Developmental Dysplasia Of The Hip Hip Research Articles

A New Method to Predict Postoperative Stem Anteversion in Total Hip Arthroplasty for Developmental Dysplasia of the Hip.

Preoperative evaluation of femoral anteversion to predict postoperative stem anteversion aids the selection of an appropriate prosthesis and optimizes the combined anteversion in total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH). The conventional prediction methods are based on the femoral anteversion measurement at the location of the femoral head and/or neck. However, varied differences between femoral anteversion and postoperative stem anteversion were demonstrated. This study investigated the predictive role of a new method based on the principle of sagittal three-point fixation. From January 2017 to December 2018, a total of 133 DDH hips that underwent THA were retrospectively analyzed. There were 76 Crowe type I, 27 type II, and 30 type III hips. The single-wedge stem was used in 49 hips, and the double-wedge stem was used in 84 hips. Preoperative native femoral anteversion at the femoral head-neck junction, anterior cortex anteversion at 2 levels of the lesser trochanter, posterior cortex anteversion at 5 levels of the femoral neck, and postoperative stem anteversion were measured using two-dimensional computed tomography. Predictive anteversion by the new method was calculated as the average anteversion formed by the anterior cortex at the lesser trochanter and the posterior cortex at the femoral neck. For hips with different neck heights, different Crowe types, different stem types, or different femoral anteversions, native femoral anteversion showed widely varied differences and correlations with stem anteversion, with differences ranging from -1.27 ± 8.33° to -13.67 ± 9.47° and correlations ranging from 0.122 (p = 0.705, no correlation) to 0.813. Predictive anteversion formed by the anterior cortex at the lesser trochanter proximal base and posterior cortex 10 mm above the lesser trochanter proximal base showed no significant difference with stem anteversion, with less varied differences (0.92 ± 7.52°) and good to excellent correlations (r = 0.826). Adopting our new method, predictive anteversion, measured as the average anteversion of the anterior cortex at the lesser trochanter proximal base and posterior cortex 10 mm above the lesser trochanter proximal base, predicted postoperative stem anteversion more reliably than native femoral anteversion.

Diagnosis of Developmental Dysplasia of the Hip by Ultrasound Imaging Using Deep Learning.

A timely diagnosis of developmental dysplasia of the hip (DDH) is important for satisfactory clinical outcomes. Ultrasonography is a useful tool for DDH screening; however, it is technically demanding. We hypothesized that deep learning could assist in the diagnosis of DDH. In this study, several deep-learning models were assessed to diagnose DDH on ultrasonograms. This study aimed to evaluate the accuracy of diagnoses made by artificial intelligence (AI) using deep learning on ultrasound images of DDH. Infants who were up to 6 months old with suspected DDH were included. DDH diagnosis using ultrasonography was performed according to the Graf classification. Data on 60 infants (64 hips) with DDH and 131 healthy infants (262 hips) obtained from 2016 to 2021 were retrospectively reviewed. For deep learning, a MATLAB deep learning toolbox (MathWorks, Natick, MA, US) was used, and 80% of the images were used as training data, with the rest as validation data. Training images were augmented to increase data variation. In addition, 214 ultrasound images were used as test data to evaluate the AI's accuracy. Pre-trained models (SqueezeNet, MobileNet_v2, and EfficientNet) were used for transfer learning. Model accuracy was evaluated using a confusion matrix. The region of interest of each model was visualized using gradient-weighted class activation mapping (Grad-CAM), occlusion sensitivity, and image LIME. The best scores for accuracy, precision, recall, and F-measure were all 1.0 in each model. In DDH hips, the region of interest for deep learning models was the area lateral to the femoral head, including the labrum and joint capsule. However, for normal hips, the models highlighted the medial and proximal areas where the lower margin of the os ilium and the normal femoral head exist. Ultrasound imaging with deep learning can assess DDH with high accuracy. This system could be refined for a convenient and accurate diagnosis of DDH. Level-Ⅳ.

Diagnostic accuracy of a deep learning model using YOLOv5 for detecting developmental dysplasia of the hip on radiography images

Developmental dysplasia of the hip (DDH) is a cluster of hip development disorders and one of the most common hip diseases in infants. Hip radiography is a convenient diagnostic tool for DDH, but its diagnostic accuracy is dependent on the interpreter’s level of experience. The aim of this study was to develop a deep learning model for detecting DDH. Patients younger than 12 months who underwent hip radiography between June 2009 and November 2021 were selected. Using their radiography images, transfer learning was performed to develop a deep learning model using the “You Only Look Once” v5 (YOLOv5) and single shot multi-box detector (SSD). A total of 305 anteroposterior hip radiography images (205 normal and 100 DDH hip images) were collected. Of these, 30 normal and 17 DDH hip images were used as the test dataset. The sensitivity and the specificity of our best YOLOv5 model (YOLOv5l) were 0.94 (95% confidence interval [CI] 0.73–1.00) and 0.96 (95% CI 0.89–0.99), respectively. This model also outperformed the SSD model. This is the first study to establish a model for detecting DDH using YOLOv5. Our deep learning model provides good diagnostic performance for DDH. We believe our model is a useful diagnostic assistant tool.

Mid-term low back pain improvement after total hip arthroplasty in 306 patients with developmental dysplasia of the hip

BackgroundLow back pain (LBP) from hip and spinal disorders has been one of the main reasons for visiting physicians in patients with developmental dysplasia of the hip (DDH). It is essential to identify the LBP improvement among all grades of DDH patients treated with total hip arthroplasty (THA) at 5-year follow-up.MethodsThe study included 407 hips of 306 patients (38 males, 268 females) who underwent THA between July 2007 and December 2016. There were 65 hips in Crowe I, 61 hips in Crowe II, 69 hips in Crowe III, and 212 hips in Crowe IV. One hundred and fourteen hips received subtrochanteric shortening. Patients included 101 bilateral THA (BTHA) and 205 unilateral THA (UTHA). The evaluation was performed through Back Pain Function Scale (BPFS), Harris hip score, Visual Analogue Scale (VAS), operative data and radiographic examinations.ResultsThe BPFS in patients of unilateral Crowe III and IV relieved significantly more (p < 0.05). However, the BPFS in patients with bilateral symmetry DDH hips relieved significantly less than other groups of DDH hips (p < 0.05). Harris in hips of Crowe II improved significantly more (p < 0.05). The VAS in hips of Crowe II and III improved significantly more (p < 0.05). The unilateral THA surgical time, blood loss, blood transfusion, and osteotomy number and length in Crowe IV were significantly more (p < 0.05).ConclusionTHA is reliable to relieve LBP in DDH patients of unilateral Crowe III and IV; however, in patients with unilateral Crowe I, Crowe II, and bilateral DDH hips, the LBP improvements were limited. This should assist shared decision-making between orthopedic surgeons and patients.Level of evidenceTherapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Active monitoring versus immediate abduction as treatment of stable developmental dysplasia of the hip: a systematic review of the literature

ObjectivesThis systematic review aims to compare the effects of active monitoring and abduction treatment on the Graf alpha angle, Acetabular Index (AI) and femoral head coverage in infants with stable...

Acetabular volume and femoral coverage change following Dega-like osteotomy in treatment of developmental dysplasia of the hip.

Although Dega's acetabuloplasty has become a commonly used osteotomy, there is still an ongoing debate regarding its impact on the volume and depth of the acetabulum. The purpose of our study was to assess the postoperative images of the transverse acetabular plane and version obtained from developmental dysplasia of the hip (DDH) patients after a modified Dega osteotomy. We performed a retrospective study of the morphologic indices obtained from the pelvic X-rays and computer tomography (CT) scans of patients with DDH, who were operated in our institution between July 2005 and October 2013, using the modified Dega osteotomy. Preoperative and postoperative pelvic X-rays were used to measure the acetabular index and the acetabular (ACM) angle. The postoperative CT scans were used to measure the acetabular anteversion angle (AAA), acetabular depth and depth of acetabular coverage [total acetabular index (TAI)]. The contralateral unaffected hips served as control. The postoperative acetabular indices and ACMs showed a significant improvement, with near-normal values measured 1 year after the surgery. Comparing the CT scan parameters (AAA, TAI and the depth of acetabulum) showed that TAI and the depth of acetabulum were not significantly different between the groups (TAI: P = 0.423; depth of acetabulum: P = 0.132), whereas AAA comparison implied a slight advantage of the DDH hips (17.6° DDH vs. 13.3° contralateral, P = 0.001). On the basis of images set of acetabular morphometric parameters, our study substantiates previous reports on an increase of acetabular volume and a significant improvement of femoral head coverage for patients with DDH who underwent Dega acetabuloplasty. Level of evidence: Level III - retrospective comparative study.

The Three-Dimensional Morphology of Femoral Medullary Cavity in the Developmental Dysplasia of the Hip.

ObjectiveThis study aimed to assess the morphology of the femoral medullary canal in subjects with developmental dysplasia of the hip (DDH) with the intent of improving the design of femoral stems in total hip arthroplasty.MethodsComputed tomography images of 56 DDH hips, which were classified into Crowe I to Crowe IV, and 30 normal hips were collected and used to reconstruct three-dimensional morphology of the femoral medullary cavity. Images of twenty-one cross sections were taken from 20 mm above the apex of the lesser trochanter to the isthmus. The morphology of femoral cavity was evaluated on each cross section for the longest canal diameter, the femoral medullary torsion angle (FMTA), and the femoral medullary roundness index (FMRI).ResultsThe Crowe IV group displayed the narrowest medullary canal in the region superior to the end of the lesser trochanter, but then gradually aligned with the medullary diameter of the other groups down to the isthmus. The FMTA along the femoral cavity increased with the severity of DDH, but the rate of variation of FMTA along the femoral canal was consistent in the DDH groups. The DDH hips generally showed a larger FMRI than the normal hips, indicating more elliptical shapes.ConclusionA femoral stem with a cone shape in the proximal femur and a cylindrical shape for the remainder down to the isthmus may benefit the subjects with severe DDH. This design could protect bone, recover excessive femoral anteversion and facilitate the implantation in the narrow medullary canal.

Robotic-Assisted Total Hip Arthroplasty in Patients Who Have Developmental Hip Dysplasia

Introduction: Total hip arthroplasty (THA) in the setting of developmental dysplasia of the hip (DDH) presents more inherent complexities than routine primary THA for osteoarthritis. These include acetabular bone deficiency, limb length discrepancy (LLD), and abnormal femoral anteversion. Three-dimensional planning and robot-assisted (RA) bone preparation may simplify these complex procedures and make them more reproducible. The purpose of this study was to evaluate radiographic and clinical outcomes in a cohort of patients who had DDH and underwent an RA THA. Materials and Methods: We retrospectively analyzed 26 DDH patients who underwent RA THA by a single surgeon between 2013 and 2019. Their mean age was 54 years (range, 29 to 72 years) and mean follow up was approximately two years. Medical records were reviewed for demographics, clinical scores, Crowe classifications, and complications. There were thirteen Crowe I and seven Crowe II DDH hips, who were routinely managed with primary cementless implants. Two patients who had Crowe III and four patients who had Crowe IV DDH were also identified. All hips were reconstructed with cementless hemispherical acetabular components with or without the use of screws, but no acetabular augments or bulk allografts. Implants allowing control of femoral anteversion were selected in 23.1% of cases, including all six cases with Crowe III or IV dysplasia, and the need for these implants was uniformly identified using preoperative information about femoral version provided by the three-dimensional planning software. No patient was managed with a shortening femoral osteotomy. Postoperative radiographs were examined for LLD, center of rotation (COR), cup position (inclination and anteversion), and component osseous-integration. Results: Mean radiographic LLD was 1.7mm (range, -9 to +14) in patients who had Crowe I DDH, and there was no clinical LLDs greater than 5mm observed. Although patients who had Crowe II and greater DDH had a mean radiographic LLD of -11.6mm (range, -26 to +2.2), again no clinical LLD greater than 5mm was observed other than one patient who had bilateral Crowe II DDH in whom 10mm of clinical lengthening was accepted at the index arthroplasty with the plan to match lengths when her contralateral THA was performed. There were no cases of dislocation or acetabular fixation failure. One patient who had a femoral deformity and an intra-osseous blade plate from a prior femoral osteotomy suffered a failure of femoral osseous-integration, resulting in revision. A 32-point increase in mean modified Harris Hip Score (mHHS) was found (p=0.002), from 48 points preoperatively to 80 points postoperatively. Discussion: RA THA provides an excellent option for the arthroplasty surgeon to both preoperatively localize and characterize the acetabular deficiency, while providing a targeted, optimal, and secure placement of the components intraoperatively. Our results suggest favorable outcomes when compared to previous research on manual THA in DDH. Further studies, including comparative analyses, could discern possible advantages over traditional THA without robotic assistance in DDH. Conclusion: Total hip arthroplasty (THA) in the setting of developmental dysplasia presents more inherent complexities than routine primary THA. Robotic-assisted THA may simplify these complex procedures.

Effect of patient-specific instrument on lowering threshold for junior physicians to perform total hip arthroplasty on developmental dysplasia of the hip patients.

To create a patient-specific instrument (PSI) in lowering the surgical experience requirement for junior physicians to perform total hip arthroplasty (THA) on developmental dysplasia of the hip (DDH) patients. Combined with rapid prototyping technology, we created a PSI and established DDH hip model in vitro. We enrolled 48 junior physicians and randomly assigned them into two groups. After creation of the PSI, they performed simulated THA surgery on a full-scale hip model with or without PSI on DDH models. The planned prothesis orientation, post-operative prothesis orientation, and surgery time were recorded. The final cup inclination was 42.0 ± 0.8° in PSI group and 37.8 ± 2.0° in control group, while final cup anteversion was 16.0 ± 0.7° in PSI group and 24.7 ± 3.5° in control group. The △inclination in PSI group was smaller than that in control group (4.2 ± 0.5° vs 9.5 ± 1.4°, P < 0.01), so does △inclination (2.9 ± 0.4° in PSI group vs 15.2 ± 2.5° in control group, P < 0.01). The outlier percent was 8.3% in PSI group and 70.8% in control group (P < 0.01). At the same time, the PSI group did not prolong the operation time (P = 0.551). The PSI can greatly increase the accuracy of placing the cup orientation and lower the threshold for junior physicians to perform THA on DDH patients. It could be a training tool for them to increase their THA surgical skills.

Impact of femoroacetabular impingement and dysplasia of the hip on hip joint sphericity.

This paper presents a parametric investigation into the effect of femoroacetabular impingement (FAI) and developmental dysplasia of the hip (DDH) on the sphericity of the femoral supra-equatorial region and acetabulum. Radiographic parameters from x-rays, sphericity calculations and visualisation and joint contact area and pressure from FE models of 10 DDH, FAI and normal hips were analysed and compared both within and between hip groups. The sphericity of the acetabulum and femoral head of both the DDH and FAI groups was found to be less than that for normal hips but the variation in sphericity was greater (range 2.4% for normal hips, compared to 3.3% and 3.1% for the FAI and DDH groups respectively). For the DDH group, femoral head sphericity was found to correlate strongly with 2 of the radiographic parameters used to diagnose the condition, CE angle and Sharp angle. For FAI and DDH hips peak contact pressure primarily occurred in Ilizaliturri Zone 2 (anterior-superior region) in the acetabulum and femoral head which corresponded with increased aspherity in this region compared to the normal hip group. These findings correlate with loading and damage patterns reported in the literature. Additionally, our analysis identified a protrusion of bone in Ilizaliturri Zones 1 and 6 (anterior-inferior region) of the acetabulum of a subgroup of FAI hips, whose existence was confirmed using a full-scale hip model fabricated using a 3D printer, which we believe could result in cartilage damage. We postulate that such protrusions could potentially explain residual symptoms and unaddressed structural deformity in patients who have undergone FAI surgery.

The application of 3D printed customized porous tantalum acetabular patch for adult DDH hip reconstruction

Objective To explore the feasibility, safety and efficacy of customized porous tantalum acetabular patch made by three-dimensional (3D) printing technique in treating adult developmental dysplasia of the hip (DDH). Methods Eight adult patients with CroweⅠtype DDH (2 men and 6 women, with a mean age of 43.75±7.81 years, range 33-58 years) who were treated with 3D printed customized porous tantalum acetabular patch hip reconstruction from January 2017 to September 2017 were included. The 3D printing technique was used for reconstructing and designing the optimal acetabular patch for the personalized hip joint of each patient. The acetabular patch was subjected to porous processing and finite element analysis until the biomechanical requirements were met. The 3D printing of porous tantalum acetabular patch and post-processing was subsequently performed. The acetabular patch was implanted through the anterior approach of the hip joint. The operative duration, intraoperative blood loss and complications were recorded. All the included patients were followed up at 1.5, 3 and 6 months postoperatively. Pain was assessed using the visual analog scale (VAS), and the hip joint function was evaluated using the Harris score and gait analysis. The patients underwent anterior-posterior radiography and 3D computed tomography of the hip joint aiming to observe the position of the acetabular patch and osteoarthritis progression. Results The mean operative duration was 1.13±0.23 h, and the mean blood loss was 114.17±41.22 ml. All patients were followed up for 6 to 12 months, with an average of 8.2 months. The mean lateral central-edge angle and anterior central-edge angle ranged from 9.83°±5.34° preoperatively to 32.67°±2.53° postoperatively and from 3.83°±2.79° preoperatively to 21.67°±1.87° postoperatively, respectively. The rate of acetabular coverage increased from 57.33%±7.97% preoperatively to 87.33%±4.56% postoperatively. The VAS and Harris scores ranged from 2.92±0.79 preoperatively to 0.83±0.72 postoperatively and from 69.67±4.62 preoperatively to 84.25±4.14 postoperatively with statistically significant difference, respectively. The results of gait analysis showed that the step speed, stride, the range of motion of hip and knee were better than that preoperatively. The images suggested a close contact between the tantalum acetabular patch and the iliac bone without loosening and progress of osteoarthritis in hip joint. Conclusion 3D printed customized porous tantalum acetabular patch could reconstruct the defect of acetabular, increase the coverage, and delay the progress of osteoarthritis of the hip joint. This method could reduce the difficulty of hip reconstruction, and the patients could obtain better joint function at the early stage. Key words: Bone diseases, development; Imaging, three-dimensional; Tantalum; Porosity

Femoral nerve palsy is a mythic complication of Pavlik harness treatment for developmental dysplasia of the hip

Introduction Femoral nerve palsy (FNP) is reported as a potential complication of Pavlik harness treatment for developmental dysplasia of the hip (DDH). It is known to be transient, as it often resolves following strap adjustment to decrease hip flexion, which may jeopardize the treatment success. The purpose of this study was to report the incidence of this potential complication, to identify any possible associated risk factors and to evaluate its outcome without any specific strap release. Materiel et methodes A retrospective chart review was conducted on all DDH patients who underwent Pavlik harness treatment for DDH between August 1997 and June 2015 by a single physician. Our treatment protocol includes biweekly visits to the clinic for strap adjustment and evaluation of bilateral active knee extension as an indirect indicator of femoral nerve palsy during the entire treatment duration, 3 months in average. Femoral nerve palsy (FNP) was defined as a partial or total deficit in active knee extension anytime during or following the completion of Pavlik harness treatment. All cases of femoral nerve palsy were identified and reviewed. In unilateral cases, the DDH hip was compared to the non-affected side. All hips with femoral nerve palsy were compared to the remaining hips of the series and any possible risk factor for paralysis was recorded, including age, patient's size, severity according to Tonnis and hip flexion angle in the harness. Statistical analysis was undertaken. Resultats Fifty-three cases of femoral nerve palsy of various severity were identified from a group of 473 children with 527 hips treated for DDH (10%) at an average age of 3.9 months. Ninety-three percent of them presented during the first 2 weeks of treatment. FNP was more common in older and larger children with the most severe Tonnis type and a hip flexion angle in the harness above 90 degrees (P  Discussion FNP is a fairly common complication of Pavlik harness treatment for DDH. It is most observed in higher Tonnis types, but its presence by itself is not predictive of treatment failure. The most significant risk factors for FNP seem to be DDH severity and hip flexion angle in the harness. FNP resolves spontaneously before completion of treatment without any specific measures and therefore does not require any strap release or harness discontinuation.

Evaluation of the ossific development in developmental dysplasia of the hip through three-dimensional coordinate system based on CT

Objective To Evaluate the bone development of the hip in developmental dysplasia of the hip (DDH) by three-dimensional (3D) CT. Methods Preoperative 3D CT was performed for 16 unilateral DDH from Dec, 2010 to Dec, 2014 in Tongji Hospital, with 4 males and 12 females, age rank from 20 months to 9 years. When assessing the CT images, the three dimensional coordinate system were established to analysis the development of hips by a paired self-control study. Additionally, the ossific radius, the dislocation length, and the relationships of those variables with the age, the dislocation length were analyzed. Results The ossific volume of the ilium were (31.14±16.25) cm3 and (32.84±17.36) cm3 for the normal side and dislocation side, respectively (t=2.660, P=0.018). The ossific volume of the ischium were (11.61±5.63) cm3 and (8.62±4.09) cm3 for the normal side and dislocation side, respectively (t=3.041, P=0.008). The ossific volume of the pubis were (4.93±2.73) cm3 and (3.93±1.94) cm3 for the normal side and dislocation side, respectively (t=3.776, P=0.002). The ossific volume of the head and superior part of femur were (23.42±12.48) cm3 and (20.21±8.93) cm3 for the normal side and dislocation side, respectively (t=3.158, P=0.006). It is related to the age but not the dislocation length that the ossific volume of the pubis, the ischium and the superior part of femur. Conclusion Preoperative 3D-CT in cases of DDH revealed the bone development of the hip in DDH. Digital model is thought to help discover the bone characteristics of DDH hips. Older age, less ossific volume of bones. Key words: Three dimensional reconstruction; Three dimensional digital model; Developmental dysplasia of the hip; Ossific development

Bilateral developmental dysplasia of the hip: setting an upper age limit for open reduction

Background Salter innominate osteotomy and Dega acetabuloplasty are considered as two of the most commonly used osteotomies for the management of developmental dysplasia of the hip (DDH) in walking children. Bilateral DDH patients add to the complexity of the problem. There is a worldwide debate about the upper age limit for open reduction, especially in bilateral cases. This study was designed as a trial to set an upper age limit for reduction of bilateral DDH hips, and to show the results of management of such cases using the two main osteotomies at an academic supervised referral university hospital. Patients and methods A total of 58 hips in 29 bilateral DDH cases were managed by a team of orthopedic surgeons. The cases were grouped into a Salter and a Dega group and were followed up for a mean of 10 ± 9 years. The same surgeons operated both sides in each case using the same osteotomy to limit the variables. The cases were evaluated clinically and radiographically. Results Radiographic and clinical evaluations were compared during and at the final follow-up visit. Favorable end results were found in 69% of cases (75% Dega and 66.6% Salter). Nevertheless, there were major complications encountered, including redislocation, avascular necrosis, pain, limb-length discrepancy (LLD), and the need for another surgery during the follow-up period. Conclusion Both Salter and Dega osteotomies provided good clinical and radiographic results when a good preoperative assessment and skillful open reduction performed by an experienced surgeon was executed. However, more complications and unfavorable results are expected despite all precautious if performed in children older than 6 years. Level of evidence: IV.

The S-ROM Modular Femoral Stem in Dysplasia of the Hip

Abnormal femoral neck anteversion, previous proximal femoral osteotomies, and small femoral canals with metaphyseal/diaphyseal mismatch are commonly seen in patients with developmental dysplasia of the hip (DDH) and are ideal indications for using a modular femoral stem. The torsional stability of the fluted modular stem makes it the implant of choice for subtrochanteric osteotomy stabilization for reduction of high-riding DDH. Modularity optimizes proximal and distal implant stability while permitting adjustments to anteversion, offset, and leg length to provide custom biomechanical reconstruction of the DDH hip. Clinical results with few complications can be achieved when using this stem in complex DDH surgery.

The Predictive Value of the Development of the Acetabular Teardrop Figure in Developmental Dysplasia of the Hip

Summary: We reviewed the radiographs of 72 hips, 47 with developmental dysplasia of the hip (DDH), and 25 normal hips, to determine the timing of the normal appearance of the acetabular teardrop figure and the value of teardrop development after reduction of the hip in predicting outcome. In normal hips, all children had a teardrop figure by age 18 months. In the 47 hips with DDH, no teardrop figure appeared until the hip was reduced. The DDH hips were divided into two groups based on the success of the initial reduction. By using statistical analysis, we found that the appearance of the acetabular teardrop within 6 months after reduction of the hip is strongly associated with a favorable long-term outcome. We believe that the appearance of the teardrop is the earliest radiographic sign that a stable, concentric reduction of the hip has been achieved

The predictive value of the development of the acetabular teardrop figure in developmental dysplasia of the hip.

We reviewed the radiographs of 72 hips, 47 with developmental dysplasia of the hip (DDH), and 25 normal hips, to determine the timing of the normal appearance of the acetabular teardrop figure and the value of teardrop development after reduction of the hip in predicting outcome. In normal hips, all children had a teardrop figure by age 18 months. In the 47 hips with DDH, no teardrop figure appeared until the hip was reduced. The DDH hips were divided into two groups based on the success of the initial reduction. By using statistical analysis, we found that the appearance of the acetabular teardrop within 6 months after reduction of the hip is strongly associated with a favorable long-term outcome. We believe that the appearance of the teardrop is the earliest radiographic sign that a stable, concentric reduction of the hip has been achieved.