Publications by authors named "Martyn Snow"

48 Publications

Does statin-treated hyperlipidemia affect rotator cuff healing or muscle fatty infiltration after rotator cuff repair?

J Shoulder Elbow Surg 2021 Jun 9. Epub 2021 Jun 9.

Department of Arthroscopy, Royal Orthopaedic Hospital NHS Foundation Trust, Birmingham, UK.

Background: Hyperlipidemia is linked to poor tendon-to-bone healing and progression of fatty infiltration after rotator cuff repair. Statins effectively treat hyperlipidemia, but it is unknown if they have any potential detrimental effects following rotator cuff repair. The aim of this study was to evaluate the effect of statins on rotator cuff healing and fatty infiltration following repair.

Methods: A total of 77 patients undergoing arthroscopic rotator cuff repair were recruited prospectively, 38 patients who were prescribed a statin for hyperlipidemia (statin group) and 39 patients who were not taking a statin (control group). Patients who did not have both preoperative and 1-year postoperative magnetic resonance imaging (MRI) scans were excluded from the study. Patient-reported outcome measures, namely the Western Ontario Rotator Cuff (WORC) index, Constant-Murley score, American Shoulder and Elbow Surgeons (ASES) score, and Disabilities of the Arm, Shoulder and Hand (DASH) score, were collected preoperatively and at 1 year. Fatty infiltration was assessed on MRI according to the Goutallier grade preoperatively and at 12 months; rotator cuff healing was assessed at 12 months according to the Sugaya classification. Following propensity score weighting to adjust for baseline imbalances, 12-month outcomes were compared between the 2 groups.

Results: At 12 months, all patient-reported outcome measures had improved significantly compared with baseline (WORC score, 85.9 vs. 32.5, P < .001; ASES score, 87.3 vs. 37.5, P < .001; Constant-Murley score, 77 vs. 31, P < .001; and DASH score, 13.6 vs. 61.4, P < .001). There was no significant difference in postoperative scores in the statin group vs. the control group (WORC score, 84.9 vs. 89.6, P = .94; ASES score, 87.5 vs. 86.6, P = .40; Constant-Murley score, 77 vs. 81, P = .90; and DASH score, 14.4 vs. 11.4, P = .14), and for 3 of these scores, the 95% confidence intervals excluded a clinically meaningful difference. Similarly, rotator cuff healing at 12 months and Goutallier fatty infiltration grades were comparable between the 2 groups. Retears were seen in 6 patients (15.8%) in the statin group and 8 (20.5%) in the control group. Progression of fatty infiltration was seen in 4 patients (10.5%) in the statin and 4 (10.3%) in the control group. Statin use did not demonstrate a significant association with either retear risk (P = .41) or progression of fatty atrophy (P = .69).

Conclusion: Patient-reported outcomes, rotator cuff retear rate, and fatty infiltration on MRI at 12 months after rotator cuff repair in patients with hyperlipidemia treated with statins are similar to those in a control group.
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http://dx.doi.org/10.1016/j.jse.2021.05.014DOI Listing
June 2021

Use of biologics in rotator cuff disorders: Current concept review.

J Clin Orthop Trauma 2021 Aug 15;19:81-88. Epub 2021 May 15.

The Royal Orthopaedic Hospital, Birmingham, United Kingdom.

Poor tendon to bone healing following rotator cuff repair has led to the continued interest and investigation into biological augmentation. The biology of tendinopathy is not fully understood and consequently the availability of disease modifying therapeutic targets is limited. A ceiling of benefit has been reached by mechanical optimisation of rotator cuff repair and thus, in order to improve healing rates, a biological solution is required. This review focuses on the strategies to biologically augment rotator cuff disorders with an emphasis on rotator cuff repair. Leucocyte rich platelet rich plasma has been shown to improve healing rates without clinically relevant improvements in outcome scores. Similarly, improved healing rates have also been reported with bone marrow stimulation and in long-term follow-up with bone marrow concentrate. Extracellular matrix (ECM) and synthetic scaffolds can increase healing through mechanical and or biological augmentation. A potential third category of scaffold is bio-inductive and has no mechanical support. Studies involving various scaffolds have shown promising results for augmentation of large to massive tears and is likely to be most beneficial when tendon quality is poor, however level I evidence is limited.
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http://dx.doi.org/10.1016/j.jcot.2021.05.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8165426PMC
August 2021

Pro-angiogenic and osteogenic composite scaffolds of fibrin, alginate and calcium phosphate for bone tissue engineering.

J Tissue Eng 2021 Jan-Dec;12:20417314211005610. Epub 2021 Apr 6.

Regenerative Biomaterials Group, The RAFT Institute & The Griffin Institute, Northwick Park & Saint Mark's Hospital, London, UK.

Due to the limitations of bone autografts, we aimed to develop new composite biomaterials with pro-angiogenic and osteogenic properties to be used as scaffolds in bone tissue engineering applications. We used a porous, cross-linked and slowly biodegradable fibrin/alginate scaffold originally developed in our laboratory for wound healing, throughout which deposits of calcium phosphate (CaP) were evenly incorporated using an established biomimetic method. Material characterisation revealed the porous nature and confirmed the deposition of CaP precursor phases throughout the scaffolds. MC3T3-E1 cells adhered to the scaffolds, proliferated, migrated and differentiated down the osteogenic pathway during the culture period. Chick chorioallantoic membrane (CAM) assay results showed that the scaffolds were pro-angiogenic and biocompatible. The work presented here gave useful insights into the potential of these pro-angiogenic and osteogenic scaffolds for bone tissue engineering and merits further research in a pre-clinical model prior to its clinical translation.
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http://dx.doi.org/10.1177/20417314211005610DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8040555PMC
April 2021

Single-Stage Arthroscopic Cartilage Repair With Injectable Scaffold and BMAC.

Arthrosc Tech 2021 Mar 8;10(3):e751-e756. Epub 2021 Feb 8.

Department of Orthopaedic Surgery, Changi General Hospital, Singapore.

Injectable scaffold augmentation is a promising modality for single-stage cartilage repair. According to published studies, cartilage repair with scaffold augmentation has improved clinical outcomes, radiological fill, and histological repair compared with microfracture alone. Injectable scaffolds have the versatility to be used in large and irregularly shaped lesions. With correct preparation, they can be applied to lesions on the femoral condyle that may be vertical, or even inverted lesions such as those in the patella. They can be combined with bone marrow aspirate concentrate (BMAC) to provide mesenchymal stem cells (MSCs), thereby avoiding the need for microfracture. This protects the subchondral plate, preventing biomechanical alteration and potentially resulting in improved long-term outcomes. In this article, we demonstrate the utility of injectable scaffolds and their combination with BMAC.
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http://dx.doi.org/10.1016/j.eats.2020.10.065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7953231PMC
March 2021

Tibial Torsion and Patellofemoral Pain and Instability in the Adult Population: Current Concept Review.

Authors:
Martyn Snow

Curr Rev Musculoskelet Med 2021 Feb 8;14(1):67-75. Epub 2021 Jan 8.

The Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham, UK.

Purpose Of Review: Tibial torsion is a recognized cause of patellofemoral pain and instability in the paediatric population; however, it is commonly overlooked in the adult population. The aim of this review article is to summarize the current best evidence on tibial torsion for the adult orthopaedic surgeon.

Recent Findings: The true incidence of tibial torsion in the adult population is unknown, with significant geographical variations making assessment very difficult. CT currently remains the gold standard for quantitatively assessing the level of tibial torsion and allows assessment of any associated femoral and knee joint rotational anomalies. Surgical correction should only be considered after completion of a course of physiotherapy aimed at addressing the associated proximal and gluteal weakness. Tibial torsion greater than 30° is used as the main indicator for tibial de-rotation osteotomy by the majority of authors. In patients with associated abnormal femoral rotation, current evidence would suggest that a single-level correction of the tibia (if considered to be a dominant deformity) is sufficient in the majority of cases. Proximal de-rotational osteotomy has been more commonly reported in the adult population and confers the advantage of allowing simultaneous correction of patella alta or excessive tubercle lateralization. Previous surgery prior to de-rotational osteotomy is common; however, in patients with persistent symptoms surgical correction still provides significant benefit. Tibial torsion persists into adulthood and can play a significant role in patellofemoral pathology. A high index of suspicion is required in order to identify torsion clinically. Surgical correction is effective for both pain and instability, but results are inferior in patients with very high pain levels pre-surgery and multiple previous surgeries.
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http://dx.doi.org/10.1007/s12178-020-09688-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7930175PMC
February 2021

Combined bezafibrate, medroxyprogesterone acetate and valproic acid treatment inhibits osteosarcoma cell growth without adversely affecting normal mesenchymal stem cells.

Biosci Rep 2021 01;41(1)

University Centre Shrewsbury, Guildhall, Frankwell Quay, Shrewsbury SY3 8HQ, U.K.

Drug repurposing is a cost-effective means of targeting new therapies for cancer. We have examined the effects of the repurposed drugs, bezafibrate, medroxyprogesterone acetate and valproic acid on human osteosarcoma cells, i.e., SAOS2 and MG63 compared with their normal cell counterparts, i.e. mesenchymal stem/stromal cells (MSCs). Cell growth, viability and migration were measured by biochemical assay and live cell imaging, whilst levels of lipid-synthesising enzymes were measured by immunoblotting cell extracts. These drug treatments inhibited the growth and survival of SAOS2 and MG63 cells most effectively when used in combination (termed V-BAP). In contrast, V-BAP treated MSCs remained viable with only moderately reduced cell proliferation. V-BAP treatment also inhibited migratory cell phenotypes. MG63 and SAOS2 cells expressed much greater levels of fatty acid synthase and stearoyl CoA desaturase 1 than MSCs, but these elevated enzyme levels significantly decreased in the V-BAP treated osteosarcoma cells prior to cell death. Hence, we have identified a repurposed drug combination that selectively inhibits the growth and survival of human osteosarcoma cells in association with altered lipid metabolism without adversely affecting their non-transformed cell counterparts.
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http://dx.doi.org/10.1042/BSR20202505DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7786328PMC
January 2021

An In Vitro Comparison of the Neurotrophic and Angiogenic Activity of Human and Canine Adipose-Derived Mesenchymal Stem Cells (MSCs): Translating MSC-Based Therapies for Spinal Cord Injury.

Biomolecules 2020 09 9;10(9). Epub 2020 Sep 9.

Faculty of Medicine, Dentistry and Life Sciences, University of Chester, Parkgate Road, Chester, Cheshire CH1 4BJ, UK.

The majority of research into the effects of mesenchymal stem cell (MSC) transplants on spinal cord injury (SCI) is performed in rodent models, which may help inform on mechanisms of action, but does not represent the scale and wound heterogeneity seen in human SCI. In contrast, SCI in dogs occurs naturally, is more akin to human SCI, and can be used to help address important aspects of the development of human MSC-based therapies. To enable translation to the clinic and comparison across species, we have examined the paracrine, regenerative capacity of human and canine adipose-derived MSCs in vitro. MSCs were initially phenotyped according to tissue culture plastic adherence, cluster of differentiation (CD) immunoprofiling and tri-lineage differentiation potential. Conditioned medium (CM) from MSC cultures was then assessed for its neurotrophic and angiogenic activity using established cell-based assays. MSC CM significantly increased neuronal cell proliferation, neurite outgrowth, and βIII tubulin immunopositivity. In addition, MSC CM significantly increased endothelial cell migration, cell proliferation and the formation of tubule-like structures in Matrigel assays. There were no marked or significant differences in the capacity of human or canine MSC CM to stimulate neuronal cell or endothelial cell activity. Hence, this study supports the use of MSC transplants for canine SCI; furthermore, it increases understanding of how this may subsequently provide useful information and translate to MSC transplants for human SCI.
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http://dx.doi.org/10.3390/biom10091301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7563337PMC
September 2020

Single-Stage Autologous Chondrocyte-Based Treatment for the Repair of Knee Cartilage Lesions: Two-Year Follow-up of a Prospective Single-Arm Multicenter Study.

Am J Sports Med 2020 05 8;48(6):1327-1337. Epub 2020 Apr 8.

Antwerp Orthopedic Center, AZ Monica, Antwerp, Belgium.

Background: There is an unmet need for a single-stage cartilage repair treatment that is cost-effective and chondrocyte-based.

Purpose: To evaluate the safety and preliminary efficacy of autologous freshly isolated primary chondrocytes and bone marrow mononucleated cells (MNCs) seeded into a PolyActive scaffold in patients with symptomatic cartilage lesions of the knee.

Study Design: Case series; Level of evidence, 4.

Methods: A total of 40 patients with symptomatic knee cartilage lesions were treated with freshly isolated autologous chondrocytes combined with bone marrow MNCs delivered in a biodegradable load-bearing scaffold. The treatment requires only 1 surgical intervention and is potentially a cost-effective alternative to autologous chondrocyte implantation. The primary chondrocytes and bone marrow MNCs were isolated, washed, counted, mixed, and seeded into a load-bearing scaffold in the operating room. Patients were followed up at 3, 6, 12, 18, and 24 months. Primary endpoints were treatment-related adverse events up to 3 months, adverse implant effects between 3 and 24 months, and the implant success rate at 3 months as measured by lesion filling.

Results: Successful lesion filling (≥67% on magnetic resonance imaging) was found in 40 patients at 3 months and in 32 of the 32 patients analyzed at 24 months. Significant improvement over baseline was found for visual analog scale for pain from 3 months onward; Knee injury and Osteoarthritis Outcome Score (KOOS)-Pain and KOOS-Activities of Daily Living from 6 months onward; for KOOS-Symptoms and Stiffness, KOOS-Quality of Life and International Knee Documentation Committee from 12 months onward; and for KOOS-Sport and Recreation from 18 months onward. Hyaline-like repair tissue was found in 22 of 31 patients available for biopsy. Arthralgia and joint effusion were the most common adverse events. Scaffold delamination and adhesions led to removal of the implant in 2 patients.

Conclusion: The treatment of knee cartilage lesions with autologous primary chondrocytes and bone marrow MNCs, both isolated and seeded into a load-bearing PolyActive scaffold within a single surgical intervention, is safe and clinically effective. Good lesion fill and sustained clinically important and statistically significant improvement in all patient-reported outcome scores were found throughout the 24-month study. Hyaline-like cartilage was observed on biopsy specimen in at least 22 of the 40 patients.

Registration: NCT01041885 (ClinicalTrials.gov identifier).
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http://dx.doi.org/10.1177/0363546520912444DOI Listing
May 2020

Pre-screening the intrinsic angiogenic capacity of biomaterials in an optimised chorioallantoic membrane model.

J Tissue Eng 2020 Jan-Dec;11:2041731420901621. Epub 2020 Feb 4.

Regenerative Biomaterials Group, RAFT Institute, Mount Vernon Hospital, Northwood, UK.

Biomaterial development for clinical applications is currently on the rise. This necessitates adequate testing, where the structure and composition of biomaterials must be specifically tailored to withstand repair and regeneration responses for a successful clinical outcome. The chorioallantoic membrane of chicken embryos has been previously used to study angiogenesis, a prerequisite for most tissue repair and regeneration. In this study, we report an optimised method using a glass-cling film set-up that yields increased embryo survival rates and has an improved protocol for harvesting biomaterials. Furthermore, we used this method to examine the intrinsic angiogenic capacity of a variety of biomaterials categorised as natural, synthetic, natural/synthetic and natural/natural composites with varying porosities. We detected significant differences in biomaterials' angiogenesis with natural polymers and polymers with a high overall porosity showing a greater vascularisation compared to synthetic polymers. Therefore, our proposed chorioallantoic membrane method can be effectively used to pre-screen biomaterials intended for clinical application.
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http://dx.doi.org/10.1177/2041731420901621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7000866PMC
February 2020

The Effect of Delayed Injection of Leukocyte-Rich Platelet-Rich Plasma Following Rotator Cuff Repair on Patient Function: A Randomized Double-Blind Controlled Trial.

Arthroscopy 2020 03 27;36(3):648-657. Epub 2019 Nov 27.

Royal Orthopaedic Hospital NHS Foundation Trust, Northfield, United Kingdom.

Purpose: To investigate the effect of delayed application of leukocyte-rich platelet-rich plasma (PRP) on rotator cuff repair results as assessed by outcome scores and imaging at one year.

Methods: Patients with a symptomatic rotator cuff tear awaiting arthroscopic repair were approached to take part in the study. Final eligibility for the study was confirmed at the time of surgery. A total of 97 patients were randomized to an ultrasound guided injection of leukocyte-rich PRP or normal saline between 10 and 14 days postsurgery. A total of 87 patients completed clinical evaluation and underwent magnetic resonance imaging imaging at 1 year. Outcome scores included the American Shoulder and Elbow Score, Constant score, Western Ontario Rotator Cuff Index, and the Disabilities of the Arm, Shoulder and Hand Score. Structural integrity of the repair was assessed according to the Sugaya grading. Muscle fatty infiltration was assessed on magnetic resonance imaging using the Goutallier classification.

Results: At 1 year postsurgery, there was no significant difference between the treatment groups on any of the patient-reported outcome measures or Constant score. On postoperative imaging analysis, there was no difference in the retear rates (Sugaya 4 and 5) between the groups (21% in control group vs 15.3% in PRP group). Fatty infiltration on postoperative imaging was found to be significantly higher in the normal saline group compared with the PRP group (Kendall's tau-b P = .032).

Conclusions: The delayed application of PRP postrotator cuff repair did not improve function as measured by patient-reported outcome measures and Constant score at 1 year postoperatively.

Level Of Evidence: Level II, prospective randomized therapeutic trial.
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http://dx.doi.org/10.1016/j.arthro.2019.09.026DOI Listing
March 2020

Which factors affect the ability to kneel following total knee arthroplasty? An outpatient study of 100 postoperative knee replacements.

J Orthop Surg (Hong Kong) 2019 Sep-Dec;27(3):2309499019885510

Royal Orthopaedic Hospital, The Woodlands, Bristol Road South, Birmingham, UK.

Background: Kneeling is an important activity of daily living, holding social, religious and occupational value. Following total knee replacement (TKR), many patients report they are unable to kneel or have been advised not to kneel.

Methods: We observed 100 consecutive knee replacements in 79 patients attending outpatient clinic at a minimum 5 months post-TKR. The patients were asked to fill out a questionnaire detailing whether they were able to kneel prior to their knee replacement and whether they thought they were able to kneel since their knee replacement. The patients were then asked to kneel on a padded examination couch and then onto a pillow on the floor for 15 s. Degree of flexion achievable was also recorded.

Results: Of the knees with patella resurfacing, 78.6% were able to kneel compared to only 45.6% knees with native patellae. Two-tailed Fisher's exact test showed this difference to be statistically significant ( = 0.001). The analysis showed that those patients with an achievable flexion of angle of greater than 100° were significantly more likely to be able to kneel than those with a flexion angle of less than 100° ( = 0.0148). Comparing posterior cruciate ligament (PCL) retaining against PCL sacrificing implants, there was no statistically significant difference in kneeling ability ( = 0.541).

Conclusion: Kneeling remains an important function in patients undergoing TKR, with patella resurfacing significantly improving the likelihood of a patient being able to kneel.
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http://dx.doi.org/10.1177/2309499019885510DOI Listing
August 2020

CD271-selected mesenchymal stem cells from adipose tissue enhance cartilage repair and are less angiogenic than plastic adherent mesenchymal stem cells.

Sci Rep 2019 02 28;9(1):3194. Epub 2019 Feb 28.

Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK.

CD271 is a marker of bone marrow MSCs with enhanced differentiation capacity for bone or cartilage repair. However, the nature of CD271+ MSCs from adipose tissue (AT) is less well understood. Here, we investigated the differentiation, wound healing and angiogenic capacity of plastic adherent MSCs (PA MSCs) versus CD271+ MSCs from AT. There was no difference in the extent to which PA MSCs and CD271+ MSCs formed osteoblasts, adipocytes or chondrocytes in vitro. In contrast, CD271+ MSCs transplanted into athymic rats significantly enhanced osteochondral wound healing with reduced vascularisation in the repair tissue compared to PA MSCs and control animals; there was little histological evidence of mature articular cartilage formation in all animals. Conditioned medium from CD271+ MSC cultures was less angiogenic than PA MSC conditioned medium, and had little effect on endothelial cell migration or endothelial tubule formation in vitro. The low angiogenic activity of CD271+ MSCs and improved early stage tissue repair of osteochondral lesions when transplanted, along with a comparable differentiation capacity along mesenchymal lineages when induced, suggests that these selected cells are a better candidate than PA MSCs for the repair of cartilaginous tissue.
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http://dx.doi.org/10.1038/s41598-019-39715-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395721PMC
February 2019

An Study to Determine the Feasibility of Combining Bone Marrow Concentrate with BST-CarGel as a Treatment for Cartilage Repair.

Cartilage 2021 04 7;12(2):226-236. Epub 2018 Dec 7.

University of Birmingham, Birmingham, UK.

Objective: The study aims were to determine whether BST-CarGel, a chitosan scaffold for cartilage repair, can be mixed with bone marrow aspirate concentrate (BMAC) to create a cell seeded implant with comparative properties to standard BST-CarGel mixed with blood.

Design: Whole blood and bone marrow were harvested from 12 patients who underwent cartilage repair surgery using BMAC after informed consent. A validated testing model was used to assess the following 6 conditions: (1) BST-CarGel mixed with whole blood (CG-WB), (2) BST-CarGel mixed with bone marrow (CG-BM), (3) BST-CarGel mixed with bone marrow concentrate (CG-BMAC), (4) whole blood (WB), (5) bone marrow (BM), and (6) bone marrow concentrate and batroxobin (BMAC-BTX). Cell retention and viability within the BST-CarGel/BMAC clots were investigated.

Results: In our study, BM and BMAC (processed using the Harvest, SmartPrep2 system and reactivated with batroxibin) when combined with BST-CarGel produced a product that had similar clot contraction, macroscopic properties, and histological appearance to standard BSTCarGel mixed with blood. Mononucleated cells from the BMAC were retained within the scaffold and remained viable until clot dissolution .

Conclusions: By combining BST-CarGel with BMAC in the manner described, bone marrow-derived mononucleated cells can be retained within the chondral defect potentially negating the need for microfracture. Further work is required to confirm these potential benefits and determine if this combination will result in more durable cartilage repair and improved clinical outcomes.
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http://dx.doi.org/10.1177/1947603518812564DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7970369PMC
April 2021

Freeze-dried chitosan-platelet-rich plasma implants improve supraspinatus tendon attachment in a transosseous rotator cuff repair model in the rabbit.

J Biomater Appl 2019 01 14;33(6):792-807. Epub 2018 Nov 14.

4 Ecole Polytechnique de Montreal, 2900 Boul Edouard-Montpetit, Montreal, Canada.

Rotator cuff tears result in shoulder pain, stiffness, weakness and loss of motion. After surgical repair, high failure rates have been reported based on objective imaging and it is recognized that current surgical treatments need improvement. The aim of the study was to assess whether implants composed of freeze-dried chitosan (CS) solubilized in autologous platelet-rich plasma (PRP) can improve rotator cuff repair in a rabbit model. Complete tears were created bilaterally in the supraspinatus tendon of New Zealand White rabbits ( n = 4 in a pilot feasibility study followed by n = 13 in a larger efficacy study), which were repaired using transosseous suturing. On the treated side, CS-PRP implants were injected into the transosseous tunnels and the tendon itself, and healing was assessed histologically at time points ranging from one day to two months post-surgery. CS-PRP implants were resident within transosseous tunnels and adhered to tendon surfaces at one day post-surgery and induced recruitment of polymorphonuclear cells from 1 to 14 days. CS-PRP implants improved attachment of the supraspinatus tendon to the humeral head through increased bone remodelling at the greater tuberosity and also inhibited heterotopic ossification of the supraspinatus tendon at two months. In addition, the implants did not induce any detectable deleterious effects. This preliminary study provides the first evidence that CS-PRP implants could be effective in improving rotator cuff tendon attachment in a small animal model.
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http://dx.doi.org/10.1177/0885328218811386DOI Listing
January 2019

Freeze-Dried Chitosan-Platelet-Rich Plasma Implants for Rotator Cuff Tear Repair: Pilot Ovine Studies.

ACS Biomater Sci Eng 2018 Nov 31;4(11):3737-3746. Epub 2017 Oct 31.

Sports Medicine and Shoulder Service, The Hospital for Special Surgery, New York, New York 10021, United States.

Rotator cuff tears are a very common shoulder pathology. Different suturing techniques have been used for surgical cuff repair, but failure of healing remains a significant clinical challenge. The objective of this study was to establish and compare chronic and acute ovine rotator cuff tear models in our laboratory and investigate the feasibility of using chitosan (CS)-platelet-rich plasma (PRP) implants in conjunction with suture anchors to treat rotator cuff tears in large animal models. Repair with suture anchors only was used as control. In two preliminary pilot studies, unilateral full-thickness tears were created in the infraspinatus (ISP) tendon of mature female Texel-cross sheep. In the chronic model ( = 4 sheep), the tendons were capped with silicon and allowed to retract for 6 weeks, leading to degenerative changes, whereas the tendons were immediately repaired in the acute model ( = 4 sheep). Transected ISP tendons were reattached with suture anchors and, in the case of treated shoulders, implants composed of freeze-dried CS solubilized in autologous PRP were additionally applied to the tendon-bone interface and on top of the repaired site. The chronic defect model induced significant tendon degeneration and retraction, which made repair more challenging than in the acute defect model. Half the tendons in the chronic repair model were found to be irrepairable at 6 weeks. In the other half, the tendons could not be reattached to the footprint due to significant retraction, which made this a model of tissue formation in a gap. In contrast, the acute tendon repair model was executed easily. Extensive bone remodeling and tissue ingrowth at the tendon-bone interface were observed in the case of treatment with anchors + CS-PRP in both models, suggesting that CS-PRP implants could potentially modulate rotator cuff healing processes in large animal models.
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http://dx.doi.org/10.1021/acsbiomaterials.7b00354DOI Listing
November 2018

A pilot study to assess the safety and radiological performance of a new low-profile locking plate for high tibial osteotomy.

Knee 2018 Oct 29;25(5):866-873. Epub 2018 Jun 29.

The Royal Orthopaedic Hospital NHS Foundation Trust, Bristol Road South, Birmingham B31 2AP, United Kingdom. Electronic address:

Background: We report the first results of a new low-profile titanium locking plate for fixation of opening wedge high tibial osteotomy (OWHTO). Short spacer plates have been associated with a high hardware complication rate, whilst fixed angle locking plates have been associated with a high incidence of soft tissue irritation. This plate aims to achieve stable fixation whilst maintaining a low profile, allowing space for combined procedures.

Methods: All patients undergoing OWHTO with the Activmotion plate were retrospectively reviewed. Patients were allowed to progress to full weight bearing after two weeks. Radiographic assessment included the medial proximal tibial angle (MPTA) and posterior tibial slope at six weeks and then three monthly until union. All complications were recorded.

Results: Thirty-seven patients with 40 OWHTOs were included in the study. The mean MPTA increased from 85.2 preoperatively to 91.9 postop. Tibial slope changed from 5.2 to 4.2°. The correction was sustained until union with no loss of correction in the MPTA (median change 0.0, 95% CI for median (-0.25, 0.4)) or tibial slope (mean increase 0.32, 95% CI (-0.02, 0.67)).

Conclusions: In this pilot study the Activmotion plate raised no safety concerns with regard to implant related adverse events or loss of initial correction. Early rehabilitation with immediate partial weight bearing was possible and all cases proceeded to osteotomy union with the exception of one case that needed to undergo bone grafting with implant retention. Premature removal of the implant was necessary in four cases due to symptomatic hardware irritation.
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http://dx.doi.org/10.1016/j.knee.2018.05.013DOI Listing
October 2018

Bi-planar intra-articular deformity following malunion of a Schatzker V tibial plateau fracture: Correction with intra-articular osteotomy using patient-specific guides and arthroscopic resection of the tibial spine bone block.

Knee 2018 Oct 9;25(5):959-965. Epub 2018 Jun 9.

The Royal Orthopaedic Hospital Birmingham NHS Foundation Trust, Bristol Road South, Northfield B31 2AP, United Kingdom.

Malunited tibial plateau fractures are a surgical challenge. We report a case of a malunion following a Schatzker V tibial plateau fracture with a biplanar deformity of the medial hemi-plateau. This was treated with an intra-articular osteotomy and biplanar restoration of the medial hemi-plateau using patient-specific guides and 3-dimensional planning based on computed tomography (CT) images. The mechanical axis was paradoxically preserved and the lateral compartment showed evidence of overload and degeneration secondary to a malunited tibial spine bone block providing varus/valgus constraint. This was arthroscopically resected at the same sitting. The tibial plateau was restored to the desirable height with a vast improvement in function and pain levels.
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http://dx.doi.org/10.1016/j.knee.2018.05.015DOI Listing
October 2018

Structuring of Hydrogels across Multiple Length Scales for Biomedical Applications.

Adv Mater 2018 Apr 12;30(14):e1705013. Epub 2018 Feb 12.

School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.

The development of new materials for clinical use is limited by an onerous regulatory framework, which means that taking a completely new material into the clinic can make translation economically unfeasible. One way to get around this issue is to structure materials that are already approved by the regulator, such that they exhibit very distinct physical properties and can be used in a broader range of clinical applications. Here, the focus is on the structuring of soft materials at multiple length scales by modifying processing conditions. By applying shear to newly forming materials, it is possible to trigger molecular reorganization of polymer chains, such that they aggregate to form particles and ribbon-like structures. These structures then weakly interact at zero shear forming a solid-like material. The resulting self-healing network is of particular use for a range of different biomedical applications. How these materials are used to allow the delivery of therapeutic entities (cells and proteins) and as a support for additive layer manufacturing of larger-scale tissue constructs is discussed. This technology enables the development of a range of novel materials and structures for tissue augmentation and regeneration.
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http://dx.doi.org/10.1002/adma.201705013DOI Listing
April 2018

Bone remodelling in vitro: Where are we headed?: -A review on the current understanding of physiological bone remodelling and inflammation and the strategies for testing biomaterials in vitro.

Bone 2018 05 3;110:38-46. Epub 2018 Feb 3.

Regenerative Biomaterials Group, RAFT Institute, Leopold Muller Building, Mount Vernon Hospital, Northwood HA6 2RN, UK.

Bone remodelling is a dynamic process required for the maintenance of bone architecture in response to the changing mechanical needs. It is also a vital process during the repair of bone tissue following injury. Clinical intervention in terms of autografting or allografting is often required to heal bone injuries where physiological healing fails. The use of biomaterials as alternatives to autografts and allografts has spurred a significant research interest into further development of biomaterials for better clinical outcomes. Unfortunately, many biomaterials fail to make it to the clinic or fail after implantation due to the inconsistencies observed between in vitro and in vivo studies. It is therefore important to mimic the in vivo situation as closely as possible in an in vitro setting for testing biomaterials. The current in vitro models focus mostly on investigating the behaviour of osteoblast progenitors with the biomaterial under development as well as assessing the behaviour of osteoclasts, endothelial cells etc. However, the sequence of events that take place during bone healing or remodelling are not incorporated into the current in vitro models. This review highlights our current understanding of the physiological bone remodelling and the bone healing process followed by strategies to incorporate both the physiological and pathophysiological events into an in vitro environment. Here, we propose three strategies for the assessment of biomaterials for bone, which includes; (1) testing biomaterials in the presence of immune cells, (2) testing biomaterials for osteogenesis, and (3) testing biomaterials in the presence of osteoclasts followed by osteoblasts to recapitulate the physiological events of bone resorption prior to bone formation. The focus of this review is to discuss the third strategy in details as the first two strategies are currently incorporated into a majority of in vitro experiments.
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http://dx.doi.org/10.1016/j.bone.2018.01.015DOI Listing
May 2018

A systematic review of the concept and clinical applications of bone marrow aspirate concentrate in tendon pathology.

SICOT J 2017 9;3:58. Epub 2017 Oct 9.

The Royal Orthopaedic Hospital, Birmingham B31 2AP, UK - Regenerative Medicine, Aston University, Aston Triangle, Birmingham B4 7ET, UK.

Tendon pathologies are a group of musculoskeletal conditions frequently seen in clinical practice. They can be broadly classified into traumatic, degenerative and overuse-related tendinopathies. Rotator cuff tears, Achilles tendinopathy and tennis elbow are common examples of these conditions. Conventional treatments have shown inconsistent outcomes and might fail to provide satisfactory clinical improvement. With the growing trend towards the use of mesenchymal stem cells (MSCs) in other branches of medicine, there is an increasing interest in treating tendon pathologies using the bone marrow MSC. In this article, we provide a systematic literature review documenting the current status of the use of bone marrow aspirate concentrate (BMAC) for the treatment of tendon pathologies. We also asked the question on the safety of BMAC and whether there are potential complications associated with BMAC therapy. Our hypothesis is that the use of BMAC provides safe clinical benefit when used for the treatment of tendinopathy or as a biological augmentation of tendon repair. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist while preparing this systematic review. A literature search was carried out including the online databases of PubMed, EMBASE, ClinicalTrial.gov and the Cochrane Library from 1960 to the end of May 2015. Relevant studies were selected and critically appraised. Data from eligible studies were extracted and classified per type of tendon pathology. We included 37 articles discussing the application and use of BMAC for the treatment of tendon pathologies. The Critical Appraisal Skills Program (CASP) appraisal confirmed a satisfactory standard of 37 studies. Studies were sub-categorised into: techniques of extraction, processing and microscopic examination of BMAC (n = 18), where five studies looked at the evaluation of aspiration techniques (n = 5), augmentation of rotator cuff tears (n = 5), augmentation of tendo-achilles tendon (n = 1), treatment of gluteal tendon injuries (n = 1), management of elbow epicondylitis (n = 2), management of patellar tendinopathy (n = 1) and complications related to BMAC (n = 5). Multiple experimental studies investigated the use of BMAC for tendon repair; nonetheless, there are only limited clinical studies available in this field. Unfortunately, due to the scarcity of studies, which were mainly case series, the current level of evidence is weak. We strongly recommend further future randomised controlled studies in this field to allow scientists and clinicians make evidence-based conclusions.
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http://dx.doi.org/10.1051/sicotj/2017039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5632955PMC
October 2017

A systematic review of the clinical applications and complications of bone marrow aspirate concentrate in management of bone defects and nonunions.

Int Orthop 2017 11 13;41(11):2213-2220. Epub 2017 Aug 13.

The Royal Orthopaedic Hospital, Birmingham, UK.

Purpose: Fracture healing encompasses a succession of dynamic multifactorial metabolic events, which ultimately re-establishes the integrity of the biomechanical properties of the bone. Up to 10% of the fractures occurring annually will need additional surgical procedures because of impaired healing. The aim of this article is to review the current literature regarding the use of bone marrow aspirate concentrate (BMAC) and its effectiveness in the management of bone defects.

Methods: We have included all published clinical literature investigating the development, techniques and applications of BMAC. Language, design and risk of bias did not deter the initial inclusion of any study. Our search was exclusively limited to studies involving human subjects. A PRISMA compliant search was carried out as published in 2009. This included the online databases: PubMed, EMBASE, clinical trial.gov and the Cochrane library from 1960 to the end of May 2015. MeSH terms used included: "Bone" AND "Marrow" AND "Aspirate" AND "Concentrate" AND "Bone Defects" AND "NONUNION". Eligible studies were independently appraised by two authors using the Critical Appraisal Skills Program checklist. For the purpose of narrative review, relevant studies were included irrespective of methodology or level of evidence.

Results: Thirty-four of the 103 (48 PubMed and 55 EMBASE) results yielded by the preliminary search were included. Exclusions included three duplicate records, six letters, 17 non-orthopaedics related studies and four records irrelevant to our search topic. The CASP appraisal confirmed a satisfactory standard of 31 studies. They all had clearly defined objectives, were well designed and conducted appropriately to meet them. The published studies reported the use of BMAC in non-union and fracture healing (15 studies), bone defects (nine studies), spine fusion (two studies), distraction osteogensis (two studies) and complications related to the use of BMAC (seven studies).

Conclusions: Stem cells found in BMAC have the potential to self-renew, undertake clonal expansion and differentiate into different musculoskeletal tissues. The commercial processing of BMAC needs to be optimized in order to achieve a consistent end product, which will provide predicable and translatable results. The future potential of cell characterization in order to determine the optimum cell for repair/regeneration of bone also needs to be explored.

Level Of Evidence: Systematic Review of minimum level IV studies.
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http://dx.doi.org/10.1007/s00264-017-3597-9DOI Listing
November 2017

Platelet-rich plasma induces post-natal maturation of immature articular cartilage and correlates with LOXL1 activation.

Sci Rep 2017 06 16;7(1):3699. Epub 2017 Jun 16.

Centre of NanoHealth, Swansea University Medical School, Swansea University, Singleton Park, Swansea, SA2 8PP, United Kingdom.

Platelet-rich plasma (PRP) is used to stimulate the repair of acute and chronic cartilage damage even though there is no definitive evidence of how this is achieved. Chondrocytes in injured and diseased situations frequently re-express phenotypic biomarkers of immature cartilage so tissue maturation is a potential pathway for restoration of normal structure and function. We used an in vitro model of growth factor-induced maturation to perform a comparative study in order to determine whether PRP can also induce this specific form of remodeling that is characterised by increased cellular proliferation and tissue stiffness. Gene expression patterns specific for maturation were mimicked in PRP treated cartilage, with chondromodulin, collagen types II/X downregulated, deiodinase II and netrin-1 upregulated. PRP increased cartilage surface cell density 1.5-fold (P < 0.05), confirmed by bromodeoxyuridine incorporation and proportionate increases in proliferating cell nuclear antigen gene expression. Atomic force microscopy analysis of PRP and growth factor treated cartilage gave a 5-fold increase in stiffness correlating with a 10-fold upregulation of lysyl oxidase like-1 gene expression (P < 0.001). These data show PRP induces key aspects of post-natal maturation in immature cartilage and provides the basis to evaluate a new biological rationale for its activity when used clinically to initiate joint repair.
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http://dx.doi.org/10.1038/s41598-017-02297-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5473810PMC
June 2017

Suspended Manufacture of Biological Structures.

Adv Mater 2017 Apr 1;29(13). Epub 2017 Feb 1.

School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT, UK.

A method for the production of complex cell-laden structures is reported, which allows high-levels of spatial control over mechanical and chemical properties. The potential of this method for producing complicated tissues is demonstrated by manufacturing a complex hard/soft tissue interface and demonstrating that cell phenotype can be maintained over four weeks of culture.
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http://dx.doi.org/10.1002/adma.201605594DOI Listing
April 2017

A systematic review of the concept and clinical applications of Bone Marrow Aspirate Concentrate in Orthopaedics.

SICOT J 2017 6;3:17. Epub 2017 Mar 6.

The Royal Orthopaedic Hospital, B31 2AP Birmingham, UK - Birmingham University, B15 2TT Birmingham, UK.

Introduction: Mesenchymal stem cells (MSC's) are believed to have multipotent plasticity with the capability to differentiate along multiple cell lineages such as cartilage, bone, tendon, muscle, and nerve. Such multipotency has the potential to play an important role in the repair and reconstruction of multiple tissues across a number of orthopaedic specialties. Bone marrow and fat are the most abundant and accessible source of MSC's with bone marrow aspirate the most commonly being reported to stimulate healing.

Methods: This review examines the current reported 20 Q2 clinical applications of bone marrow aspirate concentrate and its effectiveness.

Results: The published studies reported techniques of collection and preparation of BMAC in addition to its applications in a number of orthopaedic sub-specialities. Studies could be sub-categorised into: techniques of extraction, processing and microscopic examination of BMAC (31), reconstruction of osseous defects/non-union (20), treatment of avascular necrosis (9), repair of cartilage defects (8), treatment of sports injuries and tendon injury/repair (9), injection in regenerative therapy (4), treatment of spine conditions (4) including enhancing postoperative fusion and degenerative disc pathology and orthopaedic oncology (4). A few published studies combined the use of platelet-rich plasma (PRP) with BMAC (4) or compared them in different applications (5).

Conclusions: BMAC has been used in bone, cartilage and tendon injuries with encouraging results.
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http://dx.doi.org/10.1051/sicotj/2017007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5966837PMC
March 2017

How to Build Your Simple and Cost-effective Arthroscopic Skills Simulator.

Arthrosc Tech 2016 Oct 12;5(5):e1039-e1047. Epub 2016 Sep 12.

Reading Shoulder Unit, Royal Berkshire and Berkshire Independent Hospital, Reading, England.

Acquisition of arthroscopic skills is not always easy and can be time-consuming. Simulation in arthroscopy improves surgical skills and can bridge the gap between reduced surgical exposure and training time and the need to reach a required level of competency. We propose a method to create a simple and cost-effective arthroscopic skills simulator using readily available materials and a low-cost Web camera available from online shops. This arthroscopic simulation device can be used to improve skills of all levels of trainees at home, in a bioskills laboratory, or in the theater. It can also be used by experienced surgeons to train with instruments and devices before using them for the first time in theaters, thus ensuring safe use and improving patient safety. Further validation as a training tool is needed and should be the focus of additional research, but early results are very promising.
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http://dx.doi.org/10.1016/j.eats.2016.05.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5124063PMC
October 2016

The Basic Science of Bone Marrow Aspirate Concentrate in Chondral Injuries.

Orthop Rev (Pavia) 2016 Sep 30;8(3):6659. Epub 2016 Sep 30.

Royal Orthopedic Hospital , The Woodlands, Birmingham, West Midlands, UK.

There has been great interest in bone marrow aspirate concentrate (BMAC) as a cost effective method in delivering mesenchymal stem cells (MSCs) to aid in the repair and regeneration of cartilage defects. Alongside MSCs, BMAC contains a range of growth factors and cytokines to support cell growth following injury. However, there is paucity of information relating to the basic science underlying BMAC and its exact biological role in supporting the growth and regeneration of chondrocytes. The focus of this review is the basic science underlying BMAC in relation to chondral damage and regeneration.
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http://dx.doi.org/10.4081/or.2016.6659DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066111PMC
September 2016

Rotator cuff repair: a review of surgical techniques, animal models, and new technologies under development.

J Shoulder Elbow Surg 2016 Dec 20;25(12):2078-2085. Epub 2016 Aug 20.

Biomedical Engineering Institute, Polytechnique Montréal, Montreal, QC, Canada; Chemical Engineering Department, Polytechnique Montréal, Montreal, QC, Canada. Electronic address:

Rotator cuff tears are the most common musculoskeletal injury occurring in the shoulder. Current surgical repair fails to heal in 20% to 95% of patients, depending on age, size of the tear, smoking, time of repair, tendon quality, muscle quality, healing response, and surgical treatments. These problems are worsened by the limited healing potential of injured tendons attributed to the presence of degenerative changes and relatively poor vascularity of the cuff tendons. Development of new techniques to treat rotator cuff tears requires testing in animal models to assess safety and efficacy before clinical testing. Hence, it is important to evaluate appropriate animal models for rotator cuff research with degeneration of tendons, muscular atrophy, and fatty infiltration similar to humans. This report reviews current clinical treatments and preclinical approaches for rotator cuff tear repair. The review will focus on current clinical surgical treatments, new repair strategies under clinical and preclinical development, and will also describe different animal models available for rotator cuff research. These findings and future directions for rotator cuff tear repair will be discussed.
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http://dx.doi.org/10.1016/j.jse.2016.06.009DOI Listing
December 2016

Hamstring stretch reflex: could it be a reproducible objective measure of functional knee stability?".

J Exp Orthop 2016 Dec 29;3(1). Epub 2016 Jan 29.

School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston Campus, Birmingham, West Midlands, B15 2TT, UK.

Background: The anterior cruciate ligament (ACL) plays an important role in anterior knee stability by preventing anterior translation of the tibia on the femur. Rapid translation of the tibia with respect to the femur produces an ACL-hamstring stretch reflex which may provide an object measure of neuromuscular function following ACL injury or reconstruction. The aim of this study was to determine if the ACL-hamstring stretch reflex could be reliably and consistently obtained using the KT-2000 arthrometer.

Methods: A KT-2000 arthrometer was used to translate the tibia on the femur while recording the electromyography over the biceps femoris muscle in 20 participants, all with intact ACLs. In addition, a sub-group comprising 4 patients undergoing a knee arthroscopy for meniscal pathology, were tested before and after anaesthetic and with direct traction on the ACL during arthroscopy. The remaining 16 participants underwent testing to elicit the reflex using the KT-2000 only.

Results: A total number of 182 trials were performed from which 70 trials elicited stretch reflex (38.5 %). The mean onset latency of the hamstring stretch reflexes was 58.9 ± 17.9 ms. The average pull force was 195 ± 47 N, stretch velocity 48 ± 35 mm/s and rate of force 19.7 ± 6.4 N/s.

Conclusions: Based on these results, we concluded that the response rate of the anterior cruciate ligament-hamstring reflex is too low for it to be reliably used in a clinical setting, and thus would have limited value in assessing the return of neuromuscular function following ACL injuries.
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http://dx.doi.org/10.1186/s40634-016-0040-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4731378PMC
December 2016

An In Vitro Comparison of the Incorporation, Growth, and Chondrogenic Potential of Human Bone Marrow versus Adipose Tissue Mesenchymal Stem Cells in Clinically Relevant Cell Scaffolds Used for Cartilage Repair.

Cartilage 2015 Oct;6(4):252-63

School of Life and Health Sciences, Aston University, Birmingham, UK.

Aim: To compare the incorporation, growth, and chondrogenic potential of bone marrow (BM) and adipose tissue (AT) mesenchymal stem cells (MSCs) in scaffolds used for cartilage repair.

Methods: Human BM and AT MSCs were isolated, culture expanded, and characterised using standard protocols, then seeded into 2 different scaffolds, Chondro-Gide or Alpha Chondro Shield. Cell adhesion, incorporation, and viable cell growth were assessed microscopically and following calcein AM/ethidium homodimer (Live/Dead) staining. Cell-seeded scaffolds were treated with chondrogenic inducers for 28 days. Extracellular matrix deposition and soluble glycosaminoglycan (GAG) release into the culture medium was measured at day 28 by histology/immunohistochemistry and dimethylmethylene blue assay, respectively.

Results: A greater number of viable MSCs from either source adhered and incorporated into Chondro-Gide than into Alpha Chondro Shield. In both cell scaffolds, this incorporation represented less than 2% of the cells that were seeded. There was a marked proliferation of BM MSCs, but not AT MSCs, in Chondro-Gide. MSCs from both sources underwent chondrogenic differentiation following induction. However, cartilaginous extracellular matrix deposition was most marked in Chondro-Gide seeded with BM MSCs. Soluble GAG secretion increased in chondrogenic versus control conditions. There was no marked difference in GAG secretion by MSCs from either cell source.

Conclusion: Chondro-Gide and Alpha Chondro Shield were permissive to the incorporation and chondrogenic differentiation of human BM and AT MSCs. Chondro-Gide seeded with BM MSCs demonstrated the greatest increase in MSC number and deposition of a cartilaginous tissue.
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http://dx.doi.org/10.1177/1947603515589650DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4568730PMC
October 2015

An analysis of the biomechanics of interference screw fixation and sheathed devices for biceps tenodesis.

Clin Biomech (Bristol, Avon) 2015 Jul 23;30(6):551-7. Epub 2015 Apr 23.

The Royal Orthopaedic Hospital, Bristol Road South, Birmingham, West Midlands B31 2AP, United Kingdom.

Background: This study aimed to evaluate the differences in biomechanical properties of biceps tenodesis when performed with sheathed versus unsheathed screws and also to investigate the effect of altering the pre-tension.

Methods: Tenodesis was performed in an in vitro model using biomechanical test blocks and ovine tendons. Blocks were allocated to 1 of 5 groups which varied by method of tenodesis and cyclical loading protocol: Group A, Biosure PK screw (10-100 N), Group B: 7-8 mm Biosure Sync and Biosure PK screw (10-100 N), Group C: Biosure PK screw (10-70 N), Group D: Biosure PK (20-100 N), and Group E: custom sheath and Biosure PK screw (10-100 N). If tenodeses remained intact after 500 cycles maximum load to failure testing was performed.

Findings: 30% of tenodeses in Group A failed prior to 500 cycles whereas none failed in the sheathed device groups (P=0.02). Using a sheathed device prevented mal-rotation. However, tenodeses in Group B were more likely to fail immediately distal to the tenodesis at a load below the anticipated maximum load to failure suggesting tendon damage during fixation. Using the custom sheath, which did not have sharp edges, resulted in a statistically significant increased maximum load to failure in Group E (348 N) when compared to Group A (228 N, mean difference 120 N, P=0.01) and Group B (253N, mean difference 95 N, P=0.0007).

Interpretation: Sheathed devices prevent mal-rotation and increase stiffness and maximum load to failure. This is further improved by reducing tendon damage at the time of tenodesis.
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http://dx.doi.org/10.1016/j.clinbiomech.2015.04.006DOI Listing
July 2015
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