An experimental model of osteoarthritis resulting from laxity of the joint was induced in eighteen mature dogs (at least two years old) by sectioning the anterior cruciate ligament of the right knee (stifle) with a stab incision, the left knee providing a control. A sham operation was also performed in three other dogs, in which a stab incision was made but the ligament left intact. The dogs were killed at various intervals from one to forty-eight weeks later. Morphological changes in bone, cartilage, synovial membrane and joint capsule were examined in all the joints and biochemical changes in the cartilage of three dogs killed after two, eight, and sixteen weeks. All the changes resulting from the operation progressed with time and became indistinguishable from those found in three dogs with natural osteoarthritis of the knee. There were no changes in the joints which had sham operations. As the time of onset is known, this experimental model in a larger species enables a study to be made of the biochemical as well as the morphological changes in the early stages of osteoarthritis

The most frequent pathogenic organism in arthroplasty infections is Staphylococcus. The immune response impairment is a frequent finding in elderly people. Objective: to investigate the response of some cytokines and the effect of age in an experimental model of osteomyelitis. Materials and methods. 40 adult male Wistar rats received a stainless steel needle, intramedullarily in the left tibia. Young rats (3 months old) and Old rats (22 months old) were alloted in: Group A: Sterile implant. Group B: Sterile implant + slime producing S. aureus. 9 weeks after surgery, rats were sacrified. Determinations: Cytokines (IL-1b, IL-2, L-4, IL-6, IL-10 and IL-12)(ELISA) in blood (previous to surgery and to sacrifice) and in tibia extract (after sacrifice); the number of bacteria in tibia and implant. The Wilcoxon, Mann-Whitney U test were used (p≤ 0.05 significant). Results. Infection was detected in all the operated tibias in old rats receiving S.aureus, and in 7/10 of young rats. IL-2 levels increased in blood in the S.aureus group after surgery in old and young rats. Pre and postoperative IL-2 levels in blood were higher in old rats in both groups than in the corresponding groups of young rats. There was a decrease with age in blood of IL-4 (previous and after surgery), and a decrease of IL-1. S.aureus groups increased IL-1 levels in the operated tibia independently of age; increased IL-2 and IL-10 levels in young rats in the operated tibia; increased IL-4, IL-6 and IL-12 in old rats in blood, decreased IL-4 and increased IL-2 and IL-10 in blood in young rats. Conclusions. Significant differences in tibia infection were found with age. Old rats presented differences with young rats in cytokine response in an experimental model of osteomyelitis, showing an immune response impairment associated with old age

The 4th England and Wales NJR showed that 83% of total knee replacements were cemented (47,626 knees). This study aimed to compare modern techniques of cementation of the proximal tibia in an experimental model against tourniquet-less knee replacement surgery with cancellous bone suction and a cement gun. A metal box was constructed to approximate the proximal tibia and open cell sawbone simulated the tibia with simulated blood flow and bone suction. Each sample was prepared in an identical fashion except for the cementing technique. The techniques compared were of. Tourniquet,. No tourniquet,. No tourniquet + cancellous bone suction and. No Tourniquet, suction applied + cement gun pressurisation. Samples were subsequently sectioned, polished and the cemented area measured using a planimeter. ANOVA testing demonstrated that the techniques were significantly different (p< 0.0001). Bonferroni Comparison demonstrated that the Exeter technique gave significantly better cement penetration for central and lateral measurements (p< 0.0001 and p< 0.0001) compared to all other methods. The authors believe that our technique of cementation of the proximal tibia offers an easy and reproducible way of getting good quality cementing of the tibial component in total knee replacement and this is borne out by our experimental model

1. The hyaluronate of synovial fluid is an acidic linear polymer which can effectively resist the diffusion of other macromolecules into its domain. Gelatin was used as an experimental model for hyaluronate, to investigate its effect upon the diffusion of protein-polysaccharides from cartilage slices. 2. The concentration of protein-polysaccilaride in the extracting medium was quantitated by uronic acid estimation and liquid scintillation spectrometry of . 35. sulphate-labelled proteinpolysaccharide. 3. Concentrations of gelatin in excess of 20 per cent (W/v) significantly retarded diffusion of protein-polysaccharides out of cartilage slices, but evidently not the movement of these molecules within cartilage. 4. It is suggested that disaggregation of both the protein-polysaecharide molecules of cartilage and the hyaluronate of synovial fluid contribute to cartilage breakdown

Posterolateral spinal fusion (PSLSF) in rabbits is a challenging model for bone substitutes because the transverse processes are extremely thin and the space to be filled with bone is greater than critical and meiopragic in terms of vascularity. Several investigators have shown beneficial effects of PRP in bone and soft-tissue healing processes. However, controversial results have been reported in clinical setting analysing the effectiveness of PRP. Aim of the present study was to test the effectiveness of PRP in experimental model of PLSF in rabbits. MATERIAL AND METHODS. 20 White females New Zeland Rabbits were used. Seven rabbits (Group 1) had PRP plus carrier on the right side (Group 1A) and plus carrier and fresh bone marrow on the left side (Group 1B). Seven rabbits (Group 2) had carrier alone on the right side (Group 2A) and carrier plus fresh bone marrow on the left side (Group 2B). Six rabbits (Group 3) had sham operation on both right and left sides. Animals were sacrificed 6 months after surgery and the lumbar spine submitted to radiolographic and histologic analysis. Vascular density (VD) was also assessed in the different zone of the grafted material. RESULTS. Radiographs showed a complete fusion in 83% of group 1A and in 83% of group 1B, and in 86% of group 2A and 2B. Pseudarthrosis or non union, was observed in 1 specimen of group 1B and 2A and in all specimens of group 3 (sham). In contrast to radiographic results, no specimen showed a complete bony bridge between the transverse processes on histologic analysis. VD was significantly greater in the periapophyseal compared to the interapophyseal region of the graft material. However, no significant difference was found in the VD between groups. CONCLUSIONS. In this study PRP alone, or augmented with fresh bone marrow, failed to induce a histologically proved bony fusion in the PLSF model. Factors which may influence the effectiveness of PRP should be further addressed before applying PRP in the clinical setting

Purpose of this study is to create an experimental model of electrophysologic evaluation of the supraspinatus muscle on rats, after traumatic rupture of its tendon. The population of this study consisted of 10 male Sprague Dawley rats weighting 300–400g. Under general anaesthesia we proceeded with traumatic rupture of the supraspinatus tendon and exposure of the muscle. The scapula was immobilized, and the supraspinatus tendon was attached to a force transducer using a 3–0 silk thread. A dissection was performed in order to identify the suprascapular nerve, which was then stimulated with a silver electrode. Stimulations were produced by a stimulator (Digitimer Stimulator DS9A) and were controlled by a programmer (Digitimer D4030). Fiber length was adjusted until a single stimulus pulse elicited maximum force during a twitch under isometric conditions. Rectangular pulses of 0.5 ms duration were applied to elicit twitch contractions. During the recordings, muscles were rinsed with Krebs solution of approximately 37 8C (pH 7.2–7.4) and aerated with a mixture of 95% O2 and 5% CO2. The output from the transducer was amplified and recorded on a digital interface (CED). The following parameters were measured at room temperature (20–21 8C): single twitch tension; time to peak; half relaxation time; tetanic tensions at 10, 20, 40, 80 and 100 Hz; and fatigue index, which was evaluated using a protocol of low frequency (40 Hz) tetanic contraction, during 250 ms in a cycle of 1 s, for a total time of 180 s. The fatigue index value was then calculated by the formula [fatigue index=(initial tetanic tension − end tetanic tension) ∗ 100/(initial tetanic tension)]. In the end, the transducer was calibrated with standard weights and tensions were converted to grams. The mean single twitch was 8.2, the time to peak 0.034 msec and the half relaxation time 0.028 msec. The strength of titanic muscle contractures was 5.7 msec at 10Hz and 17.7 at 100Hz. Finally, the fatigue index was calculated at 48.4. We believe that electrophysiologic evaluation of the supraspinatus muscle in rats will help us understanding the pathology of muscle atrophy after rotator cuff tears and possibly the functional restoration after cuff repair

Aim. Bacterial identification in musculoskeletal infection is sometimes difficult and treatment strategy difficult facing unknown pathogen agent. We wonder if the delay of incubation and the preservation conditions of the samples between surgical procurement and subculture on plates have an influence. Method. 25 cm³ bone fragments were obtained from femoral heads retrieved during hip arthroplasty and excluded for bone transplant donation. Informed consent was obtained from the donor for research purpose. The study was approved by the Ethic Committee (N°B403201317725). Bone fragments were immersed for 30 minutes under gently agitation (140 RPM) at 35°C in a physiologic solution (negative control) or two solutions with two concentrations of staphylococcus epidermidis (0.5 Mc Farland or 1.5× 108 bacteria and 7.5×102 bacteria). Bone samples were separated and preserved at room temperature or at 4°C until seeded on Petri Plates to observe the influence of preservation conditions. Samples were plated after different delays (T0, T30min, T1H, T2H, T4H, T6H, T8H, T12H, T16H, T24H et T48H) to observe the influence of delay of culture. Experiments were repeated 5 times. When culture was positive, results were expressed with the number of colony. Results. We observed a regular diminution of number of colonies with the delay of culture. The number of colony goes to zero after 40 hours when the samples have been preserved at room temperature. Differences were not significant between preservation at room temperature and at 4°C for delay inferior to 04 hours but become significant for higher delay of culture in favor of low temperature preservation. With a low bacterial bioburden, no colony was recovered after a delay of 06 hours. False positive results were observed in 4% of the negative control. Conclusions. This experimental model demonstrates the negative influence of delay of culture and preservation at room temperature if the culture is delayed for more than 04 hours. The negative influence is more critical when facing low bacterial bioburden as it is generally the case in musculoskeletal infections. Our model do not included biofilm embedded bacteria and is limited to a staphylococcus epidermidis strain. The results could be worse with anaerobic bacteria. Some inhibition due to antibi prophylaxis given to patient just before hip arthroplasty could have negatively influence the results. This study stresses the importance of a rapid seeding of bacterial samples to improve bacterial identification. Procedures should be in place to transfer rapidly samples to the lab and process them immediately

Different calcaneal plates with locked screws were compared in an experimental model of a calcaneal fracture. Four plate models were tested, three with uniaxially-locked screws (Synthes, Newdeal, Darco), and one with polyaxially-locked screws (90° ± 15°) (Rimbus). Synthetic calcanei were osteotomised to create a fracture model and then fixed with the plates and screws. Seven specimens for each plate model were subjected to cyclic loading (preload 20 N, 1000 cycles at 800 N, 0.75 mm/s), and load to failure (0.75 mm/s). During cyclic loading, the plate with polyaxially-locked screws (Rimbus) showed significantly lower displacement in the primary loading direction than the plates with uniaxially-locked screws (mean values of maximum displacement during cyclic loading: Rimbus, 3.13 mm (. sd. 0.68); Synthes, 3.46 mm (. sd. 1.25); Darco, 4.48 mm (. sd. 3.17); Newdeal, 5.02 mm (. sd. 3.79); one-way analysis of variance, p < 0.001). The increased stability of a plate with polyaxially-locked screws demonstrated during cyclic loading compared with plates with uniaxially-locked screws may be beneficial for clinical use

Introduction. The same cup orientation is classically applied to all cases of hip replacement (45° abduction, 20° anteversion). We hypothesize that this orientation must be adapted to the patient's hip range of motion. We tested this hypothesis by means of an experimental study with respect to hip range of motion, comparing the classical orientation (45° and 20°), and the orientation obtained with computer-assisted navigation. Material and Methods. The experimental model included a hemipelvis equipped with a femur whose mobility was controlled for three configurations: stiff (60°/0°, 15°/10°, 10°/10°), average (80°/10°, 35°/30°,35°/25°), mobile (130°/30°, 50°/50°, 45°/35°). The hemipelvis and the cup holder were equipped with an electromagnetic system (Fastrack ™) to measure cup orientation. The Pleos™ navigation system (equipping the hemipelvis, the femur, and the cup holder) guided the cup orientation by detecting the positions risking impingement through a kinematic study of the hip. Nine operators each performed 18 navigation-guided implantations (162 hip abduction, anteversion, and range of movement measurements) in two series scheduled 2 months apart. Results. The model used herein showed intra and interobserver reliability. Compared to the navigation-assisted surgery, the arbitrary orientation gave a mean anteversion error of only 1° ± 6° (−12 to +19°) but 5° ± 8° (−26° to +13°) for abduction. However, 16% of the errors were more than 10° in anteversion (1/2 in the mobile configuration) and 11% of the errors were more than 15° in abduction (for the most part in the mobile configuration). With arbitrary orientation, the errors consisted in excess anteversion and insufficient abduction. Discussion and Conclusion. The experimental model developed was reliable and can be used to evaluate different prosthetic configurations. This study emphasizes that the ideal arbitrary cup orientation cannot be applied to all hips. All the surgeons are very reproducible but the only way to integrate the range of motion in there ‘own way to do’ in vitro, is to use a navigation system witch can guide the surgeon so as to reduce the risk of impingement and instability

Purpose: The purpose of our work was to study the effects of sequential arthroscopic section of the anterior capsule of the shoulder joint using an experimental model of retractile capsulitis induced by heat treatment. Material and methods: Twelve cadaver shoulders were studied. Passive mobility was initially normal. Anterior capsule retraction was first created under arthroscopic control (Arthrocare® generator, power 2). Twelve programmed sequential sections were then performed successively using the thermal probe (Arthrocare®, power 9) on: the coracohumeral ligament (CHL) and the superior glenohumeral ligament (SGHL), the middle gleno-humeral ligament (MGHL), the inferior glenohumeral ligament (IGHL), and the intra-articular portion of the subscapular muscle tendon (SST). The posterior capsule was not studied. At each step, motion was measured independently by two operators. At the end of the sequence, the articulation was opened to verify the sections as was the absence of any injury to noble structures. Results: Measures were reproducible (mean difference 5° between two series). The sections were correctly achieved. Macroscopically, there were no injuries to noble structures. The role of the different elements studied were as follows: — rotator interval (CHL, SGHL): gain in RE1 (mean 40°) and RE2 (mean 35°) (greater than loss during retraaction; — IGHL: gain in elevation (mean 33°); — IGHL and rotator interval: potentialisation of gain in FE2 (mean 41°) and elevation (mean 50°); — MGHL: moderate increase in external rotation at 45° antepulsion and elevation (mean 20°); —SST: discrete gain in RE1 (10°) but risk of dislocation (n=1). Discussion: Our model was reproducible. Section of the anterior capsule by a thermal method did not produce macroscopic injury to neighboring tissues. Our study pointed out the preeminent importance of sectioning the rotator interval for recovering external rotation. This section, combined with section of the IGHL has a potentialsing effect. The limitation of our study is the absence of examination of the posterior capsule

Joint tissues release extracellular vesicles (EVs) that potentially sustain joint homeostasis and contribute to osteoarthritis (OA) pathogenesis. EVs are putative novel therapeutics for OA, and transport biologically active molecules (including small non-coding RNAs (SNCRNAs)) between cells. This study identified altering SNCRNA cargo in EVs in OA which may act as early diagnostic markers and treatment targets.

OA was surgically induced in four skeletally mature Standardbred horses using an osteochondral fragment model in the left middle carpal joint. The right joint underwent sham surgery. Synovial fluid (SF) and plasma were obtained weekly throughout the 70-day study. EVs were isolated using size exclusion chromatography and characterised using nanoparticle tracking (Nanosight), and exosome fluorescence detection and tetraspanin phenotyping (Exoview). RNA was extracted from EVs derived from SF (sham and OA joints) and plasma collected at days 10, 35, 42, 49, 56, 63, and subjected to small RNA sequencing on a NovaSeq SP100 flow cell (Illumina).

Nanosight-derived EV characteristics of size and concentration were not significantly different following disease induction. The diameter of the temporal population of plasma and SF-derived exosomes changed significantly for CD9 and CD81 following OA induction with significant temporal, and disease-related changes in CD63 and CD81 protein expressin in plasma and SF.

In SF and plasma-derived EVs snoRNAs, snRNAs, tRNAs, lncRNA, y-RNA, piRNAs and scRNA were found. Following pairwise analysis of all-time points we identified 27 miRs DE in plasma and 45 DE miRs in SF. Seven were DE in plasma and SF; miR-451, miR-25, miR-215, miR-92a, miR-let-7c, miR-486-5p, miR-23a. In plasma and SF 35 and 21 snoRNAs were DE with four DE in plasma and SF; U3, snord15, snord46, snord58.

This work has identified alterations to OA EV sncRNAs in plasma and SF providing a greater understanding of the role of EVs in early OA.

Aims

Periprosthetic hip fractures (PPFs) after total hip arthroplasty are difficult to treat. Therefore, it is important to identify modifiable risk factors such as stem selection to reduce the occurrence of PPFs. This study aimed to clarify differences in fracture torque, surface strain, and fracture type analysis between three different types of cemented stems.

The aim of this work was to develop a novel, accessible and low-cost method, which is sufficient to measure changes in meniscal position in a whole-knee joint model performing dynamic motion in a knee simulator.

An optical tracking method using motion markers, MATLAB (MATLAB, The MathWorks Inc.) and a miniature camera system (Raspberry Pi, UK) was developed. Method feasibility was assessed on porcine whole joint knee samples (n = 4) dissected and cemented to be used in the simulator (1). Markers were placed on three regions (medial, posterior, anterior) of the medial meniscus with corresponding reference markers on the tibial plateau, so the relative meniscal position could be calculated. The Leeds high kinematics gait profile scaled to the parameters of a pig (1, 2) was driven in displacement control at 0.5 Hz. Videos were recorded at cycle-3 and cycle-50. Conditions tested were the capsule retained (intact), capsule removed and a medial posterior root tear. Mean relative displacement values were taken at time-points relating to the peaks of the axial force and flexion-extension gait inputs, as well as the range between the maximum and minimum values. A one-way ANOVA followed by Tukey post hoc analysis were used to assess differences (p = 0.05).

The method was able to measure relative meniscal displacement for all three meniscal regions. The medial region showed the greatest difference between the conditions. A significant increase (p < 0.05) for the root tear condition was found at 0.28s and 0.90s (axial load peaks) during cycle-3. Mean relative displacement for the root tear condition decreased by 0.29 mm between cycle-3 and cycle-50 at the 0.28s time-point. No statistically significant differences were found when ranges were compared at cycle-3 and cycle-50.

The method was sensitive to measure a substantial difference in medial-lateral relative displacement between an intact and a torn state. Meniscus extrusion was detected for the root tear condition throughout test duration. Further work will progress onto human specimens and apply an intervention condition.

Background: Developmental dysplasia of the hip (DDH) is a common paediatric orthopaedic problem. Open reduction and debridement of the hip joint in neonates is necessary to ensure a congruent reduction in some patients. Despite advances in the treatment of DDH, the various surgical approaches are not without limitations and risks. The development of hip arthroscopy is a new science, which we believe could be applied to the treatment of DDH.

Aims: To date there have been no reports in the literature of the use of hip arthroscopy in either the neonatal hip or in infantile hips with DDH. The purpose of this study was: (a) to design a suitable animal model of DDH for the purpose of designing and evaluating hip arthroscopy, (b) to document the pathoanatomy of the dysplastic hip arthroscopically and (c) to define the methodology of performing hip arthroscopy in neonates with DDH.

Method: A novel model of producing hip dysplasia in large white cross piglets has been created. 4-week-old piglets undergo surgical fixation of the knee by retrograde passage of a 3.5mm diameter steinmann pin. After free ambulation, progressive hip dysplasia is produced. We have monitored the development of hip dysplasia at 4 and 6 weeks post fixation by plain radiographs, MRI and Hip Arthroscopy using a 2.7mm diameter arthro-scope.

Results: We have successfully produced hip dysplasia in an animal model of comparable size and anatomy to that seen in infants. Hip arthroscopy was performed in 20 animals. Documentation of a lax capsule, elongated ligamentum teres and pulvinar has been made. In addition arthroscopic debridement of the joint has been performed. We believe that arthroscopic debridement of the impediments to reduction in DDH is possible using the techniques learned from this model.

In a new rabbit model of carbapenem-resistant Klebsiella pneumoniae knee-prosthesis infection, we studied the efficacy of colistin cement alone or in combination with systemic intramuscular (i.m.) injections of colistin.

Seven days after infection, surgical debridement and removal of the infected prostheses were performed, and rabbits were randomly assigned to one of four different treatment groups of twelve rabbits: prosthesis replacement by drug-free cement spacer (control) prosthesis replacement by colistin-loaded cement spacer (3 MUI of colistin/40 g of cement) (colistin local), prosthesis replacement by drug-free cement spacer and i.m. colistin (12 mg/kg of body weight, three time a day for 7 days), or colistin local + i.m.

We observed a statistically significant difference (p = 0.049) between the colistin local + systemic group and the control group in the criteria of number of rabbits with sterile bone under the total number of rabbits.

Combination of systemic and local colistin could be an interesting therapeutic option to cure carbapenem-resistant Klebsiella pneumoniae peri prosthetic joint infection.

Aims: Developmental dysplasia of the hip (DDH) is a common paediatric orthopaedic problem. Open reduction and debridement of the hip joint in neonates is necessary to ensure a congruent reduction in some patients. Despite advances in the treatment of DDH, the various surgical approaches are not without limitations and risks. The purpose of this study was: (a) to design a suitable animal model of DDH for the purpose of designing and evaluating hip arthroscopy, (b) to document the pathoanatomy of the dysplastic hip arthroscopically and (c) to deþne the methodology of performing hip arthroscopy in neonates with DDH. Methods: A novel model of producing hip dysplasia in large white cross piglets has been created. 4-week-old piglets undergo surgical þxation of the knee by retrograde passage of a 3.5mm diameter steinmann pin. After free ambulation, progressive hip dysplasia is produced. We have monitored the development of hip dysplasia at 4 and 6 weeks post þxation by plain radiographs, MRI and Hip Arthroscopy using a 2.7mm diameter arthroscope. Results: We have successfully produced hip dysplasia in an animal model of comparable size and anatomy to that seen in infants. Hip arthroscopy was performed in 20 animals. Documentation of a lax capsule, elongated ligamentum teres and pulvinar has been made. In addition arthroscopic debridement of the joint has been performed. We believe that arthroscopic debridement of the impediments to reduction in DDH is possible using the techniques learned from this model.

1. Synovitis was induced in the hip joints of fifty-six rabbits by the intra-articular injection of surgical talc. The opposite hip joint and eleven suitable"sham" operations served as controls.

2. The results in the hips injected with talc were as follows. Widening of the medial joint space and sometimes acetabular changes were seen; enlargement of the femoral head and neck in two planes was found, with, in most cases, flattening of the superior aspect of the head; there was thickening of the joint cartilage and sometimes deformity of the capital epiphysis; thickening of the cartilage was the main cause of the coxa magna, cervix magna and ischium magnum.

3. The embryology, micro-anatomy and development of the hip joint is reviewed and attention is drawn to the configuration of the layers of germinal cartilage cells. The effect of an induced synovitis in producing hyperplasia of the joint cartilage, incongruity of the articulating surfaces and subsequent subluxation is discussed.

Introduction and purpose: We have studied the in-vitro response of older and osteoarthritic chondrocytes when confronted with various factors in order to analyze the possible reversion of their phenotype to that of healthy chondrocytes.

Materials and methods: The study used cartilage from young (3 months’ old) and old (7 years old) lambs with an osteoarthritic pathology. The latter group was obtained by means of a meniscectomy after a two-month evolution. Cells coming from the femur cartilage were isolated by means of collagenase digestion and cultured in a single layer using a DMEM culture medium supplemented with 10% fetal serum, penicilin and streptomycin, hepes and L-cystein (Gibco-BRL®). BrdU incorporation assays were performed by means of an ELISA protocol in order to analyze the proliferation rate. Later, a gene expression analysis was conducted using RT-PCR. The treatment was carried out at a concentration of 50 ng/mL using FGFa, IGF-a, TGF-b (Peprotech Inc) and OP-1 (Stryker) growth factors, and later growth factor combinations FGFa/IGF-1, FGFa/OP-1, FGFa/TGF-b and TGF-b/OP-1.

Results and conclusions: Comparison between the three groups showed that the proliferation rate was lower in older and osteoarthritic cells. These last two groups, however, did not have the same expression pattern as the genes studied. The analysis of the response to growth factors showed that FGFa and IGF-1 were the most efficient ones, and their combination proved to be the most powerful of all.

Purpose: The study looked at different suturing configurations for hamstring reconstruction of the ACL to ensure that all four limbs of the graft were evenly tensioned at the time of insertion.

Method: Calf hoof flexor tendons were used as an animal model for the four strands of a “hamstring” ACL graft. They were sutured together at one end, which was clamped rigidly in a test rig. The free ends were then sutured altogether, in doubles or singly using 2 Ethibond. Miniature Variable Resistance Reluctance Transducers (DVRT) were then inserted into the tendons. The tendon construct was then loaded to 100N in 5N increments (with an initial I5N preload).

One hundred Newtons was decided on as the maximum force following measurements in theatre showing a force of approximately 75N were applied to a hamstring ACL graft at the time of fixation in the tibial tunnel. The DVRT’s allowed accurate assessment of the Load/Displacement of each tendon in the construct to be assessed. Repeatability experiments on the DVRT’s were performed. Ten specimens were prepared which were all tested in the different suturing configurations. Each test was repeated three times on each construct.

Results: The results showed that those tendons sutured all together did not load evenly with only one or two of the tendons in the construct showing any displacement throughout the loading cycle. When sutured as pairs, one of the tendons in each pair showed immediate displacement with the other tendon also showing displacement early in the loading cycle. When sutured individually the tendons all showed evidence of displacement early in the loading cycle, therefore showing more even tensioning and load sharing.

Conclusion: We recommend the use of singly sutured hamstring tendons in ACL reconstruction to allow more even tensioning and load sharing therefore reducing the risk of construct rupturing.