This condition is similar in cause to Patellar Tendonitis as it involves a mal-tracking of the Patellae within the femoral groove. There is a slot or groove that the Patellae glides within. When it no longer sits correctly in its groove, it will start to shear against the femur. Eventually the cartilages will wear down, the patellar will have a rough sound on the knee, and when bending it can crackle.
When the cartilage wears through it will be bone on bone, the knee can become osteoarthritic eventually needing surgical assistance.
It can be painful and can lead to locking of the knee. Often there may be loose bodies as bits of bone or cartilage break loose and float around the knee.
It can also be caused by muscle imbalances where there are weak Quadriceps compared to the Hamstrings.
Tight retinaculums which are tissues that assist the position of the patellae may be leading to mal-tracking.
Treatment in the early stages involves biomechanical appreciation of the cause and management through stretching, insoles and orthotics. The purpose is to reduce Internal Tibial Rotation to assist the Patellae to track better.
When the Patellae tracks better it can relieve pain and further wear and tear.
In some cases, Arthroscopy may be necessary to clean the knee out. Osteoarthritic knees may need a Total Knee Replacement, although that is normally only done much later in life.
Muscle imbalances,dealing with strength and flexibility are important in this condition, a Biokinetisist can assist in this regard. Isokinetic testing with computerised Cybex machine can determine the accuracy of the imbalances.
Knee braces that assist in patellar alignment can help as a conservative measure.