Seng Jin Yeo

Continuous femoral nerve block in total knee arthroplasty: immediate and two-year outcomes.

We conducted a prospective study to investigate the immediate and 2-year outcomes of total knee arthroplasty patients who received continuous femoral nerve block (FNB) for analgesia. Sixty patients undergoing unilateral total knee arthroplasty were randomized into 3 groups and received high-dose continuous FNB, low-dose continuous FNB, or no FNB. In the immediate postoperative period, we studied their pain scores, cumulative morphine use, any FNB-related complications, time of first ambulation, and patient satisfaction. At 2 years, we assessed their functional outcomes with Oxford knee questionnaire and Knee Society clinical rating system. Immediately after surgery, there was less pain, higher satisfaction, and lower morphine use among patients on continuous FNB regardless of ropivacaine dosage used. At 2 years, there were no significant differences in functional outcomes.

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.

Improved Clinical Outcomes After High-Flexion Total Knee Arthroplasty: A 5-Year Follow-Up Study

The purpose of this study was to determine if high-flexion total knee arthroplasty resulted in improved outcomes compared with conventional total knee arthroplasty. This was a prospective, double-blind, randomized controlled trial involving 76 patients over 5 years. We compared the postoperative flexion range, Knee Society scores, Oxford knee scores, and SF-36 scores between 2 groups. The high-flexion group was able to achieve a significant sustainable increase in postoperative knee flexion angle; and this correlated to a significant improvement in the General Health, Vitality, and Physical Functioning scales of SF-36 at 5 years postoperatively. Our results signify that high-flexion total knee arthroplasty has additional benefits to the quality of life in patients who require higher degrees of knee flexion in their activities of daily living.

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.

Accelerometer-Based Navigation Is as Accurate as Optical Computer Navigation in Restoring the Joint Line and Mechanical Axis After Total Knee Arthroplasty: A Prospective Matched Study.

The Zimmer iASSIST system is a novel accelerometer-based navigation system for TKA. 76 patients (76 knees) were prospectively matched for age, BMI, gender, diagnosis, and pre-operative scores, and underwent TKA using the iASSIST (n=38) or optical CAS (n=38). There were no significant differences in clinical outcomes or satisfaction rates at six months post-operatively (P>0.05). Mechanical axis was 1.8±1.3° in the iASSIST cohort versus 2.1±1.6° in the CAS cohort (P=0.543). There were no significant differences in number of outliers for mechanical axis (P=1.000), coronal femoral-component angle (P=0.693), coronal tibial-component angle (P=0.204) or joint line deviation (P=1.000). The duration of surgery was significantly longer in the CAS group (P<0.001), while the added cost of accelerometer-based navigation was approximately

Comparison of the responsiveness of the SF-36, the Oxford Knee Score, and the Knee Society Clinical Rating System in patients undergoing total knee replacement

1000 per operation.

Computer navigation is a useful intra-operative tool for joint line measurement in total knee arthroplasty

ObjectivesTo compare the responsiveness of the Knee Society (KS) Clinical Rating System, the general health status measure Short Form 36 (SF-36), and both the raw and Rasch-based scores of the condition-specific Oxford Knee Score (OKS) in patients undergoing total knee replacement (TKR)MethodsData were prospectively collected as part of routine care from adult patients who underwent TKR between 2001 and 2006. OKS data fit the Rasch partial credit model after removing items regarding limping and kneeling. Responsiveness was assessed using effect size (ES), standardised response mean (SRM), and relative validity (RV).ResultsAmong 702 patients with complete data at baseline and two follow-ups, the pain subscale of the KS (KS-P), raw-OKS, and Rasch-OKS consistently had higher levels of responsiveness than all eight SF-36 and the other KS subscales. At 6-month follow-up, Rasch-OKS had the largest ES and KS-P had the largest SRM (2.7 and 2.0, respectively). When compared to raw-OKS, the RVs of KS-P, Rasch-OKS, SF-36 bodily pain, and SF-36 physical functioning were 1.1, 0.66, 0.49, and 0.36, respectively. A similar ordering of responsiveness was observed at 24-month follow-up.ConclusionThe OKS and KS-P are more responsive than most SF-36 subscales in TKR patients. Raw-OKS and Rasch-OKS have comparable responsiveness. Different responsiveness indices may give different results.

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

BACKGROUND Restoration of the native joint line in total knee arthroplasty is important in restoring ligamentous balance and normal knee kinematics. Failure to achieve this could lead suboptimal outcomes. The purpose of this study was to analyze the clinical and functional outcome of patients who demonstrated joint line changes after computer-assisted (CAS) total knee arthroplasty (TKA). METHODS One hundred sixty-eight patients (168 knees) underwent CAS TKA by two surgeons at a single institution with 2 years follow-up. The final change in joint line was calculated from the verified tibial resection and distal femoral cuts. Group A patients had joint line changes of less than 4mm and Group B patients had joint line changes of more than 4mm. Post-operative Oxford scores, Knee scores, Function scores and SF-36 scores were obtained at 6 months and 2 years post TKA. RESULTS There was significant linear correlation between joint line changes and Oxford scores (P=0.0001), Function scores (P=0.0001) and Knee scores (P=0.0001) at 6 months and Oxford scores (P=0.0001) alone at 2 years with increasing joint line changes having poorer outcome scores. Group A compared to Group B patients demonstrated better Oxford scores (P=0.0001), Function scores (P=0.0001), Knee scores (P=0.0001) and total SF-36 scores (P=0.003) at 6 months as well as better Oxford scores (P=0.0001) and Knee scores (P=0.014) at 2 years. CONCLUSIONS CAS is a useful intra-operative tool for assessing the final joint line in TKA. Outliers in joint line changes of ≥4 mm are associated with poorer clinical outcome scores. LEVEL OF EVIDENCE Prognostic Study, Level II-1.