Impact of support instruments in medial closed-wedge distal femoral osteotomy: a finite element analysis

INTRODUCTION

Medial closed-wedge distal femoral osteotomy (MCWDFO) is a valuable treatment approach for lateral knee osteoarthritis with femoral valgus deformity. Improved results have been reported with the upgrade of surgical techniques and locking plates. However, the risk of nonunion and loss of correction increases in cases of lateral hinge fractures. This study aimed to evaluate the mechanical impact of hinge fractures and support instruments in MCWDFO using finite element analysis (FEA).

MATERIALS AND METHODS

Five femur models were developed using Mechanical Finder 11.0 FEA software. We simulated the following models: only a medial locking plate (MLP) (group A); an MLP with a lateral support screw (group B); and an MLP with a lateral support plate (group C). The equivalent stress around the hinge was evaluated and the percentage of the plastic deformation zone was calculated for the hinge area in the no-hinge fracture model. The equivalent stress of the MLP and the degree of displacement were calculated using the hinge fracture model.

RESULTS

The percentages of the plastic deformation zone in groups A, B, and C were 18.0 ± 11.7%, 3.3 ± 2.4%, and 2.3 ± 2.8%, respectively. The percentages tended to be lower in groups B and C than in group A. In the hinge fracture model, the mean equivalent stress of the MLP in group C was significantly less than that in group A. In terms of the mean degree of displacement, group A showed more than 1 mm of displacement, which was significantly larger than that of the other groups.

CONCLUSION

The support instruments provided stability to the hinge site and reduced the equivalent stress of the main plate in the MCWDFO with hinge fractures. No significant difference was observed between the two instruments in terms of stability.

Estimation Failure Risk by 0.5-mm Differences in Autologous Hamstring Graft Diameter in Anterior Cruciate Ligament Reconstruction: A Meta-analysis

BACKGROUND

Because grafts are made in 0.5-mm increments clinically for anterior cruciate ligament (ACL) reconstruction, it is important to clarify how the failure rate decreases as the diameter increases. Moreover, it is important to know whether even a slight increase in the graft diameter decreases the risk of failure.

HYPOTHESIS

The risk of failure decreases significantly with each 0.5-mm increase in hamstring graft diameter.

STUDY DESIGN

Meta-analysis; Level of evidence, 4.

METHODS

The systematic review and meta-analysis have estimated the diameter-specific failure risk for each 0.5-mm increase in ACL reconstruction using autologous hamstring grafts. We searched for studies describing the relationship between graft diameter and failure rate published before December 1, 2021, in leading databases, such as PubMed, EMBASE, Cochrane Library, and Web of Science, according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We included studies using single-bundle autologous hamstring grafts to investigate the relationship between failure rate and graft diameter of 0.5-mm intervals with >1-year follow-up. Then, we calculated the failure risk caused by 0.5-mm differences in autologous hamstring graft diameter. Assuming Poisson distribution for the statistical model, we employed an extended linear mixed-effects model in the meta-analyses.

RESULTS

Five studies containing 19,333 cases were eligible. The meta-analysis revealed that the estimated value of the coefficient of diameter in the Poisson model was -0.2357 with a 95% CI of -0.2743 to -0.1971 (P < .0001). With every 1.0-mm increase in diameter, the failure rate decreased by 0.79 (0.76-0.82) times. In contrast, the failure rate increased by 1.27 (1.22-1.32) times for each 1.0-mm decrease in diameter. The failure rate significantly decreased with each 0.5-mm increase in graft diameter in the range of <7.0 to >9.0 mm from 3.63% to 1.79%.

CONCLUSION

The risk of failure decreased correspondingly with each 0.5-mm increase in graft diameter in the range of <7.0 to >9.0 mm. Failure is multifactorial; however, increasing the graft diameter as much as possible to match each patient's anatomic space without overstuffing is an effective precaution that surgeons can take to reduce failures.

Incidence and Distribution of Deep Vein Thrombosis Following Total Hip Arthroplasty Using an Anterolateral Supine Approach

Purpose

Venous thromboembolism (VTE) is a potential major complication in patients undergoing total hip arthroplasty (THA). However, the incidence of VTE following THA using anterolateral supine approach (ALS) has not been reported. The purpose of this study was to investigate the incidence of perioperative VTE and the distribution and characteristics of deep vein thrombosis (DVT) following ALS THA.

Patients and Methods

This retrospective single-arm study analyzed the 182 consecutive hips of 164 patients who underwent primary ALS THA. Pharmacological prophylaxis consisted of enoxaparin 20 mg twice daily for approximately 6 days starting 24 h postoperatively until duplex ultrasonography was performed to determine whether postoperative DVT was present. DVT was assessed by whole-leg Doppler ultrasound, and the location and characteristics of any thrombus were recorded. If pulmonary thromboembolism was suspected, contrast-enhanced computed tomography was performed.

Results

The overall incidence of VTE was 9.9% for DVT (18/182 hips) and 0.5% for pulmonary thromboembolism (1/182 hips). Most DVTs were in the soleal vein on the affected side and showed isoechoic or hypoechoic echogenicity. All thrombi were non-floating.

Conclusion

Following ALS THA with standard pharmacological prophylaxis and an early weight-bearing protocol, the incidence of perioperative DVT was approximately 10%, mostly occurring in the lower leg.

Lateral joint tightness in flexion following cementless mobile-bearing total knee arthroplasty decreases patient-reported outcome measures and postoperative range of motion

PURPOSE

The purpose of this study was to clarify the association between clinical outcomes and the flexion joint gap following rotating concave-convex (Vanguard ROCC) total knee arthroplasty (TKA).

METHODS

This consecutive retrospective series included 55 knees that underwent ROCC TKA. All the surgical procedures were performed using a spacer-based gap-balancing technique. To evaluate the medial and lateral flexion gaps, axial radiographs of the distal femur were obtained using the epicondylar view with a distraction force to the lower leg at 6 months postoperatively. Lateral joint tightness was defined as the lateral gap being greater than the medial gap. To evaluate clinical outcomes, patients were asked to complete patient-reported outcome measures (PROMs) questionnaires preoperatively and during at least 1 year of follow-up postoperatively.

RESULTS

The median follow-up duration was 24.0 months. Overall, 16.0% of patients had postoperative lateral joint tightness in flexion. The postoperative range of motion and PROMs were lower in patients with lateral joint tightness than in those with a balanced flexion gap or lateral joint laxity. No serious complications, including bearing dislocations, occurred during the observation period.

CONCLUSION

Lateral joint tightness in flexion following ROCC TKA decreases PROMs and postoperative range of motion.

LEVEL OF EVIDENCE: 4

Open-wedge high tibial osteotomy with a slight valgus correction from neutral limb alignment achieves clinical improvements comparable with those for knees with varus deformity

PURPOSE

The effect of open-wedge high tibial osteotomy (OWHTO) on the preoperative neutral alignment of the knee is unknown. The purpose of this study was to clarify the clinical outcome of OWHTO with neutral alignment, defined as within 4 degrees of varus.

METHODS

This retrospective study included 72 knees with varus that underwent medial OWHTO. The knees were divided according to the preoperative hip-knee-ankle angle into a neutral alignment group (≤ 4° of varus alignment) and a varus alignment group (> 4° of varus alignment). The Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Forgotten Joint Score-12 (FJS-12) were evaluated preoperatively and during at least 2 years of follow-up postoperatively.

RESULTS

There were no significant differences between the preoperative FJS-12 (17.9 versus 23.7; p = 0.16) and postoperative FJS-12 (57.3 versus 60.6; p = 0.52) or KOOS subscale scores (p > 0.05) in the neutral alignment group or the varus alignment group. Each group had a mean change in the KOOS subscale scores that exceeded the minimum clinically important difference.

CONCLUSION

The short-term clinical results of OWHTO for neutral alignment were as favourable as those for varus malalignment.

LEVEL OF EVIDENCE

IV.

Robotic-assisted total knee arthroplasty is not associated with increased risk of postoperative deep vein thrombosis

PURPOSE

Prolongation of operation time due to registration and pin insertion has been reported with robotic-assisted total knee arthroplasty (RATKA), and there has been concern about an increase in the postoperative incidence of deep vein thrombosis (DVT). In this study, we compared the incidence of DVT after RATKA with that after conventional manual TKA (mTKA).

METHODS

This consecutive retrospective series included 141 knees that underwent primary TKA using the Journey II system. The CORI robot was used. There were 60 RATKAs and 81 mTKAs. Doppler ultrasound was performed in all patients on postoperative day 7 to determine whether DVT was present.

RESULTS

The operation time was longer in the RATKA cohort (99.5 min vs 78.0 min, p < 0.001). The overall incidence of DTV was 43.9% (62/141 knees), all of which were asymptomatic. There was no significant difference in incidence of DVT between RATKA and mTKA (50.0% vs 39.5%, p = 0.23). Use of the robot did not affect the incidence of DVT following TKA (odds ratio 1.02, 95% confidence interval 0.40-2.60; p = 0.96).

CONCLUSION

The incidence of DVT was not significantly different between RA-TKA and mTKA. Multiple logistic regression indicated that RATKA is not associated with increased risk of postoperative DVT.

LEVEL OF EVIDENCE

IV.

A survey on the usage of decellularized tissues in orthopaedic clinical trials

Orthopaedic surgery requires grafts with sufficient mechanical strength. For this purpose, decellularized tissue is an available option that lacks the complications of autologous tissue. However, it is not widely used in orthopaedic surgeries. This study investigated clinical trials of the use of decellularized tissue grafts in orthopaedic surgery. Using the ClinicalTrials.gov (CTG) and the International Clinical Trials Registry Platform (ICTRP) databases, we comprehensively surveyed clinical trials of decellularized tissue use in orthopaedic surgeries registered before 1 September 2022. We evaluated the clinical results, tissue processing methods, and commercial availability of the identified products using academic literature databases and manufacturers' websites. We initially identified 4,402 clinical trials, 27 of which were eligible for inclusion and analysis, including nine shoulder surgery trials, eight knee surgery trials, two ankle surgery trials, two hand surgery trials, and six peripheral nerve graft trials. Nine of the trials were completed. We identified only one product that will be commercially available for use in knee surgery with significant mechanical load resistance. Peracetic acid and gamma irradiation were frequently used for sterilization. Despite the demand for decellularized tissue, few decellularized tissue products are currently commercially available, particularly for the knee joint. To be viable in orthopaedic surgery, decellularized tissue must exhibit biocompatibility and mechanical strength, and these requirements are challenging for the clinical application of decellularized tissue. However, the variety of available decellularized products has recently increased. Therefore, decellularized grafts may become a promising option in orthopaedic surgery.

AP3×ML3 reduction quality classification for femoral trochanteric fractures: validation for reliability focusing on positive medial cortical support

INTRODUCTION

This study evaluated the validity of the AP3 × ML3 reduction quality classification, which applies the concept of positive medial cortical support.

METHODS

A total of 120 trochanteric fractures classified as AO Foundation/Orthopedic Trauma Association 31A1 and A2 were retrospectively analyzed. The validity of the AP3 × ML3 classification was evaluated by comparison with the Baumgaertner reduction quality criteria. When using the AP3 × ML3 classification, reduction quality was divided into three classes based on the degree of anterior cortical contact between the proximal and distal fragments. Reduction quality was also divided into three classes when using the Baumgaertner criteria. The frequency of mechanical complications, including cut-out, delayed union, and excessive migration of the lag screw, was retrospectively assessed. Intra-observer and inter-observer reliability was assessed using the intraclass correlation coefficient (ICC).

RESULTS

Mechanical complications included 4 cases of cutout (3.3%) and 1 of delayed union (0.8%). Mechanical complications occurred for all levels of reduction quality in both classifications, except for the acceptable of the Baumgaertner criteria. When reduction quality was rated as good, acceptable, and poor the incidence of mechanical complications was 2.5%, 5.7%, and 16%, respectively, under the AP3 × ML3 classification and 3.3%, 0%, and 15.0%, respectively, under the Baumgaertner criteria. The ICC was 0.80 for intra-observer reliability and 0.57 for inter-observer reliability when using the AP3 × ML3 classification and 0.85 and 0.34, respectively, when using the Baumgaertner criteria.

CONCLUSION

The AP3 × ML3 classification was reliable and easy to use compared with the widely used Baumgaertner reduction quality criteria. Level of evidence 4.

High tibial osteotomy for medial meniscus posterior root tears in knees with moderate varus alignment can achieve favorable clinical outcomes

Purpose

Favorable clinical results have been reported following high tibial osteotomy (HTO) for medial meniscus posterior root tear (MMPRT) in knees with varus alignment. However, the effect on the preoperative neutral alignment of the knee is not known. This study sought to evaluate the clinical outcomes of medial open-wedge HTO for MMPRT with neutral alignment.

Methods

We retrospectively reviewed 119 medial open-wedge HTOs and analyzed 22 knees with MMPRT. The knees were divided according to the preoperative hip-knee-ankle angle into a moderate varus alignment group (≤4° of varus alignment) and a varus alignment group (> 4° of varus alignment). The Knee Injury and Osteoarthritis Outcome Score (KOOS) and Forgotten Joint Score-12 (FJS-12) values were evaluated preoperatively and at the latest follow-up. The healing status of MMPRT at the time of second-look arthroscopy, performed at a mean of 15.4 ± 4.2 months, was compared with that after the primary HTO.

Results

There were 11 knees in the moderate varus alignment group and 11 in the varus alignment group. In terms of perioperative patient-reported outcome measures, there was no significant difference in the preoperative or postoperative KOOS subscale score or FJS-12 score between the moderate varus and varus alignment groups. The healing rate was significantly higher in the moderate varus alignment group.

Conclusion

Favorable clinical results were obtained by medial open-wedge HTO in knees with MMPRT and moderate varus alignment in the short term. Surgeons should consider the indications for medial open-wedge HTO, even with moderate varus alignment, when planning treatment for MMPRT with persistent knee pain.

Level of evidence

IV

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00504-9.

Effect of bone morphology of the tibia plateau on joint line convergence angle in medial open wedge high tibial osteotomy

Background

Change in the joint line convergence angle (JLCA) of the knee after high tibial osteotomy (HTO) is difficult to predict accurately. Given that any change in JLCA is intra-articular, the shape of the articular surface, including the bone morphology of the proximal tibia, may affect the alignment of the knee joint postoperatively. The purpose of this study was to investigate the relationship between the shape of the tibial plateau and postoperative alignment of the knee joint by focusing on changes in JLCA.

Methods

One hundred and nine knees that underwent HTO were retrospectively reviewed. The shape of the tibial plateau was classified based on the slope of the medial and lateral articular surfaces as depressed, flat (within 3 degrees), or convex (pagoda-like). The relationship between the shape of the tibial plateau and radiological parameters was investigated.

Results

The shape of the tibial plateau was depressed in 38 knees, flat in 52 knees, and pagoda-like in 19 knees. There was a moderate correlation between the postoperative change in JLCA and the preoperative hip-knee-ankle angle for knees with a pagoda-shaped tibial plateau (r = 0.56) but not for the other two shapes.

Conclusions

These findings suggest that knees with marked varus deformity before HTO are likely to show more change in JLCA postoperatively if the tibial plateau is pagoda-shaped than if it has a depressed or flat shape. The advantage of focusing on the bone morphology of the proximal tibia is that surgeons can easily perform visual assessment using preoperative radiograph.

Perioperative varus alignment does not affect short-term patient-reported outcome measures following mobile-bearing unicompartmental knee arthroplasty

Background

Although favorable long-term survival of Oxford unicompartmental knee arthroplasty (UKA) has been reported regardless of postoperative varus alignment, the effect of degree of varus alignment on patient-reported outcome measures (PROMs) remains unclear. Furthermore, the Forgotten Joint Score-12 (FJS-12), which has a low ceiling effect, may be useful for such assessment. The objective of this study was to evaluate short-term clinical outcomes after Oxford UKA in knees with a greater degree of preoperative varus alignment focusing on use of the FJS-12.

Methods

This retrospective study involved 66 knees that had undergone primary Oxford UKA. Based on the hip-knee-ankle angle, the knees were divided into two alignment groups: severe varus group (≥ 185° varus alignment) and a mild varus group (< 185° varus alignment). PROMs, including the FJS-12, Knee Injury and Osteoarthritis Outcome Score, and Knee Society Score, were obtained pre- and postoperatively for assessment of clinical outcomes. In addition, the ceiling effect of the FJS-12 was evaluated.

Results

All PROMs showed significant improvement after surgery. However, there were no statistically significant differences between the severe varus group and the mild varus group. Moreover, no ceiling effect was found for the FJS-12 in this study.

Conclusion

Short-term results were good for Oxford UKA in knees with a greater degree of varus alignment and were not significantly different from those in knees with mild varus alignment.

Correlation of patient-reported numbness around surgical scars with patient-reported outcome measures and joint awareness after knee replacement: a cohort study

Background

Knee replacement is a very effective and indispensable treatment option for end-stage knee arthritis, and the number of cases has been increasing worldwide. A replaced knee joint without patient joint awareness is thought to be the ultimate goal of artificial knees. Joint awareness reportedly correlates with patient satisfaction. Although numbness around a replaced knee is a minor but common problem, its effect on postoperative outcome is controversial. Joint awareness also is sensitive to subtle abnormalities of the joint, so it must be negatively affected by numbness. Although numbness is minor, it cannot be ignored to further improve knee replacement outcomes. This study investigated the relationship between patient-reported numbness and other patient-reported outcome measures (PROMs), including joint awareness, and kneeling. We developed a numbness score based on a 5-point Likert scale on frequency of numbness, with an intraclass correlation coefficient of 0.76 and higher scores indicating less numbness.

Methods

The numbness score, New Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score-12 (FJS-12), and other clinical and radiological data from 311 patients (394 primary knee replacements) were analyzed. Kneeling ability was evaluated by using kneeling-specific items in the KSS (KSS-Kneeling).

Results

No numbness was found in 170 knees (43.1%), and some degree of numbness was found in the remaining 224 knees (56.9%). The numbness score showed weak-to-moderate correlations with KSS-Symptoms (r = 0.44), KSS-Satisfaction (r = 0.41), KSS-Activities (r = 0.29), and all KOOS subscales (r = 0.23–0.44), and FJS-12 (r = 0.42). Multiple regression analyses suggested that midline incision positively affected the numbness score over the anteromedial incision (p = 0.04) and that a better numbness score (p = 0.001), male sex (p < 0.0001), and better postoperative knee flexion angle (0.04) positively affected kneeling.

Conclusions

The numbness score positively correlated with PROMs and positively affected kneeling. Knee replacements performed via an anteromedial incision may be at higher risk for numbness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04971-6.

Anterior prominence of the femoral condyle varies among prosthesis designs and surgical techniques in total knee arthroplasty

BACKGROUND

Patellofemoral overstuffing after total knee arthroplasty (TKA) can cause limited range of motion and anterior knee pain. This study compared anterior prominence of femoral components among different prothesis designs in surgical simulation models utilizing the anterior reference (AR) and posterior reference (PR) techniques.

METHODS

Surgical simulations were performed using on a three-dimensional planning system preoperative computed tomography data of consecutive 30 patients with knee osteoarthritis scheduled to undergo TKA. Four implant models were used: Attune, Persona, Journey II, and Legion. Rotational alignment was set parallel to the transepicondylar axis and size was selected based on the absence of notch formation in the femoral anterior cortex and the best fit with the shape of the medial posterior femoral condyle. For each combination of surgical technique (AR or PR method) and implant model, measurements were taken of the maximum medial, central, and lateral prominence of the implant from the anterior femoral cortex.

RESULTS

Using either the AR or PR method, the medial and central prominences were significantly lower with Journey II than with the other models. The lateral prominence was the lowest with Attune in the AR method. The AR method was associated with significantly less prominence compared with the PR method, regardless of implant model.

CONCLUSIONS

The degree of anterior prominence of the femoral implant is affected by the implant design when the AR method is used. The PR method is associated with greater anterior prominence compared with the AR method, and the pitch size is an additional factor in the PR method. Surgeons should be familiar with implant designs, including the thickness of the anterior flange and the available size selections.

Good Validity and High Internal Consistency of the Forgotten Joint Score-12 in Patients After Medial Opening Wedge High Tibial Osteotomy

BACKGROUND

The Forgotten Joint Score-12 (FJS-12) was originally developed to assess awareness of an artificial joint. Medial opening wedge high tibial osteotomy (MOWHTO), an alternative surgical method of knee replacement, is a joint-preservation surgery; therefore, joint awareness should be used to evaluate its clinical results. However, FJS-12 has not been validated as a tool to evaluate the postoperative results of MOWHTO. This study aimed to validate FJS-12 in MOWHTO.

METHODS

Patients with bilateral knee surgery, previous knee surgery, flexion contracture >15°, varus alignment >20°, and patients without plate removal surgery were excluded. Finally, 71 knees of 71 patients were analyzed, with a mean follow-up of 34.5 months. The FJS-12 score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were obtained, and the floor and ceiling effect of each score was investigated. Cronbach's α was calculated to determine the internal consistency of FJS-12. Spearman's correlation coefficients between FJS-12 and KOOS were calculated to assess convergent validity.

RESULTS

There were ceiling effects in 3 KOOS subscales (symptoms [25.4%], pain [15.5%], and activities of daily living [25.4%]) but not in FJS-12 (8.5%). No floor effect was noted in any patient-reported outcome measures. The total Cronbach's α was 0.9457 in FJS-12. FJS-12 showed moderate-to-strong positive correlations with all KOOS subscales (r = 0.64-0.72).

CONCLUSION

FJS-12 showed a lower ceiling effect than KOOS and high internal consistency and convergent validity in patients following MOWHTO. With its low ceiling effect, FJS-12 was found to be useful for evaluating patients following MOWHTO.

Effect of osteoarthritis severity on survival and clinical outcomes after high tibial osteotomy

BACKGROUND

This study aimed to evaluate the effect of osteoarthritis severity on clinical outcomes using the 2011 Knee Society Score (KSS2011) and survival rates after closed wedge high tibial osteotomy (CWHTO).

METHODS

In this retrospective study, KSS2011 questionnaires were mailed to patients who had undergone CWHTO between January 1991 and December 2011. The completed questionnaires returned by the patients were analyzed. Preoperative osteoarthritis severity was evaluated by Kellgren-Lawrence (K-L) grade. KSS2011 was compared between the K-L grade groups. To determine the effect of K-L grade for revision surgery, Kaplan-Meier survival curves were created using the need for total knee arthroplasty (TKA) as the endpoint to estimate the probability of failure.

RESULTS

There were 16, 81, and 47 knees with preoperative K-L 2, 3, and 4, respectively. Among the KSS2011 sub-scores, the symptom score showed significant differences between the groups (p = 0.006). However, no significant difference was found regarding satisfaction, expectation, and functional activity scores. No significant difference in the symptom score was found between the K-L 2 and 3 groups (p > 0.05). Eighteen knees were treated with TKA at a mean of 9 years after CWHTO. Using the Kaplan-Meier survival estimates, the K-L 4 group showed a significantly higher rate of total knee arthroplasty conversion than the K-L 2 and 3 groups (p < 0.001).

CONCLUSIONS

Osteoarthritis severity affects clinical outcomes and survival rates during long-term follow-up after CWHTO. Surgeons should consider the preoperative osteoarthritis grade for long-term outcomes when considering CWHTO for patients with varus knees.

Monocortical fixation for locking plate distal screws does not impair mechanical properties in open-wedge high tibial osteotomy

Background

The neurovascular bundle containing the deep peroneal nerve has a potential risk of injury during open-wedge high tibial osteotomy (OWHTO), particularly due to drilling for bicortical fixation at distal screw holes. Therefore, monocortical fixation is recommended for distal fixation of a long locking plate as long as good stability is ensured. The purpose of this study was to analyse the biomechanical properties of monocortical fixation of distal locking screws for OWHTO.

Methods

Three-dimensional models of bone and fixation materials simulating OWHTO were created using computed tomographic data of patients and material data of a T-shaped long locking plate and screws. Three of the four distal screws of the locking plate were chosen for a bicortical fixation or monocortical fixation procedure. In addition, loss of correction was assessed by measuring the medial proximal tibial angle (MPTA) in patients who underwent OWHTO with two bicortical and two monocortical distal fixation screws at 1 month and 1 year after surgery.

Results

No significant differences in stress were observed in either the normal or osteoporotic bone model between the monocortical and bicortical fixation models, including in the area of the lateral hinge at the osteotomy site.

Furthermore, there were no significant differences in MPTA between the early post-operative period and 1-year follow-up.

Conclusions

The monocortical fixation method for three distal screws of the locking plate did not worsen the mechanical properties of fixation for OWHTO using a long locking plate with four proximal and four distal screws. In actual surgery, the number of distal bicortical screws should be reduced based on the patient’s condition, taking into account the risk of lateral hinge fracture and unexpected surgical complications. Using at least two bicortical screws would be practical considering the various factors related to reduced fixing ability.

Assessing the Validity of a New Prediction Model for Patient Satisfaction After Total Knee Arthroplasty: A Retrospective Cross-Sectional Study

Purpose

Previously, a simplified model using statistically selected questionnaires from various patients reported outcome measures (PROMs) was proposed to predict patient satisfaction after total knee arthroplasty (TKA). However, this simple and useful model needs to be validated across ethnic and cultural differences. The objective of this study was to evaluate the utility of this predictive model in Japanese patients.

Patients and Methods

Of all knees treated using primary TKA at our institution between August 2017 and June 2018, this study involved 50 knees of 48 patients (11 men, 37 women) to whom the predictive model was applied preoperatively and from whom PROMs were obtained at least 1 year postoperatively. To evaluate PROMs, patients completed the KSS and the Forgotten Joint Score-12. Correlations were analyzed between preoperatively predicted postoperative patient satisfaction and actual postoperative patient satisfaction, as well as each PROM.

Results

KSS satisfaction improved from 15.6 ± 6.1 preoperatively to 27.8 ± 8.3 postoperatively, with satisfaction reported for 41 knees (82%). The preoperatively predicted postoperative patient satisfaction score was 26.3 ± 4.6, with no significant correlation with actual postoperative score (r = 0.05, p = 0.72). The difference between preoperatively predicted patient satisfaction and actual postoperative patient satisfaction was positively correlated with the score for question 9 of the Pain Catastrophizing Scale, among other instruments constituting the predictive model.

Conclusion

Our data suggest that the predictive model had a low predictive value and that it had limited applicability to Japanese patients. The results also suggest that a tendency toward catastrophic thinking is associated with discrepancy between preoperatively predicted postoperative patient satisfaction and actual postoperative patient satisfaction. The predictive model has low utility and needs some modification.

Tibial condylar valgus osteotomy - indications and technique

PURPOSE

To describe the indications for, and surgical technique of, tibial condylar valgus osteotomy (TCVO).

INDICATIONS

TCVO is commonly performed in patients with middle-to-end-stage medial unicompartmental osteoarthritis. Among the most important TCVO indication criteria are the types of tibial plateau shape. The convex-type (also called "pagoda-type"), with over a 5° joint line convergence angle on the standing X-ray, meets the indication criteria for TCVO.

SURGICAL TECHNIQUE

An L-shaped osteotomy is performed from the medial side of the proximal tibia to the lateral beak of the intercondylar eminence. The apex of the L-shaped osteotomy line is on the medial border of the patellar tendon insertion. Surgeons should note the direction of the chisel (during the osteotomy) to the intercondylar eminence following fluoroscopic guidance. The posterior cortical bone is cut under a lateral view observation, and the crossed-leg position is adopted to prevent injury to the popliteal blood vessels. The spreader should be positioned at the posterior cortical bone to avoid increasing the tibial slope. The locking plate reliably stabilizes the osteotomy and helps shorten the period of postoperative rehabilitation.

CONCLUSIONS

TCVO adjusts varus deformity alongside joint congruity. Accurate identification of indications and a detailed surgical plan would ensure effective correction and proper alignment. Additional osteotomies are recommended in case of under-correction of the varus limb deformity. TCVO is an effective intervention in patients with advanced knee osteoarthritis and lateral joint laxity with the pagoda-type tibial plateau shape.

Deep peroneal nerve has a potential risk of injury during open-wedge high tibial osteotomy

PURPOSE

To assess the risk of injury to the neurovascular bundle on the interosseous membrane of the leg during drilling for distal screw insertion in open-wedge high tibial osteotomy (OWHTO), and to investigate the possible influence of the method of plate placement on the risk.

METHODS

This retrospective study involved, 55 patients (32 with a TomoFix plate, 23 with a TriS plate) who underwent postoperative CT scanning of the knee following OWHTO between 2009 and 2018. The angle and position of the locking plate, and the direction of screw insertion relative to the interosseous membrane were analysed.

RESULTS

All distal screws had a risk of neurovascular injury. In particular, 25 screws at the #4 hole (45%) had an extended insertion trajectory that intersected with the interosseous membrane. The angle of the proximal part of the TomoFix plate was a significant risk factor. In contrast, methods of TriS plate placement showed no statistically significant differences.

CONCLUSIONS

Extended insertion trajectories of distal screws were likely to intersect with the interosseous membrane with the neurovascular bundle potentially on its surface; thus, drilling for bicortical fixation posed a risk of neurovascular injury. The risk increased as the TomoFix plate was placed more medially, suggesting that bicortical drilling must be performed with the utmost attention when the plate is placed at the medial position. Given the particularly high risk at the #3 and #4 screw holes, monocortical fixation of a few distal screws is recommended as long as good stability is ensured.

Noise after total knee arthroplasty has limited effect on joint awareness and patient-reported clinical outcomes: retrospective study

Background

Some patients complain of noise after total knee arthroplasty (TKA). Controversy still exists on how the noise affects the clinical outcomes, including joint awareness, after TKA. The Forgotten Joint Score—12 (FJS-12) measures the clinical outcomes focusing on joint awareness after surgery. The Knee Society Scoring System—2011 (KSS-2011) includes questionnaires for satisfaction, expectation, and functional activities. The aim of this study is to clarify the relationship among FJS-12, KSS-2011, and the noise. Furthermore, the relationship between FJS-12 and KSS-2011 was validated.

Methods

Using FJS-12 and KSS-2011, 295 knees from 225 patients who underwent TKA were retrospectively evaluated. Noise perception was evaluated by a questionnaire with five grades, a method that follows the questionnaire form of FJS-12 (“Are you aware of the noise of your artificial joint?”; never, almost never, seldom, sometimes, mostly). Correlations among FJS-12, KSS-2011, and noise were analyzed. The patients were divided into four groups based on the mechanism of their implant [cruciate retaining, posterior stabilized, cruciate sacrificed, and bicruciate stabilized (BCS)]. FJS-12, KSS-2011, and noise were compared among the groups.

Results

A strong correlation was found between FJS-12 and total score of KSS-2011 (0.70; P < 0.001). FJS-12 correlated with KSS-2011 subcategories of “symptoms,” “satisfaction,” and “standard activities,” with correlation coefficients at approximately 0.60. Noise had weak correlations with FJS-12 (0.28; P < 0.001) and KSS-2011 (0.20 P < 0.001). In comparing the TKA mechanisms, BCS had remarkably better KSS-2011 and greater movement range but worse noise scores.

Conclusions

Noise perception after TKA had limited effect on joint awareness and clinical outcomes. FJS-12 correlated strongly with KSS-2011 and associated with satisfaction, residual symptoms, and daily activities, as assessed by KSS-2011 subscores.

Trial registration

This study was approved by the Medical Ethical Committee of the Tokyo Women’s Medical University (approval number: 4681 on March 2, 2018).

Deep peroneal nerve injury during plate fixation for medial open-wedge high tibial osteotomy: A case report and cadaveric study

This report presents a case of deep peroneal nerve palsy caused by an injury during drilling for distal locking screws of a T-shaped locking plate used for osteosynthesis of medial open-wedge high tibial osteotomy. A cadaveric simulation study reproduced the risk of injury during the surgery.

Treatment of Capitellum Fracture with Chronic Radial Head Dislocation

We encountered a case of capitellum fracture with radial head dislocation in which it was challenging to diagnose whether the dislocation was coincident with the fracture or this was chronic dislocation that presented before the fracture. Chronic radial head dislocation may be congenital or could occur in patients with untreated post-traumatic dislocation, although diagnosis is particularly challenging if the radial head dislocation is unilateral. Classical capitellum fracture involves anterosuperior bone fragment dislocation. However, in the present case, the bone fragment was present beneath the radial head, which suggests chronic radial head dislocation. When the bone fragment appears in a different position than usual, every effort should be made to understand the pathophysiology by reviewing the mechanism of onset, disease history, and imaging.

Abstract P5-03-08: Eribulin-induced EpCAM expression provides drug resistance in triple-negative breast cancer cells

Breast cancer is the most common cancer in women in the world. Among breast cancer subtypes, triple-negative breast cancer is aggressive. Because there is no effective therapy for triple-negative breast cancer, development of a novel therapeutic strategy is required.

Eribulin, a derivative of halicondrin B, is an anticancer chemical. Eribulin treatment has been approved in many countries for patients with metastatic or inoperable breast cancer, including triple-negative breast cancer. The known functions of Eribulin are inhibition of microtubule polymerization and induction of the expression of epithelial genes in breast cancer cells. However, the function of Eribulin-induced genes on the therapy for patients with triple-negative breast cancer remains unclear.

EpCAM (Epithelial cell adhesion molecule) is one of epithelial markers and known as a cell-cell adhesion molecule. In addition, EpCAM expression is involved in drug resistance in cancer. We therefore focused on EpCAM expression in Eribulin-treated breast cancer cells.

We used MDA-MB-231 cells that is a commonly used triple-negative breast cancer cell line. We treated cells with 10 nM Eribulin and observed inhibition of cell growth. In the same condition, we found up-regulation of EpCAM expression in both mRNA and protein levels. In mouse xenograft model with MDA-MB-231 cells, EpCAM expression was detected in whole tumor at 96 h after Eribulin administration. We analyzed the effect of other microtubule polymerization inhibitors, nocodazole and colchicine, on EpCAM induction. In the results, there was no up-regulation of EpCAM expression in cells treated with these chemicals, suggesting that EpCAM expression is not induced by inhibition of microtubule polymerization and growth inhibition.

To analyze EpCAM function on Eribulin treatment, we constructed shRNA-mediated EpCAM knockdown system. We introduced EpCAM knockdown in MDA-MB-231 cells and treated with Eribulin. In the results of cell growth assays, the cell number of Eribulin-treated EpCAM-knockdown cells was significantly smaller than that of Eribulin-treated control-shRNA cells, whereas no change was observed between solvent-treated control-shRNA and EpCAM-knockdown groups. In mouse xenograft experiments, EpCAM-knockdown cells showed smaller tumor weights than control-shRNA cells after administration of Eribulin. These results indicate that EpCAM expression provides Eribulin resistance in breast cancer cells.

In conclusion, we found Eribulin-induced EpCAM expression in triple-negative breast cancer cells. The EpCAM expression provides Eribulin resistance both in vitro and in vivo. These suggest that a combination of Eribulin treatment and EpCAM inhibition may improve therapy for breast cancer.

Citation Format: Tanaka S, Itou J, Sato F, Toi M. Eribulin-induced EpCAM expression provides drug resistance in triple-negative breast cancer cells [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-03-08.

Abstract P2-01-11: A peptide with the conserved amino acid residue of integrin α6 inhibits metastasis through disruption of complex formation in breast cancer cells

Metastasis inhibition may improve survival of breast cancer patients. Our previous study revealed that a transcription factor SALL4 promotes cell migration for metastasis through up-regulation of integrin α6β1 in metastatic basal-like breast cancer cells. In these cells, integrin α6β1 modulates Rho GTPase activity, which enhances focal adhesion dynamics for cell migration. We therefore focused on integrin α6 as a therapeutic target for metastasis.

We investigated the expression level of integrin α6 in breast cancer cell lines and a tissue microarray of breast cancer patients. In both experiments, we observed higher integrin α6 expression in basal-like breast cancer cells than in luminal ones. We performed shRNA-mediated integrin α6 knockdown in basal-like breast cancer cells and conducted Boyden chamber assays. In the results, reduced cell migration was observed in integrin α6 knocked-down cells. Reciprocally, we introduced integrin α6 overexpression in low-migratory luminal breast cancer cell lines and observed increased cell migration. These results indicate that integrin α6 promotes cell migration in breast cancer cells.

To identify the functional residue of integrin α6, we analyzed its amino acid sequence by in silico analyses. First, we extracted integrin α6 specific residues in integrin α family in the human genome. Then, we compared integrin α6 sequences among vertebrates. In the result, we obtained an integrin α6-specific and vertebrate-conserved sequence, Asp-358, as a candidate for the functional residue.

To inhibit integrin α6 function, we designed an 8-amino acid peptide with the sequence around Asp-358. Basal-like breast cancer cells treated with the peptide showed reduced cell migration in a dose-dependent manner. The peptide did not reduce cell migration in integrin α6 knocked-down cells, suggesting that the peptide inhibits integrin α6 function. To determine whether the peptide inhibits metastasis, we performed zebrafish metastasis assays, and observed reduced metastasis rate in the peptide-treated group. These results indicate that the peptide inhibits metastasis through reduction in cell migration.

To understand the effect of the peptide, we performed chemical cross-liking assay in a basal-like breast cancer cell line. Protein samples from the cells treated with a cross-linker showed bands of integrin α6 complexes, and the intensities of these bands were reduced in the peptide-treated group. Moreover, we immunostained cells with an antibody for focal adhesion marker, phospho-paxillin, because integrins regulates focal adhesion formation for cell migration. In the results, the peptide reduced the number of focal adhesions. These observations indicate that the peptide inhibits integrin α6 function. In the future, our findings may contribute to development of a metastasis inhibition therapy.

Citation Format: Itou J, Tanaka S, Senda N, Iida A, Sehara-Fujisawa A, Sato F, Toi M. A peptide with the conserved amino acid residue of integrin α6 inhibits metastasis through disruption of complex formation in breast cancer cells [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-01-11.

[A successful surgical repair for all right pulmonary venous return and intact atrial septum associated with patent left superior vena cava]

A successful repair of total right pulmonary venous return and intact atrial septum associated with patent left superior vena cava (PLSVC) is reported. A 31-year-old women was admitted for evaluation of heart failure. A heart murmur had been detected since her childhood without any subjective symptoms. She was diagnosed as partial anomalous venous return of all right pulmonary vein and intact atrial septum (IAS) associated with PLSVC by cardiac catheterization. Operative findings revealed that all right pulmonary vein connected to right atrium (RA) and superior vena cava (SVC), PLSVC drained into coronary sinous (CS), therefore RA, right ventricle and CS were enlarged, but SVC was small due to PLSVC. Through large incision from RA to SVC, atrial septum was opened 30 mm in diameter. Internal conduit using pericardial patch was made in order to drain anomalous pulmonary venous blood into left atrium through the ASD. Finally, SVC and RA were reconstructed by pericardial patch for prevention of conduit obstruction. One month after operation, no stenosis of SVC and right pulmonary vein was evidenced by cardiac catheterization and all through the postoperative course, arrhythmias did not detected. She was discharged with uneventful postoperative course.