Cristina Herrera Ligero, Enric Medina Ripoll, Úrsula Martínez-Iranzo, Salvador Pitarch Corresa, Ignacio Bermejo Bosch*, Xavier Andrade Celdrán, Juan López Pascual

Instituto de Biomecánica (IBV) Universitat Politècnica de València (Edificio 9C) Camino de Vera s/n (E-46022) Valencia (Spain)

* IBV’s Healhcare Technology Group. CIBER in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN)

NedCodo/IBV is a software application that has been developed by the Institute of Biomechanics (IBV) to assist professionals in the functional assessment of the elbow. Of particular note is its usefulness in the study of such complex pathologies as epicondylosis or lateral epicondylitis. It is a Class I medical device that has been specifically designed to return objective and non-manipulable results of elbow functionality in an agile and simple way.
The results are compared to databases to facilitate interpretation and the decision-making process in relation to therapeutic management and reintegration into the workplace.

INTRODUCTION

On a functional level, the elbow is one of the most important joints in the human body, primarily in terms of manipulation activity. Thanks to its main axes of motion [1], one transverse (flexion-extension) and one longitudinal (pronosupination), the elbow makes it possible to direct and position the hand on the ultimate target of its manipulative action [2].

Elbow pathologies are many and of diverse origin (traumatic, degenerative, inflammatory or neurological, etc. [3]). Each one can, in turn, cause different limitations, affecting specific gestures in each case. Because of its high prevalence, one of the most important causes of elbow pain is lateral epicondylitis (also referred to as epicondylosis due to the type of tendon injury that causes the condition [4,5]). This condition is especially relevant in the occupational sphere, given its association with physical risk factors, such as the handling of tools or repetitive motions of the upper limbs. Among other things, it often affects the grip strength of the hand.

Despite the existence of complementary tests that reveal the underlying structural lesions of a pathology, a discrepancy sometimes exists between the pain or the limitation reported by the patient and these lesions. In this way, biomechanical assessment becomes an objective tool for evaluating the real repercussions caused to the subject's functionality by the pathology, and proves useful:

• In supporting the diagnosis of musculoskeletal disorders in accordance with the functional pattern.

• In evaluating the severity, extent or nature of an illness or injury, from the point of view of the disability it causes.

• In following up on treatments and/or supporting the selection of the most appropriate one depending on the pathology.

• In assessing the individual's capacity and support in making decisions related to his or her job.

• In predicting the results of a specific intervention.

In summary, biomechanical assessment of the elbow can assist in the planning of rehabilitation treatments and can provide information for decision making in the treatment of the patient. The purpose of this article is to put forward an assessment system based on the evaluation of different functions and activities of the upper limb, so that it becomes possible to select those most appropriate for assessing a particular pathology, including lateral epicondylitis.

NedCodo/IBV Objectives

The objective of NedCodo/IBV is to offer an intuitive, agile, objective and reliable method of assessing the functionality of the elbow that allows decisions to be taken on the follow-up, treatment and functional assessment of patients, in line with the main needs detected in the socio-health sector.

DESCRIPTION OF NedCodo/IBV

NedCodo/IBV offers a quantitative and objective assessment of elbow functionality, both from a dynamic and kinematic point of view. To this end, it generates assessment indexes that make it possible to evaluate the extent of the patient’s functional limitation. NedCodo/IBV is a class I medical device. 

The most relevant aspects of the NedCodo/IBV system are described below:

Data recording

For the assessment, NedCodo/IBV requires a motion analysis system that uses photogrammetry and a compatible isometric dynamometry system that makes it possible to obtain both kinematic and dynamic information during the performance of different gestures that may be affected by the elbow pathology.

A model of upper limb markers has been developed, based on the axes described by the International Society for Biomechanics (ISB, [6]), but avoiding the use of markers that, due to their location, give rise to problems of concealment [7]. The design criteria for the model were as follows:

• Reduced number of markers (n=10)

• Avoidance of marker concealment

• Scalable

• Simplicity in patient instrumentation.

• Provision of relevant information.

Test protocol

Elbow alterations can be very diverse and, for that reason, the assessment protocol consists of various gestures that can be selected depending on the type of pathology and the objective of the assessment.

The test protocol (Figure 1) consists of loaded mobility tests, including maximum flexion-extension and pronosupination tests [8,9,10], as well as the assessment of reach activity with different loads [11,12] and strength tests, including grip strength and fatigue in different positions [13,14,15], as well as pronosupination strength tests [16,17,18]. To facilitate the choice of the most suitable tests in each case, NedCodo/IBV provides a system for recommending and selecting tests (see section on “Computer Application and Reports”).

It should be noted that the patient can be prepared for this test in less than 2 minutes, and that both this process and the execution and recording of the gestures described above are remarkably simple. In this regard, the selected marker model has made it possible to improve the agility of the assessment process.

Figure 1: from left to right, flexion-extension test, pronosupination, reach and grip strength in elbow flexion and extension.

Data processing

NedCodo/IBV obtains the most relevant parameters produced by the assessment of different gestures. After various statistical analyses, the parameters that made it possible to draw significant distinctions between different groups of subjects were selected. Among these selected parameters, the following stand out:

Kinematic parameters:

• Flexion-extension and pronosupination range: elbow and forearm range of motion during the execution of the gesture. It is expressed in degrees (°) and as a percentage of normality.

• Maximum Speed: Maximum angular speed during the execution of the gesture. It is expressed in degrees per second (°/s) and as a percentage of normality.

• Maximum Acceleration: Maximum angular acceleration during the execution of the gesture. It is expressed in degrees per second squared (°/s^²) and as a percentage of normality.

• Repeatability: Similarity between the cycles carried out when making the same gesture, calculated from the angular speed curves. It is expressed as a percentage of normality.

Dynamic parameters:

• Maximum strength: the maximum value of the strength applied during the repetitions of the gesture in question. It is expressed in Newtons (N) and as a percentage of normality.

• Average strength: the average of the maximum strength values obtained for a given gesture. It is expressed in Newtons (N) and as a percentage of normality.

• IPF1 (Contralateral). Loss of Strength Index 1: the percentage of loss of strength of the injured side with respect to the contralateral, for that same motion or gesture. It is expressed as a percentage and as a percentage of normality. It is calculated using the following formula:

• IPF2 (Normality). Loss of Strength Index 2: the percentage of loss of strength of the injured side with respect to that of the same side of dominance in a database of normality (database of normality/IBV segmented by age, sex and dominance), for that same motion or gesture. It is expressed as a percentage and as a percentage of normality. It is calculated using the following formula:

• Fatigue Index: expresses the percentage of reduction in isometric force during a 30-second fatigue test compared to a hypothetical maximum voluntary contraction of 100% without fatigue. It is expressed as a percentage value and as a percentage of normality.

Others:

• Symmetry: It compares all the analyzed parameters bilaterally. It is expressed as a percentage of normality.

• Coefficient of variation: reflects the percentage relationship between the standard deviation and the average of the maximum strength values obtained in the repetitions under consideration. It is calculated on the basis of dominance. It is also expressed as a percentage of normality.

Finally, we have generated classification algorithms that facilitate the interpretation of NedCodo/IBV results from a database of healthy, pathological and simulator subjects. In this way, NedCodo/IBV automatically generates the following overall results:

• Normality Index: This index allows us to quickly and objectively determine if the patient presents an alteration in the joint and muscle function of the elbow based on the parameters obtained during the execution of different gestures.

• Collaboration Index: the result of the classification algorithm between the database of normal, pathological and simulator subjects. This value helps to determine whether the patient has made an effort compatible with his or her possibilities in the gestures requested by the assessor.

Computer application and reports

The NedCodo/IBV computer application has been developed with the aim of facilitating the work of professionals and guaranteeing the correct application of the methodology and the interpretation of the results. To achieve our goal, the software application guides the user through the various processes: test selection, executing the protocol, and the analysis of the results.

With regard to the selection of tests, NedCodo/IBV offers the most recommendable ones to the user, in accordance with the clinical situation of the patient; in this way we manage to streamline the assessment process in a simple way and without losing any key information.

The results of the assessment offered by NedCodo/IBV are automatic, non-manipulable, and in real time (Figure 2). In addition, once the valuation has been completed, the application allows the user to generate reports automatically in MS Word and PDF formats, to speed up the work of the health professional.

Figure 2: Example of a results screen showing a functional assessment of an elbow using the NedCodo/IBV system.  Results of the loaded mobility tests.

Commissioning

The Institute of Biomechanics (IBV) handles the installation of the product and provides training on how to use the application, execute the protocol, interpret the results, and write reports. Similarly, the Institute of Biomechanics (IBV) offers a continuous technical and methodological consultancy service that includes the implementation of audits that ensure that the protocols are properly executed and that the system works correctly.

BENEFITS OF NedCodo/IBV

• Agility:Carrying out an assessment with NedCodo/IBV can take between 20 and 45 minutes depending on the number of tests selected by the assessor. A report is obtained automatically. The reports are specially designed to allow the professional to spend time on what really matters, the patients.

• Simplicity: Training for professionals, the software application, the system for recommending and selecting tests and the assessment indexes allow for easy and simple handling and interpretation of the information provided by the NedCodo/IBV application.

• Scientific validity: studies have demonstrated the reliability and validity of NedCodo/IBV for the assessment of functionality in an elbow pathology.

ACKNOWLEDGEMENTS

Our thanks go to the mutual insurance companies that collaborate with the Social Security and have participated in the initial definition of needs (Mutua Navarra, Mutualia, Umivale, Ibermutua, Asepeyo, Egarsat and MAZ) and in the pilot experiences carried out during the project (Ibermutua, Umivale), without whose collaboration the development of NedCodo/IBV would not have been possible.

REFERENCES

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