Assessment of the radioanatomic positioning of the osteoarthritic knee in serial radiographs: comparison of three acquisition techniques.

OBJECTIVE: Recent studies using various standardized radiographic acquisition techniques have demonstrated the necessity of reproducible radioanatomic alignment of the knee to assure precise measurements of medial tibiofemoral joint space width (JSW). The objective of the present study was to characterize the longitudinal performance of several acquisition techniques with respect to long-term reproducibility of positioning of the knee, and the impact of changes in positioning on the rate and variability of joint space narrowing (JSN). METHODS: Eighty subjects were randomly selected from each of three cohorts followed in recent studies of the radiographic progression of knee osteoarthritis (OA): the Health ABC study (paired fixed-flexion [FF] radiographs taken at a 36-month interval); the Glucosamine Arthritis Intervention Trial (GAIT) (paired metatarsophalangeal [MTP] radiographs obtained at a 12-month interval), and a randomized clinical trial of doxycycline (fluoroscopically assisted semiflexed anteroposterior (AP) radiographs taken at a 16-month interval). Manual measurements were obtained from each radiograph to represent markers of radioanatomic positioning of the knee (alignment of the medial tibial plateau and X-ray beam, knee rotation, femorotibial angle) and to evaluate minimum JSW (mJSW) in the medial tibiofemoral compartment. The effects on the mean annualized rate of JSN and on the variability of that rate of highly reproduced vs variable positioning of the knee in serial radiographs were evaluated. RESULTS: Parallel or near-parallel alignment was achieved significantly more frequently with the fluoroscopically guided positioning used in the semiflexed AP protocol than with either the non-fluoroscopic FF or MTP protocol (68% vs 14% for both FF and MTP protocols when measured at the midpoint of the medial compartment; 75% vs 26% and 34% for the FF and MTP protocols, respectively, when measured at the site of mJSW; P<0.001 for each). Knee rotation was reproduced more frequently in semiflexed AP radiographs than in FF radiographs (66% vs 45%, P<0.01). In contrast, the FF technique yielded a greater proportion of paired radiographs in which the femorotibial angle was accurately reproduced than the semiflexed AP or MTP protocol (78% vs 59% and 56%, respectively, P<0.01 for each). Notably, only paired radiographs with parallel or near-parallel alignment exhibited a mean rate of JSN (+/-SD) in the OA knee that was more rapid and less variable than that measured in all knees (0.186+/-0.274 mm/year, standardized response to mean [SRM]=0.68 vs 0.128+/-0.291 mm/year, SRM=0.44). CONCLUSION: This study confirms the importance of parallel radioanatomic alignment of the anterior and posterior margins of the medial tibial plateau in detecting JSN in subjects with knee OA. The use of radiographic methods that assure parallel alignment during serial X-ray examinations will permit the design of more efficient studies of biomarkers of OA progression and of structure modification in knee OA.

Biomechanical, histologic and macroscopic assessment of articular cartilage in a sheep model of osteoarthritis.

OBJECTIVES: Our primary objective was to explore the full potential of the ovine medial meniscectomy (MMx) model of early osteoarthritis (OA) for studies to validate non-destructive articular cartilage (AC) assessments and therapeutic interventions. Our secondary objective was to re-evaluate the relationships between the different types of AC assessment after MMx in sheep. METHODS: Macroscopic assessments, dynamic shear modulus (G*), phase lag and AC thickness measurements were performed at a total of 5437 reference points on all six articular surfaces in four normal joints and 16 MMx ovine stifle (knee) joints. Comparisons with histologic assessments of gross structural damage, collagen organisation (birefringence) and proteoglycan content were possible at 702 of these points. RESULTS: Histologic gross structural damage and proteoglycan loss were seen throughout the joint with greatest severity (fibrillation) in closest proximity to the MMx site. Increases in AC (30-50%) thickness, reductions in G* (30-40%) and collagen birefringence intensity (15-30%) occurred more evenly throughout the joint. Macroscopic softening was evident only when G* declined by 80%. G* correlated with AC thickness (rho=-0.47), collagen organisation rho=0.44), gross structural damage (rho=-0.44) and proteoglycan content (rho=0.42). Multivariate analysis showed that collagen organisation contributed twice as much to dynamic shear modulus (t=6.66 as proteoglycan content (t=3.21). Collagen organisation (rho=0.11) and proteoglycan content (rho=0.09) correlated only weakly to phase lag. CONCLUSIONS: Macroscopic assessments were insensitive to AC softening suggesting that arthroscopic assessments of AC status might also perform poorly. Collagen integrity was more important for the maintenance of AC stiffness (G*) than proteoglycan content. The development of major AC softening and thickening throughout the joint following MMx suggested involvement of non-mechanical (e.g., protein and biochemical) chemical and cytokine mediated processes in addition to the disturbance in biomechanical loading. The ovine MMx model provides a setting in which the spectrum of AC changes associated with the initiation and progression of OA may be evaluated.

Interreader agreement in the assessment of magnetic resonance images of rheumatoid arthritis wrist and finger joints--an international multicenter study.

Magnetic resonance imaging (MRI) allows direct visualization of inflammation and destruction in rheumatoid arthritis (RA) joints. However, MRI scoring methods have not yet been standardized or appropriately validated. Our aim was to examine interreader agreement for a simple system of scoring RA changes on MRI among 5 centers that had not undertaken intergroup calibration. MRI of RA wrist and metacarpophalangeal (MCP) joints were scored by experienced readers in 5 centers in different countries. In substudy 1, 5 sets of 2nd-5th MCP joints from UK [Technique A: 1.5 T, coronal and axial T1 and T2 spin-echo, -/+ fat saturation (FS), -/+ iv gadolinium (Gd)] were scored for synovitis (score 0-3) and bone lesions (0-3). In substudy 2, we evaluated 19 sets of 2nd-5th MCP joints [10 sets from UK (Technique A) and 9 sets from the US (Technique B: 1.5 T; coronal T1 spin-echo and T2* gradient-echo + FS, no Gd)] and 19 wrist joints [9 from the US (Technique B) and 10 from Denmark (Technique C: 1.0 T; coronal and axial T1 spin-echo, no FS, -/+ Gd)]. Synovitis (0-3), bone lesions (0-3), and joint space narrowing (JSN, 0-3) were scored in each MCP joint and in 3 different regions of the wrist. Bone erosions and lesions in each bone were scored 0-5. Substudy 1 served to test and redesign the score sheets. In substudy 2, the scores of synovitis and bone lesions by the 5 groups were the same or differed by only one grade in 73% and 85% of joints, respectively. On MRI that included 2 imaging planes and iv Gd (Techniques A and C), these rates were 86% (synovitis) and 97% (bone lesions). Corresponding intraclass correlation coefficients (quadratic weighted kappas) were 0.44-0.68, mean 0.58 (synovitis), and 0.44-0.69, mean 0.62 (bone lesion), i.e., in the moderate to good range. Unweighted kappa values were in the low to moderate range, generally lowest for JSN (< 0.20), better for synovitis and bone erosions, and best for bone lesions, being generally highest for MRI with 2 planes pre- and post-Gd and in MCPjoints compared with wrists. These preliminary results suggest that the basic interpretation of MRI changes in RA wrist and MCP joints is relatively consistent among readers from different countries and medical backgrounds, but that further training, calibration, and standardization of imaging protocols and grading schemes will be necessary to achieve acceptable intergroup reproducibility in assessing synovitis and bone destruction in RA multicenter studies.

Preliminary core set of domains and reporting requirements for longitudinal observational studies in rheumatology.

Observational and longitudinal observational studies (LOS) provide essential information about the course and outcome of rheumatic disorders that cannot be provided by randomized controlled trials, and they constitute the major clinical scientific communication in rheumatology. There has been no consensus as to the full and appropriate content of LOS. This report defines a core set of domains and reporting requirements for LOS. At the 1998 OMERACT IV Conference a consensus process evaluated the literature of rheumatology in light of the constructs, variables, and outcomes of rheumatology by using introductory lectures, nominal groups, and plenary sessions. The result of this process was to identify 5 "core" domains that should be included in every LOS: Health Status, Disease Process, Damage, Mortality, and Toxicity/Adverse Reactions. Two additional domains, Work Disability and Costs, were recognized as important, but need not be used in all LOS. Eleven subdomains were identified that divided the domains into convenient clinical and conceptual units. A set of reporting requirements was also determined. The core recommendations, which follow on the WHO ICIDH-2 outline, are not disease-specific; the substitution of different "disease process" and "damage" measures make them suitable for many rheumatic disorders. The core set is intended to serve as a core for LOS in almost all rheumatic conditions.