Since the medieval rack is cited so often as a mechanism to get taller it would be interesting to see how it works.

The torture or stretch arthritis syndrome (A modern counterpart of the medieval ‘manacles’ and ‘rack’)

“A characteristic symmetrical bilateral polyarthritis syndrome is described, affecting the compartments of the wrist joints in a characteristic sequence. The pisiform-triquetral joint gives first, exposing the inferior radioulnar joint so that pisiform pain and tenderness are followed by painful supination{Rotation of the forearm and hand are rotated forward or up}. The proximal radiocarpal joint slackens next, followed by the mid-carpal joints. The lunates subluxate{dislocate} as their posterior attachments stretch. Synovial oedema{swelling} may produce additional median and ulnar carpal tunnel syndromes. The best radiologic sign of this distraction is anterior subluxation of the lunates. Nocturnal arthralgia becomes severe; grip and the ability to write are lost and stretching now shows as a traumatic arthritis in the clavicular joints. The patient is incapacitated and therefore progression halts. A history of excessive straining and lifting is obtained eg with a wheel-barrow, iron pots or strenuous rowing{so if the rack worked to increase height you could just row instead for some of the effects?}. All serologic tests for rheumatoid disease are negative. Serum uric acid levels and blood sedimentation rates remain normal. There are clear analogies with old descriptions of the effects of torture by stretching from manacles or gauntlets or by the rack.”

IF the rack were to increase height it would have to occur before the pisiform-triquetral joint “gives”.