Adaptive Lower Limb Prostheses for Sports and Recreation

Francois J. Van Der Watt CPO, LPO

Neither Francois J. Van Der Watt nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.

This chapter is adapted from Bragaru M, Van Der Watt F: Adaptive lower limb prostheses for sports and recreation, in Krajbich JI, Pinzur MS, Potter BK, Stevens PM, eds: Atlas of Amputations and Limb Deficiencies: Surgical, Prosthetic, and Rehabilitation Principles, ed 4. American Academy of Orthopaedic Surgeons, 2016, pp 621-629.

ABSTRACT

Participation in sports and recreational activities by individuals with lower limb amputation can improve physical and mental health status. Prostheses specifically designed for sports participation can assist lower limb amputees in achieving optimal performance but are not needed to engage in all sports activities. Prosthesis use in sporting and recreational activities is best determined after consultation with a prosthetist, physiotherapist, and other members of the rehabilitation and sports team.

Introduction

There are no written records of individuals with amputations or other physical disabilities participating in major organized sporting events from before the beginning of the 20th century. The first record of an amputee participating in a major event is that of George Eyser, who competed in the 1904 Summer Olympic Games.¹ Eyser, who lost his lower left leg in a train accident and used a wooden prosthetic leg, successfully competed against ablebodied athletes and won six Olympic medals (including three gold medals).¹ Taking into account the major differences in physical functioning between able-bodied individuals and those with amputations, his performance represents an outstanding achievement.²^,³

The first sporting event dedicated to individuals with physical disabilities took place in 1948 at the Stoke Mandeville Hospital, under the initiative of Sir Ludwig Guttmann, a British neurologist of German descent.⁴ The first Paralympic Games took place in Rome, Italy, in 1960 and these have since become a regular event held once every 4 years.⁵ The number of participants and sports participation has increased in every subsequent Paralympic Games. In the 2016 summer Paralympic Games held in Rio de Janeiro, 4,328 athletes competed from 159 countries.⁶^,⁷ Because of the global COVID-19 pandemic in 2019, the 2020 Paralympic Games in Tokyo, Japan, was postponed until 2021. A total of 4,403 athletes from 162 nations competed in 22 sports.⁸ Participants were organized into six disability groups to “ensure competition is fair and equal, and that winning is determined by skill, fitness, power, endurance, tactical ability and mental focus, the same factors that account for success in sports for able-bodied athletes.”⁹

Approximately 30% of individuals with a lower limb amputation participate in sports, with cycling, fitness, swimming, golf, and walking being some of the favored activities.¹⁰ Generally, an individual who was actively participating in sports before their amputation is more likely to participate in sports after an amputation. Other factors that may have a positive influence on the participation in sports are a younger age, a more distal level of amputation, and a nonvascular amputation.

To better understand participation in recreational and competitive sports by individuals with limb absence or loss, the effects of factors such as physical health, psychological determinants, and technical aids (such as prostheses) must be considered.

Physical Health

Although amputees generally have better physical health than individuals with other physical disabilities such as cerebral palsy or spinal cord injury,¹¹^,¹² they still have substantial limitations in physical functioning compared with able-bodied individuals.¹³ The rehabilitation period can provide the ideal place, time, and professional care to recover from the amputation and explore the possibility for sports participation for those demonstrating the will and capability to become recreational or competitive athletes. The physical therapist and prosthetist may
be a source for advice and guidance on the training required and the sport that best suits the individual’s skills and capabilities.

Psychological Determinants

The trauma associated with limb amputation is not confined to physical trauma. Psychological trauma is also experienced by many lower limb amputees, who are prone to depression in the first 2 years after an amputation.¹⁴^,¹⁵ Regular participation in a sport is one method for dealing with depression, and it has proved both physically and psychosocially beneficial for those who have undergone a lower limb amputation.¹⁰^,¹³^,¹⁶^,¹⁷^,¹⁸^,¹⁹^,²⁰^,²¹^,²² When questioned about the advantages of sports participation, one amputee mentioned the improvement in well-being, the chance to feel useful, and the opportunity to get out of the house and on a path to regaining a social life.²³

Factors that may promote or deter an individual’s participation in sports include past experiences, personal desires and aims, stigma management, coping skills, self-efficacy, disability acceptance, general health, physical capacity, functional outcome, and regional opportunities for participation.²⁴ Support from family and peers may encourage sports participation.

Technical Aids and Prostheses

The idea of amputees participating in sports is not new, but the understanding of sport prostheses and the role they play in performance is still a developing science. Although some sports can be performed with conventional prostheses not specifically adapted for a particular sport, other sports require a specially designed prostheses. In recent years, there has been an increase in the rate of development of specialized prostheses and prosthetic components used for sports.²⁵ In 1996, the first Flex-Foot Cheetah (Össur) became available; advancements in sports prosthetic technology have continued since that time. Although the study and understanding of the biomechanics and functioning of prosthetic devices for sports have continued to improve over the past decade, much of the science concerning sport-specific prostheses and their performance is still unknown.²⁶ Sport-specific components are only one part of the athlete’s total package that enables them to participate and achieve advanced performance in sports activities. The limb-socket interface, the method of suspension, and the alignment of prosthetic components are also important factors that continue to develop. A pilot study by Hefner et al suggested that in the development and use of crossover feet, the participants exhibited increased mobility (ie, Timed Up and Go [TUG]²⁷ at comfortable and fast speeds), endurance (ie, distance walked in 6 minutes), and walking performance (ie, walking speed, cadence, sound step length) compared with their energy-storing foot, Similarly. participants reported decreased exertion (ie, lower Borg rating of perceived exertion [RPE]²⁸) in crossover feet.²⁹

Prosthetic Sockets

A prosthetic socket should be custom made to fit the characteristics of the athlete’s residual limb. The socket should provide the required support and comfort to allow the athlete to voluntarily move and control the prosthesis during the sports activity. The socket trim lines should be optimized to allow joint mobility without compromising limb support. Muscle atrophy in the residual limbs of amputee athletes is common and requires socket adjustments to accommodate changes in limb shape and volume. It is fairly common to see an increase of up to 17% in the volume of the residual limb during competition or training.³⁰ Therefore, an adjustable socket may be useful for an athlete with a transfemoral or transtibial amputation. One option for resolving the issue of varying limb volume is an adjustable socket achieved by cutting out targeted socket walls and fitting them with adjustable flaps (Figure 1). This approach can use an adjustable cable system to alter the position of the socket walls to increase or decrease the volume of the socket as changes occur in the volume of the residual limb during an activity.

FIGURE 1 Photograph of the RevoFit® (Click Medical), with an adjustable socket for volume fluctuations. (Courtesy of Click Medical LLC.)

At the transfemoral amputation level, subischial or brimless socket designs, which allow increased range of motion and muscle movement, can be considered. These types of sockets are designed for use with a liner to provide skin protection and relief from shear forces applied to the skin of the residual limb by the increased load experienced during sports activities.

Suspension System

The primary function of the socket suspension system is to secure the prosthesis to the athlete’s residual limb. The suspension method can also play a critical role in reducing mental fatigue by decreasing the fear of losing the prosthesis during sports participation. The suspension method should be functional and should not limit the joint range of motion. A variety of options is available, and individual needs will determine the most appropriate suspension method. These can include mechanical connections, suction suspension, vacuum suspension, or a combination incorporating two or more suspension methods. The use of an interface liner is most common across all suspension techniques.

Prosthetic Component Choice and Alignment

The prosthetist can choose from a large variety of components that will enable
a patient to achieve their best performance in the desired sport. During the dynamic alignment of these components, the manufacturer’s recommendations can be helpful because individual component properties and functions differ among manufacturers.

When the need for shock absorption is anticipated and the associated components are incorporated into the prosthetic design, the overall height of the prosthesis must be adjusted accordingly. During running, the compression experienced by shock-absorbing components can affect the timing of ground contact and stride length, and both elements can affect running or agility speed. The selection of the appropriate stiffness for a prosthetic foot can be challenging because the level of amputation, limb length, strength, body weight, and the force production capabilities will vary based on the characteristics of the individual athlete. Secondary, comorbid impairments are also common in traumatic or congenital amputees and should be considered when optimizing the prosthetic setup and alignment for the athlete.

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