> a short-term variety described as a primary idiopathic form affecting adolescents and young adults with chronic persistent pain and resolving with a minimum to no residual;
> a secondary variety described as a secondary adolescent form due to direct patellar trauma with repeated patellar traumatic episodes which contribute to osteoarthritic development as age advances;
> an adult form presenting primarily in the second decade with osteoarthritic symptoms developing asymptomatically and progressing as age advances and becoming symptomatic with middle age or beyond.
Contact between the patella and the femur is close at the commencement of flexion. This contact slowly passes outward transferring to the medial and lateral facets after flexion is beyond 90 degrees. This area of contact, or friction, between the medial facet and medial femoral condyle, represents the site of earliest osteoarthritic changes where the development of softening and fissuring from the outset is properly considered chondromalacia. It is also noteworthy that the area of patellar contact on the medial femoral angle corresponds with the site of predisposition for osteochondritis dissecans. The location of the patellar cartilage relative to movement is not suited for the high compressive and frictional forces to which it is subjected. Consequently, the cartilage breaks down and with spontaneous degenerative changes which follow this process, the entire patellofemoral region undergoes osteoarthritic change.
There is clinical evidence of patellofemoral arthritis and generalized genicular arthritis which interferes with stair climbing and arising from a chair, both of which result in pain. There is pain upon compressing the patella against the femur in the form of tenderness. Widespread joint disease results in joint stiffness relieved by activity, limitation of motion, discomfort at rest reduced by heat application, recurrence of effusion, and marked crepitus throughout the joint. There is progressive increase in pain and difficulty in going upstairs, stepping up on a curb, or arising from a chair. With severe disease, walking, even on a level becomes impossible, or requires a walking aid, there is marked effusion resulting from a minimal trauma.
Conservative care includes rest, thermal therapy, external supports, hydrocortisone (1%) or lidocaine ointment (2.5%), pulsed phonophoresis, and gentle quadriceps exercises. Thermal therapy may be in the form of hydrocollator packs, or silicone gel wrap both applied over adequate protective toweling for 10-15 minutes, p.r.n. pain and prior to gentle exercises. Steroid/lidocaine pulsed phonophoresis may be administered b.i.d., or t.i.d., p.r.n. pain per physician choice. An appropriate knee support may be worn during walking activity as needed. To modulate moderately severe pain, interferential current therapy may be administered. Care should be taken to position the electrode around the genicular articulation in such a manner as to achieve a cross sectional point of current interference at the approximate center of the patella being treated. The transfer of current should also involve the greatest current density by the superimposed current at the potential space between the posterior surface of the patella and the anterior surface of the genicular components. With the achievement of adequate milliamperage in the carrier currents, the superimposed current should assume an elliptical ovoid within the geometric spacial configuration of the patellofemoral space. This will better ensure adequate exposure of appropriate knee components to this therapeutic process.
Of course, motion and positions which impose painful loads on the knee components such as stair climbing, squatting, etc., are forbidden. Appropriate quadriceps exercises may be found in texts which deal with this subject. Conservative care should be limited to the early stages of development of this problem. If it has progressed to a moderately advanced stage of osteoarthritic change, it should be referred for orthopedic surgical consultation.
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R. Vincent Davis, DC, BSPT, DNBPM