Wolfgang Linhart

Biologically and chemically optimized composites of carbonated apatite and polyglycolide as bone substitution materials.

We report on the development and characterization of a new composite material consisting of amorphous carbonated apatite, Ca(5)(PO(4), CO(3))(3)(OH), and microstructured poly(hydroxyacetic acid), polyglycolide (PGA). This material is able to keep the pH of a surrounding solution within the physiological range (7.2-7.6). This was achieved by chemical fine-tuning of the counterplay between the acidic degradation of the polyester and the basic dissolution of calcium phosphate. Microporous samples with pore sizes of <1 microm and compact samples were prepared. The biological behavior was assayed in vitro by long-term osteoblast culture. Morphological and biochemical analyses of cell differentiation revealed excellent biocompatibility, leading to cell attachment, collagen and osteocalcin expression, and mineral deposition. This material could be of use as a biodegradable bone substitution material and as a scaffold for tissue engineering.

Einheilung autogener Transplantate nach dorsoventraler Instrumentierung instabiler Frakturen der thorakolumbalen Wirbelsäule

ZusammenfassungFragestellung. In der operativen Versorgung instabiler Frakturen des thorakolumbalen Überganges besteht Unklarheit darüber,mit welchem Verfahren die besten Ergebnisse erzielt werden können.Aufgrund der höheren mechanischen Stabilität scheint sich gegenwärtig die kombinierte dorsoventrale Stabilisierung durchzusetzen.Für das kombinierte Verfahren sind bislang trotz erster Langzeituntersuchungen keine aussagekräftigen Daten zur Einheilung autogener Transplantate verfügbar.Zielsetzung dieser Untersuchung war es, die Integration autogener Transplantate und die lokalen Komplikationen an der Entnahmestelle zu evaluieren. Methodik. Um die knöcherne Fusionsrate zu untersuchen,wurden aus einer konsekutiven Serie 30 Patienten mit traumatischen Frakturen des thorakolumbalen Überganges selektiert und in eine prospektive klinische Verlaufsstudie eingeschlossen. Nach dorsaler Stabilisierung mit einem Fixateur interne (USS, Synthes) erfolgte die Instrumentierung der ventralen Säule durch Verwendung eines autogenen trikortikalen Beckenkammspans und zusätzliche Osteosynthese (MACS,Aesculap; VentroFix, Synthes). Die knöcherne Fusion wurde computertomographisch vor der Entfernung des dorsalen Implantates (t=12±2,4 Monate) untersucht. Ergebnisse. Die Analyse der ca.1 Jahr postoperativ durchgeführten Computertomographien erbrachte den Nachweis einer vollständigen knöchernen Integration der Transplantate in 77% (23/30). Klinisch mussten lokale Beschwerden an der Entnahmestelle in 37% (11/30) der Fälle hingenommen werden. Schlussfolgerungen. Diese Daten verdeutlichen, dass eine vollständige Fusion der vorderen Säule unter Verwendung autogener Beckenkammspäne keineswegs in allen Fällen erwartet werden kann und mit einer relativ hohen Rate lokaler Komplikationen an der Entnahmestelle gerechnet werden muss. Vor diesem Hintergrund werden alternative Verfahren wie der Einsatz von Cages zunehmend an Bedeutung gewinnen.AbstractObjective. It is widely believed that combined dorso-ventral stabilization provides superior mechanic stability in the operative treatment of thoracolumbar spine fractures. Currently there are no data available reflecting the fusion rates in trauma patients following the combined procedure. Aim of this investigation was to study the fusion rates following dorso-ventral stabilization of thoracolumbar spine fractures and the rates of local complications at the donor site. Methods. In order to assess fusion and complication rates 30 patients with unstable fractures of the thoracolumbar spine were selected from a consecutive series and investigated in a prospective study.After posterior stabilization with a fixateur interne (USS, Synthes) anterior arthrodesis was performed subsequently by autogenous iliac bone grafting in combination with an osteosynthesis (MACS,Aesculap;VentroFix, Synthes). The osseous integration of the autogenous transplants was measured by CT-scan 12±2.4 months after surgery. Results. The evaluation of the radiographic and CT data revealed a fusion rate of 77% (23/30) one year after surgery.These findings were accompanied by minor complications at the donor site in 37% (11/30). Conclusion. Our experiences with autogenous spine grafting gave evidence that a reliable osseus integration can not be expected in all of the cases.Furthermore one has to consider a high rate of local complications. Therefore alternative procedures such as the use of cages will be of increasing influence in the surgical treatment of thoracolumbar spine fractures.

Gait improvement surgery in diplegic children: how long do the improvements last?

Gait improvement surgery in ambulatory children with cerebral palsy performed as single-event multilevel surgery is today a well-established modality of treatment, but follow-up studies are lacking. Preoperative and follow-up gait analysis data of 32 diplegic children who underwent single-event multilevel surgery for gait improvement between 1995 and 1998 were evaluated retrospectively. Relevant sagittal plane kinematic parameters of the hip, knee, and ankle joint and time-distance parameters were considered for outcome measures in this study. Postoperative gait analysis was performed three times in all the cases: after discontinuation of the dynamic AFOs (mean 1.0 ± 0.3 years), after discontinuation of the night splints (mean 2.3 ± 0.7 years), and at least 1.5 years after discontinuation of physiotherapy and splints (mean 4.4 ± 1.1 years). The aim of the study was to ascertain whether the improvements in gait function were maintained over these examinations. The authors found that gait function continued to change over 1, 2, and 3 years of follow-up. A general decrease in gait function was measurable in this collective between the first postoperative and the second postoperative evaluations. The results indicate that evaluation of gait improvement surgery in cerebral palsy performed at a minimum of 3 years after surgery would give the most predictive outcome of treatment.

Pitfalls and complications in the use of the proximal femoral nail

Background and aimsOsteosynthesis with the proximal femoral nail (PFN) features the advantages of high rotational stability of the head–neck fragment, an unreamed implantation technique and the possibility of static or dynamic distal locking. However, the use of the nail is technically ambitious and is accompanied by some risks of error, which can lead to failure of the osteosynthesis. In this paper we present the results of a critical analysis of mistakes that were made in our hospital during the introduction period of this implant.Patients and methodsWe carried out a prospective analysis of the data of 121 consecutive patients who were suffering from trochanteric or subtrochanteric fracture between December 1997 and December 2000 and who had been treated with a PFN.ResultsWe identified intraoperative technical difficulties in 23 patients (19.1%). Seven cases showed postoperative local complications that required operative revision on six patients (4.9%). The main reasons for the failure of the operations involved were poor reduction and wrong choice of screws. Following our critical analysis, we were able to avoid those problems.ConclusionsWhen 31A fractures are to be stabilised with a PFN, the precise technical performance of the implantation represents the basic surgical requirement. Already present minor deviations will subsequently cause loosening of the implants and failure of the operation.

Increased plasma kynurenine values and kynurenine-tryptophan ratios after major trauma are early indicators for the development of sepsis.

Kynurenine, the major degradation product of tryptophan has been shown to directly damage tissues, but its possible contribution to posttraumatic morbidity is unknown. Here, we studied the kinetics of kynurenine in patients after major trauma and whether this correlates with the development of posttraumatic sepsis. Kynurenine and tryptophan levels of 60 multiple-injured patients with Injury Severity Score of more than 16 were quantified prospectively by high-performance liquid chromatography. Blood samples were obtained daily from admission until day 10 after admission. Significantly increased kynurenine values were detectable already at day 1 after admission in blood from patients who later developed sepsis, regardless of injury pattern (P < 0.01). In contrast, kynurenine values of nonsepsis patients remained low throughout the observation period. However, all patients exhibited significantly decreased tryptophan values versus healthy controls (P < 0.01). Moreover, significantly increased kynurenine-tryptophan ratios rapidly predicted subsequent sepsis, multiple organ failure, and death (P < 0.01). Both increased kynurenine values and kynurenine-tryptophan ratios predicted posttraumatic development of sepsis and organ failure. This ought to be validated in subsequent studies.

Langzeitergebnisse nach Anwendung einer porösen Hydroxylapatitkeramik (Endobon) zur operativen Versorgung von Tibiakopffrakturen

ZusammenfassungEndobon, eine poröse Hydroxylapatitkeramik bovinen Ursprungs, ist seit 1989 als Knochenersatzmittel zur Therapie von Knochendefekten zugelassen. In der Literatur sind gegenwärtig keine Langzeitdaten zur klinischen Anwendung von Endobon verfügbar.Um die Langzeiteffekte von Endobon zu evaluieren, wurden im Rahmen einer retrospektiven Studie 35 Patienten mit Tibiakopffrakturen untersucht, die von 1992–1997 in unserer Klinik behandelt wurden. Nach Anhebung und Rekonstruktion der Gelenkfläche wurden die metaphysären Defekte mit Endobon gefüllt und die Frakturen durch Plattenosteosynthese stabilisiert. Von den eingeschlossenen Patienten konnten im Januar 2000 insgesamt 26 zu einer Nachuntersuchung einbestellt werden. Ein mechanisches Versagen der implantierten Keramiken mit sekundärem Korrekturverlust wurde nicht beobachtet. Einzelne Biopsate zeigten, dass das eingebrachte Material nach 18 Monaten vollständig ossär integriert wurde. Radiologische Anzeichen für eine Auslockerung, Dislokation, Sinterung oder Fraktur der Keramiken wurden auch nach Entfernung des Osteosynthesematerials nicht gesehen.Diese Daten zeigen, dass Endobon im Langzeitverlauf mechanisch stabil ist und bei entsprechender Indikation eine gute Alternative zur autogenen Spongiosaplastik darstellt.AbstractEndobon is a porous hydroxyapatite ceramic which has been used as a bone replacement substitute since 1989. Currently there are no data available reflecting long-term effects of Endobon in human bone grafting.In order to assess such effects 35 patients with fractures of the proximal tibia were studied retrospectively over a period up to 91 months. The metaphyseal defects were filled by Endobon and fractures were stabilized by internal plate fixation subsequently. A secondary loss of reduction due to mechanical failure of the bone replacement material did not occur even after removal of metal implants. No histological signs of resorption or degradation could be found 18 months after application.Our data show that Endobon provides good mechanical properties during a long term follow-up and can be recommended as a suitable therapeutic option versus cancellous bone graft.

Antegrade nailing of humeral head fractures with captured interlocking screws.

Objectives/Design: To assess the functional outcome after treatment of proximal humeral fractures with a new antegrade nail that provides angular and sliding stability. Intervention/Patients: Ninety-seven patients were treated during a 4-year period between April 2000 and March 2004. All patients were followed for 6 months, 51 patients (53%) for 12 months, and 31 patients (32%) for 24 months. This study focuses mainly on the patients with a follow up of 1 year. Their mean age was 68 years (range: 33 to 90); 22% were more than 80 years of age. Main Outcome Measurements: All fractures were radiologically graded by the Neer and AO/ASIF classifications. Clinical assessment was performed at all follow-up visits using the Constant-Murley and Neer scores, and complications were recorded. Results: There were 26.8% 2-part, 66% 3-part, and 7.2% 4-part fractures. The relative Constant-Murley score improved significantly (P < 0.001) from 72% at 6 months to 82% at 12 months after operation. No further improvement regarding functional outcome was observed after 24 months. Patients younger than 60 years of age had better results. No significant functional differences were found among 2-, 3- or 4-part fractures. Complications included backing out of the proximal screws (9.8%), secondary dislocation (1.9%), complete osteonecrosis (1.9%), and partial osteonecrosis (5.8%). Conclusion: Treatment with this nail provides sufficient fixation of the fragments to allow early mobilization. The good functional results in the majority of the patients indicate that this nail can be used, even in complex fractures and elderly patients.

Computer-assisted screw insertion into the first sacral vertebra using a three-dimensional image intensifier: results of a controlled experimental investigation

Currently there are few data available regarding the application and efficacy of computer-assisted procedures in the sacral spine. In order to optimize and standardize this procedure, a controlled experimental investigation has been performed. The aim of the study is to systematically assess the efficacy of a novel three-dimensional image intensifier used for navigated transiliac screw insertion into the first sacral vertebra. Screws were inserted iliosacrally into the first sacral vertebra of preserved human cadaver specimens. The instrument navigated procedure was performed with the “Siremobil Iso-C3D ” (Siemens Medical Solutions) and the “Navigation System” by Stryker. The accuracy and quality of the imaging procedure as well as the fluoroscopic exposure times were measured. These results were compared to three control groups (CT-based navigation, C-arm navigation, and fluoroscopic guidance). In each group a total amount of 20 screws was implanted. Screw position was postoperatively assessed by Iso-C3D or CT-scan. The navigated procedure using the Iso-C3D provided good feasibility characteristics without requiring a specific matching process. It revealed the shortest procedure time of all navigated procedures and significantly decreased fluoroscopic time compared to C-arm navigation and fluoroscopic guidance. Furthermore, Iso-C3D navigation showed no screw malposition and was in this regard superior to C-arm navigated and fluoroscopic guided procedures. The quality of imaging was sufficient for accurate placement, but did not share the high-resolution level of CT-based navigation. These findings indicate that application of the Iso-C3D for navigated transiliac screw insertion into S1 can be recommended as a feasible and safe technique, enabling the surgeon to reduce procedure and fluoroscopic time. Further progress in improving the quality of the Iso-C3D image should be attempted.

Complications amd Problems in Intramedullary Nailing of Children's Fractures

Elastic stable intramedullary nailing (ESIN) is well established for stabilizing pediatric diaphyseal and special metaphyseal limb fractures. Expanding its application requires the evaluation of problems and complications to prevent uncritical use.Four pediatric surgical departments participated in a retrospective study. Between 1990 and 1998, 937 fractures were treated by ESIN. Major indications were forearm and femur fractures. Continuous documentation of treatment, postoperative course and follow-up formed the basis of evaluation. Analysis was subdivided into intraoperative problems, postoperative problems, and complications.Intraoperative problems (6.5%) were characterized by open reduction, cortical perforation by a nail tip with subsequent instability and by iatrogenic bursting of a third fragment. Postoperatively, 6.4% of patients showed soft tissue irritation due to nail ends or joint effusions. Complications (8.4%) included axial deviation >10° or instability of osteosynthesis in 5.3% and nerve injuries in 1.4%. Delayed healing, pseudarthrosis, osteomyelitis and synostosis were only observed in isolated cases, 5 children sustained a refracture.Severe complications are rare, problems arise from suboptimal technique and incorrect indication. Detailed knowledge of technical principles and procedural recommendations constitutes the mainstay in prevention.

[Treatment of metaphyseal bone defects after fractures of the distal radius. Medium-term results using a calcium-phosphate cement (BIOBON)].

ZusammenfassungFragestellung.Der Kalziumphosphatzement BIOBON® steht seit 1998 für den klinischen Einsatz zur Behandlung knöcherner Substanzdefekte zur Verfügung. Hinsichtlich des Einsatzes von BIOBON® als Knochenersatzmaterial sind in der Literatur gegenwärtig keine Daten zu den klinischen Resultaten verfügbar.Methodik.Um die mittelfristigen klinischen Ergebnisse bei der Therapie metaphysärer Defekte nach distaler Radiusfraktur mit BIOBON ® zu evaluieren,wurden im Rahmen einer retrospektiven Studie 29 Patienten erfasst, die aufgrund einer instabilen distalen Radiusfraktur mit BIOBON® und additiver Osteosynthese von 1998 bis 2001 behandelt wurden.Ergebnisse.Von den 29 Patienten konnten 20 (69,0%) zur klinisch-radiologischen Nachuntersuchung nach durchschnittlich 18,35 Monaten (9—40 Monate) einbestellt werden. Bei allen Patienten waren radiologisch noch Anteile des Ersatzmaterials im Knochen nachweisbar. Im Gartland-und-Werley-Score wurden im Durchschnitt 7,5 Punkte (2—21 Punkte) und damit ein gutes Ergebnis erzielt.Schlussfolgerungen.Kalziumphosphatzemente stellen eine gute Alternative zur autogenen Knochentransplantation dar,von der vor allem ältere Patienten profitieren können.AbstractProblem.Since 1998 the calcium-phosphate cement BIOBON® has been an established tool for the operative treatment of metaphyseal bone defects. No data are currently available in the literature on the clinical results of employing BIOBON®.Methods.For the evaluation of the mediumterm outcome in the therapy of metaphyseal bone defects after distal radial fractures, we examined 29 patients in a retrospective study. These patients with unstable radial fractures were treated between 1998 and 2001 with BIOBON® and additional osteosynthesis.Results.We performed a clinical and radiological examination of 20 patients (69.0%) after an average period of 18.35 months (9–40 months). In all patients parts of the bone replacement material were still visible radiologically. The average outcome using the Gartland and Werley score was 7.5 points (2–21) and therefore a good result.Conclusion.Calcium-phosphate cements represent a good alternative to autogenous bone transplantation, especially in elderly patients.