Isolated chondral fractures of the knee.

Eighteen patients with isolated chondral fractures of the knee were reviewed to reevaluate the clinical signs and symptoms. No other conditions had been present to account for the symptoms. Most of the patients had significant injuries often involving a flexed knee. All patients had had symptoms and physical findings strongly suggestive of meniscal abnormality. Roentgenographic examinations were noncontributory. The lesions occurred in four distinct patterns. All were full thickness. Many of the lesions occurred on the posterior aspect of a femoral condyle, a location where they could be easily overlooked if the condyle were not examined with the knee in extreme flexion. Abutment of the tibial spine against the medial femoral condyle may be one cause of these injuries. The incidence of isolated chondral fractures was found to be higher than previously reported. A negative arthroscopic meniscal examination in a patient with symptoms and physical findings suggestive of meniscal abnormality should alert the physician to the possibility of an isolated chondral fracture.