Beijing, China, East, Dongcheng District, North Third Ring Road. Beijing Global Trade Center #36

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1 Ref: ES B 2 EN A France Technopôle de l Aube BP Troyes Cedex 9 France +33 (0) China Unit 08, Level 16, Building A, Beijing Global Trade Center #36 North Third Ring Road East, Dongcheng District, Beijing, China, Brazil Rua Bela Vista, No 77, Centro Sao Bernardo do Campo SP, CEP Brazil United States 4030 West Braker Lane, Suite 360 Austin, Texas LDR, LDR Spine, LDR Médical, BF+, BF+(ph), Easyspine, Laminotome, MC+, Mobi, Mobi-C, Mobi-L Mobidisc, ROI, ROI-A, ROI-MC+ and ROI-T are trademarks or registered trademarks of LDR Holding Corporation or its affiliates in France, the United States and other countries. P E D I C L E S C R E W S Y S T E M

2 Designed by leading spine surgeons, the Easyspine Pedicle Screw System features a simplified surgical technique and adaptable implants to accommodate varied anatomies Unique self-contained multi-axial connection Multi-axial joint is integrated into the pedicle screw Locking component is pre-assembled A new standard: the LDR flattened rod Variable stiffness with a constant diameter Choice of stiffness Flat-on-flat connection Protection safety stop Facilitates restoration of lordosis Mechanical optimization Reliable locking (flat-on-flat) Multi-axial freedom of movement Multi-axial locking Excellent physiological mechanical properties Sterility and traceability Sterile packaging Absolute traceability Optimized management Table of Contents Static Tests - Slippage Static Tests - Multi-axial Resistance Rod Stiffness Rod Deflection Static Testing Static and Dynamic Construct Testing Competitive Comparison A Summary and Comparison of Results for the Mechanical Testing Performed on the Easyspine System

3 Static Tests - Slippage To determine the slippage resistance of the Easyspine Rod-Screw Connection, the product was tested according To ASTM The worst case size was determined to be the Rigid (R) rod, since this size has the least surface contact. The construct was assembled with a torque of 8.5 N.m (75 in-lbs) according to the surgical technique. R Rod 14.0mm 2 M Rod 18.8mm 2 S Rod 19.6mm 2 Contact Surface The Easyspine multi-axial connection was able to withstand an axial load of 1400 N (314 lbs). Static Tests - Multi-axial Resistance F The Multi-axial resistance of the Easyspine rod/screw connection was tested and compared to published results of competitive systems*. The system was tested in a worse case scenario by measuring the force required to move the Rod/Screw angle from 80 to 90. It is important to note that the diameter of the screws for the Easyspine system was less than competitive systems tested (6.0mm vs for Stryker/DePuy). In addition the locking torque for Easyspine was 8.5 N.m (75 in-lbs), which is 30-50% less than that of competitive systems (13 N.m for Stryker and 15 N.m for DePuy). 80 Screw System Load to Failure (N) Screw Diameter (mm) Silhouette (Zimmer) BMI (Blackstone Medical) Moss Miami (DePuy) M8 (Medtronic) Click X (Synthes) SD 90 (Surgical Dynamics) Easyspine Alpha Screw (LDR) Xia (Stryker) Monarch (DePuy) Magnum (DePuy) *Guy R. Fogel, MD, Charles A. Reitman, MD, Weiqiang Liu, PhD, and Stephen I. Esses, MD. Physical Characteristics of Polyaxial-headed Pedicle Screws and Biomechanical Comparison of Load with their Failure. SPINE Volume 28, Number 5, pp (2003) 30 mm The Maximum Load for the Easyspine Alpha Screw without failure was determined to be 375 N (85 lbs). 2-3

4 Rod Stiffness LDR Rods Conventional Rods Comparison of Stiffness Between LDR Rods and Conventional Round Rods h Ø R Rod: M Rod: S Rod: h = 5.6mm h = 5.0mm h = 4.0mm Ø 5.9mm Ø 5.5mm Ø 4.6mm Elastic Limit for LDR Rods (Newton) R Rod M Rod Stiffness100% Stiffness 80% S Rod Stiffness 50% The Easyspine rods (R, M, S) are roughly equivalent to traditional round rods that are 5.9mm, 5.5mm, and 4.6mm. Rod Deflection Static Testing 5 million dynamic compression cycles were performed with a cyclic load ranging from 28 to 280 N according to ASTM F These tests were performed on the R Rods. Note that up to 280 N, the M and S rods are still within the elastic deformation zone. 35 mm F Blocking system Displacement After 5 million dynamic compression cycles there were no failures. 4-5

5 Static and Dynamic Construct Testing The Easyspine system construct was tested in accordance with Vertebrectomy Model defined in ASTM F Static Test To determine the elastic limit of a standard assembly Dynamic Test To determine a maximum load applied for a fixed number of cycle (5 Million Cycles) Locking torque 8.5 N.m With a loading cycle of 20 N to 200 N, the Easyspine Alpha Screw withstood 5 million cycles without breakage. Competitive Comparison It is important to note that the Easyspine system uses (as per the surgical technique) a lower locking torque than competitive systems (13 N.m for Stryker Screws vs. 8.5 N.m for LDR Screws). In addition, the diameter of the screws is less in the Easyspine testing than competitive systems tested (6.5mm for Stryker Screws vs. 6.0mm for LDR Screws). Static Testing Results Chart Screw System Elastic Limit (N) Screw Diameter Locking Torque Xia (Stryker Spine) mm 13 N.m Moss Miami Ti (DePuy) mm 10/15 N.m Tenor (Medtronic) mm 10 N.m Moss Miami SS (DePuy) mm 10/15 N.m Synergy VLS closed mm 14 N.m (Biomet) Synergy VLS open mm 11 N.m (Biomet) Easyspine Alpha Screw (LDR) mm 8.5 N.m Dynamic Testing Results Chart Screw System Load Screw diameter Xia (Stryker Spine) 220 N: Failure 6.5mm Moss Miami Ti (DePuy) 208 N: Failure 6.0mm Synergy VLS Closed (Biomet) 199 N: Failure 6.5mm Synergy VLS Open (Biomet) 219 N: Failure 6.5mm Easyspine Standard Screw (LDR) 280 N: No Failure 6.0mm Easyspine Alpha Screw (LDR) 200 N: No Failure 6.0mm Ralph Edward Stanford, FRACS, PhD, Andreas Herman Loefler, FRACS, Philip Mark Stanford, DipAppSci, and William R. Walsh, PhD, Multiaxial Pedicle Screw Designs: Static and Dynamic Mechanical Testing, SPINE Volume 29, Number 4, pp (2004) The Easyspine Standard Screw sustained a dynamic testing load of 280 N (63 lbs) without failure, outlasting competitive systems that failed under lower loads, all while using 30-50% less locking torque. 6-7

6 A Summary and Comparison of Results for the Mechanical Testing Performed on the Easyspine System Presented by: LDR Executive Summary The LDR Easyspine Pedicle Screw System was subjected to testing that confirmed its equivalence to other systems in the market. In the US, the Easyspine System is cleared for use as a posterior pedicle screw system intended for immobilization and stability of spinal segments when used as an adjunct to fusion in the thoracic, lumbar and sacral spine. There are specific tests required by the FDA and there are other industry-recognized tests that are performed to further distinguish a particular system over the competition. Testing of the LDR Easyspine Pedicle Screw System clearly demonstrated that it meets the standards for static and dynamic compression, as well as torsional stability characteristics. When compared to peerreviewed, published test results for other popular systems, Easyspine compares very favorably. When evaluated and compared for more specific attributes, the LDR Easyspine system demonstrates superior results. For example, load-to-failure testing clearly demonstrated that the LDR polyaxial screw has the highest resistance to shear failure of any published polyaxial screw in the market, having comparable thread diameters. In other words, the Easyspine screw is less likely to shear at the bone interface. Due to the unique rod design with flat locking surfaces, the LDR Easyspine system provides three rod stiffness options, with 1/3rd the inventory. Every rod in the system is compatible with every available diameter of Easyspine screw. In addition, the flat locking surfaces and fine thread in the integrated locking mechanism provide higher assurance of a secure lock with the polyaxial tightening screw at significantly lower torque values than any other system in the market. The patented Easyspine system provides all of the basic mechanical characteristics offered by competitive systems, yet clearly goes beyond those systems to provide much more in the form of assurance of system flexibility and relative mechanical properties. Test Methods To date, the Easyspine System has been subjected to all required tests and clearly demonstrated both its equivalence and superiority to other polyaxial pedicle screw fixation systems currently available in the market. In addition, the system has been subjected to additional testing and evaluation techniques to further distinguish itself as a better choice for a fusion system. Below is a description of the testing: ASTM F Standard Test Methods for Spinal Constructs in a Vertebrectomy Model: a) These test methods cover the materials and methods for the static and fatigue testing of spinal implant assemblies in a vertebrectomy model. b) These test methods are intended to provide a basis for the mechanical comparison among past, present, and future spinal implant assemblies. They allow comparison of spinal implant constructs with different intended spinal locations and methods of application to the spine. These test methods are not intended to define levels of performance. c) These test methods set out guidelines for load types and methods of applying loads. Methods for three static load types and one fatigue test are defined for the comparative evaluation of spinal implant assemblies. d) These test methods establish guidelines for measuring displacements, determining the yield load, and evaluating the stiffness and strength of the spinal implant assembly. There are essentially four tests defined by this ASTM standard which have been prescribed to evaluate the spinal implant assemblies. These are the same tests used to determine substantial equivalence to previously cleared spinal construct systems: three static mechanical tests and one dynamic test. The three static mechanical tests are 1) compression bending, 2) tensile bending, and 3) torsion. The dynamic test is 4) compression bending fatigue. Due to variability in designs and intended application of components, the ASTM test standards have been constructed with the intent to minimize variations when systems are compared to one another for potential in-vivo performance. They are only intended for comparison of relative mechanical parameters. Static Compression Bending Test: Run with a transverse bar to simulate the potential for additional fatigue generated at the site of the cross-connector clamp. (It is more critical to demonstrate this requirement in the compression fatigue test, but is usually utilized in the static test for consistency of test set-up). Static Tension Bending Test: Used to further differentiate fatigue properties of the polyaxial head, when needed. In general, this test is specific to cervical devices (typically plates) and not normally utilized for evaluation of thoraco-lumbar fixation systems. Static Torsional Test: Run without a transverse bar to simulate the weakest configuration - without additional torsional stability provided by a cross-connection (transverse bar). Compression Bending Fatigue Testing: Run with a transverse bar to simulate the potential for additional fatigue generated at the site of the cross-connector clamp. (As always, all testing should be done with the weakest and/or worst case configuration). The effect of environment may be significant. In order to provide consistent, relevant comparisons, these tests should be initially performed dry (ambient room conditions). The maximum recommended frequency for this type of cyclic testing should be 5 Hz. All testing should have a minimum of five (5) samples. The fatigue testing should result in at least two samples surviving 5,000,000 (minimum) cycles at a load with a difference of no more than 10% of the (static) compression bending ultimate load. Designation: F (Reapproved 2003): Standard Guide for Evaluating the Static and Fatigue Properties of Interconnection Mechanisms and Subassemblies Used in Spinal Arthrodesis Implants a) This standard covers the measurement of uniaxial static and fatigue strength, and resistance to loosening of the component interconnection mechanisms of spinal arthrodesis implants. b) The purpose of this standard is to provide a means of mechanically characterizing different designs of spinal implant interconnections. Ultimately, the various components and interconnections should be combined for static and fatigue testing of the spinal implant construct, (ASTM F ). Polyaxial Locking - Load to Failure: - (Variant of ASTM F : Evaluating the Static and Fatigue Properties of Interconnection Mechanisms and Subassemblies Used in Spinal Arthrodesis Implants): A test of the physical characteristics of the polyaxial locking mechanism and resistance to failure. In this case, the objective for Easyspine was to determine the (worst case scenario) load at which the recommended locking torque for the polyaxial screw would fail to hold the associate spinal rod when the screw was subjected to a cantilever load. Static Resistance to Sliding (Static Axial Grip Capacity Test) - (Variant of ASTM F : Evaluating the Static and Fatigue Properties of Interconnection Mechanisms and Subassemblies Used in Spinal Arthrodesis Implants): This test was performed to determine the amount of axial load (applied along the longitudinal axis of rod) that would be required to cause the rod to slip in the screw, after the polyaxial screw was tightened to the manufacturer s recommended torque. Dynamic Resistance to Sliding (Dynamic Axial Grip Capacity Test) - (Variant of ASTM F : Evaluating the Static and Fatigue Properties of Interconnection Mechanisms and Subassemblies Used in Spinal Arthrodesis Implants): This test was performed to determine the amount of dynamic axial load (applied along the longitudinal axis of rod) that would be required to cause the rod to slip in the screw, after the polyaxial screw was tightened to the recommended torque. Loads were determined based on a percentage of maximum static load achieved in the previous test. Significance and Use of ASTM standards Spinal implants are generally composed of several components (screws, hooks, rods, etc.) which, when connected together, form a spinal implant assembly. Spinal implant assemblies are designed to provide some stability to the spine while arthrodesis takes place. The ASTM test methods outline standard materials and methods for the evaluation of different spinal implant assemblies so that comparison between different designs may be facilitated. These test methods are used to quantify the static and dynamic mechanical characteristics of different designs assemblies. The mechanical tests are conducted in vitro using simplified load schemes and do not attempt to mimic the complex loads of the spine. The results obtained cannot be used directly to predict in vivo performance. However, the results can be used to further distinguish a system when compared to other system designs in terms of their relative mechanical potential. Finite Element Analysis: This is a computer simulation to demonstrate the stress magnitude and pattern that develops in each (screw) design when tested and validated per the ASTM 1717 benchmark for design performance. Rod Flexion / Stiffness Analysis: Is a measure of resistance to bending. The Elastic Limit is the greatest stress that can be applied to a material without causing permanent (bending) deformation. In the case of Easyspine, the rod stiffness (elastic limit) was measured to allow comparison to conventional (round) rods made from the same material (Ti6Al4V). 8-9

7 ASTM : Standard Test Methods for Spinal Constructs in a Vertebrectomy Model Static Compression Bending (Std. Screws) I MTS Scale Used 0-25kN Ø6 x L40mm Std. Screw Control: Displacement Speed: 10mm / min Screw Tightening Torque: 8.5 N.m Additional Static Compression Bending (Alpha Screws) II MTS 810 Scale Used 0-25kN Ø6 x L40mm Alpha Screw Control: Displacement Speed: 10mm / min Screw Tightening Torque: 9.5 N.m Specimens Test # Maximum Displacement Displacement Stiffness Load (mm) 2% of to 2% of Elastic (N) 1 Elastic Limit (mm) 2% offset Limit (N) yield Ø6 x L40mm mm R-rod Ø6 x L40mm mm R-rod Ø6 x L40mm mm R-rod Mean Specimens # of Test Mean Value of Yield Bending Mean Value of Maximum Samples Load on the Polyaxial Recorded Stress Connection (N) (N) Ø6 x L40mm Alpha Screw w/ mm R-rod Static Torsion Test (Std. Screws) III MTS Mini Bionix II Ø6 x L40mm Std. Screw Control: Angulation Speed: 10º / min Screw Tightening Torque: 8.5 N.m Specimens Test # Maximum Maximum Torque Angulation Stiffness Torque Torque to 2% to 2% of Elastic (N/º) (Nm) Angulation of Elastic Limit (mm) ( ) Limit (Nm) Ø6 x L40mm mm R-rod Ø6 x L40mm mm R-rod Mean (Dynamic) Compression Bending Fatigue Test (Std. Screws) IV ESM with a capacity of 10kN Ø6 x L40mm Std. Screw Control: Load Load Applied: 50% 25% % % of max static compression bending load (1118 N) Ratio: 0.1 Frequency: 5 Hz Duration: 5,000,000 cycles or failure of implant assembly Screw Tightening Torque: 8.5 N.m Specimens Test # % of Load Amplitude Numbers Type of Maximum Cycles of of Cycles Failure Static Load Applied Displacement Achieved Observed Obtained (N) (mm) Ø6 x L40mm to ,486 Broken Screw 100mm R-rod to ,000,000 No Failure to ,759,153 Broken Screw to ,000,000 No Failure to ,785,253 Broken Rod to ,000,000 No Failure Additional (Dynamic) Compression Fatigue Testing (Alpha Screws) V ESM with a capacity of 10kN Ø6 x L40mm ALPHA Screw Control: Load Load Applied: 50% - 25% % % of max static compression bending load (1118 N) Ratio: 0.1 Frequency: 5 Hz Duration: 5,000,000 cycles or failure of implant assembly Screw Tightening Torque: 8.5 N.m Specimens Test # % of Load Numbers Type of Maximum Cycles of Cycles Failure Static Load Applied Achieved Observed Obtained (N) Ø6 x L40mm to 100 5,000,000 No Failure Alpha Screw w/ 90mm R-rod to 150 5,000,000 No Failure to 200 5,000,000 No Failure to , to ,829 Broken Screw at PE Block Interface 2 Broken Screws at PE Block Interface N = Newton: A metric measurement of Force. (1 N lbs.; or, 1 lb N)

8 Comparison of Easyspine Test Results to Literature : For direct comparison of results between the Easyspine System and other commercially available polyaxial pedicle screw systems, we turn to literature. The most relevant recent reference is by Stanford, et al., published in Spine in February, 2004 vi. Table 1 - Specifications and Construction Torques for Screw Assemblies v * Tenor design locked by failure of a shear nut. # Root diameter of screw measured immediately below rod screw link, this either tapered to a smaller diameter at the tip or was constant to the tip (straight). Torque applied to locking screw for the Alpha Screw design only. Torque applied to inner and outer locking nuts, respectively. Screw Design Manufacturer Material Outer Screw Root Screw) Rod Locking Diameter (mm) Diameter (mm) Diameter (mm) Torque (Nm) Easyspine Std. & LDR Titanium alloy tapered / 9.5 Alpha Screws Tenor Medtronic Titanium alloy tapered * Moss Miami (SS) DePuy Stainless Steel straight /15 Moss Miami (Ti) DePuy Titanium alloy straight /15 Xia Stryker Spine Titanium alloy tapered Synergy VLS Biomet Titanium alloy tapered (Open) Synergy VLS Biomet Titanium alloy tapered (Closed) Table 2 - Static and Dynamic Compression Structural Properties of Assemblies by Screw Design Static Data Dynamic Cycles to Failure (at described loads x 10 3 cycles) Screw Screw 2% Ultimate 50% Load 75% Load Design Diameter (mm) 2% Offset of Elastic Bending Load Actual Load Actual Load Yield (N/mm) Limit (N) (N) Easyspine N 420 N Std. Screw (5,000) (3759) Tenor N (5,000) 498 N (4,719) Moss Miami (SS) Moss Miami (Ti) N (4,280) 312 N (42) Xia N (4,394) 337 N (106) Synergy VLS (Open) N (5,000) 219 N (987) Synergy VLS (Closed) N (532) 298 N (110) Alpha Screw Screw Yield Ultimate 50% Load * 79% Load * Design Diameter 2% Offset Bending Bending Actual Load Actual Load (mm) Yield (N/mm) Load (N) Load (N) Easyspine Alpha 6.0 Not Recorded N 250 N Screw Design (5,000) (643) Table 3 - Number and Mode of Failure of Screw Designs in Static and Compressive Loading to Failure Static Compression Failure Dynamic Compression Failure Screw Number Tested Mode Number Tested Mode Design out of 5 out of 5 Easyspine (α) 5 No Rotation of the Rod 25% Fracture of screw at the PE test block Alpha 6.0mm VII Longitudinal Slip of 50% interface, no slip of link or fretting. Rod/screw Link Interface 63% Rods tipped in α-screw cradle at 10º 75% in relation to screw axis. Tenor 1 Rotational Slip of Rod/screw Link 25% Fracture of rod adjacent to 50% rod / screw link, 75% no slip of link or fretting. Moss Miami (SS) 5 Rotational Slip of Rod/screw Link Moss Miami (Ti) 5 Rotational Slip of Rod/screw Link 25% Fracture of neck of screw, 50% just below rod / screw link, 75% no slippage or fretting. Xia 5 Rotational Slip of Rod/screw Link 25% Rotational slip of rod / screw link, 50% with cracking of neck of 75% screw adjacent to link. Synergy VLS 5 Rotational Slip of Rod/screw Link 25% Rotational slip of rod / screw link with (Open) 50% cracking of link casing and fretting 75% of serrated components. Synergy VLS 5 Rotational Slip of Rod/screw Link 25% Rotational slip of rod / screw link with (Closed) 50% cracking of link casing and fretting 75% of serrated components. Discussion of Results from Typical Static and Dynamic Testing : By itself, the raw data is not really that telling, however, when one compares the results of the Easyspine system with the data from various well known systems available in the market, one begins to note that the Easyspine screws provide significant advantages in terms of relative mechanical parameters. For example, both the Alpha and Standard (6.0mm) Easyspine screw designs have a higher static yield bending load than any other 6.0mm screw, while the Standard design has significantly better properties in nearly every category. When compared to conventional rod and screw systems tested by independent evaluators and published in peer-reviewed journals, the Easyspine System is the only system that had no rotational slippage between the rod and locking screw during static or dynamic testing. This could imply that the surgeon should be less concerned about the potential for de-rotation of the spinal segments when using the Easyspine System. As noted previously, these test methods are used to further quantify the static and dynamic mechanical characteristics of design assemblies. These mechanical tests are also conducted in vitro using simplified load schemes and cannot mimic the complex loads of the spine. The results obtained cannot be used directly to predict in vivo performance. However, the results can be used to further distinguish a system when compared to other system designs in terms of their relative mechanical potential. Slippage Tests ASTM F : Standard for Evaluating the Static and Fatigue Properties of Interconnection Mechanisms and Subassemblies Used in Spinal Arthrodesis Implants A slippage test demonstrates the ability of the system to resist movement between the rod and the locking screw once the system is assembled with the appropriate tightening torque. Assembly was tested according to ASTM ALL tests were conducted made with the R Rod *** and a locking torque of only 8.5 N.m. Additionally, one should note that these results were obtained using the Easyspine polyaxial screw that has a self-contained locking screw that requires a lower tightening torque than most (if not all) other screws in the market

9 Illustrations of the three types of rods are provided below. *** The R rod has the smallest contact surface area (and highest stiffness) for the rods in the Easyspine system. R Rod 14.0mm 2 (Rigid) M Rod 18.8mm 2 (Medium) S Rod 19.6mm 2 (Slender) Contact Surface Static Resistance to Sliding Test - (Rod / Std. Screw Axial Gripping Capacity) MTS Scale Used 0-25kN Control: Displacement Speed: 2mm/min Screw Tightening Torque : 8.5 N.m Specimens Test # Maximum Load Displacement of Obtained (N) Maximum Load (mm)** Ø6 x L40mm mm R-rod Mean ** Displacement of Maximum Load: Failure of grip strength was deemed to have occurred when the rod was able to slip under the polyaxial head a distance of approx. 0.2mm (or the approx. equivalent to 2.5 x the thickness of a human hair). (Dynamic) Resistance to Sliding Test - (Rod / Std. Screw Axial Gripping Capacity) ESM Scale Used 0-25kN Control: Load Load Applied: 75% - 80% - 85% of max static load (1399 N) Ratio: 0.1 Frequency: 5 Hz Duration: 2,500,000 cycles or failure of implant / connection Screw Tightening Torque: 8.5 N.m Specimens Test # % of Load Numbers Type of Maximum Cycles of Cycles Failure Static Load Applied Achieved Observed Obtained (N) Ø6 x L40mm 1 75% 100 to ,500,000 No Break or Sliding 60mm R-rod 2 80% 110 to ,500,000 No Break or Sliding 3 85% 120 to ,500,000 No Breakage - Sliding between the Screw and the Screw and Rod occurred at the very end of the test Polyaxial Locking - Load to Failure: for the Alpha (α) Screw These diagrams represent a variation of the screw angle from 80 to 90 respectively. In order to test a worst case loading scenario, it was necessary to determine the load needed to deflect or break the connection between the multi-axial Alpha (α) screw head and rod, from an extreme, locked position (80 ) to a point approaching 90, (the theoretically strongest position). A1 B1 X2 A1 B1 X2 For 5 alpha screws (Ø 6mm), the results of the maximum force required to shift the rod / screw axis angle from 80 to 90 were 481N, 439N, 419N, 187N, and 344N. The average of these 5 results is 375 N. It should be noted that there was no breakage of the screw or polyaxial mechanism, only the locking torque resistance (8.5 Nm) was overcome. Comparison of Easyspine Results to Peer-Reviewed, Published Data Additional peer-reviewed published literature which provides further direct comparison of load-to failure results between commercially available polyaxial pedicle screw systems can also be found in Spine. The most relevant reference for this comparison is by Fogel, et. al, published in Spine in February, 2003 VIII. Utilizing a modified version of ASTM F , the author compared the loads to failure for nine different polyaxial pedicle screws. For comparison, the test results for the Easyspine Alpha screw is shown in shaded format to the right. Screw System Load to Failure (N) Screw Diameter (mm) Silhouette (Zimmer) BMI (Blackstone Medical Inc) Moss Miami (DePuy) M8 (Medtronic) Click X (Synthes) SD 90 (Surgical Dynamics) Alpha (α) Screw (LDR) Xia (Stryker) Monarch (DePuy) Magnum (DePuy) Analysis and Conclusions from Slippage and Locking Mechanism Evaluations : One should note that the static load required to overcome the resistance to slippage between the rod and the locking screw (1399 N) for the Std. Easyspine screw, was 25% greater than the static compression bending load (1118 N) noted previously for the Easyspine System. When comparable published data could be found, the Easyspine system demonstrated clearly superior results. The results from the load-to-failure testing of the polyaxial pedicle screws, presented by Fogel et. al,, demonstrates that the weakest point of the construct is the head-to-screw coupling. The author suggests that this failure of the polyaxial head may be a protective factor for the pedicle screw shaft, preventing early breakage. However, the author fails to note that the load-to-failure for most designs of polyaxial screws is in direct correlation to the cross-section of the screw at the polyaxial swivel joint. This cross-sectional diameter is controlled by a function of the minor diameter of the screw thread and the major diameter of the polyaxial head that must swivel over the ball-joint at the end of the screw head. As demonstrated above, all screws tested (with the exception of Moss Miami and Easyspine), were between 6.5mm and 7.5mm in diameter). The Easyspine Screw provides a uniquely different (patented) solution to this limitation by incorporating the polyaxial swivel within the self-contained locking screw in the head of each screw. Subsequently, there is no built-in stress-riser or weak point at the bone interface, (polyaxial ball-joint). The only strength limitation of the screw is the minor diameter of the thread itself, which is stronger than any polyaxial ball-joint found in typical polyaxial screws, similar to those described by the Interpore-Cross / Biomet 555 patent. Additional System-Specific Tests : In support of the analysis and conclusion drawn above, the Easyspine screw design was subjected to a detailed Finite Element Analysis (FEA) to determine the magnitude and pattern of stresses which could develop when subjected to the simulated loading scenario required by the various ASTM testing protocols. Additionally, the Easyspine rods were evaluated for stiffness and compared to conventional round titanium rods. Finite Element Analysis of the Easyspine Polyaxial Screw IX The finite element method was used to evaluate three different pedicle screw design configurations: Alpha size 5, Standard size 5, and Standard size 6. The stress magnitude and pattern that develops in each design when tested per ASTM 1717 was used to benchmark the design performance. Methods: Finite Element models of each design were constructed using LDR CAD files in STEP format. The files were imported into the FEA environment (FEMAP), where the meshing and boundary conditions were applied to simulate ASTM 1717 testing. Because only the screw component of the spinal fixation assembly was simulated, an equivalent load was applied to the screw as determined by rigid body mechanics. All designs were simulated using the same boundary conditions (fixation point and equivalent load). Each FEA model was tested against a rigorous validation and verification protocol. All models demonstrated appropriate accuracy for the required application, with differences from closed form approximations of less than 10%. For the available configurations (size 5 Alpha and size 6 Standard), the FEA correctly predicted the failure location as observed in real-world tests. Complete model details, validation and verification, and results are documented in ProbaSci reports: Finite Element Analysis simulating ASTM 1717 testing on LDR's Pedicle Screw Design Alpha, size 5; Finite Element Analysis simulating ASTM 1717 testing on LDR's Pedicle Screw Design Standard, size 5; Finite Element Analysis simulating ASTM 1717 testing on LDR's Pedicle Screw Design Standard, size 6. Results: Figure 1 A-C shows the FEA predicted stresses for each design. The stress magnitudes in the expected failure zone were: Alpha size MPa, Standard size MPa, and Standard size MPa. All three screw design configurations exhibited the same pattern of stress. The highest stresses were observed in the threaded region, near to the constraint location, with the head regions experiencing much lower stress. When subjected to this loading, all three designs are expected to fail in the same location: in the threaded region, near the constraint point. The difference in the Alpha size 5 and the Standard size 5 is 17 MPa, which is 4% of the predicted stress. This difference is within the estimated model errors and is therefore too small to be practically significant. In other words, the Alpha size 5 and Standard size 5 designs perform equally, within the error of the model. While the Standard size 6 demonstrated similar stress patterns as the Standard 5 and Alpha 5, the magnitude of the stress was about 1/2 of the size 5 designs. It should be noted that these FEA findings represent a very powerful method of analysis. Due to the highly variable nature of real world fatigue tests, an equivalent real world test protocol would require a very large amount of samples in order to detect a 4% difference in design performance

10 Comparison Alpha 5, Standard 5, and Standard 6 Fig. 1- A. (Alpha 5) Fig. 1- B. (Standard 5) Fig. 1 C. (Standard 6) Figure 1: FEA predicted stresses during ASTM 1717 for screw design configurations: (A) Alpha size 5, (B) Standard size 5, (C) Standard size 6. Conclusion: The Alpha size 5, Standard size 5, and Standard size 6 all demonstrate similar FEA predicted stress patterns when simulating ASTM 1717 loading. The Alpha size 5, Standard size 5, and Standard size 6 all demonstrated much lower stresses in the head section than in the threaded section. The Alpha size 5, Standard size 5, and Standard size 6 could all be expected to fail in a similar location that is in the threaded region, near the constraint point. The Alpha size 5 and Standard size 5 demonstrated equivalent stresses. The Alpha size 5 stress was 419 MPa and the Standard size 5 was 402 MPa. The Standard size 6 had approximately 1/2 the stress level as the Standard size 5 and the Alpha size 5 under identical loading. The Standard size 6 stress was 219 MPa. In short: By relocation the polyaxial mechanism to the inside of the screw head, only the minor diameter of the thread affects the strength of the screw construct, not the polyaxial connection, as with all other conventional designs. Finally: In addition to the FEA performed on the screws, the mechanical characteristics of the rods were determined using both mechanical and theoretical analysis methods. LDR Rods - Flexion Test and Comparison Flexion test protocol Flexion Tested Rods Rod's length F 35 mm Blocking system R Rod M Rod S Rod Displacement Flexion test results on LDR Rods (Elastic limit for each type of LDR rods) Load (Newton) R Rod M Rod S Rod - 5 million dynamic compression cycles were performed with a cyclic load ranging from 28 to 280 N according to ASTM F These tests were performed on the "R" Rods. - All LDR rods have a constant Ø6.0mm, with a variable (milled cross-section) height, roughly corresponding to industry accepted diameters for Ø4.0mm, Ø5.0mm, and Ø6.0mm rods - One should note that up to 280N, the "M" and "S" Rods are still within the elastic deformation zone. Comparison of Stiffness Between LDR Rods and Conventional Round Rods In bending, the deflection is determined by the following equation: F: applied force f = Fl 3 / 3EI : f: deflection l: rod's length E: Young modulus I: moment of inertia If one compares the deflection calculation with an LDR Rod and with a round Rod, the only variation is the moment of inertia. The calculation of the moment inertia implies the equivalence of the following stiffness: LDR Rods Conventional Rods Analysis / Comparison of Results for the Easyspine Rods: As noted in the in-vitro results presented above the unique design for the Easyspine system rods will afford essentially equal performance compared to any standard 6.0mm round titanium rod offered by any other system and superior results for stiffness when compared to any other 5.0mm or 4.0mm round rod. Again, one should note that any size rod offered in the Easyspine System can be used interchangeably with any size screw in the system. The net result of this means that the surgeon need never worry about the ability to match the appropriate rod stiffness and fusion stability of a construct to match the need of the patient, regardless of screw size. The results presented cannot be used directly to predict in vivo performance. However, the results can be used to further distinguish a system when compared to other system designs in terms of their relative mechanical potential. Summary: R Rod: M Rod: S Rod: h h = 5.6mm h = 5.0mm h = 4.0mm Ø 5.9mm Ø 5.5mm Ø 4.6mm Ø Testing of the LDR Easyspine System clearly demonstrated that it meets all safety and efficacy standards for static and dynamic compression, as well as torsional stability characteristics. When compared to peerreviewed, published test results for other popular systems, Easyspine compares very favorably. When evaluated and compared for more specific attributes, the LDR Easyspine system demonstrates superior results. For example, load-to-failure testing clearly demonstrated that the LDR polyaxial screw has the highest resistance to shear failure of any published polyaxial screw in the market, having comparable thread diameters. This is further confirmed and validated by FEA. In other words, the Easyspine screw is less likely to shear at the bone interface. Further, testing has demonstrated the ability of the alpha screw to withstand higher failure loads (locking torque resistance) than any other polyaxial screw of comparable diameter. Due to the unique rod design with flat locking surfaces, the LDR Easyspine system provides three rod stiffness options, with 1/3rd the inventory. Every rod in the system is compatible with every available diameter of Easyspine screw. In addition, the flat locking surfaces and fine thread in the integrated locking mechanism provide higher assurance of a secure lock with the polyaxial tightening screw at significantly lower torque values than any other system in the market. The patented Easyspine system provides all of the basic mechanical characteristics offered by competitive systems, yet clearly goes beyond those systems to provide much more in the form of assurance of system flexibility and relative mechanical parameters. Bibliography I CRITT Report # B : Static and Dynamic Tests of Compression and Torsion on Easyspine Implants According to ASTM F 1717 and ASTM II LNE - Laboratoire National D Essais - Test Report: Dossier D Document CQPE/2, April 10, 2003; Mechanical Characteristics of the Easyspine (Ø6.0mm) α-screw by Means of Static and Dynamic Tests. III IV CRITT Report # B : Static and Dynamic Tests of Compression and Torsion on Easyspine Implants According to ASTM F 1717 and ASTM CRITT Report # B : Static and Dynamic Tests of Compression and Torsion on Easyspine Implants According to ASTM F 1717 and ASTM V LNE - Laboratoire National D Essais - Test Report: Dossier D Document CQPE/2, April 10, 2003; Mechanical Characteristics of the Easyspine (Ø6.0mm) α-screw by Means of Static and Dynamic Tests. VI Multiaxial Pedicle Screw Designs: Static and Dynamic Mechanical Testing; Ralph E. Stanford, FRACS, PhD, Andreas H. Loefler, FRACS,, Philip M. Standford, DipAppSci, and William R. Walsh, PhD; SPINE Volume 29, Number 4, pp (2004) VII LNE - Laboratoire National D Essais - Test Report: Dossier D Document CQPE/2, April 10, 2003; Mechanical Characteristics of the Easyspine (Ø6.0mm) α-screw by Means of Static and Dynamic Tests. VIII IX Physical Characteristics of Polyaxial-headed Pedicle Screws and Biomechanical Comparison of Load with their Failure: Guy R. Fogel, MD, Charles A. Reitman, MD, Weiqiang Liu, PhD, and Stephen I. Esses, MD SPINE Volume 28, Number 5, pp (2003) ProbaSci Final Report - June 7, 2005: Comparison of FEA Results for the Alpha Size 5, Standard Size 5, and Standard Size 6 Easyspine Pedicle Screw Designs