Aims

Aseptic loosening is a leading cause of uncemented arthroplasty failure, often accompanied by fibrotic tissue at the bone-implant interface. A biological target, neutrophil extracellular traps (NETs), was investigated as a crucial connection between the innate immune system’s response to injury, fibrotic tissue development, and proper bone healing. Prevalence of NETs in peri-implant fibrotic tissue from aseptic loosening patients was assessed. A murine model of osseointegration failure was used to test the hypothesis that inhibition (through Pad4^-/- mice that display defects in peptidyl arginine deiminase 4 (PAD4), an essential protein required for NETs) or resolution (via DNase 1 treatment, an enzyme that degrades the cytotoxic DNA matrix) of NETs can prevent osseointegration failure and formation of peri-implant fibrotic tissue.

Abstract. Objectives. Over 1% of the global population suffers with ankle osteoarthritis (OA), yet there is limited knowledge on the changes to subchondral bone with OA. In other joints, it has been shown that bone becomes osteosclerotic, with fewer, thicker trabeculae that become hypomineralised, causing an increased apparent bone volume fraction (BV/TV). Microstructural alterations reduce overall joint strength, which may impact the success of late-stage surgical interventions, such as total ankle arthroplasty (TAA). Previous ankle studies have evaluated changes to cartilage, bone plate and bone morphology with OA, hence this study aimed to characterise changes to trabecular architecture. Methods. Three ankle joints were isolated from non-diseased cadaveric feet (three males: 43, 50 and 57 years, MEEC 18-027). Cylindrical subchondral bone specimens (N=6, 6.5 mm Ø) were extracted from the tibial plafond. Osteoarthritic bone samples (N=6, distal tibia) were sourced from local patients (three males: 65, 58 and 68 years, NREC 07/Q1205/27) undergoing TAA surgery. Specimens were imaged using µCT at a 16 µm isotropic resolution (µCT-100 ScanCo Medical). Virtual cores of bone (6.5 mm Ø) were extracted from the image data of the osteoarthritic specimens and trimmed to a height of 4 mm. BoneJ was used to evaluate key morphological indices: BV/TV; anisotropy (DA); trabecular thickness (Tb.Th); trabecular density (Conn.D) and ellipsoid factor (EF) which characterises rod/plate geometry. Differences between the two groups of specimens were evaluated using a t-test with Bonferroni correction. Results. Significant increases in BV/TV and Tb.Th (p<0.01) were observed with OA compared to non-diseased. Differences in EF showed a shift to more rod-dominated structure with OA, but this was not significant. No significant differences to DA and Conn.D were observed. Conclusions. The results of this study agree with trends observed in other OA joints, but would benefit from a larger sample size. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Aims

We have evaluated the survivorship, outcomes, and failures of an interlocking, reconstruction-mode stem-sideplate implant used to preserve the native hip joint and achieve proximal fixation when there is little residual femur during large endoprosthetic reconstruction of the distal femur.

Aims

To determine whether half-threaded screw holes in a new titanium locking plate design can substantially decrease the notch effects of the threads and increase the plate fatigue life.

Aims

Fixation of osteoporotic proximal humerus fractures remains challenging even with state-of-the-art locking plates. Despite the demonstrated biomechanical benefit of screw tip augmentation with bone cement, the clinical findings have remained unclear, potentially as the optimal augmentation combinations are unknown. The aim of this study was to systematically evaluate the biomechanical benefits of the augmentation options in a humeral locking plate using finite element analysis (FEA).

Aims

The aim of this study is to report the results of a case series of olecranon fractures and olecranon osteotomies treated with two bicortical screws.

Objectives

Legg–Calvé–Perthes’ disease (LCP) is an idiopathic osteonecrosis of the femoral head that is most common in children between four and eight years old. The factors that lead to the onset of LCP are still unclear; however, it is believed that interruption of the blood supply to the developing epiphysis is an important factor in the development of the condition.

Objectives

This study aims to evaluate if micro-CT can work as a method for the 3D assessment and analysis of cancellous bone by comparing micro-CT with undecalcified histological sections in OVX rats.

Aims

Fractures of the distal femur are an important cause of morbidity. Their optimal management remains controversial. Contemporary implants include angular-stable anatomical locking plates and locked intramedullary nails (IMNs). We compared the long-term patient-reported functional outcome of fixation of fractures of the distal femur using these two methods of treatment.

Introduction. Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmental dysplasia. However, it is a technically demanding surgery with several critical issues, including graft resorption, graft collapse, and cup loosening. The purpose of this study is to describe our new bone grafting technique and review the radiographic and clinical results. Patients and Methods. We retrospectively reviewed 105 hips in 89 patients who had undergone covered bone grafting (CBG) in total hip arthroplasty for developmental dysplasia. We excluded patients who had any previous surgeries or underwent THA with a femoral shortening osteotomy. According to the Crowe classification, 6 hips were classified as group I, 39 as group II, 40 as group III, and 20 as group IV. Follow-up was at a mean of 4.1 (1 ∼ 6.9) years. The surgery was performed using the direct anterior approach. The acetabulum was reamed as close to the original acetabulum as possible. The pressfit cementless cup was impacted into the original acetabulum. After pressfit fixation of the cup was achieved, several screws were used to reinforce the fixation. Indicating factor for using CBG was a large defect where the acetabular roof angle was more than 45 degrees and the uncovered cup was more than 2 cm (Fig.1). The superior defect of the acetabulum was packed with a sufficient amount of morselized bone using bone dust from the acetabular reamers. Then, the grafted morselized bone was covered with a bone plate from the femoral head. The bone plate was fixed with one screw to compact the morselized bone graft. The patient was allowed to walk bearing full weight immediately after surgery. We measured the height of the hip center from the teardrop line and the pelvic height on anteroposterior roentgenograms of the pelvis and calculated the ratio of the hip center to the pelvic height. We defined the anatomical hip center as the height of the center less than 15 % of the pelvic height, which was nearly equal to 30 mm, because the mean pelvic height was 210 mm. Results. The mean height of the hip center was 9.8 (4.1∼18.0) % of the pelvic height and the 101 (96.2%) cups were placed within the anatomical hip center. Radiographically, in all patients, the host-graft interface became distinct and the new cortical bone in the lateral part of the plate bone appeared within 1 year after surgery (Fig.2, 3). We observed no absorption of the plate bone graft and no migration of the cup at the last follow-up. Conclusion. CBG technique is simple, because the bone graft is always performed after the pressfit of the cup is achieved. Moreover, patients require no partial weight bearing postoperatively, because the cup is supported by the host bone with the pressfit and additional screws. The CBG technique would be an excellent option for the reconstruction of the acetabulum in patients with severe dysplasia to avoid a high hip center and bulky bone grafting

Acetabular reconstruction of extensive bone defect is troublesome in revision total hip arthroplasty (rTHA). Kerboull or Kerboull type reinforcement acetabular device with allobone grafting has been applied since 1996. Clinical results of the procedure were evaluated. Patients. One hundred and ninety-two consecutive revision total hip arthroplasties were performed with allograft bone supported by the Kerboull or Kerboull type reinforcement acetabular device from 1996 to 2009. There were 23 men and 169 women. Kerboull plates were applied to 18 patients, and Kerboull type plates to 174. The mean follow up of the whole series was 8 years (4–18years). Surgical Technique. The superior bone defect was reconstructed principally by a large bulky allo block with plate system. Medial bone defect was reconstructed by adequate bone chips and/or sliced bone plates. After temporally fixation of bulky bone block with two 2.0mm K-wires, it was remodeled by reaming to fit the gap between host bone and plate, followed by fixation to the iliac bone by screws. Finally, residual space of the defect between host bone and the fixed plated was filled up with morselized cancellous bones, bone chips, and/or wedged bony fragments with impaction. This method was sufficiently applicable to AAOS Typeâ�, II, and III bone defects. In case of AAOS Typeâ�£, the procedure was also available after repairing discontinuation between distal and proximal bones by reconstrusion plate or allografting with tibial bone plates or sliced femoral head. Results. Nine patients (4.7%) required revision surgery (infection 5, breakage 3, and malalignment 1). The plate breakage was observed in 8 joints (4.2%). Three patients had no symptoms after the breakage. Three required revision, but the other cases were carefully observed without additional surgical intervention. Ten-year survival rate by Kaplan-Meier method was 96.6% when the endpoint was set revision by asceptic loosning. Conclusions. This study indicated that acetabular allograft reconstructions reinforced by Kerboull or Kerboull type acetabular device were able to recover bone stock with anatomic reconstruction of femoral head center, thus providing satisfactory clinical results in middle term period

We hypothesised that the removal of the subchondral bone plate (SCBP) for cemented acetabular component fixation in total hip arthroplasty (THA) offers advantages over retention by improving the cement-bone interface, without jeopardising implant stability. We have previously published two-year follow-up data of a randomised controlled trial (RCT), in which 50 patients with primary osteoarthritis were randomised to either retention or removal of the SCBP. The mean age of the retention group (n = 25, 13 males) was 70.0 years (sd 6.8). The mean age in the removal group (n = 25, 16 males) was 70.3 years (sd 7.9). Now we have followed up the patients at six (retention group, n = 21; removal group, n = 20) and ten years (retention group: n = 17, removal group: n = 18), administering clinical outcome questionnaires and radiostereometric analysis (RSA), and determining the presence of radiolucent lines (RLLs) on conventional radiographs. RSA demonstrated similar translation and rotation patterns up to six years. Between six and ten years, proximal acetabular component migration and changes of inclination were larger in the retention group, although the mean differences did not reach statistical significance. Differences in migration were driven by two patients in the SCBP retention group with extensive migration versus none in the SCBP removal group. The significant difference (p < 0.001) in the development of radiolucent lines in the retention group, previously observed at two years, increased even further during the course of follow-up (p < 0.001). While recognising SCBP removal is a more demanding technique, we conclude that, wherever possible, the SCBP should be removed to improve the cement–bone interface in order to maximise acetabular component stability and longevity.

Cite this article: Bone Joint J 2015;97-B:35–44.

Cartilage repair in terms of replacement, or regeneration of damaged or diseased articular cartilage with functional tissue, is the ‘holy grail’ of joint surgery. A wide spectrum of strategies for cartilage repair currently exists and several of these techniques have been reported to be associated with successful clinical outcomes for appropriately selected indications. However, based on respective advantages, disadvantages, and limitations, no single strategy, or even combination of strategies, provides surgeons with viable options for attaining successful long-term outcomes in the majority of patients. As such, development of novel techniques and optimisation of current techniques need to be, and are, the focus of a great deal of research from the basic science level to clinical trials. Translational research that bridges scientific discoveries to clinical application involves the use of animal models in order to assess safety and efficacy for regulatory approval for human use. This review article provides an overview of animal models for cartilage repair.

Cite this article: Bone Joint Res 2014;4:89–94.

Little is known about the long-term outcome of mobile-bearing total ankle replacement (TAR) in the treatment of end-stage arthritis of the ankle, and in particular for patients with inflammatory joint disease. The aim of this study was to assess the minimum ten-year outcome of TAR in this group of patients.

We prospectively followed 76 patients (93 TARs) who underwent surgery between 1988 and 1999. No patients were lost to follow-up. At latest follow-up at a mean of 14.8 years (10.7 to 22.8), 30 patients (39 TARs) had died and the original TAR remained in situ in 28 patients (31 TARs). The cumulative incidence of failure at 15 years was 20% (95% confidence interval (CI) 11 to 28). The mean American Orthopaedic Foot and Ankle Society (AOFAS) ankle–hindfoot score of the surviving patients at latest follow-up was 80.4 (95% CI 72 to 88). In total, 21 patients (23 TARs) underwent subsequent surgery: three implant exchanges, three bearing exchanges and 17 arthrodeses. Neither design of TAR described in this study, the LCS and the Buechel–Pappas, remains currently available. However, based both on this study and on other reports, we believe that TAR using current mobile-bearing designs for patients with end-stage arthritis of the ankle due to inflammatory joint disease remains justified.

Cite this article: Bone Joint J 2013;95-B:1656–61.

Fracture repair occurs by two broad mechanisms: direct healing, and indirect healing with callus formation. The effects of bisphosphonates on fracture repair have been assessed only in models of indirect fracture healing.

A rodent model of rigid compression plate fixation of a standardised tibial osteotomy was used. Ten skeletally mature Sprague–Dawley rats received daily subcutaneous injections of 1 µg/kg ibandronate (IBAN) and ten control rats received saline (control). Three weeks later a tibial osteotomy was rigidly fixed with compression plating. Six weeks later the animals were killed. Fracture repair was assessed with mechanical testing, radiographs and histology.

The mean stress at failure in a four-point bending test was significantly lower in the IBAN group compared with controls (8.69 Nmm^-2 (sd 7.63) vs 24.65 Nmm^-2 (sd 6.15); p = 0.017). On contact radiographs of the extricated tibiae the mean bone density assessment at the osteotomy site was lower in the IBAN group than in controls (3.7 mmAl (sd 0.75) vs 4.6 mmAl (sd 0.57); p = 0.01). In addition, histological analysis revealed progression to fracture union in the controls but impaired fracture healing in the IBAN group, with predominantly cartilage-like and undifferentiated mesenchymal tissue (p = 0.007).

Bisphosphonate treatment in a therapeutic dose, as used for risk reduction in fragility fractures, had an inhibitory effect on direct fracture healing. We propose that bisphosphonate therapy not be commenced until after the fracture has united if the fracture has been rigidly fixed and is undergoing direct osteonal healing.

Cite this article: Bone Joint J 2013;95-B:1263–8.

Hyaline articular cartilage has been known to be a troublesome tissue to repair once damaged. Since the introduction of autologous chondrocyte implantation (ACI) in 1994, a renewed interest in the field of cartilage repair with new repair techniques and the hope for products that are regenerative have blossomed. This article reviews the basic science structure and function of articular cartilage, and techniques that are presently available to effect repair and their expected outcomes.

Objectives

Small animal models of fracture repair primarily investigate indirect fracture healing via external callus formation. We present the first described rat model of direct fracture healing.

Bone fixation plates are routinely used in corrective and reconstructive interventions. Design of such implants must take into consideration not only good surface fit, but also reduced intra-operative bending and twisting of the implant itself. This process increases mechanical stresses within the implant and affects its durability and the functional outcome of the surgery. Wound exposure and anaesthesia times are also reduced. Current population-based designs consider the average shape of a target bone as a template to pre-shape the implant. Other studies try to enhance the average design by optimising surface metrics in a statistical shape space. This could ensure a low mean distance between the implant and any bone in the population, but does not reduce neither the maximum possible distances nor directly the mechanical forces needed to fit the implant to the specific patient. We propose a population-based study that considers the bending and torsion forces as metrics to be minimised for the design of enhanced fixation plates. Our aim is to minimise the necessary intra-operative deformations of the plates. In our approach, we first propose to represent a fixation plate by dividing it into discrete sections lengthwise and fitting a plane to each section. The number of sections depends on the size of the implant and anatomical location. It should be small enough to capture the anatomical curvatures, but large enough not to be affected by local noise in the surface. Surface patches corresponding to common locations for plate fixations are extracted from 200 segmented computed tomography (CT) images. In this work, distal lateral femoral patches are considered. A statistical shape model of the patches is then computed and a large population of 2,197 instances is generated, evenly covering the natural statistical variation within the initial population. These instances are considered as both bone surfaces and potential new designs of the contact surface of the fixation plate. The key formulation of our solution is to examine the effect of deforming each section of the implant on the rest of the sections and compute the amount of bending and torsion needed to shape one patch to another. Each instance of the population is fitted to all others and the maximum bending and torsion angles are recorded. A similar process was applied for the mean of the population. The goal is to pick from the population the shape that simultaneously minimises the bending and torsion angles. The maximum required bending was reduced from 25.3® to 19.3® (24.72% reduction), whereas the torsion component was reduced from 12.4® to 6.2® (50% reduction). The method proposed in this abstract enhances the current state-of-the-art in orthopaedic implant design by considering the mechanical deformations applied to the implant during the surgery. The obtained results are promising and indicate a noticeable improvement over the standard pre-contouring to the population mean. We plan to further validate the method and as a future outlook, we intend to test the approach in real surgical scenarios

In the last years custom-fit cutting guides using magnetic resonance imaging (MRI) were introduced by orthopedic surgeons for total knee arthroplasty (TKA). One of the advantages of these shape-fitting jigs is the possibility to transfer the preoperative planning of the TKA directly to the individual patient's bone. However, one has to be aware, that the jigs are designed for single-use and have to be custom made by an external manufacturer. This increases the cost of implantation and unlinks the surgeon from this process. In addition a potentially necessary adjustment of the preoperatively planned implant size and position in a surgical situation is not possible. The purpose of our development was to combine the advantages of custom-fit cutting guides as a 3-D-computer-assisted planning tool with the option to adjust and improve the preoperative planning and the jig in the actual surgical situation. In addition no outside jig manufacturing would occur in this concept. This leaves the surgeon in control of the entire process. The purpose of this study was to examine the reliability of this screw-based shape – fitting system. In order to do this we assessed the inter- and intra-observer reliability of the recurrent placement of the plate on a set of bone samples with preset screws. We developed a plate with the dimension of 66 × 76 × 10 mm, containing 443 threaded holes. A connector for further instrumentation is mounted on the proximal part of the plate,. As the plate and the screws are made of aluminum and steel, sterilization is possible. After computer tomography (CT) scans were taken from three human femoral bones, eight to nine variably positioned screws (50.45 mm length, 2.75 mm diameter), reversibly fixed by locknuts, formed an imprint of a bone's surface. For calculating precise screw positions, a computer-based planning software was developed resulting in a three-dimensional reconstruction of the bony surfaces. The plate was integrated in the 3-D reconstruction software. With a defined distance to the distal part of the femurs, allowed the proper length and position of the screws to be calculated. These calculations were transferred to the screws on the real plate. In the next step the plate was positioned on the bony surface and after reaching the planned position the plate's connector was rigidly fixed to the bone. The plate was removed to give place to link saw jigs to the connector. Planning and setting of the plate and the screws were conducted on three femoral bones. Examinations were performed by five investigators with ten repetitions on each bone with three distinct plates. Intra- and inter-observer variability was assessed by measuring the variation in plate position between the trials. The jigs were placed in a mean frontal tilting (medial to lateral) of 0.83°. The mean axial tilting (proximal to distal) was 1.66° and the mean shift on the axis from proximal to distal 8.48 mm. The shift and the tilting were significantly bone dependent but not user dependent. Compared with previous studies the deviation from the mechanical axis were comparable with conventional TKA (2.6° and 0.4°), computer assisted TKA (1.4° and 1.9°) and Custom-fit TKA (1.2°). We developed a preoperative planning system for TKA that allows a transfer of the planning and the calculated imprint of the bones surface on a grid-plate during surgery by the surgeons themselves. Neither external manufacturers to create a fixed device nor a navigation system is necessary. Results showed the functioning of the screw – based shape fitting technique within the accuracy mentioned above. These findings are encouraging to do further research to examine the ideal number of screws to offer a perfect fitting

Introduction. Periprosthetic femur fractures are a serious complication after hip replacement surgery. In an aging population these fractures are becoming more and more common. Open reduction and plate osteosynthesis is one of the available treatment options. Objective. To investigate hip stem stability and cement mantle integrity under cyclic loading conditions after plate fixation with screws perforating the cement in the proximal fragment. Methods. Polished tapered hip stems were implanted in 16 biomechanical testing femora with Palacos cement (3rd generation technique) according to the manufacturer's recommendations. 8 testing bones were osteotomised distal to the stem representing the fracture group (Vancouver Type C). The osteotomy was fixed with a polyaxial locking plate, the other 8 specimens served as a control group. The specimens were tested in a biaxial material testing machine under axial compression (including adduction and torsion moments) for 100.000 cycles at physiological loads. Stem subsidence was measured in 3 planes with a stereoscopic image correlation system during the tests. Subsequently the sliced and crack dyed specimens were investigated microscopically for cement cracks. Results. In the control group no specimen failed during testing. There were no statistically significant differences in stem subsidence along the longitudinal axis (control group mean ± SD −15.4 ± 12.2 μm, fracture group −14.1 ± 13.1 μm). In the fracture group two specimens fractured through the most proximal screw hole after 74.000 and 80.000 cycles. Overall 15 out of 36 screws in the proximal fragment had direct stem contact. No cement cracks were detected in the sliced specimens in both groups. Conclusion. Drilling the cement mantle and placing screws in the cement did not increase stem subsidence under cyclic loading. No cracks or cement mantle failure were observed. Large screw diameters proximally weaken the lateral cortex resulting in tension failure of the bone. Plate fixation of a periprosthetic femoral fracture with a stable, cemented prosthesis does not lead to early cement mantle failure