Six minutes into the second session at the Sachsenring, Lorenzo flipped over the front of his factory Yamaha and landed on his left shoulder.
A fortnight ago at the Dutch round in Assen, Lorenzo broke his left collarbone, resulting in him flying to Barcelona for an emergency operation during which he had eight screws and a plate inserted.
Astonishingly, Lorenzo returned to Assen where he managed to finish fifth behind team-mate Valentino Rossi who ended a three-year wait for victory.
Following Friday's accident, however, initial x-rays at the circuit medical centre have shown damage to the titanium plate, which means Lorenzo may require further surgery.
Heading into today's practice sessions, Lorenzo conceded he was far from 100 per cent and the injury would require further time to heal.
Despite that the 26-year-old posted the quickest time at the end of first practice, clocking one minute 22.047secs, 0.174secs ahead of title rival and championship leader Dani Pedrosa on the factory Honda.
In second practice Lorenzo only managed three laps, which was still good enough to finish fourth behind home favourite Stefan Bradl on his LCR Honda.
The German emerged quickest overall with a lap of 1:22.030, ahead of Honda pair Pedrosa and Marc Marquez, followed by Lorenzo and Rossi.
For Britain's Cal Crutchlow, fourth in the standings, the two sessions proved painful affairs.
Crutchlow was one of a trio of riders who fell heavily at turn 11 in first practice, Andrea Dovizioso and Andrea Iannone the others, with the latter's Ducati ending up in two pieces.
Come second practice, the same corner again caught out the 27-year-old, forcing him to sit out the remainder of the session due to scrapes and burns to his left hand.
Crutchlow was sixth quickest in the first session, 0.422secs adrift of Lorenzo, but due to his accidents in the afternoon he finished 19th, almost two seconds down on Bradl.
Tech 3 Yamaha team-mate Bradley Smith was a second off the pace in 11th.