal appearing weightbearing pattern with double peaks was seen. The adduction moment significantly decreased, resulting in less contact pressure through the medial degenerative compartment of the knee. The authors recommend medial opening-wedge high tibial osteotomy for young patients with varus alignment and medial compartment arthritis to allow this patient population to remain highly active and delay progression to total knee arthroplasty without activity restrictions.

Joint motion simulators (JMS’s) have been developed for many applications enabling the repeatable testing of prostheses, scientific investigations of joint mechanics and the study of surgical procedures.[1–4] Although Morrey has reported that radial head implants have lower post-operative satisfaction than other joint implants[5] and Dunning has examined several issues with radial heads, many problems remain.[6] It is therefore beneficial to develop a simulator capable of evaluating radial head implants. A robust simulator can also provide the ability to test soft tissue strains at the elbow and compare control schemes that may elucidate the body’s means of controlling multiaxial multimuscle systems.Copyright © 2008 by ASME

In search of a complete understanding of a joint’s function, one must understand both the anatomic parameters and how the brain controls the joint’s actuation. Accurate measurements of anatomical parameters are critical to non-linear biomechanical modeling and control and also to a clinical understanding of orthopaedic reconstruction. Likewise, new frontiers in the study of neuromuscular control contribute to our understanding of joint structure and function. One approach to study joint function is to use a joint simulator to actuate cadaver limbs. Towards the goals of understanding and improving human elbow joint control, a physiologic elbow joint simulator was previously constructed in our laboratory. It is the first elbow simulator to operate completely under closed-loop control. The closed-loop force control used to study joint mechanics permits measurement of moment arms in cadaveric elbow specimens. We hypothesized that the approach yields comparable results to previously-reported moment arm values.[1]Copyright © 2007 by ASME

The many muscles crossing the elbow joint allow for its motions to be created from different combinations of muscular activations. Muscles are strictly contractile elements and the joints they surround rely on varying loads from opposing antagonists for stability and movement. In designing a control system to actuate an elbow in a realistic manner, unidirectional, tendon-like actuation and muscle co-activation must be considered in order to successfully control the elbow’s two degrees of freedom. Also important is the multifunctionality of certain muscles, such as the biceps brachii, which create moments impacting both degrees of freedom: flexion / extension and pronation / supination. This paper seeks to develop and implement control algorithms on an elbow joint motion simulator that actuates cadaveric elbow specimens via four major muscles that cross the elbow joint. The algorithms were validated using an anatomically-realistic mechanical elbow. Clinically-meaningful results, such as the evaluation of radial head implants, can only be obtained under repeatable, realistic conditions; therefore, physiologic motions must be created by the application of appropriate loads. This is achieved by including load control on the muscles’ actuators as well as displacement control on both flexion / extension and supination / pronation.Copyright © 2007 by ASME

Studies indicate that the statistical properties and temporal structure of the sound signal are important in determining the extent of hearing hazard. As part of a pilot study to examine hearing conservation program effectiveness, NIOSH collected noise samples of impact noise sources in an automobile stamping plant, focusing on jobs with peak sound levels (Lpk) of greater than 120 dB. Digital tape recordings of sounds were collected using a Type I Precision Sound Level Meter and microphone connected to a DAT tape recorder. The events were archived and processed as .wav files to extract single events of interest on CD‐R media and CD audio media. A preliminary analysis of sample wavelet files was conducted to characterize each event using metrics such as the number of impulses per unit time, the repetition rate or temporal pattern of these impulses, index of peakedness, crest factor, kurtosis, coefficient of kurtosis, rise time, fall time, and peak time. The spectrum, duration, and inverse of duration for e...