D. Briem

The treatment of intertrochanteric fractures: results using an intramedullary nail with integrated cephalocervical screws and linear compression.

Objective: A new device for the treatment of intertrochanteric fractures that uses 2 cephalocervical screws in an integrated mechanism allowing linear intraoperative compression and rotational stability of the head/neck fragment has been developed. The aim of this study was to describe the results using this device for the treatment of stable and unstable intertrochanteric fractures. Design: Prospective, consecutive. Setting: Academic Trauma Center. Methods: Between March 1, 2005, and July 31, 2006, 100 consecutive patients with an intertrochanteric fracture were treated with a new trochanteric antegrade nail (InterTan; Smith-Nephew, Memphis, TN). All living patients were followed up for a minimum of 1 year postoperatively (range 12-27 months). Clinical and radiographic examinations were performed until healing and at the 1-year anniversary of the index procedure. Healing, pain with ambulation, return to activities of daily living, the modified Harris hip score, and Barthel Index were used to evaluate outcomes. Results: The mean age of the patients was 81.2 (±11.3) years. Thirty-seven patients died, 12 were too infirmed for follow-up, and 3 could not be located, leaving 48 patients available for final evaluation. The average surgical time was 41 minutes (13-95 minutes). This rose significantly with the complexity of the fracture (OTA/AO classification: A1 versus A3, P = 0.016). All fractures healed within 16 weeks (range 10-16 weeks). Radiographic analysis at healing revealed no loss of reduction, no uncontrolled collapse of the neck, no nonunions, no femoral shaft fractures, and no implant failures. Two cases in the series were poorly reduced and settled into varus malalignment. There was no varus malposition seen in the remaining 46 fractures. The mean prefracture Harris hip score (75.1 ± 13.4) was significantly reduced at the time of follow-up (70.3 ± 14.5, P = 0.003); 58% of the patients recovered their prefracture status. No significant difference was seen for the Barthel Index. Conclusions: The InterTan device appears to be a reliable implant for the treatment of intertrochanteric femoral fractures. Its design provides for stability against rotation and minimizes neck malunions (shortening) through linear intraoperative compression of the head/neck segment to the shaft. As a result of the negligible complication rate and improved clinical outcomes, this implant is now the standard treatment for all intertrochanteric fractures at our institution.

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.

Comparison of open versus percutaneous pedicle screw insertion in a sheep model

Minimally invasive surgery has become more and more important for the treatment of traumatic spine fractures. Besides, some clinical studies, objective data regarding the possible lower damage to the surrounding tissue of the spine is still missing. Here we report a sheep model where we compared a percutaneous versus an open approach for dorsal instrumentation with pedicle screws to the spine. Twelve skeletally mature sheep underwent bilateral pedicle screw fixation at the L4–L6 level. Forty-eight pedicle screws were bilaterally inserted into the pedicles and connected with rods using either an open dorsal standard or a percutaneous approach. Operation time, blood flow, compartment pressure, radiation time, loss of blood, laboratory findings and EMG were evaluated to objectify possible advantages for the percutaneous operation technique. Loss of blood and the distribution of CK-MM as a marker for muscle damage were significantly lower in the percutaneous group. However, radiation time was significantly longer in the percutaneous group. Other parameters like compartment pressure, blood flow and also measurement of the EMG at different time points did not reveal significant differences. Based on the results we found in the present study, percutaneous screw insertion can bring moderate advantages but it should be noted that essential functional deficits to the muscle could not be detected.

Biomechanical Evaluation of 3 Stabilization Methods on Acromioclavicular Joint Dislocations

Background: Traumatic acromioclavicular (AC) joint dislocations can be addressed with several surgical stabilization techniques. The aim of this in vitro study was to evaluate biomechanical features of the native joint compared with 3 different stabilization methods: locking hook plate (HP), TightRope (TR), and bone anchor system (AS). Hypothesis: The HP provides higher stiffness than the anatomic reconstruction techniques. Study Design: Controlled laboratory study. Methods: A new biomechanical in vitro model of the AC joint was used to analyze joint stability after surgical repair (HP, TR, and AS). Eighteen cadaveric specimens were randomized for bone density and diameter in the midclavicle section. Joint stiffness was measured by applying an axial load and a defined physiological range of motion for internal and external rotations and upward and downward rotations. Data were recorded at 3 stages: for the native joint after dissecting the AC ligaments, directly after repair, and after axial cyclic loading (1000 cycles with 20 and 70 N at 1 Hz). To evaluate which implant mimics physiological joint properties best, axial stiffness of vertical stability was assessed in combination with rotation. Finally, static loading in the superior direction was applied until failure of the joints occurred. Results: Axial stiffness of the TR and AS groups was 2-fold higher than for the HP group and the native joint (67.1, 66.1, and 22.5 N/mm, respectively; P < .004). Decreased load-to-failure rates were recorded in the HP group compared with the TR and AS groups (248.9 ± 72.7, 832.0 ± 401.4, and 538.0 ± 166.1 N, respectively). The stiffness of the rotations was not significantly different between the treatment methods but was lower in horizontal and downward rotations compared with the native state. Thus, native AC ligaments contributed a significant share to joint stiffness. Conclusion: The TR and AS groups demonstrated higher vertical load capacity. Compared with the TR and AS, the HP demonstrated an axial stiffness closest to the native joint. For restoring physiological properties, reconstruction of the AC ligaments may be necessary. Clinical Relevance: The results show different biomechanical properties of the HP and anatomic reconstructions.

Computerassistierte Verschraubung des hinteren Beckenrings

ZusammenfassungFragestellungComputerassistierte Verfahren sind in der Traumatologie von zunehmender Bedeutung. Als eine sinnvolle Indikation hat sich die iliosakrale Schraubeninsertion erwiesen, wobei bislang keine systematischen Untersuchungen dazu vorliegen, mit welchem Navigationsverfahren die besten Ergebnisse erzielt werden können. In einer experimentellen Untersuchung sollte die Praktikabilität eines für die Beckenchirurgie zugelassenen 3D-Bildwandlers für diese Indikation geprüft und mit bereits etablierten Navigationsverfahren verglichen werden.Material und MethodenDie Versuche wurden an 20 fixierten Humankadavern vorgenommen. Zur Durchführung der navigierten Prozedur wurde ein aktives optoelektronisches System verwendet. Die Verschraubung erfolgte perkutan in Rückenlage mit durchbohrten Spongiosaschrauben, wobei 4 Behandlungsgruppen gebildet wurden. Die postoperative Schnittbildgebung erfolgte mittels fluoroskopischem 3D-Scan und MSCT. Zielparameter der Untersuchung waren neben der Praktikabilität und Präzision der Verfahren die durchschnittliche Operations- und Durchleuchtungszeit pro instrumentierter Schraube.ErgebnisseAlle navigierten Verfahren führten im Vergleich zur konventionellen Technik zu einer Verlängerung der Operationszeit (2D: p<0,001, 3D: p>0,05, CT: p<0,001). Gleichzeitig wurde die intraoperative Durchleuchtungszeit bei Anwendung aller navigierten Verfahren signifikant gesenkt (p<0,001). Die Fehlplatzierungsrate betrug bei der konventionellen und der 2D-fluoroskopisch navigierten Verschraubung jeweils 20%, die Verfahren mit dreidimensionaler (3D-)Bilddarstellung blieben jeweils ohne Implantatfehllagen (p>0,05). Die CT-Navigation erwies sich für die untersuchte Indikation aufgrund des störanfälligen Registrierungsvorgangs und der häufig unzureichenden Matchingpräzision allerdings nur als bedingt geeignet.SchlussfolgerungenUnsere Daten zeigen, dass die fluoroskopisch navigierte Verschraubung des hinteren Beckenrings gegenüber der CT-Navigation hinsichtlich Praktikabilität und logistischem Aufwand eindeutige Vorteile aufweist. Beide bildwandlergestützten Navigationsverfahren senken darüber hinaus die intraoperative Strahlenbelastung im Vergleich zur konventionellen Technik. Eine verbesserte Präzision der Schraubenplatzierung kann eher durch Verwendung eines 3D-Bildwandlers erreicht werden, mit dem darüber hinaus die Schraubenplatzierung noch intraoperativ zuverlässig beurteilt werden kann.AbstractObjectiveComputer-assisted procedures have recently been introduced for navigated iliosacral screw placement. Currently there are only few data available reflecting results and outcome of the different navigated procedures which may be used for this indication. We therefore evaluated the features of a new 3D image intensifier used for navigated iliosacral screw placement compared to 2D fluoroscopic and CT navigation.Materials and methodsTwenty fixed human cadavers were used in this trial. Cannulated cancellous screws were percutaneously implanted in the supine position in four treatment groups. An optoelectronic system was used for the navigated procedures. Screw placement was postoperatively assessed by fluoroscopic 3D scan and CT. The target parameters of this investigation were practicability, precision as well as procedure and fluoroscopic time per screw.ResultsAll navigated procedures revealed a significant loss of time compared to non-navigated screw placement (2D: p<0.001, 3D: p>0.05, CT: p<0.001). Simultaneously a significant decrease of radiation exposure time was observed in the navigated groups (p<0.001 each). The misplacement rate was 20% in the non-navigated and the 2D fluoroscopic navigated group each. Procedures providing 3D imaging of the posterior pelvis did not produce any screw misplacement (p>0.05). However, the CT procedure was associated with time-consuming registration and high rates of failed matching procedures.ConclusionOur data show a clear benefit of using C-arm navigation for iliosacral screw placement compared with the CT-based procedure. While both fluoroscopy-based navigation procedures decrease intraoperative radiation exposure times, only 3D fluoroscopic navigation seems to improve the precision compared to non-navigated screw placement.

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.

Biomechanical evaluation of peri- and interprosthetic fractures of the femur.

BACKGROUND Because of an increasing life expectancy of patients and the rising number of joint replacements, peri- and interprosthetic femoral fractures are a common occurrence in most trauma centers. This study was designed to answer two primary questions. First, whether the fracture risk increases with two intramedullary implants in one femur; and second, whether a compression plate osteosynthesis is sufficient for stabilizing an interprosthetic fracture. METHODS Twenty-four human cadaveric femurs were harvested and four groups were matched based on the basis of bone density using a peripher quantitative computer tomography (pQCT). All groups-(I) hip prosthesis with a cemented femoral stem; (II) hip prosthesis and retrograde femoral nail; (III) hip prosthesis, retrograde femoral nail, and lateral compression plate; (IV) all three implants with an additional simulated interprosthetic fracture-were biomechanically tested in a four-point bending in lateral-medial direction. RESULTS The second group with two intramedullary implants exhibited 20% lower fracture strength in comparison with group 1 with proximal femoral stem only. The stabilization of an interprosthetic fracture with a lateral compression plate (group IV) resulted in a fracture strength similar to femur with prosthesis only. CONCLUSION Two intramedullary implants reduce the fracture strength significantly. If an interprosthetic fracture occurs, sufficient stability can be achieved by a lateral compression plate. Because two intramedullary implants in the femur may decrease the fracture strength, the treatment of supracondylar femoral fractures with a retrograde nail in cases with preexisting ipsilateral hip prosthesis should be reconsidered.

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.

[Computer-assisted screw placement into the posterior pelvic ring: assessment of different navigated procedures in a cadaver trial].

ZusammenfassungFragestellungComputerassistierte Verfahren sind in der Traumatologie von zunehmender Bedeutung. Als eine sinnvolle Indikation hat sich die iliosakrale Schraubeninsertion erwiesen, wobei bislang keine systematischen Untersuchungen dazu vorliegen, mit welchem Navigationsverfahren die besten Ergebnisse erzielt werden können. In einer experimentellen Untersuchung sollte die Praktikabilität eines für die Beckenchirurgie zugelassenen 3D-Bildwandlers für diese Indikation geprüft und mit bereits etablierten Navigationsverfahren verglichen werden.Material und MethodenDie Versuche wurden an 20 fixierten Humankadavern vorgenommen. Zur Durchführung der navigierten Prozedur wurde ein aktives optoelektronisches System verwendet. Die Verschraubung erfolgte perkutan in Rückenlage mit durchbohrten Spongiosaschrauben, wobei 4 Behandlungsgruppen gebildet wurden. Die postoperative Schnittbildgebung erfolgte mittels fluoroskopischem 3D-Scan und MSCT. Zielparameter der Untersuchung waren neben der Praktikabilität und Präzision der Verfahren die durchschnittliche Operations- und Durchleuchtungszeit pro instrumentierter Schraube.ErgebnisseAlle navigierten Verfahren führten im Vergleich zur konventionellen Technik zu einer Verlängerung der Operationszeit (2D: p<0,001, 3D: p>0,05, CT: p<0,001). Gleichzeitig wurde die intraoperative Durchleuchtungszeit bei Anwendung aller navigierten Verfahren signifikant gesenkt (p<0,001). Die Fehlplatzierungsrate betrug bei der konventionellen und der 2D-fluoroskopisch navigierten Verschraubung jeweils 20%, die Verfahren mit dreidimensionaler (3D-)Bilddarstellung blieben jeweils ohne Implantatfehllagen (p>0,05). Die CT-Navigation erwies sich für die untersuchte Indikation aufgrund des störanfälligen Registrierungsvorgangs und der häufig unzureichenden Matchingpräzision allerdings nur als bedingt geeignet.SchlussfolgerungenUnsere Daten zeigen, dass die fluoroskopisch navigierte Verschraubung des hinteren Beckenrings gegenüber der CT-Navigation hinsichtlich Praktikabilität und logistischem Aufwand eindeutige Vorteile aufweist. Beide bildwandlergestützten Navigationsverfahren senken darüber hinaus die intraoperative Strahlenbelastung im Vergleich zur konventionellen Technik. Eine verbesserte Präzision der Schraubenplatzierung kann eher durch Verwendung eines 3D-Bildwandlers erreicht werden, mit dem darüber hinaus die Schraubenplatzierung noch intraoperativ zuverlässig beurteilt werden kann.AbstractObjectiveComputer-assisted procedures have recently been introduced for navigated iliosacral screw placement. Currently there are only few data available reflecting results and outcome of the different navigated procedures which may be used for this indication. We therefore evaluated the features of a new 3D image intensifier used for navigated iliosacral screw placement compared to 2D fluoroscopic and CT navigation.Materials and methodsTwenty fixed human cadavers were used in this trial. Cannulated cancellous screws were percutaneously implanted in the supine position in four treatment groups. An optoelectronic system was used for the navigated procedures. Screw placement was postoperatively assessed by fluoroscopic 3D scan and CT. The target parameters of this investigation were practicability, precision as well as procedure and fluoroscopic time per screw.ResultsAll navigated procedures revealed a significant loss of time compared to non-navigated screw placement (2D: p<0.001, 3D: p>0.05, CT: p<0.001). Simultaneously a significant decrease of radiation exposure time was observed in the navigated groups (p<0.001 each). The misplacement rate was 20% in the non-navigated and the 2D fluoroscopic navigated group each. Procedures providing 3D imaging of the posterior pelvis did not produce any screw misplacement (p>0.05). However, the CT procedure was associated with time-consuming registration and high rates of failed matching procedures.ConclusionOur data show a clear benefit of using C-arm navigation for iliosacral screw placement compared with the CT-based procedure. While both fluoroscopy-based navigation procedures decrease intraoperative radiation exposure times, only 3D fluoroscopic navigation seems to improve the precision compared to non-navigated screw placement.