Modified Stabilization Test to Diagnose Chronic Syndesmotic Injuries Based on Posture Control.

BACKGROUND: To propose and validate a modified noninvasive method for the diagnosis of chronic syndesmotic injuries. METHODS: This study included 16 patients with chronic ankle instability. Herein, we propose the Modified Stabilization Test, a new measurement for use in the diagnosis of chronic syndesmotic injury, as determined by wearing a 60-kPa pneumatic brace. The test combines the center of pressure and sensory organization test to measure postural control. For comparison, we also measured the tibiofibular clear space, tibiofibular overlap, and medial clear space using anteroposterior radiograph; a line marked horizontally above the tibial plaque using computed tomography (CT) to measure the syndesmotic gap and fibular rotation angle; and magnetic resonance imaging (MRI) scans to determine the presence of the λ sign. The distance of syndesmosis was confirmed in 16 individuals through arthroscopy, and the results of the examination were used to determine the diagnostic efficacy of each index. RESULTS: Receiver operating characteristic curve analysis revealed that the optimal cut-off value, sensitivity, and specificity of the Modified Stabilization Test for the diagnosis of chronic syndesmotic injuries were 0.80, 100%, and 87.5%, respectively. The area under the curve (AUC) of the Modified Stabilization Test was 0.906 (95% CI 0.656, 0.993; P < .001), which was superior to imaging indices such as radiography, CT, and MRI (AUC = 0.516-0.891). CONCLUSION: We developed the Modified Stabilization Test-a noninvasive diagnostic tool for the screening of chronic syndesmotic injuries. The test showed high sensitivity and specificity for the identification of chronic syndesmotic injuries and is helpful in the identification of chronic syndesmotic injuries. LEVEL OF EVIDENCE: Level II, diagnostic-investigating a diagnostic test.

Biomechanical comparison between bioabsorbable and medical titanium screws in distal chevron osteotomy of first metatarsal in hallux valgus treatment.

Polylactic acid (PLA) composite materials have been used for manufacturing surgical internal fixations owing to their satisfactory mechanical strength and absorbability. This, in turn, reduces the pain and risks associated with the secondary operation on patients. Although the mechanical properties of bioabsorbable materials have been considerably enhanced via modifications and optimization, the strength and stiffness of these materials are considerably inferior to those of metals. Therefore, whether PLA fixation can satisfy the required mechanical properties has been a consistent subject of interest in clinical practice. In this study, the mechanical properties of PLA bioabsorbable (Changchun SinoBiomaterials Co., Ltd., China) and titanium hollow screws (Shanghai Carefix Medical Instrument Co., Ltd., China) were compared in hallux valgus surgery with chevron osteotomy. Three-dimensionally printed osteotomy guides were used for cutting the artificial first metatarsal model (SKU3422, Sawbones) to reduce the errors due to the variations in individual bone densities and osteotomy angles; the cut parts were subsequently fixed with the PLA and titanium alloy screws. A digital image correlation system was used to obtain the full-field strain of the specimen to evaluate the mechanical behaviors under static and fatigue loads. The experimental results demonstrated that, by designing a reasonable osteotomy angle, the compressive strength of the specimen with PLA screws under chevron osteotomy can be as high as that of the specimen with titanium screws. Moreover, their stiffness can reach up to 60%-90% that of titanium screws. After 240,000 cycles of compression, the PLA screws maintained their strength and stiffness. These bioabsorbable fixtures can effectively prevent stress shielding under a suitable osteotomy. Hence, as an optimal substitute for metal fixtures, an increase in clinical applications to surgery is anticipated, along with progressive in-depth research on the biomechanical properties of bioabsorbable materials.

Ankle distraction arthroplasty for the treatment of severe ankle arthritis: Case report, technical note, and literature review.

RATIONALE: Widely applied in the treatment of severe ankle arthritis (AA), ankle distraction arthroplasty (ADA) can avoid not only the ankle range of motion loss but also ankle fusion. However, the clinical outcomes of ADA for severe AA are poorly understood. This study aims to present our clinical outcomes of severe AA treated by ADA. PATIENT CONCERNS: A 53-year-old man suffered right ankle sprain 10 years ago, endured right ankle pain and limited movement for 6 years. DIAGNOSIS: The patient was diagnosed as severe AA. INTERVENTIONS: He received ankle distraction arthroplasty. No adjuvant procedures were performed. The visual analog scale (VAS), the American Orthopaedic Foot and Ankle Society (AOFAS) score, the short-form (SF)-36 physical component summary (PCS) score and ankle activity score (AAS) were recorded to access the clinical outcomes pre- and postoperatively. Moreover, ankle joint space distance was evaluated on weight-bearing radiographs. OUTCOMES: The patient derived effective pain relief and restored a satisfactory range of movement. There was a 13-month follow-up period after frame removal. The AOFAS score improved from 56 preoperatively to 71 postoperatively. The VAS score decreased from 6 prior to surgery to 1 after surgery. The SF-36 PCS was 47.2 and 71.8 pre- and postoperative, respectively. The AAS scores were improved from 3.4 preoperatively to 7.3 postoperatively. LESSONS: ADA is reliable to achieve pain relief, functional recovery, and serve AA resolution. Besides, it is an alternative to ankle arthrodesis or total ankle arthroplasty in selected patients with severe AA.

Accurate Osteotomy for the Treatment of a Rare Case of Postaxial Polydactyly of the Foot That Originated From a Deformed Calcaneus Using a 3D-Printed Guiding Plate.

Polydactyly is a common congenital deformity of the foot that can be categorized as preaxial, central, or postaxial. Current treatments involve resecting the supernumerary toe(s) and repairing the normal toe(s) and soft tissue. Here, we present the first published report describing a very rare case of polydactyly of the foot, in which the supernumerary toe originated from a deformed calcaneus, which formed an abnormal bony bump. Preoperatively, 3-dimensional (3D) computed tomography reconstruction images revealed the morphology of the deformed toe and calcaneus, and gait analysis showed an abnormal weightbearing zone in the left foot. The 3D printing technology and a specially designed 3D-printed guiding plate were used for osteotomy. Postoperatively, x-ray showed that the calcaneus had a normal shape and surface, whereas gait analysis showed that the left foot was uniformly loaded and the area of pain was eliminated. Our findings should raise awareness among clinicians that a 3D-printed guiding plate is useful in the treatment of such an unusual deformity.

Calcium Phosphate Cement loaded with 10% vancomycin delivering high early and late local antibiotic concentration in vitro.

BACKGROUND: Antibiotics impregnated calcium phosphate cement (CPC) has emerged as a local treatment of osteomyelitis. However, there is no study investigating the optimal concentrations of vancomycin (VCM) included in CPC to obtain prolonged drug release (≥8 weeks) and also with enough compressive strength (>the normal cancellous bone, 11MPa) for osteomyelitis therapy. Therefore, we bring forward two questions: 1) Was antibiotic activity of the eluates correlated to the load of antibiotics within the cement? 2) Were the mechanical properties of CPC affected by VCM-loading? HYPOTHESIZED: There was an optimal concentrations of vancomycin (VCM) loaded in CPC which could provide sufficient effective antibacterial time (≥8 weeks) and enough compressive strength (>11MPa). MATERIALS AND METHODS: CPC specimens were obtained by incorporating different doses (weigh ratios of 0%, 5%, 10%, 15%, 20%, 25 and 30%) of injectable VCM into CPC. The antibacterial effect of released VCM solution against Staphylococcus aureus was assessed by inhibition ring assays. The physicochemical properties such as compressive strengths were characterized and compared among these specimens. RESULTS: Drug release profiles showed only 5 and 10% VCM-loaded CPC displayed a long enough drug release time (at least 8 weeks) and maintained the eluate concentrations (>4µg/mL) with effective antibacterial ability. The concentration of VCM in 10% group at 8th week was twice higher than 5% group. Compressive strength test showed that the proportional increase of VCM/CPC ratios resulted in a significant decrease of compressive strength (r=-0.906, p<0.001). CONCLUSION: 10% VCM-loaded CPC offered the optimal physicochemical properties and drug releasing profile and appears as the most suitable concentration for clinical use. LEVEL OF EVIDENCE: III.

LIM kinase 1 is required for insulin­dependent cell growth of osteosarcoma cell lines.

Osteosarcoma is a type of malignant bone tumor with high metastasis and poor prognosis. Previous studies have demonstrated the involvement of LIM kinase 1 (LIMK1) in the proliferation of osteosarcoma cells. LIMK1 is overexpressed in human osteosarcoma tissues and cell lines. To further study LIMK1-associated mechanisms, we used shRNA targeted to the LIMK1 gene to block its expression in the osteosarcoma cell lines MG63 and U2OS. Insulin promoted the proliferation of MG63 cells in a time- and dose-dependent manner, however, this insulin induced proliferation was significantly inhibited by transfection of shRNA targeted to the LIMK1 gene, as well as by the PI3K inhibitor LY294002, but not by the mitogen­activated protein kinase (MAPK) inhibitor PD98059. The level of cofilin phosphorylation was increased significantly following stimulation of insulin for 24 h, indicating the activation of LIMK1. MG63 cell proliferation was also significantly inhibited by 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) in a time-dependent manner. Furthermore, 1,25(OH)2D3 negated the inhibitory effect of LIMK1 shRNA, indicating that LIMK1 is important in the inhibitory pathway of 1,25(OH)2D3. The present study confirms that LIMK1 is important in regulating osteosarcoma cell proliferation via the insulin/PI3K/LIMK1 signaling pathway, thus the development of gene therapy for osteosarcoma targeting LIMK1 is warranted.

Regulation of cofilin activity by CaMKII and calcineurin.

Cofilin promotes actin filament turnover by severing and depolymerizing actin filaments. Cofilin is inactivated by phosphorylation on Ser-3 by LIM-kinase1 (LIMK1) and is activated when protein phosphatase Slingshot-1L (SSH1L) dephosphorylates this residue. The authors have shown that Ca-induced cofilin dephosphorylation is mediated by calcineurin (Cn)-dependent activation of SSH1L. In this study, Ca/calmodulin-dependent protein kinase II (CaMKII) is shown to negatively regulate SSH1L activity and bind to SSH1L in a complex with 14-3-3. Phosphorylation of LIMK1 by CaMKII and its subsequent activation regulates the subcellular localization of SSH1L. Based on these findings, the authors suggest that CaMKII and Cn provide a switch-like mechanism that controls Ca-dependent LIMK1, SSH1L and cofilin activation, and subsequently actin cytoskeletal reorganization.

Overexpression of LIMK1 promotes migration ability of multidrug-resistant osteosarcoma cells.

Multidrug resistance (MDR) to chemotherapy is a major obstacle in the treatment of cancer and the resistance process is multifactorial. Studies on multidrug resistance mechanisms relied on the availability of cancer multidrug resistance cell lines that have been established. In this study we successfully established a multidrug resistance cell line MG63/VCR derived from human osteosarcoma cell line MG63 based on the induction by vincristine. MG63/VCR cells exhibited high resistance to vincristine and other anticancer drugs, accompanied by upregulated expression of MDR-associated genes MDR1, MRP1, and Bcl-2. Notably, we found that MG63/VCR cells exhibited higher migration ability compared to parental MG63 cells. Moreover, we demonstrated that LIMK1, a key regulator of actin cytoskeleton, was overexpressed at both mRNA and protein levels in MG63/VCR cells and the higher LIMK1 protein level was correlated with higher level of phosphorylated cofilin. In addition, knockdown of LIMK1 abolished the higher migration ability of MG63/ VCR cells. These results suggest that LIMK1 overexpression contributes to the invasion and metastasis of drug-resistant osteosarcoma and reveal LIMK as a novel therapeutic target for drug resistant osteosarcoma.