MEDmetric® Corporation
The
KT1000 was developed to provide objective measurement of the sagittal
plane motions of the tibia relative to the femur. This motion, sometimes
referred to as drawer motion, occurs when an examiner applies force to
the lower limb or when the muscles of the quadriceps are contracted. Both
the KT1000 and KT2000 models of the Knee Ligament ARTHROMETER®
accurate, easy-to-use instruments for the clinical assessment of ACL and
PCL integrity.
The MEDmetric® Knee Ligament ARTHROMETER® was first available, most used, and most accurate knee ligament testing system manufactured, a claim supported by the many published scientific papers and articles produced using data collected with the KT1000 and KT2000.
The KT1000, first introduced in 1982, is the product of research and development beginning prior to 1979. Orthopedic surgeon Dale M. Daniel, M.D., devised schemes for instrumenting knee articulation and, with the collaboration of MEDmetric® founder Lawrence L. Malcom, Ph.D., developed three distinct prototypical models which evolved finally to the portable form of the instrument as it exists today.
Since the Knee Ligament ARTHROMETER® was designed for the orthopedic practitioner, the instrument allows the examiner easily to screen acute knee injuries and quantitatively document anterior-posterior knee measurability in the office or clinical setting.
The Knee Ligament ARTHROMETER® was designed to overcome problems commonly encountered when attempting to perform a 25° displacement measurement on a large, well muscled, or obese patient. This was accomplished by supporting both things with a firm, comfortable platform placed proximal to the popliteal space. This helps keep the patient's knee flexion angle constant throughout the test. A foot support accessory, supplied with all ARTHROMETERs®, positions the feet symmetrically, allowing optimal leg positioning for the test while reducing external rotation of the tibia.
The patient seems to relax and in general react
favorably to an ACL stability examination done with an ARTHROMETER®.
The flexion angle of the test, which is between 20° and 35°, is
usually the most comfortable position for an acute knee injury. A thigh
strap (provided) controls external hip rotation and offers support that
encourages patient relaxation. Since both legs are lying on a stable thigh
support platform, the patient can relax and will exhibit less apprehension
during the test.
Design improvements are
continually incorporated which enhance the accuracy, reliability and
durability of the KT devices.
As significant improvements or new features are developed, you will be
notified and given the
opportunity to upgrade your instrument. Your KT device need never be
obsolete.
Although the ARTHROMETER® is easy to use and examinations may be performed quickly, a reliable and reproducible technique, requiring study and practice, must be developed. A modest commitment of time is needed to acquire a further understanding of knee mechanics and to develop a good testing procedure. The support materials supplied are intended to assist examiners in their efforts. Regional Knee Ligament ARTHROMETER® workshops are conducted from time to time; we encourage you to attend if possible. Alternatively, we suggest that you network with KT device users in your area and spend time with examiners who have a developed technique. MEDmetric® Corporation phone support is also available for your convenience. (858) 536-9122
Instrumentation
ARTHROMETER®
Model KT1000.
A self-contained anterior/posterior tibiofemoral displacement measuring
instrument. Features electronic, audible force level indicators at 15,
20, and 30 pounds anterior and posterior. Powered by two standard
nine-volt batteries. Instrument weight: 4.6 pounds.
A - Distal Velcro Strap
B - Battery Compartment Door
C - Proximal Velcro Strap
D - Force Handle
E - Displacement Dial
F - Patella Sensor Adjustment Dial
G - Patella Sensor Pad
H - Joint Line Arrow
I - Tibia Sensor Pad
Adjustable Thigh Support Platform. Stabilizes knees at 20° to 35° of flexion. Adjusts to accommodate patients of varying heights. Also available separately for use in physical exams. MRI-safe.
Thigh Strap. Autoclaveable, three-inch wide Velcro strap to stabilize external rotation of the tibia.
Foot Support Platform.
Stabilizes foot position to orient tibia.
Reference, Maintenance and Users Guide. Detailed description of ARTHROMETER® operation, including illustrated, step-by-step instructions for use and standard testing protocol.
Patient Evaluation Forms. With spaces for recording measurement results.
Published Clinical Studies. A guide to clinical knee stability results that have been obtained with the ARTHROMETER®.
Goniometer. For measurement of knee flexion angle.
Carrying Case. Rugged case with contoured foam interior holds the ARTHROMETER® and all accessories.
Benefits of using the KT1000
§ There is no anesthesia risk.
§ The patient undergoes no x-ray exposure.
§ Due to patient comfort, there is minimal muscle guarding.
§ It is inexpensive when compared to x-ray, MRI or CT scan testing.
§ Ease of Testing Large Patients
§ Contributes to Patient Relaxation
§ Improvements, Upgrades and Retrofits
Over the years, MEDmetric® has modified the Knee Ligament ARTHROMETER® and its accessories to improve performance. The information in this guide reflects the KT1000 and KT2000 as of October 1996. Among the differences found in earlier model KTs are:
§ Hall Effect Retrofit (ARTHROMETERs® with serial numbers below 186). The earliest KT models required periodic adjustment or re-calibration of force tones. The Hall Effect Retrofit eliminated the need for scheduled service.
§ Thigh Strap (KT serial number 200). The strap was introduced to resist external limb rotation during ACL testing at 20° to 35° of flexion.
§ 30 lb. Force Tone. The original KT1000 design incorporated two anterior force levels: 15 lbs. and 20 lbs. A 30 lb. force tone was later incorporated to add test sensitivity for well muscled or large patients.
§ Adjustable Thigh Support. The thigh support for current production ARTHROMETERs® is adjustable in three steps for short, medium and tall subjects. The new thigh support is MRI safe since it has no metal components.
§ Posterior Force Tones. KT2000 (serial number 455 and higher) and the newest KT1000 units emit force tones when 15, 20, and 30 pounds of force is applied posteriorly. Earlier KT1000 devices featured posterior force tones at 15 and 20 pounds; previous KT2000 units enuciated a tone at 20 pounds of posterior force only.
§ Force Tone Shutdown. When batteries are weak, new KT2000 units (Serial Number 327 and higher) cease enunciating force tones. This is an indication that batteries must be changed in order to maintain plotter/computer output accuracy.
Factory installed retrofits and upgrades are available
for all Knee Ligament ARTHROMETERs®. To find the serial
number of your KT, examine the metal plate affixed to the bottom of your
Knee Ligament ARTHROMETER®.
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