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PubMedDate not supplied

Location of the femoral head in developmental dysplasia of the hip: three-dimensional evaluation by means of magnetic resonance image.

By using magnetic resonance imaging, we analyzed the position of the femoral head in 21 hips of 21 infants with developmental dislocation. The femoral head changed its location according to the hip position. In type A dislocation, the head was anterior to the acetabulum when the hip was extended, and it was posterior when the hip was flexed. There was wide contact area between the femoral head and the acetabulum in any hip position. In type B, the head was on the rim of the acetabulum when the hip was extended. When the hip was flexed, the head was on the posterior rim of the acetabulum, and there was no contact between the femoral head and acetabular cartilage. Some heads slipped into the socket with a click phenomenon when the hip was flexed/abducted. In type C dislocation, the head was on the edge of the acetabulum when the hip was extended. When the hip was flexed, the head moved posteriorly, and it was completely out of the socket.

Acetabulum↗
PubMed1999

Acetabular involvement in osteonecrosis of the femoral head.

When an arthroplasty is needed to treat osteonecrosis of the femoral head, the use of a component that replaces or resurfaces only the femoral head is often considered as an alternative to total hip replacement if the acetabulum appears radiographically normal. However, the long-term results of the use of endoprostheses have often been poor, secondary in part to progressive degeneration of the acetabular cartilage and to protrusio acetabuli. To help to explain these observations, we examined the acetabular cartilage in forty-one hips in which a primary total hip replacement had been performed because of osteonecrosis of the femoral head in association with a radiographically normal acetabulum. The cartilage in the superior, weight-bearing region of the acetabulum was grossly abnormal in forty of the forty-one hips and it was histologically abnormal in all thirty-three hips that were so evaluated. In all but one hip, gross degeneration of the cartilage was apparent, involving less than 20 percent of the acetabulum; the degeneration was graded as mild (superficial fibrillation and slight irregularity of the surface) in sixteen hips, moderate (moderate fibrillation, alteration in color and consistency, and thinning of cartilage without complete erosion to bone) in twenty hips, and severe (marked fibrillation, alteration in color and consistency, and marked thinning of cartilage with areas of complete erosion to bone) in four hips. These observations emphasize the fact that radiographs cannot demonstrate early degeneration of cartilage and that, by the time that an arthroplasty is needed, degenerative changes are already present in the acetabular cartilage of a high percentage of hips with osteonecrosis, even when radiographs of the acetabulum show no abnormalities. These findings should be kept in mind when a decision is being made regarding which type of arthroplasty should be done in a patient who has osteonecrosis of the femoral head and regarding when to do the procedure.

Acetabulum↗
PubMed2002

Anatomical study of the blood supply of the coxal bone: radiological and clinical application.

The aim of this work was to study the arterial blood supply of the coxal bone in order to optimize radiological embolization and to minimize the risk of postoperative osteonecrosis. Ten fresh cadavers were dissected after intra-arterial injection of colored resin. All the collateral vessels running to this bone were described and counted. On 25 dry bones, the vascular foramina were measured with the aid of a millimetric gauge and a vascular map was created. The posterior part of the ilium appears to be twice as well vascularized as the anterior part. Fractures of the posterior arch of the pelvis are theoretically more hemorrhagic. The presence of the iliolumbar artery in contact with the sacroiliac joint increases the risk with open book or shearing fractures. The artery of the ischium, a collateral of the pudendal artery, supplies the posterior and lateral parts of the acetabulum and the artery of the roof of the acetabulum, its superior and lateral parts. The branches of the anterior and posterior divisions of the obturator artery supply the superior part of the surroundings of the obturator foramen and the antero-inferior and postero-inferior parts of the acetabulum. The Kocher approach may injure the artery of the ischium. Letournel's extended lateral approach and Mears' triradiate approach may injure the artery of the ischium and the artery of the roof of the acetabulum. The risk of osteonecrosis appears to be theoretically increased if one adds an endopelvic approach. The anterior approach to the acetabulum appears to be that which theoretically leads to the least devascularization. The French version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00276-002-0029-2.

Arteries↗
PubMed2004

Anatomical and biomechanical investigations of the iliotibial tract.

Divergent descriptions of the anatomic location and biomechanical function of the iliotibial tract (IT) can be found in the literature. This study attempted to obtain exact data regarding the anatomic course and material characteristics including the biomechanical properties of this structure. The following were its aims: (1) anatomical investigations of the IT; (2) mechanical properties of the IT; (3) femoral head centralizing force of the IT and subligamentous forces in the height of the greater trochanter in different joint positions by using a custom-made measuring prosthesis and a subligamentous positioned sensor; (4) construction of a finite element model of the proximal femur including the IT and measuring the femoral neck angle under variation. The hip joints and IT in a total of 18 unfixed corpses were evaluated. We studied the anatomic relationship to surrounding structures, as well as the material properties with the help of tensile strength testing utilizing an uniaxial apparatus. During the test, a load-displacement curve was registered, documenting the maximum load and deformation of the IT. To measure the subligamentous pressure at the height of the greater trochanter, a custom-made sensor with a power-recording instrument was constructed. Furthermore, an altered hip prosthesis with a pressure gauge at the height of the femoral neck was used to measure the forces which are directed at the acetabulum. The investigations were done in neutral-0 position and ab/adduction of the hip joint of the unfixed corpse. In addition, we varied the femoral neck angle between 115 degrees and 155 degrees in 5 degrees steps. To confirm the subligamentous forces, we did the same measurements intraoperatively at the height of the greater trochanter before and after hip joint replacement in 12 patients. We constructed a finite element model of the proximal femur and considering the IT. The acquisition of the data was done at physiological (128 degrees), varus (115 degrees), and valgus (155 degrees) femoral neck angles. The influencing forces of the IT at the height of the greater trochanter and the forces at the femoral head or the acetabulum could be measured. Our anatomical investigations revealed a splitting of the IT into a superficial and a deep portion, which covers the tensor fasciae latae. The tensor fasciae latae has an insertion on the IT. The IT continues down the femur, passing over the greater trochanter without developing an actual fixation to the bone. Part of the insertion of the gluteus maximus radiates into the IT. The IT passes over the vastus lateralis and inserts at the infracondylar tubercle of the tibia or Gerdy's tubercle, at the head of the fibula, as well as at the lateral intermuscular septum. Portions also insert on the transverse and longitudinal retinaculum of the patella. Concerning the material properties of the IT, we found a structural stiffness of 17 N/mm extension on average (D = 17 N/mm). The subligamentous measurements at the height of the greater trochanter in the unfixed corpse and intraoperatively during hip joint replacement showed an increase of the forces during adduction and a decrease during abduction of the hip joint. We found thereby a maximum increase up to 106 N with 40 degrees adduction. Concerning the femoral neck angle, we can state that valgus leads to lower subligamentous forces and varus to higher subligamentous forces. The forces directed at the acetabulum, which were measured by the prosthesis with a sensor along the femoral neck, showed a decrease with varus angles and an increase with valgus angles. The highest force of 624 N was measured with 40 degrees adduction and an angle of 155 degrees. The finite element model of the proximal femur showed a sole hip joint-centralizing force of the IT of 655 N with a femoral neck angle of 128 degrees after subtraction of the gluteal muscle force and the body weight. At 115 degrees, we found an increase up to 997 N and a decrease to 438 N at 155 degrees. Concerning the resulting forces in the acetabulum, we found opposite forces in comparison with the force of the IT at the height of the greater trochanter: at 115 degrees, a femoral head-centralizing force of 1601 N; at 128 degrees, 2360 N; and at 155 degrees, 2422 N. By our investigations, we can approximately prove the hip joint-centralizing force of the IT. By variation of the femoral neck angle and the position of the hip joint, we can predict the subligamentous force of the IT and the resulting force at the femoral head or at the acetabulum. The intraoperative measurement of the subligamentous forces of the IT is a good monitoring mechanism for the persistent hip-centralizing function of the IT in the course of hip joint replacement. The surgeon has the opportunity to check the stability of the hip joint after replacement. The finite element model gives the opportunity to check the divergent relative strength by variation of the femoral neck angle and the tension of the IT. In this way, the changes in the forces induced by a displacement osteotomy could be estimated preoperatively.

Aged↗
PubMed1999

An in vitro comparison of the motion behavior of different bipolar endoprostheses.

The relative motion of 3 different bipolar endoprostheses was evaluated in vitro. A paired fresh acetabulum was frozen at 0 degrees C and defrosted 12 hours before the experiment. Three bipolar endoprostheses were evaluated: UNIQHIP system (United Orthopedics), UHR system (Osteonics), and AML system (Depuy). The surface roughness and spherical roundness of outer shells and inner heads of the bipolar prostheses were measured before the experiments. The acetabulum and outer shell of the bipolar prostheses were fixed on a Bionix 858 material testing system axially by separate fixation tools. The axial load of 1,400 N and 2,800 N was than applied on the specimen. The axis was rotated from 0 degrees to 90 degrees at the speed of 1 degree/s. All 3 outer shells were tested to this paired acetabulum randomly and separately. The frictional torque on the outer bearing surface of the different prostheses was recorded by the material testing system. The frictional torque on the inner bearing surface was also measured by the same procedure as was done for the outer bearing. The final results were statistically compared by the 1-way analysis of variance test method. Bipolar prostheses of the UHR system showed the largest frictional torque on outer bearing when it was loaded with 1,400 N and 2,800 N. The final results showed that all the bipolar prostheses had ideal motion behavior when functioning under the loading of 1,400 N. The frictional torque on the inner bearing was found to be larger than the frictional torque on the outer bearing in some prostheses when the loading was increased to 2,800 N. Thus, the bipolar endoprostheses functioned as unipolar prostheses. The only relative motion remained between the outer bearing surface and the acetabulum. This effect causes complications, such as implant protrusion in the acetabulum.

Hip Prosthesis↗
PubMed1980

[Insertion of Judet's prosthesis in high-region dislocation of the hip (author's transl)].

Osteoarthrosis of the hip (also known as coxarthrosis) as a result of a high-region dislocation of the hip, presents a difficult task for the orthopaedic surgeon, the solution of which is still under frequent and intense discussion. Total hip replacemnt (hip endoprosthesis) involves technical difficulties which result on the one hand, from the underdeveloped anatomic conditions (underdeveloped primary acetabulum with soft spongiosa on valgus position of the highly sclerosed secondary acetabulum associated with underdeveloped shaft of the femur); on the other hand, a repositioning is difficult if anchoring of the prosthesis is effected at the level of the primary acetabulum. For this reason, we developed an original operation method requiring two sessions: in a first operation, an extended arthrolysis is performed via an anterior access, whereas at the same time an extension is carried out by means of the distraction apparatus according to Wagner. After this first session, distraction is performed during 3 to 4 weeks until the head of the femur has attained the level of the primary acetabulum. The prosthesis is inserted in a second session, where anchoring at the level of the primary acetabulum becomes possible and repositioning can be affected without undue difficulties. An example of such total hip replacement by endoprosthesis, requiring 2 sessions, is demonstrated.

Female↗
PubMed2004

Recognizing acetabular version in the radiographic presentation of hip dysplasia.

Attention to the radiographic shadow of the walls of the acetabulum seen on the anteroposterior projection of a well-centered radiograph of the pelvis is important to identify the orientation of the opening of the acetabulum. This is referred to as the acetabular version. The opening of the mouth of the acetabulum may be oriented anteriorly, which is referred to as anteverted; posteriorly, or retroverted; or when the shadow of the lips of the anterior and posterior walls terminate together on the lateral edge of the acetabular rim, neutral version. The radiographs of 153 patients with developmental hip dysplasia presenting with hip pain were reviewed to determine the frequency of retroversion of the acetabulum. In this group of patients, retroversion of the hip socket was surprisingly common, one in three hip sockets, and generally was associated with smaller values of the lateral center edge measurement. The observation is important, because it must be taken into account when planning a corrective osteotomy of the acetabulum so the abnormal horizontal orientation of socket is corrected along with the usual anterior and lateral insufficiency.

Adult↗
PubMed2003

Cartilage lesions in the hip: diagnostic effectiveness of MR arthrography.

PURPOSE: To evaluate the diagnostic performance of magnetic resonance (MR) arthrography in the detection of articular cartilage lesions in patients suspected of having femoroacetabular impingement and/or labral abnormalities. MATERIALS AND METHODS: Forty-two MR arthrograms obtained in 40 patients with a clinical diagnosis of femoroacetabular impingement and/or labral defect were retrospectively analyzed. Two readers independently interpreted the images for cartilage lesion location, depiction, and characteristics. Within 6 months after MR arthrography, each patient underwent open hip surgery, during which the entire cartilage of the hip joint was inspected. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. kappa values were calculated to quantify the level of interobserver agreement. RESULTS: At surgery, most (37 [88%] of 42) cartilage defects were identified in the anterosuperior part of the acetabulum. In 23 (55%), 12 (29%), 10 (24%), and 10 (24%) hips, lesions were found in the posterosuperior acetabulum, anteroinferior acetabulum, posteroinferior acetabulum, and femoral head, respectively. The sensitivities and specificities of MR arthrographic detection of cartilage damage in all regions combined were 79% (73 of 92 regions) and 77% (91 of 118 regions), respectively, for reader 1 and 50% (46 of 92 regions) and 84% (99 of 118 regions), respectively, for reader 2. At interobserver comparison, agreement was fair (kappa = 0.31) for detection of cartilage lesions in the femoral head and poor (kappa <or= 0.2) for detection of lesions in all acetabular regions. CONCLUSION: Cartilage lesions are common in young and middle-aged patients with femoroacetabular impingement and/or labral abnormalities and are most frequently found in the anterosuperior part of the acetabulum. 2003

Adult↗
PubMed1997

[Sonographic measures of the hip joint of 1328 newborns of Han and Uygur nationalities-relative factors of congenital dislocation of hip].

The four sonographic methods (Engesaeter, Terjesen, Graf, Morin-Harcke) were used for examining the hip joint of 1328 newborns of Han and Uygur nationalities. The difference between Han and Uygur newborns was not statistical significant, but some literatures reported that in our country, the incidence of different nationalities in different regions varied. Our conclusion is that there is no obvious relationship between the depth of the acetabulum and the percentage of the femoral head covered by the acetabulum. It is caused by other factors, inherent or acquired. The value of the hip joint of the male and female has significant difference (P < 0.0005). The incidence of CDH in girls is much higher than that in boys. This may be related to the different depth of the acetabulum and different percentage of the femoral head covered by the acetabulum. In the period of newborn, girl's depth of the acetabulum is smaller than that of boys.

Anthropometry↗
PubMedDate not supplied

Anatomical ceramic arthroplasty (AN.C.A.): preliminary experience with a new cementless prosthesis.

The study reports the results obtained in 100 hips operated with a new cementless arthroplasty (AN.C.A.) characterized by the anatomical shape of a stem coated with Al2O3 and by a spherical acetabulum in ceramic-titanium, stabilized to the acetabulum first by screwing of the titanium ring and then by bony ingrowth in the cupola covered with porous ceramic. The patients were followed-up after an average of 17.4 months (+/- 8 SD). The patients were clinically evaluated using on the Merle d'Aubigné system, with the following average values +/- SD: pain 5.51 +/- 1, walking 5.01 +/- 1.1, and range of motion 5.38 +/- 0.9. The radiographic stabilization of the prosthesis (considering the worst results of the acetabulum and/or of the stem) was bony (BS) in 83% of the case and fibrous (FS) in 11%; 6 cases (5 acetabulums and 1 stem) showed signs of radiographic instability. Of these, 2 were submitted to further surgery to substitute the acetabulum. Two other patients were also submitted to a second operation: 1 involved substitution of the fractured ceramic head, and the other involved substitution of the stem in a patient with progressive coxalgia and no radiographic signs of loosening. The method of radiographic evaluation was significantly correlated with pain (p = 0.0001) and with walking (p = 0.0095). Instead, there were no significant correlations between stabilization of the prosthesis and precision of the femoral fit (press-fit) of the stem, age, evaluation of preoperative mineralization of the bone, and length of the stem. 8% of the cases presented important radiographic signs of stress-shielding; while 16% presented hypertrophy of the femoral cortex. These radiographic findings were not correlated to clinical ones.

Adult↗
PubMed1990

[Total hip prosthesis in coxarthrosis following congenital hip dislocation (65 hips reviewed at 5 years)].

In 45 patients, 65 hips with CDH were given a THR after 5 years or more, with an average follow up of 8.5 years. The results and the technical problems are discussed. Of those 65 hips, there were 46 anterior dislocations, 15 intermediate dislocations and 4 cases of posterior dislocation. The mean shortening was 58.3 mm. In all cases, the authors performed a total arthroplasty on the original acetabulum, after lowering and reconstruction of the acetabulum by grafts taken from the femoral head. There are some immediate postoperative complications: 12 thromboembolic complications, hematomas and 2 cases of paralysis of the peroneal nerve. There was loosening in 8 patients (12%), with 3 infections. The functional results were good in 85% and poor in 7.5%. Nevertheless, the limp was maintained in 49 patients. There was residual low back pain in 7 patients. In 14% a second operation on the homolateral knee was performed after an average time of 2 years. The technical problems are discussed: the cup should be placed in the original acetabulum and in evaluating the lowering of the acetabulum, the condition of the lumbar spine should be considered. Posterior luxation is discussed as well; the authors recommend prudence in the indication for THR operations with lowering of the acetabulum shell.

Adult↗
PubMed1994

[Contribution to the study of pelvic stress during weight-bearing. Role of the pubic branch and trabecular bone].

INTRODUCTION: Several authors have reported evidence of loosening of the acetabular component in 14 per cent of cases at 10 years follow-up. To understand this phenomena, parametric studies of the acetabulum have involved finite element analysis, photo elastic models or strain gauges. The differing and sometimes contradictory results were due to the way the model was solicited. If the classic "Resultant" is accurate for the study of the forces on the hip, Pauwels described other forces on the pelvis during the gait. The effect of the application of these other forces on the acetabulum are the object of this study. MATERIALS AND METHOD: Four pelvises were loaded with different forces. Nine strain gauges were pasted around the acetabulum. The pelvis was loaded up to 140 Kg and a compressive force was applied to the pubis by 10 Kg increments up to 40 Kg. The stress data with and without the second force were recorded. A cortical window was bored on the anterior inferior iliac spine. Through this patch, the trabecular bone of the acetabular roof was cut up to disturb its mechanical properties. The load was once again applied to the pelvis and the stress data recorded. RESULTS: The compressive force applied to the symphyseal surface decreases the deformation of the posterior acetabular rim and increases deformation in the proximity of the ischio-iliac and iliopubic junctions. The disruption of trabecular bone generates an increase in deformation mainly perpendicularly to the acetabular rim. DISCUSSION: The decrease of the stress on the posterior acetabular rim is interpreted as a reduction of the solicitations on a fragile zone and its increase on the iliopubic and ischio iliac junctions expresses the application of the acetabular horn on the femoral head permitting better settling of the hip during the gait. The constatation of a stress increase around the acetabulum after disruption of the traecbular bone is interesting. The bone behavior with different acetabular cup models on different pelvis may be studied by strain gauges pasted on the cortical bone. The variable quality of the trabecular bone may introduce an error factor in the measurement. CONCLUSION: The deformation of the acetabulum during gait has to be studied following the different forces described by Pauwels. The compressive force on the pubic symphysis during one leg stance permits a decrease of the stress on the acetabular rim and an increase in the setting of the femoral head. Different qualities of trabecular bone change the deformation of the cortical bone for an equivalent load. This incites us, in comparative studies, to be careful in the deduction of the acetabular roof stresses from the recorded cortical bone deformations.

Aged↗
PubMed1996

[Surgical treatment of radiation-induced lesions of the hip in adults].

The authors report their experience in the surgical management of lesions of the adult hip following radiotherapy. The diagnosis of a hip problem occurring after pelvic radiotherapy for malignant tumors is made by clinical and radiological examination. The problems include femoral head necrosis, necrosis and/or fracture of the acetabulum, or involvement of the entire hip joint (radiation coxopathy). Fractures of the femoral neck have been described in the literature, but are now very rare following the routine use of external shields as protection during irradiation. Post-irradiation lesions are often bilateral 21%. They appear after a variable latency period of two to twenty years and they progress remorselessly. A diagnosis of simple radio necrosis can only be made after using radio isotope bone scanning, MRI or CT to exclude malignant disease as acetabular metastasis, and radio-induced sarcomas. Hemiarthroplasty is often followed by collapse of the acetabulum and should no longer be used. The treatment generally practised nowadays is a Total Hip Replacement (THR). We report a retrospective study of 71 hips in 56 patients treated, between 1970 and 1982, by the use of conventional cemented components. In 49 hips this was followed by a 52% incidence of acetabular loosening resulting from the poor quality of the irradiated bone which had become necrotic and porotic. Between 1983 and 1990, we modified the technique by regularly using reinforcing the acetabulum with a metallic ring fixed by long screws, (as used in revision surgery for THR). Bone grafts were also used in 9 cases. We had a 12% incidence of loosening in 22 hips with a mean follow-up of 40 months. There were also two post-operative infection which need removal of the prostheses. This emphasizes the risk of infection in this type of surgery and is probably increased by the associated lesions of the soft tissues (lymphoedema, radiodermitis). The authors wish to stress the poor prognosis of radiation lesions of the hip which often occur in patients who have otherwise recovered from their pelvic tumour. These radiation lesions have to be recognised and treated in a specific way. Our experience and the reports in the literature suggest that the generally used conventional THR gives uncertain results, and therefore we propose a THR employing metallic reinforcement of the acetabulum with or without any necessary bone grafts. It is vital to warn the patients that the results may not be as excellent as with THR for other types of hip disorders. When there is severe destruction of the acetabulum the choice between a THR combined with massive bone allograft, and a Girdlestone hip resection must be very carefully discussed with the patient. This latter "salvage" procedure may in any case become necessary if there are local and otherwise unmanageable problems.

Adult↗
PubMed1985

Contact finite element stress analysis of the hip joint.

Two-dimensional finite element analyses were conducted of the normal hip using contact elements at the joint surface. The models studied were constructed for a slice through the pubis, acetabulum, and ilium. In the analyses the proximal femur was pressed into the acetabulum and intraarticular pressures and principal stresses in the joint region were determined for different load magnitudes and directions and various boundary conditions. Three sets of boundary conditions were examined: (a) deformable pubic symphysis, (b) rigid pubic symphysis, and (c) simulations of experimental studies. In the deformable model the pubic symphysis was free to displace in the sagittal plane and rotate. In the rigid model the pubic symphysis was rigidly fixed. Superoposterior loading resulted in high-contact pressures at the acetabular dome for all sets of boundary conditions. For the deformable model subject to a more medially directed load the acetabulum closed in such a manner as to squeeze the head of the femur creating high-contact pressures superiorly and inferiorly. This resulted in significant compressive stresses in the superior dome cancellous bone and inferior cancellous bone. The cumulative effect of this squeezing action with normal biological remodeling may cause elongation of the femoral head resulting in asphericity and incongruity of the unloaded hip joint articular surfaces. Rigidly fixing the pubic symphysis stiffened the model and resulted in principal stress patterns that did not reflect trabecular density or orientations as well as those of the deformable pubic symphysis model. Finite element simulations of previous experimental studies modeled the close proximity of the fixation to the excised acetabulum. These boundary conditions prevented the squeezing caused by pelvis deformations. The resulting contact areas, pressure distributions, and bone stresses were very different from those of the more anatomic, deformable pubic symphysis model. These findings demonstrate the sensitivity of hip contact pressures and stresses to imposed boundary conditions and indicate that care should be taken to simulate anatomic conditions in experimental and theoretical studies.

Acetabulum↗
PubMed1991

Alterations in femoral and acetabular bone strains immediately following cementless total hip arthroplasty: an in vitro canine study.

Alterations in strain patterns in both the femur and acetabulum of the dog, due to cementless total hip arthroplasty (THA), were evaluated by monitoring cortical bone strains before and immediately following implantation of components, using an accurate in vitro jig, simulating the loading of the canine hip in vivo. Femoral arthroplasty with straight stem, canal-filling, femoral components, made of titanium-based alloy, led to a statistically significant reduction of proximal femoral bone strains, with proximal medical compressive strains reduced, on average, to only 22% of intact strain magnitude (p less than 0.01), even though the prostheses contained collars and were not fixed with cement. Strain alterations on the acetabulum, following cementless THA, were more complex and variable. Laterally, a significant decrease (p less than 0.01) in periacetabular strains to between 20 and 60% of the intact state was observed, while medial wall strains varied inconsistently after arthroplasty. These strain alterations reflect major changes in mechanical loading of both the femur and acetabulum immediately following cementless THA, using components similar to those used clinically in humans. Major reductions in strains on the proximal femur occurred with cementless femoral components, while the change in strains on the acetabulum were variable, and could be a result of variations in fit and placement of components inherent even in well-controlled implantation techniques. The physiologic in vitro loading of the canine femur with the pelvis, used to obtain these data, can be applied to future investigations exploring stress transfer around uncemented components and the relationship of stress transfer to morphological changes of bone, in the canine model.

Acetabulum↗
PubMed1984

Artificial replacement of the hip joint in severe coxarthroses secondary to acetabular dysplasia.

The reconstruction of hip joints is problematic in cases of subluxation coxarthrosis, since the dysplastic acetabulum's lack of depth does not primarily allow reliable anchorage of an acetabular prosthesis component. Since enlargement of the acetabulum by fraising is ruled out on biomechanical grounds, a suitable bed for the implant can only be created by reconstructing the roof of the acetabulum. Laterally supported osteoplasty has proved to be a suitable method for repairing dysplastic acetabular defects, involving screwing of autogenic or allogenic grafts firmly onto the acetabular margin. The radiological and clinical results of 70 hips followed up confirm the efficiency of the endoprosthetic acetabulum implanted by this method in cases of marked dysplastic coxarthrosis.

Acetabulum↗
PubMed1987

In vitro experiments with an injection technique for cup fixation in total hip arthroplasty.

A new technique has been developed to position the cup rigidly into the acetabulum during total hip joint replacement. After positioning the flanged cup on the acetabulum by means of screws, a low-viscosity cement is injected through a hole in the rim of the cup. A comparison with the standard cementing technique was made on the basis of in vitro experiments. For this purpose a mold was constructed to produce castings simulating the human acetabulum. The distribution of the cement, the pressure developed in the acetabulum, and the penetration of the cement are compared for the two cementing techniques.

Acetabulum↗
PubMed1997

Anatomic study of the pre- and neonatal hip. Physiopathologic considerations on dysplasia and congenital dislocation of the hip.

Therapeutic success in dysplasia and congenital dislocation of the hip depends on an early diagnosis. The physiopathology remains very debatable and several concepts are propounded. For a better physiopathologic understanding, the authors have carried out a study of the morphology and development of 22 pre- and neonatal hips. At first, the acetabulum is cartilaginous and distorted by the moving femoral head; this acetabulum is histologically affected by the femoral pressure. The pathologic hip is characterized by defective posterior bony coverage of the femoral head by the acetabulum. The acetabulum ossifies during the 3 months following birth, forming a cup-like cavity under the pressure of the femoral head. Therefore, neonatal screening tests such as sonography must take place in the first weeks of life.

Acetabulum↗