Institute of Bone and Joint Surgery

Related Articles

Hydroxyapatite-coated RM cup in primary hip arthroplasty.

Int Orthop. 2003;27(2):90-3

Authors: Ali MS, Kumar A

We reviewed 113 patients with 127 primary total hip arthroplasties using a hydroxyapatite-coated RM (Robert Mathys) cup. Average patient age was 61 (30-70) years and mean follow-up was 9.4 (6-13) years. Four patients were lost to follow-up and nine patients died of unrelated causes during the course of the study. Three acetabular components were revised; two cups were radiologically loose and one was revised for marginal erosion. No radiolucency was noted in any of the three zones in the remaining cups. There were no cases of cup migration or dislocation. The life table method predicted a 10-year survival rate of 97.9% with revision of the acetabular component for any cause as the endpoint.

PMID: 12700931 [PubMed - indexed for MEDLINE]

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Cementless coated and noncoated Mathys acetabular cups: radiographic and histologic evaluation.

Orthopedics. 1999 Jan;22(1):39-41

Authors: Roffman M, Kligman M

This study evaluated 185 cementless Mathys coated and uncoated acetabular cups inserted for total hip replacement since September 1984. All of the cups were high-density polyethylene. Sixty were uncoated (group A), 96 were coated with hydroxyapatite (group B), and 29 were coated with titanium (group C). Cup survival was assessed clinically, histologically, and radiographically, and a computer-assisted EBRA method was used to evaluate cup migration. After a mean follow-up of 8 years, five cups in group A that had previously shown migration were revised as a result of aseptic loosening, while no loosening of hip sockets occurred in groups B and C. These results suggest that Mathys cups should be used only if coated with hydroxyapatite or titanium. Furthermore, the histologic evaluation in four cups from groups B and C revealed normal bone formation without inflammation or fibrotic tissue around the cups, promising long-term survival.

PMID: 9925196 [PubMed - indexed for MEDLINE]

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[Results of cement-free implanted, Robert Mathys isoelastic acetabular cup]

Unfallchirurgie. 1998 Apr;24(2):49-54

Authors: Olivier LC, Neudeck F, Hippel C, Kaiser S, Schmit-Neuerburg KP

In 163 patients--125 (76.7%) female, 38 (23.3%) male--172 cementfree isoelastic acetabular cups were implanted. The average patient age was 72.6 years (range: 16 to 96 years). Sixty-seven (41.1%) patients with 72 (41.9%) cups could be followed-up for an average of 6.0 years (range: 2.0 to 12.2 years) after the procedure. Using the Harris-hip-score we found 49 (68.1%) "very good" to "fair" results. In 23 (31.9%) hips scoring had to be classified as "bad". The rate of cup-loosenings in the collective was low at 3.5% (6/172), probably due to the reduced physical activity of our comparatively older patients. Because after the 8th year symptomatic loosening must be routinely expected, the procedure is not indicated for younger patients. In older patients with femoral neck fractures the cementfree isoelastic acetabular cup has proven itself effective in our experience.

PMID: 9606850 [PubMed - indexed for MEDLINE]

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Isoelastic total hip replacement: clinical evaluation of prosthetic isoelasticity.

J Formos Med Assoc. 1994 Jun;93(6):497-502

Authors: Au MK

By using the lower modulus material, polyacetal, ie, prosthesis made by R. Mathys', isoelastic hip prosthesis is claimed to reduce stress shielding effects and secure long-term, stable fixation of prostheses. In Tri-Service General Hospital from October 1985 to October 1989, 23 patients (25 hips) were treated using this prosthesis. Twenty patients (22 hips) were followed for clinical and radiographic evaluation for an average of 44.8 months (29-58 months). In clinical evaluation, the overall results were comparable to other cemented or cementless hip prostheses. The Merle d'Aubigne and Postel score for pain, motion and walking were improved from 1.6, 3.9, and 2.4 to 4.6, 4.3, and 4.9, respectively. The acetabular cup showed more favorable radiographic evaluation with a total mean score by combined Charnley and Engh's system of 7.9. It was not optimal on the femoral side and it showed that 20 of the femoral stems were stable fibrous fixations with a mean score of 15.8. Early complications included two dislocations, two significant femoral shaft fractures, and five medial neck cracks at surgery. The late complications included one loosening, one screw breakage, and one screw back out. The isoelastic hip always gained an inferior score in clinical evaluation from the "self comparison" in three patients with one side isoelastic hip and the other side different cemented or cementless prosthesis. There is no obvious benefit in radiographic evaluation, both in elimination of stress shielding and enhancement of fixation stability. As a result, the theoretical advantages of the isoelasticity concept are difficult to justify in our clinical practice.

PMID: 7858438 [PubMed - indexed for MEDLINE]

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Nine-year follow-up of the Mathys uncemented acetabular cup: a radiological evaluation.

Bull Hosp Jt Dis. 1993;53(1):51-3

Authors: Roffman M, Juhn A

Radiological studies were performed in patients who underwent hip arthroplasty using the Mathys acetabular cup. The development of radiolucent and sclerotic lines, subsidence, changes in position of the implants, changes in bone density, and the significance of these findings are discussed.

PMID: 8374492 [PubMed - indexed for MEDLINE]

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Special instruments and prosthetic cups for the removal and replacement of a total hip prosthesis.

Arch Orthop Trauma Surg. 1979 Mar 19;93(3):191-9

Authors: Stühmer G, Weber BG, Mathys R

In the course of replacing more than 500 total hip prostheses over a period of five years the authors have developed a new set of instruments for the removal of the defective prosthesis and cement and for improved anchorage of the new prosthetic cup. The set comprises: 1. A set of special chisels and an axially guided drill for removal of the old cement from the femur. These instruments greatly simplify the latter procedure. 2. A new type of prosthetic cup with a weight-bearing collar. This cup is used for cases in which the amount or structure of the acetabular bone is such that it will not support a conventional cup. 3. A new type of drill with a flexible drive and easily exchangeable drill bits for cutting anchorage holes in otherwise inaccessible parts of the acetabular bone.

PMID: 464755 [PubMed - indexed for MEDLINE]