A method of immunoassay for distinguishing between pathological cartilage turnover and normal or benign cartilage turnover, the method comprising: a) detecting, in a sample, presence of at least one N- or C-terminal neoepitope of mammalian Cartilage Oligomeric Matrix Protein, COMP, wherein said at least one N- or C-terminal neoepitope is formed by cleavage of said mammalian COMP in pathological cartilage turnover, wherein said at least one N- or C-terminal neoepitope is not formed in normal or benign cartilage turnover, and wherein detecting presence of said at least one Nor C-terminal neoepitope comprises: contacting said sample with an isolated antibody, wherein said isolated antibody specifically binds to an N- or C-terminal neoepitope formed by cleavage of mammalian COMP in pathological cartilage turnover; and detecting presence of said at least one N- or C-terminal neoepitope in said sample based on said isolated antibody; and b) determining presence of pathological cartilage turnover based on said detected presence of said at least one N- or C-terminal neoepitope in said sample; wherein said isolated antibody specifically binds to an N-terminal neo-epitope amino acid sequence selected from the group consisting of: VRTGL (SEQ ID NO 33) LHCAP (SEQ ID NO 34) CAPGF (SEQ ID NO 35) TESGA (SEQ ID NO 36) CVPNS (SEQ ID NO 37) SVCIN (SEQ ID NO 38) RFCPD (SEQ ID NO 39) RAFQT (SEQ ID NO 40) NQGRE (SEQ ID NO 41) TAFNG (SEQ ID NO 42) NGVDF (SEQ ID NO 43) GDTES (SEQ ID NO 44) VGYIR (SEQ ID NO 45) VVLDT (SEQ ID NO 46) CFSQE (SEQ ID NO 47) or wherein said isolated antibody specifically binds to a C-terminal neo-epitope amino acid sequence selected from the group consisting of: GMQQS (SEQ ID NO 18) SVRPL (SEQ ID NO 19) RPLLH (SEQ ID NO 20) VACIQ (SEQ ID NO 21) TGQHN (SEQ ID NO 22) NCVPN (SEQ ID NO 23) QRRAQ (SEQ ID NO 24) TLTDF (SEQ ID NO 25) NWVVL (SEQ ID NO 26) LAVGY (SEQ ID NO 27) GYTAF (SEQ ID NO 28) ALWHT (SEQ ID NO 29) QHRPQ (SEQ ID NO 30) VADSN (SEQ ID NO 31) RLGVF (SEQ ID NO 32) a) detecting, in a sample, presence of at least one N- or C-terminal neoepitope of mammalian Cartilage Oligomeric Matrix Protein, COMP, wherein said at least one N- or C-terminal neoepitope is formed by cleavage of said mammalian COMP in pathological cartilage turnover, wherein said at least one N- or C-terminal neoepitope is not formed in normal or benign cartilage turnover, and wherein detecting presence of said at least one Nor C-terminal neoepitope comprises: contacting said sample with an isolated antibody, wherein said isolated antibody specifically binds to an N- or C-terminal neoepitope formed by cleavage of mammalian COMP in pathological cartilage turnover; and detecting presence of said at least one N- or C-terminal neoepitope in said sample based on said isolated antibody; and contacting said sample with an isolated antibody, wherein said isolated antibody specifically binds to an N- or C-terminal neoepitope formed by cleavage of mammalian COMP in pathological cartilage turnover; and detecting presence of said at least one N- or C-terminal neoepitope in said sample based on said isolated antibody; and b) determining presence of pathological cartilage turnover based on said detected presence of said at least one N- or C-terminal neoepitope in said sample; wherein said isolated antibody specifically binds to an N-terminal neo-epitope amino acid sequence selected from the group consisting of: VRTGL (SEQ ID NO 33) LHCAP (SEQ ID NO 34) CAPGF (SEQ ID NO 35) TESGA (SEQ ID NO 36) CVPNS (SEQ ID NO 37) SVCIN (SEQ ID NO 38) RFCPD (SEQ ID NO 39) RAFQT (SEQ ID NO 40) NQGRE (SEQ ID NO 41) TAFNG (SEQ ID NO 42) NGVDF (SEQ ID NO 43) GDTES (SEQ ID NO 44) VGYIR (SEQ ID NO 45) VVLDT (SEQ ID NO 46) CFSQE (SEQ ID NO 47) or wherein said isolated antibody specifically binds to a C-terminal neo-epitope amino acid sequence selected from the group consisting of: GMQQS (SEQ ID NO 18) SVRPL (SEQ ID NO 19) RPLLH (SEQ ID NO 20) VACIQ (SEQ ID NO 21) TGQHN (SEQ ID NO 22) NCVPN (SEQ ID NO 23) QRRAQ (SEQ ID NO 24) TLTDF (SEQ ID NO 25) NWVVL (SEQ ID NO 26) LAVGY (SEQ ID NO 27) GYTAF (SEQ ID NO 28) ALWHT (SEQ ID NO 29) QHRPQ (SEQ ID NO 30) VADSN (SEQ ID NO 31) RLGVF (SEQ ID NO 32)