Interobserver and Intraobserver Reliability of the Enneking Classification in Plain Radiographic Staging of Benign Bone Tumors of the Extremities in Patients Seen at the Philippine General Hospital

  • Bernardino B. Alpuerto II Department of Orthopedics, Philippine General Hospital
  • Edward H.M. Wang Philippine General Hospital
Keywords: Enneking, tumors, reliability, interobserver, intraobserver


Objective. To determine the interobserver and intraobserver reliabilities of the Enneking Classification system in staging benign bone tumors.

Methods. Photographs of traditional plain radiographs of 65 histologically benign tumors from the PGH Department of Orthopedics Tumor Registry were used in the study. Nine Orthopedic surgeons (three consultants, one fellow, and five senior residents) staged the tumors using the Enneking Classification based on radiographic tumor-host margins. The photographs were sent to the surgeons twice (batch 1 and 2), three months apart, for staging. The Fleiss and Cohen kappa statistics were used to determine interobserver and intraobserver reliabilities, respectively. This is a pilot study.

Results. There was only fair interobserver reliability of the Enneking Classification staging with Fleiss kappa of 0.38 and 0.26 for batches 1 and 2, respectively. Also, there was only moderate intraobserver reliability (Cohen kappa 0.48) for the staging. Moreover, there was also a relatively low intraobserver percent agreement (67%) among raters. In both reliabilities, the consultants/fellow group consistently showed better interobserver and intraobserver reliabilities compared to the residents.

Conclusion. The Enneking Classification in staging benign bone tumors had relatively low interobserver and intraobserver reliabilities. There was also a tendency of experienced orthopedic tumor consultants and senior residents to stage the same radiograph differently upon repeat testing.