The treatment of acute full thickness chondral damage within the knee is a surgical challenge. Frequently used surgical techniques include chondroplasty, micro-fracture and chondrocyte implantation. These procedures give unpredictable functional outcomes and if the formation of neocartilage is achieved it is predominantly composed of type 1 collagen. The TruFit osteochondral plug was designed to provide a scaffold for cell proliferation into full thickness chondral defects. It is a composite polymer composed of polylactide co-glycolide, calcium sulphate and poly-glycolide fibres. It is composed of 2 layers, one with a similar trabecular network to cancellous bone and a superficial layer designed to simulate articular lining. The TruFit bone plug was analysed using micro-computed tomography. Its morphology characteristics, granulometry, mechanical performance and image guided failure were tested as well as numerical modelling to assess the permeability of TruFit. Morphological parameters of the TruFit bone plug compared favourably with those of human tissue. Under load the scaffold exhibited shear bands throughout the composite leading to a failure mechanism similar to cancellous bone. Stress relaxation rates of the scaffolds were greatly decreased under wet conditions, likely due to plasticisation of the scaffold by water. The biomechanical properties of the TruFit bone plugs are a cause for concern. The Scaffolds mechanical performance under load rapidly deteriorates in wet conditions at body temperature (the natural knee environment). This early failure will lead to defects in the articular surface where the plug has been inserted. Clinical data is sparse. This study correlates with work performed by Dockery et al & Spalding et al. These clinical studies have shown that the TruFit implant shows no evidence of bone ingrowth or osteoconductivity. It provides no subchondral support to neocartilage or tissue that was stimulated to form around the defects and surgical sites

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

In a prospective randomised controlled trial, 51 patients who did not receive a bone plug during total knee replacement surgery were compared to 49 patients who received a bone plug. The primary outcome measure was the need for allogenic blood transfusion requirement and the secondary outcome was the post-operative blood loss and decline in haemoglobin levels. The patients had autologous re-transfusion from their closed drainage system. The two groups did not differ in the demographics. The mean intra-operative blood loss was slightly more in the no plug group (difference of 41.25 millilitres), which was not statistically significant. There was no statistically significant difference in total post-operative blood loss and drop in haemoglobin levels. Only one patient had two units of allogenic blood transfusion in the no bone plug group while none required allogenic blood in the bone plug group. There was no statistically significant difference in the amount of blood re-transfused from the drain between the two groups. Our findings did not show any statistically significant difference in post-operative blood loss, decline in haemoglobin levels and the need for allogenic blood transfusion in total knee replacement surgery

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

This paper reports a series of comparative tests in-vitro that examined how lateral meniscectomy and meniscal allografting affected tibio-femoral joint contact pressures. 8 Cadaver knees (age range 81 – 98 years) were loaded in axial compression in an Instron materials testing machine up to 700N for 10 seconds and pressure maps obtained from the lateral compartment using Fuji Prescale film inserted below the meniscus. This was repeated after meniscectomy, then after meniscal allografting with fixation by a bone plug for the insertional ligaments, plus peripheral sutures. Finally, the pressure when the allograft was secured by peripheral sutures alone was measured. Meniscectomy caused a significant increase in peak contact pressures (p=0.0002). Both of the reconstructive methods reduced the peak contact pressures significantly below that of the meniscectomised knee (p=0.0029 with bone block; p=0.0199 with sutures alone). A significant difference was not found between the peak contact pressures after the reconstructions and that of the intact knee (p=0.1721 with bone block; p=0.0910 with sutures alone). The peak pressures increased slightly when the allografts were converted from bone block to suture-only fixation (p=0.0349). The principal finding was that both of the meniscal allograft insertion techniques reduced the peak contact pressure significantly below that of the meniscectomised knee, so that it did not then differ significantly from the peak contact pressure in the intact knee. When the two fixation methods were compared, the loss of the bone plug attachment caused a small increase in peak pressure. This study suggests that meniscal allografting should have a chondroprotective effect and that there is a small advantage from adding bony fixation to suture fixation

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

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

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

Introduction. Meniscus deficiency leads to the development of early arthritis. Total knee replacement may be the only available treatment option in certain situations. However it is generally best avoided in young patients. We hypothesized that a combination of the two procedures, Allograft Meniscal Transplantation (AMT) and Autologous Chondrocyte Implantation (ACI) would be a solution to treat bone-on-bone arthritis in meniscal deficient knees and postpone the need for a total knee replacement (TKR). Materials/Methods. 12 consecutive patients who underwent both ACI and AMT between 1998 and 2005 were followed up prospectively. The patients were assessed by a self-assessed Lysholm score prior to the procedure and yearly thereafter. All operations were performed by the senior author (JBR). ACI procedure was performed according to the standard technique. Frozen meniscal allograft with bone plugs at either ends secured by sutures in the bone tunnels. Post operatively all patients underwent a strict Oscell Rehabilitation protocol. A repeat procedure or progression to a TKR was taken as a failure. Results. Out of the twelve patients only eleven were included as one had died at three months after surgery. Three patients had delayed TKR, and two were heading towards TKR at 8 years. The median pre-operative lysholm score in the remaining six patients rose from 45 to 64 at last follow up. Conclusions. In our small pilot study there was a 19 point increase in the lysholm score. The combination of ACI & AMT could give a good result defer the need for TKR

A new surgical hybrid technique involving the combination of autologous bone plug(s) and autologous chondrocyte implantation (AOsP-ACI) was used and evaluated as a treatment option in 15 patients for repair of large osteochondral defects in knee (N=12) and hip joints (N=3). Autologous Osplugs were used to contour the articular surface and the autologous chondrocytes were injected underneath a biological membrane covering the plug. The average size of the osteochondral defects treated was 4.5cm. 2. The average depth of the bone defect was 26mm. The patients had a significant improvement in their clinical symptoms at 12 months with significant increase in the Lysholm Score and Harris Hip Score (p = 0.031). The repaired tissue was evaluated using Magnetic Resonance Imaging, Computerised Tomography, arthroscopy, histology and immunohistochemistry (for expression of type I and II collagen). Magnetic Resonance Imaging, Computerised Tomography and histology at 12 months revealed that the bone plug became well integrated with the host bone and repair cartilage. Arthroscopic examination at 12 months revealed good lateral integration of the AOsP-ACI with the surrounding cartilage. Immunohistochemistry revealed mixed fibro-hyaline cartilage. We conclude that the hybrid AOsP-ACI technique provides a promising surgical approach for the treatment of patients with large osteochondral defects. This study highlights the use of this procedure in two different weightbearing joints and demonstrates good early results which are encouraging. The long term results need to be evaluated

Injuries to the infra-patella branch of the saphenous nerve on harvesting Bone-Patella Tendon-Bone (BPB) autograft commonly cause anterior knee pain. The purpose of this study is to investigate the possibility of harvesting a good BPB graft without injury to the nerve by using double mini-incision. Twelve adult cadaveric knees, with two vertical incisions of 25mm, one over the inferior pole of the patella, and the other over the tibial tuberosity were prepared. The tibial bone block was harvested, with preservation of the para-tendon, making a subcutaneous tunnel proximally and stripped to dissect the middle 1/3 of the patella tendon. The graft was then detached after harvesting the patella bone block, and examined for size and quality. The knees were finally dissected to check the relationship of the incisions with the infra-patella branch, and see if it was injured. All BPB grafts were found to have good tendon qualities of average 9.5mm in width. The tibial bone plug is of average 25mm in length and 10mm in width, while the patella bone plug is of average 22mm in length & 9mm in width. All 12 knees have 2 infra-patella branches, with the proximal branch running at averaged distance of 23mm distal to the proximal incision, while the distal branch lying at averaged distance of 11mm proximal to the distal incision. 2 out of the 12 distal branches were injured by the distal incision. Double-mini incision allows harvesting of a consistently good quality BPB graft with preservation of the infra-patella branch of the saphenous nerve

Roentgen stereophotogrammetric analysis (RSA) is the most accurate radiographic technique for the assessment of three-dimensional micromotion in joints. RSA has been used previously to study the kinematics of the anterior cruciate ligament (ACL)-deficient knee and to measure knee laxity after bone-tendon-bone (BTB) reconstructions. There is no published evidence on its use in assessing hamstring grafts in vivo, in comparing hamstring versus BTB reconstruction, or in-depth analyses of graft performance. The aim of this project was to use RSA to measure laxity in both BTB and hamstring reconstructions, and to attempt a detailed analysis of graft behaviour in both reconstructions, with particular attention to graft stretching and slippage of the bony attachments. A prospective study was undertaken on 14 patients who underwent ACL reconstruction. Seven had BTB reconstruction, and seven had four-stranded semitendinosus/gracilis (STG). Tantalum markers were inserted at the time of surgery, into distal femur and proximal tibia, and also directly into the graft itself. Stress radiographs (90N anterior and 90N posterior force) were taken early post-operatively, and then at 6 weeks, and 3, 6 and 12 months. In addition to measuring total anteroposterior knee laxity, a detailed analysis of the graft itself was possible. The BTB grafts had stretched by an average of 1.54%, and the bone plugs had migrated by 0.50 mm at the femoral end and by 0.61mm at the tibial end. The hamstring grafts had stretched on average 3.94%, and the intraosseous ends had migrated by 3.96mm at the femoral end and by 7.10mm at the tibial end. This is believed to be the most detailed application of RSA in analysing the performance of the two commonly used grafts in ACL reconstruction. Details such as graft stretching and fixation slippage have not been available previously; the data obtained in this study may have implications for clinical practice

Introduction. Novel hydrogel implants, TRUFIT® bone plugs, have been developed by Smith & Nephew to replace worn-out cartilage surfaces, restoring mobility and relieving joint pain. There is limited information, however, on the biomechanical properties of the implants. Therefore, appropriate mechanical testing and modelling must be carried out to assess their mechanical properties for load bearing applications. In this study, compressive properties of TRUFIT® bone and dual layer implants were examined under selected physiological loading conditions. The bone layer of the implant was also modelled using a biphasic poroviscoelastic (BPVE) material constitutive law and the results from the model are compared with those from the experiments. Materials and Methods. TRUFIT® CB plugs, with diameters of 11 and 5mm, were sectioned to obtain single layer bone and dual layer samples, with an aspect ratio of 0.86. Specimens were tested in confined and unconfined compressions at two constant strain rates of 0.002/sec (walking) and 0.1/sec (impact) [1-3] on a MTS servo-hydraulic test machine equipped with a bionix envirobath. All samples were tested in phosphate buffered saline (PBS) solution at 37 °C. A preload of 0.1 MPa was applied and preconditioning (10 cycles of 0.008 strain) at a constant strain rate of 0.005 sec. −1. [4] was used. The compressive modulus was calculated from the slope of the linear part of the stress-strain curve. In addition, whilst stress relaxation tests were performed on the bone samples in unconfined compression up to 5% strain, at a strain rate of 0.01/s (running) [1-2]. Biphasic Modelling. The bone implant was modelled as a biphasic poroviscoelastic (BPVE) material assuming constant permeability and linear viscoelasticty. An axisymmetric finite element model of the implant in unconfined compression was built using FEBio [5], with 8-node tri-linear displacement and pore pressure elements. The governing equations for linear BPVE theory are summarized in [6]. Six material coefficients were obtained to describe the model, as shown in Table 1. E and µ are the Young's modulus and Poisson coefficient of the solid matrix; k is the hydraulic permeability; G∗, t. 1. and t. 2. represent the discrete relaxation spectrum magnitude and time relaxation constants used to describe the intrinsic viscoelastic nature of the solid matrix. The Young's modulus of the solid matrix was calculated from the equilibrium stress versus strain in the linear range. The Poisson coefficient of the porous solid matrix was determined also from 3D in situ step-wise compressive tests using Digital Volume Correlation. Permeability measurements were performed, where steady state flow rate versus pressure gradient was measured and the hydraulic permeability was calculated using the Darcy's law. An inverse iterative FE technique was used to identify the remaining coefficients from the stress relaxation experiments. Results & discussion. The compressive moduli are summarized in Fig 1. The preliminary results seem to suggest that strain rate seems to have a dominant effect on compressive modulus. Higher strain rate would always result in higher modulus. On the other hand, the influence of confinement seems to be small. Higher moduli were observed for bones. Smaller sized (5mm) bone samples seem to have a higher modulus at both strain rates. For plugs, significantly higher modulus was found for 5mm samples in walking but similar results were obtained in impact. Fig. 2 shows a typical curve fitting exercise of the BPVE model using the experimentally determined stress relaxation curve (R. 2. =0.95), from which model parameters were obtained. The BPVE model is able to account for the initial, transient and stationary regime of stress relaxation. Moreover, the model is able to reproduce the monotonic unconfined compressive responses at two strain rates (walking and impact), as illustrated in Fig. 3. Acknowledgements. The authors would like to thank Smith & Nephew for providing the samples