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The Journal of Bone & Joint Surgery British Volume
Vol. 91-B, Issue 6 | Pages 766 - 771
1 Jun 2009
Brunner A Honigmann P Treumann T Babst R

We evaluated the impact of stereo-visualisation of three-dimensional volume-rendering CT datasets on the inter- and intraobserver reliability assessed by kappa values on the AO/OTA and Neer classifications in the assessment of proximal humeral fractures. Four independent observers classified 40 fractures according to the AO/OTA and Neer classifications using plain radiographs, two-dimensional CT scans and with stereo-visualised three-dimensional volume-rendering reconstructions. Both classification systems showed moderate interobserver reliability with plain radiographs and two-dimensional CT scans. Three-dimensional volume-rendered CT scans improved the interobserver reliability of both systems to good. Intraobserver reliability was moderate for both classifications when assessed by plain radiographs. Stereo visualisation of three-dimensional volume rendering improved intraobserver reliability to good for the AO/OTA method and to excellent for the Neer classification. These data support our opinion that stereo visualisation of three-dimensional volume-rendering datasets is of value when analysing and classifying complex fractures of the proximal humerus


The Journal of Bone & Joint Surgery British Volume
Vol. 87-B, Issue 11 | Pages 1520 - 1523
1 Nov 2005
Attias N Lindsey RW Starr AJ Borer D Bridges K Hipp JA

We created virtual three-dimensional reconstruction models from computed tomography scans obtained from patients with acetabular fractures. Virtual cylindrical implants were placed intraosseously in the anterior column, the posterior column and across the dome of the acetabulum. The maximum diameter which was entirely contained within the bone was determined for each position of the screw. In the same model, the cross-sectional diameters of the columns were measured and compared to the maximum diameter of the corresponding virtual implant. We found that the mean maximum diameter of virtual implant accommodated by the anterior columns was 6.4 mm and that the smallest diameter of the columns was larger than the maximum diameter of the equivalent virtual implant. This study suggests that the size of the screw used for percutaneous fixation of acetabular fractures should not be based solely on the measurement of cross-sectional diameter and that virtual three-dimensional reconstructions might be useful in pre-operative planning


The Journal of Bone & Joint Surgery British Volume
Vol. 90-B, Issue 11 | Pages 1495 - 1498
1 Nov 2008
Shen J Tong P Qu H

This randomised study compared outcomes in patients with displaced fractures of the clavicle treated by open reduction and fixation by a reconstruction plate which was placed either superiorly or three-dimensionally. Between 2003 and 2006, 133 consecutive patients with a mean age of 44.2 years (18 to 60) with displaced midshaft fractures of the clavicle were allocated randomly to a three-dimensional (3D) (67 patients) or superior group (66). Outcome measures included the peri-operative outcome index, delayed union, revision surgery and symptoms beyond 16 weeks. CT was used to reconstruct an image of each affected clavicle and Photoshop 7.0 software employed to calculate the percentage of the clavicular cortical area in the sagittal plane. The patients were reviewed clinically and radiographically at four and 12 months after the operation. The superior plate group had a higher rate of delayed union and had more symptomatic patients than the 3D group (p < 0.05). The percentage comparisons of cortical bone area showed that cortical bone in the superior distal segment is thicker than in the inferior segment, it is also thicker in the anterior mid-section than in the posterior (p < 0.05). If fixation of midshaft fractures of the clavicle with a plate is indicated, a 3D reconstruction plate is better than one placed superiorly, because it is consistent with the stress distribution and shape of the clavicle


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 467 - 467
1 Sep 2012
Ding M Overgaard S
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Introduction. Osteoporosis (OP), osteoarthrosis (OA), and rheumatoid arthritis (RA) are the most common age-related degenerative bone diseases, and major public health problems in terms of enormous amount of economic cost. RA is considered as a major cause of secondary osteoporosis. At late stage, OP often leads to skeletal fractures, and OA and RA result in severe joint disability. Over the last a few decades, much significant research on the properties has been carried out on these diseases, however, a detailed comparison of the microarchitecture of cancellous bones of these diseases is not available. In this study, we investigated three-dimensional (3-D) microarchitectural properties of OP, OA and RA cancellous bone. We hypothesized that there were significant differences in microarchitecture among OP, OA and RA bone tissues that might lead to different bone quality. Materials and Method. Twenty OP, fifty OA, and twelve RA femur heads were harvested from patients undergone total hip replacement surgery. Cubic cancellous bone samples (8∗8∗8 mm3) were prepared and scanned with a high resolution microtomographic system (vivaCT 40, Scanco Medical AG., Brüttisellen, Switzerland). Then micro-CT images were segmented using individual thresholds to obtain accurate 3-D data sets. Detailed microarchitectural properties were evaluated based on novel unbiased, model-free 3-D methods. For statistical analysis, one-way ANOVA was used, and a p<0.05 was considered significant. Results. Significant differences in the microarchitecture of cancellous bone were observed among the OP, OA and RA groups. Compared with the other groups, OP cancellous bone had lowest density, thinner, typical rod-like structure and less connectivity (all p<0.01). Interestingly, there were no significant differences in the microarchitectural properties measured between the OA and RA cancellous bones. Both OA and RA cancellous bones had significant higher bone volume fraction and were thicker, typical plate-like structure compared with the OP group (all p<0.01), even though there was clearly bone erosion observed in RA cancellous bone. Discussion. Quantification of the alterations in bone properties and quality will help to gain more insights into the pathogenesis of degenerative bone diseases and to target and develop novel approaches for the intervention and treatment, and for the design, fixation and durability of total joint prosthesis. Our study demonstrated that there were significant differences in the microarchitecture of the OP, OA and RA femur head cancellous bone. The OA and RA cancellous bone had similar bone density and microarchitecture despite apparent bone erosion in the RA cancellous bone. These results from femur head did not support the traditional notion that RA and OP had similar low bone density. Thus, whether femur head bone tissues from these diseases have similar bone collagen, mineral and mechanical properties, more importantly bone quality, should be clarified in the future


The Journal of Bone & Joint Surgery British Volume
Vol. 86-B, Issue 3 | Pages 413 - 425
1 Apr 2004
Edelson G Kelly I Vigder F Reis ND

Existing classifications of fractures of the head of the humerus are inadequate in terms of interobserver reliability and the predictability of the clinical outcome. From a combined study of 73 fracture specimens in museums and 84 CT-three-dimensional reconstructions in patients, we have devised a classification which appears to be more useful clinically. Common patterns of fracture and a plausible mechanism of injury were observed.

In 3-D most proximal humeral fractures can be organised into five basic types. These correspond in some degree to the Codman/Neer classification, but differ significantly in regard to the more complex patterns of fracture. We observed a logical progression from simple to complex fractures. An interobserver reliability study was carried out which indicated the improved usefulness of this new 3-D concept in providing a common language among clinicians for classifying these injuries. When surgery is indicated, the 3-D concept is also invaluable in guiding the restitution of anatomy through either open or percutaneous means.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_V | Pages 4 - 4
1 Mar 2012
Karuppiah S Downing M Broadbent R Christie M Carnegie C Ashcroft G Johnstone A
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Due to its popularity of intramedullary nails (IMN) high success rate, newer design (titanium) IMN system have been introduced to replace stainless steel system. However the stability provided by the titanium IMN

may not be adequate, there by influencing the union rate.

We aimed to compare the results of both IMN systems via prospective clinical study and biomechanical testing using RSA.

Biomechanical study

This study was done in an experimental set-up which consisted of a physically simulated femoral shaft fractures models fixed with a stainless steel (Russell Taylor) or Titanium (Trigen) IM nailing system. Two common fracture configurations with stimulated weight bearing conditions were used and the axis of fragment movements recorded.

Clinical study

The data on two groups of patients were collected as part of a prospective cohort study. Details of the implant, such as size of nail, cross screw lengths, screw thickness, etc. was collected. Patients were followed up for a minimum of 4 months and details of clinical complications recorded


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_16 | Pages 55 - 55
1 Apr 2013
Kawakami Y Hiranaka T Niikura T Matsuzaki T Hida Y Uemoto H Doita M Tsuji M Kurosaka M
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Introduction

Plate fixations have been recommended for dislocated clavicle fractures. However, existing plates are inadequate for morphological compatibility with the clavicle. The aim of this study is to measure the anatomical shape of the clavicle and to compare the radiographical and clinical outcomes of our tree-dimensional (3D) reconstruction plate with conventional straight plate.

Methods

Chest CT image of 15 patients with normal clavicle were analyzed. Their clavicles were reconstructed and measured their anatomical variables. A hospital-based case-control study was conducted, including a consecutive series of 52 patients with displaced midshaft clavicle fractures. 3D reconstruction plate was used for 26 patients and another 26 patients were treated with conventional straight plate. Outcome measures included the period of bone union, revision surgery, operating times and clinical symptoms using DASH score.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_5 | Pages 10 - 10
13 Mar 2023
Rankin C Coleman S Robinson P Murray I Clement N
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We aim to determine the differences in lower limb joint kinematics during the golf swing of patients who had undergone Total Knee Arthroplasty (TKA) and a control group of native knee golfers. A case-control study was undertaken with ten golfers who had undergone TKA (cruciate retaining single radius implant) and five age and matched golfers with native knees. Each golfer performed five swings with a driver whilst being recorded at 200Hz by a ten-camera motion capture system. Knee and hip three-dimensional joint angles (JA) and joint angular velocities (JAV) were calculated and statistically compared between the groups at six swing events. The only significant differences in knee joint kinematics between TKA and control groups was a lower external rotation JA in the left knee during the backswing (p=0.010). There was no significant difference in knee JAV between the groups. Both hips demonstrated significantly (p=0.023 for left and p=0.037 for right) lower flexion in the TKA group during the takeaway swing event, and there was lower internal rotation in the backswing and greater external rotation in the downswing of the right hip. There was also slower left hip extension JAV in the downswing. Normal knee kinematics were observed during the golf swing following TKA, with the exception of reduced external rotation in the left knee during the back swing and the right during the down swing. The differences demonstrated in the hip motion indicate that they may make compensatory movements to adjust to the reduced external rotation demonstrated in the knee


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_7 | Pages 9 - 9
1 May 2021
Gillespie MJ Nicholson JA Yapp LZ Robinson CM
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The aim of this study was to determine if the extent of the glenoid and humeral bone loss affects the rate of recurrent instability and the functional outcome following the Latarjet procedure. 161 patients underwent open Latarjet procedure during the period 2006–2015 (Mean age 30.0 years, 150t (93.2%) Male, 118 (73.3%) primary procedure). Functional outcome was measured using the Western Ontario Shoulder Instability Index (WOSI) and Quick Disabilities of the Arm, Shoulder and Hand (QuickDash) score at a mean of 4.7 years post-operatively. All patients underwent computed tomographic (CT) imaging pre-operatively. Using three-dimensional reconstruction, the glenoid bone loss, Hill-Sachs lesion and ‘Glenoid Track’ status was recorded. Radiographically-confirmed redislocation was rare (1.2%), but 18.5% (n=23/124) reported ongoing subjective shoulder instability. Fifty-two shoulders (32.3%) were classified as “Off-Track”. The median Quick DASH and WOSI scores were 2.27 (IQR 9.09; range 0–70.45) and 272.0 (IQR 546.5; range 0–2003), respectively. There were no significant differences observed between overall Quick DASH scores or WOSI scores for either On-Track or Off-Track groups (p=0.7 and 0.73, respectively). Subjective instability was not influenced by the degree of glenoid bone loss (p=0.82), the overall size of the Hill-Sachs lesion (p=0.80), or the presence of an ‘Off-Track’ lesion (p=0.84). Functional outcome and recurrent instability following the Latarjet procedure do not appear to be influenced by the extent of glenohumeral bone loss prior to surgery


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_18 | Pages 1 - 1
1 Dec 2018
Turnbull G Shu W Picard F Riches P Clarke J
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Bone is the second most commonly transplanted tissue worldwide, with over four million operations using bone grafts or bone substitute materials annually to treat bone defects. However, significant limitations affect current treatment options and clinical demand for bone grafts continues to rise due to conditions such as trauma, cancer, infection and arthritis. The need for a novel, cost effective treatment option for osteochondral defects has therefore never been greater. As an emerging technology, three-dimensional (3D) bioprinting has the capacity to deposit cells, extracellular matrices and other biological materials in user-defined patterns to build complex tissue constructs from the “bottom up”. Through use of extrusion bioprinting and fused deposition modelling (FDM) 3D printing, porous 3D scaffolds were successfully created in this study from hydrogels and synthetic polymers. Mesenchymal stem cells (MSCs) seeded onto polycaprolactone scaffolds with defined pore sizes and porosity maintained viability over a 7-day period, with addition of alginate hydrogel and scaffold surface treatment with NaOH increasing cell adhesion and viability. MSC-laden alginate constructs produced via extrusion bioprinting also maintained structural integrity and cell viability over 7 days in vitro culture. Growth within osteogenic media resulted in successful osteogenic differentiation of MSCs within scaffolds compared to controls (p<0.001). MSC spheroids were also successfully created and bioprinted within a novel, supramolecular hydrogel with tunable stiffness. In conclusion, 3D constructs capable of supporting osteogenic differentiation of MSCs were biofabricated via FDM and extrusion bioprinting. Future work will look to increase osteochondral construct size and complexity, whilst maintaining cell viability


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_16 | Pages 93 - 93
1 Apr 2013
Abe Y Tanoue M
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Introduction. The treatment of trochanteric femoral fractures with the use of short femoral nails has become an established method. The fixation is required that lag screw be centered to prevent complications. But correct positioning of the device may difficult because of anatomical feature. This study evaluated the femoral morphology three-dimensionally using computed tomography (CT) images. Methods. Seventy eight patients (mean age 75)who underwent total knee arthroplasty were included. After three-dimensional reconstruction of the CT images, the anterior deviation from the femoral neck axis to proximal shaft axis was measured. The proximal shaft axis was defined as a line between center of the cross-section underneath the lesser trochanter and the center of diaphysis. The connection of center in narrow section of the neck and femoral head center was defined as neck axis. Results. The femoral neck axis and shaft axis were not coplanar. The anterior deviation of the axes was 7.5 mm (1.7 to 18.4 mm). The neck-shaft angle was 124° (110–142°). Discussion. Our results indicate that the nail and screw could not be center in current nail system, because of the non-crossing of the femoral axes. The large variation of neck-shaft angle would lead error in preoperative planning using traditional 2-D template system. Our study suggests needs for three-dimensional template system and newly femoral nail device


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 82 - 82
1 Sep 2012
Benjamin G Zadegan F Hannouche D Nizard R
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Limb length disparity is a frequent complication after hip surgery inducing many surgeon-patients conflicts. To date no study has been able to precisely quantify such limb length disparity. EOS® system, currently validated to measure lower limb parameters, allows from two bi-dimensional numerical orthogonal radiographies in standing position to obtain a tri-dimensional reconstruction of lower limbs. A computerized system achieves the parameters calculation. The aim of this study is to precisely measure the limb length disparities and the other hip parameters following total hip arthroplasty surgical procedure, by using a standard X-rays and using EOS® three-dimensional reconstructions. Twenty-eight patients programmed for total hip arthroplasty have been included (i.e. thirty lower limbs). Two independent performers have carried out twice the measures either on standard X-rays and using three-dimensional reconstructions of the lower limb disparities prior and after the surgical procedure. The inter and intra-observer reproducibility for the measure of the lower limb disparities have been of the EOS® measures have been respectively of 0.854 and 0.865 and for the standard X-rays of 0.717 and 0.726. Mean length disparity observed was before Total Hip Arthroplasty of −0.328 cm (0.705; −1.266/0.530) and was of 0.088 mm (1.326; −1.635/0.632) after. We are able to decrease the lower limbs disparity in 69.1% and for the average of 0,416cm. Using EOS® system has allowed assessing with greater precision the possibility to restore equal lower limb length. This assessment has permitted introducing a new planning procedure including EOS® imaging associated to the fusion of the prosthetic tri-dimensional image in order to achieve adequate lower limb length


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_18 | Pages 4 - 4
1 Nov 2017
Goudie E Clement N Murray I Wilson M Robinson C
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This study aimed to evaluate the effect of clavicular shortening, measured by three-dimensional computerized tomography (3DCT), on functional outcomes and satisfaction in patients with healed, displaced, midshaft clavicle fractures up to one year following injury. The data used in this study were collected as part of a multicenter, prospective randomized control trial comparing open reduction and plate fixation with nonoperative treatment for displaced midshaft clavicle factures. Patients who were randomized to nonoperative treatment and who had healed by one year were included. Clavicle shortening relative to the uninjured contralateral clavicle was measured on 3DCT. Outcome analysis was conducted at six weeks, three months, six months and one year following injury and included the Disabilities of the Arm, Shoulder and Hand (DASH), Constant and Short Form-12 (SF-12) scores, and patient satisfaction. 48 patients were included. The mean shortening of injured clavicles, relative to the contralateral side, was 11mm (+/− 7.6mm) with a mean proportional shortening of 8percnt;. Proportional shortening did not significantly correlate with the DASH (p>0.42), Constant (p>0.32) or SF-12 (p>0.08) scores at any time point. There was no significant difference in the mean DASH or Constant scores at any followup time point both when the cut off for shortening was defined as one centimeter (p>0.11) or two centimeters (p>0.35). There was no significant difference in clavicle shortening between satisfied and unsatisfied patients (p>0.49). This study demonstrated no association between shortening and functional outcome or satisfaction in patients with healed, displaced, midshaft clavicle fractures up to one year following injury


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 4 | Pages 525 - 530
1 Apr 2011
Tobita K Ohnishi I Matsumoto T Ohashi S Bessho M Kaneko M Matsuyama J Nakamura K

We evaluated the effect of low-intensity pulsed ultrasound stimulation (LIPUS) on the remodelling of callus in a rabbit gap-healing model by bone morphometric analyses using three-dimensional quantitative micro-CT. A tibial osteotomy with a 2 mm gap was immobilised by rigid external fixation and LIPUS was applied using active translucent devices. A control group had sham inactive transducers applied. A region of interest of micro-CT was set at the centre of the osteotomy gap with a width of 1 mm. The morphometric parameters used for evaluation were the volume of mineralised callus (BV) and the volumetric bone mineral density of mineralised tissue (mBMD). The whole region of interest was measured and subdivided into three zones as follows: the periosteal callus zone (external), the medullary callus zone (endosteal) and the cortical gap zone (intercortical). The BV and mBMD were measured for each zone. In the endosteal area, there was a significant increase in the density of newly formed callus which was subsequently diminished by bone resorption that overwhelmed bone formation in this area as the intramedullary canal was restored. In the intercortical area, LIPUS was considered to enhance bone formation throughout the period of observation. These findings indicate that LIPUS could shorten the time required for remodelling and enhance the mineralisation of callus


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 582 - 582
1 Sep 2012
Miyasaka D Ito T Suda K Imai N Endo N Dohmae Y Minato I
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Several studies have reported the assessment of the femoral head coverage on plane radiograph and CT data in supine position, though young patients with the dysplastic hip often have symptoms during activities such as standing, walking, and running. On the other hand, some investigators have used a method of CT which allows standardization of the femoral head coverage against an anterior pelvic plane based on the anterior superior iliac spines and the pubic tubercle. We believe both the weight-bearing position and the standardized position to be more relevant for diagnosis and preoperative surgical assessment. So, we show the femoral head coverage in standardized position using 3D-CT method and in weight-bearing position using the plane radiograph and the three-dimensional lower extremity alignment assessment system before and after Curved periacetabular osteotomy (CPO). Especially the covered volume of the femoral head, a new concept, using the three-dimensional lower extremity alignment assessment system which differs from the affected area and is measured by the ratio of the covered area in the medial part of the line connecting the anterior point of the acetabulum with the posterior to the femoral head area in each axial slice, superior slices than the slice passing through the femoral head center, obtained from the reproduced 3D model of the pelvis and the femur in standing position allows us to integrate various measurements reported by past researchers. We studied the consecutive 16 patients treated with CPO. In standardized position the sagittal sectional angles on the slice passing through the femoral head center using 3D-CT method gave us how the anterior, lateral, and posterior coverage was lack compared with normal subjects and whether the adequate transfer of the rotated fragment was performed after operation. The covered volume of the femoral head decides generally the deficiency or the adequateness. In standing position, though the pelvic tilt changes, the femoral head coverage on plane radiograph, representation by the CE angle, the VCA angle, AHI and ARO, was significantly improved, and the covered volume of the femoral head was significantly improved from 25.7% preoperatively to 51.1% postoperatively. Our study showed the improvement of the femoral head coverage, including the covered volume of the femoral head as a new concept, after CPO in weight-bearing and standardized position. The morphological and functional assessment of the femoral head coverage on both pre- and post-CPO should be performed because we can obtain the objective information in standardized position and the femoral head coverage in standing position is closely connected with the pain


The Bone & Joint Journal
Vol. 95-B, Issue 10 | Pages 1396 - 1401
1 Oct 2013
Gabbe BJ Esser M Bucknill A Russ MK Hofstee D Cameron PA Handley C deSteiger RN

We describe the routine imaging practices of Level 1 trauma centres for patients with severe pelvic ring fractures, and the interobserver reliability of the classification systems of these fractures using plain radiographs and three-dimensional (3D) CT reconstructions. Clinical and imaging data for 187 adult patients (139 men and 48 women, mean age 43 years (15 to 101)) with a severe pelvic ring fracture managed at two Level 1 trauma centres between July 2007 and June 2010 were extracted. Three experienced orthopaedic surgeons classified the plain radiographs and 3D CT reconstruction images of 100 patients using the Tile/AO and Young–Burgess systems. Reliability was compared using kappa statistics. A total of 115 patients (62%) had plain radiographs as well as two-dimensional (2D) CT and 3D CT reconstructions, 52 patients (28%) had plain films only, 12 (6.4%) had 2D and 3D CT reconstructions images only, and eight patients (4.3%) had no available images. The plain radiograph was limited to an anteroposterior pelvic view. Patients without imaging, or only plain films, were more severely injured. A total of 72 patients (39%) were imaged with a pelvic binder in situ. Interobserver reliability for the Tile/AO (Kappa 0.10 to 0.17) and Young–Burgess (Kappa 0.09 to 0.21) was low, and insufficient for clinical and research purposes. Severe pelvic ring fractures are difficult to classify due to their complexity, the increasing use of early treatment such as with pelvic binders, and the absence of imaging altogether in important patient sub-groups, such as those who die early of their injuries. Cite this article: Bone Joint J 2013;95-B:1396–1401


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 3 | Pages 378 - 386
1 Mar 2011
Foruria AM de Gracia MM Larson DR Munuera L Sanchez-Sotelo J

Our aim was to determine the effect of the initial pattern of fracture and the displacement of fragments on the outcome of proximal humeral fractures treated conservatively. We followed 93 consecutive patients prospectively for one year. Final movement and strength were compared with those of the contralateral side. The final American Shoulder and Elbow Society score and the Disabilities of Arm, Shoulder and Hand and Short-Form 36 questionnaires were compared with those provided by the patient on the day of the injury. Radiographs and CT scans with three-dimensional reconstruction were obtained in all patients. The pattern of the fracture and the displacement of individual fragments were analysed and correlated with the final outcome. There were two cases of nonunion and six of avascular necrosis. The majority of the fractures (84 patients; 90%) followed one of the following four patterns: posteromedial (varus) impaction in 50 patients (54%), lateral (valgus) impaction in 13 (14%), isolated greater tuberosity in 15 (16%), and anteromedial impaction fracture in six (6%). Head orientation, impaction of the surgical neck and displacement of the tuberosity correlated strongly with the outcome. In fractures with posteromedial impaction, a poor outcome was noted as the articular surface displaced inferiorly increasing its distance from the acromion. A poorer outcome was noted as a fractured greater tuberosity displaced medially overlapping with the posterior articular surface. Lateral impaction fractures had a worse outcome than other patterns of fracture


Introduction. Short-segment posterior instrumentation for spine fractures is threatened by unacceptable failure rates. Two important design objectives of pedicle screws, bending and pullout strength, may conflict with each other. Hypothesis. Multiobjective optimization study with artificial neural network (ANN) algorithm and genetic algorithm (GA). Materials & Methods. Three-dimensional finite element (FE) methods were applied to investigate the optimal designs of pedicle screws with an outer diameter of 7 mm using a multiobjective approach for these two objectives. Based on the FE results on an L25 orthogonal array, two objective functions were developed by an ANN algorithm. Then, the trade-off solutions known as Pareto optima were explored by a GA. The optimal design was validated by mechanical tests. Results. The knee solutions of the Pareto fronts had simultaneous high bending and pullout strength ranging from 92 to 94 percent of their maxima. The corresponding range of the design parameters was 3.8 to 4.06 mm for inner diameter and 3.21 to 3.3 mm for pitch; 0 mm for beginning position of conical angle, 0.4 mm for proximal root radius, 5 degrees for proximal half angle, and 0.1 mm for thread width. The optimal design was well validated by mechanical tests, comparing with commercially available pedicle screws. Discussion & Conclusions. The optimal design of pedicle screws obtained could achieve an ideal with high mechanical performance in both bending and pullout tests


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 585 - 585
1 Sep 2012
Albers C Steppacher S Ganz R Siebenrock K Tannast M
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The Bernese Periacetabular Osteotomy (PAO) has become the established method for treating developmental dysplasia of the hip. In the 1990s, the surgical technique was modified to avoid postoperative cam impingement due to uncorrected head neck offset or pincer impingement due to acetabular retroversion after reorientation. The goal of the study was to compare the survivorship of two series of PAOs with and without the modifications of the surgical technique and to calculate predictive factors for a poor outcome. A retrospective, comparative study of two consecutive series of PAOs with a minimum follow-up of 10 years was carried out. Series A included 75 PAOs performed between 1984 and 1987 and represent the first cases of PAO. Series B included 90 hips that underwent PAO between 1997 and 2000. In this series, emphasis was put on an optimal acetabular version next to the correction of the lateral coverage. Additionally, a concomitant arthrotomy was performed in every hip to check impingement-free range of motion after reorientation and in 50 hips (56%) an additional offset correction was performed. Survivorship analyses according to Kaplan and Meier were carried out and the endpoint was defined as conversion to a total hip arthroplasty, progression of osteoarthritis, or a Merle d'Aubign score 14. Predictive factors for poor outcome were calculated using the Cox-regression analysis. The cumulative 10-year survivorship of Series A was significantly decreased (77%; 95%-confidence interval [CI] 72–82%) compared to Series B (86%; 95%-CI 82–89%, p=0.005). Hips with an aspherical head showed a significantly increased survivorship if a concomitant offset correction was performed intraoperatively (90% [95%-CI 86–94%] versus 77% [95%-CI 71–82%], p=0.003). Preoperative factors predicting poor outcome included a high age at surgery, a Merle d'Aubign score 14, a positive impingement test, a positive Trendelenburg sign, limp, an increased grade of osteoarthritis according to Tönnis, and (sub-) luxation of the femoral head (Severin > 3). In addition, predictive factors related to the three dimensional orientation of the acetabular fragment were identified. These included total, anterior, and posterior acetabular over-coverage or under-coverage, acetabular retroversion or excessive anteversion, a lateral center edge angle < 22 °, an acetabular index > 14 °, and no offset correction in aspherical femoral heads. A good long term result after PAO mainly depends on optimal three-dimensional orientation of the acetabulum and impingement-free range of motion with correction of an aspherical head neck junction if necessary


The Journal of Bone & Joint Surgery British Volume
Vol. 79-B, Issue 2 | Pages 285 - 288
1 Mar 1997
Hernigou P Besnard P

Plain radiographs show only two dimensions of a three-dimensional object. On anteroposterior and lateral radiographs an implant may appear to be safely within the head of the femur although surface penetration has occurred. We have attempted to identify this complication in the treatment of fractures of the femoral neck and have analysed the position of a screw or pin in the femoral head and neck on the basis of orthogonal frontal and lateral radiographs. A retrospective analysis of 60 cases of osteosynthesis of fractures of the femoral neck confirmed the risk of non-recognition of articular penetration or breaking of the cortex of the neck during surgery. Unrecognised screw penetration of the hip was observed in 8% and of the posterior part of the neck in 10%. The risk differs according to the type of fracture: it is greater in the coxa valga produced by Garden-I fractures of the femoral neck