twinSys® Stem
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Even though a great deal of care is taken over the choice of the future implant in preoperative preparation, the intraoperative situation based on case material can reveal a completely different picture that requires a rapid and uncomplicated solution.
Uncemented or cemented after all?
The twinSys® instrumentation provides a safe surgical procedure for both stems and lets the surgeon choose "even at the last minute". The rasps allow the implantation of an uncemented as well as of a cemented stem.
The uncemented twinSys® stem
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Primary stability is obtained by wedging the stem in the prepared medullary cavity, and the risk of a postoperative subsidence is reduced due to the triple taper design. The design of the stem and the chosen Ti6A 4V material enable an almost natural proximal force distribution in the bone through the previously compressed cancellous bone.
In the proximal area of the stem, the selected cross-sectional geometry fills the medullary cavity almost entirely and in the metaphyseal area, the rectangular shaping protects the stability of the implant against acting torsional forces. The slim distal tip of the prosthesis minimises the risk of stress shielding.
The vertical rib structure increases primary press-fit on the one hand and on the other it opposes the acting torsional forces.
For a durable anchoring in the bone, the plasma spray method is used to deposit a hydroxyapatite coating on the corundum-blasted surface.
The cemented twinSys® stem
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Compared to the rasp, the implant is undersized by 1mm per side and provides sufficient space for a homogeneous cement coat. The triple tapered stem geometry transforms the shearing forces as far as possible into compressive forces and enables optimal wedging of the stem in the cement coat in case of postoperative subsidence.
The mirror-bright polished surface absorbs micro-movements at the implant/cement coat interface and reduces the risk of loosening at the bone/cement coat interface. The chamfered rectangular cross-sectional geometry protects the stability of the stem against acting torsional forces.
The benefits of the optimised cone design
In comparison to other designs, the optimised cone geometry distinctly increases the extent of anatomical movement. In addition, it also distinctly reduces the risk of dislocation and wear of the cup's inlay as a result of impingement between the stem and the cup.
A combination with all our 12/14 heads is guaranteed, so that an articulation choice suitable for the patient can be made.
Literature
Other innovative products
Our company has several other innovated products which are not
published on this website. Please refer to your Mathys contact person
for further information.