1. Evidence has been produced to show that adhesions in the quadriceps may be the primary cause of knee stiffness after fractures of the shaft of the femur.
2. The recovery of perfect knee movement after a fracture of the shaft of the femur depends upon the complete absorptin of scar tissue involving muscle at the fracture site.
3. The production of scar tissue around a fracture and the involvement of the surrounding muscles is a biological process, related to the healing power of the fracture and unrelated to early mechanical knee motion.
4. If the fracture of the femur shows clinical union in eight weeks, final knee motion will he excellent even if the knee remains fixed throughout treatment. Scar tissue in these cases is minimum, and bony callus is plentiful.
5. If the fracture of the femur shows delayed union, it is doubtful whether mechanical knee movement will prevent considerable permanent knee stiffness. In these cases, bony callus is scanty, permanent scar tissue is plentiful, and quadriceps tethering occurs.