Proximal femoral and periacetabular osteotomies for the treatment of osteoarthrosis have produced varying clinical results. Because the underlying pathomechanics of osteoarthrosis are not yet fully understood, it is difficult to predict which type of osteotomy will most improve the biomechanical environment in a given situation. Osteotomies result in relatively small changes in joint load (10% to 20% at most), which probably do not govern tissue responses. However, osteotomies do change the distribution of the load (i.e., stresses) and, perhaps more important, stress gradients. These changes in contact and underlying stresses undoubtedly affect cartilage and bone adaptation. It is likely that the magnitude of stress and strain in cartilage and underlying bone can be altered in such a way that more predictable beneficial remodeling will occur. Emerging imaging and computational technologies may allow patient-specific modeling, which should improve the efficacy and durability of repair.