Dervan rim sign new, simple radiological sign for unique Indian medial femoral condylar osteoarthritis

Abstract

Introduction: OA knee is most common form of arthritis in Asian population. The medial compartment of knee is most commonly involved. Most X-ray studies have been from the Western Caucasian patients with different genetic pool, habitus and lifestyle. The accepted norm for surgical intervention like unicondylar knee replacement or High Tibial Osteotomy is bone on bone Arthritis which has simultaneous affection of both medial Tibial & Femoral compartments. We however noted a different radiological pattern also causing severe pain on medial side of knee, without bone on bone arthritis. This was labeled DERVAN RIM SIGN.Materials and Method: This pilot Study describes a new radiological sign based on standard Anteroposterior Xray of knee joint, taken in standing weight bearing position with toes and patella pointing forwards in 15 degrees of flexion.The findings of this sign and correlation to selective medial condylar femoral cartilage loss in 25 patients are confirmed with1 MRI of knee joint 17 patients2 Arthroscopy of knee joint 3 patients3 Open Arthrotomy during Unicondylar knee Arthroplasty 5 patientsResults: 100 percent correlation is seen in all 25 cases between the Dervan RIM sign & Eburnation and loss of Medial femoral cartilage in the three modalities of visual confirmation viz MRI, Arthroscopy or Visual examination in open surgery. Mild involvement of the Tibial condyle was noted in all cases and this was the cause of absence of bone on bone Arthritis.