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A modified technique of the triple pelvic osteotomy: early results.

A modification of the triple pelvic osteotomy for children over 8 years and the young adult is described. The results of the first 32 cases are reviewed. These show that the indications for the operation can be widened so that not only primary dysplasias but also subluxated or dislocated hips with secondary dysplasia can be operated on successfully. The operation is done in two stages. At first the patient is lying prone. The osteotomy of the ischial ramus is done dorsally by cutting the connection between the sciatic notch and obturator foramen immediately behind and below the acetabulum. In the second stage, with the patient lying supine, the pubic and the iliac osteotomy are performed rather circular and parallel to the hip joint. These modifications have several advantages: (a) the operator has a direct field of view at all times; (b) the osteotomy is performed close to the acetabulum, thus allowing a great amount of lateral rotation and medial displacement of the acetabulum, thereby providing good coverage of the femoral head by hyaline cartilage; and (c) the ischial ramus and its ligaments to the sacrum are left intact, leading to greater stability of the pelvis and spine.

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Acetabular coverage: three-dimensional anatomy and radiographic evaluation.

The three-dimensional relationship between acetabulum and femoral head, known as coverage, was evaluated radiographically using a modified inlet view of the pelvis. The relationship of the anterior edge, the center of the femoral head, and the posterior edge of the acetabulum is a straight line (180 degrees) in normal coverage but less in dysplastic hips. This radiographic method provides anatomical information concerning anterior and posterior coverage. Evaluation of 26 hips delineated problems, including possible danger of anterolateral rotation of the acetabulum in the face of posterior deficiency and inadequacy of posterior coverage after Chiari osteotomy.

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Lateral acetabular rotation improves anterior hip subluxation.

Surgical reorientation of the acetabulum is used to improve stability of subluxated or dysplastic hips, but the specific mechanical consequences of reorientation have not been quantified. I used a rigid body spring model of the human hip to study the effects of different acetabular positions on hip stability during single-limb stance. The model predicted subluxation direction and magnitude, and the effective joint contact area, as functions of acetabular position. Frontal plane acetabular orientation varied from 20 degrees medial rotation to 50 degrees lateral rotation, corresponding to center-edge angles from 0 degrees to 70 degrees. Sagittal acetabular orientation varied from 45 degrees anterior rotation to 15 degrees posterior rotation. Center-edge angles less than 20 degrees produced progressive anterolateral subluxation, with dislocation occurring when center-edge angles were less than 0 degrees. Lateral subluxation disappeared when cen-ter-edge angles were 30 degrees or greater. Anteroposterior subluxation was controlled by anterior or posterior rotation of the acetabulum in the presence of low center-edge angles, but there was no specific position of stability that effectively stabilized the femoral head. Anterior subluxation also was controlled by lateral rotation of the acetabulum. Joint contact area increased 1% for every 3 degrees lateral acetabular rotation. The anterolateral subluxation associated with hip dysplasia can be controlled by acetabular reorientation. Joint contact area will increase, thereby reducing peak joint pressure. Anterior and lateral subluxation can be improved by lateral rotation alone, which may reduce the severity of anterior femoroacetabular impingement after periacetabular osteotomy.

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Relation between vertical orientation and stability of acetabular component in the dysplastic hip simulated by nonlinear three-dimensional finite element method.

In acetabular dysplasia, more vertical orientation of the acetabular component is often used to minimize the superolateral bone grafting. This study was designed to determine the effects of vertical orientation of the cup on the stability and polyethylene wear of the acetabular component in uncemented total hip arthroplasty (THA). Three-dimensional finite element models of the hemipelvis with dysplastic acetabulum were developed. Metal-backed hemispherical cups were placed in the true acetabulum with abduction angles of 35, 45, 55, and 65 degrees. It was found that more vertical orientation of the cup was associated with larger relative motion of the metal shell between the acetabulum and metal shell. Furthermore, tilting and torsional shear stresses in the model of the cup abduction angle of 65 degrees were found to be 1.7 times larger than that in the model with 35 degrees at the bone-metal shell interface. More vertically oriented cups caused larger contact stresses at the articulating surfaces of the polyethylene liners. The results suggest that the abduction angle of the acetabular component significantly influences cup loosening and polyethylene wear in THA.

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Pharmacokinetic disposition of cefazolin in serum and tissue during canine total hip replacement.

Intraoperative cefazolin concentrations were measured in serum, joint capsule, cancellous bone of the acetabulum, and proximal cancellous bone of the femur in 15 dogs undergoing total hip replacement. Cefazolin (22 mg/kg intravenously [IV]) was administered every hour for three doses. The mean peak serum concentrations (+/- SEM) were 387.79 +/- 27.56 micrograms/mL, 521.71 +/- 28.00 micrograms/mL, and 542.20 +/- 30.91 micrograms/mL, respectively. Mean serum concentrations just before administration of doses 2 and 3 were 51.77 +/- 2.39 micrograms/mL, and 64.84 +/- 3.46 micrograms/mL, respectively. The mean cefazolin concentrations in the joint capsule, cancellous bone of the acetabulum, and cancellous bone of the femur were 34.71 +/- 2.50 micrograms/g, 28.70 +/- 7.40 micrograms/g, and 36.20 +/- 3.80 micrograms/g, respectively. The minimum inhibitory concentration of cefazolin for 90% of the common contaminants (MIC90) in this clinic is less than or equal to 2 micrograms/mL or per gram of tissue. Serum concentrations never fell below 15 times the MIC90 (lowest trough, 35.93 micrograms/mL), and the lowest tissue concentration (6.57 micrograms/mL in cancellous bone from the acetabulum) was still more than 3 times the MIC90. The mean tissue concentration was 15 times the MIC90.

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Normal acetabular anatomy for acetabular fracture assessment: CT and plain film correlation.

The computed tomographic (CT) and conventional radiographic appearances of the acetabulum are correlated for assessment of acetabular fractures according to the Judet and Letournel classification system, a system widely used by orthopedic surgeons performing fracture reduction and external fixation of the acetabulum. A desiccated pelvis was marked along the acetabular borders with lead solder, and anteroposterior (AP) and oblique radiographs were obtained. The solder was then replaced by barium-impregnated string, and the acetabulum was scanned by CT. Radiographic-CT correlations of acetabular landmarks should aid the orthopedist by providing a useful interpretation of acetabular fractures according to the Judet and Letournel system.

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Pelvic reconstruction using saddle prosthesis following limb salvage operation for periacetabular tumour.

PURPOSE: To assess the clinical results of pelvic reconstruction using a saddle prosthesis following limb salvage operation for periacetabular tumour. METHODS: 12 patients with sarcoma and 4 with metastasis involving the pelvis were treated using the saddle prosthesis between 1995 and 2003 inclusive. Wide pelvic resection was performed for all patients with sarcoma and one with a metastatic lesion; intralesional excision of the acetabulum was undertaken for the remaining 3 patients with metastatic lesions. Oncologic prognosis, operation time, postoperative function, and complications were assessed retrospectively. RESULTS: Of the 12 patients with sarcomas, 5 were alive without evidence of recurrence after a mean follow-up of 37 months, one was alive with disease, 3 died of the disease, and 3 of other medical conditions. Respective mean postoperative functional scores according to the Musculoskeletal Tumor Society-International Symposium on Limb Salvage system and the Toronto Extremity Salvage Score were 53 and 64% in patients undergoing wide acetabular resection, and 30 and 42% in patients undergoing intralesional excision of the acetabulum. In patients undergoing wide acetabular resection and intralesional excision of the acetabulum, the mean operation times were 391 and 162 minutes respectively, whereas the mean times to ambulation were 7 and 4 days respectively. Major complications included infection and dislocation. CONCLUSION: Saddle prosthesis arthroplasty is a useful option for pelvic reconstruction following resection of acetabular malignancies. It is associated with a short operation time, rapid recovery, and moderately good postoperative function, but a relatively high risk of complications.

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Effects of acetabular resurfacing component material and fixation on the strain distribution in the pelvis.

A 3D finite element (FE) model of an implanted pelvis was developed as part of a project investigating an all-polymer hip resurfacing design. The model was used to compare this novel design with a metal-on-metal design in current use and a metal-on-polymer design typical of early resurfacing implants. The model included forces representing the actions of 22 muscles as well as variable cancellous bone stiffness and variable cortical shell thickness. The hip joint reaction force was applied via contact modelled between the femoral and acetabular components of the resurfacing prosthesis. Five load cases representing time points through the gait cycle were analysed. The effect of varying fixation conditions was also investigated. The highest cancellous bone strain levels were found at mid-stance, not heel-strike. Remote from the acetabulum there was little effect of prosthesis material and fixation upon the von Mises stresses and maximum principal strains. Implant material appeared to have little effect upon cancellous bone strain failure with both bended and unbonded bone-implant interfaces. The unbonded implants increased stresses in the subchondral bone at the centre of the acetabulum and increased cancellous bone loading, resembling behaviour obtained previously for the intact acetabulum.

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A long-term follow-up of congenital dislocation of the hip.

Drawing upon a total experience of 450 hips affected by established congenital dislocation or subluxation, the author presents the long-term results in 177 hips treated for the first time between the ages of nine months and three and a half years, in support of his contention that surgical endeavour should in the first place be directed towards the limbus and upper end of femur rather than the acetabulum. The 144 patients, all treated on lines previously described in this journal (Scott 1953; Somerville 1953a, b; Somerville and Scott 1957), have now been followed up annually for between ten and twenty-five years, both hips receiving equal scrutiny. In brief, the routine has consisted of arthrography, excision of any limbus shown to be inverted, reduction by traction in abduction, and rotation osteotomy of 70 degrees. The addition of 10 to 15 degrees of varus was found beneficial and has become routine. Some hips required secondary procedures, and regret is expressed that these were not carried out sooner. The upper age at which recovery of the acetabulum may occur was found to be much higher than generally supposed, with a critical period between eleven and fourteen. The main conclusion is that in the great majority of cases first seen in this particular age group, improvement of the mechanics of the joint, especially by attention to the upper end of femur, leads to satisfactory development of the acetabulum and good functional results, at least up to early adult life.

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Congenital dislocation of the hip and computerised axial tomography.

CT scans of 18 hips with typical congenital dislocation have been studied in 16 children. These show that the common position of dislocation is lateral, superior and slightly anterior, and that a "false acetabulum" can be distinguished even in young children. A defect in the posterior ischium causing distortion of the acetabulum was also present in most cases. The cartilage and the acetabular contents were well shown. Positions of reduction and the anteversion of the acetabulum and the femoral neck were studied. Hypotheses are presented on the mode of dislocation and on the cause of the pathological changes.

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The predictability of acetabular development after closed reduction for congenital dislocation of the hip.

We have reviewed the serial radiographs of 63 hips in 53 children treated by closed reduction for congenital dislocation with a view to finding a radiological measurement which can predict subsequent acetabular development. All had been followed for more than seven years, and at latest review, 34 hips were dysplastic. Failure to obtain concentric reduction or its loss by migration of the femoral head within one year of reduction were the best predictors of persisting acetabular dysplasia and were best quantitated by the h/b ratio (Smith et al. 1968). The acetabular index at reduction or its decrease in the first year were not reliable predictors. Late treatment was less likely to lead to normal acetabular development, but avascular necrosis did not appear to have a significant influence. The average age at which the acetabulum stopped developing was five years, but ranged from 17 months to eight years. The failure of a dysplastic acetabulum to improve in each annual radiograph after closed reduction should lead to consideration of operation on the acetabulum.

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Cementless uncoated polyethylene acetabular components in total hip replacement. Review of five- to 10-year results.

We reviewed the results of 545 consecutive total hip replacements using a cementless non-coated high-density polyethylene acetabular component combined with a cemented Müller stem at five to 10 years. In all, 421 patients (445 hips) were available for review, 118 by questionnaire and 303 by examination and radiography. Of these, 86% had a good or excellent result. We found a high rate of radiological loosening of the cup after the sixth year, and a high rate of clinical loosening after the eighth year. Loosening was commoner in women, in younger patients and where a smaller size of acetabulum had been used. Calcar resorption was significantly related to loosening of the acetabulum. Loosening appeared to be mainly due to polyethylene debris produced by micro-movement of the acetabulum against the bone, which had resulted in a giant cell foreign body reaction and subsequent bone erosion. We have abandoned the use of this prosthesis and suggest that direct contact between bone and polyethylene should be prevented by a coating of metal or some other material.

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Microanatomy of the acetabular cavity and its relation to growth.

The anatomy and development of the growing acetabulum are not clearly understood. We dissected and studied histologically two acetabula from the pelvis of a three-month-old infant. Relative rates of growth at the different growth plates were assessed by comparing the height of the proliferative layer with that of the hypertrophic layer. The three bones which form the acetabulum are surrounded by growth plates on all sides except medially. These face towards the centre of the triradiate cartilage, the limbs of the triradiate cartilage and the articular surface and each may be divided into four distinct areas according to the orientation of its cell columns which reflect the direction of growth. Growth was particularly rapid at the ischial growth plates directed towards the centre and the articular cartilage, add on both sides of the anterior limb of the triradiate cartilage. These findings may explain the mechanism by which the acetabulum changes orientation and inclination with growth.

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The role of the acetabular labrum and the transverse acetabular ligament in load transmission in the hip.

We performed a biomechanical study of seventeen hip joints in the pelves of nine cadavera in order to assess the role that the acetabular labrum and the transverse acetabular ligament play in load transmission. The distribution of contact area and pressure between the acetabulum and the femoral head was measured with the hip in four different conditions: intact (seventeen hips), after removal of the transverse acetabular ligament (eight hips), after removal of the entire labrum (nine hips), and after removal of both the transverse acetabular ligament and the labrum (seventeen hips). The hip joint was loaded in simulated single-limb stance, and the measurements were made with use of pressure-sensitive film. A peripheral distribution of load was seen in the intact acetabula. This pattern was altered only minimally after removal of the transverse acetabular ligament or the labrum, or both. When both of these structures were removed, the only significant change was a decrease in the maximum pressure in the posterior aspect of the acetabulum (p = 0.02). No significant changes were detected with regard to the contact area, load, mean pressure, or maximum pressure in the anterior or superior aspect of the acetabulum under any testing condition.

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Total hip arthroplasty with bulk femoral head autograft for acetabular reconstruction in developmental dysplasia of the hip.

BACKGROUND: The long-term results of total hip arthroplasty performed with cement and use of a bulk autograft for acetabular reconstruction in patients with developmental dysplasia of the hip have varied considerably. We evaluated the results of total hip arthroplasties performed with acetabular bulk autograft to identify the factors that influence the results of this procedure. METHODS: Acetabular roof defects secondary to developmental dysplasia of the hip were reconstructed with a bulk femoral head autograft at the time of total hip arthroplasties performed with use of the Charnley technique and prosthesis. Thirty-seven hips in thirty patients (mean age at the time of the operation, fifty-seven years) were followed for ten to twenty-six years (mean, nineteen years). The Crowe classification of hip subluxation or dislocation was Group II for sixteen hips, Group III for seventeen, and Group IV for four. RESULTS: Coverage of the socket by the graft ranged from 5% to 49% (mean, 33%). Twenty-nine sockets were located within the true acetabulum, and eight were placed more proximally. At the time of the latest follow-up, all of the patients had an excellent clinical result, all of the grafts had united, and no hip had radiographic evidence of failure of the fixation. CONCLUSIONS: We found that total hip arthroplasty performed with cement and use of a bulk autograft to reconstruct an acetabulum with severe bone deficiency secondary to developmental dysplasia of the hip can provide long-term success in patients forty-eight years of age and older when coverage of the socket by the graft does not exceed 50%. When it is not possible to achieve >50% coverage of the socket by the ilium at the level of the true acetabulum, more proximal placement of the socket to obtain adequate coverage is recommended.

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Total hip arthroplasty with bulk femoral head autograft for acetabular reconstruction in DDH. Surgical technique.

BACKGROUND: The long-term results of total hip arthroplasty performed with cement and use of a bulk autograft for acetabular reconstruction in patients with developmental dysplasia of the hip have varied considerably. We evaluated the results of total hip arthroplasties performed with acetabular bulk autograft to identify the factors that influence the results of this procedure. METHODS: Acetabular roof defects secondary to developmental dysplasia of the hip were reconstructed with a bulk femoral head autograft at the time of total hip arthroplasties performed with use of the Charnley technique and prosthesis. Thirty-seven hips in thirty patients (mean age at the time of the operation, fifty-seven years) were followed for ten to twenty-six years (mean, nineteen years). The Crowe classification of hip subluxation or dislocation was Group II for sixteen hips, Group III for seventeen, and Group IV for four. RESULTS: Coverage of the socket by the graft ranged from 5% to 49% (mean, 33%). Twenty-nine sockets were located within the true acetabulum, and eight were placed more proximally. At the time of the latest follow-up, all of the patients had an excellent clinical result, all of the grafts had united, and no hip had radiographic evidence of failure of the fixation. CONCLUSIONS: We found that total hip arthroplasty performed with cement and use of a bulk autograft to reconstruct an acetabulum with severe bone deficiency secondary to developmental dysplasia of the hip can provide long-term success in patients forty-eight years of age and older when coverage of the socket by the graft does not exceed 50%. When it is not possible to achieve >50% coverage of the socket by the ilium at the level of the true acetabulum, more proximal placement of the socket to obtain adequate coverage is recommended.

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The prevalence of acetabular retroversion among various disorders of the hip.

BACKGROUND: Acetabular retroversion can result from posterior wall deficiency in an otherwise normally oriented acetabulum or from excessive anterior coverage secondary to a malpositioned acetabulum, or both. Theoretically, a retroverted acetabulum, which adversely affects load transmission across the hip, may occur more frequently in hips with degenerative arthritis. The aim of this study was to assess the prevalence of acetabular retroversion in normal hips and in hips with osteoarthritis, developmental dysplasia, osteonecrosis, and Legg-Calvé-Perthes disease. METHODS: We retrospectively examined anteroposterior radiographs of the pelvis of 250 patients (342 hips). Fifty-six patients (112 hips) had normal findings; sixty-six patients (seventy hips) had osteoarthritis; sixty-four (seventy-four hips), developmental dysplasia; thirty (thirty-six hips), osteonecrosis of the femoral head; and thirty-four (fifty hips), Legg-Calvé-Perthes disease. The sole criterion for a diagnosis of acetabular retroversion was the presence of a so-called cross-over sign on the anteroposterior radiograph of the pelvis. RESULTS: The prevalence of acetabular retroversion was 6% (seven of 112 hips) in the normal group, 20% (fourteen of seventy hips) in the osteoarthritis group, 18% (thirteen of seventy-four hips) in the developmental dysplasia group, 6% (two of thirty-six hips) in the group with osteonecrosis of the femoral head, and 42% (twenty-one of fifty hips) in the group with Legg-Calvé-Perthes disease. In patients with Legg-Calvé-Perthes disease, the prevalence of acetabular retroversion was 68% in twenty-five hips with Stulberg class-III, IV, or V involvement. In contrast, only four (16%) of twenty-five hips with Stulberg class-I or II involvement had acetabular retroversion. The difference was significant (p = 0.0002). Patients with osteoarthritis, developmental dysplasia, or Legg-Calvé-Perthes disease are significantly more likely to have acetabular retroversion than are normal subjects (p < 0.05). CONCLUSIONS: Acetabular retroversion occurs more commonly in association with a variety of hip diseases, in which the prevalence of subsequent degenerative arthritis is increased, than has been previously noted.

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Lateral acetabular growth stimulation following a labral support procedure in Legg-Calve-Perthes disease.

BACKGROUND: The main goal of containment treatment in cases of Legg-Calvé-Perthes disease is to prevent hip deformity, which leads to arthritis in adulthood. Recently, the shelf arthroplasty (the labral support procedure) has been proposed as a method of containment. The purpose of the present study was to evaluate growth stimulation of the acetabulum in patients with unilateral Legg-Calvé-Perthes disease by measuring acetabular depth and height following treatment with the labral support procedure. Uninvolved, contralateral hips and hips that were treated with proximal femoral varus osteotomy were used to compare growth. METHODS: Sixty-five consecutive patients with unilateral Legg-Calvé-Perthes disease that had been treated with the labral support procedure (forty-nine) or a proximal femoral varus osteotomy (sixteen) were evaluated on the basis of radiographic and clinical data that had been obtained at the time of surgery as well as at one, three, and five years after surgery. Acetabular dimensions (depth, height, and total depth with shelf) were measured and, to eliminate radiographic magnification error, the data were expressed in ratios between the involved and uninvolved sides. RESULTS: Preoperatively, both surgical groups were comparable. Acetabular depth indexes at the time of surgery were not different between the groups (p = 0.46). At one, three, and five years postoperatively, the mean depth indexes in the labral support group were significantly higher than those in the proximal femoral varus osteotomy group (F = 5.417, p = 0.001), and trend analysis showed a significant quadratic effect over time in the labral support procedure group (F = 13.132, p = 0.001). The acetabular height indexes at the time of surgery were not different between groups and showed 11% to 13% acetabular overgrowth. The acetabular height indexes in both groups remained unchanged at the time of follow-up (F = 2.82, p = 0.1). The total depth index showed decreasing linear trend values over the period studied (F = 35.115, p = 0.001). CONCLUSIONS: Overgrowth of the acetabulum occurs naturally and early in the course of Legg-Calvé-Perthes disease and is more pronounced in terms of height. The labral support procedure induces additional lateral growth of the true acetabulum (excluding the shelf) for three years following surgery, whereas a proximal femoral varus osteotomy does not. Thus, beneficial effects of the labral support procedure are lateral acetabular growth stimulation, prevention of subluxation, and shelf resolution after femoral epiphyseal reossification. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

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