The deltoid ligament complex is reliably visualised as four fascicles in two layers with 3D volumetric MRI in the ankles of 20 asymptomatic volunteers.

PURPOSE: The anatomy of the deltoid ligament is complex. There is agreement on the presence of superficial and deep layers but the number and frequency of fascicles remains controversial. Identifying injuries to specific components of the deltoid ligament may inform decision-making on their management. The anatomy was reviewed to establish the number and dimension of fascicles visible with three-dimensional (3D) volumetric magnetic resonance images (MRI). METHODS: Twenty ankles from asymptomatic healthy volunteers were imaged with 3D volumetric MRI. The presence of individual fascicles was recorded and measured in 3D. RESULTS: The median age of participants was 26 years (range: 20-37) of which 13 (65%) were female. All 20 ankles had a deltoid ligament formed of four fascicles in two layers: three fascicles in the superficial layer; tibionavicular (mean dimensions 22.5 × 10.0 × 2.4 mm), tibiospring (16.6 × 6.7 × 1.9 mm) and tibiocalcaneal (23.8 × 4.6 × 1.8 mm) and a deep layer consisting of the tibiotalar fascicle, which could be divided into two parts: anterior tibiotalar (mean dimensions 10 × 5.6 × 4.1 mm) and the significantly larger posterior tibiotalar (14.2 × 13.8 × 17.5 mm, p < 0.01). There were no additional fascicles observed. CONCLUSIONS: The deltoid ligament complex was consistently visualised as four fascicles (tibionavicular, tibiospring, tibiocalcaneal, tibiotalar) in two layers (superficial and deep) in all 20 ankles. The posterior part of the tibiotalar fascicle was the thickest of all the fascicles in the deltoid ligament. It is, therefore, possible to accurately identify the components of the deltoid ligament, and 3T MRI can be used to assess fascicle-specific injury, which will guide treatment and rehabilitation. LEVEL OF EVIDENCE: Level III.

Directly measured strain patterns of the anterior talofibular and calcaneofibular ligaments after isolated ATFL repair in a combined ATFL and CFL injury: A cadaver study.

BACKGROUND: Even though 20% of chronic lateral ankle instability results from a combined anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) injury, only the ATFL is sutured using arthroscopic ligament repair techniques. Although some biomechanical and clinical studies have proved that isolated ATFL repair yields excellent results, previous biomechanical studies were performed using systems that only allow indirect estimations. The purpose of this study was to clarify strain patterns by directly measuring repaired ATFL and CFL strain patterns on cadaveric models that underwent isolated ATFL repair of a combined ATFL and CFL injury. METHODS: The miniaturization ligament performance probe (MLPP) system was used for directly measuring the strain patterns to insert the strain gauges into the mid-substance of normal and repaired ATFL and CFL fibers in five cadaveric specimens to allow measurement of strain patterns in the axial and three-dimensional motion of the ankle. RESULTS: The normal and repaired ATFL showed similar strain patterns in axial and three-dimensional motions. During the axial range of motion of the ankle, the repaired CFL showed a strain pattern almost similar to that of normal CFL, but the strain increased as the plantar flexion or dorsiflexion angle increased to the maximum value of 100 at 30° plantarflexion or strain values of 17-55/100 at 15°dorsiflexion. During three-dimensional motion, the repaired CFL was under the maximum value of 100 during dorsiflexion-inversion and exhibited less strain (7-38/100) during plantar flexion-eversion. CONCLUSION: The repaired CFL did not show a strain pattern that was completely consistent with a normal strain pattern; however, it did have some degree of tension similar to a normal strain pattern, even though it was not directly repaired.

Cartilage thickness in the medial compartment of the knee joint evaluated by MRI three-dimensional analysis correlates with weight-bearing line ratio and joint line convergence angle.

PURPOSE: The correlation between cartilage thickness evaluated by 3D MRI and knee alignment has not been elucidated. The study's purpose was to retrospectively verify whether average cartilage thickness calculated by the automatic MRI 3D analysis system for each subregion was correlated with knee alignment. METHODS: A total of 53 patients underwent medial meniscus repair or high tibial osteotomy for medial knee osteoarthritis. Cartilage thickness was automatically calculated using 3D MRI software. Knee alignment, weight-bearing line ratio (WBLR), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were calculated on a weight-bearing long-leg radiograph using digital planning software. The association between knee alignment and the average cartilage thickness at 18 subregions in the medial femoral condyle (MFC) and medial tibial plateau (MTP) was evaluated using Spearman's rank correlation coefficient. RESULTS: Cartilage thickness of the MFC had moderately positive correlations with WBLR at four subregions and weak correlations at two subregions. Cartilage thickness of the MTP had moderately positive correlations with WBLR at four subregions. Cartilage thickness of the MFC had moderately negative correlations with JLCA at six subregions. Cartilage thickness of the MTP had moderately negative correlations with JLCA at four subregions and a weak correlation at one subregion. Conversely, cartilage thickness had weak correlations with MPTA or LDFA. CONCLUSIONS: In knees with pathological conditions in the medial compartment, cartilage thicknesses by 3D MRI had positive correlations with WBLR and JLCA at almost all subregions of the MFC and at the anterior-middle and central-external of the MTP. Treatment strategies should be considered in light of these regions. LEVEL OF EVIDENCE: Cross-sectional study (diagnosis); Level of evidence, 2.

Low central sensitisation inventory score is associated with better post-operative outcomes of osteotomy around the knee.

PURPOSE: The purpose of this study was to investigate the potential association between central sensitisation inventory (CSI) scores and post-operative patient-reported outcomes (PROs) in patients underwent osteotomy around the knee (OAK), with a CSI cut-off score specific for knee osteoarthritis. METHODS: CSI scores were collected from 173 patients who underwent OAK, along with their knee injury and osteoarthritis outcome score (KOOS) and pain numeric rating scale (NRS) scores. Patients were divided into high-CSI score group and low-CSI score group with a cut-off score of 17. Multivariate linear regression was performed to test the association between CSI scores and post-operative outcomes. Pre-surgery KOOS and NRS scores and the rate of attainment of minimal clinically important difference (MCID) of KOOS scores was analysed as secondary outcomes. RESULTS: Low-CSI score group had significantly higher post-operative KOOS scores and lower pain NRS scores compared to the high-CSI score group (< p = 0.01) after adjusting for confounding factors. For pre-operative scores, only the KOOS-Symptom score was significantly different between the groups (64.7 ± 20.1 when CSI < 17 vs.55.1 ± 19.7 when CSI ≥ 17; p = 0.008). The low-CSI score group had significantly higher MCID achievement rates of KOOS-Pain, Symptom, and ADL than the high-CSI score group (86% vs. 68%; 74% vs. 55%; 86% vs. 67%, respectively; P < 0.05). CONCLUSIONS: This study established an association between post-operative CSI scores ≥ 17 and poorer outcomes following OAK, highlighting the potential value of the CSI in identifying patients in need of more comprehensive peri-operative pain management. LEVEL OF EVIDENCE: Level III. Retrospective comparative study.

Individual fascicles of the ankle lateral ligaments and the lateral fibulotalocalcaneal ligament complex can be identified on 3D volumetric MRI.

PURPOSE: Lateral ligament ankle sprains are common and the anatomy on imaging studies is vital for accurate diagnosis. The lateral fibulotalocalcaneal ligament (LFTCL) complex consists of the inferior fascicle of the anterior talofibular ligament (ATFL) which is connected by arciform fibres with the calcaneofibular ligament (CFL). The superior fascicle of ATFL is an independent structure that should be assessed individually. MRI evaluation of these distinct fascicles and the arciform fibres has not been described. The aim of this study is to identify the anatomical relationship of these components of the LFTCL complex in healthy individuals on MRI. METHODS: Thirty ankles from healthy volunteers were imaged using 3D volumetric MRI. The ATFL fascicles and size were evaluated. Presence of arciform fibres connecting the inferior ATFL fascicle and CFL to form the LFTCL complex and anatomical relationship around the lateral ligament complex were assessed. RESULTS: Both the superior and inferior ATFL fascicles were observed in 26 (86.7%) ankles. The superior ATFL fascicle was significantly larger in all specimens (39% longer and 80.7% wider). For the specimens with a single fascicle, this was similar in size to the superior fascicle observed in the other 26 specimens. These measurements were not affected by age or gender. Arciform fibres of the LFTCL complex were identified in 22 (84.6%) specimens with two ATFL fascicles and three (75%) ankles with a single ATFL fascicle. Connecting fibres from the ATFL to PTFL were observed in 19 (63.3%) ankles while connections between the CFL and PTFL were identified in 21 (70%) ankles. Five ankles had a perforating artery visualized in the intervening space between the superior and inferior ATFL fascicles (a branch of the lateral tarsal artery of the dorsalis pedis artery). CONCLUSION: Two distinct ATFL fascicles may be identified in the majority of ankles on MRI. Isolated injury to the superior fascicle identified on MRI may be useful when diagnosing patients presenting with symptoms of subtle instability without overt ankle laxity on clinical examination. The current study is the first to identify the arciform fibres of the LFTCL complex supporting isolated ATFL repair in the presence of intact LFTCL complex. LEVEL OF EVIDENCE: Level III.

Effects of different surgical procedures for meniscus injury on two-year clinical and radiological outcomes after anterior cruciate ligament reconstructions. -TMDU MAKS study.

BACKGROUND: The treatment of meniscus injuries combined with anterior cruciate ligament (ACL) reconstruction would be important to improve outcomes after ACL reconstruction. However, the effects of treatment methods for meniscus after ACL reconstruction have not been thoroughly investigated. The objective of this study was to investigate the effects of treatment methods for meniscus on clinical and radiological outcomes at 2 years after ACL reconstruction. METHODS: Three-hundred and eighteen patients with primary ACL reconstruction using autologous hamstring tendon registered in our multicenter study database and who were followed up for 2 years were included. They were then divided into 3 groups, the no meniscal lesion/untreated group (n = 149), the meniscal repair group (n = 139), and the meniscal resection group (n = 30). Patient-based subjective evaluations (Lysholm score, Knee injury and Osteoarthritis Outcome score and International Knee Documentation Committee subjective score), objective evaluations (Lachman test, pivot shift test and KT measurement), and radiological measurements (medial and lateral joint space width) were compared among the 3 groups preoperatively and at 2 years follow-up. RESULTS: All subjective scores and objective evaluations significantly improved in all groups without significant differences among the groups postoperatively. Regarding radiological findings, the medial joint space width significantly decreased only in the resection group during the 2-year period, and the medial joint space width in the resection group was significantly smaller than that of the other groups at the 2-year follow-up. Moreover, the medial joint space width significantly decreased during the 2-year period when MM was resected. CONCLUSIONS: In radiological findings, medial meniscus resection decreased medial joint space width two years after ACL reconstruction. On the other hand, treatment methods for meniscus neither significantly affected subjective nor objective findings until the 2-year follow-up. LEVEL OF EVIDENCE: Ⅱ, Cohort study.

Strain patterns in normal anterior talofibular and calcaneofibular ligaments and after anatomical reconstruction using gracilis tendon grafts: A cadaver study.

BACKGROUND: Inversion ankle sprains, or lateral ankle sprains, often result in symptomatic lateral ankle instability, and some patients need lateral ankle ligament reconstruction to reduce pain, improve function, and prevent subsequent injuries. Although anatomically reconstructed ligaments should behave in a biomechanically normal manner, previous studies have not measured the strain patterns of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) after anatomical reconstruction. This study aimed to measure the strain patterns of normal and reconstructed ATFL and CFLs using the miniaturization ligament performance probe (MLPP) system. METHODS: The MLPP was sutured into the ligamentous bands of the ATFLs and CTLs of three freshly frozen cadaveric lower-extremity specimens. Each ankle was manually moved from 15° dorsiflexion to 30° plantar flexion, and a 1.2-N m force was applied to the ankle and subtalar joint complex. RESULTS: The normal and reconstructed ATFLs exhibited maximal strain (100) during supination in three-dimensional motion. Although the normal ATFLs were not strained during pronation, the reconstructed ATFLs demonstrated relative strain values of 16-36. During the axial motion, the normal ATFLs started to gradually tense at 0° plantar flexion, with the strain increasing as the plantar flexion angle increased, to a maximal value (100) at 30° plantar flexion; the reconstructed ATFLs showed similar strain patterns. Further, the normal CFLs exhibited maximal strain (100) during plantar flexion-abduction and relative strain values of 30-52 during dorsiflexion in three-dimensional motion. The reconstructed CFLs exhibited the most strain during dorsiflexion-adduction and demonstrated relative strain values of 29-62 during plantar flexion-abduction. During the axial motion, the normal CFLs started to gradually tense at 20° plantar flexion and 5° dorsiflexion. CONCLUSION: Our results showed that the strain patterns of reconstructed ATFLs and CFLs are not similar to those of normal ATFLs and CFLs.

Three-dimensional analysis of anterior talofibular ligament strain patterns during cadaveric ankle motion using a miniaturized ligament performance probe.

BACKGROUND: Measuring the strain patterns of ligaments at various joint positions informs our understanding of their function. However, few studies have examined the biomechanical properties of ankle ligaments; further, the tensile properties of each ligament, during motion, have not been described. This limitation exists because current biomechanical sensors are too big to insert within the ankle. The present study aimed to validate a novel miniaturized ligament performance probe (MLPP) system for measuring the strain patterns of the anterior talofibular ligament (ATFL) during ankle motion. METHODS: Six fresh-frozen, through-the-knee, lower extremity, cadaveric specimens were used to conduct this study. An MLPP system, comprising a commercially available strain gauge (force probe), amplifier unit, display unit, and logger, was sutured into the midsubstance of the ATFL fibers. To measure tensile forces, a round, metal disk (a "clock", 150 mm in diameter) was affixed to the plantar aspect of each foot. With a 1.2-Nm load applied to the ankle and subtalar joint complex, the ankle was manually moved from 15° dorsiflexion to 30° plantar flexion. The clock was rotated in 30° increments to measure the ATFL strain detected at each endpoint by the miniature force probe. Individual strain data were aligned with the neutral (0) position value; the maximum value was 100. RESULTS: Throughout the motion required to shift from 15° dorsiflexion to 30° plantar flexion, the ATFL tensed near 20° (plantar flexion), and the strain increased as the plantar flexion angle increased. The ATFL was maximally tensioned at the 2 and 3 o'clock (inversion) positions (96.0 ± 5.8 and 96.3 ± 5.7) and declined sharply towards the 7 o'clock position (12.4 ± 16.8). Within the elastic range of the ATFL (the range within which it can return to its original shape and length), the tensile force was proportional to the strain, in all specimens. CONCLUSION: The MLPP system is capable of measuring ATFL strain patterns; thus, this system may be used to effectively determine the relationship between limb position and ATFL ankle ligament strain patterns.

Strain pattern of each ligamentous band of the superficial deltoid ligament: a cadaver study.

BACKGROUND: There are few reports on the detailed biomechanics of the deltoid ligament, and no studies have measured the biomechanics of each ligamentous band because of the difficulty in inserting sensors into the narrow ligaments. This study aimed to measure the strain pattern of the deltoid ligament bands directly using a Miniaturization Ligament Performance Probe (MLPP) system. METHODS: The MLPP was sutured into the ligamentous bands of the deltoid ligament in 6 fresh-frozen lower extremity cadaveric specimens. The strain was measured using a round metal disk (clock) fixed on the plantar aspect of the foot. The ankle was manually moved from 15° dorsiflexion to 30° plantar flexion, and a 1.2-N-m force was applied to the ankle and subtalar joint complex. Then the clock was rotated every 30° to measure the strain of each ligamentous band at each endpoint. RESULTS: The tibionavicular ligament (TNL) began to tense at 10° plantar flexion, and the tension becomes stronger as the angle increased; the TNL worked most effectively in plantar flex-abduction. The tibiospring ligament (TSL) began to tense gradually at 15° plantar flexion, and the tension became stronger as the angle increased. The TSL worked most effectively in abduction. The tibiocalcaneal ligament (TCL) began to tense gradually at 0° dorsiflexion, and the tension became stronger as the angle increased. The TCL worked most effectively in pronation (dorsiflexion-abduction). The superficial posterior tibiotalar ligament (SPTTL) began to tense gradually at 0° dorsiflexion, and the tension became stronger as the angle increased, with the SPTTL working most effectively in dorsiflexion. CONCLUSION: Our results show the biomechanical function of the superficial deltoid ligament and may contribute to determining which ligament is damaged during assessment in the clinical setting.

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.

Effects of different femoral tunnel positions on tension changes in anterolateral ligament reconstruction.

PURPOSE: Several kinds of anterolateral ligament (ALL) reconstructions to augment intra-articular anterior cruciate ligament reconstruction to better control anterolateral rotational instability (ALRI) have been reported. However, the optimal femoral attachment site for ALL reconstruction is still unclear. The purpose of this study was to investigate the effects of different femoral attachment sites on the tension changes through knee motions in different situations in order to determine a recommended femoral attachment site for ALL reconstruction. METHODS: Six fresh-frozen cadaveric knees were included. ALL reconstructions were performed with three different femoral attachment sites (F1: 2 mm anterior and 2 mm distal to the lateral epicondyle, F2: 4 mm posterior and 8 mm proximal to the lateral epicondyle and F3: position for the lateral extra-articular tenodesis). The graft tension changes were measured by a graft tensioning system during knee flexion-extension and manual maximum internal/external tibial rotation in the following situations: (1) intact, (2) ALL cut, (3) ALL and ACL cut and (4) ALL cut and ACL reconstructed. Effects of the different femoral attachment sites, the route superficial or deep to the LCL, and the situations of (1) to (4) were calculated via repeated-measures analysis of variance. RESULTS: The tension of F1 was higher in flexion and lower in extension, whereas the tension of F2 and F3 was higher in extension and lower in flexion. F2 showed the smallest tension change. Situations of (1) to (4) did not affect tension changes. The graft tension became higher with internal rotation and lower with external rotation regardless of femoral attachment sites or situations. CONCLUSION: With F2-4 mm posterior and 8 mm proximal to the lateral epicondyle-the reconstructed ALL had the least tension change with only a slight increase in tension as the knee extended. This result indicates that F2 is recommended for ALL reconstruction to better control ALRI, which will help determine the optimal femoral tunnel position for ALL reconstruction.

In-vivo kinematics of high-flex posterior-stabilized total knee prosthesis designed for Asian populations.

PURPOSE: The purpose of this study was to determine in-vivo kinematics of our developed posterior-stabilized (PS) total knee prosthesis for Asian populations in comparison with a popular high-flexion PS prosthesis. METHODS: We analyzed 62 osteoarthritic knees: 31 knees with the new PS prosthesis (group A) and 31 knees with a popular high-flexion PS prosthesis (group B). Radiographic knee images were taken during standing, lunge, and kneeling activities. The three-dimensional position and orientation of the implant components were determined using model-based shape matching techniques. RESULTS: Group A showed slightly greater implant flexion angles compared with knees with conventional prosthesis at maximum lunge (average: 119 vs. 110°, p = 0.001), and at maximum kneeling (121 vs. 114°, p = 0.004), although the range of motion was not significantly different. The femoral centre positions were more posterior in group A at standing, at 90° lunge, at maximum lunge (-9 and -7 mm, p = 0.004), at 90° kneeling, and at maximum kneeling (-9 vs. -7 mm, p = 0.016), and posterior translations of the femoral center were greater at 90° knee flexion postures. The femoral centre positions had a strong negative correlation with implant flexion angles at maximum lunge in group B (r = -0.893, p < 0.001), but not in group A (p = 0.242). CONCLUSIONS: The new PS prosthesis designed for Asian knee morphology achieved flexion angles and range of motion at least comparable to that of conventional high-flexion PS prosthesis. The femoral roll-back pattern, however, is different from a conventional knee, reflecting the post/cam design.

A comparison of abductor hallucis muscle activation and medial longitudinal arch angle during nine different foot exercises.

BACKGROUND: Intrinsic foot muscles are known to support the medial longitudinal arch (MLA) and stabilize the foot, and they are activated with weight bearing and increased postural demand. Various types of intrinsic foot muscle training have been reported, but one of the most useful of these, the short foot exercise, is challenging to perform effectively and requires practice, making it difficult to implement in ordinary clinical settings. RESEARCH QUESTION: What are the differences in abductor hallucis longus (ABH) muscle activity and MLA angle during intrinsic foot muscle exercises that employ weight bearing and balancing conditions when they are performed with minimal practice? METHODS: Sixteen healthy volunteers performed nine different intrinsic foot muscle exercises, practiced once or twice. The exercises consisted of toe curl, short foot without pushing, short foot with pushing and toe spread exercises in sitting and standing positions, and single leg swing in a standing position. Each exercise was performed three times for five seconds. The activities of the ABH muscles were measured using surface electromyographic (EMG) sensors and the MLA angles during the exercises were captured using an optical motion tracking system. The integrals of the ABH EMG signals were calculated. RESULTS: Differences in the integral and maximum of the ABH EMG signal were found between the exercises (p < 0.001). Post-hoc pair-wise analysis revealed that the EMG activity was larger during the swing exercise than in exercises other than toe spread, both in sitting and standing positions, and short foot exercise with pushing while standing. The minimum MLA angle during each exercise was smaller for the toe spread exercise in a sitting position than other exercises (p < 0.023). SIGNIFICANCE: A single leg swing exercise may be effective for self-exercise of intrinsic foot muscles, particularly when intensive supervised physiotherapy is not possible.

Foot and Ankle MRI Findings in Asymptomatic Professional Ballet Dancers.

Background: Previous research in sport populations has demonstrated that abnormal magnetic resonance imaging (MRI) findings may be present in individuals without symptoms or known pathology. Extending this understanding to ballet, particularly in relation to the foot and ankle, is important to guide medical advice given to dancers. Purpose: To assess foot and ankle MRI scans in asymptomatic ballet dancers focusing on bone marrow edema and the posterior ankle and to investigate whether these MRI findings would become symptomatic within 1 year. Study Design: Case series; Level of evidence, 4. Methods: In total, 31 healthy dancers (62 feet/ankles; 15 male and 16 female; age, 26.5 ± 4.3 years) who were dancing in full capacity were recruited from an elite professional ballet company. Orthogonal 3-plane short tau inversion recovery imaging of both feet and ankles was obtained using 3T MRI and the images were reviewed using a standardized evaluation form by 2 musculoskeletal radiologists. Injuries in the company were recorded and positive MRI findings were assessed for correlation with any injuries requiring medical attention during the subsequent 12 months. Results: A total of 51 (82%) of the 62 feet and ankles had ≥1 area of bone marrow edema. The most common locations of bone marrow edema were the talus (n = 41; 66%), followed by first metatarsal (n = 14; 23%). Os trigonum and Stieda process were seen in 5 (8%) and 8 (13%) ankles, respectively. Among them, 2 os trigona showed bone marrow edema. Fluid in the anterior and posterior talocrural joints and the subtalar joint was observed in 48%, 63%, and 63% of these joints, respectively. Fluid around foot and ankle tendons was observed, with the most prevalent being the flexor hallucis longus tendon (n = 13; 21%). Two dancers who had positive findings on their MRI subsequently developed symptoms during the next 12 months. Conclusion: Positive MRI findings are commonplace in the foot and ankle of asymptomatic professional ballet dancers. The majority do not result in the development of symptoms requiring medical attention within 12 months. Careful interpretation of MRI findings with the dancer's clinical picture is required before recommending activity modification or further intervention.

Steep medial posterior tibial slope angle and ramp lesion are independent risk factors for an increase in quantitatively measured pivot shift in patients with ACL-deficient knees.

Background: Delayed anterior cruciate ligament (ACL) reconstruction often causes residual anterolateral rotatory instability (ALRI) and consequent knee osteoarthritis, warranting the recommendation of early ACL reconstruction within 6 months after injury. Nonetheless, some cases show notable instability, even shortly after injury. The purpose of this study was to identify risk factors for an increase in quantitatively measured pivot shift in patients with ACL-deficient knees within 6 months after injury. Methods: Patients with primary ACL reconstruction within 6 months after injury and quantitative triaxial accelerometer measurements of preoperative pivot shift were included. Descriptive statistics were calculated for 11 independent variables (age, gender, time from injury to surgery, KT-1000, knee extension angle, lateral and medial posterior tibial slope angle, medial and lateral meniscus tears, ramp lesion and Tegner active scale). A single regression analysis was performed on the 11 items and acceleration during the pivot shift, and a multiple regression analysis was performed for items with p value less than 0.1. Results: Overall, 111 patients met the inclusion criteria. Single regression analysis showed that medial posterior tibial slope angle, medial meniscus tear and ramp lesion were significantly correlated with acceleration during the pivot shift (p < 0.001, p = 0.04 and p = 0.001). Multiple regression analysis identified medial posterior tibial slope angles and ramp lesions as independent factors for increased preoperative pivot shift (p = 0.005 and 0.01). Conclusion: A steep medial posterior tibial slope angle and ramp lesion were independent risk factors for increased quantitatively measured pivot shift in patients with ACL-deficient knees. Level of Evidence: Level IV, case series study.

Characteristics of the synovial microenvironment and synovial mesenchymal stem cells with hip osteoarthritis of different bone morphologies.

BACKGROUND: Variations in bone morphology in patients with hip osteoarthritis (HOA) can be broadly categorized into three types: atrophic, normotrophic, and hypertrophic. Despite the investigations examining clinical elements, such as bone morphology, pain, and range of motion, our understanding of the pathogenesis of HOA remains limited. Previous studies have suggested that osteophytes typically originate at the interface of the joint cartilage, periosteum, and synovium, potentially implicating synovial mesenchymal stem cells (SMSCs) in the process. This study aimed to investigate the potential factors that drive the development of bone morphological features in HOA by investigating the characteristics of the synovium, differentiation potential of SMSCs, and composition of synovial fluid in different types of HOA. METHODS: Synovial tissue and fluid were collected from 30 patients who underwent total hip arthroplasty (THA) with the variable bone morphology of HOA patients. RNA sequencing analysis and quantitative reverse transcription-polymerase chain reaction (RT-qPCR) were performed to analyse the genes in the normotrophic and hypertrophic synovial tissue. SMSCs were isolated and cultured from the normotrophic and hypertrophic synovial tissues of each hip joint in accordance with the variable bone morphology of HOA patients. Cell differentiation potential was compared using differentiation and colony-forming unit assays. Cytokine array was performed to analyse the protein expression in the synovial fluid. RESULTS: In the RNA sequencing analysis, 103 differentially expressed genes (DEGs) were identified, predominantly related to the interleukin 17 (IL-17) signalling pathway. Using a protein-protein interaction (PPI) network, 20 hub genes were identified, including MYC, CXCL8, ATF3, NR4A1, ZC3H12A, NR4A2, FOSB, and FOSL1. Among these hub genes, four belonged to the AP-1 family. There were no significant differences in the tri-lineage differentiation potential and colony-forming capacity of SMSCs. However, RT-qPCR revealed elevated SOX9 expression levels in synovial tissues from the hypertrophic group. The cytokine array demonstrated significantly higher levels of CXCL8, MMP9, and VEGF in the synovial fluid of the hypertrophic group than in the normotrophic group, with CXCL8 and MMP9 being significantly expressed in the hypertrophic synovium. CONCLUSION: Upregulation of AP-1 family genes in the synovium and increased concentrations of CXCL8, MMP9, and VEGF were detected in the synovial fluid of the hypertrophic group of HOA patients, potentially stimulating the differentiation of SMSCs towards the cartilage and thereby contributing to severe osteophyte formation.