Evaluation of the anatomical features, details of surgical technique and results of the THA in patients with CDH (type C1 and C2 by G. Hartofilakidis). From 2001 to 2016 years one surgical team performed 683 THA in patients with CDH. We retrospectively studied 561 total hip arthroplasties in 349 patients, follow-up rate was 82.1%, from 12 to 188 months (mean 69.4). The results were evaluated by clinical examination, X-rays analysis, Harris Hip Score. Unilateral high hip dislocation was observed in 175 patients (31.2%), in these cases often have underdeveloped half of the pelvis on the side of the dislocation. Type C1 was observed in 326 cases and type C2 – in 235 cases. Type C1 in comparison with C2 has less leg length discrepancy, developed shape of proximal femur, presence of supraacetabular osteophyte. The mean displacement of femoral head was 47.6 mm (from 29 to 55) for C1 and 63.4 mm (from 41 to 78) for C2. Average offset in C1 was 50.1 mm (37–63) and in C2 − 44.3 mm (34–52). Shortening osteotomy by T. Paavilainen performed in 165 cases (50.6%) with C1 dysplasia and in 235 cases (100%) with C2. The features of surgical technique were small size of the cups with obligatory additional screw fixation of the cup and small offset of the stems. The cup was positioned into the true acetabulum in 99.1% cases of C2 type, for C1 – only 69.0%). The cups size 44 mm were used in 97.3% cases for type C2 and in 78.6% cases for type C1. For shortening osteotomy in 76.3% cases Wagner Cone stems were used. Early complications included 9 dislocations (1.6%), 8 femoral nerve neuropathies (1.4%) and 3 infections (0.5%). There is no sciatic nerve palsy. Late complications included dislocation in two hips (1.1%), nonunion of the greater trochanter (8.4%), aseptic loosening of the femoral component − 2 (0.8 %), aseptic loosening of the cup − 11 (1.6%). Average Harris Hip score improved from 39.5 to 83.6 with unsignificant diffence between types C1 and C2 (from 37.3 to 81.4 and from 40.4 to 85.1 consequently). Revision rate was 2.1% for type C1 and 5.5% for type C2. Hip replacement surgery in patients with high hip dislocation is very challenging. Type C2 dysplasia has only one surgical option with good long-term results – placement of the cup into the true acetabulum and shortening osteotomy. Its advantages include leg length alignment and decreased risk of sciatic nerve injury. Type C1 dysplasia presents more heterogenic group of patients and allows to use several surgical options – different placement of the cup and surgical approach without shortening osteotomy. Functional results in patients with type C1 are a little bit worse in comparison with type C2, but C1 had less risk of complications. The main problem of shortening osteotomy by Paavilainen is delayed union and non-union of great trochanter

Goals: Advantage of the dorsal fixation of C1/2

Materials and Methods: From 01/2006 to 12/2006 22 patients with a traumatic fracture of C1/2 were operativly stabilized. The avarage age was 79 year (66–92). No neurological deficit. Diagnostic was always a CT-scan for classification of fracture typ. 7 patients were temporarily immobilized with HALO fixateur. Within th next 8 days final operation hab been carried out. 7 patients with Anderson fractures typ II were stabilized with open fixation from ventral (group 1). 4 Jefferson fractures and 2 combined C1/2 fractures were were stabilized with open fixation from dorsal (Magerl) (group 2). Percutanous fixation from dorsal was done in 5 patients with fractures of the atlas, 4 with Anderson fractures typ II (group3). Clinical and radiological follow up was done in 18 patients

Results: Duration for operation was in 64min in group1, 134min in group 2 and in 42min in group3. No neurological deficit or damage of A.vertebralis occurred. Blood loss was in group 1 and 3 under 50ml in group 2 750ml. In group3 one slightly dislocation of screw happened without need of revision. Movement of cervical spine was reduced in group 2 and 3. During follow up 3 of seven ventral stabilized Anderson fractures typ II (group1) were dislocated. Dorsal percutanous fixation for operatively revision was done.

Discussion: Percutanous dorsal transarticular screw fixation C1/2 is a challanging procedure for stabilization of atlantoaxial fractures. Main advantages compared to other operation techniques are less blood loss, short operation time, high rate of success.

To assess the outcome and safety of transarticular C1-C2 screw fixation

The clinical and radiological outcomes of 15 patients treated with posterior atlantoaxial transarticular screw fixation and posterior wiring was assessed at a minimum follow up of six months. Indications for fusion were rheumatoid arthritis in eight (instability in six and secondary degenerative changes in two), non union odontoid fracture four, symptomatic osodontoideum one, C1-C2 arthrosis one and irreducible odontoid fracture one. Fusion was assessed with plain x-rays including flexion – extension films.

Twenty nine screws were placed under fluroscopic guidance. Bilateral screws were placed in 14 patients and a single screw in one patient. This patient had a single screw placed due to the erosion of the controlateral C2 pars by an anomolous vertebral artery. All patients had radiological union. Two screws (7%) were malpositioned, neither was associated with clinical sequelae. No neurological or vascular injuries were noted.

Transarticular C1-C2 fusion yielded a 100% fusion rate. The risk of neurological or vascular injury can be minimised by thorough assessment of pre operative CT scans to assess position of the vertebral artery and use of intra operative lateral and AP fluroscopy.

Introduction: Fixation of the atlantoaxial complex has traditionally involved transarticular screws combined with posterior wiring techniques and structural bone grafting. Although this does lead to excellent fusion rates, the technique has a potential risk of injury to the vertebral artery. In addition, it cannot be used in fixed subluxation of the C1/2 complex. We describe the use of C1 lateral mass screws in combination with C2 pedicle screws for safe and versatile C1/C2 fixation. Methods: Over a fifteen month period, (July 2003–October 2004) a total of 10 patients underwent posterior C1/ C2 fixation alone, or as part of a more extensive posterior construct. The average age was 54.25 years, ranging from 20–78 years. There were 7 women and 3 men. The average length of stay was 18.5 days ranging from 5–36 days. Technique: A midline posterior approach was used in all cases. The C2 roots were mobilized and the C1 lateral masses identified bilaterally. A drill was inserted into the middle of each lateral mass under image intensification. Bicortical polyaxial screws were then inserted. The C2 pedicle screws were inserted under direct vision, as were the other pedicle screws in the more extensive constructs. Contoured rods and posterior iliac bone graft were used in all cases. Results: Five patients required isolated C1/C2 fusion for instability, two patients had an odontoid fracture non-union, one had an unstable C2 fracture, and the remaining two patients had C1/C2 subluxation secondary to rheumatoid arthritis. More extensive posterior instrumentation was performed for the following cases, these included; occipitothoracic fixation in one patient with rheumatoid arthritis with multi-level cervical subluxation, and occipitocervical fixation in three patients, two who had metastatic disease in the cervical spine, and the remaining patient who had rheumatoid arthritis. The final patient was instrumented from C1–C5 posteriorally following removal of a C3 giant cell tumour. No neurological or vascular complications were observed. One patient, with rheumatoid arthritis and osteoporosis, had a halo applied to protect an occipitothoracic construct. All other patients were discharged in a Miami-J cervical collar. The early follow up data, clinical and radiological, showed fusion in all patients. There were no implant failures. Conclusion: The combination of C1 lateral mass and C2 pedicle screws allows safe, effective and versatile fixation of the C1/C2 complex

Purpose: The biomechanical behaviour of the cervical spine was studied in vitro with an optoelectronic system in order to better understand its physiology. Material: Twenty fresh cervical spines (occiput-D1) from fourteen men and six women, mean age 66.5 years, were sterilised with ß radiation (2.5 Mrad) and stored at −24°C then studied after slow thawing and excision of the paraspinal muscles. Methods: Three-point reflecting markers were rapidly attached to each vertebral segment (4 or 5 vertebrae). The inferior vertebra was blocked. Six pure moment couples (2 N.m maximum, 10 increments) were applied in the three anatomic planes using a loading device lodged on the superior vertebra. Displacements were measured with the VICON 140 using a kinematic software. Results: The three-dimensional behaviour curves of each functional unit (FU) were recorded for each solicitation to analyse the principal movement and coupled movements (maximum mobility, neutral zones, rigid zones, rigidity). Mean maximal flexion-extension movements were C0/C1= 28.7°; C1/C2 = 22.3°; C2/C3 = 7.3°; C3/C4 = 10.6°; C4/C5 = 13.8°; C5/C6 = 13.4°; C6/C7 = 10.8°; C7/T1 = 6.4°. Maximum overall lateral inclinations were: C0/C1= 8.7°; C1/C2 = 9.3°; C2/C3 = 8.7°; C3/C4 = 6.7°; C4/C5 = 10.5°; C5/C6 = 12.2°; C6/C7 = 8.6°; C7/T1 = 5.7°. Maximal overall axial rotations were: C0/C1= 11°; C1/C2 = 71°; C2/C3 = 9.5°; C3/C4 = 10.8°; C4/C5 = 12.3°; C5/C6 = 9°; C6/C7 = 5.6°; C7/T1 = 5.7°. All the FU exhibited flexion-extension movement. Lateral inclination coupled important controlateral rotation for C1/C2 and minimal ipsilateral rotation (< 10°) in the lower FU of the cervical spine. Axial rotation of the C1/T1 functional unit was coupled with homolateral rotation (< 10°). Discussion: Our experimental protocol provided precision of < 1° and good reproducibility allowing simultaneous three-dimensional analysis of the spinal functional units. Making measurements without direct contact is particularly useful for the cervical spine. Our results are within the experimental corridor defined by Goel, Panjabi and Wen. Conclusion: This work on a large number of functional units adds further support to data in the literature concerning the biomechanical behaviour of the cervical spine. Our protocol could be applied to analyse the impact of surgical procedures used for the cervical spine, particularly for the evaluation of new fixation systems or prostheses

Aims. In this study, we aimed to visualize the spatial distribution characteristics of femoral head necrosis using a novel measurement method. Methods. We retrospectively collected CT imaging data of 108 hips with non-traumatic osteonecrosis of the femoral head from 76 consecutive patients (mean age 34.3 years (SD 8.1), 56.58% male (n = 43)) in two clinical centres. The femoral head was divided into 288 standard units (based on the orientation of units within the femoral head, designated as N[Superior], S[Inferior], E[Anterior], and W[Posterior]) using a new measurement system called the longitude and latitude division system (LLDS). A computer-aided design (CAD) measurement tool was also developed to visualize the measurement of the spatial location of necrotic lesions in CT images. Two orthopaedic surgeons independently performed measurements, and the results were used to draw 2D and 3D heat maps of spatial distribution of necrotic lesions in the femoral head, and for statistical analysis. Results. The results showed that the LLDS has high inter-rater reliability. As illustrated by the heat map, the distribution of Japanese Investigation Committee (JIC) classification type C necrotic lesions exhibited clustering characteristics, with the lesions being concentrated in the northern and eastern regions, forming a hot zone (90% probability) centred on the N4-N6E2, N3-N6E units of outer ring blocks. Statistical results showed that the distribution difference between type C2 and type C1 was most significant in the E1 and E2 units and, combined with the heat map, indicated that the spatial distribution differences at N3-N6E1 and N1-N3E2 units are crucial in understanding type C1 and C2 necrotic lesions. Conclusion. The LLDS can be used to accurately measure the spatial location of necrotic lesions and display their distribution characteristics. Cite this article: Bone Joint Res 2024;13(6):294–305

INTRODUCTION: Atlanto-axial instability due to Rheumatoid arthritis has been treated by posterior C1/C2 wiring techniques supplemented with bone graft. Magerls technique of Transarticular fixation provides a three-point fixation by eliminating motion, promoting fusion, increased mechanical strength and treating instability. It allows fixation across the plane of movement and prevents basilar invagination. The clinical results of transarticular fixation are satisfactory in terms of clinical outcome with few complications. However there are concerns that these patients develop subaxial kyphosis. It is important to highlight that none of these patients in our series had supplementary wiring techniques with TAS The purpose of this study is to analyse postoperative Xrays of patients who have undergone transarticular atlantoaxial fixation and look at the following parameters;. What percentage of patients develop subaxial kyphosis?. Are the ADI and PADI maintained postoperatively?. Is there a late failure rate of TAS despite the absence of supplementary wiring techniques?. MATERIALS & METHODS: 15 patients underwent pre and postoperative cervical spine X-rays in the AP and lateral projections. In addition flexion/extension views were also obtained pre and postoperatively. We analysed the following parmeters:. Pre and Postoperative ADI and PADI. C0/C1, C1/C2, C1/C7, C2/C7 angles. C2/C3 slip and C2/C3 osteoarthritis. Any breakage or pullout of screws. Postoperative basilar invagination. It is important to highlight that all these 15 patients had bony fusion at the C1/C2 joints and these findings have been analysed and published in the clinical counterpart of this study (Fusion rates 97% in 36/37 patients). RESULTS: As highlighted, the clinical outcome of these patients has been published. We would like to present the radiological parameters of this subgroup of patients. The ADI improved in 13 patients with a preoperative median of 7 and postoperatively 3.5. The preoperative and postoperative PADI remained at 15. The C0/C1 angle changed from 12 to 17 postoperatively. The C2/C7 angle changed from 21 to 26 postoperatively. C1/C7 angle changed from 39 to 41. The spinal cord diameter remained at 15 pre and postoperatively. There was only 1 patient with C2/C3 slip on flexion/extension views. 2 patients developed subaxial kyphosis with evidence of significant disc degeneration on preoperative imaging. There are some interesting conclusions from these 15 xrays. Only 2 out of 13 patients have developed a subaxial kyphosis. The 2 patients that have developed subaxial kyphois had subaxial disc degeneration at the level of the kyphois. There was only 1 patient with a C2/C3 spondylolisthesis on flexion/extension. The ADI and SAC were maintained at the craniocervical junction. There is no late failure rate despite the absence of a modified gallie fusion

Introduction: Occipito-cervical fusion has evolved from the used of simple onlay bone grafts to the use of sophisticated modular implants. Initial stiffness prevents micromotion and allows a higher fusion rate. Methods: A composite occipito-cervical model (OCM) was developed and validated using data obtained from cadaveric specimens. A jig was designed to pot the OCM, which allowed the application of independent moment forces to simulate flexion, extension, lateral flexion and rotation. The following implants were used 1 ) Grob plate with C1/C2 transarticular screw fixation.2) Grob Plate without C1/C2 transarticular screw fixation.3) Cervifix rod system 4) A Ransford loop system 5.) Olerud plate fixation. A three dimensional ultrasonic motion analysis system (Zebris Inc.) was used to record motion at three positions: 1)C0 2) C2 3) C4.A separate OCM was used for each instrumentation system. Results: The Grob plate with C1/C2 transarticular fixation was found to confer the greatest initial stiffness. The Ransford loop construct was found to confer the least initial stiffness. Plate fixation offered greater stability then rod or loop constructs. We found the three dimensional motion analysis system to be ideal for displacement analysis in complex spinal instrumentation constructs

Objective: To review the clinical outcome of 37 consecutive patients undergoing C1– C2 transarticular fixation for patients with Rheumatoid Arthritis. Design: Prospective Observational Study. Methods: There were 37 patients at 2 centres. Age range was 37– 82 years. The time since diagnosis to treatment was 2– 23 years. Clinical presentation included suboccipital pain in 26/ 37 patients and neck pain in 29/37 patients. 22 patients had presented with myelopathy ( Ranawat grade II or III A). The preoperative imaging included Plain X Rays, CT scans and MRI scans. All patients underwent C1/ C2 transarticular screws ( Stealth guided) except 4 patients in which an aberrant course of the vertebral artery was identified. Outcome measures: Functional outcome, Complications, Postoperative Neurological Status, Neck Disability index, Myelopathy disability index. Results: 1 patient had died at 12 month followup. Neck pain improved in 22( 75%) of patients by > 5 points on the VAS. Suboccipital pain had improved in all patients. 17 patients (80%) improved following operation on the Ranawat Grading, 2 patient were worse and 3 patients remained the same. > 70% patients reported improvement in neck disability index and > 50% patients reported improvement in myelopathy disability index. Conclusions: C1/ C2 Transarticular fixation with spinal navigation is a safe technique for treating atlantoaxial instability in patients with Rheumatoid Arthritis. This study demonstrates improvement in all domains including neck disability, myelopathy scores and functional outcome

The purpose of this study is the biomechanical comparison of five C1 – C2 posterior arthrodesis techniques. Ten adult human cadaveric upper cervical spine specimens were sectioned at the C3 level. The occiput and C3 vertebra were potted in PMMA. The specimens were tested intact; after destabilizing with odontoid transection and sectioning of the transverse and capsular ligaments; and after stabilization with Brooks-Jenkins cable fixation, Brooks-Jenkins with unilateral transarticular screw, Gallie posterior wire construct with unilateral transarticular screw, Brooks-Jenkins with bilateral screws, and Gallie with bilateral screws. Data were analysed with special attention paid to the motion at C1 – C2. The neutral zone (NZ) and range of motion (ROM) were measured in the main plane of each motion, as well as in coupled planes. In flexion / extension and lateral bending, the ROM and NZ increased significantly in the injured specimens as compared to the intact (p< 0.0001). In axial torsion, there was no significant difference between the intact and injured spines at C1 – C2 level. In the different fixation systems, the ROM and NZ were significantly lower than in injured and intact spines in all motions (p< 0.01), except the lateral bending in intact spine. Among the 5 instrumentations, the NZ and ROM in flexion / extension for the Gallie construct with one screw were significantly higher than for the Brooks-Jenkins construct with one or two screws (p< 0.05). In axial torsion, the Gallie construct with one screw displayed a larger NZ and ROM than any of the other four constructs (p< 0.05)

Objectives. Using a simple classification method, we aimed to estimate the collapse rate due to osteonecrosis of the femoral head (ONFH) in order to develop treatment guidelines for joint-preserving surgeries. Methods. We retrospectively analyzed 505 hips from 310 patients (141 men, 169 women; mean age 45.5 years . (sd. 14.9; 15 to 86)) diagnosed with ONFH and classified them using the Japanese Investigation Committee (JIC) classification. The JIC system includes four visualized types based on the location and size of osteonecrotic lesions on weightbearing surfaces (types A, B, C1, and C2) and the stage of ONFH. The collapse rate due to ONFH was calculated using Kaplan–Meier survival analysis, with radiological collapse/arthroplasty as endpoints. Results. Bilateral cases accounted for 390 hips, while unilateral cases accounted for 115. According to the JIC types, 21 hips were type A, 34 were type B, 173 were type C1, and 277 were type C2. At initial diagnosis, 238/505 hips (47.0%) had already collapsed. Further, the cumulative survival rate was analyzed in 212 precollapsed hips, and the two-year and five-year collapse rates were found to be 0% and 0%, 7.9% and 7.9%, 23.2% and 36.6%, and 57.8% and 84.8% for types A, B, C1, and C2, respectively. Conclusion. Type A ONFH needs no further treatment, but precollapse type C2 ONFH warrants immediate treatment with joint-preserving surgery. Considering the high collapse rate, our study results justify the importance of early diagnosis and intervention in asymptomatic patients with type C2 ONFH. Cite this article: Y. Kuroda, T. Tanaka, T. Miyagawa, T. Kawai, K. Goto, S. Tanaka, S. Matsuda, H. Akiyama. Classification of osteonecrosis of the femoral head: Who should have surgery?. Bone Joint Res 2019;8:451–458. DOI: 10.1302/2046-3758.810.BJR-2019-0022.R1

Wear of the polyethylene liner in Total hip arthroplasty (THA) is associated to aseptic component loosening. With low wear bearing surfaces and metal backing in acetabular components the manual methods of measurements have not fared well. Computerized methods increased the ease and accuracy of wear measurement. The average clinician has no access to these methods. In this study we proposed to develop a method of manual wear measurement (PowerPoint – PP method) using a simple office PC and. quantify its accuracy and reproducibility. compare the accuracy with Livermore and Dorr method and. determine the accuracy in different degrees of wear. The study population was divided into class 1 (C1), Class 2 (C2) and Class 3 (C3) group. C1 group had 20 patients who had undergone liner change for high wear. This class simulated a high wear situation. C2 group had 24 patients who were implanted with HXLP. This class simulated very low wear situation. 10 patients were included in C3 group. The same 6week postoperative radiograph was paired as a set of x rays for analysis. This mimics a zero wear situation. PP method had more consistency with Livermore method for C1 group. For C2 and C3 groups all the three methods did not provide consistent results. The correlation coefficient values for wear measurement by PP method showed good correlation between observers in C1 and C2 wear (P values < 0.05). For C3 with true zero wear there was poor correlation between the observers (r −0.659, 0.028, 0.638). The paired T test P values for all classes and both observers were > 0.05. There was no statistically significant difference in the reading of the two observers. Pearson correlation coefficient for all methods showed good correlation for C1and C2 groups. All the methods had errors while measuring true zero in C3. The one way ANOVA analysis was done to identify the ability of the three methods differentiate between C2 and C3. The PP method had the ability (P value < 0.05) to differentiate between C1, C2 and C3. The Dorr’s and Livermore’s methods could only differentiate the C1 from C2andC3. Computerized methods have certain limitations. Matthew Collier et al reported a mean linear wear rate of 0.4(0.04–0.86) and 0.27 (0.01–0.56) by computerized methods in radiographs with true zero wear. In C3 group the average wear rate by PP method was 0.22 ± 0.206 mm. In PP method ability to work at 400% magnifications, ability to correct for rotation on X axis, grouping function of PowerPoint program leads to less chances of errors. PP method has a good reproducibility for clinical use (r> 0.930). The ability of the PP method to differentiate between C2 and C3 should make it a preferred manual method of wear assessment. The PP method has limitations. The least measurement is limited by diameter of the femoral head. It cannot be utilized for wear analysis in cup loosening or migration. It can be regarded as a supplement to the existing methods of manual wear measurements

Purpose of the study:. Is circular external fixation a safe and effective method of managing closed distal third tibia fractures. These fractures are conventionally treated with plaster casts, intramedullary nails or plate fixation. These treatment modalities have complication rates in the literature of up to 16% malunion, 12% non-union, and 17% deep infections. Description and Methods:. Retrospective review of 18 patients with closed distal third tibia fractures, with or without extension into the ankle joint, treated with circular fixator systems and minimal percutaneous internal fixation of the intra-articular fragment if required. Patients were followed up for time to union, malunion incidence as well as incidence of pin tract and deep infection. Distal third fractures which were extra articular or with simple intra articular extension were included. (AO 43 A, B1, C1, C2 + AO 42 in distal third) Patients with pilon fractures (AO 43 B2, B3 and C3) were excluded. Summary of results:. The average time to union in these patients was 16 weeks (11–33 weeks). The non-union rate was 11.1% in comparison to 12% with conventional treatment. The malunion rate was 0% compared to 16% with conventional treatment. The incidence of pin tract infection was 16.6%, but no deep infections were noted, whilst conventional treatment shows deep infection in up to 17%. Conclusion:. Circular external fixation is a safe and efficient option in the treatment of distal tibia fractures. The incidence of complications is significantly reduced in comparison to conventional treatment

Detection of clinical situations are the most difficult for primary THA and factors which determine the complexity. Results of 2368 primary THA performed by one surgeon in 1923 patients with various hip pathologies from 2004 to 2016 were analyzed. The time of the surgery, the bloodloss, the features of the surgical technique, the implants used, and the incidence of complications and revisions were assessed and X-ray analysis was performed. Difficult cases of primary hip arthroplasty include severe dysplasia (types B2, C1, and C2 according to the Hartofilakidis classification), post-traumatic segmental acetabular defects and pelvic discontinuity, protrusio acetabuli, iatrogenic bone ankylosis and consequences of proximal femur fractures with significant shortening of the limb. X-ray signs of difficulty included an interruption of the Shenton line of 2 cm or more (except for acute fractures of proximal femur), the femoral neck-shaft angle less than 100°, and the horizontal distance from Kohler line to center of rotation less than 20% of the diameter of the femoral head. An additional burdening factor is the previous surgical interventions on the hip joint. The ten-year survival rate for standard cases was 94.9%, and for complex cases − 92.3%. The odds ratio development of complications in complex cases compared to standard cases is OR = 8.402 (95% CI from 4.614 to 15.300). In standard cases mean HHS increased from 42.9 points before surgery to 95.3 after surgery. In complex cases mean HHS before surgery was 38.9 and after surgery improved to 81.6 points, p <0.001. The complexity of the operation cannot be determined on the basis of only the etiological factor, it is necessary to take into account the severity of anatomical changes

Atlanto-axial rotatory fixation (AARF) is uncommon and is usually associated with a history of trauma to the neck or an upper respiratory tract infection. In patients who present early, correction of the deformity with traction and orthoses has been reported. Owing to failure of reduction, patients presenting late (more than a month after the condition developed) have been treated with an in situ C1/C2 fusion. Follow-up of in situ fusions has shown both progression of the deformity and correction through compensatory mechanisms. Over a five-year period seven AARF patients (16%), ranging in age from 5 to 11 years, presented more than three months after injury. All patients had a ‘cock robin’ posture and were neurologically intact. In three patients the injury was sustained in a fall from a tree and in four it was due to a motor vehicle accident. Two patients sustained additional fractures. All patients had CT scans. In four patients MR scans and MR angiography were used to evaluate the pathology in the atlanto-axial complex, including the vertebral artery, and revealed soft-tissue interposition in the atlanto-axial joint and atlantodental interval. There was thrombosis of the vertebral artery in two patients. Clinical and radiological correction of the deformity was achieved with transoral release and skull traction, followed by fusion. While in previous studies there has been speculation on the causes of failure of closed reduction, MRI and the transoral procedure identified the pathology in this uncommon condition

Introduction. Dual-mobility (DM) liners have increased popularity due to the range of motion and stability provided by these implants. However, larger head diameters have been associated with anterior hip pain, due to surrounding soft-tissue impingement, particularly the iliopsoas. To address this, an anatomically contoured dual mobility (ACDM) liner was designed by reducing the volume of the liner below the equator (Fig1). Previous cadaver studies have shown that the ACDM significantly reduces iliopsoas tenting and trapping of the liner compared to conventional designs. We created a finite element study based on previous cadaver testing to further analyze the effectiveness of the ACDM design in reducing soft-tissue impingement, specifically the tendon-liner contact pressure and the tendon stress. Methods. The finite element model was developed within COMSOL 4.3b. The psoas tendon was modelled as a Yeoh hyper-elastic Material, which uses 3 constants (c1-c3), density (1.73g/cm3) and a bulk modulus (26GPa)[Hirokawa,2000]. In a previous, separate study, the average stiffness of 10 psoas tendon samples (5 cadavers), were measured to be 339[N/mm] in the linear region with average width and thickness of 14mmX4mm. The 3 constants were tuned to match experimental uniaxial test data, and were 5[GPa], 0[Gpa], and 46[GPa] for c1, c2, and c3 respectively. The implant components were rigidly modeled relative to the psoas. Cadaver specific CT models were used to create the FEA geometry. The insertion points for the Psoas were digitally determined on the proximal end of the lesser trochanter, and the psoas notch on the pelvis for hip flexion angles of −15°, 0°, 15° and 30°. These insertion points determined the length of the psoas and its relative position to the femoral head in 3D. The specific liner size and position for each cadaver was determined by implant planning with the CT models. In this abstract, we only present data for 2 specimens (left/right hips) with 44mm conventional DM, and 44mm ACDM, matching specimen anatomy. A 500N tensile load was applied to the psoas tendon proximally to simulate moderate physiological loading, the average/max stresses and contact pressures between the psoas and the two liner designs were determined. Results. At all flexion angles from −15° to 30°, the ACDM had lower psoas-liner contact pressure and stress compared to the conventional liner. Both contact pressure and tendon stress decreased for both liners with increasing hip flexion. At −15° flexion angle, there was an average contact pressure difference of .51MPa between the conventional and ACDM designs, or 37% decrease in pressure when using the ACDM. The average difference in tendon stress was 67.9MPa, or a 59% decrease in stress when using the ACDM (fig2, fig3). Conclusion. This study utilized cadaver specific FEA models to evaluate interaction between the iliopsoas tendon and conventional and ACDM liners. Although this abstract presented FEA models for only four hips (two specimens), the results show a notable reduction in contact pressure and tendon stress with ACDM designs. This validates findings from previous cadaver studies, suggesting that anatomically contoured designs could reduce anterior hip pain and soft tissue impingement

Stereotactic navigation in cranial surgery is a well-established technique, in routine clinical use since the turn of the century. The advent of computer guided stereotaxis since the early 1990’s has led to an explosion in applications for the technology in cranial surgery, with the development of new surgical techniques, minimal access and consequent claimed reduction in morbidity and mortality. Computer guidance also allows application of stereotactic techniques in spinal surgery. Early interventions have concentrated on the insertion of pedicle screws with improvement in accuracy and certainty of optimal screw placement. The use of fluoroscopic guidance allows the insertion of percutaneous pedicle screws and truly minimal access fusion techniques for the lumbar spine. More recently the development of improved registration has allowed the application of this technology to thoracic spinal surgery and to the cervical spine. Percutaneous techniques for C1/C2 arthrodesis, image guided vertebrectomy and transoral surgery, have been reported. The technology allows the development of surgical techniques designed not only for individual pathology but adapted to the anatomy of the individual patient. Disadvantages include a significant learning curve, especially for cervical spine surgery, the cost and need for registration which may be time consuming. Advantages include claimed accuracy in decompression, hardware placement, minimal access techniques and a three-dimensional solution to what is essentially a three dimensional problem. More recently non-computer based navigation systems have become available with improved hardware placement without the problems associated with computer based systems. The purpose of this paper is to review computer guided spinal surgery, present new techniques based on its application to the adult spine, discuss advantages and disadvantages of those techniques and present the results of studies on the new non-computer based navigation systems

Early percutaneous pin fixation after closed reduction is the treatment of choice for displaced distal humerus fractures. Our purpose was to study the outcome of closed reduction and external fixation more than 1 week after injury. Material and methods: Ninety-one children with fractures of the distal humerus were treated more than 7 days after injury (range 7 – 65 days, average 10,5 days). The average age at the time of surgery was 6,7 years (range 3,3 – 16,1years). 63 were male. All had 1–3 previous unsuccessful closed or\and open reductions in another clinic. Twelve had iatrogenic nerve injury. Our method consists of applying the Ilizarov’ apparatus in the proximal humerus for primary transolecranon traction and close reduction using image intensifier. After reduction two crossed K-wires were passed through the condyles and final fixator was constructed. The K-wire from olecranon was removed. Postoperative fixation was done for 3 – 6 weeks. Elbow motion was started 2–3 days after surgery. Results: The results depended on the severity of the fracture and time after injury. All fractures went on to union. Good and excellent results (no deformity or contracture) occurred in 95 % of 59 patients with transcondylar fractures (AO classification type A2 and A3) and 7–16 days after injury. Of twenty patients with transcondylar fractures (AO classification A2 and A3) and more than 17 days 85% had similar result. Three children required eventual supracondylar osteotomy because of progressive rotational-varus deformity. Of twelve children with T- of Y- fractures (AO C1, C2, or C3) three (25%) had poor Results: Conclusion: Late reduction with external fixation was accomplished with anatomic reduction and good functional outcome and allowed early motion of the elbow

Introduction: The rotational fiexibility of the occipito-atlanto-axial complex is infiuenced by several ligaments, capsules and the alarian ligament (AL). For the development of a biomechanical model simulating dens fractures and stabilization techniques, we investigate the rotational range of motion of the atlantodental joint reducing sequentially the infiuence of capsules and additional ligaments in two different groups (segments C0–C2 and segments C1–C2). The torque affecting the dens axis was analyzed. Methods: 7 fresh C0–C2 + 7 fresh C1–C2 cadaver segments with the integrity of all ligaments and joint capsules were mounted on a custom made rotational testing device (RTD) of a universal mechanical testing machine (UTM). Pure axial torque with a rotational speed of 5°/s was applied clockwise and counter-clockwise. To acquire the physiological range of motion (ROM) between C1 and C2, a maximal axial torque of ±1.5Nm was applied. Consecutively, all the ligaments which do not attach to the odontoid were transected and the ligaments which attach to or contact with the odontoid were preserved. The previously recorded rotation was applied to the specimens with the RTD. The torque between C1 and C2 was recorded. Results: The group C0–C2 had a mean unidirectional ROM of 23.45° at 0.3Nm and of 32.87° at 1.5Nm respectively. The group C1–C2 had a larger ROM of 27.41° at 0.3Nm and of 35.47° at 1.5Nm. After resection of ligaments the torque in Group C0–C2 was reduced by 38% (0.3 Nm) and 61% (1.5Nm) respectively. The group C1–C2 showed a higher reduction of the transmitted torque: 90% (0.3Nm) and 80% (1.5Nm) respectively. Discussion: Evaluating the direct torque forces on the atlantodental joint, we sequentially cut the ligamentous junction of the C1–C2 complex. ROM measurements at 0.3 Nm correlate well to previous data. Measurements in the group with cut AL (C1–C2) had an increased ROM. Comparing the reduction of the transmitted torque between the two groups, 90% (0.3Nm) and 80% (1.5Nm) in group C1–C2 in contrast to only 38% (0.3Nm) and 61% (1.5Nm) in group C0–C2, the rotationally stabilizing meaning of the AL in the occipito-atlantodental complex is punctuated. Higher torques (1.5Nm) increased the reduction of the transmitted torque in group C0–C2 between the measurements with intact and with cut ligaments. We hypothesize that the torque acting on the atlantodental joint is dominated by the AL at smaller angles and has to be considered in the evaluation of upper cervical models. In higher angles the torque is predominately determined by the capsules. Transferring the data to a model simulating the torque on the dens, a clear distinction has to be made based upon the region of the ROM. For larger angles at the borders of the ROM, the infiuence of the facet joint capsules cannot be neglected

Between 1994 and 2002, 42 patients aged over 65 years were admitted to the spinal injuries unit with odontoid fractures. Data was retrospectively collected by analysis of the national spinal unit database, hospital inpatient enquiry (HIPE) system, chart and x-ray review. Mean age of patients was 79 years (66–88). Mean following-up with 4.4 years (1–9 yrs). Male to female ratio was 1:1.2 (M=19, F=23). Among the mechanism of injury, simple fall (low-energy) was the commonest underlying cause in 76% of the odontoid fracture, whereas 23% fractures were sustained as a result of motor vehicle accident. Fractures were classified according to Anderson and D’Alonzo method. There were 29 (69%) type 11 fractures, 13 (30%) were type 111 fractures and there was no type 1 fracture. Anterior and posterior displacements were recorded with almost equal frequency. Seven fractures displaced anteriorly and six fractures posteriorly. Primary union occurred in 59% of fractures. Forty (95.3%) fractures were treated non-operatively. Two fractures were stabilized primarily with C1/C2 posterior interspinous fusion. These fractures were odontoid type 11, anteriorly displaced. Three fractures (7.1%) failed to unite and another three fractures (7.1%) united with prolonged interval (9–11 months). Neurological compromise was mainly related to displacement of the fracture. The overall complication rate was significant (48%) with an associated in-hospital mortality of 11.1%. Loss of reduction, non-union after non operative treatment, pin site problems and complication due to associated injuries accounted primarily for this significant complication rate. Most fractures can be managed in orthosis but unstable fractures require rigid external immobilization or surgical fixation. Outcome was assessed using a cervical spine outcome questionnaire from Johns Hopkins School of Medicine. Questionnaires were sent by post to all patients identified. Non responders were subsequently contacted by phone, if possible, to complete the questionnaire. In the follow-up, additional 6(14.2%) patients were found deceased, 4 patients were unavailable for review and the remaining 69% had significant recovery. Functional outcome scores approached pre-morbid level in all patients. Outcome of these patients are related to increasing age, co-morbidity and the severity of neurological deficit