The purpose of this biomechanical study was to determine whether a multidirectional fixed-angle plate with locking screws or with locking pegs in the distal fragment would optimize fixation of Orthopaedic Trauma Association (OTA) type A3 distal radius fractures.Eight pairs of fresh-frozen human distal radii were used. Extra-articular distal radius fractures were created and stabilized with a multidirectional volar fixed-angle plate. The radii were randomized into 2 matched-paired groups. The distal fragment in Group I was stabilized with 7 locking screws. The distal fragment in Group II was fixed with 7 locking pegs. The proximal fragment in both groups was fixed with 3 screws. The specimens were tested under torsion and axial compression during static and cyclic tests. Finally, load-to-failure tests were performed under torsion.After 1000 cycles, 99% of the median torsional stiffness remained in the group using screws, whereas only 76% of the median stiffness under torsion remained in the group using pegs (P = 0.018). Under axial compression, median stiffness remained at 93% in the group using screws after 1000 cycles compared with a median of 0% in the group using pegs (P = 0.018).This biomechanical study showed a statistically significant difference between the locking screw and locking smooth peg configuration with regard to stiffness of the constructs after 1000 cycles. The use of locking screws as opposed to smooth locking pegs for OTA type A3 extra-articular distal radius fractures optimizes construct stability.
The aim of the study was to investigate bone metabolism after surgery through monitoring of bone turnover markers up to 1 year. Samples from 58 patients with diaphyseal fractures of the lower leg or tibia (group 1, n = 13), pertrochanteric femur fractures (group 2, n = 10), medial femoral neck fractures treated by cemented hip hemiarthroplasty (group 3, n = 13), soft tissue diseases (group 4, n = 12) and in patients who underwent abdominal surgery (group 5, n = 10) were analyzed. We measured serum bone alkaline phosphatase (BAP) and osteocalcin (OC) as markers of bone formation and serum type I collagen C-terminal telopeptide (ßCTX) as marker of bone degradation. We found a significant decrease of BAP in all groups within the first week after surgery. Potential mediators, responsible for this early decrease are cytokines of the acute phase response. After an initial fall, serum concentration of the degradation marker ßCTX increased at 10 - 14 days depending on group, while bone formation markers started to rise later. The increase of markers of bone metabolism seems to reflect bone resorption and bone remodeling initiated by the surgical procedure and damage to the bone. Markers of bone metabolism provide a new and promising tool for monitoring fracture and hip replacement. Here, we present a review of recent patents and markers of bone metabolism provide a new and promising tool for monitoring fracture and hip replacement. Keywords: Abdominal surgery, bone alkaline phosphatase, fracture, hip arthroplasty, osteocalcin, type I collagen, C-terminal telopeptide, bone metabolism
Fünf unterschiedliche Plattensysteme zur Versorgung von distalen Radiusfrakturen über einen palmaren Zugang wurden im biomechanischen Kadavermodell untersucht. Dazu wurde eine 1 cm breite metaphysäre Osteotomie unmittelbar proximal zum Gelenkspalt durchgeführt und die jeweilige Platte entsprechend den Anweisungen des Herstellers fixiert. Unter axialer Belastung wurde das Konstrukt dann in einer pneumatisch angetriebenen Testmaschine (Sincotec) geprüft. Jedes Implantatsystem wurde an jeweils 8 Leichenknochen bezüglich der Steifigkeit gemessen. Keines der Konstrukte zeigte Deformitäten im Osteotomiespalt von über 2 mm unter Lasten bis zu 100 N. Bei Lasten bis zu 250 N stellten sich signifikante Differenzen bezüglich der Steifigkeit und der Versagenscharakteristika der unterschiedlichen Plattensysteme dar. Die mittlere Steifigkeit unter axialer Belastung (MW±SD) betrug 356,4±138,6 N/mm für die Radiuskorrekturplatte ohne lateralen Ausläufer, 299,7±86,3 N/mm für die Radiuskorrekturplatte mit lateralem Ausläufer, 132,8±41,5 N/mm für die distale volare Radiusplatte, 112,5±40,2 N/mm für die 3,5 mm Titan Locking-Compression-Platte und 91,9±29,2 N/mm für die 3,5 mm Standard T-Platte. Dabei zeigte das nichtwinkelstabile Implantat (STP-Platte) die geringste Steifigkeit. Unerwartet gab es Differenzen von über 100% bezüglich der Steifigkeit zwischen den auf den ersten Blick weitgehend ähnlich erscheinenden winkelstabilen Implantaten. Zusätzlich erfolgte die Auswertung der in der Literatur beschriebenen Ergebnisse von biomechanischen Untersuchungen bei der distalen Radiusfraktur.
