Fragestellung: Extrakorporale Stosswellentherapie (ESWT) wird bei chronischer Epikondylitis humeri radialis (EHR) als alternative Therapieform empfohlen. Eine Beeinflussung der Durchblutung wird al...

Article Materialabhängige Differenzierung von humanen Knochenmarkszellen - Eine Zellkulturuntersuchung mit orthopädisch relevanten Biomaterialien - was published on January 1, 1995 in the journal Biomedical Engineering / Biomedizinische Technik (volume 40, issue s1).

Fragestellung: Um den Stand der Dokumentation als Instrument zur weiterführenden kontinuierlichen Qualitätssicherung in der Endoprothetik zu erfassen, erfolgte eine schriftliche Umfrage zu diesem Thema. Die Zielstellung konzentrierte sich auf Elemente der Strukturund Prozeßqualität.

By a failed first operation allogenic tissues, as human Achilles tendons are offered for anterior cruciate ligament replacement. The effects of freeze-drying and primary Gamma- or EO-sterilization on the mechanical properties of 62 complete and 74 bisected tendons again fresh frozen controls were investigated under axial tension. A significant decrease of tensile strength for the freeze-dried preparations of 33% for the whole and 43% for the bisected tendons were observed, while Gamma- or EO-sterilizations showed a smaller deleterious effect on the tendons. Considering only the primary mechanical strength complete freeze-dried or complete and bisected irradiated Achilles tendons show sufficient tensile strength for anterior cruciate ligament replacement.

The author presents a modification of Morscher's sagittal osteotomy of the patella especially for the treatment of excentric chondromalacia. Congruity of the joint spaces in this modification is achieved through removal of an anteriorly based bone wedge from the patella after sagittal wedge osteotomy allowing the lifting of one or the other patellar facet. This osteotomy is indicated in all cases of unilateral chondromalacia or arthrosis with narrowing of the two joint spaces viewed on tangential patello-femoral X-rays. Following the ideas of Pauwels and Maquet, restoration of a wide joint space and reduction of local excessive stress result in reparative mechanisms of the cartilage involved. The to date preliminary clinical results in 5 cases (1 year max. follow-up) are encouraging.

A review of the currently clinically established biomaterials UHMWPE, Al2O3-ceramic, CoCr- and Ti-based alloys and HA-coatings is given on the basis of recognized and new insights. Advantages and disadvantages as well as prospectives (PE-disease, Ti wear, HA-resorption in vivo etc.) are discussed and documented with results from experimental and clinical experience. New surface hardening techniques for Ti-based alloys are mentioned. Experimental results and singular experience from clinical retrieval study of new plastics (PAEK, Triazin-resin) are presented. Composite materials as a basis for a new generation of isoelastic hip prosthesis stems are described at the end of this paper.

In a review of the recent literature after conservative treatment of the complete anterior cruciate ligament (acl) rupture good results were found in an average (av) of 56% (12-80%) of all cases. In comparison the conservative treatment of partial tears showed in 84% (60-100%) of all cases good results. 79% (32-100%) of the patients with complete acl ruptures and 90% (66-100%) of the cases with partial acl tears were able to continue their sportactivities. Secondary acl replacement or meniscussurgery were later necessary in 20% and 14% of the cases (av) with complete acl ruptures and in only 6% and 5% (av) of the cases with partial tears. Most of the patients who were operated later were young and ambitionsly engaged in sports. The results of the mostly retrospective studies display a high variability. For this reason it is necessary to perform more prospective, controlled and randomized studies to verify the preventive effect of an early operative treatment to protect the joint form osteoarthritis and progressive instability. Arthrocopy is essential for all cases of acute hemartrosis. Partial acl tears are predominantly treated conservatively, while complete acl ruptures should be treated following an individual decision regimen. A tree for decision making of the treatment of acute acl-injuries is proposed.

Aim: The purpose of this study was to survey and to evaluate the first clinical and radiological results with the cementless ZMR taper hip prosthesis. Method: The modular distal-tapered stem was designed with a roughened titanium surface and sharp splines to achieve secure distal fixation and rotational stability. 90ZMR taper hip prostheses were implanted between October 1999 and July 2002. Out of these, 4 interventions were primary and 86 were revision procedures. In 43 cases a complete hip prosthesis revision and in 43 cases a stem revision was necessary. The mean age of the 90 patients (42 males, 48 females) was 67.1 years. The mean follow-up period was 7.6 months (3 to 25 months). Results: The stem displayed an excellent distal fixation. The mean subsidence could be measured with 4.3 mm. Furthermore, most cases showed a particularly favourable remodelling of the proximal femoral bone stock. Complications associated with revision included intraoperatively 4 femur fractures, 3 femur fissures, 5 femur perforations, 2 trochanter fractures and postoperatively 19 dislocations, 5 superficial wound infections, 2 transient palsies, 1 pulmonary embolism, 1 stem rotation and 4 wound healing failures. Considering these complications 15 re-revisions were necessary and the ZMR taper hip prosthesis had to be exchanged in 3 cases. Conclusion: On the one hand the ZMR taper hip prosthesis proved its value, particularly with regard to the stem modularity, the excellent distal fixation in conjunction with the possibility of partial body weight bearing and the rapid bone remodelling of the femur. On the other hand an increased number of postoperative complications and re-revisions occurred. Further long-term studies seem to be essential.

Studienziel: Das Ziel dieser Studie war die Erhebung und die Bewertung der ersten klinischen und radiologischen Ergebnisse mit dem zementfreien ZMR-Taper-Revisionsschaft. Methode: Der modulare konische ZMR-Schaft ist mit einer aufgerauten Titanoberfläche sowie scharfen Finnen versehen, so dass eine gute distale Verankerung bei gleichzeitiger Rotationsstabilität erreicht werden kann. Im Untersuchungszeitraum von Oktober 1999 bis Juli 2002 wurde bei 90 Patienten der ZMR-Taper-Revisionsschaft implantiert. Hierbei handelte es sich um 4 Primärimplantationen und 86 Hüftendoprothesenwechsel. In 43 Fällen wurde ein kompletter Hüftendoprothesenwechsel und in 43 Fällen ein Schaftwechsel durchgeführt. Das Durchschnittsalter der 90 Patienten (42 Männer, 48 Frauen) betrug 67,1 Jahre. Der mittlere Nachuntersuchungszeitraum belief sich auf 7,6 Monate (3 bis 25 Monate). Ergebnisse: Der Schaft zeigte eine sehr gute distale Verklemmung, so dass ein durchschnittliches Einsinken von nur 4,3 mm vermessen werden konnte. Des Weiteren fand sich ein außerordentlich rasches Bone Remodelling des Femurs in nahezu allen Fällen. An intraoperativen Komplikationen waren 4 Femurfrakturen, 3 Femurfissuren, 5 Femurperforationen und 2 Trochanterfrakturen zu verzeichnen. Die postoperativen Komplikationen beschränkten sich auf 19 Luxationen, 5 oberflächige Infektionen, 2 passagere Paresen, 1 Lungenembolie, 1 Schaftrotation und 4 Wundheilungsstörungen. Bei den hierdurch bedingten 15 Revisionseingriffen wurden 3 ZMR-Schaftwechsel notwendig. Schlussfolgerung: Einerseits konnte der ZMR-Taper-Revisionsschaft durch seinen modularen Lösungsansatz, der guten distalen Verklemmung im Femur, der damit verbundenen Möglichkeit einer Teilbelastung des operierten Beines und der raschen Remodellierung des Femurs überzeugen. Andererseits traten vermehrt postoperative Komplikationen mit einer erhöhten Rerevisionsrate auf, so dass weitere längerfristige Studien notwendig erscheinen.

Storing autologous blood as whole blood (WB) has been proposed for increasing the cost-effectiveness of preoperative autologous blood donation programmes. However, experimental data suggest that autologous leucocytes might lead to immunomodulation similar to the effect attributed to allogeneic leucocytes.In a retrospective analysis, the postoperative outcome of 120 patients undergoing elective orthopaedic surgery and having donated up to two units of autologous WB (AWB) was compared with that of a control group of 52 patients, whose autologous donation had been processed into buffy coat-depleted red cell concentrates (RCC). At least one autologous unit, but no allogeneic units, had been transfused in all analysed patients.Donation schemes were equally efficacious in both groups. There was no significant difference in post-operative infection rates between the two groups. Overall rates were 7.7% in the RCC group and 8.3% in the WB group. Surgical, thromboembolic and other recorded complications, length of postoperative hospital stay and days of the use of antibiotics were also not significantly different between the two groups.The results of this study suggest that transfusion of up to two units of unmodified AWB is as efficacious as the transfusion of autologous RCC and does not negatively influence the postoperative outcome in elective orthopaedic surgery.

Tissue engineering is a promising tool for treating structural and functional defects in bone and cartilage. To provide optimal conditions for three-dimensional cell growth the use of a scaffold is necessary. The aim of the study was to test the potential application of an electrospun poly (I-lactide)-nanostructured scaffold as a matrix for tissue engineering. Matrices were seeded with human osteosarcoma MG-63 cells and cultivated for 14 days. Cells showed a clear preference for growth along the nanofibres, and demonstrated no signs of degeneration or apoptosis. The fine structure of electrospun nanofibres makes them an ideal scaffold for tissue engineering, in particular for cartilage repair. They can be "doped" with growth factors, medications, etc., and are both biocompatible and biodegradable.

Studienziel: Methode: Ergebnisse: Schlussfolgerung: Study goal: Methods: Results: Conclusion:

Zielsetzung: Eine Anzahl von Erkrankungen des menschlichen Hüftgelenkes geht mit einer Änderung des Drehzentrums der Hüfte einher. Bei operativen Eingriffen sollte dabei die anatomische Rekonstruktion des Drehzentrums besonderes Augenmerk verdienen. Dadurch können die biomechanischen Verhältnisse optimiert werden. Dies setzt voraus, dass die Lage des Drehzentrums bekannt ist. Es existieren verschiedene Methoden zur Bestimmung des Drehzentrums, jedoch sind bisher keinerlei Untersuchungen durchgeführt worden, ob das so ermittelte Drehzentrum tatsächlich dem anatomischen Drehzentrum entspricht.

The goal of this study was to compare the migration of noncemented diffusion sintered titanium fibermesh-coated tibial components with (HA group) and without (non-HA group) additional hydroxyapatite coating. For this purpose digital radiostereometry (DIRSA) was used to compare the migration after 2 and 9 years for the two groups. After 2 years the mean maximum subsidence of the HA-coated components (0.24+/-0.18 mm) was about one-half of the mean maximum subsidence of the non-HA-coated group (0.55+/-0.55 mm). After 9 years the maximum subsidence of the HA-coated components was still smaller, but not as pronounced as before. The same trend was also found for the endpoint maximum total point motion (MTPM). After 2 years the mean MTPM of the HA-coated components was 0.66+/-0.38 mm and of the non-HA group 0.73+/-0.50 mm. After 9 years the mean MTPM for the HA-coated components was 0.54+/-0.15 mm and for the non-HA-coated components 0.74+/-0.20 mm. None of the HA-coated tibial components but one of the non-HA group had to be revised and exchanged due to aseptic loosening.

AIMPeriprosthetic adaptive bone remodeling after total hip arthroplasty (THA) has been frequently simulated in computer models, combining bone remodeling theory with finite element analysis. Unfortunately, there is still a lack of clinical validation data. The collection of prospective volumetric bone density data with a clinical computerized tomography study after THA was previously conducted. The objective of the study presented here is an additional evaluation of femoral strain.METHODIn a prospective clinical trial with 7 female patients after THA computerized tomography (CT) and finite element (FE) modeling was patient specifically combined immediately after surgery, as well as at three and 24 months postoperatively. Mechanical strain was expressed by strain energy density.RESULTSCorresponding to a bone density decrease, a decrease of the femoral strain energy density was observed during the two year follow-up after surgery (approximately 20 %). The predominant change occurred within the first three months and was found to be distally stronger than proximally.CONCLUSIONAs far as we are aware, this is the first combination of fully prospective 3D CT density data in vivo with patient-specific finite element modeling. The assessment of mechanical strain data during a follow-up trial should be a new approach for analyzing hip stems in clinical biomechanics. A future confirmative study based on a statistical case number calculation would increase the evidence of the results presented here.

Fragestellung: Bestimmung der Migration zementfreier Tibiakomponenten (diffusionsgesintertes Titanfasernetz, Miller-Galante II) mit (HA-Gruppe) und ohne (NonHA-Gruppe) zusätzlicher Hydroxylapatitbeschichtung mittels digitaler Radiostereometrieanalyse.

STUDY GOAL:In September 2002 the Federal Ministry of Health (BMG) has passed a decree in respect to the diagnosis related group system (G-DRG) for German hospitals (KFPV). From 2003 on the basis of this decree German hospitals were offered for the first time to use the G-DRG system optionally according to the " Section 17b Abs.4 of the Hospital Financing Law (Krankenhausfinanzierungsgesetz-KHG)". In addition the preliminary calculation data for the German DRG-System were published. The goal of this study was to compare the development of the cost weights and the average lengths of hospital stay in Australian teaching hospitals between 1998 and 2001 with the cost weights and average lengths of hospital stay in German hospitals according to the data published in the first German calculation (G-DRG V1.0).METHODS:An analysis was performed using the publically accessible reports on the national hospital cost data collections from 1998 until 2001 as they were published by the Commonwealth Department of Health and Aged Care in Australia. These data were compared with the cost weight calculation and average lengths of hospital stay calculation of the Institute for the Assessment of Cost Weights (InEK GmbH) published in the G-DRG V1.0 version.RESULTS:From 1998 until 2001 the cost weights of medical procedures such as spine fusion operations and joint arthroplasty revision operations on the hip and on the knee with severe complications and co-morbidities increased continuously. This development was not seen in DRG's without complications and co-morbidities, in food and ankle procedures and in shoulder procedures. The average length of hospital stay decreased continuously with very few exceptions. The average length of stay for so called C-DRG's (I09, I12, I13, I68, I69, I71, I75, I76) and in particular so called Z-DRG's (I16-I27) are in general longer by a factor of at least 2 in German hospitals when compared to Australian hospitals.CONCLUSION:A high quality of right-coding of ICD and ICPM Codes is a prerequisite to reach the correct revenue-relevant DRG. In Germany the average length of hospital stay is significantly longer than in Australia. In general the MDC-8-DRG's have demonstrated a smaller range when compared with the first calculated German DRG's in respect to the complexity of the procedures. Future management of the expected reductions in hospital stay will be based on a continuous co-operative efforts to improve the structural-, process- and (clinical guidelines and clinical pathways) and outcome quality of our medical procedures. The central objective of this effort is the well-being of our patients.

BACKGROUND:We retrospectively compared the influence of surface finish with respect to the long-term durability of a cemented titanium alloy stem of the same design but different surface finish.METHODS:From 1984 to 1994, the stem was made of a titanium-aluminum-vanadium alloy. A total of 201 patients with 220 smooth stems (mean follow-up 11 years and 4 months) out of 612 implanted between 1984 and 1987 and 319 patients with 343 rough stems (mean follow-up 5 years and 10 months) out of 812 implanted between 1991 and 1993 could be reviewed clinically and radiologically for comparison. The average age of the patients with the smooth stem was 58.1 years and of the patients with the rough stem, 62.2 years. In both groups, 35% of patients were male and 65% female.RESULTS:The mean Merle d'Aubigné hip score increased from 10.5 to 16.0 points in the smooth stem group and from 11.0 to 16.9 points in the rough stem group. The distribution of radiolucent lines, according to the zones of Gruen, was similar in both groups. The smooth stem required revision in 18 cases after a mean follow-up of 11 years and 4 months and the rough stem in 30 cases after a mean follow-up of 5 years and 10 months. The survival analysis (Kaplan-Meier) revealed 95.4% survival after 13 years for the smooth femoral component and 76.7% survival after 8 years for the rough femoral component.CONCLUSIONS:The implantation of titanium alloy stems with a rough surface finish cannot be recommended because of its high aseptic loosening rate.

AIM:Periprosthetic adaptive bone remodeling after total hip arthroplasty (THA) has been frequently simulated in computer models, combining bone remodeling theory with finite element analysis. Unfortunately, there is still a lack of clinical validation data. The collection of prospective volumetric bone density data with a clinical computerized tomography study after THA was previously conducted. The objective of the study presented here is an additional evaluation of femoral strain.METHOD:In a prospective clinical trial with 7 female patients after THA computerized tomography (CT) and finite element (FE) modeling was patient specifically combined immediately after surgery, as well as at three and 24 months postoperatively. Mechanical strain was expressed by strain energy density.RESULTS:Corresponding to a bone density decrease, a decrease of the femoral strain energy density was observed during the two year follow-up after surgery (approximately 20 %). The predominant change occurred within the first three months and was found to be distally stronger than proximally.CONCLUSION:As far as we are aware, this is the first combination of fully prospective 3D CT density data in vivo with patient-specific finite element modeling. The assessment of mechanical strain data during a follow-up trial should be a new approach for analyzing hip stems in clinical biomechanics. A future confirmative study based on a statistical case number calculation would increase the evidence of the results presented here.

INTRODUCTION: Conventional wisdom dictates that fusion rates increase with increasing construct stiffness. Traditional pedicle screw systems generally rely upon stiff components and rigid interconnections. For ease of insertion, some "semi-rigid" systems include polyaxial connections. A favorable bio logical outcome (fusion) is only weakly related to instrumentation type and it is increasingly recognized that even semi-rigid instrumentation may be too stiff [1]. Dynesys (Dynamic Neutralization System for the Spine, Centerpulse Spine-Tech, Inc., Minneapolis, MN) has non-rigid interconnections, non-rigid polymer spacers, and pedicle screw anchorage. The biomechanics of more traditional polyaxial pedicle screw/rigid rod fixation (Silhouette ) compared to this non-rigid system are unknown. It was hypothesized that spines fixed with the non-rigid stabilization system will exhibit greater ranges of motion (ROM) than spines fixed with the all-metal semi-rigid pedicle screw system. METHODS: Twelve fresh -frozen calf lumbar spines were used. Soft tissues were removed but the discs and ligaments were left intact. Structures above L1 and below L5 were removed. Spines were kept moist and were maintained at 35-41 °C (body temperature) throughout testing. Intact spines were tested in flexion, extension, left/ right lateral bending, and left/right axial rotation. Instrumentation was applied at L3/L4 using the manufacturers’ recommended techniques and instruments. For non-rigid (Dynesys) stabilization, the facet joints were cut open. For semi-rigid (Silhouette) fixation, the facet joints were decorticated with a high speed burr and rongeurs. (This variation was necessary to accomodate geometric differences between the instrumentation types.) Spines were destabilized at the reconstructed level by creating a window in the annulus and by cutting the supraspinous, interspinous, and posterior longitudinal ligaments, and the ligamentum flavum. Six spines received non-rigid stabilization and six spines received semi-rigid fixation. Instrumented spines were retested in flexion, extension, left/right lateral bending, and left/right axial rotation. A biaxial load frame was configured with two rotary actuators with integral rotary poteniometers mounted onto glide tables. This configuration created a six degree-of-freedom spine testing machine: the rotary actuators coincided with flexion/extension and lateral bending, the glide tables coincided with anterior/posterior and medial/lateral translations, and the biaxial actuator coincided with axial rotation and axial translation of the spine. Flexion-extension, axial rotation, and lateral bending moments were applied in 1.5Nm intervals up to +/-6Nm in each direction with no axial pre-load. Position data were recorded upon a third loading cycle after two preconditioning cycles. Relative intervertebral motions were recorded by a optoelectronic position measurement system (Optotrak 3020, Northern Digital Inc., Waterloo, Ontario, Canada). Ranges of motion were derived from the momentangular displacement curves. For instrumented spines, ROM's were normalized to intact and reported. In general, groups were compared by a t -test. A significance level of p<0.05 was chosen. RESULTS SECTION: In axial rotation, flexion/extension and lateral bending, spines with non-rigid stabilization were not significantly different from spines with semi-rigid fixation. In axial rotation, neither was significantly different from intact. However, in flexion/extension and lateral bending, both were significantly different from intact. Table. Range of Motion (Percent of Intact, mean ± 1 s.d.) L/R Axial Rotation Flexion/ Extension L/R Lateral Bending Non-Rigid Fixation 125 ± 50 54 ± 12 10 ± 4 Semi-Rigid Fixation 125 ± 47 40 ± 29 13 ± 7 DISCUSSION: Both constructs substantially reduced flexion/extension and lateral bending motion but the constructs were not different from each other. Consequently, neither fixation system was superior in terms of reducing flexion/extension and lateral bending. In axial rotation, neither Dynesys nor Silhouette was different from its intact condition and the constructs were not different from each other. Neither construct substantially affected axial rotation motion. Our findings are limited to single-level, bilateral constructs; no differences between non-rigid stabilization (Dynesys) and semi-rigid fixation (Silhouette) were notable. Multi-level or unilateral constructs may likewise exhibit no differences between instrumentation types, but these variables were not included in this study. Another limitation is that calf lumbar spines were tested in this study. Wilke has found that calf and human spines are biomechanically similar and that the calf spine is an appropriate model for the human spine in vitro test s [2]. Our tests were further limited in that the spines were fresh -frozen and the spines were normal without obvious anatomic defects or disease. These limitations are accepted for all in-vitro tests. No axial preload was applied though axial preload has been shown to have an important effect when examining natural spine kinematics [3]. The best axial preload for in-vitro comparisons of posterior fixation systems remains to be demonstrated. It has been recommended by other investigators than care be taken to guarantee that any preload be consistently applied throughout testing [4]; our methodology ensured this. The constructs model fixation only immediately post-operatively and without bone graft. The effects of time of implantation may be important in several ways. First, ranges of motion and stiffness may be affected by repeated loading in -situ; in this study, a nominal number of load cycles were applied. Second, the material properties of the bone or of the implants may change with time in-situ; these changes could not be modeled. Third, successful fixation should lead to the development of a fusion mass in -situ; the biomechanical consequences of the presence of a fusion mass were not studied. Contrary to the hypothesis, non-rigid stabilization and semi-rigid fixation presented equivalent ranges of motion in axial rotation, flexion/extension, and lateral bending. Both the non-rigid stabilization system and the semi-rigid fixation system provided acute stability. REFERENCES: 1. Pfeiffer M, Deike B, Clausen JD, Wilke A, Griss P: A new semirigid implant for instrumentation of scoliosis: preliminary report. Eur Spine J 2001 Oct;10(5):427-36 2. Wilke HJ, Krischak ST, Wenger KH, Claes LE: Load-displacement properties of the thoracolumbar calf spine: experimental results and comparison to known human data. Eur Spine J 1997;6(2):129-37 3. Janevic J, Ashton-Miller JA, Schultz AB: Large compressive preloads decrease lumbar motion segment flexibility. J Orthop Res 1991 Mar;9(2):228-36 4. Cripton PA, Bruehlm ann SB, Orr TE, Oxland TR, Nolte LP: In vitro axial preload application during spine flexibility testing: towards reduced apparatus-related artefacts. J Biomech 2000 Dec;33(12):155968 Figure. Range of Motion Results 0 50 100 150 200 L/R Axial Rot Flex/Ext L/R Lat Bend P er ce nt o f I nt ac t Non-Rigid Stabilization