The extended posterior approach for resection of sacral tumours.

PURPOSE: The conventional posterior approach is mostly advocated for excision of sacral tumours below S2. We describe an operative technique of single-stage en bloc resection of sacral tumours, extending up to S1, through an extended posterior approach. METHOD: Nine patients, who had undergone resection of sacral tumours, by the described technique formed the basis of this study. Four patients had chordomas, whereas schwannoma, neurilemmoma, giant-cell tumour, malignant paraganglioma and recurrent Ewing's sarcoma were seen in one patient each. They were followed up at regular intervals with a mean follow-up of 45.4 months. Perioperative complications, their functional and oncological outcomes at final follow-up were analysed. RESULT: None of the patients had any perioperative complications like uncontrolled haemorrhage, injury to the rectum, deep vein thrombosis or pulmonary embolism. One patient had a superficial wound infection which subsided with regular dressing, and another patient developed a wound breakdown that required an additional flap procedure. At final follow-up, six patients were able to walk without any assistive devices, six patients had normal bladder function, and five patients had normal bowel function. Five patients did not have any recurrence at final follow-up, whereas two were alive with the disease and two had died. CONCLUSION: The reported technique allows en bloc resection of sacral tumours up to S1, through a posterior-only approach. It is less invasive with minimal morbidity. The functional and oncological outcomes are similar to those reported by other investigators. These slides can be retrieved from electronic supplementary material.

Realistic C-arm to pCT registration for vertebral localization in spine surgery : A hybrid 3D-2D registration framework for intraoperative vertebral pose estimation.

Spine surgeries are vulnerable to wrong-level surgeries and postoperative complications because of their complex structure. Unavailability of the 3D intraoperative imaging device, low-contrast intraoperative X-ray images, variable clinical and patient conditions, manual analyses, lack of skilled technicians, and human errors increase the chances of wrong-site or wrong-level surgeries. State of the art work refers 3D-2D image registration systems and other medical image processing techniques to address the complications associated with spine surgeries. Intensity-based 3D-2D image registration systems had been widely practiced across various clinical applications. However, these frameworks are limited to specific clinical conditions such as anatomy, dimension of image correspondence, and imaging modalities. Moreover, there are certain prerequisites for these frameworks to function in clinical application, such as dataset requirement, speed of computation, requirement of high-end system configuration, limited capture range, and multiple local maxima. A simple and effective registration framework was designed with a study objective of vertebral level identification and its pose estimation from intraoperative fluoroscopic images by combining intensity-based and iterative control point (ICP)-based 3D-2D registration. A hierarchical multi-stage registration framework was designed that comprises coarse and finer registration. The coarse registration was performed in two stages, i.e., intensity similarity-based spatial localization and source-to-detector localization based on the intervertebral distance correspondence between vertebral centroids in projected and intraoperative X-ray images. Finally, to speed up target localization in the intraoperative application, based on 3D-2D vertebral centroid correspondence, a rigid ICP-based finer registration was performed. The mean projection distance error (mPDE) measurement and visual similarity between projection image at finer registration point and intraoperative X-ray image and surgeons' feedback were held accountable for the quality assurance of the designed registration framework. The average mPDE after peak signal to noise ratio (PSNR)-based coarse registration was 20.41mm. After the coarse registration in spatial region and source to detector direction, the average mPDE reduced to 12.18mm. On finer ICP-based registration, the mean mPDE was finally reduced to 0.36 mm. The approximate mean time required for the coarse registration, finer registration, and DRR image generation at the final registration point were 10 s, 15 s, and 1.5 min, respectively. The designed registration framework can act as a supporting tool for vertebral level localization and its pose estimation in an intraoperative environment. The framework was designed with the future perspective of intraoperative target localization and its pose estimation irrespective of the target anatomy.

A Hybrid 3D-2D Image Registration Framework for Pedicle Screw Trajectory Registration between Intraoperative X-ray Image and Preoperative CT Image.

Pedicle screw insertion is considered a complex surgery among Orthopaedics surgeons. Exclusively to prevent postoperative complications associated with pedicle screw insertion, various types of image intensity registration-based navigation systems have been developed. These systems are computation-intensive, have a small capture range and have local maxima issues. On the other hand, deep learning-based techniques lack registration generalizability and have data dependency. To overcome these limitations, a patient-specific hybrid 3D-2D registration principled framework was designed to map a pedicle screw trajectory between intraoperative X-ray image and preoperative CT image. An anatomical landmark-based 3D-2D Iterative Control Point (ICP) registration was performed to register a pedicular marker pose between the X-ray images and axial preoperative CT images. The registration framework was clinically validated by generating projection images possessing an optimal match with intraoperative X-ray images at the corresponding control point registration. The effectiveness of the registered trajectory was evaluated in terms of displacement and directional errors after reprojecting its position on 2D radiographic planes. The mean Euclidean distances for the Head and Tail end of the reprojected trajectory from the actual trajectory in the AP and lateral planes were shown to be 0.6-0.8 mm and 0.5-1.6 mm, respectively. Similarly, the corresponding mean directional errors were found to be 4.90 and 20. The mean trajectory length difference between the actual and registered trajectory was shown to be 2.67 mm. The approximate time required in the intraoperative environment to axially map the marker position for a single vertebra was found to be 3 min. Utilizing the markerless registration techniques, the designed framework functions like a screw navigation tool, and assures the quality of surgery being performed by limiting the need of postoperative CT.

An intraarticular fibroma of the tendon sheath in the knee joint.

Fibromas that usually occur in the tendon sheaths of the wrist and hand are extremely rare in intra-articular locations. Only five such cases in the knee joint have been reported so far. This is a case report of an intra-articular fibroma of the tendon sheath of the knee joint arising adjacent to posterior cruciate ligament (PCL). Magnetic resonance imaging (MRI) revealed a well-defined intra-articular lesion in the region of the intercondylar notch of the femur behind the PCL. The mass was excised by arthrotomy. Histopathological study confirmed the diagnosis.

Tension pneumocephalus following an implant removal from spine.

Pneumocephalus is commonly seen after skull and maxillofacial fractures. It can also occur following cerebrospinal fluid leak after skull base surgery and epidural catheter placement. We report a rare case report of a 20-year-old man who developed tension pneumocephalus following implant removal from the spine. He responded well to the conservative treatment without any neurological complications.

Cryptococcal spondylodiscitis in a non-HIV patient with CD4 lymphocytopenia.

Infections that affect the intervertebral discs and vertebrae are known as spondylodiscitis. Such infections are commonly caused by pyogenic organisms, particularly Staphylococcus aureus, and hematogenous spread is the most common route. Non-pyogenic infections include Mycobacterium tuberculosis and Brucellosis. Mycotic infections are becoming more common, in line with the growing number of immunodeficiency disorders. Cryptococcus is included among these mycotic infections. We present a case of such an infection in a non-immunocompromised patient with a known history of treatment with antitubercular therapy. A 52-year-old man came to our hospital with a backache of one-month duration and progressive neurological deficits of the lower limbs of one-week duration. His imaging studies were suggestive of spondylodiscitis at the D10-11 and D11-12 levels with a left paraspinal abscess. The patient underwent anterolateral decompression, biopsy, and instrumented posterior spinal fusion. The pus grew Cryptococcus, and histopathology confirmed Cryptococcal spondylodiscitis. The patient was treated with parenteral amphotericin B and fluconazole. A mycotic infection must be considered in the differential diagnosis of infectious spondylodiscitis.

Melioidosis mimicking tubercular cold abscess.

Burkholderia pseudomallei is a Gram-negative bacillus found in soil. The infection is thought to occur by inoculation or inhalation. It usually affects people with predisposing factors like diabetes mellitus and chronic alcoholism. A 36-year-old man, on the treatment of diabetes in the past 4 years, on oral hypoglycaemic drugs, presented to us with pain and insidious onset of swelling over left loin like a lumbar cold abscess. He underwent incision and drainage of the abscess. As per the culture report, we used ceftazidime for 2 weeks, followed by cotrimoxazole for 6 months. Surgical drainage of large abscesses is indicated. A dedicated team of microbiologist and physicians is required to identify and treat the disease. Orthopaedic manifestations are uncommon.