The purpose of this study was to determine the incidence of graft-tunnel mismatch (GTM) when performing anatomic anterior cruciate ligament reconstruction (ACLR) using bone-patella tendon-bone (BPTB) grafts and anteromedial portal drilling. Beginning in November 2018, 100 consecutive patients who underwent ACLR by two sports fellowship-trained, orthopedic surgeons using BPTB autograft and anteromedial portal drilling were prospectively identified. The BPTB graft dimensions and the femoral tunnel distance, tibial tunnel distance, intra-articular distance, and total distance were measured. Surgeons determined the depth and angle of tunnels based on the patella tendon graft length dimensions in each case. After passage of the graft, the distance from the distal graft tip to the tibial cortex aperture was measured. GTM was defined as the need for additional measures to obtain satisfactory tibial graft fixation (< 1 5e20 mm of bone fixation). The incidence of mismatch was 6/100 (6%). Five cases involved the graft being too long, with the tibial bone plug protruding excessively from the tibial tunneld4/5 had a patella tendon length ? 50 mm. Three cases were managed with femoral tunnel recession, and two were treated with a free bone plug technique. One patient with a patella tendon length of 35 mm had a graft that was too short, with the tibial bone plug recessed in the tibial tunnel. Of patients whose tibial tunnel distance was within 5 mm of the patella tendon length, only 1/46 (2%) patients had mismatch, whereas 5/54 (9%) of patients who had >5 mm difference had mismatch. The incidence of grafttunnel mismatch after anatomic ACLR using BTPB and anteromedial portal drilling in this study is 6%. To limit the occurrence of GTM where the graft is too long, surgeons should drill tibial tunnel distances within 5 mm of the patella tendon length

Abstract. Aims. Growth disturbances after transphyseal paediatric ACL reconstruction have led to the development of physeal-sparing techniques. However, evidence in their favour remains weak. This study reviews the literature to identify factors associated with growth disturbances in paediatric ACL reconstructions. Materials and Methods. Web of Science, Scopus and Pubmed were searched for case series studying paediatric ACL reconstructions. Titles, abstracts, text, results and references were examined for documentation of growth disturbances. Incidences of graft failures were also studied in these selected studies. Results. 78 studies with 2693 paediatric ACL reconstructions had 70 growth disturbances (2.6%). Of these 17 were varus, 26 valgus, 13 shortening, 14 lengthening and 5 patients had reduced tibial slope. Coronal plane deformities were seen more frequently with eccentric physeal arrest and lengthening with intraepiphyseal tunnelling. Shortening and reduced tibial slope were related to large central physeal arrest and anterior tibial physeal arrest respectively. Extraphyseal technique were least likely to have growth disturbances. 62 studies documented 166 graft failures in 2120 patients (7.83%). Conclusion. Growth disturbances resulting from transphyseal ACL reconstruction can be minimised by keeping drill size small, drilling steep and away from the physeal periphery. Insertion of bone plug, hardware or synthetic material through the drilled physis should be avoided. The evidence to accurately quantify such growth disturbances till skeletal maturity remains weak. Robust long term studies such as national ligament registries may standardise preoperative and postoperative outcome assessment to further characterise the risk of growth disturbance and re-ruptures

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.

Abstract. Introduction. Osteoarthritis (OA) is one of the lead causes of pain and disability in adults. Bone marrow lesions (BMLs) are one feature of subchondral bone involvement in OA. MRI images suggest changes in tissue content and properties in the affected regions however, it is not known if this alters the mechanical behavior of the bone, which could in turn affect OA progression. The aim of this study was to characterize the mechanical properties of BMLs, using a combined experimental and computational approach. Methods. Six human cadaveric patellae from donors aged 56–76 were used in this study; all exhibited BML regions under MRI. Bone plugs were taken from non-BML (n = 6) and BML (n = 7) regions within the patellae, with guidance from the MRI. The plugs were imaged at 82µm resolution using micro computed tomography (µCT) and tested under uniaxial compression. Finite element (FE) models were created for each plug from the µCT scans and morphological properties such as bone volume fraction (BV/TV) were also determined. The relationship between bone volume fraction and apparent modulus was investigated for both sample groups. Results. The BV/TV range was similar for the BML and non-BML groups (0.25–0.46 and 0.18–0.44) From the experimental tests, a moderate positive correlation was found between BV/TV and apparent modulus in the no BML group (r= 0.57) while no correlation was found in the BML group (r = −0.02). From the FE results, a different relationship between BV/TV and element elastic modulus was found for the BML and non-BML groups. Conclusions. The results of this study show that in regions of bone containing BMLs, bone volume fraction does not predict overall apparent modulus and has different relationship to local modulus, suggesting the BML associated tissue structural changes affect mechanical behavior. Funders: EPSRC

Aims

The main objective of this study is to analyze the penetration of bone cement in four different full cementation techniques of the tibial tray.

Bone-patellar tendon-bone autografts, hamstring autografts or allografts are widely used grafts for ACL revision surgeries. Also use of quadriceps autograft for both primary and revision ACL surgeries is in an increasing popularity due to its biomechanical superior properties and less donor site morbidity. However, although several fixation techniques and devices for quadriceps tendon graft fixation on femoral side have been reported, literature lacks about biomechanical studies comparing properties of these different fixation techniques and devices. We aimed to investigate whether there is a difference between the fixation techniques of quadriceps tendon graft by using different fixation techniques and devices on the femoral side in terms of stiffness and amount of slippage in the tunnel. Full-thickness central parts of quadriceps tendons from paired knees of twenty five calf knees were fixed through a 10mm x 25mm tunnel in twenty five paired sheep femurs. Quadriceps tendon patellar side with soft tissue ending fixed with four different fixation devices (adjustable suspensory system (group 1), absorbable interference screw (group 2), titanium interference screw (group 3) and adjustable suspensory system + absorbable interference screw (group 4)) and quadriceps tendon with a patellar bone plug fixed with a titanium interference screw (group 5) were tested in a servohydraulic materials testing machine. 10 samples were included in each group. After applying a preload of 10 N, a cyclic force was applied for 20 cycles from 10N to 110N at a 1 hertz frequency. Amount of slippage in the tunnel was calculated as the difference measured in millimeters between length at 10 N after 20 cycles and starting length at 10 N (Graph 1). To determine the stiffness, a single load-to-failure cycle was performed at a strain rate of 20 mm/min as the last step (Figure 1). Rupture of the graft was not seen in any of the samples. Median values of amount of slippage in the tunnel were 6,41mm, 5,99mm, 3,01mm, 4,83mm, and 3,94mm respectively. Median values of maximum load at failure were 464N, 160N, 350N, 350N and 389N respectively. Amount of slippage in the tunnel was highest in the group 1 and was lowest in the group 3 (p<0.001). Group 1 was found to be most resistant group against load-to-failure test and group 2 was the weakest (p<0.001). However inter-group analyses between group 3 and 5 revealed that, although group 3 had the least slippage in the tunnel, group 5 was better in terms of stiffness, but there was no statistically significant difference (p=0,124 and 0,119 respectively). There was a significant difference between group 2 and 3 in both amount of slippage in the tunnel and stiffness (p=0,001 and 0.028 respectively)(Table 1). Our study revealed that, although quadriceps graft with a bone plug fixed with metal interference screws is widely presumed to be a stable fixation technique, there was no significant difference in terms of stiffness when compared with quadriceps graft with soft tissue ending fixed with a metal interference screw. Although adjustable suspensory device group was the best in the terms of resistance against load-to-failure, it was the worst in terms of amount of slippage from the tunnel. Thus, if a suspensory device is to be used, it must be kept in mind that a strong 20 cycles of intra-operative tension force must be applied to prevent further slippage of the graft in the tunnel which can result in failure of reconstruction. For any figures or tables, please contact the authors directly

Aims

Metaphyseal cones with cemented stems are frequently used in revision total knee arthroplasty (TKA). However, if the diaphysis has been previously violated, the resultant sclerotic canal can impair cemented stem fixation, which is vital for bone ingrowth into the cone, and long-term fixation. We report the outcomes of our solution to this problem, in which impaction grafting and a cemented stem in the diaphysis is combined with an uncemented metaphyseal cone, for revision TKA in patients with severely compromised bone.

Decellularised extracellular matrix scaffolds show great promise for the regeneration of damaged musculoskeletal tissues (cartilage, ligament, meniscus), however, adequate fixation into the joint remains a challenge. Here, we assess the osseo-integration of decellularised porcine bone in a sheep model. This proof-of-concept study supports the overall objective to create composite decellularised tissue scaffolds with bony attachment sites to enable superior fixation and regeneration. Porcine trabecular bone plugs (6mm diameter, 10mm long) were decellularised using a novel bioprocess incorporating low-concentration sodium dodecyl sulphate with protease inhibitors. Decellularised bone scaffolds (n=6) and ovine allograft controls (n=6) were implanted into the condyle of skeletally mature sheep for 4 and 12 weeks. New bone growth was visualised by oxytetracycline fluorescence and standard resin semi-quantitative histopathology. Scaffolds were found to be fully decellularised and maintained the native microarchitecture. Following 4-week implantation in sheep, both scaffold and allograft appeared well integrated. The trabecular spaces of the scaffold were filled with a fibro-mesenchymal infiltrate, but some areas showed a marked focal lymphocytic response, associated with reduced bone deposition. A lesser lymphocytic response was observed in the allograft control. After 12-weeks the lymphocytic reaction was minimised in the scaffold and absent in allografts. The scaffold showed a higher density of new mineralized bone deposition compared to allograft. New marrow had formed in both the scaffold and allografts. Following the demonstration of osteointegration this bioprocess can now be transferred to develop decellularised composite musculoskeletal tissue scaffolds and decellularised bone scaffolds for clinical regeneration of musculoskeletal tissues

Osteoarthritis is a debilitating disease affecting over 1.7 million people in the UK annually. Total ankle replacements are an increasingly sought option for repairing a late stage arthritic ankle, but result in the removal of significant portions of bone regardless of tissue quality. Hence, the mapping of bone quality would allow the use of targeted treatments at earlier stages of the disease. This study aims to develop characterisation methodologies using porcine tissue to investigate the mechanical properties of subchondral bone in the ankle. N=11 talar bone plugs (6mm diameter) were extracted from porcine ankles and embedded into Delrin endcaps using a thin layer of PMMA cement. These were scanned under micro-CT (16 microns) and subjected to quasi-static uniaxial compression to determine apparent stiffness for each specimen. Specimen-specific continuum FE models were developed, with material properties derived from the greyscale value of the underlying image. A python-based least squares regression (Opti4Abq, N=6) was used to minimise the difference between experimental and model stiffness values, to determine the coefficient linking greyscale and mechanical properties. Apparent stiffness, elastic modulus and compressive strength were compared to BV/TV, which was derived using BoneJ (a bone image plugin for the NIH ImageJ). The results show positive correlations between BV/TV and compressive strength, stiffness and Young's modulus. Average BV/TV across all samples was 0.45. Average experimental and computational stiffness were 986N/mm and 891 N/mm respectively. A 21.8% RMS error was found using the validation set (N=5), which was of similar order to the calibration set. Some specimens saw issues with misalignment of the specimen faces and the loading platens, likely causing overestimation of mechanical properties. This study has developed methods that can be translated for use with human ankle bone and will lead to the development of an accurate means of mapping arthritic bone in the ankle

Objectives

We studied subchondral intraosseous pressure (IOP) in an animal model during loading, and with vascular occlusion. We explored bone compartmentalization by saline injection.

INTRODUCTION. Avascular necrosis (AVN) of the femoral head (FH) initiates from biological disruptions in the bone and may progress to mechanical failure of the hip. Mechanical and structural properties of AVN bone have not been widely reported, however such understanding is important when designing therapies for AVN. Brown et al.[1] assessed mechanical properties of different regions of AVN FH bone and reported 52% reduction in yield strength and 72% reduction in elastic modulus of necrotic regions when compared to non-necrotic bone. This study aimed to characterise structural and mechanical properties of FH bone with AVN and understand the relationship between lesion volume and associated mechanical properties. METHODS. Twenty FH specimens from patients undergoing hip arthroplasty for AVN and six non-pathological cadaveric FH controls were collected. Samples were computed tomography scanned and images analysed for percentage lesion volume with respect to FH volume. Samples were further divided for structural and mechanical testing. The mechanical property group were further processed to remove 9mm cylindrical bone plugs from the load bearing and non-load-bearing regions of the FHs. FH and bone plug samples were tested in compression (1mm/min); elastic modulus and yield stress were calculated. RESULTS. Imaging. Individual lesion size within AVN FHs varied: multiple small lesions or small numbers of large lesions were present in all FHs. Mean lesion volume percentage for AVN FHs was significantly greater than control FHs (p30% total FH volume. Structural Properties: The mean elastic modulus for AVN FHs was 15% lower than that of control FHs and mean yield stress was 4% lower than that of control FHs, however this difference was not significant. Mechanical Properties. The mean elastic modulus and yield stress of bone plugs from the load-bearing regions of AVN FHs were significantly lower than those of control samples (79% and 77% respectively; p<0.05, Kruskal-Wallis), however, for non-load-bearing samples, mean elastic modulus and yield stress of AVN FHs were significantly higher than control samples (by 153% and 123% respectively; p<0.05, Kruskal-Wallis). DISCUSSION. Although mechanical properties of bone in load-bearing regions of AVN FHs were significantly less than those of control FHs, replicating previous findings by Brown et al. (1981, CORR. 156, 240-7), mechanical properties in the non-load bearing regions were increased. This may be due to adaptation of the non-load bearing region to support loads following AVN in normally load bearing regions, or due to the presence of denser sclerotic tissue. In this study, necrotic bone samples demonstrated smaller changes in mechanical properties in the load-bearing region with respect to those regions in the control samples than previously reported by Brown et al.. This may be due to differences in experimental methods (e.g. patient demographics, quality of control bone samples, loading rate, and location of samples) or due to the disease stage of the AVN FHs from which tissues were taken. In addition, this study has demonstrated that necrotic lesions are not consistent in quantity, size and location

Aims

Our aim in this study was to describe a continuing review of 11 total hip arthroplasties using 22.225 mm Alumina ceramic femoral heads on a Charnley flanged femoral component, articulating against a silane crosslinked polyethylene.

The current study aims to ascertain the outcome of ACI with simultaneous transplantation of an autologous bone plug for the restoration of osteoarticular defects in the femoral condyle of the knee (‘Osplug’ technique). Seventeen patients (mean age of 27±7 years), twelve with Osteochondritis dissecans (OD) and five with an osteochondral defect (OCD) was treated with unicortical autologous bone graft combined with ACI (‘Osplug’ technique). Functional outcome was assessed with Lysholm scores obtained for 5 years post-operatively. The repair site was evaluated with the Oswestry Arthroscopy Score (OAS), MOCART MRI score and ICRS II histology score. The mean defect size was 4.5±2.6 SD cm² and mean depth was 11.3±5 SD mm. A significant improvement of Lysholm score from 45 (IQR 24, range 16–79) to 77 (IQR 28, range 41–100) at 1 year (p-value 0.001) and 70 (IQR 35, range 33–91) at 5 years (p-value 0.009). The mean OAS of the repair site was 6.2 (range 0–9) at a mean of 1.3 years. The mean MOCART score was 61 ± 22SD (range 20–85) at 2.6 ± 1.8SD years. Histology demonstrated generally good integration of the repair cartilage with the underlying bone. Poor lateral integration of the bone graft on MRI and low OAS were significantly associated with a poor outcome and failure. The Osplug technique shows significant improvement of functional outcome for up to 5 years. This is the first report describing the association of bone graft integration with functional outcome after such a procedure

Background

Structural and functional outcome of bone graft with first or second generation autologous chondrocyte implantation (ACI) in osteochondral defects has not been reported.

Objectives

Favourable results for collarless polished tapered stems have been reported, and cement creep due to taper slip may be a contributing factor. However, the ideal cement thickness around polished stems remains unknown. We investigated the influence of cement thickness on stem subsidence and cement creep.

The ability to pre-clinically evaluate new cartilage substitution therapies in viable physiological biotribological models, such as the femoral-tibial joint would be advantageous. Methods for osteochondral (OC) plug culture have been developed and the aim of this study was to extend these methods to organ culture of whole femoral condylar and tibial osteochondral tissues. Porcine femoral condyles and tibial plateau were aseptically dissected. The majority of cancellous bone was removed leaving intact cartilage and a layer of cortical bone. OC plugs were from porcine knee condyles. “Whole joint” tissues and OC plugs were cultured in defined medium and the viability of the cartilage at day 0, 8 or 14 days of culture assessed by XTT assay and LIVE/DEAD staining. Histological analysis (H&E; alcian blue staining) was used to determine cell number and visualise glycosominoglycans (GAGs). GAG levels were quantified in the cartilage using the dimethylene blue assay. XTT conversion by OC plug cartilage reduced significantly between day 0 and day 8 with no further change between day 8 and 14. GAG levels did not change. “Whole joint” tissue behaved similarly with reduced XTT conversion between days 0 and 8 (femoral only) and days 0 and 14 (femoral and tibial). LIVE/DEAD staining showed the majority of cells remained alive in the mid and deep cartilage zones. There was a band of mainly dead cells in the surface zone, from day 0. There was no change in the GAG levels over the 14 day culture period. In conclusion, large cuts of femoral and tibial osteochondral tissues were maintained in organ culture for extended periods. Surface zone chondrocytes rapidly lost membrane integrity ex-vivo whereas mid- and deep zone chondrocytes remained viable. It is hypothesised that physiological loading in a novel physically interactive bioreactor will improve the viability and will be the focus of future studies

Objectives

Studies reporting specifically on squeaking in total hip arthroplasty have focused on cementless, and not on hybrid, fixation. We hypothesised that the cement mantle of the femur might have a damping effect on the sound transmitted through the metal stem. The objective of this study was to test the effect of cement on sound propagation along different stem designs and under different fixation conditions.

Background. Cement restrictors are used for maintaining good filling and pressurization of bone cement during hip and knee arthroplasties. The limitations of certain cement restrictors include the inability to accommodate for large medullary canals particularly in revision procedures. We describe a technique using SurgicelTM (Johnson & Johnson) and SPONGOSTAN™ (Johnson & Johnson) (Fig 1) to form a cement restrictor that can accommodate for large canal diameters and provide excellent pressurisation. Technique. The technique involves the application of SPONGOSTAN™ (Johnson & Johnson) foam onto a SurgicelTM (Johnson & Johnson) mesh which is then rolled onto the SPONGOSTAN™ foam forming a uniform cylindrical structure Figs 2,3. The diameter of the restrictor can be adjusted according to the desired femoral canal diameter through increasing the thickness of the SPONGOSTAN™ (Johnson & Johnson) foam. The restrictor is then inserted into the desired position in the medullary canal where it expands uniformly creating an effective restrictor and bone plug Fig 4. Bone cement is then applied and pressurisation commenced prior to the insertion of the implant Fig5. SPONGOSTAN™ is an absorbable haemostatic sponge intended for haemostatic use by applying to a bleeding surface. It consists of a sterile, water-insoluble, malleable, porcine gelatin absorbable sponge. Surgicel ™ is an absorbable hemostatic agent composed of oxidized regenerated cellulose. It is a sterile, absorbable knitted fabric that is flexible and adheres readily to bleeding surfaces. Both products are routinely used for their haemostatic properties in various surgical disciplines. Discussion. The use of intramedullary plugs in cemented total joint arthroplasty is essential in order to achieve good filling and pressurization in hip and knee arthoplasties, traditionally, a small piece of bone or a cement restrictor may be used to plug the shaft. Distal plugs seal the femoral canal, improve fixation and prevent bone cement from leaking during delivery and pressurization. Plugging the intramedullary canal during total hip arthroplasty increases penetration of cement into cancellous bone proximal to the intramedullary plug. Numerous plug designs and materials are available ranging from non-resorbable to resorbable. Regardless of design, all restrictors should avoid intramedullary cement leakage and plug migration during cement and stem insertion to ensure adequate intramedullary pressures. In some instances the diameter of the femoral canal is too wide to accommodate a conventional cement restrictor particularly when crossing the femoral isthmus and even more so in revision procedures requiring the implantation of long stemmed cemented components. The use of the Surgicel-Spongostan haemostatic restrictor overcomes some of the limitations of a standard cement restrictors. These include the ability to bypass a narrow femoral isthmus, accommodate large femoral canals, particularly in revision procedures, and the flexibility of adjusting the restrictor to the desired diameter of the medullary canal and in effect providing a bespoke cement restrictor. This technique was used successfully in over 300 revision hip and knee procedures with no adverse effects and excellent outcomes

Transverse pin femoral fixation of bone-patella tendon-bone (BPTB) in ACL reconstruction has been widely applied during the last decades. Aim of our study is to confront two different system of transverse femoral fixation for BPTB graft: Transfix BTB (Arthrex) and BioTransfix T3 (Arthrex). The main differences between these two system are the diameter (3.0 mm Transfix BTB and 3.5 mm BioTransfix T3), and section (Transfix BTB is cannulated). Surgical technique adopts the same transverse vectorial guide but different guide sleeves. 30 fresh-frozen porcine knees (mean age 2.2 years) were assigned to the two groups randomisedly. the patellar bone block and tendon were harvested using the same size in all specimens (10mm × 25 mm, 10 mm). Zwick-Roell z010 tension/compression device with bone clamps, was used for the study:. Cyclic test (1000 cycles, 0.5 Hz, 50–250 N/cycle, 100 cycles of preload). Final pull-out test (1 mm/s). Failure analysis. CT scan and densitometry. Any implant didn't fail during cyclic test. The elongation average was 1.85±0.63 for Transfix BTB and 1.69±0.87 for BioTransfix T3. Pull-out test showed very similar values in terms of Ultimate Strength Failure (USF), Stiffness at USF, and Stiffness:. The failure mode was bone plug fracture (12 for Transfix BTB and 13 for BioTransfix T3) and tendon failure (3 for Transfix BTB and 2 for BioTransfix T3). The post-test CT scan showed any failure of the fixation devices and the correct position inside the femoral half-tunnel. The mean bone density of porcine femora was comparable to young human femora (1.12±0.31 BMD). Both systems showed a similar behaviour in terms of USF, Stiffness, Cyclic load, method of failure and other biomechanical parameters. The reproducibility of surgical technique, the mechanical strength and endurance of the systems suggest two valid options for ACL reconstruction with BPTB even if in-vivo studies are necessary to confirm the animal ex-vivo biomechanical data