Table 3 Summary of the studies on diagnostic accuracy

Fritz et al. [24]

- Aberrant Movement Pattern (Painful arc on flexion, painful arc on return, instability catch, Gower sign, reverse lumbopelvic rhythm). Positive test: at least 1 of the 5 signs was present.

I: LBP with or without referred pain on the lower extremities, < 60 yrs

N.49

Dynamic X-ray: the patient stands at the edge of a tall stool with feet flat on the floor and arms folded across the chest. The patient is instructed to flex forward as far as possible for the flexion X-Ray. For the extension X-ray, the patient stands with arms folded, and is asked to extend as far as possible.

1 Physical Therapist

- Prone instability test Positive test: pain provoked during the first part of the test decreases when the test is repeated with the legs off the floor.

E: contraindications to radiographic assessment (e.g., current pregnancy), previous lumbar fusion surgery, inability (e.g., pain or muscle spasm) to actively flex and extend the spine adequately to permit an assessment of segmental motion

- Age: 39.2 ± 11.3 yrs

Criteria for instability: sagittal plane translation greater than 4.5 mm or greater than 15% of the vertebral body width, or sagittal plane rotation greater than 15° at L1/L2, L2/L3, L3/L4 levels, greater than 20° at L4/L5, or greater than 25° at L5/S1.

- Posterior Shear Test Positive test: familiar symptoms are provoked.

- Duration of symptoms (median days) 78

Instability diagnosis: 2 segments with either rotational or translational instability OR 1 segment with both translational and rotational instability

- Distribution of symptoms: back/buttock only 63.3%, symptoms distal to the knee 30.6%

- Previous history of LBP: 83.7%

- LBP episodes becoming more frequent: 30.6%

Kasai et al. [25]

- Passive lumbar extension test: The subject was in the prone position; both lower extremities the were elevated concurrently to a height of about 30 cm from the bed while maintaining the knees extended and gently pulling the legs. Positive test when the subject complained of strong pain in the lumbar region (“low back pain”, “very heavy feeling on the low back”, “feeling as if the low back was coming off”) during elevation of both lower legs, and such pain disappeared when they returned to the initial position. In contrast, when the subject complained of an abonrmal sensation (mild numbness or prickling sensation) the test was negative.

I: lumbar degenerative diseases

N. 122 subjects with lumbar degenerative diseases: 89 lumbar spinal canal stenosis; 21 lumbar spondylolisthesis; 12 lumbar degenerative scoliosis.

Dynamic x-ray: flexion-extension films of the lumbar spine, lateral vision.

n°3 Orthopedics

E: /

- 39 ± 8.8 yrs;

3 criteria to asses radiological instability: angular motion > 20°; transactional motion > 5 mm; cutoff value of - 5° for the intervertebral endplate angle on the flexion film.

n°2 for testing PLE test (who had 12 and 15 yrs of clinical experience)

- mean illenss duration 11.2 months;

Radiograph instability: positive for 1 o more of the 3 criteria.

n°1 for testing Instability catch sign (with 20 yrs of clinical experience).

- Instability catch sign: The subject was asked to bend his body forward as much as possible and then return to the erect position; subject who was not able to return to erect position because of sudden low back pain was judged positive to the test.

- Complain of pain: 70.5% lumbago, 60.7% intermittent claudicatio, 42.6% neurological symptoms in the lower legs

For RX evaluation:

n°2 Orthopedics who had 8 and 14 yrs of clinical experience.