Biomechanical and Tribological Aspects of Orthopaedic Implants

Abstract

Orthopaedic and dental implant treatments have allowed to enhance the quality of life of millions of patients. Total hip/knee arthroplasty is a surgical replacement of the hip/knee joint with an artificial prosthesis. The aim of joint replacement surgery is to relieve pain improve function, often for sufferers of osteoarthritis, which affects around a third of people aged over fifty. Nowadays, total hip and knee replacement (THR) surgeries are considered routine procedures with generally excellent outcomes. Given the increasing life expectancy of the world population, however, many patients will require revision or removal of the artificial joint during their lifetime. The most common cause of failure of hip and knee replacements is mechanical instability secondary to wear of the articulating components. Thus, tribological and biomechanical aspects of joint arthroplasty are of specific interest in addressing the needs of younger, more active patients. The most significant improvements in the longevity of artificial joints have been achieved through the introduction of more wear resistant bearing surfaces. These innovations, however, brought about new tribocorrosion phenomena, such as fretting corrosion at the modular junctions of hip implants. Stiffness mismatch between the prosthesis components, non-physiological stress transfer and uneven implant-bone stress distribution are all involved in premature failure of hip arthroplasty. The development of more durable hip and knee prostheses requires a comprehensive understanding of biomechanics and tribocorrosion of implant materials. Some of these insights can also be applied to the design and development of dental implants.

Soft and Hard Tissue Integration around Percutaneous Bone-Anchored Titanium Prostheses: Toward Achieving Holistic Biointegration

“…92 A book chapter by Irene Gotman reviews the topic of wear debris, osteolysis, and aseptic loosening of orthopedic implants in detail. 93 Last, in commercial Ti implants with surface coatings, Zimmer Biomet manufactured femoral stems with porous plasma spray (PPS) Ti-coated Taperloc hip femoral stem demonstrated long-term osseointegration and survival with low 7.8% revisions required due to aseptic loosening, osteolysis, infections, peri-prosthetic fractures, etc. after a 25-year follow-up.…”

“…Another important consideration in the context of osseointegration is the stiffness (Young’s modulus) mismatch of the cortical and cancellous bone (4–30 GPa) with Ti and Ti6Al4V alloy (∼110 GPa) that causes stress shielding, bone resorption, and implant loosening . A book chapter by Irene Gotman reviews the topic of wear debris, osteolysis, and aseptic loosening of orthopedic implants in detail . Last, in commercial Ti implants with surface coatings, Zimmer Biomet manufactured femoral stems with porous plasma spray (PPS) Ti-coated Taperloc hip femoral stem demonstrated long-term osseointegration and survival with low 7.8% revisions required due to aseptic loosening, osteolysis, infections, peri-prosthetic fractures, etc.…”

Application of magnetic field assisted finishing process for nanofinishing of freeform femoral knee joint and performance analysis of finished surface

“…Studies show that UHMWPE wear is the main reason behind aseptic loosening in orthopedic implants. 9 Friction between the contacting articulating surfaces can be reduced by minimizing adhesion and also by minimizing normal and shear stresses, which can be achieved through ultra-high polishing. 10 According to fundamental tribological investigation, wear of UHMWPE increases with an increase in counterface or femoral component surface roughness.…”