Chondromalacia Patellae
by Dr. Terry R. Yochum, D.C.; D.A.C.B.R.; Fellow, A.C.C.R. and Dr. Chad J. Maola, D.C.
History: This adult female patient presents with chronic knee pain.
Diagnosis: Chondromalacia patellae. Observe the loss of the retropatellar joint space, osteophytes, and sclerosis. Note the smooth, concave anterior femoral erosion (arrow), caused by mechanical extrinsic pressure of the superior patellar osteophyte.
General
Considerations:
Chondromalacia patellae is the term applied to the syndrome of pain and crepitus arising from the patellofemoral articulation. As a distinct entity, it was first described by Budinger in 1906. Plain film radiography is, for the most part, unrewarding and usually acts to exclude other underlying pathologic alterations.1
Clinical Features:
Considerable confusion exists as to the actual nature and significance of the lesion in the diagnosis and delineation of its true etiology. The term chondromalacia patellae is often haphazardly used to encompass a wide variety of patellofemoral syndromes, and this has contributed greatly to the confusion. Typically, chondromalacia patellae is a disease of the adolescent and young adult. Etiologic factors include trauma, patellar dislocation, malalignment syndrome, primary cartilage vulnerability, and occupation. Many consider it a normal part of patellofemoral joint aging. It is often confused clinically with symptoms arising from a meniscal injury.
The most often used clinical criteria for applying the diagnosis of chondromalacia patellae are anteromedial knee pain associated with crepitus, buckling, locking, stiffness, swelling, and tenderness. Pain is usually aggravated by sitting in a confined space with the knee flexed (“movie sign”) and by walking up stairs. A distinctive physical sign is retropatellar pain elicited by direct patellofemoral compression with the knee slightly flexed.
Measurement of the Q angle has received attention as a method to detect patellar malalignment which may predispose to chondromalacia. It is the angle formed by the line of the quadraceps muscle and the patellar ligament. Measurement is performed clinically by assessing the angle formed by two lines: (a) from the ASIS to the center of the patella and (b) from the tibial tubercle to the center of the patella. The normal range of this angle is 15 to 20º, with greater than 20º being considered abnormal.1
Pathologic Features:
Chondromalacia literally means cartilage softening. The pathogenetic sequence is characteristic and parallels that seen in degenerative joint disease. Initial swelling and softening of the cartilage produces a blister-type of cartilage lesion. Subsequently, fissuring and fibrillation occur, predominatly involving the medial facet of the patella. Involvement of the lateral facet has also been documented but rarely occurs.1
Radiologic Features:
Specific radiographic findings are characteristically absent. MR is the most accurate method of detecting focal cartilage defects. Bone changes are limited to occasional underlying osteoporosis of the patellar articular surface, particularly the medial facet. Loss of joint space denotes more advanced changes of degenerative joint disease and is usually present in advanced chondromalacia.
Malalignment of the patella can be assessed as a possible contributing factor to chondromalacia. A patella that is situated too high on the femur does not allow proper redirection of the quadriceps muscle and is termed patella alta.
Dr. Terry R. Yochum is a second generation chiropractor and a Cum Laude Graduate of National College of Chiropractic, where he subsequently completed his radiology residency. He is currently Director of the Rocky Mountain Chiropractic Radiological Center in Denver, Colorado, and Adjunct Professor of Radiology at the Southern California University of Health Sciences, as well as an instructor of skeletal radiology at the University of Colorado School of Medicine, Denver, CO. Dr. Yochum can be reached at 1-303-940-9400 or by e-mail at [email protected].
is a 1990 Magna Cum Laude Graduate of National College of Chiropractic. Dr. Maola is a Chiropractic Orthopedist and is available for post-graduate seminars. He may be reached at 1-303-690-8503 or e-mail [email protected]
Reference
1. Yochum TR, Rowe LJ: Essentials of Skeletal Radiology, 3rd ed., Williams & Wilkins, Baltimore, Maryland, 2005.lignant Differential Diagnosis: AJR 126:32, 1976.