Purpose: Total knee arthroplasty (TKA) is a clinically efficacious surgical option for end-stage knee osteoarthritis.However, TKA increases the risk of serious bleeding and blood transfusion. The objective of this study was to evaluate the difference in postoperative blood loss in groups subjected to 3 h of clamping and non-clamping and determine the variations in rate and amount of transfusion after TKA between the two groups. Materials and methods: Propensity score matching of the group subjected to 3-h drain clamping (43 patients;September 2015 to April 2016) and the control group (43 patients; before initiating the clamping method) was performed in patients undergoing unilateral primary posterior stabilized TKA. The two groups were compared. We measured the total drained blood volume until the drain was removed 48 h after surgery, and we compared the preoperative levels of hemoglobin and hematocrit with levels observed on days 1 and 2 after surgery. We also determined the blood transfusion rate and volume as well as the occurrence of clamping-associated complications. Results: In the group subjected to 3-h drain clamping, the mean volume of total drained blood was significantly lower than in the control group (333.8 ± 190.2 mL vs. 839.9 ± 339.8 mL, P <0.001). There was no significant difference in total blood loss between the two groups (1226.9 ± 488.1 mL vs. 1127.1 ± 424.5 mL,P = 0.315), but the hidden blood loss was significantly higher in the 3-h drain clamping group than in the control group (893.1 ± 487.7 mL vs.294.7 ± 531.8 mL, P <0.001). Both the transfusion rate and amount in the 3-h drain clamped group were higher than in the control group but were not statistically significant (30.2% vs. 37.2%, P = 0.494 and 269.8 ± 483.8 mL vs.316.3 ± 158.2 mL,P = 0.648, respectively). No significant differences in complications, including deep vein thrombosis, pulmonary thromboembolism, and oozing, were noted between the two groups (all,P = 1.000). Conclusions The 3-h drain clamping method after primary TKA using posterior stabilized implant reduced the loss of postoperative drained blood. However, hidden blood loss was significantly higher in the 3-h drain clamping group; as a result, there were no differences in total blood loss and transfusion rate. The clamping method did not significantly alter the complication rate.

Background: The aims were to assess whether sex had a clinically significant independent influence on the outcome of total knee arthroplasty (TKA) according to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Short Form (SF-) 12 scores and patient satisfaction at 1 year. Methods: A retrospective cohort of 3510 primary TKA were identified. Patient demographics, comorbidities, WOMAC and SF-12 scores were collected preoperatively and 1 year postoperatively. Patient satisfaction were assessed at 1 year. Results: There were 1584 males and 1926 females. The preoperative WOMAC and SF-12 scores were significantly (p < 0.001) worse in females but were not greater than the minimal clinically important difference (MCID). When adjustments had been made for confounding differences, females showed a significantly greater improvement in their function (1.5 points, p = 0.03) and total (1.5 points, p = 0.03) WOMAC scores compared to males, but these were not greater than the MCID. When adjustments had been made for confounding differences, females were less likely to be satisfied with their pain relief (p = 0.03) relative to males. Conclusion Sex does not clinically influence the knee specific outcome (WOMAC) or overall generic (SF-12) health 1 year after TKA. However, satisfaction with pain relief after TKA was significantly less likely in female patients.Level of evidence II: Prognostic retrospective cohort study.

Purpose: Intraoperative femoral condyle fracture is a significant but rarely reported complication during primary total knee arthroplasty (TKA). This is the first study to identify the incidence, risk factors, location and outcome of these fractures in an Asian population with modern posterior-stabilized (PS) TKA. Materials and methods: We reviewed 2682 consecutive primary TKAs performed between 2011 and 2017 in a single centre; 23 femoral condyle fractures were identified and analysed. Results: Fractures were managed conservatively with screw fixation or revision arthroplasty. Mean follow up was 3.0 years (range 3 months to 5.9 years). All patients achieved bone union and good functional outcome. The mean Knee Society Knee score was 89.4 (range 71–100) and the function score was 80.2 (range 60–95) at a mean of 3.0 years post-operation. Bilateral surgery was found to be a significant risk factor for femoral condyle fracture, while there was a higher trend of fracture in female patients and Stryker articular surface mounted (ASM) navigation. Conclusions Intraoperative fracture is not uncommon with modern PS TKA. Postulated risk factors for fracture were discussed. Early identification of risk factors and a rigorous surgical technique may reduce risk of fracture. A good functional result was expected after proper treatment.

Background: We aimed to evaluate the effect of vitamin D levels on the functional outcome of elderly women who underwent total knee arthroplasty (TKA). Methods: Seven hundred and four patients (1013 knees) who underwent primary TKA were included in our retrospective study. Preoperative vitamin D levels were measured and the relationship analyzed between these and age, weight, height, body mass index, and bone mineral density. Two hundred and twenty patients (220 knees) who received unilateral TKA and were followed up for more than 1 year after operation were divided into two groups: Group 1, serum 25-hydroxyvitamin D3 (25(OH)D3) level < 20 ng/ml; and Group 2, 25(OH)D3 level ≥ 20 ng/ ml. Both groups were evaluated for the relationship between vitamin D levels and postoperative Visual Analogue Scale (VAS) score, Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS), and Western Ontario and McMaster Universities Arthritis Index (WOMAC) score. Results: The number of vitamin D-deficient patients (< 20 ng/ml of serum 25(OH)D3 level) was 556 (79.0%). In the correlation analysis, the vitamin D level was negatively correlated with weight only (pConclusions Vitamin D deficiency was highly prevalent in patients who underwent TKA. Vitamin D levels negatively correlated with weight. Low vitamin D level was not a risk factor for unsatisfactory TKA outcome in elderly women.

Background: The purpose of this study was to evaluate the effect of patellar facet angle on pre- and postoperative patellofemoral alignment and the progress of arthritis of the patellofemoral joint in posterior-stabilized total knee arthroplasty (PS TKA) without patellar resurfacing. Methods: Patients who had a PS TKA for a varus osteoarthritic knee who were followed up for more than 2 years were included in this study. The radiologic and clinical outcomes were compared between 72 knees (group A) whose patellar facet angle was greater than 126° (> 126°) and 32 knees (group B) whose patellar facet angle was smaller than or equal to 126° (≤ 126°). For the radiologic assessment, the Kellgren-Lawrence grade, mechanical femorotibial angle, Insall-Salvati ratio, patellar tilt angle, patellar displacement and the osteosclerosis of the patellar ridge were evaluated. The range of motion (ROM) and patient-reported outcomes (the Knee Society knee score, the Knee Society function score, the Feller patellar score, and the Kujala patellofemoral score) were used for the clinical assessment. Results: The preoperative patellar tilt angle was 9.8° (standard deviation [SD] 5.5) and 14.6° (SD 4.1) in group A and group B, respectively, a significant difference (p < 0.001). Other preoperative radiologic parameters and preoperative patient-reported outcomes and ROM showed no significant difference between the two groups (all parameters (p> 0.05). At the last-follow-up, 22 knees (30.6%) showed progression of osteosclerosis of the patellar ridge in group A and 13 knees (40.6%) showed progression of osteosclerosis in group B (p = 0.371). The postoperative radiologic and clinical outcomes showed no significant difference between the two groups (all parameters,p > 0.05). Conclusions Although a narrow patellar facet angle was related to an increase of lateral tilting of the patella, it showed no impact on the preoperative clinical assessment. The radiologic and clinical outcomes evaluated after the PS TKA showed no statistical difference according to the patellar shape. Although the patellar shape evaluated by the patellar facet angle can partially affect the preoperative patellofemoral alignment, this study result indicated insignificant clinical relevance of the patellar shape in the PS TKA.

Background: We applied bibliometric tools to original articles published in the official journal of the Korean Knee Society between 1999 and 2018 to identify their characteristics related to knee surgery and to examine the changes in research trends in the last 20 years. Methods: Over a 20-year period, 579 original articles were published in the journal Knee Surgery and Related Research (KSRR). We analyzed the title, keywords, and abstract of the article to analyze the research topics and assigned original articles to seven surgical categories as follows: total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), high tibial osteotomy (HTO), arthroscopy, surgery for cruciate ligament, revision surgery, and other surgery. To analyze the trends in research, we divided the study period into two equal parts of 10 years each, examined the percentage of articles in each decade, and analyzed topic trends using the growth rate. Results: Among the original articles, 86 on the topic of non-surgery were excluded, and 493 original articles related surgical research were included. Articles related to surgery accounted for 85.2% of the total original articles published annually. By period, this was 85.6% in the first half and 84.8% in the late half (p = 0.76). A total of 493 original articles related to surgery, with the largest number of TKA-related research at 52.1%. In the study period, the largest increase in the percentage of articles was on the topic of HTO surgery, by 149%. The topics of UKA and revision surgery increased by 95.3% and 33.9%. The topic of TKA increased by 5.9% and the topic of surgery for cruciate ligament decreased by 18.7%. The topic of arthroscopy showed the largest decrease, by 47.6%. Conclusions The bibliometric findings of this study suggest that the majority of surgery-related original articles published in KSRR during the last 20 years involved research about TKA surgery, and the greatest relative increase over the study period involved research about HTO surgery. The authors expect that the analysis of characteristics and research trends of original articles published in KSRR will provide useful information about KSRR for future researchers.

Methods: Isokinetic strengths of the quadriceps and hamstring muscles and endurances were compared between a group of 20 patients undergoing PCLR using a tibialis anterior allograft and a 1:2 matched control group of 40 patients undergoing ACLR using a hamstring autograft at 2 years after the operations. Clinical results were also compared using stability tests and the Lysholm and the International Knee Documentation Committee scores. Results: At 2 years after the operations, the torque deficit of the hamstring muscle in the involved leg compared to the uninvolved leg at both 60°/s and 120°/s was greater in the PCLR group than in the ACLR group (60°/s, 21.8 ± 14.0% versus 1.9 ± 23.9%, P = 0.0171; 120°/s, 15.3 ± 13.7% versus −0.7 ± 17.4%, P = 0.012, respectively). The peak torque of the hamstring muscle at 120°/s was significantly lower in the involved leg than in the uninvolved leg only in the PCLR group (71.3 ± 31.9 N·m versus 81.9 ± 27.8 N·m, P = 0.005). There was no significant difference in the clinical results between the groups except for a side-to-side difference in the tibial translation on Telos stress radiographs. Conclusion The strength of the hamstring of the PCLR leg with allograft was significantly weaker than that of the unoperated leg after 2 years, whereas that of the ACLR leg with hamstring autograft maintained a similar level of strength compared to that of the uninvolved leg.Level of evidence: Level III, case–control study.

Purpose: The aim of this study was to determine if contralateral knee range of motion is associated with postoperative range of motion in the operative knee after total knee arthroplasty. Methods: Contralateral (nonoperative) knee range of motion was compared to postoperative knee range of motion after total knee arthroplasty using linear regression models in 59 patients who had undergone primary total knee arthroplasty with a minimum of 4 months postoperative follow-up data (range 4–13 months). Results: A strong linear relationship was observed between contralateral knee ranges of motion of 115° or greater and postoperative knee ranges of motion after total knee arthroplasty (slope 0.93, 95% CI 0.58–1.29, P < 0.0001), with a mean difference of −7.44° (95% CI −10.3 to −4.63, P < 0.0001). However, there was no association between contralateral knee range of motion and postoperative knee range of motion when contralateral knee range of motion was less than 115°. Conclusion Contralateral knee range of motion of 115° or greater correlates linearly with postoperative range of motion after total knee arthroplasty, and thus may be predictive in such cases.

Purpose: The purpose of this study is to investigate the proprioceptive function of patients with isolated articular cartilage lesions of the knee as compared to normal controls. Methods: The Cartilage group consisted of eight subjects with radiologically and arthroscopically confirmed, isolated, unilateral, articular cartilage lesions of the knee (Outerbridge grade III or IV). They were compared to 50 normal controls. Knee proprioception was assessed by dynamic postural stabilometry using the Biodex Balance SD System. Patient-reported outcome measures (PROMs) were used to evaluate all subjects. Results: Proprioception of the injured knee of the Cartilage group was significantly poorer compared to that of the control group (p < 0.001). A significant proprioceptive deficit also was observed when the uninjured knees of the Cartilage group were compared to those in the Control group (p = 0.003). There was no significant proprioceptive difference between the injured and the contra-lateral uninjured knee of the Cartilage group (p = 0.116). A significant correlation was found between the proprioception measurements of the injured and uninjured knee of the Cartilage group (r = 0.76,p = 0.030). A significant difference was observed in all PROMs (p < 0.001) between the Cartilage and Control groups. Conclusions Patients with isolated articular cartilage lesions of the knee had a significant proprioceptive deficit as compared to normal controls. The deficiency was profound and even affected the proprioceptive function of the contra-lateral uninjured knee. This study has shown that articular cartilage lesions have a major influence on knee proprioception. However, it remains uncertain as to whether a proprioceptive deficit leads to osteoarthritis or is a consequence of it.

Background: The mechanism of injury (MoI) for a patellar dislocation has not been fully established. The aim of this study was to use systematic video analysis to determine the MoI of a patella dislocation. Methods: A systematic search was conducted of three video sharing websites and three popular search engines to identify videos demonstrating a patellar dislocation. Videos were reviewed by three surgeons trained in systematic video analysis, who commented on the position of the lower limb and the situation in which the injury occurred.The results were reviewed to build a consensus of the MoI for each video. Statistical analysis was conducted for interobserver agreement (p < 0.05). Results: Initial search yielded 603 videos with 13 meeting the inclusion criteria. The injuries were sustained performing a sporting activity (n = 9) or whilst dancing (n = 4). The injury was predominantly sustained during a non-contact situation (n = 10). The most common mechanism was an unbalanced individual with a flexed hip sustaining a valgus force to their flexed knee with the tibia externally rotated. Conclusions This study provides some insight into the MoI for a patellar dislocation and the findings may assist in developing injury prevention programmes and rehabilitation protocols as well as guiding future research.