Kersten Berndt1, Stefan Rahm2, Claudio Dora1, Patrick O Zingg1. 1. Department of Orthopaedics, Balgrist University Hospital, University of Zurich, 8008 Zurich, Switzerland. 2. Department of Orthopaedics, Balgrist University Hospital, University of Zurich, 8008 Zurich, Switzerland. Electronic address: stefan.rahm@balgrist.ch.
Abstract
BACKGROUND: The direct minimally invasive anterior approach (DMIAA) in total hip arthroplasty (THA) is widely accepted. In our department the DMIAA according to Rachbauer together with the Trident cup and Accolade stem was introduced in 2004. The purpose of the study was to demonstrate the five-year results and to analyze the learning curve of a new introduced approach. PATIENTS AND METHODS: Between July 2004 and May 2006, a consecutive series of 151 THA in 147 patients was retrospectively analyzed. All patients were planned to received a THA with the Accolade/Trident implant system using the DMIAA without traction table. Clinical and radiographic data, complications and survivorship were documented with a follow-up of at least 5 years. RESULTS: Regarding cup implantation, there were 11 (7.3%) failed intentions to treat due to missing pressfit (8 cases) and acetabular floor perforation (3 cases). No failed intentions to treat occurred during stem implantation. Total implant survival after 5 years follow-up after exclusion of 11 cases with failed intention to treat (N=140) was 96.9% (SD 1.4; CI 94.3-99.6). After exclusion of the failed intentions to treat (N=140, N=4 in the first 20 cases), there was significant (p<0.001) difference between the first 16 implants with a 5 year-survival of 83.2% (SD 8.6; CI 66.4-100) and 95.7% (SD 0.9; CI 93.9-97.5) for the following 124 implants. Radiolucent lines were observed in Gruen zone 1 in 3.3% and in Gruen zone 1 and 2 in 1.1%. DISCUSSION: THA with Accolade/Trident using the DMIAA without traction table according to Rachbauer temporary exposed patients to a higher risk of implant revisions, which was normalized after the first 20 cases. Results of the learning curve are comparable to other techniques using an orthopaedic traction table. After the typical learning curve, the rate of 5 years implant failure is in accordance with the registry data for non-cemented implants. The Accolade stem showed minimal radiographic signs of radiolucency. LEVEL OF EVIDENCE: IV, retrospective, consecutive case series.
BACKGROUND: The direct minimally invasive anterior approach (DMIAA) in total hip arthroplasty (THA) is widely accepted. In our department the DMIAA according to Rachbauer together with the Trident cup and Accolade stem was introduced in 2004. The purpose of the study was to demonstrate the five-year results and to analyze the learning curve of a new introduced approach. PATIENTS AND METHODS: Between July 2004 and May 2006, a consecutive series of 151 THA in 147 patients was retrospectively analyzed. All patients were planned to received a THA with the Accolade/Trident implant system using the DMIAA without traction table. Clinical and radiographic data, complications and survivorship were documented with a follow-up of at least 5 years. RESULTS: Regarding cup implantation, there were 11 (7.3%) failed intentions to treat due to missing pressfit (8 cases) and acetabular floor perforation (3 cases). No failed intentions to treat occurred during stem implantation. Total implant survival after 5 years follow-up after exclusion of 11 cases with failed intention to treat (N=140) was 96.9% (SD 1.4; CI 94.3-99.6). After exclusion of the failed intentions to treat (N=140, N=4 in the first 20 cases), there was significant (p<0.001) difference between the first 16 implants with a 5 year-survival of 83.2% (SD 8.6; CI 66.4-100) and 95.7% (SD 0.9; CI 93.9-97.5) for the following 124 implants. Radiolucent lines were observed in Gruen zone 1 in 3.3% and in Gruen zone 1 and 2 in 1.1%. DISCUSSION: THA with Accolade/Trident using the DMIAA without traction table according to Rachbauer temporary exposed patients to a higher risk of implant revisions, which was normalized after the first 20 cases. Results of the learning curve are comparable to other techniques using an orthopaedic traction table. After the typical learning curve, the rate of 5 years implant failure is in accordance with the registry data for non-cemented implants. The Accolade stem showed minimal radiographic signs of radiolucency. LEVEL OF EVIDENCE: IV, retrospective, consecutive case series.