[150 years of the patellar tendon reflex: Discovery, interpretation and clinical establishment].

In 1875, two German neurologists simultaneously described a previously unknown phenomenon in the same medical journal: Carl Westphal (1833-1890) referred to it as the "phenomenon of the lower leg", while Wilhelm Erb (1840-1921) called it the "patellar tendon reflex".This novel observation quickly attracted significant attention from the international medical community. Yet many questions remained unanswered: Was this truly a reflex transmitted via the tendons? Nothing comparable had been described before. Where in the spinal cord could its neural circuitry be localized? And how might this phenomenon be clinically useful?Further complicating its classification was the observation that the reflex could occur in both patients and healthy individuals - but inconsistently, and at times not at all.Moreover, critical voices from neighboring France repeatedly claimed that Erb and Westphal had merely repackaged previously known findings as their own.Drawing on extensive research of 19th-century medical literature, this account traces the initial descriptions of the reflex, the subsequent scientific investigations, and its eventual incorporation into clinical neurological practice.