hi,
try to inhibit his extensor tone by making him lie prone as this would increase the floxor tone according to the TLR, when you flex a patients head the body would flex and vice versa. you can use the head as the key control and try to reduce the amount of extension. dont encourage pelvic bridging as the patient himself is extending a lot!! Find out if the problem is because of the tone in teh extensors or becanse of an undiagnosed hip conditionwhich could be a HO. Try to teach him flexion of trunk in lying!! you can also use the area around t12 vertebra as a key point to get trunk flexion!! Try to do coming up to standing emphasising on the flexion part of the trunk!!