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.

Introduction and purpose: Calcaneal fractures are relatively common. The severity of this condition is due to the residual functional limitation. There are several therapeutic alternatives.

Materials and methods: We carried out a retrospective study of 70 patients with calcaneal fractures, divided into two groups. The first group of 35 patients was treated with bone synthesis using pins and the second group of 35 with bone synthesis with a low-profile plate and screws. We analysed epidemiological data, injury mechanism, type of fracture and complications. We calculated the reduction of Böhler’s angle and return to work. The clinical and functional results were analysed using the AOFAS scale.

Results: The mean age and injury mechanism were very similar in both groups. In the pin group, the fracture type was mainly grade 2 according to the Sanders classification, while in the plate group it was grade 3.

The reduction of Böhler’s angle was greater in the plate group. There were no statistically significant differences between the two groups with regard to return to work. However the final AOFAS score was 82.7 in the plate and 69.8 in the pin group.

Conclusions: A fracture of the calcaneus is a complex pathology, especially because of the functional limitation it leaves behind.

There were fewer complications in the plate group, except for skin problems.

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

Purpose: To assess the use of cortical allografts (bone plates?) in hip replacement surgery. Materials and methods: This is a retrospective study of 43 bone plates in 36 hip prostheses. In 18 cases they were implanted to treat a periprosthetic fracture (an associated replacement of the femoral component was performed in 5 cases) and in 18 they were implanted to replace a loosened stem in a hip with large bone defects. Standard long uncemented stems were implanted in 7 cases and standard cemented stems associated with morselized compacted allografts were implanted in 16 cases. 14 patients were only given bone plates and in 22 these bone plates were associated to a metal plate. The mean age was 69.1 years (range: 38–82). 61.1% were female, 18% were implanted in the right side and the mean follow-up was 45.4 months. Results: At the time of the last review, three patients had died but for reasons not related to their hip surgery. Transient sciatic nerve palsy was observed in one patient, prosthetic dislocation in three cases (two of them were successfully treated with bracing and the other had to be given a constrained cup), there was an infection (treated with a two-stage replacement) and two re-fractures (after 3 and 13 months) treated with a new osteosynthesis with a bone plate associated to a metal plate. All the fractures healed and the imaging tests showed an integration of the bone plate with the host bone with no signs of prosthetic loosening. Conclusions: Cortical allografts can fulfill two functions: a mechanical one (they behave as if they were a plate) and a biological one (they increase bone stock on integration)

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

The evolution of bone plate design has been with a view to reducing the interface contact between the plate and the underlying bone thereby limiting the perfusion deþciency that developes. Little consequence however, has been attributed to the drilling of holes in the steps prior to bone plate application; the work present herein attempts to deþne the vascular response of bone to the trauma of drilling holes. Anaesthetized sheep underwent the creation of drill holes in both tibiae and metatarsi. Animals were then heparinized and euthanatized. Utilizing femoral cannula, perfusion of the vasculature ensued; Spalteholz (India ink), Disulphine blue and radiocontrast material (Barium sulfate). Decalciþed histology was performed and correlated with the perfusion studies. Regions of perfusion deþciency were observed immediately adjacent to, and removed from, the drill hole site. Radiographic images showed substantial haematoma formation and vascular disruption in the vicinity of the drill hole site. Histologically, blood vessels immediately adjacent and distal to the drill hole site, contained a proteinaceous/ cellular material occluding the vascular space. Our þndings support the proposal of a short-term obstruction in cortical blood ßow which may contribute to later adaptational osteopaenia following bone plate application. We have observed an acute vascular insufþciency in cortical bone directly related to the trauma of drilling screw holes

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

Introduction: The authors introduce a modified technique of iliac splitting and expanding shelf (ISES) arthroplasty for severe LCPD, and report on the intermediate outcomes. Materials and Methods: This new procedure is a modification of the previously reported tectoplasty of Saito (1986) and the shelf arthroplasty of Catterall (1992). Only the sartorius muscle and the indirect head of the rectus femoris muscle are detached, leaving the abductors intact. A superiorly hinged bony flap was raised from the lateral iliac wall just above the hip joint capsule. A corticocancellous bone plate was harvested from the inner table of the iliac wing, and was placed between the lateral hip joint capsule and the bony flap. The triangular space between the split iliac wall and the bone plate was packed with autogenous cancellous bone chips and Osteoset® (Wright-Medical, Arlington, Tennessee, USA). The repaired indirect head of the rectus femoris muscle gave stability to the shelf. After 4 weeks in a Petrie cast, the hip was mobilized, and partial weight bearing was started postoperative at 6 weeks. Twenty one hips in 21 children older than 8 years presenting with early (18 hips) and late (reossification) (3 hips) LCPD were treated by ISES arthroplasty. All patients were followed up for more than 2 years (range, 2 to 8.5 years). Results: There were significant functional and radiological improvements after operation. One patient needed a secondary varus osteotomy to solve persistent subluxation. The poorest result occurred in a very obese child, presenting with early stage of Catterall IV involvement at age 11.5 years. Discussion: Our modified technique of the shelf arthroplasty, sparing the abductor mechanism, appears to be a reliable and effective method to augment the superolateral coverage of the femoral head in severe LCPD

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.

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

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.

Introduction: Increasing number of osteoporotic fractures of the femur, especially upper part of the femur creates everyday problem of health services. Treatment of these fractures has been improving markedly during the past 25 years. DHS, gamma nail and some other implants are very useful in everyday surgery. However some of complications still can not be resolved like cut out. Osteoporotic fractures in subtrochanteric area represent even bigger challenging. Diaphyseal fractures are also difficult to be treated. The main problem is quality of osteoporotic bone. Plate with parallel screws doesn’t provide reliable fixation. Intramedulary nails, because of wide channel in distal femur area also don’t provide desirable fixation stability. Material and Method: We analysed results of using of one new device: selfdynamisable internal fixator (SIF) in the series of 389 patients treated because of upper femur fractures. That device has possibilities of spontaneous dynamisation in two axes: along the femoral neck axis and along the diaphyseal axis. Spontaneous dynamisation in the diaphyseal axis is very important if diaphyseal or subrtochanteric fracture or comminuted fracture of the upper femur with subtrochanteric extension treated. For activation of axial dynamisation it not necessary to do any action from outside the body. This feature is activated spontaneously if there is no progress in fracture union within 6–8 weeks. This device provides three-dimensional fixation using clams and rod onto the lateral surface of the femur. The age of patients was from 59 to 87 years. This internal fixator is applied using minimally invasive method – by one or two small incisions. Results: During the treatment it has been confirmed working of self-dynamisation concept. Spontaneous dynamisation in the long axis of the femur has been proven in 21% of patients with subtrochanteric and diaphyseal fractures and it has been proven radiologically that sliding happened between 1–4 mm (average 2.5 mm). Such dynamisation together with 3D configuration of screws resulted in relatively quick fracture healing. Follow up was 19 months (6–60). Altogether 97.6% fractures healed within normal healing time. There were 1 infection, 2 cut out, 1 mechanical complication, 4 delay unions and one non-union. Conclusion: According to results obtained, it can bee concluded that new biological internal fixator is suitable for minimally invasive technique, without opening of fracture site

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).

Sutures from intraosseous anchors are used to secure soft tissue down onto bone during healing. Increasingly anchors are made from absorbable materials. Poly lactide carbonate (PLC - poly lactide with calcium carbonate) is an absorbable formulation with osteoconductive properties that should enhance both tissue healing and its own replacement by bone over time. An animal model of soft-tissue-to-bone healing was used to assess the efficacy of PLC Bioraptor™ anchors in comparison to anchors of non-osteoconductive poly lactide (PLLA). Forty-seven ewes were used in two groups of PLC or PLLA anchors, surviving to either four or 12 weeks. The patellar tendon was pared off the tibia, the footprint decorticated then the tendon re-attached. An external fixator protected the tendon from load bearing for three weeks. At post mortem the patella/patellar tendon/tibia complex was either prepared for histological examination or stored deep frozen for later measurement of peak load at failure. Non-operated specimens failed within the tendon mid substance; the failure site of healing specimens was dependent on their strength, with the weakest through interpositional granulation tissue, stronger specimens through fibres at various distances from the bone and the strongest, by partial bone avulsion. Active healing of the enthesis consisted of merging regions of. a) re-established cortical bone plate;. b) advancing mineralization of new, oriented collagen;. c) dense, cellular collagen parallel to the tendon axis. Thin new bone was present around both PLLA and PLC anchors. Healing tissues held by PLC suture anchors, were significantly stronger by 12 weeks than those held by PLLA anchors, possibly due to the calcium carbonate in the PLC anchor. However, the macroscopic and microscopic appearances of the healing tissues seemed little different between the two groups. This study indicates that PLC is a suitable replacement for PLLA in the fabrication of suture anchors. As well as its ability to produce stronger healing tissues, PLC has a shorter longevity in vivo and longer term is replaced by bone

Wire cerclage is one of the oldest forms of internal fixation. Cerclage has numerous applications in orthopaedics as a primary method of fracture fixation and as a supplement to other forms of fixation. Traditional wire cerclage, however, has several disadvantages. Monofilament wire is prone to breakage. Multifilament braided cables tend to undergo fatigue failure and fray, releasing metallic particulate debris into the body. Both have a limited ability to maintain compression. This paper presents performance data on a novel flexible, high strength, high fatigue life cable that addresses the inherent problems associated with traditional metal wire cerclage. The iso-elastic cerclage cable consists of a nylon core encased in a jacket of UHMWPE braided fibers. A tensioning instrument tightens the assembly with a metal clasp. Cable assemblies were tested under in vitro static and dynamic loading conditions. Viscoelastic response and wear behavior under in vitro loading conditions were characterized. The iso-elastic cerclage cable displayed an ultimate tensile strength of pproximately 650 MPa and withstood over one million cycles of simulated physiologic load without failure. After 8 weeks of static loading, initial cable tension decreased by approximately 40%. After one million loading cycles against a bone plate, the iso-elastic cable displayed no evidence of fraying or fiber breakage. The ultimate strength of the iso-elastic cable is comparable to that of traditional metal cable while its fatigue strength is clearly superior. After initial relaxation, the iso-elastic cable maintained compressive forces that are typical of the initial compression held by metal cerclage wires. The wear characteristics of the iso-elastic cable are clearly superior to those of multifilament metal cerclage cables. The iso-elastic cable shows high tensile strength and fatigue life. An iso-elastic cable has been developed to compensate for micro-movement within the bone fracture construct while maintaining a continuous compressive force across the fracture

Aims: The goal of this study to compare the clinical outcome of patients with calcaneus fractures differential strategy and non-differential conservative strategy treated. Methods: The study based on the results of treatment of 122 patients with 140 heel bone fractures. Results of only conservative treated 52 patients (54 fractures) in period 1992–1999 were retrospectively evaluated. Results of 70 patients (86 fractures) differential strategy treated in period 1999–2001 were prospectively evaluated. The plain radiographs – that is lateral, antero-posterior, oblique radiographs of the foot, axial and Broden view – and computerized tomography were used for examine patients. In period 1999–2001 the patients were differential strategy treated. All patients were divided in 5 groups: non-displacement fractures (early range of motion), beak type fractures (close reduction internal fixation by cannulated screw), tongue-type fractures (axial reposition axial fixation by Schantz screw), jointdepression and comminuted fractures (ORIF calcaneus bone plate AO). The results were evaluated by own score system in first group in 4 – 8 years period and 1 – 2,5 years period in second group. Results: The results of differential strategy treated patients with heel bone fractures (excellent – 60,9%± 5,9, good – 29,0%± 4,8, fair – 5,8%± 2,4, bad – 4,3%± 2,1) were reliably (p≥95%) better than results in only conservative treated group (excellent – 26,8%±4,7, good – 23,9%±4,5, fair – 23,9%±4,5, bad 25,4%±4,6). Conclusions: This study demonstrates that the differential strategy of treatment allows to reach good results and minimize soft tissue trauma

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

Purpose: The Less Invasive Stabilization System (LISS), Dynamic Condylar Screw (DCS) and Condylar Buttress Plate (CBP) are three common fixation methods for supracondylar femur fractures. The DCS and CBP are compression plates while the LISS uses locking screws to transfer load from bone to plate without compression. We developed a study to determine if the theoretical biomechanical advantages of the LISS would be evident in laboratory testing. Methods: Identical AO type C fractures were created in eighteen composite femurs and fixed with either LISS, CBP, or DCS (6 each). Roentgen Stereophotogrammetric Analysis (RSA) was used for analysis. Reference markers were implanted into each bone segment. Biplanar x-rays were taken to give a three-dimensional representation of the fracture. The femurs were loaded axially in an Instron 1350 and subjected to cyclic loading (50kg ± 25 for 50000 cycles). After loading, the bones were x-rayed to determine relative motion between fracture segments. To examine inducible displacement under static loading, the femurs were x-rayed in an unloaded and loaded (50 kg) condition. Again, RSA was used for analysis. Results: RSA-CMS software was used to analyze relative motion between the bone segments. After cyclic loading, the condylar buttress plate showed significantly more permanent deformation between the medial condyle and shaft of the femur than the DCS or LISS. Under static load, the LISS showed greater displacement than the other devices between the medial condyle and shaft, and between the lateral condyle and shaft. Conclusions: The LISS demonstrated less permanent deformation but greater inducible deformation between the medial femoral condyle and femoral shaft, compared to the DCS and CBP. The results were statistically significant. These results may have clinical implications regarding the choice of fixation devices for this difficult fracture pattern. Funding: Other Education Grant. Funding Parties: Capital Health Research Grant

Two stainless steel ‘TriMed’ distal radial fracture reduction techniques were tested to compare the relative stability of the two in vitro for a pre-determined fracture pattern. The movement of the bony segments were plotted over time using an ARAMIS 3 dimensional non-contacting displacement mapping system (GOM mbH, Braunschweig, Germany) to give quantitative data. The data was used to calculate the relative motion of the bony segments with the aim of investigating regions of compression across the fracture line, which is thought to accelerate fracture healing, and shear between bony segments, which is detrimental to fracture healing. Ten third generation adult radius biomechanical model Sawbones (Sawbones, Malmö, Sweden) were cut to simulate AO type C2 fractures with dorsal comminution. Five bones were plated using the TriMed fixed angle volar bearing plate and five were plated using the TriMed radius and ulnar plating technique. Samples were potted and loaded cyclically at 1 Hz via a floating scaphoid-lunate bearing onto the end of the radius at incrementally increasing loads of 100 N – 500 N with 1000 load cycles applied for each load level. The results showed the radius and ulnar pin-plate configuration allowed greater movement of the articular surface, with relative shear motion and separation between the two segments, although the relative shear movement between the two distal segments was below 2mm, which is considered the definition of failed fixa-tion. With the volar bearing plate the two distal segments moved as single unit and compression with minimal shear was applied across the fracture line to the proximal radius. Thus the radius and ulnar plates allowed shear across all three fracture lines, while the volar plate held the two distal segments fixed relative to each other and allowed compression across the interface with the proximal radius. The ARAMIS system allowed the three dimensional motion of the bony segments to be followed, in particular the relative motion between the segments, indicating the type of healing to be expected clinically. The study demonstrated the value of ARAMIS in investigating the stability of wrist fractures fixations and can easily be adapted to investigate other orthopaedic fixation systems