Background Osteoporosis is common in patients with rheumatoid arthritis (RA) even in the era of biologic therapy (BT). In the hand, osteoporosis includes periarticular lesions and cortical bone of the metacarpal diaphysis (MD). The latter is reported to serve as a surrogate marker of disease progression, morbidity, and hand function. Some patients with RA show laterality of loss of cortical bone of the MD, but few studies have focused on it.
Objectives To identify factors associated with loss of cortical bone of the MD and its laterality in patients with RA.
Methods We enrolled 143 RA patients (107 females; mean age 62.4 years; disease duration 11.1 years). We measured the average cortical rate (CR), provided by periosteal and endosteal diameters at the midpoint of both 2nd to 4th metacarpals in hand radiographs. The laterality of cortical bone of the MD was defined by the rate of right average CR to left one, which was >1.25 or <0.8. Bone destruction was defined > stage II by Steinbrocker's classification. We analyzed factors associated with low CR and its laterality among some clinical parameters, including bone destruction, handedness, hand surgical history, age, sex, RA duration, medication and disease activity of RA, positivity of RF and/or ACPA, medication for osteoporosis, body mass index (BMI), drinking, smoking, diabetes, and chronic kidney disease. Then, we investigated the impact of BT on low CR and its laterality.
Results Low CR (<50%) was detected in 74.1% in right, and 72.0% in left. Multivariable analysis revealed the association between low right CR and right wrist joint destruction (WJD) (p=0.049), and low left CR and age (p<0.01) and left WJD (p=0.013). Laterality of CR was detected in 16.8%. Predominant low right CR (group R) and left one (group L) were 7.7% and 9.1%, respectively. Patients with laterality showed lower BMI (p=0.044), and higher frequency of left WJD (p<0.01), than patients without it (group N). Multivariable analysis revealed the association between the laterality and left WJD (p=0.014). Patients in group R showed higher frequency of right WJD than those in group N (p=0.048). Patients in group L showed higher frequency of left WJD than those in group N (p<0.01). Multivariable analysis revealed the association between predominant low right CR and right WJD (p=0.11), and between predominant low left CR and left WJD (p<0.01). No impact on these associations was shown by other clinical parameters, including handedness, hand surgical history, and bone destruction of metacarpophalangeal joints. No patient showed improvement in the average CR on either side or its laterality even after BT.
Conclusions WJD was associated with loss of cortical bone from the MD on the ipsilateral side in patients with established RA. WJD was also associated with laterality of loss of cortical bone of MD, which was shown in about 17%. No patient showed improvement of bone loss on either side or laterality of MD after BT. These results suggest the necessity of aggressive therapy and specific concept of rehabilitation for wrist arthritis from the early phase of RA.
J Rheumatol 2006;33:508-16.
Disclosure of Interest None declared