Background Recent clinical trials of biologic agents have reported that radiographic evidence of healing was seen in patients with rheumatoid arthritis (RA) who were in clinical remission. However, those results were limited to small joints (hand and foot), while the effects on large weight-bearing joints (hip and knee) have not been clarified. Some other investigators reported1) that all hip and knee joints examined with pre-existing damage rated as Larsen grade2) III/IV showed joint-damage progression, even in patients with a good anti-inflammatory response to biologic agents such as anti-TNF. In contrast, another investigator reported3) a patient with RA who was treated with adalimumab and showed radiological evidence of reparative change of a previously damaged hip joint. Here, we present sevral cases of RA with observed clinical improvement as well as radiographic evidence of remodeling of a previously damaged hip joint. A characteristic radiological finding was noted in these cases, which may indicate remodeling.
Objectives The purpose of this study was to examine the implications of the radiographic “beak sign” at the hip joint.
Methods We retrospectively investigated RA patients who had complained of hip pain between January 2000 and December 2011 and were treated with biologic agents in our hospital. Not all cases needed total hip arthroplasty (THA).
Results Of 8 patients (mean age 57.6 years, range: 50-66; all female) with Larsen grade II or III destructive changes in RA hip joints before the start or during anti-TNF therapy, 5 patients underwent THA. 3 patients showed such clinical improvements throughout at least 5 years of follow-up, as well as radiographic evidence of hip remodeling, that they did not need THA, and they reported no hip pain at final follow up. A distinctive radiological finding which we call “beak sign” (Figure) became obvious within 2 years in all 3 of these cases, and it may indicate remodeling. Radiographs showed subchondral bone sclerosis of the femoral head and acetabular surfaces, as well as osteophyte formation in the lateral aspect of both the acetabulum and femoral head. This paired osteophyte formation resembles a bird's beak. In the 12 year period there were 561 primary THA cases in our hospital, of which 54 (9.6%) were RA cases. We checked all pre-operative X-rays, but found no beak signs in any RA cases which underwent THA.
Conclusions Since we found “beak sign” only in cases which had shown lasting good improvement and which required no THA, we suspect that even at an early developmental stage beak sign may be indicative of successful remodeling processes. To the extent that growth of beak sign paired osteophytes would not be expected if RA type joint erosion were still active, we consider that even early-stage beak sign development indicates clinical improvement (in our cases associated with anti-TNF therapy) such that THA may not become necessary.
Seki E, et al. Radiographic progression in weight-bearing joints of patients with rheumatoid arthritis after TNF-blocking therapies. Clin Rheumatol 2009;28:453–60.
Larsen A, et al. Radiographic evaluation of rheumatoid arthritis and related conditions by standard reference films. Acta Radiol Diagn 1977;18:481–91.
Momohara S, et al. Reparative radiological changes of a large joint after adalimumab for rheumatoid arthritis. Clin Rheumatol 2011;30:591–2.
Disclosure of Interest : None declared