The Kellgren‐Lawrence Grading Scale: Development of An Online Training Tutorial
Authors: Hayes Bethany , Kittelson Andrew , Loyd Brian , Stevens‐Lapsley Jennifer 
Published: November 2023

Background/ObjectiveKnee osteoarthritis (OA) is a degenerative form of arthritis characterized by skeletal changes, including osteophyte formation and joint space narrowing. In research, these changes are visualized by radiography, and the severity of radiographic OA is nearly always reported in terms of the semi‐quantitative (0–4 point) Kellgren‐Lawrence (KL) grading scale. However, several studies have documented unsatisfactory inter‐ and intra‐rater reliability of the KL grading scale. Therefore, the purpose of this study was to develop a training module to improve the reliability of this common, but highly subjective, tool.MethodsA 30‐minute training module was developed in an e‐learning authoring tool, Articulate Presenter. This experimental module included information related to 1) the history of the KL grading scale and its relatively poor reliability, 2) the normal anatomy of a knee as pictured on a radiograph and, 3) examples of each of the KL grades with detailed descriptions of the corresponding radiographic features. In the module, special attention was paid to features that distinguished KL grade definitions, namely: “definite” versus “possible” osteophytes, joint space narrowing, and bony deformity. A second module was also developed as a control, which provided a brief orientation to the KL grading scale and knee OA radiography but lacked an extended discussion of radiographic features specific to each KL grade. These modules were then tested in 4 graduate students at the University of Colorado, each with basic knowledge of radiography but no prior knowledge of the KL grading scale. Two of the students were educated in KL grading by the experimental training module, and two of the students were selected to receive the control module. Each student then completed a quiz that included KL grading of 30 unique knee radiographs, with an additional 15 replicates randomly interspersed. The weighted kappa (kw) statistic was used to calculate inter‐and intra‐rater reliability for KL grading amongst participants in the experimental and control groups.ResultsAltman's benchmark scale was used to compare reliability; 0–0.20 is regarded as poor reliability, 0.21–0.40 is fair reliability, 0.41–0.60 is moderate reliability, 0.61–0.80 is good reliability, and 0.81–1.0 is excellent reliability. Intra‐rater reliability of KL grading in the experimental group was excellent (kw=0.80), compared to good intra‐rater reliability (kw=0.65) in the control group. Inter‐rater reliability was good in the experimental group (kw=0.65), compared to moderate in the control group (kw=0.49).ConclusionTo our knowledge, this is the first study to attempt to standardize training in KL grading for knee OA and examine the effects of this training on reliability. Both intra and inter‐rater reliability were higher among participants who received the experimental training module, although further testing with larger sample sizes and formal randomization is required to determine if differences in reliability can be attributed to the training per se. Nevertheless, this study suggests that utilization of a training module for the KL grading scale may improve reliability among graders, and therefore, may improve the consistency of OA severity assessments in both clinical and research settings.Support or Funding InformationMSMHA Student Travel Award