Effect of risedronate on hip structural geometry: a 1-year, double-blind trial in chemotherapy-induced postmenopausal women

INTRODUCTION

Chemotherapy-induced menopause is associated with bone loss. The effect on structural geometry is unknown. Our objective was to determine if oral bisphosphonate therapy could maintain or improve femoral geometry in breast cancer patients with chemotherapy-induced menopause.

METHODS

This preplanned 1 year interim, secondary analysis of the Risedronate's Effect on Bone loss in Breast CAncer Study (REBBeCA Study) examined hip structure analysis (HSA), i.e. changes in the bone cross-sectional area (bone CSA), section modulus (SM: measure of bending strength), cortical thickness (CT) and buckling ratio (BR: index of cortical bone stability), in a double-blind trial of 87 newly postmenopausal, nonmetastatic breast cancer patients, randomized to risedronate, 35 mg once weekly (RIS) versus placebo (PBO).

RESULTS

After 12 months, intertrochanteric parameters demonstrated percentage improvement (RIS vs. PBO) from baseline in bone CSA (mean+/-SD: 4.25+/-6.29 vs. 0.60+/-5.99%), SM (3.97+/-6.40 vs. 0.80+/-7.08%), and CT [5.20+/-6.98 vs. 1.13+/-6.87% (all p-values <0.05 except SM p=0,0643)]. Similar improvements were observed at the femoral shaft [bone CSA: 2.24+/-5.74 vs. -0.78+/-5.73%; SM: 1.62+/-6.23 vs. -1.39+/-7.06%; CT: 3.79+/-7.84 vs. -0.17+/-7.90% (all p-values <0.05, RIS vs. PBO, except SM p= p =0.0568)]. At both sites, the BR had significant decreases consistent with improved strength.

CONCLUSION

We conclude that RIS improves measures of hip structural geometry in women with breast cancer following chemotherapy.

Sexual dimorphism of the hip joint in Greeks

The objective of the present study was to report our measurements of hip bones within the Greek population and review the possible implications of these differences in their health as well as in social life. For this purpose the remains of 100 male and 100 female pelvic and femoral bones were studied. The distance from the pubic tubercle to the anterior rim of the acetabulum, the acetabulum diameter between its rims, their ratio, the depth of the acetabulum, the diameter of the femoral head and the ratio between the femoral head and the diameter of the acetabulum were measured. It was found that in males, in comparison to the females, the distance from the pubic tubercle to the anterior rim of the acetabulum was smaller while the acetabulum diameter and its depth, the diameter of the femoral head and the ratio between femoral head and the acetabulum diameter were larger. The above differences reached strong statistical significance. Of the two ratios used only the first one reached statistical significance. Using this ratio alone offered the best discrimination rate of up to 99% and should be the preferred choice when available.

[Optimization of capsulotomy of enhanced posterior soft tissue repair in total hip arthroplasty]

OBJECTIVE

To investigate the anatomic feature of the posterior hip joint capsule and its distributional difference of collagen fibers and to probe the optimization of the capsulotomy which can reserve the best strength part.

METHODS

Ten adult cadaver pelvises (6 males and 4 females, aged 28-64 years) fixed with formalin were used. Ten right hips were used for anatomical experiment of hip joint capsule. The posterior hip joint capsules were divided into 3 sectors (I-III sectors) and 9 parts (I(A-C), II(D-F), III(G-I). The average thickness of each part was measured and the ischiofemorale ligaments were observed. Five capsules selected from ten left hips were used for histological experiment. The content of collagen fibers in sector I and sector II was analyzed by Masson's staining. Two fresh frozen specimens which were voluntary contributions were contrasted with the fixed specimens. The optimal incision line of the posterior capsule was designed and used.

RESULTS

The thickness in the posterior hip joint capsule [I(A) (2.30 +/- 0.40), I(B) (4.68 +/- 0.81), I(C) (2.83 +/- 0.69), II(D) (2.80 +/- 0.79), II(E) (4.22 +/- 1.33), II(F) (2.50 +/- 0.54), III(G) (1.57 +/- 0.40), III(H) (2.60 +/- 0.63), III(I) (1.31 +/- 0.28) mm] had no uniformity (P < 0.01). The III(G) part and the III(I) part were thinner than the I(B) part and the II(E) part (P < 0.01). Two weaker parts located at obturator externus sector (sector III), the ischiofemorale ligament trunk went through two thicker parts (I(B) and II(E)). The distribution of the collagen fibers in sector I and sector II(I(A) 20.34% +/- 5.14%, I(B) 48.79% +/- 12.67%, I(C) 19.87% +/- 5.21%, II(D) 17.57% +/- 3.56%, II(E) 46.76% +/- 11.47%, II(F) 28.65% +/- 15.79%) had no uniformity (P < 0.01). The content of collagen fibers in I(B) part and II(E) part were more than that of other parts (P < 0.01). There were no statistically significant difference in the distribution feature of the thickness and the ischiofemorale ligaments between the fresh frozen specimens and the fixed specimens. The optimal incision line C-A-B-D-E of the posterior capsule was designed and put into clinical application. The remaining capsular flap comprise the most of the ischiofemorale ligament trunk and the part of gluteus minimus.

CONCLUSION

Although enhanced posterior soft tissue repair in total hip arthroplasty was investigated deeply and obtained great development, but the postoperative dislocation rate was not eliminated. It is significant for optimizing the capsulotomy to reserve the best strength part of the posterior capsule and to bring into full play the function of the ischiofemorale ligaments.

Confirmation of needle placement within the piriformis muscle of a cadaveric specimen using anatomic landmarks and fluoroscopic guidance

Of patients presenting to pain clinics, complaints are of low back or buttock pain with or without radicular leg symptoms is one of the most common. Piriformis syndrome may be a contributor in up to 8% of these patients. The mainstay of treatment is conservative management with physical therapy, anti-inflammatory medications, muscle relaxants, and correction of biomechanical abnormalities. However, in recalcitrant cases, a piriformis injection of anesthetic and/or corticosteroids may be considered. Because of its small size, proximity to neurovascular structures, and deep location, the piriformis muscle is often injected with the use of commuted tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), fluoroscopy, electrical stimulators, or electromyography (EMG). Numerous techniques have been proposed using one or a combination of the above modalities. However, application of these techniques is limited by unavailability of CT, MRI, and EMG equipment as well as a paucity of trained physicians in US-guided procedures in many pain treatment centers throughout the United States. Fluoroscopy, however, is more widely available in this setting. This study utilized a cadaveric specimen to confirm proper needle placement for piriformis or peri-sciatic injection utilizing the previously documented landmarks for fluoroscopic guidance as described by Betts. An anteroposterior of the pelvis with inclusion of the acetabular region of the hip and the inferior aspect of the sacroiliac joint was obtained. The most superior-lateral aspect of the acetabulum and the inferior aspect of the sacroiliac joint were identified. A marker was placed one-third of the distance from the acetabular location to the inferior sacroiliac joint, indicating the target location. A 22-gauge, 3.5-inch spinal needle was directed through the gluteal muscles to the target location using intermittent fluoroscopic guidance. The posterior ileum was contacted and the needle was withdrawn 1 -2 mm. This approach found the needle within the piriformis muscle belly 2 -3 cm lateral to sciatic nerve. The present study was the first study, to our knowledge, that has confirmed the intramuscular position of the needle within the piriformis muscle of a cadaveric specimen using these anatomic landmarks and fluoroscopic guidance.

[Pressure on the bearing surface of the hip joint (author's transl)]

The 3-dimensional geometry of the articular surface of the hip joint was reconstructed using data obtained from ap radiograms of the pelvis. Combining the results of this calculation with data published on the weight distribution of adult persons, the mean and the standard deviation of the pressure on the articular surface of the hip joint are calculated.

The shape of the acetabular cartilage surface: a geometric morphometric study using three-dimensional scanning

The acetabular cartilage surface plays an important role in hip joint biomechanics, locomotion and lubrication, but few studies has focused on its geometric morphometry. The aim of this study was to present a novel, accurate mathematical representation of the acetabular cartilage surface based on a new method, combined with a reverse engineering technique, surface-fitting algorithms and mathematical curve surface theory. By using a three-dimensional (3D) laser scanner, a 3D triangulated mesh surface approximation of acetabular cartilage was created. Using surface-fitting algorithms and mathematical curve surface theory, two main curvature parameters, Gaussian curvature and mean curvature at each point on the surface of the acetabular cartilage, were calculated. The distribution patterns of both parameters over the curved surface were elucidated and the eigenvalues of the surface were calculated to determine the shape of the acetabular cartilage surface. By statistically analyzing 25 specimens, it was found that the shape of the acetabular cartilage surface was not theoretically spherical but rotational ellipsoidal, which is a novel mathematical description. The surface-fitting error of a rotational ellipsoid shape was significantly smaller than that of a spherical shape for representing the acetabular cartilage surface (p<0.001). The highest surface-fitting error for a spherical shape was seen in the roof area of the acetabular cartilage, where a rotational ellipsoid surface presented a better anatomical fit. The results will not only be helpful in gaining a new anatomical understanding of the acetabular cartilage surface, but will also be usable in the construction of a precise 3D numerical model in simulation studies of the hip joint.

Hip joint contact force in the emu (Dromaius novaehollandiae) during normal level walking

The emu is a large, (bipedal) flightless bird that potentially can be used to study various orthopaedic disorders in which load protection of the experimental limb is a limitation of quadrupedal models. An anatomy-based analysis of normal emu walking gait was undertaken to determine hip contact forces for comparison with human data. Kinematic and kinetic data captured for two laboratory-habituated emus were used to drive the model. Muscle attachment data were obtained by dissection, and bony geometries were obtained by CT scan. Inverse dynamics calculations at all major lower-limb joints were used in conjunction with optimization of muscle forces to determine hip contact forces. Like human walking gait, emu ground reaction forces showed a bimodal distribution over the course of the stance phase. Two-bird averaged maximum hip contact force was approximately 5.5 times body weight, directed nominally axially along the femur. This value is only modestly larger than optimization-based hip contact forces reported in literature for humans. The interspecies similarity in hip contact forces makes the emu a biomechanically attractive animal in which to model loading-dependent human orthopaedic hip disorders.

Disproportional geometry of the proximal femur in patients with Turner syndrome: a cross-sectional study

OBJECTIVE

Patients with Turner syndrome (TS) have altered growth and increased risk of osteoporosis due to oestrogen deficiency and possibly a host of other factors. Thus, TS patients have a 4.9-fold increased risk of femoral neck fractures. Most patients are treated with oestrogen during puberty and adolescence to facilitate pubertal development and prevent secondary osteoporosis. The geometry of the hip is a predictor for hip fractures independent of bone mineral density (BMD). The purpose of the present study was to investigate the variation of the geometry of the hip in patients with TS in comparison with healthy controls.

PATIENTS

The study population comprised 58 patients with TS (aged 22-67 years) and 60 age-matched healthy women (aged 21-65 years).

MEASUREMENTS

Hip axis length (HAL), neck width (NW), neck shaft angle (NSA), and femoral head-radius (HR) on dual-energy X-ray absorptiometry (DXA) screen images. These parameters related to age of oestrogen supplementation, menarche, and duration of oestrogen exposure.

RESULTS

Height was 146.6 +/- 6.9 cm and 167.1 +/- 6.2 cm (P < 0.1) and weight 57.4 +/- 13.9 kg and 62.3 +/- 8.3 kg (P < 0.001) in patients and controls, respectively. After adjustment for differences in height, HAL was not significantly different (9.4 +/- 0.5 vs. 9.5 +/- 0.5 cm; NS) in TS compared with controls while NW was significantly increased (3.5 +/- 0.4 cm vs. 3.3 +/- 0.2 cm, P < 0.001), NSA was similar (129 +/- 4 degrees vs. 130 +/- 4 degrees , NS), and HR was significantly decreased (4.1 +/- 0.4 vs. 4.5 +/- 0.3 cm, P < 0.001). The duration of oestrogen exposure was significantly shorter among TS, but did not correlate significantly with the geometrical parameters in either TS or controls.

CONCLUSION

Our data demonstrates that hip geometry is disproportionate in TS compared with normal controls. The altered hip geometry, however, cannot explain the increased risk of hip fracture in TS.

The relationship between hip joint space width, center edge angle and acetabular depth

OBJECTIVE

Radiographic parameters used to define acetabular dysplasia may be related to anthropological characteristics independent of dysplasia. The goal of the present study was to investigate the relationship between the minimal joint space width (JSW) of the hip and the parameters that define acetabular dysplasia, in clinically normal subjects.

DESIGN

One hundred and eighteen patients who underwent supine abdominal radiography for non-rheumatological indications and had no hip pain or history of hip arthritis were evaluated. JSW was quantified manually using dial calipers, and center edge (CE) angle and acetabular depth were measured for each hip.

RESULTS

CE angle, but not acetabular depth, correlated (inversely) with the minimal hip JSW (r=-0.26 and -0.20, P=0.005 and 0.038, R (right) and L (left) hips, respectively). CE angle inversely correlated with the pelvic width (r=-0.27 and 0.27, P=0.003 and 0.004, R and L hips, respectively) and acetabular depth correlated with subject's height (r=0.27 and 0.42, P=0.008 and <0.001 R and L hips, respectively) and leg length (r=0.27 and 0.45, P=0.008 and <0.001, R and L hips, respectively). Also, pelvic width correlated significantly with the JSW (r=0.27 and 0.20, P=0.003 and 0.033, for R and L hips, respectively).

CONCLUSIONS

The radiographic parameters used to define acetabular dysplasia, CE angle and acetabular depth, are strongly associated with anthropological variables and CE angle is associated with minimal JSW of the hip. It is important to recognize that height and limb length variability may affect radiographic parameters of acetabular dysplasia, and thus may falsely suggest the presence of anatomic abnormalities in some patients.

Acetabular labral tears of the hip in women

Acetabular labral tears are a major cause of hip dysfunction in young patients and a primary precursor to hip osteoarthritis. In addition, labral disease more commonly occurs in women and can present with nonspecific symptoms. It is possible to diagnose, quantify, and treat labral tears before the onset of secondary joint deterioration. However, the diagnosis requires a high index of suspicion, special attention to subtle patterns of presentation, and timely consideration for imaging studies. Treatment options are still evolving and include a wide array of nonsurgical and surgical techniques. Treatment should also address secondary dysfunction that can be associated with hip pathology. An initial trial of conservative management is recommended and failure to progress is an indication for surgical consultation.

Bivariate linkage study of proximal hip geometry and body size indices: the Framingham study

Femoral geometry and body size are both characterized by substantial heritability. The purpose of this study was to discern whether hip geometry and body size (height and body mass index, BMI) share quantitative trait loci (QTL). Dual-energy X-ray absorptiometric scans of the proximal femur from 1,473 members in 323 pedigrees (ages 31-96 years) from the Framingham Osteoporosis Study were studied. We measured femoral neck length, neck-shaft angle, subperiosteal width (outer diameter), cross-sectional bone area, and section modulus, at the narrowest section of the femoral neck (NN), intertrochanteric (IT), and femoral shaft (S) regions. In variance component analyses, genetic correlations (rho ( G )) between hip geometry traits and height ranged 0.30-0.59 and between hip geometry and BMI ranged 0.11-0.47. In a genomewide linkage scan with 636 markers, we obtained nominally suggestive linkages (bivariate LOD scores > or =1.9) for geometric traits and either height or BMI at several chromosomes (4, 6, 9, 15, and 21). Two loci, on chr. 2 (80 cM, BMI/shaft section modulus) and chr. X (height/shaft outer diameter), yielded bivariate LOD scores > or =3.0; although these loci were linked in univariate analyses with a geometric trait, neither was linked with either height or BMI. In conclusion, substantial genetic correlations were found between the femoral geometric traits, height and BMI. Linkage signals from bivariate linkage analyses of bone geometric indices and body size were similar to those obtained in univariate linkage analyses of femoral geometric traits, suggesting that most of the detected QTL primarily influence geometry of the hip.

The internervous safe zone for incision of the capsule of the hip. A cadaver study

In order to determine the potential for an internervous safe zone, 20 hips from human cadavers were dissected to map out the precise pattern of innervation of the hip capsule. The results were illustrated in the form of a clock face. The reference point for measurement was the inferior acetabular notch, representing six o'clock. Capsular branches from between five and seven nerves contributed to each hip joint, and were found to innervate the capsule in a relatively constant pattern. An internervous safe zone was identified anterosuperiorly in an arc of 45 degrees between the positions of one o'clock and half past two. Our study shows that there is an internervous zone that could be safely used in a capsule-retaining anterior, anterolateral or lateral approach to the hip, or during portal placement in hip arthroscopy.

Computed tomographic evaluation of growth-related changes in the hip joints of young dogs

OBJECTIVE

To evaluate changes in canine hip joint characteristics during growth via computed tomography (CT) and compare CT features of hip joints with and without laxity in young dogs placed in 2 imaging positions.

ANIMALS

21 dogs (42 hip joints).

PROCEDURES

From 2 to 12 months after birth, CT examinations of the acetabulum of each hip joint in simulated normal standing and simulated weight-bearing positions were performed monthly for all dogs. Acetabular angle, dorsal acetabular rim angle (DARA), and femoral head diameter (FHd) were analyzed as skeletal variables; the lateral center edge angle (LCEA), dorsolateral subluxation (DLS) score, and center distance (CD) index were analyzed as joint laxity variables. At 12 months, all dogs underwent the Ortolani test to as-sess hip joint laxity.

RESULTS

Hip joint laxity was detected in 5 dogs (10 joints) at 12 months of age; from 2 months, the acetabular angle and FHd increased and DARA decreased significantly until 5 months and the LCEA and DLS score increased significantly until 6 months. In nonlax hip joints in both positions, the CD index decreased significantly until 4 months of age and be-came stable thereafter. In lax hip joints, the CD index increased from 4 through 12 months; between 8 and 12 months, these changes were significantly greater in the weight-bearing position than in the standing position.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that CT-detected abnormalities in the DARA and CD index during body weight loading might be useful indicators of hip dysplasia in 2- to 6-month-old dogs.

Hip2Norm: an object-oriented cross-platform program for 3D analysis of hip joint morphology using 2D pelvic radiographs

We developed an object-oriented cross-platform program to perform three-dimensional (3D) analysis of hip joint morphology using two-dimensional (2D) anteroposterior (AP) pelvic radiographs. Landmarks extracted from 2D AP pelvic radiographs and optionally an additional lateral pelvic X-ray were combined with a cone beam projection model to reconstruct 3D hip joints. Since individual pelvic orientation can vary considerably, a method for standardizing pelvic orientation was implemented to determine the absolute tilt/rotation. The evaluation of anatomically morphologic differences was achieved by reconstructing the projected acetabular rim and the measured hip parameters as if obtained in a standardized neutral orientation. The program had been successfully used to interactively objectify acetabular version in hips with femoro-acetabular impingement or developmental dysplasia. Hip(2)Norm is written in object-oriented programming language C++ using cross-platform software Qt (TrollTech, Oslo, Norway) for graphical user interface (GUI) and is transportable to any platform.

Mechanical devices to help in PennHIP examination

A modified PennHIP procedure (MPP), using specific mechanical holding devices, was used on 70 dogs and compared to the standard PennHIP method (SPM) used on 39 dogs, in terms of technical effectiveness and the mean number of essential individuals within the X-ray room (EIXRR). The data using the Chi-squared test were consistent with the null hypothesis that the technical effectiveness was equal in the groups under investigation (P > 0.05). On the contrary, using the two-sample unpaired t-test the null hypothesis, that the mean EIXRR was equal, was rejected (P < 0.001). The estimated EIXRR was 3.4 +/- 0.7 and 5.7 +/- 1.2 (mean +/- SD) for MPP and SPM, respectively. In conclusion, the MPP needs fewer EIXXR than the SPM and complies with the new recommendations in X-ray protection, which introduce the ALARA (as-low-as-reasonably-achievable) idea.

Future of tissue engineering in rheumatic diseases

Chronic inflammation during rheumatoid arthritis and degenerative processes during osteoarthritis eventually result in joint destruction. Anti-inflammatory therapies facilitate the inhibition or delay of progressing joint cartilage and bone loss, but do not regenerate these tissues. Surgical procedures are quite unsatisfactory in long-term evaluation and often lead to endoprothetic joint replacement. Present tissue engineering technologies offer new strategies for the treatment of cartilage and bone defects. Here, beyond implantation of cell suspensions, biomaterials combined with tissue-specific cells or mesenchymal stem cells are clinically applied. This review focuses on state-of-the-art and future in situ mesenchymal stem cell-based tissue engineering approaches for joint repair in patients with rheumatic diseases.

Efficient collision detection within deforming spherical sliding contact

Handling the evolving permanent contact of deformable objects leads to a collision detection problem of high computing cost. Situations in which this type of contact happens are becoming more and more present with the increasing complexity of virtual human models, especially for the emerging medical applications. In this context, we propose a novel collision detection approach to deal with situations in which soft structures are in constant but dynamic contact, which is typical of 3D biological elements. Our method proceeds in two stages: First, in a preprocessing stage, a mesh is chosen under certain conditions as a reference mesh and is spherically sampled. In the collision detection stage, the resulting table is exploited for each vertex of the other mesh to obtain, in constant time, its signed distance to the fixed mesh. The two working hypotheses for this approach to succeed are typical of the deforming anatomical systems we target: First, the two meshes retain a layered configuration with respect to a central point and, second, the fixed mesh tangential deformation is bounded by the spherical sampling resolution. Within this context, the proposed approach can handle large relative displacements, reorientations, and deformations of the mobile mesh. We illustrate our method in comparison with other techniques on a biomechanical model of the human hip joint.

Hip joint contact stress as an additional parameter for determining hip dysplasia in adults: comparison with Severin's classification

BACKGROUND

The hip's biomechanical state affects its future development. Therefore, a relevant biomechanical evaluation would be of use in assessing hip dysplasia. Recently, a noninvasive method was developed to determine stress on the weight-bearing area of the hip. The biomechanical assessment was compared with Severin's radiographic classification.

MATERIAL/METHODS

Standard anteroposterior radiographs, taken prior to surgery, of 35 adult patients who were treated for hip dysplasia were analyzed. The AP radiographs of 59 hips were classified into groups 1-3 according to Severin's classification. The geometrical and biomechanical parameters of the hips within each of Severin's groups were compared.

RESULTS

The differences between the mean peak stress on the weight-bearing area of the hip and the peak stress normalized to body weight of both the first and second groups compared with the third group were highly statistically significant. All three of Severin's groups had stress readings ranging from 2 to 4 MPa.

CONCLUSIONS

This study shows that, in general, the biomechanical results corresponded to the results obtained by Severin's evaluation; however, when assessing an individual hip, important differences may be present. Since all of Severin's groups had a stress reading ranging from 2 to 4 MPa, it would be useful to determine the hip's stress distribution when determining treatment.

Effects of movement for estimating the hip joint centre

Determination of the hip joint centre (HJC) using a functional approach requires access to the kinematics of various body postures. The present study aimed to determine the combined impact of the nature of the movement, its type and the number of cycles, on the accuracy of HJC estimation. Kinematics noise was modelled based on the deformation of hip and thigh clusters of seven subjects, while perfect ball-and-socket movements (used as reference) were calculated based on the movements of one of the subjects. The noise added to the reference kinematics allowed the simulation of 27 tests. Errors were defined as the Euclidean distance between the estimated and the reference HJC. A nested ANOVA and a multiple comparison procedures were performed on all errors. A test including 10 cycles of three different types of limited movements (flexion-extension, abduction-adduction and circumduction) yielded the greatest accuracy for estimating HJC (4.0+/-1.3 mm). Combining different types of movements allowed improving the accuracy. Given that noise increases as a function of the range of a motion, limited movements proved to be the most accurate; however, 10 cycles were required to achieve such results. For trials involving a single cycle, a large movement proved more efficient.

Femoroacetabular Impingement

Arthritis of the hip is a common cause of chronic disability. Although traditionally perceived as a condition occurring in the elderly, the detection of early hip arthritis in the young population must not be overlooked. The detection of subtle anatomical abnormalities giving rise to hip pain continues to pose a challenge. Recently, femoroacetabular impingement has been recognized as an etiological risk factor for early arthritis and hip pain in the young adult. The recent advances in imaging technology and the potential for joint-preserving surgical procedures allow early diagnosis and potentially better delivery of care to these patients. It is hence imperative that all those in the musculoskeletal community involved in the management of these young patients be familiar with this relatively common condition.

Validation and usefulness of a computer-assisted cup-positioning system in total hip arthroplasty. A prospective, randomized, controlled study

BACKGROUND

Malpositioning of the acetabular component during total hip arthroplasty increases the risk of dislocation, reduces the range of motion, and can be responsible for early wear and loosening. The purpose of this study was to compare computer-assisted with freehand insertion of the acetabular component.

METHODS

A randomized, controlled, matched prospective study of two groups of thirty patients each was performed. In the first group, cup positioning was assisted by an imageless computer-assisted surgical system based on bone morphing. In the control group, the cup was placed freehand. All of the patients were operated on by the same surgeon through an anterolateral approach. Cup anteversion and abduction angles were measured on three-dimensional computed tomography reconstructions postoperatively for each patient by an independent observer using special cup-evaluation software.

RESULTS

There were sixteen men and fourteen women in each group, and the mean body-mass index was approximately 25 in each group. The computer-assisted procedure took a mean of twelve minutes longer than the freehand procedure. Fifty-seven percent (seventeen) of the thirty cups placed freehand and 20% (six) of the thirty in the computer-assisted group were outside of the defined safe zone (outliers). This difference was significant (p = 0.002). There were no differences between the computer-assisted group and the freehand-placement group with regard to the mean abduction and anteversion angles, but there was a significant heterogeneity of variances, with the lowest variations in the computer-assisted group.

CONCLUSIONS

Use of an imageless navigation system can improve cup positioning in total hip arthroplasty by reducing the percentage of outliers.

Trendelenburg position with hip flexion as a rescue strategy to increase spinal anaesthetic level after spinal block

BACKGROUND

When the level achieved by a spinal anaesthetic is too low to perform surgery, patients are usually placed in the Trendelenburg position. However, cephalad spread of the hyperbaric spinal anaesthetics may be limited by the lumbar lordosis. The Trendelenburg position with the lumbar lordosis flattened by hip flexion was evaluated as a method to extend the analgesic level after the administration of hyperbaric local anaesthetic.

METHODS

When the pinprick block level was lower than T10 5 min after intrathecal injection of hyperbaric bupivacaine (13 mg), patients were recruited to the study and randomly allocated to one of the two positions: the Trendelenburg position with hip flexion (hip flexion group, n = 20) and the Trendelenburg position without hip flexion (control group, n = 20). Each assigned position was maintained for 5 min and then patients were returned to the horizontal supine position. Spinal block level was assessed by pinprick, cold sensation, and modified Bromage scale at intervals for the following 150 min.

RESULTS

The maximum level of pinprick and cold sensory block [median (range)] was higher in the hip flexion group [T4 (T8-C6) and T3 (T6-C2)] compared with the control group [T7 (T12-T4) and T5 (T11-T3)] (P < 0.001). The maximum motor blockade median (range) was not different between the two groups being 3 (3-3) in the hip flexion group vs 3 (0-3) in the control group.

CONCLUSIONS

When the level of spinal anaesthesia is lower than required, flexion of the hips in the Trendelenburg position may be useful as a strategy attempt to increase the level of the block.

Hyaline Cartilage Thickness in Radiographically Normal Cadaveric Hips: Comparison of Spiral CT Arthrographic and Macroscopic Measurements

PURPOSE

To assess spiral multidetector computed tomographic (CT) arthrography for the depiction of cartilage thickness in hips without cartilage loss, with evaluation of anatomic slices as the reference standard.

MATERIALS AND METHODS

Permission to perform imaging studies in cadaveric specimens of individuals who had willed their bodies to science was obtained from the institutional review board. Two independent observers measured the femoral and acetabular hyaline cartilage thickness of 12 radiographically normal cadaveric hips (from six women and five men; age range at death, 52-98 years; mean, 76.5 years) on spiral multidetector CT arthrographic reformations and on coronal anatomic slices. Regions of cartilage loss at gross or histologic examination were excluded. CT arthrographic and anatomic measurements in the coronal plane were compared by using Bland-Altman representation and a paired t test. Differences between mean cartilage thicknesses at the points of measurement were tested by means of analysis of variance. Interobserver and intraobserver reproducibilities were determined.

RESULTS

At CT arthrography, mean cartilage thickness ranged from 0.32 to 2.53 mm on the femoral head and from 0.95 to 3.13 mm on the acetabulum. Observers underestimated cartilage thickness in the coronal plane by 0.30 mm +/- 0.52 (mean +/- standard error) at CT arthrography (P < .001) compared with the anatomic reference standard. Ninety-five percent of the differences between CT arthrography and anatomic values ranged from -1.34 to 0.74 mm. The difference between mean cartilage thicknesses at the different measurement points was significant for coronal spiral multidetector CT arthrography and anatomic measurement of the femoral head and acetabulum and for sagittal and transverse CT arthrography of the femoral head (P < .001). Changes in cartilage thickness from the periphery to the center of the joint ("gradients") were found by means of spiral multidetector CT arthrography and anatomic measurement.

CONCLUSION

Spiral multidetector CT arthrography depicts cartilage thickness gradients in radiographically normal cadaveric hips.

Prediction of the hip joint centre in adults, children, and patients with cerebral palsy based on magnetic resonance imaging

The location of the hip joint centre (HJC) is required for calculations of hip moments, the location and orientation of the femur, and muscle lengths and lever arms. In clinical gait analysis, the HJC is normally estimated using regression equations based on normative data obtained from adult populations. There is limited relevant anthropometric data available for children, despite the fact that clinical gait analysis is predominantly used for the assessment of children with cerebral palsy. In this study, pelvic MRI scans were taken of eight adults (ages 23-40), 14 healthy children (ages 5-13) and 10 children with spastic diplegic cerebral palsy (ages 6-13). Relevant anatomical landmarks were located in the scans, and the HJC location in pelvic coordinates was found by fitting a sphere to points identified on the femoral head. The predictions of three common regression equations for HJC location were compared to those found directly from MRI. Maximum absolute errors of 31 mm were found in adults, 26 mm in children, and 31 mm in the cerebral palsy group. Results from regression analysis and leave-one-out cross-validation techniques on the MRI data suggested that the best predictors of HJC location were: pelvic depth for the antero-posterior direction; pelvic width and leg length for the supero-inferior direction; and pelvic depth and pelvic width for the medio-lateral direction. For single-variable regression, the exclusion of leg length and pelvic depth from the latter two regression equations is proposed. Regression equations could be generalised across adults, children and the cerebral palsy group.

Establishment of peak bone mineral density in Southern Chinese males and its comparisons with other males from different regions of China

Peak bone mineral density (PBMD) is an important determinant of osteoporotic fracture and a precondition for correct diagnosis of osteoporosis. The objective of this study was to establish the reference data of PBMD at the lumber spine and hip in Southern Chinese males. Bone mineral density (BMD) was measured at the lumbar spine and hip (femoral neck, trochanter, intertrochanter, and total) in 1155 Chinese men aged 15-39 years, using dual-energy X-ray absorptiometry (DXA). We utilized a fit curve method to determine the best age range over which to calculate PBMD. Our results indicated that the PBMD was observed at the age range of 18-25 years at the various sites. The mean value and standard deviation of PBMD was 0.753 +/- 0.117, 1.156 +/- 0.148, 0.896 +/- 0.120, 0.989 +/- 0.122, and 0.980 +/- 0.116 g/cm2 at the trochanter, intertrochanter, femoral neck, total hip, and spine, respectively. When the present PBMD reference was compared with the documented PBMD reference of males from other regions of China, we found great difference in standardized PBMD between Changsha males and those from other regions of China. The PBMD for Chinese males in Changsha at the various sites were 3.19%-11.33% lower than that for American Caucasian males. In conclusion, the PBMD at the spine and hip may be used as normal reference data for Southern Chinese males in Changsha instead of documented PBMD from other regions of China and the manufacturer's reference data.

[Evidence-based current concepts in the radiological diagnosis and follow-up of developmental dysplasia of the hip]

This review summarizes some new concepts introduced in the past five years for the radiological diagnosis and follow-up of developmental dysplasia of the hip (DDH). It has been found that the rates of obtaining a standard plain in hip ultrasonography using the Graf method range from 66% to 93% between 1 and 6 years, being greater than 90% between 1 and 3 years. It has been reported that taking the lateral point of acetabular subchondral sclerosis as the measuring point, instead of the lateral point of the acetabular roof, while measuring both the Sharp's angle and the center-edge angle could better define the global hip pathology. To define the pathology more accurately, two alternative methods have been developed to measure the MZ distance that delineates the congruency between the centers of the acetabulum and the femoral head. Measurement of the acetabular anteversion angle on standard anteroposterior pelvis radiography have been defined, that would otherwise be measured only on computed tomography. This angle is measured between the anterior and posterior acetabular wall lines on a plain radiograph, yielding very close values to those obtained by computed tomography. The other method measures the center-trochanter distance in millimeters between the center of the femoral head and the uppermost point of the greater trochanter to evaluate the proximal femur. As the Severin classification proved to be insufficient for the radiographic evaluation of the treatment results in DDH, a new radiographic classification and scoring system has been developed, that numerically evaluates acetabular inclination, shape of the proximal femur, and the relation between the acetabulum and the proximal femur. These evidence based new concepts are considered useful in the clinical practice.

Validation of a low-dose hybrid RSA and fluoroscopy technique: Determination of accuracy, bias and precision

Analyzing skeletal kinematics with radiostereometric analysis (RSA) following corrective orthopedic surgery allows the quantitative comparison of different implant designs. The purpose of this study was to validate a technique for dynamically estimating the relative position and orientation of skeletal segments using RSA and single plane X-ray fluoroscopy. Two micrometer-based in vitro phantom models of the skeletal segments in the hip and knee joints were used. The spatial positions of tantalum markers that were implanted into each skeletal segment were reconstructed using RSA. The position and orientation of each segment were determined in fluoroscopy images by minimizing the difference between the markers measured and projected in the image plane. Accuracy was determined in terms of bias and precision by analyzing the deviation between the applied displacement protocol and measured pose estimates. Measured translational accuracy was less than 100 microm parallel to the image plane and less than 700 microm in the direction orthogonal to the image plane. The measured rotational error was less than 1 degrees . Measured translational and rotational bias was not statistically significant at the 95% level of confidence. The technique allows real-time kinematic skeletal measurements to be performed on human subjects implanted with tantalum markers for quantitatively measuring the motion of normal joints and different implant designs.

T2 mapping of hip articular cartilage in healthy volunteers at 3T: A study of topographic variation

PURPOSE

To perform baseline T2 mapping of the hips of healthy volunteers, focusing on topographic variation, because no detailed study has involved hips. T2 mapping is a quantitative magnetic resonance imaging (MRI) technique that evaluates cartilage matrix components.

MATERIALS AND METHODS

Hips of 12 healthy adults (six men and six women; mean age = 29.5 +/- 4.9 years) were studied with a 3.0-Tesla MRI system. T2 measurement in the oblique-coronal plane used a multi-spin-echo (MSE) sequence. Femoral cartilage was divided into 12 radial sections; acetabular cartilage was divided into six radial sections, and each section was divided into two layers representing the superficial and deep halves of the cartilage. T2 of these sections and layers were measured.

RESULTS

Femoral cartilage T2 was the shortest (-20 degrees to 20 degrees and -10 degrees to 10 degrees, superficial and deep layers), with an increase near the magic angle (54.7 degrees ). Acetabular cartilage T2 in both layers was shorter in the periphery than the other parts, especially at 20 degrees to 30 degrees. There were no significant differences in T2 between right and left hips or between men and women.

CONCLUSION

Topographic variation exists in hip cartilage T2 in young, healthy adults. These findings should be taken into account when T2 mapping is applied to patients with degenerative cartilage.

Assessment of acetabular version by plain radiograph

Radiographs are routinely used to assess the condition and position of the acetabular component. The condition of the cement mantle, or the ingrowth potential, is usually easily recognized. Component-bone position can be assessed by using the method of Ranawat or by measuring abduction angles. Assessment of the version of an acetabular component is often overlooked. This angle or position is important relative to instability, impingement, and motion abnormality. The opening angle or version can be implied from a true acetabular or cross-table lateral radiograph, but good-quality views are often difficult to obtain on an outpatient basis. Using the simple technique presented here, clinicians can assess the acetabular component for version on the basis of plain anteroposterior pelvis and hip radiographs.

Hip arthroscopy: surgical indications

Successful outcomes of hip arthroscopy are most clearly dependent on selecting appropriate patients. The indications are numerous and continue to evolve. These indications are summarized in this report. The anatomic architecture of the hip region imposes unique challenges to performing this procedure. As a surgeon's experience evolves, so will his or her indications for this operation. It is imperative to be knowledgeable about the technique, to exercise care with the procedure, and to be certain that it is being performed for proper reasons.

Repeatability and reproducibility of distraction indices in PennHIP examinations of the hip joint in dogs

Repeatability and reproducibility of Distraction Index (DI) measurements in the PennHIP method were evaluated in 100 dogs. The PennHIP distraction views sent to the PennHIP Analysis Center (PAC) were duplicated, digitalised, and identified with a code, and an adequate computer software was used for DI measurements. One examiner performed two DI measurement sessions, evaluating individually 200 hip joints. The scoring repeatability and reproducibility were estimated calculating the Intraclass Correlation Coefficient (ICC) between the two DI measurement sessions and between the second DI measurement session and the DI in PAC reports, respectively. The ICC for repeatability was 0.97 [95% confidence interval (CI), 0.96 to 0.98], and the ICC for reproducibility was 0.95 (95% CI, 0.93 to 0.96). The results suggest that the DI measurement method described is repeatable and can reproduce the PAC reports with confidence. Distraction indices measured in different PennHIP studies, using this DI measurement method and performed by trained researchers, can be considered interchangeable.

Comparison of digitized and conventional radiographic images for assessment of hip joint conformation in dogs

OBJECTIVE

To determine agreement between assessments of canine hip joint conformation provided by board-certified radiologists after evaluation of digitized and conventional radiographic images.

SAMPLE POPULATION

200 pelvic radiographs previously evaluated by radiologists using the Orthopedic Foundation for Animals standard grading system for canine hip joint conformation.

PROCEDURES

Each of 20 board-certified radiologists evaluated conventional and digitized pelvic radiographs from each of 200 dogs for hip joint conformation. A weighted kappa coefficient and intraclass correlation were used to determine agreement between assessments derived from digitized radiographic images and conventional radiographs and between the original Orthopedic Foundation for Animals conformation ratings and assessments derived from each image format.

RESULTS

Overall, agreement between assessments derived from the digitized images and conventional radiographs was good, with all but 1 radiologist attaining a weighted kappa coefficient > 0.61. Intraclass correlation for each radiologist ranged from 0.75 to 0.98 (95% confidence interval, 0.67 to 0.984). On comparison of conformation assessments, 95.7% of those derived from conventional radiographs and digitized images were within 1 grade. On comparison of digitized radiographic conformation assessments and conformation ratings, 94.2% were within 1 grade. On comparison of conventional radiographic conformation assessments and conformation ratings, 92.3% were within 1 grade.

CONCLUSIONS AND CLINICAL RELEVANCE

The use of digitized radiographic images does not appear to impact the radiographic assessments of canine hip joint conformation made by consultant radiologists. Compared with conventional radiographs, the use of digitized radiographic images decreases storage space requirements and enables more rapid reporting of assessment results for individual dogs.

The ischiatic region: normal and MRI anatomy

AIM

The aim of this study was to describe the anatomy correlated to the normal magnetic resonance imaging (MRI) images of the proximal thigh region and the ischial tuberosity.

METHODS

MRI coronal and axial sequences were obtained from 20 asymptomatic volunteers (10 male and 10 female) aged 20 to 38 years (mean age: 28 years), and then they were compared with 2 anatomical dissections and 7 cryosections of 6 cadaver thighs.

RESULTS

The anatomical specimens were directly correlated with MRI scans. From the comparison it could be seen how the axial MRI sequences well outlined the sciatic nerve, usually observed oval in shape with moderate signal intensity, and thus easily detectable from other surrounding organs. Other structures were also identified by axial images: the ischial tuberosity, the proximal origin of the hamstring muscles arising from the ischium and the related bursae, the gluteus maximus and its bursa, the quadratus femoris and its inconstant bursa, a triangular adipose body and vessels. Coronal scans also showed well the hamstring muscles, both in length and thickness.

CONCLUSIONS

Both MRI images and cadaver dissections showed the ischial tuberosity as an interesting intersection area that could be delimited as follows: on the dorsal border the gluteus maximus and its bursa, on the dorso-medial side the hamstring muscle origin, and on the antero-lateral side the quadratus femoris muscle with its inconstant bursa and the ischial tuberosity. These anatomical and MRI descriptions are very useful to give a contribution to the right explanation of sciatic symptoms caused by those sports specifically overloading the hamstring muscles. Frequently, in fact, in these athletes a sciatic syndrome arise drawing the physician's attention to the lumbosacral joint or to the sciatic nerve course near the piriformis muscle. Another very important site where the sciatic symptoms can rise, indeed, could also be found in the hamstring muscle region, where the nerve run under the gluteus maximus beside the ischiatic bone. Athletes who manifest notorious muscle overload in this anatomical region usually show sciatic pain symptoms that are not to be related with pathologies of the lumbosacral junction nor to relationships of the sciatic nerve with the piriformis muscle but rather to relationships that this nerve acquires with either gluteal muscles as well as with muscles of the underneath ischiatic region.

An optimized protocol for hip joint centre determination using the functional method

The functional method identifies the hip joint centre (HJC) as the centre of rotation of the femur relative to the pelvis during an ad hoc movement normally recorded using stereophotogrammetry. This method may be used for the direct determination of subject-specific HJC coordinates or for creating a database from which regression equations may be derived that allow for the prediction of those coordinates. In order to contribute to the optimization of the functional method, the effects of the following factors were investigated: the algorithm used to estimate the HJC coordinates from marker coordinates, the type and amplitude of the movement of the femur relative to the pelvis, marker cluster location and dimensions, and the number of data samples. This was done using a simulation approach which, in turn, was validated using experiments made on a physical analogue of the pelvis and femur system. The algorithms used in the present context were classified and, in some instances, modified in order to optimize both accuracy and computation time, and submitted to a comparative evaluation. The type of movement that allowed for the most accurate results consisted of several flexion-extension/abduction-adduction movements performed on vertical planes of different orientations, followed by a circumduction movement. The accuracy of the HJC estimate improved, with an increasing rate, as a function of the amplitude of these movements. A sharp improvement was found as the number of the photogrammetric data samples used to describe the movement increased up to 500. For optimal performance with the recommended algorithms, markers were best located as far as possible from each other and with their centroid as close as possible to the HJC. By optimizing the analytical and experimental protocol, HJC location error not caused by soft tissue artefacts may be reduced by a factor of ten with a maximal expected value for such error of approximately 1mm.

Propagation of the hip joint centre location error to the estimate of femur vs pelvis orientation using a constrained or an unconstrained approach

To estimate hip joint angles during selected motor tasks using stereophotogrammetric data, it is necessary to determine the hip joint centre position. The question is whether the errors affecting that determination propagate less to the angles estimates when a three degrees of freedom (DOFs) constraint (spherical hinge) is used between femur and pelvis, rather than when the two bones are assumed to be unconstrained (six DOFs). An analytical relationship between the hip joint centre location error and the joint angle error was obtained limited to the planar case. In the 3-D case, a similar relationship was obtained using a simulation approach based on experimental data. The joint angle patterns resulted in a larger distortion using a constrained approach, especially when wider rotations occur. The range of motion of the hip flexion-extension, obtained simulating different location errors and without taking into account soft tissue artefacts, varied approximately 7 deg using a constrained approach and up to 1 deg when calculated with an unconstrained approach. Thus, the unconstrained approach should be preferred even though its estimated three linear DOFs most unlikely carry meaningful information.

Influence of anthropometric parameters and bone size on bone mineral density using volumetric quantitative computed tomography and dual X-ray absorptiometry at the hip

PURPOSE

To evaluate the influence of anthropometric parameters (age, height, and weight) and bone size on bone mineral density (BMD) using volumetric quantitative computed tomography (QCT) and dual X-ray absorptiometry (DXA) in a group of elderly women.

MATERIAL AND METHODS

BMD values were obtained with DXA and QCT at the spine and hip in a cohort of 84 elderly women (mean age 73 +/- 6 years). QCT measures included trabecular, integral, and cortical BMD assessed at the hip and spine as well as cross-sectional areas of the mid-vertebrae and proximal femora. Spinal integral and femoral neck BMD measures were well matched to the regions of bone quantified on anteroposterior (AP) spine DXA and the femoral neck region of hip DXA.

RESULTS

When QCT parameters were linearly regressed against body height and weight, only the relationships with weight were found to be statistically significant. Except for cortical BMD at the femoral neck, all BMD and geometric parameters measured from both DXA and QCT showed statistically significant associations with body weight (r2 = 0.4, 0.0001 < P < 0.02). The strongest associations with weight were found for DXA Neck (DXA_NECK) and DXA lumbar spine (DXA_LSP) (r2 = 0.4, P < 0.0001).

CONCLUSION

The relationship of DXA BMD is stronger than QCT BMD with body weight and it encompasses the response of both bone size and density to increasing body mass.

Experimental verification of a computational technique for determining ground reactions in human bipedal stance

We have developed a three-dimensional (3D) biomechanical model of human standing that enables us to study the mechanisms of posture and balance simultaneously in various directions in space. Since the two feet are on the ground, the system defines a kinematically closed-chain which has redundancy problems that cannot be resolved using the laws of mechanics alone. We have developed a computational (optimization) technique that avoids the problems with the closed-chain formulation thus giving users of such models the ability to make predictions of joint moments, and potentially, muscle activations using more sophisticated musculoskeletal models. This paper describes the experimental verification of the computational technique that is used to estimate the ground reaction vector acting on an unconstrained foot while the other foot is attached to the ground, thus allowing human bipedal standing to be analyzed as an open-chain system. The computational approach was verified in terms of its ability to predict lower extremity joint moments derived from inverse dynamic simulations performed on data acquired from four able-bodied volunteers standing in various postures on force platforms. Sensitivity analyses performed with model simulations indicated which ground reaction force (GRF) and center of pressure (COP) components were most critical for providing better estimates of the joint moments. Overall, the joint moments predicted by the optimization approach are strongly correlated with the joint moments computed using the experimentally measured GRF and COP (0.78 < or = r(2) < or = 0.99,median,0.96) with a best-fit that was not statistically different from a straight line with unity slope (experimental=computational results) for postures of the four subjects examined. These results indicate that this model-based technique can be relied upon to predict reasonable and consistent estimates of the joint moments using the predicted GRF and COP for most standing postures.

The painful hip: new concepts

Hip pain is a common condition, and the work-up often includes imaging. This article reviews the normal MR anatomy of the hip and the imaging findings of internal derangements, snapping hip, and femoral acetabular impingement. We will describe the role of MR arthrography in evaluating the patient with suspected labral and articular cartilage abnormalities, as well as the pitfalls in interpretation. We will review the causes of a snapping hip, and the role of sonography in evaluating and guiding treatment of the snapping iliopsoas tendon. We will also review the radiographic and MRI signs of femoroacetabular impingement (FAI), a cause of early degenerative joint disease and hip pain.

Ultrasound imaging for the rheumatologist III. Ultrasonography of the hip

Ultrasonography (US) is a reliable and useful diagnostic tool for the assessment of hip pathology. It depicts changes within the coxo-femoral joint (synovitis, erosions, osteophytes) and in the adjacent peri-articular tissues (calcifications, tendonitis, enthesitis, bursitis) in many rheumatic diseases (rheumatoid arthritis, spondyloarthritis, osteoarthritis, polymyalgia rheumatica ) and in some orthopaedic disorders (septic arthritis, trauma, abscess, painful hip after arthroplasty). It is commonly used both in adults and in children. In the assessment of hip joint pathology, US exerts considerable diagnostic supremacy over physical examination. In fact, by virtue of its size and position, reliable physical examination of the hip is often difficult thus making US particularly useful as a bedside tool for the evaluation of a painful hip. Hip US has also proven to be of great practical benefit when performing aspiration and injection within the joint and in the periarticular soft tissues. The relatively limited acoustic windows available to the US beam is the principal limitation to hip US thereby making detailed examination of some important structures impossible together with the interpretation of power Doppler signal sometimes unreliable. In addition, the deep location of the hip can confer further problems to US scanning in obese or particularly muscular subjects.

Common misconceptions of normal hip joint relations on pelvic radiographs

This study defines normal bilateral variations in offset and hip center location on pelvic radiographs. The relationship of the femoral head center to the tip of the greater trochanter and that of offset to medullary canal diameter are also defined. Measurements of the offset, hip center location, height of the tip of the greater trochanter from the femoral head center, and medullary canal diameter were carried out on 100 normal pelvic radiographs. The offset of one hip was found to predict that of the contralateral hip to within 4.62 mm with 95% confidence. Their hip center locations differed by 6.3 mm. The tip of the greater trochanter was, on average, 8 mm higher than the femoral head center. Although offset generally increased with an increase in medullary canal diameter, frequent discrepancies occurred in their relationship.

Developmental dysplasia of the hip: nursing implications and anticipatory guidance for parents

Developmental dysplasia of the hip (DDH) is a comprehensive term used to describe an abnormal relationship between the femoral head and the acetabulum. Developmental dysplasia of the hip includes a very wide spectrum of abnormality from a frank dislocation (very unstable) to a stable hip with a slightly shallow acetabulum. As many of these findings may not be present at birth, the term developmental more accurately reflects the biologic features than does the term congenital. Despite the recent increased awareness of DDH and the importance of thorough screening programs, hip dysplasia continues to be a frequently missed diagnosis in pediatrics. Earlier detection and diagnosis of DDH is associated with a much more successful and less invasive outcome.

Changes in Bone Microarchitecture and Bone Mineral Density following Experimental Osteonecrosis of the Hip in Rabbits

BACKGROUND

Osteonecrosis of the femoral head is a common disorder which can lead to hip joint destruction usually necessitating total hip replacement.

METHODS

Quantitative micro-computed tomography, digital radiography and histology were used to characterize changes in bone microarchitecture and bone mineral density during the repair of the osteonecrotic femoral head as well as during the development of secondary osteoarthritis in the ipsilateral acetabulum. Osteonecrosis was induced surgically in 17 adult, male rabbits and the contralateral side was used as control.

RESULTS

At 4 weeks no changes in microarchitecture in the femoral head nor in the acetabulum were found. At 6 months the repair process led to an increase in bone mass in the trabecular region of the femoral head. However, a decrease in volumetric bone mineral density and an increase in apparent porosity were seen in the compact subchondral and cortical region of the osteonecrotic femoral head. At 6 months the subchondral bone of the osteoarthritic ipsilateral acetabulum was thicker, but had a lower volumetric bone mineral density and a higher apparent porosity.

CONCLUSION

Resorption of necrotic compact bone may weaken the structural properties of the femoral head. Moreover, remodeling and resorption of subchondral bone may play a critical role in the disease process of osteoarthritis.

High Field (4.7T) Magnetic Resonance Imaging of Feline Hip Joints

Magnetic resonance imaging (MRI) is a non-invasive technique widely used to investigate degenerative joint disease (DJD). In this study, we obtained magnetic resonance images of feline hip joints, using a high magnetic field MRI unit (4.7 tesla) with proton density (PD)-weighted and T2-weighted fast spin-echo (FSE). PD-weighted FSE provided detailed anatomical images of feline hip joints with superb depiction of subchondral bones of the femoral head and acetabulum. Articular cartilage (AC) was also visualized with PD-weighted and T2-weighted FSE; however, mild AC lesions noted on gross examination were not detectable with these sequences.

Natural course of the minimally symptomatic nonoperated hip in patients with bilateral hip dysplasia treated with contralateral rotational acetabular osteotomy

BACKGROUND

The purpose of this study was to investigate the natural course of the minimally symptomatic nonoperated hip in patients with pre-osteoarthritis or early osteoarthritis in bilaterally dysplastic hips.

METHODS

The material consisted of 61 patients with bilaterally dysplastic hips who underwent rotational acetabular osteotomy in their symptomatic hip and nonoperative treatment in their asymptomatic or minimally symptomatic hip. The average follow-up was 10.1 years (range 7.0-15.6 years), and the average age at the time of surgery was 38.2 years (range 20-58 years). All patients were divided into two groups by joint congruity of the nonoperated hip at surgery with rotational acetabular osteotomy.

RESULTS

On radiographic assessment, 1 of the 35 pre-osteoarthritis hips had developed early osteoarthritis, and 6 of the 26 early osteoarthritis hips had progressed to advanced osteoarthritis. The Kaplan-Meier survivorship analysis for the whole group of nonoperated hips, with radiographic progression of osteoarthritis as the endpoint, predicted a 10-year survival rate of 83.7% (95% confidence interval 70%-98%). Significant differences were observed in the radiographic stage (pre- and early osteoarthritis group, P=0.015) and joint congruity (good and fair group, P=0.005).

CONCLUSIONS

If the contralateral nonoperated hip has good joint congruity, minimal symptoms, and no or little radiographic change in patients with pre- or early osteoarthritis and bilateral acetabular dysplasia, the probability of radiographic progression is low.

MR Imaging of the Normal Hip

This article reviews the complex normal anatomy of the hip joint and its surrounding structures on MR imaging, including MR arthrography.Thorough knowledge of the normal appearance of the marrow and osseous and articular anatomy as well as the ligaments, tendons, and surrounding muscles of the hip is essential for imaging diagnosis.

MR Imaging of the Hip Abductors: Normal Anatomy and Commonly Encountered Pathology at the Greater Trochanter

Lateral hip pain, also referred to as the greater trochanteric pain syndrome, is a commonly encountered clinical problem with a broad set of differential considerations. A detailed understanding of the osseous anatomy of the greater trochanter, the correspond-ing attachment sites of the abductors of the hip, and the spatial and anatomic relations of their corresponding bursae is crucial to the accurate characterization and localization of pathologic findings in these structures. This article reviews the anatomy and pathologic findings of the osseous and soft tissue anatomy of the greater trochanter.

Lifecourse study of bone health at age 49-51 years: the Newcastle thousand families cohort study

OBJECTIVE

To quantify the direct and indirect effects of fetal (position in family, weight, and social class at birth), childhood (breast feeding, growth, infections, and social class in childhood, age at menarche), and adult life (social class, alcohol consumption, smoking, diet, reproductive history, exercise, hormone replacement therapy use), and adult size (height, weight) on bone health at age 49-51 years, as measured by bone mineral density, total scanned bone area of the hip and lumbar spine, and femoral neck shaft angle.

DESIGN

Follow up study of the Newcastle thousand families birth cohort established in 1947.

PARTICIPANTS

171 men and 218 women who attended for dual energy x ray absorptiometry scanning.

MAIN RESULTS

Fetal life explained around 6% of variation in adult bone mineral density for men, but accounted for less than 1% for women. Adult lifestyle, including effects mediated through adult weight accounted for over 10% of variation in density for men and around 6% for women. Almost half of variation in bone area for men was explained by early life. However, most of this was mediated through achieved adult height and weight. In women, less than 5% of variation in bone area was accounted for by early life, after adjusting for adult size. Most of the variation in each of the indicators for both sexes was contributed either directly or indirectly by adult lifestyle and achieved adult height and weight.

CONCLUSIONS

The effect of fetal life on bone health in adulthood seems to be mediated through achieved adult height.

An Invariant Guiding Stair Descent by Young and Old Adults

In this study the author compared the perception-action capability of young and old adults (respectively, mean age 22 and 62 years old) when descending stairs and examined the relevant task constraints that guide the action. It was found that old adults selected and descended stairs that were significantly lower than young adults and showed less hip joint flexibility. However, the performance parameter, defined as the ratio between the height of the stair and the distance taken by the stepping foot to the top edge of the stair, was invariant for both groups. Thus, despite different ability levels, young and old adults are constrained by the same perception-action invariant for guiding the act of stair descent.

Labral Injuries of the Hip: A Review of Diagnosis and Management

OBJECTIVE

To report the current knowledge of the diagnosis and treatment of acetabular labral tears.

METHODS

A search of the MEDLINE, CINAHL, and Science Direct indexing systems (1966 to September 2004) was conducted using the following key indexing terms: labrum, labral, hip, acetabulum, injury, and treatment. One hundred eighty-six publications were sourced using this methodology and were considered in this review. The literature was sorted according to publication date and relevance.

RESULTS

There is a small amount of literature on the topic of labral lesions. This is particularly true of the use of conservative (manual therapy) methods for the treatment of labral lesions. The literature on surgical diagnosis and management is more mature; however, longer-term follow-up studies are required to conclusively show the benefit of surgical intervention.

CONCLUSIONS

Early diagnosis is important as labral tears may be linked to the progression of hip osteoarthritis. Initial treatment consisting of partial weight-bearing may respond if initiated early. Arthroscopy currently represents the gold standard in both the diagnosis and treatment of labral tears. Future research must investigate the long-term outcomes of partial labrectomy, as well as the efficacy of conservative approaches to care.