Association between hospital and surgeon procedure volume and outcomes of total hip replacement in the United States Medicare population. - Katz,J.N.; Losina,E.; Barrett,J.; Phillips,C.B.; Mahomed,N.N.; Lew,R.A.; Guadagnoli,E.; Harris,W.H.; Poss,R.; Baron,J.A. (J Bone Joint Surg [Am], 2001)