The orientation of the acetabular cup in hip joint anteroposterior radiograph is a key factor in evaluating the postoperative outcomes of total hip arthroplasty (THA). Currently, measurement of the acetabular cup anteversion angle primarily relies on manual drawing of auxiliary lines by orthopedic surgeons and calculations using scientific calculators. This study proposes an automated computer-aided measurement method for the acetabular cup anteversion angle based on hip joint anteroposterior radiograph. The proposed method segments hip prosthesis images using an improved Otsu algorithm, identifies feature points at the acetabular cup opening by combining circle-fitting theory and the cup's geometric characteristics, and fits an ellipse to the cup opening to calculate the anteversion angle. A total of 104 hip joint anteroposterior radiographs, including 71 right-sided and 81 left-sided prostheses, were analyzed. Two orthopedic surgeons independently measured the postoperative anteversion angles, and the results were compared with computer-generated measurements for correlation analysis. Spearman and Pearson correlation analyses demonstrated significant correlations between the proposed method and manual measurements for both the right group ( r = 0.795, P < 0.01) and the left group ( r = 0.859, P < 0.01). This method provides a reliable reference for orthopedic surgeons to assess postoperative prognosis.
Humans ; Acetabulum/anatomy & histology* ; Arthroplasty, Replacement, Hip/methods* ; Algorithms ; Hip Prosthesis ; Hip Joint/diagnostic imaging* ; Radiography ; Image Processing, Computer-Assisted/methods*

The basic stress pathway above the acetabular dome is important for the maintenance of implant stability in acetabular reconstruction of total hip arthroplasty (THA). The purpose of this study was to describe the basic stress pathway to provide evidence for clinical acetabular reconstruction guidance of THA. A subject-specific finite element (FE) model was developed from CT data to generate 3 normal hip models and a convergence study was conducted to determine the number of pelvic trabecular bone material properties using 5 material assignment plans. In addition, in the range of 0 to 20 mm above the acetabular dome, the models were sectioned and the stress pathway was defined as two parts, i.e., 3D, trabecular bone stress distribution and quantified cortical bone stress level. The results showed that using 100 materials to define the material property of pelvic trabecular bone could assure both the accuracy and efficiency of the FE model. Under the same body weight condition, the 3D trabecular bone stress distributions above the acetabular dome were consistent, and especially the quantified cortical bone stress levels were all above 20 MPa and showed no statistically significant difference (P>0.05). Therefore, defining the basic stress pathway above the acetabular dome under certain body weight condition contributes to design accurate preoperative plan for acetabular reconstruction, thus helping restore the normal hip biomechanics and preserve the stability of the implants.
Acetabulum ; anatomy & histology ; Arthroplasty, Replacement, Hip ; Biomechanical Phenomena ; Finite Element Analysis ; Hip Prosthesis ; Humans ; Imaging, Three-Dimensional ; Stress, Mechanical ; Tomography, X-Ray Computed

OBJECTIVETo solve the problem of screw penetrating the joint surface easily by determining the angle of inclination and the mean longth screw plated on the posterior column.

METHODSTen specimens of adult male cadavers, aged 20 to 74 years old, averaged 54.5 years old, were collected. After removal of the bilateral femurs from the hip joints, and sawing through the sacral and pubic symphysis in the median sagittal plane, 20 semi pelvic specimens were used for this study when the osseous abnormalities were excluded. The specimens were air dried naturelly after the soft tissue attaching to the pelvis had been eliminated. The margin of superior acetabular and inferior acetabular were determined, and the serial cross-sections of the acetabular posterior column were made. The width of posterior column,the width of acetabulum,the width ratio of acetabulum to posterior column, the angle of inclination and the mean length of screw on all entry points were measured. Defined the level parallel to 1/2 section of superior acetabulum was cross-section B; 1/2 section of acetabulum was C; 1/2 section of inferior acettabulum was D. At the different levels, defined the entry point on the outer edge of posterior column of the acetabulum or the trailing edge of acetabulum was B0, C0 or D0; lateral 1/2 of posterior column of the acetabulum was B1, C1 or D1; 1/2 of posterior column of the acetabulum was B2, C2 or D2; medial 1/2 of posterior column of the acetabulum was B3, C3 or D3; the inner edge of posterior column of the acetabulum was B4,C4 or D4.

RESULTSOn cross-section B, the angle of inclination and the mean length of screw at B0 was 41 degrees and 44.0 mm; at B1 was 66 degrees and 42.2 mm; at B2 was 91 degrees and 59.5 mm; at B3 was 107 degrees and 64.0 mm; the maximum angle and the mean length at point B4 was 123 degrees and 65.5 mm; the minimum angle and the mean length at point B4 was 109 degrees and 59.0 mm. On cross-section C,the angle and the mean length at point CO was 39 degrees and 39.0 mm; at C1 was 57 degrees and 36.0 mm; at C2 was 74 degrees and 36.0 mm;at C3 was 90 degrees and 36.0 mm; at C4 was 106 degrees and 76.0 mm. On cross-section D,the angle and the mean length at DO was 42 degrees and 35.5 mm; at D1 was 61 degrees and 33.0 mm; at D2 was 81 degrees and 32.0 mm; at D3 was 100 degrees and 31.0 mm; at D4 was 120 degrees and 74.0 mm.

CONCLUSIONWhen using the fixation technique of acetabular posterior column plate, the angles of screw-posterior column are 40 degrees to 60 degrees, 60 degrees to 75 degrees, 75 degrees to 90 degrees and 90 degrees to the angle of parallel to the square area respectively on the region of outer 1/4,outer-middle 1/4,inner-middle 1/4 and inner 1/4 of the acetabulum region, and the screw length is 30 mm.

Acetabulum ; anatomy & histology ; injuries ; surgery ; Adult ; Aged ; Bone Plates ; Bone Screws ; Fracture Fixation, Internal ; instrumentation ; Fractures, Bone ; surgery ; Humans ; Internal Fixators ; Male ; Middle Aged ; Young Adult

Various musculoskeletal injuries are well known complications of epilepsy either because of direct trauma or because of unbalanced forceful muscle contraction. We report a case of non-traumatic bilateral central acetabular fracture dislocation due to seizure activity induced by neurocysticercosis of the brain, which was managed conservatively and obtained reasonable good outcome. This case highlights the importance of proper evaluation in young non-osteoporotic patients who have experienced an epileptic attack without any previous history. It is also imperative to mention that these patients should be thoroughly examined neurologically to find out the exact etiology and should be treated accordingly to prevent future seizure activity.
Acetabulum ; anatomy & histology ; injuries ; Fractures, Bone ; complications ; etiology ; Joint Dislocations ; complications ; etiology ; Seizures ; complications

OBJECTIVETo explore morphological character and clinical significance of superior-posterior acetabular wall by anatomically measuring and quantitatively analyzing thickness of posterior acetabular wall, then provide a theoretical reference for clinical treatment of acetabular fracture.

METHODSFifteen adult formalin-preserved cadaveric pelvises (8 males and 7 females) were used for this investigation. Excess soft tissue was removed and the whole acetabular posterior walls were marked with "angle" sector method and the thickness was measured with caliper in different levels of the different split points. The measurement results were validated and analyzed statistically.

RESULTSAt 5 mm away from acetabular rim, the average thickness of superior-posterior acetablar wall fluctuated between (6.47±0.61) mm and (7.43±0.71) mm; the average thickness of inferior-posterior acetabuluar wall fluctuated between (5.62±0.51) mm and (6.33±0.61) mm; the average thickness of acetabular roof fluctuated between (7.71±0.74) mm and (8.27±0.99) mm. There was no statistical difference between average thickness of superior-posterior wall of acetabulum and inferior-posterior wall of acetabulum (P>0.05), but the average thickness of acetabular roof was significantly larger than superior-posterior acetabular wall (P<0.05). At 10 mm away from the acetabular rim, the average thickness of superior-posterior acetabular wall fluctuated between (8.81±0.67) mm and (13.35±0.89)mm; the average thickness of inferior-posterior acetabular wall fluctuated between (7.02±0.63) mm and (7.66±0.69) mm; the average thickness of acetabular roof fluctuated between (14.46±0.97) mm and (17.05±1.35) mm. Comparatively, the average thickness of superior-posterior acetabular wall was significantly larger than inferior-posterior wall of acetabulum (P<0.05), and the average thickness of acetabular roof was significantly larger than superior-posterior acetabular wall (P<0.01). At 15 mm away from the acetabular rim, the average thickness of superior-posterior acetabular wall fluctuated between (12.08±0.78) mm and (19.84±1.03) mm; the average thickness of inferior-posterior acetabular wall fluctuated between (10.17±0.76) mm and (11.12± 0.77) mm; the average thickness of acetabular roof fluctuated between (23.23±1.12) mm and (26.01±1.53) mm. Comparatively, the average thickness of superior-posterior wall of acetabulum was significantly larger than inferior-posterior acetabular wall (P<0.01), and the average thickness of acetabular roof was significantly larger than superior-posterior acetabular wall (P< 0.01).

CONCLUSIONThe thickness of entire acetabular posterior edge revealed an increasing tendency from inferior-posterior wall to the superior-posterior wall to acetabular roof. And this trend became more obvious with increasing distance away from acetabular rim. Therefore, the superior-posterior acetabular wall could not only maintain the stability of hip joint but also bear loading.

Acetabulum ; anatomy & histology ; injuries ; surgery ; Female ; Humans ; Male

OBJECTIVETo study the influences of head/neck ratio and femoral antetorsion on the safe-zone of operative acetabular orientations, which meets the criteria for desired range of motion (ROM) for activities of daily living in total hip arthroplasty (THA).

METHODSA three-dimensional generic, parametric and kinematic simulation module of THA was developed to analyze the cup safe-zone and the optimum combination of cup and neck antetorsion. A ROM of flexion > or =120 degree internal rotation > or = 45 degree at 90 degree flexion, extension > or = 30 degree and external rotation > or =40 degree was defined as the criteria for desired ROM for activities of daily living. The cup safe-zone was defined as the area that fulfills all the criteria of desired ROM before the neck impinged on the liner of the cup. For a fixed stem-neck (CCD)-angle of 130 degree theoretical safe-zones fulfilling the desired ROM were investigated at different general head-neck ratios (GR=2, 2.17, 2.37, 2.61 and 2.92) and femoral anteversions (FA equal to 0 degree,10 degree,20 degree and 30 degree).

RESULTSLarge GRs greatly increased the size of safe-zones and when the CCD-angle was 130 degree, a GR larger than 2.37 could further increase the size of safe-zones. There was a complex interplay between the orientation angles of the femoral and acetabular components. When the CCD-angle was 130 degree the optimum relationship between operative acetabular anteversion (OA) and femoral antetorsion (FA) could be estimated by the formula: OA equal to -0.80 multiply FA+47.06, and the minimum allowable operative acetabular inclination (OI(min)) would be more than 210.5 multiply GR(-2.255).

CONCLUSIONSLarge GRs greatly increase the size of safe-zones and it is recommended that the GR be more than 2.37 so as to extend the acceptable range of error that surgeons cannot avoid completely during operation. As to the optimum operative acetabular inclination (OI), surgeons need to make a decision combining with other factors, including stress distribution, soft tissue and cup wear conditions, as well as patients'individual situations and demands. The data obtained from this study and the module of THA can be used to assist surgeons to choose and implant appropriate implants.

Acetabulum ; anatomy & histology ; Arthroplasty, Replacement, Hip ; methods ; Computer Simulation ; Femur Head ; anatomy & histology ; physiology ; Femur Neck ; anatomy & histology ; physiology ; Humans ; Range of Motion, Articular

OBJECTIVESTo study the best entry points, direction and length of screw in acetabular posterior column plate technique, and to prevent the serious complications of screw penetrating the joint surface.

METHODSFebruary to July 2008 20 male cadaveric adult semi-pelvic specimen were taken.Serial cross-sections of the acetabular posterior column were determined and made. The safe angle of screw entry and the length on all entry points of each cross-section were measured. And put all data into software SPSS 10.0 for statistics process.

RESULTSOn margin of acetabulum, lateral-middle 1/4 point, midpoint, medial-middle 1/4 point and medial margin of posterior column of each cross-section, safe entry angle of inclination was 39 degrees , 57 degrees , 74 degrees , 90 degrees and 106 degrees respectively, the length of the screw was 39, 57, 74, 90 and 106 mm respectively.

CONCLUSIONOn lateral 1/4 region, lateral-middle 1/4 region, medial-middle 1/4 region and medial 1/4 region, screw posterior column angle is 40 degrees to 60 degrees , 60 degrees to 75 degrees , 75 degrees to 90 degrees , 90 degrees to parallel to the quadrilateral plate, and the length of the screw is 30 mm.

Acetabulum ; anatomy & histology ; surgery ; Adult ; Bone Plates ; Bone Screws ; Cadaver ; Fracture Fixation, Internal ; methods ; Humans ; Male

OBJECTIVETo evaluate the safe zones of screw fixations of Jumbo cup and reinforcement rings in acetabular revision surgery.

METHODSFrom December 2006 to January 2008, 11 fresh frozen human cadaver pelvises were prepared by removing all soft tissues except the medial neurovascular structures, each specimen was held in supine position with clamps. The anteroposterior radiographs were taken after the Jumbo cups or reinforcement rings were fixed in places. Left sides of acetabulum were used to create the models to evaluate the safe zones of the high hip center and Jumbo cups. Right sides were used to evaluate the safe zones of 3 different designs of acetabular reinforcement rings (Müller, Ganz, Burch-Schneider cage).

RESULTSJumbo cups: screws in the superoanterior and anteroinferior quadrants could cause neurovascular injuries. High hip center: neurovascular injuries could be expected in all quadrants except the inferoposterior and posterior half of superoposterior quadrant. Müller ring: screws placed in the intra-acetabular and extra-acetabular areas of the superoanterior quadrant could cause neurovascular injuries. Ganz ring:the screws placed in superoanterior quadrant and apex area were dangerous. The insults were confirmed in all of the specimens. Burch-Schneider cage: the medial nervous and vasculature structures were injured in all of the specimens if the screws placed in the superoanterior (intra-acetabular and extra-acetabular) quadrant. Screws for ischial fixation could cause sciatic nerve injury.

CONCLUSIONSIn revision acetabular surgery, the superoanterior quadrant, the anterior half of the superoposterior quadrant and the implant's central area are unsafe for screw fixation, especially when the exposed thread is longer than 15 mm.

Acetabulum ; anatomy & histology ; surgery ; Arthroplasty, Replacement, Hip ; Bone Screws ; Female ; Hip Prosthesis ; Humans ; In Vitro Techniques ; Male

OBJECTIVETo study the best entry points, direction and length of screw in acetabular anterior column plate technique, and to prevent the serious complications of screw penetrating the joint surface.

METHODSTwenty male cadaveric adult semi-pelvic specimen were taken, and the distance from anterior acetabular margin, posterior acetabular margin to anterior inferior iliac spine, iliopubic eminence and pubic tubercle were measured respectively. Determine and make serial cross-sections of the acetabular anterior column, measure the safe angle of screw entry on all entry points of each cross-section, and put all data into software SPSS 10.0 for statistics process.

RESULTSThe distance from anterior acetabular margin to anterior inferior iliac spine, iliopubic eminence and pubic tubercle was (25.4 +/- 1.4) mm, (11.8 +/- 0.7) mm and (37.4 +/- 1.5) mm respectively, the distance from posterior acetabular margin to anterior inferior iliac spine, iliopubic eminence was (15.5 +/- 0.9) mm and (29.1 +/- 1.6) mm respectively. On each cross-section, the maximum of the safe entry angle of inclination in 0.5 cm, 1.0 cm and 1.5 cm entry point lateral to the linea terminalis of pelvis was (8.2 +/- 2.2) degrees , (14.9 +/- 3.4) degrees and (26.1 +/- 4.5) degrees respectively.

CONCLUSIONSWhen plate for internal fixation on acetabular region of anterior column is used, there are three ways to avoid screw penetrating the joint surface. The first way is using short screw in any direction; the second way is using long screw close to the linea terminalis of pelvis, the direction of the screw is parallel to the quadrilateral plate; the third way is using different entry angle and length according to different entry point.

Acetabulum ; anatomy & histology ; surgery ; Adult ; Bone Plates ; Bone Screws ; Cadaver ; Fracture Fixation, Internal ; instrumentation ; methods ; Humans ; Male ; Models, Anatomic

OBJECTIVETo set up three-dimensional reconstruction of acetabulum bone structure from CT scanned image in computer with software of CAD and study quantitatively the morphologic features of the acetabulum.

METHODSThrough the process of CT scanning, and edge recording of the CT image, we made use of CAD software and Unigraphics software to reconstruct the 40 normal acetabulum bones for the radius of acetabulum (R), minimum thickness of medial wall of acetabulum (L), depth of Harris fossa (D) and maximum opening rim width in cross-sectional plane (W).

RESULTSThe average R was 30.48 +/- 2.05 mm. The average L was 2.35 +/- 1.13 mm. The average D was 5.71 +/- 1.21 mm. The average W was 63.06 +/- 2.05 mm. There was a linear relationship between the R and the W, but no correlation between the R, the L and the D.

CONCLUSIONSThere was a significance linear relationship between the R and the W in normal adult acetabulum. However no correlation between the R, the L and the D.

Acetabulum ; anatomy & histology ; diagnostic imaging ; Adult ; Humans ; Imaging, Three-Dimensional ; methods ; Pelvimetry ; methods ; Tomography, X-Ray Computed