25 Years Of Biologic Fixation
In 1979, the Austrian surgeon, Prof. Dr. Karl Zweymüller revolutionised the orthopaedic world when he carried out the first hip replacement operation without using bone cement. To date almost one million operations have been carried out worldwide following his philosophy.
The hip unit - the SL-PLUS hip stem and the Bicon-PLUS cup - owe their reputation to the partnership between Karl Zweymüller and PLUS Endoprothetik AG, and both parties met in Vienna 25 years on to celebrate the landmark, as did OPN’s Alex Dodd.
The pioneering idea of cementless implantation occurred to Professor Zweymüller 25 years ago. If it were possible to anchor hip implants directly in the bone, without using bone cement, there would be a range of significant advantages to the patient. Today this is confirmed by around one million satisfied patients worldwide and a series of long term studies.
His vision of biological fixation of hip implants was revolutionary. How was cementless fixation to withstand the constant dynamic forces applied to the hip joint? Ultimately, after a hip operation, the patient wants to walk, sit, run, ride a bicycle, climb, in short, fully enjoy life again.
Biological fixation dispenses entirely with the use of bone cement as a “binder” and thereby with any foreign material between the implant and bone. Instead it relies on a perfectly conceived implant design and the power of the bone tissue to mend itself. This development – known in technical language as “osteointegration” – is among the most valuable achievements in modern orthopaedic surgery.
The principle behind the fixation has not changed in over two decades and has proved itself a hundred thousand times. In contrast, the material and design of the implants are constantly being tested and refined. Long term studies and regular evaluation of international operative experiences assist in subsequent further development and detailed refinement of the system, so that the high quality of implants, and of the instruments required for the operation, can be guaranteed in future.
This year, biological fixation is now celebrating its 25th anniversary, which is a milestone in cementless hip endoprosthetics. Professor Zweymüller and PLUS Endoprothetik AG - a leading company in the field of orthopaedic implants and the developers of the SL-PLUS hip stem and the Bicon-PLUS cup - met in Vienna to acknowledge the occasion and discuss the impact of biological fixation.
Press Conference: 01.10.04
Members of both the Trade and Public Press from all over Europe gathered at the Café Griensteidl, to attend the press conference for ‘25 Years of Biologic Fixation’ – a pre-cursor to Saturday’s Symposium.
The attendees were given a presentation by Professors’ R. F Santore, H-G. Willert, F. Lintner, K-H. Widmer, F. Higuchi; with Professor Zweymüller giving his presentation first.
Professor Zweymüller is Medical Director and Head of Department at the Gersthof Specialist Orthopaedic Hospital in Vienna. The hospital performs over 1,000 major joint implants (hip and knee joints) and over 400 arthroscopies and hallux valgus operations each year. Since 1991, Prof. Zweymüller has been working in collaboration with EndoPlus in the fields of research and product development.
Prof. Zweymüller talked about the evolution of the SL PLUS stem and Bicon-PLUS cup, which form a hip prosthesis system described as the Gold Standard®.
He explained that the original stem has undergone a number of changes: from the shape, to the type of metal it is made from – now a reinforced titanium wrought alloy, which has proved itself to be the best tolerated by the body. Also, the ball is ceramic – a bold move away from the traditional metal ball joint. When asked if he thought things would turn out the way they have, he announced “No. I never thought things could be like this. I think we should be happy with the way things have turned out, and where we are right now.”
Prof. Santore (left), from San Diego, California, talked about why he thought the cementless method is superior, and what problems have arisen in the past from using bone cement. He stated that the cementless method of Prosthesis is compatible with the growth in population – as the population expands, so does the number of people who need hip replacements.
He also talked about recovery time: the time from operation to regaining mobility can be less than three days – quite an astonishing fact: “Many patients can get up the day after the operation and walk.” He told the press that the SL Plus stem is a friendly option for surgeons who do as few as 20 prosthesis a year, as positioning the stem is not as critical as it is when cement is used.
At the end of his presentation, Prof. Santore presented Prof. Zweymüller with a bottle of Wine from the Bordeux region of France, which was bottled in the same month as the first cementless prosthesis was performed by the Austrian surgeon.
Prof. Willert (right) highlighted the two distinct groups of surgeons – the cemantates – those who use cement, and the cementless – those who don’t. He briefly outlined the history of bone cement – from its first use in 1902, to its worldwide production after WWII. He told the press that patients who had undergone a cementless prosthesis complained less of being in pain than those whose prosthesis relied on cement. He explained the problems with cement, saying that in some cases there is toxicity in the patient – which could even result in death. He summed up by saying that the technology in biologic fixation is more advanced than cement prosthesis.
Prof. Lintner (left) explained the importance in monitoring prosthesis, and stated that with the cementless implant, it was easier to monitor the outcome of the surgery. He gave the example of a woman who had the same implant for 25 years - it was found to be totally stable even after she had died.
Prof. Higuchi (right) from Japan, explained that the SL Plus stem is very helpful in the practice of Minimally Invasive Total Hip Arthroplasty and Prof. Widmer from Switzerland concluded by saying that he is treating more and more young patients. He said that sportsmen and women are able to undergo a hip replacement and carry on with their sports as normal.
Prof. Santore concluded rounded off the presentation with some video clips of his patients, mobile without any walking aids, only days after their surgery. He also said that he had operated on another surgeon – the operation took place on a Monday and he was back to work on the Friday – “No crutches, no cane, and no pain”!
Symposium: 02.10.04
The symposium took place on Saturday, and saw over 1,000 Orthopaedic Surgeons from all over the world meet to hear presentations from surgeons who use the SL Plus hip stem.
The location of the symposium was the decadent Concert House, which is more used to hosting operas than Orthopaedic conferences. Amongst the speakers were Professor Santore, M. Steindl and B. Kou – who travelled from the Arthritis Institute in Peking, China.
Minimally Invasive And Small Incision
Joint Replacement SurgeryWhat Patients Should Consider
Authors: American Association of Hip and Knee Surgeons (AAHKS)
Purpose
The purpose of this position statement is to provide information to patients about the emerging use of minimally invasive and small incision techniques in the practice of hip and knee joint replacement surgery.
Background
Hip and knee replacement are among the most common and successful orthopaedic surgeries. The indications for these surgeries are well established and their overall success documented by extensive research (1,2). Substantial pain relief and improvement in function, with longevity of 15 years or more, is expected for most patients.
Minimally invasive and small incision joint replacement surgery has recently been offered by some surgeons, and has been promoted by surgeons, hospitals, and orthopaedic industry. This variation of traditional joint replacement surgery encompasses an array of modifications to the original technique.
Definitions
“Less invasive surgery” is terminology that encompasses both small incision techniques and minimally invasive techniques. Small incision hip and knee replacement surgery entails performing the conventional approach through a smaller skin incision.
The length of less invasive incisions may be compared to contemporary incisions (those used by most surgeons today), which are smaller than historical incisions (those used when joint replacement surgery was in its early stages of development). Minimally invasive hip and knee replacement surgery uses not only a smaller incision (or incisions) but also new exposure techniques. This is said to be less invasive to soft tissues and or bone.
In knee arthroplasty published studies have defined incisions for less invasive surgery as approximately one-half that of contemporary incisions. Some techniques allow a minimally invasive approach to the knee to minimize incisions into the extensor mechanism or the suprapatellar pouch.
In less invasive hip arthroplasty, reports have described both one and two incision surgeries. Some techniques allow for surgery through a single incision, usually one-half the length of a contemporary total hip incision. Other techniques utilise 2 smaller incisions – each 2 to 4 inches in length. Minimally invasive surgery may allow less hip muscle detachment and smaller capsular incisions.
Less invasive surgery may include unique pre- and post-operative pathways for anesthesia, nursing care and rehabilitation. Some institutions, however, may include both contemporary and less invasive surgical patients in the same pathways.
Patient Selection Criteria
Patient selection for less invasive surgery is evolving, but some surgeons define the ideal patient as young, thin, healthy, and motivated. Good candidates should have a thorough understanding of the possible advantages and disadvantages of this type of surgery.
Possible advantages
The reported advantages of less invasive surgery occur in the first few weeks or months after surgery. The reported short-term advantages include:
- Smaller incision length (improved cosmesis)
- Less discomfort (immediate peri-operative pain)
- Less blood loss (fewer blood transfusions)
- Shorter hospitalisation
- Shorter rehabilitation
- Earlier return to work
Possible disadvantages
The reported disadvantages of less invasive surgery relate to the difficulty of performing surgery within a restricted visual field as well as issues related to learning a new exposure technique. The reported disadvantages include:
- Stretching/tearing of skin/soft tissues
- A more restricted visual surgical field
- Increased duration of surgery
- Superficial nerve injury in hip surgery with the anterior incision
- Fracture of bone during implant insertion
- Limited implant choices
Unknown surgical technique related factors
Several factors are not yet thoroughly understood when comparing contemporary and less invasive hip and knee replacement surgery. These factors will be the object of ongoing research, and include:
- Long-term durability of the joint reconstruction
- Long term pain relief, motion and function
- Implant positioning
- Infection rate
- Incidence of thromboembolism
- Incidence of neurovascular injury
- Joint stability and dislocation rate
- Reoperation rate
What to discuss with your surgeon
You should have a clear understanding of the goals of your joint replacement surgery before you proceed. A discussion of joint replacement surgery should include a review of the technique that your surgeon suggests. If your surgeon offers minimally invasive or small incision surgery, ask about potential short-and long-term risks and benefits of this type of surgery. Review his or her specific results for contemporary and minimally invasive surgery in relation to fracture, infection, blood clot, neurovascular injury and dislocation rates. Inquire about his or her qualifications, competence, and proficiency with the technique. Understanding the usual post-operative course, including hospitalisation, blood loss, rehabilitation, and return to work is important.
Conclusion
Less invasive hip and knee replacement surgery is of great interest to both patients and their surgeons. Much of this interest is based on the promise of the same or better long-term results, with a shorter and less painful recovery. This set of outcomes has not yet been validated with large studies. The most positive results have been demonstrated by a small number of high surgical volume total joint centers in selected patient populations. We will have a better understanding of the value of this type of surgery in the future, and hope to understand whether it will benefit most joint replacement patients, just select groups of patients, or relatively few patients.
Credentialing
The AAHKS, through its educational endeavors, attempts to educate the public, orthopaedic surgeons, and other practitioners about new and existing techniques. However, the AAHKS does not certify the competence of an individual for clinical use of a new technique or provide any credentials.
Disclaimer
The American Association of Hip and Knee Surgeons (AAHKS) cannot provide medical advice. Patients seeking specific orthopaedic advice or assistance should contact their own orthopaedic surgeon, healthcare provider or State medical association. The AAHKS makes no warranty concerning the accuracy of the content of this statement or other linked sites. The AAHKS specifically disclaims any and all liability for injury and/or other damages that result from an individual using techniques discussed in this consensus statement. The AAHKS cannot respond to requests for endorsements of surgical techniques, products or individual physician recommendations.
Copyright © 2004 American Association of Hip and Knee Surgeons. Reprinted with permission.
References
- NIH Consensus Statement, Total Hip Replacement, September 12-14, 1994, Vol. 12, No. 5, http://consensus.nih.gov/cons/098/098_intro.htm
- NIH Consensus Development Conference on Total Knee Replacement, December 8-10, 2003, Final Statement http://consensus.nih.gov/cons/117/117cdc_statementFINAL.html
© July 2004, American Association of Hip and Knee Surgeons
Minimally Invasive And Small Incision
Joint Replacement SurgeryWhat Surgeons Should Consider
Authors: American Association of Hip and Knee Surgeons (AAHKS)
Purpose
The purpose of this advisory statement is to provide information to surgeons about the emerging use of minimally invasive and small incision techniques in the practice of hip and knee joint replacement surgery. This information has been derived from a review of both the scientific literature and information presented at meetings, and is augmented by the expertise of a group of orthopaedic surgeons and researchers experienced in the use of and study of less invasive techniques.
Introduction
For decades, pioneering surgeons have experimented with less invasive joint replacement procedures involving smaller incisions and non-traditional surgical approaches. Recently, however, there has been a renewed interest by both patients and surgeons in so-called “minimally invasive and small incision surgery,” and new techniques and peri-operative protocols have been offered. Standardized nomenclature, enhanced training, and rigorous evidence-based research of these emerging techniques will continue to improve the surgical outcomes for the hundreds of thousands of patients who benefit from hip and knee arthroplasty each year.
Hip and knee replacement are among the most common and successful orthopaedic surgeries. The indications for these surgeries are well established and their overall success documented by extensive research (1,2). Substantial pain relief and improvement in function, with longevity of 15 years or more, is expected for most patients.
Terminology and Definitions
Recent changes in total joint implant materials and design, in addition to surgical approaches, have been widely reported in the press, and are often lumped together. Such changes have been interpreted in the context of the growth of less invasive surgery in other surgical fields (which are for the most part ablative). A result is that patients and physicians expect the benefits of total joint surgery with smaller incisions and less dissection than occurs in contemporary approaches. Direct-to-consumer advertising may magnify these expectations.
Minimally invasive and small incision techniques are difficult to evaluate for a number of reasons. The variability of contemporary arthroplasty techniques confounds comparison. Incision length, for example, is not well documented in the orthopaedic literature and has not been, until recently, a major focus of concern. A surgeon’s training and individual experiences, in conjunction with surgical proficiency, affect the invasiveness of his or her approach. There is no codified way to measure incision length or soft tissue “damage” that occurs with surgery.
The relative importance of any given anatomic structure’s integrity, detachment and excision is often hard to know. A sharp distinction between contemporary and less invasive approaches is therefore difficult to establish. There are no commonly accepted definitions of less invasive hip and knee arthroplasty techniques. In addition, less invasive treatment of unique surgical problems (such as early avascular necrosis of the hip and isolated medial compartment knee arthritis) has been combined with less invasive total joint procedures. Finally, new anesthesia, pain management and physical therapy protocols have been introduced at the same time as less invasive surgical techniques, further confusing evaluation.
One of the deficiencies in the objective evaluation of minimally invasive and small incision surgery is a precise and universally accepted definition for these new techniques. “Less invasive surgery” is terminology that encompasses both small incision techniques and minimally invasive techniques. Small incision hip and knee replacement surgery entails performing the conventional approach through a smaller skin incision. The length of less invasive incisions may be compared to contemporary incisions (those used by most surgeons today), which are smaller than historical incisions (those used when joint replacement surgery was in its early stages of development). Minimally invasive hip and knee replacement surgery uses not only a smaller incision (or incisions) but also new exposure techniques. This is said to be less invasive to soft tissues and or bone.
In knee arthroplasty, published studies have defined incisions for less invasive surgery as approximately one-half that of contemporary incisions. These incisions are presumably measured at the time of surgery and with the knee in extension. Less invasive surgery should also involve smaller capsular incision and either a medial or lateral approach. Some espouse that a minimally invasive approach to the knee should not violate the extensor mechanism or the suprapatellar pouch.
In less invasive hip arthroplasty, reports have described both one and two incision surgeries. For single incision surgery, both components are placed through a single incision, with abbreviated but similar exposure to the traditional anterolateral and posterior hip approaches. Authors have defined incisions for less invasive surgery about one-half those of contemporary surgery. These incisions are usually linear, and are presumably measured at the time of surgery with the hip in neutral abduction. Other techniques utilise 2 smaller incisions – each 2 to 4 inches in length. The femoral and acetabular components are placed through two different approaches in this “two-incision” variation, and incision size depends on the surgeon’s experience. Minimally invasive surgery may also involve less muscle detachment (abductors, piriformis, quadratus femoris) and smaller capsular incisions or removal.
Less invasive surgery may include unique pre- and post-operative pathways for anesthesia, nursing care and rehabilitation. Some institutions, however, may include both contemporary and less invasive surgical patients in the same pathways.
Patient Selection Criteria
Patient selection for less invasive surgery is evolving. Some surgeons define the ideal patient as young, thin, healthy, and motivated. Other surgeons, however, have offered this type of surgery to most or all of their patients. Some of these selection criteria are difficult to quantify, which further confounds evaluation of this type of surgery.
Less invasive surgical implants, such as unicompartmental knee arthoplasty and resurfacing hip arthroplasty, utilise alternative components and incision techniques. These surgeries should be evaluated as a separate type of less invasive surgery, so as to help clarify this technology.
Possible Advantages
Acknowledging that there are contradictions as well as weaknesses in the literature published to date on less invasive arthroplasty techniques, proponents have pointed out several advantages. The reported advantages of less invasive surgery occur in the first few weeks or months after surgery. Minimally invasive and small incision techniques are reported to decrease immediate post-operative pain, shorten length of hospital stay and rehabilitation, allow earlier return to work, decrease blood loss and fewer transfusions, improve cosmesis, preserve normal tissue intervals and decrease scarring / muscle damage, and have high patient satisfaction.
A lower overall complication rate and earlier weight bearing have also been reported. If image intensification and / or surgical navigation are used in conjunction with less invasive surgery, component positioning may be improved compared with traditional techniques without such guidance.
Possible Disadvantages
Potential disadvantages of less invasive joint replacement have also been reported, and relate to the difficulty of performing surgery within a restricted visual field as well as issues related to learning a new exposure technique. Various authors and presenters have pointed out that there may be an increased overall complication rate because of poor visualisation of landmarks and vital structures. This may lead to fracture, malposition and nerurovascular injury, although these complications are by no means limited to less invasive techniques.
Injury to skin and soft tissues can occur by excessive retraction of skin, and most proponents recommend the use of specialised instruments. Length of surgery may be increased, and this may lead to a higher rate of thromboembolism or infection. Cost may be increased with longer operating times, need for specialised equipment, and the use of image intensification or navigation systems. With techniques espoused by certain implant manufacturers, only specific prostheses are suggested for minimally invasive surgery, limiting surgeon choice of fixation type, degree and prosthesis geometry. Damage to prosthetic bearing surfaces may occur at the time of implantation or relocation in cases where the joint is not well visualised.
A major potential disadvantage of these techniques is that one or more of the aforementioned issues may have a negative effect on the otherwise positive long-term results and durability that our patients and we have come to expect from total joint replacement surgery.
Unknown Surgical Technique Related Factors
Several factors are not yet thoroughly understood when comparing contemporary and less invasive hip and knee replacement surgery. Contradictory or inconclusive results, or lack of sufficient follow-up in currently available studies leave these areas open to debate in the discussion regarding the risks and benefits of less invasive surgery. These factors will be the object of ongoing research, and include:
- Long-term durability of the joint reconstruction
- Long term pain relief, motion and function
- Implant positioning
- Infection rate
- Incidence of thromboembolism
- Incidence of neurovascular injury
- Joint stability and dislocation rate
- Reoperation rate
Safety/Ethical Considerations
Patient safety is a major concern for any new and emerging technique. Many surgical landmarks and vital structures may not be visualized, are poorly visualized, or may be located solely by imaging techniques in less invasive surgery. Anatomic relationships may be different than with more traditional techniques as vital structures and soft tissues may move less freely. Complications may be more likely, particularly during the so-called “learning curve” for surgeons. The operative time for less invasive techniques will not only be longer during their early application, and also may be longer even when the surgeon becomes proficient. Longer surgical times may translate to higher direct cost, in addition to complications such as infection and deep vein thrombosis.
The ethical considerations for the introduction of a new procedure are myriad, and many are new to the current generation of orthopaedic surgeons.
Future implications/research opportunities
Any new medical technology, surgical approach or treatment protocol should be compared to pre-existing or conventional methods. Factors such as safety, efficacy, cost effectiveness, clinical advantages and patient outcomes should be evaluated before new approaches are accepted. Durability is of paramount importance in joint replacement surgery and thus studies must address both short-term and long-term results. Surgeons who choose to offer these emerging techniques to their patients are encouraged to collect and compare the clinical outcomes of the two types of surgery in their own practice.
On a larger scale, we suggest that any new techniques should be scientifically compared with contemporary conventional methods. If possible, a single variable should be changed in any given assessment and both accepted evaluation processes and sufficient statistical power should be utilized. The gold standard for objective evaluation is a randomized prospective comparison—only then will the risks, benefits and costs of new techniques be made clear to patients and physicians.
Understanding the application of a new technique is the final challenge. If proven to be beneficial, determining who should perform the technique and under what conditions is mandatory for successful outcomes.
Conclusion
Less invasive hip and knee replacement surgery is of great interest to patients, joint replacement surgeons, and third party payers. Much of this interest is based on the promise of same or better long-term results, with shorter and less painful recovery. This set of outcomes has not been validated and there is not a great deal of scientific proof to support it at this time. The most positive results have been demonstrated by a small number of high volume total joint centers and surgeons in selected patient populations. As surgeons, we need to critically evaluate these emerging techniques. Scientific evidence and rigorous evaluation of minimally invasive total joint arthroplasty techniques are needed before these techniques are recommended for more widespread clinical practice.
Credentialing
Surgeons who are engaged in new techniques are responsible to be competent, proficient and qualified to perform these new approaches. The surgeon should discuss any additional risks associated with these approaches as well as their own experience and qualifications in performing any surgical procedure in the informed consent process.
The AAHKS, through its educational endeavors, attempts to educate orthopaedic surgeons and other practitioners about new and existing technology and techniques. However, the AAHKS does not certify the competence of an individual for clinical use of a new technique or provide any credentials.
Disclaimer
The American Association of Hip and Knee Surgeons (AAHKS) cannot provide medical advice. Patients seeking specific orthopaedic advice or assistance should contact their own orthopaedic surgeon, healthcare provider or State medical association. The AAHKS makes no warranty concerning the accuracy of the content of this statement or other linked sites. The AAHKS specifically disclaims any and all liability for injury and/or other damages that result from an individual using techniques discussed in this consensus statement. The AAHKS cannot respond to requests for endorsements of surgical techniques, products or individual physician recommendations.
Copyright © 2004 American Association of Hip and Knee Surgeons. Reprinted with permission.
References
- NIH Consensus Statement, Total Hip Replacement, September 12- 14, 1994, Vol. 12, No. 5 www.consensus.nih.gov/cons/098/098_intro
- NIH Consensus Development Conference on Total Knee Replacement, December 8-10, 2003, Final Statement www.consensus.nih.gov/cons/117/117cdc_statementFINAL
© July 2004, American Association of Hip and Knee Surgeons
