Incidence and evolution of chondral lesions of the knee

Chondral lesions of the knee are frequent in sports traumatology. The most commonly utilized classifications for cartilage lesions are the Outerbridge (Table 1) and the ICRS classification. Full thickness chondral Outerbridge grade 3 and 4 lesions seem to be less frequent, and sometimes it is possible to make an incidental diagnosis while treating arthroscopically meniscal or ligamentous pathologies of the knee. In a recent study, Widuchowski et al. (3), on a total of over 25,000 arthroscopic procedures, have reported chondral defects in 60% of the patients: 42% were grade 2 Outerbridge lesions. Curl et al. (2) on a total of 31,000 arthroscopies, have shown lesions in 63% of the procedures. Patients under 40 years of age with grade IV lesions accounted for 5% of all arthroscopies. no associated ligamentous or meniscal pathology was found in 37% of these patients. In a study conducted by Aroen et al on a sample of 993 consecutive knee arthroscopies, articular cartilage pathology was found in 66% and a localized cartilage defect was found in 20% of the knees. A localized full-thickness cartilage lesion (ICRS grade 3 and 4) was observed in 11% of the knees. The patellar articular surface (11%, 36-38%) and the medial femoral condyle (32-34%, 58%) are the most frequent localizations of these lesions. Isolated full-thickness grade 3 and 4 Outerbridge defects are the most commonly associated to medial meniscus (37% – 42%) and ACl (26%) tears: exists an important variability between the association to acute (23%) and chronic (54%) ACl deficiency. The mean Outerbridge grade 3 or 4 defect size is 1.7-2.1 cm2 (1). The high arthroscopic incidence of isolated chondral lesions may lead to think that many are asymptomatic. nevertheless Messner and Maletius have reported good to excellent results at 14 years since diagnosis in 22/28 patients with untreated isolated chondral lesions, but most part of their patients showed abnormal X-Rays aspects at follow up. This result suggests a degenerative progression of many asymptomatic lesions. Some studies report an increase of defect size in 37%, and poor subjective results in 33% of patients, with a significative correlation to sex, age, BMI and initial size of the lesion . In another study Maletius and Messner have reported results at 12 to 15 years of follow up in 42 patients showing chondral lesion, treated with or without partial meniscectomy. X-Rays showed modifications in all patients, but worse results were reported in those having both chondral and meniscal lesions (P<0.03). Shelbourne et al, in a perspective study in 2003, evaluated clinical and functional outcomes at a mean follow up of 6 years, among patients arthroscopically treated for ACl reconstruction, who had an articular cartilage defect of Outerbridge grade 3 or 4 but had both menisci intact. Results showed significantly lower subjective scores (IKdC), than did the patients from a control group having intact cartilage, even if patients had few symptoms, and the distribution of IKdC radiographic ratings was not significantly different between the groups. Cartilage defects of knee articular surface, due to traumatic or degenerative factors, if untreated can often progress, leading to symptoms and X-Rays signs of osteoarthritis.