Arthrometers Provide Objective Data in Orthopedics


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Arthrometers Provide Objective Data in Orthopedics



Mobil-Aider DeviceOrthopedics is about precision. Decisions should be based on objective data. In the 1980’s, Med Metrics Corp. Inc. developed a knee arthrometer called the KT1000. For the first time, injury to the anterior cruciate ligament (ACL) could be quantified. The device paved the way for a plethora of research studies and enhanced understanding of the magnitude of translation that defined pathology. With the KT1000 off the market since 2012, little has been done to develop an arthrometer for the knee or any other joints.  In 2021, the Mobil-Aider entered the market and has begun to populate the literature. 



Mobil-Aider kneeFor the knee, MRI’s have been the gold standard for ACL diagnosis but MRI’s are expensive and are static images. Arthrometers provide dynamic data.  A study with the Mobil-Aider on individuals with ACL injuries successfully quantified the magnitude of laxity.  It has identified partial and complete ACL tears can be identified when the difference between knees is 2.05 mm and 3.38 mm, respectively. This is consistent with numerous studies using the KT1000 (2-3 mm partial; 3-4 mm complete). 


Ankle Anterior Drawer in Prone


For the ankle, anterior talofibular ligament arthrometer testing has found a 1.11 mm difference was consistent with a 1° sprain and 2.16 mm difference indicated a 2° sprain. These values correspond with numerous studies using stress radiographs and can significantly impact the treatment decision.  Being able to differentiate between a grade 1 and grade 2 sprain can help drive clinical decision making regarding treatment.  A measure of 1.11 mm versus 2.16 mm can be the difference between recommending an aircast or a boot.

Likewise, the Mobil-Aider Arthrometer has also been used to test  shoulder mobility and was found to have a 0.83 correlation with electro-magnetic motion analysis.  It has also been found to have strong intra-rater reliability.  For glenohumeral posterior glides it was 0.771 and for radiocarpal volar glides it was found to be 0.904.


Thus, there is technology available to provide objective data on joint laxity that fills the void between subjective assessment and expensive imaging. In addition, by capturing objective data, the use of an arthrometer is eligible for insurance re-imbursement using a 97750 code.  For more information on arthrometry testing visit:   or email


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