Orthopedic implants

GCET kashmir

1. Orthopedic implants ….created by haleeful jud Lecturer Biomedical engineering

2. Hard tissue implant Hard issue is also known as calcified tissue A tissue which is mineralized and has a firm intercellular matrix. Hard tissues of humans are bone and teeth(orthopedic and dental) Any impant intended to use in repair or replacement of hard tissues of humans can be refered to as hard tissue implants. for e.g knee replacement, fracture fixation etc. 2 main categories; Orthopedic and dental implants

3. Orthopedic implants An orthopedic implant is a medical device manufactured to replace a missing joint or bone or to support a damaged bone People sufferering from accidents and joint diseases such as osteoarthritis, Rheutamoid arthritis etc may need surgery requiring implants such as total hip and knee replacements. Orthopedic implants also include temporay fixation devices such as plates, screws, pins, wires, and nails. Orthopedic implants can be classified as permenant and temporary implants

4. Permenant implants Permenant orthopedic implants are expected to serve in human body throughout the life span of patients. Different types of total joints including knee, hip, ankle, shoulder, elbow etc are used as replacemants clinically Replacement surgeries are preferred for patients to undertake these implants

5. Hip replacement implants Hip replacement, also called hip arthroplasty, is a surgical procedure to address hip pain . The surgery replaces parts of the hip joint with artificial implants . The hip joint consists of a ball (at the top of the femur, also known as the thigh bone) and a socket (in the pelvis, also known as the hip bone ). Hip replacement surgery includes replacement of one or both parts. The goal of the procedure is to allow you to resume daily activities and exercise with less pain.

6. …. Parts of a Hip Replacement Implant (Hip Prosthesis) The hip replacement implant has two parts: A  ceramic ball  attached to a metal stem, which is inserted into the thigh bone (femur) for stability A  metal cup  (typically made of titanium) with an inner plastic layer, which is attached to the socket part of the hip joint (acetabulum) to allow the prosthetic joint to rotate smoothly In the past, the ball was made of metal as well, but the current standard is ceramic.

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8. Knee replacement implants

9. … Knee replacement surgery — also known as knee arthroplasty can help relieve pain and restore function in severely diseased knee joints . The procedure involves cutting away damaged bone and cartilage from your thighbone, shinbone and kneecap and replacing it with an artificial joint (prosthesis) made of metal alloys, high-grade plastics and polymers.

10. Implant Components Implants are made of metal alloys, ceramic material, or strong plastic parts. Up to three bone surfaces may be replaced in a total knee replacement: The lower end of the femur.   The metal femoral component curves around the end of the femur (thighbone). It is grooved so the kneecap can move up and down smoothly against the bone as the knee bends and straightens.

11. … The top surface of the tibia.   The tibial component is typically a flat metal platform with a cushion of strong, durable plastic, called polyethylene. Some designs do not have the metal portion and attach the polyethylene directly to the bone. For additional stability, the metal portion of the component may have a stem that inserts into the center of the tibia bone. The back surface of the patella.  The patellar component is a dome-shaped piece of polyethylene that duplicates the shape of the patella (kneecap). In some cases, the patella does not need to be resurfaced.

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13. Shoulder replacement implants

14. …. Shoulder replacement removes damaged areas of bone and replaces them with parts made of metal and plastic (implants) In an anatomic total shoulder replacement, the ball and the socket are replaced with implants that resemble the natural shape of the bones . In traditional shoulder replacement surgery, the damaged humeral head (the ball of the joint) is replaced with a metal ball, and the glenoid cavity (the joint socket) is replaced with a smooth plastic cup. (The humeral head is at the top of the humerus – the upper arm bone, and the glenoid is located in the scapula – the shoulder blade.)

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16. temporary orthopedic implants Another type of orthopedic implants is temporary ones that are needed to fix broken or fractured bones during the healing process. Temporary orthopedic implants including plates, screws, pins, wires, and intramedullary nails. They are supposed to serve for a relatively short time just long enough to let bones heal. Screws are commonly used together with other devices especially plates to fix the associated devices to bones and also as stand-alone components to fix fractured fragments

17. Pins Pins can be used as adjunctive fixation devices along with other devices in complex fracture of bones in order to withstand a large loading force or used alone to fix bones under a relatively weak force. Wires As simple but versatile implants, wires are commonly employed to hold bone fragments together and also in reattachment of the greater trochanter in hip replacements or long oblique/spiral fracture of long bones..

18. Nail An intramedullary nail is a surgical rod forced into a long bone of the extremities through the medullary canal to act as an immobilization device to hold the two ends of the fractured long bone in position. To anchor the nails in place inside a piece of bone, other implants such as pins or screws are generally inserted into predrilled holes in the rods. Plates with different types and sizes containing holes for screws and pins are used to fix plates to bones, so that bone fragments can be compressed together during the healing process of load-bearing bones.

19. Bone plates And screws

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21. Important properties of ortho implants Mechanical properties The mechanical requirements for orthopedic implant materials are related to the intended working conditions and specific applications. The Young’s modulus, yield strength, ultimate tensile strength, fracture toughness, and elongation at break are five important mechanical properties Wear resistance is an inevitable problem for joint replacements where there is relative motion between the two surfaces under loading resulting in successive release of wear debris into the areas surrounding an implant high wear resistance is desired for joint replacements and fixation devices to avoid loosening and premature failure of implants

22. Corrosion resistance Corrosion is of great concern particularly for metallic materials in vivo. The human body presents an aggressive environment because human body fluids consist of various cations such as sodium, potassium, calcium, and magnesium (Mg) ions; anions like chloride (Cl) ions, phosphate, and bicarbonate ions; amino acids; proteins; and dissolved oxygen (O2). Electrochemical corrosion tends to occur on the metallic implant surfaces in the corrosive physical environment over time.

23. Biocompatiblity As the most important aspect of implant materials, biocompatibility is defined by the US Food and Drug Administration as the effect that the materials induce no measurable harm to the host. It is critical that implant materials are nontoxic and do not produce harmful effects to the host because of the intimate contact with human tissues. Metal ions released from metallic implants to adjacent tissues may activate the immune system and induce hypersensitivity response, which may eventually contribute to implant failure

24. osseointegration Osseointegration is defined as the direct structural and functional connection between the living bone and surface of a load-bearing implant . The ability of an implant to bond with the surrounding host bone is another fundamental requirement for permanent orthopedic implants. Insufficient osseointegration can lead to the formation of fibrous tissues and ensuing loosening of the prostheses. Factors such as the design, chemical composition, surface roughness, and surface chemistry of the implants and loading conditions are important to good osseointegration of implants

25. Materials used in orthopedic implants Metals: Stainless steel Cobalt based alloys Titanium based alloys Bio-degradable metals: polyglycolide (PGA), polylactide (PLA),

26. … Ceramics Alumina Zirconia Hydroxyapetite Polymers PMMA Ultrahigh-Molecular-Weight Polyethylene Polyetheretherketone

27. … Thankyou