Objectives. All-suture anchors are increasingly used in rotator cuff repair procedures. Potential benefits include decreased bone damage. However, there is limited published evidence for the relative strength of fixation for all-suture anchors compared with traditional anchors. Materials and Methods. A total of four commercially available all-suture anchors, the ‘Y-Knot’ (ConMed), Q-FIX (Smith & Nephew), ICONIX (Stryker) and JuggerKnot (Zimmer Biomet) and a traditional anchor control TWINFIX Ultra PK Suture Anchor (Smith & Nephew) were tested in cadaveric human humeral head rotator cuff repair models (n = 24). This construct underwent cyclic loading applied by a mechanical testing rig (Zwick/Roell). Ultimate load to failure, gap formation at 50, 100, 150 and 200 cycles, and failure mechanism were recorded. Significance was set at p < 0.05. Results. Overall, mean maximum tensile strength values were significantly higher for the traditional anchor (181.0 N, standard error (. se). 17.6) compared with the all-suture anchors (mean 133.1 N . se. 16.7) (p = 0.04). The JuggerKnot anchor had greatest displacement at 50, 100 and 150 cycles, and at failure, reaching statistical significance over the control at 100 and 150 cycles (22.6 mm . se. 2.5 versus 12.5 mm . se. 0.3; and 29.6 mm . se. 4.8 versus 17.0 mm . se. 0.7). Every all-suture anchor tested showed substantial (> 5 mm) displacement between 50 and 100 cycles (6.2 to 14.3). All-suture anchors predominantly failed due to anchor pull-out (95% versus 25% of traditional anchors), whereas a higher proportion of traditional anchors failed secondary to suture breakage. Conclusion. We demonstrate decreased failure load, increased total displacement, and variable failure mechanisms in all-suture anchors, compared with traditional anchors designed for rotator cuff repair. These findings will aid the surgeon’s choice of implant, in the context of the clinical scenario. Cite this article: N. S. Nagra, N. Zargar, R. D. J. Smith, A. J. Carr. Mechanical properties of all-suture anchors for rotator cuff repair. Bone Joint Res 2017;6:82–89. DOI: 10.1302/2046-3758.62.BJR-2016-0225.R1

Suture anchor have been used in surgical procedure of tendon or ligament repair. Recently, there has been developed an all suture anchor (soft anchor) which can be used even when the insertion area is narrow. But, the stability of soft anchors due to narrow zone has not been elucidated. This purpose of this study was to investigate stability of soft anchors with respect to their fixation intervals. Polyurethane foams with two different bone densities (10 pcf; 0.16g / cm³, 20 pcf; 0.32g / cm³) were used. All suture anchors and conventional suture anchors were fixed at 10mm, 5mm, and 2.5mm intervals. The failure load was measured using a mechanical testing machine. The average load to failure of conventional suture anchor were 200.4N, 200.2N, 184.7N in the 10mm, 5mm and 2.5mm interval with 10pcf foam bones and 200.4 N, 200.2 N and 184.7 N with the 20 pcf foam bone respectively. Average load to failure load of soft anchor was 97.3N, 93.9N and 76.9N with 10pcf foam bones and 200.4 N, 200.2 N and 184.7 N with 20 pcf foam bone. Suture screw spacing and bone density are important factors in anchor pullout strength. In osteoporotic bone density, insertion of the suture screw interval of 5 mm might be necessary

Introduction. Suture anchor have been used in surgical procedure of tendon or ligament repair. Recently, there has been developed an all suture anchor (soft anchor) which can be used even when the insertion area is narrow. But, the stability of soft anchors due to narrow zone has not been elucidated. This purpose of this study was to investigate stability of soft anchors with respect to their fixation intervals. Methods. Polyurethane foams with two different bone densities (10 pcf; 0.16g / cm³, 20 pcf; 0.32g / cm) were used. All suture anchors and conventional suture anchors were fixed at 10mm, 5mm, and 2.5mm intervals. The failure load was measured using a mechanical testing machine. Results. The average load to failure of conventional suture anchor were 97.3N, 93.9N, and 76.9N in the 10mm, 5mm and 2.5mm interval with 10pcf foam bones and 200.4 N, 200.2 N and 184.7 N with the 20 pcf foam bone respectively. Average load to failure load of soft anchor was 97.3N, 93.9N and 76.9N with 10pcf foam bones and 200.4 N, 200.2 N and 184.7 N with 20 pcf foam bone. Conclusion. Suture screw spacing and bone density are important factors in anchor pullout strength. In osteoporotic bone density, insertion of the suture screw interval of 5 mm might be necessary

To ensure clinical relevance, the in vitro engineering of tissues for implantation requires artificial replacements to possess properties similar to native anatomy. Our overarching study is focussed on developing a bespoke bone-tendon in vitro model replicating the anatomy at the flexor digitorum profundus (FDP) tendon insertion site at the distal phalanx. Anatomical morphometric analysis has guided FDP tendon model design consisting of hard and soft tissue types. Here, we investigate potential materials for creation of the model's bone portion by comparison of two bone cements; brushite and genex (Biocomposites Ltd).

3D printed molds were prepared based on anatomical morphometric analysis of the FDP tendon insertion site and used to cast identical bone blocks from brushite and genex cements. Studies assessing the suitability of each cement type were conducted e.g. setting times, pH on submersion in culture medium and interaction with fibrin gels. Data was collected using qualitative imaging and qualitative measurements (N=3,n=6) for experimental conditions.

Both brushite (BC) and genex (GC) cements could be cast into bespoke molds, producing individual blocks and were mixed/handled with appropriate setting times. On initial submersion in culture medium, BC caused a reduction in pH values (7.49 [control]) to 6.85) while GC remained stable (7.59). Reduction in pH value also affected fibrin gel interaction where gel was seen to be detaching/not forming around BC and medium discolouration was noted. This was not observed in GC. While GC outperformed BC in initial tests, repeated washing of BC led to pH stabilisation (7.5,3xwashes), consistent with their further use in this model.

This study has compared BC and GC as materials for bone block production. Both materials show promise, and current work assessing material properties and cell proliferation are needed to inform our choice for use in our FDP-tendon-bone interface model.

This research was supported by an ORUK Studentship award (ref:533). Genex was kindly provided by Biocomposites, Ltd.

This study aims to compare the biomechanical properties of the “Double Lasso-Loop” suture anchor (DLSA) technique with the commonly performed interference screw (IS) technique in an ex vivo ovine model. Fourteen fresh sheep shoulder specimens were used in this study. Dissection was performed leaving only the biceps muscle attached to the humerus and proximal radius before sharply incised to simulate long head of biceps tendon (LHBT) tear. Repair of the LHBT tear was performed on all specimens using either DSLA or IS technique. Cyclical loading of 500 cycles followed by load to failure was performed on all specimens. Tendon displacement due to the cyclical loading at every 100 cycles as well as the maximum load at failure were recorded and analysed. Stiffness was also calculated from the load displacement graph during load to failure testing. No statistically significant difference in tendon displacement was observed from 200 to 500 cycles. Statistically significant higher stiffness was observed in IS when compared with DSLA (P = .005). Similarly, IS demonstrated significantly higher ultimate failure load as compared with DSLA (P = .001). Modes of failure observed for DSLA was mostly due to suture failure (7/8) and anchor pull-out (1/8) while IS resulted in mostly LHBT (4/6) or biceps (2/6) tears. DSLA failure load were compared with previous studies and similar results were noted. After cyclical loading, tendon displacement in DLSA technique was not significantly different from IS technique. Despite the higher failure loads associated with IS techniques in the present study, absolute peak load characteristics of DLSA were similar to previous studies. Hence, DLSA technique can be considered as a suitable alternative to IS fixation for biceps tenodesis

Introduction and Objective. Local cartilage defects in the knee are painful and mostly followed by arthritis. In order to avoid impaired mobility, the osteochondral defect might be bridged by a synthetic compound material: An osteoconductive titanium foam as an anchoring material in the subchondral bone and an infiltrated polymer as gliding material in contact with the surrounding natural cartilage. Materials and Methods. Titanium foam cylinders (Ø38 mm) with porosities ranging from 57% to 77% were produced by powder metallurgy with two different grain sizes of the space holder (fine: 340 ± 110 μm, coarse: 530 ± 160 μm). The sintered titanium foam cylinders were infiltrated with UHMWPE powder on one end and UHMWPE bulk at the other end, at two different temperatures (160 °C, 200 °C), using a pressure of 20 MPa for 15 minutes. Smaller cylinders (Ø16 mm) were retrieved from the compound material by water jet cutting. The infiltration depths were determined by optical microscopy. The anchoring of the UHMWPE was measured by a shear test and the mechanical properties of the titanium foam were verified by a subsequent compression test. The tribological behaviour was investigated in protein containing liquid using fresh cartilage pins (Ø5 mm) sliding against a UHMWPE disc with or without a notch to simulate the gap between the implant and the surrounding cartilage. Friction coefficients were determined in a rotation tribometer and the cartilage wear in a multidirectional six-station tribometer from AMTI (load 10 – 50 N, sliding speed 20 mm/s, 37 °C). Results. UHMWPE could be infiltrated into titanium foam by 1.1 – 1.3 mm with fine pores and by 1.5 – 1.8 mm with coarse pores. The infiltration was neither dependent on the type of UHMWPE (powder or bulk) nor on the temperature. The polymer was so well anchored inside the titanium foam pores that the shear forces for the compounds exceeded the shear strength obtained for a UHMWPE-cylinder. This effect was due to the increased stiffness of the compound plug. Uniaxial compression of the titanium foams after the shear-off of the polymer revealed yield strengths ranging from 50 – 88 MPa for porosities of 62 – 73%. The Ø16 mm samples yielded beyond physiological loads in the knee (≥ 10x body weight) and behaved in a strain hardening and fully ductile manner, reaching deformations of at least 50 % of their initial height without the appearance of macroscopically visible cracks. For smaller plug diameters down to Ø8 mm, however, the lower porosity / higher strength foam should be used to limit elastic deformation of the compound to < 0.1 mm. Pore size did not significantly influence the strength and stiffness values. The elevated coefficient of friction between cartilage and UHMWPE of about 1 was not negatively affected by the presence of the gap. The height loss of the cartilage pin after 1 hour (respectively after 3600 reciproque wear cycles) was 0.2 ± 0.1 mm using a flat disc. For discs with a 1 mm wide V-notch, the wear increased to 0.9 ± 0.3 mm. Conclusions. The tested titanium foams are well suited to act as an anchoring material in the subchondral bone as mechanical properties can be tailored by choosing the adequate porosity and as bone ingrowth has previously been demonstrated for the used pore sizes. UHMWPE is not an ideal gliding partner against cartilage because the friction coefficients of frictions were high. The presence of a V-notched gap was detrimental for cartilage wear. More hydrophilic polymers like PCU should be tested as potential gliding materials

Despite extensive research aimed at improving surgical outcomes of enthesis injuries, re-tears remain a common problem, as the repairs often lead to fibrovascular scar as opposed to a zonal enthesis. Zonal enthesis formation involves anchoring collagen fibers, synthesizing proteoglycan-rich fibrocartilage, and mineralizing this fibrocartilage [1]. During development, the hedgehog signaling pathway promotes the formation and maturation of fibrocartilage within the zonal tendon-to-bone enthesis [1-4]. However, whether this pathway has a similar role in adult zonal tendon-to-bone repair is not known. Therefore, we developed a murine anterior cruciate ligament (ACL) reconstruction model [5] to better understand the zonal tendon-to-bone repair process and perturb key developmental regulators to determine the extent to which they can promote successful repair in the adult. In doing so, we activated the hedgehog signaling pathway both genetically using transgenic mice and pharmacologically via agonist injections. We demonstrated that both treatments improved the formation of zonal attachments and tunnel integration strength [6]. These improved outcomes were due in part to hedgehog signaling's positive role in proliferation of the bone marrow stromal cell (bMSC) progenitor pool and subsequent fibrocartilage production of bMSC progeny cells that form the attachments. These results suggest that, similar to growth and development, hedgehog signaling promotes the production and maturation of fibrocartilage during tendon-to-bone integration in adults. Lastly, we developed localized drug delivery systems to further improve the treatment of these debilitating injuries in future translational studies. Acknowledgements: This work was supported by NIH R01AR076381, R21AR078429, R00AR067283, F31AR079840, T32AR007132, and P30AR069619, in addition to the McCabe Fund Pilot Award at the University of Pennsylvania

Extracellular matrix (ECM) mechanical cues guide healing in tendons. Yet, the molecular mechanisms orchestrating the healing processes remain elusive. Appropriate tissue tension is essential for tendon homeostasis and tissue health. By mapping the attainment of tensional homeostasis, we aim to understand how ECM tension regulates healing. We hypothesize that diseased tendon returns to homeostasis only after the cells reach a mechanically gated exit from wound healing. We engineered a 3D mechano-culture system to create tendon-like constructs by embedding patient-derived tendon cells into a collagen I hydrogel. Casting the hydrogel between posts anchored in silicone allowed adjusting the post stiffness. Under this static mechanical stimulation, cells remodel the (unorganized) collagen representing wound healing mechanisms. We quantified tissue-level forces using post deflection measurements. Secreted ECM was visualized by metabolic labelling with non-canonical amino acids, click chemistry and confocal microscopy. We blocked cell-mediated actin-myosin contractility using a ROCK inhibitor (Y27632) to explore the involvement of the Rho/ROCK pathway in tension regulation. Tissue tension forces reached the same homeostatic level at day 21 independent of post compliance (p = 0.9456). While minimal matrix was synthesized in early phases of tissue formation (d3-d5), cell-deposited ECM was present in later stages (d7-d9). More ECM was deposited by tendon constructs cultured on compliant (1Nm) compared to rigid posts (p = 0.0017). Matrix synthesized by constructs cultured on compliant posts was less aligned (greater fiber dispersion, p = 0.0021). ROCK inhibition significantly decreased tissue-level tensional forces (p < 0.0001). Our results indicate that tendon cells balance matrix remodeling and synthesis during tissue repair to reach an intrinsically defined “mechanostat setpoint” guiding tension-mediated exit from wound healing towards homeostasis. We are identifying specific molecular mechanosensors governing tension-regulated healing in tendon and investigate the Rho/ROCK system as their possible downstream pathway

We compared time-dependent changes in the biomechanical properties of single-and double-row repair of a simulated acute tear of the rotator cuff in rabbits to determine the effect of the fixation techniques on the healing process. A tear of the supraspinatus tendon was created in 80 rabbits which were separated into two equal groups. A single-row repair with two suture anchors was conducted in group 1 and a double-row repair with four suture anchors in group 2. A total of ten intact contralateral shoulder joints was used as a control group. Biomechanical testing was performed immediately post-operatively and at four and eight weeks, and histological analysis at four and eight weeks. The mean load to failure in group 2 animals was greater than in group 1, but both groups remained lower than the control group at all intervals. Histological analysis showed similar healing properties at four and eight weeks in both groups, but a significantly larger number of healed tendon-bone interfaces were identified in group 2 than in group 1 at eight weeks (p < 0.012). The ultimate load to failure increased with the number of suture anchors used immediately post-operatively, and at four and eight weeks. The increased load to failure at eight weeks seemed to be related to the increase in the surface area of healed tendon-to-bone in the double-row repair group

Repair of tendon injuries aims to restore length, mechanical strength and function. We hypothesise that Demineralised Cortical Bone (DCB) present in biological tendon environment will result in remodelling of the DCB into ligament tissue. A cadaveric study was carried out to optimize the technique. The distal 1cm of the patellar tendon was excised and DCB was used to bridge the defect. 4 models were examined, Model-1: one anchor, Model-2: 2 anchors, Model-3: 2 anchors with double looped off-loading thread, Model-4: 2 anchors with 3 threads off-loading loop. 6 mature sheep undergone surgical resection of the distal 1cm of the right patellar tendon. Repair was done using DCB with 2 anchors. Immediate mobilisation was allowed, animals were sacrificed at 12 weeks. Force plate assessments were done at weeks 3, 6, 9 and 12. Radiographs were taken and pQCT scan was done prior to histological analysis. In the cadaveric study, the median failure force for the 4 models; 250N, 290N, 767N and 934N respectively. In the animal study, none of the specimens showed evidence of ossification of the DCB. One animal failed to show satisfactory progress, X-rays showed patella alta, on specimen retrieval there was no damage to the DCB and sutures and no evidence of anchor pullout. Functional weight bearing was 79% at week12. Histological analysis proved remodelling of the collagen leading to ligamentisation of the DCB. Results prove that DCB can be used as biological tendon substitute, combined with the use of suture bone anchor early mobilisation can be achieved

Introduction and Objective. Intramedullary nails are frequently used for treatment of unstable distal tibia fractures. However, insufficient fixation of the distal fragment could result in delayed healing, malunion or nonunion. The quality of fixation may be adversely affected by the design of both the nail and locking screws, as well as by the fracture pattern and bone density. Recently, a novel concept for angular stable nailing has been developed that maintains the principle of relative stability and introduces improvements expected to reduce nail toggling, screw migration and secondary loss of reduction. It incorporates polyether ether ketone (PEEK) inlays integrated in the distal and proximal canal portions of the nail for angular stable screw locking. The nail can be used with new standard locking screws and low-profile retaining locking screws, both designed to enhance cortical fixation. The low-profile screws are with threaded head, anchoring in the bone and increasing the surface contact area due to the head's increased diameter. The objective of this study was to investigate the biomechanical competence of the novel angular stable intramedullary nail concept for treatment of unstable distal tibia fractures, compared with four other nail designs in an artificial bone model under dynamic loading. Materials and Methods. The distal 70 mm of thirty artificial tibiae (Synbone) were assigned to 5 groups for distal locking using either four different commercially available nails – group 1: Expert Tibia Nail (DePuy Synthes); group 2: TRIGEN META-NAIL with Internal Hex Captured Screws (Smith & Nephew); group 3: T2 Alpha with Locking Screws (Stryker); group 4: Natural Nail System featuring StabiliZe Technology (Zimmer) – or the novel angular stable TN-Advanced nail with low-profile screws (group 5, DePuy Synthes). The distal locking in all groups was performed using 2 mediolateral screws. All specimens were biomechanically tested under quasi-static and progressively increasing combined cyclic axial and torsional loading in internal rotation until failure, with monitoring by means of motion tracking. Results. Initial nail toggling of the distal tibia fragment in group 5 was significantly lower as compared with group 3 in varus (p=0.04) or with groups 2 and 4 in flexion (p≤0.02). In addition, the toggling in varus was significantly lower in group 1 versus group 4 (p<0.01). Moreover, during dynamic loading, within the course of the first 10,000 cycles the movements of the distal fragment in terms of varus, flexion, internal rotation, as well as axial and shear displacements at the fracture site, were all significantly lower in group 5 compared with group 4 (p<0.01). Additionally, group 5 demonstrated significantly lower values for flexion versus groups 2 and 3 (p≤0.04), for internal rotation versus group 1 (p=0.03), and for axial displacement versus group 3 (p=0.03). A trend to significantly lower values was detected in group 5 versus group 1 for varus, flexion and shear displacement – with p ranging between 0.05 and 0.07 – and versus group 3 for shear displacement (p=0.07). Cycles to failure were highest in group 5 with a significant difference to group 4 (p<0.01). Conclusions. From a biomechanical perspective, the novel angular stable intramedullary nail concept with integrated PEEK inlays and low-profile screws provides ameliorated resistance against nail toggling and loss of reduction under static and dynamic loading compared with other commercially available intramedullary nails used for fixation of unstable distal tibia fractures

Aim. To investigate the validity of threshold values for the Oxford Hip and Knee Score (OHS and OKS) for treatment success 12 months after total knee or hip replacement. Methods. Questionnaires were administered to patients undergoing total hip (THA) or knee (TKA) replacement before and 12 months after surgery alongside questions assessing key accepted aspects of treatment success (satisfaction, pain relief, functional improvement) to form a composite criterion of success and assessed using receiver operator characteristic (ROC) analysis. Thresholds providing maximum sensitivity and specificity for predicting treatment success were determined for the total sample and subgroups defined by pre-surgery scores. Results. Data was available for 3203 THA and 2742 TKA patients. Applying the composite treatment success criterion, 52.7% of the TKA and 65.6% of the THA sample reported a successful treatment outcome. Accuracy for predicting treatment success was high for the OHS and OKS (both areas under curve 0.87). For the OHS a threshold value of 37.5 points showed highest sensitivity and specificity in the total sample, while for the OKS the optimal threshold was 32.5 points. Depending on pre-surgery scores optimal thresholds varied between 32.5 and 38.5 for the OHS and 28.5 and 35.5 for the OKS. Conclusions. This is the first study to apply a comprehensive composite “success” anchor to the OHS and OKS in order to determine thresholds for successful treatment with total joint replacement. Compared to widely publicised postoperative satisfaction metrics, far fewer patients report success with our composite anchor

INTRODUCTION. Growth-guidance constructs are an alternative to growing rods for the surgical treatment of early onset scoliosis (EOS). In growth-guidance systems, free-sliding anchors preserve longitudinal spinal growth, thereby eliminating the need for surgical lengthening procedures. Non-segmental constructs containing ultra-high molecular weight polyethylene (UHMWPE) sublaminar wires have been proposed as an improvement to the traditional Luque trolley. In such a construct, UHMWPE sublaminar wires, secured by means of a knot, serve as sliding anchors at the proximal and distal ends of a construct, while pedicle screws at the apex prevent rod migration and enable curve derotation. Ideally, a construct with the optimal UHMWPE sublaminar wire density, offering the best balance between providing adequate spinal fixation and minimizing surgical exposure, is designed preoperatively for each individual patient. In a previous study, we developed a parametric finite element (FE) model that potentially enables preoperative patient-specific planning of this type of spinal surgery. The objective of this study is to investigate if this model can capture the decrease in range of motion (ROM) after spinal fixation as measured in an experimental study. MATERIALS AND METHODS. In a previous in vitro study, the ROM of an 8-segment porcine spine was measured before and after instrumentation, using different instrumentation constructs with a sequentally decreasing number of wire fixation points. In the current study, the parametric FE model of the thoracolumbar spine was first validated relative to ROM values reported in the literature. The rods, screws, and sublaminar wires were implemented, and the model was subsequently used to replicate the in vitro tests. The experimental and simulated ROM”s for the different instrumentation conditions were compared. RESULTS. Good agreement between in vitro biomechanical tests and FE simulations was observed in terms of the decrease in ROM for the complete construct with wires at each level. The stepwise increase in total ROM with decreasing number of wires at the construct ends was less prominent in silico in comparison to in vitro. CONCLUSION. Important first steps in the implementation and validation of a growth-guidance construct for EOS patients in a patient-specific FE model of the spine have been made in this study. The parametric nature of the FE model allows for rapid personalization. Although further improvements to the model will be necessary to better distinguish between different spinal instrumentation constructs, we conclude that the model can well capture essential aspects of spinal motion and the overall effect of instrumentation

Chronic rotator cuff tears are a major problem especially in the elderly population. Refixation is associated with high re-rupture rates. Therefore new implants or healing methods are needed. For a control of success biomechanical characteristics of native as well as treated tendons are of particular importance. Currently, tensile tests with static material testing machines are the most common technique for the biomechanical characterization of tendons. Resulting values are the maximum force (Fmax), stiffness and the Young´s modulus. However, no information is given about the allocation of strains over the tendon area. In addition, the determination of Fmax results in tissue destruction thus foreclosing further evaluation like histology. The Digital Image Correlation (DIC) is a contact-free non-destructive optical measuring method which gives information about distribution of strains by tracking the areal shift of an applied speckle pattern. The needed speckle pattern has to have a high contrast, a homogeneous distribution and a good adhesion to the surface. The method is established for the characterization of construction materials [1] to detect e.g. weak points. The present study examined if DIC is applicable for the complementary biomechanical evaluation of the sheep infraspinatus tendon. Fine ground powder extracted from a printer cartridge was chosen as a starting point. Preliminary to the in vitro experiments, the powder was applied on sheets with different methods: brushing, blowing, sieving and stamping. Stamping showed best results and was used for further in vitro tests on cadaveric native tendons (n=5). First, the toner powder was transferred to coarse-grained abrasive paper using a brush and stamped on the tendon surface. Afterwards DIC analysis was performed. For the in vivo tests, the left infraspinatus tendon of two German black-headed Mutton Sheep was detached and then refixed with bone anchors, the right tendon was used as native control (authorization: AZ 33.19-42502-04-17/2739). 12 weeks after surgery the animals were euthanized, the shoulders were explanted and DIC measurement performed. The speckle pattern could be applied adequately on the smooth tendon surfaces of native tendons. All specimens could be analyzed by DIC with sufficient correlation coefficients. The highest displacements were measured in the peripheral areas, whereas the central part of the tendon showed a low displacement. Repaired left tendons showed obvious differences already macroscopically. The tendons were thicker and showed inhomogeneous surfaces. Application of the toner powder by stamping was distinctly more complicated, DIC analysis could not produce sufficient correlation coefficients. In summary, transfer of DIC to native infraspinatus tendons of sheep was successful and can be further transferred to other animal and human tendons. However, irregular surfaces in tendon scar tissues affect the application of an adequate speckle pattern with a stamp technique. Therefore, further modifications are necessary. This research project has been supported by the German Research Foundation “Graded Implants FOR 2180 – tendon- and bone junctions” WE 4262/6-1

Background. The majority of studies assessing minimal clinical important difference in outcome do so for management of chronic low back pain. Those that identify MCID following spinal surgical intervention fail to differentiate between the different pathologies and treatments or use variable methods and anchors in the calculation. Aim. To identify the MCID in scores across the most common spinal surgical procedures using standardised methods of calculation. Method. Prospective longitudinal study following elective lumbar spinal surgery. All patients had a complete set of spinal outcome assessments (ODI and VAS) and self perceived rating of the global and Mcnab criteria. MCID was calculated as defined by Hagg et al. Results. 244 patients of average age 53 years were followed up for 62 months post surgery. The MCID across the range of spinal surgeries was a 10 point change in ODI and 28 points for the VAS. A MCID following lumbar decompression surgery was a 3 point change in ODI and 29 points for VAS; 24 points in ODI and 37 points in the VAS for a discectomy, and 13 points in ODI and 23 point change in VAS for revision surgery. This value also varied depending on the anchor and method used for calculation. Conclusion. The MCID in score varies between different spinal procedures, method of calculation and the external anchor used. Standardised methods of calculating MCID in outcome measures should be used to allow comparative research and assessment. Generalisation of MCID in scores across a range of spinal procedures should be strongly discouraged. Conflicts of Interest. None. Source of Funding. None. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting

Summary. Our results prove that Demineralised Cortical Bone (DCB) can be used as biological tendon graft substitute, combined with correct surgical technique and the use of suture bone anchor early mobilisation can be achieved. Introduction. Surgical repair of tendon injuries aims to restore length, mechanical strength and function. In severe injuries with loss of tendon substance a tendon graft or a substitute is usually used to restore functional length. This is usually associated with donor site morbidity, host tissue reactions and lack of remodelling of the synthetic substitutes which may result in suboptimal outcome. In this study we hypothesise that DCB present in biological tendon environment with early mobilisation and appropriate tension will result in remodelling of the DCB into ligament tissue rather that ossification of the DCB at traditional expected. Our preparatory cadaveric study (abstract submitted to CORS 2013) showed that the repair model used in this animal study has sufficient mechanical strength needed for this animal study. Methods. 6 mature female sheep undergone surgical resection of the distal 1 cm of the right patellar tendon and osteotomy of patellar tendon attachment at the tibial tuberosity under general anaesthesia. Repair was done using DCB with 2 suture bone anchor. Animals were allowed immediate mobilisation after surgery and were sacrificed at 12 weeks. The force passing through the operated and non-operated legs was assessed preoperatively and at week 3, week 6, week 9 and week 12 bay walking the animals over a force plate. Radiographs were taken immediately after euthanasia, the Patella-Tendon-tibia constructs were retrieved and pQCT scan was done. Histological analysis included tenocytes and chondrocytes cell counts, semi-quantitative scoring of the neo-enthesis and polarised microscopy. Result. In this study, none of the retrieved specimens showed any evidence of ossification of the DCB as proved by the pQCT analysis. One animal failed to show satisfactory progress after week 3, X-rays showed patella alta, on specimen retrieval no damage to the DCB was found, sutures and stitches were intact and no evidence of anchor pullout was found. Force plate analysis of the other 5 animals showed satisfactory progression over time with 44% functional weight bearing at week 3 progressing to 79% at week 12. There was full range of movement of the stifle joint after 12 weeks. Histological analysis proved formation of neo-enthesis with evidence of cellulisation, vascularisation and remodelling of the collagen leading to ligamentisation of the DCB. Discussion. Surgical reconstruction of damaged tendons is technically challenging, patellar tendon injuries presents even more challenging situation as it involves weight bearing joint. It is generally accepted that a period of immobilisation with passive range of movement exercises and protected weight bearing for up to 6 weeks post operatively is usually advised. Some surgeons use offloading metal wire to protect the repair for 6 weeks involving second surgical procedure to remove the wire. Demineralised bone is usually used in orthopaedics to utilise its osteogenic properties as bone graft substitute and to enhance osteogenesis in load bearing situations. In our study we explored a potential new use of the demineralised bone as tendon graft substitute, it acts as collagen scaffold allowing host cells to remodel its fibres into ligament like structure

Summary Statement. Demineralised bone matrix augmented tendon-bone fixations in the animal model show less scar tissue and an enthesis morphology closer to the physiologic one which may lead to a more resistant repair construct. Introduction. Rotator cuff repair is one of the most common operative procedures in the shoulder. Yet despite its prevalence recurrent tear rates of up to 94% have been reported in the literature. High failure rates have been associated with tendon detachment from bone at the tendon – bone interface. Exogenous agents as biological strategies to augment tendon – bone healing in the shoulder represent a new area of focus to improve patient outcomes. Demineralised bone matrix (DBM) contains matrix bound proteins, exposed through acid demineralization step of DBM manufacture, and has long been recognised for its osteoinductive and osteoconductive properties. We hypothesised that DBM administered to the bone bed prior to the reattachment of the tendon, will upregulate healing and result in enhanced tissue morphology that more closely resembles that of a normal enthesis. An established ovine transosseous equivalent rotator cuff model was used. Methods. Following ethics approval, 10 adult wethers (18 months) were randomly allocated to control, n=4 (without DBM) or DBM, n=6 (DBM administered to bone bed) groups. The infraspinatus tendon was detached from its insertion and repaired in a transosseous equivalent fashion using PEEK suture anchors. In treatment animals 0.25cc of ovine DBM, previously prepared using a modified Urist protocol, was injected into two drill holes within the bony tendon footprint. Animals were culled at 4 weeks following surgery and processed for tissue histology and microcomputed tomography (μCT) endpoints. Results. No infection or tendon detachment following repair was noted in either group. 3D reconstructed images of μCT scans verified correct DBM and suture anchor placement. Histological images demonstrated distinct differences in tissue morphology between the two groups; however there was no evidence of the four – zoned structure characteristic of a healthy tendon bone insertion, in any specimens. In the control group specimens, the tendon midsubstance was highly disorganised with randomly arranged collagen fibres and diminutive areas of fibrocartilage. In the treatment group, large regions between tendon and bone were occupied by fibrocartilage. Within the fibrocartilage region, insertional collagen fibres appeared organised and chondrocytes were orientated in the direction of the insertional collagen fibres. Organised collagen fibre orientation within the tendon midsubstance was observed, though this was not consistent throughout all the specimens. DBM particles were resorbed and trabecular bone occupied the DBM holes. The PEEK anchors were all in direct contact with the ongrowing bone indicating good quality integration and fixation. Discussion. This study showed that DBM augmented tendon to bone repair leads to an upregulated cellular activity resulting in increased amounts of fibrocartilage between the repaired tendon and underlying bone. The upshot of this is an improved tissue organization which more closely resembles the morphology of the normal enthesis. Introduction of osteoinductive DBM at the tendon – bone interface during surgery may reduce failure rates associated with rotator cuff repair and improve clinical outcomes

Repair of the rotator cuff requires secure reattachment, but large chronic defects cause osteoporosis of the greater tuberosity which may then have insufficient strength to allow proper fixation of the tendon. Recently, suture anchors have been introduced, but have not been fully evaluated. We have investigated the strength of suture-to-anchor attachment, and the use of suture anchors in repairs of the rotator cuff either to the greater tuberosity or the lateral cortex of the humerus. The second method gave a significant increase in the strength of the repair (p = 0.014). The repairs were loaded cyclically and failed at low loads by cutting into bone and tendon, casting doubt on the integrity of the repair in early mobilisation after surgery. Repairs with suture anchors did not perform better than those with conventional transosseous attachment

A suitable wound closure is an indispensable requirement for an uncomplicated and expedient recovery after an abdominal surgery. The closure technique will have a great impact on the healing process of the wound. Surgical complications, such as wound dehiscence (sometimes associated with evisceration), infection, hernia, nerve injury and incisional pain are very common in the postoperative period of an abdominal surgery. Besides, although their development can be promoted by other risk factors like age, sex, lifestyle, diet, health condition, the closure method can also influence the emergence of these undesirable complications. For this reason, and having the wellbeing and quality of life of the patients in mind, particularly high-risk patients, a closure system consisting of anchors applied on either side of the wound that aims to reduce the tension caused on the surrounding tissues of a wound and, consequently, decrease the risk of herniation was evaluated in a pilot animal study and compared with the traditional suture approach

Musculoskeletal diseases are leading causes of disability, morbidity and economic loss across the globe today. Yet for much of the world's population access to cheap, safe and effective intervention is lacking, while others choose not to accept best practice and best evidence, or significantly more expensive treatment. Great advances have been made in some diseases like rheumatoid arthritis, but the cost of many new treatments is unaffordable, and individuals, insurance and governments struggle to, or cannot fund it. Anchor bias and politics determines national policies and research funding, often favouring other illnesses while musculoskeletal disorders lack the support proportional to their frequency and impact. This is not appreciated by policy makers and governments, and the consequences of lack of care or poor-quality care. The need has never been greater for a treatment for osteoarthritis, the most common disease in the world; but the search for a cure needs funding, and if discovered, who will pay for it?