Order and judgment (one paper), Supreme Court, New York County (Eugene L. Nardelli, J.), entered November 4, 1991, which denied petitioner’s application pursuant to CPLR article 78 to annul respondents’ determination denying petitioner’s application for an accident disability pension, and dismissed the petition, unanimously affirmed, without costs.
Petitioner claims that while on restricted duty because of several prior line-of-duty injuries, he injured his ankle while walking down the stairs of the office to which he was assigned when his "right knee gave out”. Although the Medical Board recommended approval of petitioner’s application for acciden*577tal disability retirement, the Board of Trustees was not bound thereby insofar as the cause of the disability is concerned (Matter of Canfora v Board of Trustees, 60 NY2d 347, 351), and we agree with the IAS Court that the Board’s determination that petitioner’s injury was not the result of an unexpected event, and thus not an "accident” within the meaning of the statute, was not arbitrary and capricious (see, Matter of Lichtenstein v Board of Trustees, 57 NY2d 1010). Concur— Murphy, P. J., Carro, Rosenberger, Ross and Asch, JJ.