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[Integration of modern technologies in therapy of sarcomas of the pelvis. Computer-assisted hemipelvectomy and implantation of a "custom-made" Bonit gentamycin coated partial pelvic prosthesis].

The resection of primary malignancies in the pelvis is technically demanding as organs and structures are to be preserved and reconstruction of the defect as well as the postoperative function and rehabilitation are dependent on an optimal prosthesis. We present two patients with a sarcoma of the pelvis where for the first time a structured concept of technology integration led to a press-fit implantation of a hemipelvic prosthesis. This concept includes the design and production of a "custom-made" prosthesis as a hemipelvic substitute and the coating of this prosthesis with Bonit, a second-generation calcium phosphate, and gentamycin in watery solution. The tumor resection was done with computer-assisted surgery based on computed tomographies (CT) of the pelvis model done by rapid prototyping rather than on the CT of the patients' pelvis. With this procedure the presurgically simulated resection could be executed precisely with complete resection of the tumors and an accuracy which allowed an exact implantation of the prosthesis. The course was uneventful with primary healing and no sign of an infection or loosening after 6 months.

Bone Neoplasms↗

[Conception and first results of the Spiron cementless femoral neck screw prosthesis].

The Spiron cementless femoral neck prosthesis is based on the idea of proximal force transmission. The concept of osseous anchorages has been proven successful various times. The prosthesis is a conical, self-cutting screw that is inserted without cement into the prepared subcapital implant bearing. It is produced from a corundum blasted titanium-vanadium alloy and is covered with a second-generation calcium phosphate coating. The coating and the form of the thread increase the implant's surface and help to optimize osseointegration. From February 2003 to April 2003, 38 Spiron prostheses were implanted at the DRK hospital in Neuwied (Germany) in 34 patients. Four patients received it for the replacement of both hip joints. The average age of the patients was 60.1 years at the time of the implantation (43-73 years); 20 male and 14 female patients received the prosthesis. We implanted 19 left-sided and 19 right-sided arthroplasties. The preoperative Harris hip score (HHS) was 51 (24-76), n=38. After 1 year, HHS(1) was 94 (86-100), n=20 (of 23 implants). Until now, we have not discovered any prosthesis-specific complications; the rehabilitation time shows a tendency to be shorter than after stem arthroplasty. Revision was necessary in one case because of an early infection. After 3 months, the radiological follow-up examinations showed the development of increasing trabecular reinforcement of the femoral neck and pertrochanteric regions. Until now, there is no evidence of any varus tendency of the Spiron prosthesis.

Adult↗

Angelchik prosthesis revisited.

There are few long-term follow-up reports of the Angelchik prosthesis (AP). We report the longest follow-up series (66-192 months, average 145 months) to date. Between October 1983 and January 1994, 65 patients (45 men and 20 women) aged between 29 and 84 years (mean 52 years) had an AP inserted for gastro-oesophageal reflux (GOR) with or without hiatus hernia (HH). Clinical, radiological, endoscopy, and operative details were reviewed. Postoperative complications, investigations, and follow-up details were critically analyzed. All living patients (n = 53) with an AP in situ were interviewed and symptomatic assessment was carried out using a modified Visick system (I-IV). The average duration of the GOR symptoms before the operation was 5.7 years (range 10 months to 20 years). The average hospital stay was 8 days (range 5-15 days). Postoperatively, five patients developed chest infection/atelectasis, four had superficial wound infection, two had deep vein thrombosis (one with pulmonary embolism), one had urinary retention, and four developed an incisional hernia. Six patients (three with an AP in situ) died of other medical conditions. Ten (15%) patients had removal of the prosthesis. Eight (12%) and 11 (17%) had transient and persistent dysphagia, respectively. Thirteen (20%) and five (8%) patients had distal slippage and proximal migration of the prosthesis, respectively. One patient had erosion of the AP into the stomach, while in another patient, the straps of the prosthesis ruptured. Of the 53 living patients with an AP in situ, 28 (53%) were Visick I, 11 (20%) were Visick II, 11 (20%) were Visick III, and 3 (7%) were Visick IV. We conclude that the AP has poor long-term results, with only 66% attaining Visick I and II, and a prosthesis removal rate of 15% (10/65). Patients with preoperative dysphagia, hypothyroidism, and diabetes tend to do worse with an AP. Obese patients and those with failed previous fundoplication seemed to fare well with an AP. In view of poor long-term results and high incidence of complications as compared to other conventional operations for GOR, we cannot recommend the continued use of the AP.

Adult↗

Successful laparoscopic removal of a migrated Angelchik prosthesis.

Implantation of an Angelchik prosthesis has been considered a quick and safe procedure for the surgical treatment of gastroesophageal reflux disease. Since its introduction in 1979 more than 25,000 have been inserted worldwide. However, the use of this device has been largely abandoned because of frequent complications and high costs. One of the more serious complications is migration of the prosthesis, which usually requires open correction. We recently operated on a 49-year-old man with a migrated Angelchik prosthesis. The device, placed 17 years earlier, had now migrated to the free abdominal cavity causing recurrent urinary tract infections and fecal incontinence. The prosthesis was removed laparoscopically via three ports in a simple procedure without any blood loss. Recovery was uneventful. At this writing, complaints have resolved, and reflux is being controlled medically. This case supports the suggestion that Angelchik prosthesis-related problems may be solved laparoscopically, even if the device was inserted via an open procedure.

Adult↗

Elevated interleukin-12 in pseudosynovial fluid in patients with aseptic loosening of hip prosthesis.

Loosening of a prosthesis is a major problem in total joint arthroplasty. To assess levels of cytokines in patients with such loosening, we measured the pseudosynovial fluid concentration of the following cytokines; tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1beta, IL-4, IL-6, IL-10, IL-12, matrix metalloproteinase (MMP)-1, and MMP-3. We examined the pseudosynovial fluid in patients with a loose hip prosthesis (group A; n = 8) and the synovial fluid in patients with osteoarthritis (OA) of the hip (group B; n = 18) using enzyme-linked immunosorbent assays. The mean concentration of IL-12 was significantly higher in group A than in group B (P < 0.01). Also, we found a significant (P < 0.05) correlation between the concentration of IL-12 and the concentration of MMP-1 in the patients with prosthesis loosening. The concentrations of TNF-alpha, IL-1beta, IL-4, IL-6, IL-10, IFN-gamma, MMP-1, and MMP-3 appeared to be similar in the two groups, although the small number of samples available precluded us from determining that there was no significant difference. The present study is the first to report elevated IL-12 levels in the pseudosynovial fluid of patients with a loose prosthesis. The immunoregulatory effect of IL-12 against wear particles could play an important role in causing loosening of the prosthesis.

Aged↗

Left ventricular rupture following mitral valve replacement due to oversize prosthesis.

Left ventricular rupture following mitral valve replacement is one of the most serious complications. We report our experience in successful treatment of type III left ventricular rupture following mitral valve replacement probably due to an oversize prosthesis. A 67-year-old woman, with the history of percutaneous transluminal mitral commissurotomy 11 years previously, underwent mitral valve replacement for mitral restenosis with a 27 mm CarboMedics mechanical bileaflet valve (Sulzer CarboMedics Inc., Austin, TX, U.S.A.). There were some difficulties in placing the entire prosthesis into the annulus at the posterior because of the oversize prosthesis. After the complete placement of the prosthesis, bulge of the left ventricular muscle was evident around the left lateral region. Following the cessation of cardiopulmonary bypass, type III left ventricular rupture, half a circular rip between the papillary muscles and posterior mitral annulus, occurred. The rip was suture-closed and a 23 mm CarboMedics valve was placed. Postoperative ultrasonic cardiography showed no prosthetic stenosis, periprosthetic leak, left ventricular pseudoaneurysm, nor left ventricular asynergy. Under cardioplegic arrest, we should not select the oversize prosthesis to prevent left ventricular rupture.

Aged↗

Effects of porous coating and collar support on early load transfer for a cementless hip prosthesis.

We used a new postprocessing method with the results from a three-dimensional finite element analysis to describe the general load transfer patterns for a cementless hip arthroplasty in the early postoperative situation, and to determine the effects of porous coating [full, partial (2/3), and none] and calcar-collar support (ideal initial contact with separation allowed upon loading, no collar) on this early load transfer. No-tension interfaces were modeled over the entire bone-prosthesis interface, with an upper bound on the Coulomb-friction over coated surfaces, and zero friction over smooth surfaces to accentuate the frictional effects of the coating. The results indicate that the anteroposterior, mediolateral, and axial forces acting on each cross section of the bone were substantially different from the corresponding homeostatic (no prosthesis) forces for the fully coated device with collar support. The frontal bending moments acting on the bone were substantially less than the homeostatic values all along the prosthesis, while the sagittal bending and torsional loads were relatively similar to the homeostatic values. By far, the largest change in these loading patterns occurred with the loss of collar support, where axial loads acting on the bone were so low that over half the bone was in net tension because appreciable transfer of the compressive head force did not occur until well below the lesser trochanter. Both axial and torsional loads were transferred more distally for devices with more coating, and torsional loading of the bone was also sensitive to the degree of collar support. The frontal bending moments acting over most of the bone were insensitive to the coating or collar support. The strain energy density in the endosteal bone was most sensitive to these design variables in the proximal region, and the largest values occurred without a collar and without coating. These findings indicate that all load components acting on the proximal bone in the early postoperative situation (no bone-ingrowth or fibrous tissue at the interface) are altered by the frictional coefficient of the bone-prosthesis interface (i.e. the presence of porous coating or some other surface treatment) and the degree of collar support, while only the axial and torsional loads are altered in the distal bone. From a prosthesis design perspective this implies that surface treatments and collar support can be used to control the axial forces and the torsional moments acting all along the bone. By contrast, the distal frontal bending moment, which dominates stresses in the diaphysis, cannot be altered by these design variables.

Bone Remodeling↗

A flexible moulage for the fabrication of an orbital prosthesis.

A technique is disucssed by which a flexible three-piece moulage may be fabricated. This procedure is a useful aid in the modeling of an orbital prosthesis. It permits the continued transfer of a wax pattern from the moulage to the patient utilizing the tissue undercuts for the retention and stabilization of the pattern. The critical task of properly positioning the ocular prosthesis is simplified by the increased stability of the entire pattern. This is of the utmost importance since even a slight error in the alignment of the eye can entirely negate the effect of an otherwise accurate prosthesis. In addition, the retention of the wax pattern simplifies the carving procedure, and accurate detail is easily secured. The acrylic resin surface on which the final silicone prosthesis is cured has proven to be accurate. Well-adapted, thin margins of the facial prosthesis have been consistently obtained.

Acrylic Resins↗

The modified Liverpool total elbow prosthesis.

We present the results of the modified Liverpool total elbow joint replacement. The humeral component of the original prosthesis was modified because of a high incidence of loosening. 19 patients who had total elbow joint replacement for rheumatoid arthritis were reviewed 8 years after surgery. 14 patients had the modified prosthesis implanted. There was dramatic relief of pain and improvement in function following surgery. There was a reduced fixed flexion deformity and an increased range of movement with the modified prosthesis. None of the humeral components of the modified prosthesis have as yet required revision. In selected patients therefore, this operation is a predictably successful procedure. Our follow-up confirms the ability of the modified prosthesis to provide a pain-free, stable and mobile joint.

Aged↗

Cancellous bone stresses surrounding the femoral component of a hip prosthesis: an elastic-plastic finite element analysis.

The cancellous bone stresses surrounding the femoral component of total hip replacement were investigated using the finite element method. Four versions of a certain femoral hip prosthesis (the Freeman, Corin Medical), cemented, HA coated, press-fit, and press-fit with ridges were analysed. Each model was subjected to two separate load cases with the cancellous bone modelled as an elastic perfectly plastic material. The effect of bone quality was investigated by varying the cancellous bone stiffness. The resulting cancellous bone stress distributions were compared to that of the intact femur. The results were also compared to clinical subsidence data (published elsewhere) for the Freeman femoral prosthesis to determine if the initial cancellous bone stress distribution could be used to predict the migration of the various versions of this prosthesis. The results showed that the press-fit designs of prosthesis generated substantially higher cancellous bone stresses than the cemented and HA coated designs, and that these stresses were up to 6.5 times higher than found in the intact femur. For all forms of fixation the cancellous bone stress distribution was found to be insensitive to changes in the trabecular bone stiffness: thus poor quality cancellous bone is more likely to promote 'plastic' deformation, and therefore subsidence of the prosthesis. Comparison with the clinical migration data showed a good correlation and revealed that it may be possible to use the calculated initial cancellous bone stresses to predict the migration of the implant, and hence the probability of early and mid-term aseptic loosening.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗

Hemodynamic evaluation of Lillehei-Kaiser and Starr-Edwards prosthesis.

The central-flow low profile disc-valve prosthesis has been offered as an alternative to ball- and tissue-valve prostheses. Extensive laboratory investigation with both pulse duplicator and experimental animals has been reported for the Lillehei-Kaster prosthesis. A series of patients receiving this prosthesis underwent postoperative cardiac catheterization to better define the hemodynamic function of this prosthesis in vivo. Because of the variations in reports of hemodynamic data from various institutions, the results of post-operative studies in an earlier group of patients with Starr-Edwards prostheses were used as a standard for comparison. Good hemodynamic function was found with the pivoting-disc prosthesis in all but the smallest valve sizes. Lillehei-Kaster and early model Starr-Edwards prostheses with equivalent tissue annulus dimensions were found to have nearly equal valve areas in vivo in the aortic position. The Lillehei-Kaster mitral valves provided larger areas than Starr-Edwards prostheses in large tissue annulus sizes.

Evaluation Studies as Topic↗

Craniofacial osseointegration of a large midfacial bone-anchored combination maxillofacial prosthesis: a clinical report.

The combination of retentive clips and magnets has been used with favorable results for smaller facial prostheses. This patient's large midfacial defect created the need for an attachment design that would retain an intraoral obturator prosthesis and a large silicone facial prosthesis. The advantages of this design include having an obturator that is separately attached by clips to the framework. This allows the patient more ease in insertion and removal of the prosthesis. It also allows for better oral hygiene. The magnets aid the patient in the proper alignment of the facial prosthesis. The O-ring attachment was not a complicated technique in this patient's treatment. The patient can, without the use of a mirror, snap the rubber matrix O-ring attachment over the patrix attachment on the framework. This resulted in a retentive facial prosthesis, which helped the patient feel more secure. The silicone margins were well adapted to the patient's skin, which allows the use of thin translucent margins and the elimination of the inherent problems associated with the use of adhesives.

Frontal Bone↗

[Bipolar shoulder prosthesis for rheumatoid arthritis with irreparable rotator cuff tear: results after 5 years' follow-up].

PURPOSE OF THE STUDY: The goal of this study was to assess the clinical and radiological outcome of bipolar shoulder prosthesis in twelve shoulders with rheumatoid arthritis (RA) and irreparable rotator cuff tears. MATERIAL AND METHODS: The follow-up was more than five years (range 2-9 years). In addition, in order to investigate the effect of rheumatoid arthritis on outcome, results were compared with ten bipolar shoulder prostheses implanted for osteoarthritis with massive rotator cuff tears. RESULTS: The mean preoperative Constant score was 16.9 points with 2.6 points for pain, 4.2 points for activity, 9.5 points for motion and 0.6 points for force. The preoperative active motion was 63.8 degrees for forward flexion, 45 degrees for abduction and 12 degrees for active external rotation. At last follow-up, the average Constant score was 39.4 points with 10.7 points for pain, 10.8 points for activity, 13.8 points for motion and 4.1 points for force. Regarding the active motion, mean forward flexion was 83.7 degrees, 70.4 degrees for abduction and 29.1 degrees for external rotation. The complication rate was low, mainly superior migration due to infraspinatus tear and glenoid wear. Satisfactory deltoid arm level was achieved in all patients and no loosening was observed. Preoperative and postoperative scores of the rheumatoid group were not significantly different from the arthritis group (p<0.001). DISCUSSION: Our findings suggest that bipolar shoulder prosthesis provides a viable replacement alternative in RA combined with massive rotator cuff tear with a low rate of complication. Bipolar shoulder prosthesis demonstrates no clear superiority over conventional hemiarthroplasty regarding improved motion and glenoid wear. In addition, no significant difference with arthritis was observed (p<0.05), assuming that outcome depends principally on the preoperative condition of the rotator cuff. CONCLUSION: Some massive tears involving the subscapularis tendon can lead to anterior recurrence after bipolar shoulder prosthesis. They might be a limit to the procedure and require a reversed shoulder prosthesis or a glenohumeral arthrodesis.

Aged↗

Repair of a proximal femoral bone defect in dogs using a porous surfaced prosthesis in combination with recombinant BMP-2 and a synthetic polymer carrier.

Total hip arthroplasty (THA) has become an almost standard procedure for the treatment of various hip lesions. However, one of the limitations has been the mechanical loosening of the prosthesis, a condition termed peri-prosthetic osteolysis. Consequently, at revision surgery, various grades of bone defect are often noted. Alternative approaches aimed at overcoming this problem have included a special design of the revision prosthesis and allo- or autogeneic bone grafting in combination with or without biomaterials. In a further attempt to address the loosening of the prosthesis, we have combined human bone morphogenetic protein-2, produced by DNA recombination (rhBMP-2) with a new synthetic biodegradable polymer (poly-D,L-lactic-acid-para-dioxanone-polyethyleneglycol block co-polymer; PLA-DX-PEG). We present data on the efficacy of the rhBMP-2 laden prosthesis to reconstruct a bone defect in a canine model. In this model, medial half of the proximal femur was surgically resected to create a bone defect that was repaired with the rhBMP-2/PLA-DX-PEG composite. Twelve weeks after implantation, the original bone defects in the rhBMP-2 treatment groups had been repaired. Thus, this type of 'hybrid' prosthesis may provide a new modality to repair bone defects or restore lost bone mass encountered in revision arthroplasty.

Absorbable Implants↗

Comparison of outcome after valve replacement with a bioprosthesis versus a mechanical prosthesis: initial 5 year results of a randomized trial.

The Veterans Administration Cooperative Study on Valvular Heart Disease was organized to compare survival and incidence of valve-related complications between patients receiving a bioprosthesis (the Hancock porcine heterograft) and a mechanical prosthesis (the Björk-Shiley spherical disc valve). Five hundred seventy-five patients undergoing single aortic or mitral valve replacement were randomized at surgery to one of the two valve types. At an average follow-up of 5 years (range 3 to 8) there are no statistically significant differences in survival between patients with the two valve types in the aortic valve replacement group. There is a statistically nonsignificant trend toward improved survival in patients undergoing mitral valve replacement with a bioprosthesis compared with a mechanical prosthesis (5 year survival probability was 0.70 +/- 0.05 and 0.58 +/- 0.06, respectively). Fatal and nonfatal valve-related complications occurred significantly less frequently in patients with a bioprosthesis compared with a mechanical prosthesis for both mitral and aortic valve replacement. Five year complication-free probability was 0.67 +/- 0.05 and 0.45 +/- 0.06, respectively, for patients with mitral valve replacement and 0.63 +/- 0.04 and 0.53 +/- 0.04, respectively, for those with aortic valve replacement. The difference in overall complication rates was largely due to the increased number of clinically significant but nonfatal bleeding episodes in patients receiving a mechanical prosthesis. Adjustment for differences in baseline characteristics between patients receiving a mitral mechanical prosthesis and a mitral bioprosthesis reduced the statistical significance of the difference in both mortality and complications.

Aortic Valve↗

Evaluation of a modular endovascular bifurcation prosthesis in a canine aortic aneurysm model.

PURPOSE: The study evaluated the deployment and healing of a novel self-expanding modular bifurcation endovascular prosthesis in a canine abdominal aortic aneurysm model. The endoluminal prosthesis consists of self-expanding nitinol stents lined by a synthetic prosthesis. One component of the device is a bifurcated body with a 12- to 14-mm diameter aortic segment and an integral 7- to 8-mm diameter iliac limb. The bifurcated body also has a stent-reinforced opening (pant-leg) for subsequent insertion of a contralateral 7- to 8-mm diameter iliac limb component. METHODS: Seventeen bifurcated prosthesis were placed; 7 were inserted through the left common carotid artery and 10 from the femoral arteries. With either route of access the 16F or 17F aortoiliac limb and the 13F iliac limb delivery catheters enabled easy passage and secure positioning of the bifurcated prostheses. Predeployment and postdeployment inspection of the dimensions and continuity of the aortoiliac prosthetic components were evaluated by cinefluoroscopy and intravascular ultrasonography (IVUS). RESULTS: After deployment was done, interval patency was assessed with angiography, IVUS, and contrast-enhanced computed tomography with the prostheses removed for analysis at 1 week (n = 4), 1 month (n = 3), 3 months (n = 4), and 6 months (n = 6). Five of the first seven implanted prostheses had occlusion of segments of the device. In two dogs the bifurcated body and both legs were occluded. In the other three the nonoccluded leg and bifurcation body were fully patent. In the first seven animals IVUS at implantation showed compression of an iliac leg by the orifice of the contralateral iliac component. After concentric fixation of the flow divider was performed, only one additional iliac limb occlusion occurred in the next 10 animals. Cinefluoroscopy, computed tomography, IVUS imaging, and histologic analysis of retrieved specimens demonstrated healing of the aortoiliac prostheses without evidence of perigraft leaks. CONCLUSIONS: This feasibility study demonstrates the ability to deploy and maintain acceptable patency of a self-expanding endoluminal, modular bifurcation prosthesis in a canine aortic model. Clinical evaluation of the device is planned for the near future.

Alloys↗

In vitro stability of an unconstrained total elbow prosthesis. Influence of axial loading and joint flexion angle.

Total elbow arthroplasty is often used to replace elbow joints that have been severely damaged by arthritis or trauma. A great disparity of designs exists, however, in currently available elbow prostheses. This study evaluated the intrinsic stability of one popular resurfacing implant, the Capitellocondylar (Johnson and Johnson Orthopaedics, Inc., New Brunswick, NJ) total elbow. The in vitro response of this unconstrained prosthesis to valgus-varus and supination-pronation loading was investigated using a materials testing machine. The influence of compressive loading and flexion angle on the intrinsic stability of the prosthesis was studied. The Capitellocondylar prosthesis was found to have little intrinsic constraint, relying on external forces for component stabilization. Dislocations were common at 111 N of compressive loading, while larger loads progressively stabilized the prosthesis. Joint flexion angle had little influence on the intrinsic constraint of the implant except to increase varus stability at lower flexion angles. The Capitellocondylar total elbow prosthesis, as designed by F. C. Ewald, behaves as an unconstrained implant. Adequate soft tissue supports, which are properly balanced to provide controlled loading, are essential to prevent instability of this arthroplasty.

Biomechanical Phenomena↗

Alumina ceramic prosthesis arthroplasty of the metacarpophalangeal joint in the rheumatoid hand. A 2-4-year follow-up study.

Swanson's finger implant is being widely used to improve deformity of the thumb and finger and to restore function in the rheumatoid hand. Breakage of the implant and implant synovitis have been the most troublesome complications. The authors developed an alumina ceramic finger prosthesis to lessen these complications. This prosthesis was used for the metacarpophalangeal joint in 5 cases of flexion deformity of the thumb and in 21 cases (82 digits) with ulnar drift deformity. These cases were followed for 24-62 months (average, 38 months). Postoperative extension of the thumb was limited to 18 degrees and flexion was 48 degrees, on average. Postoperative range of motion was 30 degrees. The average limitation of extension of all digits was 18 degrees, and the average flexion was 54.5 degrees. The average range of motion was 36.5 degrees. Flexion deformity of the metacarpophalangeal joint of the thumb disappeared after operation, and ulnar drift was reduced to less than 10 degrees deviation in 87.8%. No dislocation or fracture of the prosthesis has been found on roentgenologic examination during short-term follow-up study. This prosthesis is useful for reducing deformity of the thumb and the finger in the rheumatoid hand. Postoperative extension of the metacarpophalangeal joint, however, has been unsatisfactory. The design of the prosthesis should be improved so that the rotational center of the metacarpophalangeal joint is located palmarly.

Adult↗