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Biomechanical study of calcium phosphate cement fixation of distal radius fractures

Author: LuoHuaSong From: www.yourpaper.net Posted: 2010-05-05 08:20:43 Read:
[Abstract] testing of calcium phosphate cement (CPC) fixation of distal radial fracture biomechanical effect, to provide biomechanical basis for the clinical application of CPC in the treatment of fractures of the distal radius.[Methods] on 18 adult upper limb specimens (below the elbow) of distal radius fracture model was prepared with bone defect, were randomly divided into 3 groups, respectively using Kirschner wire, CPC and CPC combined with Kirschner wire fixation, longitudinal compressive load on the wrist applied perpendicular to 98N, and the simulation of the wrist palm flexion and dorsiflexion movement, range of motion for palmar flexion 5 ~ 30 dorsiflexion, exercise 2000 times, every 500 times measurement displaced distal radius in radial and dorsal distance.The 2 specimens tested CPC elastic modulus.[results] Kirschner wire fixation group and the other 2 groups of fixed fracture displacement distance difference has statistics significance (P< 0.05), but no statistical significance in the group fixed by bone cement and bone cement augmentation Kirschner wire fixation group differences (P> 0.05).(conclusion) has good effect of CPC on the bone defect of distal radius fracture.The elastic modulus of CPC was about 30 MPa, between cancellous bone and cortical bone.
[keyword] biomechanics of calcium phosphate bone cement, elastic modulus, fracture of the distal radius
Abstract: (Objective) To test the biomechanical effects of calcium phosphate cement in fixating distal tadius fractures, and to provid biomechanical foundation for clinical treating distal tadius fractures. (Method) A models of 18 human distal radius fracture of adult upper limbs specimen were made and randomly divided into three groups:fixed with Kirschner wire (Kirschner group), CPC (CPC group), and CPC combined with Kirschner wire (combination group).Wrist joint was vertically loaded with 98 N, and palmar flexion with dorsal extention motion was dimulated, which range of movement was from palmar flexion to dorsal  5 30 and; extention frequency was 2000 cycles.Displace data of distal radius were measured by sliding caliper at every 500 cycles, we had tested Young's modulus of two samples of CPC. (Result) Multiple factor variance anAlysis was used, Kirschner group and others had significantly statistical difference (P< 0.05), but CPC group and CPC combined with Kirschner wire group had not significantly statistical difference (P> 0.05). (Conclusion) CPC can provide enough fixation strength for distal radius fracture with bone defect and Young's modulus of CPC is about 30 MPa, which is between those of cancellous bone and compact bone.
Key words:radial fracture; biomechanics; calcium phosphate cement; Young's modulus
fracture of the distal radius is span the articular surface of the distal radius fractures within 3 cm.This part is the cancellous and cortical bone at the junction, is the local anatomy and mechanics of weak, once the external forces are prone to fracture.Its occurrence rate is about 1 / 6 of all fractures, mostly occurs in the elderly, more women than men, if treatment is not timely or properly, often make a success can disorder and pain.
calcium phosphate cement (calcium phosphate cement, CPC) is a self-setting and degradation activity, inorganic materials for bone activity under physiological conditions, is a good internal fixation and bone repair materials, used in the treatment of fractures of the distal radius has certain advantages.
the CPC biomechanical study on treatment of fracture of the distal radius is relatively small (1), in order to explore the feasibility of CPC fixation of fractures of the distal radius, the authors test the biomechanical strength of CPC fixation of distal radius fractures, and compared with traditional Kirschner wire fixation, to provide biomechanical basis for the clinical application of CPC treatment of distal radius fractures.
1 materials and methods
1.1 model of distal radius fractures preparation
surgery were performed on all specimens wrist X-ray examination and determination of bone mineral density were excluded, deformity and bone mineral density data acquisition.Remove all soft tissue specimens, preserve the integrity of the interosseous membrane, the dorsal carpal membrane and transverse carpal ligament.The radial dorsal proximal is centered at 2.5 cm, in the distal and proximal 0.5 cm to about 30 angle electric oscillating saw a 1 cm wide and radial axis vertical osteotomy, retain the palm side of cortical bone integrity.Remove the dorsal wedge bone, forming the bone defects with bone knife, the volar cortex were truncated, reserved cortical contact, simulation Colles fractures of the distal radius (2 ~ 5).
1.2 block fixed
18 adult upper limb specimens (below the elbow) of distal radius fracture models were randomly divided into 3 groups, each group by analysis of variance between the bone density, there was no statistically significant difference.(1) the Kirschner wire group: the reduction of the fracture, keep the palm side cortical contact, by 2 1.5 mm gram for the fracture fixed.With an electric drill 1 Kirschner wires from the styloid process of the radius into the proximal diaphyseal ulnar, radial stem axis with 60 , the other 1 Kirschner wires from the distal radius Lister junction
Section through the proximal shaft, the palmar and dorsal side out, the radius is 60 angle.The fracture of the distal radius and proximal diaphyseal fixation (2); group CPC: after reduction of the fracture, keep the palm side cortical contact, then the solid powder and liquid phase CPC and liquid mixed in proportion (Shanghai Ruibang biological material Co Ltd provides), according to a concentration of 4 g/cm3 fast filling with bone cement was implanted into the bone defect office, keep the stability of the fragment, do not place the location of the mobile, 10 min after bone cement preliminary solidify rear can move; (3) CPC combined with Kirschner wire fixation group: the first fracture reduction with Kirschner wire fixation, and bone defects were filled with CPC.
the above specimens after a fixed, X-ray examination, to understand the situation of reposition, and then were placed on the removed 24 h after 100% moisture, 37 environment, biomechanical test.
1.3 biomechanical test
1.3.1 shift distance test radial side and dorsal distal radius fracture
the specimen in the distal to metacarpophalangeal joints disarticulation, proximal to the elbow joint under 5 cm disconnection, the far and near ends respectively with self-curing denture powder entrapment (6, 7), to be removed after the curing fixed on the biomechanical testing machine on the biomechanical test.Longitudinal compressive load on the wrist (8) of 98 N applied perpendicular to the biomechanical testing machine, to set the movement frequency parameters and Simulation of wrist flexion and dorsiflexion movement, range of motion for palmar flexion 5 ~ 30 flexion (9, 10), 2000 (11) motion.Are the radial side and a back side fixed 2 1 mm needle in the distal radius fractures, fracture displacement is used for the measurement of the mark point.With electronic vernier caliper (accuracy is 0.01 mm) measurement marks the distance between points in 100, 500, 1500, 2000 times.Differences in recording shift data and statistics of 3 groups of specimens.
1.3.2 CPC elastic modulus test
2 copies of CPC powder and liquid mixed with 5 ml injector, concussion to tight uniform distribution, the natural curing.24 h after the removal, determination of CPC cylinder with an electronic digital caliper diameter, height, and then into the biomechanical testing machine for applying the longitudinal compression load, when the bone cement cylinder structure appears to stop testing, cracks and loose, cylindrical body height measuring vernier caliper after compression, load a record load, the stress / strain the formula to calculate the elastic modulus of the material (12, 13).
1.4 statistical analysis
distal radial side and dorsal displacement distance data represented by s, packet were processed by SPSS 13 software, repeated measures analysis of variance, P=0.05. 2
2.1 distal radial side and dorsal displacement data (Tables 1, 2).Table 1 distal radial displacement distance table 2 dorsally displaced distal radial distance
after exercise frequency different compared to the distal radius, radial displacement distance and dorsal displacement distance of P> 0.05, no significant difference.Simple Kirschner wire group and simple bone cement group, simple Kirschner wire group and bone cement augmentation Kirschner wire group distal radial side and dorsal displacement distance is P< 0.05, the difference was statistically significant, and simple bone cement and bone cement augmentation Kirschner wire group distal radial side and dorsal displacement distance is P> 0.05, no significant difference.Table 3 CPC elastic modulus test
elastic modulus of 2 specimens of the measured CPC value between cancellous bone and cortical bone, can be caused by the fracture of the distal radius bone collapse to fill the role of good.
3 for on
in patients with conditions, distal radius fracture treatment goals should be good reduction, to avoid further tissue damage and temporary stable fixation to fracture healing.In recent years, with the development of science and technology and the people to the wrist biomechanics and anatomical knowledge, ideas constantly updated treatment, treatment means for continuous improvement.For patients with comminuted serious fracture, osteoporosis, fractures and severe bone defects, the traditional treatment methods have higher once again shift and malunion, it is difficult to obtain satisfactory results.
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