Introduction
Orthopedic prosthetics have come a long way in recent years. Advanced materials, manufacturing techniques and computer technology have enabled engineers and medical practitioners to design prosthetics that can closely mimic human movement and biomechanics.

Materials Used in Modern Prosthetics
Orthopedic Prosthetics were traditionally made from materials like wood, leather and metal. While durable, these materials could not replicate the range of motion of natural limbs. Advanced materials now allow for prosthetics that are not only functional but also lightweight and comfortable.
Carbon fiber: Carbon fiber has revolutionized prosthetic design due to its high strength to weight ratio. Carbon fiber prosthetics are considerably lighter than their metal counterparts, allowing for an easier gait. Modern microprocessor-controlled knees also use carbon fiber.
Plastics: Advances in plastics like polypropylene, polyethylene and polyurethane have allowed for highly dexterous and cosmetically realistic prosthetic hands and fingers. Thermoplastic materials can be easily molded to fit patients' residual limbs.

Myoelectric Control of Upper Limb Prosthetics
One of the most groundbreaking advancements has been the development of myoelectric control systems for upper limb prosthetics. Myoelectric refers to detecting small electrical signals generated by muscles. Sensors placed on the skin over residual muscles can read these signals when the muscles are contracted. Modern prosthetic hands and arms can now open and close their grips, rotate their wrists and perform multiple simultaneous movements based on muscle control. This sophisticated level of control allows prosthetic users to perform activities of daily living with ease. Complex sensor and processing systems interpret subtle muscle signals to control multi-fingered hand prosthetics with a high degree of dexterity.

Computerized Lower Limb Prosthetics
Microprocessor knees have revolutionized mobility for lower limb amputees. Early prosthetic knees locked firmly during the swing phase of gait and lacked adjustable flexion/resistance during stance. Microprocessor technology introduced hydraulic, pneumatic or electric controls that could continuously sense forces and fine-tune resistance in real-time. Some advanced knees have multiple hydraulic pistons or electronic sensors to replicate the biomechanics of descending and ascending stairs, ramps and unstable terrain. Such terrain adaption was not possible with conventional mechanical knees. Computerized ankle-foot mechanisms have also been developed that can store and release energy during walking for a near-natural gait.

Cosmetic Advances in Prosthetic Design
While function is paramount, the cosmetic appearance of prosthetics is also becoming increasingly life-like. Recent innovations in materials and 3D printing/scanning allow for custom cosmetic covers that match a patient's unaffected limb in color, texture, skin tone and nail details. Some covers are made of materials like silicone that move like natural skin and sweat pores. This level of cosmetic realism reduces feelings of self-consciousness and improves psychosocial well-being for amputees.

Advances in Prosthetic Sockets
The interface between the residual limb and the prosthesis, known as the socket, is critical for comfort, control and long-term use. Custom-molded sockets were traditionally made from wood, plaster or foam. Now, 3D scanning and computer-aided design help engineers generate precise digital models of the residual limb from which to manufacture thermoplastic or carbon fiber sockets. Some advanced systems use vacuum-assisted suction and hydrostatic pressure to hold the socket gently against the limb without the need for rigid bony locking or tightly-strapped suspension systems. This reduces pain and skin problems. Suspension systems themselves have also evolved with the use of lightweight liners, gel cushions and microprocessor-controlled actuators.

Osseointegration for Direct Skeletal Attachment
A highly promising advancement is the technique of osseointegration which involves surgically implanting a titanium post or replica joint surface directly into the residual bone. After osseointegration or bony fusion occurs, percutaneous abutments protrude through the skin allowing a prosthesis to be locked onto the body without a conventional socket. This eliminates skin issues and harness discomfort. While still experimental, osseointegration ultimately aims to restore near-natural sensorimotor control and higher activity levels compared to socket suspensions. With further research, it may become the standard for multiple types of limb loss.

Continued Advancement through Research
Prosthetics continue to evolve at a rapid pace driven by collaborative research between engineers, manufacturers, medical practitioners and amputee communities. Areas of ongoing innovation include neural control interfaces, powered prosthetic joints, regenerative solutions and targeted rehabilitation protocols. With expanded access to advanced care worldwide, prosthetics aim to restore near-normal function and quality of life for individuals with limb loss or absence.

Significant technical and materials breakthroughs over the past few decades have radically transformed both upper and lower orthopedic prosthetics. Computerized control, customized artificial sensory feedback, biomimetic designs and improved interface systems now deliver prosthetic function, comfort and appearance that replicates healthy limbs. Further research combining engineering, biomedicine, rehabilitation, 3D printing and machine learning will continue to augment human capabilities through ever more sophisticated orthopedic devices.

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