There are two kinds of bone cements for orthopaedic procedures, conventional cement (PMMA) and bioasorbable composites. Cement augmentation is a very useful technique for fixation of implants such as screws, plates, or IMnails in osteoporotic bone. Generally, cement augmentation features increased strength of implant fixation, rapid restoration of patient mobility, and reduction of the complications of implant failures. The occurrence of severe skeletal loss requires the stability provided by polymethylmethacrylate (PMMA). In a biomechanical study which investigated the treatment of osteoporotic trochanteric patients, femurs which had the lowest bone density showed a significant improvement in the initial fixation stability and total displacement of the femoral head was reduced by 39% on average in the group with the modified sliding hip screw (SHS) and PMMA compared to the standard SHS group (6). PMMA is however a permanent implant which has its shortcomings and complications such as excessive
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Alternatively, cements which are made from calcium phosphate have a better purchase to bone and supersede PMMA as void fillers. Cements that are resorbable can be tailored to provide sufficient rigidity to allow bone healing and retain mechanical strength for a period of time. Subsequently the cement undergoes degradation and is eventually replaced by the host bone. Another advantage of using cements is the possibility of early weight bearing. The advantage of cementing screws is the intimate screw-cement interface, which increases the holding power. An innovative screw design which facilitates PMMA augmentation is the ported screw. Bone cement can be injected into the screw shaft and then flows via side holes into the surrounding bone. The holding power was 278% greater than the holding power of a standard screw
Alternatively, cements which are made from calcium phosphate have a better purchase to bone and supersede PMMA as void fillers. Cements that are resorbable can be tailored to provide sufficient rigidity to allow bone healing and retain mechanical strength for a period of time. Subsequently the cement undergoes degradation and is eventually replaced by the host bone. Another advantage of using cements is the possibility of early weight bearing. The advantage of cementing screws is the intimate screw-cement interface, which increases the holding power. An innovative screw design which facilitates PMMA augmentation is the ported screw. Bone cement can be injected into the screw shaft and then flows via side holes into the surrounding bone. The holding power was 278% greater than the holding power of a standard screw