Search

Purpose: Multimodal articulated image registration (MAIR) is a challenging problem because the resulting transformation needs to maintain rigidity for bony structures while allowing elastic deformation for surrounding soft tissues. Existing deep learning-based methods ignore the articulated structures and consider it as a pure deformable registration problem, leading to suboptimal results. Methods: We propose a novel weakly supervised anatomy-aware multimodal articulated image registration network, referred as MAIRNet, to solve the challenging problem. The architecture of MAIRNet comprises of two branches: a non-learnable polyrigid registration branch to estimate an initial velocity field, and a learnable deformable registration branch to learn an increment. These two branches work together to produce a velocity field that can be integrated to generate the final displacement field. Results: We designed and conducted comprehensive experiments on three datasets to evaluate the performance of the proposed method. Specifically, on the hip dataset, our method achieved, respectively, an average dice of 90.8%, 92.4% and 91.3% for the pelvis, the right femur, and the left femur. On the lumbar spinal dataset, our method obtained, respectively, an average dice of 86.1% and 85.9% for the L4 and the L5 vertebrae. On the thoracic spinal dataset, our method achieved, respectively, an average dice of 76.7%, 79.5%, 82.9%, 85.5% and 85.7% for the five thoracic vertebrae ranging from T6 to T10. Conclusion: In summary, we developed a novel approach for multimodal articulated image registration. Comprehensive experiments conducted on three typical yet challenging datasets demonstrated the efficacy of the present approach. Our method achieved better results than the state-of-the-art approaches.

Aims: To assess (1) hip pain and function and ROM; (2) subsequent surgeries, complications; and (3) subjective satisfaction and PROMs in patients undergoing femoral derotation osteotomies.Methods: Femoral derotation subtrochanteric osteotomies to treat symptomatic posterior extraarticular ischiofemoral hip impingement were performed in 23 patients (25 hips) between 2013 and 2017. The mean age was 26 ± 8 years (96% female) with a minimum 2-year follow-up (mean follow-up of 4 ± 1 years). Surgical indication was a positive posterior impingement test and limited external rotation (mean 16° ± 8°) in extension in patients with abnormal high femoral version (mean 46° ± 9, measured on CT scans with the Murphy method) and high McKibbin instability index (mean 67°). Femoral osteotomies were combined with a surgical hip dislocation in 96% for cam resection and labrum or cartilage treatment. Preoperative MRI and 3D-CT with dynamic impingement simulation were evaluated.Results: (1) The posterior impingement test decreased significantly from preoperatively 100% to 4% (p<0.001). External rotation in extension increased significantly (p<0.001) from preoperative 16° ± 8 to 44° ± 16°. The MdA score increased significantly from 14 ± 1 to 16 ± 2 (p<0.001) points. (2) At follow-up, all 25 hips were preserved. No conversion to THA and no revision osteosynthesis was performed. 64% underwent complete hardware removal. (3) 80% of the patients reported at follow-up that they would undergo surgery again. Subjective satisfaction (SHV) increased significantly (p<0.001) from preoperatively 24% to 84% postoperatively.Conclusions: Femoral derotation subtrochanteric osteotomies for the treatment of posterior extraarticular ischiofemoral hip impingement are safe and improve posterior hip pain and function and external rotation in mostly female patients with high femoral version and a high McKibbin instability index.

Purpose: Preservation surgery can halt the progress of joint degradation, preserving the life of the hip; however, outcome depends on the existing cartilage quality. Biochemical analysis of the hip cartilage utilizing MRI sequences such as delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), in addition to morphological analysis, can be used to detect early signs of cartilage degradation. However, a complete, accurate 3D analysis of the cartilage regions and layers is currently not possible due to a lack of diagnostic tools. Methods: A system for the efficient automatic parametrization of the 3D hip cartilage was developed. 2D U-nets were trained on manually annotated dual-flip angle (DFA) dGEMRIC for femoral head localization and cartilage segmentation. A fully automated cartilage sectioning pipeline for analysis of central and peripheral regions, femoral-acetabular layers, and a variable number of section slices, was developed along with functionality for the automatic calculation of dGEMRIC index, thickness, surface area, and volume. Results: The trained networks locate the femoral head and segment the cartilage with a Dice similarity coefficient of 88 ± 3 and 83 ± 4% on DFA and magnetization-prepared 2 rapid gradient-echo (MP2RAGE) dGEMRIC, respectively. A completely automatic cartilage analysis was performed in 18s, and no significant difference for average dGEMRIC index, volume, surface area, and thickness calculated on manual and automatic segmentation was observed. Conclusion: An application for the 3D analysis of hip cartilage was developed for the automated detection of subtle morphological and biochemical signs of cartilage degradation in prognostic studies and clinical diagnosis. The segmentation network achieved a 4-time increase in processing speed without loss of segmentation accuracy on both normal and deformed anatomy, enabling accurate parametrization. Retraining of the networks with the promising MP2RAGE protocol would enable analysis without the need for B1 inhomogeneity correction in the future.

Objective To assess whether subchondral drilling of acetabular cartilage flaps during femoroacetabular impingement (FAI) surgery improves (1) acetabular dGEMRIC indices and (2) morphologic magnetic resonance imaging (MRI) scores, compared with hips in which no additional treatment of cartilage lesions had been performed; and (3) whether global dGEMRIC indices and MRI scores correlate.Design Prospective cohort study of consecutive patients with symptomatic FAI treated with open surgery between 2000 and 2007. Patients with subchondral drilling of acetabular cartilage flaps were allocated to the study group, those without drilling to the control group. All patients underwent indirect 3-T MR arthrography to assess cartilage quality by dGEMRIC indices and a semiquantitative morphologic MRI score at minimum 5 years after surgery. dGEMRIC indices and morphologic MRI scores were compared between and among groups using analysis of covariance/paired ttests.Results No significant difference was found between the global dGEMRIC indices of the study group (449 ± 147 ms, 95% CI 432-466 ms) and the control group (428 ± 143 ms, 95% CI 416-442 ms; P= 0.235). In regions with cartilage flaps, the study group showed higher dGEMRIC indices (472 ± 160 ms, 95% CI 433-510 ms) compared with the control group (390 ± 122 ms, 95% CI 367-413 ms; P< 0.001). No significant differences were found for the morphologic MRI scores. A strong inversely linear correlation between the dGEMRIC indices and the morphologic MRI scores (r= −0.727, P< 0.001) was observed.Conclusions Treatment of acetabular cartilage flaps with subchondral drilling leads to better cartilage quality in regions with cartilage flaps at minimum 5 years of follow-up.

Objective To investigate acetabular cartilage thickness among (1) 8 measurement locations on the lunate surface and (2) different types of femoroacetabular impingement (FAI).Design Prospective descriptive study comparing in vivomeasured acetabular cartilage thickness using a validated ultrasonic device during surgical hip dislocation in 50 hips. Measurement locations included the anterior/posterior horn and 3 locations on each peripheral and central aspect of the acetabulum. The clock system was used for orientation. Thickness was compared among cam (11 hips), pincer (8 hips), and mixed-type (31 hips) of FAI. Mean age was 31 ± 8 (range, 18-49) years. Hips with no degenerative changes were included (Tönnis stage = 0).Results Acetabular cartilage thickness ranged from 1.7 mm to 2.7 mm and differed among the 8 locations (P< 0.001). Thicker cartilage was found on the peripheral aspect at 11 and 1 o’clock positions (mean of 2.4 mm and 2.7 mm, respectively). At 5 out of 8 locations of measurement (anterior and posterior horn, 1 o’clock peripheral, 12 and 2 o’clock central), cartilage thickness was thinner in hips with pincer impingement compared to cam and/or mixed-type of FAI (Pranging from <0.001 to 0.031). No difference in thickness existed between cam and mixed-type of impingement (P= 0.751).Conclusion Acetabular cartilage thickness varied topographically and among FAI types. This study provides first baseline information about topographical cartilage thickness in FAI measured in vivo. Thinner cartilage thickness in pincer deformities could be misinterpreted as joint degeneration and could therefore have an impact on indication for hip preserving surgery.

Compared with three-dimensional (3D) dual-flip-angle acquisition, 3D magnetization-prepared 2 rapid acquisition gradient-echo MRI enabled more accurate T1 mapping of hip cartilage, was less affected by B1inhomogeneities, and showed high accuracy against a T1 reference in participants with hip pain.

AimsThe prevalence of combined abnormalities of femoral torsion (FT) and tibial torsion (TT) is unknown in patients with femoroacetabular impingement (FAI) and hip dysplasia. This study aimed to determine the prevalence of combined abnormalities of FT and TT, and which subgroups are associated with combined abnormalities of FT and TT.MethodsWe retrospectively evaluated symptomatic patients with FAI or hip dysplasia with CT scans performed between September 2011 and September 2016. A total of 261 hips (174 patients) had a measurement of FT and TT. Their mean age was 31 years (SD 9), and 63% were female (165 hips). Patients were compared to an asymptomatic control group (48 hips, 27 patients) who had CT scans including femur and tibia available for analysis, which had been acquired for nonorthopaedic reasons. Comparisons were conducted using analysis of variance with Bonferroni correction.ResultsIn the overall study group, abnormal FT was present in 62% (163 hips). Abnormal TT was present in 42% (109 hips). Normal FT combined with normal TT was present in 21% (55 hips). The most frequent abnormal combination was increased FT combined with normal TT of 32% (84 hips). In the hip dysplasia group, 21% (11 hips) had increased FT combined with increased TT. The prevalence of abnormal FT varied significantly among the subgroups (p < 0.001). We found a significantly higher mean FT for hip dysplasia (31°; SD 15)° and valgus hips (42° (SD 12°)) compared with the control group (22° (SD 8°)). We found a significantly higher mean TT for hips with cam-type-FAI (34° (SD 6°)) and hip dysplasia (35° (SD 9°)) compared with the control group (28° (SD 8°)) (p < 0.001).ConclusionPatients with FAI had a high prevalence of combined abnormalities of FT and TT. For hip dysplasia, we found a significantly higher mean FT and TT, while 21% of patients (11 hips) had combined increased TT and increased FT (combined torsional malalignment). This is important when planning hip preserving surgery such as periacetabular osteomy and femoral derotation osteotomy.Cite this article: Bone Joint J2020;102-B(12):1636–1645.

Questions: Does surgical hip dislocation with drilling or bone grafting, cartilage treatment and femoral osteotomy in avascular necrosis of the femoral head (AVN) result in: (1) progression of osteonecrosis or osteoarthritis; (2) pain relief and improved function; and (3) subsequent surgery and complications?Methods: We retrospectively reviewed 12 patients (13 hips, mean age 29 ± 9 years) undergoing surgical hip dislocation for AVN. Preoperative ARCO stages were: 1 hip ARCO II, 8 hips ARCO III early, 4 hips ARCO III late. Drilling was performed in 4 hips, 9 hips underwent curettage, drilling and autologous bone grafting. Cartilage was sutured in 5 hips, autologous matrix-induced chondrogenesis was performed in 3 hips, an osteochondral autograft was used in 1 hip. Femoral osteotomy was performed in 10 hips. Mean follow-up was 3 ± 2 years. Progression of AVN and osteoarthritis was assessed preoperatively and at latest follow-up using Tönnis and ARCO staging. Pain and function were assessed with the Merle d’Aubigné-Postel score. Complications were graded according to Sink et al.Results: 1 hip had AVN progression and converted to THA. 9 hips showed no AVN- or advanced osteoarthritis progression and 3 hips improved at least 1 ARCO stage. The Merle d’Aubigné-Postel score increased from preoperatively 14.1 ± 3.2 to 16.6 ± 1.2 (p= 0.012). Subsequent surgery were performed in 3 hips, complications occurred in 3 hips.Conclusion: Although the first results are promising a longer follow-up with more patients is needed to draw a definite conclusion regarding the joint preserving potential in AVN.

Hintergrund: Femorale Torsionsfehler beinhalten die femorale Retrotorsion und die erhöhte femorale Antetorsion und sind mögliche Ursachen für Hüftschmerzen und Hüftarthrose. Femorale Torsionsfehler bei jungen Patienten mit femoroazetabulärem Impingement (FAI) gelten als weitere Möglichkeit für ein Hüftimpingement neben dem Cam- und Pincer-FAI. Ziel der Arbeit: Dieser Artikel soll einen Überblick über die verschiedenen Messmethoden und Normwerte der femoralen Torsion geben. Die klinische Präsentation von Patienten mit femoralen Torsionsfehlern, mögliche Kombinationen und die chirurgische Therapie wird beschrieben. Methoden: Zur Messung der femoralen Torsion ist die Schnittbildgebung mittels CT oder MRT der Goldstandard. Dabei sollten die verschiedenen Definitionen berücksichtigt werden, weil diese zu sehr unterschiedlichen Werten und Fehldiagnosen führen können, vor allem bei Patienten mit hoher femoraler Antetorsion. Eine dynamische 3D-Impingementsimulation, basierend auf 3D-CT, kann bei der Differenzierung zwischen intra- und extraartikulärem FAI helfen. Ergebnisse und Diskussion: Eine femorale Retrotorsion (&lt; 5°) kann sowohl zu einem anterioren intra- als auch extraartikulären („subspine“) FAI zwischen der Spina iliaca anterior inferior und dem proximalen Femur führen. Die erhöhte femorale Antetorsion (> 35°) kann zu einem posterioren intra- und extraartikulären (ischiofemoralen) Impingement zwischen dem Trochanter minor/major und dem Tuber ischiadicum führen. Klinisch kann eine femorale Retrotorsion durch die fehlende Innenrotation und einen positiven anterioren Impingementtest erkannt werden. Bei der erhöhten femoralen Antetorsion ist die Innenrotation erhöht, typischerweise in Bauchlage und der Faber-Test und der posteriore Impingementtest sind positiv.

AimsAbnormal femoral torsion (FT) is increasingly recognized as an additional cause for femoroacetabular impingement (FAI). It is unknown if in-toeing of the foot is a specific diagnostic sign for increased FT in patients with symptomatic FAI. The aims of this study were to determine: 1) the prevalence and diagnostic accuracy of in-toeing to detect increased FT; 2) if foot progression angle (FPA) and tibial torsion (TT) are different among patients with abnormal FT; and 3) if FPA correlates with FT.Patients and MethodsA retrospective, institutional review board (IRB)-approved, controlled study of 85 symptomatic patients (148 hips) with FAI or hip dysplasia was performed in the gait laboratory. All patients had a measurement of FT (pelvic CT scan), TT (CT scan), and FPA (optical motion capture system). We allocated all patients to three groups with decreased FT (< 10°, 37 hips), increased FT (> 25°, 61 hips), and normal FT (10° to 25°, 50 hips). Cluster analysis was performed.ResultsWe found a specificity of 99%, positive predictive value (PPV) of 93%, and sensitivity of 23% for in-toeing (FPA < 0°) to detect increased FT > 25°. Most of the hips with normal or decreased FT had no in-toeing (false-positive rate of 1%). Patients with increased FT had significantly (p < 0.001) more in-toeing than patients with decreased FT. The majority of the patients (77%) with increased FT walk with a normal foot position. The correlation between FPA and FT was significant (r = 0.404, p < 0.001). Five cluster groups were identified.ConclusionIn-toeing has a high specificity and high PPV to detect increased FT, but increased FT can be missed because of the low sensitivity and high false-negative rate. These results can be used for diagnosis of abnormal FT in patients with FAI or hip dysplasia undergoing hip arthroscopy or femoral derotation osteotomy. However, most of the patients with increased FT walk with a normal foot position. This can lead to underestimation or misdiagnosis of abnormal FT. We recommend measuring FT with CT/MRI scans in all patients with FAI.Cite this article: Bone Joint J2019;101-B:1218–1229

Radial 2D MRI scans of the hip are routinely used for the diagnosis of the cam type of femoroacetabular impingement (FAI) and of avascular necrosis (AVN) of the femoral head, both considered causes of hip joint osteoarthritis in young and active patients. A method for automated and accurate segmentation of the proximal femur from radial MRI scans could be very useful in both clinical routine and biomechanical studies. However, to our knowledge, no such method has been published before. The aims of this study are the development of a system for the segmentation of the proximal femur from radial MRI scans and the reconstruction of its 3D model that can be used for diagnosis and planning of hip-preserving surgery. The proposed system relies on: (a) a random forest classifier and (b) the registration of a 3D template mesh of the femur to the radial slices based on a physically based deformable model. The input to the system are the radial slices and the manually specified positions of three landmarks. Our dataset consists of the radial MRI scans of 25 patients symptomatic of FAI or AVN and accompanying manual segmentation of the femur, treated as the ground truth. The achieved segmentation of the proximal femur has an average Dice similarity coefficient (DSC) of 96.37 ± 1.55%, an average symmetric mean absolute distance (SMAD) of 0.94 ± 0.39 mm and an average Hausdorff distance of 2.37 ± 1.14 mm. In the femoral head subregion, the average SMAD is 0.64 ± 0.18 mm and the average Hausdorff distance is 1.41 ± 0.56 mm. We validated a semiautomated method for the segmentation of the proximal femur from radial MR scans. A 3D model of the proximal femur is also reconstructed, which can be used for the planning of hip-preserving surgery.

Introduction: The best treatment of acetabular chondral flaps during surgery for femoroacetabular impingement (FAI) is unknown. We asked if subchondral drilling improves clinical and radiographic outcome and if there are factors predicting failure.Methods: We treated 79 patients with symptomatic FAI and acetabular chondral flaps with surgical hip dislocation between January 2000 and December 2007. Exclusion of all patients with previous hip pathology or trauma resulted in 62 patients (80 hips). The chondral flap was slightly debrided in 43 patients/51 hips (control group). In 28 patients/29 hips (study group), additional osseous drilling was performed. 4 patients (5 hips, 6%) were lost to follow-up. Mean follow-up was 9 years (5–13 years). The groups did not differ in demographic data, radiographic parameters or follow-up. Clinical outcome was assessed with the Merle d’Aubigné score, modified Harris Hip Score and University of California Los Angeles activity score and progression of osteoarthritis with the Tönnis grade.Results: No patient underwent conversion to total hip arthroplasty (THA) in the drilling group compared to 7 patients (8 hips, 16%) in the control group (p= 0.005); in the remaining hips, clinical scores and progression of Tönnis grade did not differ. Increased acetabular coverage, age and body mass index were univariate predictive factors for conversion to THA. No drilling was as an independent predictive factor for conversion to THA (hazard ratio 58.07, p= 0.009).Conclusion: Subchondral drilling under acetabular chondral flaps during surgical treatment of FAI is an effective procedure to reduce the rate of conversion to THA.

Valgus intertrochanteric osteotomy is a well-established treatment in delayed union of femoral neck fractures as it converts shear forces into compression forces. Non-union of the femoral neck fracture may persist following valgus intertrochanteric osteotomy, and secondary femoroacetabular impingement (FAI) may be a contributing factor.

To develop a hybrid augmented marker-based navigation system for acetabular reorientation during peri-acetabular osteotomy (PAO). The system consists of a tracking unit attached to the patient’s pelvis, augmented marker attached to the acetabular fragment and a host computer to do all the computations and visualization. The augmented marker is comprised of an external planar Aruco marker facing toward the tracking unit and an internal inertial measurement unit (IMU) to measure its orientation. The orientation output from the IMU is sent to the host computer. The tracking unit streams a live video of the augmented marker to the host computer, where the planar marker is detected and its pose is estimated. A Kalman filter-based sensor fusion combines the output from marker tracking and the IMU. We validated the proposed system using a plastic bone study and a cadaver study. Every time, we compared the inclination and anteversion values measured by the proposed system to those from a previously developed optical tracking-based navigation system. Mean absolute differences for inclination and anteversion were 1.34 ($$\pm \,1.50$$ ±1.50 ) and 1.21 ($$\pm \, 1.07$$ ±1.07 )$$^\circ $$ ∘ , respectively, for the cadaver study. Mean absolute differences were 1.63 ($$\pm \,1.48$$ ±1.48 ) and 1.55 ($$\pm \,1.49$$ ±1.49 )$$^\circ $$ ∘ for inclination and anteversion for the plastic bone study. In both validation studies, very strong correlations were observed. We successfully demonstrated the feasibility of our system to measure the acetabular orientation during PAO.

Arthrofibrosis is defined as an excessive fibrotic tissue response within a joint leading to a painful loss of motion. This pathological scar formation process with dysregulated, inordinate extracellular matrix formation, especially collagen, may occur in any joints, although is frequently localized in the knee. Different etiologies have been described and most of them are related to trauma, infection or recent surgical procedure. Although arthrofibrosis affects people of all ages, it is unusual in pediatric population. We present a case report of an uncommon, foreign body induced knee arthrofibrosis in a 14-year old boy. We also review the current literature regarding diagnostic procedures and treatment rationale for arthrofibrosis of the knee.

Accurate preoperative planning is crucial for the outcome of total hip arthroplasty. Recently, 2D pelvic X-ray radiographs have been replaced by 3D CT. However, CT suffers from relatively high radiation dosage and cost. An alternative is to reconstruct a 3D patient-specific volume data from 2D X-ray images. In this paper, based on a fully automatic image segmentation algorithm, we propose a new control point-based 2D–3D registration approach for a deformable registration of a 3D volumetric template to a limited number of 2D calibrated X-ray images and show its application to personalized reconstruction of 3D volumes of the proximal femur. The 2D–3D registration is done with a hierarchical two-stage strategy: the scaled-rigid 2D–3D registration stage followed by a regularized deformable B-spline 2D–3D registration stage. In both stages, a set of control points with uniform spacing are placed over the domain of the 3D volumetric template first. The registration is then driven by computing updated positions of these control points with intensity-based 2D–2D image registrations of the input X-ray images with the associated digitally reconstructed radiographs, which allows computing the associated registration transformation at each stage. Evaluated on datasets of 44 patients, our method achieved an overall surface reconstruction accuracy of $$0.9 \pm 0.2\,\hbox {mm}$$ 0.9±0.2mm and an average Dice coefficient of $$94.4 \pm 1.1\,\%$$ 94.4±1.1% . We further investigated the cortical bone region reconstruction accuracy, which is important for planning cementless total hip arthroplasty. An average cortical bone region Dice coefficient of $$85.1 \pm 2.9\,\%$$ 85.1±2.9% and an inner cortical bone surface reconstruction accuracy of $$0.7 \pm 0.2\,\hbox {mm}$$ 0.7±0.2mm were found. In summary, we developed a new approach for reconstruction of 3D personalized volumes of the proximal femur from 2D X-ray images. Comprehensive experiments demonstrated the efficacy of the present approach.

Acetabular retroversion following acetabular osteotomy in hips with dysplasia can negatively effect the outcome. Total retroversion, where the entire anterior rim is lateral to the posterior rim, is rare and can easily be missed on pelvic radiographs due to the lack of a crossover sign. We evaluated the clinical and radiographic presentation, the surgical management, and the outcome of hips with total acetabular retroversion.We retrospectively reviewed 26 patients (26 hips) with total retroversion following 15 periacetabular osteotomies (PAO) (1), 10 triple type, and one Salter osteotomy (2). We obtained range of motion (ROM), anterior impingement test, Drehmann's sign, Merle d'Aubigné-Postel score, and Tönnis score for osteoarthrosis. Corrective surgery included 19 revision PAOs and seven total hip arthroplasties (THA). The mean follow-up was 4.7 ± 4.2 (range 0.5-13.8) years.Patients presented with a restricted ROM (flexion and internal rotation), a positive anterior impingement test, a positive Drehmann's sign, and a decreased Merle d'Aubigné-Postel score due to pain. Corrective surgery was performed after mean of 7 ± 5 (1-15) years. Complications for revision PAO and THA occurred in 37% and 29%, respectively. At follow-up, the Merle d'Aubigné-Postel score improved for both revision PAOs and THAs. The prevalence of a positive anterior impingement test and Drehmann's sign decreased for revision PAOs. There was a tendency for progression of OA in hips with revision PAO.Iatrogenic total acetabular retroversion following reorientation is a disabling condition for the patients. Corrective surgery including revision PAO and THA results in improved clinical outcome. However, these procedures are technically challenging and associated with high complication rates.

The analysis and treatment of hips with healed Legg-Calvé-Perthes disease (LCPD) differs substantially from the treatment in the acute phase of the disease. More specifically, the treating orthopaedic surgeon is often faced with a complex three-dimensional pathomorphology of the hip that is difficult to understand and correct. To date, none of the current classification systems provide a useful decision-making algorithm with regards to the type of surgical intervention necessary to improve hip function in patients with sequelae of LCPD. The conceptual recognition of the femoroacetabular impingement (FAI) and the ability to safely dislocate the hip have revolutionised our diagnostic and therapeutic algorithm for joint-preserving surgery of hips with structural residuals of LCPD. We present a systematic approach to analyse femoral and acetabular pathomorphologic features. The resulting pathomechanisms and the surgical treatment options are presented.

To classify the fracture patterns of gunshot wounds to the acetabulum; identify the associated injuries and complications; determine the predictors of poor outcome and deep infection; and propose a treatment algorithm based on the results.

To investigate the clinical and radiographic results after operative treatment of complete symphyseal disruption resulting from childbirth and to evaluate residual pain and implant failure in relation to the timing of surgery.

The objective was to report the ability of a magnetic resonance image to document the integrity of the obturator externus tendon after posterior hip dislocation as a potential predictor for preserved femoral head vascularity.

The aim of this study was to assess the ability to extract surgically relevant information from plain radiographs in trimalleolar fractures and to compare this with the information gathered from computed tomography (CT).

The crossover-sign (COS) is a radiographic sign for diagnosis of acetabular-retroversion(AR) in patients with femoroacetabular-impingement (FAI) but overestimates AR. Three signs combined with retroversion-index (RI) could potentially improve diagnostic-accuracy.

Both Hip Dysplasia(DDH) and Femoro-acetabular-Impingement(FAI) are complex three-dimensional hip pathologies causing hip pain and osteoarthritis in young patients. 3D-MRI-based models were used for radiation-free computer-assisted surgical planning. Automatic segmentation of MRI-based 3D-models are preferred because manual segmentation is time-consuming.