Novation Ceramic AHS Stability in Motion

Osteolysis and dislocation have been shown to be two of the major complications with total hip arthroplasty (THA). The Novation® Ceramic AHS® is designed to minimize osteolysis by utilizing an alumina ceramic bearing that provides significantly lower wear debris generation over traditional bearing surfaces. With a goal of creating a more stable hip replacement in mind, the Novation Ceramic AHS utilizes a sizing scheme that allows the use of a large (36mm) head in the majority of patients (with a 54mm acetabulum or greater) and femoral stems with neck flats to increase range of motion, decrease impingement and mitigate the incidence of dislocation.¹

A. Acetabular Shells

• Titanium alloy
• Designed with an 18-degree internal taper to provide a secure locking mechanism
• Titanium plasma coating for press-fit fixation (with HA coating option)
• Offered in a “cluster-hole" configuration
  

B. Ceramic Bearing (Head/Liner)

• Heads available in 28mm, 32mm and 36mm

• Sizing combinations allow a 36mm head/liner in a 54mm acetabular shell resulting in increased range-of-motion

• Industry standard BIOLOX®forte alumina ceramic head and liner for wear resistance and high strength²

C. Exactech Stems

• The Novation Ceramic AHS is compatible with Exactech’s primary femoral stem systems as well as the AcuMatch® L-Series femoral stems:
• Novation Tapered, Splined and Cemented
• AcuMatch P-Series, C-Series and L-Series
• All of Exactech’s primary femoral stems feature neck flats for increased range of motion, a 131-degree neck angle and two offsets for replication of biomechanics.

Long-Term Resistance to Wear

A critical component of successful THA is resistance to wear over time. The Novation Ceramic AHS bearing system is designed to minimize wear debris and has been shown to wear up to 2,000 times less than traditional metal/polyethylene bearings.^2,3

Range of Motion

The  Novation primary femoral stems incorporate the Exactech neck flat geometry, which maintains thickness on the lateral side for strength while minimizing material medially, allowing for greater range of motion (ROM). The neck flat geometry, combined with the low profile design of the Novation Ceramic AHS system, allows up to 147 degrees ROM* utilizing the “click-to-click” measurement method.⁵

*Components used in the computer-simulation (Unigraphics NX) ROM study for the data value presented are as follows:

• Acetabular shell: Novation Ceramic AHS 54mm OD (catalog number 140-01-54)
• Head/Insert: BIOLOX®forte 36mm combination (catalog number 140-36-93/140-36-13)
• Stem: Novation primary press-fit size 9 (catalog number 160-00-09)

Increased Stability/Decreased Impingement

Larger heads have been shown to increase stability, range of motion and decrease impingement and dislocation rates.¹ Novation Ceramic AHS has a major advantage in sizing compared to the competition. Novation Ceramic AHS allows the use of a 36mm head/liner combination in a 54mm shell while other systems either don’t allow a 36mm head/liner combination or don’t allow it until a larger shell is used. Novation sizing combinations allow greater stability in more patients.

References
1. Hedlundh U, Ahnfelt L, et al. Dislocations and the femoral head size in primary total hip arthroplasty. Clin Orthop Relat Res. 1996 Dec;(333):226-33.

2. www.fda.gov/cdrh/pdf5/p050039b.pdf

3. Taylor SK, Serekian P, Manley M. Wear performance of a contemporary alumina: Alumina bearing couple under hip joint simulation. Trans. 44th Annual Meeting, ORS, 51, 1998.

4. Greenwald AS, et al.  Alternative bearing surfaces: the good, the bad and the ugly. J Bone Joint Surg Am. 2001;83-A Suppl 2 Pt 2:68-72. 

5.  Data on file at Exactech, Inc.