Predictive value of the pendulum test for assessing knee extensor spasticity

So fucking what about predictions? We want solutions, not this lazy crapola. Does no one understand the only goal in stroke? It is incredibly simple; 100% recovery.  Prediction does nothing for that goal.

Predictive value of the pendulum test for assessing knee extensor spasticity

• Alyssa Whelan,
• Andrew Sexton,
• Melony Jones,
• Colleen O’Connell and
• Chris A. McGibbonEmail authorView ORCID ID profile

Journal of NeuroEngineering and Rehabilitation201815:68

https://doi.org/10.1186/s12984-018-0411-x

©  The Author(s). 2018

• Received: 10 January 2018
• Accepted: 5 July 2018
• Published: 18 July 2018

Abstract

Background

The pendulum test is commonly used to quantify knee extensor spasticity, but it is currently unknown to what extent common pendulum test metrics can detect spasticity in patients with neurological injury or disease, and if the presence of flexor spasticity influences the test outcomes.

Methods

A retrospective analysis was conducted on 131 knees, from 93 patients, across four different patient cohorts. Clinical data included Modified Ashworth Scale (MAS) scores for knee extensors and flexors, and years since diagnosis. BioTone™ measures included extensor strength, passive and active range of motion, and pendulum tests of most affected or both knees. Pendulum test metrics included the relaxation index (RI), 1st flexion amplitude (F1amp) and plateau angle (Plat), where RI=F1amp/Plat. Two-way ANOVA tests were used to determine if pendulum test metrics were influenced by the degree of knee flexor spasticity graded by the MAS, and ANCOVA was used to test for confounding effects of age, years since injury, strength and range of motion (ROM). In order to identify the best pendulum test metrics, Receiver Operator Characteristic analysis and logistic regression (LR) analysis were used to classify knees by spasticity status (none or any) and severity (low/moderate or high/severe).

Results

Pendulum test metrics for knee extensors were not influenced by degree of flexor spasticity, age, years since injury, strength or ROM of the limb. RI, F1amp and Plat were > 70% accurate in classifying knees by presence of clinical spasticity (from the MAS), but were less accurate (< 70%) for grading spasticity level. The best classification accuracy was obtained using F1amp and Plat independently in the model rather than using RI alone.

Conclusions

We conclude that the pendulum test has good predictive value for detecting the presence of extensor spasticity, independent of the existence of flexor spasticity. However, the ability to grade spasticity level as measured by MAS using the RI and/or F1amp may be limited. Further study is warranted to explore if the pendulum test is suitable for quantifying more severe spasticity.

Keywords

• Spasticity
• Knee extensor
• Knee flexor
• Pendulum test
• Relaxation index
• Modified Ashworth scale
• Classification
• Logistic regression
• Receiver operator characteristic

Background

Muscle spasticity can be a painful and debilitating complication that negatively impacts function and quality of life in people with upper motor neuron injury from neurological disease or trauma [1], such as acquired brain injury (trauma, stroke), cerebral palsy, multiple sclerosis and spinal cord injury. Management of spasticity typically involves pharmacologic intervention a

nd/or ongoing physical therapy [2, 3], but a significant barrier to effective treatment prescription is the inability to quantify spasticity in the clinic [4].

Spasticity is typically assessed by inducing a rapid stretch of the muscle, or administering a “stretch-reflex” test. Clinical tests such as the Modified Ashworth Scale [5] and Tardieu Scale [6] apply this method to quantify spasticity subjectively, but their inter-rater reliability [7, 8, 9, 10] and validity [11] have been questioned. Several studies have examined objective approaches to quantifying spasticity in the clinic using wearable sensor technologies during passive muscle stretches [9, 12, 13, 14, 15], but there is not yet a clear consensus on testing protocol and how to best translate the resulting electrophysiological and biomechanical signals into clinically relevant measures of spasticity. As such, the Modified Ashworth Scale remains a commonly used method of quantifying spasticity in clinical settings.

For the knee joint, the Wartenberg pendulum test [16] offers a potential solution for translation to clinical assessment. The pendulum test offers a simple approach whereby gravity induces the stretch-reflex of knee muscles by dropping the lower-leg from a resting horizontal position, and observing its oscillatory behavior throughout the passive movement [17, 18]. The test’s easy implementation and execution with commonly available sensors (e.g. electromyography with video [19], goniometry [20, 21], and other accessible devices such as the Wii remote [22]) has contributed to it emerging as an objective and reliable way to quantify spasticity in the knee extensors [17, 23, 24, 25]. Nevertheless, there is still a lack of consensus on what pendulum test metrics are most relevant to clinical spasticity assessment, and importantly, whether the pendulum test is sensitive to knee flexor spasticity. Thus the purpose of this study was two-fold:

1. 1)
   To determine if the measurement of extensor spasticity is influenced by flexor spasticity during the pendulum test in patients with neurological injury or disease; and
2. 2)
   To determine which pendulum test metrics are the closest indicators of clinical muscle spasticity, as represented by the Modified Ashworth Scale (MAS).

Methods

This is a retrospective analysis of knee spasticity measurement data from a multi-site study to evaluate wearable sensor-based systems for acquiring objective measures of muscle tone in the clinic.