Jochen Blum

Biomechanical comparison of bending and torsional properties in retrograde intramedullary nailing of humeral shaft fractures.

OBJECTIVE To establish whether the bending and torsional stiffness of an implanted nail are influenced by nail design and nail-bolt interface, this study compared two implanted retrograde nail systems: the AO/ASIF unreamed humeral nail (UHN) and the Russell-Taylor (RT) nail. DESIGN Pair randomization. SETTING Mechanical laboratory testing. SPECIMENS Twelve pairs of freshly harvested cadaveric humeri. METHODS Transverse fractures were simulated with a standardized midshaft osteotomy and a three-millimeter gap. Both nails were proximally and distally interlocked. The RT nail has a single interlock at its base and tip. The UHN has double interlocking both proximally and distally. The screw hole design of the RT nail features slots, whereas the UHN has round screw holes. MAIN OUTCOME MEASURES Anteroposterior and mediolateral bending stiffness and torsional stiffness. RESULTS The RT nail showed higher bending stiffness in anteroposterior and mediolateral bending. Large differences were seen in the torsional characteristics: for the first 30 degrees, the RT nail showed a much lower resistance against torsion than the UHN. Analysis of variance of stiffness at four, six, and eight newton-meters showed statistical significance (p < 0.0001). Torsional stiffness, defined as the slope of a straight line approximated to between 75 and 100 percent of the maximum torque, was very similar in both nails. CONCLUSION The torsional differences between the two nail systems are attributable to the nail-bolt interface of the RT nail. This dynamic system allows a clinically relevant degree of movement. The greater resistance to rotatory forces of the UHN is explained by the fact that the interlocking at its tip and base creates a static rather than a dynamic system.

Internal Fixation of Proximal Humeral Fractures: Current Concepts

AbstractFractures of the proximal humerus are an increasingly common type of injury. Mainly elderly patients with osteoporotic bone are affected. Whereas non-displaced and stable fractures are managed successfully with conservative treatment, there is no general agreement on the surgical strategy for displaced and unstable two- to four-part fractures. The clinical outcome is influenced by the fracture type and concomitant injury to the rotator cuff. Extensive surgical manipulation of the soft tissues, non-anatomic and/or unstable fixation as well as technical errors are important contributing factors to poor clinical results.Goals of surgical treatment are to restore anatomy, to achieve fixation that is stable enough to allow early mobilization, to avoid secondary displacement and not to harm the blood supply of the humeral head in order to minimize the risk for avascular necrosis.Minimally invasive procedures using closed reduction are advantageous for protection of the arterial blood supply. Plate fixation offers superior biomechanical stability. There is a recent tendency to use fixedangle implants for proximal humeral fractures in order to avoid secondary loss of fixation. Locked plates acting as internal fixator as well as intramedullary nails better adapt according to the biomechanical and anatomical characteristics of the proximal humerus. First clinical experience with those implants is encouraging but they do not compensate for an insufficient surgical technique.

Intramedullary Stabilization of Extraarticular Proximal Tibial Fractures : A Biomechanical Comparison of Intramedullary and Extramedullary Implants Including a New Proximal Tibia Nail (PTN)

Objectives: To determine in the laboratory whether there are or are not differences between individual geometrical designs of intramedullary and extramedullary devices used for the fixation of extraarticular proximal tibial fractures. Methods: Five devices were tested: a newly developed Proximal Tibia Nail (PTN), conventional double-plate osteosynthesis (DPO), the Less Invasive Stabilization System (LISS), an augmented Unreamed Tibial Nail with a T-stabilization-plate (UTN + TSP), and an external fixator (ExFix). A 10-mm defect osteotomy was performed on paired human tibiae, and the proximal and distal ends were potted in polymethylmethacrylate cement (PMMA). Each pair of bones was randomly stabilized with the new PTN in 1 tibia (Groups PTN1 through PTN4) and in 1 of the 4 comparative implants in the corresponding contralateral bone. A biomechanical test of the bone implant construct was then performed with a vertical axial force of 350, 600, and 900 N, a bending moment of 6 Nm and a bidirectional rotational strain of 8 Nm. Displacement of bone fragments was measured and depicted as a force-displacement diagram. Results: For axial loading, significant differences were seen between the PTN 2 group compared to the LISS group (P = 0.016) and the PTN 4 group compared to the ExFix group (P = 0.016). No statistically significant differences were seen for the PTN 1 group compared to the DPO group (P = 0.125) and the PTN 3 group compared to the UTN + TSP group (P = 0.453). The bending stiffness of the PTN 1-4 groups was not significantly different from any of the 4 alternative implants. There was comparable torsional stiffness in all implant groups except for the UTN + TSP group, which was less stable and significantly different from the PTN 3 group (P = 0.016). Conclusions: Given the parameters of this investigation, the new PTN would theoretically provide the same mechanical stability as the DPO in axial loading. Higher stability in axial loading may be present when compared to the LISS or the ExFix. Further clinical investigation of this implant will determine its usefulness among proximal tibial fixation devices.

Biomechanik der Verriegelungsmarknagelung bei Oberarmschaftfrakturen Vergleichsuntersuchungen zweier Marknagelsysteme und des Effekts der interfragmentären Kompression bei unaufgebohrtem Humerusnagel

ZusammenfassungDer unaufgebohrte Humerusnagel (UHN) wurde in dieser biomechanischen Studie hinsichtlich seiner Biege- und Torsionssteifigkeiten im implantierten Zustand geprüft. Andere intramedulläre Nägel, insbesondere die unverriegelten Markraumschiener wurden von verschiedenen Autoren hinsichtlich unzulänglicher Rotationsstabilität insbesondere bei Quer- und kurzen Schrägbrüchen des Humerusschafts kritisiert. Es wird untersucht, ob der UHN selbst, wie auch der UHN in Verbindung mit interfragmentärer Kompression durch ein spezielles Kompressionsgerät die Torsionssteifigkeit signifikant erhöhen kann. Zur Bewertung von Biege- und Torsionssteifigkeit des UHN wurde dieser mit dem Russell-Taylor (RT)-Humerusnagel in paarigen in Schaftmitte osteotomierten Leichenhumeri biomechanisch verglichen. Identische Paarvergleiche erfolgten mit dem UHN ohne und UHN mit interfragmentärer Kompression. Sowohl in a.-p.-, wie auch mediolateraler Richtung ist die Steifigkeit unter 4-Punkte-Biegung bei Stabilisierung mit dem RT signifikant höher. Unter Torsionsbelastungen mit Momenten von 4, 6 und 8 Nm erzielt der UHN um mehr als das Doppelte höhere Torsionssteifigkeiten. Der nur dynamisch verriegelbare RT besitzt ein auffallend hohes initiales Bolzen-Nagel-Spiel. Durch zusätzliche interfragmentäre Kompression steigt sowohl die Steifigkeit des UHN unter 4-Punkte-Biegung in a.-p.-, wie auch mediolateraler Richtung signifikant an. Auch unter Torsionsbelastung mit Drehmomenten von 4, 6 und 8 Nm erhöht sich die Torsionssteifigkeit durch interfragmentäre Kompression signifikant. Im Vergleich mit biomechanischen Studien anderer Autoren zeigt sich, dass diese statische Verriegelungsnagelung hinsichtlich ihrer Torsionsstabilität den nicht-statischen intramedullären Verfahren, und hier insbesondere den Markraumschienern, deutlich überlegen ist und sich insbesondere f6uuml;r rotationskritische Frakturtypen wie Quer- und kurze Schrägfrakturen des Humerusschafts anbietet.AbstractIn this biomechanical study the implanted Unreamed Humeral Nail (UHN) has been tested concerning bending and torsional stiffnesses. In literature other intramedullary implants have been critisized for insufficient rotatory stability especially in transverse and short oblique fractures of the humeral shaft. This study examined, whether the implanted UHN, as well as the UHN implanted with interfragmentary compression through a specific compression device, is able to augment torsional stiffness significantly. To evaluate bending and torsional stiffnesses, the UHN has been compared biomechanically to the Russell-Taylor humeral nail (RT) in paired mid-shaft osteotomized cadaveric humeri. Identic paired comparison has been performed with the UHN without and UHN with interfragmentary compression. In anterior-posterior, as well as medio-lateral direction stiffness under four-point-bending is significantly higher in stabilizing with the RT. Under torsional loading with moments of 4 Nm, 6 Nm and 8 Nm the UHN reached more than the double torsional stiffness. The RT, which is only dynamically interlocked, owns a high initial “play” between bolts and nail itself. Through additional interfragmentary compression stiffness of the UHN under four-point-bending in anterior-posterior, as well as medio-lateral direction augments significantly. Also under torsional loading with moments of 4 Nm, 6 Nm und 8 Nm torsional stiffness increases with interfragmentary compression significantly. In comparison to other biomechanical studies of different autorship it is clear, that this statically interlocked intramedullary nailing of the humeral shaft is superior to non-statically interlocked types of nailing concerning their stabilizing potency in torsion and serves especially for fracture types, which are critically under rotation, as transverse or short oblique humeral shaft fractures.

Influence of formalin fixation on the biomechanical properties of human diaphyseal bone

Abstract Owing to the lack of fresh human bones, formalin-fixed specimens are frequently used in biomechanical testing. However, formalin fixation is assumed to affect the biomechanical properties of bone. The aim of this study was to compare axial and torsional stiffness and bone mineral density in fresh and embalmed human bones. The subtrochanteric regions of 12 pairs of fresh human femora were randomised into two groups for paired comparison. After bone mineral density measurement, one group was preserved in 4% formalin. After 6 weeks, bone mineral density was remeasured and each specimen underwent axial and torsional loading. The formalin group showed significant higher stiffness values for torsional and axial loads than the fresh group. Axial stiffness increased by 14.1%, whereas torsional stiffness increased by 14.3%. These differences were not reflected in bone mineral density values. Formalin fixation significantly influences the stiffness of human cadaveric bones. Fresh bones represent the in vivo conditions better than formalin fixed bones.

[Angle-stable intramedullary nailing of proximal humerus fractures with the PHN (proximal humeral nail)].

OBJECTIVE Stable fixation of two- and three-part fractures of the proximal humerus through minimally invasive operative technique and rapid bone healing as well as restoration of original anatomy. Early functional training with the goal of restoration of former mobility and daily activities. INDICATIONS Unstabile two- and three-part fractures of the proximal humerus (AO classification: 11-A2, 11-A3, 11-B1, 11-B2, 11-B3). Subcapital nonunion of the humerus. Pathologic fractures. CONTRAINDICATIONS Pediatric fractures of the proximal humerus. Fractures of the proximal humerus types 11-C2 und 11-C3 according to the AO classification. Active local infection, e.g., after former operation. SURGICAL TECHNIQUE Closed reduction. Anterior acromial incision, splitting of the deltoid muscle and the rotator cuff. Opening of the medullary canal with the awl. Nail introduction. Spiral blade introduction in cannulated technique through stab incision. Distal interlocking through aiming device, angle-stable blocking of nail and blade through end cap. POSTOPERATIVE MANAGEMENT Postoperative fixation in Gilchrist sling until 2nd postoperative day; then physiotherapy respecting fracture type and stability, local swelling, patients age and compliance, and concomitant injuries. RESULTS 151 proximal humeral fractures were treated with a proximal humeral nail (PHN). 108 patients could be followed up 1 year postoperatively. Significant complications were perforation of the articular surface through bolts or blades (n = 8), implant-related pain (n = 10), fragment dislocation (n = 2), nonunion (n = 2), humeral head necrosis (n = 3), and superficial infection (n = 1). 1 year after the operation, the Constant-Murley Score showed a median value of 75.3 in the injured shoulder and of 89.9 in the uninjured shoulder. The DASH (Disability of the Arm, Shoulder and Hand) Score was 5.9 preoperatively and 9.3 at 1 year postoperatively. The worst results regarding the Constant-Murley Score as well as the DASH Score were found in C-type fractures.ZusammenfassungOperationszielStabile Fixierung von Zwei- und Dreifragmentfrakturen des proximalen Humerus durch minimalinvasive Operationstechnik und rasche Ausheilung bei Wiederherstellung der ursprünglichen Anatomie. Erreichen einer frühzeitigen funktionellen Nachbehandlung mit dem Ziel der Wiederherstellung der ursprünglichen Beweglichkeit und der früheren Alltagsfunktion.IndikationenInstabile Zwei- und Dreifragmentfrakturen am proximalen Humerus (AO-Klassifikation: 11-A2, 11-A3, 11-B1, 11-B2, 11-B3).Subkapitale Humeruspseudarthrosen.Pathologische Frakturen.KontraindikationenKindliche Frakturen am proximalen Humerus. Frakturen am proximalen Humerus nach der AO-Klassifikation: 11-C2 und 11-C3.Floride lokale Infektion, z.B. nach Voroperationen.OperationstechnikGeschlossene Reposition. Anteriore Inzision im Akromionbereich, Spaltung des Musculus deltoideus und der Rotatorenmanschette. Eröffnung des Markraums mit dem Pfriem.Einbringen des Nagels. Einbringen der Spiralklinge in kanülierter Technik über Stichinzision.Distale Verriegelung über Zielbügel. Winkelstabile Verblockung von Nagel und Spiralklinge mit der Verschlussschraube.WeiterbehandlungPostoperative Ruhigstellung im Gilchrist-Verband bis zur Drainageentfernung; am 2. postoperativen Tag Beginn mit physiotherapeutischer Übungsbehandlung je nach Frakturtyp, Stabilität der Osteosynthese, Knochenqualität, Alter des Patienten, lokalen Begleitverletzungen, Schwellungssituation und Patientenmitarbeit. Abnahme des Gilchrist-Verbands zur Physiotherapie ab dem 2. Tag. Passive und assistive Bewegungsübungen im schmerzfreien Bereich je nach biomechanischen und biologischen Gegebenheiten.Ergebnisse151 proximale Humerusfrakturen wurden mittels proximaler Humerusmarknagelung behandelt. 108 Patienten (71,5%) konnten 1 Jahr postoperativ nachverfolgt werden. Bedeutende Komplikationen waren Perforationen der Humerusgelenkfläche durch Bolzen oder Spiralklinge (n = 8), Schmerzen durch das Implantat (n = 10), Fragmentdislokationen (n = 2), Pseudarthrosen (n = 2), Humeruskopfnekrosen (n = 3) und ein oberflächlicher Wundinfekt. Der Constant- Murley-Score zeigte 1 Jahr nach Operation einen Mittelwert der verletzten Seite von 75,3 und der nichtverletzten Seite von 89,9. Der DASH-Score (Disability of the Arm, Shoulder and Hand) lag präoperativ bei 5,9 und 1 Jahr postoperativ bei 9,3. Die schlechtesten Ergebnisse fanden sich sowohl im Constant-Murley-Score als auch im DASH-Score bei den Typ-C-Frakturen.AbstractObjectiveStable fixation of two- and three-part fractures of the proximal humerus through minimally invasive operative technique and rapid bone healing as well as restoration of original anatomy. Early functional training with the goal of restoration of former mobility and daily activities.IndicationsUnstabile two- and three-part fractures of the proximal humerus (AO classification: 11-A2, 11-A3, 11-B1, 11-B2, 11-B3).Subcapital nonunion of the humerus.Pathologic fractures.ContraindicationsPediatric fractures of the proximal humerus.Fractures of the proximal humerus types 11-C2 und 11-C3 according to the AO classification.Active local infection, e.g., after former operation.Surgical TechniqueClosed reduction. Anterior acromial incision, splitting of the deltoid muscle and the rotator cuff. Opening of the medullary canal with the awl.Nail introduction. Spiral blade introduction in cannulated technique through stab incision.Distal interlocking through aiming device, angle-stable blocking of nail and blade through end cap.Postoperative ManagementPostoperative fixation in Gilchrist sling until 2nd postoperative day; then physiotherapy respecting fracture type and stability, local swelling, patient’s age and compliance, and concomitant injuries.Results151 proximal humeral fractures were treated with a proximal humeral nail (PHN). 108 patients could be followed up 1 year postoperatively. Significant complications were perforation of the articular surface through bolts or blades (n = 8), implant-related pain (n = 10), fragment dislocation (n = 2), nonunion (n = 2), humeral head necrosis (n = 3), and superficial infection (n = 1). 1 year after the operation, the Constant-Murley Score showed a median value of 75.3 in the injured shoulder and of 89.9 in the uninjured shoulder. The DASH (Disability of the Arm, Shoulder and Hand) Score was 5.9 preoperatively and 9.3 at 1 year postoperatively. The worst results regarding the Constant-Murley Score as well as the DASH Score were found in C-type fractures.

Die winkelstabile Marknagelung bei Frakturen am proximalen Humerus mit dem PHN (Proximaler Humerusnagel)

OBJECTIVE Stable fixation of two- and three-part fractures of the proximal humerus through minimally invasive operative technique and rapid bone healing as well as restoration of original anatomy. Early functional training with the goal of restoration of former mobility and daily activities. INDICATIONS Unstabile two- and three-part fractures of the proximal humerus (AO classification: 11-A2, 11-A3, 11-B1, 11-B2, 11-B3). Subcapital nonunion of the humerus. Pathologic fractures. CONTRAINDICATIONS Pediatric fractures of the proximal humerus. Fractures of the proximal humerus types 11-C2 und 11-C3 according to the AO classification. Active local infection, e.g., after former operation. SURGICAL TECHNIQUE Closed reduction. Anterior acromial incision, splitting of the deltoid muscle and the rotator cuff. Opening of the medullary canal with the awl. Nail introduction. Spiral blade introduction in cannulated technique through stab incision. Distal interlocking through aiming device, angle-stable blocking of nail and blade through end cap. POSTOPERATIVE MANAGEMENT Postoperative fixation in Gilchrist sling until 2nd postoperative day; then physiotherapy respecting fracture type and stability, local swelling, patients age and compliance, and concomitant injuries. RESULTS 151 proximal humeral fractures were treated with a proximal humeral nail (PHN). 108 patients could be followed up 1 year postoperatively. Significant complications were perforation of the articular surface through bolts or blades (n = 8), implant-related pain (n = 10), fragment dislocation (n = 2), nonunion (n = 2), humeral head necrosis (n = 3), and superficial infection (n = 1). 1 year after the operation, the Constant-Murley Score showed a median value of 75.3 in the injured shoulder and of 89.9 in the uninjured shoulder. The DASH (Disability of the Arm, Shoulder and Hand) Score was 5.9 preoperatively and 9.3 at 1 year postoperatively. The worst results regarding the Constant-Murley Score as well as the DASH Score were found in C-type fractures.ZusammenfassungOperationszielStabile Fixierung von Zwei- und Dreifragmentfrakturen des proximalen Humerus durch minimalinvasive Operationstechnik und rasche Ausheilung bei Wiederherstellung der ursprünglichen Anatomie. Erreichen einer frühzeitigen funktionellen Nachbehandlung mit dem Ziel der Wiederherstellung der ursprünglichen Beweglichkeit und der früheren Alltagsfunktion.IndikationenInstabile Zwei- und Dreifragmentfrakturen am proximalen Humerus (AO-Klassifikation: 11-A2, 11-A3, 11-B1, 11-B2, 11-B3).Subkapitale Humeruspseudarthrosen.Pathologische Frakturen.KontraindikationenKindliche Frakturen am proximalen Humerus. Frakturen am proximalen Humerus nach der AO-Klassifikation: 11-C2 und 11-C3.Floride lokale Infektion, z.B. nach Voroperationen.OperationstechnikGeschlossene Reposition. Anteriore Inzision im Akromionbereich, Spaltung des Musculus deltoideus und der Rotatorenmanschette. Eröffnung des Markraums mit dem Pfriem.Einbringen des Nagels. Einbringen der Spiralklinge in kanülierter Technik über Stichinzision.Distale Verriegelung über Zielbügel. Winkelstabile Verblockung von Nagel und Spiralklinge mit der Verschlussschraube.WeiterbehandlungPostoperative Ruhigstellung im Gilchrist-Verband bis zur Drainageentfernung; am 2. postoperativen Tag Beginn mit physiotherapeutischer Übungsbehandlung je nach Frakturtyp, Stabilität der Osteosynthese, Knochenqualität, Alter des Patienten, lokalen Begleitverletzungen, Schwellungssituation und Patientenmitarbeit. Abnahme des Gilchrist-Verbands zur Physiotherapie ab dem 2. Tag. Passive und assistive Bewegungsübungen im schmerzfreien Bereich je nach biomechanischen und biologischen Gegebenheiten.Ergebnisse151 proximale Humerusfrakturen wurden mittels proximaler Humerusmarknagelung behandelt. 108 Patienten (71,5%) konnten 1 Jahr postoperativ nachverfolgt werden. Bedeutende Komplikationen waren Perforationen der Humerusgelenkfläche durch Bolzen oder Spiralklinge (n = 8), Schmerzen durch das Implantat (n = 10), Fragmentdislokationen (n = 2), Pseudarthrosen (n = 2), Humeruskopfnekrosen (n = 3) und ein oberflächlicher Wundinfekt. Der Constant- Murley-Score zeigte 1 Jahr nach Operation einen Mittelwert der verletzten Seite von 75,3 und der nichtverletzten Seite von 89,9. Der DASH-Score (Disability of the Arm, Shoulder and Hand) lag präoperativ bei 5,9 und 1 Jahr postoperativ bei 9,3. Die schlechtesten Ergebnisse fanden sich sowohl im Constant-Murley-Score als auch im DASH-Score bei den Typ-C-Frakturen.AbstractObjectiveStable fixation of two- and three-part fractures of the proximal humerus through minimally invasive operative technique and rapid bone healing as well as restoration of original anatomy. Early functional training with the goal of restoration of former mobility and daily activities.IndicationsUnstabile two- and three-part fractures of the proximal humerus (AO classification: 11-A2, 11-A3, 11-B1, 11-B2, 11-B3).Subcapital nonunion of the humerus.Pathologic fractures.ContraindicationsPediatric fractures of the proximal humerus.Fractures of the proximal humerus types 11-C2 und 11-C3 according to the AO classification.Active local infection, e.g., after former operation.Surgical TechniqueClosed reduction. Anterior acromial incision, splitting of the deltoid muscle and the rotator cuff. Opening of the medullary canal with the awl.Nail introduction. Spiral blade introduction in cannulated technique through stab incision.Distal interlocking through aiming device, angle-stable blocking of nail and blade through end cap.Postoperative ManagementPostoperative fixation in Gilchrist sling until 2nd postoperative day; then physiotherapy respecting fracture type and stability, local swelling, patient’s age and compliance, and concomitant injuries.Results151 proximal humeral fractures were treated with a proximal humeral nail (PHN). 108 patients could be followed up 1 year postoperatively. Significant complications were perforation of the articular surface through bolts or blades (n = 8), implant-related pain (n = 10), fragment dislocation (n = 2), nonunion (n = 2), humeral head necrosis (n = 3), and superficial infection (n = 1). 1 year after the operation, the Constant-Murley Score showed a median value of 75.3 in the injured shoulder and of 89.9 in the uninjured shoulder. The DASH (Disability of the Arm, Shoulder and Hand) Score was 5.9 preoperatively and 9.3 at 1 year postoperatively. The worst results regarding the Constant-Murley Score as well as the DASH Score were found in C-type fractures.

Bending and Torsional stiffness in cadaver humeri fixed with a self-locking Expandable or interlocking nail system a mechanical study

Objectives: This study was designed to gain data about a new expandable, noninterlocked intramedullary nails capacity to stabilize unstable transverse humeral shaft fractures without the need for interlocking, thus making nail implantation simpler and to prove our goal hypothesis: that in a midshaft osteotomy of the humeral shaft the expandable humeral nail will show the same bending and torsional stiffness as an interlocked humeral nail, when implanted correctly according to the manufacturers instructions. Design: Pair randomization. Setting: Mechanical laboratory testing. Participants: Eight pairs of freshly harvested cadaveric humeri. Interventions: Fracture model was a midshaft transverse osteotomy, gapped to 3 mm. Each humerus pair received an expandable humeral nail (Fixion®) or an interlocked humerus nail (Synthes) through a retrograde approach. The humeri were fixed in polymethylmethacrylate cylinders and tested in a servo-pneumatic material-testing machine. Main Outcome Measurements: Torsional stiffness and bending stiffness of the nail-bone-construction. Results: Expandable nails (interlocked nails) showed a lateral bending stiffness of 0.73 ± 0.14 (0.63 ± 0.1) KN/mm (P = 0.026) and a frontal bending stiffness of 0.67 ± 0.18 (0.58 ± 0.09) KN/mm (P = 0.084). Torsional stiffness values were 0.13 ± 0.19 (0.43 ± 0.09 Nm/°) (P = 0.012). Lower torsional stiffness in the expandable nail group was observed in humeri with a funnel shaped proximal intramedullary canal. Conclusions: The nail systems showed similar characteristics for frontal bending (P = 0.084), but not for lateral bending (P = 0.026). For lateral bending, the Fixion® nail showed significantly more stiffness than the UHN® nail (P = 0.026). There was significantly lower torsional stiffness with expandable nails compared with interlocked nails. Clinical correlation would suggest that in rotationally unstable fractures (A2 and A3 diaphyseal fractures), interlocked nails would provide increased stability over expandable nails.

Ergebnisse nach primärer ungebohrter Tibianagelung von Unterschenkelfrakturen mit schwerem offenem oder geschlossenem Weichteilschaden

Primary stabilization was performed in 72 tibial fractures with severe open (n = 37) or closed (n = 35) soft tissue injury using unreamed interlocking nails. In 60 (83%) cases the fractures healed without additional procedures. There were 2 cases of osteitis, but both these fractures healed after removal of the nail or after reamed nailing. In 9 patients with delayed union reamed nailing (n = 8) or bone grafting (n = 1) led to healing. In 1 patient with hypertrophic pseudarthrosis, union was achieved after substitution of a reamed nail for the anreamed nail. The infection rate was similar to that observed with external fixation. More secondary procedures, such as bone grafting or a change of the osteosynthesis technique, are necessary with external fixation than with unreamed nailing. Further advantages of unreamed nailing are the internal treatment of the fracture and the patients greater comfort. Therefore, unreamed nailing can be recommended for the primary treatment of tibial fractures with severe open or closed soft tissue trauma.

Intramedullary Nailing of Humeral Head and Humeral Shaft Fractures

There is an increasing interest in intramedullary nailing for humeral fractures. Starting with diaphyseal fractures, now also proximal metaphyseal fractures of the humerus can be nailed with satisfying results. Basic ideas for humeral nailing are less invasive approaches to the humerus, less soft tissue damage, e.g. lower rates of radial nerve palsy, closed reduction and the biomechanical aspects of a central implant with elastic fixation properties. Nailing of diaphyseal humeral shaft fractures is an equivalent alternative to plating; nailing of proximal metaphyseal humeral fractures is still new and needs more reliable scientific data to clear its advantages compared to other fixation techniques. Nailing of distal metaphyseal humeral fractures is no serious option at the moment. Angular stable interlocking systems show better fixation qualities for proximal fractures or fracture components. Although in very osteoporotic bone cutouts are registered. Static interlocking is advisable. High torsional stability of the fracture fixation has to be achieved, since significant torsional load occurs during the usual movement of the upper limbs. As there is an important learning curve, possible complications of intramedullary nailing have to be kept in mind and avoided by a careful operation technique.