Modern Implants Research Articles

Limb salvage for proximal tibial tumours using a modular prosthesis.

We report early results after the resection of proximal tibial tumours followed by reconstruction using a modular prosthesis. The indication for wide resection was a malignant tumour in 13 patients, and a neglected giant cell tumour in 2. There were no mechanical failures during an average follow-up of 3.5 years. However, there were 5 peroneal nerve palsies, 1 complete sciatic nerve palsy, 1 vascular injury leading to an above knee amputation, and 2 deep prosthetic infections. There were 2 superficial skin necroses and 1 fracture proximal to the femoral prosthetic component. The mean post-operative Musculo-Skeletal Tumour Society (MSTS) score in 12 patients who still had their prosthesis in situ was 18.3 out of a possible total of 30 (range: 10-28). Limb salvage surgery in the proximal tibia has a high early complication rate even with the use of modern implants and improved techniques.

Primary total knee arthroplasty: indications and long-term results

In the year 2000, total knee arthroplasty is an accepted, reliable form of treatment of the end-stage arthritic knee, and there is a wealth of literature available to support its widespread success. For modern implants to be regarded as bona fide improvements over their predecessors, however, long-term prosthesis survival and patient satisfaction must be demonstrated. The ancestor of most contemporary implants was the Total Condylar Knee prosthesis, a posterior cruciate–sacrificing design. From this design, a multitude of different cruciate-substituting and cruciate-retaining designs have evolved, many of which have proven durable, reliable, and successful over the long term. Other, less popular designs have also been used with published long-term success. The concept of bicruciate retention continues to be implemented in an attempt to use minimal constraint and to allow for normal knee kinematics with reduced wear. Although cemented fixation has become the “gold standard,” various cementless implants have emerged in an attempt to improve upon fixation. Mobile-bearing designs have been developed to lower contact stresses and decrease interface stress and component loosening. The younger arthritic patient has traditionally represented a frustrating dilemma for the knee surgeon, but recent literature supports the decision to proceed with arthroplasty when end-stage disease is identified in this population. This article presents a brief overview of the available long-term data for the various designs of total knee arthroplasty applied to a variety of different patient populations. Abbreviations:ACL anterior cruciate ligament, PCL posterior cruciate ligament Tricompartmental arthroplasty has evolved into a predictable and satisfying procedure for providing pain relief for the arthritic knee. A recent meta-analysis that examined patient outcomes following total knee arthroplasty noted almost 90% good or excellent results 4 years after surgery, with a 3.8% revision rate in nearly 10,000 patients from 130 published reports [1]. Over 245,000 total knee replacements are performed in the United States annually [2], and this number is expected to rise as the percentage of Americans over 65 years of age rises in the coming years. Modifications are frequently made to implants with respect to prosthetic design, materials, and fixation technique. Consequently, most clinical studies report only short-or intermediate-term follow-up data. Time and large study populations are necessary to determine whether these modifications truly represent long-term improvements. The purpose of this article is to review the available long-term data for outcomes of modern condylar-type total knee arthroplasties.

Total hipjoint replacement

During 1990-1998 at CITO total hipjoint replacement was performed in 1668 patients. 1599 patients were followed from 1 to 8 years. In 1100 patients (68.8%) good results (passively flex the hipupto 90 degrees without pain, walk without additional support) were achieved. 399 patients (25%) had satisfactory results (passively flex the hipupto 60 degrees, transient pain, walk with additional support). 100 patients (6.2%) underwent revision hiparthroplasty due to prosthesis loosening. Outcomes were improved when the modern implants with structural surface and high-firm polyethylene - chirulen (Biomet, ESI, Plus Endoprothetik AG) were used.

Problems encountered in leg shortening

We reviewed 46 leg-shortening operations (37 femoral and nine tibial), performed by different methods, to assess the incidence of complications and permanent disability. Shortening of as much as 7.5 cm in the femur and 5 cm in the tibia was achieved in men of normal height without any loss of function. Complications were seen with all surgical techniques despite the use of modern implants. Most problems arose from inadequate stabilisation of the osteotomy. The most reliable method of femoral shortening was open subtrochanteric osteotomy with preservation of the isthmus, and fixation with an intramedullary nail locked at its proximal end. In tibial shortening, bone excision should be at the level of the flare in the lower diaphysis in order to achieve reliable bone healing. Simple intramedullary nail fixation should be supplemented with a long-leg cast for six weeks or the nail should be locked at both ends to prevent postoperative distraction or rotation.

Niomaterials Highlights II. Materials for Biomedical Applications — High Long‐Term Success Rates might pose new Problems

Biomaterials Highlights II: The increasing functional lifetime of modern implants has been due to engineering successes in utilizing new materials. However, along with this progress has come the concern that some of these materials are not as biologically inert as expected and systemic damage may in some cases be caused. Second article in a quarterly series.magnified image

Materials for biomedical application– high long‐term success rates might pose new problems

The increasing functional lifetime of modern implants has been due to engineering successes in utilizing new materials. However, along with this progress has come the concern that some of these materials are not as biologically inert as expected and systemic damage may in some cases be caused. Second article in a quarterly series. magnified image

Patient Selection for the Multichannel Electronic Prosthesis

We recommend individualized evaluation strategies for cochlear implant candidates that consider new developments in hearing aid technology. Four categories of patients are presented. Category I patients can be helped by modern ear level high-powered hearing aids and implantation is not warranted. Categories II and III patients leave us uncertain; they have improved sound detection with hearing aids, but achieve no open set word recognition. Category IV patients are unquestionably candidates for implants because no method of stimulation helps them. Experience has taught us that the most appropriate evaluation plan reflects the patient's history and is sensitive to the emotional and financial consequences of aborted candidacy. Those patients who are candidates can be guided through each component of the evaluation process with ever increasing confidence of ultimate success at the time of surgery.

Abdominal implantation of intraocular lenses resulting in the formation of reactive membranes.

For a better understanding of the cytological principles involved in the formation of reactive membranes on lens implants in the human eye, two kinds of modern implants were placed into the peritoneal space of mice. Continuous membranes mainly composed of macrophages were observed after 5 days. The membrane on a polymethylmethacrylate implant contained numerous large giant cells, while there were no giant cells on a glass implant. Implantation of intraocular lenses into the abdomen of mice is suggested as an excellent testing situation for implants of different composition and shape.