Central Dislocation Research Articles

Clinical outcome of surgically treated displaced acetabular fractures with central dislocation using combined anterior and medial plating.

Acetabular fractures are complex articular fractures with a big challenge for orthopaedic surgeons. Surgically managed displaced fractures carry favourable outcomes, especially if the articular surface is reduced accurately. This study aims to assess the clinical outcomes of surgically fixed displaced acetabular fractures with central dislocation using combined anterior and medial plating. We have retrospectively evaluated sixteen patients, who had surgically managed displaced acetabular fractures with central dislocation at our institute. All patients underwent open reduction and internal fixation using combined anterior and medial plating via the Kocher-Langenbeck, the ilioinguinal, or the Stoppa approach. The functional outcome was assessed using the Harris Hip score. Our study includes sixteen patients (12 males, 4 females) with a mean age of 35 years (range: 15-53 years). The mean follow-up was 7.8 years (range: 5-13 years). Functional outcomes were good to excellent in 12 (80%) patients and fair in 3 (20%) patients. At the final follow-up, the solid union had been achieved in all fractures, the mean HHS was 88.84 ± 7.61. Early reduction and surgical fixation of displaced acetabular fractures with central dislocation using combined anterior and medial plates appear to have good clinical outcomes.

Post-Traumatic Central or Axial Atlantoaxial Dislocation Presenting with “Atypical” Symptoms—Analyzing the Role of Dynamic Imaging on the Basis of Experience with 14 Patients Treated by Atlantoaxial Fixation surgery

This is a report of a series of 14 patients who presented with a range of "atypical" cranial, spinal, and systemic symptoms that started after they suffered a relatively severe injury to the head and/or neck several months or years before surgical treatment. The implications of diagnosing and treating central or axial atlantoaxial dislocation (CAAD) is discussed. Also, the role of dynamic rotatory and lateral head tilt imaging in the diagnosis and treatment is analyzed. Of the 14 patients, 7 were men and 7 were women, with an age range of 21-64 years (average, 42 years). Due to the severity of the presenting neurological and non-neurological symptoms, all the patients had lost their occupation and were heavily dependent on painkillers and/or antidepressant drugs. In addition to other characteristic clinical and radiological evidence, CAAD was diagnosed made based on the facetalignments on lateral profile imaging in the neutral head position. Dynamic head flexion-extension, lateral head tilt, and neck rotation imaging findings confirmed and subclassified CAAD. All 14 patients underwent atlantoaxial fixation surgery. A personalized self-assessment clinical scoring parameter and the World Health Organization Disability Assessment Schedule 2.0 was used to evaluate the outcome. One patient did not follow-up after surgery. At a minimum follow-up of 6 months after atlantoaxial fixation surgery, the remaining 13 patients experienced relief from all major symptoms. Diagnosing and treating CAAD can have major therapeutic implications for patients presenting with progressively worsening disabling clinical symptoms following relatively severe head and/or neck trauma.

Bipolar Head Perforation With Rhabdomyosarcoma of the Thigh: A Case Report With Literature Review.

High complication rates during the perioperative management of sarcomas around the pelvis have been reported; however, few include the detailed clinical course or complications in the late postoperative period. Radiotherapy is a multidisciplinary strategy for treating sarcomas. However, irradiated bone and soft tissues show a permanent loss of repair and immunocompetence. We present a case of pleomorphic rhabdomyosarcoma of the thigh that resulted in acetabular collapse induced by radiation and intestinal perforation during long-term follow-up. Additionally, we discuss the risk factors for late complications and pelvic reconstruction methods. A 75-year-old man presented with a 1-month history of a recurring fever. Ten years prior, he was diagnosed with pleomorphic rhabdomyosarcoma of the right thigh and underwent a wide resection and bipolar hip arthroplasty, followed by chemotherapy and radiotherapy. Radiographs showed central dislocation of the bipolar head. Computed tomography revealed free air in the hip joint and thickening of the colon wall. Colonoscopy revealed displacement of the bipolar head into the colon wall. Colon resection and hip disarticulation were performed, as the bipolar head was contaminated with intestinal contents. Currently, he is able to walk stably with a walker, and there is no evidence of recurrence or metastasis of the tumor. Irradiation of the periacetabular bone may induce resorptive destruction, resulting in future structural failure. Hardware should not be used for periacetabular bone reconstruction; the risk of pelvic organ damage should be considered when the acetabular collapse becomes deteriorated. Therefore, other reliable and permanent reconstruction options are required.

A Modified Cannulated Cancellous Bone Impactor Is a Helpful Tool During Acetabular Fractures ORIF, a Technical Note

A Modified Cannulated Cancellous Bone Impactor Is a Helpful Tool During Acetabular Fractures ORIF, a Technical Note

Central or axial atlantoaxial dislocation and craniovertebral junction alterations: a review of 393 patients treated over 12 years.

The authors reviewed their scientific publications and updated their clinical material obtained over the last 12 years for cases of central or axial atlantoaxial dislocation (CAAD) identified in the presence of craniovertebral musculoskeletal and/or neural alteration(s). The management implications of diagnosing and treating CAAD are highlighted. During a 12-year period, CAAD was diagnosed in 393 patients with craniovertebral junction-related musculoskeletal and neural alterations who underwent atlantoaxial fixation. No bone decompression was done. All CAAD-related craniovertebral junction structural changes were identified to have a naturally protective role. Hence, in this paper the term "craniovertebral alterations" is used for "craniovertebral junction anomalies" and the term "Chiari formation" is used instead of the commonly used term "Chiari malformation." The major radiological diagnosis was determined either singly or in cohort with one or more of other so-called pathological entities that included Chiari formation (367 cases), syringomyelia with Chiari (306 cases), idiopathic syringomyelia (12 cases), type B basilar invagination (147 cases), bifid arch of the atlas (9 cases), assimilation of the atlas (119 cases), C2-3 fusion (65 cases), Klippel-Feil alteration (4 cases), and dorsal kyphoscoliosis (15 cases). The follow-up period ranged from 6 to 155 months. Clinical improvement was observed in all patients. Understanding and treating CAAD may have significant implications in the surgical treatment of a number of clinical entities. The gratifying clinical outcomes obtained in patients after atlantoaxial fixation, without any type of decompression involving bone or soft-tissue resection, consolidate the concept that atlantoaxial instability has a defining role in the pathogenesis.

Dynamic distraction in a coronal split intra-articular fracture of middle phalangeal base: A case report

Abstract Proximal interphalangeal joint (PIPJ) is a special joint, which has maximum motion among the joints of the hand. Needless to say, that injury of this particular joint may lead to fracture dislocation and dreaded complications with a disability, if not treated adequately and timely. We report a case of coronal split intra-articular fracture of middle phalangeal base managed by dynamic distraction. The aim of this report was to emphasize that in a central PIPJ dislocation dynamic distraction is a viable and safe option.

Central Atlantoaxial Dislocation: Presenting Symptoms, Diagnostic Parameters, and Surgical Treatment from Reports on 15 Surgically Treated Patients.

This chapter reviews the clinical entity of central or axial atlantoaxial instability (CAAD). From January 2018 to November 2020, 15 patients were identified as having CAAD, wherein there was no atlantoaxial instability when analyzed by conventional radiological parameters and wherein there was no evidence of neural or dural compression due to the odontoid process. The patients were identified as having atlantoaxial instability on the basis of the alignment of facets on lateral profile imaging and a range of telltale clinical and radiological indicators. The clinical statuses of the patients were recorded both before and after surgical treatment by using the specially designed Goel symptom severity index and visual analog scale (VAS) scores. All patients were treated via atlantoaxial fixation. There were six men and nine women ranging in age from 18 to 45years (average: 37years). The presenting clinical symptoms were relatively subtle and long-standing. Apart from symptoms that are generally related to neural compromise at the craniovertebral junction, a range of nonspecific cranial and spinal symptoms were prominent. The follow-up time after surgery ranged from 6 to 34months. All patients showed early postoperative and sustained clinical recovery. The correct diagnosis and appropriate surgical treatment of CAAD can provide an opportunity for quick and lasting clinical recovery.

Treatment of acetabular fracture involving quadrilateral body by external rectus abdominis incision combined with calcaneal profiled plate internal fixation

To investigate the therapeutic effect of lateral rectus abdominis incision combined with winged calcaneal plate on pelvic and acetabular fractures involving quadrilateral body. From January 2017 to April 2021, 21 cases of pelvic and acetabular fractures involving quadrilateral bodies were retrospectively analyzed, including 12 males and 9 females. The age ranged from 21 to 73 years with an average of (43.23±6.45) years. All patients were treated by lateral incision of rectus abdominis combined with open reduction and internal fixation with aerofoil plate, including 12 cases of pelvis with anterior and posterior column fractures, 7 cases of acetabular fractures with quadrilateral involvement, and 2 cases of acetabular fractures with central dislocation. All 21 patients were followed up for 12 to 36 months with an average of (18.60±6.45) months. All fractures healed. According to Matta's image reduction evaluation after operation, 11 cases of pelvic anterior and posterior column fractures were all anatomic reduction, 1 case was satisfactory reduction, 7 cases of acetabular fractures involving quadrilateral were anatomic reduction, 1 case with central dislocation was anatomic reduction, and 1 case was satisfactory reduction. The modified Merle D'Aubigne Postel hip joint score was 13 to 17 points. Lateral incision approach of rectus abdominis combined with wing-shaped steel plate can obtain good radiological and clinical results in the treatment of complex pelvic and acetabular fractures involving quadrilateral bodies, and has advantages in the treatment of complex pelvic fractures and acetabular quadrilateral fractures.

Fragility fractures of the acetabulum

There are limited epidemiological data dedicated to geriatric acetabular fractures. The incidence in individuals older than 60 years of age has more than doubled in the past three decades and expected to double further over the next 20 years. These fractures represent a challenging subset of acetabular trauma patients to treat. Conservative treatment is a valid option in those with minimal displaced fractures and a preserved congruent hip joint. Similarly the frail patient with multiple medical co-morbidities and those unlikely to tolerate surgical intervention should have appropriate analgesia and their fracture managed or ignored by watchful neglect. Surgical treatment options include percutaneous fixation or open reduction and internal fixation techniques. Good outcomes may be expected should a concentric reduction be achieved. Age-related involutional osteoporosis associated with fracture comminution and acetabular dome impaction complicate surgical fixation with higher complication rates and the need for further surgery recognised. Historically described as central fracture dislocations, stoved in hip or burst fracture, acute arthroplasty is advocated in the setting of femoral head damage and in significant acetabular impaction injuries. Controversy remains whether geriatric patients should be treated by open reduction and internal fixation or total hip arthroplasty either acute or delayed and needs to be assessed based on the patient and personality of the fracture.

State of the Art : Current Acetabulum Fracture Management

The annual incidence of acetabulum fractures is estimated to be 8.1 per 100.000 patients. In young adults, high energy trauma is the primary mechanism, but in the elderly, low energy trauma is the primary mechanism. Comorbidities, poor bone quality, and delayed presentation are all linked to a poor outcome. From diagnosis to treatment, the goal of this study is to describe the required procedures in reaching a satisfactory result.It is essential to be able to correctly classify acetabular fractures using the Joudet and Letournel classifications, especially when planning definitive therapy. Non-surgical and operative treatment methods are available for acetabulum fractures. All acetabulum fractures that result in hip joint instability and/or incongruity require surgical treatment. Although the prognosis is lower than in younger patients, Open Reduction Internal Fixation (ORIF) remains the mainstay of therapy for most elderly acetabular fractures. Central fracture dislocation of the hip with medial migration of the quadrilateral plate is common in patients with both column, transverse, T-shaped, and anterior column-posterior hemi-transverse fractures. Failure to repair the quadrilateral plate will result in an incongruent hip and a poor outcome since it has a thin medial wall that fractures with less force than the superior weight-bearing portion of the acetabulum.The goals of postoperative care are to maximize the patient's function, allow a quick return to function, and detect early problems. Complications with acetabulum fractures might occur with any treatment option. Post-traumatic arthritis is the most common complications, followed by Deep Vein Thrombosis (DVT), heterotrphic ossification, infection, and iatrogenic sciatic nerve damage.

Aseptic necrosis of the femoral head as a complication of its traumatic dislocation

The work is based on the analysis of examination and treatment results in traumatic hip dislocation (52 patients). The development of aseptic femoral head necrosis was detected in 11 patients at follow-up from 2 to 5 years. Algorithm of complex examination and treatment in traumatic hip dislocation has been elaborated for early and long-term periods after trauma. The group of high risk for aseptic femoral head necrosis development includes the patients with concomitant trauma, with posterior, obturatory and central dislocation. Rehabilitation is requiered to all patients with traumatic hip dislocation in the period from 2 to 5 years taking into account the peculiarities of hip injury. If the signs of posttraumatic aseptic femoral head necrosis are detected at early stages, then conservative treatment is indicated. In advanced process the operative treatment is indicated. Localization of necrosis area within femoral head, necrosis extension and articular surface congruence are of importance for the choice of adequate operative treatment. Roentgenologic signs of irreversibility of articular tissues destruction are the indication for total hip replacement.

890 Bilateral Acetabular Fractures Induced by An Epilepticseizure In a Paediatric Patient: A Unique Case Andits Management

Abstract Bilateral acetabular fractures following epileptic seizures are a rare but known occurrence in adults, with an 18.5% mortality rate. These fractures occurring post epileptic seizures have not been previously documented in children. We report a case of a 13-year-old boy who presented to hospital via ambulance following two violent generalised tonic–clonic seizures in a postictal state, metabolically acidotic and a low haemoglobin. Acute abdomen was suspected, and the patient underwent a CT scan which showed bilateral acetabular fractures with central dislocations of both femoral heads and free fluid in the abdomen. The patient underwent initial damage control intervention with insertion of bilateral distal femur skeletal traction. Definitive fixation of the acetabular fractures occurred 1 week later with an open reduction internal fixation with novel supra- pectineal plates using a Pfannenstiel incision. We use this report to increase awareness of significant pelvic injuries in paediatric patients post epileptic seizures.

Acetabular Fractures with Central Hip Dislocation: A Retrospective Consecutive 50 Case Series Study Based on AO/OTA 2018 Classification in Midterm Follow-Up.

Introduction Management of acetabular fractures is challenging, especially when a medial acetabular fracture is complicated by central hip dislocation. We retrospectively investigated the clinical outcome and risk factors of secondary hip osteoarthritis requiring total hip arthroplasty after the surgical treatment of acetabular fractures with central hip dislocation. Materials and Methods The medical records of all patients who had acetabular medial wall fractures with central hip dislocation treated with open reduction and internal fixation by a single surgeon between January 2015 and June 2017 were reviewed. Surgical reduction was performed with the modified Stoppa with/without the Kocher-Langenbeck (KL) approach. Patients were followed for a minimum of three years, and the Majeed scoring system was used for functional evaluation. Multivariate logistic regression analysis was used to assess the association of patients' characteristics with the likelihood of advanced posttraumatic arthritis developing with conversion to total hip arthroplasty. Results Fifty patients were included in this study, with disease classified as AO/OTA 2018 62B/62C. Thirty-five patients (70%) had good or excellent Majeed pelvic scores. Eleven patients (22%) eventually received total hip arthroplasty because of end-stage posttraumatic arthritis. Three risk factors identified for total hip arthroplasty were male sex, initial marginal impaction, and sciatic nerve injury. Kaplan-Meier survivorship analysis estimated that the cumulative probability of free-from-end-stage arthritis was 78% (95% confidence interval, 73%–90%) at the 5-year follow-up. Conclusion Surgical fixation with the modified Stoppa and the KL approach for acetabular medial wall fractures with central hip dislocation is an effective approach with a satisfactory functional outcome. A prodromal factor was marginal impaction concomitant with articular damage. The trauma of high axial loading and the occupational distribution (males performing heavy manual labor and heavy lifting) with preoperative sciatic nerve injury increased the odds of developing end-stage arthritis.

Management of quadrilateral plate fractures: An up to date

Acetabular fractures are result of mostly high velocity injury with an incidence of 3/100,000/year. However in elderly patent low energy trauma also result in acetabulum fracture due to osteoporosis. Most of acetabular fracture commonly combined with quadrilateral plate fractures. Till date there is no standard classification system for quadrilateral plate fracture of acetabulum is published which can be utilized for accurately studying the fracture pattern and planning for the surgical approach with management. Initially acetabulum fracture was managed conservatively with traction for at least 6 weeks which results in aggravation of secondary symptoms such as pressure sore, DVT, post traumatic arthritis, loss of muscle strength and endurance. Aim of acetabulum fracture fixation are to allow early mobilization, restoring joint congruity, pain relive and reducing the risk of post traumatic arthritis. An internet search of MEDLINE and PMC using the search term 'acetabular fracture', 'quadrilateral plate fracture' and central hip dislocation in English language was performed on 1st march 2021. Papers specific with quadrilateral plate fracture were only included in the study and we found variety of technique available for displaced quadrilateral plate fractures, such as cerclage wire-plate composite, pelvic brim long screws, various combinations of spring plates (T-shaped plate, L-shaped plate, infrapectineal plate, H-plate, and multidirectional titanium fixator. In this review article we studied different treatment modalities and techniques used over several decades for management of quadrilateral fracture with their outcome.

Intra Cranial Dislocation of Mandibular Condyle—10 Year Follow up of a Case and Review of Literature

Dislocation of the mandibular condyle into the middle cranial fossa is a rare event with only 59 cases having been reported in the English literature. The common etiology is road traffic accident. Epidemiology wise this injury is found commonly in children and young adults. This has been attributed to the undeveloped condyle being small and rounded. In this report we present a case of central dislocation of the mandibular condyle into the middle cranial fossa in a 20 year old female patient sustained in a road traffic accident. Computed tomography helped in early diagnosis and treatment of the patient. We also stress upon the need for long term follow up of the patient to prevent secondary complications of ankylosis.

Surgical Outcomes of C1-2 Posterior Stabilization in Patients With Chiari Malformation Type 1.

Study Design:Retrospective chart review.Objectives:Chiari malformation (CM) is characterized by a downward displacement of the cerebellar tonsils through the foramen magnum. This tonsillar herniation may sometimes be accompanied by syringomyelia and/or basilar invagination (BI). In this study, we examined the surgical outcomes of patients by underwent C1-2 reduction + fixation (C1-2RF), which is a new method defined by Goel, in the literature.Methods:Between 2015 and 2018, 21 patients (mean age and duration of follow-up: 39 years and 20 months, respectively) with CM were treated with atlantoaxial fixation. We found syringomyelia in all patients and BI in 9 of them. In all cases, radiography, computed tomography, and magnetic resonance imaging were performed radiologically. C1-2RF was performed in all patients. Preoperative and postoperative clinical Japanese Orthopaedic Association scores were obtained. Syrinx size and cerebrospinal fluid flow rate were compared radiologically.Results:All patients were treated with C1-2RF. None of the patients underwent foramen magnum decompression or intervention for the syrinx. Occipital bone and subaxial spinal structures were not included in the fixation. In addition to significant clinical improvement, significant improvement in syringomyelia and cerebrospinal fluid flow rate was seen on the radiographs of all patients.Conclusions:Although posterior fossa decompression and/or duraplasty is a common treatment modality in CM, we propose that the C1-2RF method described by Goel is a radiologically and clinically effective treatment method, whether or not BI and/or syringomyelia in CM are present. This article is the first article of central and axial atlantoaxial dislocation, except for Goel’s writings in the literature.

Unexpected increase in extravascular lung water after acute lunginjury

We report on a 27-year-old female patient presenting with pneumonia and developing acute respiratory distress syndrome. Using transpulmonary thermodilution, an elevated extravascular lung water was detected (17 ml/kg). Patient required lung-protective mechanical ventilation and received antibiotic therapy. Negative fluid balance was targeted. Under this treatment, respiratory function improved, inflammation parameters declined, and extravascular lung water was recurrent (10 ml/kg). Subsequently, extravascular lung water increased to 29 ml/kg. In a chest x-ray, the central venous catheter tip was dislocated into the right internal jugular vein. 7 days before, the catheter was shown to be in projection of the Vena cava superior in a previous chest x-ray. After insertion of a new central venous catheter, extravascular lung water was quantified at 10 ml/kg again. After 10 days of mechanical ventilation the patient was successfully extubated. As mechanism for this catheter dislocation, we propose a Valsalva maneuver or spontaneous movements of the upper body of the patient. Sudden increase in extravascular lung water may reflect central venous catheter tip dislocation and chest x-ray should be considered to verify catheter tip position.

Fractures around the Pelvis, Pelvic Rim & Acetabulum in the Elderly: Report on 54 Cases

The authors report on 34 patients with a pelvic rim disruption who were treated with percutaneous 7.3 mm screws. This technique is less invasive and gives immediate comfort. Screws were placed with conventional fluoroscopic assistance. In four cases, the screw tip was protruding out of the pelvic bone, two malposition screws were in the back, and two were in the front of the pelvic ring. A revision was needed in one case. We also report on 20 elderly patients with a fracture dislocation of the hip that ran into the pelvis. Eight of them were anteromedial dislocations, and the rest were central dislocations of the femoral head. In the group of anteromedial fracture dislocations, the results were excellent, with an open reduction and internal fixation (ORIF) achieved through a retroperitoneal approach. In the subgroup of central fracture dislocations, we performed the same type of osteosynthesis via the retroperitoneal approach. However, we obtained an excellent result for only two cases. We have a couple of results. First, a percutaneous screw fixation for pelvic fractures with fluoroscopic guidance gives excellent results in most cases. Second, central fracture dislocations of the hip perform poorly after osteosynthesis via the retroperitoneal approach. These fractures probably should be offered acute or delayed total hip arthroplasty (THA).

КОРРЕЛЯЦИОННЫЙ АНАЛИЗ ОСНОВНЫХ ГРАНИЦ ОСАДОЧНОГО ЧЕХЛА СЕВЕРО-УСТЮРТСКОГО РЕГИОНА

Актуальность исследования обусловлена необходимостью наращивания ресурсной базы Республики Казахстан за счет открытия новых месторождении нефти и газа в Северо-Устюртском регионе. Цель: определение корреляционной связи структурных элементов крупных геоструктур Северо-Устюртского региона. Объекты: поверхности фундамента и палеозоя, подошвы юрских и меловых отложений Северо-Устюртского региона. Методы: переведение в цифровой формат серии структурных карт: по поверхности фунда­мента, палеозоя, доюрской поверхности, подошве мела Северо-Устюртской региона с помощью программных средств Didger, Surfer, ArcGIS, Geosoft; количественный корреляционный анализ основных геологических границ в программном комплексе COSCAD 3D. Результаты. В Устюртском регионе по характеру коррелируемости поверхности фундамента и палеозоя, подошвы юрских и меловых отложений выделены три группы геоструктур. В первую группу вошли подвижные складчатые системы и «мобильные углы», в которых коэффициенты корреляции вышеуказанных границ проявляются слабо либо не проявляются вовсе (Южно-Эмбенское поднятие, Арало-Кызылкумский вал, Центрально-Устюртская система дислокации, Горный Мангышлак). Вторую группу формируют внутренние мобильные элементы, обособляющиеся как крупные положительные структуры характеризующиеся экстремально высокими значениями коэффициентов корреляции по поверхности фундамента и палеозоя, подошвы юрских и меловых отложений, (Бузачинский выступ, Актумсукское поднятие, Куаныш-Коскалинский вал, Байчагыр-Яркимбайский свод). Третью группу геоструктур образуют тектонические элементы внутренних районов Северо-Устюртского региона (Северо-Устюртская система прогибов, Челкарская и Барсакельмесская депрессии), характеризующиеся длительным и унаследованным прогибанием в фанерозое и высокой коррелируемостью поверхности фундамента и палеозоя, подошвы юры и мела.

Central dislocation of the femoral head without involvement of anterior or posterior column of the acetabulum: a case report

This study showed a case of a patient with central dislocation of the femoral head without involvement of anterior or posterior column of the acetabulum. The patient was associated with endocrine disorders caused by pituitectomy, severe osteoporosis caused by a long-term gulucocorticoids intake history, and poor bone quality of the quadrilateral plate. The direct impact of the femoral head on the quadrilateral plate after trauma resulted in purely central dislocation of the femoral head. 3D printing technique was used to print the fracture model for observation of the fracture morphology and the simulated operation before surgery. The variable-angle locking acetabular plate with a propeller-like shape was designed on the basis of the mirror of the ipsilesional semi-pelvis. This fracture was reduced via the lateral-rectus approach under direct vision. The quadrilateral surface fractures were fixed by the variable-angle locking acetabular plate which was used as a template for reduction. The follow up after surgery showed good reduction and fixation, equal length of double lower limbs, good positive and passive motion of the injured hip joint and without perioperative complications. This report describes an isolated quadrilateral plate fracture that has not yet been classified. It was effectively treated by using a customized variable-angle locking acetabular plate with a propeller-like shape via the lateral rectus approach.