... ofjoint debris that may cause a synovitis.Subchondral bone, periostium, synovium, ligaments, and joint capsule are all richly innervated and containnerveendingsthatmaybethesourceofpaininOApatients ... contributionsMI, KYI, TY, IN and HK conceived and designed the study. MI, TW, KN, HK, IF and AT undertook measurement of knee structures. MI, HK, IN, KK and RPhad the major role in analysis and interpretation ... identify early sys-temic differences in cartilage, bone and synovial metabo-lism that may be associated with joint pain in K/L grade1 (supposedly normal) patients and in early (K/L grade2)...