H. Lill

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.

Straining of the intact and fractured proximal humerus under physiological-like loading.

Surgical treatment of proximal humeral fractures remains challenging in elderly patients, primarily due to insufficient implant fixation. Both bone quality and physiological-like loading conditions are commonly overlooked during pre-clinical in vitro evaluation. However, this knowledge is necessary in order to improve surgical treatment of the proximal humerus and the mechanical behavior of implants, particularly in patients with complex fractures and weak bone stock. We hypothesize that the bone quality has a high influence on the bone straining, independent of the arm position. The goal of this study was to determine the straining of the intact and fractured proximal humerus under physiological-like loading conditions. Furthermore, the impact of augmentation on tissue straining was evaluated. Two representative humeri were selected for this study, one osteoporotic and one reference quality, and scanned using both QCT and DEXA (average DEXA value=0.26 and 0.49 g/cm2 respectively). Subcaptial defects were generated, then stabilized with a plate prior to mechanical stiffness testing. From the QCT data, finite element models were generated and the in vitro stiffness tests analytically simulated. Under physiological-like loading conditions, the straining of the bone and implant were analyzed for 0 degrees, 90 degrees forward flexion, and 90 degrees abduction. Maximal strain values were found for the intact and fractured bone at 90 degrees abduction. This study demonstrates that the straining in a fractured bone of poor quality leads to considerably higher bone strains (up to +30%) than in a more healthy bone. Augmentation of a central void under physiological-like loading with commercial cement led to mechanical failure at the bone-cement interface. New concepts for the surgical treatment of complex fractures of the proximal humerus should take bone distribution into account and thereby allow effective treatment of fractures in osteoporotic patients. The ultimate salvage procedure of augmentation has mechanical limitations as long as current cement materials are used in osteoporotic patients.

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.

Conservative functional treatment of ankle fractures.

Abstract. Thirty-eight patients (mean age 49xa0years; range 19–91xa0years; nine of them over 60xa0years; 28 women, 10 men) suffering from an isolated Weber B fracture with a dislocation of less than 1xa0mm underwent functional therapy using a pneumatic ankle brace and were included in a prospective study. The clinical outcome was measured according to the Olerud-Molander ankle score. Functional therapy was finished in 34 cases successfully. Twenty-one patients were scored after 17xa0months on average (range 8–27xa0months) with the Olerud-Molander ankle score. A very good result was seen in 18 patients, including 12 with 100 points, a complete remission. The remaining 3 patients showed good results (1 had 90, 2 had 85). However, functional treatment failed in 4 cases due to secondary dislocation. These patients underwent surgery without further complications. The control group, 31 operated patients, did not show as good results. Functional therapy of stable Weber-B ankle fractures appears to be superior to surgery. We were able to avoid surgery in 90% of our patients and got better results than with patients undergoing open reduction and internal fixation.

[Monteggia injuries in adults: Critical analysis of injury pattern, management, and results].

ZusammenfassungHintergrund.Komplikationen, Revisionseingriffe und unbefriedigende funktionelle Ergebnisse nach operativer Versorgung von Monteggia-Frakturen sind häufig. Zudem existieren kaum Studien, die sich nur mit dem therapeutischen Konzept beim Erwachsenen beschäftigen.Patienten und Methode.Im Zeitraum 01/1988 bis 12/2001 wurden 68 erwachsene Patienten mit Monteggia-Frakturen oder -Äquivalenten operativ versorgt. 49xa0Patienten konnten nach 83 (25–176) Monaten nachuntersucht werden. Beurteilt wurde der Frakturtyp nach der Bado-Klassifikation, das funktionelle Ergebnis nach dem Mayo Elbow Score und das Ausmaß der Arthose in Anlehnung an die Kriterien von Baird u. Jackson.Ergebnisse.Das Alter der nachuntersuchten Patienten betrug median 38xa0Jahre (18–89; 31 männlich, 18 weiblich). Entsprechend der Bado-Klassifizierung lagen folgende Verletzungen vor: 18-mal Typxa01, 22-mal Typxa02, 5-mal Typxa03 und 4-mal Typxa04. Nach operativer Versorgung erreichten 14xa0Patienten ein „sehr gutes“, 21 ein „gutes“, 9 ein „befriedigendes“ und 5xa0Patienten ein „schlechtes“ Ergebnis. Bei 9 der 14xa0Patienten mit „befriedigenden“ oder „schlechten“ Ergebnissen lag eine Typ-2-Verletzung vor. Revisionspflichtige sowie nicht revisionspflichtige Komplikationen traten in jeweils 14xa0Fällen auf. Schwere arthrotische Veränderungen im Humero- bzw. Radioulnargelenk wurden in 4xa0Fällen festgestellt.Schlussfolgerungen.Monteggia-Frakturen im Erwachsenenalter sind trotz überwiegend guter funktioneller Ergebnisse komplikationsträchtig. Der Patient sollte frühzeitig auf die Gefahr verbleibender funktioneller Defizite sowie notwendiger weiterer Eingriffe hingewiesen werden.AbstractBackground.Complications, revision surgery, and unsatisfactory functional results after operative management of Monteggia fractures are frequent. Moreover, hardly any studies exist that deal exclusively with the therapeutic concept for adults.Patients and methods.Between January 1988 and December 2001, 68 patients with Monteggia fractures or equivalent injury were surgically treated. A total of 49 patients could be followed up after 83xa0months (25–176). Fracture type was assessed according to Bado’s classification, functional results according to the Mayo elbow performance score, and the extent of osteoarthritis based on the criteria of Baird and Johnson.Results.The median age of the follow-up patients was 38xa0years (18–89, 31 men, 18 women). Corresponding to Bado’s classification the following injuries were observed: 18 cases of type 1, 22 of type 2, 5 of type 3, and 4 cases of type 4. After surgical intervention, 14 patients achieved “very good”, 21 “good”, 9 “satisfactory”, and 5 “poor” results. Of the 14 patients with either “satisfactory” or “poor” results, 9 manifested a type 2 injury. Complications requiring revision surgery occurred in 14 patients and complications not requiring revision in another 14. Severe osteoarthritic changes in the humeral or radioulnar joint were observed in 4 cases.Conclusions.Monteggia fractures in adults are fraught with complications despite good functional results in the majority of cases. The patient should be made aware early on of the risk of residual functional deficits and the need for further surgical intervention.

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.

Monteggia-Verletzungen im Erwachsenenalter

ZusammenfassungHintergrund.Komplikationen, Revisionseingriffe und unbefriedigende funktionelle Ergebnisse nach operativer Versorgung von Monteggia-Frakturen sind häufig. Zudem existieren kaum Studien, die sich nur mit dem therapeutischen Konzept beim Erwachsenen beschäftigen.Patienten und Methode.Im Zeitraum 01/1988 bis 12/2001 wurden 68 erwachsene Patienten mit Monteggia-Frakturen oder -Äquivalenten operativ versorgt. 49xa0Patienten konnten nach 83 (25–176) Monaten nachuntersucht werden. Beurteilt wurde der Frakturtyp nach der Bado-Klassifikation, das funktionelle Ergebnis nach dem Mayo Elbow Score und das Ausmaß der Arthose in Anlehnung an die Kriterien von Baird u. Jackson.Ergebnisse.Das Alter der nachuntersuchten Patienten betrug median 38xa0Jahre (18–89; 31 männlich, 18 weiblich). Entsprechend der Bado-Klassifizierung lagen folgende Verletzungen vor: 18-mal Typxa01, 22-mal Typxa02, 5-mal Typxa03 und 4-mal Typxa04. Nach operativer Versorgung erreichten 14xa0Patienten ein „sehr gutes“, 21 ein „gutes“, 9 ein „befriedigendes“ und 5xa0Patienten ein „schlechtes“ Ergebnis. Bei 9 der 14xa0Patienten mit „befriedigenden“ oder „schlechten“ Ergebnissen lag eine Typ-2-Verletzung vor. Revisionspflichtige sowie nicht revisionspflichtige Komplikationen traten in jeweils 14xa0Fällen auf. Schwere arthrotische Veränderungen im Humero- bzw. Radioulnargelenk wurden in 4xa0Fällen festgestellt.Schlussfolgerungen.Monteggia-Frakturen im Erwachsenenalter sind trotz überwiegend guter funktioneller Ergebnisse komplikationsträchtig. Der Patient sollte frühzeitig auf die Gefahr verbleibender funktioneller Defizite sowie notwendiger weiterer Eingriffe hingewiesen werden.AbstractBackground.Complications, revision surgery, and unsatisfactory functional results after operative management of Monteggia fractures are frequent. Moreover, hardly any studies exist that deal exclusively with the therapeutic concept for adults.Patients and methods.Between January 1988 and December 2001, 68 patients with Monteggia fractures or equivalent injury were surgically treated. A total of 49 patients could be followed up after 83xa0months (25–176). Fracture type was assessed according to Bado’s classification, functional results according to the Mayo elbow performance score, and the extent of osteoarthritis based on the criteria of Baird and Johnson.Results.The median age of the follow-up patients was 38xa0years (18–89, 31 men, 18 women). Corresponding to Bado’s classification the following injuries were observed: 18 cases of type 1, 22 of type 2, 5 of type 3, and 4 cases of type 4. After surgical intervention, 14 patients achieved “very good”, 21 “good”, 9 “satisfactory”, and 5 “poor” results. Of the 14 patients with either “satisfactory” or “poor” results, 9 manifested a type 2 injury. Complications requiring revision surgery occurred in 14 patients and complications not requiring revision in another 14. Severe osteoarthritic changes in the humeral or radioulnar joint were observed in 4 cases.Conclusions.Monteggia fractures in adults are fraught with complications despite good functional results in the majority of cases. The patient should be made aware early on of the risk of residual functional deficits and the need for further surgical intervention.

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.

The role of cell type in bone healing mediated by ex vivo gene therapy

BackgroundThe ideal cellular vehicle for use in cell-mediated gene therapy to enhance bone healing has not yet been identified. The purpose of this study was to compare the capacity of two types of cells transduced with retro-bone morphogenetic protein 4 (BMP4)—muscle-derived cells (MDCs) and unfractioned bone marrow stromal cells (BMSCs).MethodPrimary rat MDCs and unfractioned rat BMSCs were transduced with a retrovirus to express BMP4. A 7-mm, critical-sized femur defect was created in adult rats, and 5×106 transduced cells were implanted into the femoral defect. Bone healing was monitored radiographically and histologically at 4, 8, and 12 weeks post-implantation.ResultsAll specimens in the MDC-BMP4 group and BMSC-BMP4 group showed a bridging callus at 8 and 12 weeks. At 12 weeks post-implantation the calluses of the MDC-BMP4 femora displayed significantly higher bone photodensity than the BMSC-BMP4 femora (P<0.05). Histomorphometry revealed no difference between the two treatment groups. However, non-union between newly formed and original bone was observed in none of the MDC femora but in six femora from the BMSC-BMP4 group.ConclusionBoth MDCs and unfractioned BMSCs can improve healing of a critical-sized bone defect following transduction of the cells with retroBMP4. However, MDCs appear to yield superior results when compared with BMSCs in terms of improved healing of segmental defects.