(Digital Presentation) Biosensors Optimizing Measurement of the Multidirectional Knee Dynamic Mobility, and Clinical Assessment of Joint Instabilities
Authors: Sanchez Jose Ignacio 
Published: November 2022

The knee is a complex joint, with intrinsic and extrinsic stability mechanisms, as well as a complex muscular interaction that allows controlled mobility during gait, and since it is a weight-bearing joint, its function is directly subject to the development of the knee. gait as a physiological action, therefore the assessment of the knee as part of gait is essential for the understanding of mobility in the 3 planes of movement dynamically, as well as the alterations that can occur due to structural injuries of the knee, as well as gait due to muscular or neuromuscular alteration.

One of the most frequent traumatic injuries in the general population and therefore with great impact on normal gait is the anterior cruciate ligament injury in the knee, and since these injuries can have sequelae during the rest of life they are of great Importance, the incidence of these injuries is estimated at 200,000 cases per year in the United States, and since few countries keep systemic incidence records, these data are not local, but in these countries the incidence is Germany 32 per 100,000 and 29 per 100.00 in USA (Singh, 2018). In addition, ruptures may occur in the same individuals, which are attributed mainly to incomplete diagnoses with poor characterization of the injury, or the instability that it produced, and therefore incomplete treatment of the injury, errors in surgical technique, or an insufficient rehabilitation with lack of strength (Csintalan, 2008).

The evaluation of gait alterations is carried out in 2 diametrically opposed environments, the first one is research, where assessment is carried out with tools such as gait analysis or dynamic goniometry, and the second one is the clinical environment, where it is done a subjective and poorly standardized assessment that does not allow adequate integration of diagnosis and treatment.

Joint stability assessment and diagnosis strategies are found in a wide range of options, from the assessment of subjective parameters, referred by the patient, static and passive measurements of joint laxity, or postural balance tests (Hatfield, Hammond, & Hunt, 2015), but none of these strategies allows a quantification of stability during activities such as walking (Knoop et al., 2012). Gait analysis allows assessment of knee function and estimating joint stability (Protopapadaki, Drechsler, Cramp, Coutts, & Scott, 2007).

The interpretation of joint mobility implies a challenge since analyzing joint dynamics in vivo requires invasive methods, also in joints such as the knee that have intrinsic and extrinsic stability mechanisms, as well as involuntary compensatory mechanisms, which depend on the supported nervous system (Van Tunen et al., 2018).

Assessing the joint stability of the knee in clinical practice, and research scenarios, is widely supported by the subjective instability reported by patients, this symptom, although subjective, is one that is related to gait disturbances, due to pain, and instability (Schrijvers et al., 2019), however, the lack of generally accepted parameters for assessing stability makes it difficult to compare results between studies (Farrokhi et al., 2014).

The implementation of biosensors, to improve and simplify the Knee movement and clinical assessment has a potential huge impact in the clinical environment due to its high incidence, and on the cost to the Health system not only because the proposed system is inexpensive, but also because of the high incidence of underdiagnosis as a frequent cause of surgery failure.

Contrasting all these perspectives (Ahldén et al., 2012) indicates that one of the biggest problems is the lack of a gold standard, since clinical manual evaluation is the basis for diagnosis and treatment, but is subjective in interpretation and performance, and the integration of different dynamic analysis models have not provided a standardized, validated and reproducible pattern.

The objective of this study was to assess an electro goniometer used combining different biosensors including a multidirectional electro goniometry and surface electromyography to allow an evaluation not only of the movement and displacement of the knee, in a wholesome manner, but also have information about compensation mechanisms, and reflex and involuntary activation of the quadriceps, and How efficient it is, which will help evaluate not only the instability itself but also when it is successfully compensated and when it should be necessary a surgical intervention.

The interaction between multiple biosensors allows us to get a reading that is not only dynamic but also more accurate and allows assessment of different activities, and a better comprehension of the individual evaluation of each knee, and different instability patterns due to the multiple possible combination of simultaneous ligamentary, chondral, meniscal, and capsular injuries.