Kwok-Hing Chiu

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.

Osteonecrosis of the femoral head treated with cementless total hip arthroplasty. A comparison with other diagnoses.

Primary cementless Porous Coated Anatomic total hip arthroplasty was carried out in 36 hips in 29 patients with osteonecrosis (ON) patients and in 36 hips in 33 patients without ON. The ON was alcohol related in 11. steroid induced in 5, post-traumatic in 4, and idiopathic in 16 patients. The average follow-up period was 6 years. Clinical evaluation demonstrated 77.8% excellent or good results in the patients with ON, with the average Harris hip scores improved from 36.8 to 83.5. No revision of a prosthesis has yet been performed in the patients with ON. The patients with alcohol-related and steroid-induced ON had inferior clinical results when compared with the patients without ON. There were no statistically significant differences in the clinical results between the patients with post-traumatic or idiopathic ON and the patients without ON.

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.

Experience with primary exeter total hip arthroplasty in patients with small femurs: Review at average follow-up period of 6 years

One hundred twelve hips in 101 Chinese patients received a primary cemented Exeter total hip arthroplasty (Howmedica, Hong Kong). Average age was 65 years. The most common diagnosis was avascular necrosis. Average follow-up period was 6 years (range, 3 years to 9 years, 6 months). The Harris hip score improved from a preoperative average of 41.2 to 82.2 at the last follow-up visit. Stem subsidence within the cement mantle occurred in 9% of the cases, and none of these stems had other evidence of loosening. Three hips in two patients were revised because of loosening at 5 to 8 years after surgery. Because of the small size of the femurs, stem oversizing was common. Oversizing of the stem and an incomplete cement mantle might account for the early loosening. Stems of a smaller size should be made available to this population.

Pseudoaneurysm of the geniculate artery following total knee arthroplasty: a report of two cases.

We report 2 cases of pseudoaneurysm of the geniculate artery after a total knee arthroplasty (TKA). The first one was located in the superomedial geniculate artery and resolved after compression dressing and warfarin cessation. The second one was located in the superolateral geniculate artery and was successfully treated with transarterial embolisation. There was no recurrence in both cases. The rare occurrence and delayed presentation of pseudoaneurysms pose a diagnostic challenge. A high index of suspicion is required to make the diagnosis. Early duplex Doppler ultrasonography is recommended when patients present with atypical knee pain and prolonged swelling after a TKA.

Original articleExperience with primary exeter total hip arthroplasty in patients with small femurs: Review at average follow-up period of 6 years

One hundred twelve hips in 101 Chinese patients received a primary cemented Exeter total hip arthroplasty (Howmedica, Hong Kong). Average age was 65 years. The most common diagnosis was avascular necrosis. Average follow-up period was 6 years (range, 3 years to 9 years, 6 months). The Harris hip score improved from a preoperative average of 41.2 to 82.2 at the last follow-up visit. Stem subsidence within the cement mantle occurred in 9% of the cases, and none of these stems had other evidence of loosening. Three hips in two patients were revised because of loosening at 5 to 8 years after surgery. Because of the small size of the femurs, stem oversizing was common. Oversizing of the stem and an incomplete cement mantle might account for the early loosening. Stems of a smaller size should be made available to this population.

Exeter Small Femoral Stem for Patients with Small Femurs

Purpose. To report the long-term results of total hip arthroplasty (THA) using small size Exeter femoral stems. Methods. Eight men and 34 women aged 60 to 83 (mean, 70) years underwent 45 THAs using the Exeter small stem with offsets of 30 mm (n=3), 33 mm (n=15), and 35.5 mm (n=27). The Harris hip score was assessed pre- and post-operatively. Stem alignment and axial subsidence of the stem were measured. Radiolucent lines around the femur were recorded at 14 Gruen zones. Completeness and thickness of the cement mantle and cement fractures were also noted. Ectopic ossification, if present, was graded. Stem loosening was based on the Olsson definitions. Results. The mean follow-up was 9 (range, 5–12) years. The mean Harris hip score improved from 37 (range, 13–61) to 80 (range, 47–96) [p<0.001]. At the latest follow-up, the score was excellent (90–100) in 8 (18%) of the hips, good (80–89) in 21 (47%), fair (70–79) in 9 (20%), and poor (<70) in 7 (16%). All hips had a complete cement mantle of ≥2 mm. All stems were inserted without intramedullary reaming. 11 (24%) of the hips developed stem subsidence of <2 mm; all stabilised within 2 years. None of these patients had pain or other radiological signs of loosening. Six stems showed radiolucent lines of <1 mm in the upper zones, which were not progressive. No cement fracture or subsidence was noted. Using revision for any cause as an endpoint, the overall survival rate of Exeter small femoral stem was 100% at 10 years and 89% at 12 years. Conclusion. The results of Exeter small stems for patients with small femurs are good.

Effect of drain pressure in total knee arthroplasty

Purpose. To study the effect of drain suction pressure on drainage volume, decrease in haemoglobin level, blood transfusion, and wound complications following total knee arthroplasty. Methods. Primary total knee arthroplasty for degenerative osteoarthritis was performed in 60 (49 female and 11 male) patients. Patients were randomised for high-pressure (600 mm Hg) or low-pressure (350 mm Hg) postoperative suction drainage. Drain output was recorded daily and the drain removed after 48 hours. Postoperative haemoglobin level was measured on the evening of the operation day and on postoperative day 2. Results. The high-pressure group had a significantly higher drainage volume and decrease in haemogloblin level than the low-pressure group. However, there was no significant difference between groups in the transfusion rate, number of units of blood transfused, wound discharge, or Knee Society knee and function scores. No wound infection was detected in any patient. Conclusion. Low-pressure suction drainage results in less blood loss without a significant increase in wound complications.

Arthroscopy-Assisted Computer Navigation in High Tibial Osteotomy for Varus Knee Deformity

Purpose. To assess the accuracy of knee alignment after high tibial osteotomy (HTO) for varus knee deformity using arthroscopy-assisted computer navigation. Methods. Six men and 4 women aged 47 to 53 (mean, 49) years underwent medial open wedge HTO for varus knee deformity and medial unicompartmental osteoarthritis using arthroscopy-assisted computer navigation with fluoroscopy. Patients were followed up for a mean of 23 (range, 11–32) months. Intra- and post-operative leg alignments were compared. Results. The mean postoperative coronal plane alignment was 2.7 (range, 1–4) degree valgus; the mean deviation from intra-operative computer images was one (range, 0.1–1.9) degree; 5 knees had less valgus in the postoperative radiographs than the intra-operative computer images. Conclusion. Despite being more technically demanding, time consuming, and costly, arthroscopy-assisted computer navigation is safe, accurate, and reliable for HTO.

The Asian size Exeter femoral stem fracture.

The Exeter femoral stemwas in clinical use since 1970with good result [1]. The collarless, double tapered, polished design allows controlled subsidence of the femoral stem within the cement mantle. Adequate thickness of cement mantle is critical for the long-term success of Exeter femoral stem. However, the original design was aimed for Western population and stem oversizing was common in Asian population with small body build [2e4]. Smaller Asian size Exeter femoral stem was introduced to fit the Asian population. Smaller Asian size stems with 30 mm and 33mm offset have been made available since 1998. In view of the small size of the Asian stem, stem fracture is of concern. Herewe report a case of Asian size Exeter femoral stem fracture. Factors contributed to the stem fracture were discussed. Careful pre-operative planning and meticulous surgical technique should be employed when use of small stem. Biomechanical studies to define the weight limitation for the smaller Asian size Exeter femoral stem was recommended. The patient was informed that data concerning the case would be submitted for publication, and she consented.