Comparison of degradation behavior and the associated bone response of ZK60 and PLLA in vivo

Calcium magnesium phosphate cements (CMPCs) are promising bone substitutes and experience great interest in research. Therefore, in-vivo degradation behavior, osseointegration and biocompatibility of three-dimensional (3D) powder-printed CMPC scaffolds were investigated in the present study. The materials Mg225 (Ca0.75Mg2.25(PO4)2) and Mg225d (Mg225 treated with diammonium hydrogen phosphate (DAHP)) were implanted as cylindrical scaffolds (h = 5 mm, Ø = 3.8 mm) in both lateral femoral condyles in rabbits and compared with tricalcium phosphate (TCP). Treatment with DAHP results in the precipitation of struvite, thus reducing pore size and overall porosity and increasing pressure stability. Over 6 weeks, the scaffolds were evaluated clinically, radiologically, with Micro-Computed Tomography (µCT) and histological examinations. All scaffolds showed excellent biocompatibility. X-ray and in-vivo µCT examinations showed a volume decrease and increasing osseointegration over time. Structure loss and volume decrease were most evident in Mg225. Histologically, all scaffolds degraded centripetally and were completely traversed by new bone, in which the remaining scaffold material was embedded. While after 6 weeks, Mg225d and TCP were still visible as a network, only individual particles of Mg225 were present. Based on these results, Mg225 and Mg225d appear to be promising bone substitutes for various loading situations that should be investigated further.

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In vivo degradation behavior of Ca-deficient hydroxyapatite coated Mg–Zn–Ca alloy for bone implant application

Colloids and Surfaces B Biointerfaces ◽

10.1016/j.colsurfb.2011.06.040 ◽

2011 ◽

Vol 88 (1) ◽

pp. 254-259 ◽

Cited By ~ 78

Author(s):

Huanxin Wang ◽

Shaokang Guan ◽

Yisheng Wang ◽

Hongjian Liu ◽

Haitao Wang ◽

...

Keyword(s):

Degradation Behavior ◽

Bone Implant ◽

In Vivo Degradation

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Comparison of the In Vivo Degradation Progress of Solid Magnesium Alloy Cylinders and Screw-Shaped Magnesium Alloy Cylinders in a Rabbit Model

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.742 ◽

2010 ◽

Vol 638-642 ◽

pp. 742-747 ◽

Cited By ~ 7

Author(s):

Nina von der Höh ◽

Dirk Bormann ◽

Arne Lucas ◽

Fritz Thorey ◽

Andrea Meyer-Lindenberg

Keyword(s):

Magnesium Alloy ◽

Pitting Corrosion ◽

Femoral Condyle ◽

Rabbit Model ◽

Degradation Behavior ◽

Gas Generation ◽

Cross Sectional ◽

Bone Implant ◽

Computed Tomograph

Resorbable magnesium alloy implants for osteosynthetic surgery would be advantageous to common implants of titanium or surgical steel as a second surgery for implant removal would become unnecessary. To influence the degradation progress, surface modifications are sensible. As plates and screws were used to stabilize fractures, the degradation behavior of threaded cylinders is of particular interest. Therefore each eight solid MgCa0.8 alloy cylinders (3 x 5 mm) with smooth and sandblasted surface, respectively, and eight screw-shaped, threaded MgCa0.8 cylinders (thread pitch 1.25 mm, length 5 mm) were inserted into the medial femoral condyle of adult New Zealand White rabbits. Implantation periods were three and six months, within which the animals were examined daily. To evaluate a possible gas generation radiographs were taken weekly. After euthanasia the bone-implant-compound was scanned in a µ-computed tomograph (µCT80, ScancoMedical). All implants were well tolerated. Smooth implants degraded slowly. The cross sectional area did not reduce obviously after three months implantation duration and only mildly after six months. Sandblasted implants showed the fastest degradation progress after both implantation periods with the most obvious generation of gas. Threaded cylinders revealed pitting corrosion at the thread pitches. They degrade faster than smooth implants but slower than sandblasted cylinders. In summary, surface modification influences the degradation behavior of resorbable magnesium alloy implants. Contrary to common materials, smooth surfaces seem to be favorable. Thread pitches of screw-shaped implants show pitting corrosion. To what extend this result affects future applications of resorbable screws has to be examined in further investigations.

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