Orthoses

Orthoses

Orthoses are devices used to provide functional support, control deformities, and reduce pain in joint, muscle, or nervous system disorders. Static types stabilize the joint, whereas dynamic typesfacilitate movement. In their design, simplicity, lightness, durability, and aesthetics are important. When prescribing orthoses, considerations include the three-point pressure system, static or dynamic stabilization, tissue tolerance, and whether the deformity is rigid or flexible.

Foot orthoses include shoes as the basic form, providing accommodation for deformities or support for walking. Insole orthoses, such as heel cups, UCBL, or Arizona orthoses, are particularly useful in flexible pes planus. Medial and lateral wedges influence varus-valgus loading at the knee, and rocker-bottom shoes facilitate weight transfer during gait.

Ankle-foot orthoses (AFOs) are used in cases of ankle muscle weakness or overactivity. The ankle angle indirectly affects knee stability. Non-articulated AFOs are rigid and aesthetically acceptable, creating a knee flexion moment during the early stance phase. Articulated AFOs allow a more natural gait pattern while providing dorsiflexion assistance and motion-limiting options. Different joint-locking mechanisms are applied in the presence of knee flexion contracture or quadriceps weakness. Supramalleolar orthoses (SMO) are suitable for mild deformities.

Knee-ankle-foot orthoses (KAFOs) are indicated in quadriceps paralysis, knee instability, or genu varum/valgum. They can be constructed from metal or plastic. The Scott-Craig orthosis allows paraplegic patients to stand and walk. Knee joints in KAFOs may be single-axis, polycentric, or posterior offset, and locking mechanisms such as drop ring, pawl lock, or adjustable locks provide additional stability.

Knee orthoses are employed for patellofemoral disorders, genu recurvatum, or sports injuries. Devices such as infrapatellar straps or the Swedish knee cage provide sagittal plane control, and polycentric joints mimic natural knee motion.

Hip-knee-ankle-foot orthoses (HKAFOs) consist of a metal frame with mechanical hip and knee joints. These orthoses are used in hip instability, especially after total hip arthroplasty, to maintain approximately 15° abduction and limited flexion. Single or double-axis hip joints provide motion control, but the device increases energy expenditure and may be challenging to use.

Trunk-hip-knee-ankle-foot orthoses (THKAFOs) are used in paraplegic patients to control the trunk and align the spine. Walking with a reciprocating gait orthosis is achieved through weight transfer.

Lower Extremity Prostheses

Lower extremity prostheses aim to provide comfort, function, lightness, and aesthetic integration. Modern developments include energy-storing feet, computer-assisted fabrication, and microprocessor-controlled knees.

The main components of a prosthesis include the socket, which interfaces with the residual limb, the suspension system, the knee joint, the pylon, and the terminal device. Sockets are generally patellar tendon-bearing, and suspensions may be either classic suction or silicone-based. Microprocessor-controlled knees adjust to walking speed and provide control during ramp or stair descent, although they do not actively extend the knee.

The foot component provides stability, shock absorption, compensation for muscle function, and aesthetics. The SACH foot is a low-cost option, whereas energy-storing dynamic response feet are suitable for running and sports. Functional levels are classified according to mobility, ranging from Level 1, which involves transfers and walking on flat surfaces, to Level 4, which includes high-energy activities.

Rehabilitation training includes donning and doffing the prosthesis, daily skin inspection, and performing safe transfers. Complications may include choke syndrome, dermatologic reactions, residual limb pain, and gait difficulties. Energy expenditure increases by 10–20% in transtibial amputees and 60–70% in transfemoral amputees.

Upper Extremity Prostheses

The selection of upper extremity prostheses depends on the level of amputation, expected function, aesthetic requirements, and cost.

Body-powered prostheses are durable, low-cost, and provide good sensory feedback, but they are less aesthetically appealing. Myoelectric prostheses detect muscle activity through electrodes, offering superior aesthetics, though they tend to be heavier and more expensive.

Terminal devices may be passive, focusing on appearance, or active, offering functional grasp such as hooks or hand types. Grasping mechanisms include pinch, tripod, key, spherical, and power grasps. Myoelectric hands provide stronger grip but are sensitive to environmental conditions.

Joint units include quick-change wrists, locked or flexion wrists, and rigid or flexible elbow hinges. Shoulder-level amputations have limited function, and some patients may prefer prostheses solely for aesthetic purposes.

Complications of upper limb prostheses include contact dermatitis, excessive sweating, pain due to poorly fitting sockets, and neuroma formation.

References

1. Nouri A, Ensafi V, Sigari E, Maalek SS. Materials and manufacturing for ankle–foot orthoses: A review. Advanced Engineering Materials. 2023;25(7):2300238. doi:10.1002/adem.202300238

2. Gunaratne PN, Tillekeratne K, Kottegoda NJ, Rathnayake L, Jayasekara R. Developments in hardware systems of active ankle orthoses. Sensors (Basel). 2024;24(24):8153. doi:10.3390/s24248153