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At least 343 records · Page 19Linked to original sources
PubMed1996

Improvement of the tissue integration of a new modified polytetrafluoroethylene prosthesis: Mycro Mesh.

We studied the behaviour of the different tissue interfaces formed on a new type of prosthesis used for the repair of abdominal wall defects, Mycro Mesh (W. L. Gore and Ass., Flagstaff, AZ, USA), which consists of perforated layers of polytetrafluoroethylene (PTFE). In 20 New Zealand white rabbits, a full-thickness (except skin) 7 cm x 5 cm defect was created in the anterior abdominal wall. The defects were repaired with a prosthetic implant (Mycro Mesh) that was placed in direct contact with abdominal viscera and subcutaneous tissue. At 14, 30, 60 and 90 d post-implantation, samples were obtained from the tissue interfaces formed between the prosthesis and subcutaneous tissue, visceral peritoneum and receptor tissue, respectively. Samples were studied by optical microscopy and scanning electron microscopy. The immunohistological study was made with RAM-11, a monoclonal antibody specific for rabbit macrophages. Tensile strength was measured with an Instron tensiometer using 2 cm wide strips obtained parallel to the shorter axis of the implant. Strips included the prosthesis and two anchor zones on the receptor tissue. Macroscopically, the prosthesis induced little adhesion formation on the visceral peritoneum interface. Microscopically, an organized neoperitoneum and abundant tissue formed on the subcutaneous interface. In the prosthesis perforations, bridges of tissue linked the peritoneal and subcutaneous sides. The macrophage response decreased significantly in intensity between day 14 and day 90 (Student-Newman-Keuls test, P = 0.01). Tensile strength increased significantly (Wilcoxon test, P < 0.05) at every study period. To conclude: the Mycro Mesh prosthesis proved suitable for implantation in sites where it comes in contact with abdominal viscera and it provided good support for the formation of an organized neoperitoneum; the perforations in the prosthetic material improved implant integration; the macrophage response was not altered by the biomaterial and the tensile strength of the prosthesis increased as scar tissue formation and tissular integration of the prosthesis progressed.

Abdominal Muscles↗
PubMed2001

Postpneumonectomy syndrome in children: advantages and long-term follow-up of expandable prosthesis.

BACKGROUND/PURPOSE: Pneumonectomy in children can be complicated by a severe mediastinal shift, which leads to bronchial stretching resulting in severe respiratory failure. This postpneumonectomy syndrome can be corrected by inserting a prosthesis in the empty side of the chest. METHODS: Forty-two children, from 6 months to 15 years old, underwent a pneumonectomy. Seven of these patients were treated surgically for severe manifestations of postpneumonectomy syndrome. First insertion of an expandable prosthesis was followed up in 5 cases by its replacement with a breast prosthesis in adolescence. The expandable prosthesis was injected periodically with saline solution to maintain the mediastinum in a midline position as the children grew. RESULTS: The mean delay between pneumonectomy and first prosthesis implantation was 5 years (range, 11 months to 8 years). Pulmonary function tests showed a substantial improvement in the obstructive syndrome in all patients except one, in whom the functional improvement was moderate. The mean follow-up after the expandable prosthesis implantation was 6 years (range, 6 months to 10 years) and all patients are doing well. CONCLUSIONS: The insertion of an intrathoracic prosthesis can dramatically improve the clinical symptoms and reduce the functional obstructive syndrome. The expandable prosthesis allowed for progressive, well-tolerated recentering of the mediastinum and adjustment for growth.

Adolescent↗
PubMed2001

How accurate is a CT-based dose calculation on a pencil beam TPS for a patient with a metallic prosthesis?

The accuracy of a CT-based dose calculation on a treatment planning system (TPS) for a radiotherapy patient with a metallic prosthesis has not previously been reported. In this study, the accuracy of the CT-based inhomogeneity correction on a pencil beam TPS (Helax TMS) was determined in a phantom containing a metallic prosthesis. A steel prosthesis phantom and a titanium prosthesis phantom were investigated. The phantoms were CT-scanned and dose plans produced on the TPS, using the CT images to provide density information for the inhomogeneity corrections. Verification measurements were performed on a linear accelerator for 6 and 15 MV x-rays. Measured dose profiles at three different depths were compared to the calculations of the TPS. For the titanium prosthesis and for 6 MV x-rays, the TPS overestimated the beam attenuation by approximately 20% at 15 and 20 cm depths in the phantom. This is due to a limitation in the density allocation of this TPS: any Hounsfield number (HN) above a certain threshold is allocated the density of steel. For the steel prosthesis, the TPS performed the correct mapping of HN to mass density. The dose calculation was within 6% for 6 MV x-rays at 15 and 20 cm depths. However. the accuracy of dose calculation varied with beam energy and depth, with large errors in the region close to the prosthesis. The TPS overestimated the dose by 11% for 6 MV and 15% for 15 MV x-rays at 11 cm depth. 2.5 cm beyond the steel prosthesis. These results highlight the limitations in the density allocation of this TPS and demonstrate shortcomings in the pencil beam dose calculation.

Hip Prosthesis↗
PubMed2004

Titanium clip prosthesis.

OBJECTIVE: Prostheses for the reconstruction of a defective ossicular chain should be stable and firmly anchored to the ossicular remnants. This will prevent a defective connection from causing diminished sound transmission efficiency and will keep the prosthesis from tilting or even losing contact, which would result in a sound transmission block. Through temporal bone experimentation, we have consequently developed a very lightweight titanium prosthesis, which is fastened onto the stapes head with a clip mechanism. METHODS: When temporal bone experiments using laser Doppler vibrometry confirmed that the prosthesis functioned well acoustically and when luxation experiments proved that it could be safely used without the risk of stapes dislocation, the prosthesis was used in a clinical application within an observational study. The University of Dresden Otorhinolaryngological Hospital as well as seven surgeons from five other hospitals participated in the study. RESULTS: The results of 133 operations showed that, in over 90% of the cases, the prosthesis could be implemented without problems and with good mechanical stability. The first acoustical results obtained during the first year from 49 patients showed a sound transmission improvement range from 12 dB to 14 dB. CONCLUSION: With the clip prosthesis, it seems possible to further improve defective middle ear function, which would allow the patient to regain social hearing after middle ear reconstruction. The reliability of the fastening is an innovation. Revision operations showed a stable prosthesis-stapes complex in the middle of a recurring cholesteatoma and the prosthesis could always be easily pulled from the stapedial suprastructure.

Auditory Threshold↗
PubMed2006

The use of a suprascrotal or 'wink' incision for placing a testicular prosthesis.

OBJECTIVE: To describe a suprascrotal technique of testicular prosthesis insertion that obviates the difficulties and complications associated with either the inguinal or scrotal approach, as although the insertion of a testicular prosthesis is common there are few reports of the various techniques of insertion, associated complication rates, and patient satisfaction. PATIENTS AND METHODS: Eight males (aged 14-26 years) who had had a previous orchidectomy, had a testicular prosthesis inserted using a suprascrotal incision. A 2-cm semilunar incision is made just above the scrotum, 2-3 cm lateral to the penis ('wink' incision). The prosthesis is inserted after developing the intrascrotal space with blunt dissection. All patients tolerated the procedure well and all were outpatient procedures. RESULTS: After a median follow-up of 12 months, all patients were satisfied with the aesthetics of the prosthesis. Incisions were hidden by pubic hair. There were no wound infections at the incision site, and no reports of any pain or discomfort associated with the prosthesis. CONCLUSION: The 'wink' incision is an attractive alternative for inserting a testicular prosthesis; the advantages of the suprascrotal approach include: (i) the incision is hidden by pubic hair; (ii) no difficult dissection through fibrotic tissue in patients who have had previous inguinal surgery; and (iii) avoidance of direct contact between the prosthesis and suture line, minimizing the risk of infection, erosion and postoperative pain, while maintaining a pouch of adequate size.

Adolescent↗
PubMed2000

A pilot study comparing the cognitive demand of walking for transfemoral amputees using the Intelligent Prosthesis with that using conventionally damped knees.

OBJECTIVE: To compare the cognitive demand of walking when using a conventional prosthesis with that using a microprocessor-controlled prosthesis. DESIGN: Ten unilateral transfemoral amputees wearing conventional pneumatic swing phase control (conventional prosthesis) prostheses walked on a treadmill which enforced a pattern of constantly varying speeds. The subjects simultaneously performed a simple or a complex distracting task. Following a period of accustomization, the subjects performed the same test wearing a prosthesis with microprocessor control of swing phase damping (the Intelligent Prosthesis). OUTCOME MEASURES: The three-dimensional trajectory (sway) of a retroreflective marker attached to the forehead was measured by a video-based motion analysis system, and used as a measure of gait quality. The ratio of the sway for the complex task over the simple task (the 'automation index') was used as a measure of the degree of automation of gait. RESULTS: No significant differences were found in the automation index between the two devices. However, the total sway for the conventional prosthesis was significantly higher. Sway during the complex distracting task was significantly higher than during the simple task. CONCLUSIONS: The microprocessor-controlled prosthesis was not found to be less cognitively demanding than a conventional prosthesis.

Adult↗
PubMed1981

Echocardiographic and phonocardiographic assessment of the St. Jude cardiac valve prosthesis.

Forty-three consecutive patients with a St. Jude mitral, aortic, or combined prosthesis were studied by simultaneous phonocardiography and echocardiography. Twenty-eight patients had a mitral prosthesis, 20 an aortic prosthesis, and five had both. No opening click was recorded in any patient; however, a loud aortic or mitral closing click was recorded in all 43 patients. In patients with St. Jude mitral valve prosthesis, an echo-free space separated the two leaflets during diastole; seven of these also had a mid-diastolic closing and late diastolic reopening motion; two of the seven had an associated closing mid-diastolic click. A mid-diastolic rumble was recorded in six of 28 patients with St. Jude mitral valve prosthesis. In patients with a St. Jude aortic valve prosthesis, left atrium leaflet motion was recorded in 17 of 20 patients and was indistinguishable in appearance from echocardiograms obtained with various eccentric monocusp valves. In addition, we report one case of malfunction of a St. Jude mitral valve and one case of a paravalvular leak diagnosed by echophonocardiography. We concluded that the St. Jude cardiac prosthesis has variable normal phonocardiographic-echocardiographic patterns. Knowledge of these variable patterns is important in assessing patients with suspected malfunction of a St. Jude cardiac prosthesis.

Adult↗
PubMed1997

The talar body prosthesis.

Arthrodesis or talectomy for the treatment of avascular necrosis of the talus or a severe crush fracture of the body of the talus often produces a disability of the ankle and the foot. Therefore, a prosthesis designed to replace the body of the talus and to preserve the function of the ankle and the foot was developed. The prosthesis has a superior curved surface, and the medial and lateral surfaces are inclined for articulation with the tibia and the fibula. The inferior aspect has a concave curved surface at the posterior aspect of the prosthesis to serve as the posterior facet for articulation with the posterior facet of the calcaneus, and there is a convex curved surface at the anterior aspect of the prosthesis for articulation with the middle facet of the calcaneus. The neck and the head of the talus are preserved to allow insertion of the prosthetic stem into bone. A transmedial malleolar approach is used for insertion of the prosthesis. We inserted the talar body prosthesis in sixteen patients - twelve who had avascular necrosis of the talar body and four who had a severe crush fracture of the talar body - between 1974 and 1990. Three patients who were evaluated five years postoperatively had a satisfactory result, and one patient had failure of the prosthesis at eight months because the diameter of the inferior concave curved surface was too small in the region of the posterior facet and had caused erosion of the posterior facet of the calcaneus. All three patients who were evaluated six to ten years postoperatively had a satisfactory result. All except one of the nine patients who were evaluated eleven to fifteen years postoperatively had a satisfactory result; the exceptional patient had an unsatisfactory result because the prosthetic stem had sunk into the talar neck. This patient had a revision thirteen years after the index operation. We believe that the talar body prosthesis can be used to replace the body of a talus with avascular necrosis or a severe crush fracture, thus maintaining the function of the ankle and the foot for a prolonged period.

Adult↗
PubMed2002

[Fresh fractures of the radial head: results with the Judet prosthesis].

PURPOSE OF THE STUDY: Communitive fractures of the radial head are a therapeutic challenge when fixation is not possible. Secondary sequelae including ulnar valgus, ascension of the radius, osteoporosis of the humeral condyle and biomechanical impairment of the elbow cannot be avoided with resection or the Swanson prosthesis. The Judet prosthesis, with its floating cup, is a technically attractive solution, but the question is whether it can avoid the secondary effects observed with resection or the Swanson prosthesis. MATERIAL AND METHODS: We have used the Judet prosthesis since August 1995 in 16 patients. These patients had Mason type IV (Johnston modification) lesions of the radial head in 14 cases and type III lesions in 2. Associated injuries included: Monteggia fracture in 2, open fracture-dislocation in 1, fracture of the radial neck associated with fracture of the lower radius in 1, and dislocation of the elbow in 2. Preoperatively, 7 of the 16 patients had an osteocartilaginous injury of the humeral condyle. The Judet prosthesis was implanted after resection in 3 patients, after osteosynthesis of the radial head in 3 others, and as the first line treatment in 10. Postoperatively, 13 of the 16 patients were given a unique 7 Gy radiation to prevent ossification as well as nonsteroidal antiinflammatory drugs (indometazin 50 mg b.i.d.) for 3 weeks. None of the patients were immobilized. RESULTS: Mean follow-up for the 16 patients was 19 months (12-45). Deficient extension persisted in 5 patients (mean 5 degrees ). Average flexion was 128 degrees; two patients were limited to 100 degrees. Average pronation was 77 degrees, and average supination 79 degrees. Muscle force was 10% weaker than the healthy side. Sagittal and frontal stability in valgus was preserved in 14 patients. Two patients had a frontal instability with minimal valgus related to a minor insufficiency of the medial collateral ligament. According to the Radin and Riseborough classification, outcome was good in 7, fair in 6 and poor in 3. According to the Morrey classification, outcome was excellent in 2, good in 12, fair in 1 and poor in 1. Radiologically, there were no cases with ulnar valgus, humeral condyle osteoporosis, ascension of the radius, or subluxation of the distal radioulnar joint. The prosthesis loosened in one case without clinical expression. DISCUSSION: Our results with the Judet prosthesis were much better than those reported in the literature for resection and Swanson prosthesis.

Adult↗
PubMed2005

Candida albicans, Staphylococcus aureus and Streptococcus mutans colonization in patients wearing dental prosthesis.

BACKGROUND: Denture stomatitis is associated to Candida albicans, different bacteria and other co-factors such as an acid pH, a carbohydrate ingestion increase, different systemic illnesses and pharmacological treatments. OBJECTIVE: The aim of this study was to determine Candida albicans, Staphylococcus aureus and Streptococcus mutans prevalence in the mucous membrane and prosthesis of patients with and without atrophic denture stomatitis and its relationship with other potential clinical co-factors. STUDY DESIGN: Saliva was collected from 105 patients (62 female and 43 male) wearing dental prosthesis in order to measure their pH. Oral samples of the mucous membrane and the internal surface of dental prosthesis were taken with sterile cotton to proceed with the microbiological study. The identification of the isolated microorganisms was performed using conventional microbiological methods. RESULTS: Diabetes and Hypertension were the most frequent systemic illnesses. High carbohydrate ingestion was observed in numerous patients. Atrophic denture stomatitis was reported in 50 patients and the pH average in saliva was of 5.2. The presence of C albicans, S. aureus and S. mutans in the mucous membrane and prosthesis was of 51.4%, 52.4% and 67.6%, respectively. C. albicans was isolated in 66.7% from the prosthesis, whereas S. aureus and S. mutans were isolated in 49.5% of those same prosthesis. C. albicans was isolated in 86% of the patients with atrophic denture stomatitis and S. aureus was isolated in a similar percentage (84% of patients). The isolation of S. mutans was less frequent, and it was observed in 16% of the oral samples of these patients. CONCLUSIONS: C. albicans, S. aureus and S. mutans frequently colonize the oral mucous of patients wearing dental prosthesis. This illness-bearing condition is more frequent in patients with denture stomatitis, even though dental prosthesis colonization is lower than in the oral mucous.

Aged↗
PubMed1991

[The evaluation of the modified Blalock-Taussig shunt with a prosthesis of microknitted Dacron for tetralogy of Fallot in early infancy].

We evaluated the surgical results of the modified Blalock-Taussig shunt (MBTS), performed with a prosthesis of microknitted Dacron, for the ductus-dependent tetralogy of Fallot (TOF) in early infancy. Nine MBTSs for eight patients, 4 with and 4 without pulmonary atresia, were performed, and one patient died. The mean age was 30 +/- 27 days, and the mean weight was 3460 +/- 770 g at the initial MBTS. In the initial two cases, the patients experienced convulsions due to severe hypoxia on account of the troubles of the preoperative administration of Prostaglandin E1 (PGE1). Thereafter, in order to prevent brain damage, we performed the MBTS following short-term administration of PGE1 (2-13 days). Consequently, we did not experience brain damage in later cases. Half of the patients with the MBTS with a 5 mm diameter prosthesis experienced postoperative congestive heart failure due to excessive pulmonary flow, and one of them died. The patients with the MBTS with a 4 mm diameter prosthesis had good postoperative courses. The suitable shunt flow in these patients was estimated to be 70-90 ml/kg/min. The MBTS with a 4 mm prosthesis obtained the lower level of this suitable shunt flow, but that a 5 mm prosthesis induced excessive shunt flow. Observing the patients' weight gain and the progress of polycythemia until two years of age, there were no differences between the MBTS with a 4 mm prosthesis and that with a 5 mm prosthesis. From these results, we recommend a 4 mm microknitted Dacron prosthesis for the MBTS of the TOF in early infancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMed1990

[Femoral fractures following total hip prosthesis].

Fractures of the ipsilateral femur after hip arthroplasty are a serious problem. In most cases, minimal trauma is responsible for the fracture. Predisposing factors, such as severe osteoporosis, loosening of the stem of the prosthesis, or cortex perforations, are often found. Such fractures occurred between 1979 and 1989 in 30 patients, i.e. 2.3% of our patients who had received primary prosthesis and 2.9% of those who had undergone revision. The patients' ages at the time of fracture ranged from 41 to 88 years (mean 63 years), 33% of the patients in these group being female. The time lapse from implantation of the prosthesis to the fracture varied between 1 month and 11 years (mean 4.4 years). The fracture was at the level of the proximal trochanteric region in 3% of these patients, between the trochanteric line and the tip of the prosthesis in 20%, and below the tip of the prosthesis in 70%. Operative treatment was performed in 29 patients. Fractures were fixed with a compression plate in 19 (63%), and in 3 the plate fixation was reinforced with intramedullary cement. In 2 osteoporotic patients with supracondylar fractures the osteosynthesis ruptured and a successful revision operation with cement was performed. In 3 others internal fixation was combined with replacement of the prosthesis; 3 patients received a Wagner revision prosthesis and 1 a long-stem Protek tumor prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Flow patterns of a normally functioning monocuspid aortic prosthesis evaluated using Doppler echocardiography].

STUDY OBJECTIVE: Flow analysis in normally functioning eccentric monocuspid aortic prosthetic valves, to obtain a reference data list. DESIGN: To analyse, using 2D-Doppler Echocardiography, aortic flow velocity and systolic time intervals in clinically normal patients (pts), by physical examination. SETTING: Referred pts to the Echocardiographic Laboratory at Santa Marta Hospital--HCL. PATIENTS: Sequential sample of 61 pts with aortic prosthesis (41 Bjork-Shiley and 20 Hall-Kaster) without clinical evidence of either cardiac failure or significant aortic regurgitation. Patients with bad quality record were also excluded. INTERVENTIONS: Doppler Echocardiography was used to record transaortic flow, and the following indexes were analysed: instantaneous peak velocity (pv) and gradient (pg), presence of regurgitation, systolic time intervals and both preejection period/ejection time (PEP/ET) and acceleration time/ejection time (AT/ET). RESULTS: Pv ranged from 1.1 to 4 m/sec (mean 2.4 +/- 0.2. The prosthesis size 19 and 21 showed a greater pg compared to the larger ones: 46.3 +/- 14.4 mmHg against 12.6 +/- 6.4 mmHg (p less than 0.001). Occasionally a pg over 50 mmHg was found in the prosthesis size 19 and 21. The correlation between prosthesis size and pg was also significant (r = -0.62; p less than 0.001). PEP interval was 60 +/- 10 milisec in prosthesis no. 19 and 90 +/- 13 milisec in no. 27 (p less than 0.01). AT ranged from 77 +/- 14 to 88 +/- 14 milisec (mean 82 +/- 13). ET was 294 +/- 5.4 milisec in valves size 19 and 257 +/- 34 millisec in no. 25 (p less than 0.05); there was also a significant difference between prosthesis size 19 and 27 (p less than 0.05). Mild regurgitation was detected in 32.7% of cases. CONCLUSIONS: These data may be particularly useful as reference values to the follow-up of pts these types of prosthesis. Significant differences were found in pg between different valve sizes and this should be remembered when proceeding to standard evaluation by 2D-Doppler Echocardiography. Regurgitation is frequently detected in normally functioning prosthesis, not deeper than 2 cm in the left ventricle.

Adult↗
PubMed1994

Doppler echocardiography evaluation of the CarboMedics valve in patients with small aortic anulus and valve prosthesis-body surface area mismatch.

A Doppler echocardiographic study was performed to evaluate the hemodynamic performances of small diameter CarboMedics aortic valves (CarboMedics, Inc., Austin, Tex.) in patients with a mismatch between the prosthetic valve and body surface area. Fourteen patients receiving either a 19 mm (n = 7) or a 21 mm valve (n = 7) prosthesis were studied. Only patients with a body surface area greater than 1.65 m2 were included in the study. Pulsed and continuous wave Doppler echocardiography was performed at rest and 2 minutes after treadmill exercise with the Bruce protocol. Peak and mean gradients across the valve prosthesis were estimated; effective orifice area, performance index, and discharge coefficient of the valve prosthesis were calculated. All patients achieved a significant increase in heart rate, systolic blood pressure, and cardiac output with exercise. Mean gradients +/- standard deviation of the mean at rest and 2 minutes after exercise were 20.1 +/- 7.1 mm Hg and 21.8 +/- 9 mm Hg for the 19 mm prosthesis and 12.3 +/- 3.4 mm Hg and 15.9 +/- 3.9 mm Hg for the 21 mm prosthesis. The 19 mm valve prosthesis significantly increased the effective orifice area with exercise (1.02 +/- 0.2 versus 1.20 +/- 0.3; p < 0.05), whereas it was almost unmodified for the 21 mm valve (1.38 +/- 0.2 versus 1.39 +/- 0.3; p = not significant). Therefore, despite a similar increase in cardiac output with exercise, only the 21 mm valve prosthesis showed a significant increase in peak (25.4 +/- 5.2 versus 34.9 +/- 8.1 mm Hg) and mean gradient (p < 0.01). We conclude that small diameter CarboMedics valves have satisfactory hemodynamic performances even after strenuous exercise in patients with large body surface areas. The hemodynamic performances of the 19 mm valve prosthesis seem to be optimized with exercise.

Aged↗
PubMed2005

[Procedures for treatment of joint mechanics impairment in the rotating Endo-model knee prosthesis].

In cases of mechanical damage of the Endo model rotating knee prosthesis, it is not necessary to change the complete prosthesis. Isolated replacement of the mechanics is possible. We changed a sled prosthesis of a 66-year-old patient to a rotating knee prosthesis because of ligament instability. After the patient fell and traumatized the operated knee, she experienced pain during weight bearing and instability. Because clinical and fluoroscopic examinations verified instability of the prosthesis, we decided to change the mechanics of the rotating knee prosthesis. In conclusion, mechanical damage of a rotating knee prosthesis is a rare complication. Operative treatment is easy to manage if replacement parts and instruments to change the mechanics have been organized preoperatively.

Aged↗
PubMed2006

The reverse shoulder prosthesis: A review of imaging features and complications.

BACKGROUND: The reverse shoulder prosthesis is a prosthesis that has been in clinical use in Europe since 1985 and was approved for use in the United States in 2004. This unique prosthesis has a baseplate attached to the glenoid, which holds a spherical component, while the humeral component includes a polyethylene insert that is flat. This design is the "reverse" configuration of that seen with a conventional arthroplasty, in which the spherical component is part of the humeral component. The indications for the reverse prosthesis are: (1) painful arthritis associated with irreparable rotator cuff tears (cuff tear arthropathy), (2) failed hemiarthroplasty with irreparable rotator cuff tears, (3) pseudoparalysis due to massive, irreparable rotator cuff tears, (4) some reconstructions after tumor resection, and (5) some fractures of the shoulder not repairable or reconstructable with other techniques. This prosthesis can produce a significant reduction in pain and some improvement in function for most of the indications mentioned. However, the unique configuration and the challenge of its insertion can result in a high incidence of a wide variety of unusual complications. Some of these complications, such as dislocation of the components, are similar to conventional shoulder replacement. Other complications, such as notching of the scapula and acromial stress fractures, are unique to this prosthesis. CONCLUSION: The configuration of the reverse prosthesis, its normal radiographic appearance and potential complications associated with its use are reviewed.

Arthroplasty, Replacement↗
PubMedDate not supplied

Response of Charité total disc replacement under physiologic loads: prosthesis component motion patterns.

BACKGROUND CONTEXT: Total disc replacement (TDR) has been recommended to reduce pain of presumed discogenic origin while preserving spinal motion. The floating core of Charité TDR is professed to allow the replication of the kinematics of a healthy disc under physiologic loads. While segmental motion after Charité TDR has been measured, little is known about the effects of a physiologic compressive preload on vertebral motion and the motion of prosthesis components after TDR. PURPOSE: (1) Does Charité TDR allow restoration of normal load-displacement behavior of a lumbar motion segment under physiologic loads? (2) How do the prosthesis components move relative to each other under physiologic loads when implanted in a lumbar motion segment? STUDY DESIGN: A biomechanical study using human lumbar spines (L1-sacrum). METHODS: Five lumbar spines (age: 52+/-9.3) were used. Specimens were tested under flexion (8 Nm) and extension (6 Nm) moments with compressive follower preloads of 0 N and 400 N in the following sequence: (i) intact, (ii) Charité TDR at L5-S1, (iii) simulated healed fusion at L5-S1 with Charité TDR at L4-L5. Segmental motion was measured optoelectronically. Motions between prosthesis end plates and core were visually assessed using sequential digital video-fluoroscopy over the full range of motion. Here we report on kinematics of 10 Charité TDRs: 5 at L5-S1 and 5 at L4-L5. RESULTS: Charité TDR increased the flexion-extension range of motion of lumbar segments (p<.05). At 400 N preload, the range of motion increased from intact values of 6.8+/-4.4 to 10.0+/-2.4 degrees at L5-S1 and from 7.0+/-2.6 to 10.8+/-2.9 degrees at L4-L5. Charité TDR increased segmental lordosis by 8.1+/-6.9 degrees at L5-S1 (p<.05) and 5.4+/-3.5 degrees at L4-L5 (p<.05). Four patterns of prosthesis component motion were noted: (1) angular motion only between the upper end plate and core, with little or no visual evidence of core translation (9 of 10 TDRs at 0 N preload and 5 of 10 TDRs at 400 N preload); (2) lift-off of upper prosthesis end plate from core or of core from lower end plate (observed in extension in 9 of 10 TDRs under 0 N preload only); (3) core entrapment, resulting in a locked core over a portion of the range of motion (observed in extension in 8 of 10 TDRs under 400 N preload); (4) angular motion between both the upper and lower end plates and core, with visual evidence of core translation (1 of 10 TDRs at 0 N preload, 5 of 10 TDRs at 400 N preload). The pattern of load-displacement curves was substantially changed under a physiologic preload in 8 of 10 TDRs; instead of a relatively gradual change in angle with changing moment application as seen for an intact segment, the TDR displayed regions of both relatively small and relatively large angular changes with gradual moment application. CONCLUSIONS: Charité TDR restored near normal quantity of flexion-extension range of motion under a constant physiologic preload; however, the quality of segmental motion differed from the intact case over the flexion-extension range. Whereas some TDRs showed visual evidence of core translation, the predominant angular motion within the prosthesis occurred between the upper end plate and the polyethylene core. Likely factors affecting the function of the Charité TDR include implant placement and orientation, intraoperative change in lordosis, and magnitude of physiologic compressive preload. Further work is needed to assess the effects of the prosthesis motion patterns identified in the study on the load sharing at the implanted level and polyethylene core wear.

Aged↗
PubMed2002

Primary stability in cementless femoral stems: custom-made versus conventional femoral prosthesis.

OBJECTIVE: To compare a custom-made femoral stem with a conventional cementless stem for initial stability in human femurs. DESIGN: The bone-femoral prosthesis interface motion was measured in vitro using displacement transducers. Combined axial and torsional loads simulating single-leg stance, loading were applied. BACKGROUND: The custom-made prosthesis is a cementless femoral stem fabricated from the patient's CT-reconstruction. To justify its clinical use its design has to be tested regarding his primary stability. METHODS: Seven pairs of human cadaveric femurs were used for testing the custom-made prosthesis versus a conventional cementless stem. Subsidence, rotation and interface motion were measured with load cycles up to 2000 N. RESULTS: The critical interface motion of 150 microm for the cementless prosthesis was not exceed for both types of prosthesis. The custom-made prosthesis enlarged in its metaphyseal part showed a decrease of dynamic micromotions and rotation behavior in the proximal region compared to the Alloclassic prosthesis stem. CONCLUSIONS: The initial stability of the custom-made femoral stem was comparable to that of a conventional femoral stem. RELEVANCE: The data set for initial stability justifies the clinical use of a custom-made femoral stem in primary hip replacement. An individualized stem fit into the endosteal cortical bone decrease micromotion.

Adult↗