If extensor mechanism function is intact management is non-operative, weight bearing as tolerated.
Evaluating extensor mechanism:
- Check function by asking patient to extend at the knee. Ensure there is a smooth arc motion without extension lag. Extension lag is a delay in the final 15-20° of extension which indicates accessory muscle use. The presence of extension lag indicates loss of normal extensor function.
- If struggling to overcome gravity, patient can be turned on their side to evaluate extensor mechanism function.