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The products and testimonials that you will be reviewing describe the efficacy and return to function of our patients after joint replacement surgery. This is the most critical part and ultimate mission of Endotec.

These products have been biomechanically designed and expertly manufactured to provide long-term fixation and function in both mild and severe cases of arthritis.

Whether or not you are a candidate for one of these prostheses will depend upon your personal symptoms and your orthopaedic surgeon’s expert opinion. Feel free to show your orthopaedic surgeon any of the information provided on this website to help in your decision making. Good Luck in your quest for pain free function! Best Wishes, Frederick F. Buechel, M.D., F.A.C.S

Introduction: Endotec’s Role
The benefits and risks associated with joint replacement are greatly dependent on design and materials. Superior design and choice of materials can substantially improve device function and minimize potential problems and complications. Endotec feels it is at the forefront of design and use of materials. A prime example of Endotec’s concern for proper design is that Endotec the leading orthopaedic implant manufacturer to use mobile bearings in its ankle joints thus avoiding the problem of articular surface overloading present in the fixed bearing knees and ankles currently available.

With regard to materials, Endotec employs titanium alloy coated with a propriety TiN ceramic called UltraCoat®. Titanium is superior to Cobalt Chrome alloy (Co-Cr), the most widely used material for metallic implants, with regard to important physical properties such as strength, stiffness and biocompatibility. However, a few years ago when titanium was used for prostheses, it was found that the relatively poor abrasion resistance of titanium caused several problems that led to the virtual exclusion of titanium for orthopaedic implants. Endotec considers the solution to the problem of poor abrasion resistance to be the use of a very hard ‘UltraCoat’ ceramic coating. This abrasion resistant ceramic coating allows all the advantages of titanium to be employed while eliminating its major disadvantage. Thus, Endotec feels it now has the best metallic implant material available today.

UltraCoat, apparently, has an additional major advantage. Our testing has shown that wear of UHMWPe is dramatically reduced when it is articulated against UltraCoat compared to the conventional Co-Cr surface. Parts coated with UltraCoat have been in clinical use for over 15 years. The Endotec UltraCoat process is also licensed to DePuy orthopaedics (a Johnson & Johnson Company) and to Wright Medical for use in prostheses.

Endotec is dominated by research and development activity. Our research and development costs and efforts greatly exceed those of our marketing and sales. Endotec’s primary interest is to design and make the best orthopaedic products available, regardless of profit. This is why Endotec is a small company, and will probably remain so. We may be out of step with market and economic realities, but our determined dedication to the advancement of science and technology is the source of our inspiration and pride.

Above all, the purpose of all this research and development is to benefit the patients: to develop and manufacture implant products that materially affect a patient’s quality of life for the better; to eliminate pain, restore lost function, and, thus, to free patients from torment, and help restore them to a near normal life. Accomplishing this is the source of our greatest satisfaction.

Benefits
The replacement of a painful and dysfunctional joint will usually eliminate, or at least greatly reduce pain, and restore most, if not all, lost function. Thus a patient, after a period of recovery and rehabilitation that may last several months, can begin to recover the ability to live and enjoy a life with normal, although not extremely demanding, activities. Work, except for those jobs that require strenuous physical activity, can resume, as can other daily activities and even some sporting activities such as golf and swimming. Another benefit is the reduction or elimination of dependence on drugs with their related side effects.

It is important to realize that a mechanical replacement joint is not a true replacement. It is inferior to the average normal healthy human joint it replaces. One cannot expect a replacement to provide total restoration of function or to be capable of the same longevity as a normal healthy joint.

Risks
An understanding of the risks associated with joint replacement is important to joint replacement patients, to aid them in deciding to have it done, the best device to choose, and how to manage the risks involved. Activity places loads and motion on the joint. Joint loads and motions affect the joint. More strenuous and frequent activities produce greater and more frequent loads and motions on the joint and thus affect the joint more aggressively. Mechanical devices degrade with use. Replacement joints are not an exception to this rule. The more strenuous and frequent the use, the greater the risk of sufficient degradation to produce those conditions that required replacement originally. Thus, it is wise to exercise caution in the use of a joint replacement to extend its longevity

Operative Risks
Most joint replacement procedures are major operations performed under general or regional anesthesia. Such procedures have a significant risk associated with them. The major risks are described below.

• General anesthesia can result in death. This risk is typically about 0.01%. Further, it can produce, particularly in the elderly, a degradation of mental capability. This latter complication is not well understood.
• Blood clots can form or fat emboli produced during the operation can produce strokes or death. Efforts are made through postoperative medication, usually anticoagulants, and mechanical means, such as intermittent compression devices and support hose, to minimize this complication. Still the death rate associated with such complications is typically about 0.1%.
• Poor wound healing sometimes associated with infection is a significant complication. The rate of complication varies widely for different joints. Problems tend to become worse for joints further from the center of the body. The operation may require the resection (cutting) of important soft tissue such as muscles, ligaments, or tendons. Some soft tissue may be removed producing some loss of function.

Infection
There are two basic types of infection. These are superficial infection and deep infection. Superficial infection is associated with infection of the skin and tissue near it. The bone supporting the prosthesis is not infected. If it is, one has a deep infection.

Superficial infection is normally produced by contamination of the outside of the wound. Patients should take great care to see that such contamination does not occur. Often inadequate blood supply resulting from the surgical incision, or former incisions, contributes to the problem. Antibacterial drugs and protection of the wound control such infection. Usually this is not a serious complication as the infection can be controlled. Any infection, however, is dangerous. If it is not controlled, it may become a deep infection where control becomes much more difficult.

Deep infection is a serious problem. Infection of the bone itself is very dangerous and difficult to manage. Such infection can progress to limb loss or even death. Furthermore, the presence of an implant increases the danger and difficulty to the point where often re-operation is required to remove the implant before the infection can be controlled. This procedure and problem can result in substantial loss of bone. If the infection can be controlled and bone loss is not excessive, an implant can often be re-implanted. The prognosis for success of the revision is dependant on the damage done as a result of the infection. The overall deep infection rate for most joints is typically about 1-2%.

Metal Sensitivity
This complication has not been well understood, and has only recently received the attention it deserves. Endotec’s experience indicates that about 1% of joint replacement patients may be sensitive to one of the alloying elements of Co-Cr or stainless steel alloys, the most widely used implant metals. Such sensitivity can produce swelling and pain in the joint. Thus, joint function can be adversely affected and the need for implant removal can develop. Patients who expect to have a Co-Cr or stainless steel implant should have their physician check for sensitivity to the alloying elements of the materials before implanting them.

Titanium has not been found to produce any measurable sensitivity effect. Thus, if a patient is sensitive to Co-Cr or stainless steel, titanium implants can probably be used. Endotec implants are well suited for such use since titanium implants are available for all joints replacements it has available. Endotec titanium implants are all coated with a ceramic TiN coating. Such a coating is needed to provide an abrasion resistant surface on the metallic implants.

Dislocation
The disease or trauma producing the need for joint replacement may damage soft tissues associated with the joint. Furthermore, the surgical insult associated with replacement can produce additional damage. Thus, a replaced joint may not be as stable as the natural joint. Poor prosthetic design, surgical procedure and instrument design can negatively affect stability as can lack of surgical skill. Thus, dislocation is a significant complication associated with joint replacement. Patient activity can also produce dislocation. Thus, patients are encouraged to carefully follow instructions of medical personnel during and after Rehabilitation. Usually dislocations can be treated without resort to a re-operation. Braces or casts may be used. Occasionally re-operation may be required to correct the cause of the dislocation or even to allow reduction of the joint to its proper position. Primary hip replacements dislocate at a rate of 1 to 3%, while revision hip replacements dislocate at higher rates of up to 30%. Other joint replacements have similar dislocation rates.

Loosening
Elements of the prosthesis are attached to the bone several ways. The most common is the use of cement, which impregnates the bone and holds the prosthesis to it. Another common method is to use a porous surface on the prosthesis into which bone grows holding the prosthesis. This is called biological fixation. Occasionally the implant will simply be pressed into the bone. This method is called press-fit fixation.

• Cement is a well-proven fixation method that has been in use for more than 45 years. Nevertheless, there are problems associated with its use. Cement is a brittle material with little resistance to the repeated loads experienced by joints. Furthermore, it has little adhesive properties. It acts simply as a grouting agent to fill the gaps between prosthesis and bone helping the bone to support the prosthesis.
• Loading and motion of the joint can produce fracture of the cement mantle and separation of the cement from the prosthesis. This separation results in motion and thus rubbing between the prosthesis and cement. This rubbing produces wear particles that are not well tolerated by the bone and produce local bone loss. Such loss makes the prosthesis loose and produces pain and loss of function and may require re-operation. Further, such bone loss greatly increases the difficulty of revision to a new prosthesis and greatly reduces the chance of a successful result.
• Biological fixation is a technique, which is used to fix metallic prostheses to bone. It avoids the problems associated with cement but it introduces its own problems, which need to be dealt with. Cement fracture and its effects are eliminated. Cement wear particles, the dominant reason for bone loss, are eliminated. Metallic wear debris is reduced but is still present and can result in damage to bone and adjacent soft tissue.

The most important problem introduced by biological fixation is poor initial fixation. Cement provides instant, excellent, initial fixation. This fixation may degrade with time and use but it is usually excellent initially. Fixation of a porous coated device initially relies on a press fit, which may be difficult to achieve. Further, there is no initial impregnation of the fixation means into the bone and thus, such press fit is inferior to cement in attaching the prosthesis to bone. Biological ingrowth, or impregnation, relies on a stable connection between prosthesis and bone. If relative motion is not essentially eliminated, ingrowth will not occur and biological fixation will not be achieved. The ability to control this relative motion is dependent on the design of the prosthesis and surgical instruments, and the design of the surgical procedure used to implant the prosthesis as well as the skill of the surgeon doing the implantation.

Because of the need to eliminate movement between prosthesis and bone so that ingrowth can occur, partial or complete immobilization of some joints may be needed. Such immobilization is often undesirable and is a disadvantage of this fixation method. The effect of the degree of motion and the effect of this immobilization is highly device specific. Although loosening is a significant potential complication in any joint replacement, it is greatest in hip replacement.

All Endotec joint replacement implants, instruments and procedures for implanting them are carefully developed to provide sufficient initial stabilization to enable ingrowth, and thus biological fixation, to occur. This provides the benefits associated with the elimination of cement. Furthermore, all Endotec metallic implants in contact with bone are coated with a highly abrasion resistant coating which is totally biologically inert such that metallic wear debris is entirely eliminated and replaced with a much smaller amount of totally inert ceramic debris. Such debris does not appear to damage bone. Of course, Endotec products can be used with cement. They are; however, designed for biological fixation, which we feel, is superior to cement for most patients, particularly younger patients.

Component Fracture
Although component fracture was a significant problem in the past, improvements in design, manufacture and metallurgy have all but eliminated this as a risk factor.

Wear
Wear is the most common and serious complication associated with replacement joints. Almost all replacement joints employ a polyethylene, usually ultra high molecular weight polyethylene (UHMWPe), bearing articulating (rubbing) against a polished metal surface. Such an articulation usually cannot provide a lifetime joint in a young, active, patient. It has a limited lifespan. These limits are heavily device dependant.

Efforts to reduce wear in joint replacements have been a major area of research and development activity for at least the last decade. These efforts are of two basic forms.

The first is an effort to develop an improved polyethylene. No improved polyethylene has yet been demonstrated clinically. Several earlier attempts at polyethylene improvement have resulted in clinical failure, where the “improved” material had greater wear clinically than conventional polyethylene. Current claims of improved “cross-linked” polyethylene usually seem suspect. Where Endotec has run a wear test on polyethylene made by a process intended to reduce wear, it has found that wear was actually greatly increased.

In the other form, alternate articulating materials are used. Here, there are currently three methods in use. Two of these are ceramic-on-ceramic and metal-on-metal, which appear to be applicable only to completely congruent joints such as the hip. The third is ceramic-on-polyethylene.

Ceramic-on-ceramic holds considerable promise of essentially solving the wear problem. Wear products should be low in volume and relatively well tolerated by the body. It is, unfortunately, the most difficult solution to implement. Formulation of the ceramic is complex and critical. Extreme accuracy of manufacture is required. Difficult design problems needed be solved. These include avoidance of excessive bone removal for implantation and the avoidance of fracture associated with the brittleness of ceramics.

Metal-on-metal is now in use in Europe and available in the USA. Despite much enthusiasm, a downside appears to be metal-metal neck cup impingement in hip replacements that results in increased metal wear debris. Long term metal wear debris may have more negative effects than polyethylene wear debris. Endotec feels that it is risky technology that is counter to conventional engineering practice of avoiding rubbing of similar metals so as to avoid adhesive type wear. Since it is unconventional, proofs justifying its use should be particularly rigorous. Rather the opposite is true. Claims of proponents of this approach are scientifically weak. Further wear tests performed by Endotec show the expected. Similar metal-on-metal articulation (of the materials proposed and used) results in poor wear performance and much wear debris.

Ceramic-on-polyethylene is also widely employed in Europe and available in the USA and has been shown by both mechanical and clinical testing to substantially reduce polyethylene wear. Most implementations of this approach use a ceramic femoral head assembled onto a metallic femoral stem articulating against a polyethylene acetabular bearing or cup. The ceramic implementation problems are greatly reduced, compared to ceramic-on ceramic, but remain. Fracture of the femoral head is a significant complication.

Endotec uses a different form of ceramic-on-polyethylene. Endotec uses a ceramic coating “UltraCoat” on a titanium substrate rather than an all-ceramic component. The problem of ceramic brittleness is thus avoided and a superior ceramic surface can be obtained. The implementation problems associated with this approach are now associated with the development and control of an optimal coating. Endotec has devoted the last decade to the development and refinement of our coating methods. This process has been licensed to other manufacturers that are now using them on their products.

Mechanical wear testing shows that UltraCoat greatly reduces polyethylene wear compared to Co-Cr alloy normally used for femoral heads. The coating has been used clinically since 1989. A detailed clinical evaluation is now underway to examine the clinical effect of the coating. Preliminary results indicate that wear, although still present, is reduced.

The problem of wear is particularly acute in load bearing, incongruent contact joint replacements such as most knee and ankle prostheses. Using conventional engineering evaluation methods the contact stresses during walking for most such designs are such that they seem clearly to be unsuitable for general human use. Such devices are usually overloaded producing rapid wear of the UHMWPe due to surface break up from fatigue or repeated overstress.

These designs are not recommended. Endotec avoids this fundamental problem in its ankle design by the use of mobile bearings, which allow mobility with congruity. However, we cannot sell them in the USA except as part of clinical trials that have ended.

Control of Risks
First and foremost a patient should find a surgeon that is knowledgeable in the evaluation of implant designs and skillful in their implantation. If you need an implant, educate yourself as much as possible in what kind of implant is best for you. Discuss implant selection and evaluation with your surgeon. Try to establish that the implant the surgeon suggests is scientifically sound is clinically proven, and that the surgeon is well trained in its implantation.

Immediately postoperatively, take care to protect the wound and keep it clean. Attentively follow surgeon and physical therapist’s instructions, and take any medications as prescribed. Further, avoid those activities and positions that may induce dislocation of the joint.

To decrease the risks associated with long-term use one should be careful not to overload or over use the joint. Remember, a joint replacement is not equal to the natural joint. It has limitations of strength, stability, wear and perhaps function and motion. A mechanical device will degrade with time and use. Remember, the more aggressive this use, the greater this degradation.

Conclusion
Joint replacement can provide great benefits if the right device is implanted and used properly. There are, however risks associated with replacement, as we have discussed at length. You can increase the benefits and reduce the risks if you make sure that the surgeon uses a well-designed and proven device. Select the surgeon carefully so that the device will be properly implanted and used. Carefully follow the instructions of the medical personnel helping you adapt to the implant.

Although much has been made of the risks associated with joint replacement, do not be discouraged from having such a replacement performed! If you make the effort to understand these risks, they can be minimized to make your joint replacement even more successful. Well-designed and properly implanted prostheses have a high success rate, and a 15-year survival rate exceeding 95%.

Keep in mind the benefits: the great reduction or elimination of pain; the great reduction or elimination of the use of drugs, the need for their effects and unwelcome side-effects; the potential for improving your fitness, health and lifestyle. In addition, if you take care to control the risks, the benefits may clearly outweigh the risks justifying your decision to have a joint replacement. You can make the most of it. It is your body, your life.

Choose wisely and enjoy life!

South Mountain Orthopaedic Associates website	Arthritis Foundation website
Buechel Patient Care and Research Education Fund website	American Academy of Orthopaedic Surgeons website
Frederick Buechel, Jr MD "My Approach to Treating Patients"