Computer-aided manufacture of individual endoprostheses

Aldinger, G.; Fischer, Anne Kristin; Kurtz, B

doi:10.1007/bf00443036

Cited by 39 publications

(4 citation statements)

References 8 publications

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“…Because of the large anatomical variation in the femoral geometry at different locations, close-fitting femoral components cannot be consistently achieved with standard commercially available implants (Wettstein et al 2005). In order to solve this geometrical mismatch between the femoral canal and uncemented implants, custom-made femoral stems were initially developed in the 1980s (Aldinger et al 1983) and refined in the 1990s as computer technology became more widely used (Aamodt et al 2001). Here we report on a series of 3-dimensionally computed custom stems in a subgroup of high-risk patients (i.e.…”

Section: Discussionmentioning

confidence: 99%

Custom stems for femoral deformity in patients less than 40 years of age

Akbar¹,

Aldinger²,

Krahmer³

et al. 2009

Acta Orthopaedica

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Background and purpose Femoral deformity associated with osteoarthritis is a challenge for both the surgeon and the implant. Many of the patients with these deformities are young. Standard implants can be difficult to fit into these femurs. We prospectively evaluated the outcome of custom uncemented femoral stems in young patients.Methods 61 consecutive patients (72 hips) underwent surgery for osteoarthritis because of femoral deformity at a mean age of 35 (22–40) years. The patients received a CT3D-A custom-made femoral stem and an uncemented cup. The mean follow-up time was 14 (10–16) years. 2 patients died at 7 and 8 years after surgery, otherwise, none of the patients were lost to follow-up.Results At follow-up, the femoral prosthesis had not been revised in 59 patients (70 hips). 3 patients (3 hips) had required revision surgery due to loosening of the acetabular component; 2 hips were awaiting revision surgery for loosening of the acetabular cup. There were no cases of dislocation or infection. At review, all stems were considered stable according to the radiographic criteria. No migration or subsidence was observed on plain radiographs.Interpretation Our results are comparable to published results of custom stems regarding survival and outcome. Considering the young age and the deformities in this series of uncemented custom femoral stems, and the fact that there was follow-up of up to 16 years, the survival is remarkable. This technique appears to be a reasonable alternative in younger patients with femoral deformities.

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Section: Discussionmentioning

confidence: 99%

Custom stems for femoral deformity in patients less than 40 years of age

Akbar¹,

Aldinger²,

Krahmer³

et al. 2009

Acta Orthopaedica

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“…7 Since we introduced this stem in our clinic it has been combined with the HarrisGalante I cup. In 48 hips, other stems were used.…”

Section: Methodsmentioning

confidence: 99%

Survival analysis of the Harris-Galante I acetabular cup

Böhm

Bösche

1998

The Journal of Bone and Joint Surgery. British volume

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We reviewed 264 consecutive primary total hip replacements in 244 patients in which the Harris-Galante I porous-coated acetabular component had been used. The mean follow-up was 95 months (69 to 132). In 221 arthroplasties a 32 mm ceramic head had been used, and in the other 43 one of cobalt-chrome alloy. There were 124 women and 120 men with a mean age at operation of 56.8 years (21 to 83).Survival analysis of the acetabular components was performed using the following definitions of failure: 1) infection; 2) removal because of aseptic loosening; 3) removal for any cause; and 4) a worst-case analysis including removal of the cup or infection or loss to follow-up.Two well-fixed cups had been removed because of deep infection and three, similarly sound cups had been exchanged at the time of femoral revision. None of the acetabular components had required revision for aseptic loosening. After 11 years survival was 97.7% using the worst-case criterion. Radiological analysis of 187 acetabular components at a mean of 82 months (41 to 132) revealed no case of aseptic loosening. Pelvic osteolysis was seen in only one patient, but was not progressive and showed signs of regression.The results using these acetabular components are encouraging but the need for regular follow-up remains since complications such as significant wear of the liner, massive osteolysis of the pelvis, aseptic loosening and late infection may increase in the second decade.

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“…The femoral components of conventional total hip endoprostheses are usually available in standardized shapes in various sizes to offer surgeons the opportunity to select the best fitting size. More recently, custom femoral components have been designed, based on the concept don't fit the bone to the prosthesis, but the prosthesis to the bone (Aldinger, 1983), 1 but there is controversy about the relative benefits of custom prostheses. It had been suggested that a high percentage of cortical form-fit of custom implants may decrease the frequency of aseptic loosening and improve long-term stability; however, bone density studies (postoperative follow-up, 5 years) have shown that a custom femoral component (evolution hip endoprosthesis) may not prevent a reduction in periprosthetic bone density and stress shielding, despite a high form-fit.…”

Section: Introductionmentioning

confidence: 99%

Microsection analysis of cortical form-fit of a custom femoral component in total hip arthroplasty: an in vitro study

2012

Orthop Rev

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Custom femoral components have been developed for total hip arthroplasty to maximize cortical form-fit and thereby to reduce the problems of stress shielding and aseptic loosening. Limited information is available about how much endosteal cortical contact can actually be achieved with these expensive implants. The aim of this study was therefore to verify the exact cortical contact of a custom made stem using microsections and comparing it to a standard stem with similar design. In 8 human femurs (3 matched pairs and 2 separate specimens), custom femoral prostheses (Adaptiva; 5 femurs: 3 matched and 2 separate) and conventional femoral prostheses (Alloclassic; 3 matched femurs) were implanted. Endosteal cortical contact was determined from CAD planning drafts and microsections cut from the specimens with a diamond saw. Microsection analysis of the paired femurs showed that contact between prosthesis and bone varied clearly along the length of the femoral stem. Total cortical contact was considerably greater in custom prostheses than conventional prostheses (custom, 47%; conventional, 32%), but markedly less than the total contact predicted by the manufacturer (84% to 90%). The custom prosthesis had more lateral cortical contact on CAD planning drafts (cortical contact: medial, 60%; lateral, 53%) than on specimen microsections after implantation (medial, 64%; lateral, 24%).In summary, the philosophy of anchorage of both prostheses types could be confirmed. However, areas of cortical contact of the custom made prosthesis were considerably smaller compared to the pre-operative planning.

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Computer-aided manufacture of individual endoprostheses

Cited by 39 publications

References 8 publications

Custom stems for femoral deformity in patients less than 40 years of age

Custom stems for femoral deformity in patients less than 40 years of age

Survival analysis of the Harris-Galante I acetabular cup

Microsection analysis of cortical form-fit of a custom femoral component in total hip arthroplasty: an in vitro study

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