We present the indications and outcomes of a series of custom 3D printed titanium acetabular implants used over a 9 year period at our institution (Sydney, Australia), in the setting of revision total hip arthroplasty. Individualised image-based case planning with additive manufacturing of pelvic components was combined with screw fixation and off-the-shelf femoral components to treat patients presenting with failed hip arthroplasty involving acetabular bone loss. Retrospective chart review was performed on the practices of three contributing surgeons, with an initial search by item number of the Medicare Benefits Scheme linked to a case list maintained by the manufacturer. An analysis of indications, patient demographics and clinical outcome was performed. The cohort comprised 65.2% female with a median age of 70 years (interquartile range 61–77) and a median follow up of 32.9 months (IQR 13.1 - 49.7). The indications for surgery were infection (12.5%); aseptic loosening (78.1%) and fracture (9.4%), with 65.7% of cases undergoing previous revision hip arthroplasty. A tumour prosthesis was implanted into the proximal femur in 21.9% of cases. Complications were observed in 31.3% of cases, with four cases requiring revision procedures and no deaths reported in this series. Kaplan-Meier analysis of all-cause revision revealed an overall procedure survival of 88.7% at two years (95%confidence interval 69 - 96.2) and 83.8% (95%CI 62 - 93.7) at five years, with pelvic implant-specific survival of 98% (95%CI 86.6 - 99.7) at two and five year follow up. We conclude that an individualised planning approach for custom 3D printed titanium acetabular implants can provide high overall and implant-specific survival at up to five years follow up in complex cases of failed hip arthroplasty and acetabular bone loss

Complex acetabular reconstruction for oncology and bone loss are challenging for surgeons due to their often hostile biological and mechanical environments. Titrating concentrations of silver ions on implants and alternative modes of delivery allow surgeons to exploit anti-infective properties without compromising bone on growth and thus providing a long-term stable fixation. We present a case series of 12 custom acetabular tri-flange and custom hemipelvis reconstructions (Ossis, Christchurch, New Zealand), with an ultrathin plasma coating of silver particles embedded between layers of siloxane (BioGate HyProtect™, Nuremberg, Germany). At the time of reporting no implant has been revised and no patient has required a hospital admission or debridement for a deep surgical site infection. Routine follow up x-rays were reviewed and found 2 cases with loosening, both at their respective anterior fixation. Radiographs of both cases show remodelling at the ilium indicative of stable fixation posteriorly. Both patients remain asymptomatic. 3 patients were readmitted for dislocations, 1 of whom had 5 dislocations within 3 weeks post-operatively and was immobilised in an abduction brace to address a lack of muscle tone and has not had a revision of their components. Utilising navigation with meticulous implant design and construction; augmented with an ultrathin plasma coating of silver particles embedded between layers of siloxane with controlled and long-term generation of silver ion diffusion has led to outstanding outcomes in this series of 12 custom acetabular and hemipelvis reconstructions. No patients were revised for infection and no patients show signs of failure of bone on growth and incorporation. Hip instability remains a problem in these challenging mechanical environments and we continue to reassess our approach to this multifaceted problem

Proximal femoral focal deficiency is a congenital disorder of malformation of the proximal femur and/or the acetabulum. Patients present with limb length discrepancy and clinical features along a spectrum of severity. As these patients progress through to skeletal maturity and on to adulthood, altered biomechanical demands lead to progression of arthropathy in any joint within the lower limb. Abnormal anatomy presents a challenge to surgeons and conventional approaches and implants may not necessarily be applicable. We present a case of a 62-year-old lady with unilateral proximal femoral focal deficiency (suspected Aitken Class A) who ambulated with an equinus prosthesis for her entire life. She presented with ipsilateral knee pain and instability due to knee arthritis but could not tolerate a total knee arthroplasty due to poor quadriceps control. A custom osteointegration prosthesis was inserted with a view to converting to the proximal segment to a total hip replacement if required. The patient went on to develop ipsilateral symptomatic hip arthritis but altered acetabular anatomy required a custom tri-flange component (Ossis, Christchurch, New Zealand) and a custom proximal femoral component to link with the existing osseointegration component (Osseointegration Group of Australia, Sydney, Australia) were designed and implanted. The 18 month follow up of the custom hip components showed that the patient had Oxford hip scores that were markedly improved from pre-operatively. Knee joint heights were successfully restored to equal when the patient's prosthesis was attached. The patient describes feeling like “a normal person”, walks unaided for short distances and can ambulate longer distances with crutches. Advances in design and manufacture of implants have empowered surgeons to offer life improving treatments to patients with challenging anatomy. Using a custom acetabular tri-flange and osseointegration components is one possible solution to address symptomatic ipsilateral hip and knee arthropathy in the context of PFFD in adulthood

INTRODUCTION. Postoperative functional limitations after Total Knee Arthroplasty (TKA) are caused, in part, by a mismatch between a patient's natural anatomy and conventional “off-the-shelf” implants. To address this, we propose a new concept combining off-the-shelf femur and tibia implants with custom polyethylene tibial inserts designed to account for a patient's unique anatomy. Our goal in this study was to use knee specific computational modeling to determine the neutral path of motion and laxity of an intact knee under axial compression and shear forces through full flexion and compare intact motion against the same knee implanted with a conventional off-the-shelf vs. a custom tibial insert. METHODS. 3D models of a healthy knee joint were acquired from an open development repository funded by the National Institute of Biomedical Imagining and Bioengineering (Harris et al., 2016). The knee model was virtually implanted with conventional (off-the-shelf) posterior cruciate retaining (CR) components including the femoral component, tibial tray, and a conventional insert. A custom CR tibial insert was designed taking into account native articular geometry and compatibility with placement of the off-the-shelf femoral/tibial tray. Bone, cartilage and implant models were imported into ANSYS Workbench. Ligaments were calibrated using data from in-vitro experimental tests (Harris et al., 2016). The following load conditions were applied to the femur: 20 N axial compression (neutral path), 20 N axial compression with 80 N anterior shear force, and 20 N axial compression with 80 N posterior shear force. Simultaneously for each loading condition, the knee was flexed from 0 – 120 degrees. A circular axis system was used to describe the motion of the femur relative to the tibia. RESULTS. For the intact case, neutral path was characterized by greater posterior femoral displacement on the lateral side than on the medial side, especially in early flexion. Neutral path of the custom insert was closer to intact condition than the conventional insert. Overall AP laxity was similar between intact and implanted models except at 30 degrees where increased laxity occurred posteriorly for the implanted models, likely due to resection of the anterior cruciate ligament (ACL) as part of the TKA procedure. For intact and implanted models, AP laxity significantly decreased at the higher flexion angles. DISCUSSION. Our findings indicate that motion with a custom tibial insert was closer to intact than the conventional design. Nonetheless, custom articular surface alone may not fully reproduce intact motion due to limitations such as resection of the ACL, and such custom inserts may benefit from guiding features such as a cam, post, or retention of the native ACL to more closely reproduce normal knee function. We did not simulate specific activities of daily living. Increasing the magnitudes of compression and shear forces would not change the neutral path of motion, although, a reduction in laxity would be expected

Knee replacement is a proven and reproducible procedure to alleviate pain, re-establish alignment and restore function. However, the quality and completeness to which these goals are achieved is variable. The idea of restoring function by reproducing condylar anatomy and asymmetry has been gaining favor. As knee replacements have evolved, surgeons have created a set of principles for reconstruction, such as using the femoral transepicondylar axis (TEA) in order to place the joint line of the symmetric femoral component parallel to the TEA, and this has been shown to improve kinematics. However, this bony landmark is really a single plane surrogate for independent 3-dimensional medial and lateral femoral condylar geometry, and a difference has been shown to exist between the natural flexion-extension arc and the TEA. The TEA works well as a surrogate, but the idea of potentially replicating normal motion by reproducing the actual condylar geometry and its involved, individual asymmetry has great appeal. Great variability in knee anatomy can be found among various populations, sizes, and genders. Each implant company creates their specific condylar geometry, or “so called” J curves, based on a set of averages measured in a given population. These condylar geometries have traditionally been symmetric, with the individualised spatial placement of the (symmetric) curves achieved through femoral component sizing, angulation, and rotation performed at the time of surgery. There is an inherent compromise in trying to achieve accurate, individual medial and lateral condylar geometry reproduction, while also replicating size and avoiding component overhang with a set implant geometry and limited implant sizes. Even with patient-specific instrumentation using standard over-the-counter implants, the surgeon must input his/her desired endpoints for bone resection, femoral rotation, and sizing as guidelines for compromise. When all is done, and soft tissue imbalance exists, soft tissue release is the final, common compromise. The custom, individually made knee design goals include reproducible mechanical alignment, patient-specific fit and positioning, restoration of articular condylar geometry, and thereby, more normal kinematics. A CT scan allows capture of three-dimensional anatomical bony details of the knee. The individual J curves are first noted and corrected for deformity, after which they are anatomically reproduced using a Computer-Aided Design (CAD) file of the bones in order to maximally cover the bony surfaces and concomitantly avoid implant overhang. No options for modifications are offered to the surgeon, as the goal is anatomic restoration. Given these ideals, to what extent are patients improved? The concept of reproducing bony anatomy is based on the pretext that form will dictate function, such that normal-leaning anatomy will tend towards normal-leaning kinematics. Therefore, we seek to evaluate knee function based on objective assessments of movement or kinematics. In summary, the use of custom knee technology to more closely reproduce an individual patient's anatomy holds great promise in improving the quality and reproducibility of postoperative function. Compromises of fit and rotation are minimised, and implant overhang is potentially eliminated as a source of pain. Early results have shown objective improvements in clinical outcomes. Admittedly, this technology is limited to those patients with mild to moderate deformity at this time, since options like constraint and stems are not available. Yet these are the patients who can most clearly benefit from a higher functional state after reconstruction. Time will reveal if this potential can become a reproducible reality

The custom triflange acetabular component has been advocated for severe acetabular defects and pelvic discontinuity, cases in which a porous-coated hemisphere will not work. These are AAOS type III or IV defects, or alternatively classified as Paprosky 3B. Many have a pelvic discontinuity. A pre-operative CT of the pelvis is sent to the manufacturer who generates a one-to-one scale 3D model of the hemipelvis. The surgeon can review either a pdf file or an actual model. If the visualised defect cannot be treated with traditional methods then a triflanged component is created. The components have backside porous and hydroxyapatite coating. Initial rigid fixation is obtained with screw fixation to the ilium and ischium. Subsequent bone ingrowth can provide long term fixation. The goal is to span the acetabular defect and obtain fixation to the ilium and ischium with a third arm which rests on the pubis. Christie first reported on 67 hips (half with a discontinuity) with a mean follow-up of 53 months. No components were removed. There was an 8% reoperation for dislocation, 6% partial sciatic nerve palsy. 46% walked without support. Dennis reported 26 hips with a mean 54 month follow-up. Eighty-eight percent were considered successful. One implant was removed and left with a resection arthroplasty and 2 others had loose components but refused reoperation. Loosening of the ischial screws was a sign of failure in the three cases. Taunton reported 57 cases with a pelvic discontinuity treated with a triflange at mean follow-up of 65 months. Eighty-one percent had a stable component and a healed pelvic discontinuity. These authors also compared a custom triflange to a trabecular metal cup-cage construct finding similar implant costs of $12,500 and $11,250, respectively. All advocates of custom triflange acetabular components believe the results are similar or superior to other options in these very challenging cases at early follow-up. The primary disadvantage of the technique is the pre-operative time required to manufacture the device – typically 4–8 weeks

The custom triflange acetabular component has been advocated for severe acetabular defects and pelvic discontinuity, cases in which a porous-coated hemisphere will not work. These are AAOS type III or IV defects, or alternatively classified as Paprosky 3B. Many have a pelvic discontinuity. A preoperative CT of the pelvis is sent to the manufacturer who generates a one-to-one scale 3D model of the hemipelvis. The surgeon can review either a pdf file or an actual model. If the visualised defect cannot be treated with traditional methods then a triflanged component is created. The components have backside porous and hydroxyapatite coating. Initial rigid fixation is obtained with screw fixation to the ilium and ischium. Subsequent bone ingrowth can provide long term fixation. The goal is to span the acetabular defect and obtain fixation to ilium and ischium with a third arm which rests on the pubis. Christie first reported on 67 hips (half with a discontinuity) with a mean follow-up of 53 months. No components were removed. There was an 8% reoperation for dislocation, 6% partial sciatic nerve palsy. 46% walked without support. Dennis reported 26 hips with a mean 54 month follow-up. 88% were considered successful. One implant was removed and left with a resection arthroplasty and 2 others had loose components but refused reoperation. Loosening of the ischial screws was a sign of failure in the three cases. Taunton reported 57 cases with a pelvic discontinuity treated with a triflange at mean follow-up of 65 months. 81% has a stable component and a healed pelvic discontinuity. These authors also compared a custom triflange to a trabecular metal cup-cage construct finding similar implant costs of $12,500 and $11,250, respectively. All advocates of custom triflange acetabular components believe the results are similar or superior to other options in these very challenging cases at early follow-up. The primary disadvantage of the technique is the preoperative time required to manufacture the device – typically 4–8 weeks

Recently, a new technique of custom-made cutting guides for TKA is introduced to clinical practice. However, no published data yet on the comparison between this new technique against both navigation and conventional techniques. The author prospectively compared between custom-made cutting guides, navigation and conventional techniques. A total number of 90 cases were included in this study with 30 consecutive cases for each technique. The highest number of medically unfit patients and those with articular and extra articular deformities were in custom guides groups. The results showed one case of aseptic loosening after one year in custom guides, one case of superficial infection and loose pins but with no fracture in navigation group, and higher need for blood transfusion in conventional. One case in the custom guide group had a periprosthetic fracture 3 weeks postoperatively diagnosed as insufficiency fracture after a relatively minor trauma to an osteoporotic bone. Navigation was the most accurate in alignment but custom guides was the most accurate in implant sizing and had the least bleeding. This clinical study showed some advantages of custom-made cutting guides over conventional instrumentation. It eliminated medullary guides, reduced operative time, and provided better accuracy. The technique was proved to be useful in complex cases of deformities and unfit patients

Hypothesis. Custom cutting blocks can produce similar alignment compared to computer navigated and conventional total knee arthroplasty (TKA) techniques. Method. We conducted a retrospective review of 37 patients who underwent TKA by a single surgeon in a teaching hospital setting. Groups were conventional method (10), computer assisted navigation (10), and custom blocks (18). The custom group was further subdivided to CT and MRI based blocks. Post-operative alignment was measured (blinded) using full length weight bearing radiographs at 18 weeks on average. Hospital records were reviewed to determine operative time, transfusion requirements, length of hospital stay, complications and cost. Results. Post-operative mechanical axis was within 3 degrees of neutral in 100% of the navigation group, 70% of the conventional group and 50% of the custom block group. Average alignment was within 1.8, 3.1 and 3.6 degrees of neutral for each group respectively. The operative time was greater for the computer navigation group (86.7 min) compared to the conventional (72.1) and MRI custom block groups which involved unfamiliar instrumentation (73.8). CT based block procedures involved otherwise familiar instruments and averaged 61.2 minutes. Length of hospital stay and complications were similar for all three groups. Total cost was the least for the conventional group. Increased costs were associated with computer equipment, pre-operative advanced imaging and custom blocks. Conclusions. Custom cutting blocks in this small series obtain worse radiographic positioning of total knee arthroplasty components compared to conventional and computer navigation techniques. Further studies with greater number of patients, CT alignment analysis and long-term follow-up are required

Introduction. Custom instrumentation in TKA utilizes pre-operative imaging to generate a customized guide for cutting block placement (Figure 1). The surgeon is able to modify the plan using three-dimensional software (Figure 2). Although this technology is increasingly gaining acceptance, there is a paucity of clinical data supporting it. Methods. One hundred and eleven patients underwent primary TKA using the Patient-Specific Instrumentation (PSI) system, in twenty-eight of the cases surgical navigation was used to validate the PSI-generated cuts. Alignment measurements included long-leg alignment and biplanar distal femoral and proximal tibial cuts. Further measurements evaluated femoral implant placement in the AP plane, femoral component rotation, measured bone resection and implant sizing accuracy. Results. The mean final limb alignment as recorded by computer-assisted surgical (CAS) tools was 0.3° of varus. Only two limbs were malaligned by greater than 3° (Figure 3). The femoral component had a mean alignment of 0.3° of valgus and 4.5° of flexion (PSI plan 3° flexion). The predicted femoral size was accurate in 89% of cases and the anterior femoral cut was congruent with the anterior cortex in 92% of cases. The PSI-directed femoral component rotation was consistent with the surgeon's perceived rotation in 95% of cases. The posterior condylar bone resection had a mean difference of < 1mm from the predicted resection. The tibial component had a mean alignment of 0.5° of varus and 8.5° of posterior slope (PSI plan 7° posterior slope). The only statistically significant deviation in alignment was the increased tibial slope (p=0.046) (Figure4). The tibial component size was accurately predicted in 66% of cases. Discussion. Custom instrumentation in total knee arthroplasty accurately achieved implant and limb alignment in our study. The plan was more reproducible on the femoral slide. The overestimation of tibial slope and tibial sizing incongruity were related to some of the reference points for the software. A potential benefit of this technology is improved mid-flexion stability by accurately determining femoral component size, placement, and rotation. Further studies are needed to determine the efficiency and cost-effectiveness of this technology

Introduction. CT based systems that are used to create custom components and custom cutting guides in total knee arthroplasty (TKA) have variable methods for accounting for the thickness of remaining cartilage that may influence component sizing and bone resection. Little information has been published about the thickness of this cartilage, especially on the posterior femoral condyles. Failure to account for this cartilage may lead to under-sizing of the femoral component, or a reduction in the posterior condylar offset that may adversely affect flexion after TKA. Methods. This IRB approved, retrospective study included 140 consecutive patients who underwent primary TKA. The medial and lateral posterior condylar bone cuts were performed in the usual manner with mechanical instruments. The resected specimen was sectioned in the sagital plane and the cartilage thickness was measured at the mid portion to the nearest millimeter. Results. The mean cartilage thickness was 1.7 mm (range, 0 to 4 mm) on the medial posterior condyle and 2.0 mm (range, 0 to 5 mm) on the lateral posterior condyle. There was no correlation between the remaining medial and lateral posterior condylar cartilage thickness (p=0.35). Conclusions. The thickness of remaining cartilage on the posterior condyles of the femur at the time of TKA is between 0 and 5 mm. This variable cartilage thickness may be poorly visualized on the CT studies used for creating custom femoral components or custom femoral cutting guides. This variability is greater than the 3 to 4 mm differences in AP measurement between femoral sizes in most contemporary TKA systems. Therefore, CT based custom systems may reproduce femoral sizing and posterior condylar offset less well than off the shelf femoral components implanted with conventional instruments. Future studies will be needed to evaluate the accuracy of component sizing between CT versus MRI based systems

The treatment of extensive bone loss and massive acetabular defects is a challenging procedure, especially the concomitant pelvic discontinuity (PD) can be compounded by several challenges and pitfalls. The appropriate treatment strategy is to restore a stable continuity between the ischium and the ilium and to reconstruct the anatomical hip center. Antiprotrusio cages, metal augments, reconstruction cages with screw fixation, structural allograft with plating, jumbo cups, oblong cups and custom-made triflange acetabular components have been reported as possible treatment options. Nevertheless, the survivorship following acetabular revision with extensive bone loss is still unsatisfactory. The innovation of three-dimensional printing (3DP) has become already revolutionary in engineering and product design. Nowadays, the technology is becoming part of surgical practice and suitable for the production of precise and bespoke implants. The technique of a 3D-printed custom acetabular component in the management of extensive acetabular defect is presented

Revision of total hip arthroplasty (THA) is being performed with increasing frequency. However, outcomes of repeated revisions have been rarely reported in the literature, especially for severe defects. Cup revision can be a highly complex operation depending on the bone defect. In acetabular defects like Paprosky types 1 and 2 porous cementless cups maybe fixed with screws give good results. Modern trabecular metal designs improve these good results. Allografts are useful for filling cavitary defects. In acetabular defects Paprosky types 3A and 3B, impacted morselised allografts with a cemented cup technique produce good results. Difficult cases with pelvic discontinuity require reconstruction of the acetabulum with acetabular plates or large cup-cages to solve these difficult problems. However, there is still no consensus regarding the best option for reconstructing hips with bone loss. Although the introduction of ultraporous metals has significantly increased the surgeon's ability to reconstruct severely compromised hips, there remain some that cannot be managed readily using cups, augments, or cages. In such situations custom acetabular components may be required. Individual implants represent yet another tool for the reconstructive surgeon. These devices can be helpful in situations of catastrophic bone loss. Ensuring long-term outcome mechanical stability has a greater impact than restoring an ideal center of rotation. We have done so far 15 3D Printed Individual Implants. All of them where Paprosky Type 3B defects, 10 with a additional pelvis discontinuity. The mean follow-up is 18 months. All implanted devices are still in place, no infection, no loosening. However, despite our consecutive case series, there are no mid- to long-term results available so far. Re-revision for failed revision THA acetabular components is a technically very challenging condition. The 3D Printed Individual Implants have a lot of advantages, like excellent surgical planning and a very simple technique (operative time, blood loss, instruments). They are a very stable construct for extensive acetabular defects and pelvic discontinuity

Revision of total hip arthroplasty (THA) is being performed with increasing frequency. However, outcomes of repeated revisions have been rarely reported in the literature, especially for severe defects. Cup revision can be a highly complex operation depending on the bone defect. In acetabular defects like Paprosky types 1 and 2 porous cementless cups fixed with screws give good results. Modern trabecular metal designs improve these good results. Allografts are useful for filling cavitary defects. In acetabular defects Paprosky types 3A and 3B, especially the use of trabecular metal cups, wedges, buttresses and cup-cage systems can produce good results. Difficult cases in combination with pelvic discontinuity require reconstruction of the acetabulum with acetabular plates or large cup-cages to solve these difficult problems. However, there is still no consensus regarding the best option for reconstructing hips with bone loss. Although the introduction of ultraporous metals has significantly increased the surgeon's ability to reconstruct severely compromised hips, there remain some that cannot be managed readily using cups, augments, or cages. In such situations custom acetabular components may be required. Individual implants represent yet another tool for the reconstructive surgeon. These devices can be helpful in situations of catastrophic bone loss. Ensuring long-term outcome, mechanical stability has a greater impact than restoring an ideal center of rotation. However, despite our consecutive case series there are no mid- to long-term results available so far. Re-revision for failed revision THA acetabular components is a technically very challenging condition

Patients with osteochondrodysplasia frequently require Total Hip Arthroplasty at a younger age, as a result of early degenerative disease of the hip joint. The outcome of Modular Total Hip Arthroplasty in this group of patients has been reported previously. In this retrospective study we evaluated the outcome of custom made (CADCAM) Total Hip Arthroplasty in patients with osteochondrodysplasia. Between 1974 and 2009, twenty one CADCAM Total Hip Arthroplasty procedures were performed in fourteen patients in our institution. There were eight female and six male patients, with the mean age at time of surgery of 40.95 years (20 to 78). The patients were followed up clinically and with the Harris hip score for a mean of 7.12 years (0.5 to 17 years). Four of the twenty-one hips (23.8%) required revision surgery at a mean of 11.54 years (6.5 to 17 years); one required it for aseptic loosening of the femoral component; one required complete revision of the acetabular component; one required exchange of acetabular liner; and one was for symptomatic non-union of a lesser trochanter avulsion. This study shows encouraging clinical outcomes of custom made (CADCAM) Total Hip Arthroplasty in patients with osteochondrodysplasia,

We present the medium to long term clinical results of 112 Uncemented custom Computer Assisted Design Computer Assisted Manufactured (CAD-CAM) total hip arthroplasties performed between 1992 and 1998 in 111 patients. Fifty three males and 58 females were included. Mean age was 46.2 years (range 24.6yrs - 62.2 yrs). Average duration of follow up was 156 months (120 – 204 months). The mean Harris Hip Score (HHS) improved from 42.4 to 90.3, mean Oxford Hip Score (OHS) improved from 43.1 to 18.2 and the mean WOMAC hip score improved from 57.0 to 11.9. There was 1 revision due to failure of the acetabular components but there were no failures of the femoral components. There were no revisions for aseptic loosening. The worst case survival in this cohort of custom femoral components at an average 13 year follow up (range 10-17 years) was 98.2% (95% Confidence interval 95% to 99%). Survival of the femoral component alone was 100%. These results are comparable with the best medium to long term results for femoral components used in primary total hip arthroplasty (THA) with any means of fixation

Treatment of Paprosky type 3A and 3B defects in revision surgery of a hip arthroplasty is challenging. In previous cases such acetabular defects were treated with massive structural allograft bone reconstructions using cemented all-polyethylene cups. In our department we started using custom made triflanged cups to restore the articulation of the hip. The triflanged cups were designed on the basis of CT-image analysis. We are using a new type of implant construction technique with additive technology. This is a production process consisting of ion beam sintering joining metal powder particles layer upon layer on the basis of a 3D model data. The production technique is similar to rapid prototyping manufacturing. 7 Patients have been treated with this new technique. The case studies will be presented with their clinical and radiographic follow-up. We think that additive technology is a breakthrough in treating this kind of severe acetabular defects

Aim. The aim of this study is to outline the steps and techniques required to create a patient specific 3D printed guide for the accurate placement of the origin of the femoral tunnel for single bundle ACL reconstruction. Introduction. Placements of the femoral tunnels for ACL reconstruction have changed over the years 1,2. Most recently there has been a trend towards placing the tunnels in a more anatomic position. There has been subsequent debate as to where this anatomic position should be 3. The problem with any attempt at consensus over the placement of an anatomic landmark is that each patient has some variation in their positioning and therefore a fixed point for all has compromise for all, as it is an average 4. Our aim was to attempt to make a cost effective and quick custom guide that could allow placement of the center of the patients’ newly created femoral tunnel in the mid position of their contralateral native ACL femoral footprint. Materials & Methods. We took a standard protocol MRI scan of a patient's knee without ACL injury transferred the DICOM files to a personal computer running OsiriX (Pixmeo, Geneva, Switzerland.) and analyzed it for a series of specific anatomical landmarks (fig1). These measurements and points were then utilized to create a 3D computer aided design (CAD) model of a custom guide. This was done using the 3D CAD program 123Design (Autodesk Ltd., Farnbourgh, Hampshire). This 3D model was then uploaded to an online 3D printing service and the physical guide was created in transparent acrylic based photopolymer, PA220 plastic (fig 2) and 316L stainless steel. The models created were then measured using vernier calipers to confirm the accuracy of the final guides. The models produced were accurate with no statistical difference in size and positioning of the center of the ACL footprint from the original computer model and to the position of the ACL from the MRI scans. The costs for the models 3D printed were £3.50 for the PA220 plastic, £15 for the transparent photopolymer and £25 for the 316L stainless steel. The time taken from MRI to delivery for the physical models was 7 days. Conclusion. This study serves as the first step and a proof of concept for the accurate creation of patient specific 3D printed guides for the anatomical placement of the femoral tunnel for ACL reconstruction. The guides were easy to create and produce taking only a week and with a cost of between £3.50 and £25

In patients requiring two-stage procedures, stabilization of large skeletal defects after radical debridement must be attained in order to successfully treat the infection. With the use of standard rod plus antibiotic impregnated PMMA spacers limb salvage may be attempted with satisfactory results. Between 1992 and 2014, 23 patients were treated for hip, knee, or shoulder musculoskeletal infections resulting in an average skeletal defect of 22 cm. There were 13 males and 10 females. Twelve patients had infected tumor prostheses, seven patients had an infected total joint arthroplasty, and four patients had a primary infection involving a large skeletal defect. The mean time from the index procedure until infection was 22 months. Following debridement, the defect was stabilized with Tobramycin and Vancomycin impregnated PMMA and intramedullary nails. Patients were treated with IV and oral antibiotics for six weeks each. In 18 patients who had resection about the knee stabilization was achieved with a single femoral or tibial nail in nine patients and with two nails joined by a screw or cerclage wire in the other nine. In four patients a cephalomedullary femoral nail was used for stabilization after resection of the proximal or total femur. One patient had a custom total humeral prostalac using threaded Steinmann pins and 16-gauge wire. The organisms cultured were gram positive in 19 cases, mixed gram positive and fungal in one, mixed gram negative and mycobacterium in one, and two patients had no growth on cultures but histologic evidence of acute infection. Of the 23 patients, 16 were successfully reimplanted following the initial procedure (70%) and seven had recurrent infections. Three patients with recurrent infections were successfully reimplanted after an additional one-stage procedure and four patients were not reimplanted. Two of these four had amputations and the other two had a second two-stage procedure and have retained their spacers. There were seven complications including a broken spacer, three periprosthetic fractures, two contractures, and one case of aseptic loosening. Successful limb salvage with infection control was 19/23 (83%). One patient required an amputation for local recurrence of their tumor. The overall limb salvage rate was 18/23 (78%). Stable temporary antibiotic laden cement spacers, made in conjunction with standard intramedullary nails, can provide the necessary limb stability to treat musculoskeletal infections and allow for reimplanation of tumor prostheses for limb salvage

Patients with skeletal dysplasia are prone to developing advanced degenerative knee disease requiring total knee replacement (TKR) at a younger age than the general population. TKR in this unique group of patients is a technically demanding procedure due to the bone deformity, flexion contracture, generalised hypotonia and ligamentous laxity. We set out to retrospectively review the outcome of 11 TKR's performed in eight patients with skeletal dysplasia at our institution using the SMILES custom-made rotating-hinge total knee system. There were 3 males and 5 females with mean age 57 years (range, 41–79 years), mean height 138 cm (range, 122–155 cm) and mean weight 56 kg (range, 40–102 kg). Preoperative diagnoses included achondroplasia, spondyloepiphyseal dysplasia, pseudoachondroplasia, multiple epiphyseal dysplasia, morquio syndrome, diastrophic dysplasia and Larson's Syndrome. Patients were followed clinically and radiographically for a mean of 7 years (range, 3–11.5 years). Knee pain and function improved in all 11 joints. Mean Knee Society clinical and function scores improved from 24 (range, 14–36) and 20 points (range, 5–40) preoperatively to 68 (range, 28–80) and 50 points (range, 22–74) respectively at final follow-up. Four complications were recorded (36%), including a patellar fracture following a fall, a tibial periprosthetic fracture, persistent anterior knee pain and a femoral component revision for aseptic loosening. Our results suggest that custom rotating-hinge TKR in patients with skeletal dysplasia is effective at relieving pain, optimising movement and improving function. It compensates for bony deformity and ligament deficiency and reduces the need for corrective osteotomy. Patellofemoral joint complications are frequent and functional outcome is worse than primary TKR in the general population. Submission endorsed by Mr Peter Calder, Consultant Orthopaedic Surgeon and Society member