knee joint is made up of 3 bones: the femur (thigh bone), tibia (shin
bone) and patella (kneecap).
The patella is wrapped inside a quadriceps
tendon that connects the thigh muscles (quadriceps) to the tibia. When the
knee bends, or straightens, the patella glides in a special groove on the
femur called the Patellofemoral groove.
- Usually, when the knee is bent or
straightened, the patella moves along a path that is controlled by the
quadriceps muscles. However, for several reasons it may stray from this
path (usually towards the outside of the knee). This is called Patellofemoral
Maltracking and produces abnormal stresses on the
under-surface of the patella that can cause pain. If allowed to progress,
these stresses can cause damage to the articular cartilage on the patella
(chondromalacia patellae) and femur. This is similar to having the front tire
of a car slightly out of alignment, leading to abnormal wear on the tire.
Patellofemoral Maltracking is one of the
most common causes of knee pain and can be caused by numerous factors:
- Tightness in certain structures. (e.g.
calf and hamstring muscles).
- Weakness or incoordination in muscles
that should help maintain normal patella tracking.
- Altered hip, knee or foot posture.
- Anatomic variations such as a shallow Patellofemoral
Signs and Symptoms
The most common symptom of is pain at the
front of the knee that can occur while:
or, more often, descending stairs
- Pain can also result from prolonged
people may experience instability (this can involve a sensation of
insecurity or actual giving way of the knee) or locking of the knee.
The causes of Patellofemoral Maltracking will be specific for each person and so it is important that a treatment
plan is formulated to meet the patient's individual needs.
- The first priority is to attempt to
settle the pain, usually through machines, rest or analgesics
prescribed by a GP.
- Once this is achieved, treatment is
likely to include stretches for the calves, quadriceps, hamstrings,
hip flexors, hip rotators and Illiotibial band.
- Of even greater importance are
exercises to both strengthen and improve the coordination of the
vastus medialis oblique (VMO) muscle. The VMO forms part of the
quadriceps muscle group and is located just above the patella, on the
inner aspect of the thigh. It is believed to help maintain the patella
in its correct position in the Patellofemoral groove. Methods of
improving VMO function may involve EMG biofeedback machines or taping
of the patella.
- Strengthening of the quadriceps muscle
group as a whole is also thought to be beneficial, but it is important
to note that traditional knee extension exercises may actually
exacerbate the problem through over-stressing the Patellofemoral joint. Closed-chain exercises (where the sole of the foot is in
contact with a flat surface) such as the squat and split-squat are
more appropriate but should only be performed in a safe, pain-free
range of motion.