[1] Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Dept Med, Div Gen Internal Med, New Brunswick, NJ 08903 USA
[2] Univ Maryland, Sch Med, Dept Epidemiol & Publ Hlth, Baltimore, MD 21201 USA
[3] Johns Hopkins Bayview Med Ctr, Baltimore, MD USA
[4] Univ Western Ontario, Div Orthopaed Surg, London, ON, Canada
[5] Univ Alberta, Dept Phys Therapy & Surg, Edmonton, AB, Canada
[6] Univ Alberta, Div Orthopaed Surg, Edmonton, AB, Canada
[7] Univ Calgary, Div Orthoped Surg, Calgary, AB, Canada
[8] Univ Calgary, Dept Med, Calgary, AB, Canada
[9] QEII Hlth Sci Ctr, Dept Orthoped Surg, Halifax, NS, Canada
[10] St Louis Univ, Sch Med, Dept Med, St Louis, MO 63103 USA
[11] Univ Med & Dent New Jersey, Sch Publ Hlth, Dept Epidemiol, Piscataway, NJ 08854 USA
[12] NHLBI, Transfus Med & Cellular Therapeut Branch, Div Blood Dis & Resources, Bethesda, MD 20892 USA
[13] Vet Affairs Med Ctr, Cooperat Studies Program Coordinating Ctr, Perry Point, MD USA
[14] Columbia Univ, Dept Orthoped Surg, New York Presbyterian Hosp, New York, NY USA
[15] Hartford Hosp, Hartford, CT 06115 USA
[16] Univ Minnesota, Sch Med, Minneapolis, MN 55455 USA
[17] Minneapolis Med Res Fdn Inc, Hennepin Cty Med Ctr, Minneapolis, MN USA