Zimmer | NexGen Knee Replacement System

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NexGen Knee Replacement System

Added Sep 13, 2010

Manufactured by Zimmer

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Categorised under: Orthopaedics > Knee > Total knee replacement

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Description

From Which Medical Device

The NexGen knee system by Zimmer is a comprehensive suite of implants for primary and revision knee replacement. Characteristics include asymmetric femoral radii (lateral condyle larger than the medial), a minimized width and thickness of the anterior femoral flange, and the availability of three styles of articular surface; standard, anterior constrained (AC) and anatomically rotated (AR). Femoral components are made from Zimmer’s proprietary Zimaloy Cobalt-chrome alloy, and are available in porous fibre metal, PMMA precoat and non-coated versions. Variants include:

NexGen CR (cruciate retaining fixed bearing device).

NexGen CRA (cruciate retaining augmented device) intended for use where there is ligamentous stability, but deficient bone stock.

NexGen Legacy Posterior Stabilized (LPS) knee replacement which substitutes for the posterior cruciate ligament.

NexGen LPS high flexion fixed bearing variant which has extended posterior condyles on the femoral component to permit an increased range of flexion (up to 155 degrees).

NexGen LPS-Flex Mobile and LPS-Mobile, mobile bearing variants of the above.

NexGen CR-Flex (high flexion variant of the NexGen CR knee).

NexGen Gender Solutions High-Flex knee which is intended to better fit female knees.

NexGen Legacy Knee Constrained Condylar Knee (LCCK).

NexGen Rotating Hinge knee.

There are also the NexGen MIS tibial component, with a lower profile intended for MIS surgery, and the Precoat Pegged Tibial Plate which does not have a stem.

This system is supported by Patient Specific Instrumentation (PSI) – custom jigs which are based on preoperative MRI scans and which allow the placement of fixation pins without the use of standard instruments.

References

In the 2012 UK National Joint Registry report, NexGen was the second most implanted primary knee replacement, with a revision rate of 1.32% (1.22% to 1.43%) at 3 and 2.11% (1.96% to 2.29%) at 5 years.
There were reports of early failures of the NexGen CR-Flex Porous (uncemented) Femoral component from Berger et al at the American Academy meeting in 2010.
Kim et al found no difference in clinical and radiological results in female patients undergoing standard and gender-specific variants of the NexGen CR-flex prosthesis, although the former more often closely matched the anatomy of the patient. (Kim YH et al. Comparison of standard and gender-specific posterior-cruciate-retaining high-flexion total knee replacements: a prospective, randomised study. J Bone Joint Surg BR. 2010 May; 92(5): 639-45)
Ahmed et al reported no difference in range of movement between standard and high flexion variants of the NexGen LPS implants in a randomized controlled study. (Ahmed I et al. Range of flexion after primary TKA: the effect of soft tissue release and implant design. Orthopedics. 2009 Nov; 32(11):811.)

Jolles et al suggested patients under 70 might benefit from the NexGen LPS rotating platform design, whereas those over 70 might be better suited to the fixed bearing variant. (Jolles BM et al. A randomised controlled clinical trial and gait analysis of fixed- and mobile-bearing total knee replacements with a five-year follow-up. J Bone Joint Surg Br. 2012 May;94(5):648-55.)
Bini et al reported that pre-coating of tibial implants with PMMA was not protective of aseptic loosening. ( Bini SA, Chen Y, Khatod M, Paxton EW. Does pre-coating total knee tibial implants affect the risk of aseptic revision? Bone Joint J. 2013 Mar;95-B(3):367-70. doi: 10.1302/0301-620X.95B3.27585)

Search Pubmed for NexGen Knee here.

Alerts

For MHRA alerts about the NexGen knee, look here.

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Last update 7th April 2013