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PubMed2005

Imaging findings of femoroacetabular impingement syndrome.

Femoroacetabular impingement syndrome (FAI) is a pathologic entity which can lead to chronic symptoms of pain, reduced range of motion in flexion and internal rotation, and has been shown to correlate with degenerative arthritis of the hip. History, physical examination, and supportive radiographic findings such as evidence of articular cartilage damage, acetabular labral tearing, and early-onset degenerative changes can help physicians diagnose this entity. Several pathologic changes of the femur and acetabulum are known to predispose patients to develop FAI and recognition of these findings can ultimately lead to therapeutic interventions. The two basic mechanisms of impingement-cam impingement and pincer impingement-are based on the type of anatomic anomaly contributing to the impingement process. These changes can be found on conventional radiography, MR imaging, and CT examinations. However, the radiographic findings of this entity are not widely discussed and recognized by physicians. In this paper, we will introduce these risk factors, the proposed supportive imaging criteria, and the ultimate interventions that can help alleviate patients' symptoms.

Acetabulum↗
PubMed2006

Acetabular retroversion as a rare cause of chronic hip pain: recognition of the "figure-eight" sign.

While well-recognized in the orthopedic literature as a cause of chronic hip pain, acetabular retroversion has not been specifically described in the radiologic literature. Acetabular retroversion represents a particular form of hip dysplasia characterized by abnormal posterolateral orientation of the acetabulum. This pathophysiology predisposes the individual to subsequent anterior impingement of the femoral neck upon the anterior acetabular margin and fibrous labrum. Without treatment, cases may progress to damage of the anterior labrum and cartilage, with eventual early onset of osteoarthritic disease. This impinging condition has been described as occurring in isolation or as part of a complex dysplasia. We describe two cases of acetabular retroversion diagnosed by conventional radiographic evaluation of the pelvis, one in isolation and one occurring in the setting of a larger congenital syndrome. These cases illustrate the utility of the "figure-eight" sign in identifying abnormalities of acetabular version and thus assisting clinicians in properly identifying these individuals so that appropriate therapy may be instituted.

Acetabulum↗
PubMed1997

MR imaging of supra-acetabular insufficiency fractures.

OBJECTIVE: Diagnosis of insufficiency fractures in the pelvis is difficult, especially in patients with prior malignancy, irradiation, steroid therapy or osteoporosis. This report shows the MR imaging appearance of supra-acetabular insufficiency fractures and how they can be differentiated from metastatic disease. DESIGN AND PATIENTS: Twelve patients (four men, eight women, average age 72.8 years) at risk for pelvic insufficiency fractures and who had pelvic or hip pain were studied with MR imaging. Indications were possible recurrent tumor or previous radiation to the pelvis (7 patients); osteoporosis from steroid use in rheumatoid arthritis (two patients); to exclude osteonecrosis of the hip (two patients); or to rule out a hip fracture (one patient). RESULTS: A characteristic linear region of low signal intensity on both T1- and T2-weighted sequences was found in the supra-acetabular region paralleling the superior acetabulum in a curvilinear are in 92% (11/12) of cases, and oblique in origin in 8% (1/11). Diffuse bands of high signal on T2-weighted images indicated surrounding edema. In two cases, MR findings obviated biopsy. One patient underwent a biopsy prior to the imaging studies being reviewed. All patients were treated conservatively and did well. DISCUSSION: Attention to insufficiency fractures has previously focused on characteristic locations in the sacrum and pubic bones. Supra-acetabular insufficiency fractures also occur and are difficult to diagnose without a high degree of suspicion. MR imaging is a useful tool for diagnosing supra-acetabular insufficiency fractures. The characteristic MR imaging appearance of these fractures can preclude additional diagnostic studies and therapy in most instances.

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PubMed2004

Acetabular reconstruction in developmental hip dysplasia using reinforcement ring with a hook.

We followed prospectively 27 patients with severe acetabular bone-stock deficiencies due to developmental dysplasia of the hip. Mean preoperative patient age was 56 (34-78) years, mean Harris hip score was 31 (16-66) points and pre-operative mean acetabular angle of Sharp was 47 degrees (34 degrees - 61 degrees). Operative acetabular reconstruction was performed in 28 hips using reinforcement ring with a hook placed in the true acetabulum and autologous bone grafting. A 2-year clinical and radiological follow-up was available in 27 hips. Mean Harris hip score improved to 91 (70-100) points. There were no clinical or radiological signs of aseptic loosening in 25 hips, and the bone graft was radiologically incorporated in all hips. In 24 hips, a radiostereometric analysis showed low rates of non-progressive translation and rotation in 21 reinforcement rings. Three rings showed progressive translation and/or rotation at the 2-year follow-up and were rated probably loose.

Acetabulum↗
PubMed2005

Total hip arthroplasty for developmental hip dysplasia.

We reviewed 38 hip replacements in 33 female patients (mean age 55.3 years) with developmental hip dysplasia. One patient had died and the remaining 32 patients (36 hips) had a mean follow-up of 12.2 years (range 8-19 years). All hips were replaced using the Müller cemented implant, and in 32 hips bulk femoral head autograft was used. In 33 hips the socket was reconstructed at the level of the true acetabulum. Complications included one intra-operative femoral fracture and two early dislocations. Correction of leg length discrepancy was possible in 30 patients. The post-operative mean modified Merle d'Aubigne and Postel scores for pain, movement and walking were 5.9, 5, and 5.3 respectively. One cup was revised due to aseptic loosening at ten years. All grafts united, but minor graft resorption was noticed in 24 hips, moderate in 2 hips and major in 1 hip.

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PubMed2005

Prospective bone density changes after periacetabular osteotomy: a methodological study.

We used computed tomography (CT) and 3D design-based sampling principles (stereology) to estimate changes in acetabular bone density after periacetabular osteotomy. We included six consecutive patients with hip dysplasia in the study. Baseline density was measured within the first 7 days following periacetabular osteotomy and compared with bone density 2 years later. Double measurements were performed on three patients, and the coefficient of error of the mean was estimated to 0.05. Bone density in zone 1 increased significantly in the anteromedial quadrant as well as in the posteromedial quadrant of the acetabulum. In the anterolateral and the posterolateral quadrant, bone density was unchanged. In zone 2 and 3, bone density was unchanged 2 years postoperatively. We suggest that the observed increase in bone density medially represents a remodelling response to an altered load distribution after osteotomy. The method used is a precise tool to estimate changes in acetabular bone density.

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PubMed2000

Cementless cup supporter for protrusio acetabuli in patients with rheumatoid arthritis.

The MC cup supporter is an acetabular reinforcement ring for the Harris-Galante (HG) cementless porous-coated socket. This supporting ring has been used with autogenous bone graft since 1991 in the management of protrusio acetabuli in patients with rheumatoid arthritis (RA). We have reviewed 15 hips in 13 patients at an average of 53.6 months (range 24-84 months) after operation. The clinical results of total hip arthroplasty (THA) in protrusio acetabuli using this ring were satisfactory. All grafts appeared to have united radiologically with no radiolucent lines between graft and acetabulum.

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PubMed1999

Bilateral acetabular fracture without trauma.

In the absence of trauma fracture of the acetabulum is an extremely rare injury. We describe a 70 year old man who spontaneously developed fractures in both acetabulae due to bony insufficiency. It was successfully treated by bilateral total hip replacement.

Acetabulum↗
PubMed2002

Anatomical and radiological correlation of Lequesne's "false profile".

Lequesne introduced a radiological projection, which is an oblique view of the edge of the acetabulum, to diagnose arthrosis affecting the anterior part of the joint and to measure the anterior coverage of the femoral head. In this study, we attempted to determine the anatomical correlation of his technique. Fifteen in vitro hemipelvises underwent radiography according to Lequesne's description, using metallic markers and wires to mark physical landmarks. According to geometric laws, the points used by Lequesne do not correlate anatomically. Although Lequesne's technique allows a diagnosis of acetabular dysplasia, measurements are on average 5.5 degrees less than those made anatomically.

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PubMed2003

Vascularized pedicled iliac crest graft for selected total hip acetabular reconstructions: a cadaver study.

Bone grafting is an essential part of most total hip acetabular reconstructions. There are a limited number of surgical options, each with inherent disadvantages for the management of structural acetabular defects. In this cadaver study, the authors aimed to evaluate the availability of vascularized pedicled iliac crest graft for the purpose of acetabular reconstruction. The hip joints, ilia and deep circumflex iliac artery pedicles of six adult preserved cadavers were dissected bilaterally. A segment of the iliac crest was elevated on the vascular pedicle and its access to different parts of the acetabulum was evaluated. The average pedicle length was sufficient for coverage of the superior and anterior acetabular walls. The access to the posterior wall, however, required modification of the bone size. A vascularized pedicled iliac crest graft is suitable for the reconstruction of selected acetabular deficiencies.

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PubMed2000

Acetabular ossicles: normal variant or disease entity?

Ossicles located in the acetabular fossa may confuse diagnostic and therapeutic work-up. An accessory ossification centre may persist unfused as an os acetabuli centrale which is surrounded by intact hyaline cartilage representing an anatomic variant. Bone islands located in the pillars of the acetabulum can project into the acetabular fossa simulating acetabular ossicles. Osteochondrosis dissecans, posttraumatic articular bodies, degenerative disease and other rare lesions may be responsible for clinical symptoms and are of similar appearance than anatomic variants. Plain film radiography, X-ray tomography, CT and MRI are used to categorize these lesions. MRI is very valuable to assess cartilage integrity in a noninvasive way, but arthro-CT or arthro-MRI have to be used in unclear cases. Therefore the purpose of this presentation is to discuss the appearance, the possible etiology and the differential diagnosis of acetabular ossicles and how they can be evaluated to avoid an unnecessary arthrotomy.

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PubMed2002

[The juxtaacetabular ganglion].

A juxtaarticular ganglion (JAG) is a rare tumor-like lesion of the acetabulum, causing chronic hip disability. Due to its location, a JAG is a special form of an intraosseous ganglion. There is a lack of histological criteria to differentiate a JAG from an osteoarthritic cyst. The clinical findings of a JAG are determined by its proximity to the joint gap and its extraarticular extension. In a case report the necessary diagnostics as well as the therapeutic consequences are discussed.

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PubMed2003

Two alternative methods for the measurement of MZ distance on a hip radiograph.

BACKGROUND: The aim of this study was to assess the use of two alternative measurement methods for the MZ distance, the distance between the acetabular centre (M) and the femoral head centre (Z), on an anteroposterior hip radiograph. METHODS: The MZ distance was measured in 900 normal and 34 dysplastic adult hips by using the classic method (MZ-c) and two alternative methods (MZ-m and MZ-x). MZ-m utilized the vectorial distance between points M and Z, like MZ-c, but was expressed as a positive or negative value according to the localization of the points with respect to each other. MZ-x was the projected distance between points M and Z on the x-axis, which was the line perpendicular to the two parallel lines passing through points M and Z, and was expressed as a positive or negative value according to the localization of the points with respect to each other. RESULTS: There was a significant correlation between the centre-edge angle and the three measurement methods in both normal and dysplastic hips. The lowest normal limits for MZ-m and MZ-x in adult hips were considered to be -3 mm and -2 mm, respectively (point Z is lateral to point M). Intraobserver and interobserver measurement variations of both methods were less than 2 mm. CONCLUSION: Both alternative methods were considered more useful than the classic one in the exact determination of the distance between the centres of the femoral head and the acetabulum.

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PubMed2004

Radiographic and magnetic resonance imaging findings of polylevolactic acid screws after rotational acetabular osteotomy.

INTRODUCTION: Biodegradable polylevolactic acid implants have become more commonly used for the treatment of fractures and osteotomies over the past few years. In the present study, the biocompatibility and degradation of polylevolactide screws used for rotational acetabular osteotomy were assessed on the basis of radiographic and MRI findings. MATERIALS AND METHODS: Forty-nine hips of 47 patients were analyzed for this study. The average age of the patients at the time of surgery was 38.0 years (range 18-62 years). The original diagnosis was osteoarthritis in 43 hips and osteonecrosis in 6 hips. The mean duration of follow-up was 2.8 years (range 1.5-5.5 years). Anteroposterior radiographs obtained at 1 week, 6 months, 1 year after the operation, as well as the most recent radiographs, were used to assess bony union, the radiolucent tract of each screw, and the sclerotic rim around each screw. Fifteen patients were chosen randomly to undergo MRI. RESULTS: Union of the osteotomized surfaces occurred in all patients within 6 months of surgery. Radiographs showed no osteolysis, no formation of bone cysts, and no displacement of the osteotomized acetabulum in any of the 49 hips. None of the patients was found to have any complications caused by problems with the biocompatibility of the implants. At the final postoperative examination, a central radiolucent tract and a sclerotic rim around the screws were seen in 34/49 hips (69%) and 23/49 hips (47%), respectively. On MRI findings, we were able to detect significant resorption of the screws in two patients after 1.2 and 1.7 years of follow-up. Though localized low-intensity areas on T1-weighted images and high-intensity areas on T2-weighted images were observed at the top of the screws in 5 patients, there was no development of pain, tenderness, or a sinus during the follow-up period. CONCLUSION: Although absorption of polylevolactic acid screws did not occur in a large majority of cases, rotational acetabular osteotomy appears to be a good indication for the use of polylevolactic acid screws.

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PubMed2004

Acetabular reduction osteotomy using surgical dislocation of the hip joint for treatment of a malunited acetabular fracture.

INTRODUCTION: Acetabular fractures remain a challenge for the orthopedic and trauma surgeon, with frequently poor outcome in terms of pain and lack of motion and high rate of posttraumatic arthritis especially in badly reconstructed fractures where the anatomy was not restored. Surgical treatment of malunited acetabular fractures is often necessary, although it can be very complex. CASE PRESENTATION: We report a young woman who sustained both column fracture with central dislocation of the femoral head in which the posterior wall fragment was initially not fixed anatomically. CONCLUSIONS: Surgical dislocation of malunited acetabular fractures is a relatively new therapeutic option that provides full access to the femoral head and acetabulum without compromising the blood supply to the femoral head. Our results show that it can also be of great help in restoring malunited acetabular fractures.

Acetabulum↗
PubMed2004

Friction of ceramic and metal hip hemi-endoprostheses against cadaveric acetabula.

INTRODUCTION: Studies of hip arthroplasty have dealt mainly with total endoprosthesis, while tribology measurement values of hemi-endoprosthetic implants are rare. The small amount of experimental tribological data concerning materials of hemi-endoprosthetic implants in the form of pendulum trials, animal experiments, in vivo measurements on human hip joints and pin on disc studies report friction coefficients between 0.014 and 0.57; the friction coefficients measured in fresh human cadaver hip joints were determined between 0.001 and 0.08. MATERIALS AND METHODS: The HEPFlEx-hip simulator was constructed to test the friction coefficients of unipolar femur head hemi-endoprostheses made of metal or ceramic against fresh cadaveric acetabula. Its plane of movement is uniaxial with a flexion-extension movement of +30/-18 degrees . The force is produced pneumatically dynamic with amounts of 2.5 kN. Newborn calf serum serves as a lubricant. We mounted 20 fresh porcine acetabula and 10 fresh human cadaver acetabula in the HEPFlEx-hip simulator and compared the two unipolar femur head hemi-endoprostheses (metal vs. ceramic). RESULTS: The mean friction coefficients against porcine acetabula were micro=0.017-0.082 for ceramic and micro=0.020-0.101 for metal; against human cadaver acetabula micro=0.017-0.083 for ceramic and micro=0.019-0.118 for metal. The frictional coefficient deltas (metal-ceramic) values of all measurements were Deltamicro=0.004 for porcine acetabula and Deltamicro=0.001 for cadaver acetabula. Box-plots graphics document significantly lower frictional coefficients of the ceramics. CONCLUSIONS: The lower frictional coefficients of ceramic compared to metal against fresh cadaveric acetabula may have a clinical impact on the process of the protrusion of the corresponding femoral head through the acetabulum.

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PubMed2006

Press fit fixation of cementless cups: how much stability do we need indeed?

INTRODUCTION: Using screws for a better primary and secondary fixation has been discussed in the literature of the recent years, although the principle of press fit has been explained as the principle of a push-button. The authors wanted to compare their own results in patients using X-rays from the postoperative course to decide if it is really safer to use screws or not. MATERIALS AND METHODS: Two hundred and twenty one consecutive, not selected patients were treated with total hip arthroplasty using a cementless cup type Duraloc. They were followed up over a time of 5 years for radiological changes of the bony acetabulum around the cup ("acetabular zones" according to De Lee and Charnley). One hundred and ten cups were additionally fixed with one to three screws at the upper part in region C1, 101 cups were implanted without the use of screws. RESULTS: Periprosthetic changes visible on the radiographs (immediate postoperative gaps, subsequent sclerosis and radiolucent lines) were assessed according to the time of their appearance. A gap in zone C2 was seen more often immediately after operation within the group without screws (17.8% vs. 7.3%) and disappeared within the following 25 months. Within the group with screws significantly more often a gap was found in zone C1 and C3 compared to the group without screws (7.3% vs. 1.9%). In the group with screws a sclerosis of the bone in zone C1 developed in 32.7% mostly within the first 5 months. It was followed by a radiolucent line in zone C3 in 28.2% mainly within 5-25 months postoperatively and in zone C1 in 20.9% within 16 months. Significantly less seldom were these phenomena seen at the cups without screw fixation. There was no correlation between lateral or medial positioning and deviations from the ideal inclination to the bony changes around the cups. No signs of loosening occurred in either group. CONCLUSION: Less radiological changes around the cup if no screws were used and no disadvantages within this group led to the conclusion that an additional screw fixation in principle is not necessary in press-fit cups.

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PubMed2005

Arthroscopic diagnosis and treatment of an acetabular labrum bucket handle tear: a case report.

The acetabular labrum is a fibrocartilaginous structure attached to the acetabular rim. It increases the surface area of acetabulum and stabilizes joint. Acetabular labral tears are an important cause of intractable hip pain in adults. We report a cause of an acetabular bucket handle tear of the right hip, caused by femoroacetabular impingement that was diagnosed and treated successfully with hip arthroscopy.

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