Combined vertical and external rotational force in plantarflexion position produces posterior pilon fracture: A preliminary cadaveric study.

BACKGROUND: Posterior pilon fracture is speculated to occur by a combination of rotation and axial load, which makes it different from rotational posterior malleolar fracture or pilon fracture, but is not validated in vitro. The aim of the current study is to investigate the injury mechanisms of posterior pilon fracture on cadaveric specimens. METHODS: Eighteen cadaveric specimens were mounted to a loading device to undergo solitary vertical loading, solitary external rotational loading, and combined vertical and external rotational loading until failure, in initial position of plantarflexion with or without varus. The fracture characteristics were documented for each specimen. RESULTS: Vertical loading force combined with external rotation force diversified the fracture types resulting in pilon fracture, tibial spiral fracture, rotational malleolar fracture, talar fracture or calcaneal fracture. Vertical violence combined with external rotational loading in position of 45° of plantarflexion and 0° of varus produced posterior pilon fracture in specimens No. 13 and 14. CONCLUSION: Combination of vertical and external rotational force in plantarflexion position on cadaveric specimens produce posterior pilon fracture.

Comparison of different surgical treatments for stage II progressive collapsing foot deformity: a finite element analysis.

BACKGROUND: This study analyzed the advantages and disadvantages of different procedures for stage IIA progressive collapsing foot deformity (PCFD) through three-dimensional finite element models. METHODS: A previous validated stage IIA PCFD FEA model was established consisting of 16 bones, 56 ligaments, 5 muscles and soft tissues. The ligament properties of the spring, deltoid, short plantar and long plantar ligaments, and plantar fascia were attenuated according to a previous publication. Medial column fusion (MCF), medializing calcaneal osteotomy (MCO), lateral column lengthening (LCL), and subtalar joint arthroereisis (SJA) operations were simulated in this model. The indexes of plantar stress distribution, maximum von Mises of the medial and lateral columns, strain of the medial ligaments and plantar fascia that supported the medial longitudinal arch, arch height, talo-first metatarsal angle, calcaneus pitch angle, and talonavicular coverage angle were all compared before and after simulated single-foot weight loading. RESULTS: The maximum plantar stress of PCFD decreased with MCO and SJA but increased with MCF and LCL. MCF and LCL failed to significantly reduce the stress on the medial column fragments, thereby increasing their stress. Both MCO and SJA relieved medial plantar stress. MCF had no significant effect on stress relief of the medial ligament. MCO, LCL, and SJA were all shown to reduce the pressure on the medial plantar ligament, with LCL having the most obvious effect. All four procedures corrected the arch deformity; however, MCF was not as effective as the other methods. SJA is the best method for restoring arch height and correcting arch deformities. For stage IIA PCFD, isolated MCF failed to reduce pressure on the medial column; however, isolated MCO significantly reduced the pressure on the medial plantar and ligamentous soft tissues while restoring the foot's arch and correcting the hindfoot valgus. CONCLUSION: SJA with type II sinus tarsi implant effectively transferred pressure from the medial plantar tract to the lateral side and restored the arch. Isolated LCL was not found suitable for stage IIA PCFD.

Preoperative Lymphocyte-to-Monocyte Ratio Can Indicate the Outcomes in Repair of I-III Degree Injury of Lateral Ankle Ligament.

Background: This study is aimed at exploring the prognostic value of preoperative lymphocyte-to-monocyte ratio (LMR), an index of systemic inflammation before operation, in ankle lateral ligament repair (ALLR). Methods: A total of 213 I-III degrees injuries of lateral ankle ligament patients received ALLR and were followed up for more than 2 years. Univariate and multivariable linear regression analysis was used to determine the relationship between preoperative LMR and postoperative recovery. The evaluations of postoperative recovery include American Orthopaedic Foot and Ankle Society (AOFAS) score, Karlsson-Peter ankle score (KPAS), Cumberland Ankle Instability Tool (CAIT) score, Visual Analog Scale (VAS) score, and range of motion (ROM). The prognostic value of preoperative LMR was measured by receiver operating characteristic (ROC) curve. Results: 178 patients (178 ankles) were followed up successfully, with a follow-up of 2.82 ± 1.54 years. Overall, the mean AOFAS, KPAS, CAIT and VAS scores, and ankle varus angle were significantly improved at the final follow-up. Univariate and multiple linear regression analysis showed that preoperative LMR was the only independent factor associated with postoperative function, ROM, and pain. The preoperative LMR of patients with poor recovery was significantly lower than that of patients with good recovery. Based on the ROC analysis, the cutoff value of preoperative LMR was 3.824. The clinical outcomes of patients with preoperative LMR < 3.824 were significantly lower than that of patients with preoperative LMR ≥ 3.824. The corresponding specificity and sensitivity were 84.6% and 71.4%. Conclusion: The clinical outcomes of open or arthroscopic repair for ATFL injury are satisfactory. As a marker of systemic inflammation, preoperative LMR can be used as a prognostic indicator for ALLR.

Not Only in Sensorimotor Network: Local and Distant Cerebral Inherent Activity of Chronic Ankle Instability-A Resting-State fMRI Study.

BACKGROUND: Increasing evidence has proved that chronic ankle instability (CAI) is highly related to the central nervous system (CNS). However, it is still unclear about the inherent cerebral activity among the CAI patients. PURPOSE: To investigate the differences of intrinsic functional cerebral activity between the CAI patients and healthy controls (HCs) and further explore its correlation with clinical measurement in CAI patients. MATERIALS AND METHODS: A total of 25 CAI patients and 39 HCs were enrolled in this study. Resting-state functional magnetic resonance imaging (rs-fMRI) was used to detect spontaneous cerebral activity. The metrics of amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), and regional homogeneity (ReHo) of the two groups were compared by two-sample t-test. The brain regions that demonstrated altered functional metrics were selected as the regions of interest (ROIs). The functional connectivity (FC) was analyzed based on the ROIs. The Spearman correlation was calculated between rs-fMRI metrics and clinical scale scores. RESULTS: Compared with HCs, CAI patients showed higher ALFF and ReHo values in the right postcentral gyrus, the right precentral gyrus, and the right middle frontal gyrus, while lower fALFF values in the orbital-frontal cortex (OFC, p < 0.01 after correction). Increasing FC between the right precentral gyrus and the right postcentral gyrus while decreasing FC between the right precentral gyrus and the anterior cingulum cortex (ACC), the right middle frontal gyrus and the left middle temporal gyrus, and the OFC and left inferior parietal lobule (IPL) was observed. In addition, in the CAI group, the ReHo value negatively correlated with the Cumberland Ankle Instability Tool score in the right middle frontal gyrus (r = -0.52, p = 0.007). CONCLUSION: The CAI patients exhibited enhanced and more coherent regional inherent neuronal activity within the sensorimotor network while lower regional inherent activity in pain/emotion modulation related region. In addition, the information exchanges were stronger within the sensorimotor network while weaker between distant interhemispheric regions. Besides, the increased inherent activity in the right middle frontal gyrus was related to clinical severity. These findings may provide insights into the pathophysiological alteration in CNS among CAI patients.

The fibula and talus position difference in functional and mechanical ankle instability: MRI findings.

PURPOSE: This study aimed to use MRI to evaluate the fibula and talus position difference in functional and mechanical ankle stability patients. METHODS: 61 and 68 patients with functional and mechanical instability, and 60 healthy volunteers were involved. Based on the axial MRI images, the rotation of the talus was identified through the Malleolar Talus Index (MTI). The position relative to the talus (Axial Malleolar Index, AMI) and medial malleolus (Intermalleolar Index, IMI) were used to evaluated the displacement of the fibula. RESULTS: Post hoc analysis showed that the values of malleolar talus index was significantly larger among mechanical instability (89.18° ± 2.31°) than that in functional instability patients (86.55° ±61.65°, P < 0.001) and healthy volunteers (85.59° ± 2.42°, P < 0.001). The axial malleolar index of the mechanical instability patients (11.39° ± 1.41°) were significantly larger than healthy volunteers (7.91° ± 0.83°) (P < 0.0001). There were no statistically significant differences in the above three indexes between the functional instability patients and healthy volunteers. CONCLUSION: The functional instability patients didn't have a posteriorly positioned fibula and an internally rotated talus. The malleolar talus index was significantly larger among mechanical instability patients than that in functional instability patients. Increased malleolar talus index may become a new indirect MRI sign for identifying functional and mechanical instability patients.

A Retrospective Study on the Morphology of Posterior Malleolar Fractures Based on a CT Scan: Whether We Ignore the Importance of Fracture Height.

OBJECTIVE: The aim of this study was to investigate the respective correlation between the height (H) of a posterior malleolar fracture (PMF) and the involved area (S) of an articular surface and the presence of "die-punch." METHODS: Patients with closed posterior malleolar fractures admitted to our hospital from January 2015 to December 2017 were selected, with complete X-ray and 3D reconstruction CT imaging data. The gender, age, injured side, and surgical fixation methods of the patients were recorded. A preoperative ankle CT scan was performed, and the images were viewed through the PACS (Picture Archiving and Communication Systems). Simultaneously, the involved joint surface area (S) by the posterior malleolar fracture was measured, as well as the proportion of the fracture area to the total ankle joint area. On the sagittal reconstruction CT images, the height (H) of the posterior malleolar fracture was measured to compare the correlation between the height of the fracture and the area of the fracture, as well as the area ratio. Besides, according to the presence or absence of "die-punch," patients were divided into two groups: A and B. And each group was further divided into three subgroups according to age (16-39 years old, 40-59 years old, and ≥60 years old). The statistical differences in the height of fracture between the subgroups were compared. RESULTS: A total of 48 patients, aged 16-82 years, with an average age of 48.9 years, were included in this study, including 13 males and 35 females. There were 20 cases of left ankle injury and 28 cases of right ankle injury. The average height of the posterior malleolar fractures was 18.19 mm, the average area of the fracture was 202.28 mm2, and the average ratio of the fracture area to the total articular surface area was 17.84%. Besides, die-punch was seen in 27 cases and not in 21 cases. The average height of fractures was 21.33 ± 5.38 mm in group A1, 14.38 ± 9.01 mm in group B1, 18.30 ± 7.95 mm in group A2, 14.48 ± 5.37 mm in group B2, 26.26 ± 6.73 mm in group A3, and 12.77 ± 3.07 mm in group B3. CONCLUSION: The height (H) of the posterior malleolar fractures is positively correlated with the fracture area (S) and the fracture area ratio (FAR). The posterior malleolar fractures with "die-punch" tend to have a greater average height than that without "die-punch." In clinical work, orthopedic surgeons should not only pay attention to the size of the posterior malleolus fracture but also value its height, which hopefully could provide insight into the treatment and prognosis of PMF patients.

In vitro study of foot bone kinematics via a custom-made cadaveric gait simulator.

BACKGROUND: Quantifying detailed kinematics of the intrinsic foot bone during gait is crucial for understanding biomechanical functions of the foot complex musculoskeletal structure and making appropriate surgery decisions. RESEARCH QUESTION: The purpose of this experiment is to measure bone kinematic of the normal foot in a gait cycle via a custom-made cadaveric gait simulator. METHODS: In this experiment, we used a custom-made 6 degrees of freedom (DOF) of robotic gait simulator simulating normal human gait to measure the 3-dimensional (3D) kinematics of tibia, calcaneus, cuboid, navicular, medial cuneiform, first metatarsal, and fifth metatarsal through six cadaveric feet. RESULTS: The results showed that the kinematic of the intrinsic foot bones in the stance phase of the gait was successfully quantified using a custom-made robotic gait simulator. During walking stance, the joints in the medial column of foot had less movement than those in the lateral column. And during the later portion of stance, no rotational cease was observed in the movement between navicular and cuboid, calcaneocuboid joint, or cuneonavicular joint. CONCLUSION: This study described foot bone motion using a biomechanically near-physiological gait simulator with 6 DOF of the tibia. The kinematic data helps to clarify previous descriptions of several joint kinematics that are difficult to study in vivo. The methodology also provides a platform for researchers to explore more invasive foot biomechanics under dynamic and near-physiologic conditions.

A Radiographic Study of Biomechanical Relationship between the Achilles Tendon and Plantar Fascia.

BACKGROUND: Previously, scholars have concluded that the Achilles tendon and the plantar fascia were closely biomechanically related, although there is little clinical evidence of the relationship between the two. To investigate the biomechanical relationship between the Achilles tendon and the plantar fascia, the author used standing lateral ankle radiographs of patients with insertional Achilles tendonitis to determine the biomechanical relationship between the Achilles tendon and plantar fascia. METHODS: The author collected standing lateral ankle radiographs from patients with insertional Achilles tendonitis who accepted surgical treatment in the author's hospital from March 2009 to July 2018. According to whether there were bone spurs on the posterior side of the calcaneus, patients were divided into group A (spur present on the posterior side) and group B (spur not present on the posterior side). The positive rates of spurs on the plantar side of the calcaneus were determined in group A and group B. The chi-square test was used to compare the measurement results between the two groups. RESULTS: In group A, 13 heels were positive for calcaneal bone spurs, and the positive rate was 65.0%. In group B, 3 heels were positive for plantar calcaneal spurs, and the positive rate was 12%. Among all 16 patients with positive plantar calcaneal spurs, 13 had posterior calcaneal spurs (accounting for 81.3%), and 3 had negative results, accounting for 18.7%. There was a significant difference between the results in groups A and B (P < 0.05). CONCLUSION: There is a relationship between posterior calcaneal spurs and plantar calcaneal spurs in patients with insertional Achilles tendonitis, which can be inferred as resulting from the increasing tension in the biomechanically complex relationship between the Achilles tendon and the plantar fascia.

The Prognostic Landscape of Tumor-Infiltrating Immune Cells and Immune Checkpoints in Glioblastoma.

Tumor-infiltrating immune cells are part of a complex microenvironment and associated with improved clinical outcomes in a broad range of tumor types. However, a detailed map for the prognostic landscape of tumor-infiltrating immune cells and immune checkpoint modulators in glioblastoma is still lacking. Here, with the web-accessible resource, The Cancer Immunome Archive, 28 types of both adaptive and innate tumor-infiltrating immune cells were characterized in glioblastoma. Tumors lacking central memory CD4 T cells or natural killer cells were associated with better prognosis in glioblastoma, as verified by immunohistochemical analysis. Moreover, Kaplan-Meier analysis for a total of 71 key immune checkpoint molecules revealed that the expression level of inducible T cell costimulators, tumor necrosis factor superfamily member 14, and UL16 binding protein 1 were negatively correlated with the clinical outcome of patients with glioblastoma. In addition, there was a significant difference between nontumor and glioblastoma samples of several immune checkpoint modulators based on the expression level of their corresponding gene. Collectively, the annotation of tumor-infiltrating immune cells and immune checkpoint modulators in glioblastoma provides a valuable resource for identifying their involvement in tumor escape mechanisms and response to therapy.

Derotation of the Talus and Arthrodesis Treatment of Stages II-V Müller-Weiss Disease: Midterm Results of 36 Cases.

BACKGROUND: Various operative procedures have been reported for the treatment of Müller-Weiss disease (MWD). This study reports the midterm operative treatment results for stages II to V MWD with derotation of the talus and arthrodesis. METHODS: Thirty-four patients (36 feet) with MWD were treated by talonavicular (TN) or talonavicular-cuneiform (TNC) arthrodesis in our center from 2008 to 2015. The affected feet were staged according to the Maceira staging system (stage II: 9; stage III: 10; stage IV: 9; stage V: 8). The American Orthopaedic Foot & Ankle Society (AOFAS) midfoot scale, the visual analog scale (VAS), and relative radiologic parameters were evaluated preoperatively and also during follow-up. The mean follow-up duration was 38.2 (range, 25-113 months). RESULTS: The final follow-up showed satisfactory outcomes. Overall, the AOFAS scores improved from 41.5 (range, 20-56) to 85.3 (range, 68-100) points ( P <.001), and the VAS score decreased from 5.7 (range, 3-8) to 0.9 (range, 0-4) points ( P <.001). The Tomeno-Méary angle decreased from -6.7 (range, -26.4 to 17.7) to 0.7 (range, -5.3 to 7) degrees ( P=.001). The calcaneal pitch angle increased from 13.7 (range, 4.1-26.2) to 22.0 (range, 13.3-28.9) degrees ( P < .001). The anteroposterior (AP) talar-first metatarsal angle decreased from -15.8 (range, -30.1 to -13.7) to -7.0 (range, -25.9 to -8.9) degrees ( P < .001), and the AP talocalcaneal angle increased from 14.7 (range, 4.7-22.3) to 22.1 (range, 13.4-29.5) degrees ( P=.005). The AP talonavicular coverage angle decreased from -27.0 (range, -40.4 to -13.3) to -7.8 degrees (range, -20.7 to -1.8) degrees ( P < .001). CONCLUSION: The midterm results found that the TN or TNC joint fusion could achieve a favorable clinical and radiologic outcome for patients with MWD. Even for the patients with severe deformities (stages IV-V), this treatment strategy could also achieve satisfactory deformity correction and functional improvement. Intraoperative restoration of talus rotation was the key to normal alignment of the subtalar joint/TN joint. LEVEL OF EVIDENCE: Level IV, retrospective case series.