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At least 1,099 records · Page 61Linked to original sources
PubMed2001

[Intraoperative Doppler ultrasound of the femoral vein for maintaining venous patency in hip joint prosthesis implantation].

PROBLEM: Is the femoral vein occluded during insertion of the stem? Can thrombembolic complications be reduced by avoiding occlusion? METHODS: In a prospective randomized study 160 cemented stems were implanted from the anterolateral approach: 76 patients had conventional figure-of-four positioning of the femur, 84 patients had a modified position according to the blood flow registered by intraoperative Doppler sonography. RESULTS: 68.7% of the 84 femoral veins were completely occluded in the figure-of-four positioning. Only by reduction of this position and soft tissue release, venous flow could be demonstrated by sonography. Increased body mass index (BMI) and age correlated with occlusion (p = 0.0001 and p < 0.05). In the 84 patients no thrombembolic complication was found. In the control group 3 deep thromboses were revealed by venography (p = 0.105). CONCLUSION: Doppler sonography helps guaranteeing venous drainage. A modified leg position should be aimed at especially in increased BMI and age.

Aged↗
PubMed1994

The effect of hydroxyapatite coating on the fixation of hip prostheses. A comparison of clinical and radiographic results of hip replacement in a matched-pair study.

The efficacy of a total hip replacement with a hydroxyapatite-coated hip prosthesis was compared with that of an uncoated, cementless prosthesis of the same type. Preoperatively, there was no difference in the patient's diagnosis, hip score, age, and sex. All operations were performed by one surgeon in a standardized manner. The choice of the implant was randomized, and the follow-up period was equal for both types. The implant used was associated with a poor outcome due to a high incidence of early aseptic loosening. Probably because of a poor initial fixation, there was a significant difference in the clinical results after a short follow-up period when an additional HA layer was used. According to the patients' pain, migration of the implant, and presence of a progressive radiolucent line, use of the HA-coated prosthesis led to a significantly better result; however, we also found an increased rate of heterotopic bone formation in the HA-coated group. It was concluded that the HA coating improves the initial fixation of a hip prosthesis.

Durapatite↗
PubMed1996

[Reasonably good results of Hansson's pins in elderly patients with a medial femoral neck fracture].

OBJECTIVE: To establish the result of treatment of medial femoral neck fractures in patients aged 70 years and older using Hansson pins introduced percutaneously. DESIGN: Descriptive. SETTING: Department of Surgery, University Hospital Utrecht, the Netherlands. METHOD: Ninety-two patients aged 70 years and older with a medial femoral neck fracture were treated in the period 1986-1994 with osteosynthesis using Hansson pins. The case histories and X-rays of these patients were analysed. All fractures were classified according to Garden and Pauwels, with Singh classification of bone quality. The result of the operation was evaluated with the aid of postoperative X-rays. RESULTS: The patients' mean age was 80 years. There were 16 non-dislocated Garden grades I or II and 71 dislocated Garden III and IV fractures. Four patients died within 30 days after the operation. At the time of the follow-up (after an average of 4.5 years), 45 patients had died. Thirty-three patients in all developed a fracture-related complication; 27 of them underwent reoperations during which 19 (21%) were fitted with a head-neck prosthesis or a total hip prosthesis. All reoperations which included implantation of a prosthesis were performed in dislocated Garden grades III and IV fractures. In fractures of this type in which postoperative repositioning proved inadequate, more reoperations were performed than in the Garden grades III and IV fractures with correct posture. CONCLUSION: Treatment of a medial femoral neck fracture in elderly patients by means of internal fixation with percutaneously introduced Hansson pins gives results similar to those of other types of internal fixation. This is a good operation for Garden grades I and II fractures, whereas in Garden grades III and IV fractures in which repositioning is impossible, internal fixation should be refrained from and a head-neck prosthesis should be implanted in one session.

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PubMed2006

[V.A.C.-instill therapy in periprosthetic infection of hip and knee arthroplasty].

Periprosthetic infection represents a main complication of arthroplasty. In case of an early infection the implant often can be left in place. Whether instillation of antiseptic solution using a reticulated sponge in combination with negative pressure wound therapy (V.A.C.-Instill) can be useful was the aim of our investigation. Up to now the instillation of Lavasept in combination with negative pressure wound therapy could be performed in three patients. In two cases an early infection of a hip prosthesis and one infected knee implant had to be treated. Following surgical debridement V.A.C.-Instill therapy was performed for 4-7 days followed by closure of the wound or a repeated application. Lavasept was used for irrigation. In all three cases retention of the primary implant could be achieved. The follow up now is 8 to 22 weeks. No recurrence of the infection occurred. After salvage of the prosthesis the joint allowed full load bearing and painfree mobilisation. The V.A.C.-Instill system proved to be easy to use. With this system early periprosthetic infection with antiseptic irrigation in combination with negative pressure wound therapy decreasing the bacterial burden, salvage of prosthesis seems to be possible. The therapy is applicable in hip and knee prosthesis. Final conclusions about this therapy however can be done only after a larger series of patients.

Aged↗
PubMed2005

Unsatisfactory results with the cementless Omnifit acetabular component due to polyethylene and severe osteolysis.

A high incidence of acetabular osteolysis (43%), associated with osteolytic lesions in the proximal femur (22.6%) and leading to a high revision rate, was experienced with the Omnifit total hip prosthesis. We reviewed the clinical and radiological results with 429 Omnifit total hips in 356 patients after a mean follow-up of 60 months. Time to revision and wear of the polyethylene liner with different acetabular shell types were specifically analysed. Pelvic osteolysis first became manifest in the acetabular bone opposite to the holes in the metal shell. Osteolysis occurred predominantly adjacent to the central hole in the metal shell of threaded cups; widespread and larger defects were found in press fit cups with peripheral screw holes. Kaplan Meier survival analysis demonstrated a higher probability for retaining the threaded cup at 6 years (96%; 95%-confidence interval: 93-99%) compared to the survival of the press fit cup (66%; 95%-CI: 56-77%). The results suggest a negative relationship between backside wear, the larger number of holes in the cup, the extent of osteolysis and survival rate of the press fit cups. Based on these findings and supported by similar reports about osteolysis related to the same cup design, it was hypothesised that backside wear due to the insufficient locking mechanism of the Omnifit acetabular cup was the major cause of the unsatisfactory results in our patients. For this reason we discontinued using this type of uncemented socket.

Adult↗
PubMed1993

Evaluation of wear in an all-polymer total knee replacement. Part 1: laboratory testing of polyethylene on polyacetal bearing surfaces.

The friction and wear characteristics of a prototype, all-polymer hip prosthesis were evaluated using a multi-station hip-joint simulator. The components consisted of 41 mm diameter polyacetal copolymer balls in combination with acetabular cups of UHMW polyethylene, and were compared to the conventional combination of cobalt-chromium alloy balls against UHMW polyethylene cups. The all-polymer combination exhibited about 20% lower friction and 39% lower wear of the polyethylene cups. The total volume of polymer wear from the all-polymer combination (i.e. including the wear of the polyacetal ball) was 23% less than the volume of polyethylene wear from the metal-polymer components. The appearance of the worn surfaces of the polyethylene cups in the scanning electron microscope were similar for the two combinations of materials, and the surfaces of the polyacetal balls showed only mild wear. Formaldehyde, a product of the degradation of polyacetal, was present in traces in some samples of lubricant from the test chambers with polyacetal balls. In this laboratory model, the friction and wear properties of a polyacetal copolymer ball in combination with an UHMW polyethylene demonstrated good potential for clinical application.

Acetals↗
PubMedDate not supplied

[Improved radiological imaging of acetabular screw socket].

The improved radiological representation of the cementless acetabular screw-socket at two levels is of fundamental importance for the postoperative determination of position as well as for the judgement of an aseptic loosening. To improve the radiological representation two special radiographic techniques in the anterior-posterior as well as in the axial view have been examined on a human preparation of pelvis and have been scrutinized on a great number of clinical patients. The a.-p. radiography with twenty degrees cranio-caudal prone view in the sagittal plane and the axial radiography with forty-five degrees caudo-cranial prone view in the coronal plane shows the best and fewest overlayed representation of the screw-socket. The position of inclination and anteversion could have been directly determined out of these two radiographs. Malpositions of the screw-socket, especially with regard to the anteversion are easily identifiable due to the special axial radiographic technique. Overprojection of adjoining bone areas, which were possible should be considered at the judgment of the implant-bone-contact. Radiographic technical and positioning problems were not observed in patients. Out of these examinations the a.-p. radiography with twenty degrees cranio-caudal prone view in the sagittal plane and the axial radiography with forty-five degrees caudo-cranial prone view in the coronal plane could be recommended to the radiological diagnosis after implantations of hip prosthesis.

Acetabulum↗
PubMed1996

How superior placement of the joint center in hip arthroplasty affects the abductor muscles.

This study examines the effects of a superiorly placed hip center on the strength of the abductor muscles. A 3-dimensional computer model of the hip and the surrounding musculature was used to calculate the moment arms, forces, and moments generated when the hip abductor muscles are maximally activated. A representation of a hip prosthesis was implanted into the computer model with altered hip center positions and a range of prosthetic neck lengths. Analysis of these simulated hip replacements demonstrated that superolateral placement of the hip center (2 cm superior and 2 cm lateral) decreases the moment arms of the hip abductor muscles by an average of 28%. This decrease in moment arm cannot be restored by increasing prosthetic neck length, resulting in an unrecoverable loss of abduction strength with superolateral displacement. By contrast, a 2-cm superior displacement of the hip center changes the moment arms and force generating capacities of the abductors by less than 10% if prosthetic neck length is increased to compensate for decreased muscle length. The results of this study suggest that superior positioning of the hip center, without lateral placement, does not have major, adverse effects on abduction moment arms or force generating capacities when the neck length is appropriately increased.

Biophysical Phenomena↗
PubMed1993

[Results of cementless implantation of 150 "Erlangen Model" hip prostheses of titanium alloy Ti Al5 Fe2.5].

Between March 17, 1984 and August 20, 1987, 142 patients with osteoarthritis of one or both hips were treated by joint replacement with the uncemented "Erlangen" hip prosthesis (Prof. H. Beck/P. Brehm Chirurgie-Mechanik GmbH). The causes of the osteoarthritis varied. Hip replacement was carried out for the following conditions: rheumatoid arthritis including ankylosing spondylitis, aseptic necrosis of the femoral head, including posttraumatic and idiopathic forms, osteoarthritis of unknown origin, osteoarthritis following dysplasia or subluxation of the hips, and loosened cemented hip prostheses (131 primary implantations and 19 revisions). Full weight-bearing was not permitted for 50 days postoperatively, but mobilization and isometric exercises were started 2 days after operation and isotonic exercises were introduced later. Complications included fracture of the femoral shaft during operation and aseptic loosening. Our results in the 142 patients (150 joints) at 32-65 months (average 44 months) after surgery are encouraging. Good results based on patient satisfaction were obtained in 92.7% (81.3% after revision) and poor results in 7.3% (18.7% after revision). Most (90.2%) of the patients can walk without a stick (50.0% after revision), and 90.2% of the patients can walk more than 1000 m (68.8% after revision).

Alloys↗
PubMed2003

The influence of resting periods on friction in the artificial hip.

Insufficient tribologic performance of total joint components is a major cause of prostheses failure. Wear has been studied intensively using testing machines that apply continuous motions. Human locomotion, however, is not well represented by continuous motions alone. Singular events and resting periods are a substantial part of daily activities. Resting does influence adhesion in the artificial joint with possible effects on friction, wear, and loosening. The current study evaluated the effects of resting on the frictional properties of hip prosthesis components. The activity measurements of 32 patients with artificial hip replacements were analyzed for resting durations of the hip. A pin-on-ball screening device was used to determine friction after characteristic resting periods and during continuous oscillating motion. All common articulation pairings were investigated. Prolonged and frequent resting periods of the hip were found for the patients. Initial friction increased with increasing resting duration for all tested materials (between 41% and 191%). The metal-on-metal articulations showed the highest friction level (0.098 for sliding) and the highest increase (191%) in friction with resting duration (0.285 after resting periods of 60 seconds). A high static frictional moment after resting periods might present a risk for aseptic implant loosening. Therefore, large head diameters of metal-on-metal joints should be used with caution, especially when additional unfavorable risk factors such as obesity, weak bone-implant interface, or high activity level are present.

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