OBJECTIVE: Blood transfusion is a common perioperative complication of primary total knee arthroplasty (TKA) that can lead to adverse outcomes, prolonged hospital stays, and increased medical costs. The purpose of our study was to explore the risk factors for blood transfusion and to establish whether operation duration is independently related to blood transfusion risk in patients undergoing primary TKA after adjusting for other covariates.
METHODS: This was a secondary analysis of data from a retrospective cohort study involving patients who underwent primary TKA in Singapore. The patients\' baseline data, comorbidity, and surgical characteristics were collected. The independent variable was operation duration and the dependent variable was blood transfusion events. Patients were divided into three groups according to operation durations (90 and 120 min). Univariate logistic regression was used to explore the risk factors associated with blood transfusion after primary TKA. Multivariate analysis was used to assess the independent effect of operation duration on blood transfusion risk after adjusting for other covariates. Additionally, we performed subgroup analyses to identify specific groups, test the robustness of the relationships, and explore whether there were interactions between the different variables. Furthermore, restricted cubic splines (RCS) were used to identify the relationship between the two variables.
RESULTS: A total of 2,562 patients were included in the study, of whom 136 (5.61%) had a transfusion event. Operation durations were 95.55 ± 36.93 and 83.86 ± 26.29 min for blood transfused and non-transfused patients, respectively. Univariate logistic regression analysis showed that age, BMI, ASA status, Hb level, OSA, CHF, creatinine level > 2 mg/dL, and anaesthesia type were risk factors for blood transfusion. After adjusting for all covariates, multivariate logistic regression models showed that operation duration was positively associated with blood transfusion risk (odds ratio [OR] = 1.87, 95% CI = 1.174-2.933, P = 0.007). Compared to patients with an operation duration of less than 90 min, those with an operation duration of more than 120 min had a 2.141-fold increased risk of blood transfusion (OR = 2.141, 95% CI = 1.035-4.265, P = 0.035). Stratified analysis results showed that the association persisted in patients aged > 50 years, Chinese, BMI > 30 kg/m 2, Hb level > 11 g/dL, ASA status levels 2 and 3, general anaesthesia, and unilateral primary TKA. A non-linear (P-non-linear = 0.30) and J-shaped relationship was identified. The risk of transfusion increased as the operation duration decreased or exceeded the inflection point (73.2 min).
CONCLUSIONS: Our study demonstrated a non-linear and J-shaped relationship between operation duration and blood transfusion events in patients undergoing primary TKA. Blood transfusion risk was the lowest when the operation duration was 73.2 min. A shorter operation duration implies irregular surgical procedures and incomplete intraoperative haemostasis, leading to increased perioperative blood loss and blood transfusion. These results will be useful for clinical decision-making.

Objective Total knee arthroplasty is one of the most common orthopedic surgeries. Readmission due to severe complications after total knee arthroplasty is a grave concern to surgeons. In this study, we evaluated the risk factors for severe complications after primary total knee arthroplasty. Methods We retrospectively collected clinical data of 2,974 patients who underwent primary total knee arthroplasty from July 2013 to June 2019 in our hospital. Postoperative complication ≥ grade Ⅲ was defined as severe complication according to Clavien-Dindo classification system. Binary logistic regression was used to identify the predictive risk factors for severe complications. Results The complication rate after primary total knee arthroplasty was 6.8% and severe complication rate was 2.5%. Male (OR = 2.178, 95%CI: 1.324-3.585, P= 0.002), individuals above 75 years old (OR = 1.936, 95%CI: 1.155-3.244, P= 0.012), arrhythmia (OR = 2.913, 95%CI: 1.350-6.285, P= 0.006) and cerebrovascular disease (OR = 2.804, 95%CI: 1.432-5.489, P= 0.003) were predictive risk factors for severe complications after primary total knee arthroplasty. Conclusion Advanced age, male, arrhythmia, and cerebrovascular disease might be patients-related risk factors for postoperative severe complications after primary total knee arthroplasty. Special attention should be paid to patients with risk factors.

OBJECTIVE: Although many studies have compared the measured resection (MR) technique to the gap balancing (GB) technique, few studies have investigated the hybrid technique. In this study, we compared imaging and clinical outcomes of the MR, GB, and hybrid techniques in primary total knee arthroplasty (TKA).
METHODS: From January 2016 to January 2019, we conducted a retrospective study on 90 patients who underwent unilateral primary TKA; 30 received the MR technique, 30 received the GB technique, and 30 received the hybrid technique. Radiological outcomes, including joint line level, mechanical alignment of the lower limb, positions of the femoral and tibial components, and rotation of the femoral component, and clinical outcomes, including the visual analog scale score for pain, the Knee Society Score, and the range of motion, were assessed among the three groups. One-way analysis of variance and Dunnett\'s test were performed for normally distributed data. Kruskal-Wallis H test and Dunn-Bonferroni test were conducted for non-normally distributed data.
RESULTS: No significant difference in the mechanical alignment (p = 0.151) and the positions of the tibial and femoral components (p = 0.230 for α angle, p = 0.517 for β angle, p = 0.686 for femoral flexion angle, and p = 0.918 for tibial slope angle) was found among the three groups. No significant difference in the elevation of the joint line between the MR and the hybrid groups was found (2.1 ± 0.3 mm vs 2.1 ± 0.1 mm, p = 0.627), but the GB group (2.8 ± 0.2 mm) differed significantly from the other two groups (p < 0.001). Although rotation of the femoral component in the GB group was larger than that of the MR and hybrid groups, the difference was not significant (1.8° ± 0.2° vs 1.7° ± 0.3° vs. 1.7° ± 0.2°, p = 0.101). The clinical outcomes were not significantly different (p > 0.05), although the results in the hybrid group were slightly higher.
CONCLUSIONS: The hybrid technique helped to restore the mechanical alignment of the lower limb and realize optimal positions of the femoral and tibial components without significant differences relative to the MR and GB techniques. The hybrid technique was more helpful for maintaining the original height of the joint line, which was similar to the MR technique. Additionally, although the improvement in the clinical outcomes in the hybrid group was slightly higher, it was not significantly different among the three groups.

UNASSIGNED: Studies of clinical outcomes that compare the Medial Pivot design (MP) with the Posterior-Stabilized design (PS) were controversial. The meta-analysis was performed to summarize existing evidence, aiming to determine whether MP was superior to PS prosthesis.
UNASSIGNED: Search strategies followed the recommendations of the Cochrane collaboration. Electronic searches such as PubMed, Embase, Web of Science, and Cochrane were systematically searched for publications concerning medical pivot and posterior stabilized prosthesis from the inception date to April 2021. Authors also manually checked and retrieved a reference list of included publications for potential studies, which the electronic searches had not found. Two investigators independently searched, screened, and reviewed the full text of the article. Disagreements generated throughout the process were resolved by consensus, and if divergences remain, they were arbitrated by a third author. Subsequently, patients were divided into the MP and PS groups.
UNASSIGNED: This study included 18 articles, comprising a total of 2614 patients with a similar baseline. The results showed the PS group had a higher risk of the patellar clunk or crepitus. However, the theoretical advantages of MP prosthesis could not translate to the difference in knee function, clinical complications, revision rate and satisfaction. Similarly, the shape and mechanism of prostheses could not affect the implant position and postoperative alignment.
UNASSIGNED: The MP prosthesis can reduce the patellar clunk or crepitus rate. However, choices between the MP and PS prosthesis would not affect knee function, clinical complications, revision rate, patient satisfaction, implant position, and postoperative alignment.

OBJECTIVE: The aim of this radiological study was to compare several relevant modified and newly applied patella height indices (PHI) in navigated primary total knee arthroplasty (TKA) to determine intra- and interobserver reliability in order to give a recommendation for clinical application in measuring patella height (PH) in primary TKA.
METHODS: A retrospective data analysis assessing different PHI (modified Insall-Salvati index (mISI), Caton-Deschamps index (mCDI), Blackburne-Peel index (mBPI), Plateau-Patella Angle (mPPA); Miura-Kawaramura index (MKI), Knee-Triangular index (KTI)) on lateral knee radiographs was performed by two blinded observers using the same software three months pre- and postoperatively. Concordance correlation coefficient and Pearson\'s correlation respectively were determined for intra- and interobserver rating as well as a categorization according to Landis and Koch and Cohen.
RESULTS: A total of 337/291 patients of a 5-year period could be analyzed pre-/postoperatively. Excellent postoperative interrater results according to the categorization of Landis and Koch were achieved for the mBPI (Pearson 0.98) > mPPA (0.90) > KTI (0.86), good results for the MKI (0.79) and the mCDI (0.69), and moderate results for the mISI (0.52) with a predominantly strong Cohen correlation in almost all cases. Preoperatively, the mBPI and the KTI were the best interrated PHI. No PH changes could be found postoperatively for the mISI, KTI, MKI, and mPPA.
CONCLUSIONS: The mBPI, the mPPA, and the KTI can be recommended for PH assessment in TKA. The mPPA might be the easiest one to use in a daily clinical set-up.

OBJECTIVE: Antibiotic-loaded bone cement (ALBC) was usually used to prevent periprosthetic joint infection (PJI) in primary total knee arthroplasty (PTKA), but whether to use ALBC or plain bone cement in PTKA remains unclear. We aimed to compare the occurrence rate of PJI using two different cements, and to investigate the efficacy of different antibiotic types and doses administered in preventing surgical site infection (SSI) with ALBC.
METHODS: The availability of ALBC for preventing PJI was evaluated by using a systematic review and meta-analysis referring to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Existing articles until December 2021 involving PTKA patients with both ALBC and plain bone cement cohorts were scanned by searching \"total knee arthroplasty\", \"antibiotic-loaded cement\", \"antibiotic prophylaxis\", \"antibiotic-impregnated cement\" and \"antibiotic-laden cement\" in the database of PubMed/MEDLINE, Embase, Web of Science and the Cochrane Library. Subgroup analysis included the effectiveness of different antibiotic types and doses in preventing SSI with ALBC. The modified Jadad scale was employed to score the qualities of included articles.
RESULTS: Eleven quantitative studies were enrolled, including 34,159 knees undergoing PTKA. The meta-analysis results demonstrated that the use of prophylactic ALBC could significantly reduce the prevalence of deep incisional SSI after PTKA, whereas there was no significant reduction in the rate of superficial incisional SSI. Moreover, gentamicin-loaded cement was effective in preventing deep incisional SSI, and the use of high-dose ALBC significantly reduced the rate of deep incisional SSI after PTKA. Besides, no significant adverse reactions and complications were stated during the use of ALBC in PTKA.
CONCLUSIONS: The preventive application of ALBC during PTKA could reduce the rates of deep PJI. Furthermore, bone cement containing gentamicin and high-dose ALBC could even better prevent deep infection after PTKA. However, the existing related articles are mostly single-center and retrospective studies, and further high-quality ones are needed for confirmation.

BACKGROUND: The accelerometer-based navigation (ABN) system is an emerging navigation system for total knee arthroplasty (TKA). This study aimed to determine whether the ABN system could improve the accuracy of mechanical alignment, component positioning, and short-term clinical outcomes for TKA when compared to conventional instruments (CON).
METHODS: A total of 204 patients were selected and divided into two groups (CON: 135, ABN: 69) after applying the inclusion and exclusion criteria. Then, 1:1 propensity score matching was performed for age, gender, body mass index, hip-knee-ankle angle (HKA), Knee Society Score (KSS), Western Ontario and McMaster Universities (WOMAC) score, and follow-up times. A total of 82 consecutive patients (82 knees) underwent total knee arthroplasty using ABN (n = 41) or CON (n = 41) were enrolled in this study. The postoperative HKA, frontal femoral component (FFC) angle, frontal tibial component (FTC) angle, lateral femoral flexion (LFF) angle, and lateral tibial component (LTC) angle were compared between the two groups to evaluate mechanical alignment and component positioning. Additional clinical parameters, including haemoglobin reduction, the KSS, and the WOMAC score, were assessed at the final follow-up (the mean follow-up period was 20.9 months in the CON group and 21.2 months in the ABN group).
RESULTS: The ABN group had a significantly improved mean absolute deviation of HKA (P = 0.033), FFC (P = 0.004), FTC (P = 0.017), LFF (P = 0.023), and LTC (P = 0.031) compared to those of the CON group. The numbers of FFCs and LTCs within 3° were significantly different (P = 0.021, P = 0.023, respectively) between the two groups. However, no differences in the numbers of FTCs within 3° (P = 0.166) and LFF within 3° (P = 0.556) were found. The ABN group had a significantly higher KS function score (P = 0.032), and the pain and stiffness scores were significantly different (P = 0.034, P = 0.020, respectively) between the two groups. Moreover, the ABN system could reduce hidden blood loss postoperatively. However, no difference was found in the KS knee score and the total WOMAC score between the two groups.
CONCLUSIONS: This study demonstrates that ABN system improved TKA mechanical alignment and component positioning and decreased the hidden blood loss postoperatively compared to conventional instruments. However, no significant differences were found in short-term clinical outcomes between ABN and conventional instruments at the final follow-up. However, whether this system contributes to revision rates and long-term clinical outcomes requires further study.

The aims of this study were to evaluate the long term clinical outcomes and survival rate of total knee arthroplasty (TKA) in Chinese population and the risk factors for failure. Between 1985 to 2001, 297 patients underwent primary TKAs with cemented fixed bearing platform in our center. Survival rate was 92.7% at 10 years, with reoperation of the implant as the endpoint, and 90.4% at 15 years. Main reasons for failure were infection and aseptic loosening. Clinical evaluation of 96 knees with HSS knee score showed the mean scores increased from 56.58 ± 11.05 preoperatively to 92.29 ± 10.95 postoperatively. RA patients had lower long-term survivorship compared with OA patients. Younger patients had better HSS scores. Patella strategy and posterior-cruciate-ligament (PCL) strategy had no effect on implant survivorship and clinical outcome. In conclusion, this was one of first studies showing valid long-term outcomes of primary TKA in Chinese.