Advanced trans-tibial socket fabrication using selective laser sintering.

There have been a variety of efforts demonstrating the use of solid freeform fabrication (SFF) for prosthetic socket fabrication though there has been little effort in leveraging the strengths of the technology. SFF encompasses a class of technologies that can create three dimensional objects directly from a geometric database without specific tooling or human intervention. A real strength of SFF is that cost of fabrication is related to the volume of the part, not the part's complexity. For prosthetic socket fabrication this means that a sophisticated socket can be fabricated at essentially the same cost as a simple socket. Adding new features to a socket design becomes a function of software. The work at The University of Texas Health Science Center at San Antonio (UTHSCSA) and University of Texas at Austin (UTA) has concentrated on developing advanced sockets that incorporate structural features to increase comfort as well as built in fixtures to accommodate industry standard hardware. Selective laser sintering (SLS) was chosen as the SFF technology to use for socket fabrication as it was capable of fabricating sockets using materials appropriate for prosthetics. This paper details the development of SLS prosthetic socket fabrication techniques at UTHSCSA/UTA over a six-year period.

Gait variables differentiating fallers from nonfallers.

PURPOSE: This study examined the qualitative and quantitative differences between 2 groups of older adults, fallers and nonfallers. We compared walking differences during overground walking to a task of obstacle clearance. METHODS: Forty-eight community dwelling older adults (18 fallers and 30 nonfallers) participated. The mean age of the participants was 78.1 +/- 7.2 years (fallers) and 75.8 +/- 5.1 years (nonfallers). Walking differences within and between fallers and nonfallers during a single visit for 6 conditions were examined: (1) baseline walking, (2) slow walking, (3) fast walking, and (4) 5 cm obstacle clearance - approach, during, and exit. Quantitative differences of temporal-spatial walking measures were analyzed using a multifactorial ANOVA adjusted for age, gender, height, and BMI with a Scheffe correction (p < 0.05) applied for multiple testing. Qualitative data were analyzed using Chi-square fisher's exact test. RESULTS: There were interaction effects for group by walking condition for single support (p = 0.002) and step length (p = 0.05), while 1st double support approached significance (p = 0.06). Main Group effects were found during the comfortable walk (p < 0.001-0.05) for all 7 gait variables. Qualitatively, the fallers demonstrated increased knee flexion during both over ground walking (c2 = 9.01 ; p < 0.006), and the fallers consistently took several small steps immediately prior to the obstacle clearance (c2 = 8.42 ; p = 0.007). CONCLUSION: There were significant differences in quantitative and qualitative walking characteristics differentiating fallers from nonfallers during over-ground walking at different velocities and during obstacle clearance.

Kinetics of high-heeled gait.

A within-subject comparative study of walking while wearing low-heeled sports shoes versus high-heeled dress shoes was performed to identify and describe changes in lower-extremity joint kinetics associated with wearing high-heeled shoes during level overground walking. A volunteer sample of 15 unimpaired female subjects recruited from the local community underwent quantitative measurement of sagittal and frontal plane lower-extremity joint function, including angular motion, muscular moment, power, and work. When walking in high-heeled shoes, a significant reduction in ankle plantar flexor muscle moment, power, and work occurred during the stance phase, whereas increased work was performed by the hip flexor muscles during the transition from stance to swing. In the frontal plane, increased hip and knee varus moments were present. These differences demonstrate that walking in high-heeled shoes alters lower-extremity joint kinetic function. Reduced effectiveness of the ankle plantar flexors during late stance results in a compensatory enhanced hip flexor "pull-off" that assists in limb advancement during the stance-to-swing transition. Larger muscle moments and increased work occur at the hip and knee, which may predispose long-term wearers of high-heeled shoes to musculoskeletal pain.

Influence of rotators on the kinematic adaptations in stubby prosthetic gait.

We report on the results of gait analysis in a patient with bilateral knee disarticulation amputations who used short nonarticulated prosthetic limbs (stubbies) to meet his ambulation needs over an extended period. To compensate for the loss of knee and ankle articulations, exaggerated pelvic obliquity (hip hiking), transverse pelvic rotation, and hip abduction were needed to ensure limb clearance and a functional step length. The addition of rotators to the prostheses improved gait velocity and reduced the perceived exertion of walking by favorably altering center of mass energetics.