Extra Free Paper

EFP1: Fournier's gangrene: A 10-year review and validation of mortality predictors in a Hong Kong major regional centre

BYO Chan, BWB Wong and CTY Tse

Department of Surgery, Tuen Mun Hospital, Tsing Chung Koon Road, Tuen Mun, New Territories, Hong Kong

Aim: Fournier’s gangrene is a surgical emergency necessitating urgent debridement and aggressive antimicrobials. Early recognition of high-risk patients enable timely critical care utilization. Controversies existed in scoring systems like Fournier Gangrene Severity index (FGSI), Uludag FGSI and simplified FGSI. No local data is available on their applicability and valid prognosticating factors, hence our study aiming to improve triage and mortality.

Methods: Fifty patients with Fournier’s gangrene from 2006 to 2015 were retrospectively reviewed. Baseline demographics, physiologic and laboratory values, management options, also parameters in established scoring systems were compared between survivors and non-survivors via univariate analyses. ROC curve analysis was performed to evaluate the diagnostic performance of three aforementioned scores.

Results: Mortality was 20%, compatible with international literature. Non-survivors had higher median age (63 vs 53, p=0.05), smoking (70% vs 30%, p=0.03), diabetes (80% vs 38%, p=0.03), immunosuppression (100% vs 68%, p=0.046), orchidectomy (30% vs 2.5%, p=0.022), higher serum creatinine (1.2mg/dL vs 0.91mg/dL, p=0.042) and lower haematocrit (31% vs 36%, p=0.006). Defunctioning stoma and suprapubic catheterization were not useful in reducing mortality. For scoring systems, no significant difference in translated score levels was seen. ROC curve analysis showed low AUC 0.588 for sFGSI, whereas that for FGSI and UFGSI were 0.798 and 0.833 respectively, but not statistically significant.

Conclusion: Elderly, smokers, diabetics or immunocompromised, higher creatinine or lower haematocrit level and patients requiring orchidectomy indicate poorer prognosis and may benefit from intensive care. Current scoring systems either perform poorly or have troublesome frontline application. This represents the first local study of such intent.

EFP2: Exploring the effect of hospital-volume on outcome of elective major hepatectomy in Hong Kong

YS Cheung, AHM Chan, CCN Chong and PBS Lai

Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong Prince of Wales Hospital, 30-32 Ngan Shing Street, Shatin, New Territories, Hong Kong

Aim: To evaluate the effect of hospital-volume on the operative outcomes in elective major hepatectomy in Hong Kong.

Methods: Retrospective analysis was performed by extracting data from the Surgical Outcome Monitoring and Improvement Program reports of Hospital Authority from July 2009 to June 2016. Hospital-volume was defined as the number of elective major hepatectomy performed annually in each hospital. Primary endpoint was 30-day mortality. Secondary endpoints were 30-day morbidity, operative blood loss and length of hospital stay. Relationship between hospital-volume and operative outcomes was plotted by scattered-plot. The cut-off value that define high-volume hospital was estimated by comparing the hospital volume and 30-day mortality rate.

Results: 2,389 elective major hepatectomy cases were included. 51 patients died after operation and thus the 30-day mortality rate over the 7-year period was 2.13%. An inverse relationship between hospital-volume and 30-day mortality rate was observed (P-value = 0.0107). By using annual hospital-volume of 40 or more major hepatectomy as cut-off, high volume hospitals had significantly lower mortality rate (odds-ratio = 2.23, P-value = 0.005) and managed to keep the mortality rate consistently below 5%. The 30-day morbidity rate (P-value < 0.001) and length of stay (P-value = 0.027) were also significantly better in high volume hospitals. No significant difference was observed in operative blood-loss among hospitals.

Conclusion: An inverse relationship between hospital-volume and operative outcome in major hepatectomy was observed in Hong Kong. Hospitals with 40 or more major hepatectomy per year were associated with lower mortality, morbidity and shorter length of stay.

EFP3: The use of biodegradable stent in peripheral arterial diseases: A systematic review of current evidence

L Chu¹ and YC Chan²

¹Department of Medicine, Nursing and Health Science, Monash University, Victoria, Australia

²Division of Vascular & Endovascular Surgery, Department of Surgery, University of Hong Kong Medical Centre, South Wing, 14^th Floor K Block, Queen Mary Hospital, Hong Kong

Introduction: For the last decade, the use of biodegradable stent has been intensely studied. With a major benefit of disappearing completely overtime, it appears to be an ideal treatment that circumvents the chronic local inflammatory reaction seen in traditional metal stents. The aim of this paper is to examine the published literature on the use of biodegradable stents in the treatment of peripheral arterial diseases (PAD).

Methods: Systematic review was formulated under the instruction of PRIMSA guideline. A computerized search with PubMed, ProQuest central and Ovid MEDLINE, with a filter to show only studies published between January 2005 and March 2015 that were written in English. The search focused on the use of biodegradable stent in the treatment of peripheral vascular diseases (PAD) using relevant keywords. On-going studies from other electronic databases were also examined.

Results: A total of 75 non-duplicated publications were identified but only 6 articles were eligible into our qualitative analysis (one animal study, 3 case-cohort studies, and 2 randomised studies). In total, 325 stents were used in 282 patients. Technical success rates were 100%. These studies had a short to medium follow-up period up to 58 months. The primary and secondary patency rates were 60.8% (range 32-77%) and 88.4% (range 79-97%) respectively. There are also four on-going studies internationally.

Conclusions: Current published literature suggests that biodegradable stent is safe and effective in the treatment of PAD, but these studies were heterogeneous and were limited by their study design, small sample size, and short follow-up period; and therefore do not produce a sufficient level of evidence to show its superiority over traditional treatments.

Keywords: biodegradable scaffolds, biodegradable stents, angioplasty, femoral, lower limb, peripheral arterial disease, peripheral vascular disease.

Conflict of Interest Declaration

No conflict of interests declared. No funding or financial gains received.

EFP4: Case-matched study on clinical and radiological characteristics of mammary phyllodes tumor and fibroadenoma

M Co,^1,2 JN Wei,² V Man,¹ B Mark,¹ C Chen,¹ D Suen¹ and A Kwong^1,2

¹Department of Surgery, The University of Hong Kong

²Division of Breast Surgery, The University of Hong Kong Shenzhen Hospital

Introduction: Phyllodes tumor (PT) and fibroadenoma (FA) are frequently diagnosed as fibroepithelial lesion pre-operatively by core biopsy. They share similar clinical characteristics. However the clinical behavior and prognosis can be very different. This study aims to compare the clinical and radiological characteristics of PT and FA.

Methods: The data of patients treated for PT from July 2013 to June 2016 were retrieved from a prospectively-maintained database. These patients were then compared with 70 consecutive case-matched patients for age with FA treated in 2015.

Results: 78 patients were treated for PT. 66 PTs (84.6%) were benign, 9 (11.5%) were borderline and 3 (3.8%) were malignant. The median age was 36 (Range 20–56). 70 case-matched patients with FA were recruited for comparison. The median age was 33 (Range 19-53).

20 (25.6%) PT patients vs. 2 (2.9%) FA patients had known history of benign breast disorders (P < 0.001). 54 (69.2%) PT patients vs. 5 (7.1%) FA patients were diagnosed as fibroepithelial lesion in pre-operative core needle biopsy (P < 0.001).

PT and FA share similar pre-operative sonographic appearances such as edge regularity, homogeneity, echogeneity and presence of posterior enhancement/shadowing (P > 0.05). However, PT is associated with presence of internal microcalcifications (P = 0.004). Median size of PT was 27mm (Range 13 – 130mm) which is significantly larger than FA - 17mm (Range 7 – 45mm) (P < 0.001).

Conclusion: PT and FA share similar sonographic appearance, although PT tends to be larger in size. As a result, excision is warranted in large (>2cm) fibroepithelial lesions even if they look sonographically-benign.

EFP5: Early experience of Transoral Endoscopic Thyroidectomy Vestibular Approach (TOETVA) in Hong Kong

W Day

Aim: To assess the feasibility and the safety of Transoral Endoscopic Thyroidectomy Vestibular Approach (TOETVA)

Method: The prospective study was performed during the period between October 2016 and May 2017 in the Hong Kong Baptist Hospital. All operations were performed by a single experienced laparoscopic surgeon.

We selected patients with a) Nodule size not larger than 5cm; b) benign colloid nodule; c) follicular lesion; d) Papillary microcarcinoma of thyroid; e) atypical cell. Exclusion criteria include patients who were a) unfit for general anaesthesia; b) previous thyroidectomy; c) thyroid carcinoma with lymph node metastasis and d) poor oral hygiene.

Results: Ten patients who met the selection criteria were selected to undergo Transoral endoscopic thyroidectomy vestibular approach (TOETVA). Eight patients had hemithyroidectomy for benign lesion, and two patients had total thyroidectomy for papillary carcinoma and microcarcinoma. The median operative time was 170mins (150-208mins). Blood loss less than 50ml. One case was converted to open. The mean hospital stay after operation is 1.4 day (1-3days). No complications such as hoarseness, haemorrhage and hypocalcaemia was identified. However, all patients had temporary loss of pain sensation over the chin after the surgery.

Conclusion: TOETVA is a safe endoscopic approach for thyroidectomy in selected cases.

EFP6: Indentification of HO1 as a novel biomarker for rejection and prognosis prediction after liver transplantation based on iTRAQ quantification

JJ Jia,^1,2,3 L Geng^1,2,3 and SS Zheng^1,2,3

¹Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, 310003, Hangzhou, China

²Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health; Department of Hepatobiliary Surgery, the First Affiliated Hospital, Zhejiang University, College of Medicine, Hangzhou, 310003, P. R. China

³Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou 310003, China

This work was supported by National Natural Science Major Project of China (No.915422058); Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No.81421062); National Natural Science Foundation of China (No.81373160); China Postdoctoral Science Foundation (2017M610374).

Background: Liver transplantation (LT) is the most effective treatment for patients with end-stage liver diseases, but allograft failure caused by rejection is still a major concern. Operational tolerance after LT has long been recognized in a proportion of recipients. However, the mechanisms underlying tolerance or rejection are still unknown and biomarkers are needed to predict rejection and long-term survival.

Methods: iTRAQ-based mass spectrometry was performed to analyze the proteome profile differences between transplant recipients with operational tolerance (n=3) and allograft rejection (n=3). Bioinformatics analysis was applied to identify the molecular signature of rejection and find the potential biomarkers. The selective candidate proteins were validated by immunohistochemistry in tissue microarray consisted of biological specimens from rejection patients (n=83) and liver function stable patient (n=59), further by western blot and immunofluorescence.

Results: With iTRAQ-based technology, a total of 3982 proteins were identified. Among these, 287 proteins were differentially expressed (fold change >1.2 or <0.8, P<0.05). Gene Ontology(GO) annotation analysis showed the up-regulated proteins (173 proteins) were mainly enriched in immune response and biological regulation while down-regulated proteins (114 proteins) mainly involved in metabolic process. Pathway analysis revealed that intergrin signalling pathway, inflammation mediated by chemokine and cytokine signalling pathway, T/B cell activation et al. significantly correlated with liver allograft rejection. HMOX1 (fold chang=1.7, P <0.05) was identified as candidate protein for rejection prediction. Immunohistochemistry, western blot and immunofluorescence confirmed the high expression of HMOX1 in rejection specimens, and immunohistochemistry of tissue microarray showed high expression of HMOX1 was associated with poor survival rates during 10-year follow-up.

Conclusions: 287 differentially expressed proteins were indentified in liver operational tolerance and rejection patients. Furthermore, the expression of HMOX1 was a novel biomarker for rejection and prognosis prediction, but still need more studies.

Keywords: liver transplantation, rejection, operational tolerace, HMOX1, iTRAQ

EFP7: Comparison of peri-operative and early post-operative outcomes of transurethral prostatic surgeries between specialists and non-specialists

KM Lai,¹ PK Chiu,² CH Yee,¹ HM Wong,³ CK Chan,¹ ES Chan,¹ CF Ng,¹ SS Hou¹ and JY Teoh¹

¹Division of Urology, Department of Surgery, Prince of Wales Hospital, Hong Kong

²Division of Urology, Department of Surgery, Alice Ho Miu Ling Hospital, Hong Kong

³Division of Urology, Department of Surgery, North District Hospital, Hong Kong

Aim: To compare the peri-operative and early post-operative outcomes of transurethral prostatic surgeries between specialists and non-specialists.

Methods: Data from the Surgical Outcomes Monitoring and Improvement Program (SOMIP) on transurethral prostatic surgeries, including monopolar and bipolar transurethral resection of the prostate (TURP), laser-assisted TURP, and transurethral electrovaporization of the prostate, performed at Prince of Wales Hospital, North District Hospital and Alice Ho Miu Ling Hospital from year 2010 to 2015 were reviewed. Peri-operative and early post-operative outcomes within 30 days between specialists and non-specialists were compared.

Results: From 2010 to 2015, 1786 patients underwent transurethral prostatic surgeries, with 935 in the specialist group and 851 in the non-specialist group. Patients in the non-specialist group were significantly older (73.29±8.602 vs 71.75±8.273; p<0.001). More patients had history of cerebrovascular accidents (12.1% vs 8%; p=0.004) in the non-specialist group. Operation time in the specialist group was significantly shorter than the non-specialist group (58.03±37.91 minutes vs 61.58±32.06 minutes; p=0.032). For the 30-day post-operative complications, there were no significant differences in systemic sepsis, need of blood transfusion or any adverse events involving the cardiac, respiratory, renal, gastrointestinal, and central nervous system.

Conclusion: Our results showed that specialists were able to complete transurethral prostatic surgeries slightly faster than non-specialists. However, peri-operative and early post-operative outcomes of transurethral prostatic surgeries between specialists and non-specialists were comparable.

EFP8: Intra-operative neuromonitoring versus visual identification of recurrent laryngeal nerve in robotic thyroidectomy: A comparative study

SY Lee, CY Law, CY Choi and CN Tang

Department of Surgery, Pamela Youde Nethersole Eastern Hospital, HKSAR

Aim: Robotic thyroidectomy is gaining popularity but some studies showed a higher incidence of recurrent laryngeal nerve (RLN) injury. Intra-operative neuromonitoring (IOMN) has been introduced to aid preservation of RLN and prevent nerve palsy. Our study aims to investigate the effectiveness of IOMN in robotic thyroid surgeries.

Methods: This is a retrospective study of a prospectively collected database of robotic thyroidectomy performed in our Surgical Department between the period Nov 2014 to Jul 2016. We compared two cohorts of patients, non-IOMN group with visual identification of recurrent laryngeal nerve and the others applied IOMN. Patient demographics and surgical outcomes were analyzed.

Results: There were a total of 42 robotic thyroidectomies included with 21 patients in each group. Mean specimen weight in IOMN was 19.7gm (5-66gm) and 21.0gm (8-50gm) in non-IOMN group. In the IOMN group, all 25 RLN were identified and preserved. In the non-IOMN group, 2 out of 24 RLN were not seen during surgery (p=0.235). 2 patients had vocal cord palsy documented by laryngoscopy in IOMN group and none in the non-IOMN group (p=0.49). Mean operative time was shorter in IOMN group (mean 160mins) than non-IOMN group (mean 202 mins), p=0.0026. Mean blood loss and mean length of hospital stay was similar, 1.9 days versus 1.95 days (p=0.78)

Conclusion: Our study shows that IOMN may help in identification of RLN but the results also echoes with current literature that IOMN does not reduce incidence of RLN palsy. It has an additional benefit of reducing operative time.

EFP9: New lipid emulsion formula improves parenteral nutrition related morbidty and mortality in paediatric short gut syndrome

YT Lee, PHY Chung, KKY Wong and PKH Tam

Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong

Purpose: The objective of this study was to compare the clinical outcomes in paediatric patients with short bowel syndrome (SBS) who were treated with long term parenteral nutrition (PN) according to two different eras over the past 20 years during which the lipid emulsion formula has changed.

Methods: This is a single-centred retrospective study from 1996-2016. Pediatrics patients with SBS who have received PN for more than 2 weeks were reviewed (n=43). The clinical outcomes of PN used in different eras (I: 1996-2006 ; II 2007-1996) were compared. In Era 1, the PN lipid was intra-lipid (soybean based) while in era II, PN lipid has been changed to SMOFlipid (combination of soybean, MCT oil, olive oil and fish oil) and Omegaven (fish-oil based formula) . In Era 2, 5 patients and 11 patients received either SMOFlipid and Omegaven respectively; 3 patients received both SMOFlipid and Omegaven.

Results: In Era 1, there were 16 patients with an average birth age being 37.1 months while in Era 2, there were 31 patients with an average birth age being 31.1 months. In both eras, necrotising enterocolitis was the most common diagnosis(I: 75% vs II: 85.7%, p=0.32). The median length of bowel remained was shorter in Era 2 (I: 50cm vs II: 31cm ,p=0.08) and the preservation of ileocecal valve is more frequent in Era 2 (I: 56.3% vs II:76.2%, p=0.25). There was no significant difference in the average duration of TPN dependence (I: 19.6 months vs II: 20.7 months, p=0.81). The occurrence of cholestasis after long term TPN use (defined as >2 weeks use) remains high in Era 2 (I: 93.8% vs II: 100%,p=0.94) but the peaked bilirubin level in the second era was lower than the first era (median value I: 123 umol/L vs II: 68 umol/L,p=0.10). In addition, there was an improvement in the overall survival rate in the second era (I: 43.8% vs II: 90.5%,p=0.07), with considerable reduction in PN-related mortality (I: 43.8% vs II: 9.5%,p=0.05).

Conclusion: With the advancement PN formula, its related mortality has decreased significantly, together with a reduction in the peak bilirubin level. Although the pathophysiology of PN-related cholestasis is yet to be unravelled, it is hoped that the addition of newer lipid formula will reverse fatal complication of PN and allow its long term use in short gut syndrome.

Keywords: parenteral nutrition, short gut syndrome, PN related liver injury

EFP10: Hybrid operation for pediatric head and neck vascular anomaly: Experience in tertiray referral center in Hong Kong

CSW Liu, MF Li, WS Hung, LY Chung, SD Yam, CL Leung, MY Tang, ^HS Fung, ^WL Poon, WY Leung and KKW Liu

Division of Pediatric Surgery, Department of Surgery, United Christian and Queen Elizabeth Hospital

^Department of Radiology and Imaging, Queen Elizabeth Hospital

Aim: Vascular anomalies typically appear at head and neck region and cause significant functional and aesthetic problems. Multidisciplinary team approach to these patients is mandatory. Single-stage hybrid operation, combining embolization and surgical resection in the endovascular operation room (EVOR), is a novel technique to enhance complete removal. Our aim is to review our hybrid operation experience for pediatric head and neck vascular anomalies.

Methods: From 8/2012 to 6/2017 period, medical records of pediatric patients with head and neck vascular anomalies treated by hybrid operation were reviewed. Validated satisfaction with outcome and facial appearance questionnaires (FACE-Q^TM) were completed by patient and/or their parents in 6/2017 to assess patient-centered outcome.

Results: 10 consecutive patients were recruited. 6 had lip venous malformation, 2 had face/ scalp non-involuting hemangioma, 1 had chin venous malformation and 1 had pinna venous malformation. Median age of operations was 13.5 years old. Median follow up duration was 18.5 months. Median blood lost was 7.5ml. 8 patients had undergone previous image guided sclerotherapy; with median number of previous sclerotherapy sessions of 2.5. All patients had complete/ near- removal of the vascular lesions. Only 1 patient required one further revision surgery. No complications or functional deficits were encountered. Questionnaire response rate was 100%. All parents/ patients were satisfied with the outcome with median overall satisfaction with outcome and appearance score of 20.5/ 24 and 32/ 40 respectively.

Conclusion: Hybrid operation is feasible for localized pediatric head and neck vascular anomalies. Near complete removal can be achieved with satisfactory functional and aesthetic outcome.

EFP11: Endovenous radiofrequency ablation versus cyanoacrylate embolization for lower limb varicose veinsEarly experience from a regional center

JK Shum, CT Lam, KW Leung and TL Chow

Department of Surgery, United Christian Hospital, Kwun Tong, Hong Kong

Aim: This study aimed to compare outcomes in patients with lower limb varicose veins due to great saphenous vein incompetence who underwent either endovenous radiofrequency ablation (RFA) or endovenous cyanoacrylate embolization (Venaseal).

Methods: This is a retrospective comparative study including patients who underwent RFA or Venaseal at our center from December 2015 to May 2017. Baseline patient characteristics, venous anatomy, VCSS (Venous Clinical Severity Score), peri-operative outcomes and postoperative outcomes including clinical recurrence, pain score, and post-operative VCSS were compared. Patients were followed up at 1 month and subsequently at 3-6 month intervals thereafter.

Results: 32 patients underwent RFA, and 11 patients underwent Venaseal, with 35 legs in the RFA group and 15 legs in the Venaseal group. Median follow up for RFA group was 7.5 months and 4 months for Venaseal group (p<0.05). Baseline patient characteristics, great saphenous vein diameter and distance from skin, preoperative VCSS (RFA 5.63 vs Venaseal 6.22, p=0.57), CEAP clinical classification (p=0.23) were comparable. Operative time and blood loss were also comparable. Postoperative pain score by the Visual Analogue Score was significantly lower in the Venaseal group (1.34 vs 0.20, p<0.01). Post-operative complication rates (RFA 5% vs Venaseal 0%, p>0.99), were comparable. Post-operative VCSS scores were comparable (p=0.13) and both groups have significantly lower post-operative VCSS scores compared with preoperative scores (RFA 1.59 vs 5.63, p<0.01, Venaseal 2.67 vs 6.22, p<0.01). There was no clinical recurrence detected.

Conclusion: Our early results show cyanoacrylate embolization for lower limb varicose veins offers comparable outcomes to radiofrequency ablation.

EFP12: Do elderly breast cancer patients have poorer survival outcome?

DTK Suen and A Kwong

Division of Breast Surgery, Department of Surgery, The University of Hong Kong Li Ka Shing Faculty of Medicine, Hong Kong SAR

Aim: This study is to compare breast cancer in elderly patients to their younger counterparts, and to look for factors affecting the survival of elderly patients

Methods: A retrospective study of breast cancer patients who have undergone surgery in a university hospital from January 2000 to December 2015 was performed. Stage on presentation, tumor characteristics and modalities of treatment for patients aged 70 and above were compared with those aged below 70. Factors affecting the overall survival were assessed by multivariate cox regression.

Results: 3825 patients with breast cancer underwent surgery during the study period. 510 patients (13.3%) were aged 70 and above. Elderly patients presented with tumors larger in size (p=0.002) and less HER-2 oncogene overexpression (p=0.007). More elderly patients had mastectomy (p=0.000), neoadjuvant (p=0.000) and adjuvant hormonal therapy (p=0.001). Elderly patients received less adjuvant radiotherapy (p=0.000), neoadjuvant (p=0.000) and adjuvant chemotherapy (p=0.000). The 5 year overall survival for elderly patients is 76.9%, which is poorer than their younger counterparts 89.5% (p=0.000). By multivariate analysis, adjuvant hormonal therapy (p=0.001, HR 0.564), T3 (p=0.014, HR 3.169), T4 (p=0.004, HR 3.877), N2 (p<0.001, HR 2.655) and N3 (p=0.003, HR 2.224) were the independent factors affecting the overall survival in elderly patients.

Conclusion: Elderly breast cancer patients had worse survival. Stage on presentation and use of adjuvant hormonal therapy are independent factors affecting the survival in elderly patients. Early diagnosis and comprehensive geriatric assessment to guide the optimal treatment plan would be useful for better survival outcome in elderly breast cancer patients.

EFP13: Systematic review of percutaneous mechanical thrombectomy in the treatment of acute iliofemoral deep vein thrombosis

PC Wong, YC Chan, Y Law and SW Cheng

Division of Vascular & Endovascular Surgery, Department of Surgery, University of Hong Kong Medical Centre, South Wing, 14^th Floor K Block, Queen Mary Hospital, Hong Kong.

Aim: To review the clinical efficacy and safety of percutaneous mechanical thrombectomy (PMT) against catheter-directed thrombolysis (CDT) in the treatment of acute iliofemoral DVT.

Method: This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. Three hundred and sixty-nine articles were identified through screening in the PubMed, EMBASE and Cochrane database from Jan 2006 to Dec 2016.

Results: Fifteen retrospective studies and one prospective registry, totaling 1170 patients, were recruited into qualitative synthesis. The venous patency rate ranged from 75-100% with a mean follow-up of 12.3 months. The rate of PTS and recurrent DVT were less than 17% and 15% respectively. The overall mortality rate was 0.26%. Compared with CDT, PMT was shown to reduce PTS at 1 year (Villalta scale 2.1+/-3.0 in PMT group and 5.1+/-4.1 in CDT group, p = 0.03) and bleeding complications (Packed cells transfusion 0.2+/-0.3 units in Pharmacomechanical thrombectomy group and 1.2+/-0.7 units in CDT group, p <0.05).

Conclusion: PMT appeared to be a safe and effective treatment for acute iliofemoral DVT in terms of restoration of venous patency, prevention of DVT recurrence and PTS. Compared with CDT alone, PMT offered lower risk of PTS and bleeding complications.

EFP14: Biomechanical study of mineralized collagen incorporated in polymethylmethacrylate in hip arthroplasty

ZB Zheng, Y Zhao and XS Weng

Department of Orthopedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No.1 Shuaifuyuan Wangfujing Dongcheng District,Beijing 100730, China.

Aim: Whether the biological active mineralized collagen(MC)-PMMA bone cement has different biomechanics with polymethylmethacrylate (PMMA) bone cement in early stage of total hip arthroplasty.

Methods: Choosing 10 matched pairs of femur specimen, excluding fractures, tumors and congenital malformations and other diseases. Performing artificial hip arthroplasty with cemented femoral prosthesis. Each paired femur specimens, one side using Classical PMMA Bone Cement (C-PMMA), on the other side using the MC-PMMA bone cement, making sure the same operative procedure. 10 pairs femur were randomly divided into A, B two groups of 5 pairs, until the bone cement completely solidified hardening, group A perform the pull-out experiment and group B perform torsion experiments by using mechanical testing machine. Record the displacement, angle, torque and the maximum loading of femoral prosthesis. The experimental data using SPSS22 statistical software to processe paired t test.

Results: The results show that C-PMMA bone cement group and MC-PMMA bone cement group pull-out test and torsion test of femoral prosthesis in displacement, maximum pullout force, maximum displacement of 250N pulling-out, 8 N • m of torsion angle, destruction torsion angle and destruction torque have no significant difference (p>0.05).

Conclusions: Experimental results show that there is no significant difference between the mineralized collagen incorporated in polymethylmethacrylate bone cement and the polymethylmethacrylate bone cement in artificial hip arthroplasty. Since the MC-PMMA bone cement having a suitable elastic modulus, good biological activity and osteogenic activity, we provide more choices for artificial hip arthroplasty in using bone cement.

Keywords: mineralized collagen, biologically active bone cement, biomechanics, hip arthroplasty