We studied radiologically the progression of ossification between the OPLL and the OALL in 52 cases of cervical OPLL patients who had been treated conservatively. Remarkable progression of the OALL was seen in 27 of 52 cases (52%). Considering corelation between the type of OPLL and the progression of OALL, remarkable progression of OALL was seen in 80% of mixed type, 50% of continuous type, 37% of segmental type in all of the patienis. In the cases followed for more than five years, remarkable progression was seen in 90% of mixed type, 60% of continuous type, 80% of segmental type. There was a tendency of remarkable progression of OALL in group of remarkable progression of OPLL. It was suggested that there is some corelation between the OPLL and the OALL in progression.
