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At least 325 records · Page 18Linked to original sources
PubMed1992

Acetabular micromotion as a measure of initial implant stability in primary hip arthroplasty. An in vitro comparison of different methods of initial acetabular component fixation.

Micromotion has been shown to affect bony ingrowth into cementless components. This study was designed both to quantitate initial micromotion at the prosthesis-periacetabular bony interface and to compare different methods of commonly employed acetabular component fixations, ie, a press-fit hemispherical titanium cup, a press-fit hemispherical titanium cup with one and two dome screws, a press-fit titanium hemispherical cup with three spikes, and a cemented chromium-cobalt cup. The press-fit component without screws demonstrated the greatest motion equaling 162 microns at the ilium, 97 microns at the publis, and 54 microns at the ischium. With one and two screws placed into the dome, the mean ileal displacement decreased by 28 microns (17%) and 36 microns (22%), respectively. Dome screw placement demonstrated a minimal effect at the pubis and ischium. Compared to the press-fit component without augmentation, the tri-spike motion was less at the pubis and ischium. The cemented prosthesis provided the least amount of motion in all three areas tested. This experiment demonstrates that the ilium provides the least amount of support to immediate acetabular fixation, while the pubis (anterior column) and ischium (posterior column) provide more stability. One dome screw does not affect the stability of a hemispherical prosthetic cup significantly. A two dome screw fixation provides an added method of support at the ilium, but fails to decrease motion at the pubis or ischium significantly. The tri-spike fixation does not restrict motion at the ilium to the extent as the dome screws, but its effect at the ischium and pubis is much more pronounced. The obvious difference between initial motion seen with cemented versus uncemented components may suggest that before surgery, patients may need a period of protected weight bearing until ingrowth has occurred.

Acetabulum↗
PubMed1991

Screw-augmented fixation of acetabular components. A mechanical model to determine optimal screw placement.

Sixteen embalmed hemipelves were used to determine the optimal acetabular screw placement to provide maximal screw pull-out strength in unicortical and bicortical screw fixation. The anterior column, superior ilium, posterior column, ischium, and pubis regions of the pelvis were tested using 6.5-mm titanium alloy screws and a hydraulic servo-controlled 1321 Instron testing machine. Force vs displacement data were acquired. Bicortical fixation was stronger than unicortical fixation in the four zones compared. This difference was significant in the superior ilium, posterior column, and ischium. The anterior column could not accept unicortical screws due to inadequate bone depth, which ranged between only 6 mm and 10 mm. Bicortical fixation was significantly greater in the superior ilium, posterior column, and ischium than in the anterior column or pubis. Unicortical fixation was greatest in the superior ilium. This information may aid decisions concerning the positioning of screws to augment acetabular component fixation.

Acetabulum↗
PubMed2003

Extraspinal bone hydatidosis.

BACKGROUND: Bone hydatidosis caused by the tapeworm larva, Echinococcus granulosis, is rare. Extraspinal locations are even rarer. We report our experience with the treatment of twenty-six patients with extraspinal osseous hydatidosis. METHODS: Between 1972 and 1998, we treated twenty-six patients with extraspinal hydatidosis. There were sixteen men and ten women, with a mean age of 51.5 years. The mean duration of follow-up was 12.8 years. The infected area was the ilium in four patients, the ilium and sacral ala in two, the ilium and hip in eight, the femoral head and the acetabular roof in five, the femoral shaft in one, the distal part of the femur in one, the femoral head in one, the scapula in two, and the ribs in two. All patients were treated with curettage or wide resection. Chemotherapy was used in all but five patients. RESULTS: Nineteen patients (73%) were free of disease at the time of the last follow-up. Repeated curettage or wide resection was necessary in nine of these patients; it was required in three of the nine because of surgical wound infection and in six because of recurrence. Of the seven patients who were not free of disease at the time of the last follow-up, six had persistent chronic productive sinuses and one had a chronic wound infection. The cases involving both the ilium and the hip were the most difficult to treat. Radical surgery is difficult in this location, and numerous surgical procedures were always required. CONCLUSIONS: The results of treatment of osseous hydatidosis are satisfactory only in locations where complete and wide excision is possible. In the pelvis and hip, where radical surgery is almost impossible, the results are disappointing.

Albendazole↗
PubMed2003

Characteristics of human body dynamic responses to landing impact in supine position.

OBJECTIVE: To study the characteristics of human body dynamic responses to landing impact. METHOD: Five healthy young men were exposed to 4-10 G for 50-80 ms half-sine acceleration pulse at 20 degrees supine angle and 10 G for 50 ms impact at 30 degrees to 60 degrees supine angles. The acceleration curves on the dropping platform of the impact tower, the seat, the human head, shoulder, chest and ilium, as well as ECG of the subjects were recorded. RESULT: The peaks of acceleration at the subject head, shoulder, chest, and ilium along chest-back direction rose with the increase of the impact level. The overshoots of acceleration at the subject head along head-ilium direction and chest-back direction were 93% and 102% respectively for 10 G at 20 degrees supine angle. With increase of supine angle, acceleration response at the subject along chest-back direction decreased. Acceleration response at the subject head along head-ilium direction was minimum at 40 degrees supine angle. CONCLUSION: Transfer function of the human body to landing impact demonstrated that human body had a series of resonance frequencies which were 25 Hz, 34 Hz, 39 Hz, 43 Hz, 50 Hz, 64 Hz, and 70 Hz respectively.

Acceleration↗
PubMed2006

Study of the morphology and biomechanics of sacral fracture.

OBJECTIVE: To observe the morphological characteristics of sacral fracture under different impact loads. METHOD: Ten fresh pelvic specimens were loaded in dynamic or static state. A series of mechanical parameters including the pressure strain and velocity were recorded. Morphological characteristics were observed under scanning electron microscope. RESULTS: The form of sacral fracture was related to the impact energy. Under low energy impact loads, ilium fracture, acetabulum fracture and crista iliaca fracture were found. Under high energy impact loads, three types of sacral fracture occurred according to the classification of Denis: sacral ala fracture, Type I fracture; sacral foramen cataclasm fracture, Type II fracture; central vertebral canal fracture, Type III fracture. Nerve injury of one or two sides was involved in all three types of sacral fracture. The fracture mechanism of sacrum between the dynamic impact and static compression was significantly different. When the impact energy was above 25 J, sacral foramen cataclasm fracture occurred, involving nerve root injury. When it was below 20 J, ilium and sacral fracture was most likely to occur. When it was 20 approximately 25 J, Type I fracture would occur. While in the static test, most of the fracture belonged to ilium or acetabulum fracture. The cross section of sacrum was crackly and the bone board of Haversian system was brittle, which could lead to separation of bone boards and malposition of a few of cross bone boards. CONCLUSIONS: In dynamic state, sacrum fracture mostly belongs to Type I and Type II, and usually involves the nerve roots. Sacrum fracture is relevant to the microstructures, the distribution of the bone trabecula, the osseous lacuna and the Haversian system of sacrum. The fracture of ilium and acetabulum more frequently appears in static state, with slight wound of peripheral tissues.

Biomechanical Phenomena↗
PubMedDate not supplied

Treatment outcome of pelvic sarcomas in young children: orthopaedic and oncologic analysis.

Five children with pelvic Ewing's sarcoma whose age was 6-10 years underwent reconstruction after resection of the tumor. One child with a tumor of the ilium underwent an iliosacral arthrodesis with allograft. Three patients underwent a hip transposition after the resection of the ilium and the upper part of the acetabulum. One patient underwent no skeletal reconstruction after the resection of the acetabulum and the ilium. Two children are alive 96 and 60 months after surgery; however, two died 12 and 21 months after surgery of metastasis, and one is alive with metastasis 15 months after surgery. Functional evaluation was possible in four patients: one is excellent, and three are fair. After resection of the ilium, including the upper part of the acetabulum, a hip transposition can be selected. If all the acetabulum is resected, it will be optimal not to do a bony reconstruction.

Bone Neoplasms↗
PubMed2025

The evolution of hominin bipedalism in two steps.

Bipedalism is a human-defining trait1-3. It is made possible by the familiar, bowl-shaped pelvis, whose short, wide iliac blades curve along the sides of the body to stabilize walking and support internal organs and a large-brained, broad-shouldered baby4-6. The ilium changes compared with living primates are an evolutionary novelty7. However, how this evolution came about remains unknown. Here, using a multifaceted histological, comparative genomic and functional genomic approach, we identified the developmental bases of the morphogenetic shifts in the human pelvis that made bipedalism possible. First, we observe that the human ilium cartilage growth plate underwent a heterotopic shift, residing perpendicular to the orientation present in other primate (and mouse) ilia. Second, we observe heterochronic and heterotopic shifts in ossification that are unlike those in non-human primate ilia or human long bones. Ossification initiates posteriorly, resides externally with fibroblast (and perichondral) cells contributing to osteoblasts, and is delayed compared with other bones in humans and with primate ilia. Underlying these two shifts are regulatory changes in an integrated chondrocyte-perichondral-osteoblast pathway, involving complex hierarchical interactions between SOX9-ZNF521-PTH1R and RUNX2-FOXP1/2. These innovations facilitated further growth of the human pelvis and the unique formation of the ilium among primates.

Animals↗
PubMed2004

Morbidity of harvesting of bone grafts from the iliac crest for preprosthetic augmentation procedures: a prospective study.

It has been the aim of the present prospective clinical study to assess the morbidity following the harvest of bone from the anterior and posterior ilium in elective preprosthetic augmentations. Fifty consecutive healthy patients (30 female, 20 male, mean age 52.5+/-9.3 years, range 31 years to 65 years) underwent augmentations of implant sites by iliac crest bone grafts. The bone harvest was carried out in 25 cases from the anterior and in 25 cases from the posterior ilium. The superficial sensory function of the skin was determined quantitatively preoperatively, 7 and 30 days after surgery with the 'Pain and Thermal Sensitivity' Test (PATH Test). On the same occasions subjective pain on a visual analogue scale (VAS) and gait disturbances were documented. In the PATH Test, for the innervation areas of the lateral femoral cutaneous nerve (LFCN) and the superior and middle cluneal nerves (SMCN) a significant impairment of the superficial sensory function could be found after 1 week and a significant tendency towards recovery after 1 month (warm stimulus(FCNpreop) 37.9+/-3.0 degrees C, warm stimulus(LFCNday7): 38.6+/-3.2 degrees C, warm stimulus(LFCNday30): 37.9+/-2.9 degrees C, P(LFCNwarmpreop/day7)=0.023,P(LFCNwarmpreop/day30) =0.886, warm stimulus(SMCNpreop): 36.1+/-2.4 degrees C, warm stimulus(SMCNday7): 36.6+/-2.3 degrees C, warm stimulus(SMCNday30): 36.3+/-4.0 degrees C,P(SMCNwarmpreop/day7) <0.0005,P(SMCNwarmpreop/day30) =0.086). Gait disturbances were seen in seven patients after anterior and in three patients after posterior bone harvest 7 days after surgery (P(gaitdisturbanceanterior/posterior)=0.123). After 1 month none of the patients of both groups showed gait disturbances any longer. The maximum subjective pain level was found on the second postoperative day in both groups. It was significantly higher for the anterior approach (VAS(anteriorday2) 7.0+/-1.5, VAS(posteriorday2) 5.5+/-1.8,P(VASanterior/posteriorday2) =0.004). At day 7 and at day 30, the pain levels did no longer differ significantly (VAS(anteriorday7) 3.7+/-1.4, VAS(posteriorday7) 3.2+/-1.6,P(VASanterior/posteriorday7) =0.165, VAS(anteriorday30) 1.4+/-0.7, VAS(posteriorday30) 1.4+/-0.8,P(VASanterior/posteriorday30) =0.724). Because of the lower morbidity of bone harvest from the posterior ilium in the early postoperative phase compared to the anterior approach it seems that it should be preferred in elective augmentation procedures.

Adult↗
PubMed1982

[Isolated ilial tuberculosis and its differential diagnosis].

Isolated tuberculous foci in the ilium are particularly rare. Over a period of 26 years (1955 to 1981) we have treated ten lesions in the ilium in our Clinic. Only two (one male, one female) were of tuberculous origin, the other consisted of non-specific osteomyelitis, one sarcoma and one lesion in a Hand-Schüller-Christian syndrome. In the discussion, the literature is reviewed concerning the frequency, features, treatment, prognosis and differential diagnosis of specific infections of the ilium.

Adult↗
PubMed2005

Risks to the superior gluteal neurovascular bundle during percutaneous iliosacral screw insertion: an anatomical cadaver study.

BACKGROUND: Iliosacral screws are a popular technique used to treat complicated injuries of the pelvis. It is well recognized that this technique entails some potentially disabling complications, including damage to vessels and lumbosacral nerves. The recommended insertion site for iliosacral screws into the S1 body lies along the posterior ilium between the greater sciatic notch and the iliac crest. The anatomy and course of the superior gluteal nerve and vessels have been described along the outer aspect of the posterior ilium. Injury to the superior gluteal nerve and vessels has been reported during pelvic surgery, including the insertion of iliosacral screws. The purpose of this study is to assess the risks of injury and proximity of percutaneously inserted iliosacral screws to the superior gluteal nerve and vessels using a cadaver model. MATERIALS AND METHODS: Twenty-nine cadaver pelvises for a total of 58 sides (58 screws) were studied. Percutaneous iliosacral screws were placed into the first sacral bodies using multiplanar fluoroscopic guidance. The superior gluteal neurovascular bundle was then studied via a posterior dissection. Injury to the neurovascular bundle was noted if it occurred, and the distance between the screw head and the neurovascular bundle was measured. Distances from the screw head to the crista glutea, greater sciatic notch, and iliac crest were also measured. RESULTS: The branching pattern of the superior gluteal nerve and vessels after they exit the greater sciatic notch demonstrated considerable variation, but was generally consistent with prior descriptions in most cases. Ten of 58 (18%) iliosacral screws caused injury to the superior branch of the superior gluteal nerve and vessels; 8 neurovascular bundles were impaled and 2 others were partly entrapped between the screw head and the ilium. The mean distance from the head of the iliosacral screws to the deep superior branches of the superior gluteal nerve and vessels was 9.1 mm (+/- 6.8 mm). The mean distances from the screw head to the crista glutea, sciatic notch, and iliac crest were 19.5 mm (+/- 4.9 mm), 33.0 mm (+/- 6.4 mm) and 50.3 mm (+/- 4.6 mm). Of the screws that caused superior gluteal nerve and vessels injury, all were within the "desired" area of insertion. CONCLUSIONS: The deep superior branch of the superior gluteal nerve and vessels, which provides major blood and nerve supply to the G. medius and G. minimus, is at significant risk during the percutaneous placement of iliosacral screws even when "well placed" and soft tissue protecting cannulas are used. The clinical effects of these injuries remain poorly understood.

Bone Screws↗
PubMed1991

Bone biopsy in the horse. 2. Evaluation of histomorphometric examination.

The histomorphometrical examination of a series of bone biopsies from the wing of ilium of foals and older horses is reported. Biopsies were obtained from 20 clinically normal horses, which had previously been infused with tetracycline intravenously twice at a 7 day interval at a dose rate of 10 to 15 mg kg-1. The horses were divided into 2 groups. Group 1 consisted of 10 foals (mean age: 4 +/- 1 months) which were biopsied at 3 different sites in the wing of ilium. Group 2 comprised 10 older horses (mean age: 91 +/- 63 months) which were biopsied from only one site in the left ilium. A systematic evaluation of intra-observer, intra-core, intra-bone and inter-bone errors was made to investigate parameter variations that might affect interpretation of bone biopsies. The measurements carried out included cancellous bone volume (Cn-BV/TV), osteoid surface (OS/BS), eroded surface (ES/BS), mean wall thickness (W.Th), mean osteoid thickness (O.Th), distance between labels (Ir.L.Th) and mineralizing surface (MS/BS). The intra-observer variance, the variance between sections, the variance between adjacent biopsies and that between right and left sides proved to be smaller than the inter-individual variance. The estimate of errors associated with the histomorphometrical analysis of bone biopsies is important for correct interpretations of changes due to disease.

Animals↗
PubMed1985

Irreversible bone loss in osteomalacia. Comparison of radial photon absorptiometry with iliac bone histomorphometry during treatment.

We examined the relationships between the changes in bone mineral deficit in the radius, determined by single-energy photon absorptiometry at standard proximal and distal sites, and in the ilium, determined by bone histomorphometry, during the treatment of osteomalacia of diverse etiology in 28 patients. In the ilium, relative osteoid volume decreased by 75-80% in both cortical bone (from 6.0% to 1.5%) and trabecular bone (from 30.1% to 6.6%) during a mean treatment duration of 2 yr. There was also a significant fall in iliac cortical porosity from 10.3% to 7.8%. As a result, mineralized bone volume increased by 7.5% in cortical and by 40.1% in trabecular bone; the cortical and trabecular increments were correlated (r = 0.69, P less than 0.001). The properly weighted increase for the entire tissue sample was 18.6%. By contrast, there was no change in bone mineral at either radial site, although there was a 2% increase at both sites when allowance was made for age-related bone loss during treatment. The proximal and distal age-adjusted increments was correlated (r = 0.76, P less than 0.001), but there was no correlation between the changes in any photon absorptiometric and any histomorphometric index. In that iliac cortical bone turnover in normal subjects was 7.2%/yr, we estimated the rate of bone turnover to be less than 2%/yr at both proximal and distal radial sites, including any trabecular bone present at the distal site. Compared to appropriate control subjects, the bone mineral deficits fell during treatment from 19.2% to 17.1% at the proximal radius (greater than 95% cortical bone) and from 20.5% to 18.5% at the distal radius (greater than 75% cortical bone). In the ilium the deficits, assuming attainment of normal values for osteoid volume and cortical porosity, fell from 41.7% to 36.1% in cortical and from 31.5% to 6.3% in trabecular bone, the properly weighted combined deficit falling from 38.6% to 27.7%. The irreversible iliac cortical deficit was entirely due to cortical thinning because of increased net endosteal resorption; the resultant expansion of the marrow cavity offset the modest loss of fractional trabecular mineralized bone. We conclude: in osteomalacia there is a large irreversible and a small reversible bone mineral deficit at both proximal and distal radial sites, in similar proportion to the iliac cortex but of smaller magnitude; the anatomic basis of the irreversible bone mineral deficit at all three sites that persists despite correction of the mineralization defect by appropriate treatment is thinning of cortical bone, most likely owing to prolonged secondary hyperparathyroidism; (c) there is no evidence that the proportion of trabecular bone in the distal radius at any site proximal to the radioulnar joint has any relevance to the interpretation of measurements made at that site; (d) there are at least three functional subdivisions of trabecular bone depending on proximity to hematopoietic marrow, fatty marrow, or synovium; and (e) single photon absorptiometry of the radius is an excellent method for measuring cortical bone mass in the appendicular skeleton, but is of little value for the assessment of changes in trabecular bone status.

Biopsy↗
PubMed1990

Pelvic anatomy relative to lumbosacral instrumentation.

Anatomical study of 72 pelves revealed that the most substantial area of bone that could best support a rod for surgical fixation is the body of the ilium, with the best part of the bone being the area above the sciatic notch. Placement of the rods into the body of the ilium provides good fixation but requires complex bending of the rods and a good three-dimensional perception of the osseous anatomy of the pelvis. This study was undertaken to define the intraosseous anatomy and the range of anatomical variation of the ilium. The results of this study are useful in developing a prebent spinal fixation rod, providing a better understanding of this anatomical area from a three-dimensional perspective and providing better lumbosacral spinal instrumentation.

Anthropometry↗
PubMed1988

[Surgical treatment of bone and soft tissue tumors in the sacroiliac area--low- and high-grade neoplasms].

Operative treatment of tumors in the sacroiliac area is very difficult for the orthopedic surgeon. We reviewed low- and high-grade neoplasms in the sacrum and part of the ilium. Primary bone tumors were giant cell tumor, chondrosarcoma and others; invading bone tumors were carcinoma, rhabdomyosarcoma and others; soft tissue tumors were liposarcoma, metastasis of extraskeletal chondrosarcoma and others; total, 19 cases. The preoperative treatment performed was embolization, intra-arterial infusion (chemotherapy) and radiation therapy. The surgical approach used were the posterior, posterolateral, anterior and posterior, anterior and lateral combined approach. The transiliac procedure using the posterolateral approach gives better visualization adjacent to the sacroiliac area. The gap between the sacrum and the ilium is bridged by grafting the resected ilium. The anterior and lateral combined approach was used in the resection of large iliac tumors, and the abdominoinguinal approach was selected for large retroperitoneal tumors. The surgical treatment performed ranged from simple to wide excision, including the external iliac vessels or rectum, and also palliative surgery. Reconstructive surgery was done for reconstruction of the pelvic ring, spinal fusion using instrumentation and replacement of artificial vessels. Many complications and functional loss requiring treatment were encountered.

Adolescent↗
PubMed1982

Methylmethacrylate reconstruction of large iliac crest bone graft donor sites.

Often full-thickness iliac crest grafts are necessary for various reconstructive procedures. Sometimes large defects remain in the donor ilium subsequent to their removal. Several complications have occurred as a result of these bony defects. Although several reports have been published regarding the repair of iliac herniae, little has been written about procedures to prevent these complications. A technique was devised to reconstruct the ilium with methylmethacrylate. After preparation of the defect, malleable retractors are bent to conform to the contour of the iliac crest. Methylmethacrylate is then packed into the mold made by the retractors. After hardening, the methylmethacrylate casting of the defect is trimmed and routine soft tissue closure is performed. This technique has been used in eight patients without any complications. The appearance of the waist and crests has been excellent; there have been no fractures or displacements of the mass of cement and there have been no infections. All these reconstructions have been mechanically stressed as all patients had well molded postoperative casts and/or braces. Reconstruction of the ilium with methylmethacrylate after removal of full-thickness grafts appears to be a reliable, safe, and easy technique based on a short-term follow-up of up to three years.

Adolescent↗
PubMed1994

Relationship of donor site to chondrogenic potential of periosteum in vitro.

Periosteum has been shown in vitro and in vivo to have a chondrogenic potential that permits it to be used for cartilage regeneration. A useful donor site should have good chondrogenic potential, availability of a large quantity of periosteum, and relative ease of access, and it should be associated with a low rate of morbidity. We hypothesized that the chondrogenic potential of periosteum varies from one bone to another and among different regions of the periosteum from a single bone. A total of 370 periosteal and 37 fascia lata (control) explants were taken from the skull, the ilium, the scapula, the upper, middle, and lower medial proximal tibia, the posterior proximal tibia, and the distal tibia of 2-month-old New Zealand rabbits. The explants were cultured for 6 weeks in agarose/Dulbecco's modified Eagle medium to which 10 ng/ml of transforming growth factor-beta 1 was added during the first 2 weeks. Skeletal muscle and fascia lata were used as controls. In addition, the thickness, cell density, and total cell count of the cambium layer were measured in 24 explants from the donor sites on the ilium and the upper, middle, and lower proximal tibia. At 6 weeks, histomorphometry and quantitative collagen typing were performed. The periosteal donor sites could be grouped into three categories according to chondrogenic potential: ilium (best), scapula and tibia, and skull (no chondrogenesis). The scapular periosteum was slightly better than that from the tibia. Within the tibia, the upper and middle zones of the proximal region were similar and were slightly better than the lower proximal tibia or the distal tibia. The cellularity of the cambium layer correlated positively with the amount of cartilage as a percentage of the total area. The results of this study indicate that iliac periosteum exhibited the best overall chondrogenic potential in vitro but that periosteum from the traditionally used medial proximal tibia also was excellent. Periosteum from the skull was not chondrogenic. The chondrogenic potential of periosteum varies from bone to bone and within the periosteum from one bone. This variation in chondrogenic potential among donor sites may be due to a difference in the total cell count of the cambium layer.

Analysis of Variance↗
PubMed2000

A simplified Galveston technique for the stabilisation of pathological fractures of the sacrum.

Mechanical stabilisation of pathological fractures of the sacrum is technically challenging. There is often inadequate purchase in the sacrum, and stabilisation has to be achieved between the lumbar vertebrae and ilium. We present a simplification of the Galveston technique. We treated a total of six patients with this technique, four for metastatic disease and two for primary tumours. Our technique consists of the formation of a proximal stable construct using ISOLA pedicle screws linked distally using a modular system of connectors to threaded iliac bolts with cross linkages. Neurological decompression and fusion was performed as appropriate. The benefits of this method are: ease of access to the ilium, a solid purchase to the ilium, less rod contouring and shorter operating time. We have had no operative complications from this procedure. All patients were discharged home mobile, with a reduced opiate requirement.

Adolescent↗
PubMed1982

Stress distributions in the acetabular region--I. Before and after total joint replacement.

Two-dimensional finite element analyses of the acetabular region before and after hip replacement were conducted. The distribution of pressure at the acetabular surface for the single limb stance phase of gait was transformed to nodal loads to stimulate in vivo loading conditions. A nonhomogeneous distribution of bone elastic properties was incorporated in the models. The results demonstrated that the principal stresses in the normal acetabulum were aligned with the principal orientations of the trabeculae. Total joint replacement increased the von Mises' equivalent stresses in the cancellous bone immediately superior to the acetabular cup, and increased stresses in the medial wall of the ilium. Biaxial, tension-compression stresses were created in the layer of bone cement and introduced in the medial wall of the ilium. Tensile stresses in the bone cement were greatest at the superior roof and at the inferior margin of the cup. Tensile stresses in the cup were more pronounced at the margins, particularly near the inferior lip. The cup tended to close in such a manner as to grip the head of the femoral component as it was pressed between the medial and lateral walls of the ilium.

Acetabulum↗