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Blood flow changes to the femoral head after acetabular fracture or dislocation in the acute injury and perioperative periods.

OBJECTIVES: Acute blood flow to the femoral head has been postulated to be affected negatively by traumatic acetabular fracture or dislocation. To the best of our knowledge, a prospective study that has examined acute changes in blood flow to the femoral head with respect to the timing of reduction and the effect of open reduction and internal fixation after acetabular fracture or dislocations has not been performed. DESIGN AND SETTING: From June 1994 to February 1996, fifty-four consecutive patients with hip dislocations with or without fractures of the acetabulum were entered into this investigation. The patients were categorized into three groups: isolated dislocations, fractures or dislocations requiring open reduction and internal fixation, and isolated acetabular fractures without dislocation but requiring open reduction and internal fixation. Single-photon emission computed tomography (SPECT) scans were obtained after relocations and preoperatively and postoperatively after open reduction and internal fixation of displaced acetabular fractures. RESULTS: The median dislocation time for all patients flow was 4.00 hours (range 1 to 24 hours). SPECT scanning showed a low blood flow pattern in five (9.25 percent) patients. A low blood flow pattern was seen in patients with early and late relocation times. Open reduction and internal fixation was not statistically associated with an avascular pattern of blood flow. Forty-two (78 percent) of our patients were available for follow-up, with an average of 24.3 months and a minimum of one year. There was one false-positive, one false-negative, and thirty-eight true-negative scans. CONCLUSIONS: A global loss of scintillation in the femoral head as determined by SPECT scanning occurs in some patients with hip dislocations and fractures or dislocations of the acetabulum in the early injury period. Changes in blood flow occurred in patients with short (one hour) and long (twenty-four hours) dislocation times. However, the development of avascular necrosis could not be predicted by early SPECT scanning. Until further multicenter studies are performed, SPECT scanning cannot be recommended on an acute or routine basis to predict those patients who will develop avascular necrosis. Operative approaches for open reduction of the hip and internal fixation of acetabular fractures do not appear to affect blood flow to the femoral head. Although a golden time to relocation cannot be fully established from this study, early relocation is advised to decrease the potential risk of vascular spasm, scarring, and subsequent avascular necrosis.

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Biomechanical consequences of secondary congruence after both-column acetabular fracture.

OBJECTIVES: To create a both-column acetabular fracture model with secondary congruence and to determine the intraarticular loading characteristics present in simulated single-leg stance. HYPOTHESIS: The normal contact pressures on the weight-bearing portion of the acetabulum in simulated single-leg stance are different from those present in a both-column fracture model exhibiting secondary congruence. DESIGN: Cadaveric Biomechanical model. SETTING: Biomechanical testing laboratory. SPECIMENS: Nine fresh frozen cadaveric hemipelves. INTERVENTION: Both-column fracture model with secondary congruence of the acetabular articular surface with respect to the femoral head was created and tested using Materials Testing Machine (MTS Systems Corp., Minneapolis, MN) and Fuji pressure-sensitive film (Sensor Products, Inc., East Hanover, NJ). OUTCOME MEASUREMENTS: Testing data recorded and analyzed comparing the fractured and unfractured states. RESULTS: With respect to the intact specimen, the contact area, mean pressure, and peak pressure in the dome region all increased (p < 0.003) in the both-column model. The contact area in the anterior articular region decreased (p < 0.02) as did the mean pressure (p < 0.032). The posterior articular region demonstrated a trend toward decreased contact area and increased mean and peak pressures. Descriptively, the stress concentration shifted toward the fracture in all cases with the most anterior and most posterior articular regions having little contact in the fracture model. CONCLUSIONS: In the authors' both-column model of secondary congruence, the stress concentration during simulated single-leg stance was increased significantly in the dome of the acetabulum adjacent to the fracture line.

Acetabulum↗

Assessment of articular fragment displacement in acetabular fractures: a comparison of computerized tomography and plain radiographs.

OBJECTIVES: Quantitatively evaluate plain radiographs, relative to computed tomography (CT) scans, for assessment of articular fragment displacement (step and gap) in displaced acetabular fractures and in canine osteotomized acetabular specimens. DESIGN: Retrospective evaluation of a consecutive series of CT scans and plain radiographs of patients with displaced acetabular fractures and canine acetabulae osteotomized to represent acetabular fractures with displacement. SETTING: Level I trauma center. PATIENTS/PARTICIPANTS: Computed tomography scans and plain radiographic images of 62 consecutive patients with displaced acetabular fractures were reviewed; 20 patients met the inclusion criteria regarding location, fracture pattern, availability of plain radiographs and CT scans, and the position of the femoral head at the time of radiographic assessment. The hemipelvi of five adult mongrels underwent osteotomy of the acetabulum and similar radiographic evaluation. INTERVENTION: Three independent reviewers measured step and gap deformity on plain radiographs and CT scans utilizing a standardized measurement technique. MAIN OUTCOME MEASUREMENTS: Sensitivity and specificity of plain radiographs for detecting step and gap displacement (2 mm and 4 mm) relative to CT scans were determined. Intraclass correlation coefficient and intraobserver reliability was also calculated. For the canine specimens, sensitivities of each imaging method were determined relative to actual fragment displacement measurements. RESULTS: In the clinical images, when compared to CT, plain radiographs showed poor sensitivity at detecting step deformity (sensitivity = 25%). When analyzed by fracture type, plain radiographs were particularly poor at detecting step deformities in fractures involving a single column of the acetabulum (sensitivity = 0%). Excellent intraobserver and intraclass reliability existed among the three reviewers. Computed tomography scans were considerably more accurate in measuring step and gap displacement relative to actual measurements than plain radiographs in the canine specimens. CONCLUSIONS: 1) Plain radiographs showed poor sensitivity for the detection of step and gap deformities in patients with acetabular fractures and in osteotomized canine specimens, relative to CT scans; 2) differences between CT and plain radiographs in both specimen types were greatest with the most clinically relevant deformity-i.e., step; and 3) CT scans are essential and should continue to be used in conjunction with plain radiographs in the preoperative evaluation of displaced acetabular fractures and perhaps should be considered in the postoperative assessment of fracture reduction.

Acetabulum↗

Primary total hip arthroplasty with a Burch-Schneider antiprotrusion cage and autologous bone grafting for acetabular fractures in elderly patients.

OBJECTIVES: To investigate the clinical and functional outcome in an elderly population with acetabular fractures after low-energy trauma treated acutely with a total hip arthroplasty supported by a reinforcement ring (Burch-Schneider antiprotrusion cage) and autologous bone grafting of the acetabulum. SETTING: University hospital. DESIGN: Retrospective clinical study. PATIENTS: Ten patients (7 males) available for follow-up, with a mean age at the time of surgery of 73 years (range 57-87). The mean time to follow-up was 38 months (range 11-84). INTERVENTION: Primary total hip arthroplasty supported by a reinforcement ring (Burch-Schneider Antiprotrusion Cage) and autologous bone grafting of the acetabulum. MAIN OUTCOME MEASUREMENTS: Surgical data, complications, radiographic assessment, pain, walking ability, Harris Hip Score, activities of daily living, health-related quality of life according to EuroQol (EQ-5D). RESULTS: The mean operating time was 159 minutes (range 125-185). The mean intraoperative blood loss was 1100 mL (700-1600 mL). The reinforcement ring was stable and there were no signs of loosening of the acetabular component or stem in any of the patients. The bone graft was completely incorporated in all cases. Four patients presented slight (Brooker I-II) heterotopic bone formation. All patients were still independent walkers at follow-up but with a slightly increased need for walking aids. The mean Harris Hip Score was 85 (range 69-99). The mean EQ-5D(index) score was 0.62. CONCLUSION: Primary total hip replacement with a reinforcement ring and bone grafting of the socket seems to be a promising treatment alternative in displaced acetabular fractures in elderly patients with osteoporotic bone, except in those with an increased risk of dislocation.

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Computerized axial tomography of pelvic ring fractures.

The radiographs of all patients admitted to the Naval Hospital, Oakland with the diagnosis of pelvic trauma from 1981 through 1985 were reviewed. Thirty-one patients sustained single or double vertical ring fractures. Fifteen of these patients underwent both plain radiography and Computerized Axial Tomographic (CAT) scans in the evaluation of their pelvic injuries. The CAT scans of these pelvic injuries aided in detecting occult sacroiliac disruptions, determining the extent of posterior ring comminution, evaluating possible extension of the pelvic fractures into the acetabulum, assessing pelvic ring stability, and demonstrating soft-tissue injuries within the pelvis. Six pelvic injuries were diagnosed as single vertical breaks in the pelvic ring and nine were diagnosed as double vertical breaks in the pelvic ring by plain radiographs. CAT scanning demonstrated occult posterior ring disruptions in four patients which led to the reclassification of their injuries to double vertical fractures. CAT scanning also demonstrated significant degrees of sacral comminution in five patients which altered surgical treatment plans in all five patients. Two fractures were classified as unstable based on marked sacral comminution demonstrated on CAT scan. Extension of the pelvic ring fractures into the acetabulum was suggested on plain radiographs in three patients and was excluded by review of the CAT scans in these patients. Significant intrapelvic hematomas were demonstrated in three patients and urine extravasation into the hip joint from a bladder laceration was seen in one patient with the CAT scan.(ABSTRACT TRUNCATED AT 250 WORDS)

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Morphologic characteristics of acetabular dysplasia in proximal femoral focal deficiency.

A retrospective radiographic analysis of the acetabulum of 13 patients (14 hips) with proximal femoral focal deficiency (PFFD), clinically classified into Gillespie and Torode type 1, was performed to better understand its morphologic features at maturity. The version of the proximal part of the acetabulum was determined quantitatively and qualitatively. All 14 hips showed residual or borderline acetabular dysplasia with a mean lateral centre-edge angle of -1.5degrees and an acetabular index of 30degrees. The acetabular dome was retroverted in all hips and averaged -24degrees. Acetabular deficiency compared with the opposite side, while not present with respect to the anterior wall, averaged 12% with respect to the posterior wall. Dysplasia associated with type 1 PFFD is therefore fundamentally different from that seen in developmental residual hip dysplasia. Clinically, despite radiographic evidence of dysplasia, 57% were without clinical manifestations of hip pathology. This may be due to a number of factors including age of last radiograph, severity of dysplasia, and the decreased functional demand placed on the hip in some individuals with associated malformations. For the symptomatic hip, the posterior insufficiency and relative retroversion of the acetabular dome should be taken into consideration in planning reorientation procedures. This can help to prevent problems of persistent subluxation or acetabulo-femoral impingement following reconstruction.

Acetabulum↗

Women awaiting knee replacement have reduced function and growth hormone.

Women experience greater functional impairment and occurrence of osteoarthritis than men. We hypothesized that lower levels of serum insulin-like growth factor-I may contribute to gender differences in physical impairments. A cross-sectional comparison (n = 139) was done on candidates having total knee arthroplasty and healthy controls subjects of similar age (range, 55-75 years). Physical function, perceived function, and serum insulin-like growth factor levels were compared across group and gender using analysis of variance. Insulin-like growth factor-I values were markedly reduced in women overall and women having surgery had significantly reduced levels despite lean body mass correction. Values consistent with clinical hormone deficiency were observed in 21% of women and only 4% of men having arthroplasty. Physical function was markedly reduced in women, at times functioning only 33% when compared with healthy women, whereas men's limitations were not as profound. The current findings indicate that physical function is more impaired and serum insulin-like growth factor-I is markedly reduced in women awaiting arthroplasty than their male counterparts. The gender differences observed biochemically and with functional performance indicate that the pathophysiology of end stage osteoarthritis may differ between men and women.

Activities of Daily Living↗

Acetabular labral tears rarely occur in the absence of bony abnormalities.

We evaluated the percentage of patients with acetabular labral tears who have a structural hip abnormality detectable by conventional radiography. Records from our institution from 1996 through 2002 were reviewed to identify all patients with labral tears. Patients were excluded who had classic hip dysplasia, advanced osteoarthritis, or a history of pelvic or femoral osteotomy. The hip radiographs were evaluated for abnormalities of Tönnis angle, center-edge angle of Wiberg, acetabular version, femoral neck-shaft angle, congruency between the femoral head and acetabulum, anterior femoral head-neck offset, and presence of femoral head osteophytes. Twenty-seven of the 31 patients (87%) had at least one abnormal finding and 35% had more than one abnormality. Ten patients had a retroverted acetabulum, 16 had coxa valga, 11 had an abnormal femoral head-neck offset, and 14 had osteophytes on the femoral head. Four of 31 patients (13%) had no identifiable structural abnormalities. To our knowledge, this is the first study to document that the majority of patients with labral tears have a structural hip abnormality detectable with conventional radiographs. Familiarity with these structural abnormalities is important for early detection and accurate diagnosis, and may impact optimal treatment planning and prognosis.

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An incomplete periacetabular osteotomy for treatment of neuromuscular hip dysplasia.

Standard innominate osteotomies that are recommended for treatment of the typical form of developmental dysplasia of the hip are not recommended for dysplasia associated with neuromuscular disorders. A periacetabular osteotomy that permitted accurate correction of the posterolateral acetabular deficiency was done on 40 patients (50 hips). The purpose of this study was to present the surgical technique, to evaluate whether it can improve acetablular dysplasia, and to provide stable hips. The patients had a mean age of 9.5 years at the time of surgery. The medial cortex of the ilium was left intact, whereas the supraacetabular and retroacetabular cancellous bone, and posterolateral cortical bone were cut. The posterior cut extended down to the triradiate cartilage, or through its former site, respectively. Forty-one hips were evaluated at a mean followup of 5.3 years (range, 2-11.7 years) after surgery. The mean acetabular index improved from 32 degrees preoperatively to 12 degrees at followup. The mean migration percentage improved from 77% to 13%. A redislocation or unstable hip occurred in two patients. According to caregivers, surgery improved personal care, positioning, and comfort. This osteotomy decreases the radius of the elongated acetabulum, provides coverage by articular cartilage particularly at the posterolateral aspect of the acetabulum, and preserves the entire medial wall of the ilium.

Acetabulum↗

The potential for bone loss in acetabular structures following THA.

Attempts to preserve periacetabular bone stock following total hip replacement have largely ignored the potential for stress shielding in the acetabulum. We sought to quantify the change in stress distribution in acetabular bone with components of varying material stiffness by developing a high-resolution 3-D finite element model from CT scans of a young female donor. Periprosthetic bone stresses and strains on the left pelvis were compared with hemispherical cups of various material properties and with a horseshoe shaped polymeric design described in the recent literature. We observed unphysiologic periacetabular bone stress and strain fields for all designs tested. For hemispherical components, reduction of the acetabular shell material modulus caused modest changes in bone stress compared to the changes in implant geometry. The horseshoe shaped cup more effectively loaded the acetabular structures than the hemispherical design. Our results suggest stress and strain fields in pelvic structures after introduction of hemispherical acetabular components predict inevitable bone adaptation that can not be resolved by changes in implant material properties alone. Radical changes in implant design may be necessary for long-term maintenance of supporting structures in the reconstructed acetabulum.

Acetabulum↗

False profile radiography for the evaluation of Legg-Calvé-Perthes disease.

False profile radiography (FPR), as proposed by Lequesne and de Sèze, depicts the pathology on the anterolateral acetabular wall and femoral head. A study was conducted to find out the differences between normal anteroposterior radiography and FPR. Twenty-seven patients with Legg-Calvé-Perthes disease who had not been operated on previously and 50 recruits without any pathology were studied for the acetabulum-head index of Heyman-Herndon (HHI) and center-edge angles (CEs) in antero-posterior radiographs and VCA angles in FPR. The VCA angle is most useful to detect anterolateral coverage of the femoral head in lateral pillar C hips. FPR is an easy, reliable and cheap technique to evaluate the anterolateral parts of the femoral head, and the acetabulum.

Acetabulum↗

Does Dega osteotomy increase acetabular volume in developmental dysplasia of the hip?

Whether acetabular volume increases or decreases after acetabular Dega osteotomy is not known. The purpose of this study is to determine the effect of Dega osteotomy on the volume of the acetabulum in patients with developmental dysplasia of the hip. Nine hips of seven patients with developmental dysplasia of the hip that have undergone Dega osteotomy were included in the study. The acetabular index, acetabular depth, and acetabular volume of each hip were calculated before and after surgery. Magnetic resonance imaging was used for the measurement of the acetabular volume. The difference between the preoperative and postoperative values of acetabular index, acetabular depth, and acetabular volume was statistically significant. We conclude that Dega acetabular osteotomy increases the volume of the acetabulum.

Acetabulum↗

Femoroacetabular impingement: an overlooked cause of hip pain.

Femoroacetabular impingement is a cause of hip pain arising from abnormal contact between the proximal femur and the acetabulum during terminal hip motion. This is caused by a structural abnormality at the femoral head/neck junction or the acetabulum. The problem usually presents in young adults and can often go undiagnosed for years. Failure to identify and properly restore the biomechanics has been hypothesized to lead to the early onset of hip osteoarthritis; thus, early recognition is important. In this case study, we report on a 31-yr-old patient with many years of bilateral hip pain who underwent successful treatment of bilateral femoroacetabular impingement.

Acetabulum↗

Acetabular notch.

Ultrasound images of dysplastic and/or unstable hips often display an indentation or notch at the superolateral part of the acetabulum where the iliac wing joins the acetabular roof. We reviewed the ultrasound and subsequent radiographic examinations of 295 babies examined in our hip screening clinic. Of the hips with a notch demonstrable at the first ultrasound, 97% had a persistent notch at the second ultrasound and in 79% the notch was apparent on the 3-month radiograph. When the notch persists, we believe that it represents damage to the lateral acetabular ring epiphysis and delayed maturation of the lateral acetabulum.

Acetabulum↗

Development of hip dysplasia in puberty due to delayed ossification of femoral nucleus, growth plate and triradiate cartilage.

Besides hip dysplasia diagnosed after birth, there are dysplasias that do not develop until puberty, causing subluxation of the femoral head to occur late in the skeletal growth period. These dysplasias have various causes. In the two siblings described in this study, the boy showed a conspicuous delay in the appearance of the femoral nuclei and the fusion of the triradiate cartilages. The fusion occurred at 16 years of age in the boy and at 13-14 years in the girl. This was preceded by conspicuous structural changes, especially in the posterior triradiate cartilage and acetabular roof but also affecting the lateral growth plate of the femoral neck, which was horizontal over two-thirds of the diameter. We know from animal studies that the growth of the triradiate cartilage increases the diameter of the acetabulum but not the depth. The acetabulum is deepened by pressure from the femoral head. As a result of coxa valga and a prolonged period of acetabular expansion, combined with abnormalities of the superior acetabular rim, the femoral heads in these children finally subluxate. Whenever development of the femoral ossific nucleus is delayed during the first year of life, radiographic follow-ups should be instituted at 8 years of age.

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Acetabular augmentation induced by extracorporeal shock waves in rabbits.

We conducted this animal study to demonstrate whether exposing the acetabulum in immature rabbits to extracorporeal shock waves induces bone formation in the acetabulum. Five thousand shock waves of 100 MPa each were directed, from outside, at the acetabular roof of eight immature rabbits. At each of two time points (4 and 8 weeks) after treatment, the pelvises of four rabbits were removed and evaluated morphologically. Woven bone formation was observed on the lateral margin of the acetabular roof at 4 weeks after treatment, and the breadth of the acetabular roof in the coronal plane was significantly increased. Eight weeks after treatment, the woven bone disappeared; the breadth of the acetabular roof, however, was significantly increased. These findings demonstrated that extracorporeal shock waves induced acetabular augmentation in rabbits. We conclude that extracorporeal shock waves, perhaps, could be applied clinically for the treatment of acetabular dysplasia.

Acetabulum↗

Capsular change following Chiari innominate osteotomy.

The case of a child treated at the age of 23 months for congenital dislocation of the hip by Chiari innominate osteotomy is presented. When additional surgery was required at the age of 4 years, exploration was made of the acetabulum which had been formed 2 years earlier by the Chiari procedure. Histologic evaluation revealed that capsular changes in the tissue interposed between the femoral head and the new acetabulum had produced well-vascularized, connective tissue with abundant collagen. The nature of the change in this tissue helps to explain why Chiari medial displacement innominate osteotomy may be successful.

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Acetabular changes in an experimental model of developmental dysplasia of the hip (DDH).

We wished to correlate the morphological acetabular changes in developmental dysplasia of the hip (DDH) with changes at the tissue level. A secondary aim was to develop a way of measuring the dysplastic acetabulum. We studied the changes in rabbit acetabula after maintaining knee extension, measuring the major diameter from the acetabular notch to the farthest opposite point on the acetabular margin. The minor diameter was at right angles to this. The dysplastic acetabula showed elongation along the major diameter compared to control hips. Microscopic sections were made along major and minor diameters. The posterosuperior lip of the dysplastic acetabulum showed an early eversion of the acetabular cartilage. Growth of the articular cartilage in this new direction accounted for the acetabular elongation. As well as providing insight into the manner of acetabular shape change, the findings suggest the nature of remodeling required before normal acetabular growth can resume during treatment.

Acetabulum↗