Injectable thermosensitive chitosan/ß-glycerophosphate/collagen hydrogel maintains the plasticity of skeletal muscle satellite cells and supports their in vivo viability.

A cell carrier plays an important role in the maintenance, growth and engraftment of specific cells aimed for defined therapeutic uses in many tissue engineering strategies. A suitable microenvironment for the cells allows for the maximum efficacy of the hybrid device. We have prepared an injectable thermosensitive chitosan/ß-glycerophosphate/collagen (C/GP/Co) gel and investigated its potential application as a support for the culture of skeletal muscle satellite cells (SMSCs). A cell viability assay was used to evaluate the in vitro cytocompatibility of the gel. Cell growth was assessed by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and histological analysis. The influence of the C/GP/Co gel on the plasticity of SMSCs seeded at the surface of the gel was assessed by induction of the myogenic, osteogenic and adipogenic differentiation. C/GP/Co gel provided the appropriate environment for the culture of SMSCs in vitro. In addition, the C/GP/Co gel supported SMSC plasticity. In vivo testing of the SMSC-seeded gel was investigated by subcutaneous injection into the dorsum of nude mice. Cell viability was assessed both by in vivo imaging and histological examination of the explants. In conclusion, C/GP/Co hydrogel is a cytocompatible carrier for the in vivo delivery of SMSCs and supportive for SMSC plasticity. Thus, this gel has potential applications in tissue engineering and regenerative medicine.

[Effects of injectable chitosan/ß-glycerol phosphate disodium/collagen scaffold on the growth and differentiation of myoblasts].

OBJECTIVE: To prepare injectable chitosan/ß-glycerol phosphate disodium/collagen scaffold and observe its effects upon the growth and differentiation of myoblasts. METHODS: After the preparations, 2 wt% chitosan (C) solution, 50 wt% ß-glycerol phosphate disodium (GP) solution and 2 mg/ml collagen (Co) solution were mixed on ice according to a volume ratio of 5:1:6 to yield a thermosensitive injectable scaffold. To assess the cytotoxicity of scaffold, the extraction fluids of different concentrations were added into the myoblast culture. Then relative growth rate (RGR) was calculated. The growth and differentiation state of myoblasts in routine culture or gel-coated plates were compared. Myoblasts were encapsulated in C/GP/Co solution before gelation to perform a 3-dimensional culture and then observed dynamically. RESULTS: No cytotoxicity was demonstrated. No significant difference of proliferation index was demonstrated (P > 0.05) but fusion index and size of myotube increased significantly (P < 0.05). Thriving viability and proliferation were verified by the observations of laser confocal scanning microscope and scanning electron microscope. CONCLUSION: C/GP/Co scaffold is a promising carrier for the culture and transplantation of myoblasts.

[Triple arthrodesis with osteotomy for the treatment of stage IIB and stage III adult-acquired flatfoot deformity].

OBJECTIVE: To analyze the clinical outcomes of triple arthrodesis with osteotomy in the treatment of Stage IIB and Stage III adult-acquired flatfoot. METHODS: The authors reviewed 10 cases of adult-acquired flatfoot, including 3 cases of stage IIB adult-acquired flatfoot and 7 cases of stage III adult-acquired flatfoot. They were treated by triple arthrodesis with osteotomy of subtalar joint (STJ), talonavicular joint (TNJ) and calcaneocuboid joint (CCJ). The combined medial and lateral incisions were used to obtain adequate exposure for CCJ, STJ and TNJ. Then the cartilages of CCJ, STJ and TNJ were completely denuded and osteotomies to restore their proper alignments. The optimal positioning of hindfoot could be achieved and fixed by Kirschner wires. Two cannulated screws of 7.3 mm were delivered through the plantar aspect of heel to fix STJ. And then two 4.5 mm cannulated screws individually fixed TNJ and CCJ distal to proximal. Clinical evaluations were based on the AOFAS ankle-hindfoot scale and subjective assessments of pains, function, cosmesis and overall satisfaction. Radiographic evaluations included measurements of anterior-posterior talo-first metatarsal angle, lateral talocalcaneal angle, lateral talo-first metatarsal angle and an assessment of time to union for all arthrodeses. RESULTS: All patients were followed-up with a mean time of 13.2 (6 - 21) months. The average AOFAS ankle-hindfoot scale improved from 39.4 ± 4.4 preoperatively to 83.7 ± 2.6 postoperatively (P < 0.01). And the patients experienced subjective improvements in pain, function and cosmesis. Overall, all patients were satisfied. Radiographically, the rate of bone healing was 100%. The anterior-posterior talo-first metatarsal angle, lateral talocalcaneal angle and lateral talo-first metatarsal angle statistically improved. No complication, such as infection and un-union, was reported. CONCLUSION: Triple arthrodesis with osteotomy is an effective procedure for the treatment of stage IIB and III adult-acquired flatfoot deformity. It may relieve pains, correct structural deformities and obtain excellent clinical outcomes.

[Medial displacement calcaneal osteotomy with mini-incision for the treatment of acquired flexible flatfoot caused by posterior tibial tendon dysfunction].

OBJECTIVE: To investigate the clinical outcomes of medial displacement calcaneal osteotomy with mini-incision for the treatment of acquired flexible flatfoot caused by posterior tibial tendon dysfunction. METHODS: From 2005 to 2009, 10 patients (13 feet) of acquired flexible flatfoot with obvious heel valgus underwent medial displacement calcaneal osteotomy with mini-incision. The lateral skin incision of 3.0 - 4.5cm was made to explore the lateral calcaneal wall. Calcaneal osteotomy was performed from inferior and lateral to superior and medial, perpendicular to the longitudinal axis of calcaneal body. The distal segment was displaced medially for 1/3-1/2 width of calcaneal body and fixed by two parallel cannulated screws. All patients were evaluated at 6 weeks, 3 months, 6 months, 12 months and every 6 months pre- and post-operatively by clinical examinations and radiological studies. All patients were physically examined with an extended protocol of questionnaires and the AOFAS Ankle & Hindfoot Scales. The lateral view of full foot allowed an assessment of bone healing, calcaneus inclination angle (CI), talocalcaneal angle (TC) and talar first metatarsal angle (TMT). The AP view of full foot allows assessment of TC and TMT. The heel varus/valgus alignment could be evaluated on the axial radiographs of hindfoot. RESULTS: With a mean postoperative follow-up period of 20.3 months (range 7 - 55 Ms), all patients had bone union as confirmed by clinical examination and radiology. The AOFAS rating scale improved from a pre-operative mean of 50.3 to a mean of 80.2 at 6 months and a mean of 84.2 at last follow-up, without any complication of infection, nerve injure and so on. All radiographic parameters were statistically significant (P < 0.001), including CI, TC and TMT on the lateral view and TC and TMT on the AP view. The heel varus/valgus was corrected on the axial view. CONCLUSION: The medial displacement calcaneal osteotomy with mini-incision is a recommended procedure for the treatment of acquired flexible flatfoot with excellent clinical outcomes, correction of deformity and fewer complications.

Application of New Allogeneic Lumbar Fusion Cage (Biocage) in Single-Segment Lumbar Degenerative Disease: A Prospective Controlled Study with Follow-Up for ≥2 Years.

OBJECTIVE: We evaluated the clinical efficacy of the Biocage in lumbar fusion surgery and its safety and effectiveness. METHODS: A total of 431 patients with single-segment lumbar degenerative disease diagnosed from January 2013 to December 2016 were considered for the present prospective, nonrandomized, and controlled study; 52 patient met the exclusion criteria and were excluded. The patients were divided into 2 groups according to their cage choice: Biocage (n = 206) and polyether ether ketone (PEEK) cage (n = 173). The patients were followed up for 24-48 months (average, 32). The operative time, blood loss, hospitalization duration, mean intervertebral fusion segment height, height of intervertebral foramen, fusion time, fusion rate, internal fixation failure rate, visual analog scale score, and Oswestry disability index were compared between the 2 groups. RESULTS: All the patients underwent surgery successfully. No significant differences were found in gender, age, clinical diagnosis, lesion segment, operative time, blood loss, visual analog scale score, or Oswestry disability index between the 2 groups. No significant differences were found in the fusion rate; however, the Biocage group had a greater fusion rate and shorter fusion time than the PEEK group. During follow-up, the mean intervertebral height recovered significantly in the Biocage group compared with the PPEK group (P < 0.05). The height of the intervertebral foramen was significantly different between the 2 groups, and recovery was better in the Biocage group (P < 0.05). The Cobb angle of fusion segment in both groups improved significantly postoperatively compared with preoperatively (P < 0.05). The improvement in Cobb angle was significantly different between the 2 groups (P < 0.05). CONCLUSIONS: The Biocage has excellent clinical efficacy in the treatment of lumbar degenerative disease. Although the Biocage achieved good therapeutic effects, it did not show obvious advantages compared with the PEEK cage. Therefore, the Biocage can only be used as a choice of bone graft materials for lumbar fusion surgery and should not completely replace the PEEK cage.

Pitavastatin attenuates monocyte activation in response to orthopedic implant-derived wear particles by suppressing the NF-κB signaling pathway.

Aseptic loosening secondary to particle­induced periprosthetic osteolysis is considered to be the primary cause of long­term implant failure in orthopedic surgery. Implant­derived wear particles activate and recruit macrophages and osteoclasts, which cause a persistent inflammatory response with bone destruction that is followed by a loosening of the implant. Thus, strategies for inhibiting macrophage and osteoclast function may provide a therapeutic benefit for preventing aseptic loosening. The aim of the present study was to determine the effects of pitavastatin on the activation and cytokine response of polymethyl methacrylate (PMMA) particle­induced monocytes. Peripheral blood monocytes were obtained and treated with PMMA and pitavastatin. ELISA demonstrated that pitavastatin inhibited mRNA and protein expression of interleukin (IL)­1ß, IL­6 and tumor necrosis factor­α. Western blot analysis and immunofluorescence staining demonstrated that pitavastatin downregulated inhibitor of κB phosphorylation and degradation, and nuclear factor κ­light­chain­enhancer of activated B cells (NF­κB) p65 translocation. Together, these results indicate that pitavastatin may attenuate monocyte activation in response to orthopedic implant wear particles by suppression of the NF­κB signaling pathway.