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.

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.

Healing of the transected anterior cruciate ligament in the rabbit.

Healing of the anterior cruciate ligament was studied in 170 male rabbits. One group included immature animals that had open epiphyses, and a second group consisted of only mature animals. In one knee of each animal, the anterior cruciate ligament was transected either completely or partially, and in the contralateral knee a sham operation was carried out. Mechanical testing and histological studies of the ligaments were done immediately postoperatively and at two weeks, six weeks, three months, and one year. As we expected, there was no regeneration after complete transection of the anterior cruciate ligament, and all of the animals in which this procedure was done had severe osteoarthrosis of the joint at three months. Postoperatively, the partially sectioned ligaments exhibited one-third of the strength of the ligaments on the side on which the sham operation had been done in the immature animals and one-fourth of the strength of the ligaments on the side on which the sham operation had been done in the mature animals. Subsequently, there was secondary complete rupture of 20 per cent of the partially sectioned ligaments. The remaining 80 per cent of the partially sectioned ligaments were clearly weaker two weeks after the operation than immediately postoperatively, but this was also true on the side on which the sham operation had been done. At six weeks, the initial postoperative strength of the partially sectioned ligaments had been regained. At one year, the ligaments of the immature animals were two-thirds as strong as those on the contralateral side, and those of the mature animals were three-fourths as strong as those on the contralateral side. The ligaments were markedly elongated, especially in the mature animals. At three months, stiffness of the ligaments returned to normal. Histologically, the defect was filled with tissue that was still somewhat different from normal ligamentous tissue.

Cementless uncoated polyethylene acetabular components in total hip replacement. Review of five- to 10-year results.

We reviewed the results of 545 consecutive total hip replacements using a cementless non-coated high-density polyethylene acetabular component combined with a cemented Müller stem at five to 10 years. In all, 421 patients (445 hips) were available for review, 118 by questionnaire and 303 by examination and radiography. Of these, 86% had a good or excellent result. We found a high rate of radiological loosening of the cup after the sixth year, and a high rate of clinical loosening after the eighth year. Loosening was commoner in women, in younger patients and where a smaller size of acetabulum had been used. Calcar resorption was significantly related to loosening of the acetabulum. Loosening appeared to be mainly due to polyethylene debris produced by micro-movement of the acetabulum against the bone, which had resulted in a giant cell foreign body reaction and subsequent bone erosion. We have abandoned the use of this prosthesis and suggest that direct contact between bone and polyethylene should be prevented by a coating of metal or some other material.

Severe osteolysis after third-body wear due to hydroxyapatite particles from acetabular cup coating.

One concern about the fixation of HA-coated implants is the possible disintegration of the surface, with the migration of HA granules into the joint space, producing third-body wear. We report a study of six revisions of HA-coated polyethylene RM cups at 9 to 14 years after successful primary arthroplasty. In all six hips, we found HA granules embedded in the articulating surface of the polyethylene, with abrasive wear of the cup and the metal femoral head. The cup had loosened in four hips and three showed severe osteolysis of the proximal femur. Third-body wear due to HA particles from implant coating may produce severe clinical problems with few early warning signs. Further clinical, radiological and histological observations are needed to determine the possible incidence of this late complication in the various types of coating of a variety of substrates.

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.

The relationship between periosteal division and compression or distraction of the growth plate. An experimental study in the rabbit.

We subjected the proximal tibial growth plates of six-week-old rabbits to either compression or distraction of 1 kg on both legs. On one side the proximal tibial periosteum was divided circumferentially and stripped for 1 cm. After six weeks, growth was measured at both proximal and distal growth plates. Compression inhibited total tibial growth and distraction enhanced it. The compressed growth plate grew less and the distracted growth plate grew more, but there was a reciprocal change at the other end of the bone. Periosteal division enhanced growth at the adjacent growth plate but inhibited it distally; the effect of distraction was enhanced and that of compression reduced. We found reciprocal growth rates at the proximal and distal growth plates. Relatively small amounts of compression or distraction did affect total bone growth. Periosteal division appeared to induce overgrowth at least partly by a mechanical effect; it may be useful as an adjunct to other methods of leg lengthening, though not to epiphyseolysis.

Bone growth and remodelling after fracture.

We used a rabbit model to investigate the mechanism by which the angulation of fractures is corrected in children. We produced a transverse proximal tibial fracture in one leg of 12 eight-week-old New Zealand white rabbits and measured bone alignment and length and the patterns of bone growth and remodelling. The angle between the joint surfaces changed rapidly to correct the alignment of the limb as a result of asymmetrical growth of epiphyseal plates. In an adult with closed plates, the angle between the joint surfaces cannot therefore improve. The angle at the fracture itself showed slow improvement because of bone drift and the asymmetrical growth of the epiphyseal plates. Remodelling corrected the shape of the bone in the region of the fracture. Periosteal division on the convex side increased the growth of the epiphyseal plate on that side, thus slowing the correction. The effect was relatively small, providing an indication that factors other than the periosteum are important in inducing correction. External torsional deformities developed because of helical growth at the plate. This was probably caused by abnormal posture which induced a torque at the growth plate. Helical growth is the mechanism by which rotational deformities can occur and correct.

Failures and successes in total hip replacement--why good ideas may not work.

The course of development of total hip replacement (THR) is neither harmonious nor linear. Progress and set-backs alternate. Progress in THR manifests itself through reductions in the number and the severity of complications (infection, aseptic loosening, prematurely worn components, etc.). Innovation is the motor of progress. However, today's innovation may well be tomorrow's revision! Progress has been achieved in part through new implant materials and designs that provide improvements in such things as stress distribution in surrounding bone, tissue compatibility and osseointegration, and resistance to both wear and cyclic fatigue. Of at least equal importance, however, are improvements achieved in operative procedures (e.g., cementing technique) and finally, in clinical quality control: more complete documentation of implant and patient variables, establishment of implant registers, and utilization of outcome studies to guide the course of further development. Causes of failure in THR are numerous. However, unexpected side effects of innovations are the most frequent cause. An innovation may solve one problem, but also creates new ones. Problems in innovation which can lead to failures include: over-generalization of expected patient responses, ignoring past experience or assigning wrong causes to encountered problems, and finally, ignoring the dynamic nature of the living system (which can be described as using "necro-" instead of biomechanical thinking). Quality control in both manufacturing and clinical practice has to be improved. The pioneer times have come to an end. Today's patients should have the right to be operated on by a well trained surgeon and to be provided with well tested, well-understood implant materials and devices. Progress in endoprosthetics has led to the present high level of clinical success. Paradoxically, however, success is the greatest obstacle to further progress. This is because the curve of progress as a result of effort expended has turned asymptotic in endoprosthetics, as it does in many endeavors. In such situations the more a product (e.g., surgical implant and procedure, automobile design, computer program) becomes successful, the more efforts (and finances) are needed for further progress. On the other hand, the "scissors"--created by crossing what might be feasible with what resources are available--open widely and can cut sharply. In fact, financial restrictions may force orthopaedic surgeons and the medical device and technology industry to turn to lower technologies in the future. However, whatever new developments in endoprosthetics may bring (be they sophistications or simplifications), we must remain open-minded and not assume things to be facts until there is evidence to support them.

Morton's intermetatarsal neuroma: morphology and histological substrate.

Twenty-three biopsies from patients with the typical symptoms of intermetatarsal neuroma (so-called Morton's metatarsalgia) were compared histologically and semi-quantitatively with 25 plantar nerves from the intermetatarsal space III/IV gained at autopsies from cases where no problems in the forefoot had been recorded. The histomorphological examination of the nerves from autopsies revealed the same findings as were found in the biopsies. Thus, qualitatively, the nerves from patients could not be distinguished from those gained at autopsy. The only difference was the diameter of the resected nerves: semi-quantitative analysis of the nerves showed that the 17 thinnest ones were all from autopsies and the five thickest ones from biopsies of symptomatic patients. At medium diameters, however, there was wide overlap of the two groups. The study yielded a specificity of the swelling of 80 % and a sensitivity of 78%. From these results it must be concluded that diagnostic MRIs or ultrasonography, are unnecessary for decision-making about operative treatment and are not superior to exploratory local anaesthesia. Since histomorphological findings in intermetatarsal neuroma (so far accepted as the gold standard for confirmation of that diagnosis) were the same as findings in autopsied (normal) specimens, the value of postoperative histological examination is questioned. It merely proved that the nerve has been resected.

Femoral neck lengthening osteotomy after growth disturbance of the proximal femur.

Treatment of congenital dislocation of the hip, Perthes disease, bacterial coxitis, or fractures in childhood may be complicated by vascular insufficiency and subsequent growth disturbance of the proximal femur. The resulting deformity, with a high-standing greater trochanter and a short femoral neck, causes leg length shortening and insufficiency of the hip abductors with a positive Trendelenburg sign and limp. Normal anatomy and biomechanics of the hip joint can be restored by lengthening the femoral neck after two parallel osteotomies of the femur at the the upper and lower border of the femoral neck, followed by distalization the greater trochanter. This femoral neck lengthening osteotomy was first described by the senior author (EM) in 1980. This retrospective study of 37 operated patients with a mean follow-up of 8 years shows good results in 32 patients with little or no preexisting osteoarthritis. Four of five patients with marked degenerative changes underwent a total hip replacement within 1 to 9 years after the osteotomy.

Operative stabilisation of dislocations, fractures and fracture-dislocations of the cervical spine.

A retrospective study of 76 patients with surgically treated cervical spine injuries from 1971 to 1980 is presented. The indications for operative treatment, the technical procedures and the preliminary results are analysed. The conclusions are as follows: 1) A rational classification of the cervical spine injuries must precede the decision for operative or conservative management. 2) The intra- and postoperative complications are low with trained staff. 3) Unsatisfactory results from an operation are due to inappropriate indication for an anterior, posterior or combined fusion. 4) A laminectomy should never be done without a fusion, and a decompression of the spinal canal is better done as a rule by an anterior approach. 5) In children an anterior fashion should be avoided in order to prevent deformity from growth arrest of the end plates of the vertebrae. 6) In contrast to the degenerative disc disease the anterior fusion should always be secured by a plate.

[Treatment and prognosis in vertebral fractures in children and adolescents]. / Behandlung und Prognose von Wirbelfrakturen im Kindes- und Jugendalter

Twenty-six children and adolescents with a total of 65 vertebral fractures are reported. Sixteen patients could be followed up an average of 3 1/4 years after the accident. The questions of growth disturbance after vertebral body fractures and adequate treatment are chiefly considered. -Most of the fractures occurred in the midthoracic spine. As a rule they were serial fractures. -Fractures of the vertebral body with sagittal wedge deformity alone have a better prognosis than those with concomitant sagittal and frontal wedge deformities. Whereas those in the first group correct themselves partially or completely during subsequent growth, improvement in the wedge deformity was only observed in about one-third of the patients in the second group. When the end-plates were fractured, there was no correction and there was a lack in vertebral growth. Severe destruction of the cartilagenous plates and intervertebral discs led to a fusion of the corresponding segment. Increase in wedge deformity was observed twice. -Slight axial deviations of the intervertebral discs following vertebral body fractures are compensated for during growth in most cases. In comminuted fractures, the axial deviation persists but can be compensated for by the adjacent segments of the spine. In instable fractures, it can increase in spite of treatment in a Milwaukee corset. -No difference was found between the children treated with a hyperextension plaster corset and those treated functionally. On the basis of the results, the fracture types which should be treated functionally and those for which a plaster cast is recommended are indicated.

[Anterior plating of the cervical spine with the hollow screw-plate system of titanium]. / Die vordere Verplattung der Halswirbelsäule mit dem Hohlschrauben-Plattensystem aus Titanium.

A hollow screw-plate system made of titanium for osteosynthesis of the cervical spine is presented. This system is designed to achieve a stable fixation for fusion of the vertebra. The posterior corticalis of the vertebral body need not and indeed cannot be perforated by the screws. Loosening of the screws is not longer possible because of growth of bone into the lumen of the screw and direct attachment of bone to the surface of the screw.

Principles of acetabular fixation in THR with special reference to the "press-fit cup".

The "press-fit cup" has been developed by the author according to the current well known principles of cementless fixation of acetabular cups in THR. Its concept is to achieve primary stability through press-fit, by flattening the dome of the hemispheric cup and by using a cup size 1.5 mm larger than the reamer used previously. The coating (Sulmesh) consists of a net shell of four layers of orderly oriented wire meshes with specific pore size and porosity volume. The pure titanium wires are bonded together. The histologies of retrieved cups shows extensive bony ingrowth both in animal experiments and in autopsy specimens. In a radiological follow-up of 100 consecutive primary total hip replacements, the press-fit cup showed complete radiological integration in all 3 zones in 97% of cases. Nonprogressive radiolucencies were found in zones I and III in only 3% of cases.

Current state of cement fixation in THR.

The author surveys important landmarks in the development of total hip arthroplasty, with an accent on implant fixation using acrylic cement. He explains why he personally opted for hybrid prostheses, combining a cemented stem and a cementless socket, in patients over sixty years. Excellent cementless, sockets have been available for a long time; on the femoral side, the first steps were difficult, but several cementless, stems were subsequently developed, which provided excellent long term results. This historical evolution resulted in a very uneven use of cemented versus cementless stems from one country to another in Europe. Cemented implants have enjoyed a renewed popularity over the past few years as a result of several factors, including economical factors. The author discusses the conditions for optimal fixation of a cemented stem; these conditions are not always met satisfactorily, as a number of surgeons obviously stick to a crude cementing technique. The author describes the role of the stem geometry and surface finish, as well as the possible influence of a centralizer; he explains why, based on a correct analysis of the available data, discredit has been unduly cast on cemented stems made of titanium alloy. He insists on one important although often disregarded factor: the specific type of cement used, as better results have clearly been achieved with certain cements than with others. He insists on the necessity to take into account all the elements involved, in order to avoid making erroneous conclusions. He also insists on one very important variable, the quality of the surgical technique. Total hip arthroplasty is likely to make further progress in the future, although we are likely now in the asymptotic portion of an ascending curve. Further improvement in clinical results will result from improvement of currently existing systems and optimization of surgical technique, rather than from the continuous designing of new implants.

[Cementless socket fixation based on the "press-fit" concept in total hip joint arthroplasty]. / Zementfrei pfannenverankerung nach dem "Press-Fit-Konzept" bei der Totalprothesen-Arthroplastik der Hüfte.

PURPOSE OF THE STUDY: The key problem of implant fixation in THR is stress distribution, i.e. load transmission between bone and implant. The closer the load transfer is to the original physiological situation, the easier the adaptation of the periprosthetic bone to the new biomechanical conditions after implantation of the cup and the safer is its longlasting fixation. The aims of the studies were 1) to get information about the physiological load transfer in the normal hip joint, 2) to get information about the load transfer between acetabulum and acetabular sockets and vice versa, 3) to measure the periacetabular pelvic bone deformation as the stimulator of the remodelling process (third stage of osseointegration) in the normal hip joint and in hip joints fitted with different acetabular cups, 4) to study the morphological stages of osseointegration of a non-cemented press-fit cup and to compare the morphological structure of the periacetabular bone with the biomechanical data obtained by the in vitro studies and finally, 5) to compare the clinical and radiological outcome of follow-up studies of the senior author's "Press-Fit cup" with the theoretical hypotheses according to the experimental observations. MATERIAL AND METHODS: Load transfer between the acetabular bone and the femoral head on one side and press-fit cups has been determined by strain gauge measurements, finite element studies, pressure sensitive Fuji prescale films, CT-osteoabsorptiometry and telemetric measurements. Periacetabular deformation has been measured by Imetric Markers. Osseointegration of the senior author's press-fit cup and, thus, the remodelling process of the bony structures adjacent to the cup have been studied in autopsy specimens of THRs which have been in situ for several years. RESULTS: Load transfer measurements have shown that the main load in the original acetabulum as well as in the acetabulum fitted with a press-fit cup is transmitted to the periphery, especially to the acetabular cortical rim whereas the subchondral bone is exposed to lower, predominantly meridional (tension) stresses. Direct measurements of the periacetabular deformation under load revealed an increase of the peripheral press-fit with increasing stability of a (oversized) press-fit cup. Both the normal as well as the acetabulum fitted with a non-cemented cup deforms in a postero-medial direction. The histo-morphology of the periacetabular bone of autopsy specimens showed excellent bony in- and ongrowth of a porous titanium coating (SULMESH) and bone formation, especially at the periphery in zone 1 and 3 according to DeLee and Charnley. CONCLUSION: The studies have shown that the subchondral bone plate of the acetabulum has very little supportive function for non-cemented press-fit cups. For the preparation of the acetabulum it is, therefore, more important to ream the sclerotic subchondral bone until there is a well vascularized, well bleeding bone bed to facilitate osseointegration of a non-cemented acetabular socket than to preserve the subchondral bone plate as is the case in cement fixation. A non-cemented press-fit socket must transmit load predominantly to the cortical bone of the acetabular rim. Therefore, a too far medial positioning of the cup, and therefore loosing contact to the cortical rim, must be avoided under all circumstances. The clinical experience with acetabular revisions and with conversions of hip arthrodeses into a THR (where there is no subchondral bone at all) have shown the superiority of a well vascularized over a sclerotic (even mechanically stronger) bone bed. Furthermore, it has been shown that the additional use of screws for fixation of an acetabular cup is not only unnecessary but can be deleterious and causes complications including osteolysis and aseptic loosening.

Reimplantation or resection arthroplasty for septic loosening.

Resection arthroplasty should nowadays be considered as obsolete for the following reasons: the removal of the implant and adequate antibiotic therapy can clear the infection. From this point of view the reimplantation of an endoprosthesis is possible. "Deficient bone stock" is not a contraindication to the reimplantation since there are surgical means available to replace bone stock. The results of revision arthroplasty (reimplantation) are incomparably better today that they were years ago (cement-free technique, bone replacement, supports of the acetabulum, special revision prostheses etc.

Morselized homologous grafts in revision arthroplasty of the acetabulum.

Because they show fairly good short- and mid-term results frozen, morselized homologous bone grafts have become very popular in acetabular reconstruction after failed total hip arthroplasty. Graft integration proceeds uneventfully. However, very little is known about its longevity. From 1980 to 1984 we performed 121 acetabular revisions in cases with contained bone defects utilizing homologous bone graft and a cementless non-coated or hydroxyapatite coated HDPE cup. At the end of 1991 (7 to 11 years after the operation), 43 patients (35%) were available for review. 41 patients (34% had died, 19 patients (16%) were lost to follow-up. In 18 patients (15%), the cups had been revised because of aseptic loosening. The Harris Hip Score showed 50% good to excellent results. Cups inserted after grafting of cystic defects showed almost no migration. However when cavity defects were filled with large bone grafts (n = 23), slow continuous cup migration and progressive graft resorption over time was observed. Due to this continuous resorption, we conclude, that morselized bone grafts do not guarantee an ever lasting inert interface. Once the non-coated HDPE cup is in contact with the autogenous host bed, bone osteolysis occurs and loosening proceeds. Cementless porous coated cups with morselized allografts alone may be used in acetabular revision only when cystic defects are present. The surface of the cup has to be brought into contact with a well vascularized autochthonous pelvic bone in order to achieve stable fixation. Segmental and massive cavity defects can only be reconstructed with morselized allografts when protected from loading by supporting rings.(ABSTRACT TRUNCATED AT 250 WORDS)

Hip revision surgery in septic loosening.

62 patients with infected hip joints whose treatment was started between January 1980 and December 1986 were analysed retrospectively in December 1992 with a mean observation period of 7.2 years (range 1-13). The treatments employed were debridement with lavage drainage in 6 cases, one-stage replacement of the prosthesis on 47 occasions and two-stage replacement in 27 cases. On 5 occasions the prosthesis was removed and a Girdlestone procedure was undertaken. In the 47 one-stage replacements primary intervention was successful in 57% (n = 27), in the two-stage replacements in 74% (n = 20). In 42 cemented shafts there was primary healing in 34, i.e. 81%, compared with 13 (65%) in the 20 non-cemented shafts. Successful healing was finally achieved in all 62 infected hips.