André Ferreira

Equivalent wear performance of dual mobility bearing compared with standard bearing in total hip arthroplasty: in vitro study

PurposeOsteolysis in total hip arthroplasty (THA) depends on polyethylene wear and dictates the survival of the prosthesis. Dual mobility in THAs, which is claimed to reduce dislocation risk, has very good long-term clinical results. However, little is known about how the liner wears in this design, compared to the standard single mobility model.MethodsA comparative study looking at wear of a conventional ultra-high-molecular-weight polyethylene liner, using gravimetric measurement, between dual mobility implants and standard implants, was performed on a simulator in accordance with a normed protocol based on the same dimensions, environmental conditions and stresses. A linear regression test was employed.ResultsUnder the same conditions (loading, cycles, sterilization, material and surface roughness), the gravimetric wear (for conventional polyethylene) is comparable between a standard and a dual mobility cup. This correlates to ten year follow-up results of dual mobility cup.Discussion - ConclusionThis in vitro equivalent wear serves to confirm the very good long-term clinical results observed with dual mobility bearing, whose use should not be restricted by concerns about increased polyethylene wear.

Dual-mobility cup: a new French revolution

When we (Figs. 1 and 2) began performing total hip arthroplasty (THA) 40 years ago, in 1976, we used the current gold standard for hips, the LFA (low-friction arthroplasty), developed by Sir John Charnley in 1962. However, the same year the dual-mobility cup (DMC) was born and patented. More than 40 years later, results with standard cups were satisfactory [1] but had two long-term problems, polyethylene (PE) wear and dislocations with an increased

Trans trochanteric approach with coronal osteotomy of the great trochanter - A new technique for extra-capsular trochanteric fracture patients treated by total hip arthroplasty (THA) in elderly

Several surgical approaches could be used in hip arthroplasty or trauma surgery: anterior, anterolateral, lateral, posterior (with or without trochanterotomy), using or not an orthopedic reduction table. Subtrochanteric and extra-capsular trochanteric fractures (ECTF) are usually treated by internal fixation with mandatory restrictions on weight bearing. Specific complications have been widely described. Mechanical failures are particularly high in unstable fractures. Hip fractures are a major public health issue with a mortality rate of 12%–23% at 1 year. An alternative option is to treat ECTF by total hip arthroplasty (THA) to prevent decubitus complications, to help rapid recovery, and to permit immediate weight bearing as well as quick rehabilitation. However, specific risks of THA have to be considered such as dislocation or cardiovascular failure. The classical approach (anterior or posterior) requires the opening of the joint and capsule, weakening hip stability and the repair of the great trochanter is sometimes hazardous. For 15 years, we have been treating unstable ECTF by THA with cementless stem, dual mobility cup (DMC), greater trochanter (GT) reattachment, and a new surgical approach preserving capsule, going through the fracture and avoiding joint dislocation. Bombaci first described a similar approach in 2008; our trans fractural digastric approach (medial gluteus and lateral vastus) is different. A coronal GT osteotomy is performed when there is no coronal fracture line. It allows easy access to the femoral neck and acetabulum. The THA is implanted without femoral internal rotation to avoid extra bone fragment displacement. With pre-operative planning, cup implantation is easy and stem positioning is adjusted referring to the top of the GT after trial reduction and preoperative planning. The longitudinal osteotomy and trochanteric fracture are repaired with wires and the digastric incision is closed. This variant of Bombaci approach could be use routinely for hemiarthroplasty or THA in the cases of unstable ECTF. It reduces complications usually linked to this procedure. Blood loss, operating time, and pain are limited, allowing fast recovery in order to decrease morbidity and mortality.