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H Effenberger

Publications and source records attributed to H Effenberger.

At least 19 recordsLinked to original sources
PubMed2006

[The importance of ultrasonography in orthopedics].

After patient history and clinical evaluation, sonography is a first-line modality in the orthopedic diagnostic algorithm together with laboratory results and standard radiographic findings. As an inexpensive investigation without known adverse effects it is used (and also repeated in the course of the disease) for the dynamic control of joint movements, and especially for imaging soft tissues. Sufficient training in the use of ultrasound in the musculoskeletal system is required; individual investigations are relatively time-consuming. The procedure is especially useful in evaluating the shoulder, hand, and knee regions and rheumatic illnesses.

Bone Diseases↗
PubMed2005

[Swan-neck and buttonhole deformities on rheumatic long fingers].

Patients suffering from rheumatoid arthritis in many cases develop typical swan-neck and buttonhole deformities. In the further course of the disease we observe several stages. In the beginning active and later passive correction are still possible, while ultimately a fixed contracture is present. The activities of daily life may be severely reduced. The pathology of the swan-neck deformity is initiated at the level of the metacarpophalangeal joint, while at the origin of the buttonhole deformity the synovitis of the proximal interphalangeal joint is obvious. In the early stages, synovectomy and balancing of the soft tissues are surgically indicated. In advanced stages, complicated soft tissue reconstruction in combination with alloarthroplasty or arthrodeses may become necessary to allow for sufficient finger function.

Arthralgia↗
PubMed2005

[Cementless stems of the hip. Current status].

Optimal fixation of cementless stems is a precondition for long-lasting stability. Thus, anchorage, stabilizers, material and surface are of essential importance. To achieve primary stability, good rotational, tilting and axial stability is necessary. Stabilizers such as fins and ribs optimize stability. The CCD-angle and length of neck-axis determine the offset (laterality), leg-length and center of rotation. The stem, is responsible for the fixation of the prosthesis and for transmitting forces to the bone. The types of fixation are epiphyseal (the femoral head is covered by a cup prosthesis), metaphyseal and meta-diaphyseal (with straight or anatomically shaped monoblock-prostheses of different lengths, modular and custom-made prostheses) and diaphyseal (using predominantly modular systems). Titanium alloys are the predominate material for cementless stems. The surfaces are generally corundum-blasted or plasma sprayed. For metaphyseal and meta-diaphyseal stems, survival rates from 95 to 98% have been reached after 15 years. Diaphyseal-fixed stems have mid-term survival-rates of 92-99%.

Arthroplasty, Replacement, Hip↗
PubMed2004

Factors influencing the revision rate of Zweymueller acetabular cup.

Between January 1986 and December 1988, we implanted 220 conical-shaped Zweymueller threaded cups in 202 patients whose average age was 65 (33-83) years. The average thickness of the polyethylene (PE) insert was 8.0 (5.4-11.9) mm. In 142 cases, the corresponding femoral head was a 32 mm Al2O3 head. We followed 157 patients for a mean of 9.2 (1-16) years. Nine cups were revised and ten PE inserts replaced after an average of 11.9 (10-13.3) years. With cup revision alone considered as failure, the survival rate after 13 years was 89%. When both cup and insert revisions were considered failures, the survival rate decreased to 72% after 13 years. Patients younger than 60 years had a significantly higher rate of insert revision. Cup size 55 showed significantly more revisions in comparison to larger sizes. Using Cox regression model, neither gender, body mass index, nor material were risks factors leading to cup revision.

Acetabulum↗
PubMed2004

[Acetabular shape and cementless cups. Comparison of osteoarthritic hips and implant design].

The anatomy of the hip must be taken into account in order to ensure primary stability of cementless acetabular implants. In this study we analyzed the shapes of osteoarthritic acetabula and compared these to normal non-degenerative acetabula and to pressfit implants. We measured 92 acetabula with osteoarthritic deformations and 35 non-degenerative acetabula. Bone tissue samples from 50 osteoarthritic acetabula were microradiographically analyzed. Furthermore, the size of the entrance plane of 37 pressfit cups was determined. The craniocaudal and ventrodorsal diameters of osteoarthritic acetabula correlate strongly ( r=0.87). In craniocaudal direction, the acetabular diameter correlates significantly to both the radius of the lunate surface ( r=0.42) and the acetabular base ( r=0.54). Osteoarthritic acetabula have a deeper shape as degeneration increases and the entrance plane becomes significantly more circular ( p<0.05). When comparing osteoarthritic and non-arthrotic acetabula, the following values differ significantly (p<0.05): craniocaudal radius of the acetabular base, craniocaudal and ventrodorsal radius of the lunate surface, and ventrodorsal divergence between lunate surface and acetabular base. To reconstruct an acetabular offset which concurs with central points of the femoral head and the radius of the lunate surface, the level of the insert's entrance plane must be outside the entrance planes of the cup and acetabulum. The rims of hemispheric cups need to be trimmed to prevent these cups from extending beyond the acetabular rim.

Acetabulum↗
PubMed2004

Anatomically adapted, HA coated SBG stem--ten years of successful implantation.

For stable implantation of anatomically conforming femur prostheses, modifications that accommodate curving and torsion are necessary. In accordance to this concept, the anatomically shaped SBG stem has been developed. The first consecutive implantations were evaluated. 194 primary arthroplasties with uncemented anatomical, HA coated SBG stems were performed. Mean patient age was 61 years. 143 patients with 151 (78%) SBG stems were followed-up clinically and radiologically after an average of 10 (9-11) years. So far, only one implant had to be revised. Survivorship with revision of the femoral component is 99.5% at ten years. The mean postoperative Harris Hip Score was 92. Patients over 75 years had a score of 89; younger patients under 40 years scored 94. Sclerotic lines were seen in zone I or VII in 8%. Minor femoral remodeling (Type 1) occurred proximally in 75%. Minor thickening of the femur at the level of the tip of the prosthesis could be observed in 27% of the cases. There is no correlation between compacta thickening and clinical symptoms (p=0.15). The anatomical shape, the oval diameter and the longitudinal grooves secure stable primary fixation. Together with the HA coating, which enhances osseointegration, the SBG stem has a high success rate in the medium and long term.

Adolescent↗
PubMed2004

[Cement-free hip cups. Current status].

Important criteria for stable cup fixation are the type of anchor system and stabilizers,cup form and the material and surface structure. Different fixation systems are manifest in pressfit and threaded cups. Pressfit implants are oversized and lead to equatorial jamming. For additional fixation, and to improve stability, screws, pegs, rings, fins, spikes or hollow cylinders are used. In threaded cups, thread geometry is decisive for the cup's performance during the screw-in process and positioning. The hemispheric shape of the cups requires less bone resection and the position of the implant can be arbitrarily selected. The conical shape guarantees high tilting stability. Most implants are made of pure titanium or a titanium-aluminum alloy. A rough surface area - produced by corundum blasting, titanium-plasma spray, titanium balls, nets or other grid designs - is essential for osseointegration. The results of second generation pressfit and threaded cups with 10 year survival rates of 93-100% are persuasive.

Acetabulum↗
PubMed2003

Primary stability of threaded cups in THR--an experimental study.

Four threaded cups were tested up to their lever-out moments, torque-in moments and their resistance to failure. A was a parabolic-shaped, B was a spherical, C was a spherical-shaped too, and D was a conical shaped cup. Cup A and D represent cups which have proven themselves in clinical applications, but not cup B. The threads were determined and showed different constructive features. The cups were torqued into precise cavities in PVC foam cubes, after that they were levered out in a testing machine. The lever-out moments of all the cups showed significant differences; the results were: A: 78.4 Nm, B: 88.7 Nm, C: 117.5 Nm, D; 136.6 Nm. In the case of the torque-in moments there were no significant differences between A and B, neither between C and D. The differences in stiffness between B and C were not significant, but they were between the others. The primary stability against lever-out and the torque-in moment of threaded cups for artificial hip replacement can be basically influenced by different constructive features. Hence lever-out moment and torque-in moment should be understood and tested as independent variables.

Arthroplasty, Replacement, Hip↗
PubMed2003

[Design, construction and modularity of pressure-fit acetabular cups].

To enable a comparison of different pressfit acetabular cups objective criteria are essential. The aim of this study is to describe the design features of this type of cup and to analyse currently available cups. 30 implants were systematically measured and analysed. The mean surface roughness (Ra) was determined and configurations established with the light section technique. For further evaluation the cups were transversely sectioned. The cups are made of pure titanium, titanium alloy or polyethylene coated with titanium. Five implants take the form of monoblocks. The configuration is predominately (n = 25) flattened spherical. The size of eight cups corresponds to the outer diameter, 19 cups have a larger outer diameter (overdimensioning), 3 cups have a smaller outer diameter (underdimensioning). The magnitude of overdimensioning is, on average, 1.9%. 9 cups are provided with plugs, hollow cylinders, fins or rings as outer stabilizers. Surface roughness achieved with corundum blasting is 6.8 microns. Titanium porous-coated implants have a surface roughness of 21-32 microns. 24 cups have polyethylene inserts, most of which are snap-fixed with equatorial lips. For 16 cups, full-ceramic inserts are available. 4 cups have a metal insert. Titanium implants with structured or HAC-coated surfaces have become the accepted standard for cementless acetabular cup implantation. Together with ceramic, metal, or modified polyethylene inserts they meet the requirement for permanent osteo-integrative stability.

Acetabulum↗
PubMed2003

Criteria for success with threaded cups (design, material and modularity).

PURPOSE OF THE STUDY: Over a period of three generations, threaded cups were developed and have become viable contemporary cementless hip implants. A few implants already have a high success rate over the mid and long term. Aim of this study was to evaluate contemporary threaded cups. MATERIAL AND METHODS: 30 of the second and third generation cups were systematically analyzed and measured using by a no-touch light section technique. Construction of inner form was determined with half sections. RESULTS: Approximately 50% have a conical shape, although there is a trend towards a more anatomical shape. 83% of the cups have a height up to 23% smaller than the radius. Only conical threaded cups have a relatively thin and constant wall thickness (1 mm-1.8 mm). Corundum blasted pure titanium, titanium alloys or HA coated implants are considered the standard materials. The insert is pre-assembled in two implants, otherwise the cups have modular inserts. Total ceramic inserts are found in four cups. Ceramic inserts with a sandwich construction are found in six cups. One cup has a full-metal insert. All other cups with metal-metal inserts have a sandwich construction. DISCUSSION: The studies by Kody (6) and our own studies (10) show that the V-cut threads have high values for turning moment and tilting stability. CONCLUSION: The screw-in behavior of threaded cups is largely determined by the design of the threads. Material and surface of threaded cups influence osseointegration and therefore long-term results. Contemporary threaded cups have a narrow V-cut and saw threads or flat threads with depths up to 3 mm, on average 4 turns, and pith values of approximately 4.5 mm. Three generations of threaded cups development were necessary to procure the current form with highly satisfactory mid- and long-term results.

Arthroplasty, Replacement, Hip↗
PubMed2002

[Modification of form, material and modularity of threaded acetabulum cups].

The fixation principle of threaded cups ensures high primary stability. Inadequate results with first-generation threaded cups led to modifications of surface machining. 10 threaded cups of the first generation, and 27 of the second and third generations were systematically analysed and their shapes measured using a no-touch light section technique. In addition, measurements of surface roughness were performed. Implants of the first generation made of polyethylene, ceramic or cobalt-chrome have an average surface roughness (Ra) of 1.5 microns. Approximately one-half of these implants have a conical shape, and one-third a height that is greater than the radius. Threaded cups of the second generation are made either of CP-titanium or titanium alloy. The average corundum-blasted surface roughness is 4.5 microns. Hydroxyapatite-coated (HA) implants have a surface roughness of 5.0 microns. Approximately 45% of the implants have a conical, biconical or flattened-conical shape, while one-third are of hemispherical shape. Approximately 90% of the cups have a height that is up to 23% smaller than the radius. A few cups have a height that approximates the radius. Implants of the third generation with identical surface structure can be supplied with crosslinked-polyethylene inlays or, optionally, with metal/metal or ceramic/ceramic contact surfaces. Primary stability, biocompatible materials and a structured surface are essential for ensuring osseointegration over the long-term. Corundum-blasted pure titanium or titanium alloys with corundum-blasted or HA-coated implants can be considered standard for these cups.

Acetabulum↗
PubMed2001

Characterisation of retention in micellar high-performance liquid chromatography, in micellar electrokinetic chromatography and in micellar electrokinetic chromatography with reduced flow.

The retention (migration) behaviour of various barbiturates, phenylurea and triazine herbicides in micellar electrokinetic chromatography (MEKC) with uncoated fused-silica capillaries was compared with the behaviour in micellar electrokinetic chromatography with reduced electroosmotic flow (RF-MEKC) using capillaries modified with linear polyacrylamide. The error in the values of the retention factors caused by the neglection of the contribution of the electroosmotic flow in RF-MEKC was investigated and a method for correcting this error was suggested. The retention was characterised using the lipophilic and polar indices to characterise and to predict the retention as a function of the concentration of the surfactant (sodium dodecylsulphate) in the running buffer in MEKC and in RF-MEKC. Homologous series of n-alkylbenzenes and of n-alkan-2-ones were compared as the standard sets for the calibration of the retention (migration) index scale. The values of the lipophilic indices of a given solute measured in reversed-phase HPLC, MEKC and RF-MEKC are close to each other. Under ideal MEKC conditions, the values of the polarity indices are close to one for various sample solutes. However, for partially ionised compounds such as weakly acidic barbiturates, where the contribution of the electrophoretic migration is significant, the values of the polarity indices are significantly lower than one. Optimum conditions for separations of mixtures of triazine and phenylurea herbicides and of barbiturates using various techniques tested were compared.

Chromatography, High Pressure Liquid↗
PubMed2001

Stress analysis of threaded cups.

Using finite element analysis we have studied the pelvic bony socket and compared it with radiological imaging using threaded acetabular cups of three different shapes (parabolic, conical, hemispherical). The two-dimensional model depicted a planar section through a left pelvic hemisphere. In all three cups the stress in the bony socket increased from lateral towards medial. Compressive stress was found on the superior and inferior parts of the cup, but mainly on the superior aspect, seen radiologically as new trabecular bone formation. The maximum compressive stresses were seen in the cranial curvature of the conical cup, with less in the parabolic form and least in the hemispheric form. The tensile stress at the bottom of the socket increased from the hemispheric to the conical shape. Radiological rarefaction gave an indication of lower stress. There was lower compressive stress between the teeth of the threads. This FE model uses computer simulation to predict bony changes with different designs of implant. The ability to simulate biological conditions is a valuable addition to the testing of mechanical strength.

Hip Joint↗
PubMed2001

Miller-Galante total knee arthroplasty: the importance of material and design on the revision rate.

We have reviewed 142 Miller-Galante I (MG I) total knee arthroplasties (TKAs) with a follow-up of 56 months, and compared these with the outcome of 219 Miller-Galante II (MG II) TKAs with a follow-up of 36 months. In the MG II TKAs we found markedly lower revision rates, higher postoperative Hospital for Special Surgery (HSS) scores, less retropatellar pain and better patellar centring without patellar resurfacing. The higher revision rate in MG I TKAs was mainly due to the need to revise the metal-backed patellae.

Arthritis↗
PubMed2001

A model for assessing the rotational stability of uncemented femoral implants.

Permanent secondary stability of the uncemented femoral stem of hip prostheses can only be achieved once primary rotational and axial stability has been ensured. Rotational stability means that the stem is resistant to the articular forces that induce rotation around the implant's longitudinal axis. The 10-year survival rates of two uncemented conical shaped stems with decisively different proximal shapes were significantly different (Schenker SK 63.9%, Zweymüller SL 97.0%). The shapes were analyzed biomechanically by testing rotational stability in a silicone model. A reduction in the mediolateral height of the metaphyseal part by one-third led to a 20% smaller angle of ascent (P < 0.01), which indicated lower resistance. The proximally broader (mediolateral) prosthesis therefore proved to have better rotational stability. The study confirms that aseptic stem loosening is attributable to the design of the proximal part of the prosthesis.

Arthroplasty, Replacement, Hip↗
PubMed2000

Experimental study of bone-implant contact with a parabolic acetabular component (Hofer-Imhof).

Incomplete bone contact with threaded acetabular components is usually attributable to the tapered thread design and sclerotic bone, and might be the reason for early loosening. The self-tapping flat threads of the Hofer-Imhof cup allow accurate insertion without incarceration, even in sclerotic bone. To demonstrate the effectiveness of this threaded cup design based on digitized measurements of bone contact area, six Hofer-Imhof cups were implanted into three human cadavers. The bone contact area at the threads was digitally analyzed on cadaver-explanted cups cut into horizontal and coronal sections. In cups fixed with ideal form fit, bone contact was 31.6% (range 8-55%) at the threads and 28.5% (range 0-49%) between the threads on average. In cups with incomplete bone contact secondary to insufficient reaming, the bone contact area averaged 27.4% (range 10-44%) at the threads. In sclerotic bone, the highest bone contact at the threads was 69%. The threads were the first part of the cup to achieve primary bone contact. Factors contributing to poor contact were incomplete reaming, sections which passed through the incisura of the acetabulum, and incomplete contact with the medial aspect of the acetabulum. The aim was to achieve complete bone contact. Because of the higher contact areas observed in sclerotic bone, some sclerotic bone should remain after reaming.

Acetabulum↗
PubMed2000

Quality assurance in hip arthroplasty.

Documentation is key to quality assurance (QA): Data must be complete, plausible, and comparable, and then analyzed to implement corrective measures. Important factors are: qualification of care-providing staff, equipment and implants available (structural quality), effective scheduling of operations and therapy management (process quality), and patient status monitoring (outcome quality). The primary aim is to reveal deficits in process quality and develop and implement improvements in care. QA does not aim at exposing individual mistakes or flawed techniques; rather it is designed to analyze processes and treatments and implement specific solutions. An evaluation profile with the key quality indicators and a QA guideline is presented. A survey conducted in Germany, Austria, and Switzerland revealed: (1) up to 12-month waiting period for surgery in 6%, (2) only 40% written instructions, (3) data mostly written by hand, (4) differences in surgery planning and use of prosthesis passport, (6) inconsistent data analysis, (7) corrective measures rarely implemented.

Arthroplasty, Replacement, Hip↗