Aims

Pelvic discontinuity is a rare but increasingly common complication of total hip arthroplasty (THA). This single-centre study evaluated the performance of custom-made triflange acetabular components in acetabular reconstruction with pelvic discontinuity by determining: 1) revision and overall implant survival rates; 2) discontinuity healing rate; and 3) Harris Hip Score (HHS).

Summary Statement

In this study, excellent positioning of custom-made glenoid components was achieved using patient-specific guides. Achieving the preoperatively planned orientation of the component improved significantly and more screws were located inside the scapular bone compared to implantations without such guide.

In severe cases of total knee arthroplasty which cannot be treated with off-the-shelf implants anymore custom-made knee implants may serve as one of the few remaining options to restore joint function or to prevent limb amputation. Custom-made implants are specifically designed and manufactured for one individual patient in a single-unit production, in which the surgeon is responsible for the implant design characteristics in consultation with the corresponding engineer. The mechanical performance of these custom-made implants is challenging to evaluate due to the unique design characteristics and the limited time until which the implant is needed. Nevertheless, the custom-made implant must comply with clinical and regulatory requirements. The design of custom-made implants is often based on a underlying reference implant with available biomechanical test results and well-known clinical performance. To support surgeons and engineers in their decision whether a specific implant design is suitable, a method is proposed to evaluate its mechanical performance. The method uses finite element analysis (FEA) and comprises six steps: (1) Identification of the main potential failure mechanism and its corresponding FEA quantity of interest. (2) Reproduction of the biomechanical test of the reference implant via FEA. (3) Identification of the maximum value of the corresponding FEA quantity of interest at the required load level. (4) Definition of this value as the acceptance criteria for the FEA of the custom-made implant. (5) Reproduction of the biomechanical test with the custom-made implant via FEA. (6) Conclusion whether the acceptance criteria is fulfilled or not. The method was applied to two exemplary cases of custom-made knee implants. The FEA acceptance criteria derived from the reference implants were fulfilled in both custom-made implants. Subsequent biomechanical tests verified the FEA results. This study suggests and applies a non-destructive and efficient method for pre-clinical testing of a single-unit custom-made knee implant to evaluate whether the design is mechanically suitable

In severe cases of total knee & hip arthroplasty, where off-the-shelf implants are not suitable (i.e., in cases with extended bone defects or periprosthetic fractures), 3D-printed custom-made knee & hip revision implants out of titanium or cobalt-chromium alloy represent one of the few remaining clinical treatment options. Design verification and validation of such custom-made implants is very challenging. Therefore, a methodology was developed to support surgeons and engineers in their decision on whether a developed design is suitable for the specific case. A novel method for the pre-clinical testing of 3D-printed custom-made knee implants has been established, which relies on the biomechanical test and finite element analysis (FEA) of a comparable clinically established reference implant. The method comprises different steps, such as identification of the main potential failure mechanism, reproduction of the biomechanical test of the reference implant via FEA, identification of the maximum value of the corresponding FEA quantity of interest at the required load level, definition of this value as the acceptance criterion for the FEA of the custom-made implant, reproduction of the biomechanical test with the custom-made implant via FEA, decision making for realization or re-design based on the acceptance criterion is fulfilled or not. Exemplary cases of custom-made knee & hip implants were evaluated with this new methodology. The FEA acceptance criterion derived from the reference implants was fulfilled in both custom-made implants and subsequent biomechanical tests verified the FEA results. The suggested method allows a quantitative evaluation of the biomechanical properties of custom-made knee & hip implant without performing physical bench testing. This represents an important contribution to achieve a sustainable patient treatment in complex revision total knee & hip arthroplasty with custom-made 3D printed implants in a safe and timely manner

In the last years, 3d printing has progressively grown and it has reached a solid role in clinical practice. The main applications brought by 3d printing in orthopedic surgery are: preoperative planning, custom-made surgical guides, custom-made im- plants, surgical simulation, and bioprinting. The replica of the patient's anatomy, starting from the elaboration of medical volumetric images (CT, MRI, etc.), allows a progressive extremization of treatment personalization that could be tailored for every single patient. In complex cases, the generation of a 3d model of the patient's anatomy allows the surgeons to better understand the case — they can almost “touch the anatomy” —, to perform a more ac- curate preoperative planning and, in some cases, to perform device positioning before going to the surgical room (i.e. joint arthroplasty). 3d printing is also commonly used to produce surgical cutting guides, these guides are positioned intraoperatively on given landmarks to guide the surgeon to perform a specific surgical act (bone osteotomy, bone resection, implant position, etc.). In total knee arthroplasty, custom-made cutting guides have been developed to help the surgeon align the femoral and tibial components to the pre-arthritic condition with- out the use of the intramedullary femoral guide. 3d printed custom-made implants represent an emerging alternative to biological reconstructions especially after oncologic resection surgery or in case of complex arthroplasty revision surgery. Custom-made implants are designed to re- place the original shape and size of the patient's bone and they allow an extreme personalization of the treatment for every single patient. Patient-specific surgical simulation is a new frontier that promises great benefits for surgical training. a solid 3d model of the patient's anatomy can faithfully reproduce the surgical complexity of the patient and it allows to generate surgical simulators with increasing difficulty to adapt the difficulties of the course with the level of the trainees performing structured training paths: from the “simple” case to the “complex” case

Contemporary acetabular reconstruction in major acetabular bone loss often involves the use of porous metal augments, a cup-cage construct or custom implant. The aims of this study were: To determine the reproducibility of a reconstruction algorithm in major acetabular bone loss. To determine the subsequent success of reconstruction performed in terms of re-operation, all-cause revision and Oxford Hip Score (OHS) and to further define the indications for custom implants in major acetabular bone loss. Consecutive series of Paprosky Type III defects treated according to a reconstruction algorithm. IIIA defects were planned to use a superior augment and hemispherical cup. IIIB defects were planned to receive either augment and cup, cup-cage or custom implant. 105 procedures in cohort 100 patients (5 bilateral) with mean age 73 years (42–94). IIIA defects (50 cases) − 72.0% (95%CI 57.6–82.1) required a porous metal augment the remainder treated with a hemispherical cup alone. IIIB defects (55 cases) 71.7% (95%CI 57.6–82.1) required either augments or cup-cage. 20 patients required a hemispherical cup alone and 6 patients received a custom-made implant. Mean follow up of 7.6 years. 6 re-revisions were required (4 PJI, 2 peri-prosthetic fractures & 1 recurrent instability) with overall survivorship of 94.3% (95% CI 97.4–88.1) for all cause revision. Single event dislocations occurred in 3 other patients so overall dislocation rate 3.8%. Mean pre-op OHS 13.8 and mean follow-up OHS 29.8. Custom implants were used in: Mega-defects where AP diameter >80mm, complex discontinuity and massive bone loss in a small pelvis (i.e., unable to perform cup-cage). A reconstruction algorithm can >70% successfully predict revision construct which thereafter is durable with a low risk of re-operation. Jumbo cup utilized <1/3 of cases when morphology allowed. The use of custom implants has been well defined in this series and accounts for <5% of cases

Abstract. Background. Distal femoral osteotomy is an established successful procedure which can delay the progression of arthritis and the need for knee arthroplasty. The surgery, however, is complex and lengthy and consequently it is generally the preserve of highly experienced specialists and thus not widely offered. Patient specific instrumentation is known to reduce procedural complexity, time, and surgeons’ anxiety levels. 1. in proximal tibial osteotomy procedures. This study evaluated a novel patient specific distal femoral osteotomy procedure (Orthoscape, Bath, UK) which aimed to use custom-made implants and instrumentation to provide a precision correction while also simplifying the procedure so that more surgeons would be comfortable offering the procedure. Presenting problem. Three patients (n=3) with early-stage knee arthritis presented with valgus malalignment, the source of which was predominantly located within the distal femur, rather than intraarticular. Using conventional techniques and instrumentation, distal femoral knee osteotomy cases typically require 1.5–2 hours surgery time. The use of bi-planar osteotomy cuts have been shown to improve intraoperative stability as well as bone healing times. 2. This normally also increases surgical complexity; however, multiple cutting slots can be easily incorporated into patient specific instrumentation. Clinical management. All three cases were treated at a high-volume tertiary referral centre (Istituto Ortopedico Rizzoli, Bologna) using medial closing wedge distal femoral knee osteotomies by a team experienced in using patient specific osteotomy systems. 3. Virtual surgical planning was conducted using CT-scans and long-leg weight-bearing x-rays (Orthoscape, Bath, UK). Patient specific surgical guides and custom-made locking plates were design for each case. The guides were designed to allow temporary positioning, drilling and bi-planar saw-cutting. The drills were positioned such that the drills above and below the osteotomy became parallel on closing following osteotomy wedge removal. This gave reassurance of the achieved correction allowed the plate to be located precisely over the drills. All screw lengths were pre-measured. Discussion. The surgical time reduced to approximately 30 minutes by the third procedure. It was evident that surgical time was saved because no intraoperative screw length measurements were required, relatively few x-rays were used to confirm the position of the surgical guide, and the use of custom instrumentation significantly reduced the surgical inventory. The reduced invasiveness and ease of surgery may contribute to faster patient recovery compared to conventional techniques. The final post-operative alignment was within 1° of the planned alignment in all cases. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Among the advanced technology developed and tested for orthopaedic surgery, the Rizzoli (IOR) has a long experience on custom-made design and implant of devices for joint and bone replacements. This follows the recent advancements in additive manufacturing, which now allows to obtain products also in metal alloy by deposition of material layer-by-layer according to a digital model. The process starts from medical image, goes through anatomical modelling, prosthesis design, prototyping, and final production in 3D printers and in case post-production. These devices have demonstrated already to be accurate enough to address properly the specific needs and conditions of the patient and of his/her physician. These guarantee also minimum removal of the tissues, partial replacements, no size related issues, minimal invasiveness, limited instrumentation. The thorough preparation of the treatment results also in a considerable shortening of the surgical and of recovery time. The necessary additional efforts and costs of custom-made implants seem to be well balanced by these advantages and savings, which shall include the lower failures and revision surgery rates. This also allows thoughtful optimization of the component-to-bone interfaces, by advanced lattice structures, with topologies mimicking the trabecular bone, possibly to promote osteointegration and to prevent infection. IOR's experience comprises all sub-disciplines and anatomical areas, here mentioned in historical order. Originally, several systems of Patient-Specific instrumentation have been exploited in total knee and total ankle replacements. A few massive osteoarticular reconstructions in the shank and foot for severe bone fractures were performed, starting from mirroring the contralateral area. Something very similar was performed also for pelvic surgery in the Oncology department, where massive skeletal reconstructions for bone tumours are necessary. To this aim, in addition to the standard anatomical modelling, prosthesis design, technical/technological refinements, and manufacturing, surgical guides for the correct execution of the osteotomies are also designed and 3D printed. Another original experience is about en-block replacement of vertebral bodies for severe bone loss, in particular for tumours. In this project, technological and biological aspects have also been addressed, to enhance osteointegration and to diminish the risk of infection. In our series there is also a case of successful custom reconstruction of the anterior chest wall. Initial experiences are in progress also for shoulder and elbow surgery, in particular for pre-op planning and surgical guide design in complex re-alignment osteotomies for severe bone deformities. Also in complex flat-foot deformities, in preparation of surgical corrections, 3D digital reconstruction and 3D printing in cheap ABS filaments have been valuable, for indication, planning of surgery and patient communication; with special materials mimicking bone strength, these 3D physical models are precious also for training and preparation of the surgery. In Paediatric surgery severe multi planar & multifocal deformities in children are addressed with personalized pre-op planning and custom cutting-guides for the necessary osteotomies, most of which require custom allografts. A number of complex hip revision surgeries have been performed, where 3D reconstruction for possible final solutions with exact implants on the remaining bone were developed. Elective surgery has been addressed as well, in particular the customization of an original total ankle replacement designed at IOR. Also a novel system with a high-tibial-osteotomy, including a custom cutting jig and the fixation plate was tested. An initial experience for the design and test of custom ankle & foot orthotics is also in progress, starting with 3D surface scanning of the shank and foot including the plantar aspect. Clearly, for achieving these results, multi-disciplinary teams have been formed, including physicians, radiologists, bioengineers and technologists, working together for the same goal

Introduction. Bone loss management represents one of the most challenging issues for the orthopaedic surgeon. In most cases, stems, structural allograft, TMcones, and sleeves are adequate to allow optimal implant stability and durable fixation. In selected cases of wide metadiaphyseal bone defects, these devices do not provide proper intraoperative stability. In such scenarios, further steps are needed and include complex modular reconstruction, substitution with megaprosthesis (exposing patients at high risk of early failure) or joint arthrodesis that can yield unacceptable results. The aim of this paper is to present early results obtained with a new custom-made implant for complex metadiaphyseal bone defects management in knee revision surgery. By means of case presentations the authors would highlight the possibilities and technical notes of this novel device in complex knee revision surgery. Methods. Since2015, 8 custom-made porous titanium devices were implanted for massive bone defect management in 6 knee arthroplasty revision procedures. Five patients were staged revision for periprosthetic joint infection (PJI) and one patient underwent a staged revision for post-traumatic septic arthritis. Main demographic and surgical data were collected. Clinical (Range of Movement [ROM], Knee Society Score [KSS] and Oxford Knee Score [OKS]), radiological findings and complications were recorded at different time points and statistically evaluated. Mean follow up was 19.5 ± 9.6months. Results. The study group included 4 males and 2 females with a mean age of 63.7 ± 5.5 years and a mean Body Mass Index of 29.3 ± 4.1. Globally, the mean number of previous surgeries was 4.8 ± 2.7. The custom made device was combined with a hinged prosthesis in 5 cases and with a constrained condylar implant in 1 patient. Hybrid fixation was used in all cases. The mean KSS and OKS of the entire population improved significantly from 35.3 ±6.5 and 19.2 ±3.5 preoperatively to 85.8 ±4.0 and 39.3 ±3.1 at the time of last follow-up evaluation (p<0.01). The range of motion improved from 46.7 ±9.8 of mean preoperative flexion and 7.8 ±6.8 of mean preoperative flexion contracture to 93.3 ±10.3 and 1.2 ±2.9 respectively (p<0.01). Radiological analysis showed no migration or implant loosening. No intraoperative or postoperative complication was recorded. One patient required a prolonged antibiotic therapy for positive culture samples of sonication of the retrieved spacer. No implant mismatch between the preoperative planning and the final implant was reported. Conclusion. The presented custom-made implant showed promising early clinical and radiological results. In extremely selected cases, this new device can be considered a safe and effective surgical step between “off the shelf” reconstruction implants and knee substitution with a tumor megaprosthesis. Accurate surgical planning and intraoperative management of soft tissues and residual bone stock are of paramount importance

Introduction and Purposes. Custom made acetabular prosthesis are a valid option for the reconstruction after the resection of pelvic tumors. They should guarantee a stable and reliable reconstruction for the expected survival of the patient. Nevertheless in many cases periacetabular metastatic lesions have been compared to high grade (IIIA-B) Paprosky defects, but treated with low or intermediate longevity implants. Some complex post-traumatic scenarios or total hip arthroplasty (THA) multiple failures need a reconstruction according to oncologic criteria to fill in the huge defect and to obtain an acceptable function. The aim of the study is to compare 3D custom-made implants for tumors and for THA failures. Materials and Methods. Three custom-made implants after tumor resection (group A: 1 chondroblastic osteosarcoma, 1 bifasic synovialsarcoma, 1 high grade chondrosarcoma) were evaluated and compared to 3 acetabular complex reconstructions after non-oncologic bone defect (group B: 3 cases of aseptic loosening after at least 2 revisions). All the implants were case-based designed, 3D printed, and realized with porous or trabecular surfaces on a Titanium base prosthesis. Age range 16–70 ys in oncologic patients and 60–75 ys in non-oncologic patients. The bone defect to be reconstructed after tumor resection was classified according to Enneking zones (1 type 1-2-3 resection, 1 type 2 resection, 1 partial type 2 resection). Non-oncologic cases were comparable in term of remaining bone stock and classified according to Paprosky classification for acetabular defects as 1 type IIIA an 2 type IIIB. Complications, MSTS functional score, necessity of walking-aids were evaluated at minimum follow up of 1 year. Results. In both groups, good functional results were obtained (MSTS score 25/30 in both groups). No cases of aseptic loosening and no infection occured. After 3 months of partial or no weight-bearing on the operated limb, 3 patients were able to walk unaided and 3 walked with one cane or crutch. No limb length discrepancy (major than 2 cm) were observed. Limping was present in oncologic cases due to muscle resection. Overall better results in term of satisfaction and quality of life were obtained in younger (oncologic) patients. Conclusions. Complex THA revision cases can sometimes be considered for a reconstruction with oncologic criteria. Even if indications are limited an acceptable functional results can be obtained. In the past for these cases a Girldestone resection was the only option. A collaboration among orthopaedic oncologist and hip arthroplasty surgeons is advisable in major orthopaedic centers to improve the prosthetic design and the functional results

Literature data show varying rates of aseptic loosening of standard hemispherical cups after primary total hip arthroplasty (THA) in patients with Crowe IV developmental dysplasia of the hip (DDH). In order to improve the results regarding the frequency of aseptic loosening of the acetabular component, we decided to use custom-made acetabular implants (CMAI) in this category of patients. The aim of our study was to report outcomes after primary THA using CMAI in patients with Crowe IV DDH. We retrospectively analyzed the results of primary THA using the CMAI in 58 hips. The mean follow-up period was 5.2 years (range 4.2 – 6.3). Patients demonstrated improved functional outcomes according to the Oxford Hip Score: preoperatively 16.9 and postoperatively 38.5 (P < 0.05). Revisions were performed in 2 cases due to dislocations, in 1 case due to nonunion of the greater trochanter and in 1 case due to chronic pain syndrome caused by contact of the CMAI flange with the iliopsoas muscle. In a patient with chronic pain syndrome, during the revision, the pubic flange of the CMAI, which was in contact with the iliopsoas muscle, was removed. There were no radiological signs of loosening of the CMAI. The use of CMAI shows good results in patients with DDH. Extended capability for supplementary screw fixation is an excellent feature of such implants, allowing them to obtain reliable primary fixation. Further observation is required to assess CMAI in the long-term follow-up

Purpose: This multicentric retrospective study was conducted to search for indications of femoral revision with a custom-made non-cemented implant. Material and methods: We collected files on femoral revisions using custom-made implants among our working group and among surgeons having a certain experience between 1989 and 1991. Twenty-one patients (13 men and 10 women), mean age 50.1 years (24–81) were operated. This was the first revision for 14, the second for six, and the third for two. Mean follow-up was 35.4 years. The implant was coated with hydroxyapatite in the proximal zone with optional distal locking except for the first cases. The implant was used when the usual implants were poorly adapted. Data acquisition was achieved with previous calibrated computed tomography. The problem was to distinguish residual bone from cement or the prior implant. Information was exchanged between the engineer and the surgeon in order to define the stem shape and anchorage. Regular clinical follow-up was performed, noting the Postel Merle d’Aubligné score. The radiographic assessment focused on the absence of prosthesis descent and lucent lines. Results: The PMA score improved from 9.6 (6–14; 2.4; 4.26; 2.91) to 14 (8–18; 4.61; 5.05; 4.25). Complications were dislocation in three hips, one requiring cup replacement and the other neck replacement. Early descent of the femoral stem was also noted in one hip which required revision. Late descent at 13 years was managed by a simple procedure in one hip (SOFCOT stage I). Discussion: The early failures were related to the severity of the initial lesions (or rather their underestimation) and to defective initial distal stabilisation. Late failures resulted from the absence of bioreactive coating. We have had no experience with impacted grafting. The indication for custom-made implants are exceptional (less than 2% of our revisions) and can be divided into four categories: extramedullary (very long neck/varus) the implant avoiding the use of balls; extrapolation (femur too small or too large requiring under- or oversized implant); dysmorphism (excessive curvature, osteotomy or fracture sequelae, narrow metaphysic with wide diaphysis); gap filling (weight-bearing zone). Conclusion: The advantage of a custom-made implant is the choice of anchorage and the simplification of the operative procedure. It is often the only solution in complex situations but requires close collaboration with the engineer (virtual intervention) and implies significant cost

Total Knee Arthroplasty (TKA) patients may present with effusion, pain, stiffness and functional impairment. A positive metal hypersensitivity (positive LTT) may be an indication for a revision surgery with a custom-made implant devoid of any hypersensitivity-related metal or an implant with the least possible ion content of the metal hypersensitivity, if no custom-made is available. The purpose of the current study is to assess the prevalence of metal hypersensitivity in subjects requiring a primary TKA and assess their early functional outcomes. We are recruiting 660 subjects admitted for TKA. Subjects are randomly assigned to 2 groups: oxidized zirconium implant group or cobalt-chrome implant group. Functional outcomes and quality of life (QoL) are measured pre operatively, 3, 6 and 12 months post operatively with WHOQOL-BREF (domain1-Physical Health, domain 2- Psychological, domain 3- Social relationships, domain 4-Environment), KSS, KOOS and pain Visual Analog Scale (VAS). LTT and metal ions are evaluated pre operatively and 12 months post-surgery. One hundred-sixty patients, 98 women, were enrolled in the study. Mean age was 65.6±8.9. Mean follow up (FU) was 7.1±3.8 months. Eighty-one (50.6%) were randomised in the cobalt-chrome group. Infection rate was 1.9%, one patient required debridement. Three patients (1.9%) presented with contracture at three months FU. At 12 months, WHOQOL-BREF domain 1, 2 and 4 improved significantly (p0,05). Overall, all 160 patients improved their functional outcomes and QoL. At 12 months, VAS scores decreased from 7±2.06 at baseline to 1.95±2.79. Furthermore, the high prevalence of positive LTT (27/65) do not seem to affect early functional outcomes and QoL on patients that may have received a potential implant with hypersensitivity (18/27)

Aims

The aim of this study was to assess the clinical and radiological results of patients who were revised using a custom-made triflange acetabular component (CTAC) for component loosening and pelvic discontinuity (PD) after previous total hip arthroplasty (THA).

Most acetabular defects can be treated with a cementless acetabular cup and screw fixation. However, larger defects with segmental bone loss and discontinuity often require reconstruction with augments, a cup-cage, or triflange component – which is a custom-made implant that has iliac, ischial, and pubic flanges to fit the outer table of the pelvis. The iliac flange fits on the ilium extending above the acetabulum. The ischial and pubic flanges are smaller than the iliac flange and usually permit screw fixation into the ischium and pubis. The custom triflange is designed based on a pre-operative CT scan of the pelvis with metal artifact reduction, which is used to generate a three-dimensional image of the pelvis and triflange component. The design of the triflange involves both the manufacturing engineer and surgeon to determine the most appropriate overall implant shape, screw fixation pattern, and cup location and orientation. A plastic model of the pelvis, and triflange implant can be made in addition to the triflange component to be implanted, in order to assist the surgeon during planning and placement of the final implant in the operating room. A wide surgical exposure is needed including identification of the sciatic nerve. Proximal dissection of the abductors above the sciatic notch to position the iliac flange can risk denervation of the abductor mechanism. Blood loss during this procedure can be excessive. Implant survivorship of 88 to 100% at 53-month follow-up has been reported. However, in a series of 19 patients with Paprosky type 3 defects, only 65% were considered successful. The custom triflange also tends to lateralise the hip center which may adversely affect hip mechanics. The use of a triflange component is indicated in cases with massive bone loss or discontinuity in which other reconstructive options are not considered suitable

Aims

Custom-made partial pelvis replacements (PPRs) are increasingly used in the reconstruction of large acetabular defects and have mainly been designed using a triflange approach, requiring extensive soft-tissue dissection. The monoflange design, where primary intramedullary fixation within the ilium combined with a monoflange for rotational stability, was anticipated to overcome this obstacle. The aim of this study was to evaluate the design with regard to functional outcome, complications, and acetabular reconstruction.

Purpose: The rate of failure knee arthrodesis can be high when performed after an infectious complication of a total knee arthroplasty. We evaluated, in 14 patients at a mean 19 months (3–44 months) follow-up, a technique for knee arthrodesis using a custom-made endomedullary implant. Material and methods: Mean age of these eight women and six men was 68 years. There were 11 patients with an infected prosthesis, one with post-trauma arthritis, one with aseptic loosening of a hinge prosthesis, and one with pseudarthrodesis. For the 12 patients with ongoing infection, surgery was performed in two times with insertion of a spacer (with antibiotics) between the operations. Mean delay between the two operations was 18 weeks. The surgical procedure was associated with a two-drug antibiotic regimen given for a mean three months after arthrodesis. All arthrodeses were stabilised with a custom-made femora-tibial implant with reaming and fixation with two screws. A graft was always used, composed of the reaming products and powder bone substitute in seven cases, reaming products alone in three, and bone-bank heads in four. Results: Morbitiy: There was one misalignment of the tibial insertion that was not revised. One skin cover problem was treated with a vastus medius flap. One nonunion evolved favourably after a new graft. There were two recurrent infections: chronic fistulae that were controlled by local care and adapted antibiotic therapy. Weight-bearing was started during the first postoperative week in 13 patients. Bone healing (assessed radiographically with resolution of pain) was achieved at a mean three months (2–6 months) in 13 cases. At last follow-up all patients had achieved a satisfactory level of independence. Discussion: According to the literature, intramedullary devices are superior for consolidating knee arthrodeses, with a lower rate of complications. Use of custom-made endo-medullary implants facilitates the operation and assures better stabilisation of the arthrodesis, allowing rapid weight-bearing. The infection must be controlled before using these implants. The results in our patients are in agreement with the most recent series reported (Barry, Stephen, Kuoan). Conclusion: In our hands, this type of implant provides an effective means of attaining bony fusion, including in patients who require arthrodesis for an infected prosthesis

The Total Knee Replacement (TKR) has been used as the effective treatment for osteoarthritis of the knee. The load of the knee joint is generally applied at the heel strike as the impact loading. In the elderly who had muscle weakness or weakening eyesight, it can be anticipated that more excessive loads are often added to the knees when they stumble or trip over. And the varus / valgus alignments of the femur and tibia differs among patients. However, most finite element analyses considering the effect of the alignments have rarely been performed. In this study, the mounting angle of the tibia component in the TKR knee was changed, and the effect of the change on the load transfer was assess using finite element analyses. Based on the CT images, the three-dimensional finite element models of the natural knee joint and TKR knee joint were created [Fig. 1]. Each model was constructed from hexahedoral elements with the isotropic material. The numbers of nodes and elements were 10,666 and 8,677 respectively. Under normal alignment, 5 degrees of varus, and 5 degrees of valgus knee, the static analyses at an applied load of 1000N and impact analyses at an applied load of 50 kg were performed. LS-DYNA ver760 software was used for the analyses. The finite element analyses results showed that under the static loading, no stress shielding was observed in the tibial cancellous bone of the intact knee or TKR knee, and the maximum compressive stress was 1.5 MPa. While under the impact loading, the compressive stress generated inside of the cancellous bone was three times higher in the TKR knee joint than that in the intact knee, and the load transfer time was reduced. This result reveals that the cancellous bone have load bearing function especially in the impact condition. When the impact load was applied to the varus and valgus TKR knee, the stress shielding was observed in the tibial cancellous bone, especially in the varus condition. In a case where the tibia component was mounted by tilting it at −5 to 5 degrees depending on the varus/valgus of the knee, the stress shielding was alleviated; the distribution of load was almost the same as that of the TKR knee joint model under the normal alignment [Fig.2]. The effect of a slight difference in the alignment on the stress distribution is expected to be a contributor to determine artificial knee joint shape, loading condition, and other design factors in developing revision arthroplasty or custom-made implant

Introduction. We discuss the use of the SMILES (Stanmore Modular Individualised Lower Extremity System) in salvage revision knee surgery and review the medium-long term results of 42 cases. Methods. This is a prospective, single-centre study. The SMILES prosthesis is a custom-made implant incorporating a rotating hinge knee joint. 42 prostheses were used in 40 patients as salvage revision procedures between September 1991 and September 1999. Patients undergoing surgery for tumours were excluded. The minimum follow-up was seven years with a mean follow-up of ten years and six months. Patients were independently assessed using the Knee Society Rating Score. The age of the patients ranged from 36-85 years (mean 68 years and 6 months). 23 of the patients were male. The original pathology was osteoarthritis in 32 patients and rheumatoid arthritis in 8 patients. The number of previous arthroplasties ranged from 1-4. The main indications for a SMILES prosthesis were aseptic loosening, periprosthetic fracture and infection in the presence of bone loss and ligamentous laxity. Results. There was a highly statistically significant improvement in overall Knee Society scores from a mean of 26 pre-op to 72 post-op. The mean knee score improved from 26 pre-op to 68 post-op while the mean function score improved from 27 to 75. The average range of motion was 60 degrees pre-op and 90 degrees post-op. Complications included: failure to eradicate infection in two patients, with one patient needing amputation; infection of the prosthesis leading to revision in one, and failure of the tibial component needing revision. Conclusion. The SMILES has produced satisfactory results in the medium to long term, offering an alternative to amputation in some cases. The cost compares favourably with other designs and the use is increasing in frequency

Objective:. Patient-specific or “custom” total knee replacements have been designed to fit the arthritic knee in primary total knee arthroplasty (TKA) better than “off-the-shelf” implants. Using computer technology, patient-specific cutting-blocks and custom-made implants are created to more accurately fit the contour of the knee and reproduce the anatomic J-curve with the hope of providing a better functional outcome. Purpose:. This retrospective, matched-pair study evaluates manipulation under anesthesia (MUA) rates in cemented patient-specific cruciate-retaining (PSCR) TKA compared to that in both cemented posterior-stabilized (PS) and non-cemented cruciate-retaining rotating-platform (NC CR RP) TKA. Materials and Methods:. From 2010 through November of 2012, 21 PSCR TKAs were performed in 19 patients. Using medical records from our patient database, these patients were matched for age, side, deformity, diagnosis, Charnley Class, and preoperative range of motion (ROM) with 42 PS TKAs performed during the same time period by the same surgeon using the same intra- and post-operative protocols. Additionally, 11 NC CR RP TKA were performed and evaluated based on the same criteria. Pre- and postoperative radiographs were performed using criteria as described by The Knee Society. Results:. Preoperatively the custom CR RP TKA cohort had a larger average ROM compared to the PS TKA cohort (P-value = 0.006). Postoperatively, however, the custom CR RP TKA cohort overall was found to have a significantly decreased average ROM compared to both the PS and NC CR RP TKA cohorts (2.0°–110.6° P-value = 0.0002 and 2.4°–117.3° P-value = 0.0003, respectively). 6 of the 21 (28.6%) PSCR TKAs performed underwent MUA to improve postoperative ROM. One manipulation was unsuccessful and the patient is scheduled for revision for arthrofibrosis. No patients in either the matched PS group or the CR RP group underwent postoperative MUA. Clinical and radiographic analysis including pre-operative ROM, deformity, side, Charnley Class, posterior tibial slope angle, epicondylar axis and posterior condylar offsets provided no insight into the reason for this higher MUA rate in the PSCR knees. Conclusion:. MUA rates in the patient-specific TKA group were significantly higher than that in the matched PS and NC CR RP groups. No correlations were found to clearly indicate the cause of the higher MUA rate among the PSCR knees. Early manipulation is recommended for stiffness with these custom devices. Level of Evidence: Level III, Retrospective comparative study. Keywords: Patient-specific total knee, Manipulation, TKA