Fritz U. Niethard

Diagnostic and therapeutic management of lumbar and thoracic spondylodiscitis – an evaluation of 59 cases

Abstract Fifty-nine patients with spondylodiscitis (SD) of the thoracic and/or lumbar spine were followed-up clinically and radiologically [X-ray, computed tomography (CT), magnetic resonance imaging (MRI)] over a mean time of 2.2 years (1–6.5 years). All patients without abscess formation (n = 35) were treated conservatively. Out of the group with abscess formation (n = 24) 6 patients were also treated conservatively, 11 were drained under CT control and 7 were operated. At time of diagnosis, “signs of florid inflammation” were seen in 60% of the roentgenograms, in 93% of the CTs and in all of the MRIs. The sensitivity to differentiate between SD with and without abscess formation was 85% by MRI and 69% by CT. “Signs of regressive inflammation” and “signs of increasing osseous consolidation”, essential facts for starting remobilization, could first be seen using CT 6 weeks after onset of therapy. Using MRI these signs were seen with a considerable delay at 12 weeks. Clinically, only 3 of the 59 analyzed patients developed recurrent SD. In conclusion, MRI is the radiological method of choice for establishing the diagnosis of SD, in particular with regard to differentiating between cases with and without abscess formations. In contrast, CT is superior for performing success control after treatment. Therapeutically, conservative, minimal-invasive and operative procedures are not rival but rather complementary.

Surface pretreatments for medical application of adhesion

Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone.The purpose of this contribution is to describe developments carried out to optimize the techniques , connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity.Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding.Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m).This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body.

Intravertebral pressure during vertebroplasty and balloon kyphoplasty: an in vitro study.

Study Design. Intravertebral pressure (IP) measurements were conducted on human cadaveric lumbar spines in a biomechanical study. Objective. To assess the pressure that is generated in the center of the vertebral body during the cement fill in vertebroplasty (VP) and balloon kyphoplasty (BKP). Summary of Background Data. High IP during polymethylmethacrylate (PMMA) injection have frequently been raised as a reason for the higher cement leakage rate during VP in contrast to BKP. The IP recorded in the periphery of the vertebral body is much lower than the injection syringe pressure. The pressure ratios in the central region of the vertebrae close to the injection cannula are not known. Methods. VP and BKP were performed in 8 lumbar cadaveric spines. A pressure sensor was placed in the center of the vertebral body. In the VP subgroup a total volume of 6 mL of polymethylmethacrylate cement was delivered in 1.5 mL increments. In the BKP subgroup balloon dilation up to a volume of 4 mL was made before cement injection of 6 mL (1.5 mL increments). Room temperature, cement mixing time, and constant volume flow during cement injection were recorded. Results. During the administration of the first 1.5 mL of bone cement the average IP for VP was 18.5 versus 1.2 kPa for BKP. For the second filling an average pressure of 34.9 kPa (VP) and 3.4 kPa (BKP) was recorded. The average IP during the third injection was 53.0 kPa (VP) and 14.8 kPa (BKP). The pressure of the last 1.5 mL averaged in 56.6 kPa (VP) and 25.5 kPa (BKP). Conclusion. The IP measured during cement augmentation in cadaveric spines was lower in BKP than in VP. In the BKP group a relative increase of the IP was registered at the end state of cement delivery when the cavity was overfilled.

Madelung deformity: clinical features, therapy and results.

In a retrospective study, 31 patients with Madelung deformity were reviewed. They were treated at one institution during a period of 15 years. On first presentation, the mean age was 22.5 years with a range from 10 years to 64 years. Twenty-four patients (77%) were female. The main complaints were pain, limited range of motion, and objectionable appearance. A family history of Madelung deformity was present in four patients (13%). The diagnosis of Leri-Weill syndrome could not be confirmed in any case. There was no correlation between the clinical appearance and the extent of radiologic abnormality. Five patients (16%) were operated on because of permanent pain. On postoperative examination, only one patient revealed no restricted range of mobility and no pain, whereas the other four patients improved in terms of pain but showed only limited improvement of function. The vast majority of patients, however, required no surgical therapy.

Die konservative Therapie der angeborenen Hüftdysplasie und -luxation

ZusammenfassungDie Hüftdysplasie und -luxation gehören trotz Einführung des sonographischen Neugeborenenscreenings nach wie vor zu den häufigsten angeborenen Erkrankungen der Bewegungsorgane.Bei übermäßiger oder forcierter Therapie dieser Hüftgelenke besteht die Gefahr der Hüftkopfnekrose, bei nicht ausreichender Therapie können Restdysplasien resultieren, sodass im späteren Verlauf weitere Maßnahmen notwendig sind.Daher ist die differenzierte und stadienangepasste Behandlung der Hüftdysplasie, die erst nach Abschluss des Hüftwachstums beendet ist,Ziel aller therapeutischen Maßnahmen.Unabdingbare Voraussetzung ist jedoch eine korrekte und frühzeitige Diagnose.AbstractDespite general ultrasound screening of the newborn,congenital dysplasia and dislocation of the hip are still among the most common congenital skeletal diseases.A differentiated and stage-adjusted therapy must be the aim because inadequate therapy can lead to necrosis of the femoral head or a residual dysplasia that both require further treatment.Now as before a correct and early diagnosis is absolutely necessary for the treatment of dysplasia of the hip.A once treated hip should be observed until completion of growth.

Correction of kyphotic deformity before and after transection of the anterior longitudinal ligament--a cadaver study.

Abstract With a custom-made measuring unit, two separate experiments, involving six and five cadaveric torsos with intact rib cages and sternums, respectively, were carried out to determine the effect of the transection of the anterior longitudinal ligament with and without osteodiscectomy and its influence on the thoracic kyphosis. The open or thoracoscopically assisted anterior release, as part of the operative treatment of scoliosis or kyphosis, usually consists of a transection of the anterior longitudinal ligament (ALL) and an additional discectomy. A complete osteodiscectomy, however, is not always possible with a minimally invasive approach. As part of our biomechanical research, we attempted to quantify the amount of correction achievable with a defined force prior to and following the isolated transection of the anterior longitudinal ligament. The aim of the study was to clarify whether or not an isolated transection of the anterior longitudinal ligament is sufficient to obtain an adequate anterior release of the spine. In the surgical treatment of kyphotic deformities, anterior release of the spine is performed in the form of a transection of the ALL and discectomy. Recently, video-assisted thoracic surgery has become increasingly popular in spine surgery. As part of this change in surgical technique, the question has arisen as to what extent an isolated transection of the ALL provides an adequate release of the thoracic spine. Eleven human spines were retrieved from fresh cadavers, dissected, and attached to a specially constructed apparatus. The spine was attached to the construct at the twelfth vertebral body. C6 and C7 were fixed in synthetic resin. We installed the instruments in such a manner as to reproducibly apply a torsional moment of 10 Nm to the spine. Motion was only permitted in the sagittal plane. Segmental transections of the ALL were carried out from T3 to T7. For comparison, the sagittal Cobb angle was also documented following an anterior release combined with an osteodiscectomy. With the isolated transection of the ALL, an average correction of the sagittal Cobb angle of 4° in each functional spinal motion segment was recorded. In comparison, the additional osteodiscectomy led to a further average increase of only 2° per level. The measurements performed on human cadavers showed that the isolated transection of the ALL leads to a sufficient anterior release of the thoracic spine, allowing a correction of the kyphotic deformity. The release with a concomitant osteodiscectomy represents a more time-consuming and more invasive procedure resulting in only a slightly greater amelioration of the sagittal Cobb angle, while being associated with a greater patient morbidity.

Improvement of the long‐term adhesive strength between metal stem and polymethylmethacrylate bone cement by a silica/silane interlayer system

A loss of adhesive strength between metal stem and bone cement is clinically found to be a serious problem in total hip arthroplasty and causes many operative revisions. The objective of this study was to improve the long-term adhesive strength at this interface. A new silica/silane interlayer coating system is introduced. The layers are designed to bond the metal stem surface to the polymethylmethacrylate bone cement marginally leakage free. In vitro tensile tests were performed on specimens of TiAl6V4 and CoCrMo that were cemented by pairs with different bone cements with and without the new coating system. The specimens were stored in isotonic saline solution up to 150 days. The adhesive strength decreased about 75% within 30 days of storage on specimens of both metal alloys that were conventionally cemented without the new interlayer system. With the new coating, the high initial adhesive strength (40-50 MPa) could be stabilized for TiAl6V4 over 150 days. For the same 150-day storage period, the adhesive strength of the coated CoCrMo alloy still decreased but the decrease was only half that experienced by the uncoated CoCrMo. The loss of adhesive strength on CoCrMo specimens could be reduced if the metal surface was activated by a plasma treatment. The new coating interface system could help to considerably reduce revision operations caused by debonding effects at the interface metal/polymethylmethacrylate bone cement.

Delegation ärztlicher Leistungen

ZusammenfassungEine Delegation ärztlicher Leistungen und Verantwortung an nichtärztliches Personal wird besonders von der Politik zunehmend gefordert. Dargestellt wird die Stellungnahme der Union Orthopädie und Unfallchirurgie. Tätigkeiten, die unter Arztvorbehalt stehen, werden einem möglichen, differenzierten Delegationsspektrum gegenüber gestellt. In erster Linie müssen Ärzte von nichtärztlichen Tätigkeiten entlastet werden. Eine potentielle Delegation einzelner ärztlicher Leistungen darf nicht das Arztbild und die Versorgungsqualität der Patienten beeinträchtigen. Chancen und Risiken einer Delegation ärztlicher Tätigkeiten werden bewertet.AbstractDelegation of medical treatment and responsibility from doctors to nonphysicians are being advocated more and more by public health politicians. The opinion of the German Union of Orthopaedic and Trauma Surgery is outlined. Definitions for treatment areas that cannot or may be delegated are presented. Physicians must be spared from overloading of administrative work. Delegating must not result in deterioration of patient care or destruction of the medical profession. Options and risks of delegation are discussed.Delegation of medical treatment and responsibility from doctors to nonphysicians are being advocated more and more by public health politicians. The opinion of the German Union of Orthopaedic and Trauma Surgery is outlined. Definitions for treatment areas that cannot or may be delegated are presented. Physicians must be spared from overloading of administrative work. Delegating must not result in deterioration of patient care or destruction of the medical profession. Options and risks of delegation are discussed.

Knochen und Gelenke

Storungen der Skelettentwicklung aufgrund konstitutioneller Systemerkrankungen konnen zu schweren Deformierungen und Kleinwuchs fuhren. Betroffene, durch ihre Erkrankung behinderte Menschen, konnen jedoch mit hoher Intelligenz und vielseitigen Begabungen ausgezeichnet sein. So war Francois Cuvillies d. Altere, als Hofbaumeister in Munchen der Schopfer formvollendeter Bauwerke des Rokkoko wie des Residenztheaters und der Amalienburg, hochgradig kleinwuchsig, wahrscheinlich aufgrund einer Achrondoplasie («Kammerzwerg»). Der zugrundeliegende Gendefekt bei Achondroplasie wurde inzwischen auf dem kurzen Arm des Chromosoms 4 (4p 16) lokalisiert.

Surface pretreatment for prolonged survival of cemented tibial prosthesis components: full- vs. surface-cementation technique

BackgroundOne of few persisting problems of cemented total knee arthroplasty (TKA) is aseptic loosening of tibial component due to degradation of the interface between bone cement and metallic tibial shaft component, particularly for surface cemented tibial components. Surface cementation technique has important clinical meaning in case of revision and for avoidance of stress shielding. Degradation of the interface between bone cement and bone may be a secondary effect due to excessive crack formation in bone cement starting at the opposite metallic surface.MethodsThis study was done to prove crack formation in the bone cement near the metallic surface when this is not coated. We propose a newly developed coating process by PVD layering with SiOx to avoid that crack formation in the bone cement. A biomechanical model for vibration fatigue test was done to simulate the physiological and biomechanical conditions of the human knee joint and to prove excessive crack formation.ResultsIt was found that coated tibial components showed a highly significant reduction of cement cracking near the interface metal/bone cement (p < 0.01) and a significant reduction of gap formation in the interface metal-to-bone cement (p < 0.05).ConclusionCoating dramatically reduces hydrolytic- and stress-related crack formation at the prosthesis interface metal/bone cement. This leads to a more homogenous load transfer into the cement mantle which should reduce the frequency of loosening in the interfaces metal/bone cement/bone. With surface coating of the tibial component it should become possible that surface cemented TKAs reveal similar loosening rates as TKAs both surface and stem cemented. This would be an important clinical advantage since it is believed that surface cementing reduces metaphyseal bone loss in case of revision and stress shielding for better bone health.