Medial Pole Osteoarthritis Series Indicates Moderate Disease

Abstract

Background: Osteoarthritis (OA) is one of the leading causes of hip pain in the United States, with over half a million total hip arthroplasties (THA) performed every year. In hip OA radiographic joint space narrowing in the superior region of the hip is typical, with narrowing in the medial region less frequently reported. As this form of OA is relatively rare, patient characteristics and prognosis are poorly understood. The goal of the current study is to provide a more complete description of medial pole OA patients. Methods: The current study performed a retrospective review of prospectively collected cases of medial joint space narrowing identified by a single surgeon between 2015 and 2023. Patient characteristics, x-ray measures, and patient reported outcome measures were recorded before and after surgery (if performed). Results: The total number of patients in this study was 54, with 22 having bilateral radiographic signs of OA and average pain at first presentation of 6.85, with 10 representing maximal pain. The cases were more frequently in women (71 %) and most demonstrated an “eyebrow” sign on anterior-posterior (AP) x-rays, with all cases Kellgren-Lawrence ≥3 exhibiting the “eyebrow” feature. Center edge angle, femoral neck angle, Tonnis Angle, and abduction lever arm ratio all fell within previously published ranges. A new x-ray view (Flint View) showed posterior joint space narrowing. Conclusions: Typically medial pole cases occurred in women with a characteristic radiographic presence of an “eyebrow sign”. Patient joint geometry measures and pain scores fall within typical ranges for hip OA patients.

Keywords

• Osteoarthritis
• Medial pole