An investigation of composition, morphology, mechanical properties, and microdamage accumulation of human type 2 diabetic bone.

This study investigates the biomechanics of type 2 diabetic bone fragility through a multiscale experimental strategy that considers structural, mechanical, and compositional components of ex vivo human trabecular and cortical bone. Human tissue samples were obtained from the femoral heads of patients undergoing total hip replacement. Mechanical testing was carried out on isolated trabecular cores using monotonic and cyclic compression loading and nanoindentation experiments, with bone microdamage analysed using micro-computed tomography (CT) imaging. Bone composition was evaluated using Raman spectroscopy, high-performance liquid chromatography, and fluorometric spectroscopy. It was found that human type 2 diabetic bone had altered mechanical, compositional, and morphological properties compared to non-type 2 diabetic bone. High-resolution micro-CT imaging showed that cores taken from the central trabecular region of the femoral head had higher bone mineral density (BMD), bone volume, trabecular thickness, and reduced trabecular separation. Type 2 diabetic bone also had enhanced macro-mechanical compressive properties under mechanical loading compared to non-diabetic controls, with significantly higher apparent modulus, yield stress, and pre-yield toughness evident, even when properties were normalised against the bone volume. Using nanoindentation, there were no significant differences in the tissue-level mechanical properties of cortical or trabecular bone in type 2 diabetic samples compared to controls. Through compositional analysis, higher levels of furosine were found in type 2 diabetic trabecular bone, and an increase in both furosine and carboxymethyl-lysine (an advanced glycation end-product) was found in cortical bone. Raman spectroscopy showed that type 2 diabetic bone had a higher mineral-to-matrix ratio, carbonate substitution, and reduced crystallinity compared to the controls. Together, this study shows that type 2 diabetes leads to distinct changes in both organic and mineral phases of the bone tissue matrix, but these changes did not coincide with any reduction in the micro- or macro-mechanical properties of the tissue under monotonic or cyclic loading.

Bilateral first metatarsophalangeal joint arthrodesis: An investigation of functional, surgical and radiological outcomes.

BACKGROUND: First metatarsophalangeal joint (MTPJ) arthrodesis is a commonly utilised procedure. In this study, the authors aim to explore functional outcomes of patients undergoing nonsynchronous bilateral first MTPJ arthrodesis under the care of a single surgeon using a compression screw/locking plate construct. METHODS: This is a prospectively collected, retrospectively analysed case series of fifty five patients who underwent bilateral nonsynchronous first MTPJ arthrodesis. Clinical and radiological outcomes were assessed preoperatively and at a minimum of two years postoperatively. Clinical outcomes were assessed using the Foot and Ankle Outcome Score (FAOS), the Self-Reported Foot and Ankle Score (SEFAS) and the Sports Questionnaire version 1 (SQ). Postoperative radiographs were used to assess evidence of union and compare both hallux valgus and intermetatarsal angles. Removal of hardware, revision surgery and correction of deformities were also recorded. RESULTS: Fifty five patients were included in the study. There was statistically significant improvements in all five facets of the FAOS (p value < 0.05). The mean postoperative SEFAS was 45.1. In total, patients participated in thirteen different sporting activities. This represented 92 patient specific activities preoperatively and 104 postoperatively. The most common activities were walking, cycling and swimming. Overall, 94.5% (N = 52) of the cohort were satisfied with their return to sport while 98.2% (N = 54) would recommend bilateral first MTPJ arthrodesis. Mean reductions in hallux valgus angles and intermetatarsal angles were noted at 18.87 and 4.69 degrees respectively. There was one non-union in the cohort which required revision surgery. One patient required removal of hardware. CONCLUSIONS: Bilateral first MTPJ arthrodesis is a safe and effective surgical option for patients with bilateral first MTPJ pathology. It has a high union rate, low complication rate and significantly improves clinical outcomes and allows patients reliably return to physical activities.

Outcomes following tibiotalocalcaneal arthrodesis using a solid posterior offset intramedullary nail in 44 patients with a minimum 30-month follow-up.

BACKGROUND: Tibiotalocalcaneal arthrodesis is frequently performed by foot and ankle surgeons in the management of complex ankle and hindfoot pathology. In this study, the authors describe the clinical and radiological outcomes of tibiotalocalcaneal arthrodesis using a solid posterior offset hindfoot arthrodesis nail. METHODS: Forty-four consecutive patients underwent tibiotalocalcaneal arthrodesis by a single surgeon operating in two centers. Clinical and radiological outcomes were assessed preoperatively and at 6-month, 12-month and final follow-up (mean 47 months). Clinical outcomes were assessed with VAS, AOFAS and MOXFQ scores. Serial radiographs were used to assess union at each follow-up visit. RESULTS: Forty-four patients attended 12-month and final follow-up (mean 47 months). A total of 44 (100%) ankle joints and 44 (100%) subtalar joints were completely united at 12-month follow-up. The VAS score improved significantly from a mean of 6.5 preoperatively to a mean of 0.98 at final follow-up (P = <0.0001). AOFAS score improved significantly from a mean of 36.4 preoperatively to a mean of 73 at final follow-up (P = <0.0001). MOXFQ score improved significantly from a mean of 44.5 preoperatively to a mean of 12.7 at final follow-up (P = <0.0001). The mean change in frontal plane alignment was 5.7 degrees (P = 0.005). A total of 6 patients (13.6%) had an adverse event during the course of the study. CONCLUSIONS: Tibiotalocalcaneal arthrodesis with a solid posterior offset hindfoot arthrodesis nail is a safe and effective surgical option for patients with severe ankle and hindfoot pathology. It has a high union rate, low complication rate and significantly improves clinical outcomes.

Macromolecular crowding in human tenocyte and skin fibroblast cultures: A comparative analysis.

Although human tenocytes and dermal fibroblasts have shown promise in tendon engineering, no tissue engineered medicine has been developed due to the prolonged ex vivo time required to develop an implantable device. Considering that macromolecular crowding has the potential to substantially accelerate the development of functional tissue facsimiles, herein we compared human tenocyte and dermal fibroblast behaviour under standard and macromolecular crowding conditions to inform future studies in tendon engineering. Basic cell function analysis made apparent the innocuousness of macromolecular crowding for both cell types. Gene expression analysis of the without macromolecular crowding groups revealed expression of tendon related molecules in human dermal fibroblasts and tenocytes. Protein electrophoresis and immunocytochemistry analyses showed significantly increased and similar deposition of collagen fibres by macromolecular crowding in the two cell types. Proteomics analysis demonstrated great similarities between human tenocyte and dermal fibroblast cultures, as well as the induction of haemostatic, anti-microbial and tissue-protective proteins by macromolecular crowding in both cell populations. Collectively, these data rationalise the use of either human dermal fibroblasts or tenocytes in combination with macromolecular crowding in tendon engineering.

The Use of Dorsal Bridge Plate Fixation in the Operative Management of Lisfranc Injuries - A Retrospective Cohort Study at Medium Term Follow-Up.

INTRODUCTION: Traditionally, early surgical management of Lisfranc injuries with transarticular screws (TAS) was deemed to be the optimal treatment. However, concerns of potential iatrogenic articular cartilage disruption has led to discrepancies in opinion amongst surgeons, with many surgeons now utilizing dorsal bridge plates (DBP) for ORIF of Lisfranc injuries. OBJECTIVES: This study sought to investigate the clinical outcomes at medium-term follow-up of consecutive patients in our institution who underwent ORIF with DBP for Lisfranc injuries. METHODS: All consecutive patients who underwent ORIF with DBPs for Lisfranc injuries were identified. Outcomes of interest included; visual analogue scale (VAS), functional foot index (FFI), American Orthopaedic Foot & Ankle Surgeons (AOFAS) hindfoot scores, and complications. RESULTS: Overall, 37 consecutive patients (24 males) with a mean age of 34.8 ± 13.0 years underwent ORIF with DBPs for lisfranc injuries. After a mean 48.3 ± 28.7 months, the mean reported AOFAS and FFI scores were 77.4 ± 23.8 and 31.9 ± 32.7 respectively, with satisfactory reported pain scores as measured by VAS post-operatively at rest and whilst walking (2.2 ± 2.5 and 3.1 ± 2.6 respectively). The reported satisfaction rate was 86.5% (32/37). Overall, 25 patients (67.6%) had subsequent removal of metal or were listed for same, 88% (22/25) of whom did so electively in the absence of broken screws or infection. CONCLUSION: This study found that the use of Dorsal Bridge Plates for Open Reduction and Internal Fixation of Lisfranc Injuries resulted in satisfactory functional outcomes, high rates of patient-reported satisfaction and a low complication rate at medium-term follow-up. LEVEL OF EVIDENCE: Level IV; Retrospective Series of Consecutive Patients.

Girdlestone resection arthroplasty of the hip (GRA): a case series-outdated procedure or acceptable outcome?

Despite considerable legacy issues, Girdlestone's resection arthroplasty (GRA) remains a valuable tool in the armoury of the arthroplasty surgeon. When reserved for massive lysis in the context of extensive medical co-morbidities which preclude staged or significant surgical interventions, and/or the presence of pelvic discontinuity, GRA as a salvage procedure can have satisfactory outcomes. These outcomes include infection control, pain control and post-op function. We describe a case series of 13 cases of GRA and comment of the indications, peri, and post-operative outcomes.

A Rare Case of Naviculo-medial Cuneiform Coalition Treated with Naviculo-medial Cuneiform Arthrodesis: A Case Report.

CASE: A 19-year-old woman developed spontaneous onset of right midfoot pain in the absence of trauma. Conservative management including orthotics and steroid injection reduced, but did not resolve, pain. Weight-bearing x-ray and CT confirmed naviculo-medial cuneiform coalition. After failure of conservative treatment, the patient elected to undergo right naviculo-medial cuneiform arthrodesis and returned to normal activity without pain postoperatively and at 4-year follow-up. CONCLUSION: Naviculo-medial cuneiform coalition is a rare source of midfoot pain, but should be considered as a differential diagnosis. This case suggests that naviculo-medial cuneiform arthrodesis can successfully resolve symptoms if conservative measures fail.

Improving Acute Orthopaedic Admission Note Documentation Standards at a Tertiary Centre Through Proforma Introduction: A Quality Improvement Initiative.

Background Clear, accurate written documentation plays an important role in the handover of medical information, helping to improve care efficiency and avoid medical errors. Both HSE and the Irish National Orthopaedic Models of Care guidelines include key documentation standards for admission notes. Standardised medical admission proforma can help improve documentation standards, but their usage across Irish orthopaedic units is limited to three centres. We evaluated whether an admission proforma improved the documentation standards of acute orthopaedic trauma admission notes within our regional trauma unit. Methods Cycle 1 consisted of a retrospective review of 50 consecutive acute orthopaedic trauma admissions. Exclusion criteria included planned admissions, age <16 years, spinal or pelvic trauma, and 'hip' fractures for whom an existing proforma was in use. Cycle 2 consisted of a prospective review of 50 consecutive acute trauma admissions using the new proforma. Each cycle was scored against a pre-determined checklist incorporating Irish Health Service Executive and Orthopaedic Models of Care documentation standards, with results collated and statistical analysis then performed using Fisher's exact test. Findings Significant improvements in admission note compliance with national documentation were observed. This encompassed multiple domains including clinical identification, e.g., consultant identification (78% to 100% p=0.0005), clinical history, time of injury (72% to 100% p=0.0001), medical history, smoking status (86% to 100% p=0.0001), and patient assessment, vital signs (28% to 70% p=0.0001). Conclusion Improvements in admission note compliance with national documentation standards followed the introduction of a standardised proforma. These findings may encourage the introduction of similar proforma in other units, with potential benefits in patient care.

Paediatric ankle cartilage lesions: Proceedings of the International Consensus Meeting on Cartilage Repair of the Ankle.

BACKGROUND: The evidence supporting best practice guidelines in the field of cartilage repair of the ankle are based on both low quality and low levels of evidence. Therefore, an international consensus group of experts was convened to collaboratively advance toward consensus opinions based on the best available evidence on key topics within cartilage repair of the ankle. The purpose of this article is to report the consensus statements on "Pediatric Ankle Cartilage Lesions" developed at the 2019 International Consensus Meeting on Cartilage Repair of the Ankle. METHODS: Forty-three international experts in cartilage repair of the ankle representing 20 countries convened to participate in a process based on the Delphi method of achieving consensus. Questions and statements were drafted within four working groups focusing on specific topics within cartilage repair of the ankle, after which a comprehensive literature review was performed and the available evidence for each statement was graded. Discussion and debate occurred in cases where statements were not agreed upon in unanimous fashion within the working groups. A final vote was then held, and the strength of consensus was characterised as follows: consensus: 51-74%; strong consensus: 75-99%; unanimous: 100%. RESULTS: A total of 12 statements on paediatric ankle cartilage lesions reached consensus during the 2019 International Consensus Meeting on Cartilage Repair of the Ankle. Five achieved unanimous support, and seven reached strong consensus (>75% agreement). All statements reached at least 84% agreement. CONCLUSIONS: This international consensus derived from leaders in the field will assist clinicians with the management of paediatric ankle cartilage lesions.

Terminology for osteochondral lesions of the ankle: proceedings of the International Consensus Meeting on Cartilage Repair of the Ankle.

BACKGROUND: The evidence supporting best practice guidelines in the field of cartilage repair of the ankle is based on both low quality and low levels of evidence. Therefore, an international consensus group of experts was convened to collaboratively advance toward consensus opinions based on the best available evidence on key topics within cartilage repair of the ankle. The purpose of this article is to report the consensus statements on "terminology for osteochondral lesions of the ankle" developed at the 2019 International Consensus Meeting on Cartilage Repair of the Ankle. METHODS: Forty-three international experts in cartilage repair of the ankle representing 20 countries were convened and participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted within four working groups focusing on specific topics within cartilage repair of the ankle, after which a comprehensive literature review was performed, and the available evidence for each statement was graded. Discussion and debate occurred in cases where statements were not agreed on in unanimous fashion within the working groups. A final vote was then held, and the strength of consensus was characterised as follows: consensus, 51%-74%; strong consensus, 75%-99%; unanimous, 100%. RESULTS: A total of 11 statements on terminology and classification reached consensus during the 2019 International Consensus Meeting on Cartilage Repair of the Ankle. Definitions are provided for osseous, chondral and osteochondral lesions, as well as bone marrow stimulation and injury chronicity, among others. An osteochondral lesion of the talus can be abbreviated as OLT. CONCLUSIONS: This international consensus derived from leaders in the field will assist clinicians with the appropriate terminology for osteochondral lesions of the ankle.

Tourniquet Use During Open Reduction and Internal Fixation of Ankle Fractures - A Systematic Review and Meta-Analysis.

The intra-operative use of tourniquet in open reduction and internal fixation (ORIF) of ankle fractures remains a topic of debate. The purpose of this study was to perform a systematic review and meta-analysis of randomized control trials (RCTs) comparing clinical outcomes of patients undergoing ankle ORIF with tourniquet use versus a control group where no tourniquet was used. A systematic review was performed with reference to Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines of the Pubmed, Scopus, Embase, and Cochrane Library databases. Studies were included if they were an RCT comparing tourniquet and no-tourniquet in ankle ORIF. Meta-analysis was performed using RevMan, and p-value <.05 was considered to be statistically significant. On completion of the literature search, a total of 4 RCTs including 350 ankles (52.6% males), with a mean age of 47.1 ± 5.7 years were included. There were 173 patients in the tourniquet group (T), versus 177 patients in the no tourniquet control group (NT), with nonsignificant differences between the groups for age, gender and body mass index demographics (all p > .05). There were significantly shorter duration of surgery, with significantly higher patient-reported rates of pain levels at day 2 postoperatively (both p < .001) in the T group. Additionally, there were significantly greater ranges of ankle motion at 6 weeks postoperatively (p = .03), with nonsignificant differences reported incidence of wound infections and deep vein thrombosis (p = .056 and p = .130 respectively) between the groups. In conclusion, current evidence suggests that although intraoperative tourniquet usage in cases of ankle ORIF results in significant reductions in duration of surgery, this may be at the expense of higher patient-reported pain scores and reduced range of motion postoperatively.

Osteochondral Lesions of the Tibial Plafond and Ankle Instability With Ankle Cartilage Lesions: Proceedings of the International Consensus Meeting on Cartilage Repair of the Ankle.

BACKGROUND: An international consensus group of experts was convened to collaboratively advance toward consensus opinions based on the best available evidence on key topics within cartilage repair of the ankle. The purpose of this article is to present the consensus statements on osteochondral lesions of the tibial plafond (OLTP) and on ankle instability with ankle cartilage lesions developed at the 2019 International Consensus Meeting on Cartilage Repair of the Ankle. METHODS: Forty-three experts in cartilage repair of the ankle were convened and participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted within 4 working groups focusing on specific topics within cartilage repair of the ankle, after which a comprehensive literature review was performed and the available evidence for each statement was graded. Discussion and debate occurred in cases where statements were not agreed on in unanimous fashion within the working groups. A final vote was then held. RESULTS: A total of 11 statements on OLTP reached consensus. Four achieved unanimous support and 7 reached strong consensus (greater than 75% agreement). A total of 8 statements on ankle instability with ankle cartilage lesions reached consensus during the 2019 International Consensus Meeting on Cartilage Repair of the Ankle. One achieved unanimous support, and seven reached strong consensus (greater than 75% agreement). CONCLUSION: These consensus statements may assist clinicians in the management of these difficult clinical pathologies. LEVEL OF EVIDENCE: Level V, mechanism-based reasoning.

Functional Capabilities After First Metatarsal Phalangeal Joint Arthrodesis Using a Locking Plate and Compression Screw Construct.

Arthrodesis of the first metatarsal phalangeal joint (MTPJ) is a widely utilized surgical procedure for a wide array of metatarsal pathologies. This study aims to explore the functional limitations following first MTPJ arthrodesis, overall satisfaction and patient's abilities to achieve activities of daily living (ADL). This prospective cohort study assessed functional limitations as well as footwear and lifestyle restrictions using several questionnaires. One hundred and three participants who had a first MTPJ arthrodesis under the care of a single surgeon were recruited. Pre- and postoperative patient-reported outcome measures were recorded. The American Orthopaedic Foot and Ankle Score (AOFAS) and the Manchester-Oxford Foot Questionnaire were also used to further examine functional status. Hallux valgus angle (HVA) and intermetatarsal angle (IMA) were compared using preoperative and postoperative weightbearing radiographs and successful fusion was recorded. Complications were documented and are discussed in detail. The duration of follow-up was more than 12 months. There was one nonunion in the cohort while 2 patients experienced delay to fusion. Approximately 97% of patients were very satisfied with the procedure and their ability to achieve ADLs post operatively. A further 82.5% of patients were able to return to wearing nonadaptive footwear. The mean reduction in HVA and IMA was 21.78° and 6.84°, respectively. This study demonstrates the safe and successful use of a compression screw/locking plate construct for arthrodesis of the first MTPJ. Furthermore, the study provides clear evidence of high levels of functionality after the procedure with statistically significant differences (p value <.05) in all 4 facets of the AOFAS questionnaire as well as several notable differences in activity levels and footwear restrictions pre and postoperatively.

A Technique to Correct Troughing in a Z-Osteotomy for Hallux Valgus Correction.

A Z-osteotomy is a commonly performed procedure to correct mild-moderate hallux valgus. It is an effective procedure with high patient satisfaction rates. However, it is not without its challenges. One of the most frequently encountered issues during a Z-osteotomy is troughing of the first metatarsal. We present a simple surgical technique to correct troughing if it is encountered without the need for additional soft tissue or bony procedures.

Superficial peroneal nerve neuroma after syndesmotic stabilisation surgery.

The ankle is a region crowded with multiple neurovascular and musculotendinous structures. We describe a case of a rare neurological complication following ankle surgery.

Perioperative Mortality and Periprosthetic Fracture: A Single-Center Experience of 857 Uncemented Hemiarthroplasties for Displaced Femoral Neck Fractures.

BACKGROUND: Uncemented hemiarthroplasty (UHA) for displaced femoral neck fracture (FNF) is favored by some surgeons because of the reduced rate of perioperative mortality and operative time. However higher rates of intraoperative and postoperative periprosthetic fractures (PPFs) have been reported. The aim of the study was to review day-0, day-1, day-2, day-30, and one-year mortality as well as intraoperative and postoperative PPF after UHA for displaced FNF and compare this with cemented hemiarthroplasties (CHAs) performed. Secondary objectives were to assess whether femoral stem geometry and alignment were associated with PPF in UHA. METHODS: A retrospective observational study was conducted of patients treated with a hemiarthroplasty for a displaced FNF over an eleven-year period. Radiographic analysis was conducted of femoral geometry and stem alignment. RESULTS: Over the 11-year study period, 857 UHAs and 247 CHAs were performed. There were no on-table, day-0, day-1, or day-2 deaths in UHA. Intraoperative PPF occurred in 3.6% UHA and 2% CHA and postoperative PPF in 2.4% UHA and 4.8% CHA. Intraoperative PPF was not associated with increased mortality (P = .15), postoperative PPF, or all-cause revision in UHA. Valgus stem alignment was a risk factor for a postoperative PPF and additional surgery in UHA (P = .004). CONCLUSION: UHA was associated with no perioperative deaths and a 30-day mortality rate of 5% in this series. It can be considered in patients with multiple medical comorbidities. Careful surgical planning and technique is important to optimize stem alignment particularly in Dorr C type femurs.

The Operative Treatment of Ankle Fractures: A 10-Year Retrospective Study of 1529 Patients.

Ankle fractures are the second most common fracture of the lower limb and account for nearly 10% of all fractures. They range from simple to complex injuries and approximately 40% require surgical intervention. The aim of our study was to provide an up-to-date reference of the epidemiology, fracture, and fixation characteristics of operatively treated ankle fractures. We also sought to determine the number of patients undergoing further surgery through revision, implant removal, or ankle fusion. A retrospective observational study was conducted of 1529 consecutive patients that underwent operative intervention for an unstable ankle fracture between 2007 and 2017. Fractures of the distal tibia and pilon injuries were excluded. The mean age of patients was 41.8 years with 50.7% male. Unimalleolar fixation was performed in 60.1%, while bimalleolar and trimalleolar fixation was performed in 31.2% and 5%, respectively. Isolated syndesmotic fixation was performed in 3.8%. A posterior malleolus fracture was present in 28.6%, of which 31.6% underwent fixation. A further procedure was performed in 234 (15.3%) patients. Revision open reduction internal fixation was required in 1.4% and 0.8% underwent future ankle fusion. Treatment of ankle fractures makes up a sizeable part of orthopedic trauma practice with more than 1 in 7 patients requiring a second procedure. More complex fractures were predominantly seen in older females, while patients who suffered trimalleolar fractures have an increased likelihood of requiring future ankle fusion or revision. Despite this the rate of ankle fusion was <1%.

Osteoporotic Vertebral Fractures are Common in Hip Fracture Patients and are Under-recognized.

INTRODUCTION: The vertebrae are the most common site for osteoporotic fracture. While they can result in disability and increased mortality, only one-third present clinically. People with multiple fractures are at greater risk of future fractures. Most hip fracture patients are neither diagnosed nor treated for their underlying osteoporosis. Computed tomography (CT) studies are often performed on hospitalised patients, can be used to diagnose osteoporosis and are gaining popularity for opportunistic osteoporosis screening by measuring BMD and other bone strength indices. The aim of this study was to assess the prevalence of vertebral fractures on CT pulmonary angiograms (CTPA) in a cohort of hip fracture patients and whether this increased their diagnosis and treatment rates. METHODS: We retrospectively identified all hip fractures admitted to our institution between 2010 and 2017 to identify those who underwent CTPA scans. An independent, blinded consultant musculoskeletal radiologist reviewed the images for vertebral fractures and quantified severity using Genant criteria. Results were compared to the original radiology report, discharge diagnoses and treatment rates for osteoporosis. RESULTS: Eleven percent (225/2122) of patients had CTPA images available. Seventy percent (158) were female with a mean age of 78 years (SD: 11). The median length of stay for all patients was 16 days (1-301). Forty percent (90) of patients had at least one vertebral fracture present and 20% (46) had more than one fracture. Only one in 5 radiology reports noted the fractures. 24% of subjects had osteoporosis treatment recorded at hospital discharge and there was no difference between those with vertebral fractures to those without. CONCLUSION: Many hip fracture patients have undiagnosed spine fractures. A screening strategy which evaluates CT scans for fractures has potential to increase diagnosis and treatment rates of osteoporosis. However, more work is needed to increase awareness.

Growth factor and macromolecular crowding supplementation in human tenocyte culture.

Cell-assembled tissue engineering strategies hold great potential in regenerative medicine, as three-dimensional tissue-like modules can be produced, even from a patient's own cells. However, the development of such implantable devices requires prolonged in vitro culture time, which is associated with cell phenotypic drift. Considering that the cells in vivo are subjected to numerous stimuli, multifactorial approaches are continuously gaining pace towards controlling cell fate during in vitro expansion. Herein, we assessed the synergistic effect of simultaneous and serial growth factor supplementation (insulin growth factor-1, platelet-derived growth factor ßß, growth differentiation factor 5 and transforming growth factor ß3) to macromolecular crowding (carrageenan) in human tenocyte function; collagen synthesis and deposition; and gene expression. TGFß3 supplementation (without/with carrageenan) induced the highest (among all groups) DNA content. In all cases, tenocyte proliferation was significantly increased as a function of time in culture, whilst metabolic activity was not affected. Carrageenan supplementation induced significantly higher collagen deposition than groups without carrageenan (without/with any growth factor). Of all the growth factors used, TGFß3 induced the highest collagen deposition when used together with carrageenan in both simultaneous and serial fashion. At day 13, gene expression analysis revealed that TGFß3 in serial supplementation to carrageenan upregulated the most and downregulated the least collagen- and tendon- related genes and upregulated the least and downregulated the most osteo-, chondro-, fibrosis- and adipose- related trans-differentiation genes. Collectively, these data clearly advocate the beneficial effects of multifactorial approaches (in this case, growth factor and macromolecular crowding supplementation) in the development of functional cell-assembled tissue surrogates.

The effect of aligned electrospun fibers and macromolecular crowding in tenocyte culture.

Tendon injuries continuously rise, and regeneration is not only slow, but also limited due to the poor endogenous healing ability of the tendon tissue. Tissue grafts constitute the clinical gold standard treatment for severe injuries, but inherent limitations drive the field toward tissue engineering approaches to create suitable tissue constructs. Recapitulation of the native microenvironment represent a key challenge for the development of tendon tissue equivalents in vitro that can be further utilized as implantable devices. Methods to maintain cellular phenotype and to enhance extracellular matrix deposition for accelerated development of tissue-like modulus should be developed. Herein, we assessed the combining effect of surface topography and macromolecular crowding in human tenocyte culture. Our data demonstrated that bidirectionally aligned electrospun fibers induce physiological cell growth, while macromolecular crowding enhanced and accelerated tissue-specific extracellular matrix deposition. Collectively, these data advocate the use of multifactorial approaches for the accelerated development of functional tissue-like surrogates in vitro.