Patella - pain related to patella
Submitted by admin on March 14, 2008 - 11:19am.
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When kneecap (patellar) pain is first experienced, the patella itself may have no structural abnormality. Patellar pain not associated with injury is usually vague in nature and experienced around the front of the knee. Characteristically a patient will rub the whole front of the knee rather than using the index finger to point to a particular spot. Pain is characteristically worse on descending or ascending stairs, or walkind downhill. Pain may be associated with crunchy noises or a grating sensation (patellar crepitus). A full evaluation of patellar pain should include observation of the gait, the standing posture, the feet, the tibia and femur bones, the patella itself and the groove in which it glides, as well as the hip and lower back. The strain on the patella may be the result of an abnormality elsewhere in the 'extensor mechanism' - that is, the chain of structures from the foot to the hip which act together when the leg is straightened during motion. Less often, the originating problem is within the patello-femoral joint itself - either a structural problem which makes the joint prone to dislocation, or a direct injury or local abnormality. |
Pain from patellar Mal-alignment & Instability
Pain over the patella area may be experienced when faults in the extensor mechanism pull the patella out of optimal alignment, causing excessive pressure on the cartilage of both patellar and the underlying femur. In severity they may be divided into -
- Functional disorder only - In a functional disorder the shape of the patella and trochlear groove are normal, although their relationship to one another may be out of synch., and the joint surface is not yet suffering any damage. Pain and tenderness around the patella may be present but no feeling of instability. The primary problem may be -
- muscle imbalance (for example, a weakness of the one part of the quadriceps (the VMO)
- poor alignment of the foot or hip or back
- Moderate structural disorder - Here the symptoms of pain and intermittent instability are associated with discernible structural (as opposed to functional) abnormalities in the bony structures of the extensor mechanism -
- flattening of the walls of the groove ('trochlear dysplasia')
- a high-riding patella ('patella alta')
- abnormal-shaped patella ('patellar dysplasia').
- Pronounced structural disorder - In this case there is gross flattening of the trochlear walls and the kneecap is readily displaced beyond its normal position in the trochlea. There is marked instability, and injury may lead to complete dislocation, often tearing the usual restraining structures on the inner side ('medial retinaculum') and even breaks (fractures) in the bones.
Pain from repetitive overuse
Overuse of the extensor mechanism in athletes and performers may lead to -
- quadriceps tendinosis - painful degeneration of the inside of the quadriceps tendon above the kneecap
- patellar tendinosis - same disorder in the tendon below the kneecap. Also called 'jumper's knee'.
- traction apophysitis - when the attachment of the patellar tendon to the bone becomes strained -
- Osgood Schlatter's disease - traction apophysitis at the attachment of the tendon to the tibial tubercle
- Sinding Larsen Johannsen Disease - traction apophysitis at the attachment of the tendon to the undersurface of the patella
Arthrofibrosis around the patella
Pain may become severe when tissues around and below the patella becomes scarred in a process known as 'arthrofibrosis'. The scar tissue may entrap the patella, and then contract to pull it down below its normal position - the 'infrapatellar contracture syndrome'. An abnormally low patella ('patella infera or baja') can be extremely painful and trigger arthritis in the joint.
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