The Association Between Morphological Alterations Of Proximal Tibiofibular Joint(PTFJ) And Structural Changes In Knee Osteoarthritis

Purpose:Osteoarthritis?OA?is a common disease characterized by joint cartilage loss and osteophyte formation.With the further investigation of OA,it was found that OA was a multifactorial disease.Recently,it is reported that proximal fibular osteotomy is effective in the treatment of medial compartmental knee OA,suggesting that the PTFJ may play a role in the development of knee OA.Our study focuses on the association between the morphological parameters of the PTFJ,such as the configuration and inclination angle of this joint,and the structural changes of knee OA.Methods:We used cross-sectional data from Tasmanian Older Adult Cohort?TASOAC?study,a prospective,population-based study aimed at identifying the environmental,genetic,and biochemical factors associated with the development and progression of OA.Participants?n=1100?between the age of 50 and 80 years were randomly selected from the roll of electors in southern Tasmania with an equal number of men and women,and finally 1099 attended a baseline clinic.Institutionalized persons and subjects with contraindications to magnetic resonance image?MRI?and diagnosed rheumatoid arthritis were excluded.A consecutive sample of 967 participants who had knee MRI scans at baseline was included in this study.The general informations such as age,sex,height and weight were recorded by questionnaires.The scores of joint space narrowing?0-3?and osteophyte?0-3?were measured on the X-ray film of knee joint using Osteoarthritis Research Society International?OARSI?atlas.Radiographic OA?ROA?score was calculated by adding scores of joint space narrowing and osteophyte.A non-zero score in either joint space narrowing or osteophyte was regarded as the evidence of any ROA.Cartilage defects,Bone marrow lesions?BMLs?,cartilage volume were assessed on MRI by OsiriX software.The morphological parameters such as joint configuration and inclination angle were also assessed on MRI.We used different statistical models to analyze the associations between PTFJ parameters and knee structural changes,according to different data types.Results:In the first part,Seven PTFJ type configurations including plane?49.4%?,trochoid?31.9%?,double trochoid?4.3%?,saddle?5.4%?,condylar?5.3%?,trochlear?3.5%?and ball&socket?0.2%?were observed on MRI.Plane type was used as a comparator during data analysis because of its'large quantities and more regular shape.We found that irregular joint types?including double trochoid,saddle,condylar,trochlear and ball&socket?were statistically significantly and negatively associated with lateral tibial and femoral,but not medial tibial and femoral cartilage volume.Comparing with plane PTFJ type,knees with PTFJ irregular joint types had about 0.09to 0.25 cm³ fewer cartilage volume at lateral tibial and femoral compartments.Furthermore,we found that irregular joint types were positively and statistically significantly associated with all knee structural abnormalities?cartilage defect,Bone marrow lesions,osteophyte?at the lateral tibial and femoral,but not medial tibial and femoral,sites.In the second part,we focused on the measurements of the inclination angle of PTFJ and analyzed its'associations with knee structural changes.We found that the PTFJ inclination angle was significantly and negatively associated with cartilage volume at lateral tibial and femoral,but not medial tibial and femoral,sites.The PTFJ inclination angle was significantly and positively associated with cartilage defects at lateral tibiofemoral,but not medial tibiofemoral,sites.And also,it was significantly and positively associated with BMLs at lateral tibial,but not medial tibial and femoral,sites.Furthermore,we found that the PTFJ inclination angle was positively associated with the incidence of ROA in female participants.Conclusions:Irregular PTFJ configurations and inclination angles are associated with osteoarthritic changes in the lateral,but not medial,tibiofemoral compartment of knee joint.The causal relationship needs to be examined in future longitudinal studies.