John W. Michael

Preliminary Evidence for Effectiveness of a Stance Control Orthosis

Individuals with lower limb paresis or paralysis have traditionally had limited orthotic options to provide knee stability during walking. Recent developments have made available new “stance control” orthoses that provide stability in stance while allowing free knee motion during swing phase. The purpose of this study was to determine whether individuals with lower limb weakness walk more efficiently when using the Stance Control Orthotic Knee Joint (SCOKJ®) than when using a conventional knee-ankle-foot orthosis (KAFO) with the knee locked in extension. Data were collected on three male subjects with significant weakness in at least one lower limb. All subjects could walk independently, without walking aids, in the home and for short distances in the community. All three subjects exhibited increased speed and cadence, increased stride and step lengths, and fewer compensatory movements at the hip, pelvis, and trunk when walking with the SCOKJ®. Two subjects completed an obstacle course more quickly with the SCOKJ®. During 5 minutes of treadmill walking (comfortable speed), two subjects exhibited a lower heart rate response when wearing the SCOKJ®, suggesting lower energy requirements for walking with the SCOKJ®. In summary, the subjects used a more symmetric, more aesthetic walking pattern, maneuvered over and around obstacles more easily, and seemed to walk more efficiently when wearing the SCOKJ® than when wearing a KAFO with the knee locked in extension.

Modern prosthetic knee mechanisms.

The plethora of presently available prosthetic knee components can be divided into two groups based on how they are controlled: recent innovations that incorporate an onboard computer and the more familiar purely mechanical devices. These categories then can be subdivided into generic functional classes based on the degree of stance phase stability and swing phase responsiveness offered by each type of knee mechanism. This article summarizes the key advantages and limitations of available prosthetic knee systems and suggests a simple method to match the biomechanical capabilities of specific prosthetic knee components to the individual functional capabilities and goals of the person with an amputated limb.

design Principles, Biomechanical Data and Clinical Experience with a Polycentric Knee Offering Controlled Stance Phase Knee Flexion: A Preliminary Report

The OTTO BOCK 3R60 prosthetic knee joint allows controlled flexion of the prosthetic knee under weightbearing in early stance phase, more closely simulating this aspect of gait than was previously possible. As the amputee transfers weight onto the prosthesis in early stance phase, this knee gradually flexes up to 15 degrees, thereby cushioning the impact of weight acceptance.In contrast to all previous polycentric knees, stability of this new design is biomechanically increased by stance flexion, rendering a locking feature unnecessary. Clinically, the amputee perceives this prosthesis as stable and comfortable. The biomechanical features of this design concept, initial clinical observations and preliminary conclusions from laboratory gait analysis are summarized.

Transfemoral amputees walking on a rotary hydraulic prosthetic knee mechanism: A preliminary report

Results from multiple instrumented gait analysis trials of seven traumatic transfemoral amputees capable of community ambulation are reviewed. All subjects used a novel rotary hydraulic prosthetic knee offering both stance and swing phase control, in combination with various contemporary prosthetic ankle-foot mechanisms. Unlike previous hydraulic stance and swing units, the Otto Bock 3R80 knee provides stance stability whenever the desired weightbearing load is applied to the prosthesis The mechanical principles and basic functions of the knee joint are described. Results from three phases of gait studies are presented to identify inter-individual variability and the effect of varying sagittal plane knee alignment and the ankle-foot mechanism selected. Subjective amputee preferences for specific foot devices are presented The pattern of hip moments on the amputated side during stance phase are characteristic of the individual amputee. However, the magnitude and timing of the hip moments vary considerably between individual amputees. So long as the prosthetic knee remains biomechanically stable, it appears that alignment alterations or the use of varying foot devices have little impact on the hip extension moment. On the other hand, the hip flexion effort required for the amputee to initiate knee flexion in late stance phase is directly related to the linear position of the prosthetic knee in the sagittal plane: the more posterior the knee, the greater the effort needed to begin swing phase Clinical function of this hydraulic prosthetic knee was considered satisfactory with all tested ankle-foot mechanisms. Transfemoral amputee preference for specific prosthetic feet in this study seemed to be determined by two biomechanical factors: (1) their ability to benefit from the use of a dynamic response foot without compensating with the non-amputated knee, and (2) their ability to generate a hip extension moment on the prosthetic side during the weight acceptance phase of gait

New developments in recreational prostheses and adaptive devices for the amputee.

Regardless of age, conventional prostheses and traditional rehabilitation programs no longer meet the needs and expectations of active amputees. The emphasis on fitness, the availability of stronger and lighter materials, and strong consumer demand have led to plethora of new prosthetic designs by progressive prosthetists and engineers. Prosthetic training techniques now take into account the amputees recreational and sports needs and desires, using advanced athletic training concepts to achieve superior performance in a wide variety of activities. The surgeon, as a key member of the amputee team, should be aware of these profound changes so that they may contribute his or her skill in surgically crafting an optimally functional residual limb. This will allow the amputee to reach for the maximum in cardiopulmonary fitness while achieving social reintegration after amputation. The combination of skills, concepts, and techniques of the amputation surgeon, prosthetist, and therapist/trainer has led to a unique situation, in which for the first time, amputees are able to successfully compete in sports because of their prostheses, rather than in spite of them.

Options for finger prostheses

Conventional, semi-custom finger prostheses centrally fabricated of poly vinyl chloride are often rejected due to suboptimal appearance and a tendency to stain. Rejection is frustrating for the amputee, prosthetist and referring physician. This article summarizes 20 years of experience by the senior author in using custom-fabricated, custom-colored prostheses made from silicone elastomers

Early Management of Elderly Dysvascular Below-Knee Amputees

The majority of transtibial (belowknee) amputations occur in elderly patients with systemic vascular disease. Rehabilitation efforts toward prosthetic ambulation are frequently delayed awaiting postoperative healing of the vascular compromised limb. Rehabilitation becomes more difficult, more costly and less successful the longer it is delayed after surgery, especially among elderly amputees. Early ambulation reduces the risk of complications such as thromboembolism, pneumonia and deconditioning in the older patient as well as enhances remaining life. An early coordinated post-amputation rehabilitation program reduces the time to prosthetic ambulation and the risk of further debility and failure among elderly amputees. The rigid removable dressing was incorporated into the program and found to be a safe method of residual limb shrinkage among elderly dysvascular transtibial amputees.

Prosthetics/orthotics research for the twenty-first century: Summary of 1992 conference proceedings

&NA; This article summarizes the findings from a 1992 conference sponsored by the National Center for Medical Rehabilitation Research (NCMRR), which brought together a multidisciplinary group of scientists, clinicians and consumers from the United States and abroad. Participants reported on current prosthetic and orthotic practice and developed recommendations for research initiatives to advance the state of the art. The conferences text, Prosthetic/Orthotic Research for the Twenty‐First Century: Proceedings of an NCMRR Conference, is available from the NCMRR.

KAFOs for ambulation: An orthotist's perspective

Knee-ankle-foot orthoses (KAFOs) are frequently considered “orthoses of last resort,” based on the limited initial and long-term acceptance rates of these devices, particularly by persons with complete spinal cord injury (SCI). Combining bilateral KAFOs with various hip control methods, such as the reciprocating gait orthosis variants, has not been shown to dramatically improve the ability to ambulate in the community for adults. The weight and bulk of KAFOs and hip-knee-ankle-foot orthoses (HKAFOs), combined with the energy-consuming gait that they provide, are believed to be factors leading to patient rejection of such ambulatory aids. Paradoxically, some persons with physical disability use a KAFO successfully for many decades. The reasons for this discrepancy are not well documented. The recent advent of stance control orthoses (SCOs) providing excellent stance phase stability at the knee without blocking knee flexion during the swing phase may overcome some of the inherent deficiencies of earlier orthoses that immobilized the knee in full extension throughout gait. Preliminary research is encouraging, but many unanswered questions remain. This report highlights KAFO design considerations from the orthotist’s perspective and points out the potential value of a classification system that would help busy practitioners categorize, discuss, and study the plethora of individualized KAFO configurations currently in clinical use. KEY INDEXING TERMS: ambulation, hip-knee-ankle-foot-orthosis, HKAFO, KAFO, knee-ankle-foot-orthosis, lower limb

Researching published information

The foundation for credible scientific research is careful review of published information and previous research as noted in available literature. This paper will discuss methods to ferret out prosthetic and orthotic knowledge from its sometimes arcane locations.