hamstrings. Patients performed a step-ascent task onto an 18cm high block, and locomotion on a treadmill at a self-selected comfortable, and 30% faster walking speeds. Kinematic data were normalized to 0-100% of the weight acceptance phase for the step-ascent task (contralateral toe-off to contact), and the terminal swing phase for the locomotion task (87-100% of the gait cycle). Medians with 95% confidence intervals were generated for each dependent variable to allow for between-group comparisons. EMG signal amplitude for the step ascent task was expressed relative to an MVIC (%). Results: In the step task, there was a significantly greater tibial rotation in the MP (11.7  , 9.1 e 13.8) and PS (10.5  , 8.3 e 11.2) groups, compared with the CR (7.4  ,5 e 9.2) group (both p<0.01); there was no difference be- tween MP and PS groups. This difference was not apparent in each of the locomotion tasks. Interestingly, all groups produced a median internal rotation, which contradicted the screw-home mechanism. The MP knees displayed significantly (P<0.01) greater knee extensor activation (rectus femoris muscle) to achieve the step-ascent than the PS group. Conclusion: These findings suggest that patients with either knee implant types are not strictly limited to producing the traditional screw-home mechanism, as previously reported. The present findings also suggest that the MP design does not necessarily encourage greater range of rotational movement during locomotion. INCIDENCE OF DVT/PE BETWEEN ONE-STAGED BILATERAL AND UNILATERAL TKA USING CONTRAST ENHANCED CT AND VENOUS ULTRASONOGRAPHY IN JAPANESE PATIENTS - EDOXABAN AS CHEMICAL PROPHYLAXIS Atsushi Sato MD, PhD 1, 2 , Soshi Asai MD, PhD 2 , Fumiyoshi Kawashima MD 2 , Masahiko Maekawa MD, PhD 2 , Shin Kato MD, PhD 2 , Takayuki Koya MD, PhD 2 , Naoki Okuma MD 2 , Takayuki Okumo MD 2 , Jun Oike MD 2 , Yushi Hoshino MD, PhD 1, 3 , Kazunari Tomita MD, PhD 1, 3 , Hiroshi Takagi MD, PhD 2, 3 . 1 Department of Orthopedic Surgery, Showa University Koto Toyosu Hospital, Tokyo, Japan; 2 Department of Orthopedic Surgery, Showa University Fujigaoka Hospital, Yokohama, Japan; 3 Department of Orthopedic Surgery, Showa University School of Medicine, Tokyo, Japan Introduction & Aims: TKA is one of the most successful surgeries to relieve pain caused by severe arthritis. Otherwise, it is still controversial that there is higher risk of DVT/PE in one-staged bilateral TKA. Therefore, we investigated incidence of DVT/PE after primary TKA by enhanced CT and venous ultrasonography (US) in Japanese Patients. Method: One hundred fourteen patients who underwent primary TKA from January 2015 to June 2016 were applied. The mean age was 74.0 years. There were 105 cases of osteoarthritis and 7 of rheumatoid arthritis. A single knee surgery team performed all operations with cemented type prostheses. There were 47 cases of one-staged bilateral TKA and 67 of unilateral TKA. Enhanced CT and venous US were performed at the 4th day after surgery and images were read by a single senior radiologist team. Results: Enhanced CT was performed in 90 patients (78.9%) and US was in all patients. The incidence of DVT was 67 patients (58.7%) and PE was 11 patients (9.6%). Then we compared the incidence between one-staged bilateral TKA group and Unilateral group. DVT was 30 (63.8%) and 33 (49.2%) respectively. PE was eight (17.0%) and three (4.4%) respectively. There was significant high incidence of PE in one-staged bilateral group. All patients with DVT/PE had no symptoms. Conclusions: We prospectively investigated 114 patients for DVT/PE after primary TKA using enhanced CT and venous US. There was significant high incidence of PE in one-staged bilateral TKA group compared in unilateral group. THE EFFECT OF KNEE REPLACEMENT DESIGN & POLYETHYLENE TYPE ON REVISION RISK FOR INFECTION. AN ANALYSIS FROM THE AOANJRR. Christopher Vertullo 1, 2 , Michelle Lorimer 1 , Yi Peng 1 , Peter L. Lewis 1 , Richard de Steiger 1 , Stephen E. Graves 1 . 1 Knee Research Australia; 2 Centre for Musculoskeletal Research, Menzies Health Institute, Australia Introduction & Aims: Infection of Total Knee Replacements (TKRs) re- mains devastating for patients and an increasingly significant burden on health care systems. While both TKR design and polyethylene type can independently alter survivorship, their influence on infection revision risk is unknown. We examined the effects of TKR stability design and poly- ethylene bearing type on the long-term revision risk for infection in TKR by comparing Minimally Stabilized (MS) TKRs with Cross-Linked Poly- ethylene (XLPE) to MS TKRs with Non-Cross-Linked Polyethylene (NXLPE), Posterior Stabilized (PS) TKRs with XLPE and PS TKRs with NXLPE. Methods: National registry revision data for infection in primary TKR for osteoarthritis were obtained from Sept 1999 to Dec 2015 for 4 patient cohorts defined by the TKR design and polyethylene type received. Re- visions 6 months were censored. Analyses were stratified by age, sex and antibiotic cement usage. Results: There were 336997 included primary TKR of which 1651(0.48%) underwent revisions for infection. Compared to MS TKR-XLPE, the risk of revision for infection was 30% higher in MS TKR-NXLPE (HR¼1.30 (95% CI 1.14, 1.50) p<0.001), 97% higher for PS TKR-XLPE (HR¼1.97 (95% CI 1.60, 2.44) p<0.001), and 110% higher for PS TKR-NXLPE (HR¼2.10 (95% CI 180, 2.44) p<0.001). This effect was apparent in all males, all females, males  65 years, males  65 years, females  65 years and in those receiving antibiotic cement. Conclusion: MS TKR with NXLPE bearing surfaces and PS TKR irrespective of bearing type have a greater long-term revision risk for infection when compared to MS TKR with XLPE. WHAT IS THE BENEFIT OF OPTIMUM PROSTHESIS COMBINATION SELECTION IN TOTAL KNEE REPLACEMENT? AN ANALYSIS OF 482373 PROSTHESES FROM THE AUSTRALIAN ORTHOPAEDIC ASSOCIATION NATIONAL JOINT REPLACEMENT REGISTRY Christopher Vertullo 1, 2 , Stephen E. Graves 1 , Yi Peng 1 , Peter L. Lewis 1 . 1 Knee Research Australia; 2 Centre for Musculoskeletal Research, Menzies Health Institute Introduction & Aims: Decades of innovations in total knee replacement (TKR) have led to large number of design and technique options, each of which can alter the revision risk. It is unknown what the accumulative effect is when the lowest risk option in each category, or “optimum prosthesis combination” (OPC) is utilized. The purpose of this analysis was to firstly identify the OPC, secondly, to analyze the effects on revision risk when the OPC was utilized compared to a cohort of patients who received an alternative prosthesis combination (APC), and finally, iden- tify which patient age-sex cohorts had the greatest alteration in risk with the OPC. Methods: National registry revision risk data for primary TKR for osteo- arthritis were obtained from Sept 1999 to Dec 2015 for two patient cohorts, those receiving an OPC and those receiving an APC. OPC was defined as TKR that had the lowest revision risk option for six primary TKR design and technique categories; fixation, posterior stability, bearing mobility, bearing surface, alignment method and patella resurfacing, while APC had one or more higher-risk options. Results: Of the 482,373 included TKR, 31,404 (6.5%) were in the OPC cohort, which was a TKR with a cemented tibia, was minimally stabi- lized, fixed bearing, had cross-linked polyethylene, was undertaken with computer navigation if the patients were <65yo and had patella resurfacing. At 10-years, the OPC cohort had a CPR of 2.4% (95% CI 2.1, 2.8) compared to 5.4% (95% CI 5.4, 5.5) for the APC cohort. The revision risk of the APC cohort was higher at all times (132% greater at  2 years (p<0.001)), in all patient age and gender subgroups, with the greatest increase in risk in females 65 years. The APC cohort had a 35% higher risk of revision for infection than the OPC cohort at 1.5 years (p¼0.047). Conclusion: The optimum prosthesis combination concept represents a pragmatic clinical decision-making tool to aid in the identification of the lowest revision risk TKR ARE ROUTINE BLOOD TESTS REQUIRED AFTER TOTAL KNEE AND HIP ARTHROPLASTY? J.S. Mulford, N. Marson, R. Matthews, D. Lyons, J. Briffa, M. Habel, M. Free, I. Robertson. Launceston General Hospital, Launceston, Australia Introduction & Aims: Blood tests are routine in many institutions after Abstracts / Asia-Pacific Journal of Sports Medicine, Arthroscopy, Rehabilitation and Technology 13 (2018) 1e18 13