*smith&nephew SL-PLUS Cementless Femoral Hip System. Product Information

Transcription

1 Product Information *smith&nephew SL-PLUS Cementless Femoral Hip System

2 First Came the Philosophy to develop a universal hip system that could be used in almost every indication, immaterial to the patient s age. Since its first implantation over 30 years ago, the cementless straight stem with its rectangular, double-tapered form has, according to Professor Karl Zweymüller, proved itself to be a reliable system over a hundred thousand times worldwide, with predictable and reproducible results. Our many years of exclusive work with Professor Zweymüller led over 15 years ago to the further development of the SL-PLUS stem that reflects the sum of clinical experience with his revolutionary, biomechanically based anchoring concept. Thanks to the consistent application of Professor Zweymüller s experience over 30 years and its clinical use throughout the world, the SL-PLUS stem now sets the international standard. It has therefore earned the name GOLD STANDARD. 02 Product Information

3 SL-PLUS Perfect primary and secondary stability Unique double-taper straight stem Optimal anchorage due to taper geometry Optimal transmission and distribution of force Force transmitted over a large cortical area in both projection planes (cortical multicontact anchorage) Optimized rotational stability Rectangular cross section Characteristic proximal-lateral trochanteric wing Proximal press-fit Anatomically matched calcar arch and prominent trochanteric wing Strong osteointegration Optimally designed surface roughness of 4 8 μm Best possible anatomical fit Anatomically matched range of sizes Biomechanically ideal rigidity Biocompatible, high-strength forged titanium alloy Rectangular design Good ROM Proximally tapering neck Sparing the endosteal blood vessel supply Rectangular stem shape not completely filling the medullary cavity 03

4 SL-PLUS Stem System Cortical multicontact anchorage Due to the precisely defined taper angle, cortical deposition distributed evenly over the entire stem length is achieved. This leads to the transmission of forces over a broad area in the metaphyseal and diaphyseal regions in both projection planes. 100 μm 1 mm 100 μm Mean roughness R = 4 8 μm Trabecular integration over a wide area, 8 magnification Bone trabeculae with direct titanium-bone binding, 50 magnification Osteointegration As a result of the special microstructuring of the biocompatible titanium alloy with a mean roughness of 4 8 μm, the surface of the SL-PLUS stem performs a strong osteointegration. 04 Product Information

5 SL-PLUS Precise preparation and bone compression Proximally there is broad, close contact between the SL-PLUS stem and the cancellous bone compressed with the special SL-PLUS rasps. Distally, the stem edges penetrate into the prepared endosteal cortex. This fixation is strengthened further by torsion and vertical forces. Rectangular tapered shape of the SL-PLUS stem The rectangular cross section requires minimum excavation of the medullary cavity. The cortical support at the edges provides optimal primary anchorage. The calcar arch flows smoothly into the distal stem segment. This creates a continuously changing curvature over the entire stem length that approximates to wedge geometry in both the sagittal and frontal planes. Endosteal blood supply The unique design of the SL-PLUS stem brings another biological advantage: it leaves enough room for nutritional supply of the bone from the medullary cavity; this is confirmed histologically by the complete secondary osteointegration of the stem. Anatomically matched stem sizes A total of 14 stem sizes for the SL-PLUS Standard stem and 12 sizes for the SL-PLUS Lateral stem for primary interventions cover all anatomical requirements throughout the world. The specific size increments were developed by a computer-assisted series of measurements, so that the system can provide an optimal fit and the intraoperative choice of the correct size is made easier. These distinct advantages have been validated in hundreds of thousands of implants. 05

6 SL-PLUS Stem System Physiological transmission of forces to the implant tip The taper at the prosthesis tip is rounded and changes smoothly into a pyramidal tip. The result is no tension spots in the distal diaphyseal area. Proximal press-fit The anatomically matched calcar arch and the prominent trochanteric wing enlarge the proximal anchoring surface and support the accentuated proximal press-fit. This guarantees optimal metaphyseal anchorage. Rotational stability The specially formed trochanteric wing, with its enlarged surface, supports the initial anchorage and, together with the rectangular base profile of the SL-PLUS stem, provides enhanced rotational stability. Biomechanically ideal rigidity SL-PLUS Ti 100% CoCr 200% Biomechanically ideal rigidity By using high-strength cast titanium alloy the rigidity of the stem is reduced by 50% compared to a cobalt-chrome stem of the same geometry. With the same medullary cavity size, the rectangular titanium stem has about one-third the rigidity of a cobalt-chrome stem filling the medullary cavity. Elliptical fit and fill cross-section Ti 160% CoCr 320% The material properties of the titanium alloy plus the rectangular stem design form an optimal combination of high-strength and biomechanically ideal rigidity. High degree of freedom of movement On average, the SL-PLUS stem with a 28 mm ball head provides a head-neck diameter ratio of 2.51, which corresponds to an exceptionally high ROM of 125. This minimizes the risk of impingement. 06 Product Information

7 SL-PLUS Survival Rate 98.1 %* The impactor is positioned along the long axis of the stem. Due to the precise coaxial direction of the broaching, the quality of the primary fit is increased since tilting moments are inhibited during impaction. The extractor with screw thread, also axially orientated, avoids any tilting moment during withdrawal of the implant. Good ROM The proximally tapering neck allows a wide range of movement for the patient. In the lateral transition to the stem, the neck expands gradually. Medially it merges into the anatomically matched calcar arch and thus provides maximal safety under continuous stress. Material Forged titanium alloy, Ti6Al7Nb Surface roughness R = 4 8 μm Range 14 stems varying in length from mm with proportionally increasing offset for the SL-PLUS Standard stem 12 stems varying in length from mm with proportionally increasing offset for the lateralized stem CCD angle 131 Standard stem 123 Lateralized stem Cone 12/14 * The Kaplan-Meier survivorship curve showing a 98.1% rate of implant survival at ten years with revision of the stem as the end point (95% confidence interval: %) Zweymüller KA, Schwarzinger UM, Steindl M. Acta Orthop. 2006; 77(6):

8 SL-PLUS Lateral Stem based on the biomechanical principles of the SL-PLUS Standard stem. The SL-PLUS Lateral stem has been designed to optimize the lateralization of the femur (offset) in revision surgery. Lateralization also increases the soft-tissue tension, which has the advantage of preventing luxation of the head out of the cup. Sometimes the use of the SL-PLUS Lateral stem may require the use of a shorter neck than would be used with the standard stem. This helps to avoid lengthening the leg inadvertently. The use of the SL Lateral stem is thus indicated in the following situations: to prevent an undesirable medialization of the femoral stem in the case of insufficient soft-tissue tension to reduce the risk of postoperative luxation to compensate for leg length discrepancies The SL-PLUS Lateral stem does not restrict the range of movement, which is the same as with the SL-PLUS Standard stem. The height of the rotation center remains unchanged compared to the SL-PLUS Standard stem. 08 Product Information

9 SL-PLUS Biomechanical Concept Reconstruction of the anatomically correct offset is a basic concern. For this reason, it is essential to achieve hip stability through ideally functioning abductor strength. There are, however, patients with different bone morphologies. For these cases, the SL-PLUS Lateral stem offers additional flexibility in individual provision because of its larger offset (6 to 8.5 mm, see table below). The SL-PLUS Lateral stem allows reconstruction of anatomical conditions and soft-tissue balancing in special cases without leg lengthening. + Offset Center ball head 28/M SL-PLUS Lateral stem Center ball head 28/M SL-PLUS Standard stem Size Size Size Size Additional offset ball head 28/M (mm) Distance ball head center 28/M Size Size Size Size Size Size Size Size

10 The Double Taper The double taper of the SL-PLUS Lateral stem is based on that of the SL-PLUS Standard stem. The rectangular cross section, the outstanding biocompatibility of the titanium alloy and the surface roughness are identical to those of the SL-PLUS Standard stem. The concept of the anatomically adapted size increments of the SL-PLUS Lateral stems corresponds to that of the Standard stems. This is why the offset increases from the smallest to the largest size. The CCD angle is 123 for the SL-PLUS Lateral stem compared to 131 for the SL-PLUS Standard stem. The ROM of the SL-PLUS Lateral stem corresponds to that of the SL-PLUS Standard stem. Case Study Patient male, 58 years. Dysplastic coxarthrosis on the right. Long femoral neck on the left. Postoperative result after implantation of a SL-PLUS Lateral stem. Precise adaptation of the offset to the contralateral side, equal leg length. 10 Product Information

11 SL-PLUS SL-PLUS Integration based on the biomechanical principles of the SL-PLUS Standard stem. The SL-PLUS stem is coated in a 0.3 mm open-pore titanium plasma layer and a 0.05 mm hydroxyapatite (HA) layer. The diameter of the proximal section of the SL-PLUS stem is thereby 0.7 mm larger than the diameter of the standard stem. The advantage of the hydroxyapatite coating, as described in the literature, can be summarized as follows: stimulating bone regeneration accelerating osteointegration bridging the gaps between the implant and the bone by up to several millimeters. The latter is especially important, as with surgery there is almost always the risk of smaller or greater distances between the implant and the bone as a result of preparing for the implantation. With the HA coating these gaps can be bridged more quickly and, more significantly, over greater distances than if prostheses are used that do not have a coating. This thickening also increases the contact in the sensitive proximal region and increases the prestrain fixation. SL-PLUS stems with HA have been in use since

12 Manufacturer Smith & Nephew Orthopaedics AG Oberneuhofstrasse 10d 6340 Baar Switzerland Contact For further information please contact our local sales office. Trademark of Smith & Nephew Lit. No e Ed. 03/