In the treatment and management of certain physical and neurological conditions affecting gait and quality of life, surgical intervention plays a key role in changing the foundation of the body in a way that can ultimately make it a better, more efficient ‘machine’ in terms of physical activity and the abilities of the patient. Certain conditions such as amputation and cerebral palsy place the patient’s body in a position that is in many ways compromised in its ability to handle day to day tasks in a way that an able-bodied person would function. However, when we consider ‘functionality,’ it is important to recognize that attempting to make changes to merely make the patient physically similar to an unaffected person may not actually result in the best possible outcome for the patient. Instead, we must look towards quantifiable measures that provide better, more solid insight into how a person’s body may function post procedure while still possessing the prior condition (e.g., amputation or cerebral palsy). In Chapter 1, we examined an obese woman amputated unilaterally above the knee. Following long term use of a leg prosthesis, she received medial thighplasty limb revision surgery consisting of medial excision and circumferential liposuction of subcutaneous adipose tissue, of her residual limb to attempt to optimize socket fit and distal device function. We assessed whether various measures of physical function (metabolic cost and gait velocity) improved post surgery. In Chapter 2, we examined a series of three children with cerebral palsy who received a musculotendon lengthening through a surgical procedure known as selective percutaneous myofascial lengthening (SPML). The surgery was performed in an effort to increase knee joint range of motion, to reduce the presence of crouch gait, and to improve other spatiotemporal parameters of gait. By exploring these foundational cases in surgical intervention, future decisions concerning management of physical and neurological conditions may be better informed, and ultimately improve quality of life of these individuals.