Zimmer^® M/L Taper with Kinectiv™ Technology

Design Considerations

Years of extensive engineering design, laboratory testing and clinical consultation have been devoted to optimize the structural integrity, wear debris characteristics and clinical presentation of the implants and instruments. 

Wear Debris 

Using long-term clinical retrieval feedback of modular junctions that have been used successfully for many years, Zimmer developed a challenging test to replicate the most aggressive clinical fretting corrosion response. This accelerated corrosion fatigue test development considered test factors including load magnitude, test frequency, number of cycles, solution pH and solution temperature.  Further advances in the test technique allowed for quantification of mass loss from the head, neck, and stem components. Internal mass loss testing has shown that the combined wear debris of the titanium-titanium Kinectiv technology junction using an extra-extended offset neck with a +0 cobalt chrome femoral head is less than that of a +10.5 cobalt chrome femoral head on traditional titanium femoral hip stems. ¹ The use of +0 heads provides a significant advantage in regard to wear debris that can result in amounts less than that produced by traditional stem-head constructs.

Modular Junction Stability 

Due to the nature of the Kinectiv Technology neck modularity, it is necessary to have a secure lock and fit of the components such that they do not disassemble in vivo.  Neck distraction testing was conducted to evaluate the security following simulated mild assembly of the components.  The force required to distract the neck components from the stem was greater than that required to distract femoral heads from traditional stem tapers.

Simplicity

With the modular neck there are many more options but there is also the risk of increased complexity. Kinectiv Technology implants and instrumentation have been designed with significant consultation with surgeons, O.R. personnel and sales representatives. The keystone for simplicity is the use of +0 heads only. This eliminates the need of multiple head lengths, complicated charts and head size limitations and allows truly independent leg length and offset adjustment. The intuitive and readily apparent leg length and offset adjustments improve operative flow. The neck provisional layout within the provisional tray mimics the template of head centers so that one simply needs to select the neck provisional that matches the templated head center location.