Pak Lin Chin

Robot-Assisted Total Knee Arthroplasty Accurately Restores the Joint Line and Mechanical Axis. A Prospective Randomised Study

Robot-assisted Total Knee Arthroplasty (TKA) improves the accuracy and precision of component implantation and mechanical axis (MA) alignment. Joint-line restoration in robot-assisted TKA is not widely described and joint-line deviation of>5mm results in mid-flexion instability and poor outcomes. We prospectively randomised 60 patients into two groups: 31 patients (robot-assisted), 29 patients (conventional). No MA outliers (>±3° from neutral) or notching was noted in the robot-assisted group as compared with 19.4% (P=0.049) and 10.3% (P=0.238) respectively in the conventional group. The robot-assisted group had 3.23% joint-line outliers (>5mm) as compared to 20.6% in the conventional group (P=0.049). Robot-assisted TKA produces similar short-term clinical outcomes when compared to conventional methods with reduction of MA alignment and joint-line deviation outliers.

Intravenous versus intra-articular tranexamic acid in total knee arthroplasty: A double-blinded randomised controlled noninferiority trial.

BACKGROUND Despite the proven efficacy of both intravenous (IV) and intra-articular (IA) tranexamic acid (TXA) in reducing blood loss during total knee arthroplasty (TKA), the ideal route of administration remained debatable. This study aimed to compare the effect of IV versus IA TXA on transfusion incidences, perioperative blood loss and postoperative lower limb swelling during TKA. METHODS One hundred patients were prospectively randomised into two groups: 1) IV TXA; and 2) IA TXA. In both groups, TXA was administered intraoperatively after cementing the prostheses. The perioperative blood loss was calculated using the haemoglobin balance method. The thigh, suprapatellar, and calf girths were measured preoperatively and on postoperative day (POD) 4. RESULTS Two patients in the IV group and one patient in the IA group required blood transfusion (p=0.500). The median and interquartile range (IQR) of perioperative blood loss on POD1 and POD4 was 530 (IQR 386,704) and 730 (IQR 523,925) ml for the IV group, compared with 613 (IQR 506,703) and 799 (IQR 563,1067) ml for the IA group (p=0.090 and p=0.232 respectively). The median increment in thigh, suprapatellar, and calf girths were 1.5 (IQR 0, 3.0), 2.0 (IQR 0.5, 4.0) and 0 (IQR 0, 1.0) cm for the IV group, compared to 2.0 (IQR 1.0, 4.0), 2.0 (IQR 0, 4.5) and 0 (IQR 0, 1.5) cm for the IA group (p=0.246, p=0.562, and p=0.937 respectively). CONCLUSIONS Both IV and IA TXA had comparable effect on transfusion incidences, perioperative blood loss, and postoperative lower limb swelling during TKA. IA TXA is an alternative to IV TXA. LEVEL OF EVIDENCE I.

Intraoperative Morphometric Study of Gender Differences in Asian Femurs

Sixty-two male and 290 female knees from the Singapore population were measured intraoperatively for anteroposterior (AP) height of both medial and lateral femoral condyles, mediolateral (ML) width, and AP/ML ratio (aspect ratio). Median AP/ML ratio for the medial condyle was 1.00 (range, 0.91-1.18) in men and 1.09 (range, 0.92-1.39) in women. Median AP/ML ratio for the lateral condyle was 0.98 (range, 0.84-1.14) in men and 1.06 (range, 0.89-1.36) in women. Both aspect ratios showed significant differences according to sex (P < .001). We conclude that women generally have narrower femurs than men for any given AP height. The aspect ratios of Asians also appear narrower than that reported in white populations.

Functional Outcome and Quality of Life after Patient-Specific Instrumentation in Total Knee Arthroplasty

Patient-specific instrumentation (PSI) surgery may represent the next advancement in total knee arthroplasty (TKA). In 2011, 60 patients were prospectively recruited and divided into two groups based on the patients choice: (1) PSI surgery; and (2) conventional TKA. At two years after surgery, the Knee Society Function Score, Oxford Knee Score and SF-36 scores were comparable between the two groups. Although the Knee Society Knee Score (KSKS) was 9 ± 3 points better in the PSI group (P=0.008), the two years improvement in KSKS was comparable between the two groups. None of the patients required revision surgery. These findings cannot justify the additional costs and waiting time incurred by the patients with PSI surgery in the practice of a high volume surgeon.

Two-year outcome of early deep MRSA infections after primary total knee arthroplasty: a joint registry review.

The aim of this study is to determine the success rate in eradication of early methicillin-resistant Staphylococcus aureus (MRSA) prosthetic joint infection. Rate of prosthesis retention and functional outcome between patients with prosthesis retention and prosthesis revision were compared. All patients who underwent primary total knee arthroplasty between May 1998 and September 2008 at our institution developing early deep MRSA infection were included. Patient demographics, time from infection to initial arthrotomy, successful eradication of infection and functional outcome of patients with a knee prosthesis at 2 years were studied. Open arthrotomy, debridement, and change of liner successfully treated 33.3% of infections. All remaining infections went onto treatment with 2-stage revision with a success rate of 88%. Overall 92% of patients had a well-functioning knee prosthesis at 2 years.

Comparative Demographics, ROM, and Function After TKA in Chinese, Malays, and Indians

BackgroundThere is marked racial disparity in TKA use rates, demographics, and outcomes between white and Afro-Caribbean Americans. Comparative studies of ethnicity in patients undergoing TKAs have been mostly in American populations with an underrepresentation of Asian groups. It is unclear whether these disparities exist in Chinese, Malays, and Indians.Questions/purposesWe therefore determined whether (1) TKA use; (2) demographics and preoperative statuses; and (3) functional outcomes at 2 years after TKA differed among three ethnic groups, namely, Chinese, Malays, and Indians who underwent TKA.MethodsFrom our hospital joint registry we identified 5332 patients who had a primary TKA from 2004 to 2009. The cohort was stratified by race and subsequently compared for demographics, preoperative knee ROM, and deformity. At the second postoperative year we determined Knee Society scores, Oxford knee scores, and obtained SF-36 health questionnaires.ResultsSix percent more Chinese patients underwent TKAs compared with Malays or Indians. Malays were operated on at a younger age with a higher body mass index. Chinese patients had more severe preoperative varus deformity. There were no major differences in joint ROM in all races. For Knee Society, Oxford knee, and SF-36 scores, Chinese patients had consistently higher preoperative and postoperative scores. Malays presented with the lowest preoperative scores but had the greatest improvement in scores at followup with postoperative scores similar to Chinese counterparts. Indians had the lowest postoperative scores and worst improvement of allConclusionsThe variations in demographics, preoperative statuses, and subsequent postoperative outcomes between the races should be considered when comparing TKA outcome studies in Asian populations.Level of EvidenceLevel II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Evaluation of medial-lateral stability and functional outcome following total knee arthroplasty: results of a single hospital joint registry.

A precept of a successful total knee arthroplasty (TKA) would be a well balanced, stable knee. We analyzed the effects of medial-lateral (ML) stability on functional outcome at 2years post-operatively. Prospectively collected Joint Registry data of all unilateral primary TKAs between 2004 and March 2008 were used. ML stability (Group 1: <5°, Group 2: 6°-9°, Group 3: ≥10°) was assessed by 3 independent researchers. 1500 patients undergoing 1507 arthroplasties were divided into their various groups. Outcome assessment involved range of motion (ROM) and functional outcome, using the Knee Society Function Score (KSS), Oxford Knee Score (OKS) and SF-36 score. At 2years, Group 1 patients reported significantly higher KSS (P<0.001) and SF-36 scores. All groups had good post-operative ROM. A stable knee (ML stability <5°) post TKA is likely associated with significantly better functional outcome.

Gender difference in outcome after total knee replacement.

Purpose. To compare the outcome after primary total knee replacement (TKR) for end-stage knee osteoarthritis (OA) in men versus women. Methods. Records of 214 men and 1040 women who underwent primary TKR for end-stage knee OA and were followed up for a minimum of 2 years were reviewed. Knee flexion, Oxford Knee Score, Knee Society Score (KSS), and 8 subscores of Short Form 36 (SF-36) were recorded preoperatively and at postoperative 6 months and 2 years. Results. Men and women were comparable only in age (67.9 vs. 67.3 years, p=0.244); men had a lower mean body mass index (27.0 vs. 28.3 kg/m2, p<0.001). Preoperatively, men had better knee flexion (117° vs. 114.8°, p=0.05), Oxford Knee Score (33.5 vs. 36.8, p<0.001), KSS knee score (44.3 vs. 40.3, p=0.001), KSS function score (52.5 vs. 47.1, p<0.001), and all 8 subscores of SF-36 (p=0.005 to p<0.001). Compared with men, women achieved greater improvement at 6 months in Oxford Knee score (13.2 vs. 15.1, p=0.009) and KSS knee score (36.9 vs. 41.6, p=0.016), and at 2 years in Oxford Knee Score (15.0 vs. 17.9, p<0.001), KSS knee score (39.8 vs. 43.9, p=0.009), and SF-36 subscores of social functioning (23.6 vs. 35.1, p<0.001) and mental health (3.9 vs. 8.2, p=0.003). Conclusion. Compared with men, women had poorer preoperative knee flexion, Oxford Knee Score, KSS, and 8 subscores of SF-36, but achieved greater improvement in the Oxford Knee Score and KSS knee score at 6 months and 2 years, as well as in SF-36 subscores of social functioning and mental health at 2 years.

Intra-Articular Administration of Tranexamic Acid in Total Hip Arthroplasty

Purpose. To evaluate the effectiveness of intra-articular tranexamic acid (TXA) in reducing blood loss and the need for blood transfusion during total hip arthroplasty (THA). Methods. Records of 19 men and 31 women aged 46 to 83 (mean, 62) years who underwent primary THA with intra-articular administration of TXA were reviewed. They were compared with a matched cohort of 17 men and 33 women aged 40 to 87 (mean, 62) years who underwent the same procedure by the same surgeon without use of TXA. Postoperatively, a standard thromboembolic prophylaxis protocol was followed. A serum haemoglobin level of <80 g/l was the trigger for blood transfusion. Results. The 2 groups were comparable in terms of age, gender, body mass index, side involved, and anaesthesia method. No patient developed infection, wound haematoma, symptomatic deep vein thrombosis, or pulmonary embolism within 30 days. Compared with controls, patients in the TXA group had a higher median postoperative serum haemoglobin level (103 vs. 112 g/l, p=0.013), lower median drop in serum haemoglobin level (31 vs. 20 g/l, p<0.001), lower median total blood loss (900 vs. 575 ml, p<0.001), and lower transfusion rate (32% vs. 10%, p=0.007). The TXA treatment cost S

Management of Periprosthetic Fracture in Unicompartmental Knee Arthroplasty Patients: A Case Series

19.50 per patient, whereas one unit of allogenic blood cost S