Acetabular Fracture Etiology / Epidemiology / Natural History
Acetabular Fracture Anatomy
Acetabular Fracture Clinical Evaluation
Acetabular Fracture Xray / Diagnositc Tests
Acetabular Fracture Classification / Treatment
Acetabular Fracture Associated Injuries / Differential Diagnosis
Acetabular Fracture Complications
Acetabular Fracture Follow-up Care
Acetabular Fracture Review References
It seems that there are a lot of strong opinions on this matter. Just to stir it up a bit more, I will propose that using a Jackson table, lateral position, with traction, and using the peroneal post with the vertical height adjustment gets the best of both worlds. The vertical post overcomes gravity quite easily and facilitates surgical luxation of the head when longitudinal traction is added. The set up is easy, all of the vectors of forces that those who propose prone positioning can be accounted for, and if a troch osteotomy is needed (for whatever reason), it allows access to more anterior structures. I am definitely not a fan of floppy lateral with manual traction. I agree with Chip, this is absolute torture, but I have used all of the described methods and settled on what seemed easiest. Over come the vectors of deformity, eliminate human fatigue (manual traction), and its not so bad. If a T or bad transverse is tough, it is probably not going to be solved, or caused by the position, but probably justifies a sequential procedure with a second postioning and anterior approach. Acetabular and pelvic surgery seemed to bring out the dogma in us all..
Bruce H. Ziran, M.D.
Director of Orthopaedic Trauma
St. Elizabeth Health Center
Associate Professor of Orthopaedic Surgery
Northeast Ohio Universities College of Medicine
> It seems that there are a lot of strong opinions on this matter. Just to stir
> it up a bit more, I will propose that using a Jackson table, lateral position,
> with traction, and using the peroneal post with the vertical height adjustment
Simple as this, 99.99% of surgeons can't safely work and clamp through the notch with the patient positioned laterally. it's just not anatomically possible. and it's all about the reduction. we know that.
Imaging is so easy with a prone patient on a radiolucent table, and it's so troublesome with a laterally positioned patient on a fracture table. we know this too.
Fracture tables with perineal posts and sustained traction (to maintain an approximate and "soft tissue tensioned" based reduction) cause complications that we're all very familiar with. if you are too young, ask those who remember the history and evolution of femoral nailing. it's written.
This is not dogma, it's just reality. it is what it is. you know what you know, but you don't know what you don't know.
These details only matter to the patients and those that you try to teach.
That's enough from me-
A bone fracture (sometimes abbreviated FRX or Fx. Fx . or # ) is a medical condition in which there is a break in the continuity of the bone. A bone fracture can be the result of high force impact or stress. or trivial injury as a result of certain medical conditions that weaken the bones, such as osteoporosis. bone cancer. or osteogenesis imperfecta. where the fracture is then properly termed a pathologic fracture.
Although broken bone and bone break are common colloquialisms for a bone fracture, break is not a formal orthopedic term.Contents Classification Edit Orthopedic Edit
In orthopedic medicine. fractures are classified in various ways. Historically they are named after the doctor who first described the fracture conditions. However, there are more systematic classifications in place currently.
All fractures can be broadly described as:
Other considerations in fracture care are displacement (fracture gap) and angulation. If angulation or displacement is large, reduction (manipulation) of the bone may be required and, in adults, frequently requires surgical care. These injuries may take longer to heal than injuries without displacement or angulation.
Other types of fracture are:
The Orthopaedic Trauma Association. an association for orthopaedic surgeons. adopted and then extended the classification of Müller and the AO foundation  ("The Comprehensive Classification of the Long Bones ") an elaborate classification system to describe the injury accurately and guide treatment.   There are five parts to the code:
There are other systems used to classify different types of bone fractures:Signs and symptoms Edit
Although bone tissue itself contains no nociceptors. bone fracture is very painful for several reasons: 
The natural process of healing a fracture starts when the injured bone and surrounding tissues bleed, forming a fracture Hematoma. The blood coagulates to form a blood clot situated between the broken fragments. Within a few days blood vessels grow into the jelly-like matrix of the blood clot. The new blood vessels bring phagocytes to the area, which gradually remove the non-viable material. The blood vessels also bring fibroblasts in the walls of the vessels and these multiply and produce collagen fibres. In this way the blood clot is replaced by a matrix of collagen. Collagen's rubbery consistency allows bone fragments to move only a small amount unless severe or persistent force is applied.
At this stage, some of the fibroblasts begin to lay down bone matrix (calcium hydroxyapatite ) in the form of insoluble crystals. This mineralization of the collagen matrix stiffens it and transforms it into bone. In fact, bone is a mineralized collagen matrix; if the mineral is dissolved out of bone, it becomes rubbery. Healing bone callus is on average sufficiently mineralized to show up on X-ray within 6 weeks in adults and less in children. This initial "woven" bone does not have the strong mechanical properties of mature bone. By a process of remodeling, the woven bone is replaced by mature "lamellar" bone. The whole process can take up to 18 months, but in adults the strength of the healing bone is usually 80% of normal by 3 months after the injury.
Several factors can help or hinder the bone healing process. For example, any form of nicotine hinders the process of bone healing, and adequate nutrition (including calcium intake) will help the bone healing process. Weight-bearing stress on bone, after the bone has healed sufficiently to bear the weight, also builds bone strength. The bone shards can also embed in the muscle causing great pain. Although there are theoretical concerns about NSAIDs slowing the rate of healing, there is not enough evidence to warrant withholding the use of this type analgesic in simple fractures. Diagnosis Edit
A bone fracture can be diagnosed clinically, based on the history given and the physical examination performed by to view the bone suspected of being fractured.
In situations where x-ray alone is insufficient, a computed tomograph (CT scan) may be performed.Treatment Edit Pain management Edit
In arm fractures in children, ibuprofen has been found to be equally effective as the combination of acetaminophen and codeine. Immobilization Edit
Since bone healing is a natural process which will most often occur, fracture treatment aims to ensure the best possible function of the injured part after healing. Bone fractures are typically treated by restoring the fractured pieces of bone to their natural positions (if necessary), and maintaining those positions while the bone heals. Often, aligning the bone, called reduction. in good position and verifying the improved alignment with an X-ray is all that is needed. This process is extremely painful without anesthesia, about as painful as breaking the bone itself. To this end, a fractured limb is usually immobilized with a plaster or fiberglass cast or splint which holds the bones in position and immobilizes the joints above and below the fracture. When the initial post-fracture edema or swelling goes down, the fracture may be placed in a removable brace or orthosis. If being treated with surgery, surgical nails. screws, plates and wires are used to hold the fractured bone together more directly. Alternatively, fractured bones may be treated by the Ilizarov method which is a form of external fixator.
Occasionally smaller bones, such as phalanges of the toes and fingers. may be treated without the cast, by buddy wrapping them, which serves a similar function to making a cast. By allowing only limited movement, fixation helps preserve anatomical alignment while enabling callus formation, towards the target of achieving union.
Splinting results in the same outcome as casting in children who have a distal radius fracture with little shifting. Surgery Edit
Surgical methods of treating fractures have their own risks and benefits, but usually surgery is done only if conservative treatment has failed or is very likely to fail. With some fractures such as hip fractures (usually caused by osteoporosis or osteogenesis Imperfecta ), surgery is offered routinely, because the complications of non-operative treatment include deep vein thrombosis (DVT) and pulmonary embolism. which are more dangerous than surgery. When a joint surface is damaged by a fracture, surgery is also commonly recommended to make an accurate anatomical reduction and restore the smoothness of the joint. Infection is especially dangerous in bones, due to the recrudescent nature of bone infections. Bone tissue is predominantly extracellular matrix. rather than living cells, and the few blood vessels needed to support this low metabolism are only able to bring a limited number of immune cells to an injury to fight infection. For this reason, open fractures and osteotomies call for very careful antiseptic procedures and prophylactic antibiotics.
Occasionally bone grafting is used to treat a fracture.
Sometimes bones are reinforced with metal. These implants must be designed and installed with care. Stress shielding occurs when plates or screws carry too large of a portion of the bone's load, causing atrophy. This problem is reduced, but not eliminated, by the use of low-modulus materials, including titanium and its alloys. The heat generated by the friction of installing hardware can easily accumulate and damage bone tissue, reducing the strength of the connections. If dissimilar metals are installed in contact with one another (i.e. a titanium plate with cobalt -chromium alloy or stainless steel screws), galvanic corrosion will result. The metal ions produced can damage the bone locally and may cause systemic effects as well.
Electrical bone growth stimulation or osteostimulation has been attempted to speed or improve bone healing. Results however do not support its effectiveness. Complications Edit
Some fractures can lead to serious complications including a condition known as compartment syndrome. If not treated, compartment syndrome can result in amputation of the affected limb. Other complications may include non-union, where the fractured bone fails to heal or mal-union, where the fractured bone heals in a deformed manner.In children Edit
In children, whose bones are still developing, there are risks of either a growth plate injury or a greenstick fracture.
To evaluate the use of rapid prototyping in the assessment, classification and preoperative planning of acetabular fractures.Introduction
The complex three-dimensional anatomy of the pelvis and acetabulum make assessment, classification and treatment of fractures of these structures notoriously difficult. Conventional imaging only provides two-dimensional images of these fractures. While interpretation of traditional imaging techniques becomes better with experience, novel techniques may assist in the understanding of these complex injuries.Methods
Twenty patients with acetabular fractures were studied. Life size three-dimensional models were manufactured from standardised CT scans, using the rapid prototyping process, selective laser sintering. Each model was presented to the operating surgeon prior to surgery. The surgeons found that the models greatly assisted in their understanding of the personality of the fracture. Three consultant orthopaedic surgeons and three senior trainees were asked to classify each fracture using conventional radiographs (AP pelvis, Judet views and CT scans) and then using the model. The kappa statistic was used to evaluate inter- and intraobserver agreement.Results
Interobserver agreement was not absolute using either conventional radiographs or the models. For the consultants the kappa statistic using conventional radiographs was 0.61 while the kappa value using the model was 0.76 (p < 0.05). For the trainees the kappa value was 0.42, using conventional radiographs and 0.71 using the model (p < 0.01).Conclusion
Full sized models of acetabular fractures greatly assisted surgeons understand the personality of complex fractures prior to surgery and have been shown in this study to significantly reduced the degree of interobserver variability in fracture classification. This effect is particularly evident for less experienced surgeons. This technique is available and relatively inexpensive. The use of these models should prove invaluable as a tool to aid clinical practice.Keywords
The complex anatomy of the pelvis and acetabulum make assessment and classification of acetabular fractures notoriously difficult. Acetabular fractures require anatomical reduction for good long-term function. If anatomic reduction is achieved 90% of patients have good results. 2 There is considerable variation in anatomical reduction rates, depending on the type and severity of the fracture, and are as low as 70% in the very difficult T fractures. 3 Any improvement in the preoperative understanding of acetabular fractures should improve reduction rates and thus patient outcome.
Traditional radiological assessment of fractures of the acetabulum involve plain X-rays and computerised tomography. These modalities only provide two-dimensional projections of the complex three-dimensional anatomy. More recent advances have allowed three-dimensional digital images to be reconstructed from computerised tomography scans. These images can be viewed on a computer screen and can be rotated and viewed from any angle. This technology is often only available in the radiology department. Despite these advances in technology, the three-dimensional anatomy is still being viewed as a flat, two-dimensional image.
In the design and manufacturing industry, three-dimensional prototypes can be constructed using computer aided design (CAD) and rapid prototyping. 5 Using this technology and specialised software (MIMICS–Materialise Interactive Medical Image Control System Software, Materialise, Belgium) computerised tomography (CT) scans can be converted into three-dimensional digital models. These digital models can then be used to manufacture life size three-dimensional physical models using the rapid prototyping process, selective laser sintering 1 (Sinterstation 2500 plus, DCM Corp, Valencia, USA) ( Fig. 1 ). In the selective laser sintering process the model is built in successive layers (like a three-dimensional printer. Successive nylon powder layers are spread on top of each other and a computer controlled CO2 laser scans the surface and selectively binds together the powder particles of the corresponding cross section of the digital model ( Fig. 2 ). The process is accurate to 0.1 of a millimetre (far in excess of the resolution provided by a standard CT scan). The finished product is a solid, durable nylon model.
A three-dimensional life size model of a pelvis with a left acetabular fracture. The femur on the left side was digitally subtracted prior to manufacture of the model to enable better appreciation of the intra-articular elements of the fracture.
The goal of this master thesis was to develop a method for real-time classification of market trading data at the Foreign Exchange (FX) department at the Skandinaviska Enskilda Bank (SEB). The characteristics in the market data sets were analyzed using Principal Component Analysis (PCA). The analysis showed that the principal component subspaces for two different types of market data, normal and abnormal, for the EUR/USD instrument where significantly different.
The result from the PCA naturally led into the construction of a Single-class detector, for detecting if quote updates were normal or abnormal based on training data. The market data sets were shown to possess multicollinear characteristics, resulting in low-rank properties of the covariance matrices. To overcome this problem the solution was to transform the data using PCA, resulting in full-rank properties of the covariance matrices of the transformed data. This vital step made it possible to classify quote updates for the EUR/USD instrument.
The project resulted in a classification algorithm which is able to successfully classify if a quote update is normal or abnormal with respect to training data in real-time. The algorithm is versatile in the sense that it can be implemented on any market for any currency pair, and can easily be extended to classify the relative behaviour between several currency pairs in real-time.
AT THIS PAGE YOU CAN DOWNLOAD THE WHOLE ESSAY . (follow the link to the next page)
Running head: What are the Types of Acetabular Fractures and their Treatments?
What are the Types of Acetabular Fractures and their Treatments?
This research paper on will touch on the types of acetabular fractures and what type of treatment is needed for each. There will be an overview of what causes acetabular fractures and what needs to be done for patients that sustain these injuries. This research paper will take you through the steps of evaluating acetabular fractures with diagnostic imaging techniques and evaluation by the physician performing a hands on pelvic exam. There are two classifications of acetabular fractures and they are broken down into several different types of fracture patterns. This paper will go in detail about each type of fracture and then explain if a surgical or non operative approach is needed for healing. It will also inform the reader of what patients have to do in operative and non operative situations.
What are the Types of Acetabular Fractures and their Treatments?
The acetabulum is the cup shaped portion of the hip bone where the ball shaped femoral head fits. Acetabular fractures are usually caused by high energy blunt trauma and usually have other injuries in the pelvis as well (Dipasquale and Nowinski, 2000). The blunt trauma usually results from a high velocity fall or a motor vehicle collision and the femur exerts force onto the femoral head and then onto the acetabulum (Thornton, 2009). Life threatening injuries can also accompany acetabular fractures and these injuries have to be stabilized before a patient can be taken to surgery (Dipasquale and Nowinski, 2000).Fracture fragments that are displaced can cause a breakdown of the cartilage in the hip joint and lead the patient with arthritis(Thacker and Tejwani, 2009). Patients with either type of acetabular fracture, have two options for treatment; surgical or the least invasive approach of.
Affiliations: Department of Orthopaedic Surgery, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200233, P.R. China, Department of Orthopaedic Surgery, Anhui Provincial Hospital, Anhui Medical University, Hefei, Anhui 230001, P.R. China
Published online on: Tuesday, April 30, 2013
This article is mentioned in:Abstract
In the field of hip arthroplasties, the secondary fixation of the implants depends directly on the quality of the primary stability. A good acetabular fit and metaphyseal filling between the prostheses and implants improve the initial stabilization, and optimize the transmission of forces to the bone. A precise knowledge of the three‑dimensional acetabular or femoral shape is essential to the selection of adapted implants. A total of 63 patients diagnosed with developmental dysplasia were analyzed by three‑dimensional computed tomography (3DCT), and the preoperative radiographic and 3DCT images were used to assess the acetabular/femoral deformities and variations of the hips. All joints were classified as Crowe type I, and bilateral measurements were taken for 10 patients. The acetabular abnormalities were classified according to the type of deficiency and the section angles of the acetabulum, with 26 hips (36%) classified as an anterior deficiency, 13 hips (18%) as a posterior deficiency and 34 hips (46%) as a lateral deficiency. The femoral side deformities were divided into three types according to the anteversion angle of the femur. A gradual increase in anteversion angle led to secondary rotational anomalies, and a narrowing of the canal at the isthmus. A total of 35 hips (48%) were classified as an F1 type deficiency, femur anteversion angle (FAVA) 40˚, with significant abnormalities of the femoral canal rotation and the diameter of the isthmus. This novel classification for adult acetabular dysplasia may provide a useful guide for surgery, and enable an improved selection of a suitable prosthesis.Introduction
Acetabular dysplasia (AD) is a developmental dysplasia of the hip (DDH), and is also known as hip joint instability. The characteristic pathological change in AD is a shallow acetabulum that leads to insufficient acetabular containment and coverage of the femoral head; however, radiographic observations have demonstrated that the femoral head remains in the true acetabulum (1 ). Studies from China have revealed that 50–60% of the patients who received a total hip arthroplasty (THA) suffered from osteoarthritis (OA) secondary to hip dysplasia, and a large number of adult AD patients ultimately undergo a total hip replacement (2 ,3 ). It has previously been suggested that the femoral and acetabular anatomical malformations that are apparent with AD increase gradually, in correlation with femoral head displacement (4 ). Since the patients with these anatomical malformations rarely develop further hip subluxations and dislocations, the majority of doctors do not consider the disorder to be a significant disability. However, anatomical variations of the acetabulum and proximal femoral medullary cavity are irregular (5 ), and preoperative X-rays do not identify all patients with AD; the correlation of the X-ray results with intraoperative findings varies greatly. A femoral neck fracture with AD is easily missed in clinical practice, and often leads to postoperative dislocation (6 ). The Crowe classification describes the proximal migration of the femoral head, regardless of the acetabular deformity, and assumes that there is a direct interrelation between the extent of the migration and the severity of disease (7 ). By contrast, the Hartofilakidis classification relies on the anatomy of the acetabulum, as encountered during surgery (8 ). However, the two classifications are not always valid, since the anatomy of the acetabulum and femur is variable, and the extent of migration is not a definite criterion for judging the type of dysplasia (8 ,9 ). Therefore, these classifications have limited uses as surgical guides, and for the selection of a suitable prosthesis. Furthermore, there is no specialized classification for mild DDH, such as AD.
With the increasing prevalence of THA, the incidence of adverse results, such as a fracture in the region surrounding the prosthesis and dislocation, has increased at follow-up. These adverse effects are often correlated with improper intraoperative management, most notably the implantation of a conventional prosthesis into an abnormal medullary cavity (10 ). The correct placement of a suitable prosthesis is the sole method of preventing adverse effects, and ensuring the long-term stability of the prosthesis. Thus, a more effective clinical classification is required to guide surgery. Following an analysis of previous studies, we propose, in the present study, a novel method of assessing acetabular and femoral deformities.Materials and methods Patients
From 2007 to 2011, 63 consecutive patients who were diagnosed with OA secondary to developmental dysplasia, or femoral neck fracture with developmental dysplasia, and who would accept a THA, were treated at Shanghai Sixth People’s Hospital (Shanghai, China). The patient cohort consisted of 14 males and 49 females, with a mean age of 55.6±12.5 years (range, 18–83 years). A total of 55 were diagnosed with OA, and eight with a femoral neck fracture. Patients who had undergone acetabular or femoral osteotomies or who suffered from rheumatoid arthritis were excluded from participation. In addition, patients in whom the dysplasia may have been affected by a neurological illness or Legg-Calvé-Perthes disease were also excluded. There were 32 cases of bilateral and 31 cases of unilateral AD. A total of 10 patients underwent a bilateral THA. Three-dimensional computed tomography (3DCT) was used to clarify whether a deformity existed and, if the result was positive, to identify the degree of acetabular or femoral deformity (11 ,12 ). A total of 30 acetabula or femurs were not able to be located in the normal anatomical sites, due to a significant acetabular or femoral deformity, out of 73 dysplastic hips. The study was conducted in accordance with the Declaration of Helsinki and with approval from the Ethics Committee of Shanghai Sixth People’s Hospital. Written informed consent was obtained from all participants.Radiographic evaluation
The radiographic evidence of AD included a central-edge angle of Wiberg (CE angle) <20° on the anteroposterior radiographs (13 ), and a Sharp angle >45° for the Crowe type I subluxation (14 ). In Crowe type I DDH, the vertical subluxation of the hip (measured from the inferior margin of the tear drop to the head-neck junction) is <50% of the diameter of the femoral head (or <10% of the height of the pelvis) (7 ). CT scans were acquired at a thickness of 1.2 mm, and a table speed of 3.0 mm/s, using a helical scanner (GE Lightspeed 16 Slice CT scanner, GE Healthcare, Waukesha, WI, USA). The helical scanning was conducted at 140 kVp and 300 mAs, and the field of view was 500 mm. Classifying the abnormalities using 3DCT involved basic scanning, ranging from 5 cm above the acetabular roof to the femoral condyles. The CT data were transferred digitally to Digital Imaging and Communications in Medicine (DICOM, version 3.0; National Electrical Manufacturers’ Association, Rosslyn, VA, USA), where the images were formatted (512×512 pixels), prior to the retrieval of the images using a compact disc or a digital versatile disc. These retrieved data were transferred to a personal laptop computer (IBM Lenovo Thinkpad X220i, Lenovo, Inc. Beijing, China), and the 3D bone images of the acetabulum and femur were reconstructed and analyzed using Intage Realia software (KGT, Inc. Tokyo, Japan). The original data were reconstructed in 1 mm intervals on coronal and sagittal images of the hip joint (12 ). Two experienced hip surgeons, who were responsible for performing >200 cases each year, subsequently measured the following parameters, twice (8 ): i) Anterior acetabular section angle (AASA), i.e. the angle between the centerline extending between the bilateral femoral heads, and the line from the center of the head to the anterior margin of the acetabulum (59–83° and 53–92° in normal males and females, respectively (12 ); Fig. 1 ); ii) posterior acetabular section angle (PASA), i.e. the angle between the centerline extending between the bilateral femoral heads, and the line from the center of the head to the posterior margin of the acetabulum [84–116° and 87–120° in normal males and females, respectively (12 ); Fig. 1 )]; iii) acetabular anteversion angle (AcetAV), i.e. the angle between the line extending between the anterior and posterior margins of the acetabulum, and the line perpendicular to the center line connecting the bilateral femoral heads (12 ) (Fig. 1 ); iii) femur anteversion angle (FAVA) (15 ) (Fig. 2 ); iv) canal rotation angle (CRA), i.e. the angle between the major axis of the ellipses of best fit to the endosteal surface of the femoral canal, and a tangent to the posterior aspect of the femoral condyles (4 ,11 ) (Fig. 3 ); v) medio-lateral and vi) antero-posterior canal width at the level of the canal isthmus (the maximum value of the medio-lateral or antero-posterior extracortical diameter of the diaphysis was also recorded); and vii) canal diameter at the isthmus (the point of the medullary canal with the smallest cross-sectional area). The mean of the normal population was used as the control (4 ,11 ). Forty-six healthy controls with normal hip anatomy were also assessed, including 11 males and 35 females, with a mean age of 56.7±11.7 years (range, 25–80 years).
Reformatted axial image on which the acetabular anteversion angle (AcetAV), the anterior acetabular section angle (AASA) and the posterior acetabular section angle (PASA) passing through the center of the femoral heads were measured.
(A) Canal rotation angle (CRA) at three different cross sections of the femoral canal: (B) center of the lesser trochanter (CLT); (C) CLT-4 cm, 4 cm below the CLT; and (D) isthmus. (E) and (F) CRA: the angle between the major axis of the ellipses of best fit to the endosteal surface of the femoral canal and a tangent to the posterior aspect of the femoral condyles.Classification
The acetabular abnormalities were classified into A1-type anterior, A2-type posterior and A3-type lateral (including mild and global) deficiencies (Table I ) (12 ). The femoral classification was as follows: F1-type, FAVA <30°; F2-type, 30°≤ FAVA ≤40°, with mild abnormalities of the femoral canal rotation and the diameter at the isthmus; F3-type, FAVA >40°, with significant abnormalities of the femoral canal rotation and the diameter at the isthmus (Tables II and III ). There were 21 A1-type cases (26 hips), nine A2-type cases (13 hips) and 33 A3-type cases (34 hips). In addition, there were 33 F1-type cases (35 hips), 26 F2-type cases (32 hips) and four F3-type cases (six hips).
Classification of acetabular dysplasia.Statistical analysis
The database was established via statistical analysis using SPSS 19.0 (SPSS, Inc. Chicago, IL, USA). For variables that were normally distributed, differences between the types were evaluated using analysis of variance (ANOVA), followed by the unpaired t-test for multiple pair-wise comparisons of all significant variables. Categorical data were compared using the χ 2 test. To assess the intraobserver reliability of the different parameters of the femur or the acetabulum, the preoperative radiographs for each patient were templated by an investigator, who subsequently repeated the templating two weeks later. In addition, the templating procedure was repeated by a second investigator, independently. The intra- and interobserver effects were calculated using an intraclass correlation coefficient (ICC) (8 ). Pearson’s correlation coefficient was used to assess the correlations between various measurements. P<0.05 was considered to indicate a statistically significant difference (Tables II and III ).Results
When the acetabular and femoral abnormalities were divided into subgroups, using 3DCT, it was observed that there was a crossover between each of the femoral subtypes (F1, F2 and F3) and the acetabular subtypes (A1, A2, or A3), with the exception that the F3-type deficiency did not appear in conjunction with the A2-type deficiency. Significant differences were demonstrated in the AcetAV (P<0.05), AASA (P<0.05) and PASA (P<0.05) between the A1, A2 and A3-type deficiencies (A1 versus A2, A1 versus A3 and A2 versus A3); however, no significant differences were observed in the CE angle (P>0.05) or the Sharp angle (P>0.05). The AASA values of the A1, A2 and A3-type deficiencies were significantly different from that of the control group (P<0.05), whereas only the PASA values of the A2 and A3-type deficiencies were significantly different in comparison with the PASA value of the control group (P<0.05; Table II ). There was a significant Pearson’s correlation between the AASA and the AcetAV (r=−0.353, P=0.002), and between the PASA and the AcetAV (r= 0.5, P= 0.001), indicating that hips with a greater AASA also had a lower AcetAV, and that those with a greater PASA also had a higher AcetAV. No significant differences were observed in the AcetAV between the A3-type deficiency and the control (t=0.102, P=0.92). The intra- and interobserver reliability values of the acetabular classification, obtained using ICC, were 0.843 and 0.862, respectively, which indicated good reproducibility in the acetabular measurements.
Table III displays the canal width at the level of the isthmus in the antero-posterior and medio-lateral directions, and the canal diameter at the isthmus; significant differences were observed between the control and the F2 and F3-type deficiencies (P<0.05), but not between the control and the F1-type deficiency (P>0.05). There was no significant difference in the canal diameter at the isthmus between the F2 and F3-type deficiencies (P=0.336), although the mean diameter of the canal of the F3-type femurs was smaller than that of the F2-type femurs (8.9 mm versus 9.7 mm). The CRAs at the three levels were significantly different between the F2 and F3-type deficiencies (P<0.05). There were no significant differences in the CRAs between the F1-type deficiency and the control cases; however, significant differences were observed in a comparison between the F2 and F3-type deficiencies and the control (P<0.05). From the center of the lesser trochanter (CLT) to the medullary cavity of the isthmus, a gradual increase was observed in the CRA. However, it was observed that there was a significantly higher mean increase in the CRA from the CLT to the isthmus in the control cases (40°), in comparison with that of the F2 (34°) and F3 (28°)-type deficiencies. The variation in femoral anteversion in the F3-type deficiency was of a greater significance than that in the F1 and F2-type hips (P<0.05). It was observed that femurs with a greater FAVA also appeared to have narrower canals (r=−0.315, P=0.007), and a smaller CRA at the isthmus (r=−0.696, P= 0.007).
There was no significant correlation between the FAVA and the AcetAV in the dysplastic hips overall (r=0.001, P=0.996). However, when the hips were divided into subgroups, a significant positive correlation was observed between the FAVA and the AcetAV in the anterior deficiency subgroups (r= 0.394, P= 0.046). By contrast, there was no significant correlation between the FAVA and the AcetAV in the posterior and global deficiency subgroups (r=−0.006, P=0.973; and r=0.038, P=0.829, respectively). The intra- and interobserver reliability values of the femoral classification, obtained using ICC, were 0.813 and 0.822, respectively, which indicated that there was an acceptable reliability in the femoral measurements. There were no significant differences in the average age (t=0.585, P= 0.561) or gender (χ 2 = 0.040, P= 0.836) of the 63 patients with AD compared with the 46 healthy controls. In the control hips, no significant correlations were observed between the FAVA and the AcetAV, Sharp angle or CE angle (r=−0.115, P= 0.448; r= 0.041, P= 0.785; and r= 0.026, P= 0.078, respectively). However, there was a significant positive correlation between the FAVA and the Sharp angle (r=0.456, P=0.00), and a significant negative correlation between the FAVA and the CE angle (r=−0.473, P=0.00) in the dysplastic hips.Discussion
In this study of 73 dysplastic hips and 46 normal hips, the morphological differences between dysplastic and normal hips were observed, and significant correlations between the AcetAV and the acetabular anterior or posterior deficiency subgroups were identified. In addition, it was demonstrated that there was a significant correlation betwen the femoral anteversion and the AcetAV in the anterior deficiency subgroup. It was revealed by Akiyama et al (5 ) that changes in the AASA, PASA and AcetAV may be detected by 3DCT, and that 3DCT clearly exhibits the location and extent of the dysplasia. In a study by Ito et al (12 ), 22 of 84 AD hips (26%) were classified as having an anterior deficiency; 17 (20%), a posterior deficiency; and 45 (54%), a lateral deficiency. Hips with poor anterior acetabular support were defined as those with an AASA <50°, while hips with poor posterior support were defined as those with a PASA <90° (12 ). In a previous study, the AASA, PASA, and AcetAV measurements were demonstrated to be effective for the precise evaluation of various acetabular deficiencies (16 ). Anda et al (17 ) revealed that the AcetAV in the anterior deficiency subgroup was significantly larger than in the other groups. By contrast, the AcetAV in the posterior deficiency subgroup has been observed to be smaller than that in the normal and global deficiency subgroups (5 ). The results of these studies supported the observations in the present study. In addition, the results of the present study demonstrated a trend towards increased or decreased acetabular anteversion in shallow hips with poor anterior or posterior support.
The previously mentioned results indicated the existence of a potential developmental interaction between the femur and acetabulum. When the dysplastic hips were divided according to the location of the acetabular bone defect, significant differences in acetabular version were observed among the subgroups. It was demonstrated that hips with a larger FAVA appeared to additionally have an increased AcetAV, indicating a biomechanical cycle resulting in the pathology of dysplastic hips with anterior acetabular deficiency (5 ). By contrast, no correlation in version was observed in hips with a posterior or global deficiency. However, it was demonstrated that there was a significant correlation between the FAVA and the Sharp/CE angles in the dysplastic acetabula.
Although the previous studies indicated that each type of dysplasia was correlated with the degree of the dysplasia, rather than the specific type of severity, they did not offer a systematic and detailed guide for THA. The large individual acetabular morphological variability across all levels of dysplasia observed in this study demonstrated that it is not possible to select an acetabular prosthesis for dysplastic hips on the basis of the severity of the subluxation alone. The results of the study suggested that there is a requirement for the surgeon to choose the type of socket implantation according to the type and extent of the acetabular defect, and to adapt to the individual FAVA. Thus, it is necessary for each patient be considered individually, in order that the angle of the acetabular cup may be customized to suit (9 ). For the A1-type deficiency, a reduction in the AcetAV or a neutral position is required when the cup is implanted. In cases with an excessive FAVA, a decrease in the FAVA is required for the inclusion and congruity of the hip joint (5 ). For the A2-type deficiency, an appropriate increase in the AcetAV is required to resolve the initial instability, in order to prevent the aggravation of the posterior acetabular insufficiency. In the present study, no significant differences were found in the AcetAV between the A3-type deficiency (mild or global) and the control group. The acetabular defects predominantly occurred on the upper and lateral margins of the acetabulum, although anterior and posterior deficiencies were also observed with the global deficiency. Due to the absence of structural bone defects in the acetabula, and since the acetabular cup covers >70% of the bone bed, there is a requirement for the acetabular cup to be placed at the center of the acetabulum, and for normal anteversion to be maintained (2 ). Since mild or global deficiencies of the acetabulum require similar methods of prosthetic implantation, hips with these types of deficiency may be classified as having a lateral deficiency (12 ). The treatment of femoral abnormalities or variations with A1, A2 or A3-type deficiencies are described in greater detail later in this study.
The present study revealed the morphological characteristics of dysplastic femurs, and investigated the effects of the disorder on the geometry of the intramedullary canal. These results were then compared with a control group. It was demonstrated that in cases with excessive anteversion, the dysplastic femurs were smaller than the control femurs, with narrower, straighter and less-tapered canals. Sugano et al and Noble et al (4 ,11 ) observed that the 3D anatomy of a femur with the mildest degree of subluxation (Crowe type I) exhibited a significantly different FAVA and medullary cavity rotation, and that several patients had a FAVA >60°. In addition, it was demonstrated that the diameter of the femoral medullary cavity was reduced in the Crowe type I femurs. The minimum diameter of the canal in the Crowe type I femurs was 1 mm less than in the control femurs (4 ,11 ). Argenson et al (9 ) revealed that the mean diameter of the medullary cavity was >1.6 mm narrower in the antero-posterior and >1.9 mm narrower in the medio-lateral position in the Crowe type I than in the control femurs (9 ,11 ). The canal flare and metaphyseal canal flare indices were used to assess variations in the width of the femoral medullary cavity on anteroposterior radiographs (18 ). X-rays are only able to assess the femoral marrow cavity in two dimensions; however, with the exception of the differences in canal width, it is important that the morphological characteristics of the femoral medullary cavity at different levels are identifiable with 3DCT. Therefore, the measurements were performed in three dimensions, i.e. in the axial, coronal and sagittal planes (19 ). It was observed that the normal rotation angle of the medullary canal gradually increased from the CLT to the isthmus. However, in the dysplastic femurs, the increased ante-version of the proximal femur resulted in a reduction in the rotation in the medullary canal, predominantly in the region from the CLT to the canal at the isthmus (4 ,11 ). The variation between the F2 and F3-type deficiencies supported this observation. With regard to surgery, this variation is critical, since it is necessary to be aware of variations in the width of the medullary cavity when the femoral canal is reamed, in order to avoid femoral fractures. When the femoral stem is implanted, there is a requirement for the morphological differences that occur at different levels of the medullary cavity to be considered, in order to ensure that the prosthesis closely matches the medullary cavity of the femur. Therefore, when the FAVA is exaggerated, the rotational orientation has a marked effect on the size and shape of the canal (11 ), and the concomitant twist of the femoral canal increases the difficulty of the joint replacement.
The results of the present study demonstrated that the position of the femoral anterior arch in the femurs with AD was not significantly different from that observed in the control group. This indicated that the primary anatomical feature affecting the successful placement of the stem is increased femur anteversion, leading to secondary rotational anomalies and a narrowing of the canal at the isthmus. Therefore, these features were the basis of our classification (4 ,9 ). With regard to the F1-type deficiency (FAVA <30°), femoral stem implantation with a normal FAVA is possible. For the F2-type deficiency (30°≤ FAVA <40°, with mild abnormalities of the femoral canal rotation and the isthmus diameter) it may be appropriate to adjust the FAVA from 15° to 25°, due to the anteversion of the acetabular cup. However, following femoral neck osteotomy, the cross-section of the long axis of the femur is not usually consistent with that required by the femoral stem. If a proximal fixed prosthesis is chosen, stability is poor; therefore, in the majority of cases a prosthesis with a straight and thin distal stem is required to accommodate this diaphyseal femoral anatomy (20 ). With regard to F3-type deficiencies, with significant abnormalities of the femoral canal rotation and a reduced isthmus diameter, it has been demonstrated that modular or customized components are necessary, in order to accommodate the shape of these dysplastic canals (21 ,22 ). Furthermore, the present study indicated that the templating technique exhibited the desired reliability, with all the ICC values exceeding 0.8 (8 ).
A retrospective database and image review was used to summarize the diversity of mild dysplasia; this reinforced the observations of a number of previous studies, concerning the exaggerated anteversion in mildly dysplastic femurs. At present, the majority of doctors do not consider the disorder of mild dysplasia to be a great disability, and, furthermore, preoperative 3DCT scans are not routinely requested for Crowe type I hips, due to the additional medical expense. However, the present study revealed the anatomical variations of the acetabulum and proximal femoral medullary cavity to be irregular and interrelated (∼41.1% of cases), and preoperative X-rays and 2DCT scans of the hip joint are not able to identify any correlation between these variations. It is therefore important that the results of 3D scans are assessed preoperatively, and that any interrelation between the femoral and acetabular morphologies is identified by the surgeons. The aim of this investigation was to emphasize the morphological variations in mild dysplasia, particularly in the femoral medullary cavity and the acetabulum, as a primary step to determining the potential requirements for surgical procedures. The results of this study are likely to provide a greater insight into the morphological characteristics of dysplastic hips, and the challenges confronting joint replacement surgeons.
In addition to suggesting a novel anatomic classification, this study provided a detailed characterization of the anatomical variations to be considered in hip arthroplasty implants for patients with AD. The purpose of this 3D morphometric analysis was to serve as an anatomical reference for acetabular and femoral implants. The novel classification employed in this study used 3DCT measurements to clarify the location and extent of acetabular deficiency, the diameter of the medullary cavity at the isthmus and the degree of rotational deformity. This is likely to facilitate the improved management of malformations of the acetabulum and femur, and to ensure the selection of a suitable prosthesis. Since the initial assessment of the patients with AD has been adopted, the individualized prosthesis implantation and surrounding bone matching have achieved the desired results, thereby increasing the long-term survival rates of the prostheses.Acknowledgements
This study was supported by the Interdisciplinary (Engineering-Medical) Research Fund of Shanghai Jiao Tong University (grant no. YG2011MS30), Shanghai Municipal Health Bureau Science Fund for Young Scholars (grant no. 2010QJ036A), the Opening Project of the State Key Laboratory of High Performance Ceramics and Superfine Microstructure (grant no. SKL201206SIC) and the National Natural Science Foundation of China (grant no. 81171688).References
Zhu, C. Cheng, M. Cheng, T. Ma, R. Kong, R. Guo, Y. Zhang, X. (2013). A novel classification to guide total hip arthroplasty for adult acetabular dysplasia. Experimental and Therapeutic Medicine, 6, 216-222. http://dx.doi.org/10.3892/etm.2013.1093
Zhu, C. Cheng, M. Cheng, T. Ma, R. Kong, R. Guo, Y. Qin, H. Shi, S. F. Zhang, X."A novel classification to guide total hip arthroplasty for adult acetabular dysplasia". Experimental and Therapeutic Medicine 6.1 (2013): 216-222.
Zhu, C. Cheng, M. Cheng, T. Ma, R. Kong, R. Guo, Y. Qin, H. Shi, S. F. Zhang, X."A novel classification to guide total hip arthroplasty for adult acetabular dysplasia". Experimental and Therapeutic Medicine 6, no. 1 (2013): 216-222. http://dx.doi.org/10.3892/etm.2013.1093