(A) At least once each year during the first five years following the retirement of a member with a disability pension, and at least once in every three-year period thereafter, the Board may require, and upon the retirant's application shall require, any disability retirant who has not attained his voluntary retirement age to undergo a medical examination to be made by or under the direction of a physician designated by the Board. Should the retirant refuse to submit to a medical examination in any such period, his disability pension may be discontinued by the Board, and should refusal continue for one year, all his rights in and to the pension may be revoked by the Board.
(B) If upon a medical examination of a retirant, the physician reports to the Board that the retirant is physically able and capable of resuming employment with the city, he shall be restored to active service with the city and his disability pension shall be discontinued. A disability retirant who has been or shall be returned to active service in the employ of the city shall again become a member of the retirement system. His credited service at the time of his retirement shall be restored to his credit. He shall be given service credit for the period he was in receipt of workmen's compensation benefits on account of his disability arising out of and in the course of his employment with the city.
(‘83 Code, § 36.40)