Clinical and morphological features of age-related, posttraumatic and metabolic phenotypes of late stage knee osteoarthritis

Abstract

Purpose: To verify clinical, functional, and morphological differences among age-related, posttraumatic and metabolic osteoarthritis (OA) phenotypes in patients with advanced gonarthrosis. Methods: The study covered 120 patients with gonarthrosis (Altman R.D., 1991) of III-IV radiological stages (Kellgren and Lawrence, 1957) hospitalized for total knee replacement. Age-related (over 50 years, absence of previous joint injury and metabolic syndrome, normal body mass index), posttraumatic, metabolic, mixed phenotypes (combination of all factors) were identified and studied, taking into account influence of the most common OA risk factors and proposed classifications in scientific literature (G.Musumeci et al., 2015; A.Dell'Isola et al., 2016; G.Herrero-Beaumont et al., 2017). There were 30 people in every group, and the informed consent was obtained. All patients have undergone clinical examination with filling out WOMAC questionnaire, algofunctional Lequesne index for knee OA, Visual Analogue Scale (VAS). To assess the quality of life the questionnaire MOS SF-36 was used. In 10 patients of every group (total n=40), histopathological study of medial tibiofemoral condyle cartilage and areolar synovial membrane of knee joints was performed using histochemical methods, Mankin H.J.(1971) and Krenn V.(2002) scales. Quantitative data were processed statistically. Results: Female predominance was found in all groups, however the largest number of women was found in metabolic (n=26, 86.7%) and mixed (n=26, 86.7%) phenotypes in comparison with age-related OA (n=18, 60%; р=0,019). The average age of patients with age-related phenotype was the highest (72,5[63; 77] years), and significant differences were detected compared with posttraumatic (62,5 [59; 64] years, p=0.001), metabolic (63 [57;68] years, p = 0.010), mixed (60 [56;64] years, p=0.001) OA. Synovitis was revealed significantly more frequently in metabolic OA (n=23, 76.7%) in comparison with age-related phenotype (n=13, 43.3%; р=0.008). The pain level according to VAS corresponded to severe (7-8 points) in all patients and did not have significant differences between the groups. The highest values of WOMAC questionnaire were found in metabolic phenotype (188 [162;207]), the lowest - in posttraumatic OA (129 [100;166], р=0,001). Lequesne index was the lowest in patients with posttraumatic phenotype (15 [14;19]) and the highest in patients with age-related and metabolic OA (20 [18;21], р=0,004; 20 [19;23], р=0,003, respectively). The lowest values of quality of life were in group of patients with metabolic phenotype (Physical Health - 28 [24.3;31.9], Mental Health - 30.9 [26.9;35.9]), the highest - in posttraumatic OA (34,1 [30,5;36,1], р=0,014 and 40,4 [32,9;43,8], р=0,005, respectively). Histopathological study showed that articular cartilage of patients with age-related OA phenotype was characterized by deep erosions, denudation of subchondral bone, hypocellularity, severe decrease of proteoglycans content. In synovial membrane, lipomatosis and severe inflammatory infiltration were found. In posttraumatic OA numerous surface defects, fibrous cartilage replacement, and chondrocyte clustering were revealed in articular cartilage, and fibrosis was detected in synovial membrane. In metabolic phenotype pronounced vascularization, ossification of articular cartilage, synovial hyperplasia, microcirculation disorders and monocyte/macrophage infiltration were observed. Mixed OA was characterized by combination of variable sings. The most severe cartilage damage according to Mankin scale was shown in age-related OA (8.5 [6;10] points). Significant differences were found in comparison with metabolic phenotype (6 [4.5;6.5] points; (р=0,001). High-grade synovitis was detected in patients with age-related and metabolic OA (5 [3;8] and 4 [3;5] points by Krenn scale, respectively). Conclusions: Age-related, posttraumatic and metabolic OA phenotypes in patients with III-IV radiological stages of gonarthrosis are characterized by various clinical and morphological features. In age-related OA phenotype late clinical debut, moderate pain and dysfunction of knee joints, severe degenerative-dystrophic changes in cartilage and synovial membrane were observed. Posttraumatic OA phenotype was characterized by mild clinical and functional disorders, acceptable quality of life of patients, severe cartilage damage, activation of reparative mechanisms, synovial fibrosis. In metabolic OA phenotype female predominance, frequent clinical synovitis, pronounced clinical and functional manifestations, low quality of patients life, cartilage vascularization and ossification, severe synovial microcirculation disorders were found. Mixed OA phenotype was characterized by variable clinical and morphological picture.