chapter 11: Articular Cartilage Lesions in Patellofemoral Pain Patients
ARTICULAR CARTILAGE LESIONS RELATED TO PATELLAR SUBLUXATION
The patient with connective tissue laxity and subluxation of the patella without tilt will be less prone to articular degeneration than the patient with tilt. Subluxation in the absence of tilt will most commonly cause apprehension and a feeling of instability, but arthrosis may not occur. It is not uncommon to operate on a patient for patellar instability with documented subluxation (without tilt or a history of dislocation on CT), and find minimal or no evidence whatsoever of articular cartilage softening or breakdown on arthroscopic or open evaluation.
Subluxation will predispose a patient, however, to dislocation, and dislocation itself will cause substantial injury both to the medial patellar facet and the lateral femoral trochlea in most patients (Fig. 11.45). Such injuries will increase the risk of articular cartilage injury substantially.
Subluxation of the patella, as an isolated entity, is less destructive of the patella than other mechanical disorders. It is the association of tilt or dislocation with subluxation that creates a more worrisome picture of traumatic articular cartilage injury, lateral facet overload, or progressive arthrosis. In short, then, the clinician should look most critically at the presence of tilt as a harbinger of arthrosis, and treat subluxation as it limits function or is associated with recurrent patellar instability. Iwano et al (57) have reported that 28% of patients with isolated patellofemoral osteoarthritis have a history of patellar subluxation or dislocation.
Inside Chapter 11: