Original Article
Knee Chondral Lesions: Incidence and Correlation Between Arthroscopic and Magnetic Resonance Findings

https://doi.org/10.1016/j.arthro.2006.11.015Get rights and content

Purpose: To determine the incidence and morphologic characteristics of knee chondral lesions found at arthroscopy and their correlation with magnetic resonance imaging (MRI). Methods: This is a prospective study on 190 consecutive knee arthroscopic procedures performed between March 2003 and February 2004 by the same surgical team. The study group’s age average was 34.8 years (14 to 77 years). The indication for surgery included anterior cruciate ligament tears, meniscal tears, and anterior knee pain. Patients without a preoperative MRI study were excluded. MRI reports were performed by qualified radiologists in all the cases. Chondral lesions were classified according to the International Cartilage Repair Society (ICRS) classification and were included in a database along with the MRI reports. The results were analyzed statistically with analysis of variance, Pearson, kappa, and χ-square tests. Results: One hundred fifteen chondral lesions in 82 patients were found during the arthroscopic procedure. Most of them were single lesions (72%) located on the medial femoral condyle (32.2%) or medial patellae (22.6%); 62.6% of the lesions were classified as ICRS type 2 or 3-A, with an average surface of 1.99 cm2. We found a significant direct correlation between the patient’s age and the size of the lesion (P = .001). MRI sensitivity was 45% with a specificity of 100%. The sensitivity increased with deeper lesions (direct relation with the ICRS classification). Our results showed a statistical power of 100%. Conclusions: Although unenhanced MRI using a 1.5-Tesla magnet with conventional sequences (proton density-weighted, T1-weighted, and T2-weighted) is most accurate at revealing deeper lesions and defects at the patellae, our study shows that a considerable number of lesions will remain undetected until arthroscopy, which remains the gold standard. Level of Evidence: Level III, diagnostic study of nonconsecutive patients.

Section snippets

Methods

Between March 2003 and February 2004, 250 knee arthroscopic procedures were performed in the same hospital by 2 surgeons with 15 years of experience in knee surgery.

Excluding patients without a preoperative MRI, 190 patients were eligible for this study (116 males and 74 females), with an average age of 34.8 years (range, 14 to 79 years). MRI was performed in a 1.5-Tesla GE machine (GE Medical Systems, Milwaukee, WI), with proton density, T1, and T2 sequences in axial, coronal, and sagittal

Results

During arthroscopic surgery, 82 out of 190 knees (43.16%) had at least 1 chondral lesion (ICRS classification 1 or more), represented by 40 women and 42 men with an average age of 41.12 years (14 to 79 years, standard deviation = 16.51). We found a total of 115 lesions in 82 knees. Single lesions accounted for 72% of all the defects (Table 2).

Regarding their location, chondral lesions showed a predilection for the medial femoral condyle (32.2%), the medial articular surface of the patellae

Discussion

Our study confirms that cartilage defects are common findings in patients with knee symptoms with an indication of arthroscopic surgery. This has been previously stated by other authors in large series of patients: Curl et al.2 found 63% of cartilage defects in 31,516 patients of which 19% were Outerbridge IV lesions.2 Hjelle et al.3 reported 61% of chondral or osteochondral lesions in 1,000 consecutive arthroscopies. We found 43.6% of lesions in 190 arthroscopies, the majority of which were

Conclusions

Knee arthroscopy is a useful method for the evaluation of chondral lesions and is more accurate than MRI in the diagnosis of these injuries. Although unenhanced MRI using a 1.5-Tesla magnet with conventional sequences (proton density-weighted, T1-weighted, and T2-weighted) is most accurate at revealing deeper lesions and defects at the patellae, our study shows that a considerable number of lesions will remain undetected until arthroscopy, which remains the gold standard.

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    The authors report no conflict of interest.

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