C. Josten

Proximal humeral fractures: how stiff should an implant be? A comparative mechanical study with new implants in human specimens.

BackgroundThe objective of this study was to determine the in vitro characteristics of the clinically used and newly developed implants for the stabilization of proximal humeral fractures under static and cyclic loading. The goal was to optimize implant stiffness for fracture stabilization even in weak bone stock.MethodsIn a laboratory study using 35 fresh human humeri, the specimens were randomized into 5 groups, which included the clinically used humerus T-plate (HTP), the cross-screw osteosynthesis (CSO), the unreamed proximal humerus nail with spiral blade (UHN), the recently developed Synclaw Proximal Humerus Nail (Synclaw PHN) and the angle-stable Locking Compression Plate Proximal Humerus (LCP-PH). The implant stiffness was determined for three clinically relevant load cases: axial compression, torsion and varus bending. In addition, a cyclic varus-bending test was performed to determine the implant properties under cyclic loading.ResultsIn contrast to a rather elastic and minimally invasive implant(LCP-PH), the conventionally designed ones (Synclaw PHN, CSO, HTP, UHN) showed rather high stiffness values under static loading. In cyclic loading, a strong decrease in stiffness (p<0.05) was found for the rigid implants HTP and UHN. In comparison with the other implants, only the elastic implant (LCP-PH) showed a significantly lower load reduction in a weak bone stock (17±6.2%).ConclusionThe high initial stiffness of rigid implants led to an early loosening and failure of the implant-bone interface under cyclic loading. Implants with low stiffness and elastic characteristics, however, appear to minimize the peak stresses at the bone-implant interface, making them particularly suitable for fracture fixation in osteoporotic bone.

Konservative oder operative Versorgung der Humeruskopffraktur beim alten Menschen

Abstract. The humeral head fracture in the elderly represents an unresolved problem, which is reflected by the variety of existing therapeutic strategies ranging from conservative treatment to humeral head replacement. The main factors influencing the prognostic outcome are the fracture type, age of the patient and biologic criteria such as osteoporosis, blood supply at the fragments, and the degree of soft tissue trauma. For selection of the optimal treatment, the general condition of the patient, additional injuries and chronic diseases have to be respected as much as the patients compliance and personal demands. According to experimental and clinical findings, for displaced two- and three-part fractures of the elderly patient minimal osteosynthesis and in the future plate osteosynthesis with angular stability should be preferred. For these fracture types, conservative treatment must be included in the therapeutic spectrum. In contrast, displaced four-part fractures and fracture dislocations are indications for primary humeral head replacement. This is explained by the fact that neither conservative treatment nor surgical reconstruction procedures meet the main goal of primary therapy, aiming for early painless mobilization and for timely discharging the elderly patients in their social environment.Zusammenfassung. Die Humeruskopffraktur des alten Menschen stellt ein ungelöstes Problem dar, was sich in dem breiten Therapiespektrum, von der konservativen Behandlung bis zum prothetischen Ersatz des Humeruskopfs, wiederspiegelt. Neben dem Frakturtyp und dem Alter des Patienten sind biologische Aspekte wie die Osteoporose, die Durchblutung der Fragmente aber auch die Weichteiltraumatisierung von entscheidender prognostischer Bedeutung. Bei dem Behandlungskonzept muss weiterhin die Gesamtsituation des Patienten, das Vorliegen von Begleitverletzungen oder -erkrankungen, die Compliance und der Anspruch des Patienten mitberücksichtigt werden. Nach experimentellen und klinischen Erkenntnissen sind bei den dislozierten 2- und 3-Segmentfrakturen des alten Menschen die Minimalosteosynthesen und zukünftig die winkelstabilen Plattensysteme zu favorisieren. Die konservative Behandlung muss bei diesen Frakturtypen mit in therapeutische Überlegungen einbezogen werden. Die dislozierten 4-Segmentfrakturen und Luxationsfrakturen stellen dagegen eine Indikation zum primären endoprothetischen Humeruskopfersatz dar, da weder die konservative noch die operativ rekonstruierende Therapie dem primären Behandlungsziel beim alten Menschen, der raschen schmerzfreien Mobilisierung und Entlassung in die häusliche Umgebung, ausreichend Rechnung tragen.

Fracture-dislocations of the elbow joint--strategy for treatment and results.

Abstract Between January 1993 and December 1996, 41 patients with fracture dislocation of the elbow joint were treated in our department. In 28 patients (median age 46 years, range 15–77 years; 16 male, 12 female), a clinical and radiological follow-up was obtained after median 34 months (range 12–59 months). In addition to the humero-ulnar dislocation, isolated fractures were present in 13 patients and combined fractures in 15 (all with involvement of the radial head). Primary neurological deficits were found in 7 and open fractures in 3 patients. In 7 patients, primary definitive surgical therapy was carried out by open reduction and internal fixation. A two-step surgical management (initial closed reduction and immobilization, 5 patients with external fixator, 7 with plaster; secondary open surgical procedure) was performed in 12 and conservative treatment in 9 patients. According to the Leipzig Elbow Score, taking subjective, clinical and radiological criteria into consideration, 4 patients achieved ‘excellent’ and 5 patients a ‘good’ result. Ten patients were scored ‘moderate’ and 9 ‘poor’. The rate of secondary complications necessitating revision was 36%. Poor results were primarily caused by extensive initial soft-tissue damage, delayed definitive surgical therapy, and ectopic heterotopic ossification. In contrast, fracture localization and degree of arthrosis were not of significant importance for the final outcome. In fracture dislocations, the goal is a primary definitive surgical treatment aiming for early postoperative physiotherapy.

Die gekreuzte Schraubenosteosynthese proximaler Humerusfrakturen

ZusammenfassungIm Zeitraum zwischen 4/1997 und 10/1999 wurden 31 Patienten mit dislozierten proximalen Humerusfrakturen mit einer gekreuzten Schraubenosteosynthese operativ versorgt. Bei diesem Operationsverfahren werden 2–3 Kleinfragmentschrauben über einen deltoidopektoralen Zugang vom Schaftfragment aus überkreuzend ventral und dorsal im Humeruskopf platziert. Bei den 2-Segmentfrakturen wird zusätzlich eine Zuggurtung angelegt, bei den 3-Segmentfrakturen das Tub. majus zusätzlich mit 2 Schrauben fixiert. 21 Patienten (14 w, 7 m, Altersmedian 62 Jahre, 18–86) konnten nach einem medianen Follow-up von 18 Monaten (10–29) klinisch und radiologisch nachuntersucht werden. Dabei handelte es sich um 10 2-Segment- und 11 3-Segmentfrakturen. Die Ergebnisse im Constant-Score ergaben bei 15 Frakturen sehr gute und gute Ergebnisse, in 3 Fällen befriedigende und bei 3 Patienten schlechte Ergebnisse (1-mal 2-Segment-, 2-mal 3-Segmentfrakturen). Die Komplikationsrate lag bei 29% (3 Patienten mit frühzeitiger Schraubenentfernung wegen Kopfperforation, 2 mit sekundärer Prothesenimplantation bei Humeruskopfnekrose und 1 mit Redislokation der Fraktur). Die gekreuzte Schraubenosteosynthese stellt eine Alternative bei der Versorgung dislozierter proximaler Humerusfrakturen dar und ermöglicht eine frühfunktionelle Nachbehandlung.AbstractBetween March 1997 and October 1999 thirty-one patients with displaced proximal humeral fractures were treated with crossed screw osteosynthesis. Insertion of the screws was realized by using a deltoideo-pectoral approach placing the screws anteriorly and posteriorly in a crossed manner from the distal fragment into the humeral head. Additionally, in all two-part-fractures a tension band was applied. In all three-part-fractures, the greater tuberosity was reattached by additional screws. In 21 patients (14 female, 7 male, median age 62 years, 18–86) a clinical and radiological follow-up (median 18 months, 10–29) was obtained. Fractures were classified as two-part-fractures in 10 patients and as three-part-fractures in 11 patients. According to the Constant-Score, “excellent” and “good” results were achieved in 15 patients, “moderate” results were found in 3 patients. However, in 3 patients results were only “poor” (1 two-part-, 2 three-part-fractures). The complication rate was 29% (premature hardware removal due to head perforation in 3 cases; humeral head necrosis necessitating prosthetic replacement in 2 patients; secondary displacement in 1 case). Crossed screw osteosynthesis represents an justified alternative in the surgical treatment of displaced proximal humeral fractures permitting early functional therapy.

Histopathology in rabbit Achilles tendon after operative tenolysis (longitudinal fiber incisions).

The surgical treatment (tenolysis) of chronic Achilles tendinopathy is often successful. However, little is known about the postoperative intratendinous changes after this procedure. The study group consisted of 21 rabbits. Operative tenolysis was done in each case on one Achilles tendon (AT). The ATs of both legs were studied histologically and immunohistochemically using antibodies against collagen types I and III 2, 4 and 6 weeks postoperatively. Nine rabbits without operation served as controls. A significant uniform hypervascularization was noted in the entire operated tendon postoperatively, and this concurred with the contralateral nonoperated AT, but neither side showed changes in collagen fiber structure as judged by immunohistochemistry. We conclude that the tenolysis procedure triggers neoangiogenesis at the AT followed by increased blood flow and improved nutrition in the same. These changes could, at least partly, explain the often seen clinical success in surgically treated tendinopathy.

PLASTISCHE WEICHTEILDECKUNG BEI DEFEKTFRAKTUREN AM UNTERSCHENKEL

Summary. Sequential radical debridement and early soft-tissue reconstruction have considerably decreased the amputation rate, length of hospital stay, chronic osteitis, the rehabilitation period and secondary reconstructive procedures in lower leg injuries. The introduction of distraction osteotomy and „biologic osteosynthesis procedures“ have led to shorter and safer osteoplastic methods. The indication, tactics and technical pitfalls of current interdisciplinary treatment options requiring modifications in soft-tissue coverage are presented.Zusammenfassung. Mit der konsequenten Einführung eines sequentiellen radikalen Débridements und der postprimären Weichgewebsrekonstruktion konnte die Amputationsrate, der Hospitalaufenthalt, die chronische Osteitis, die Rehabilitationsperiode und die Zahl sekundärer rekonstruktiver Eingriffe bei drittgradig offenen Unterschenkelfrakturen deutlich reduziert werden. Durch die Distraktionscorticotomie und biologische Osteosyntheseverfahren wurde die Knochenrekonstruktion deutlich verkürzt. Es werden die Indikation, taktisches Vorgehen und technische iatrogene Probleme der aktuellen interdisziplinären Verfahren geschildert, die eine Modifikation auch bei der Weichgewebsrekonstruktion erfordern.

Open MR imaging in spine surgery: experimental investigations and first clinical experiences

Abstract Introduction: The latest open MRI technology allows to perform open and closed surgical procedures under real-time imaging. Before performing spinal trauma surgery preclinical examinations had to be done to evaluate the artifacts caused by the implants. Methods: The MRT presented is a prototype developed by GE. Two vertically positioned magnetic coils are installed in an operation theater. By that means two surgeons are able to access the patient between the two coils. Numerous tests regarding the material of instruments and implants were necessary in advance. The specific size of the artifact depending on the pulse sequence and the positioning within the magnetic field had to be examined. Results: The magnifying factors of the artifact in the spin echo sequence regarding titanium are between 1.7 and 3.2, depending on the direction of the magnetic vector. Regading stainless steel they are between 8.4 and 8.5. In the gradient echo sequence the factors are between 7.5 and 7.7 for titanium and between 16.9 and 18.0 for stainless steel. The tip of an implant is imaged with an accuracy of 0 to 2 mm. Since September 1997 16 patients with unstable fractures of the thoracic and lumbar spine have been treated by dorsal instrumentation in the open MRI. Percutaneous insertion of the internal fixator has proven a successful minimally invasive procedure. The positioning of the screws in the pedicle is secure, the degree of indirect reduction of the posterior wall of the vertebral body can be imaged immediately. The diameter of the spinal canal can be determined in any plane. Discussion and conclusion: The open MRI has proven useful in orthopedic and trauma surgery. The size and configuration of the artifacts caused by instruments and implants is predictable. Therefore exact positioning of the implants is achieved more easily. Dorsal instrumentation of unstable thoracolumbar fractures with a percutaneous technique has turned out safe and less traumatic under MR-imaging. Real-time imaging of soft tissue and bone in any plane improves security for the patient and allows the surgeon to work less invasively and more precisely.

Tibiakopfplateaufrakturen – Erste Erfahrungen mit einem resorbierbaren Knochenzement zur Augmentation

ZusammenfassungIm Zeitraum von 10/96 bis 01/99 wurde bei insgesamt 29 Patienten (16 Frauen, 13 Männer; Alter Median 56,Spannweite 22–86 Jahre) mit lateralen Tibiakopffrakturen (5 B1-, 13 B2- und 11 B3-Frakturen nach der AO-Klassifikation) eine Osteosynthese in Form einer arthroskopisch, radiologisch gestützten Reposition mit perkutaner Verschraubung (16-mal) oder einer offenen Reposition und Plattenosteosynthese (13-mal) durchgeführt.Das Patientenkollektiv bestand aus: 15 Patienten (7 Frauen, 8 Männer;Alter Median 41,Spannweite 22–86 Jahre), die von 10/96 bis 12/97 retrospektiv erfasst und nach median 11 Monaten (9–22) klinisch und radiologisch nachuntersucht werden konnten.14 Patienten (9 Frauen,5 Männer;Alter Median 56,Spannweite 27–84 Jahre) wurden von 01/98 bis 01/99 prospektiv erfasst und nach 6 Monaten nachuntersucht.Die Impressionszone wurde insgesamt 11-mal mit autologer Spongiosa und 9-mal mit einem resorbierbaren Knochenzement (Norian SRS) augmentiert. In 9 Fällen war wegen des geringen Defektes bzw. eines Spaltbruchs keine Augmentation erforderlich.Im Lysholm-Score und im röntgenologischen Ergebnis zeigten sich in allen Gruppen überwiegend gute bis sehr gute Ergebnisse ohne Unterschiede bezüglich der Augmentationsformen. In der Norian SRS-Gruppe war die Dauer der Teilbelastung sowie die Behandlungsdauer deutlich kürzer.Nach den bisherigen Erfahrungen eignet sich der injizierbare neue Knochenzement aufgrund der günstigen Applikationsform und der hohen Primärstabilität zur Augmentation bei Impressions- bzw. Impressions-/Depressionsfrakturen.AbstractBetween October 1996 and January 1999,29 patients (f:16,m:13,age: 22–86) with fractures of the lateral tibial plateau were operated on arthroscopic,fluoroscopic control or were treated with open reduction and internal fixation. 15 of them were retrospective and 14 prospective analysed.The metaphyseal defect after elevation of the depressed fragment was augmentated in 11 cases with autologeous spongeous bone grafting,in 9 cases with biodegradable bone cement (Norian SRS).Augmentation was unnecessary in 9 cases.The results according to the Lysholm score and the radiological results were good or excellent.Concerning the kind of augmentation no difference was noted. In the Norian SRS-group the duration of postoperative treatment was shorter than in the other group.The duration of partial weight bearing was shorter too.The results of the present study suggest that an injectable calciumphosphate cement may be a competent material for augmetation in lateral tibial plateau fractures because of the application form and the initial high mechanical stability.

Endoskopisch assistierte Rekonstruktion der thorakolumbalen Wirbelsäule in Bauchlage

ZusammenfassungDie standardisierte einzeitige dorsoventrale Instrumentation thorakolumbaler Wirbelfrakturen erfordert bislang sowohl bei ventral offenem als auch bei endoskopisch gestütztem Vorgehen eine zeitaufwändige intraoperative Umlagerung von der Bauch- in die Seitenlagerung.Dieser Beitrag beschreibt eine ventrale endoskopisch gestützte Zugangstechnik in alleiniger Bauchlage für die Segmente von Th4 bis L4 über einen 4–5 cm langen Zugang mit einem selbsthaltenden Retraktorsystem. Die Narkosezeiten können bei diesem einzeitig kombinierten Verfahren durch den Wegfall der Umlagerungszeit um etwa 40 min reduziert werden. Die Minimalinzision in Verbindung mit dem Retraktorsystem erlaubt die Verwendung von größtenteils konventionellen Instrumenten und Implantaten und macht die endoskopisch gestützte Operation somit kostengüstiger. Wesentliche Vorteile des offenen und endoskopischen Verfahrens werden miteinander verbunden. Der größte Vorteil der Bauchlagerung liegt in der Möglichkeit des gleichzeitigen dorsalen und ventralen Zugangs zur Wirbelsäule und den damit verbundenen permanenten simultanen Korrekturmöglichkeiten.AbstractIrrespective of an anterior open or endoscopic approach, the combined postero-anterior instrumentation of thoracolumbar fractures requires time consuming intraoperative maneuvres changing the patients position from prone to lateral.A standardised anterior endoscopically assisted approach for the segments Th4 to L4 is described, allowing the patient to remain in prone position, using a 4–5cm incision combined with a retractor system.The approach to the anterior spine in prone position is feasible by using a self holding retractor system for the region from Th4 to L4. Time of anaesthesia for the one stage combined procedure can be reduced by about 40 min, when changing the position of the patient is no longer necessary. The minimal incision in combination with the retractor system allows mainly the use of conventional instruments and implants, which provides reasonable lower costs. The advantages of the open and the endoscopical technique are combined. The main advantage of the prone position is the opportunity to access the anterior and posterior spine simultaneously, which is extremly helpful in reduction maneuvres.

Bilateral posterior fracture-dislocation of the shoulder caused by an epileptic seizure – Diagnostic, treatment and result

SummaryThe case of an 39-year-old man is presented, who sustained a bilateral locked fracture dislocation of the shoulders occurring during an epileptic seizure. Radiographs demostrated a compression-fracture of the anteromedial aspect of the humeral head bilaterally (reversed Hill-Sachs-lesions). Additionally, fractures of the lesser and greater tuberosity were diagnosed at the right site. Open reduction and internal fixation was performed in both shoulders within 12 hours. 6 months later the patient has no complaints with a free range of motion. Diagnostics, treatment and result are discussed in context with the literature.ZusammenfassungEs wird der Fall eines 39 jährigen Patienten beschrieben, der sich im Rahmen eines Grand-mal-Anfalls eine fixierte, bilaterale posteriore Schulterluxationsfraktur zuzog. Beidseits lagen große „reversed Hill-Sachs-lesions“ vor, rechts bestanden zusätzlich dislozierte Frakturen von Tuberculum majus und minus. Beide Schultern wurden nach entsprechender Diagnostik am Unfalltag offen reponiert, die Impressionen angehoben und mit einem resorbierbaren Knochenzement (Norian SRS) unterfüttert, sowie die Frakturen osteosynthetisch versorgt; 6 Monate postoperativ war der Patient beschwerdefrei bei freier Beweglichkeit in beiden Schultergelenken. Anhand dieses Beispiels und der Literatur werden Diagnostik und Behandlungsstrategie bei hinteren Schulterluxationen dargestellt.