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Zimmer, Inc.

Zimmer® MotionLoc® Screw for the NCB® Polyaxial Locking Plate System

Zimmer® Motion Loc ® Screws reduce the stiffness of locked plating constructs to promote healing of long bone fractures

The MotionLoc Screw is Zimmer Trauma's latest advancement in locking plate technology and is intended for use in conjunction with the Zimmer NCB Locking Plate System.

View Zimmer’s MotionLoc Screw surgeon testimonial video discussing Zimmer’s cutting edge technology for reducing the stiffness of locking plate constructs and improving patient outcomes.

Far cortical locking technology forms the basis for the MotionLoc Screw, which reduces the stiffness of a locked plating construct study results and analysis without losing construct strength. This offers surgeons a new option to treat complex fractures.

MotionLoc technology generates parallel motion at the fracture site through elastic flexion of the screws to actively promote secondary bone healing circumferentially across the entire fracture gap.

The challenge of fracture nonunions with traditional locked plating technology

Locked plating constructs are creating a challenge for surgeons.  While it is true that a plating construct needs to be strong enough to support the damaged bone while the fracture heals, it is also true that too much stiffness forces the body to heal through osteonal (primary or direct) healing. 3

Primary healing requires near-perfect anatomic reduction and rigid compression for absolute stability which can be a complex and unforgiving procedure.4

Three recent studies examining supracondylar femur fractures show concern for the high degree of stiffness of locked plating constructs and report nonunion rates as high as 23%.1,2,3

Figure 1: Asymmetric Gap Closure

Figure 1 illustrates how locked plating constructs will bend to create motion and callus formation on the far cortex. This can lead to delayed union or nonunion issues if the fracture does not heal before the plate breaks.

MotionLoc Screw technology answers that challenge with controlled movement

Zimmer MotionLoc screws provide fixation in the far cortex of the diaphysis of the bone and are locked into the plate.  Without being rigidly fixed in the near cortex, these screws flex within a motion envelope with controlled movement. 

Zimmer’s observational study demonstrates faster and stronger healing with MotionLoc technology.  See Zimmer’s MotionLoc Screw Brochure for summarized outcomes data.5

Contact your Zimmer sales rep for the complete study results and analysis.

Surgical Technique

References

1. Boulton C, Chacko A, Appleton P, Rodriguez E: Factors For Increased Failure Rate of Locked Plating in the Treatment of Distal Femoral Fractures. Poster presented at the 78th Annual Meeting of the American Academy of Orthopaedic Surgeons, February 15-19, 2011, San Diego, CA.

2. Gross J, Serna F, Lybrand K, Qui X, Humphrey C, Gorczyca J: Surgical Approach Does Not Affect Union of Supracondylar Femur Fractures Treated with Plate Fixation. Poster presented at the 78th Annual Meeting of the American Academy of Orthopaedic Surgeons, February 15-19, 2011, San Diego, CA.

3. Henderson CE, Lujan TJ, Kuhl LL, Bottlang M, Fitzpatrick DC, Marsh JL: Healing Complications are Common after Locked Plating for Distal Femur Fractures. Clin Orthop Relat Res 2011; 469(6):1757-1765.

4. Skirving AP, Day R, Macdonald W, McLaren R: Carbon Fiber Reinforced Plastic (CFRP) Plates Versus Stainless Steel Dynamic Compression Plates in the Treatment of Fractures of the Tibiae in Dogs. Clin Orthop Relat Res 1987; 224:117-124.

5. Clinicaltrials.gov, Identifier NCT01667887

Achieve enhanced surgical flexibility with Zimmer MotionLoc Screws

Zimmer’s MotionLoc Screw technology was designed to work with the Zimmer NCB Locking Plating System, to enhance flexibility, during surgery, with polyaxial screw placement (30°) cone and improved angular stability. Equipped with a locking screw technology, Zimmer’s Minimally Invasive Solutions™ technique (MIS) enables surgeons to fully utilize NCB locking plate options to deal with complex fractures of the proximal humerus, the distal femur, and the proximal tibia. 

Figure 2: MotionLoc Screw Technology Concept

Zimmer’s MotionLoc Screw features

  • Concept: MotionLoc screws lock in the plate and the far cortex of diaphyseal bone. MotionLoc screws have a reduced diameter mid-shaft to bypass the near cortex. Under load, the screw will elastically flex to create interfragmentary motion at the fracture site until the shaft of the screw contacts the near cortex for added support and load sharing (Fig. 2).

  • Reduced Stiffness: MotionLoc screws provide flexible fixation by elastic bending of screw shafts. MotionLoc screws reduced the initial axial stiffness of a locked plating construct by up to 64%.6
  • Bi-Phasic Stiffness: At elevated loading and flexion, the near cortex of the bone will support the flexing screw shaft to provide a stiffness increase and reinforce the strength of the loading curve of a locked plating construct (Fig. 4).

  • Parallel Motion: The elastic deformation of the working length of the screws translates to a nearly parallel micromotion at the fracture site.  The working length of the screw is the area that essentially does all the work and flexes a controlled amount to create micromotion at the fracture site.  With a standard locking construct in a bridging technique, micromotion is only created at the far cortex (Fig. 3).

  • Load Distribution: MotionLoc constructs provide evenly distributed load sharing among all MotionLoc screws. In contrast, the end-screw of a standard locked construct induces a stress riser, which reduces construct strength in bending and torsion.7

Figure 3: Parallel Motion

Figure 4: Bi-Phasic Stiffness: 

References

6. Data on file at Zimmer. Please reference ZRR 2198-10-REV2

7. Bottlang, M. Doornick, J., Byrd, G., Fitzpatrick, DC, Madey, SM, A non-locking end screw can decrease fracture risk caused by locked plating in the osteoporotic diaphysis. JBJS-A, 91(3): 620-62, 2009.

Motion Loc Screw innovation is helping to improve fracture outcomes

Zimmer’s MotionLoc Screw innovation enables the surgeon to reduce the stiffness of the locking plate construct, while still maintaining the strength needed until the fracture begins to heal, helping to improve fracture outcomes. Watch Zimmer TV’s MotionLoc Screw surgeon testimonial video to learn why surgeons are choosing MotionLoc technology.

MotionLoc technology is based on the concept of Far Cortical Locking, which reduces the stiffness of locked plating constructs while still retaining the construct's strength.  The durability of MotionLoc fixation and periosteal callus assessment are shown in Figures 5 and 6, demonstrating faster and stronger healing with MotionLoc technology. (See Product Brochure for observational study.)

MotionLoc Screws look different than most cortical screws. The MotionLoc Screw’s innovative design generates parallel micromotion at the femur fracture site through elastic flexion of the screws to actively promote secondary bone healing circumferentially across the entire fracture gap. (See Surgical Technique, Fig. 1.)

Figure 5: Durability of fixation in presence of excessive weight-bearing in an ambulating patient with a body mass index of 56, weighing 157 kg. (Clinicaltrials.gov, Identifier NCT 01667887)

Periosteal callus assessment

Figure 6: Periosteal callus assessment: A) Average size of projected periosteal callus area at the medial, anterior, and posterior aspects. B) Periosteal callus distribution, shown to scale for different time points and locations. Percentages refer to the distribution of callus at a specific time. For example, of the total periosteal callus at week 6, 35%, 30% and 35% was deposited at the posterior, anterior, and medial cortex, respectively. C) Circumferential periosteal callus included callus formation on the lateral aspect adjacent to the plate. (Clinicaltrials.gov, Identifier NCT 01667887)

Zimmer® MotionLoc® Screw for use with the Periarticular Locking Plate System (Stainless Steel) – Surgical Technique

Zimmer MotionLoc Screw —designed for the complete NCB Polyaxial Locking Plate system

MIS Technique

The percutaneous plate and screw insertion technique continues Zimmer’s success in devising Minimally Invasive Solutions™ procedures. Requiring a smaller than normal incision, there is less damage to surrounding soft tissue and a reduced risk of complications with wound healing. 8,9,10

NCB Periprosthetic Femur Plate System

The NCB (Non-Contact Bridging) Periprosthetic Femur Plate System is a line of polyaxial locking plates for the treatment of femur fractures, particularly periprosthetic femur fractures.

NCB Proximal Humerus Plate

Oblique holes x 2mm can be used for sutures after plate osteosynthesis.

NCB Proximal Tibia Plate

Two versions of the NCB PT Plate are available: 2-proximal and 3-proximal holes. Plate head has 6° posterior tilt to match the lateral tibial contour.

NCB Distal Femur Plate

The polyaxiality of the system allows some varus/valgus correction during surgery. For this purpose insert four screws as shown in the figure without tightening the screws. Place the two distal screws anterior and posterior.

NCB Polyaxial Locking Plate System

Now the fracture can be reduced by rotation around the bone axis of the proximal fragment and varus/valgus correction of the distal fragment.

References

8. Biggi, F. et al.: Tibial plateau fractures: Internal fixation with locking plates and the MIPO technique, Injury - International Journal of the Care of the Injured, Vol. 41, p. 1178 – 1182, 2010.

9. Rüedi, T.P., Buckley, R.E., Moran, C.G.: AO Principles of Fracture Management - Second expanded edition, Volume 1-Principles, AO Publishing, Switzerland, 2007

10.  Resch H., Hubner C., Schwaiger R.: Minimally invasive reduction and osteosynthesis of articular fractures of the humeral head, Injury - International Journal of the Care of the Injured, 2001:(32 Suppl 1):SA25-32