Mark midline 10cm above the dimples of Venus and 5cm below while standing, then re-measure distance in flexion (<5cm difference implies lumbar flexion limitation that may be due to ankylosing spondylitis if there are other symptoms/signs)
Measure chest circumference in expiration and inspiration. Around 7cm difference is normal (<5cm suggests ankylosing spondylitis).
With patient prone, passively flex knee and extend hip (anterior thigh pain = femoral nerve irritation, usually due to L2-4 disc herniation)
With patient supine, lift a leg to full flexion or until significant leg pain, then depress it slightly and passively dorsiflex foot (leg pain radiating down below knee = sciatic nerve irritation, usually due to L4-S1 disc herniation/facet joint impingement)
Ask patient to flex their hip and knee, then passively push that knee into the patient’s chest and push the contralateral thigh into the bed (pain = sacroiliac joint pathology)