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Fulltext Comparison of various functionally graded femoral prostheses by finite element analysis

Oshkour AA, Talebi H, Shirazi SF, Bayat M, Yau YH, Tarlochan F, et al.

ScientificWorldJournal, 2014;2014:807621.
PMID: 25302331 DOI: 10.1155/2014/807621

This study is focused on finite element analysis of a model comprising femur into which a femoral component of a total hip replacement was implanted. The considered prosthesis is fabricated from a functionally graded material (FGM) comprising a layer of a titanium alloy bonded to a layer of hydroxyapatite. The elastic modulus of the FGM was adjusted in the radial, longitudinal, and longitudinal-radial directions by altering the volume fraction gradient exponent. Four cases were studied, involving two different methods of anchoring the prosthesis to the spongy bone and two cases of applied loading. The results revealed that the FG prostheses provoked more SED to the bone. The FG prostheses carried less stress, while more stress was induced to the bone and cement. Meanwhile, less shear interface stress was stimulated to the prosthesis-bone interface in the noncemented FG prostheses. The cement-bone interface carried more stress compared to the prosthesis-cement interface. Stair climbing induced more harmful effects to the implanted femur components compared to the normal walking by causing more stress. Therefore, stress shielding, developed stresses, and interface stresses in the THR components could be adjusted through the controlling stiffness of the FG prosthesis by managing volume fraction gradient exponent.

Matched MeSH terms: Femur/surgery
Comparable clinical and radiological outcomes between anatomical and high femoral tunnels in posterior cruciate ligament reconstruction

Yoon KH, Kim JS, Park JY, Park SY, Kiat RYD, Kim SG

Knee Surg Sports Traumatol Arthrosc, 2021 Jun;29(6):1936-1943.
PMID: 32914218 DOI: 10.1007/s00167-020-06266-0

PURPOSE: To compare clinical and radiological outcomes and failure rates between anatomical and high femoral tunnels in remnant-preserving single-bundle posterior cruciate ligament (PCL) reconstruction.
METHODS: 63 patients who underwent remnant-preserving single-bundle PCL reconstruction between 2011 and 2018 with a minimum 2-year follow-up were retrospectively reviewed. Patients were divided into two groups according to the femoral tunnel position: group A (33 patients with anatomical femoral tunnel) and group H (30 patients with high femoral tunnels). The femoral tunnel was positioned at the center (group A) or upper margin (group H) of the remnant anterolateral bundle. The position of the femoral tunnel was evaluated using the grid method on three-dimensional computed tomography. Clinical and radiological outcomes and failure rates were compared between the groups at the 2-year follow-up.
RESULTS: The position of the femoral tunnel was significantly high in group H than in group A (87.4% ± 4.2% versus 76.1% ± 3.7%, p

Matched MeSH terms: Femur/surgery*
Fulltext Case report: migration of a broken screw to the knee joint after hardware failure following closing wedge distal femoral osteotomy

Lee YS, Lee SH, Lee ES, Fong TS

BMC Musculoskelet Disord, 2019 Mar 20;20(1):118.
PMID: 30894158 DOI: 10.1186/s12891-019-2505-4

BACKGROUND: We report a case of hardware failure after distal femoral osteotomy (DFO) with a broken screw pulled out from the locking hole and positioned within the knee joint.
CASE PRESENTATION: A 57-year-old man presented to our orthopedic outpatient department with 3-months history of an unusual painful swelling at the operated area following DFO. The leakage of joint fluid from the penetrated suprapatellar pouch was assumed to be the reason for this complication.
CONCLUSIONS: The overall aim of this case report is to provide a lesson to budding surgeons who might experience a similar situation that cannot be easily explained, like the unexpected complication in the present case.

Matched MeSH terms: Femur/surgery
Biomechanical analysis of three different types of fixators for anterior cruciate ligament reconstruction via finite element method: a patient-specific study

Zainal Abidin NA, Abdul Wahab AH, Abdul Rahim RA, Abdul Kadir MR, Ramlee MH

Med Biol Eng Comput, 2021 Sep;59(9):1945-1960.
PMID: 34392448 DOI: 10.1007/s11517-021-02419-6

Complication rates of anterior cruciate ligament reconstruction (ACL-R) were reported to be around 15% although it is a common arthroscopic procedure with good outcomes. Breakage and migration of fixators are still possible even months after surgery. A fixator with optimum stability can minimise those two complications. Factors that affect the stability of a fixator are its configuration, material, and design. Thus, this paper aims to analyse the biomechanical effects of different types of fixators (cross-pin, interference screw, and cortical button) towards the stability of the knee joint after ACL-R. In this study, finite element modelling and analyses of a knee joint attached with double semitendinosus graft and fixators were carried out. Mimics and 3-Matic softwares were used in the development of the knee joint models. Meanwhile, the graft and fixators were designed by using SolidWorks software. Once the meshes of all models were finished in 3-Matic, simulation of the configurations was done using MSC Marc Mentat software. A 100-N anterior tibial load was applied onto the tibia to simulate the anterior drawer test. Based on the findings, cross-pin was found to have optimum stability in terms of stress and strain at the femoral fixation site for better treatment of ACL-R.

Matched MeSH terms: Femur/surgery
Bilateral atypical femoral diaphyseal fractures in a patient treated with alendronate sodium

Lee JK

Int J Rheum Dis, 2009 Jul;12(2):149-54.
PMID: 20374333 DOI: 10.1111/j.1756-185X.2009.01396.x

Antiresorptive agents have been used as primary or first-line therapy in managing patients with osteoporosis. Bisphosphonates in particular are used widely to reduce bone resorption, increase bone mineral density, improve bone quality and therefore reduce fracture risk. However, prolonged use of bisphosphonates may cause over-suppression of bone resorption, leading on to accumulation of micro-damage in bone. This in turn might lead on to atypical femoral fractures. A patient treated with alendronate sodium for 8 years, and presenting with bilateral atypical femoral diaphyseal fractures is reported. X-rays of both femurs showed typical horizontal fracture line involving the thick lateral cortex with short oblique fracture pattern over the medial cortex. This fracture pattern was further confirmed with intra-operative examination of the fracture ends. Histopathological examination of the endocortical fragment removed from the proximal fracture end showed absence of osteoclasts and osteoblasts. Bone mineral density with dual energy X-ray absorptiometry (DXA) scan showed osteopenia over the femoral neck. Blood investigations did not show significant abnormalities. Bone turnover marker levels were not reliable, as presence of fracture might have altered the marker levels. Both femoral fractures united well. The patient reported here had complete pictures on X-ray examination, intra-operative findings, histopathological examination, DXA, as well as blood test results. Complete data should be collected from patients treated with alendronate sodium presenting with atypical femoral fractures to show any link between the use of alendronate sodium with atypical fracture of femur.

Matched MeSH terms: Femur/surgery
Advancement in total hip implant: a comprehensive review of mechanics and performance parameters across diverse novelties

Soliman MM, Islam MT, Chowdhury MEH, Alqahtani A, Musharavati F, Alam T, et al.

J Mater Chem B, 2023 Nov 15;11(44):10507-10537.
PMID: 37873807 DOI: 10.1039/d3tb01469j

The UK's National Joint Registry (NJR) and the American Joint Replacement Registry (AJRR) of 2022 revealed that total hip replacement (THR) is the most common orthopaedic joint procedure. The NJR also noted that 10-20% of hip implants require revision within 1 to 10 years. Most of these revisions are a result of aseptic loosening, dislocation, implant wear, implant fracture, and joint incompatibility, which are all caused by implant geometry disparity. The primary purpose of this review article is to analyze and evaluate the mechanics and performance factors of advancement in hip implants with novel geometries. The existing hip implants can be categorized based on two parts: the hip stem and the joint of the implant. Insufficient stress distribution from implants to the femur can cause stress shielding, bone loss, excessive micromotion, and ultimately, implant aseptic loosening due to inflammation. Researchers are designing hip implants with a porous lattice and functionally graded material (FGM) stems, femur resurfacing, short-stem, and collared stems, all aimed at achieving uniform stress distribution and promoting adequate bone remodeling. Designing hip implants with a porous lattice FGM structure requires maintaining stiffness, strength, isotropy, and bone development potential. Mechanical stability is still an issue with hip implants, femur resurfacing, collared stems, and short stems. Hip implants are being developed with a variety of joint geometries to decrease wear, improve an angular range of motion, and strengthen mechanical stability at the joint interface. Dual mobility and reverse femoral head-liner hip implants reduce the hip joint's dislocation limits. In addition, researchers reveal that femoral headliner joints with unidirectional motion have a lower wear rate than traditional ball-and-socket joints. Based on research findings and gaps, a hypothesis is formulated by the authors proposing a hip implant with a collared stem and porous lattice FGM structure to address stress shielding and micromotion issues. A hypothesis is also formulated by the authors suggesting that the utilization of a spiral or gear-shaped thread with a matched contact point at the tapered joint of a hip implant could be a viable option for reducing wear and enhancing stability. The literature analysis underscores substantial research opportunities in developing a hip implant joint that addresses both dislocation and increased wear rates. Finally, this review explores potential solutions to existing obstacles in developing a better hip implant system.

Matched MeSH terms: Femur/surgery