Dual Modular Titanium Alloy Femoral Stem Failure Mechanisms and Suggested Clinical Approaches.

Titanium (Ti) alloys have been proven to be one of the most suitable materials for orthopaedic implants. Dual modular stems have been introduced to primary total hip arthroplasty (THA) to enable better control of the femoral offset, leg length, and hip stability. This systematic review highlights information acquired for dual modular Ti stem complications published in the last 12 years and offers a conclusive discussion of the gathered knowledge.

Secondary hip dysplasia increases risk for early coxarthritis after Legg-Calve-Perthes disease. A study of 255 hips.

The biomechanical parameters of the hip joint articular surface were analysed in 141 adult hips after Legg-Calve Perthes Disease, and 114 contralateral unaffected hips (controls), by using HIPSTRESS mathematical models. Geometrical parameters, assessed from anteroposterior and axial radiograms, were used as input to models for resultant hip force and contact hip stress. Results confirm previous indications that head enlargement after the Legg-Calve-Perthes Disease compensates the values of hip stress.

Modular femoral neck failure after revision of a total hip arthroplasty: a finite element analysis.

The authors report on a case of modular femoral neck fracture which appeared 21 months after revision of acetabular component. The revision surgery was performed 8 years after the primary total hip arthroplasty due to aseptic loosening of the acetabular component. During acetabular revision, the primary implanted short (S, - 3.

Why do some titanium-alloy total hip arthroplasty modular necks fail?

Background: Increased modularity in total hip arthroplasty (THA) through extra junction between the neck and the femoral stem is gaining popularity among orthopaedic community. However, the advantage of the additional junction is shadowed by an increased risk of mechanical failure. The aim of this study was to describe the exact mechanism of fracture of the modular femoral neck in an uncemented stem.

Porous tantalum in spinal surgery: an overview.

Porous tantalum is an open-cell metal structure that approximates the appearance of human cancellous bone. It has a low modulus of elasticity, close to that of subchondral and cancellous bones, leading to better load transfer and minimizing the stress-shielding phenomenon. Its coefficient of friction is one of the highest among biomaterials, allowing for sufficient primary stabilization of implants, possibly even without screw fixation.

Patient-matched instruments versus standard instrumentation in total knee arthroplasty: a prospective randomized study.

Background: Optimal positioning of implants and restoration of neutral mechanical axis are two primary surgical goals in total knee arthroplasty (TKA). Despite modern instruments and improved surgical techniques, malalignment remains an important cause of early failure after TKA. The aim of this prospective randomized study was to compare the value of a new patient-matched instrument system (PMI) (Signature(TM); Biomet, Inc, Warsaw, Indiana) to that of standard TKA surgical instrumentation (STD) in terms of coronal mechanical alignment, time of operation and blood loss.

Porous tantalum shells and augments for acetabular cup revisions.

Purpose: The purpose of this study was to evaluate early functional results of revision hip arthroplasty with pelvic bone loss revised with porous tantalum (PT) acetabular components.

Methods: Twenty-five consecutive patients (25 hips) with loose acetabular components after total hip arthroplasty with a minimum of Paprosky IIa pelvic bone loss treated with PT cups with and without modular augments were retrospectively reviewed. Clinical outcomes were assessed using Harris hip score, and Western Ontario and McMaster Universities scores.

Unfavorable hip stress distribution after Legg-Calvé-Perthes syndrome: a 25-year follow-up of 135 hips.

To study the effect of hip and pelvis geometry on development of the hip after Perthes disease, we determined the resultant hip force and contact hip stress distribution in a population of 135 adult hips of patients who had been treated for Perthes disease in childhood. Contra-lateral hips with no record of disease were taken as the control population. Biomechanical parameters were determined by mathematical models for resultant hip force in one-legged stance and for contact hip stress, which use as an input the geometrical parameters assessed from anteroposterior radiographs.