Ana M. Herrero-Beites, Nerea Pérez-Herrero, Fernando Pérez-Ruiz
Affiliation(s):
Cruces Rheumatology Division
Background: calcium pyrophosphate crystals have been retrieved in synovial fluid of joints during total knee arthroplasty in up to 30% (Berfus BA, et al. J Rheumatol 2002), although a diagnosis of calcium pyrophosphate arthritis (CPA) is only present in 0.20% of knee prothesis files (Paperis K, et al. Clin Rheumatol 2022) and in only 0.15% of hip prothesis (Parperis K, et al. Semin Arthritis Rheum 2023). Knee and hip prothesis have not been considered as a core outcome for OMEARCT OMERACT (Zhang Y et al, et al. Semin Arthritis Rheum 2025), not analyzed associated to clinical phenotypes in the EULAR/ACR CPA classification database (Latourte T, et al. A&R 2024).
Objective: to study variables associated to total joint prosthesis (TJP) in patients with CPA, including general, metabolic, and phenotype tanto variables, along with the diagnosis previous to surgery during orthopedic surgery (OS) evaluation.
Method: transversal study of patients fulfilling EULAR/ACR classification criteria. Genreal variables (age, gender), disease variables (time from onset, clinical phenotype, joint distribution, crown dens presence, knee-hip-both joints prosthesis,), metabolic factors (Ca/ P/ Mg/ SatFe%/ Ferritin/ 25OHD3/ Pth) were available for analysis. In addition, diagnosis from OS at the time of indication of surgery was retrieved.
Results: data from 345 patients were available, 188 women (54.5%), mean age 78 years (median 79, IC range 71-86), time from onset 6.6 years (6, 1-11), chronic inflammatory phenotype 167 (48,4%), joint involvement monoarticular 143 (41.4%), oligoarticular 145 (42.1%), and polyarticular 57 (16.5%). A total joint prosthesis was present in 90 patients (26.1%), 46 (13.3%) knee, 27 (7.8%) hip, and 17 (4.9%) in both locations. Variables significantly associated to TJP were: older age (80 vs. 77 years), time from onset (11 vs. 5 years), multiple joint (51%, 35% y 8% respectively, chronic inflammatory phenotype (24 vs. 2%), and presence of crowned dens in CT scan (74% vs. 54%).
A diagnosis of “chondrocalcinosis” was retrieved in only 3/90 (3%) of patients with TJP and none of those without TJP. Osteoarthritis was the most frequent diagnosis from OS: 82/90 (91%) of patients with TJP and 96/143 (67%) in patients evaluated by OS but not with a TJP (p<0,01). Symptomatic diagnosis (“knee pain” and “hip pain”) was retrieved from OS in 7/90 (7.8%) of non-TJP and 38/143 (26.6%) patients with TJP.
Multivariate analysis showed that only time from onset (ExpB 1.21; IC 95% 1.13-1.31, p <0.001) y e and chronic inflammatory phenotype (ExpB 15,05; IC 95% 6.09-37.26, p< 0,001) were independently associated to TJP.
Conclusions: 1.- patients with CPA show a high rate of f TJP. 2.- CPA is seldom retrieved as a diagnosis by OS specialists. 3.- Time from onset and chronic inflammatory phenotype seem to be mostly associated to TJP.
Prospective studies are needed to investigate whether proper, early diagnosis, and treatment would reduce the rate of TJP, especially in patients showing a chronic inflammatory phenotype.