Bob's ACL WWWBoard On-Line Knee Library |
Click here to return to the subsection Knee-Injury Diagnostics.
Click here to return to the subsection
Textbook Chapters, Conference Proceedings, and Other
Resources.
For a brief overview of knee anatomy, physiology, biomechanics, and terminology, please click here.
------
Document Title: Paine-EKLR-Ch04-2000.shtml
Article Title: Instrumented Examination
Author: Russell M. Paine, PT,
and Ron M. Johnson, PT, MPT, ATC, LAT, CSCS
Publication: Knee Ligament Rehabilitation, edited by Todd S. Ellenbecker.
Philadelphia, Pennsylvania: Churchill Livingstone (Harcourt), 2000. (This book has 51 contributing authors and 465 pages.)
Pages: 40-69
Keywords: Knee-injury diagnostics, ligament tests, manual drawer testing, Lachmann drawer test, anterior-drawer test, posterior-drawer test, valgus-stress stress, varus-stress test, pivot-shift test, dynamometer, Cybex, Biodex, Kin-Com, KT-1000/2000, KLT.
(Reference-denoting numbers appear in the same font and point size as the document text. As with all Knee Library documents, this article is provided in full-text form, complete with all figures and tables. Although this article has been published as a book chapter, it can be read independently of the other chapters in the book. Other chapters from this book can be found here.)
Comments: This chapter/article is a must-read for anyone who has been examined via knee-arthrometer instruments. Instruments are very helpful in providing reproducible measurements of knee laxity and hence injury to ligaments, but they must be used properly. The authors note that the person doing the examination must be well-experienced. (This caveat also applies to manual-manipulation tests, as done by hand by a seasoned orthopedic professional. Instruments such as those described in this chapter should only be used as an adjunct to manual-manipulation testing.) The most widely used device, the basic KT-1000/2000 from MedMetric, should only be considered accurate if the person doing the testing has had at least a month's worth of experience in using it. Similar precautions apply to other knee-ligament laxity testers such as the KLT, Genucom, Dyonics DCT, and UCLA-ICKTA devices. Meanwhile, a stationary dynamometer (e.g. Biodex, Cybex, Kin-Com), a sophisticated and highly automated machine which measures kinematic parameters and which very nicely quantifies strength and endurance, but does not directly measure knee-ligament laxity, can bring good accuracy and reproducibility without making a lot of demands on the clinician's skills. (Dynamometers are very expensive machines, and many take up a lot of space. The ones described herein are designed for durability and longevity. Properly maintained, these units can last for decades. The dynamometers described in this chapter date from the mid-1990s, and so the computerized aspects of the units specified will appear out-of-date today. However, the basic mechanical and electromechanical aspects will remain the same in newer units. Many dynamometers have been upgraded to reflect the ongoing advances in computer capabilities.) Newer devices, such as those involving force plates (e.g. from AMTI or Kistler) and three-dimensional optical-marker-tracking systems (e.g. from Northern Digital), are also helpful for ascertaining biomechanical parameters and for measuring rehabilitation progress and determining areas needing improvement.
Please note that, with anything from a portable ligament-laxity tester to a high-tech dynamometer, test results can be affected by various factors, including recent exercise and time of day. In any case, there is a lot to think about when looking at results from these devices. It is always appropriate to compare the affected (injured) knee to the contralateral (presumed uninjured) knee, and to report laxities in the form of side-to-side differences instead of absolute values. Muscle-strength patterns should also be benchmarked to the uninjured side. (Things become more complicated if the person has bilateral knee injuries, since the absence of an uninjured knee makes it impossible to report a meaningful side-to-side difference.) If a person is tested using one of these instruments, and if the machine indicates that the knee is okay but other signs and symptoms, for example instability, swelling, history of giving-way, documented violent abnormal forcing to the knee (e.g. in a football injury caught on videotape), and/or observed abnormal movement of the knee (e.g. the knee was seen to hyperextend grotesquely) indicate otherwise, then it is clear that further investigation (e.g. arthroscopic examination) is warranted. The authors also touch on the topic of evaluation under anesthesia, and note that lingering muscle tenseness (common after any knee injury) can mask ligamentous deficiencies. (This same problem also affects manual-manipulation testing.) Note, too, that useful information can sometimes be obtained from MRI scans; however, remember that MRI scans are not always accurate with regards to knee-ligament injuries. Finally, the authors also discuss isokinetic dynamometers, as used to evaluate dynamic muscular performance and thereby to quantify rehabilitation progress.
Note: Appendices follow reference listing.
- - - - - - -
Introduction
Currently, measuring outcomes is at the forefront of the changing health-care environment. As we progress toward measures of functional outcomes, techniques and tools for recording data continue to be developed. To document these outcome measures, commercially available instrumented testing devices have been used to objectively quantify various biomechanical and kinematic characteristics of the knee.
To date, knee ligament arthrometers have been the predominantly used devices in instrumented testing. These arthrometers attempt to objectively measure in millimeters the various diagnostic knee examination tests, the results of which were previously quantified by a grading system. The development of isokinetic testing dynamometers has made it possible to objectively quantify knee muscular characteristics and predict possible functional limitations of the knee in ligamentous disorders. Finally, a new instrumented device called the Functional Active System for Testing and Exercise (FASTEX) has been introduced that offers the capability of quantifiably measuring functional lower extremity tests.
The purpose of this chapter is to provide an overview of instrumented testing and provide specific clinical techniques that may be useful in obtaining reproducible and accurate results during an instrumented testing examination. The less inherent margin for error a device has, the greater its reliability will be. As is true with any instrument that has been proven to be reliable, its reliability is totally dependent on the expertise of the examiner.
To access the full text of this article, please click here.
There is no charge for viewing articles. However, a password is required.
If you do not already have a password, please e-mail Michael Frind at frind@execulink.com for one.
Prior to requesting a password, please make certain you have read the
Site Terms of Use
pertaining to this site.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Copyright Churchill Livingstone, 2000. For details regarding copyright as it applies to this page, please visit the page entitled Site Terms of Use and Aspects of Copyright on this site.
This website was created for the benefit of the world's largest knee-injury community, Bob's ACL WWWBoard (also known as the Kneeboard), accessible to everyone at http://factotem.org.
Documents posted on this site serve merely as a virtual library, and are intended solely for purposes of making access to high-quality peer-reviewed medical-journal articles convenient for all users of the Kneeboard. Knee-injury patients are hereby encouraged to discuss this material with their respective medical teams.
Click here to return to the Main Entrance Page of the Knee Library.
Looking for the Main Index Page of Bob's ACL WWWBoard? Click here!
To find recent postings on Bob's ACL WWWBoard, use the Search Engine.
To find older postings on Bob's ACL WWWBoard, use the On-Line Archive.
Site Terms of Use and Aspects of Copyright