[Connecting adapter for coupling exoprostheses to endoshafts : Demands on orthopedic technicians with respect to planning and application]. / Anschlussadapter zur Ankopplung der Exoprothese an den Endostiel : Anforderungen an den Orthopädietechniker hinsichtlich Planung und Anwendung.

INTRODUCTION: Transcutaneous, bone anchored prostheses have proved to be an alternative for amputees. In addition to the safe osseointegration of the implant, the correct prosthetic alignment is also important. Therefore, the interaction between prosthesis components and the prosthesis wearer is significant and the role of the certified prosthetist should not be underestimated. AIM: The aim of treatment is the best possible compensation of disability after limb loss with increase of physical abilities and comfort of the prosthesis wearer by means of bone anchored prosthesis. METHOD: Endoprosthesis inserted by the surgeon carrying out both surgery with the implant and a double-cone and 6 weeks later the exoprosthesis is fitted by the certified prosthetist orthotist (CPO). Mounting the external adaptors, assembly of the prosthesis. RESULTS: The long-term results with cementless implants and more than 35 years experience are presented. Clinical experience with the endo-exo prosthesis since 1999. A total of 135 patients treated after transfemoral amputation, 8 of them bilateral, 8 out of 135 were transtibial amputees and 1 of them bilateral. A total of 85% were amputated as a consequence of trauma and 12 out of 135 had a full range of motion at the beginning of the prosthetic work following osseointegration. In other cases, a hip flexion contracture between 3 and 12 ° had to be considered by corresponding posterior displacement adaptors. CONCLUSION: Bone anchored prostheses influence the skeleton and joints in a more direct way. This fact requires specific prosthetic measures concerning the connection between the endo-implant and the exoprosthesis. Therefore, specially matched adaptors and the prosthetic alignment are the focus of interest. Prostheses connected to an osseointegrated implant have many biomechanical advantages compared to socket-guided prostheses. Because the quality of rehabilitation is clearly affected by the prosthetic alignment, it has to be carried out extremely carefully and precisely if the prosthesis is connected to an osseointegrated implant. According to the survey, none of the prosthesis wearers wanted to return to a socket-guided prosthesis.

[Biomechanical investigation on refixation of tuberosities on shoulder prostheses. Does refixation with different suture materials offer enough stability?]. / Biomechanische Untersuchung zur Refixation der Tuberkula an Frakturschulterendoprothesen. Bietet die Rekonstruktion der Tuberkula mittels unterschiedlicher Nahtmaterialien eine ausreichende Stabilität?

BACKGROUND: Elderly patients suffering from complex, non-reconstructable fractures of the proximal humerus are commonly treated by primary implantation of a shoulder endoprosthesis. One of the most critical factors for success or failure of treatment is still the refixation of the tuberosities. METHOD: Using sheep infraspinatus tendons with attached tuberosities three different suture materials were investigated. For 2 of the suture materials 4 tests were accomplished and 5 tests were carried out for the third suture material. A material testing machine was used to perform cyclic loading tests (20 mm/min, Fmin=50 N, Fmax=100 N, respectively after 50 cycles: Fmax+50 N until failure). RESULTS: The results showed large variations in the average maximum forces (152.4 N for suture 1, 219.9 N for suture 2 and 452.3 N for suture 3). All tests showed a high initial lengthening and caused incision-like defects in the bone or tendon and led to failure and high displacement of the tuberosities. CONCLUSION: Due to these results suture materials have a limited usefulness for refixation of tuberosities as an increased risk of obstruction for bony consolidation can result.

[The modular MML revision system in knee revision and tumor arthroplasty]. / Einsatz eines modularen Knierevisionssystems MML im Rahmen des Knieprothesenwechsels und der Tumorendoprothetik.

Increasing age and a higher level of mobility lead to an increasing incidence in revision arthroplasty after total knee replacement and tumor surgery. So far, the reconstruction of large defects in bony and soft tissue environments can be accomplished by the modern modular components of revision implants. The consecutive reconstruction of the extensor mechanism in extended revision has its own drawbacks and is often associated with significant functional limitations for the patient. Specially designed implants and methods are required to generate good functional results. The modular knee revision system MML provides specific modifications of the tibial component for reconstruction of the extensor mechanism. Combined with artificial strips, an excellent functional outcome could be achieved. In this study, 70 patients were operated with the MML endoprosthesis in knee revision or tumor surgery. An excellent functional outcome could be determined. At 7 years after surgery, an average of 32+/-13 points was achieved on the Oxford Knee Score. The outcome measurement using the functional scoring system of the American Knee Society (AKS score) showed similarly good results with 71+/-25 points out of 100. A minor deficit of only 2 degrees in active extension could be observed after reconstruction of the extensor mechanism. In conclusion, we have demonstrated that the MML modular revision system is appropriate for reconstruction of segmental bone defects.

[The medial approach for total hip replacement]. / Der mediale Zugang am Hüftgelenk zur Implantation von Endoprothesen.

BACKGROUND: In an anatomical study we investigated the medial approach to the hip joint and developed the surgical technique for patients with hip joint replacement. MATERIAL AND METHODS: The temporary detachment of the adductor longus tendon allows a perfect exposure of the surgical site without risk of damaging important structures. RESULTS: The operation is possible with normal instruments. The blood loss is little. CONCLUSION: The abductor apparatus (gluteal muscles and fascia lata) and the superior gluteal nerve remain intact. Immediate lateral positioning is allowed after surgery. The scar is unremarkable.

[Bionic surface design in metal on metal bearings for total hip arthroplasty--optimization of tribological characteristics]. / Bionische Oberflächengestaltung der Metall/Metall- Gleitpaarung in der Hüftendoprothetik Optimierung tribologischer Eigenschaften.

Bionic systems are aiming to integrate natural observing into mechanical solutions. This has been realized in the design of metal on metal bearing in total hip resurface arthroplasty. The articular side of the femoral cup is covered with a dimple like surface. Under laboratory condition this so called "surf-metal-cup" achieved a reduction of the mechanical wear to almost a third part in comparison to a metal-cup with plane surface. This advantage, caused by the reduced friction-coefficient due to improved hydrodynamic lubrication could also be proved under laboratory conditions. The clinical introduction is expected to offer a significant extension of durability in this prosthetic system and needs to be proved in a long-term study.

[ESKA (CUT) endoprosthesis]. / Die ESKA- (CUT-)Endoprothese.

The ESKA femoral neck endoprosthesis (CUT) is a mini endoprosthesis anchored in the metaphysis for surgical management of young arthrosis patients with good bone quality. The necessary surgical intervention can be considered minimally invasive and adequate because only the affected femoral head is removed. The preserved femoral neck is used for fixation of the endoprosthesis to obtain proximal physiological force transmission and avoid stress shielding. Since the diaphyseal marrow cavity is not opened, the procedures entail decidedly less blood loss. Should the need arise to change the endoprosthesis, an endoprosthetic stem anchored in the diaphysis can easily be implanted after resection of the femoral neck near the base.

[Primary stability of cement free hip cup prostheses--morphometric comparative analysis of two cup types]. / Primärstabilität zementfreier Hüftpfannenprothesen--morphometrische Vergleichsanalyse an zwei Pfannentypen.

An uncemented implanted acetabular cup must ensure primary stability and postoperative osteointegration. For both conditions the immediate postoperative contact between bone and the structured surface of the cup is of decisive importance. Two different types of acetabular cups manufactured by ESKA (standard model and Kapuziner model) were implanted in the innominate bones of elderly deceased persons. After plastination, thin serial sections were obtained. On the basis of X-rays of these sections, contact between bone and the reticulate surface of the cups was quantified. The quality of the contact was analysed densitometrically.

[Less is more--a new general practiced oriented form of knee navigation]. / Weniger ist mehr--eine neue praxisorientierte Form der Knie-Navigation.

Modern navigation technology appears to be acquiring an established place in the fields of orthopedics and orthopedic surgery. This technology helps the surgeon to apply his manual skills with greater precision and thus more effectively, and its positive impact on the quality of surgical treatment has already been demonstrated. The SURGETICS navigation system described in this paper shows that the technology can be adapted to the requirements of daily surgical practice, without compromising its utility for the surgeon and, in the last resort, the patient. Provided that due consideration is given to clinical needs, this technology will surely become a standard tool, not only in European hospitals.

[The first osseointegrated percutaneous prosthesis anchor for above-knee amputees]. / Die erste osteointegrierte perkutane Prothesenverankerung für Oberschenkel-Amputierte.

A percutaneous osseointegrated anchoring device for above-knee implantation designed to enable permanent attachment of an artificial limb is described. In addition to a technical description, the two-stage operative procedure, together with the rehabilitation process in an 18-year-old man, is also detailed. Following amputation and complete healing of the soft tissues, a surface-structured metal pin capable of supporting large loads, is driven into the medullary canal of the thigh bone. A metal sleeve having an identical surface structure serves to close off the medullary canal and provide an interface with the soft tissues. Screwed to the end of the pin is a conical metal adapter to which is attached a silicone cylinder whose right-angled distal end is located subcutaneously and ends in a titanium mesh. The first part of the implantation procedure is concluded by closing the silicone cylinder with a plastic plug for 6 weeks to permit osseous integration and the ingrowth of tissue into the mesh. In a second step, the plastic plug is removed via a skin incision, and the permanent load-bearing metal adapter fitted. In the above-mentioned patient wound healing at the metal/tissue interface was complication-free, since the implanted silicone cylinder prevented the "wedge effect" caused by the build-up of "luxuriant" tissue. After a further healing phase of 6 weeks, rehabilitation with an exoprosthesis took only 2 weeks, after which time, the patient was able to walk without a walking aid, and returned to work.

[ESKA-Ceram--a new material in hip endoprosthetics]. / ESKA-Ceram--ein neuer Werkstoff in der Endoprothetik des Hüftgelenkes.

ESKA-Ceram is a new material for use in hip endoprostheses, and comprises two-thirds polyurethane and one-third Al2O3 ceramic powder. Its wear rates are of a similar low order of magnitude as those reported for metal-metal and ceramic-ceramic combinations. A great advantage of the material is that it permits the production of asymmetrical inserts for acetabular cups.

[Percutaneous vertebral augmentation (PVA) in osteoporosis of the vertebrae--an experimental study]. / Perkutane vertebrale Augmentation (PVA) bei osteoporotischen Wirbelkörpern--eine experimentelle Unterschung.

The present study was conducted with the aim of establishing whether minimally invasive percutaneous techniques used to stabilize osteoporotic vertebrae are technically feasible. Two different methods were investigated in human thoracolumbar cadaveric vertebrae. In the first technique, special titanium implants were placed via a postero-lateral approach. With the second method, the vertebrae were filled with different types of cement of different viscosities. After each procedure, the vertebrae were examined with conventional X-ray and CT scans. The first technique proved quite unsuccessful--the insertion of the titanium implants proving difficult despite the use of special instruments. The results achieved with the second method were much better. The use of low-viscosity bone cement produced the best results. Despite a single lateral point of entry, the vertebrae were almost completely filled right into the contralateral side. Lumbar vertebrae required an average volume of cement of 7 ml (range: 6.5-10 ml) and thoracic vertebrae 5.5 ml (range: 4-7 ml). Specially developed cement application devices made possible problem-free, controlled introduction of the cement.

[Measures for biomechanically correct positioning of knee joint endoprostheses]. / Massnahmen zur biomechanisch korrekten Positionierung von Kniegelenkendoprothesen.

Normal post-operative function, permanent stable fixation and long life for the implant material are determined mainly by the correct biomechanical positioning of the knee joint prosthesis. We have identified six measures within the surgical procedure that are of vital importance for achieving biomechanically correct positioning. Because of their great importance, we call these measures "The Golden Six", and describe their application using the ESKA Resurfacing Knee System (RKS). This system, which is so designed that it enables a maximal bone saving resection technique, makes use of a diagonal screw-fixation of the endoprosthetic elements, resulting in increased primary stability. For the safe and reliable implementation of our measures, we have developed a special set of instruments. Anatomical, kinematic and surgical studies have shown that with the aid of the above-mentioned six measures biomechanically correct positioning of all the implanted elements can be achieved, thus ensuring trouble-free post-operative function of the knee joint and the least possible mechanical stressing of the implanted materials.

[Cementless fixation of the endoprosthesis using trabecular, 3-dimensional interconnected surface structures]. / Zementlose Endoprothesenverankerung mittels trabekulären, dreidimensional interkonnektierenden Oberflächenstrukturen.

While the principle of enlarging the surface area has been recognized and used in different ways for some time, there is often no schematic, detailed description or fundamental research. Taking a surface structure consisting of trabecular three-dimensional connecting elements, essential parameters are shown, making it clear that the flexible dynamic reaction of the effective "anchoring space" with a suitable specified shape (construction height, alignment, network) can be reproducibly shaped and used. This has led to a hip endoprosthesis with a graduated surface structure. The construction height of the trabecular structure varies, decreasing from proximal to distal.

[Endoscopic fusion of the lumbar vertebrae]. / Endoskopische lumbale Wirbelsäulenfusion.

For certain indications, anterior fusion of the lumbar spine is a standard operation. The surgeon specializing in operations on the vertebral column needs to learn to utilize the advantages of laparoscopic surgery. However, an absolute must before employing the technique in patients is adequate training in its use in living animals. For this purpose, the pig is a highly suitable model. The surgical team comprises a surgeon experienced in spinal procedures, an abdominal surgeon with skills in laparoscopic surgery and an experienced camera assistant. In the animal model and in clinical trials, a change in position-organ preparation from the cranial direction, a suprasym-physial approach to the vertebrae-has proved expedient. The use of a special instrumentarium for maintaining the pneumo-peritoneum, for protecting the spinal cord and for exact centering, including the application of a special dowel (ESKA-spacer and instruments) is essential. The greater technical effort may be expected to result in shorter hospitalization (2-3 days) in the future.

[The ESKA femoral neck prosthesis--an alternative to standard endoprosthesis of the hip joint for patients of younger age groups]. / Die ESKA-Schenkelhalsprothese--eine Alternative zur Standardendoprothese des Hüftgelenkes für Patienten in jüngerem Lebensalter.

The ESKA femoral neck prosthesis introduces a new metaphyseal anchorage principle for total hip replacements. Primary stability of the conical-oval shaped implant is achieved through the use of a lateral traction screw, and permanent stability through bony growth into the macroporous TRIPO metal structure. The system is used in combination with the standard ESKA acetabulum, and metal-polyethylene, ceramic-polyethylene, ceramic-ceramic and metal-metal articulations are all possible.

[Design considerations for improving the acetabular cup of the ESKA hip endoprosthesis by using the ceramic/ceramic wear couple]. / Konzeptionelle Uberlegungen zur Verbesserung der Pfanne der ESKA-Hüftendoprothese durch die Gleitpaarung Keramik/Keramik.

Since 1987, cementless THR acetabular components with coarsely reticulate surfaces (S&G, ESKA) have been implanted in the Department of Orthopaedic Surgery of the Alfried Krupp Hospital in Essen. By 31st December 1995, 590 of these components had been implanted. Follow-up of the first 51 of these completely cement free THRs revealed loosening in an only single case (2%). Despite these good medium-term results, however, it must be expected that over a ten-year period, the life of the THR will decrease, the probable reason being increasing debris caused by polyethylene (PE) wear leading to aseptic loosening. An alternative to the PE/ceramic system of opposing materials would be ceramic/ceramic. Experience to date has shown that the biological inertness of ceramic does not allow ingrowth and bony integration to take place. Against this background an acetabular component employing a metal backing with the 3-dimensional reticulate surface mentioned above and a Biolox ceramic cup insert articulating with a Biolox ceramic femoral head was designed. The result is a cement free modular THR with optimal bony integration properties and articulating surfaces. To investigate the superiority of this new concept, a comparative study involving two groups of 50 patients each, one group receiving the PE/ceramic system, the other the new ceramic/ceramic system, has been initiated.

[Anatomically adapted endoprosthesis of the proximal end of the femur]. / Die anatomisch angepasste Endoprothese des proximalen Femurendes.

The marrow-cavities of several human femora were cleaned and filled with plastics; the femoral component design was developed based on these moulds. Different sizes of the stem were obtained by scaling down the biggest mould in steps of 10%. The stem has an oval cross-section and is twisted similar to the form of the marrow-cavity; therefore different designs for the left and right femur are necessary. As the marrow-cavity of the femur tapers down to the middle of the shaft the length of the prosthetic stem cannot be selected arbitrarily. The stem must end above the narrowest site of the cavity. Data are presented. To avoid disadvantageous frictional stresses between the collar of the prosthesis and the plane of resection of the femoral neck both must be aligned perpendicular to the most common direction of the load of the hip joint. Therefore a step-like osteotomy of the femoral neck becomes necessary without disturbing the calcar femorale instead of an inclined osteotomy. A firm contact between the femoral wall and the collar, which forms an angle of 64 degrees with the axis of the femoral shaft, guarantees that only small frictional stresses occur between collar and femoral cortex if the load of the hip joint varies within the physiological range. A set of ceramic femoral heads with three different conical borings yield different lengths of the neck of the prosthesis. Independent of which femoral head and which size of prosthesis are chosen the direction of the maximum hip load in any case thrusts the contact area between collar and femoral wall. Thus dangerous tilting moments round the medial calcar femorale do not occur, the incidence of a fracture of the prosthesis shaft is therefore reduced. After implantation of the anatomically designed femoral component both remodeling and resorption of the calcar femorale are observed. This reaction is independent of the kind of fixation, i.e. if a smooth stem was fixed with cement or a stem with a porous, cancellous bone-like metallic surface was implanted without cement fixation.(ABSTRACT TRUNCATED AT 250 WORDS)

[The Anatomical sliding-axis knee-joint prosthesis (author's transl)]. / Die anatomische GT-Gleitachsendoprothese des kniegelenkes (Grundei-Thomas).

In order to avoid the disadvantages of a fixed axis the newly-designed knee-joint prosthesis was equipped with a sliding one. This is not a load-bearing component; its main purpose is to guide the movement of the endoprosthesis. The design permits almost physiological movement, thus diminishing the detrimental forces at the anchor points. To further improve anchoring the shafts of the prosthesis were designed with an anatomical cross-section. The design of the anatomical sliding-axis prosthesis is described and the results of the first 36 implantations are presented.

[The anatomical GT sledge endoprosthesis Lübeck (author's transl)]. / Die anatomische GT-Schlittenendoprothese Lübeck.

In case of complete or partial destruction of articular surfaces of the knee joint where the ligamentous apparatus is present but probably insufficient, alloplastic substitution of the articular surfaces is indicated. To achieve mobility as ideally as possible, it will be necessary to shape the endoprosthetic parts in such a manner that the healthy knee joint is imitated as closely as ever possible. The anatomical GT sledge endoprosthesis Lübeck (Grundei--Thomas) was conceived with this view in mind. To preserve the knee-joint as a functional unit, all of its compartments were taken into consideration, in particular also the articulatio plana, or arthrodial joint. To perform implantation of these endoprosthetic parts without improvisation, the implantates must be prepared in accordance with surgical patterns. The high functional demands made on the knee joint can only be met by completely abandoning the simplified schematic shapes and by producing articular surface substitutes imitating the normal anatomic joints.