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 Table of Contents  
Year : 2019  |  Volume : 2  |  Issue : 2  |  Page : 35-40

3.3 Physical and rehabilitation medicine clinical scope: Medical diagnostic tools

1 Department of Mental and Physical Health and Preventive Medicine, University of Campania “Luigi Vanvitelli,” Naples, Italy
2 Department of Medical and Surgical Specialties and Dentistry, University of Campania “Luigi Vanvitelli,” Naples, Italy

Date of Web Publication11-Jun-2019

Correspondence Address:
Prof. Francesca Gimigliano
Department of Mental and Physical Health and Preventive Medicine, University of Campania “Luigi Vanvitelli,” Naples
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jisprm.jisprm_11_19

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How to cite this article:
Gimigliano F, Iolascon G. 3.3 Physical and rehabilitation medicine clinical scope: Medical diagnostic tools. J Int Soc Phys Rehabil Med 2019;2, Suppl S1:35-40

How to cite this URL:
Gimigliano F, Iolascon G. 3.3 Physical and rehabilitation medicine clinical scope: Medical diagnostic tools. J Int Soc Phys Rehabil Med [serial online] 2019 [cited 2019 Sep 15];2, Suppl S1:35-40. Available from: http://www.jisprm.org/text.asp?2019/2/2/35/259337

  Introduction Top

A detailed functional assessment of a patient is fundamental before a rehabilitation plan is put together. There are many different scales that can be used to measure different aspects of functioning [Table 1] along with diagnostic tools that, if well used, can rapidly define a patient's health condition and level of functioning.
Table 1: Most commonly used scales in different areas of assessment

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  Algometer Top

Pain is usually measured with pain rating scales, and considering its subjective nature, patients' responses vary depending on how they react to environmental, psychological, and physical influences.

Algometers are tools which are able to quantify both the levels of tenderness and pain sensitivity. They are made of a very sensitive mechanical or digital gauge that measures the forces applied to the patient. Results are typically reported as pressure pain threshold, that is, the minimal amount of pressure that produces pain.[1] Even though the subjective nature of pain does not allow any real objective measurement, algometry has been shown to be a reliable way to document pain intensity.[2]

  Goniometer, Electrogoniometer, Inclinometer Top

The measurement of the range of motion (ROM) is commonly performed with standard plastic goniometers, but nowadays, electronic tools are available and have made it possible to measure joints' angles during dynamic movements and in more than one plane of motion simultaneously. Electrogoniometers convert angles to voltage and can use resistive or microelectromechanical inertial sensors. A recent systematic review comparing electrogoniometers with three-dimensional video analysis systems concluded that electrogoniometers can be cost-effective and capable to collect data in a standard environment.[3] A limitation of these tools might be the difficulty in placing the sensors in case of misalignment of the joint or their slippage during movement.

Inclinometers are tools specifically designed to assess the ROM of the spine. The most common ones are manually held by the evaluator on the back of the patient while he/she is bending forward. An electronic evolution of the inclinometer is made by a portable dual-axis accelerometer system that can also capture extreme trunk postural data in occupational settings.[4]

  Dynamometer Top

Muscle strength is usually clinically assessed with the manual muscle test[5] with good inter-rater reliability in trained examiners.[6] However, this method fails to differentiate among patients with various degrees of muscle weakness compared with more objective methods such as isokinetic dynamometry and hand-grip dynamometer (HGD) or knee extension dynamometer (KED).[7] Both HGD and KED have been used to assess the overall limb muscle strength of individuals.

Isokinetic dynamometers are computerized machines which can measure power, endurance, peak force, maximal force angle, and other elements of muscle strength.[8] They are considered reliable and valid to assess muscle strength.[9]

Although isokinetic dynamometry is considered the gold standard in measuring muscle strength, in daily clinical practice, HGD and KED are more commonly used as they are portable, small, minimally time-consuming, and relatively inexpensive.[10]

  Myotonometer Top

The most commonly used clinical tests to assess muscle tone are the Ashworth Scale and the Modified Ashworth Scale.[11] In addition, muscle tone can be measured using a myotonometer, an electronic device that, using a probe to make a pressure into the skin overlying a muscle, is able to quantify the tissue displacement per unit of force applied. The reliability of the myotonometer for the measurement of skeletal muscle viscoelastic parameters in healthy controls and in several clinical conditions has been investigated.[12],[13],[14],[15]

  Electroneuromyography Top

The electroneuromyography (ENMG), also known as electrodiagnosis, is a neurophysiological method used to study neuromuscular and muscle diseases, and it is the only diagnostic tool which is able to examine the peripheral nervous system. It is always meant to be complementary to the clinical examination, and it is fundamental to identify the location, type, and extent of the damage. The examination can be divided into electroneurography (ENG) and electromyography (EMG).

ENMG consists of several tests that are performed in succession and involve the graphic representation of the electric and/or muscular phenomena evoked by direct or indirect stimulation with an electrode. The ENG uses surface electrodes that apply electrical stimuli to the nerve, which in turn activate the sensory or motor fibers and evoke action potentials that travel along the same nerve. The recorded parameters are amplitude, speed of conduction, and distal and proximal latencies that are then compared with reference values and normalized by age, height, and skin temperature. The EMG uses disposable needle electrodes, which record the activity of muscle fibers (action potentials) at different conditions: rest, during voluntary and progressive contraction up to the maximum effort, and during a sustained average contraction. In this way, it is possible to study the type of muscle recruitment, the morphology of motor unit potentials, and the presence or absence of spontaneous electrical activity at rest.

A percutaneous electrical stimulation of peripheral nerve induces action potentials in the innervated skeletal muscle (evoked EMG) that includes the H-wave. The H-wave gives us information on the distribution of the stimulus input from muscle spindle to the spinal cord motor neuron pools; it is useful for the evaluation of muscle tone (spasticity) and the diagnosis of peripheral neuropathy.[16]

  Imaging Top

The term imaging is referred to a set of techniques used to explore from outside the body structures. These commonly include ultrasonography (US), radiography, computed tomography (CT), magnetic resonance imaging (MRI), scintigraphy, positron emission tomography (PET), and single photon emission CT (SPECT).


US is extensively used in physical and rehabilitation medicine (PRM) supporting both diagnosis and interventions. It is based on sound waves with frequencies from 7.5 MHz up to 18 MHz. The creation of an image from sound is based on the production of a sound wave and the reception and interpretation of echoes. The creation of sound waves is due to a piezoelectric transducer which is able to transform electrical transmission pulses into ultrasound pulses and to convert ultrasonic echo pulses into electrical signals. The electrical signal is then processed by a computer in an image.

US is useful in the diagnosis of several acute and chronic muscle injuries, tendon pathologies, traumatic injuries of ligaments, enthesopathies, and injured joints.[17] Another relevant use of US is represented by injections. Performing US-guided injections reduce the risk of unnecessary injuries to the surrounding tissues, thanks to the possibility to visualize the needle in real time.[17]

US is a cost-effective and patient-friendly method. Its disadvantages include a steep learning curve and a reduced sensitivity in obese patients or those who have severe limitation of the ROM.


Radiography uses a beam of X-rays which are differently absorbed by the various structures of the body, on the basis of their density and their thickness. The X-rays that pass through the structures are captured by the photographic film (traditional radiography) or a digital detector (digital radiography), and a two-dimensional image is created.

Radiography is useful to study the skeleton and allows to evaluate both the qualitative and quantitative characteristics of the bones. The examination is performed according to two orthogonal projections (anteroposterior and laterolateral), but more projections might be needed in specific cases.

Computed tomography

CT is a noninvasive technique that uses computer-processed combinations of several X-rays measurements made from different angles to produce cross-sectional (tomographic) images of specific areas of the body. It is able to distinguish the various organs and tissues according to their density and different absorption of the X-rays that crosses them. The reconstructed CT image is represented in a numerical map called matrix. Each element of the matrix (pixel) is assigned a numerical value which is proportional to the linear attenuation coefficient of the corresponding portion of the tissue under examination. This numerical value is expressed in Hounsfield units.

In PRM, CT is particularly useful for the study of bones and joints and for the evaluation of fractures and microfractures not visible on traditional radiographic examination.

Magnetic resonance imaging

MRI is a noninvasive method that provides multiplanar sections of the body under examination using magnetic fields and radio waves, without the use of ionizing radiation. MRI has a high contrast resolution; however, it has a lower spatial resolution than CT and higher management costs. MRI systems produce images using the magnetic properties of the hydrogen nucleus, which is the most abundant element in the body. MRI signals are used to form an image in which the shades of gray of the tissues are as clear as the signal emitted by them is more intense and vice versa.

In PRM, MRI has elective indication at the spine, as it is the best imaging technique for the study of degenerative and inflammatory pathologies as well as of the contents of the spinal canal, nerve roots, disc structures, and bone marrow. MRI also provides important information in the assessment of muscular, tendinous, and synovial pathologies, ligament injuries, meniscal injuries, and of the whole nervous system. It is also indicated to highlight bone marrow edema.


Scintigraphy is a diagnostic method based on the examination of the distribution in organs and tissues of the administered radioisotopes.

Bone scintigraphy provides functional information of the bone metabolic activity, allowing an early diagnosis of skeletal pathologies. However, it does not allow to identify the nature of the lesions. That is why, it is considered a high-sensitive but low-specific test.

Positron emission tomography and single photon emission computed tomography

PET is a diagnostic method that provides a metabolic image of the organism, using positron emission by glucose labeled with radioactive molecules (18-fluorodeoxyglucose) with radioisotopes introduced into the body. Cells use different amounts of glucose for their own metabolism depending on their functional activities and state (growth and active division or not). PET returns an image of the metabolic activity of organs and tissues, indicating the different levels of activity with different colors.

SPECT is similar to PET, but it is based on the use of radioactive compounds that emit directly gamma radiation. SPECT is mainly used for the diagnosis of brain diseases and the neuroendocrine system.

  Bone Densitometry Top

Quantitative bone mass measurement techniques are indicated in the study of metabolic bone alterations, characterized by a deterioration of tissue microarchitecture with a consequent increase in bone fragility and fracture risk. The most common densitometric techniques use the phenomenon of X-ray attenuation that occurs when the beam passes through the bone tissue and can measure the following: the bone mineral content (BMC) expressed in g/cm, the bone mineral density (BMD) expressed in g/cm2, and the BMD in a given volume expressed in mg/cm3.

The dual X-ray absorptiometry (DXA) consists of the X-ray source, the system that allows the separation of the two energy levels, and the digital detector device. During the patient scan, the computer reconstructs the image of the section under examination, the operator manually positions the regions of interest, and the equipment provides data on BMC and BMD. For the diagnosis of osteoporosis, it is good to perform both the measurement of lumbar spine and femoral neck BMD (the study of this last skeletal segment is mandatory after 65 years). The values obtained after the scan are automatically shown on a reference curve normalized by age and sex.

The high spatial resolution of the recently introduced DXA scanners makes it possible to measure the dimensions of the anterior, central, and posterior vertebral height (morphometric analysis) which facilitates the diagnosis of vertebral fracture.

The DXA also allows the measurement of the “Whole Body” which provides a complete analysis of the three components of the total body composition (skeletal mass, fat mass, and lean mass).

  Functional Magnetic Resonance Imaging Top

Functional MRI (fMRI) is a noninvasive technique which is able to study changes in brain metabolism. It is based on Pauling's observation that the modification of hemoglobin oxygenation changes has magnetic properties.[18] This effect is defined as blood oxygen level dependent (BOLD) and provides an endogenous marker of neuronal activity. BOLD fMRI can represent the changes in the magnetic field depending on hemoglobin oxygenation: oxygenated hemoglobin (HbO2) is magnetically identical to brain tissue, deoxygenated hemoglobin (Hb) instead has 4 unpaired electrons and it is highly paramagnetic. This paramagnetism results in local gradients in magnetic field depending on Hb concentration. During brain activity, the increase of HbO2 causes an increase in the BOLD signal, and the activated regions appear as more intense at the fMRI.

Since 1990, fMRI has been used in an exceptionally large number of studies in the cognitive neurosciences.[19]

  Gait Analysis Top

Experienced clinicians can get important information observing the patient gait before starting the clinical examination. Videorecording the patient gait and looking back to it in slow motion might be useful to get further qualitative information. Gait analysis is a diagnostic tool used for the quantitative assessment of gait disturbances.[20] The gait analysis laboratory has several video and/or infrared cameras placed around a walkway and linked to a computer. Markers are located on various reference body parts of the patient such as the iliac spines of the pelvis, the ankle malleolus, and the condyles of the knee or on half of the body segments. The patient walks down the walkway, the cameras collect information on the position of the markers, and the computer graphically represents their trajectories in three dimensions. The activity of the muscles contributing to gait can be investigated using surface electrodes.

A valuable, though less detailed, analysis of the gait can be performed outdoor using wearable sensors (WS). The most used WS are accelerometer and gyroscope and goniometers. Recently, there have been produced smaller, lighter, and more robust WS systems.[21] In the future, affordable and noninvasive measurement devices that can provide real-time feedback to healthcare providers and to patients in their daily activities might improve the healthcare system.[22]

  Conclusion Top

A detailed functional assessment of a patient is fundamental before a rehabilitation plan is put together. There are many different scales that can be used to measure different aspects of functioning along with diagnostic tools that, if well used, can rapidly define a patient's health condition and level of functioning. This includes checklists and assessment tools as well as algometer, goniometer, electrogoniometer, dynamometer, myotonometer, ENMG, bone densitometry, fMRI, and gait analysis.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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Fischer AA. Pressure threshold meter: Its use for quantification of tender spots. Arch Phys Med Rehabil 1986;67:836-8.  Back to cited text no. 2
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Leggin BG, Neuman RM, Iannotti JP, Williams GR, Thompson EC. Intrarater and interrater reliability of three isometric dynamometers in assessing shoulder strength. J Shoulder Elbow Surg 1996;5:18-24.  Back to cited text no. 10
Pandyan AD, Johnson GR, Price CI, Curless RH, Barnes MP, Rodgers H, et al. Areview of the properties and limitations of the Ashworth and modified Ashworth scales as measures of spasticity. Clin Rehabil 1999;13:373-83.  Back to cited text no. 11
Leonard CT, Deshner WP, Romo JW, Suoja ES, Fehrer SC, Mikhailenok EL, et al. Myotonometer intra-and interrater reliabilities. Arch Phys Med Rehabil 2003;84:928-32.  Back to cited text no. 12
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Marusiak J, Kisiel-Sajewicz K, Jaskólska A, Jaskólski A. Higher muscle passive stiffness in Parkinson's disease patients than in controls measured by myotonometry. Arch Phys Med Rehabil 2010;91:800-2.  Back to cited text no. 14
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Shull PB, Jirattigalachote W, Hunt MA, Cutkosky MR, Delp SL. Quantified self and human movement: A review on the clinical impact of wearable sensing and feedback for gait analysis and intervention. Gait Posture 2014;40:11-9.  Back to cited text no. 21
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  [Table 1]


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