Bone morphology and physical characteristics of the pro-cyclist hip joint.

PURPOSE: This study aimed to investigate the radiographic findings for the hip joint and hip range of motion in professional cyclists, and to determine their bone morphology and physical characteristics. The effects of physical characteristics on athletic performance were examined in terms of metabolic efficiency using simulation analysis. METHODS: We performed a case-control research study on 22 hips in 11 male professional cyclists (average age 28.5, height 1.73 m, weight 77.6 kg). Thirty hips in 15 healthy male volunteers were selected as controls. As radiographic evaluations, acetabular dysplasia was assessed on standardized radiographs. During physical evaluations, the hip range of motion was examined. We used simulation analysis to investigate the metabolic efficiency in the different cycling forms. RESULTS: The radiographic evaluations showed a significant difference in the incidence of acetabular dysplasia (p = 0.01): 59% (13/22 hips) in the pro-cyclist group versus 10% (3/30 hips) in the control group. The physical evaluations revealed significant differences in the hip internal rotation angle (p = 0.01), with greater ranges of internal rotation in the pro-cyclist group versus the control group. The simulation analyses showed that metabolism was reduced in the cycling form with hip internal rotation, especially in the lower extremities. CONCLUSIONS: Pro-cyclists showed a high frequency of acetabular dysplasia and superior hip internal rotation. According to the cycling model analyses, hip internal rotation allowed pedaling with reduced metabolic power.

Pathophysiology of abnormal compensation ability of the subtalar joint in the varus knee.

BACKGROUND: In recent years, the involvement of the compensation ability of the subtalar joint in lower extremity alignment has been reported. We previously showed that hindfoot alignment angle (HAA) is an indicator of compensation ability of the subtalar joint. The abnormal compensation ability of the subtalar joint was defined by the mobility of the subtalar joint, and evaluation of the mobility of the subtalar joint may help to further clarify the pathophysiology of abnormal compensation ability of the subtalar joint. This study was performed to evaluate the mobility of the subtalar joint and clarify the pathophysiology of abnormal compensation ability of the subtalar joint in the varus knee. METHODS: Seventy-two knees of 72 patients aged ≥40 years with varus knee were included in this study. Preoperative radiographs were used for measurement of this study parameters. Based on our previous study, we defined HAA of ≥15.9°as abnormal compensation ability of the subtalar joint. The patients were divided into an abnormal group (A-group) and normal group (N-group). All measurement parameters were compared between the groups, and correlations between the HAA and each measurement parameter were analyzed. RESULTS: The weight-bearing hindfoot angle (WBHA) (p < 0.001) and non-weight-bearing hindfoot angle (non-WBHA) (p = 0.003), were significantly greater in the A-group than in the N-group. Conversely, the ratio of change in hindfoot alignment (p = 0.006), were significantly smaller in the A-group than in the N-group. The HAA was positively correlated with WBHA (r = 0.66) and non-WBHA (r = 0.43) and negatively correlated with the ratio of change in hindfoot alignment (r = -0.32). CONCLUSIONS: The pathophysiology of abnormal compensation ability of the subtalar joint in the varus knee is thought to involve a state of increased valgus of hindfoot alignment and an inability to move into normal hindfoot alignment. LEVEL OF EVIDENCE: Level Ⅲ, retrospective study.

Influence of hindfoot alignment on postoperative lower limb alignment in medial opening wedge high tibial osteotomy.

INTRODUCTION: We have experienced unexpected under-correction after medial opening wedge high tibial osteotomy (MOWHTO). Although the tibia was corrected accurately, the postoperative mechanical axis (MA) was less than 57%. The purpose of this study was to evaluate the relationship between hindfoot alignment and postoperative lower limb alignment, and to reveal whether hindfoot alignment affects lower limb alignment after MOWHTO. Our hypothesis was that hindfoot alignment influences the postoperative MA in MOWHTO. MATERIALS AND METHODS: This study was a retrospective comparative study. The study cohort comprised 43 knees in 43 patients who underwent MOWHTO and had standing long-leg anteroposterior view and hindfoot alignment view radiographs taken preoperatively and at 3 months postoperatively. To evaluate the hindfoot alignment, the absolute value of the ankle joint line orientation relative to the ground was added to the absolute value of the hindfoot angle. We defined a postoperative MA of 57-67% as acceptable correction (A group) and a MA of < 56% as under-correction (U group). The two groups were analyzed to identify factors that affected postoperative limb alignment. RESULTS: The preoperative hindfoot alignment angle was significantly larger in the U group than the A group. The preoperative hindfoot alignment angle was a significant predictive factor of the postoperative MA, and the cut-off value that distinguished under-correction from acceptable correction was 15.9 degrees. CONCLUSION: Abnormal hindfoot alignment is one of the causes of under-correction after MOWHTO. Attention should be paid to the preoperative ankle joint line orientation relative to the ground and hindfoot angle. If the preoperative hindfoot alignment angle is ≥ 15.9 degrees, surgeons should reconsider the operative procedure and correction angle. LEVEL OF EVIDENCE: Therapeutic level III, retrospective study.

Soft tissue stabilization of the hinge position in medial closed wedge distal femoral osteotomy: an anatomical study.

BACKGROUND: Soft tissue has an important role in stabilizing the hinge point of medial closed wedge distal femoral osteotomy (MCWDFO). However, there are conflicting data on the soft tissue anatomy around the hinge point of MCWDFO and, therefore, further anatomical data are needed. The purposes of the study were to: 1) anatomically analyze the soft tissue around the hinge point of MCWDFO; 2) radiologically define the appropriate hinge point to prevent an unstable hinge fracture based on the result of the anatomical analysis; and 3) histologically analyze the soft tissue based on the result of the anatomical analysis. METHODS: In 20 cadaveric knees, the capsule attachment of the distal lateral side of the femur was marked with a radiopaque ball bearing. A digital planning tool was used to calculate the area of the marked capsule attachment around the ideal hinge point of MCWDFO on radiographs. The soft tissue around the hinge point was histologically examined and the periosteal thickness was measured and visualized graphically. The graph and radiograph were overlayed using image editing software, and the appropriate hinge position was determined based on the periosteal thickness. RESULTS: As a result, the periosteal thickness of the distal lateral femur tended to rapidly decrease from the metaphyseal region toward the diaphyseal region. The overlayed graph and radiograph revealed that the periosteal thickness changed in the region corresponding to the apex of the turning point of the femoral metaphysis in all cases. CONCLUSIONS: In conclusion, the periosteum might support the hinge of MCWDFO within the area surrounded by the apex of the turning point of the femoral metaphysis and the upper border of the posterior part of the lateral femoral condyle.

Femoral morphology affects postoperative alignment of the lower extremities in hybrid closed-wedge high tibial osteotomy.

INTRODUCTION: This study aimed to determine correction error predictors of lower extremitiy alignment after hybrid closed-wedge high tibial osteotomy (HCWHTO). MATERIALS AND METHODS: From 2011 to 2015, 102 knees in 75 patients with medial compartment knee osteoarthritis of the knee and varus knee deformities who underwent HCWHTO were evaluated in this retrospective study with a minimum 2-year follow-up. Preoperative radiological parameters including weight-bearing line ratio (WBL ratio), mechanical leg axis angle, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and JLCA under varus or valgus stress were measured. The knees were divided into the following three groups based on the WBL ratio on average 54 months after procedure: acceptable (WBL crossing the tibial plateau between 50 and 70%), under-correction (< 50%), and overcorrection (> 70%). A multiple regression analysis was performed to evaluate predictors that could influence postoperative WBL ratio and cut-off values of predictive preoperative factors was analysed. RESULTS: Significant differences in pre- and postoperative WBL ratios and mechanical leg axis angles were found. Preoperative mLDFA in the under-correction group (89.4° ± 2.1°) was significantly higher than that in the overcorrection group (87.4° ± 2.2°) (p = 0.015), while other preoperative parameters revealed no significant differences. The postoperative MPTA in the under-correction group (92.1° ± 3.7°) was significantly lower than that in the other two groups (p = 0.005 and p = 0.0001, respectively), while there was no significant change between the acceptable (94.6° ± 3.4°) and the overcorrection (96.7° ± 3.2°) groups. Multiple regression analysis revealed that mLDFA (ß = - 0.316; p = 0.010) had a significant impact on postoperative WBLR. The cut-off value for under-correction of mLDFA was 89.5°and sensitivity and specificity were 53.6 and 71.6%, respectively (p = 0.014). CONCLUSIONS: Preoperative mLDFA is significantly associated with postoperative alignment in HCWHTO. While postoperative MPTA is important, disregarding the preoperative mLDFA may bears a high risk of malcorrection. Varus alignment of the knee with larger mLDFA may be an indication for not only HCWHTO, but also for distal femoral osteotomy.

Suppression of joint destruction with subcutaneous tocilizumab for Japanese patients with rheumatoid arthritis in clinical practice.

Objectives: To investigate the efficacy of suppressing joint destruction with subcutaneous tocilizumab (TCZ-SC) for Japanese rheumatoid arthritis (RA) patients in the real-world clinical setting.Methods: This 1-year prospective, multicenter study included 110 RA patients in whom TCZ-SC was newly initiated. Primary endpoint was the change from baseline in vdH-modified total Sharp score (mTSS) at week 52. Structural remission was defined as yearly mTSS of 0.5 or less. Disease activity was evaluated using the disease activity score (DAS28-ESR) and clinical disease activity index (CDAI).Results: At baseline, the patients' mean age was 58.6 years, and the mean disease duration was 10.6 years. The proportion of patients who were naïve for biologics was 44.5%, and 64.5% concomitantly received methotrexate. The yearly mTSS showed significant improvement from 9.41 before TCZ-SC initiation to -0.15 after 52 weeks. The structural remission rate was 76.1%. After 52 weeks, the DAS28-ESR and CDAI remission rates were 52% and 21%, respectively. Although the previous usage of biologics and baseline disease activity significantly affected the clinical remission, no factors with significant effects on structural remission were identified.Conclusion: These findings support the efficacy of TCZ-SC in suppressing disease activity as well as joint destruction over a 1-year period.

Hybrid closed wedge high tibial osteotomy improves patellofemoral joint congruity compared with open wedge high tibial osteotomy.

PURPOSE: To evaluate clinical outcomes and radiographic changes in patellofemoral (PF) joint congruity between open wedge high tibial osteotomy (OWHTO) and hybrid closed wedge HTO (HCWHTO). METHODS: From 2011 to 2013, 36 knees in 31 patients who underwent OWHTO and 21 knees in 17 patients who underwent HCWHTO were evaluated in this retrospective study with a minimum 5-year follow-up. Radiological outcomes including hip-knee-ankle angle (HKA), femoral patellar height index (FPHI), preoperative PF osteoarthritis (OA) grade, medial and lateral joint spaces of the PF joint, and congruence angle were measured. Clinical parameters including the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Oxford Knee Score (OKS) were also evaluated. Preoperative and final follow-up values for each procedure were compared in outcome analyses. RESULTS: Mean preoperative HKA and the degree of PF-OA were significantly more severe for patients treated with HCWHTO compared with those treated with OWHTO (p = 0.001, p = 0.0001). Mean postoperative FPHI was significantly decreased with proximalization of the patella in HCWHTO (p = 0.01) but showed no significant change in OWHTO (n.s.). Regarding PF joint congruity after HCWHTO, lateral joint space and congruence angle were significantly improved (p = 0.0001, p = 0.005), while medial joint space was not significantly changed (n.s.). After OWHTO, congruence angle showed no significant difference (n.s.), but medial and lateral joint spaces were significantly decreased (p = 0.0001, p = 0.018). There were no significant differences in KOOS and OKS between the groups (n.s., n.s.). CONCLUSIONS: Although degrees of varus knee and PF-OA were more severe in HCWHTO than those in OWHTO, HCWHTO led to improved PF joint congruity, and its mid-term clinical outcomes were equivalent to those of OWHTO. Therefore, in patients with varus knee combined with PF-OA preoperatively, HCWHTO is a more effective treatment than OWHTO. LEVEL OF EVIDENCE: Therapeutic level III.

Coronal tibial anteromedial tunnel location has minimal effect on knee biomechanics.

PURPOSE: Studies have found anatomic variation in the coronal position of the insertion site of anteromedial (AM) bundle of the anterior cruciate ligament (ACL) on the tibia, which can lead to questions about tunnel placement during ACL reconstruction. The purpose of this study was to determine how mediolateral placement of the tibial AM graft tunnel in double-bundle ACL reconstructions affects knee biomechanics. METHODS: Two different types of double-bundle ACL reconstructions were performed. The AM tibial tunnel was placed at either the medial or lateral portion of tibial AM footprint. Nine cadaveric knees were tested with the robotic/universal force-moment sensor system with the use of (1) an 89.0-N anterior tibial load at full extension (FE), 30°, 60° and 90° of knee flexion and (2) a combined 7.0-Nm valgus torque and 5.0-Nm internal tibial rotation torque at FE, 15°, 30°and 45° of knee flexion. RESULTS: Both medial (2.6 ± 1.2 mm) and lateral (1.6 ± 0.9 mm) double-bundle reconstructions reduced the anterior tibial translation (ATT) to less than the intact value (3.9 ± 0.7 mm) at FE. At all other flexion angles, there was no significant different in ATT between the intact knee and the reconstructions. At FE, the ATT for the medial AM reconstruction was different from that of the lateral AM construction and closer to the intact ACL value. CONCLUSION: The coronal tibial placement of the AM tunnel had only a slight effect on knee biomechanics. In patients with differing AM bundle coronal positions, the AM tibial tunnel can be placed anatomically at the native insertion site.

Impact of methotrexate dose on efficacy of adalimumab in Japanese patients with rheumatoid arthritis: Results from registered data analyses.

OBJECTIVE: Upper limit of methotrexate (MTX) for patients with rheumatoid arthritis (RA) was recently increased from 8 to 16 mg/week in Japan. We therefore examined the effect of concomitant MTX dose on the efficacy of adalimumab (ADA) in clinical practice. METHOD: Sixty-one consecutive RA patients treated with ADA were followed for minimum 52 weeks and retrospectively compared by MTX dose; patients receiving concomitant MTX of 10 mg/week or more (MTX ≥10 mg group) and <10 mg/week (MTX <10 mg group). Disease activity and remission were evaluated by the disease activity score 28 (DAS28) criteria. RESULTS: The MTX ≥10 mg group consistently showed better improvement in DAS28 and resulted in more patients (52.8%) with DAS28-remission compared with the MTX <10 mg group (26.1%). Multivariate analysis showed that MTX ≥10 mg had a significant effect on DAS28 remission with odds ratio of 5.12. ADA retention rate was 72.2% in MTX ≥10 mg group compared with 52.0% in MTX <10 mg group. Discontinuation of ADA due to adverse events were comparable in the MTX ≥10 mg and MTX <10 mg groups (11.1% vs. 12.0%). CONCLUSIONS: These findings support the critical role of concomitant MTX in the efficacy of ADA, and recommend use of MTX ≥10 mg in Japanese RA patients.

The Influence of Knee Flexion Angle for Graft Fixation on Rotational Knee Stability During Anterior Cruciate Ligament Reconstruction: A Biomechanical Study.

PURPOSE: To evaluate the effect of knee flexion angle for hamstring graft fixation, full extension (FE), or 30°, on acceleration of the knee motion during pivot-shift testing after either anatomic or nonanatomic anterior cruciate ligament (ACL) reconstruction using triaxial accelerometry. METHODS: Two types of ACL reconstructions (anatomic and nonanatomic) using 2 different angles of knee flexion during graft fixation (FE and 30°) were performed on 12 fresh-frozen human knees making 4 groups: anatomic-FE, anatomic-30°, nonanatomic-FE, and nonanatomic-30°. Manual pivot-shift testing was performed at ACL-intact, ACL-deficient, and ACL-reconstructed conditions. Three-dimensional acceleration of knee motion was recorded using a triaxial accelerometer. RESULTS: The anatomic-30° group showed the smallest overall magnitude of acceleration among the ACL-reconstructed groups (P = .0039). There were no significant differences among the anatomic-FE group, the nonanatomic-FE group, and the nonantomic-30° group (anatomic-FE vs nonanatomic-FE, P = .1093; anatomic-FE vs nonanatomic-30°, P = .8728; and nonanatomic-FE vs nonanatomic-30°, P = .1093). After ACL transection, acceleration was reduced by ACL reconstruction with the exception of the nonanatomic-FE group that did not show a significant difference when compared with the ACL-deficient (P = .4537). CONCLUSIONS: The anatomic ACL reconstruction with the graft fixed at 30° of knee flexion better restored rotational knee stability compared with FE. An ACL graft fixed with the knee at FE in anatomic position did not show a significant difference compared with the nonanatomic ACL reconstructions. CLINICAL RELEVANCE: Knee flexion angle at the time of graft fixation for ACL reconstruction can be considered to maximize the rotational knee stability.

Biomechanical evaluation contribution of the acetabular labrum to hip stability.

PURPOSE: Knowledge of the effect of hip pathologies on hip biomechanics is important to the understanding of the development of osteoarthritis, and the contribution of the labrum to hip joint stability has had limited study. The purpose of this study was to evaluate the effect of labral injury to stability of the femoral head in the acetabular socket. METHODS: Ten cadaver hip specimens were tested using a robotic system under four different loading conditions: axial loading (80 N) along the femoral axis and axial loading (80 N) combined with either anterior, posterior or lateral loading (60 N). The hip states were examined were intact, with a 1.5 cm capsulotomy and with a 1 cm resection of the anterosuperior labrum. RESULTS: At 30° of flexion, under axial load, the displacement of the hip with capsulotomy and labral resection (9.6 ± 2.5 mm) was significantly larger then the hip with capsulotomy alone (5.6 ± 4.1 mm, p = 0.005) and the intact hip (5.2 ± 3.8 mm, p = 0.005). Also, at 30° of flexion, the displacement under combined axial and anterior/posterior load was increased with capsulotomy and labral resection. CONCLUSION: The acetabular labrum provides stability to the hip joint in response to a distraction force and combined distraction and translation forces. One centimetre of labral resection caused significant displacement ("wobbling" effect) of the femoral head within the acetabulum with normal range of motion. Successful labral repair could be crucial for restoration of the hip biomechanics and prevention of coxarthrosis.

A comparison of dynamic rotational knee instability between anatomic single-bundle and over-the-top anterior cruciate ligament reconstruction using triaxial accelerometry.

PURPOSE: Recently, single-bundle (SB) anterior cruciate ligament (ACL) reconstruction has been advanced by the anatomic concept, but the biomechanical outcome of the anatomic method has not been fully investigated, especially for rotational instability. Anatomic SB and the single over-the-top procedures are the treatment of choice for primary cases and revision or skeletally immature cases, respectively. The purpose of this study was to investigate the dynamic rotational instability of anatomic SB and over-the-top reconstruction during a pivot shift test using triaxial accelerometry. METHODS: Eight fresh frozen human cadaveric knees were used in this study. Rotational instability measurement was conducted during a pivot shift test by the use of a triaxial accelerometer attached to the tibia. The tests were performed in the ACL-intact, ACL-deficient and ACL-reconstructed knees with two different procedures (anatomic SB and over-the-top). The acceleration in three directions and the magnitude of acceleration were measured to evaluate rotational instability and compare between four different knee states. RESULTS: The overall magnitude of acceleration was significantly different (P < 0.01) between the ACL-intact knees and the ACL-deficient knees. Both anatomic SB and over-the-top ACL reconstruction significantly reduced the overall magnitude of acceleration compared to the ACL-deficient knees, but still had larger accelerations compared to the ACL-intact knees. There was no significant difference for the overall magnitude of acceleration between anatomic SB and over-the-top reconstruction procedure. CONCLUSION: Over-the-top reconstruction provides comparable result to anatomic SB reconstruction in terms of controlling the dynamic rotational stability. Over-the-top reconstruction might be one of the options for revision cases and in skeletally immature patients.

Soft Tissue Stabilization of the Hinge Position for Lateral Closing-Wedge Distal Femoral Osteotomy: An Anatomic Study.

Background: Soft tissue plays an important role in stabilizing the hinge point for osteotomy around the knee. However, insufficient data are available on the anatomic features of the soft tissue around the hinge position for lateral closing-wedge distal femoral osteotomy (LCWDFO). Purpose: To (1) anatomically analyze the soft tissue around the hinge position for LCWDFO, (2) histologically analyze the soft tissue based on the anatomic analysis results, and (3) radiologically define the appropriate hinge point to prevent unstable hinge fracture based on the results of the anatomic and histological analyses. Study Design: Descriptive laboratory study. Methods: In 20 cadaveric knees (age, 82.7 ± 7.8 years; range, 60-96 years), the soft tissue of the distal medial side of the femur was anatomically analyzed. The thicknesses of the periosteum and direct insertion of the adductor tendon (AT) were histologically examined and measured using an electron microscope. The thickness of the periosteum was visualized graphically, and the graph of the periosteum and radiograph of the knee were overlaid using image editing software. The appropriate hinge position was determined based on the periosteal thickness and attachment of the AT. Results: The mean thickness of the periosteum of the metaphysis was 352.7 ± 58.6 µm (range, 213.6-503.4 µm). The overlaid graph and radiograph revealed that the thickness of the periosteum changed at the part corresponding to the transition between the diaphyseal and metaphyseal ends of the femur. The mean width of the AT attached to the distal medial femur from the adductor tubercle toward the distal direction was 7.9 ± 1.3 mm (range, 6.3-9.7 mm). Conclusion: Results indicated that the periosteum and AT support the hinge for LCWDFO within the area surrounded by the apex of the adductor tubercle and the upper border of the posterior part of the lateral femoral condyle. Clinical Relevance: When the hinge point is located within the area surrounded by the apex of the adductor tubercle and the upper border of the posterior part of the lateral femoral condyle, these soft tissues work as stabilizers, and there is no risk of cutting into the joint space.

Effectiveness and safety of sarilumab in patients with rheumatoid arthritis: A multicenter, retrospective, inverse probability of treatment-weighted analysis based on the FRAB-registry.

OBJECTIVE: The efficacy and safety of sarilumab (SARI) were investigated in real-world clinical practice in Japan. METHOD: Subjects were 121 rheumatoid arthritis (RA) patients in 23 medical institutions in Fukuoka Prefecture, Japan, who started treatment with SARI between May 2018 and November 2021. Data on the SARI starting dose, patients' baseline characteristics, disease activity, and blood test data at the start of treatment, as well as follow-up data on the SARI dose, disease activity, and adverse events until Week 52. Safety and the continuation rate calculated by the Kaplan-Meier method were evaluated, and the effectiveness of treatment at 1 year was assessed using the clinical disease activity index (CDAI). Patients' baseline characteristics for which significant differences were evident were adjusted with a propensity score by using the inverse probability of treatment-weighting (IPTW) method. RESULTS: The continuation rate at Week 52 was 66.1%. The CDAI showed significant improvement from Week 4 that was maintained until Week 52. Comparisons conducted after IPTW adjustment for patients' baseline characteristics for which significant differences were evident revealed no significant differences at Week 52 between the groups classified by higher or lower body mass index (BMI) (p = 0.231), serious comorbidities (p = 0.973), MTX use (p = 0.321), or prior treatment with ≤ 1 or ≥ 2 biologic and targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) (p = 0.765). CONCLUSIONS: The results showed that the efficacy of SARI is not affected by BMI, comorbidities, MTX use, or the number of prior b/tsDMARDs, and no new safety concerns were apparent. Key Points • This is the first real-world clinical study to report on the efficacy and safety of SARI in Japan. The results of this study indicate that the efficacy of SARI was not affected by BMI, comorbidities, MTX use, or number of previous b/tsDMARDs. • It was shown that SARI can be used in a Japanese population without any new side effects.

The effect of tunnel placement on rotational stability after ACL reconstruction: evaluation with use of triaxial accelerometry in a porcine model.

PURPOSE: Conventional transtibial technique fails to restore the rotational knee stability in spite of successful anterior laxity, while anatomic anterior cruciate ligament reconstruction using the anteromedial portal technique has been developed expecting better rotational kinematics because of closer reproduction of the native anterior cruciate ligament anatomy. However, the rotational instability after those two procedures has not been fully examined especially in terms of dynamic component of the rotational stability. The purpose was to assess the effect of anatomic versus non-anatomic tunnel placement on rotational knee stability after anterior cruciate ligament reconstruction using triaxial accelerometry. METHODS: Sixteen porcine knees underwent a manual pivot-shift test at four different conditions: (1) anterior cruciate ligament intact, (2) anterior cruciate ligament deficient, (3) non-anatomic transtibial reconstruction, and (4) anatomic anteromedial portal reconstruction. The three-dimensional acceleration of knee motion during the pivot-shift test was recorded using a triaxial accelerometer. RESULTS: Both anterior cruciate ligament reconstructions decreased significantly the acceleration of the pivot-shift test from the increased level in the anterior cruciate ligament-deficient condition. However, the transtibial technique fails to reach the intact level of acceleration, while the anteromedial portal technique reduced the acceleration to even less than the intact level. CONCLUSION: The transtibial anterior cruciate ligament reconstruction could not restore the dynamic rotational stability of the intact knee, whereas the anteromedial portal technique restored the dynamic rotational stability closer to the intact level. LEVEL OF EVIDENCE: III.

Biomechanical comparison of different graft positions for single-bundle anterior cruciate ligament reconstruction.

PURPOSE: Recent reports have highlighted the importance of an anatomic tunnel placement for anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare the effect of different tunnel positions for single-bundle ACL reconstruction on knee biomechanics. METHODS: Sixteen fresh-frozen cadaver knees were used. In one group (n = 8), the following techniques were used for knee surgery: (1) anteromedial (AM) bundle reconstruction (AM-AM), (2) posterolateral (PL) bundle reconstruction (PL-PL) and (3) conventional vertical single-bundle reconstruction (PL-high AM). In the other group (n = 8), anatomic mid-position single-bundle reconstruction (MID-MID) was performed. A robotic/universal force-moment sensor system was used to test the knees. An anterior load of 89 N was applied for anterior tibial translation (ATT) at 0°, 15°, 30° and 60° of knee flexion. Subsequently, a combined rotatory load (5 Nm internal rotation and 7 Nm valgus moment) was applied at 0°, 15°, 30° and 45° of knee flexion. The ATT and in situ forces during the application of the external loads were measured. RESULTS: Compared with the intact ACL, all reconstructed knees had a higher ATT under anterior load at all flexion angles and a lower in situ force during the anterior load at 60° of knee flexion. In the case of combined rotatory loading, the highest ATT was achieved with PL-high AM; the in situ force was most closely restored with MIDMID, and the in situ force was the highest AM-AM at each knee flexion angle. CONCLUSION: Among the techniques, AM-AM afforded the highest in situ force and the least ATT.

A case of extrapulmonary tuberculosis after use of baricitinib.

Extrapulmonary tuberculosis (TB) can occur in patients treated with Janus kinase (JAK) inhibitors. We present a case of rheumatoid arthritis complicated by extrapulmonary TB following baricitinib treatment. A 45-year-old Japanese woman was diagnosed with rheumatoid arthritis at another hospital, and she subsequently started treatment with methotrexate (MTX) at 6.0 mg/week and prednisolone at 3.0 mg/day at our institute. The MTX dose was increased to 10 mg/week, and clinical remission was achieved; however, the disease activity flared up 6 months after the initial visit. Isoniazid (INH) prophylaxis was started following positive T-SPOT® screening for TB, and baricitinib (Olumiant®) was introduced 3 weeks later because of an insufficient response to MTX. INH prophylaxis was continued for 6 months. Ten months after starting INH treatment, a painless mass was observed on the left side of the patient's neck. Magnetic resonance imaging showed enlarged lymph nodes with calcification. A subsequent biopsy and pathologic examination led to a diagnosis of tuberculous lymphadenitis, and the patient was started on anti-TB therapy. Ten months later, the patient was still in remission and doing well. Extrapulmonary TB can be difficult to diagnose because of inconsistent physical and laboratory findings. When treating patients with JAK inhibitors, physicians should be cognisant of the potential for extrapulmonary TB to develop.

Biomechanics of the human triple-bundle anterior cruciate ligament.

PURPOSE: To investigate the biomechanics of the intermediate (IM), anteromedial (AM), and posterolateral (PL) bundles in the human anterior cruciate ligament (ACL). METHODS: Eighteen human cadaveric knees were tested with a robotic/universal force-moment sensor testing system. Anterior tibial translation (ATT) was determined under an 89-N anterior tibial load. Coupled ATT was determined under a combined rotatory load of 7-Nm valgus and 5-Nm internal rotation torque (pivot moment). Each bundle's in situ forces were measured under identical external loading conditions. RESULTS: Under anterior load, the PL bundle's in situ force was highest at 0° and decreased during flexion. Under the anterior load, the AM bundle's in situ force was significantly higher than the IM and PL bundles' force at 15°, 30°, and 60°. Under the pivot moment, the AM bundle's in situ force was significantly higher than the PL and IM bundles' force at 0° and 15°, and the IM bundle had the lowest in situ force at 0° but higher in situ force than the AM and PL bundles at 30° and 45°. IM and AM bundle removal increased ATT under the anterior load at all angles. Cutting the PL bundle after IM and AM bundle removal (whole ACL removal) significantly increased ATT under the anterior load at 0°, 15°, and 30° of knee flexion and increased coupled ATT under the pivot moment at 0° and 15°. CONCLUSIONS: The biomechanical role of each of the 3 ACL bundles (AM, IM, and PL) was measured with a robotic/universal force-moment sensor testing system. The AM bundle stabilized the knee against both the anterior and rotatory loads. The PL bundle stabilized the knee especially near full extension. The IM bundle supported the AM and PL bundles through all flexion angles, especially from 30° to 45°, against the rotatory load. CLINICAL RELEVANCE: Knowledge of functions of the different ACL bundles will help improve ACL reconstruction techniques to enable restoration of normal knee function.

Measurement of the end-to-end distances between the femoral and tibial insertion sites of the anterior cruciate ligament during knee flexion and with rotational torque.

PURPOSE: The aim of this study was to determine the end-to-end distance changes in anterior cruciate ligament (ACL) fibers during flexion/extension and internal/external rotation of the knee. METHODS: The positional relation between the femur and tibia of 10 knees was digitized on a robotic system during flexion/extension and with an internal/external rotational torque (5 Nm). The ACL insertion site data, acquired by 3-dimensional scanning, were superimposed on the positional data. The end-to-end distances of 5 representative points on the femoral and tibial insertion sites of the ACL were calculated. RESULTS: The end-to-end distances of all representative points except the most anterior points were longest at full extension and shortest at 90°. The distances of the anteromedial (AM) and posterolateral (PL) bundles were 37.2 ± 2.1 mm and 27.5 ± 2.8 mm, respectively, at full extension and 34.7 ± 2.4 mm and 20.7 ± 2.3 mm, respectively, at 90°. Only 4 knees had an isometric point, which was 1 of the 3 anterior points. Under an internal torque, both bundles became longer with statistical meaning at all flexion angles (P = .005). The end-to-end distances of all points became longest with internal torque at full extension and shortest with an external torque at 90°. CONCLUSIONS: Only 4 of 10 specimens had an isometric point at a variable anterior point. The end-to-end distances of the AM and PL bundles were longer in extension and shorter in flexion. CLINICAL RELEVANCE: The nonisometric tendency of the ACL and the end-to-end distance change during knee flexion/extension and internal/external rotation should be considered during ACL reconstruction to avoid overconstraint of the graft.

Acute Anterior Dislocation in a Total Knee Arthroplasty Patient With a History of Sarcoma Resection.

Dislocation after total knee arthroplasty (TKA) is a rare complication, and few cases of anterior dislocation have been reported. Furthermore, there are no reports of early postoperative dislocation. A 72-year-old woman who had previously undergone resection of the posterior thigh muscle group for liposarcoma of the thigh underwent TKA for knee osteoarthritis. However, anterior dislocation was observed at 1 week postoperatively. We considered that the cause of the early anterior dislocation was previous resection of the posterior soft tissues of the knee joint. This case is a rare report of early anterior postoperative dislocation after TKA.