Introduction: Studies have shown that the Kellgren-Lawrence (K-L) score can differentiate the severity of osteoarthritis (OA). However, this grading system has not been compared with intraoperative assessment. The purpose of this study was to correlate the arthroscopic findings of knees with severe OA with their Kellgren-Lawrence grade.

Methods: Tibiofemoral knee OA was graded according to the K-L scale in 89 knees presenting for arthroscopic treatment for knee OA. The study group consisted of 55 males and 34 females with an average age of 55 (range 37 to 88) years. Each radiograph was examined by two orthopaedic surgeons, and arthroscopic data were collected prospectively.

Results: Radiographic grading yielded five knees with Grade 2 K-L, 47 with Grade 3 K-L, and 37 with Grade 4 K-L. At arthroscopy, ipsilateral tibial/femoral lesions were noted in 66 knees, including 17 knees with tibial/femoral lesions of both compartments. Meniscus pathology was present in 78 knees including 37 knees with both medial and lateral pathology. When comparing knees with radiographic K-L grades of 3 and 4, the following was noted: more males had Grade 4 K-L (p=0.001); knees with Grade 4 K-L were more likely to exhibit Outerbridge Grade III or IV tibial/femoral lesions on 3 or 4 surfaces (p=0.001); Grade 4 K-L knees had significantly more ipsilateral tibial/femoral lesions (p=0.000); and finally, Grade 4 K-L knees were more likely to contain meniscus pathology (p=0.032).

Conclusion: Grade 4 Kellgren-Lawrence scores correlated with more severe chondral degeneration and meniscus pathology. The Kellgren-Lawrence scale can differentiate between moderate and severe osteoarthritis.