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At least 541 records · Page 30Linked to original sources
PubMed1991

[Mechanical changes in the femur induced by a joint prosthesis. Comparative extensometric studies].

This study using electrical extensometry is aimed at comparing the relative deformations of the same fresh femur before and after the successive implantation of the following titanium prostheses: a cement-free prosthesis with metaphyseal endocortical support, a cemented prosthesis with, then without collar, and finally a screwed titanium prosthesis. The 56 deformation measurement paths produce an overall exploration of the behavior of the femur. The results applied to the same straight section of the femur are different from those of earlier works. The density of the measurement areas has particularly been increased in the upper metaphysis by the use of bidirectional gages. The loading device ensures the absence of variations of the external stress torsion transmitted to the femur between the individual prostheses. The results recorded with the cement-free prosthesis with metaphyseal endocortical support and with the collar-free cemented prosthesis are very similar. The incidence of the "collar effect" is very low in spite of optimal in vitro implantation conditions ensuring good contact between the collar and the neck of the femur. The screwed prosthesis is the implant that most stiffens the upper end of the femur. The testing procedure chosen has allowed recording the deformations caused by the mere insertion of the implants and the bone. The importance of the upper metaphysea endocortical support of the cement-free, screwless implant contributes in ensuring a better primary anchorage, producing stresses that will then foster the secondary anchorage through endosteal osteogenesis.

Biomechanical Phenomena↗
PubMed1989

[Operative results of tricuspid valve replacement with St. Jude Medical prosthesis].

Since 1974, 14 patients underwent tricuspid valve replacement (TVR) with prosthetic heart valves. Hardy's operation was undergone in 2 patients with Ebstein's anomaly and mitral valve surgery or multiple valve surgery were undergone in 9 patients with rheumatic valvular disease, concomitantly. Four types of prosthetic heart valves were used in the tricuspid position, i.e. 2 Starr-Edwards prostheses, 1 Hancock xenograft, 1 Björk-Shiley prosthesis and 12 st. Jude Medical prostheses. The operative mortality rate was 14.3% (2/14) and 2 hospital deaths were due to low cardiac output syndrome. Twelve survivors have been followed with a maximum follow-up of 13 years and the mean of 4.7 years. There were 3 late deaths due to congestive heart failure and prosthetic valve endocarditis (PVE) of the aortic Björk-Shiley prosthesis. There was 1 PVE of the tricuspid Starr-Edwards prosthesis and 1 thrombosis of the tricuspid Björk-Shiley prosthesis, but no thrombosis and no other valve-related complications of SJM prostheses in the tricuspid position. The post-operative NYHA function class improved satisfactorily in 9 survivors. Judging from our relatively satisfactory post-operative results in TVR cases using SJM prostheses, SJM prosthesis in the tricuspid position is one of advisable prosthesis to get satisfactory hemodynamic improvement post-operatively.

Adult↗
PubMed1989

[Transesophageal color-coded Doppler echocardiography: diagnosis of regurgitation of mitral valve prosthesis].

In patients with mechanical mitral prosthesis, the presence of dysfunction and regurgitation of the prosthesis may be difficult to assess by standard precordial color flow Doppler. Moreover, the kind of mitral prosthesis regurgitant jet is often impossible to determine. We have recently studied 4 patients with clinically suspected mitral prosthesis dysfunction. In all of them the conventional transthoracic color flow technique was unable to evidentiate prosthesis regurgitation, whereas the transesophageal color flow Doppler assessed a partial displacement with a peri-prosthetic regurgitation in 3 patients, and a prosthetic endocarditis with intra-prosthetic regurgitation in 1. All studies were performed using an Aloka SSD 860 and 5 MHz transesophageal color Doppler transducer, using a topical anesthesia with 10% lidocaine. The procedure was well tolerated without any complication in all patients. Transesophageal color flow Doppler has specific improved capabilities over transthoracic conventional color flow Doppler and represents an important advance even for the noninvasive evaluation of patients with suspected mitral prosthesis regurgitation.

Adult↗
PubMed1988

[Normally functioning mitral prosthesis: visualization and characterization of the trans-valvular flow using color-coded Doppler].

Color flow imaging (CFI) allows real time visualization of intracardiac and transvalvular blood flow, superimposed on two-dimensional echocardiographic images. Therefore it can be useful in the identification and characterization of spatial configuration of jets through valve prosthesis. The aim of this study was to define the transvalvular flow pattern of jet in 54 patients (pts) with mitral valve prosthesis which were functioning well. Thirty-six of these pts were females and 18 males; their ages ranged from 40 to 73 years, mean age: 58. Prosthetic mitral inflow was evaluated utilizing the parasternal long axis, apical long axis and apical 4 chamber views; in addition ("off axis") intermediate sections were used when needed. Adequate CFI for detailed frame by frame analysis was obtained in 50 pts (92%). Fourteen pts had biological prosthesis (9 Hancock, 4 Carpentier-Edwards, 1 Ionescu-Shiley). Thirty-six pts had mechanical prosthesis: 13 Björk-Shiley, 8 Starr-Edwards, 9 Sorin, 5 Lillehey-Kaster, 1 Smeloff-Cutter. Variable jet configurations were identified, which were related to the type of prosthetic valve. Bioprosthetic valve characteristically had a wide, homogeneous transvalvular flow, directed towards the interventricular septum. Björk-Shiley prosthesis presented typically a jet with two components. Trans-prosthetic flow was dependent on the spatial position of the prosthesis and on the orientation of the tilting disc. Thus, the main jet, coming from the major orifice, could be directed towards the apex, flowing parallel to the left ventricular postero-lateral wall while the jet coming from the minor orifice was thin and directed towards the interventricular septum.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[Hemodynamic effect of a mitral valve prosthesis].

Hemodynamic findings are analysed in 113 patients with different types of mitral prosthesis. Catheterization of the heart was carried out before the operation and during the late post-operative period. The gradient through the prosthesis was estimated for patients with different types of mitral valve prosthesis during the operation. According to our data, the tilting-disc valve prosthesis MKC-59 and the ball valve prosthesis MKC-25 are associated with the best gradients. Mitral prosthesis improves hemodynamic activity, but does not normalize it. The heart index remains lowered, while the pressure inside the pulmonary capillaries and pulmonary artery remains elevated, as compared to normal levels. Signs of mitral stenosis become more apparent during exercise.

Adult↗
PubMedDate not supplied

[Single compartment Oxford knee prosthesis].

From 1988 to 1992, we implanted 30 Oxford single compartment prostheses. Follow-up was sufficient for study in 27 cases. The Oxford single compartment prosthesis is original because the height of the meniscal component varies with mobility during flexion-extension. This single compartment prosthesis requires a rigorous technique on the basis of well respected fundamental principles. The opposite femorotibial compartment must be untouched, otherwise a slight deviation of the axis may occur. Mobility must be satisfactory and the anterior cruciate ligament must not be injured. In our series, we obtained the same results as published in the literature, particularly those reported by Goodfellow who advocates its use. Results were satisfactory in 89% of the patients. There was an extraordinary improvement in pain symptomatology. There was little improvement in mobility. Overcorrection must be absolutely avoided because of the risk of destroying the opposite compartment. Besides the classical complications which include thrombophlebitis and retarded scar formation, we noted 3 luxations of the meniscus, 2 involving the medial meniscus and 1 the lateral meniscus. In 2 cases we had to change the meniscus (once under general anaesthesia) and in 1 cases had to reoperate to install a total prosthesis. The Oxford single compartment knee prosthesis is an important implant which has its place between osteotomy and a total prosthesis, when used according to rigorous technique. There is nevertheless the risk of meniscal luxation with this type of prosthesis.

Aged↗
PubMed1994

[Radial head prosthesis with floating cup in recent and old injuries of the elbow: preliminary results].

PURPOSE OF THE STUDY: In recent traumatology (complex radial head fractures with severe sprain of the medial collateral ligament), as well as in sequellae (extensive release for severe elbow stiffness), the implantation of a radial head prosthesis may be necessary to stabilize the humero-ulnar joint and the radial shaft. Its major advantage consists of allowing immediate postoperative mobilization. Swanson first proposed a silastic replacement of the radial head which turned out to have serious mechanical and biological disadvantages. MATERIAL AND METHODS: We propose a new Titanium implant, which is stiffer, and made of 2 parts connected by a spherical joint, thus maintaining an optimum congruence between the prosthetic component and the humeral condyle in any position of the joint (flexion/extension or pronosupination). This prosthesis was implanted in 4 recent fractures and reviewed after an average follow-up of 23 months [12-36]. RESULTS: Results were excellent in 2 cases, and good in 1 case: functional assessment was fair in the last case, in which the initial lesion consisted of a complex ulnar fracture associated with a Mason 3 fracture of the radial head. An osteosynthesis of the ulnar shaft and olecranon had preceeded implantation of the radial head prosthesis. In 5 additional cases with severe posttraumatic elbow stiffness, the prosthesis was implanted during elbow release, regularly allowing durable stabilization of the joint in an anatomic position, and in 2 of these cases, permanent correction of the radio-ulnar index. In these last cases, proximal migration of the radial shaft had occurred after resection of the radial head. In one case, this migration had resulted in ulnar fusion complicating a Sauve-Kapandji procedure. In the other case, proximal migration of the radius had resulted in painful distal radio-ulnar dislocation. In this second group, patients were followed-up an average of 31 months [12-46]. No complication has yet been recorded (no osteolysis, no stem breakage, no wear, no loosening). DISCUSSION: Indications for implantation of a radial head prosthesis were deduced from these observations: in recent trauma, implantation of the prosthesis should only be indicated in those fractures, in which osteosynthesis appears not to be possible (Mason 3 or 4), with the following associations: radial head fracture with severe sprain of the medical collateral ligament--patients with positive radio-ulnar index--extensive lesions of the interosseous membrane (Essex-Lopresti, or Monteggia affecting the ulnar shaft)--associated fracture of the proximal ulna (olecranon, coronoid process...). In sequellae, we propose the following indications: extensive elbow release compromising elbow stability--painful inferior radio-ulnar dislocation complicating resection of the radial head--valgus instability complicating radial head resection.

Adolescent↗
PubMed1993

[Reoperation after failure of unicompartmental knee prosthesis. Therapeutic strategy and results based on 40 cases].

Forty revisions for failure of unicompartmental knee prostheses were assessed. Twenty-eight women and twelve men (mean age: 67 years) were reoperated. Failure of an medial single-compartment prosthesis was involved in 35 cases, of a lateral prosthesis in 5 cases. The initial prostheses had been cemented in 19 cases and uncemented in 21 cases. Preoperative functional conditions were assessed by Hungerford's functional score and a 200-points score. The radiological study before revision showed 35 cases of varus distortion; in 12 of these, the varus distortion exceeded 10 degrees. Rather than studying the causes for failure of the single-compartment prosthesis, it seemed more useful to try to define the adequate reoperation procedure strategy and analyze its results. Our procedure aimed at solving the following difficulties: surgical approach: the same incision as in the initial operation was performed, the primary prosthesis was removed and a two-stage treatment was justified in cases of infection, metallosis involved complete removal of debris, the problem of bone-recutting and, chiefly, the problem of residual bone defect requiring bone-graft. Bone-recutting was performed with the tibial and femoral elements of the primary prosthesis still in place and using the ancillary equipment of the new prosthesis. Bone defects involved the femur as often (14 cases) as the tibia (12 cases); tibial bone defects occurred more frequently with cemented prostheses (9 cases) than with uncemented prostheses (3 cases). Femoral graft being relatively easier to perform one of the two major difficulties in our strategy was the achievement of a tibial graft.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Incidence and treatment of vascular prosthesis infection in the groin. Personal experience].

The incidence of prosthesis infection in the groin ranges between 1 and 3%, with high morbidity and mortality rates. Contamination, irrespective of whether it is endogenous or exogenous, may occur during surgery of afterwards due to a secondary bacterial load which is often associated with a traumatic surgical technique for tissues, often in emergency surgery or re-operations. MATERIALS AND METHODS. Over the past 5 years a total of 410 prosthetic alloplastic grafts have been made by our Division of Vascular Surgery with at least one anastomosis at an inguinal level. The materials used for prosthesis were dacron and PTFE. Thirty-one infections were observed in the groin of which 11 involved the prosthesis and 20 were apparently restricted to the superficial and deep layer of the dermis. A cell culture test and antibiogram was always performed. Surgical or medical therapy (loco-regional + general) was used according to individual cases. RESULTS. With regard to the 11 patients with manifest infections of the prosthesis, only trans-obturator bypass surgery gave positive long-term results, whereas other operations (femoro-femoral bypass, axillo-popliteal bypass) were not satisfactory. Of the other 20 patients treated using loco-regional and general medical therapy, 9 developed pseudo aneurysm over time for which it was then necessary to resort to surgery. DISCUSSION AND CONCLUSION. Currently there is no universally accepted treatment protocol for the management of prosthesis infection. However, it is generally considered useful to isolate any pathological agent (using routine biopsies of arterial wall or thrombo-endoluminal fragments during the primary operation) before infection can develop so as to be able to commence specific antibiotic therapy. In this context the authors underline the more devastating action of some bacteria (pseudomonas, Staphylococcus aureus) in comparison to others (Staphylococcus epidermidis). Turning to therapeutic measures, when there are anatomical grounds and with the greatest possible respect for periarterial tissues, it is considered that trans-obturator bypass is preferable in the presence of manifest infection of the prosthesis, whereas medical therapy can be used (loco-regional + general) if infection is limited to the surface layers of the inguinal area. Possible complications over time may be corrected using surgery and in situ reconstruction if infection is no longer present.

Aged↗
PubMed1993

A method of selecting the best implant prosthesis design option using three-dimensional finite element analysis.

This report presents a method for determining the optimum arrangement of implants and the optimum scheme of prosthesis splinting using biomechanics and three-dimensional finite element analysis. The three-dimensional finite element structural analysis method was used to determine the distribution of occlusal forces on teeth and dental implants. The results of the analysis showed that force distribution on occlusal surfaces does not change significantly with changes in the scheme of prosthesis splinting or implant positions. The induced stresses in bone are sensitive to the scheme of prosthesis splinting and implant positions. Induced stresses on implants for different schemes of prosthesis splinting and different implant positions varied as much as 1,000%. Therefore, the selection of implant positions and of the scheme of prosthesis splinting is critical for the longevity and stability of an implant prosthesis.

Bite Force↗
PubMed1996

[Quality assurance in hip prosthesis surgery. New type hip prostheses, review of a 3-year material].

This article deals with the short-term results of prosthetic replacement of the hip joint. The investigation was carried out three years after the introduction of a new hip prosthesis - the ITH (" International Total Hip") prosthesis. Our results were analysed retrospectively, the primary goal being quality assessment of the results of our hip surgery. We found that the results of hip prosthetic surgery with the ITH-prosthesis were satisfying, although the frequency of complications was rather high: 185 implantations of the ITH-prosthesis gave 13 cases of deep venous thrombosis; one case of deep infection and subsequent revision surgery; four cases of dislocation of the prosthesis, of which two cases have been subsequently revised; one case of perforation of the femur with later revision; and one case of permanent paralysis of the femoral nerve. The overall rate of revisions was 2.7%. The overall survival of the prosthesis according to Kaplan Meier was 97% after three years.

Adult↗
PubMed1997

[Vascular prosthesis in kidney transplantation].

OBJECTIVE: Three cases of kidney transplantation that required a vascular prosthesis are described and the literature reviewed. METHODS: Of 920 cases of kidney transplantation, 3 required a vascular prosthesis to repair the aortoiliac vessels. One patient with severe atherosclerotic disease had an aorto-bifemoral prosthesis (Gore-Tex) six months before renal transplantation and the other two patients required a vascular prosthesis to repair iliac artery lesions discovered during transplantation. RESULTS: The initial surgical results were satisfactory. No complications arising from the vascular prosthesis were observed. Two patients have a functioning renal graft, but the third patient developed acute tubular necrosis and tubulo-interstitial rejection and died from acute pulmonary edema. CONCLUSION: The importance of the preoperative cardiovascular evaluation in patients undergoing kidney transplantation is underscored. Some patients may require a vascular prosthesis. We should therefore be familiar with the prosthetic materials and the surgical techniques, which are not particularly difficult, and optimum results can be achieved. In patients with both end-stage renal disease and severe aortoiliac atherosclerotic disease, the controversy remains whether aortoiliac repair and kidney transplantation should be done simultaneously or in two stages.

Adult↗
PubMed2006

[Conventional x-ray after shoulder prosthesis].

Three types of shoulder prostheses are commonly used to cover the different indications of shoulder joint replacements: classical modular, inverse and cup. The modular prosthesis can replace the glenoid as well as the humeral head components. Exact visualization of the interface between the glenoid component and bone (or cement-bone interface) is necessary to detect osteolysis, which is relatively common. Therefore, it is mandatory to make true AP and axial projections. When describing the humeral component, the interface between bone and implant must again be considered. Additionally, the position of the humeral head in relation to the glenoid has to be noted. The glenoid component is usually fixed by screws to the bone and an osteolysis is often present at the inferior pole of the glenoid component due to prosthesis bone notching. If the implants are modular devices (classic modular prosthesis, inverse shoulder prosthesis) there is the possibility of dissociation of components and any suspicion of this should be reported. In case of reporting the conventional x-ray of cup prosthesis, the bone implant interface should be mentioned. Again the position of the humeral head to the glenoid requires attention. In all types of prostheses, dislocation of the glenohumeral joint is obvious and has to be addressed in the medical report.

Arthroplasty, Replacement↗
PubMed1991

A three-dimensional non-linear finite element study of the effect of cement-prosthesis debonding in cemented femoral total hip components.

A three-dimensional non-linear finite element analysis of a cemented femoral component in which the component was partially debonded from the cement mantle was used to assess the effects of debonding on stresses in the cement. Three cases of partial cement-metal debonding were modelled with debonding of the proximal portion of the implant down to a horizontal plane which was 35, 62.5, or 82.5 mm below the prosthesis collar. Each situation was studied under loads simulating both gait and stairclimbing. Also, complete debonding between the implant and the surrounding cement mantle was modeled for loads simulating gait. Under stair climbing loads with partial cement-mental debonding, hoop stresses of 13-18 MPa were observed in the cement at the cement-metal interface at the proximal postero-medial corner of the implant. Similarly, in stair climbing, the maximum principal stresses in the cement were also adjacent to the proximal postero-medial region of the implant. These stresses were compressive and increased from 15 MPa with fully bonded interfaces to 48 MPa with debonding down to 82.5 mm below the prosthesis collar. Under gait loads, complete debonding caused high compressive stresses up to 34.9 MPa in the cement distal to the prosthesis tip. Thus, cement failure subsequent to prosthesis debonding is likely in the proximal region in a partially debonded implant due to stair climbing loads and is likely below the prosthesis tip in a fully debonded implant due to gait loading.

Body Weight↗
PubMed1993

The Hydroflex penile prosthesis: a test case for the introduction of new urological technology.

The AMS Hydroflex* penile prosthesis was introduced for commercial distribution in 1985 but 5 years later this device was no longer available on the United States market. In an attempt to understand why this device, which initially enjoyed substantial popularity, was abruptly withdrawn from the market, patients who underwent implantation at the University of Wisconsin were interviewed and a critical analysis of the Food and Drug Administration approval process of medical devices was performed. An AMS Hydroflex penile prosthesis was implanted in 17 patients (mean age 57.7 years, range 27 to 84 years). The followup period ranged from 37 to 73 months with a mean of 58 months, and 3 patients died within that time. Of the remaining patients 10 (71%) were satisfied with the device in the first months after implantation but only 6 (43%) were satisfied at the time of followup, 9 (64%) were more satisfied with sexual relationships after receiving the prosthesis and 7 (50%) found the prosthesis simple to operate. Mechanical failure was noticed by 11 patients (79%), of whom 5 (45%) underwent further surgery. Classification of medical devices started with the enactment of the Medical Device Amendment to the Federal Food, Drug and Cosmetic Act, May 28, 1976. All medical devices that were in commercial distribution at that time were classified in 3 regulatory control categories depending upon the degree of regulation necessary to assure safety and effectiveness of each device. Before May 28, 1976 no approved application was necessary for marketing medical devices, and the Food and Drug Administration has variable amounts of information about safety and effectiveness of the different devices marketed prior to that date. Since May 1976 approved applications have been mandated for new or significantly changed devices. The specific process by which the Hydroflex prosthesis, as well as other medical devices, is approved is critically reviewed.

Adult↗
PubMed2003

[The BIAX total wrist prosthesis as an alternative to arthrodesis in degenerative and posttraumatic arthritis--early results in twenty-one patients].

The BIAX total wrist prosthesis was first implanted 1983 by Beckenbaugh in the United States. From a total of twenty-one BIAX-prostheses between March 2001 and February 2002, we have inserted eleven in patients for degenerative arthrosis, eight for posttraumatic arthrosis and two for rheumatoid arthritis of the wrist. The average age of the patients was 53.0 +/- 10.7 years with a follow-up between eleven and fourteen months on an average of one year. The motion of the operated joints was preserved on average. We have taken pain as the main criterion for the success of the operation and distinguished between pain at rest, in motion and under exertion. All patients showed a very good pain relief of 5 1/2 values from 6 1/2 before to one after surgery on a scale from one to ten. Pain relief is less under exertion, thus we are reserved with heavy workers of the implantation of the prosthesis. Apart from that, the indication corresponds to the arthrodesis of the wrist. The satisfaction of patients with the prosthesis is very high: 17 patients declared it was much better, three declared it was better and only one patient said it was unchanged. Complications occurred in six patients. The main complication was the postoperative dislocation of the prosthesis in three patients. After repositioning, the joints were long-term stable. The straight secured surgical technique is described in detail. For the majority of patients with posttraumatic or degenerative arthrosis, as well as with rheumatoid arthritis, the BIAX wrist prosthesis is recommended as a first-time operation as an alternative to wrist arthrodesis due to pain relief with preservation of joint motion and good acceptance among patients.

Arthritis, Rheumatoid↗
PubMed2004

[The cartilage guide: a solution for anchoring a columella-prosthesis on footplate].

BACKGROUND: A torp (columella-prosthesis) is the typical ossicular reconstruction in cases of a destroyed stapedial arch. Yet, many unsatisfactory hearing results are due to the lack of a stable, reliable anchoring of the base of the prosthesis on the footplate. Some solutions have been postulated, amongst them the perforation of the footplate with a tiny spike at the lower end of the prosthesis, which, however, many otosurgeons regard as too dangerous for the inner ear. Specially designed silicone sheets cannot guarantee a permanent guide of the columella. METHODS: From our good experience with cartilage in different reconstruction procedures, we therefore developed a cartilage guide for the oval window niche. An oval 2,5 x 3,5 mm cartilage with a central hole is cut out of a thin (0,2 - 0,3 mm) cartilage plate with a help of a cartilage punch, which we had designed in collaboration with Heinz Kurz manufacture. The cartilage is placed into the oval niche and its hole guides the prosthesis onto the centre of the footplate. RESULTS: Temporal bone experiments demonstrated a reliable sound transport through this guide. Revision surgery revealed a stable ingrowth of the cartilage plate into the oval niche, its perforation securely guiding the prosthesis similar to a piston on to the footplate. The first short time hearing results (max. 1 year) in 22 patients confirmed the acoustic quality of this stabilisation of a columella on the footplate as compared to a matched control group. CONCLUSIONS: The stabilization of the columella with a cartilage-guide might solve one of the many problems with unsatisfactory hearing results after the reconstruction of a completely destroyed ossicular chain.

Adolescent↗
PubMed2005

[The WEKO finger joint prosthesis].

The WEKO prosthesis was developed between 1989 and 1993 in order to restore stability and function of destroyed metacarpophalangeal joints in rheumatoid arthritis. The prosthesis is a hinged one and is fixed to the bone cementlessly by special osseointegrated sleeves in which the stem of the implant is fastened by a cone. Forty-eight patients with 74 prosthesis have been operated on in 1993. In a follow-up study in 2003, 43 of them (89.5 %) with 65 prostheses (87.8 %) could be re-examined clinically and radiographically. In seven patients (16.2 %) implant arthroplasty failed comprising loosening of the prosthesis within their sleeves, loosening of the sleeves in the bone and implant breakage. Twelve implants (16.2 %) had to be removed. The range of motion at follow-up was 0/10/70 degrees in comparison to 0/0/90 degrees postoperatively. Patients satisfaction over the first three to four years was higher than later due to deterioration of the rheumatoid disease. Thus, classical handscores to assess the outcome could not be applied. A second generation of the WEKO prosthesis was developed to improve rotational stability and osseointegration paying attention to reports concerning failures which were seen also by other authors. The stem of the implant was changed to a cylindrical one with star shaped cross-section which allows some pistoning in order to reduce the stressload of the sleeves.

Arthritis, Rheumatoid↗