Kawasaki's John Hopkins will sit out the German and US Grand Prix races, after further medical checks revealed the injuries he sustained in a high-speed qualifying crash at Assen would r equire corrective surgery before he can return to action.Hopkins crashed at 230km/h towards the end of qualifying for the Dutch TT, after losing the front of his Ninja ZX-RR at Ramshoek corner, the ultra-fast left-hander just before the final chicane. The Kawasaki pilot slid across the track and through the gravel trap before colliding feet first with the tyre wall on the outside of the turn. X-rays of his injured left leg at the circuit medical centre revealed that Hopkins had sustained a fracture to the bottom of his tibia and that he had reopened a previous fracture, the result of a crash earlier in his racing career. The x-rays also showed a fracture to the lateral malleolus, which is one of the bones at the top of the ankle.