A new gap balancing technique with functional alignment in total knee arthroplasty using the MAKO robotic arm system: a preliminary study.

BACKGROUND: Gap tension is an important factor influencing the clinical outcomes of total knee arthroplasty (TKA). Traditional mechanical alignment (MA) places importance on neutral alignment and often requires additional soft tissue releases, which may be related to patient dissatisfaction. Conversely, the functional alignment requires less soft tissue release to achieve gap balance. Conventional gap tension instruments present several shortcomings in practice. The aim of this study is to introduce a new gap balancing technique with FA using the modified spacer-based gap tool and the MAKO robotic arm system. METHODS: A total of 22 consecutive patients underwent primary TKA using the MAKO robotic arm system. The gap tension was assessed and adjusted with the modified spacer-based gap tool during the operation. Patient satisfaction was evaluated post-operatively with a 5-point Likert scale. Clinical outcomes including lower limb alignment, Knee Society Score (KSS) and Western Ontario and McMaster Universities Arthritis Index (WOMAC) were recorded before surgery, 3 months and 1 year after surgery. RESULTS: The range of motion (ROM) was significantly increased (p < 0.001) and no patients presented flexion contracture after the surgery. KSS and WOMAC score were significantly improved at 3 months and 1 year follow-up (p < 0.001 for all). During the surgery, the adjusted tibial cut showed more varus than planned and the adjusted femoral cut presented more external rotation than planned (p < 0.05 for both). The final hip-knee-ankle angle (HKA) was also more varus than planned (p < 0.05). CONCLUSIONS: This kind of spacer-based gap balancing technique accompanied with the MAKO robotic arm system could promise controlled lower limb alignment and improved functional outcomes after TKA.

[Impact of anemia on incidence of perioperative lower limb deep vein thrombosis in patients undergoing total hip arthroplasty].

Objective: To explore the impact of anemia on the incidence of perioperative lower limb deep vein thrombosis (DVT) in patients undergoing total hip arthroplasty (THA). Methods: A retrospective analysis was conducted on clinical data of 1 916 non-fracture patients who underwent THA between September 2015 and December 2021, meeting the selection criteria. Among them, there were 811 male and 1 105 female patients, aged between 18 and 94 years with an average of 59.2 years. Among the patients, 213 were diagnosed with anemia, while 1 703 were not. Preoperative DVT was observed in 55 patients, while 1 861 patients did not have DVT preoperatively (of which 75 patients developed new-onset DVT postoperatively). Univariate analysis was performed on variables including age, gender, body mass index (BMI), diabetes, hypertension, history of tumors, history of thrombosis, history of smoking, revision surgery, preoperative D-dimer positivity (≥0.5 mg/L), presence of anemia, operation time, intraoperative blood loss, transfusion requirement, and pre- and post-operative levels of red blood cells, hemoglobin, hematocrit, and platelets. Furthermore, logistic regression was utilized for multivariate analysis to identify risk factors associated with DVT formation. Results: Univariate analysis showed that age, gender, hypertension, revision surgery, preoperative levels of red blood cells, preoperative hemoglobin, preoperative D-dimer positivity, and anemia were influencing factors for preoperative DVT ( P<0.05). Further logistic regression analysis indicated that age (>60 years old), female, preoperative D-dimer positivity, and anemia were risk factors for preoperative DVT ( P<0.05). Univariate analysis also revealed that age, female, revision surgery, preoperative D-dimer positivity, anemia, transfusion requirement, postoperative level of red blood cells, and postoperative hemoglobin level were influencing factors for postoperative new-onset DVT ( P<0.05). Further logistic regression analysis indicated that age (>60 years old), female, and revision surgery were risk factors for postoperative new-onset DVT ( P<0.05). Conclusion: The incidence of anemia is higher among patients with preoperative DVT for THA, and anemia is an independent risk factor for preoperative DVT occurrence in THA. While anemia may not be an independent risk factor for THA postoperative new-onset DVT, the incidence of anemia is higher among patients with postoperative new-onset DVT.

The Validation and Modification of the Caprini Risk Assessment Model for Evaluating Venous Thromboembolism after Joint Arthroplasty.

BACKGROUND: The Caprini risk assessment model (RAM) is the most commonly used tool for evaluating venous thromboembolism (VTE) risk, a high score for arthroplasty can result in patients being classified as high risk for VTE. Therefore, its value in post-arthroplasty has been subject to debate. METHODS: Retrospective data were collected from patients who underwent arthroplasty between August 2015 and December 2021. The study cohort included 3,807 patients, all of whom underwent a thorough evaluation using Caprini RAM and vascular Doppler ultrasonography preoperatively. RESULTS: A total of 432 individuals (11.35%) developed VTE, while 3,375 did not. Furthermore, 32 (0.84%) presented with symptomatic VTE, while 400 (10.51%) were detected as asymptomatic. Additionally, 368 (9.67%) VTE events occurred during the hospitalization period, and 64 (1.68%) cases were detected during postdischarge follow-up. Statistical analysis revealed significant differences between the VTE and non-VTE groups in terms of ages, blood loss, D-dimer, body mass index >25, visible varicose veins, swollen legs, smoking, history of blood clots, broken hip, percent of female, hypertension, and knee joint arthroplasty (p < 0.05). The Caprini score was found to be significantly higher in the VTE group (10.10 ± 2.23) compared with the non-VTE group (9.35 ± 2.14) (p < 0.001). Furthermore, there was a significant correlation between the incidence of VTE and the Caprini score (r = 0.775, p = 0.003). Patients with a score ≥9 are at a high-risk threshold for postoperative VTE. CONCLUSION: The Caprini RAM shows a significant correlation with the occurrence of VTE. A higher score indicates a greater likelihood of developing VTE. The score ≥9 is at particularly high risk of developing VTE.

Bond strength of metal-free polyether-ether-ketone knee prostheses compared to metal knee prostheses with bone cement: A preliminary in vitro study.

BACKGROUND: Total knee arthroplasty is the most effective treatment for advanced-stage knee arthritis, and the majority of knee prostheses are made of metal. Nevertheless, metal prostheses still have several problems. The objective of this study is to introduce new metal-free knee prostheses made of polyether-ether-ketone (PEEK) and to compare their cement bond strength with metal prostheses. METHODS: Twelve sets of knee prostheses were divided into four groups (unloaded PEEK, unloaded Metal, 10 million cycles (MC) PEEK, 10 MC Metal, N = 3 each), and then attached to composite bones using bone cement. Both the 10 MC PEEK and 10 MC Metal groups were subjected to dynamic gait simulations of 10 MC, whereas the other two sets were not. Afterwards, a pull-off strength test was performed on the femoral prostheses and a shear strength test was performed on the tibial prostheses. RESULTS: No apparent cracks were observed in the bone cement after subjecting the PEEK and Metal groups to 10 million cycles of dynamic simulation. No statistically significant differences were observed (p > .05) in the strength tests for unloaded PEEK vs. unloaded Metal, 10 MC PEEK vs.10 MC Metal in the femoral pull-off test, and for unloaded PEEK vs. unloaded Metal in the tibial shear test. The shear strength of 10 MC PEEK was significantly lower (p < .05) compared to that of 10 MC Metal. CONCLUSIONS: By comparing the force analysis of previous investigations on knee prostheses with the failure pattern observed in the PEEK knee prosthesis of this study, which replicates that of the metal prosthesis. We believe that the combination of the peek knee prosthesis with bone cement is reliable. We anticipate that metal-free PEEK knee prostheses will find application in Total Knee Arthroplasty (TKA) in the future, thereby benefiting patients.

The accuracy of an extramedullary femoral cutting system in total knee arthroplasty in patients with severe coronal femoral bowing: a radiographic study.

BACKGROUND: Intramedullary (IM) femoral alignment instrument is imprecise for the coronal alignment in total knee arthroplasty (TKA) in patients with severe lateral bowing of the femur, while the extramedullary (EM) alignment system does not depend on the structure of the femoral medullary cavity. The aim of this retrospective study was to compare the accuracy of postoperative limb alignment with the two femoral alignment techniques for patients with severe coronal femoral bowing. METHODS: From January 2017 to December 2019, patients with end-stage knee osteoarthritis and coronal femoral bowing angle (cFBA) ≥ 5° who underwent total knee arthroplasty TKA at our institution were enrolled in the study. The postoperative hip-knee-ankle (HKA) alignment, femoral and tibial component alignment between the IM group and the EM group were compared on 5° ≤ cFBA < 10° and cFBA ≥ 10°. RESULTS: In patients with 5° ≤ cFBA < 10°, no significant differences were observed in the EM group and IM group, including preoperative and postoperative parameters. However, when analyzing the patients with cFBA ≥ 10°, we found a significant difference in postoperative HKA (4.51° in the IM group vs. 2.23°in the EM group, p < 0.001), femoral component alignment angle (86.84° in the IM group vs. 88.46° in the EM group, p = 0.001) and tibial component alignment angle (88.69° in the IM group vs. 89.81° in the EM group, p = 0.003) between the two groups. Compared to the EM group, the IM group presents a higher rate of outliers for the postoperative HKA and femoral components. CONCLUSIONS: The study showed that severe lateral bowing of the femur has an important influence on the postoperative alignment with the IM femoral cutting system. In this case, the application of EM cutting system in TKA will perform accurate distal femoral resection and optimize the alignment of lower limb and the femoral component.

Is the femoral component flexion affected by the sagittal femoral shaft bowing in conventional intramedullary guided TKA?

BACKGROUND: The aim of the present study was to investigate the influence of sagittal femoral bowing on sagittal femoral component alignment, and whether there was correlation between sagittal femoral component alignment and coronal femoral component alignment. METHODS: We retrospectively reviewed 77 knees in 71 patients who had undergone primary TKA for advanced osteoarthritis. All surgeries were performed by using a standard medial parapatellar approach. The osteotomy was performed with a conventional technique using an intramedullary rod for the femur and a mechanical extramedullary guiding system for the tibia. All patients enrolled in the study were evaluated with full-length lower extremity load-bearing standing scanograms, and the patients had preoperative and postoperative radiographs of the knees. Coronal femoral bowing angle (cFBA), sagittal femoral bowing angle (sFBA), and postoperatively, mechanical tibiofemoral angle of the knee (mTFA), ß angle (femoral component flexion angle) were measured. The radiographic results of both groups were compared using Student's t test. A two-sided Pearson correlation coefficient was obtained to identify the correlations between FBA in the coronal and sagittal planes, as well as FBA and age or BMI, sFBA and ß angle, cFBA and mTFA. Comparison of FSB incidence between different genders was made using Chi-square test. The p value < 0.05 indicates a statistically significant difference. RESULTS: The mean sFBA, cFBA, ß angle, mTFA were 9.34° ± 3.56°(range 1°-16°), 3.25° ± 3.79°(range - 7° to -17°), 3.91° ± 3.15°(range - 1° to -13°), 0.60° ± 1.95°(range - 3° to -6°), respectively. There was no correlation between age and sFBA (CC = 0.192, p = 0.194) or cFBA (CC = 0.192, p = 0.194); similarly, there was no correlation between age and sFBA (CC = 0.067, p = 0.565) or cFBA (CC = 0.069, p = 0.549). The sFBA was correlated with cFBA and ß angle (CC = 0.540, p < 0.01; CC = 0.543, p < 0.01, respectively), and the cFBA was correlated with mTFA (CC = 0.430, p < 0.01). There was no significant difference (p = 0.247) of cFBA between the patients with sFSB and the patients without sFSB. CONCLUSIONS: The current study showed that the sFBA was correlated with cFBA in the patients undergoing TKA and the patients with sFSB usually presented non-cFSB. We also found that sFSB could affect the femoral component alignment in the sagittal plane and cFSB could affect the femoral component alignment in the coronal plane. The sFBA or cFBA was not correlated with age, BMI, or gender.