Methodological challenges of multiple-component intervention: lessons learned from a randomized controlled trial of functional recovery after hip fracture.
Allegrante JP, Peterson MG, Cornell CN, MacKenzie CR, Robbins L, Horton R, Ganz SB, Ruchlin HS, Russo PW, Paget SA, et al. HSS J. 2007 Feb; 3(1):63-70.