By using the reverse engineering (RE) technology, the mesh surface model of acetabulum was reconstructed by triangulation. Based on this kind of model, the local morphological analysis (LMA) and global morphological analysis (GMA) could be processed. The fitting minimal quadric surface method was applied to calculate the curvature of any point on the acetabulum bony surface, the local morphological character of its surface could be acquired, and its global surface character could be determined by GMA. The results showed that the acetabulum bony surface is elliptical surface, and its three eigenvalues (lambda1, lambda2, lambda3) relations on the three axes (x, y, z) are as follows: lambda1 is short than lambda2 and lambda3, lambda2 is close to lambda3.
Acetabulum ; anatomy & histology ; Humans ; Models, Anatomic

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

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 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

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

The research on the morphology features of the acetabulum bone joint surface area would be helpful to establishing the acetabulum 3D model for the purpose of the biomechanical analysis of hip joint, and therefore might have its important clinical significance. However, in former studies, the acetabulum was simply considered as a semi sphere. In this study, based on the acetabulum 3D-point data acquired by the 3D laser surface scanner and the reverse engineering technology together with the optimal fit algorithm, two kinds of best-fit model were achieved by a sphere surface and a rotating elliptical surface respectively approaching to the acetabulum bone joint surface. Both fitting errors were then compared and analyzed. The results showed that the fitting error of the rotating elliptical surface was significantly less than that of the sphere surface (P < 0.001). The average radius of fitting sphere was 24.37 +/- 2.22 mm and the average long axis of fitting rotating elliptical surface was 26.02 +/- 2.76 mm while its short axis was 24.17 +/- 2.16 mm. These findings would be helpful to our new recognition of the acetabulum since they were results of the first quantitative analyses for the acetabulum bone surface and also might serve as an important reference base in its further studies and application.
Acetabulum ; anatomy & histology ; Adult ; Algorithms ; Humans ; Imaging, Three-Dimensional ; Models, Anatomic

I examined the sphericity and the congruity of the femoral head and the acetabulum in 172 Korean fetuses and in 655 Korean adults. I found that Korean fetal acetabuli and femoral heads are spherical and that the proportion of the head contained in the acetabulum remains constant and congruous throughout the fetal life. Adult actabuli and femoral heads are also spherical in both gender and are there are no visible changes in the shape of the acetabuli and the femoral heads with respect to age. No evidence was found that the congruity of the hip joint is a cause of osteoarthritis of the hip joint. Clinical Relevance: Stable hip joints at the time of birth provide an explantation for the low incidence of congenital dislocation of the hip joint in Koreans. The spherical femoral head and acetabulum (congruous hip joint) seem to be a contributing factor to the low incidence of primary osteoarthritis of the hip in Koreans.
Acetabulum/*anatomy and histology/embryology ; Adult ; Female ; Femur Head/*anatomy and histology/embryology ; Fetus/anatomy and histology ; *Hip Joint/pathology ; Human ; Incidence ; Korea/epidemiology ; Male ; Osteoarthritis, Hip/epidemiology/*etiology/pathology

I examined the sphericity and the congruity of the femoral head and the acetabulum in 172 Korean fetuses and in 655 Korean adults. I found that Korean fetal acetabuli and femoral heads are spherical and that the proportion of the head contained in the acetabulum remains constant and congruous throughout the fetal life. Adult actabuli and femoral heads are also spherical in both gender and are there are no visible changes in the shape of the acetabuli and the femoral heads with respect to age. No evidence was found that the congruity of the hip joint is a cause of osteoarthritis of the hip joint. Clinical Relevance: Stable hip joints at the time of birth provide an explantation for the low incidence of congenital dislocation of the hip joint in Koreans. The spherical femoral head and acetabulum (congruous hip joint) seem to be a contributing factor to the low incidence of primary osteoarthritis of the hip in Koreans.
Acetabulum/*anatomy and histology/embryology ; Adult ; Female ; Femur Head/*anatomy and histology/embryology ; Fetus/anatomy and histology ; *Hip Joint/pathology ; Human ; Incidence ; Korea/epidemiology ; Male ; Osteoarthritis, Hip/epidemiology/*etiology/pathology

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

The main reason of invalidation of prosthetic hip joint is the prostheses flexibility and shift, dislocation and disjunction. Promoting the long time stability of the prostheses is the key of improving the long term hip joint replacement effect. Former research work was focused on the upper segment of femur, and assumed the acetabulum cup to be a spheric concave, and the external form of acetabulum prostheses was basically semi spheric. This paper presents a method of acquiring the point data on the surface of the hip bone using the reverse engineering technology. By analyzing the acetabulum surface fitting error we use rotating elliptical surface to fit the acetabulum surface, together with the optimal technique to build up the CAD model of acetabulum surface. We compare the fitting error between the sphere fitting and rotating elliptical surface fitting and get the result that the rotating elliptical surface fitting error is smaller than the sphere fitting error, and the rotating elliptical surface can describe the shape of the acetabulum better.
Acetabulum ; anatomy & histology ; Anthropometry ; Arthroplasty, Replacement, Hip ; Computer Simulation ; Computer-Aided Design ; Hip Joint ; anatomy & histology ; Hip Prosthesis ; Humans ; Models, Anatomic ; Prosthesis Design