Kwok Chuen Wong

Precision tumour resection and reconstruction using image-guided computer navigation

The use of a navigation system in musculoskeletal tumour surgery enables the integration of pre-operative CT and MRI images to generate a precise three-dimensional anatomical model of the site and the extent of the tumour. We carried out six consecutive resections of musculoskeletal tumour in five patients using an existing commercial computer navigation system. There were three women and two men with a mean age of 41 years (24 to 47). Reconstruction was performed using a tumour prosthesis in three lesions and a vascularised fibular graft in one. No reconstruction was needed in two cases. The mean follow-up was 6.9 months (3.5 to 10). The mean duration of surgery was 28 minutes (13 to 50). Examination of the resected specimens showed clear margins in all the tumour lesions and a resection that was exactly as planned.

Computer assisted pelvic tumor resection and reconstruction with a custom-made prosthesis using an innovative adaptation and its validation.

Computer aided musculoskeletal tumor surgery is a novel concept. Ideally, computer navigation enables the integration of preoperative information concerning tumor extent and regional anatomy to facilitate execution of a surgical resection. Accurate resection helps oncological clearance and facilitates precise fitting of a custom prosthesis. We adapted a commercially available computer navigation platform for spine, and used it to plan and execute pelvic bone resection and custom pelvic prosthetic reconstruction in a patient with a metastatic tumor affecting the acetabulum. The surgery was simulated and validated using a plaster bone model based on the patients preoperative CT data, before performing the procedure on the patient.

Joint-preserving Tumor Resection and Reconstruction Using Image-guided Computer Navigation

BackgroundJoint-preserving surgery is performed in select patients with bone sarcomas of extremities and allows patients to retain the native joint with better joint function. However, recurrences may relate to achieving adequate margins and there is frequently little room for error in tumors close to the joint surface. Further, the tumor margin on preoperative CT and/or MR images is difficult to transpose to the actual extent of tumor in the bone in the operating room.Questions/purposesWe therefore determined whether joint-preserving tumor surgery could be performed accurately under image-guided computer navigation and determined local recurrences, function, and complications.MethodsWe retrospectively studied eight patients with bone sarcoma of extremities treated surgically by navigation with fused CT-MR images. We assessed the accuracy of resection in six patients by comparing the cross sections at the resection plane with complementary prosthesis templates. Mean age was 17 years (range, 6–46 years). Minimum followup was 25 months (mean, 41 months; range, 25–60 months).ResultsThe achieved resection was accurate, with a difference of 2 mm or less in any dimension compared to that planned in patients with custom prostheses. We noted no local recurrence at latest followup. The mean Musculoskeletal Tumor Society score was 29 (range, 28–30). There were no complications related to navigation planning and procedures. There was no failure of fixation at the remaining epiphysis.ConclusionsIn selected patients, the computer-assisted approach facilitates precise planning and execution of joint-preserving tumor resection and reconstruction. Further followup assessment in a larger study population is required in these patients.Level of EvidenceLevel IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Transmission and Prevention of Occupational Infections in Orthopaedic Surgeons

Microorganisms are transmitted in hospitals mainly by contact, droplet, and airborne routes. Orthopaedic surgeons have a substantial occupational risk of contracting a blood-borne infection because of frequent handling of sharp instruments and objects during operative procedures. Aerosolization means the formation of aerosols and droplets when blood or other body fluids are mechanically disturbed. Smaller particles (<5 microm) will remain suspended in air. Pathogens that can survive in these small airborne particles may cause infection if they are inhaled. Aerosol-generating procedures in patients with tuberculosis or severe acute respiratory syndrome (SARS) may facilitate airborne transmission. The Hospital Infection Control Practices Advisory Committee and the Centers for Disease Control and Prevention have established guidelines for isolation precautions in hospitals.

Comparison of the anti-tumor effects of denosumab and zoledronic acid on the neoplastic stromal cells of giant cell tumor of bone

Abstract Denosumab and Zoledronic acid (ZOL) are two antiresorptive drugs currently in use for treating osteoporosis. They have different mechanisms of action but both have been shown to delay the onset of skeletal-related events in patients with giant cell tumor of bone (GCT). However, the anti-tumor mechanisms of denosumab on the neoplastic GCT stromal cells remain unknown. In this study, we focused on the direct effects of denosumab on the neoplastic GCT stromal cells and compared with ZOL. The microscopic view demonstrated a reduced cell growth in ZOL-treated but not in denosumab-treated GCT stromal cells. ZOL was found to exhibit a dose-dependent inhibition in cell growth in all GCT stromal cell lines tested and cause apoptosis in two out of three cell lines. In contrast, denosumab only exerted a minimal inhibitory effect in one cell line and did not induce any apoptosis. ZOL significantly inhibited the mRNA expression of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) in two GCT stromal cell lines whereas their protein levels remained unchanged. On the contrary, denosumab did not regulate RANKL and OPG expression at both mRNA and protein levels. Moreover, the protein expression of Macrophage Colony-Stimulating Factor (M-CSF), Alkaline Phosphatase (ALP), and Collagen α1 Type I were not regulated by denosumab and ZOL either. Our findings provide new insights in the anti-tumor effect of denosumab on GCT stromal cells and raise a concern that tumor recurrence may occur after the withdrawal of the drug.

Use of a patient-specific CAD/CAM surgical jig in extremity bone tumor resection and custom prosthetic reconstruction

Computer navigation has recently been introduced for bone tumor surgery in the orthopedic field, with the aim of achieving increased accuracy and precision in tumor resection and in custom prosthetic reconstruction. However, the technique requires bulky navigation facilities, the presence of a system operator in the operating room, and surgeons with prior experience in navigated surgery. We describe a new and simple method of using a patient-specific computer-aided design/computer-aided modeling (CAD/CAM) surgical jig to realize the preoperative planning in the surgical field. The accuracy of the proposed method was first tested in a cadaver trial. It took one minute to set the location of the jig prior to the bone resection and three minutes to perform the bone resections via the cutting slits of the jig. The dimensional difference between the achieved and planned bone resection was <1 mm on validation with the help of a junctional plate and a navigation system. The technique was then applied successfully to a patient with a low-grade osteosarcoma of the femur. An intercalated tumor resection was performed using a patient-specific surgical jig, and a custom CAD prosthesis reconstruction matched accurately to the skeletal defect. Further assessment in a larger population is necessary to determine the clinical efficacy of the technique.

Integration of CAD/CAM planning into computer assisted orthopaedic surgery.

Modern Computer Aided Design/Modeling (CAD/CAM) software allows complex surgical simulations, but it is often difficult to transfer and execute precisely the planned scenarios during actual operations. We describe a new method of integrating CAD/CAM surgical plans directly into a computer surgical navigation system, and demonstrate its use to guide three complex orthopaedic surgical procedures: a periacetabular osteotomy of a dysplastic hip, a corrective osteotomy of a post-traumatic tibial deformity, and a multi-planar resection of a distal femoral tumor followed by reconstruction with a CAD custom prosthesis.

Severe Acute Respiratory Syndrome (sars) In A Geriatric Patient With A Hip Fracture: A Case Report

In March 2003, there was an outbreak of atypical pneumonia in Hong Kong. The World Health Organization (WHO) has termed the illness severe acute respiratory syndrome (SARS). The disease is highly contagious and has spread rapidly throughout the world. Globally, there were more than 3000 reported cases and 154 related deaths as of April 14, 2003 1. We report a case of an eighty-one-year-old woman who sustained an intertrochanteric fracture. Her postoperative course was complicated by a suspected aspiration pneumonia. She did not have the typically reported clinical features of SARS or a definite history of contact with a patient with SARS. She died of severe respiratory failure. An autopsy showed typical findings of SARS. An eighty-one-year-old woman who resided in a home for the elderly had a history of chronic obstructive airway disease. She had no history of contact with a SARS patient. She was admitted to the orthopaedic ward after a fall on March 16, 2003. Radiographs of the left hip showed a comminuted intertrochanteric fracture. A closed reduction and Asiatic Gamma nail fixation was performed with the patient under spinal anesthesia one day after admission. The operation was uneventful and was completed in forty-five minutes. Postoperatively, the patients dentures were missing, and a radiograph of the chest was made to rule out aspiration. The radiograph showed only a hyperinflated lung. On the first postoperative day, oxygen desaturation and mild shortness of breath developed. A chest radiograph revealed bilateral pulmonary infiltrates in the middle and lower lobes ( Fig. 1 ). A pulmonary medicine consultation was obtained on the second postoperative day, and a provisional diagnosis of aspiration pneumonia was made on the basis of the episode of suspected aspiration. The clinical picture did not suggest SARS in view of leukocytosis (a leukocyte count of 14 × …

Use of Computer Navigation in Orthopedic Oncology

Abstract The use of computer navigation was first described in the surgical resection of pelvic tumors in 2004. It was developed to improve surgical accuracy with the goal of achieving clear resection margins and better oncologic results. During the past few years, there has been tremendous advancement of computer-assisted tumor surgery (CATS) in the field of orthopedic oncology. Currently, CATS with image fusion offers preoperative three-dimensional surgical planning and allows surgeons to reproduce the intended bone resections in musculoskeletal tumors. The technique is reported to be useful in technically demanding resections, such as in pelvic and sacral tumors; joint-preserving intercalated and multiplanar tumor resection; and complex reconstruction with custom computer-aided design prostheses or allografts. This article provides an up-to-date review of the recent developments and key features in CATS, its current status in clinical practice, and future directions in its development.

Navigation Endoscopic Assisted Tumor (NEAT) surgery for benign bone tumors of the extremities

A novel technique of using both a navigation system and an endoscope in intra-lesional curettage of benign bone tumors enables safe and adequate tumor removal via a minimal access approach. We performed curettage of benign bone tumors in five consecutive patients (4 female, 1 male, mean age 31.4 years) using a commercial CT-based navigation system supplemented by visual guidance through a shoulder arthroscope. The bone defect was filled with bone cement in four patients and with artificial bone substitute in one patient. Mean follow-up time was 8.8 months (range: 7–12 months). Mean duration of surgery was 144 min (range: 120–165 min). Mean wound length of each portal site was 19.5 mm (range: 15–25 mm). All patients could achieve a full range of joint movement and walk unaided at 4 weeks post-surgery. No local recurrence was noted.