Genu Recurvatum versus Fixed Flexion after Total Knee Arthroplasty

BACKGROUND: To date, there is no study comparing outcomes between post-total knee replacement genu recurvatum and fixed flexion. This study aims to provide data that will help in deciding which side to err on when neutral extension is not achieved. METHODS: A prospective cohort study of primary total knee arthroplasties was performed, which compared the 6-month and 2-year clinical outcomes between fixed flexion and genu recurvatum deformities at 6 months. RESULTS: At 6 months, knees in genu recurvatum did better than knees in fixed flexion deformity in terms of knee flexion. However, at 2 years, knees in fixed flexion deformity did better in terms of knee scores and showed better improvement in the degree of deformity. CONCLUSIONS: We conclude that it is better to err on the side of fixed flexion deformity if neutral alignment cannot be achieved.

Reducing allograft contamination and disease transmission: intraosseous temperatures of femoral head allografts during autoclaving

<p><b>INTRODUCTION</b>The Singapore General Hospital Bone Bank, which exclusively stores femoral head allografts, relies on flash sterilisation to prevent allograft-related disease transmission and wound infection. However, intraosseous temperatures during autoclaving may be lower than required to eliminate human immunodeficiency virus, and hepatitis B and C viruses. The aim of this study is to determine the intraosseous temperatures of femoral head allografts during autoclaving and to assess the adequacy of autoclaving in preventing disease transmission.</p><p><b>METHODS</b>Six femoral heads were acquired from patients who underwent hip arthroplasty. The specimens were divided into two groups. The first group underwent flash sterilisation with a sterilisation time of 4 min, while a longer sterilisation time of 22 min was used for the second group.</p><p><b>RESULTS</b>The highest core temperature in the first group was 130°C, while the core temperatures in the second group plateaued at 133°C for all allografts. In the first group, only smaller allografts maintained temperatures sufficient for the inactivation of the clinically relevant viral pathogens. In contrast, all allografts in the second group were terminally sterilised.</p><p><b>CONCLUSION</b>There is an inverse correlation between the size of allografts and intraosseous temperatures achieved during autoclaving. Therefore, we recommend dividing large allografts into smaller pieces, in order to achieve intraosseous temperatures adequate for the elimination of transmissible pathogens during flash sterilisation. Allografts should not be terminally sterilised, as the resulting allografts will become unusable. Despite modern processing techniques, stringent donor selection remains vital in the effort to prevent allograft-related infections. Autoclaving is an economical and efficacious method of preventing allograft-related disease transmission.</p>

Early experiences with robot-assisted total knee arthroplasty using the DigiMatch™ ROBODOC® surgical system

<p><b>INTRODUCTION</b>The use of robotics in total knee arthroplasty (TKA) has been shown to minimise human error, as well as improve the accuracy and precision of component implantation and mechanical axis alignment. The present study aimed to demonstrate that robot-assisted TKA using ROBODOC® is safe and capable of producing a consistent and accurate postoperative mechanical axis.</p><p><b>METHODS</b>We prospectively recruited 27 consecutive patients who underwent robot-assisted TKA between May and December 2012. Two patients were excluded from the study due to intraoperative technical problems with the robot. Long-leg radiography and computed tomography were performed prior to surgery, and used for mechanical axis measurements and component sizing. DigiMatch™ ROBODOC® Surgical System software version 4.3.6 (Curexo Technology Corp, Fremont, CA, USA) was used in all cases to perform bone cuts in accordance with the preoperative plan.</p><p><b>RESULTS</b>The postoperative coronal mechanical alignment was within 3 degrees, with a mean alignment of -0.4 ± 1.7 degrees, confirming the accuracy of the preoperative surgical plan and bone cuts. The mean operating time was 96 ± 15 min, and preoperative planning yielded 100% implant sizing accuracy.</p><p><b>CONCLUSION</b>Robotics has the potential to enable surgeons to consistently attain ideal postoperative alignment. The use of bone movement monitors and an integrated navigation system enhances the safety profile of ROBODOC® by minimising errors. However, the role of the surgeon in TKA is still vital, as the surgeon is ultimately in charge of planning the surgery, its execution and ensuring soft tissue balance during TKA.</p>

A Singapore perspective on the use of a short course of chemothromboprophylaxis in patients who underwent total knee arthroplasty

<p><b>INTRODUCTION</b>There is considerable controversy regarding the best method to prevent venous thromboembolism. In 2008, the American College of Chest Physicians (ACCP) published specific guidelines recommending the use of ow-molecular-weight heparin or warfarin, and a target international normalised ratio of 2.0-3.0 for a duration of at least 7-10 days, after elective knee arthroplasties. Many orthopaedic surgeons believe that these recommendations are biased toward reducing deep venous thrombosis (DVT), but neglect the implicated possibility of a higher incidence of wound complications. In order to enable an objective evaluation of the fit of the ACCP recommendations to the needs of our local cohort of patients, we aimed to look at the incidence of DVT in our local population.</p><p><b>METHODS</b>This study was a prospective observational study involving existing local patients in Singapore General Hospital, Singapore, who underwent total knee arthroplasty (TKA) and were on a short course of chemothromboprophylaxis (< 7 days) after the operation. The incidence of DVT in patients was evaluated using DVT imaging 4-6 days after the operation and at one month after the operation.</p><p><b>RESULTS</b>In our study cohort, the prevalence of DVT during the period between postoperative Days 4 and 6 was 12% (11% were distal DVT and 1% was proximal DVT). Only 9% of the patients had DVT one month after the operation. Using chi-square analysis, we found that there was no significant increase in the number of DVT and pulmonary embolism cases 4-6 days and 1 month after the operation (p > 0.05).</p><p><b>CONCLUSION</b>Contrary to the ACCP guidelines, a short course of chemothromboprophylaxis post TKA, lasting no more than 7 days, is safe and adequate in the low-risk Asian population.</p>

Revision total knee arthroplasty: causes and outcomes

<p><b>INTRODUCTION</b>Local data on revision total knee arthroplasty (TKA) are limited. This study aims to assess the causes and outcomes of revision TKA in a single institution, with a 2-year follow-up.</p><p><b>MATERIALS AND METHODS</b>A retrospective review of case records of patients who underwent revision TKA in 2008 and 2009 in the authors' institution was performed. Outcome was assessed using SF-36, Oxford knee score and Knee Society Clinical Rating System preoperatively, at 6 months and at 2 years' follow-up.</p><p><b>RESULTS</b>Forty-one patients (41 knees) were included in the study. Indications for revision were aseptic loosening in 13 (31.7%), mechanical wear/component failure in 10 (24.4%), infection in 9 (22.0%), malalignment in 4 (9.8%), instability in 3 (7.3%), periprosthetic fracture in 1 (2.4%) and persistent stiffness in 1 (2.4%). Significant improvements were seen postoperatively in all 3 instruments used to evaluate clinical outcome. These improvements were seen at 6 months after surgery, and were maintained through the 2-year follow-up period. There were no significant changes in all scores between 6 months and 2 years follow-up. There was 100% survivorship of the implants with no postoperative complications requiring surgical intervention.</p><p><b>CONCLUSION</b>Indications for revision TKA locally are similar to those in other large centres. Revision total knee arthroplasty results in significantly improved function and quality of life for patients, which is maintained over a 2-year follow-up period. In our series, we obtained 100% implant survivorship.</p>