Arcos Modular Femoral ™ Revision System Design Rationale Knees • Hips • Extremities • Cement and Accessories • PMI® • Technology Arcos Modular Femoral Revision System ™ Surgeon Developers The design team for the Arcos™ platform includes surgeons with vast experience in addressing complex revision hip situations. Each brings a different philosophy to the design to ensure that various implant and surgical technique preferences were incorporated into the platform. The design team includes the following: • Hugh Apthorp, FRCS, Conquest Hospital, Hastings, UK • John Barrington, M.D., Texas Center for Joint Replacement, Plano, TX, USA • Keith R. Berend, M.D., Joint Implant Surgeons, New Albany, OH, USA • J. Rod Davey, M.D., University Health Network, Toronto, ON, Canada Figure 1: Arcos™ Modular Femoral Revision System consists of three proximal and five distal stem bodies. • Andrew Freiberg, M.D., Massachusetts General Hospital, Boston, MA, USA Introduction • Edward McPherson, M.D., Los Angeles Orthopaedic Institute, Los Angeles, CA, USA Revisions involving the femur continue to be one of the most difficult operations faced by surgeons today. • Christopher Peters, M.D., University of Utah, Salt Lake While the published clinical results for revision total hip City, UT USA arthroplasty have shown favorable results, leg length • Ian Stockley, FRCS, The Northern General Hospital, discrepancies and instability are still a concern. Leg Sheffield, UK length discrepancies and instability can be addressed by implant design. One-piece and modular femoral stems System Overview have been used for the past twenty years to address femoral revision cases. However, modular implants provide The Arcos™ Modular Femoral Revision System is a surgeons the flexibility to adjust leg length and apply the comprehensive, press-fit revision femoral component necessary anteversion or retroversion to address stability. consisting of three proximal and five distal stem bodies In addition, both metaphyseal and diaphyseal defects may with multiple designs for reconstruction of various defects be addressed independently. associated with femoral revision surgery. Auxiliary implants are available to aid in fixation and include trochanter Biomet was at the forefront of implant design for revision reattachment claws, bolts and interlocking screws. This hip arthroplasty with the introduction of the Modular system is for use with Type I taper modular heads Calcar System in 1992. This revision system was one and compatible acetabular shells/liners and screws. of the first modular systems to address complex Components are available in a variety of designs and femoral reconstruction with a porous coated, modular sizes to offer 117 proximal/distal combinations for various calcar-replacing proximal body and modular distal femoral defects. stem segments. Biomet was also the first company to address taper strength at the modular junction with the introduction of Roller Hardening Technology in 2000. The Arcos™ Modular Femoral Revision System builds upon the clinical success of this platform, design philosophies and technology while expanding the options available to address varying needs of patients and surgeons (Figure 1). Surgical Technique and The Arcos™ Modular Femoral Revision System is Instrumentation intended for the following indications: The Arcos™ instrumentation is simple and intuitive. Common 1. Noninflammatory degenerative joint disease proximal implant and instrument geometries (Figure 2) including osteoarthritis and avascular necrosis allow for intraoperative revision efficiency, reducing the number of instruments required to a number comparable 2. Rheumatoid arthritis to a primary hip surgery. In addition, the platform design provides the flexibility to use any implant combination 3. Correction of functional deformity with the surgical technique that is required to address the 4. Treatment of non-union, femoral neck fracture needs of the patient. This platform allows the implant to be and trochanteric fractures of the proximal femur assembled in any of the following ways: with head involvement, unmanageable using • Back table/sterile field other techniques • Preparation of the proximal femur after the distal stem is implanted (ream-over) 5. Revision of previously failed total hip arthroplasty • Locking of the modular taper once the proximal and distal segments are inserted into the femur Relative contraindications include: 1. Uncooperative patient or patient with neurologic disorders who is incapable of following directions 2. Osteoporosis 3. Metabolic disorders which may impair bone formation 4. Osteomalacia 5. Distant foci of infections which may spread to the implant site Figure 2: Common Implant and Instrument Geometry 6. Rapid joint destruction, marked bone loss or bone resorption apparent on roentgenogram 7. Vascular insufficiency, muscular atrophy, Detailed System Description or neuromuscular disease In femoral revisions, it is necessary to address deficiencies of the metaphysis and the diaphysis independently. The use of a modular system can be a valuable tool when Absolute contraindications include infection, sepsis, addressing proximal to distal mismatch. The Arcos™ and osteomyelitis. Modular Femoral Revision System offers implant options to address deficiencies in both regions of the femur to accommodate the specific needs of the patient and the surgical procedure and implant preference of the surgeon. 1 Arcos Modular Femoral Revision System ™ Proximal Body Design Broached Proximal Body Vertical body height options: 60mm The Arcos™ system includes broached, calcar replacing Size options: A–F and cone proximal body options to meet various patient According to the Mallory classification of femoral defects, needs, along with the surgeons’ preferred technique Type I and II femoral defects involve severe loss of and femoral reconstruction philosophy. All proximal body cancellous bone, minimal damage to the calcar and intact options are available in standard and high offsets (Figure 3), diaphyseal cortex (Figure 5).9 The broached proximal with a reduced proximal profile (RPP) option to address a body (Figure 6) design addresses these defect types. This wider range of femoral revision requirements. In addition, proximal body is an anatomic fit and fill geometry designed all proximal bodies are coated with Biomet’s clinically to provide initial stability and bone contact. proven PPS® (Porous Plasma Spray) coating to allow for initial scratch-fit stability and biologic fixation.1–8 high offset (130°) standard offset (135°) Type I femoral defect Type II femoral defect Figure 3: All proximal body options are available in standard and high offsets. Figure 5: The broached proximal body is designed for Type I and II femoral defects. To simplify implant nomenclature the proximal body size is labeled A,B,C,D,E,F or G. The smallest size (A) has a distal diameter of 18.5mm over the PPS® coating. The distal diameter of each body increases 2mm (1mm per side) per increased size increment (e.g., size B distal diameter is 20.5mm). 60mm vertical height Figure 6: The broached proximal body is an anatomic fit and fill geometry designed to provide initial stability and bone contact. 1mm per side Figure 4: The distal diameter of each proximal body increases 2mm (1mm per side) per increased size increment. 2 Calcar Proximal Body Cone Proximal Body Vertical body height options: 50 and 60mm Vertical body height options: 50, 60, 70 and 80mm Size options: 50mm: A 60mm: A–F Size options: 50mm: A 60–80mm: A–G The calcar replacing proximal body is designed for cases If the proximal femur does not require proximal femoral that involve deficiencies in the medial calcar where loading or if the proximal femur is too small to accommodate proximal femoral support is desired. Type IIIa, IIIb, and IIIc a fit and fill style implant, cone bodies can be used (Figure 9). femoral defects are defined as violations of the proximal The Arcos™ cone body offers a three degree tapered body femur above, into and below the lesser trochanter, and four different vertical height options (Figure 10). The respectively (Figure 7).9 To address these various defect implant design and vertical height options allow for the types, the calcar replacing body offers three resection level preparation of the proximal femur after the distal stem is options: 0, +10 and +20 (Figure 8). implanted to achieve the desired vertical offset and version adjustment (Figure 11). Broached body silhouette Cone body Figure 9: When the proximal femur is too small to accommodate a fit and fill style implant (broached body), the cone body option can Type IIIa femoral defect Type IIIb femoral defect Type IIIc femoral defect be used. Figure 7: The calcar replacing proximal body is designed for Type IIIa, IIIb and IIIc femoral defects. 0 +10 +20 Figure 10: The cone proximal body has a three degree tapered body and four different vertical height options. Figure 8: The calcar replacing body offers three resection level options: 0, +10 and +20. Figure 11: The cone proximal body design allows for the preparation of the proximal femur after the distal stem is implanted to achieve the desired vertical offset and version adjustment. 3 Arcos Modular Femoral Revision System ™ Auxiliary Implant Designs Distal Stem Design One of the unique aspects of modular revision implants The Arcos™ system offers five distal geometry options offered by Biomet has been the ability to use a bolt and to address differing quality of diaphyseal bone, desired claw auxiliary implant to reattach the trochanteric fragment fixation and surgical technique. This system offers both directly to the modular proximal body. The first generation clinically proven PPS®1–8 coated and grit blasted distal of implants required the bolt to be captured medially. stem options. Biomet has a long clinical heritage of coating The Arcos™ system allows for a lateral only attachment its implants with titanium PPS® coating, which helps of the bolt to the implant (Figure 12). This new design achieve long-term fixation and implant stability. Biomet reduces the risk of bolt loosening and provides accurate has also offered splined stems blasted with a rough blast measurement. By reattaching the fragment in this method, media to provide additional fixation and rotational stability. the soft tissues and bony fragment are stabilized, providing Both splined and PPS® coated stems have been shown an added level of joint stability. to withstand the rotational forces seen in the femur during daily activities.10 PPS® Coated Distal Stems Arcos™ PPS® coated distal stem options provide for fixation throughout the diaphysis. The Arcos™ system offers a slotted, bullet-tip and interlocking PPS® coated stem design. All PPS® coated stem designs utilize the same instrumentation, allowing for intraoperative flexibility. These stem options are available in multiple lengths to address differing severities of diaphyseal defect. All PPS® coated distal stem diameter options are sized to include the PPS® coating as indicated on the implant packaging. Figure 12: The Arcos™ system allows for a lateral only attachment of For example, a 12mm stem, as labeled, measures 12mm the bolt to the implant. over PPS® coating. The cobalt chrome (CoCr) claw is offered in 100mm lengths with two options; a full profile for larger trochanters and a reduced profile for smaller trochanters (Figure 13). These CoCr claws also have the option to utilize a cable attachment for additional stability of the implant and bone fragment. 100mm Both have grooves to accept cable attachments Narrower claw Wider claw option option Figure 13: The cobalt chrome (CoCr) claw is offered in 100mm lengths in full and reduced profile options. 4 Slotted Distal Stem Bullet-tip Distal Stem Stem design and length options: bowed stem Stem design and length options: straight stem available in 150, 200 and 250mm lengths available in 115mm; bowed stem available in The bowed, coronal slotted distal stem design matches 150, 200 and 250mm lengths the natural anatomy of the femur to reduce the risk of The bullet-tip distal stem design is fully PPS® coated with anterior impingement, allowing for extended distal fixation a polished bullet-shaped distal tip that provides a gradual and a gradual separation from the cortex designed to separation from the cortex to reduce distal stresses. reduce thigh pain. Figure 14: The slotted distal stem is a bowed stem design with a Figure 15: The bullet-tip distal stem is fully PPS® coated with a coronal slot. polished bullet-shaped distal tip. 5 Arcos Modular Femoral Revision System ™ Interlocking Distal Stem STS™ (Splined Tapered Stem) Distal Stem Stem design and length options: bowed stem Stem design and length options: straight stem available in 200, 250 and 300mm lengths available in 150 and 190mm lengths The interlocking and bullet-tip distal stems are similar. When an intact diaphysis is present, a non-coated, splined, However, the interlocking distal stem option incorporates tapered stem provides a viable option for fixation, particularly interlocking screw holes that are inserted percutaneously when the defect is superior to the femoral bow. The Arcos™ for initial rotational stability in complex femoral STS™ distal stems are splined to maximize rotational reconstruction. stability and blasted with a rough 30 grit blast media to provide a biologic fixation surface. The three-degree Note: Distal stems and interlocking screws pending taper transfers load from the proximal to the distal portion 510(k), not available for sale in the United States. of the femur, thus reducing stress shielding. In addition, the 190mm stem design incorporates an anterior relief to reduce the risk of anterior impingement. The diameter on the splined distal stem option is 1mm larger than indicated on the implant packaging to allow for press-fit beyond the reamed diameter. Figure 16: The interlocking distal stem is fully PPS® coated with a Figure 17: The STS™ distal stem is splined with a three-degree taper polished bullet-shaped distal tip and interlocking screw holes. and 30 grit blast media. 6 ETO (Extended Trochanteric Osteotomy) Roller Hardened Taper Junction Distal Stem The use of a modular junction is a requirement for any Stem design and length options: kinked stem system that allows for modularity. Although modular taper available in 250mm length junctions have been in use since 1992, the issue of a taper Extended trochanteric osteotomy provides surgeons with junction fracture is always a concern. To reduce the risk of a valuable tool in the revision of a well-fixed cementless fracture, there are different methods for strengthening the stem and/or for the removal of cement in unsuccessful taper junction. Biomet is the only manufacturer that uses cemented applications. In these cases, it is difficult to a patented roller hardening manufacturing process for the utilize a splined stem and often a fully porous coated modular taper junction. Roller hardening is a specialized stem is used. The femur below the osteotomy is often process used to compress or “work harden” the taper able to support a splined stem, but when replacing the region of the distal stem. This process increases the trochanteric fragment there is need for biologic fixation. hardness of the titanium alloy metal at the interface of the To address this common need, the Arcos™ system offers taper junction, thus making the construct more resistant a stem specifically designed for these surgical situations. to fretting.11 Greater resistance to fretting translates into The ETO stem provides dual mode fixation for stability in significantly greater fatigue strength of the modular distal both the intact diaphysis and for repair of the trochanteric stem. This manufacturing technology reduces the risk of fragment. taper fractures in comparison to machined-only tapers.11 The Arcos™ ETO distal stem is the first modular stem in the industry to combine two forms of fixation; PPS® coating for biologic fixation and grit blasted splines that allow for bone on-growth. These are combined on one distal stem option to provide dual mode fixation in complex femoral reconstruction when extended trochanteric osteotomy is necessary. dense metal surface Figure 19: This picture of the roller hardened taper (mag x100) shows the dense metal at the surface (note the bracket), caused by the roller hardening process. This creates greater resistance to fretting and thus higher fatigue properties.11 In addition to the use of roller hardened tapers, it is also imperative to protect the taper junction in cases where the proximal femur is deficient. The use of medial or lateral strut grafts to protect the modular taper junction is critical in these types of situations. Figure 18: The ETO distal stem combines two forms of fixation; PPS® coating and grit blasted splines to provide dual mode fixation. 7 Arcos Modular Femoral Revision System ™ Proven Fixation – PPS® Porous Plasma Spray Coating Biomet was the first orthopedic company to introduce a plasma-sprayed prosthesis with the release of the PPS® coated Taperloc® hip stem in 1982. The Arcos™ Modular Femoral Revision System features this same PPS® coating, a proprietary process that is instrumental to Biomet’s clinical success. The PPS® plasma spray application is unique in that only the titanium powder used to create the coating is heated, while the implant’s substrate is retained at near ambient temperatures (Figure Figure 21: The irregularly shaped titanium particles sprayed onto the substrate result in a wide pore size distribution. 20). This unique process enables the implant to maintain its mechanical properties and has been shown to help guard against osteolysis and allow both immediate and Biomet’s PPS® coating has irregularly shaped molten long-term fixation.4–8 titanium particles that splatter upon impaction with the substrate surface (Figure 21), creating a micro-rough The heating effect of the PPS® process is transient (lasting texture and generating a wide distribution of pore-size only milliseconds). Therefore, the substrate material between 100 and 1,000 microns. The larger distribution remains virtually unaffected and the fatigue properties are of pore size, in conjunction with micro-rough texture and maintained. enhanced biocompatibility of titanium, allows for immediate fixation via mechanical interlocking and long-term biologic fixation. This has enabled Biomet PPS® coating’s clinically proven success for over 20 years which has been documented in a variety of published clinical papers.1–8 Figure 20: Titanium PPS® (Porous Plasma Spray) coating being applied through a heated plasma arc. 8