The quads and hams, to be colloquial, surround the knee in a tripod-like fashion, the quadriceps through the patella and its tendon acting to straighten the knee, while the hamstrings at the back of the thigh diverge, to be inserted behind the knee on the inside and outside to complete our tripod. If you think of them as being like the guy ropes of a tent, a tightening of one group will stretch the other, and it is this alternate movement that enables the knee to function.
The quadriceps muscles may be torn anywhere from hip to knee.
The common acute tear will cause sudden pain, accompanied by weakness which may make you stumble or fall. It is more likely to occur if you are pushing off to jump a hurdle or obstacle, or to go uphill.
Little difficulty is usually experienced in the diagnosis of a quadriceps tear. There is pain at the site of injury and any resistance to straightening of the knee will cause pain at this site. As a bruise forms, there is thickening of the muscle, which becomes hard and tender, although, if the muscle is severed completely (a not uncommon situation) a gap may be visible when the muscle contracts.
Because the diagnosis is so obvious, investigations are rarely required unless the condition becomes chronic, with the risk of the scar changing to bone (myositis ossificans). An x-ray will confirm whether bone is forming within the scar tissue.
What else could it be?
Other causes of pain in the thigh are rare, though it is not impossible for a stress fracture of the femur, an adductor muscle tear or referred pain from the lower back to appear as quadriceps pain.
The basic principles of RICE apply to early management. This should occupy 48 hours, with ice being applied for 15 minutes per hour, as often as feasible. This will limit bleeding and aid later rehabilitation as you attempt to stretch, then strengthen the damaged muscle.
Apart from professional guidance as to the optimum time-scale for patient-initiated treatment, some forms of electrical therapy may further speed up healing. The risk is always of over-enthusiastic treatment and the complications mentioned above.
Can you run through it?/Recovery time
While a simple tear may recover in a week, a complete rupture or deep tear of the muscle may have effects for several weeks. If there is a complete rupture, surgical repair is not necessary, as accessory muscles will take the strain and build power and strength to mimic the actions of the injured muscle. A return to full strength may take three months.