Outcomes of the MS-30 cemented femoral stem.

The MS-30 (Morscher-Spotorno) cemented femoral stem is a straight, three-dimensionally tapered, collarless implant for cemented fixation in total hip replacement, manufactured from a FeCrNiMnMoNb-alloy. This paper documents the review of 4 original follow-ups performed at four orthopaedic hospitals: three at the author's institution (Basel/Switzerland 2, Pietra Ligure/Italy 1), and one at the University Orthopaedic Hospital of Heidelberg/ Germany. A total of 911 hips in 867 patients have been provided with the MS-30 stem. All stems were fixed with Palacos bone cement, the great majority with antibiotic (Gentamicine) loaded cement. The mean observation time was 10.2, 5.6, 10.2 and 6.5 years. One hundred and sixty-four hips were lost due to patients death, 121 patients were unable to come to the follow-up check. Ten patients only were lost to follow-up. The total number of hips with a clinical radiological follow-up was 597. The clinical and radiological assessment was in accordance with the International Documentation and Evaluation System (IDES) forms from the Institute of Documentation of the M.E. Müller Foundation in Berne/Switzerland. RESULTS The overall survivorship in the four follow-ups were 100% after 10 years, 98.4% and 99.2% after 5.5.years, 98.5% after 10 years and finally 96.1% after 6.5 years. The respective percentages of survival for aseptic loosening were 100%, 99.2%, 100%, 98.5% and 98.8%. CONCLUSION According to the NIH (National Institute of Health, United Kingdom) a survival rate of 95% regarding aseptic loosening justifies or even recommends further clinical use of the respective endoprosthesis system.

Ten-year survival of the MS-30 matt-surfaced cemented stem.

The Morscher-Spotorno (MS-30) femoral stem is a stainless-steel, straight, three-dimensionally tapered, collarless implant for cemented fixation in total hip replacement. We report the results at ten years of a consecutive series of 124 total hip replacements in 121 patients with the matt-surfaced MS-30 stem and an alumina ceramic head of 28-mm diameter. All the stems were fixed with Palacos bone cement with gentamicin using a modern cementing technique. They were combined with an uncemented, press-fit cup. The mean period of observation was 10.2 years (8.3 to 12.1) and no patient was lost to follow-up. Twenty-seven patients (22%) died with the implant in situ. Nine could only be interviewed by telephone. We included 85 patients with 88 hips in the clinical and radiological follow-up examinations. None of the stems or cups had been revised. The Harris hip score was excellent or good in 97% (85 hips) and moderate in 3% (three hips). Radiologically, six hips (6.8%) had osteolysis adjacent to the stem, mostly in Gruen zone 7. Twenty (22.7%) showed one or more radiolucent lines. Twenty-two stems (25%) had subsided by 2 mm to 5 mm. In these cases two showed osteolysis (9.1%) with subsidence and four without (6.1%). Radiolucent lines were seen in seven with migration (31.8%) and in 13 without (19.7%). No infections and no acetabular osteolysis were observed. The clinical results were excellent with survivorship after ten years of 100% and only a slightly statistically non-significant higher rate of osteolysis and radiolucency in cases of subsidence.

Acetabular revision in total hip replacement with a press-fit cup.

The need for supplementary screw fixation in acetabular revisions is still widely debated. We carried out 439 acetabular revisions over an eight-year period. In 171 hips with contained or small segmental defects, the Morscher press-fit cup was used. These revisions were followed prospectively. No screws were used for additional fixation. A total of 123 hips with a mean follow-up of 7.4 years (5 to 10.5) were available for clinical and radiological review. There was no further revision of a press-fit cup for aseptic loosening. Radiological assessment revealed osteolysis in three hips. Of the original 171 hips there was cranial and medial migration of up to 6 mm at two years in 44 (26%). No further migration was seen after the second post-operative year. Acetabular revision without screws is possible with excellent medium-term results in well selected patients.

Nine-year results of Müller cemented titanium Straight Stems in total hip replacement.

At the Orthopaedic Department of the University of Basel, a total of 540 cemented Müller titanium alloy (Ti6Al7Nb) Straight Stems were inserted between 1989 and 1993. A cohort of 120 consecutive patients (66 women, 54 men) with 126 prostheses operated on between March and December 1989 were followed clinically and radiologically in a prospective manner for a mean observation time of 9.1 years. In all cases, the Müller titanium alloy Straight Stem was combined with the senior author's (E.W.M.) Press-Fit Cup. The mean age of the patients at surgery was 66 (range 43-93) years. Fourty patients (41 hips) died, 9 were interviewed by telephone, none was 'lost to follow-up'. Seventy-one patients with 76 hip replacements were available for the follow-up. Four hips had been revised: two of them due to aseptic loosening of the femoral component, one because of a late infection--all after 9 years--and one owing to a periprosthetic fracture after 6 years. The 9-year overall survivorship is 96.8%, and for aseptic loosening of the stem 98.4%. None of the cups had to be revised for aseptic loosening. The clinical result (according to Merle d'Aubigné) was excellent and good in 88%, moderate in 8%, and poor in 4%. The radiological analysis showed no osteolysis or radiolucent lines in 59 prostheses (78%). Nine stems (12%) showed a radiolucent line. Focal osteolysis was detected in 8 cases (10%) in one or more Gruen zones. The distribution of the osteolyses shows that predominantly zones VII, VI, V, and II are affected in decreasing frequency. No osteolysis was detected on the acetabular side. Our results do not confirm the high rate of osteolysis and revisions with the Müller titanium alloy Straight Stem presented by some other institutions. The verdict on a specific endoprosthetic implant must be made by combined assessment of the design, the implant surface condition, the material, the cement, the cementing procedure and the operative technique. The statement made in earlier publications that cemented titanium alloy should not be used as a femoral stem prosthesis should be reconsidered.

[Acetabulum revision. Classifications and treatment possibilities]. / Die Pfannenrevision. Klassifikationen und Behandlungsmöglichkeiten.

Several different defect classifications have been published. The most commonly used are described. For clinical practice, differentiation between "contained" and "noncontained" or segmental defects has proven useful. If the acetabular rim provides support, press-fit cups can be used without screws. With an appropriate reaming technique, it is possible to create a sufficiently supportive bed for the implant in many cases. This allows the use of a press-fit acetabular component over a wide range of defects as long as a tilting of the cup can be avoided. Between 1988 and 1995, 439 acetabular cups were revised at the Orthopedic University Clinic in Basel, 171 of them using the Morscher press-fit cup. After a mean follow-up of 7.1 years, not a single cup had to be revised for aseptic loosening. The 9.5% dislocations were due to abductor insufficiencies because of trochanteric pathologies or muscular alterations from former approaches.

[Comparative periprosthetic bone density measurements of the proximal femur shaft using dual energy x-ray absorptiometry (DEXA) with experimental "Press Fit-gliding Stem Prosthesis"]. / Vergleichende periprothetische Knochendichtemessungen am proximalen Femurschaft mittels Dual Energy X-ray-Absorptiometry (DEXA) mit experimenteller "Press Fit-Gleitschaftprothese".

PROBLEM: Periprosthetic bone atrophy caused by stress shielding is one of the problems of non-cemented femoral stems of hip arthroplasty. Stress shielding and thus the loss of bone mass and their dissemination in the proximal part of the femur of conventional non-cemented femoral stems depends on stiffness (E-modules of the material and the geometry) of the implant and on the bonding between implant and bone. All currently implanted non-cemented femoral stems lead to proximal bone loss which goes up to 40-50% of the original bone mineral content. The senior author (E. M.) developed a femoral stem (Press Fit-Gliding Stem PFGS) which shifts relative movements of force-transmission from the bone-implant interface into the interior of the prosthetic system (Inner Bearing-System) and which only transfers forces proximal into the femur. METHOD: The examinations were made in 21 patients between 1 and 6 years after implantation of a Press Fit-Gliding Stem compared with a normal contralateral femur (12), with bilateral PFGS (3) and other bilateral arthroplasty (6). RESULTS: In all 21 patients supplied with a PFGS an increase of bone mineral content (BMC) and bone mineral density (BMC) in zone 7 as well as a marked smaller deviation around the mean value in all zones respectively could be noticed. CONCLUSIONS: With the Dual Energy X-ray Absorptiometry (DEXA)-measurement of bone mineral content (BMC) and bone mineral density (BMD) in all zones according to Gruen could be shown that it is not only possible with regard to a favorable force transmission to avoid the inevitable bone atrophy but on the contrary to induce an increase of bone at the point of local force transmission that is in the region of the calcar femorale (zone 7). CLINICAL RELEVANCE: The Press Fit-Gliding Stem is still in the clinical test-program.

Rationale of a flexible press fit cup in total hip replacement. 5-year followup in 280 procedures.

A consecutive series of 280 total hip replacements in 261 patients using the Press Fit Cup with a minimum followup of 5 years is presented. The Press Fit Cup is a nonmodular acetabular component with a porous coating made of titanium fibers. It has one peg and is 1.5 mm oversized with biradial eccentricity. It has a flattened pole area, requires no screw fixation, and partially preserves elasticity. The mean age was 71 years for women, 70 years for men. Forty-seven patients (49 hips) died before the 5-year review, and five patients were unable to return for the followup because of physical infirmity. Two hundred eighteen patients (226 hips) were available for the clinical 5-year followup, and 208 patients (213 hips) were available for the radiographic followup. No intraoperative fracture of the acetabulum occurred; four hips dislocated; 94% clinically were rated as excellent or good. One hip in a patient with rheumatoid arthritis had to be revised for aseptic loosening of the cup and nine femoral stems had to be revised. No migration of the cup could be measured. There was no osteolysis seen around the cup. In six cases a radiolucent line was seen in Zone 1, and in eight hips in Zone 3. There was one hip with a continuous radiolucent line which was considered radiographically loose.