Introduction and Definition of screening tests and screening examination

A screening test refers to use of an individual test with high sensitivity in order to rule out presence of a disease or condition.
A screen examination is an abbreviated exam intended to quickly identify the region of the body where a problem is located (Kaltenborn, Evjenth, Kaltenborn, Morgan, & Vollowitz, 2003). It is composed of a cluster of tests with mixed sensitivity and specificity. The reason for using a screening test or examination is to detect injuries or disease pathology that require referral or more specialised testing. It serves to define or focus additional examination and, in some cases, leads to a diagnosis and immediate treatment.
A screening examination can lead to the following:

• Diagnosis
• Further detailed examination
• Identification of precautions and contraindications
Screening examination requires:
• Mastery to detailed examination
• Putting much thought to the process
• Clinical experience to easily recognise patterns of conditions
Note: Novice practitioners and students should master detailed examination without relying on screening examination. For experienced practitioners there is no set sequence or flow of procedure in how to conduct a screening exam.

As physiotherapist you do not want to be treating serious pathologies as routine disorders.

Lower Quarter Screening (The Lumbar Spine)

The aim for screening the lumbar spine is to determine if we can reproduce the concordant sign. The concordant sign is defined as the pain or symptom that is familiar to the patient i.e. usually the symptom for which the patient is seeking physiotherapy (Mathers, 2012).

Components of Screening Tests/Examination in the Lumbar Spine

• Active movements of the lumbar spine with an overpressure
  • Flexion of the trunk
  • Extension of the trunk
  • Side bending of the trunk
  • Rotation of the trunk.
• Neurological tests:
  • Sensory test: Sensory testing for lumbar radiculopathy is based on dermatomes. It is an easy test to do via application of neuroanatomy knowledge. However, there are significant variations in current dermatome maps in standard anatomy texts (Lee, McPhee, & Stringer, 2008). Dermatomes might help us to know which level the lesion might be.
  • Motor test: In some studies, straight leg raise (SLR) has been documented to have sensitivity of 91% and specificity of 26%.
  • Deep tendon reflex tests: Diagnostic test of deep tendon reflex is good. Research found an inter-observer specificity ranging from 60% to 93% and sensitivity ranging from 14% to 67%. However, this confirms a great variation (Tawa, Rhoda, & Ina, 2017). For upper motor neurone signs, Babinski was found to have a specificity of 99% and sensitivity of 50%. However, absence of Babinski requires additional patient evaluation if upper motor neurone lesion is being suspected. This is because Babinski has low sensitivity (Isaza, et al., 2014). Femoral nerve stretch test has a sensitivity 100% and a specificity of 83% (Tawa, Rhoda, & Ina, 2017).

Structural Differentiation and Regional Interdependence

Structural interdependence refers to the concept that seemingly unrelated impairments in a remote anatomical region may contribute to, or be associated with, the patient’s primary complaint (Wainner, Whitman, Cleland, & Flyn, 2007). It is known that some patients experience back and knee pain from hip involvement. Structural differentiation is meant to rule out involvement of the thoracic spine in low back problems. Provocation tests such as compression T-spine in seated position may not be accurate because of accompanied compression of the L-spine. Mobility testing has shown that decreased T-spine mobility might also be a contributor to LBP. Apart from ruling out involvement of the thoracic spine in lumbar spine disorders, structural differentiation can also help rule out sacral, pelvic and hip involvement in LBP troubles.
Clinical examination is a more reliable way of diagnosing pelvic fractures than plain films (Duane, et al., 2008). Duane, et al. suggested the following as the most predictive clinical examination findings for a pelvic fracture:

• Age
• Hip pain
• Internal rotation of the leg
• Tenderness to palpation over the sacrum
• Tenderness to palpation over the right/left hip
• Diffuse pain throughout the sacrum

Sacroiliac Joint Dysfunction

Sacroiliac joint dysfunction is pain from the sacroiliac joint. Sacroiliac dysfunction can refer pain to the lower back and or legs. Leg pain from sacroiliac joint dysfunction can be particularly difficult to differentiate from radiating leg pain caused by a lumbar dis herniation (sciatica) as they can feel quite similar.

Characteristics of Sacroiliac Joint Pain:

• Pain in the Fortin’s area (3cm horizontal and 10cm vertical of posterior superior iliac spine)
• There is no centralization or peripheralization with movement
• Lateralization of pain while standing from sitting
• Sign of the buttock
• Clear onset
• Sign of the buttock (De Coninck, 2018). Note: Sign of the buttock refers to 7 signs which indicate presence of serious gluteal pathology. Presence of sign of the buttock is a red flag and requires referral. The 7 features which comprise sign of the buttock include:
  • Buttock large and swollen and tender to touch
  • Straight Leg Raise (SLR) limited and painful
  • Limited trunk flexion
  • Hip flexion with knee flexion limited and painful
  • Empty end-feel on hip flexion
  • Non-capsular pattern of restriction at hip (flexion-abduction-internal rotation)
  • Resisted hip movements painful and weak especially hip extension (Physiopedia, 2018; De Coninck, 2018)

(Positive SLR and non-capsular pattern of restriction hip (Flexion - Abduction- Internal rotation). To test hip or buttock involvement, perform hip flexion with flexed knee. If positive it will result in pain (empty end-feel). (The Student Physical Therapist, 2018)
To diagnose sacroiliac joint dysfunction, the gold standard is a diagnostic nerve block. However, Laslett et al identified a 5-item test cluster (TIC) after McKenzie evaluation to rule out discogenic pain. A TIC is a group of special tests which are developed to facilitate clinical decision making by improving the diagnostic utility. Initially when 3 of the following 5 tests were positive, it was considered an SIJ dysfunction:

• Distraction
• Compression test
• Thigh thrust
• Sacral thrust
• Gaenslen test

With continued research, it was found that removing Gaenslen did not change the diagnostic accuracy and hence 2 out of 4 indicates SIJ dysfunction. Removing Gaenslen test was found not to affect the cluster in any way (Laslett, Aprill, McDonald, & Young, 2005). Diagnostic value of the four tests above (excluding Gaenslen test) is as follows:

Measure	Values (95% CI)
Sensitivity	0.88 (0.64, 0.97)
Specificity	0.78 (0.61, 0.89)
+LR	4.00 (2.13, 8.08)
-LR	0.16 (0.04, 0.47)

Physiopedia, 2018 . It is recommended to use distraction test, compression test, thigh thrust/posterior shear, sacral thrust, and resisted hip abduction as these are the only tests that have specificity and sensitivity greater than 60% as demonstrated in studies done before (Stuber K. J., 2007).

Classification of Pain

Based on Smart’s mechanism-based classification of pain, pain is classified into:

• Central sensitization (CS)
• Neuropathic pain (NPP)
• Nociceptive pain (NCP)

Central Sensitisation (CS)

Refers to pain arising from a dominance of neurophysiological dysfunction within the central nervous system (Smart, Blake, Staines, Thacker, & Doody, Mechanisms-based classifications of musculoskeletal pain: part 1 of 3: symptoms and signs of central sensitisation in patients with low back (± leg) pain, 2012). To detect central sensitization, a predictive cluster of 4 clinical criteria was proposed by Smart et al. These include:

• Disproportionate, non-mechanical, unpredictable pattern of pain provocation in response to multiple/non-specific aggravating/easing factors
• Pain disproportionate to the nature and extent of injury or pathology
• Strong association with maladaptive psychosocial factors (e.g. negative emotions, poor self-efficacy, maladaptive beliefs and pain behaviours)
• Diffuse/non-anatomic areas of pain or tenderness on palpation

Based on this criterion, sensitivity of identifying this type of pain is 91.8% and specificity is 97.7%.

Neuropathic Pain (NPP)

Neuropathic pain (neuralgia) is a pain that comes from problems with signals from the nerves (Tidy, 2016). It is pain caused by damage, injury or dysfunction of nerves due to trauma, surgery, disease or chemotherapy. It is described as burning, painful, cold or electric shocks and may be associated with tingling, pins and needles, numbness or itching. Neuropathic pain can be the primary symptom of a stand-alone condition, such as complex regional pain syndrome, multiple sclerosis or post herpetic neuralgia. It can also be associated with other medical conditions or other forms of pain, including pelvic pain, fibromyalgia and orofacial pain. Lumbar radiculopathy( dermatomal numbness and reduced reflex activity) and phantom pain following a limb amputation is also a type of neuropathic pain. Without effective treatment, neuropathic pain can lead to serious disability. It is not pain from nociceptors and this kind of pain does not respond to usual pain killers but antidepressants. It may also respond to other pain killers (Pain Australia, 2018).
To predict neuropathic pain, a cluster of predictive clinical criteria can be used. Here are the three clinical criteria that is used to predict neuropathic pain:

• Pain referred in a dermatomal or cutaneous distribution
• History of nerve injury, pathology or mechanical compromise
• Pain or symptom provocation with mechanical or movement tests (e.g. Active/Passive, Neurodynamic) that move/load/compress neural tissue

Clinical note: This clinical criterion has a sensitivity of 86.3% and a specificity of about 96% (Smart, Blake, Staines, Thacker, & Doody, Mechanisms-based classifications of musculoskeletal pain: part 2 of 3: symptoms and signs of peripheral neuropathic pain in patients with low back (± leg) pain, 2012).

Nociceptive Pain (NCP)

Refers to pain attributable to the activation of the peripheral receptive terminals of primary afferent neurones in response to noxious chemical, mechanical or thermal stimuli.
Predictive cluster of 7 criteria:

• Pain localised to the area of injury/dysfunction
• Clear, proportionate mechanical/anatomical nature to aggravating and easing factors
• Usually intermittent and sharp with movement/mechanical provocation; may be a more constant dull ache or throb at rest
• Absence of Pain in association with other dysesthesias
• Night pain/disturbed sleep
• Antalgic postures/movement patterns
• Absence of pain variously described as burning, shooting, sharp or electric-shock-like

This cluster has a high level of accuracy, sensitivity of 90.9% and specificity of 91%. (Smart, Blake, Staines, Thacker, & Doody, Mechanisms-based classifications of musculoskeletal pain: part 3 of 3: symptoms and signs of nociceptive pain in patients with low back (± leg) pain., 2012).