Description
The basic design of the twinSys stem system is based on the straight-stem prosthesis concept by Prof. Maurice E. Müller. The twinSys system has been distributed since 2003 with the aim of enabling surgeons to perform cemented and uncemented implan-tation with a single instrumentation.
The cemented twinSys stem is a straight monoblock prosthesis available in both Standard and Lateral versions. In relation to the rasp, the stem is under-dimensioned by 1 mm per side, offering sufficient space for a homogenous cement mantle.
The rounded, rectangular cross-section gives the implant its stability against rotational forces acting on it. According to the French philosophy of combining a highly polished stem with a thin cement mantle («composite beam»), no centring aid is necessary. 1, 2
The triply conical stem geometry transforms the shear forces into compressive forces and allows wedging of the stem in the cement mantle, thereby minimising the risk of postoperative subsidence. 3 By absorbing micro-movements between the implant and the cement mantle, the highly polished surface reduces the risk of prosthesis loosening. 1, 2
Benefit
- Same instrumentation for implantation of the cemented and uncemented stems
- Triply conical design with thin cement mantle to minimise the risk of subsidence 1, 2, 3
- Highly polished surface to reduce micro-movements and friction between implant and cement 2, 3
- 7 A* ODEP rating 4
1 Skinner, J.A., et al., Should the cement mantle around the femoral component be thick or thin? J Bone Joint Surg Br, 2003. 85(1): p. 45-51.
2 Scheerlinck T.; Casteleyn P.-P.; The design features of cemented femoral hip implants; J Bone Joint Surg [Br] 2006;88-B:1409-18.
3 Siepen W., et al. Prospective two-year subsidence analysis of 100 cemented polished straight stems – a short-term clinical and radiological observation. BMC Musculoskelet Disord, 2016. 17(1): p. 395.
4 The most recent ODEP rating can be downloaded from www.odep.org.uk.