Management of open fracture and related complications: the Japanese way.

Open fractures continue to be a challenging clinical problem throughout the world, and Japan is no exception. Surgeons are faced with critical decisions throughout the care of these injuries that can have significant effects in clinical outcome, ranging from the type and timing of antibiotic administration, fixation, soft-tissue management, and interventions for postfracture complications. In October 2022, the Japanese Society for Fracture Repair (JSFR) was invited to represent Japan as the Guest Nation society at the 38th Annual Meeting of the Orthopaedic Trauma Society held in Tampa, Florida. The JSFR organized a symposium, entitled "Management of Open Fracture and related complications-the Japanese way," that featured cutting-edge approaches to open fractures in their country, including presentations on the "fix-and-flap" approach, local antibiotics perfusion delivery, and a "chipping" method for the stimulation of bone healing. This article summarizes the content of these 3 presentations from that symposium.

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.

Effects of high antibiotic concentrations applied to continuous local antibiotic perfusion on human bone tissue-derived cells.

Aims: Continuous local antibiotic perfusion (CLAP) has recently attracted attention as a new drug delivery system for orthopaedic infections. CLAP is a direct continuous infusion of high-concentration gentamicin (1,200 µg/ml) into the bone marrow. As it is a new system, its influence on the bone marrow is unknown. This study aimed to examine the effects of high-concentration antibiotics on human bone tissue-derived cells. Methods: Cells were isolated from the bone tissue grafts collected from six patients using the Reamer-Irrigator-Aspirator system, and exposed to different gentamicin concentrations. Live cells rate, apoptosis rate, alkaline phosphatase (ALP) activity, expression of osteoblast-related genes, mineralization potential, and restoration of cell viability and ALP activity were examined by in vitro studies. Results: The live cells rate (the ratio of total number of cells in the well plate to the absorbance-measured number of live cells) was significantly decreased at ≥ 500 µg/ml of gentamicin on day 14; apoptosis rate was significantly increased at ≥ 750 µg/ml, and ALP activity was significantly decreased at ≥ 750 µg/ml. Real-time reverse transcription-polymerase chain reaction results showed no significant decrease in the ALP and activating transcription factor 4 transcript levels at ≥ 1,000 µg/ml on day 7. Mineralization potential was significantly decreased at all concentrations. Restoration of cell viability was significantly decreased at 750 and 1,000 µg/ml on day 21 and at 500 µg/ml on day 28, and ALP activity was significantly decreased at 500 µg/ml on day 28. Conclusion: Our findings suggest that the exposure concentration and duration of antibiotic administration during CLAP could affect cell functions. However, further in vivo studies are needed to determine the optimal dose in a clinical setting.

Novel Local Antifungal Treatment for Fungal Periprosthetic Joint Infection With Continuous Local Antibiotic Perfusion: A Surgical Technique.

Fungal periprosthetic joint infections are one of the most intractable orthopedic disorders. Continuous local antibiotic perfusion allows direct administration of the antifungal agent micafungin into the local infection area at biofilm-disruptive concentrations, while controlling the dead space in addition to conventional treatment. Although the appropriate use of continuous local antibiotic perfusion requires familiarity with the characteristics of local antibiotic perfusion, it is a versatile treatment modality that can improve the clinical outcomes of fungal periprosthetic joint infection in combination with conventional treatment methods.

Open fractures: Current treatment perspective.

Severe open fractures present challenges to orthopaedic surgeons worldwide, with increased risks of significant complications. Although different global regions have different resources and systems, there continue to be many consistent approaches to open fracture care. Management of these complex injures continues to evolve in areas ranging from timing of initial operative debridement to the management of critical-sized bone defects. This review, compiled by representative members of the International Orthopaedic Trauma Association, focuses on several critical areas of open fracture management, including antibiotic administration, timing of debridement, bone loss, soft tissue management, and areas of need for future investigation.

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.

Continuous Local Antibiotics Perfusion Therapy for Acute Deep Infections after Open Fractures.

Unresolved bone and soft tissue infections remain a great hindrance to fracture management worldwide, both economically and functionally for the patient. For this purpose, the benefits of local antibiotic administration besides systemic therapy have been elucidated. We present a retrospective descriptive analysis of six patients (4 males and 2 females) with acute deep infections after open fractures managed using the continuous local antibiotic perfusion (CLAP) therapy. After sufficient debridement, gentamicin solution concentrated at 1,200 µg/mL was continuously infused (2 mL/h) for 7-12 days by syringe pump through an inlet tube placed on the infected area. The antibiotics injected into the infected area were both collected and perfused by negative pressure using a negative-pressure wound therapy system. After an average of 9.5 days of CLAP therapy, symptoms of infection disappeared, and the bacterial culture was negative. There were no cases of recurrence during the follow-up period, and no complications, such as acute renal failure, ototoxicity, allergic or hypersensitivity reactions, and impaired fracture healing, were observed. All six cases were successfully managed with the CLAP therapy without any serious side effects. CLAP therapy may be a potential treatment option for acute deep infections after open fractures.

A novel treatment strategy using continuous local antibiotic perfusion: A case series study of a refractory infection caused by hypervirulent Klebsiella pneumoniae.

BACKGROUND: Conventional topical antimicrobial therapy cannot maintain a constant local concentration, resulting in uncontrolled infection and complications. We propose continuous local antibiotic perfusion (CLAP), which can maintain a constant appropriate local antibiotic concentration for a long time with less invasiveness and complications. CLAP is clearly different from traditional treatment because it uses negative pressure to direct the continuously infused antibiotic solution to the center of infection and excrete it outside the body. This study aimed to demonstrate the effectiveness of CLAP by presenting cases in which even refractory bone and soft-tissue infections caused by the hypervirulent Klebsiella pneumoniae (hvKp) could be cured without significant tissue loss and dysfunction. METHODS: This study is a case series in which four patients with limb infection due to hvKp were treated by CLAP. hvKp was defined by a positive string test. The therapy included intra-soft-tissue antibiotic perfusion and intramedullary antibiotic perfusion. Gentamicin (60 mg/50 cc) was infused continuously through dual-lumen tubes and bone marrow needles at low-flow rates (2 mL/h). Negative pressure was used to collect the antimicrobial solution and eliminate the dead space. RESULTS: The infection was controlled in all four patients after a mean period of 44.3 days. The mean maximum blood concentration of gentamicin was 1.6 µg/dL, and no cases of renal dysfunction or ototoxicity occurred. After CLAP, wound closure was required in two patients and iliac bone grafting was required in one patient. As sequelae, there were one case of osteoarthritis and one case of higher brain dysfunction due to hypoxia. CONCLUSIONS: Our results suggest that intractable hvKp infections can be controlled by CLAP. CLAP may give us the option to directly control local infections with less systemic complications. Therefore, it is considered a valuable treatment for further basic and clinical research, and this research report may be a first step.

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.

Insufficiency and deficiency of vitamin D in elderly patients with fragility fractures of the hip in the Japanese population.

BACKGROUND: Data of vitamin D sufficiency in Asian patients with osteoporotic fragility hip fractures are limited. This study aimed to obtain data from the Japanese population. METHODS: Patients aged 60 years or older with hip fractures were prospectively enrolled. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured. Levels were compared between patients receiving and not receiving treatment for osteoporosis, those with and without previous contralateral hip fractures, and those with femoral neck versus trochanteric fractures. Sex-based differences were also assessed. The serum levels in patients younger than 60 years with extremity fractures were assessed, and differences between elderly and younger patients were evaluated. The individual correlation between 25(OH)D levels and the ultraviolet (UV) index and age was analyzed in elderly patients with hip fractures. RESULTS: The data of 360 patients (aged 84.7 ± 8.2 years), comprising 80 men and 280 women, were analyzed. The mean 25(OH)D level was 16.5 ± 7.2 ng/mL. The prevalence of vitamin D insufficiency (25(OH)D <30 ng/mL) and deficiency (25(OH)D <20 ng/mL) was 93.9% and 71.7%, respectively. A significant difference was noted in the prevalence of vitamin D deficiency between patients with and without previous contralateral hip fractures. Age and 25(OH)D levels were found to be correlated, with no correlation between the UV index and the 25(OH)D levels. The 25(OH)D level in the younger population (n = 123) was 20.7 ± 8.6 ng/mL, which was significantly higher than that of the elderly. CONCLUSION: Perennial vitamin D insufficiency is prevalent in elderly Japanese patients with hip fractures.

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.

Clinical and radiological results of locking plate fixation for periprosthetic femoral fractures around hip arthroplasties: a retrospective multi-center study.

BACKGROUND: Osteosynthesis of periprosthetic femoral fractures around hip arthroplasties is challenging, and locking plate fixation has been found to be a reasonable treatment. However, there is a paucity of evidence of the extent to which patients recover their activities of daily living (ADL). The purpose of this study was to study the clinical results, particularly recovery of ADL, radiological results, and potential complications arising from the use of locking plate fixation for periprosthetic femoral fractures around hip arthroplasties. METHODS: We conducted a retrospective, multi-center study. Patients with periprosthetic femoral fractures around hip arthroplasties who were treated by osteosynthesis with use of locking plates and who underwent follow-up for at least 6 months postoperatively were enrolled in the study. For each patient, recovery of ADL, in terms of social and ambulatory recovery and Parker mobility score, were compared before fracture and at last follow-up. Postoperative complications were investigated. Bony union, loss of reduction, and malunion were assessed radiologically. RESULTS: Thirty-two patients were enrolled in this study. Mean follow-up was 25.1 months. For 84.4, 68.8, and 53.1% of patients, respectively, social status, ambulation, and Parker mobility score at last follow-up were determined to be equal to that before the fracture. Bony union was observed for 30 patients within the follow-up period. Four patients had not achieved bony union 6 months postoperatively. There was no loss of reduction, malunion, or implant breakage, and no infection. For one patient each, partial pullout of the locking screws and a supracondylar fracture at the plate end were observed, and additional surgery was required. CONCLUSIONS: Our results reveal that locking plate fixation provided sufficient stability for satisfactory recovery of ADL for most elderly patients with periprosthetic femoral fractures around hip arthroplasties.

Influence of intra-operative parameters on postoperative early recovery of active knee flexion in posterior-stabilized total knee arthroplasty.

PURPOSE: Active knee flexion is more important for daily activities than passive knee flexion. The hypothesis is that the intra-operative parameters such as osteotomized bone thickness and soft tissue balance affect the postoperative active flexion angle in total knee arthroplasty (TKA). Therefore, we evaluate the influence of intra-operative parameters on postoperative early recovery of active flexion after posterior-stabilized (PS) TKA. METHODS: The subjects were 45 osteoarthritic knees undergoing primary PS TKA with anterior-reference technique. Intra-operative soft tissue balance was measured using an offset type tensor, and each osteotomized bone thickness was also measured. Pre- and postoperative active knee flexion angles were measured using lateral radiographs. Liner regression analysis was used to determine the influence of these intra-operative parameters on postoperative active flexion angles or recovery of active flexion angles. RESULTS: Pre-operative flexion angle was positively correlated with postoperative flexion angle (R = 0.52, P = 0.0002). Postoperative flexion angle was negatively correlated with the osteotomized bone thickness of femoral medial posterior condyle (R = -0.37, P = 0.012), and femoral lateral posterior condyle (R = -0.36, P = 0.015). Recovery of flexion angle was slightly negatively correlated with gap difference calculated by subtracting joint gap at extension from that at flexion between osteotomized surfaces (R = -0.30, P = 0.046). CONCLUSIONS: The osteotomized bone thickness of the femoral posterior condyle is a significant independent factor of postoperative flexion angles. This indicates that the restoration of the posterior condyle offset may lead to larger postoperative active flexion angles in PS TKA.

The influence of patellar position on soft tissue balance in minimal incision total knee arthroplasty.

PURPOSE: This study aims to clarify the influence of surgical exposure on intra-operative soft tissue balance measurements using a new tensor in minimal incision total knee arthroplasty (TKA). METHODS: Sixty patients with osteoarthritis of the knee received minimal incision TKAs. Twenty patients received a posterior-stabilized TKA using a quadriceps sparing approach, and the other forty patients, using a limited medial parapatellar (mini) approach. After femoral trial placement, soft tissue balance was measured using an offset type tensor at full extension and 90° of knee flexion, with the patella both laterally retracted and reduced. The joint component gap and varus imbalance were used to assess the difference in patellar position and surgical exposure. RESULTS: At extension, the joint component gap and varus imbalance showed no statistical difference regardless of patellar position in either TKA. However, the joint component gaps decreased at 90° of flexion when the patella was laterally retracted in both TKAs. Additionally, a significantly smaller joint gap was observed in the quadriceps sparing TKA than the mini-TKA with a retracted patella at 90° of flexion. Varus ligament imbalances decreased with the patella laterally retracted at 90° of flexion in the quadriceps sparing TKA, not in the mini-TKA. CONCLUSION: Surgeons should be aware of the influence in surgical exposure of the joint gap and ligament balance during patella shift in minimal incision TKA. LEVEL OF EVIDENCE: III.