A pelvic kinematic approach for calculating hip angles for active hip disarticulation prosthesis control.

BACKGROUND: Control system design for a microprocessor-controlled hip-knee-ankle-foot (HKAF) prosthesis is a challenge since hip disarticulation amputees lack the entire leg and, therefore, only have pelvis movement as user-guided input. This research proposes a method for determining hip joint angles from pelvis movement in a control system for the next generation of powered prostheses. METHOD: Three-dimensional pelvic motion and stance time of 10 transfemoral (TF) prosthetic users were used to identify important features and to develop an algorithm to calculate hip angles from pelvis movement based on correlation and linear regression results. The algorithm was then applied to a separate (independent) TF group to validate algorithm performance. RESULTS: The proposed algorithm calculated viable hip angles during walking by utilizing pelvic rotation, pelvic tilt, and stance time. Small angular differences were found between the algorithm results and motion capture data. The greatest difference was for hip maximum extension angle (2.5 ± 2.0°). CONCLUSIONS: Since differences between algorithm output and motion data were within participant standard deviations, the developed algorithm could be used to determine the desired hip angle from pelvis movements. This study will aid the future development of gait control systems for new active HKAF prostheses.

Hip disarticulation and hemipelvectomy prostheses: A review of the literature.

BACKGROUND: Although the global population of people with a hip disarticulation (HD) or hemipelvectomy (HP) amputation is small, the degree of disability is high, affecting function and independence. A comprehensive literature review is needed to examine the evidence for prostheses in these amputation levels. METHOD: A scoping literature review was conducted to examine related research documents from 1950 to September 2020, found using Scopus, Web of Science, PubMed, and Google Scholar databases. Studies evaluated (retrospectively or prospectively) HD or HP prostheses and were written in English. Study design and protocol, research instrument, sample size, and outcome measures were reviewed. RESULTS: In the past 70 years, 53 articles that evaluated HD or HP prostheses were published. Most research was conducted in the United States (24 articles) and Japan (nine articles). In 42 articles, authors prospectively evaluated the effects of prostheses in these amputation levels. On average, prospective studies had four (SD = 5) participants. Since 1950, only five prospective studies evaluated HD or HP prostheses with 10 or more participants. Moreover, sufficient information was often unavailable for research replication. CONCLUSION: More evidence is needed regarding the effects of HD or HP prosthetic components (i.e. hip, knee, ankle, socket type, and suspension system) on gait, patient satisfaction, prosthetic use, interface pressure, and energy expenditure. Articles mostly have small sample sizes that reduce confidence in the reliability of their findings and limit generalizability. Future investigations are needed with vigorous methodology and larger sample sizes to provide strong statistical conclusions.