Enhancing fracture diagnosis in pelvic X-rays by deep convolutional neural network with synthesized images from 3D-CT.

Pelvic fractures pose significant challenges in medical diagnosis due to the complex structure of the pelvic bones. Timely diagnosis of pelvic fractures is critical to reduce complications and mortality rates. While computed tomography (CT) is highly accurate in detecting pelvic fractures, the initial diagnostic procedure usually involves pelvic X-rays (PXR). In recent years, many deep learning-based methods have been developed utilizing ImageNet-based transfer learning for diagnosing hip and pelvic fractures. However, the ImageNet dataset contains natural RGB images which are different than PXR. In this study, we proposed a two-step transfer learning approach that improved the diagnosis of pelvic fractures in PXR images. The first step involved training a deep convolutional neural network (DCNN) using synthesized PXR images derived from 3D-CT by digitally reconstructed radiographs (DRR). In the second step, the classification layers of the DCNN were fine-tuned using acquired PXR images. The performance of the proposed method was compared with the conventional ImageNet-based transfer learning method. Experimental results demonstrated that the proposed DRR-based method, using 20 synthesized PXR images for each CT, achieved superior performance with the area under the receiver operating characteristic curves (AUROCs) of 0.9327 and 0.8014 for visible and invisible fractures, respectively. The ImageNet-based method yields AUROCs of 0.8908 and 0.7308 for visible and invisible fractures, respectively.

Ground kinematically aligned total knee arthroplasty: new personalized technique which enables a stable knee with deep flexion.

PURPOSE: This study aimed to evaluate kinematically aligned total knee arthroplasty (KA-TKA) targeting the neutral ground mechanical axis (MA) (hip-to-calcaneus axis), the line from the hip centre to the bottom of the calcaneus, (ground KA-TKA) in terms of its comparison with tibia-restricted modified KA-TKA (modified KA-TKA). METHODS: This retrospective cohort study included 106 consecutive patients who underwent unilateral KA-TKA for varus osteoarthritis (OA) (60 modified KA-TKAs and 46 ground KA-TKAs). After 1:1 propensity score matching, 60 patients (30 pairs) were matched between the groups with comparable demographic data. The hip-knee-ankle (HKA) angle, coronal femoral component alignment (FCA), and coronal tibial component alignment (TCA) were compared between groups. Intraoperative soft tissue balance, including the joint component gap and varus/valgus balance, was also compared between the groups. One year postoperatively, the clinical outcomes, including the range of motion and 2011 Knee Society Score, were compared between groups. RESULTS: The HKA angle and FCA/TCA were not significantly different between groups. Whereas the varus/valgus balance showed no significant differences between groups, smaller joint component gaps were found throughout the range of motion in the ground KA-TKA group than in the modified KA-TKA group. Despite no difference in clinical scores between groups, a significantly deeper postoperative flexion angle was achieved in the ground KA-TKA group than in the modified KA-TKA group (p < 0.05). CONCLUSION: Targeting neutral ground MA in KA-TKA for patients with varus OA has the potential to provide a better flexion angle with stable intraoperative soft tissue balance.

Prosthetic orientation, limb alignment, and soft tissue balance with bi-cruciate stabilized total knee arthroplasty: a comparison between the handheld robot and conventional techniques.

PURPOSE: This study aimed to examine the prosthetic orientations, limb alignment, intraoperative soft tissue balance, and early clinical outcomes associated with the use of the relatively new handheld robot technique compared to those associated with the use of the conventional alignment guide for bi-cruciate stabilized total knee arthroplasty (TKA). METHODS: This retrospective cohort study compared the prosthetic orientation and limb alignment of 35 patients who underwent TKA using robotic assistance (robot group) with those of patients who underwent TKA using a conventional alignment guide (control group). The coronal femoral component alignment (FCA), coronal tibial component alignment (TCA), and the hip-knee-ankle (HKA) angle were compared between groups. Intraoperative soft tissue balance, including the joint component gap and varus/valgus balance assessed by an offset-type tensor, were also compared between groups. One year postoperatively, the clinical outcomes, including the range of motion and 2011 Knee Society Score (KSS), were compared between groups. RESULTS: The HKA angle and FCA were 0.1° varus and 0.1° varus, respectively, in the robot group and 1.3° varus and 1.3° varus, respectively, in the control group. The difference in the HKA angle and the FCA, but not the TCA, between groups was statistically significant (p < 0.05). The intraoperative soft tissue balance showed more stable joint component gaps and varus/valgus balances throughout the range of motion in the robot group than in the control group. Clinical outcomes of the robot group showed superior 2011 KSS subscales compared to those of the control group. CONCLUSION: The accuracy of the implantations and stable soft tissue balance in the robot group were superior to those of the control group. The robot group also had superior patient-reported scores for early clinical outcomes.

The Effect of Prosthesis Type on Intraoperative Soft-Tissue Balance and Clinical Outcomes in Modified Kinematically Aligned Cruciate-Retaining Total Knee Arthroplasty.

INTRODUCTION: Kinematically aligned total knee arthroplasty (KA-TKA) has gained interest for achieving more favorable clinical outcomes than mechanically aligned TKA. One of the advantages of KA-TKA is reported to be an easy acquisition of intraoperative soft-tissue balance without excessive medial release for varus osteoarthritis. However, we hypothesized that the prosthesis type affects intraoperative soft-tissue balance even in the KA-TKA. The present study aimed to compare intraoperative soft-tissue balance and clinical outcomes of KA-TKAs using single-radius (SR) or multiradius (MR) prostheses. MATERIALS: AND METHODS: Consecutive 70 cruciate-retaining modified KA-TKAs (31 SR and 39 MR) were performed in patients with varus-type osteoarthritis using a navigation system. Intraoperative soft-tissue balance including joint component gap and varus/valgus balance was measured with femoral component placement and patellofemoral joint reduction throughout the range of motion using offset-type tensor and compared between the two groups. Two years postoperatively, the range of motion and 2011 Knee Society Scores were compared between the two groups. RESULTS AND CONCLUSION: Joint component gaps showed no significant differences between the two groups from 0 to 30 degrees of flexion. However, during 60 to 120 degrees of flexion, joint component gaps of SR group showed significantly larger values than those of MR group (p < 0.05). There were no significant differences in varus/valgus balance throughout the range of motion between the two groups. The postoperative clinical outcomes showed no significant differences between the two groups. INTERPRETATION: Despite no difference in clinical outcomes, joint component gap showed different patterns due to the prosthesis type in modified KA-TKAs.

Knee Stability following Posterior-Stabilized Total Knee Arthroplasty: Comparison of Medial Preserving Gap Technique and Measured Resection Technique.

Novel medial preserving gap technique (MPGT) focuses on medial compartment stability and allows lateral physiological laxity. This study aimed to compare the MPGT with the measured resection technique (MRT) to determine which provides better postoperative knee stability after posterior-stabilized total knee arthroplasty (PS-TKA). Primary PS-TKA, using either MPGT (n = 65) or MRT (n = 65), was performed in 130 patients with varus knee osteoarthritis. Postoperative knee stabilities at extension and flexion were assessed using varus-valgus stress radiographs and stress epicondylar view, respectively (at 1 month, 6 months, 1 year, and 3 years postoperatively). The distance between the femoral prosthesis and polyethylene insert was measured on each medial and lateral side, defined as the medial joint opening (MJO) and lateral joint opening (LJO), respectively. Decreasing MJO or LJO translated to increasing postoperative stability. The femoral external rotation angle was compared between the two surgical techniques; postoperative knee stability was also compared between the medial and lateral compartments, as well as the surgical techniques. A significant difference was found in the femoral external rotation angle between MPGT (4.2 ± 0.2 degrees) and MRT (3.6 ± 0.1 degrees, p < 0.01). Postoperative MJOs both at extension and flexion were significantly smaller than LJOs using MPGT and MRT at all time points (p < 0.05). MJOs and LJOs at extension using MPGT were significantly smaller than those when using MRT, at 1 and 3 years postoperatively (p < 0.05). Furthermore, MJOs at flexion using MPGT were significantly smaller than those when using MRT at 6 months, 1 year, and 3 years postoperatively (p < 0.05). MPGT provided higher postoperative medial knee stability than MRT both at extension and flexion, even at 3 years after PS-TKA. This suggests that this newly developed surgical technique is a more feasible option than MRT for the preservation of postoperative medial knee stability.

Continuous Local Antibiotic Perfusion (CLAP) for Post-operative Infection of Open Tibial Fractures: A Case Report.

Introduction: We encountered a case of post-operative infection of an open tibial fracture that was controlled by continuous local antibiotic perfusion (CLAP), a novel method of fracture-related infection (FRI) that we have developed. CLAP is a procedure in which a bone marrow needle and a double lumen tube are placed in the infected area, and an appropriate concentration of antimicrobial agent is continuously administered and perfused. Case Report: The patient was a 78-year-old woman. She was hit by a motor vehicle and fell to the farmyard floor. She suffered multiple traumas, including a lower leg open fracture, multiple rib fractures, clavicle fracture, pelvic fracture, mandibular fracture, and liver injury. Her tibial fracture was a Gustilo-Anderson type IIIA open fracture. After debridement and external fixation of the tibial open fracture on the same day, open reduction and internal fixation with an intramedullary nail was performed 3 days after the injury. Twelve days after the injury, local heat and redness were observed at the nail insertion wound and the posteromedial calf, and a purulent clot was discharged from the open wound. We performed curettage of the lesion and retained the implant. CLAP was then constructed to perfuse local antibiotics along the nail and large hematoma area. Locally, the inflammation improved and the inflammatory response became negative 3 weeks after the initiation of CLAP. Six months after surgery, bony union was achieved. At present, 3.5 years after the internal operation, there is no sign of infection, and the patient has returned to her pre-injury life with no abnormalities in motor function. Conclusion: CLAP may be a novel treatment method that can be expected to achieve bone healing while preserving the implant in FRI cases after open tibial fracture.

Influence of posterior tibial slope on sagittal knee alignment with comparing contralateral knees of anterior cruciate ligament injured patients to healthy knees.

Posterior tibial slope (PTS) has been known to contribute to anterior-posterior knee stability and play an essential biomechanical role in knee kinematics. This study aimed to investigate the effect of PTS on single-leg standing sagittal knee alignment of the intact knee. This study included 100 patients with unilateral ACL injury knee (ACL injury group, 53 patients) or with the normal knee (control group, 47 patients). The single-leg standing sagittal alignment of the unaffected knees of the ACL injury group and normal knees of the control group were assessed radiographically with the following parameters: knee extension angle (EXT), PTS, PTS to the horizontal line (PTS-H), femoral shaft anterior tilt to the vertical axis (FAT), and tibial shaft anterior tilt to the vertical axis (TAT). PTS was negatively correlated with EXT and positively correlated with TAT. EXT was significantly larger in the ACL injury group, whereas TAT was smaller in the ACL injury group. Patients with larger PTS tend to stand with a higher knee flexion angle by tilting the tibia anteriorly, possibly reducing tibial shear force. Patients with ACL injury tend to stand with larger EXT, i.e., there is less preventive alignment to minimize the tibial shear force.

Continuous local antibiotic perfusion: A treatment strategy that allows implant retention in fracture-related infections.

PURPOSE: Fracture-related infections are difficult to treat because of the formation of biofilms around implants. Systemic antibiotics are notoriously ineffective against biofilms due to their insufficient penetration of tissues with poor vascularity. The goal of treating fracture-related infections is to achieve bone union while retaining the implant. Our proposal of continuous local antibiotic perfusion is a sustained local delivery system of sufficient antibiotics to bone and soft tissue infection sites, including to bone marrow via needles as intra-medullary antibiotics perfusion and to soft-tissue via double-lumen subcutaneous tubes as intra-soft tissue perfusion. METHODS: In this study, we examined the outcomes of 40 patients treated for fracture-related infections using continuous local antibiotic perfusion between 2015 and 2021 at Steel Memorial Hirohata Hospital, Himeji, Japan. RESULT: The antibiotic used for continuous local antibiotic perfusion was gentamicin in all cases. Implant removal was required in five patients. Two patients required toe amputation and knee arthrodesis, while the remaining 38 patients achieved fracture union. Only one case of transient acute renal injury as a systemic side effect was observed, but it soon resolved. The blood concentration of gentamicin could be adjusted to less than the trough level. CONCLUSIONS: Continuous local antibiotic perfusion is a novel local drug delivery system that has the potential of delivering sufficient concentrations of antibiotics with few systemic side effects; it is a useful option for the treatment of fracture-related infections.

Evaluation of morphological characteristics for incomplete discoid medial meniscus with an oversized posterior segment.

BACKGROUND: A discoid medial meniscus is rare in comparison with a discoid lateral meniscus. We encountered a new type of incomplete discoid with an oversized posterior segment. Therefore, this study aimed to report cases of medial meniscus with an oversized posterior segment and analyze the morphological characteristics by comparing them to cases with a discoid medial meniscus and normal medial meniscus. METHODS: Four patients with an oversized posterior segment medial meniscus (oversize group, mean age: 25.3 ± 12.0 years) and seven patients with a discoid medial meniscus (discoid group, mean age: 34.4 ± 19.6) were identified using magnetic resonance imaging (MRI) and diagnosed by arthroscopic findings in our hospital. Fifty patients without medial meniscal injury were retrospectively selected as the normal group (normal group, mean age: 24.0 ± 11.3 years). The clinical symptoms were examined. The anteroposterior (AP) length of both the anterior and posterior segments, AP length ratio of the posterior segment to the AP length of the medial tibial plateau, and mediolateral (ML) width of the mid-body of the medial meniscus were also evaluated using MRI and compared among the three groups. RESULTS: All patients in the oversize group complained of medial knee pain during deep knee flexion. In sagittal MRI, posteriorly deviated indentations were also observed at the medial tibial plateau in all cases in the oversize group. There was a significant difference in the AP length of the posterior segment between the normal and oversize groups (14.3 ± 2.8 vs. 23.6 ± 2.8 mm, P < 0.001), whereas there was no significant difference in the AP length of the anterior segment (9.1 ± 2.1 vs. 9.5 ± 1.9 mm, P = 0.869). The ML width of the mid-body in the normal, oversize, and discoid groups was 9.3 ± 1.8, 19.9 ± 2.6, and 25.8 ± 1.9 mm, respectively (normal vs. oversize group: P < 0.001, oversize vs discoid group: P = 0.01, normal vs. discoid group: P < 0.001). CONCLUSIONS: Oversized posterior and normal anterior segments characterize this new type of incomplete discoid medial meniscus as a morphological abnormality.

Evaluation of consistency of patient-satisfaction score in the 2011 Knee Society Score to other patient-reported outcome measures.

BACKGROUND: Patient-reported outcome measures (PROMs) are important aspects of evaluating clinical outcomes after total knee arthroplasty (TKA). The patient-satisfaction score in the 2011 Knee Society Score (KSS) is one of the most frequently used questionnaires; however, patient satisfaction is a subjective assessment and is affected by multiple factors. Therefore, we evaluated correlations between the patient-satisfaction score in the 2011 KSS and that of other categories of the 2011 KSS as well as other PROMs. Furthermore, the ceiling effects of each PROMS were also investigated. METHODS: We enrolled 85 patients aged ≥65 years who underwent cruciate retaining TKA. Patients completed various questionnaires, including the 2011 KSS, Forgotten Joint Score-12 (FJS-12), EuroQol 5 Dimension (EQ-5D), and Geriatric Locomotive Function Scale (GLFS-25), one year after TKA. Simple linear regression analysis was used to evaluate correlations between each PROM and the patient-satisfaction score in the 2011 KSS. Ceiling effects of the patient-satisfaction score in the 2011 KSS, FJS-12, EQ-5D and GLFS-25 were evaluated by comparing the number of patients categorized into the top 10% with each PROM. RESULTS: All scores were significantly correlated (p < 0.001) with the patient-satisfaction score in the 2011 KSS (symptoms: r = 0.69, functional activities: r = 0.69, patient expectations: r = 0.73, FJS-12: r = 0.72, EQ-5D: r = 0.67, GLFS-25: r = -0.74). The patient-satisfaction score in the 2011 KSS and GLFS-25 showed a ceiling effect. On the other hand, this effect was not observed in the results of the FJS-12 and EQ-5D. CONCLUSIONS: The patient-satisfaction score in the 2011 KSS correlated with other PROMs, and the indicated level of satisfaction was consistent. The results of the FJS-12 and EQ-5D had good positive correlation to patient satisfaction without ceiling effect.

Intra-medullary antibiotics perfusion (iMAP) for the control of fracture-related infection early after osteosynthesis.

PURPOSE: In our hospital, cases of bone and soft tissue infections have been treated with continuous local antibiotics perfusion that allows for continuous circulation of antibiotics throughout the infected lesion. We termed this treatment "intramedullary antibiotics perfusion (iMAP)" for bone infection such as fracture-related infection (FRI) and "intrasoft tissue antibiotics perfusion" for soft tissue infection. Many cases are treated with both modalities. To introduce iMAP, this study focused on the patients with FRI treated with iMAP and reviewed their treatment outcomes. METHODS: We included 10 patients with FRI treated with iMAP between 2004 and 2017. The iMAP needles were inserted near the infected lesion, and an aminoglycoside antimicrobial was continuously administered. Patient characteristics, pathogenic bacteria, administered antibiotics, duration of administration, concentrations of antibiotics in blood and leachate fluid, fracture union rate, implant retention rate, and complications were studied. RESULTS: The mean age of patients was 59.9 years, and the mean follow-up period was 2.5 years. Affected bones were the tibia (n = 8), humerus (n = 1), and fibula (n = 1). Deep infections developed on average 29.9 days after osteosynthesis. Pathogenic bacteria were methicillin-susceptible Staphylococcus aureus (n = 6), methicillin-resistant S. aureus (n = 2), and unknown (n = 2). Average iMAP duration was 17.1 days. In all patients, infection was eradicated while preserving the implants, and fracture union was achieved without complications. CONCLUSION: iMAP is a novel local drug delivery system allowing high concentrations of antibiotics to be administered without complications and is useful in the treatment of FRI.

Detecting pelvic fracture on 3D-CT using deep convolutional neural networks with multi-orientated slab images.

Pelvic fracture is one of the leading causes of death in the elderly, carrying a high risk of death within 1 year of fracture. This study proposes an automated method to detect pelvic fractures on 3-dimensional computed tomography (3D-CT). Deep convolutional neural networks (DCNNs) have been used for lesion detection on 2D and 3D medical images. However, training a DCNN directly using 3D images is complicated, computationally costly, and requires large amounts of training data. We propose a method that evaluates multiple, 2D, real-time object detection systems (YOLOv3 models) in parallel, in which each YOLOv3 model is trained using differently orientated 2D slab images reconstructed from 3D-CT. We assume that an appropriate reconstruction orientation would exist to optimally characterize image features of bone fractures on 3D-CT. Multiple YOLOv3 models in parallel detect 2D fracture candidates in different orientations simultaneously. The 3D fracture region is then obtained by integrating the 2D fracture candidates. The proposed method was validated in 93 subjects with bone fractures. Area under the curve (AUC) was 0.824, with 0.805 recall and 0.907 precision. The AUC with a single orientation was 0.652. This method was then applied to 112 subjects without bone fractures to evaluate over-detection. The proposed method successfully detected no bone fractures in all except 4 non-fracture subjects (96.4%).

Treatment of Chronic Osteomyelitis of the Femur by Intramedullary Antibiotic Perfusion (iMAP): A Case Report.

Introduction: Chronic osteomyelitis is difficult to cure definitively, because local areas are often covered with sequestrum and scar tissues with a poor blood flow; these may render systemic antibiotic administration ineffective. We present a case of chronic osteomyelitis that was successfully treated with continuous local antibiotic perfusion (CLAP) through an intramedullary antibiotic perfusion (iMAP) pin. Case Presentation: A 65-year-old man who suffered an episode of the right femoral osteomyelitis at the age of 15 years experienced a relapse at the age of 63 years. Systemic administration of antibiotics could not control the infection; thus, a surgery was performed. A bone marrow needle (i.e., an iMAP pin; diameter: 3 mm) was percutaneously inserted, from the front, distally and proximally to the cystic lesion in the distal femur. After washing through the iMAP pins, the pins were left indwelling. A closed drain tube was placed on the bone surface, which was close to the fistula of the bone marrow lesion. CLAP therapy was then initiated. Gentamicin was continuously infused through the iMAP pin at a rate of 2 mL/h and drained using the tube. Accordingly, 2.4 mg/mL, 1.2 mg/mL, and 1.2 mg/mL of gentamicin were administered for 4 days using two iMAP pins, for 5-8 days using two iMAP pins, and for 9-15 days using one iMAP pin, respectively, with a syringe pump. The iMAP pins and the drain tube were removed 15 days after the initiation of the CLAP therapy. The C-reactive protein level normalized 25 days postoperatively. The patient recovered full range of motion of the knee joint and recreational sports activity without recurrence of osteomyelitis for 5 years after the therapy. Conclusions: CLAP therapy allows local administration of a sufficient concentration of antibiotics and device removal after treatment is simple. This may be a novel treatment for chronic osteomyelitis.

Sequential changes in lower extremity function after total knee arthroplasty.

PURPOSE: The effectiveness of total knee arthroplasty (TKA) for recovering ambulation and balance functions has not been investigated in detail. The present study aimed to measure functional changes in the lower limb before and after TKA by measuring ambulation function with the 3 m Timed Up and Go (TUG) test and balance function using one-leg standing time (ST). METHODS: The study included 137 patients (116 women and 21 men) with osteoarthritis of the knee who underwent primary TKA. The mean age of the patients was 74.4 years. The mean postoperative hospital stay for rehabilitation was 23.9 days. The TUG test and ST were performed preoperatively, 2 weeks postoperatively, at discharge, and 3, 6, and 12 months postoperatively. These results from these six measurements were also compared using one-way repeated measures analysis of variance. RESULTS: The TUG test and ST were significantly improved at 3 months after surgery. However, both the TUG test and ST did not improve further from 3 months to 6 months postoperatively or from 6 months to 1 year postoperatively. CONCLUSION: TKA is useful for restoring lower limb function, as both ambulation and balance functions were significantly improved 3 months after surgery. However, no further improvement in ambulation or balance function was recognized beyond 3 months.

Comparison of intraoperative soft tissue balance measurement between two tensor systems in total knee arthroplasty.

BACKGROUND: Differences in measurement outcomes using different tensors in total knee arthroplasty (TKA) remain unknown. This study aimed to compare intraoperative soft tissue balance between two measurement systems in TKA. METHODS: This study included 24 cruciate-retaining (CR) and 27 posterior-stabilized (PS) TKAs for varus-type osteoarthritis. All TKAs were performed with the measured resection technique. Intraoperative soft tissue balance was assessed with femoral component placement and patellofemoral joint reduction throughout the range of motion. Measurements were performed using the Offset Repo-Tensor (Zimmer) and Ligament Sensor Tensor (Depuy). Joint component gaps and varus/valgus ligament balance were compared statistically in CR and PS TKAs. RESULTS: Joint component gaps with the Offset Repo-Tensor were significantly larger at 0°, 10°, 30°, and 60° of knee flexion in CR TKA and at all knee flexion angles, except 0° and 135°, in PS TKA than those with the Ligament Sensor Tensor (P < .05). Varus balance with the Offset Repo-Tensor was significantly larger at 0°, 10°, and 30° of knee flexion in CR TKA and at 10°, 30°, 60°, 90°, and 120° of knee flexion in PS TKA than that with the Ligament Sensor Tensor (P < .05). CONCLUSION: Surgeons should consider the discrepancy in assessing intraoperative soft tissue balance depending on the tensor used. The Ligament Sensor Tensor tended to underestimate soft tissue balance in CR and PS TKAs compared with the Offset Repo-Tensor, especially in PS TKA. Thus, surgeons should know the difference in values between the offset-type tensor with consistent distraction force and a spring-loaded tensor.

Intraoperative Soft Tissue Balance/Kinematics and Clinical Evaluation of Modified Kinematically versus Mechanically Aligned Total Knee Arthroplasty.

Recently, kinematically aligned total knee arthroplasty has been found to achieve better clinical outcomes than mechanically aligned TKA. Despite the good clinical outcomes that are reported at short- to mid-term follow-up, intraoperative variables that are associated with a better outcome have not been measured. Therefore, this study was conducted to compare intraoperative kinematics/soft tissue balance and the clinical outcomes of patients who underwent modified kinematically (restricted tibial cut) or mechanically aligned total knee arthroplasty. Sixty cruciate-retaining total knee arthroplasties (30 modified kinematically [3-degree varus and 7-degree posterior slope in tibial cut] and 30 mechanically aligned) were performed in patients with varus-type osteoarthritis using a navigation system. Intraoperative kinematics assessed by the navigation system and soft tissue balance assessed by an offset-type tensor were compared between the groups. One year postoperatively, the range of motion and 2011 Knee Society scores were compared between the groups. Kinematic assessment exhibited that tibial internal rotation during flexion was significantly maintained in the kinematic compared with the mechanical group (p < 0.05). Varus/valgus ligament balance at 90 and 120 degrees of flexion significantly maintained lateral laxity in the kinematic compared with the mechanical group (p < 0.05). Improvement of flexion angles, functional activity scores, and patient satisfaction were significantly better in the kinematic than in the mechanical group (p < 0.05). Modified kinematically aligned cruciate-retaining total knee arthroplasty maintained more tibial internal rotation and lateral laxity during flexion than mechanically aligned total knee arthroplasty; thus, the former may result in better clinical outcomes.

Medial knee stability at flexion increases tibial internal rotation and knee flexion angle after posterior-stabilized total knee arthroplasty.

BACKGROUND: Soft-tissue balance is an important element for the success of total knee arthroplasty; however, the influence of intraoperative soft-tissue balance on knee kinematics in posterior-stabilized-total knee arthroplasty remains unknown. We investigated whether intraoperative soft-tissue balance could influence knee kinematics and flexion angle after posterior-stabilized-total knee arthroplasty. METHODS: This study included 30 patients with knee osteoarthritis and varus alignment who underwent posterior-stabilized total knee arthroplasty; intraoperative soft-tissue balance parameters, such as varus ligament balance and joint component gap, were assessed by an offset-type tensor at knee flexion angles of 0°, 10°, 30°, 60°, 90°, 120°, and 135°. Medial and lateral compartment gaps were calculated. The amount of tibial internal rotation was determined between 60° and 135° flexion by the navigation system. Simple linear regression analysis was used to analyze the effects of intraoperative soft-tissue balance on tibial internal rotation. Linear regression analysis was used to assess correlation between tibial internal rotation and postoperative knee flexion angle. FINDINGS: Medial compartment gaps at 60° (r = -0.57, P < 0.05) and 90° (r = -0.60, P < 0.05) of flexion were significantly negatively correlated with tibial internal rotation. Moreover, tibial internal rotation showed a significant correlation with the 2-year postoperative knee flexion angle (r = 0.50, P < 0.05) and improvement in knee flexion angle (r = 0.61, P < 0.05). INTERPRETATION: Thus, smaller medial compartment gaps at 60° and 90° of flexion play an important role in achieving medial pivot motion with tibial internal rotation; moreover, tibial internal rotation provides a better flexion angle after posterior-stabilized total knee arthroplasty.

Effect of intraoperative soft tissue balance on postoperative recovery of ambulatory and balancing function in posterior-stabilized total knee arthroplasty.

BACKGROUND: The effectiveness of total knee arthroplasty (TKA) on ambulatory and balancing function recovery should be quantitatively investigated. The present study aimed to evaluate ambulatory function using 3m-timed up and go (TUG) test and balancing function using one-leg standing time (ST) from before and after TKA, and to analyze the effects of intraoperative soft tissue balance on the postoperative improvement of their functions after TKA. METHODS: The study included 65 patients with varus-type knee osteoarthritis who underwent primary posterior-stabilized (PS) TKA. The TUG test and ST were performed preoperatively, 1 month and 12 months after TKA. The intraoperative soft tissue balance, medial and lateral joint looseness (MJL, LJL) were evaluated with both femoral trial in place and patellofemoral joint reduced using the OFR tensor® with the knee at 0, 10, 30, 45, 60, 90, 120, and 135°. The influences of MJL and LJL on the improvement in TUG test time and ST and the 2011 Knee Society Knee Scoring System (2011 KSS) 12 months after TKA were investigated. RESULTS: The mean TUG test times and ST were 12.7 and 13.1, 13.5 and 15.4, and 10.9 and 19.2 s preoperatively, 1 month and 12 months after TKA, respectively. The MJL at 10, 30 and 90° flexion was significantly negatively correlated with improvement in the TUG test time and the MJL at 0° flexion was significantly negatively correlated with improvement in the ST. However, the LJL was not significantly correlated with improvement in the TUG test time and the ST. The MJL at 45, 60, and 90° flexion was significantly negatively correlated with the 12-month postoperative score on the activities subscale of the 2011 KSS. CONCLUSIONS: The higher intraoperative medial knee stability may be associated with the better postoperative improvement in ambulatory function and activities subscale of the 2011 KSS after PS-TKA.

Intraoperative soft tissue balance using novel medial preserving gap technique in posterior-stabilized total knee arthroplasty: comparison to measured resection technique.

PURPOSE: To investigate intraoperative soft tissue balance with femoral component trial in place using a novel medial preserving gap technique, focusing on medial compartment stability and allowing lateral physiological laxity, with compared with using a measured resection technique in posterior-stabilized (PS) total knee arthroplasty (TKA). METHODS: Primary PS TKA, using either medial preserving gap technique (n = 127) or measured resection technique (n = 148), was performed in 275 subjects with varus knee osteoarthritis. Intraoperative soft tissue balance with femoral component in place was assessed using Offset Repo-Tensor with 40 lbs. of joint distraction force throughout the range of motion, and medial and lateral compartment gaps (mm) were calculated. Medial and lateral joint gap changes (mm) were calculated by subtracting the medial/lateral compartment gap at 0° from the medial/lateral compartment gap at each knee flexion angle, respectively. RESULTS: Medial and lateral joint gap changes in medial preserving gap technique were significantly smaller than measured resection technique respectively (mean difference between two procedures: medial; 0.9 ± 0.2 mm, lateral; 1.0 ± 0.3 mm). Medial and lateral joint gaps were significantly changed during knee flexion in measured resection technique, whereas medial and lateral joint gaps were not significantly changed during mid-to-deep knee flexion (30°-90° in medial, 30°-120° in lateral) in medial preserving gap technique. CONCLUSIONS: Medial preserving gap technique provided more consistent intraoperative soft tissue balance during knee flexion than the measured resection technique, suggesting that this novel technique can be utilized to obtain a more stable joint gap in PS TKA. LEVEL OF EVIDENCE: III.

The Influence of Postoperative Knee Stability on Patient Satisfaction in Cruciate-Retaining Total Knee Arthroplasty.

BACKGROUND: Although knee stability is well known as an important element for the success of total knee arthroplasty (TKA), the direct relationship between clinical outcomes and knee stability is still unknown. The purpose of this study was to determine if postoperative knee stability and soft-tissue balance affect the functional outcomes and patient satisfaction after cruciate-retaining (CR) TKA. METHODS: Fifty-five patients with varus osteoarthritis of the knee who underwent CR TKA were included in this study, and their postoperative knee stability was assessed by stress radiography at extension and flexion 1 month postoperatively. Timed Up and Go test, patient-derived clinical scores using the 2011 Knee Society Score, and Forgotten Joint Score-12 were also assessed at 1 year postoperatively. The effects of stability parameters on clinical outcomes were analyzed using Spearman's rank correlation. RESULTS: Medial stability at both knee extension and flexion had significant correlations with the shorter Timed Up and Go test and the higher patient satisfaction. Moreover, lateral laxity at extension was significantly correlated with the better patient satisfaction and Forgotten Joint Score-12. However, these correlation coefficients in this study were low in the range of 0.32-0.51. CONCLUSION: Medial stability and lateral laxity play an important role in influencing 1-year postoperative clinical outcomes after CR TKA. However, we should keep in mind that these correlations are weak with coefficients at 0.50 or less and the clinical results are also affected by various other factors.