Biceps Femoris Tendon Avulsion
The biceps femoris is one three hamstring muscles. An avulsion strain or fracture involves the tendon pulling away from the bone.
Symptoms of Biceps Femoris Avulsion
- Avulsions normally occur during a rapid or violent movement involving hip flexion and knee extension and are known to be extremely painful
- Swelling will appear in the region of the avulsion
- There will be an associated loss in hamstring strength i.e.a decreased ability to flex the knee joint against resistance
- In the case of an avulsion fracture, the bone fragment may be palpated through the skin
What is the Biceps Femoris Tendon?
The muscle is made up of two seperate muscle bellies which originate from different sites, namely a long head and a short head. The long head originates from a region at the back of the hip bone called the ischial tuberosity.
The short head originates from the back of the femur (thigh bone). Both muscle bellies join together, cross the knee joint and insert into the top outer surface of the two shin bones, the tibula (inner) and fibula (outer). As with all the hamstrings it has a dual function, both to bend the knee and extend the hip.
What is avulsion of the Biceps Femoris Tendon?
The biceps femoris is commonly injured in sports that require explosive bending of the knee as seen in sprinting. If the athlete is fatigued or has not warmed up properly he/she may suffer a hamstring strain/rupture, which is the tearing of the hamstring muscle.
Avulsion of the biceps femoris tendon, is the complete pulling away of the tendon from the bone. This most commonly occurs where the long head attaches to the ischial tuberosity.
Injuries to biceps femoris are more common than to the other hamstrings. One theory for this is the fact that each of the two heads are innervated by different branches of the sciatic nerve. In states of fatigue or when the muscle is not fully warmed up, uncoordinated firing of the nerves may cause the muscle to contract inappropriately during movement, leading to injury.
Biceps femoris tendon avulsion may also be associated with an avulsion fracture which occurs when a piece of the bone is pulled away with the tendon, during forceful contraction.
Treatment of Biceps Femoris Avulsion
What can the athlete do?
- Apply RICE Technique immediately.
- Apply compression with elasticized bandage.
- See a sports injury specialist.
What can a sports injury specialist do?
- Diagnose the problem - an x-ray may be necessary if an avulsion fracture is suspected.
For less serious cases conservative treatment may be advised. This may include:
- Strengthening and proprioception exercises.
- Manual techniques such as deep tissue massage.
- Ultrasound and TENS In more serious injuries, surgery may be necessary to re-attach the tendon (and bone fragment, if present).
- In some cases the knee must be kept at 90 degrees using a knee brace for a number of weeks following surgery.
- Recovery following surgery usually takes significantly longer than by conservative methods.
