Simple geometry tribological study of osteochondral graft implantation in the knee

Robust preclinical test methods involving tribological simulations are required to investigate and understand the tribological function of osteochondral repair interventions in natural knee tissues. The aim of this study was to investigate the effects of osteochondral allograft implantation on the local tribology (friction, surface damage, wear and deformation) of the tissues in the natural knee joint using a simple geometry, reciprocating pin-on-plate friction simulator. In addition, the study aimed to assess the ability of osteochondral grafts to restore a low surface damage, deformation and wear articulation when compared to the native state. A method was developed to characterise and quantify surface damage wear and deformation of the opposing cartilage-bone pin surface using a non-contacting optical profiler (Alicona Infinite Focus). Porcine 12 mm diameter cartilage-bone pins were reciprocated against bovine cartilage-bone plates with 6 mm diameter osteochondral allografts, cartilage defects or stainless steel pins (positive controls) inserted centrally. Increased levels of surface damage with changes in geometry were not associated with significant increases in the coefficient of dynamic friction. Significant damage to the opposing cartilage surface was observed in the positive control groups. Cartilage damage, deformation and wear (as measured by change in geometry) in the xenograft (2.4 mm³) and cartilage defect (0.99 mm³) groups was low and not significantly different (p>0.05) compared to the negative control in either group. The study demonstrated the potential of osteochondral grafts to restore the congruent articular surface and biphasic tribology of the natural joint. An optical method has been developed to characterise cartilage wear, damage and deformation, that can be applied to the tribological assessment of osteochondral grafts in a whole natural knee joint simulation model

Artificial intelligence in osteoarthritis: repair by knee joint distraction shows association of pain, radiographic and immunological outcomes

Objectives Knee joint distraction (KJD) has been associated with clinical and structural improvement and SF marker changes. The current objective was to analyse radiographic changes after KJD using an automatic artificial intelligence-based measurement method and relate these to clinical outcome and SF markers. Methods Twenty knee osteoarthritis patients were treated with KJD in regular care. Radiographs and WOMAC were collected before and ∼1 year post-treatment. SF was aspirated before, during and after treatment; biomarker levels were assessed by immunoassay. Radiographs were analysed to obtain compartmental minimum and standardized joint space width (JSW), Kellgren–Lawrence (KL) grades, compartmental joint space narrowing (JSN) scores, and osteophytosis and sclerosis scores. Results were analysed for the most affected compartment (MAC) and least affected compartment. Radiographic changes were analysed using the Wilcoxon signed rank test for categorical and paired t-test for continuous variables. Linear regression was used to calculate associations between changes in JSW, WOMAC pain and SF markers. Results Sixteen patients could be evaluated. JSW, KL and JSN improved in around half of the patients, significant only for MAC JSW (P < 0.05). MAC JSW change was positively associated with WOMAC pain change (P < 0.04). Greater monocyte chemoattractant protein 1 (MCP-1) and lower TGFβ-1 increases were significantly associated with changes in MAC JSW (P < 0.05). MCP-1 changes were positively associated with WOMAC pain changes (P < 0.05). Conclusion Automatic radiographic measurements show improved joint structure in most patients after KJD in regular care. MAC JSW increased significantly and was associated with SF biomarker level changes and even with improvements in pain as experienced by these patients

Clinical significance of quantitative immunohistology in labial salivary glands for diagnosing Sjogren's syndrome

Objectives. Because patients with primary Sjogren's syndrome (pSS) are at risk of developing other autoimmune phenomena and malignant lymphoma, it is important to distinguish pSS from non-Sjogren's (nSS) sicca syndrome. However, this distinction might be difficult because of the lack of a gold standard for pSS. We studied the clinical significance of quantitative immunohistology (QIH) in labial salivary glands for diagnosing pSS. Methods. In a model mimicking the making of a clinical diagnosis, five experts diagnosed 396 patients as nSS, 'indefinite', pSS or secondary SS (sSS) using 25 clinical parameters. Patients were diagnosed twice, namely without (yielding gold-standard diagnoses) and with knowledge of QIH. The numbers of changes in diagnosis from 'indefinite' to 'definite' (nSS, pSS or sSS) or vice versa were compared. Patient groups with vs without a changed diagnosis in the four gold-standard diagnosis groups were compared regarding objective autoimmune parameters. Results. Sensitivity, specificity, positive and negative predictive value for abnormal QIH in pSS vs nSS were 93, 86, 76 and 96%, respectively. Changes in diagnosis from 'indefinite' to 'definite' (31%) were found more often (P = 0.00) than changes from 'definite' to 'indefinite' (10%). Knowledge of QIH distinguished patient groups within the gold-standard nSS, indefinite and pSS patient group with regard to autoimmune parameters. Conclusion. In view of the consequences of distinguishing pSS from nSS, these results point to an additional diagnostic role for QIH in clinical practice

Cartilage repair activity during joint-preserving treatment may be accompanied by osteophyte formation

Knee joint distraction (KJD) treatment has shown cartilage repair and clinical improvement in patients with osteoarthritis, as has high tibial osteotomy (HTO). Following KJD, TGFβ-1 and IL-6 were increased in synovial fluid (SF), factors related to cartilage regeneration, but also to osteophyte formation. As such, osteophyte formation after both joint-preserving treatments was studied. Radiographic osteophyte size was measured before, one year, and two years after treatment. Changes were compared with natural progression in patients from the CHECK cohort before undergoing total knee arthroplasty. An additional KJD cohort underwent SF aspiration, and one-year Altman osteophyte score changes were compared to SF-marker changes during treatment. After two years, both KJD (n = 58) and HTO (n = 38) patients showed an increase in osteophyte size (+6.2 mm2 and +7.0 mm2 resp.; both p < 0.004), with no significant differences between treatments (p = 0.592). Untreated CHECK patients (n = 44) did not show significant two-year changes (+2.1 mm2; p = 0.207) and showed significant differences with KJD and HTO (both p < 0.044). In SF aspiration patients (n = 17), there were significant differences in TGFβ-1 changes (p = 0.044), but not IL-6 (p = 0.898), between patients with a decrease, no change, or increase in osteophyte Altman score. Since KJD and HTO showed joint space widening and clinical improvement accompanied by osteophyte formation, increased osteophytosis after joint-preserving treatments may be a bystander effect of cartilage repair activity related to intra-articular factors like TGFβ-1 and raises questions regarding osteophyte formation as solely characteristic of the joint degenerative process