Biomechanical analysis of load distribution in porcine hip joints at different acetabular coverages.

BACKGROUND: Developmental dysplasia of the hip causes secondary osteoarthritis. Finite element analysis suggests high hip joint contact pressure in patients with hip dysplasia and a reduction in contact pressure after periacetabular osteotomy. However, few biomechanical studies have examined the load distribution in the hip joint. This study aimed to investigate the biomechanical properties of load distribution in porcine hip joints at different acetabular coverages. METHODS: Six porcine hip joints were analyzed using three models: 1) neutral coverage, 2) 15° under-coverage (defined as dysplasia model), and 3) 15° over-coverage created by varying the acetabular coverage. The load distribution was assessed using a pressure-mapping sensor system after applying a loading force of 100 N to the hip joint. RESULTS: In the dysplasia model, the load was concentrated at the acetabular rim; in the neutral and over-coverage models, it was dispersed. The average contact pressure was significantly higher in the dysplasia model than in the neutral coverage model ([0.42 vs. 0.3 MPa]; p = 0.004). The contact area was significantly smaller in the dysplasia model than in the neutral coverage model ([250.7 vs. 345.0 mm2]; p = 0.004). No significant differences were observed in contact pressure or area between the neutral and over-coverage models. CONCLUSIONS: Insufficient acetabular coverage in the dysplasia model demonstrated higher contact pressure and smaller contact area than the neutral model. Conversely, the contact pressure and area in the over-coverage model did not differ significantly from those in the normal model. Therefore, surgeons should note that acetabular coverage overcorrection has limited effect; normalization is crucial during periacetabular osteotomy.

Equivalent Clinical Outcomes Between Anatomical Alignment Versus Mechanical Alignment of Simultaneous Bilateral Total Knee Arthroplasty Using a Posterior-Stabilized Prosthesis During an Average Follow-Up of Five Years: A Prospective Randomized Clinical Trial.

BACKGROUND: This study aimed to investigate the differences in clinical outcomes between anatomical alignment and mechanical alignment in each knee, respectively, in patients who underwent bilateral total knee arthroplasty. METHODS: Bilateral simultaneous total knee arthroplasty using a posterior-stabilized prosthesis was performed between June 2016 and May 2018, with one knee undergoing anatomical alignment and the contralateral knee undergoing mechanical alignment, which was randomized. There were 80 knees in 40 patients (mean age 75 years, range 60 to 87, with 4 men and 36 women) followed up for at least two years (mean follow-up 4.9 years, range 2 to 7y). On the anatomical side, the distal femoral cut was set 2° more valgus to the mechanical axis, and the tibial cut was set to 2 or 3° varus using a specific guide. Implant position and lower extremity alignment were measured using postoperative radiographs and computed tomography images. The range of motion before and after surgery, Knee Society score, patient satisfaction, postoperative 2011 Knee Society questionnaire, and Knee Injury and Osteoarthritis Outcome Scores were evaluated. RESULTS: A significant difference was observed in joint line orientation (0.6 versus 2.9°, P < 0.001), but not in the postoperative hip-knee-ankle angle between two groups. There was one knee in the mechanical alignment group that required revision surgery at five years due to implant loosening. Before surgery, the anatomical alignment group had a significantly lower knee extension angle (-7.2 versus -6.0º, P = 0.035) and Knee Society score (46.1 versus 49.1, P = 0.046). No significant difference was observed between the groups except for the 2011 Knee Society questionnaire satisfaction scores (26.7 versus 25.7, P = 0.035). More participants preferred the anatomical alignment side postoperatively. CONCLUSION: Anatomical and mechanical alignments had similar clinical outcomes in patients undergoing bilateral total knee arthroplasty at a mean of 4.9 year follow-up.

Comparison of changes in health-related quality of life between elderly and non-elderly patients undergoing elective surgery for colorectal cancer.

PURPOSE: Elderly people are thought to be more likely than their non-elderly counterparts to experience a decline in activities of daily living (ADL) and quality of life (QOL) due to the onset and treatment of disease. In this study, we investigated whether there was an age-related difference in changes in health-related QOL indices after surgical resection of colorectal cancer (CRC). METHODS: Patients who underwent elective surgery for primary CRC at our hospital between September 2017 and November 2021 were enrolled. Changes in QOL after surgery were evaluated after dividing the study population into a non-elderly (NE) group (younger than 75 years) and an elderly (E) group. A Short-Form 36-Item Health Survey was used as an index of QOL. The subscale and component summary scores before and 6 months after surgery were compared. RESULTS: Forty-seven patients were included in the E group and 166 patients were the NE group. The E group had significantly worse preoperative performance and physical status than the NE group. However, indices of physical function were not worsened after surgery in either group. In the NE group, there were significant decreases in role physical and role component summary scores and significant increases in general health, mental health, and mental component summary scores. In the E group, there were no significant changes in the subscale or component summary scores after surgery. CONCLUSION: Our study demonstrated elderly patient did not necessarily show a decline in QOL more than non-elderly patients after CRC surgery. Surgical resection for CRC should be considered even for elderly patients, while considering possible risk factors for worsening ADL and QOL.

Limited medial posterior capsular release increases the intraoperative medial component gap while maintaining the joint varus angle at extension in posterior-stabilized total knee arthroplasty.

PURPOSE: There is a lack of robust evidence for the magnitude of the effects of posterior capsular release (PCR) on intraoperative component gaps during total knee arthroplasty (TKA). The purpose of the present study was to quantify and compare the effects of partial versus full PCR on the intraoperative component gaps at various degrees of flexion during posterior-stabilized TKA. METHODS: Full PCR was performed on 39 consecutive cases (full PCR group), and partial PCR (the medial side up to and including the intercondylar notch) was performed on the subsequent 39 consecutive cases (partial PCR group) during posterior-stabilized TKA using the measured resection technique for varus knee osteoarthritis. Medial component gaps and varus angles at 0°, 10°, 45°, 90°, and a maximum of flexion were measured with a tensor device before and after the PCR. Differences between the two groups in post-release medial component gap increase and post-release joint varus angle increase were assessed using a t test. Pre- to post-release medial component gaps and joint varus angles in each group were compared using a paired samples t test. RESULTS: In both groups at 0° and 10° of flexion, post-release medial compartment gaps were significantly greater than pre-release gaps (all P < 0.001). At 45°, 90° and maximum flexion, the medial compartment gap increase did not exceed the minimal detectable change in either group. At 0° and 10° of flexion, there was no significant difference in post-release medial compartment gap change between the two groups. In the full PCR group, post-release joint varus angles at 0° of flexion were significantly greater than pre-release angles (P < 0.001), while there was no significant pre- and post-release difference in the partial PCR group. The change in post-release joint varus angles at 0° of flexion was significantly greater in the full PCR group than in the partial PCR group. CONCLUSION: Both full and partial PCR show similar clinical usefulness for increasing the medial component gap at extension and reducing component gap mismatch. A partial PCR can be used to avoid increasing joint varus angles at 0° of flexion. LEVEL OF EVIDENCE: Level 2 (prospective comparative study).

Effect of posteromedial vertical capsulotomy with medial collateral ligament liberation on intraoperative medial component gap mismatch between extension and mid-flexion during total knee arthroplasty.

PURPOSE: The aim of this study was to quantify the effect of posteromedial vertical capsulotomy on intraoperative component gaps and angles from extension through mid-flexion to flexion during total knee arthroplasty (TKA). METHODS: In the present study, 47 cases of primary posterior-stabilized TKA using the measured resection technique for varus knee osteoarthritis (hip-knee-ankle angles < 0°) were reviewed. Component gaps and angles at 0°, 10°, 45°, 90°, and maximum flexion were measured intraoperatively, before and after posteromedial vertical capsulotomy. Differences in pre- and post-posteromedial vertical capsulotomy medial and lateral component gaps and angles and medial component gap mismatches among knee flexion angles were assessed using the Wilcoxon signed rank test for two paired samples. RESULTS: The medial component gaps at 0° and 10° of flexion of post-posteromedial vertical capsulotomy were significantly greater, exceeding the minimal detectable change, than those pre posteromedial vertical capsulotomy (change of the gap after the procedure at 0° of flexion was 0.7 ± 0.7 mm and at 10° of flexion was 0.8 ± 0.8 mm; all P values < 0.05). The medial component gap mismatches between both 0° and 10°, and 45°, 90°, and maximum flexion were significantly smaller post posteromedial vertical capsulotomy than pre posteromedial vertical capsulotomy, with the values of the change exceeding the minimal detectable change (change of the gap mismatch after the procedure: knee flexion at 0° and 45° was - 0.6 ± 0.9 [mm], at 0° and 90° was 0.7 ± 1.0, at 0° and maximum flexion was - 0.6 ± 1.2, at 10° and 45° was - 0.7 ± 0.9, at 10° and 90° was - 0.8 ± 0.9, at 10° and maximum flexion was - 0.7 ± 1.1; all P values < 0.05). CONCLUSIONS: Posteromedial vertical capsulotomy increased the medial component gaps during knee extension but not during mid-flexion or full flexion during posterior-stabilized TKA. Posteromedial vertical capsulotomy improved mild medial component gap mismatch between extension and mid-flexion and full flexion during posterior-stabilized TKA. Surgeons can consider posteromedial vertical capsulotomy when there is intraoperative constriction of the medial component gap during extension in patients undergoing posterior-stabilized TKA.

Simultaneous bilateral total knee arthroplasty is safe and effective for patients in different ages.

BACKGROUND: Simultaneous bilateral total knee arthroplasty is considered beneficial for patients with bilateral end-stage knee osteoarthritis, even though there could be potential postoperative complications. Presently, there is a paucity of evidence of the efficacy and safety of SB-TKA for elderly patients. This study aimed to compare the clinical outcomes of simultaneous bilateral total knee arthroplasty by different age groups. METHODS: A total of 216 knees of 108 patients, who underwent simultaneous bilateral total knee arthroplasty for osteoarthritis at our hospital between April 2015 and September 2018, were divided into three groups based on age: 60s (44 knees), 70s (106 knees), and 80s (66 knees). Perioperative data and postoperative clinical outcomes 1 year after surgery were compared between the age groups. RESULTS: The patients in the Group 60s were characterized by a higher body mass index (BMI) (P < 0.01), a lower pre-operative knee function score (P < 0.01), longer operation time (P < 0.01), greater intra-operative (P < 0.01), and postoperative bleeding (P = 0.026). No significant difference was found in terms of occurrence of various postoperative complications, although deep vein thrombosis and delirium occurred slightly more frequently in the Group 70s and the Group 80s than in the Group 60s group. The Knee Society Knee Score, a function score, and patient satisfaction scores were significantly improved in all groups 1 year after surgery. Moreover, these indexes of clinical outcomes were similar among the three groups. CONCLUSION: Performing simultaneous bilateral total knee arthroplasty in 80s patients was found to be as safe and effective as in the 60s and 70s patients. LEVEL OF EVIDENCE: 3 (A retrospective cohort study).

Mid-term clinical outcomes of a posterior stabilized total knee prosthesis for Japanese patients: A minimum follow-up of 5 years.

BACKGROUND: A high-flexion posterior-stabilized total knee prosthesis has been developed for the Asian population. The component design was based on computed tomography images of Japanese osteoarthritic knees. The femoral component is composed of zirconia ceramics, which exhibit low friction and high durability. The present study aimed to evaluate the mid-term clinical outcomes of this implant. METHODS: This study included 334 knees of 210 patients who underwent primary total knee arthroplasty with this implant at our hospital between October 2010 and December 2014. The patients comprised 28 men and 172 women with an average age of 73 years. The average follow-up period was 5.9 years, and the follow-up rate was 71.1%. Clinical outcomes were assessed using the Knee Society scoring system, 2011 Knee Society questionnaire, and Knee Injury and Osteoarthritis Outcome Score. Kaplan-Meier survivorship analysis was performed to determine the cumulative prosthesis survival rate. RESULTS: In terms of clinical outcomes at the final follow-up, the average ranges of motion were -2.0 in extension and 126.7 in flexion. The Knee Society knee and function scores were 94.2% and 72.6%, respectively. With revision surgery or radiographic failure for any reason as the endpoint, the survival rates at 5 and 9 years were 98.2% and 95.5%, respectively. The most common reason for revision surgery or radiological failure was aseptic loosening. CONCLUSIONS: Despite several revision cases mainly due to aseptic loosening, the present study found that this new high-flexion posterior-stabilized total knee arthroplasty prosthesis design showed comparable results for Asian populations with other PS prosthesis. LEVELS OF EVIDENCE: Level Ⅱ (Prospective cohort study).

Effect of posterior capsular release on intraoperative joint gap mismatch in the mid-flexion range during posterior-stabilized total knee arthroplasty.

INTRODUCTION: Intraoperative mismatch between extension and mid-flexion joint gaps remains a critical issue in posterior-stabilized total knee arthroplasty (PS-TKA). Posterior capsular release has been found to increase the extension joint gap. However, there is still a lack of robust evidence for the effect of posterior capsular release on the mid-flexion joint gap. The purpose of the present study was to quantify the effect of posterior capsular release on the intraoperative joint gap from extension through 45° mid-flexion to flexion and to clarify how this procedure might affect the improvement of gap mismatch in the mid-flexion 45° range. MATERIALS AND METHODS: In total, 38 consecutive cases of primary PS-TKA were reviewed. The center, medial, and lateral component gaps from extension to flexion were measured with a tensor device before and after posterior capsular release. The minimal detectable change for joint gap measurement was calculated using two methods, error variance and intra-observer intraclass correlation coefficients. Pre- and post-release joint gap differences were assessed using the paired t-test. RESULTS: Minimal detectable change was found to be 0.59 mm. At 0° and 10° of flexion, the post-release center, medial, and lateral component gaps were significantly greater than at pre-release. At 45° and 90° and maximum flexion, there were no joint gap differences exceeding the minimal detectable change. The joint gap mismatches between 0° and 10°, and 45°, 90° and maximum flexion were significantly smaller at post-release than those at pre-release with the change values exceeding the minimal detectable change (P < 0.05). CONCLUSION: Posterior capsular release significantly decreased both joint gap mismatch between extension and 45° mid-flexion, and extension and flexion, showing clinical usefulness in PS-TKA.

[Cases of Advanced Colorectal Cancer with Nephrotic Syndrome after FOLFIRI plus Ramucirumab Administration].

We report 2: Cases of advanced colorectal cancer that developed nephrotic syndrome after ramucirumab(RAM)administration. Case 1: A 54-year-old woman with rectal cancer, liver and lung metastases, and peritoneal dissemination underwent sigmoid colon double-barrel colostomy for perforation management. The patient received 15 postoperative CAPOX plus bevacizumab(Bev)courses. FOLFIRI plus RAM was introduced as the second-line treatment. After 2 courses, the patient showed marked proteinuria and hypoalbuminemia and was diagnosed with nephrotic syndrome. The patient's condition improved promptly with administrating diuretics and antihypertensive drugs. Case 2: A 72-year-old man underwent sigmoid colon cancer resection with duodenal infiltration. Despite the treatment, a tumor was identified at the radial margin(RM1), with a positive cytological test(CY1)result. Therefore, postoperative mFOLFOX6 plus Bev was administered for 17 courses. FOLFIRI plus RAM was introduced as the second-line treatment due to residual tumor growth. After 2 courses, the patient showed accentuated proteinuria and was diagnosed with nephrotic syndrome and heart failure. The patient's condition improved after administrating diuretics, antihypertensive drugs, and V2-receptor antagonists. In both cases, marked proteinuria was observed after shifting to second-line treatment with two RAM administrations. Therefore, monitoring nephrotic syndrome development during the early RAM introduction stage is essential.

Trends in arthroplasty in Japan by a complete survey, 2014-2017.

BACKGROUND: Precise knowledge of the prevalence and trends of arthroplasty can facilitate the design of medical plans for efficient treatments. The National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) Open Data Japan provides statistics about the annual number of arthroplasties (knee, hip, shoulder, finger, elbow, and foot/ankle) through health insurance claim numbers for these surgeries. The purpose of this study was to document the annual arthroplasty numbers between 2014 and 2017 in Japan and to analyze their four-year trends, gender differences, age distributions, and regional differences as revealed by the complete survey. METHODS: Numbers of arthroplasty surgeries were extracted from the NDB Open Data Japan for 2014-2017. For "knee", "hip", "shoulder", "finger", "elbow", and "foot/ankle" arthroplasties, we showed the annual arthroplasty numbers, annual arthroplasty numbers by age group, annual arthroplasty numbers in individual prefectures, and annual arthroplasty numbers per 100,000 population in individual prefectures. RESULTS: The annual arthroplasty numbers in 2017 were 146,189 for all joints, 82,304 for knees, 59,029 for hips, 2454 for shoulders, 1551 for fingers, 536 for elbows, and 291 for feet/ankles. For the four years up to 2017, the rate of alteration in the number of arthroplasties was +14% for total arthroplasties, +9% for knees, +21% for hip joints, +97% for shoulders, + 8% for fingers, -10% for elbows, and +25% for feet/ankles. The proportion of females was 70-90% and the peak age was between the late 60s and late 70s for all joints. Variations in arthroplasty numbers per population by prefecture appeared to be small for knees and hips and large for other joints. CONCLUSIONS: We revealed the annual total number of arthroplasties for each joint in Japan using the NDB Open Data Japan for the first time.

Effect of transplanted mesenchymal stem cell number on the prevention of cartilage degeneration and pain reduction in a posttraumatic osteoarthritis rat model.

BACKGROUND: Mesenchymal stem cells (MSCs) transplantation therapy is considered an alternative therapy to prevent posttraumatic osteoarthritis (PTOA). However, consensus as to the sufficient number of MSCs for the prevention of PTOA is lacking. The purpose of this study was to determine the sufficient number of MSCs to achieve PTOA prevention and the reduction in pain after anterior cruciate ligament transection (ACLT). METHODS: Eight-week-old male Wistar rats were used. ACLT was conducted in the knee joint as a PTOA model. According to the species-specific knee joint volume, 104 MSCs in rats are equivalent to 3 × 107 MSCs in humans, which was clinically prepared. MSCs (104, 105, or 106 cells) or phosphate-buffered saline were injected into the knee joint at 1, 2, and 3 weeks after ACLT. Histological examinations were performed at 12 weeks after ACLT. The weight-bearing distribution improvement ratio was calculated as an assessment of pain until 12 weeks after ACLT. RESULTS: Histological evaluations showed that all the MSCs groups except for 104 MSCs group in femur were significantly improved compared to the control group at 12 weeks after ACLT. The weight-bearing distribution in the 104 and 105 MSCs groups at 12 weeks after ACLT and in the 106 MSCs group at 6, 8, 10, and 12 weeks after ACLT were significantly higher than those of the control group. CONCLUSION: A clinically feasible number of MSCs was found to reduce the articular cartilage degeneration and to decrease pain in the PTOA model. Increasing numbers of the cells further protected the articular cartilage against degeneration.

[Laparoscopy Assisted Subtotal Gastrectomy(Billrothâ Reconstruction)for Gastric Cancer in the Upper Stomach-A Report of Three Cases].

We experienced 3 cases of upper gastric cancer who underwent BillrothⅠ reconstruction in laparoscopy assisted subtotal gastrectomy. Two cases were female and 1 was male. The postoperative course was uneventful in all cases without heartburn, and the surgical margin was negative. The body weight loss rate was 5.8-12.6%, and the short-term results were relatively acceptable. Although the number of cases in this study was small, reconstruction with BillrothⅠ/delta-shaped anastomosis after laparoscopy assisted subtotal gastrectomy were considered to be useful.

Correction to: Coronal and sagittal laxity affects clinical outcomes in posterior-stabilized total knee arthroplasty: assessment of well-functioning knees.

Unfortunately, the co-author "Hiroki Katagiri' was omitted in the original publication from the author group. The author name is added here. The original article has been corrected.

Coronal and sagittal laxity affects clinical outcomes in posterior-stabilized total knee arthroplasty: assessment of well-functioning knees.

PURPOSE: Both coronal and sagittal laxity of well-functioning knees after total knee arthroplasty (TKA) was examined, and the correlations between the joint laxity and the clinical outcomes were analyzed to clarify the adequate joint laxity for the prosthesis, and the relationship between the laxity and the outcomes. METHODS: Forty well-functioning TKA knees with a high-flexion posterior-stabilized (PS) prosthesis were studied. All patients were diagnosed as having osteoarthritis with varus deformity and were followed up for 2 years or more. The coronal and sagittal laxity was assessed at extension and flexion, and the correlations between the joint laxity and the clinical outcomes were evaluated. RESULTS: The varus and valgus laxity averaged 5.6 ± 1.8° and 3.6 ± 1.2° at 10° knee flexion, and 7.4 ± 5.1° and 3.6 ± 2.7° at 80° knee flexion, respectively, and the AP laxity at 30° and 75° knee flexion averaged 8.7 ± 3.6 mm and 6.6 ± 2.3 mm, respectively. Knee flexion angle correlated with the joint laxity, while the other outcomes including patient-reported pain and instability were adversely affected by the greater laxity. CONCLUSIONS: This study exhibited the importance of consistent medial laxity both at extension and flexion, which averaged 3.6°. Care should be taken to maintain the medial stability and to obtain adequate laxity both at extension and flexion during surgery. A few degrees of medial tightness can be allowed to achieve excellent clinical results after TKA for preoperative varus knees. LEVEL OF EVIDENCE: Therapeutic study, Level III.

[A Case of a Huge Gastrointestinal Stromal Tumor with Extraluminal Growth Arising in the Small Intestine Diagnosed as an Ovarian Tumor].

We report a case of a gastrointenstinal stromal tumor(GIST)of the small intestine with extraluminal growth that was difficult to distinguish from an ovarian tumor. A 73-year-old woman presented to a nearby hospital for lower abdominal pain. A computed tomography(CT)scan showed a 17 cm ovarian tumor in the pelvis, and she was referred to the gynecology department of our hospital. Following examinations(enhanced CT and magnetic resonance imaging), she was referred to our department in suspicion of a small intestinal GIST in which the superior mesenteric artery/vein was the feeding blood vessel, and intraperitoneal tumor resection was performed. A large cystic tumor occupied the abdominal cavity and was in contact with the small intestinal wall. As the tumor was not in contact with the uterus or bilateral adnexa, only partial resection of the small intestine was performed. Histopathological examination showed c-kit positivity and she was diagnosed with small intestinal GIST; as a result, a course of imatinib was started.

Anterior Tibial Post Impingement During Stair Climbing: A Kinematic Analysis and Clinical Outcomes.

BACKGROUND: Anterior tibial post impingement during gait and stair ambulation was reported in knees with posterior-stabilized prostheses. However, the link between anterior post impingement and knee kinematics and between anterior post impingement and the clinical outcome has not been well investigated. Therefore, the purpose of this study was to assess the anterior impingement to clarify the relevant kinematics and clinical results including patient-reported outcomes. METHODS: We analyzed 40 well-functioning knees in 20 patients with a posterior-stabilized prosthesis due to osteoarthritis and who were followed up for 2 years or more. Dynamic lateral radiographs during stair-climbing activity were analyzed using a shape-matching technique, and anterior post impingement and the clinical outcome were assessed. RESULTS: Anterior impingement of the tibial post was observed in 13 knees (33%) during the latter half of the stance phase and at the beginning of the swing phase with the average implant flexion angle of -2.4°. Implant flexion was significantly smaller, while the femoral component was located more posterior in the impingement knees. The posterior tibial slope was significantly greater in the impingement group (6.7° ± 2.0°, 5.3° ± 1.9°, respectively; P = .041); however, no significant differences were demonstrated in anteroposterior laxity and patient-derived assessments. CONCLUSION: To avoid anterior post impingement, the posterior tibial slope should be made at 5° or less. Femoral notch-anterior post articulation should be designed to have good congruency in order to act as an anterior stabilizer in the case of impingement at knee extension.

Comparison of three approaches for femoral tunnel during double-bundle anterior cruciate ligament reconstruction: A case controlled study.

BACKGROUND: It is still controversial whether which femoral tunnel creation technique is best during anterior cruciate ligament reconstruction (ACLR). We aimed to clarify the features of three different techniques based on the femoral tunnel position created with the same tunnel-creating concept and the measurement data. METHODS: The femoral tunnel of double-bundle (DB) ACLR was created using the behind-remnant approach in a remnant preserved manner following the policy of our institute. The trans-tibial approach (TT) was applied for all primary ACL injured cases until December 2012. The trans-portal approach (TP) was applied from January to September 2013, and the outside-in approach (OI) was indicated from October 2013 to March 2014. We compared the femoral tunnel aperture positions with the postoperative three-dimensional computed tomography (3D-CT). Additionally, the femoral tunnel length and the septum distance of each anteromedial (AM) and posterolateral (PL) tunnel were analyzed. RESULTS: The AM tunnel aperture position of TT was significantly higher and shallower than that of TP in knee flexion position. The femoral tunnel length of TP was significantly shorter than that of TT and OI. The septum between each tunnel of OI trended wider than that of TT and TP. CONCLUSIONS: The AM tunnel aperture position of TT runs the risk of a high and shallow position. TP runs the risk of insufficiently short tunnel length. It is important to apply each method flexibly to each case because no single best approach was found.

Lateral meniscus posterior root tear contributes to anterolateral rotational instability and meniscus extrusion in anterior cruciate ligament-injured patients.

PURPOSE: The purposes of this study were to investigate (1) meniscus status and clinical findings in anterior cruciate ligament (ACL)-injured patients to clarify associations between the meniscus posterior root tear (PRT) and knee instability, and (2) magnetic resonance imaging (MRI) findings of the PRT to clarify sensitivity and specificity of MRI and prevalence of meniscus extrusion. METHODS: Three hundred and seventeen patients with primary ACL reconstruction were included. PRTs for both medial and lateral sides were confirmed by reviewing surgical records. Preoperative MRI was reviewed to evaluate sensitivity and specificity of the PRT and meniscus extrusion width (MEW). Clinical information regarding the number of giving-way episodes, preoperative KT-1000 measurements and preoperative pivot shift was also assessed. RESULTS: Thirty-nine patients had a lateral meniscus (LM) PRT, whereas only four patients had a medial meniscus PRT. One hundred and seventeen patients had no meniscus tear (control). Twenty-eight patients (71.8%) showed positive signs of the LMPRT based on at least one view of MR images, with the coronal view showing the highest sensitivity. MEW in the LMPRT group was significantly larger than that in the control group. The preoperative pivot shift test grade in the LMPRT group was significantly greater than that in the control group. There were no significant differences in other parameters. CONCLUSIONS: In ACL-injured patients, the LMPRT was associated with ALRI as well as with meniscus extrusion. The coronal view of MRI was useful in identifying the LMPRT, although its sensitivity was not high. Therefore, surgeons should prepare to repair PRTs at the time of ACL reconstruction regardless of MRI findings, and they should make every effort to repair the LMPRT. LEVEL OF EVIDENCE: III.

Risk factors for residual pivot shift after anterior cruciate ligament reconstruction: data from the MAKS group.

PURPOSE: To investigate the risk factors for residual pivot shift test after anterior cruciate ligament (ACL) reconstruction based on a multicenter prospective cohort study. METHODS: This study included patients who were registered in the Multicenter Arthroscopic Knee Surgery Study, a prospective longitudinal multicenter cohort study, and who underwent primary ACL reconstruction using autologous hamstring tendon graft between 2013 and 2016. The exclusion criteria included prior injuries or surgeries in the contralateral knee, prior ligamentous injuries in the involved knee, grade 2 or 3 concomitant ligament injuries, and inflammatory or other forms of osteoarthritis. Data from the preoperative period and at 1-year follow-up were used for further analysis, and patients with incomplete data, re-injury and loss to follow-up were also excluded. Logistic regression analysis was conducted with age, gender, Lachman test, pivot shift test, KT measurement, hyperextension, single-bundle vs. double-bundle, meniscus injury sites, and meniscus treatments as the independent variables, and postoperative pivot shift test was used as the dependent variable. RESULTS: Three hundred and sixty-eight patients were included in the study. Hyperextension knee (P = 0.025) and a preoperative pivot shift test under anesthesia (P = 0.040) were identified as risk factors for a postoperative pivot shift via logistic regression analysis. There were no statistically significant differences in the other variables. CONCLUSIONS: The results from a multicenter cohort study indicated that knee hyperextension and greater preoperative pivot shift under anesthesia were risk factors for residual pivot shift at 1 year after ACL reconstruction. In cases with a preoperative high-grade pivot shift and knee hyperextension, additional anterolateral structure augmentation might be considered in order to eliminate pivot shift and eventually obtain better outcomes after ACL reconstruction. LEVEL OF EVIDENCE: II.

Posteriorly inserted anterior cruciate ligament in knees with discoid lateral meniscus corresponding to bony morphological characteristics of femoral lateral condyle.

PURPOSE: Discoid meniscus often causes mechanical problems and needs surgical treatment at an early age. However, many aspects of its morphological development and changes remain unknown. The purpose of this study was to investigate the insertion of the femoral anterior cruciate ligament (ACL) via the behind-ACL approach and the morphology of the lateral femoral condyle to which the ACL attaches to clarify the morphological characteristics of the knee with discoid lateral meniscus (DLM). METHOD: Sixty-six patients with meniscus injury who underwent arthroscopic surgery were retrospectively reviewed. Preoperative plane radiographs were reviewed. To evaluate the shape of the femoral condyle, the ratio of the medial and lateral condyles, obliquity of the inter-epicondylar line, and the prominence ratio were assessed. From the arthroscopic observation using the behind-ACL approach, the insertion of the femoral ACL was classified as low, middle, and high based on the height from the deepest area of the articular surface to the direct insertion, including fibrous extension from the joint surface at 90° flexion. RESULTS: Twenty-nine patients had DLM (DLM group), and 37 patients had a semilunar meniscal injury (non-DLM group). The ratio of the lateral femoral condyle, obliquity of the inter-epicondylar line, and prominence ratio in the DLM group were significantly smaller than those in the non-DLM group. On the other hand, no significant difference in the ratio of the medial femoral condyle was observed. Arthroscopic evaluation revealed that the femoral ACL was significantly inserted lower in the DLM group than in the non-DLM group. CONCLUSION: The femoral ACL with DLM was inserted close to the femoral joint surface with morphological abnormality in the knees with DLM related to hypoplasic of the lateral femoral condyle.