Intra-articular pressure characteristics of the knee joint: An exploratory study

Inflammation-predominant osteoarthritis is an important clinical type of osteoarthritis, with synovitis suggested as its distinct pathophysiology. We investigated whether the synovium's mechanical properties in knees differed by osteoarthritis and other clinical parameters through retrospectively analyzing intra-articular pressure-volume characteristics. We analyzed 60 knees that were administered intra-articular corticosteroids while undergoing pressure monitoring. McMurray's test, pain complaints at end-range knee flexion, Kellgren-Lawrence classification from standing anteroposterior radiographs, and suprapatellar effusion from ultrasound constituted clinical parameters. Pressure-volume profiles-phasic changes in pressure by volume infusion, the volume of Phase 1-the potential volume of the synovial space, the pressure at 45 ml infusion-intra-articular pressure at a standardized volume, and the slope of Phase 2-synovial stiffness were compared with clinical parameters. All graphs were biphasic. Knees with suprapatellar effusion or radiologically definite osteoarthritis (Kellgren-Lawrence grade ≥2), had a lower Phase 1 volume. Knees with definite radiographic osteoarthritis also showed higher pressures at 45 ml and Phase 2 slopes (171.11 ± 94.35 mmHg and 5.08 ± 3.07 mmHg/ml, respectively) than those without (101.88 ± 58.12 mmHg and 2.84 ± 1.27 mmHg/ml, respectively). The Phase 2 slope was higher for knees with positive provocative tests than in those with negative provocative tests, although not statistically significant. The synovium stretched earlier in knees with effusion or radiologically definite osteoarthritis. Intra-articular pressure and synovial stiffness were significantly higher in patients with radiologically definite osteoarthritis. The synovium's mechanical characteristics are altered by osteoarthritis of the knee joint. Intra-articular pressure characteristics could be utilized for synovial evaluation clinically.

Medial Calcar Erosion Is Associated With Synovial Thickness in Patients With ASR XL Total Hip Arthroplasty

BACKGROUND

Medial calcar erosion is considered a late finding in patients with severe adverse local tissue reactions (ALTRs) after total hip arthroplasty (THA) with dual modular neck stems. Although calcar erosion has been associated with dual modular neck stems, one would expect similar findings in standard stems owing to analogous corrosion at the taper junction. The aim of this study was to evaluate whether medial calcar erosion is also associated with ALTR in patients with standard stems in metal-on-metal (MoM) THA.

METHODS

A total of 96 patients (108 hips) with MoM THA had radiographs and a magnetic resonance imaging of the hip performed at a mean time of 5.7 years after surgery. Calcar erosion was assessed from radiographs. ALTR Anderson grade, diameter, volume, and synovial thickness were assessed from magnetic resonance imaging.

RESULTS

Calcar erosion was present in 54 hips (50%) and was associated with ALTR synovial thickness but not with Anderson grade, diameter, or volume. Most of the hips with calcar erosion (n = 45) had an ALTR (positive predictive value 0.83, 95% confidence interval 0.70-0.92). The relative risk of having a synovial thickness > 3 mm increased by a factor of 3.0 (95% confidence interval 1.3-6.5) if calcar erosion was observed.

CONCLUSION

Subtle erosions of the medial calcar after MoM THA may be an early indicator of an adverse reaction to wear particles warranting cross-sectional imaging. Synovial thickness may also be more relevant than absolute size in the classification of ALTR severity and collateral tissue damage.

Clinical, laboratory, and ultrasound assessment of the knee in juvenile rheumatoid arthritis

Background:

The aim of this work was to study the ultrasonographic (USG) features of knee joints in relation to clinical and laboratory measures in patients with juvenile rheumatoid arthritis (JRA), and also to evaluate the accuracy of ultrasound in the diagnosis of local joint activity.

Methods:

This study included 20 with JRA and 20 matched and apparently healthy controls. All patients were subjected to full history taking, careful clinical examination and laboratory investigation. The knee joints of all patients and control were examined with plain radiography and ultrasonography on the same day of clinical examination using ultrasound to detect synovial thickness and effusion at the knee.

Results:

Mean USG knee synovial thickness was significantly greater in JRA patients versus controls (4.2 ± 2.4 mm versus 1.7 ± 0.3 mm, P < 0.001). Although knee effusion was not detected in any of the controls, it was demonstrated in 90% of JRA patients, with a mean effusion volume of 3.8 ± 3.1 mL. There was a statistically significant difference (P < 0.001) between clinically active and inactive knees with regard to knee synovial thickness. Mean knee effusion volume was significantly (P < 0.05) higher in the clinically active than in the clinically inactive knees. Patients with high disease activity had a significantly (P < 0.05) higher knee synovial thickness and knee effusion volume than patients with low and moderate disease activity. Significantly (P < 0.05) positive correlations were found between knee synovial thickness and articular index (AI) scores, disease activity score, clinical knee scores, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels. Significant positive correlations (P < 0.05) were found between knee effusion volume and AI scores, visual analog scores, disease activity scores, clinical knee scores, ESR, and CRP levels. Significant negative correlations (P < 0.05) were found between knee effusion volumes and hemoglobin levels.

Conclusion:

UGS-detected parameters represent a reliable index of JRA disease activity with a higher sensitivity for knee synovial thickness and higher specificity for knee effusion.