Document Detail

Relative motion of a mobile bearing inlay after total knee arthroplasty--dynamic in vitro study.
MedLine Citation:
PMID:  11779646     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: The purpose of this study was to measure the in vitro range of motion of a mobile bearing inlay knee prosthesis under dynamic isokinetic loading conditions. Additionally, the effect on the range of motion of rotational malalignment of the tibia baseplate was determined. DESIGN: Specimens with implanted knee prostheses were mounted onto a custom built knee simulator. 3-D inlay movement was measured by an ultrasonic tracking system. BACKGROUND: More recent knee prostheses include mobile bearing inlays type designs. These systems are intended to allow higher conformity of the tibiofemoral joint and thereby decrease contact stress without decreasing the knee's range of motion. METHODS: Dynamic testing in the knee simulator mimicked both the speed and resulting moment of a knee isokinetic extension test. The tibia baseplate was first implanted with no rotational malalignment, followed by sequential internal and external rotation of upto 15 degrees. RESULTS: Correctly aligned, the inlay center moved 3.5 mm (SD, 1.5 mm) posterior during extension. With the tibia baseplate externally rotated more than 10 degrees the movement pattern changed. CONCLUSION: At up to 10 degrees of rotational malalignment the primary motion pattern of the mobile bearing is maintained. However, beyond 10 degrees unintended motion may occur. RELEVANCE: These test results correlate to radiographic measurements of in vivo movements of mobile bearing inlays showing "paradoxical" movement of the mobile inlay compared to physiologic meniscal movement.
C Stukenborg-Colsman; S Ostermeier; K H Wenger; C J Wirth
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Clinical biomechanics (Bristol, Avon)     Volume:  17     ISSN:  0268-0033     ISO Abbreviation:  Clin Biomech (Bristol, Avon)     Publication Date:  2002 Jan 
Date Detail:
Created Date:  2002-01-07     Completed Date:  2002-03-19     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8611877     Medline TA:  Clin Biomech (Bristol, Avon)     Country:  England    
Other Details:
Languages:  eng     Pagination:  49-55     Citation Subset:  IM    
Orthopaedics Department, Hannover Medical School, Heimchenstr. 1-7, 30625, Hannover, Germany
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MeSH Terms
Knee Joint / physiology*
Knee Prosthesis*
Middle Aged
Prosthesis Design
Range of Motion, Articular
Statistics, Nonparametric
Stress, Mechanical
Tibia / physiology*
Weight-Bearing / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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