Aims. Prior cost-effectiveness analyses on osseointegrated prosthesis for transfemoral unilateral amputees have analyzed outcomes in non-USA countries using generic quality of life instruments, which may not be appropriate when evaluating disease-specific quality of life. These prior analyses have also focused only on patients who had failed a socket-based prosthesis. The aim of the current study is to use a disease-specific quality of life instrument, which can more accurately reflect a patient’s quality of life with this condition in order to evaluate cost-effectiveness, examining both treatment-naïve and socket refractory patients. Methods. Lifetime Markov models were developed evaluating active healthy middle-aged male amputees. Costs of the prostheses, associated complications, use/non-use, and annual costs of arthroplasty parts and service for both a socket and osseointegrated (OPRA) prosthesis were included. Effectiveness was evaluated using the questionnaire for persons with a transfemoral amputation (Q-TFA) until death. All costs and Q-TFA were discounted at 3% annually. Sensitivity analyses on those cost variables which affected a change in treatment (OPRA to socket, or socket to OPRA) were evaluated to determine threshold values. Incremental cost-effectiveness ratios (ICERs) were calculated. Results. For treatment-naïve patients, the lifetime ICER for OPRA was $279/quality-adjusted life-year (QALY). For treatment-refractory patients the ICER was $273/QALY. In sensitivity analysis, the variable thresholds that would affect a change in the course of treatment based on cost (from socket to OPRA), included the following for the treatment-naïve group: yearly replacement components for socket > $8,511; cost yearly replacement parts OPRA < $1,758; and for treatment-refractory group: yearly replacement component for socket of > $12,467. Conclusion. The use of the OPRA prosthesis in physically active transfemoral amputees should be considered as a cost-effective alternative in both treatment-naïve and treatment-refractory socket prosthesis patients. Disease-specific quality of life assessments such as Q-TFA are more sensitive when evaluating cost-effectiveness. Cite this article: Bone Jt Open 2024;5(3):218–226

Aims. Safety concerns surrounding osseointegration are a significant barrier to replacing socket prosthesis as the standard of care following limb amputation. While implanted osseointegrated prostheses traditionally occur in two stages, a one-stage approach has emerged. Currently, there is no existing comparison of the outcomes of these different approaches. To address safety concerns, this study sought to determine whether a one-stage osseointegration procedure is associated with fewer adverse events than the two-staged approach. Methods. A comprehensive electronic search and quantitative data analysis from eligible studies were performed. Inclusion criteria were adults with a limb amputation managed with a one- or two-stage osseointegration procedure with follow-up reporting of complications. Results. A total of 19 studies were included: four one-stage, 14 two-stage, and one article with both one- and two-stage groups. Superficial infection was the most common complication (one-stage: 38% vs two-stage: 52%). There was a notable difference in the incidence of osteomyelitis (one-stage: nil vs two-stage: 10%) and implant failure (one-stage: 1% vs two-stage: 9%). Fracture incidence was equivocal (one-stage: 13% vs two-stage: 12%), and comparison of soft-tissue, stoma, and mechanical related complications was not possible. Conclusion. This review suggests that the one-stage approach is favourable compared to the two-stage, because the incidence of complications was slightly lower in the one-stage cohort, with a pertinent difference in the incidence of osteomyelitis and implant failure. Cite this article: Bone Jt Open 2023;4(7):539–550

Introduction. Clione Anchored Replacement Prosthesis (CARP-H system) is a novel femoral implant for cementless fixation at the metaphysis of the proximal femur and preservation of cancellous bone of the femoral diaphysis is expected (Fig.1). We developed CARP-H system and started to use the prosthesis after the approval by Pharmaceuticals and Medical Devices Agency in 2012. This study examines the efficacy and short-term outcome of CARP-H system in a series of patients undergoing total hip arthroplasty (THA) or bipolar hemi-arthroplasty (BHA). Patients and Methods. Seventeen patients (17 hips) of osteonecrosis of the femoral head (ON) or osteoarthritis of the hip (OA) were included. The diagnoses were OA in 10 patients, and ON in 7 patients. The mean age at surgery was 55 years (35–62 years). The mean follow-up was 12 months (6–19 months). THA using CARP-H system was performed in 11 hips and BHA in 6 hips. Results. The mean clinical score with the Merle d'Aubigne and Postel system was improved from 8 points preoperatively to 16 points at follow-up. No complications such as infection, dislocation, intraoperative fracture, or pulmonary infarction were identified. No radiolucent line around the prosthesis was observed postoperatively. Discussion and Conclusion. We used to perform THA using the thrust plate hip prosthesis (TPP) which is an outstanding prosthesis for young patients in terms of bone preservation and biological fixation. Our mid- or long-term outcome of TPP was satisfactory provided the indication was appropriate. However, TPP has been kicked out in our country since 2006. The structural concept of CARP-H system is derived from TPP, and the design of the prosthesis is modified in order to adapt to Japanese patients. CARP-H system could be a beneficial prosthesis from the viewpoint of bone-preservation at the proximal femur

Aims. The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes. Methods. A retrospective consecutive study of all patients who underwent a rTKA using the fully cemented SMILES rotating hinge prosthesis between 2005 to 2018. Outcome measures included aseptic loosening, reoperations, revision for any cause, complications, and survivorship. Patients and implant survivorship data were identified through both prospectively collected local hospital electronic databases and linked data from the National Joint Registry/NHS Personal Demographic Service. Kaplan-Meier survival analysis was used at ten years. Results. Overall, 69 consecutive patients (69 knees) were included with a median age of 78 years (interquartile range 69 to 84), and there were 46 females (66.7%). Indications were septic revisions in 26 (37.7%), and aseptic aetiology in the remining 43 (62.3%). The mean follow-up was 9.7 years (4 to 18), and the overall complication was rate was 7.24%, all with patellofemoral complications. Failure rate with ‘any cause revision’ was 5.8%. There was one case of aseptic loosening of the femoral component. At ten years, 17/69 patients (24.63%) had died, and implant survivorship was 92.2%. Conclusion. In our experience, the SMILES rotating hinge prosthesis achieves satisfactory long-term outcomes with ten-year implant survivorship of 92.2% and a patellofemoral complication rate of 7.24%. Cite this article: Bone Jt Open 2023;4(10):776–781

Aims. The aim of this study was to identify variables associated with time to revision, demographic details associated with revision indication, and type of prosthesis employed, and to describe the survival of hinge knee arthroplasty (HKA) when used for first-time knee revision surgery and factors that were associated with re-revision. Methods. Patient demographic details, BMI, American Society of Anesthesiologists (ASA) grade, indication for revision, surgical approach, surgeon grade, implant type (fixed and rotating), time of revision from primary implantation, and re-revision if undertaken were obtained from the National Joint Registry data for England, Wales, Northern Ireland, and the Isle of Man over an 18-year period (2003 to 2021). Results. There were 3,855 patient episodes analyzed with a median age of 73 years (interquartile range (IQR) 66 to 80), and the majority were female (n = 2,480, 64.3%). The median time to revision from primary knee arthroplasty was 1,219 days (IQR 579 to 2,422). Younger age (p < 0.001), decreasing ASA grade (p < 0.001), and indications for revision of sepsis (p < 0.001), unexplained pain (p < 0.001), non-polyethylene wear (p < 0.001), and malalignment (p < 0.001) were all associated with an earlier time to revision from primary implantation. The median follow-up was 4.56 years (range 0.00 to 17.52), during which there were 410 re-revisions. The overall unadjusted probability of re-revision for all revision HKAs at one, five, and ten years after surgery were 2.7% (95% confidence interval (CI) 2.2 to 3.3), 10.7% (95% CI 9.6 to 11.9), and 16.2% (95% CI 14.5 to 17.9), respectively. Male sex (p < 0.001), younger age (p < 0.001), revision for septic indications (p < 0.001) or implant fracture (p = 0.010), a fixed hinge (p < 0.001), or surgery performed by a non-consultant grade (p = 0.023) were independently associated with an increased risk of re-revision. Conclusion. There were several factors associated with time to first revision. The re-revision rate was 16.2% at ten years; however, the risk factors associated with an increased risk of re-revision could be used to counsel patients regarding their outcome. Cite this article: Bone Joint J 2023;105-B(1):47–55

Introduction: Design of the prosthesis is an important factor in the successful outcome and longevity of total hip replacement. The purpose of the present study is to evaluate the minimum six-year results of primary total hip replacement using LX cemented prosthesis. Methods: We prospectively studied 177 patients (60 male and 117 female) who underwent 197 hip replacements, between 1996 and 1999, using LX cemented prosthesis comprising a femoral component with cylindrical cross section of the stem and an acetabular component of ultrahigh molecular weight polyethylene. The average follow up was 7.3 years (6.1–9.6years). Clinical (Harris Hip Score) and radiological assessments (Barrack’s grading of cementation, subsidence, debonding, radiolucent lines and osteolysis) were performed. Results: The average Harris Hip Score is 85.53 (28–99) compared to the preoperative score of 59.28. 28 cases (14.2%) developed progressive radiolucent lines around the stem. Sinking and debonding of the stem was noted in 18 cases (9.1%). 15 hips (7.6%) have dislocated and 11 were recurrent dislocations. Revision hip replacement was carried out in 12 cases (6%) for subsidence and debonding of stem, cement fracture and recurrent dislocation. The femoral stem components were found to be loose at the time of surgery. Discussion: We believe that design of the prosthesis is an important factor in the high incidence of subsidence and debonding of the femoral stem. Both the geometry (cylindrical shape) and the rough surface finish (Ra value 100 microinches) were responsible for the pattern of progressive loosening. Lack of progressive increase in the offset with increase in the size of femoral component from 1 to 2 is one of the factors which contributed to high incidence of dislocation

Purpose of the study: This retrospective analysis compared surgical treatments of femoral neck fractures in patients aged over 80 years. Material and methods: Two hundred femoral neck fractures (Garden 3 and 4) were treated in three different manners: total prosthesis with a retaining cup (74 patients), intermediary prosthesis (58 patients), and osteosynthesis (68 patients). Indications were the same, but the periods of treatment were successive. Study variables were: mortality, number of revisions, duration of hospital stay, discharge to home or rehabilitation center, cost per hospital day. Follow-up was at least two years. The chi-square test was applied with p< 0.05. Results: Mortality was similar for the three groups: eight deaths during stay in orthopedic unit (4%), three after total prosthesis (4%), three after osteosynthesis (5%) and two after intermediary prosthesis (3%). The difference was nonsignificant (p=0.24). Among the total prostheses, five dislocations (6.7%) required anesthesia despite the retaining cup. The rate of dislocation was 12% for intermediary prostheses and to avoid recurrence four revisions were needed to totalize an intermediary prosthesis with a retaining cup. Among the osteosynthesis cases, the rate of revision was 25%; transformation to a total prosthesis was necessary for 17% and material removal with resection of the head and neck was necessary in 8%. One total prosthesis and one intermediary prosthesis had to be removed because of infection. Resection of the head and neck for infection also occurred in one patient with an intermediary prosthesis. The rate of revision for an orthopedic problem was significantly less (p< 0.01) in the total prosthesis group. At last follow-up, or before death, patients with a total prosthesis were more independent and returned to their home significantly more often than patients treated with osteosynthesis. The economic cost of these interventions were not significantly different, the cost of the implant being insignificant compared with the cost of hospitalization and reeducation of this very elderly population. Discussion: Total hip arthroplasty is a recognized treatment for painful degenerative hip disease. Historically, the total prosthesis was not considered as a first-intention treatment for fractures of the femoral neck in elderly subjects due to the risk of intraoperative blood loss, the risk of infection, and the risk of dislocation if a hip stabilization mechanism was not applied. This study demonstrated that, in light of the complications observed with the other methods, progress in anesthesia and use of implants avoiding dislocation can be proposed as first-intention treatment for total prosthesis patients who suffer a fracture of the femoral neck

Introduction. Post-meniscectomy syndrome is broadly characterised by intractable pain following the partial or total removal of a meniscus. There is a large treatment gap between the first knee pain after meniscectomy and the eligibility for a TKA. Hence, there is a strong unmet need for a solution that will relieve this post-meniscectomy pain. Goal of this first-in-man study was to evaluate the safety and performance of an anatomically shaped artificial medial meniscus prosthesis and the accompanying surgical technique. Methods. A first-in-man, prospective, multi-centre, single arm clinical investigation was intended to be performed on 18 post-medial meniscectomy syndrome patients with limited underlying cartilage damage (Kellgren Lawrence scale 0–3) in the medial compartment and having a normal lateral compartment. Eventually 5 patients received a polycarbonate urethane mediale meniscus prosthesis (Trammpolin® medial meniscus prosthesis; ATRO Medical B.V., the Netherlands) which was clicked onto two titanium screws fixated at the native horn attachments on the tibia. PROMs were collected at baseline and at 6 weeks, 3, 6, 12 and 24 months following the intervention including X-rays at 6, 12 and 24 Months. MRI scans were repeated after 12 and 24 months. Results. The surgical technique to select the appropriately sized implant and correct positioning of the fixation screws and meniscus prosthesis onto the tibia was demonstrated feasible and reproducible. The surgeries showed that in particular the positioning of the posterior screw is crucial for correct positioning of the prosthesis. Inclusion stopped after 5 patients, who reached the 6 months evaluation. The PROMs did not improve in the first 6 months after surgery. All patients reported knee joint stiffness and slight effusion in their knee at 6 months follow-up. In case of symptomatic patients an evaluation of the device position and integrity was performed by MRI. In three patients the implants were removed because of implant failure and in one patient the implant was removed because of persistent pain and extension deficit. At present one patient has the implant still in situ. The explantations of the implants demonstrated no articular cartilage damage and the fixation screws were securely anchored. Discussion. This is the first clinical study with an artificial meniscus-like prosthesis. Except one, all implants were removed due to implant breakage or discomfort of the patient. Analysis of the torn implants showed fatigue failure resulting from the lack of loadsharing between implant and cartilage: the implant was too stiff and carried all the load in the medial compartment of the knee. Furthermore, the fixation with screws seemed too rigid which restricted the motion of the posterior horn. Based on previous in vitro and animal experiments, we expected more creep of the material and more motion on the screw fixation. Conclusion. This first-in-man clinical study demonstrates that the investigated device design is not safe and did not perform as expected. Therefore, modification of the meniscus prosthesis design and fixation technique is required to allow for more motion of the meniscus prosthesis during knee joint movement

Aims. The Mathys Affinis Short is the most frequently used stemless total shoulder prosthesis in the UK. The purpose of this prospective cohort study is to report the survivorship, clinical, and radiological outcomes of the first independent series of the Affinis Short prosthesis. Methods. From January 2011 to January 2019, a total of 141 Affinis Short prostheses were implanted in 127 patients by a single surgeon. Mean age at time of surgery was 68 (44 to 89). Minimum one year and maximum eight year follow-up (mean 3.7 years) was analyzed using the Oxford Shoulder Score (OSS) at latest follow-up. Kaplan-Meier survivorship analysis was performed with implant revision as the endpoint. Most recently performed radiographs were reviewed for component radiolucent lines (RLLs) and proximal humeral migration. Results. Five shoulders underwent revision surgery (3.5%); three for rotator cuff failure, one for infection, and one for component malposition. Survivorship of the implant was 95.4% (95% confidence interval 90.1% to 97.9%) at five and nine years. Mean OSS improved significantly compared to preoperative values from 19.0 (1 to 35) to 43.3 (7 to 48) (p < 0.001). Radiological analysis was undertaken for 99 shoulders. This revealed humeral RLLs in one case (1%), glenoid RLLs in 15 cases (15.2%), and radiological rotator cuff failure in 22 cases (22.2%). Conclusion. This prospective cohort study shows encouraging short- to mid-term survivorship and clinical and radiological results for the Mathys Affinis Short, Short Stem Total Shoulder Prosthesis. Level of Evidence: IV. Cite this article: Bone Jt Open 2021;2(1):58–65

Background. The literature on the outcome of revision total ankle arthroplasty (TAA) remains limited. We aim to report the clinical and radiological outcomes of revision TAA at a high-volume centre in the UK. Methods. Retrospective review of 28 patients that underwent 29 revision TAA procedures using INBONE II prosthesis. Demographic, radiological, and patient reported outcome measures data were analysed. Results. The mean (range) duration from primary TAA to revision was 87.5 (16–223) months. The main indication for the revision was aseptic loosening of the primary TAA (82.8%). Additional procedures were required in 75.9% of patients. At mean (range) follow-up of 40 (24- 60) months, the infection, re-operation, and implant survival rates were 6.9%, 6.9% and 96.5% respectively. A significant postoperative improvement in the component alignment radiographic measures was observed. Osteolysis, subsidence, loosening and heterotopic ossification rates were comparable to other reports and did not influence the clinical outcome. A significant improvement was observed in the MOXFQ (all domains) and the EQ-5D (three domains) at 24 months postoperatively. Conclusions. Revision TAA using INBONE II was associated with good short-term survival and improvement in the postoperative scores at 2 years. Maintenance of the postoperatively improved alignment was documented at follow up. The relatively high survival rate in this series supports the notion that revision TAA is a satisfactory option for failed primary TAA

A common location for radius fracture is the proximal radial head. With the arm in neutral position, the fracture usually happens in the anterolateral quadrant (Lacheta et al., 2019). If traditional surgeries are not enough to induce bone stabilization and vascularization, or the fracture can be defined grade III or grade IV (Mason classification), a radial head prosthesis can be the optimal compromise between bone saving and recovering the “terrible triad”. A commercially available design of radial head prosthesis such as Antea (Adler Ortho, Milan, Italy) is characterized by flexibility in selecting the best matching size for patients and induced osteointegration thanks to the Ti-Por. ®. radial stem realized by 3D printing with laser technique (Figure 1). As demonstrated, Ti-Por. ®. push-out resistance increased 45% between 8 −12 weeks after implantation, hence confirming the ideal bone-osteointegration. Additional features of Antea are: bipolarity, modularity, TiN coating, radiolucency, hypoallergenic, 10° self-aligning. The osteointegration is of paramount importance for radius, in fact the literature is unfortunately reporting several clinical cases for which the fracture of the prosthesis happened after bone-resorption. Even if related to an uncommon activity, the combination of mechanical resistance provided by the prosthesis and the stabilization due to the osteointegration should cover also accidental movements. Based upon Lacheta et al. (2019), after axial compression-load until radii failure, all native specimens survived a compression-load of 500N, while the failure happened for a mean compression force of 2560N. The aim of this research study was to test the mechanical resistance of a radial head prosthesis obtained by 3D printing. In detail, a finite element analysis (FEA) was used to understand the mechanical resistance of the core of the prosthesis and the potential bone fracture induced in the radius with simulated bone- resorption (Figure 2a). The critical level was estimated at the height for which the thickness of the core is the minimum (Figure 2b). Considered boundary conditions:. - Full-length prosthesis plus radius out of the cement block equal to 60mm (Figure 2a);. - Bone inside the cement equal to 60mm (Figure 2b);. - Load inclined 10° epiphysiary component (Figure 2c);. - Radius with physiological or osteoporotic bone conditions;. - Load (concentrated in the sphere simulating full transmission from the articulation) of 500N or 1300N or 2560N. Figure 3 shows the results in terms of maximum stress on the core of the prosthesis and the risk of fracture (Schileo et al., 2008). According to the obtained results, the radial head prosthesis shows promising mechanical resistance despite of the simulated bone-resorption for all applied loads except for 2560N. The estimated mechanical limit for the material in use is 200MPa. The risk of fracture is in agreement with the experimental findings (Lacheta et al. (2019)), in fact bone starts to fail for the minimum reported failure load, but only for osteoporotic conditions. The presented FEA aimed at investigating the behavior of a femoral head prostheses made by 3D printing with simulated bone-resorption. The prosthesis shows to be a skilled solution even during accidental loads. For any figures or tables, please contact the authors directly

Constrained implants with intra-medullary fixation are expedient for complex TKA. Constraint is associated with loosening, but can correction of deformity mitigate risk of loosening?. Primary TKA's with a non-linked constrained prosthesis from 2010-2018 were identified. Indications were ligamentous instability or intra-medullary fixation to bypass stress risers. All included fully cemented 30mm stem extensions on tibia and femur. If soft tissue stability was achieved, a posterior stabilized (PS) tibial insert was selected. Pre and post TKA full length radiographs showed. i. hip-knee-ankle angles (HKAA). ii. Kennedy Zone (KZ) where hip to ankle vector crosses knee joint. 77 TKA's in 68 patients, average age 69.3 years (41-89.5) with OA (65%) post-trauma (24.5%) and inflammatory arthropathy (10.5%). Pre-op radiographs (62 knees) showed varus in 37.0%. (HKAA: 4. o. -29. o. ), valgus in 59.6% (HKAA range 8. o. -41. o. ) and 2 knees in neutral. 13 cases deceased within 2 years were excluded. Six with 2 year follow up pending have not been revised. Mean follow-up is 6.1 yrs (2.4-11.9yrs). Long post-op radiographs showed 34 (57.6%) in central KZ (HKKA 180. o. +/- 2. o. ). . Thirteen (22.0%) were in mechanical varus (HKAA 3. o. -15. o. ) and 12 (20.3%) in mechanical valgus: HKAA (171. o. -178. o. ). Three failed with infection; 2 after ORIF and one with BMI>50. The greatest post op varus suffered peri-prosthetic fracture. There was no aseptic loosening or instability. Only full-length radiographs accurately measure alignment and very few similar studies exist. No cases failed by loosening or instability, but PPF followed persistent malalignment. Infection complicated prior ORIF and elevated BMI. This does not endorse indiscriminate use of mechanically constrained knee prostheses. Lower demand patients with complex arthropathy, especially severe deformity, benefit from fully cemented, non-linked constrained prostheses, with intra-medullary fixation. Hinges are not necessarily indicated, and rotational constraint does not lead to loosening

Prosthetic joint infections represent complications connected to the implantation of biomedical devices, they have high incidence, interfere with osseointegration, and lead to a high societal burden. The microbial biofilm, which is a complex structure of microbial cells firmly attached to a surface, is one of the main issues causing infections. Biofilm- forming bacteria are acquiring more and more resistances to common clinical treatments due to the abuse of antibiotics administration. Therefore, there is increasing need to develop alternative methods exerting antibacterial activities against multidrug-resistant biofilm-forming bacteria. In this context, metal-based coatings with antimicrobial activities have been investigated and are currently used in the clinical practice. However, traditional coatings exhibit some drawbacks related to the insufficient adhesion to the substrate, scarce uniformity and scarce control over the toxic metal release reducing their efficacy. Here, we propose the use of antimicrobial silver-based nanostructured thin films to discourage bacterial infections. Coatings are obtained by Ionized Jet Deposition, a plasma-assisted technique that permits to manufacture films of submicrometric thickness having a nanostructured surface texture, allow tuning silver release, and avoid delamination. To mitigate interference with osseointegration, here silver composites with bone apatite and hydroxyapatite were explored. The antibacterial efficacy of silver films was tested in vitro against gram- positive and gram-negative species to determine the optimal coatings characteristics by assessing reduction of bacterial viability, adhesion to substrate, and biofilm formation. Efficacy was tested in an in vivo rabbit model, using a multidrug-resistant strain of Staphylococcus aureus showing significant reduction of the bacterial load on the silver prosthesis both when coated with the metal only (>99% reduction) and when in combination with bone apatite (>86% reduction). These studies indicate that IJD films are highly tunable and can be a promising route to overcome the main challenges in orthopedic prostheses

Aim. Due to medical and organizational factors, it occurs in everyday practice that spacers are left in place longer than originally planned during a two-stage prosthesis exchange in the case of prosthetic joint infections. Patients are severely restricted in their mobility and, after initial antibiotic administration, the spacer itself only acts as a foreign body. The aim of this study is to analyze whether the duration of the spacer in situ has an influence on the long-term success of treatment and mortality. Method. We retrospectively studied all 204 two-stage prosthesis replacements of the hip and knee from 2012 to 2016 with a minimum follow-up of two years at an arthroplasty center with 3 main surgeons. The duration of the spacer interval was divided into two groups. Patients replanted within ten weeks (as is standard in multiple algorithms) after systemic antibiotic treatment were assigned to the ‘Regular Spacer Interval (< 70 days)’ group. If the spacer interval was longer, they were assigned to the ‘Long Spacer Interval (≥ 70 days)’ group. Results. Patients were on average 67.69 years old (SD 12.3). The mean duration of the spacer-interval was 100.9 days (range: 423.0; SD, 60.0). In 62 patients reimplantation could be performed within 70 days after explantation, in 142 patients this took longer (max. 438 days). In 26 patients, the spacer had to be changed at least once during this period (11 patients in the hip group, and 15 patients in the knee group). In the remaining cases, other medical or organizational reasons delayed replantation. Both groups were comparable concerning Charlson Comorbity Index, age, number of previous surgeries and laboratory infection markers. There was no statistically significant influence of the duration of the spacer interval on the infection free survival (n=204, p=0.32). There was also no influence on mortality (n=204, p=0.35) and aseptic implant failure (n=204, p=0.15). Conclusions. The timely replantation of a knee or hip prosthesis seems to be reasonable in general because the patients are strongly limited in their mobility and daily activities by the spacer. However, there does not seem to be a negative influence on infection eradication and survival due to a long spacer interval

The place of the myo-electric prosthesis in below-elbow amputees has been reviewed. Forty-three patients were seen and all possessed both a myo-electric prosthesis and a standard artificial limb. Nearly half the patients used the newer device almost all the time at work and many of these wore it for the majority of their waking hours. Its use at work was mainly related to the patient's type of job and here in turn there was concern about damaging the device. It is suggested that acceptance would be further increased if greater attention were paid to the durability of the arm and its glove. Criteria for prescription and future developments are discussed

Purpose: A spacer can be used for two-phase replacement of an infected total hip prosthesis. The goal is to facilitate reimplantation by avoiding soft tissue retraction. Several types of spacers can be used. We searched for a spacer which avoids wear debris due to methacrylate friction against bone, delivers a local antibiotic, is easily removed, and does not worsen bone damage. Since 1995, we have used a Charnley Kerboull type prosthesis as a spacer. The purpose of the present study was to 1) verify the absence of spacer-related complications, 2) assess outcome in terms of cure of infection and improved function. Material and methods: We used 14 articulated spacers for two-phasee prosthesis replacement in nine men and five women, mean age 64 years. Erythrocyte sedimentation rate was 32 and C-reactive protein was 17. The mean Postel-Merle d’Aubigné (PMA) score was 3+5+2. All patients were reviewed at a minimum 37 months follow-up. Technique: The approach was generally a digastric trochanterotomy, associated with a more or less extensive femoral procedure (depending on the length of the plug to remove) to achieve removal of all implants and cement. A small-size polyethylene cup was inserted with cement delivering at least one antibiotic on a Surgicel bed to facilitate later extraction. A long small-diameter femoral stem was then inserted (bridging the femoral window) and blocked with cement, also on a Surgicel bed. Partial then total weight bearing was authorised between the phases. Results: There were no dislocations. All patients achieved total weight bearing between the two phases. The same germ identified at the first operation was also identified at the second in two patients, requiring prolonged antibiotic therapy. There was one septic failure, in a different patient. The mean PMA score was 5.7+5.8+5.2. Conclusion: This technique avoids methacrylate wear induced by classical spacers and does not modify polymorphonuclear chemotactism, facilitating the efficacy of medical treatment. Patient comfort is also improved between the two phases and muscle atrophy, which could compromise long-term function, is avoided

Previous scientific studies have highlighted how coupling is an important element affecting total hip arthroplasty's survival. This study aims to evaluate whether metal-on-metal (MOM) coupling could be a statistically significant risk factor. The data from the regional joint registry (Registro dell'Impiantologia Protesica Ortopedica, RIPO) was used for analysis. The data collection accuracy of this registry was 97.2% in 2017. We retrospective evaluate all MOM total hip arthroplasties (THAs) implanted in our department between January 01st 2000 and December 31st 2011. We used a control group composed by all other prosthesis implanted in our Department in the same time lapse. We registered 660 MOM THAs. Mean age of patients was 66.9 years. 603 patients have a >36mm head, while 78 a <36 mm one. Neck modularity was present in half of patients. 676 implants were cementless. We registered 69 revisions, especially due to aseptic mobilization (16 THAs), implant breakage (9 THAs) and periprosthetic fracture (6 THAs). The MOM THAs overall Kaplan-Meier survival rate was 87.2 at 15 years, and the difference between MOM THAs and other implants two curves is statistically significant (p<0.05). Male sex is a significant risk factors. Further evaluations are in progress to establish the presence of any additional risk factors. We think weight and/or BMI may be included in this category. Our study confirms the data currently present in the literature regarding a lower survival of metal-on-metal hip prostheses. The male sex is a statistically significant risk factor (p<0.05), while age, head size and modularity of the prosthetic neck are not statistically significant (p>0.05). Any new finds will be presented at the congress venue

Coronoid fractures account for 2 to 15% of the cases with elbow dislocations and usually occur as part of complex injuries. Comminuted fractures and non-unions necessitate coronoid fixation, reconstruction or replacement. The aim of this biomechanical study was to compare the axial stability achieved via an individualized 3D printed prosthesis with curved cemented intramedullary stem to both radial head grafted reconstruction and coronoid fixation with 2 screws. It was hypothesized that the prosthetic replacement will provide superior stability over the grafted reconstruction and screw fixation. Following CT scanning, 18 human cadaveric proximal ulnas were osteotomized at 40% of the coronoid height and randomized to 3 groups (n = 6). The specimens in Group 1 were treated with an individually designed 3D printed stainless steel coronoid prosthesis with curved cemented intramedullary stem, individually designed based on the contralateral coronoid scan. The ulnas in Group 2 were reconstructed with an ipsilateral radial head autograft fixed with two anteroposterior screws, whereas the osteotomized coronoids in Group 3 were fixed in situ with two anteroposterior screws. All specimens were biomechanically tested under ramped quasi-static axial loading to failure at a rate of 10 mm/min. Construct stiffness and failure load were calculated. Statistical analysis was performed at a level of significance set at 0.05. Prosthetic treatment (Group 1) resulted in significantly higher stiffness and failure load compared to both radial head autograft reconstruction (Group 2) and coronoid screw fixation, p ≤ 0.002. Stiffness and failure load did not reveal any significant differences between Group 2 and Group 3, p ≥ 0.846. In cases of coronoid deficiency, replacement of the coronoid process with an anatomically shaped individually designed 3D printed prosthesis with a curved cemented intramedullary stem seems to be an effective method to restore the buttress function of the coronoid under axial loading. This method provides superior stability over both radial head graft reconstruction and coronoid screw fixation, while achieving anatomical articular congruity. Therefore, better load distribution with less stress at the bone-implant interface can be anticipated. In the clinical practice, implementation of this prosthesis type could allow for early patient mobilization with better short- and long-term treatment outcomes and may be beneficial for patients with irreparable comminuted coronoid fractures, severe arthritic changes or non-unions

Revision total hip arthroplasty (rTHA) in the presence of femoral defects can be technically challenging. Reconstruction with long stems is widely accepted as the standard. However long stems can be difficult to insert and can compromise distal bone stock for future revisions. The aims of this study were to identify whether there was a difference in survival and outcomes following rTHA using a long versus standard or short femoral stem. A comprehensive systematic review was performed according to PRISMA guidelines using the MEDLINE, EMBASE, Chochrane Library and Web of Science databases. Inclusion criteria were (i) adult patients >18 years; (ii) randomised controlled trials, joint registry, or cohort studies; (iii) single or staged rTHA for Paprosky 1–3B femoral defects. Exclusion criteria were (i) mixed reporting without subgroup analysis for revision stem length; (ii) ex-vivo studies. Screening for eligibility and assessment of studies was performed by the authors. Out of 341 records, 9 studies met criteria for analysis (including 1 study utilising joint registry data and 1 randomised controlled trial). Across studies there were 3102 rTHAs performed in 2982 patients with a mean age of 67.4 years and a male: female ratio of 0.93. Revision prostheses were long-stemmed in 1727 cases and short or standard in 1375 cases with a mean follow up of 5 years (range, 0-15 years). On subgroup analysis the use of a long cemented stem compared to a long cementless prosthesis was associated with fewer complications and periprosthetic fracture in older patients. Survivorship was 95% with short stems compared to 84% with long stems at 5 years. Moderate quality evidence suggests that in rTHA with Paprosky type 1-3B femoral defects, the use of a short or standard stem can achieve comparable outcomes to long stems with fewer significant complications and revisions. Using a shorter stem may yield a more straightforward surgical technique and can preserve distal bone stock for future revision

Aims

The aim of this study was to compare the biomechanical models of two frequently used techniques for reconstructing severe acetabular defects with pelvic discontinuity in revision total hip arthroplasty (THA) – the Trabecular Metal Acetabular Revision System (TMARS) and custom triflange acetabular components (CTACs) – using virtual modelling.

The management of femoral bone loss is challenging during revision hip arthroplasty. In patients with Paprosky grade IIIB and IV defects, obtaining fixation and rotational stability using traditional surgical constructs is difficult. The use of a custom-made internal proximal femoral replacement prostheses has been proposed as a solution in patients, with severe femoral bone stock loss. However, there is a paucity in the literature on their use and long-term outcomes. We report on the clinical and radiological results of our cohort. We retrospectively reviewed all patients who underwent internal proximal femoral replacement for revision hip arthroplasty between April 1996 and April 2019. All patients had at least 2 years of follow-up time. 160 patients underwent limb salvage at our institution using internal proximal femoral replacement. The mean follow-up was 79.7 months (S.D 41.3). Indications for revision included periprosthetic fractures, aseptic loosening, and deep infection. The mean Oxford hip score increased from 13.8 (0–22) to 31.5 (18–43) (paired t-test, p < 0.001). Kaplan-Meier prosthesis survival analysis with revision as the endpoint was 87% at 5 years. None required revision of the femoral stem. There were four dislocations (5%) and there was failure to eradicate the deep infection in four. This technique allows instant distal fixation, allowing for early mobilisation. Long-term clinical and radiological outcomes are encouraging and the complication rates are acceptable for this patient group

Purpose

The purpose of this study was to elucidate kinematic change according to the implant's specific femoral rotation by using orthosensor (Verasense) implant with three degrees external rotation of femoral rotation rebuilt (Genesis-II) and traditional TKA implant without rebuilt of the femoral rotation (Anthem).

Purpose: The purpose of this work was to evaluate the quality of cemented humeral stem fixation. We analysed the incidence and influence of humeral lucent lines and loosening after implantation of a shoulder prosthesis as a function of aetiology (fracture versus scapular osteoarthritis) and glenoid status (total versus partial humeral prosthesis). Material and methods: This retrospective series included 1842 first-intention shoulder prostheses reviewed at mean five years (2–10). We selected patients whose initial diagnosis was fracture of the superior portion of the humerus (n=300) and centred osteoarthritis (n=767). All stems implanted for fracture were cemented. For osteoarthritis, there were 610 total prostheses and 157 simple humeral prostheses: 752 stems were cemented and 15 were implanted without cement. The Constant score and radiographic results (AP and lateral view at least) were noted. Results: For cemented stems, the incidence of radiographic lucent lines and loosening was significantly higher in fractures (40% and 10% respectively) than in centred osteoarthritis (14% and 1%). Lucency and loosening did not influence functional outcome in patients with centred osteoarthritis but had a significantly negative effect on final outcome in fractures. For fractures, the incidence of lucent lines was correlated with migration of the tubercles. For osteoarthritis, there was no difference between total and partial prostheses in terms of loosening, but the functional outcome was significantly better with total prostheses. Conclusion: Fixation of the humeral implant with cement remains the gold standard for shoulder prostheses implanted for centred osteoarthritis. However, cement fixation yields disappointing results for fractures: defective fixation of the humeral stem is correlated with migration of the tubercles. For osteoarthritis, there are not more lucent lines with a total prosthesis which provides the better functional results

Aim. A significant number of patients undergoing shoulder arthroplasty surgery have C acnes contamination at the end of the primary surgery. The objective of this study is to determine whether patients with C acnes contamination at the end of their primary shoulder surgery have a worse prognosis than those who end up without C. acnes contamination. Method. Prospective study including all patients who underwent a reverse shoulder prosthesis from January 2015 to December 2018. In all of them, 5 to 12 cultures were performed during primary surgery. The patients underwent surgery for shoulder arthritis secondary to rotator cuff tears, acute fracture of the proximal humerus, and sequelae of fracture of the proximal humerus. Exclusion criteria included the existence of previous surgeries on the affected shoulder, the presence of signs of infection, having received infiltrations and / or complementary invasive examinations (Arthro-MRI and Arthro-CT). Follow-up from 2 to 5 years. Functional assessment according to the Constant Functional Scale. All complications were also recorded. Results. 162 patients were included. Of these, 25 had positive cultures for C. acnes at the end of primary shoulder surgery. Average age of 74.8 years. 136 women and 26 men. 75.9% Shoulder arthritis secondary to rotator cuff tears, 13.6% acute fractures and 10.5% sequelae of fractures. There were no differences between patients with C. acnes and those without C. acnes regarding age and indication for surgery. Predominance of men in the group with positive C. acnes (p <0.001). No differences at 2 and 5 years in the Constant functional scale between the two groups (2 years, 59.6 vs 59.2 p 0.870) (5 years, 62.4 vs 59.5 p 0.360). Significant differences regarding the number of complications (p 0.001). Patients without C. acnes had 1 aseptic loosening of the metaglene and patients with C. acnes had 2 infections, 1 dislocation, and 1 revision surgery. Patients with contamination by C. acnes had more comorbidities (p 0.035) than patients without contamination. Conclusions. Patients with C acnes contamination at the end of primary surgery do not have functional differences when compared with patients without contamination at 2 and 5 years, but they have a higher number of complications in the medium term

Introduction. Studies have shown that increased implant conformity in total knee arthroplasty (TKA) has been linked to increased constraint and thus rotational torque at the bone/implant interface. Anterior stabilized (AS) tibial inserts were designed to compensate for excessive AP motion in less-conforming cruciate-retaining (CR) tibial inserts. However, increased constraint may affect implant loading. Therefore, the purpose of this study is to model rotational prosthesis constraint based on implant-specific data and to compare rotational torque and 3D contact forces in implants with CR-lipped and AS tibial inserts during normal gait. Methods. A previously reported knee joint contact model was updated to include rotational torque due to prosthesis constraint (ASTM F1223(14)). Piecewise multiple linear regression with manually selected cutoff points was used to determine estimates of AP force, ML force, and rotation torque as functions of AP displacement, ML displacement, knee external rotation, respectively, and knee flexion angle from standard data. These functions were used to estimate total moment contribution of the prosthesis from measured knee displacement/rotation angles. Estimates were incorporated into the contact model equilibrium equations as needed by the model. As the model parametrically varies muscle activation coefficients to solve for the range of physiologically possible forces at each time point, the reported force/torque values are the mean across all solutions at each time point. Rotational torque and three dimensional contact forces were calculated for 14 informed-consented subjects, five with AS tibial inserts (1/4 m/f, 67±10 years, 29.2±4.4 BMI, 1/4 right/left) and nine with CR-lipped TKRs (2/7 m/f, 64±6 years, 30.6±5.8 BMI, 4/5 right/left). Rotational torque waveforms were compared using statistical nonparametric mapping; 3D contact forces were compared at mean timing of the flexion/extension moment peaks using independent samples t-tests. Results. Waveform analysis of rotational torque found no significant differences between implant types. CR- lipped inserts showed an initial peak internal rotation torque during weight acceptance and continued with a pattern of internal rotation throughout stance. Peak torque for AS inserts also occurred during weight acceptance, but it varied between internal/external rotation torque. Additionally, after weight acceptance, AS subjects showed a pattern of external rotation torque. Mean axial force, medial-lateral shear force, and anterior-posterior shear force waveforms were similarly shaped between implant groups. Flexion and extension moment peaks occurred at 23% and 74% stance on average. There were no significant differences in three-dimensional knee joint contact forces between groups at either time point. Discussion. There were different patterns of rotational torque between groups. Implants with lipped CR inserts tended to undergo internal rotation torques that peaked during weight acceptance. Torque seen in implants with AS inserts was also largest during weight acceptance, but greatly varied between internal and external rotation, before settling in a pattern of external rotation for the remainder of stance. This may be due to constraints added by AS insert geometry. In conclusion, a model of rotational torque due to implant constraints has been developed; increased implant constraint increased the external rotation torque experienced by the implant and may also affect shear forces at the implant surface. For any figures or tables, please contact authors directly

Purpose of the study: The purpose of this study was to compare mid-term results after total shoulder arthroplasty (TSA) versus simple humeral arthroplasty (SHA) for the treatment of primary centered osteoarthritic degeneration of the shoulder joint. Material and methods: The series included 41 Aequalis prostheses (27 TSA, 14 SHA) implanted by the same surgeon. TSA was performed in 21 women and six men, mean age 68.3 years (range 51–78). SHA was performed in nine women and five men, mean age 68.3 years (range 58–83). The glenoid cavity presented concentric wear (type A) in 70% and asymmetric wear (type B) in 30% of patients undergoing TSA. Type A wear was observed in 57% of the patients undergoing SHA and type B (or C) wear in 43% of them. Mean follow-up was 35 months (range 24–49) for TSA and 37 months (24–59) for SHA. The Constant score and the Neer classification were noted. The position of the implants and lucent lines was noted on plain x-rays. Results: For the TSA patients, the mean non-weighted Constant score was 82/100 points (gain of 48 points), anterior elevation was 151° (gain 54°), and active external rotation 44° (gain 29°). For the SHA patients, the mean non-weighted Constant score was 71/100 points (gain 41 points), active anterior elevation 135° (ain 46°), and active external rotation 43° (gain 28°). The Neer classification demonstrated excellent or satisfactory outcome for 93% of the TSA patients and 86% of the SHA patients. TSA was more effective than SHA for pain relief (p=0.045). Periglenoid lucent lines were observed for 63% of the TSA but with no loosening or complication for the glenoid component at last follow-up. Discussion: Compared with a simple humeral prosthesis, total shoulder arthroplasty was more effective for the treatment of primary centered osteoarthritis of the shoulder joint

Aim. Patellofemoral Arthroplasty (PFA) prosthesis with asymmetric trochlear component was introduced as an improvement from existing designs for surgical treatment of symptomatic isolated patellofemoral arthritis. The purpose of this study was to evaluate midterm results in patients who underwent PFA procedure using such prosthesis. Methods. Our study involved a continuous retrospective cohort of patients who underwent PFA using Journey PFJ with asymmetric trochlear component, performed between June 2007 and October 2018 at a non-designer centre. The Patient Reported Outcome Measures and patient satisfaction questionnaires were collected for final evaluation. Results. A total of 128 PFA performed on 96 patients were evaluated. All patients were under regular follow up, and no patient was lost to follow up. Eighteen patients underwent simultaneous bilateral procedures, and 14 patients underwent PFA of the contralateral knee later. Median age at the time of surgery was 59 years (interquartile range 53 – 66 years); the median follow up period was 6 years (interquartile range 2.5 – 7 years). The Oxford Knee Score showed improvement from a median of 18 to 37. There were statistically significant improvements in functional outcome scores. Beverland satisfaction questionnaire revealed that 22.1 % (19/86) were ‘Very happy’ and 39.5% (34/86) were ‘Happy’ following the procedure. Four knees were revised to Total Knee Arthroplasty for reasons not related to the implant. The cumulative survival estimated by the Kaplan-Meier method was 95.2% (95% confidence interval: 90.4%– 99.9%). Conclusion. This series of patients who underwent PFA with the asymmetric trochlear component has shown promising mid-term results with no implant related complications

Aims. The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) may improve quality of life for amputees by avoiding soft-tissue complications associated with socket prostheses and by improving sensory feedback and function. It relies on the formation of a seal between the soft tissues and the implant and currently has a flange with drilled holes to promote dermal attachment. Despite this, infection remains a significant risk. This study explored alternative strategies to enhance soft-tissue integration. Materials and Methods. The effect of ITAP pins with a fully porous titanium alloy flange with interconnected pores on soft-tissue integration was investigated. The flanges were coated with fibronectin-functionalised hydroxyapatite and silver coatings, which have been shown to have an antibacterial effect, while also promoting viable fibroblast growth in vitro. The ITAP pins were implanted along the length of ovine tibias, and histological assessment was undertaken four weeks post-operatively. Results. The porous titanium alloy flange reduced epithelial downgrowth and increased soft-tissue integration compared with the current drilled flange. The addition of coatings did not enhance these effects. Conclusion. These results indicate that a fully porous titanium alloy flange has the potential to increase the soft-tissue seal around ITAP and reduce susceptibility to infection compared with the current design. Cite this article: Bone Joint J 2017;99-B:393–400

The Thompson hemiarthroplasty is a common treatment option for acute neck of femur fractures in the elderly population. Our department noted a significant number of patients returning with thigh pain, radiographic loosening and femoral osteolysis following cemented implantation of the titanium alloy version of the Thompson hemiarthroplasty. We are not aware of any previous reports documenting complications specific to the titanium Thompson implant and a retrospective cohort study was therefore initiated following clinical governance approval.

366 titanium alloy Thompson prostheses were implanted for hip fracture treatment between 2017 and 2020. As of February 2023, 6 of these have been revised at our hospital. 5 were revised for symptomatic femoral osteolysis and 1 presented with an acute periprosthetic fracture. All revised cases were determined to be aseptic. 32 living patients were excluded from recall on compassionate grounds due to permanent nursing home residence. 47 living patients were identified of which 33 attended for xray. 28 deceased and/or nursing home resident patients who had pelvis x-rays in the previous 12 months were also included in the analysis. Including the 6 index hips already revised, a total of 61 hip xrays were analysed, of which 19 hips (31.1%) showed radiographic evidence of femoral osteolysis or loosening.

We conclude that there is a concerning incidence of femoral osteolysis and implant loosening associated with the titanium Thompson implant. We have discontinued use of the implant and reported our experience to the MHRA. We encourage other Scottish Health-Boards who use this implant to consider enhanced follow-up.

Total ankle replacement (TAR) is contraindicated in patients with significant talar collapse due to AVN and in these patients total talus body prosthesis has been proposed to restore ankle joint. To date, five studies have reported implantation of a custom-made talar body in patients with severely damaged talus, showing the limit of short-term damage of tibial and calcaneal thalamic joint surfaces. Four of this kind of implants have been performed. The first two realized with “traditional” technology CAD-CAM has been performed in active patients affected by “missing talus” and now presents a survival follow-up of 15 and 17 years. For the third patient affected by massive talus AVN we designed a 3D printed porous titanium custom talar body prosthesis fixed on the calcaneum and coupled with a TAR, first acquiring high-resolution 3D CT images of the contralateral healthy talus that was “mirroring” obtaining the volume of fractured talus in order to provide the optimal fit. Then the 3D printed implant was manufactured. The fourth concern a TAR septic mobilization with high bone loss of the talus. The “two-stage” reconstruction conducted with the implant of total tibio-talo-calcaneal prosthesis “custom made” built with the same technology 3D, entirely in titanium and using the “trabecular metal” technology for the calcaneous interface. Weightbearing has progressively allowed after 6 weeks. No complications were observed. All the implants are still in place with an overall joint mobility ranging from 40° to 60°. This treatment requires high demanding technical skills and experience with TAR and foot and ankle trauma. The 15 years survival of 2 total talar prosthesis coupled to a TAR manufactured by a CAD-CAM procedure encourages consider this 3D printed custom implant as a new alternative solution for massive AVN and traumatic missing talus in active patients

Aim. In surgeries on patients with advanced ligament instabilities or severe bone defects modern-generation of rotating hinged knee prostheses are one of the main options. The objective of our study is to evaluate the mid-term functional results and complications of several surgeries using this form of prosthesis. Material and Method. The rotating hinged knee prosthesis (RHKP) was applied to 208 knees of 204 patients in primary surgeries between September 2009 and December 2017, the minimum followup was 15 months (mean, 65 months; range, 15–115 months). Of the total number of female patients there were 152 (74.5%), men − 52 (25.5%). The average age of the patients was 64,6 years (from 32 to 85). The main indications for using RHKP were severe varus deformity with flexion contracture in 107 knees (51,4%), severe valgus deformity (from 20 to 50 degrees) in 54 knees (26,0 %), severe ligamentous deficiencies in 24 knees (11,5%) and ankylosis in the flexion position in 23 cases (11,1%). Patients were evaluated clinically (Knee Society score) and radiographically (positions of components, signs of loosening, bone loss). Results. The average Knee Society Knee Scores, and Knee Society Functional Scores were 27, and 18, respectively, before the surgery; and 86, and 77 in the final post-surgery follow-ups. In addition, the average range of motion increased from the pre-operative level of 46 to 104 degrees at the final evaluation. Four patients (2%) had various complications after the surgery : two patients had deep infection, in one case took place fracture of the hinge mechanism and in one - post-operative rupture of the patellar tendon. Conclusions. Primary knee arthroplasty using RKHP can be successful in cases with advanced ligament instability or severe bone defects. Modern-generation of the kinematic rotating-hinge total knee prostheses allow to achieve in difficult primary cases the same consistently good results as commonly used constructions in standard situations

Orthopaedic implants, such as femoral heads, sockets and stems, are manufactured with a high degree of smoothness and very low form error in order to function as low wear bearings. The surfaces are subject to both wear and damage during in vivo use. Articulating surfaces naturally wear during normal use. Aseptic loosening associated with osteolysis and release of wear particles is the main reason for revision of total hip arthroplasty (THA). Damage of femoral heads is well known to increase the wear rate at the articulating surface and is vulnerable to scratching during the maneuver of positioning the femoral component into the acetabulum component either in primary as in revision total hip arthroplasties. The findings emphasize the importance of achieving and maintaining good surface finish of the femoral head component. The author presents a very simple and “zero cost” method of preventing scratching of the femoral head of any kind of total hip prosthesis (ceramic on ceramic, ceramic on poly, metal on metal, metal on poly and even metal on ceramic) when the reduction of the femoral head prosthesis is done inside the new acetabular component with metal, ceramic liner or poly liner with metal back (where the scratching can also occur) as one of the final stages of the surgical procedure which can be crucial to the long survival of the hip prosthesis. A short one minute video on an e-poster will show how this can be done being an easy, reproducible, safe and reliable technique to prevent femoral head scratching

In 2011, approximately 1.6 million total hip arthroplasties (THAs) were conducted in 27 of the 34 member countries in the Organization for Economic Cooperation and Development (OECD) However, approximately 10–15% of patients still require revision surgery every year. Therefore, new technologies are required to increase the life-spam of the prosthesis from the current 10–15 years to at least 20–30 years. Our strategy focuses on surface modification of the bearing materials with a hydrophilic coating to improve their wear behaviour. These coatings are biocompatible, with high swelling capacity and antifouling properties, mimicking the properties of natural cartilage, i.e. wear resistance with permanent hydrated layer that prevents prosthesis damage. Clear beneficial advantages of this coating have been demonstrated in different conditions and different materials, such as UHMWPE, PEEK, CrCo, Stainless steel, ZTA and Alumina. Using routine tribological experiments, the wear for UHMWPE substrate was decreased by 75% against alumina, ZTA and stainless steel. For PEEK-CFR substrate coated, the amount of material lost against ZTA and CrCo was at least 40% lower. Further experiments on hip simulator adding abrasive particles (1-micron sized aluminium particles) during 3 million cycles, on a total of 6 million, showed a wear decreased of around 55% compared to uncoated UHMWPE and XLPE. In conclusion, CIDETEC‘s coating technology is versatile and can be adapted to protect and improve the tribological properties of different types of surfaces used for prosthesis, even in abrasive conditions

Aims. To explore the effect of different types of articulating antibiotic-loaded cement spacers in two-stage revision for chronic hip prosthetic joint infection (PJI). Methods. A retrospective cohort study was performed involving 36 chronic PJI patients treated with different types of articulating antibiotic-loaded cement spacers between January 2014 and December 2017. The incidence of complications and the therapeutic effects of different types of antibiotic-loaded articulating cement spacers were compared. Results. A total of 36 patients with chronic hip PJI were included. Of these, 13 patients were treated with spacers with Kirschner wires as an endoskeleton (group I), ten patients were treated with spacers with a cemented femoral prosthesis as an endoskeleton (group II), and 13 patients were treated with cemented femoral prostheses combined with polyethylene sockets as a spacer (group III). All patients were followed for 12 to 60 months, with a mean follow-up period of 26.44 months (SEM 14.09). Infection was controlled in 34 patients (94.44%), and there were no significant differences in the eradication rate among the three groups (p = 0.705), but the risk of complications related to the spacer in group III was significantly lower than that in groups I and II (p = 0.006). Conclusion. Articulating antibiotic-loaded cement spacers is effective in the treatment of chronic hip PJI, but we must pay attention to the occurrence of spacer fracture and dislocation, which can lead to poor joint function. The risk of spacer-related mechanical complications is low, and better joint function can be achieved when using cemented femoral prostheses combined with polyethylene sockets as spacers. Cite this article: Bone Joint Res 2020;9(8):484–492

Modulus femoral prosthesis is a modular cementless femoral system which consists of 5 degree tapered conical stem made of a titanium alloy with 8 fins of 1mm and modular neck. Modular neck enables to control any ideal stem anteversion as a surgeon prefers. This system is considered to be useful in severe hip deformity, for example developmental dysplasia of the hip (DDH). In this study, clinical and radiographic outcomes of the Modulus femoral prosthesis were evaluated at a mean of 3.6 (2–6) years postoperatively. We assessed the results of 193 primary total hip arthroplasty using a Modulus femoral prosthesis in 169 patients (15 males, 154 females) undergoing surgery between September 2007 and December 2011. The mean age at the time of surgery was 65.6 (31–86) years old. The diagnoses were osteoarthritis (OA) in 178 hips (including 167 hips of DDH), rapidly destructive coxopathy (RDC) in 6 hips, rheumatoid arthritis (RA) in 6 hips, osteonecrosis in 2 hips, and subchondral insufficiency fracture in one hip. Clinical outcomes were assessed using Japan Orthopedic Association (JOA) hip scores and complications. Radiographic assessments were including stem alignment, bone on-growth, cortical hypertrophy, stress shielding and stem subsidence. 43.8 points of the preoperative mean JOA score was significantly improved to 93.1 points postoperatively. In one case intraoperative femoral fracture was occurred. One dislocation had occurred and thigh pain was observed in one hip. No revision surgery was required. In 192 hips of 193 hips (99.5%), stem was implanted in neutral position (within ±2 degrees). Bone on-growth was observed in all cases (94.3% in zone 3; 73.1% in zone 5; 30.6% in zone 2; 22.3% in zone 6). Cortical hypertrophy was observed in 66 hips (34.2%) at zone 3 and 5. Reduction of bone density due to stress shielding was observed (1. st. degree was 58.5%; 2. nd. degree was 29.5%; 3. rd. degree was 11.9%; 4. th. degree was 0%). In 22 cases (11.4%), more than 2mm of stem subsidence was observed, however the subsidence was stopped within 6 months in all cases. Modulus femoral prosthesis showed good clinical results and radiographic findings up to 6 years postoperatively

Aims. The aim of this study was to compare the cost-effectiveness of treatment with an osseointegrated percutaneous (OI-) prosthesis and a socket-suspended (S-) prosthesis for patients with a transfemoral amputation. Patients and Methods. A Markov model was developed to estimate the medical costs and changes in quality-adjusted life-years (QALYs) attributable to treatment of unilateral transfemoral amputation over a projected period of 20 years from a healthcare perspective. Data were collected alongside a prospective clinical study of 51 patients followed for two years. Results. OI-prostheses had an incremental cost per QALY gained of €83 374 compared with S-prostheses. The clinical improvement seen with OI-prostheses was reflected in QALYs gained. Results were most sensitive to the utility value for both treatment arms. The impact of an annual decline in utility values of 1%, 2%, and 3%, for patients with S-prostheses resulted in a cost per QALY gained of €37 020, €24 662, and €18 952, respectively, over 20 years. Conclusion. From a healthcare perspective, treatment with an OI-prosthesis results in improved quality of life at a relatively high cost compared with that for S-prosthesis. When patients treated with S-prostheses had a decline in quality of life over time, the cost per QALY gained by OI-prosthesis treatment was considerably reduced. Cite this article: Bone Joint J 2018;100-B:527–34

Aims. Extendible endoprostheses have been available for more than 30 years and have become more sophisticated with time. The latest generation is ‘non-invasive’ and can be lengthened with an external magnetic force. Early results have shown a worryingly high rate of complications such as infection. This study investigates the incidence of complications and the need for further surgery in a cohort of patients with a non-invasive growing endoprosthesis. Patients and Methods. Between 2003 and June 2014, 50 children (51 prostheses) had a non-invasive growing prosthesis implanted for a primary bone sarcoma. The minimum follow-up was 24 months for those who survived. Their mean age was 10.4 years (6 to 14). The incidence of complications and further surgery was documented. Results. The mean follow-up was 64 months (20 to 145). The overall survivorship of the patients was 84% at three years and 70% at five years. Revision-free survival was 81.7% at three years and 61.6% at five years with competing risk analysis. Deep infection occurred in 19.6% of implants at a mean of 12.5 months (0 to 55). Other complications were a failure of the lengthening mechanism in five prostheses (9.8%) and breakage of the implant in two (3.9%). Overall, there were 53 additional operations (0 to 5 per patient). A total of seven patients (14%) underwent amputation, three for local recurrence and four for infection. Their mean limb length discrepancy was 4.3 mm (0 to 25) and mean Musculoskeletal Tumor Society Score functional score was 26.5 (18 to 30) at the final follow-up. Conclusions. When compared with previously published early results, this mid-term series has shown continued good functional outcomes and compensation for leg-length discrepancy. Infection is still the most common complication: post-operative wound healing problems, central line infection and proximal tibial location are the main risk factors. Cite this article: Bone Joint J 2016;98-B:1697–1703

Patients with transfemoral amputation (TFA) often experience problems related to the use of socket-suspended prostheses. The clinical development of osseointegrated percutaneous prostheses for patients with a TFA started in 1990, based on the long-term successful results of osseointegrated dental implants. Between1999 and 2007, 51 patients with 55 TFAs were consecutively enrolled in a prospective, single-centre non-randomised study and followed for two years. The indication for amputation was trauma in 33 patients (65%) and tumour in 12 (24%). A two-stage surgical procedure was used to introduce a percutaneous implant to which an external amputation prosthesis was attached. The assessment of outcome included the use of two self-report questionnaires, the Questionnaire for Persons with a Transfemoral Amputation (Q-TFA) and the Short-Form (SF)-36. The cumulative survival at two years’ follow-up was 92%. The Q-TFA showed improved prosthetic use, mobility, global situation and fewer problems (all p < 0.001). The physical function SF-36 scores were also improved (p < 0.001). Superficial infection was the most frequent complication, occurring 41 times in 28 patients (rate of infection 54.9%). Most were treated effectively with oral antibiotics. The implant was removed in four patients because of loosening (three aseptic, one infection). Osseointegrated percutaneous implants constitute a novel form of treatment for patients with TFA. The high cumulative survival rate at two years (92%) combined with enhanced prosthetic use and mobility, fewer problems and improved quality of life, supports the ‘revolutionary change’ that patients with TFA have reported following treatment with osseointegrated percutaneous prostheses. Cite this article: Bone Joint J 2014;96-B:106–13

We determined the short-term clinical outcome and migration within the bone of the humeral cementless component of the Instrumented Bone Preserving (IBP) total elbow replacement in a series of 16 patients. There were four men and 12 women with a mean age at operation of 63 years (40 to 81). Migration was calculated using radiostereometric analysis. There were no intra-operative complications and no revisions. At two-year follow-up, all patients showed a significant reduction in pain and functional improvement of the elbow (both p < 0.001). Although ten components (63%) showed movement or micromovement during the first six weeks, 14 (88%) were stable at one year post-operatively. Translation was primarily found in the proximal direction (median 0.3 mm (interquartile range (IQR) -0.09 to 0.8); the major rotational movement was an anterior tilt (median 0.7° (IQR 0.4° to 1.6°)). One malaligned component continued to migrate during the second year, and one component could not be followed beyond three months because migration had caused the markers to break off the prosthesis. This study shows promising early results for the cementless humeral component of the IBP total elbow replacement. All patients had a good clinical outcome, and most components stabilised within six months of the operation. . Cite this article: Bone Joint J 2014;96-B:229–36

Introduction. In rheumatoid patients the use of a long intramedullary stem in ipsilateral shoulder and elbow replacement carries the risk of humeral fracture of the small area of unviolated bone between the implants. Healing may be compromised. Because of this a short stemmed humeral head prosthesis was designed which rests on the bone surface after resection of the humeral head instead to be fixed in the shaft of the humerus. Since 1994 this prosthesis, specially designed for the rheumatoid patients has been in use in our clinic. The design rationale and the clinical results will be presented. Result. Since 1994 the short stemmed shoulder prosthesis has been inserted by the author in 54 shoulders. 8 Patients had osteoarthritis, 42 patients rheumatoid arthritis, 3 patients osteonecrosis and 1 patient a post-traumatic osteoarthritis. The average age was 65 years (range 32–83). In 19 shoulders a total shoulder arthroplasty was performed and the 36 shoulders a hemiarthroplasty. 32 Patients had a follow-up of more than 1 year and the average follow-up in this group is 2. 5 years (range 1-5. 5). All patients were scored clinically with the HSS score and the Constant score and radiographically before the operation, 1 year after the operation and after that at regular intervals. At follow-up pain decreased in all patients but more than 50% of the shoulders still had some mild or moderate pain during daily activities. Pre-operatively active forward flexion averaged 61°, external rotation 10° and abduction 50°. Postoperatively the active forward flexion increased to 75°, the external rotation to 19° and the abduction to 67°. The gain in ROM is similar to a group of patients operated in the same time period with another shoulder prosthesis. Discussion. The short stem shoulder prosthesis is a good alternative for a shoulder prosthesis with a long intra medullary stem. The clinical results with regards to pain reflief and gain in ROM are similar. The long term fixation of short sem humeral prosthesis remains good, without signs of radiolucency or migration. The advantage of a short stem prosthesis are:. easy technique to reconstruct the anatomical position of the humeral head. bone sparing. no stress shielding of the shaft. no surgical problems when a long stemmed elbow prosthesis is used. possibility for revision

Aims

The Exeter V40 cemented polished tapered stem system has demonstrated excellent long-term outcomes. This paper presents a systematic review of the existing literature and reports on a large case series comparing implant fractures between the Exeter V40 series; 125 mm and conventional length stem systems.

Extensive and severe bone loss of the femur may be a result of a failed total hip arthroplasty (THA) or total knee arthroplasty (TKA) with multiple revision surgeries which may be caused by factors such as infection, periprosthetic fracture or osteolysis. The aim of this study was to assess outcomes of using the “Push-Through Total Femoral Prosthesis” (PTTF) for revision of a total hip replacement with extreme bone loss.

Fourteen patients who had extensive bone defects of the femur due to failed THR's and were treated with PTTF between 2012 and 2020 were included in this study. Primary functional outcomes were assessed using Harris Hip Score (HHS), Toronto Extremity Salvage Score (TESS) and Musculoskeletal Tumor Society (MSTS) scores. Range of motion, complications, and ambulatory status were also recorded to assess secondary outcomes.

Two of 14 patients underwent surgery with PTTF for both knee and hip arthroplasty revision. The mean time between index surgery and PTTF was 15 years (3 to 32 yrs.). Acetabular components were revised in six of 14 patients. After a mean follow-up of 5.9 years, hip dislocations occurred in 3 patients. All dislocated hips were in patients with retained non-constrained acetabular bearings. Patient satisfaction was high (MSTS: 67%, HHS: 61.2%, TESS 64.6%) despite a high re-operation rate and minor postoperative problems.

PTTF is a unique alternative that may be considered for a failed THA revision procedure in patients with an extreme femoral bone defect. Patients are able to ambulate pain free relatively well. Routine usage of constrained liners should be considered to avoid hip dislocation which was our main problem following the procedure.

Introduction. This study reports outcomes of 35 revisions of a recalled metal-on-metal (MOM) monoblock prosthesis performed by a single surgeon. Methods. We prospectively collected data on all patients who underwent revision of a recalled metal-on-metal monoblock prosthesis between 2010 and 2015. Average follow-up was 2.5 years post-revision and 6.9 years post-primary procedure. We evaluated the cohort for age, BMI, gender, existence of medical comorbidities, and post-op complications. We compared pre and post-revision cup abduction angles, anteversion angles, combined angles, cup sizes, and Harris Hip Scores. Cobalt and chromium levels were followed throughout the study period for each patient. Results. Thirty-one patients underwent 35 revisions surgeries for pain, high metal ions, infection, aseptic loosening, failure of ingrowth, leg length discrepancy and/or pseudotumor. Two of these revisions were subsequently re-revised – one for continued pain and one for failure involving multiple dislocations, breakage of screws, and acetabular fracture. The survival rate for our revisions to date is 94.3%. Female patients comprised a majority of revisions (54%) despite comprising a minority (28%) of primary hip replacements using the studied prosthesis. Revised patients were an average of 51.8 years of age with a BMI of 31.07. Demographics are included on Table 1. There were five post-operative complications, including 2 infections, 2 dislocations, and one DVT. Cups were revised from a mean abduction angle of 47.5° in primary hips to 42.3° in revisions. Cups were revised from a mean of 53.4 to 57.8. Cobalt and chromium levels were followed in all patients and showed significant decrease after revision (Graph 1). Cobalt levels decreased from an average of 33.7 to 13.1 ng/mL while Chromium levels decreased from an average of 12.4 to 9.2 ng/mL. Harris Hip Scores increased significantly after revision (45.8 to 72.1). Conclusion. This study presents 35 revisions of a recalled monoblock hip prosthesis performed by a single surgeon at our institution from 2010 to 2015. To our knowledge, this is the largest single-surgeon study reported in the literature. Acetabular cups were revised to a lower average abduction angle. Patients have had significant improvements in Harris Hip Scores and significant decreases in Cobalt and Chromium levels after revisions. Our revision survival rate to date is 94.3% at an average of 2.5 years (range 2 weeks – 4.3 years). To view tables/figures, please contact authors directly

Background. The use of reverse total shoulder arthroplasty considerably increased since first introduced by Paul Grammont in the late 1980s. Over the past few years, results from several mid- and long-term clinical studies have demonstrated good functional outcomes and pain relief. However, several complications, especially inferior glenoid notching, and high revision rates were reported in the literature. Improvements in prosthesis design should contribute to a lower complication rate and lesser amount of glenoid erosion. Few studies have reported the clinical outcome andcomplications of Anatomical Shoulder Inverse/ Reverse Prosthesis. This study documents 2- and 6-year clinical and radiological results following reversed shoulder arthroplasty using this novel prosthesis. Methods. We report the results for sixty-eight consecutive patients (seventy shoulders) with cuff tear arthropathy (CTA) treated with Anatomical Shoulder Inverse/Reverse Prosthesis between 2006 and 2008. Two groups were defined: (A) primary treatment and (B) revision. Clinical evaluation tools comprised Constant-Murley score (CS), range of motion, and a visual analog scale to assess pain. Radiographs (anteroposterior view in neutral position) were evaluated for notching and radiolucent lines. Any complications were recorded. Results. In total, 66 shoulders (94%) with a mean follow-up of 30.0 months were initially analysed. CS increased from preoperatively 20.2 to postoperatively 53.6 points. Inferior scapular notching was identified in 58% of patients, primarily grade 1 and 2 (low-graded). 16% of patients experienced a complication, including instability, infection or periprosthetic fracture. 58 patients (83%) were re-evaluated 69.0 months after implantation. CS decreased to 50.2 points (n.s.). 16 patients (23%) had postoperative complication at final follow-up. We observed progressive radiographic changes in 75% and an increased frequency of large notches (grade 3 and 4). No significant difference regarding clinical outcome was detected between group A and B after both 2 and 6 years. Conclusion. Total shoulder arthroplasty with the Anatomical Shoulder Inverse/Reverse Prosthesis is a reliable treatment option in patients with cuff tear arthropathy. Primary and revision arthropathies result in similar improvements in range of motion and pain. Constant-Murley score and radiographic changes deteriorated with time. Inferior scapular notching appeared rapidly after implantation. A change of prosthesis design and prosthetic overhang intraoperatively seems to be the most effective way to prevent scapular conflict. The complication rate in our series is equally to previously reported rates

Purpose of the study: Revision shoulder arthroplasty is generally considered to be a difficult procedure yielding modest improvement. Material and methods: We report a prospective study of 45 patients, aged 69.8 years (range 49–85 years). Thirty-two patients had a simple humeral prosthesis and thirteen a total prosthesis. A reversed prosthesis was used for all revisions. The reasons for the revisions were classified into five groups: failure of prosthesis implanted for fracture (36%), glenoid problems of a total shoulder arthroplasty (24%), prosthetic instability (18%), failure of a hemiarthroplasty implanted for rotator cuff tear (11%), failure of a hemiarhtroplasty implanted for post-traumatic osteoarthritis (11%). The revision consisted in replacement with a reversed prosthesis. Patients were assessed pre and postoperatively using the Constant score for the clinical assessment and plain x-rays for the radiological assessment. Results: Forty-one patients were reviewed at mean follow-up of 42.1 months (range 24–92). The four other patients died during the first two postoperative years. Subjectively, 73% of patients were satisfied. The Constant score improved from 187.7 to 55.6 on average. The best gain was obtained for the pain and daily activities scores. Discussion: Revision shoulder arthroplasty provides only moderate improvement. Neer called a limited goal surgery. Results published on revision shoulder arthroplasty using a non-constrained prosthesis show that the functional gain is moderate. Revisio with a reversed total prosthesis gives better results because of the lesser impact of the cuff deficiency. The rate of complications after revision is greater than with first intention implantations. Conclusion: Use of a reversed total shoulder prosthesis for revision shoulder arthroplasty provides encouraging results in terms of the mid-term functional outcome

Summary. Revision TKA using CCK prosthesis showed comparable outcome to PS prosthesis in clinical and radiological results. Introduction. In revision total knee arthroplasty (TKA), the goal should be to obtain good motion, function and most importantly stability. The stability depends on remaining soft tissue and implant design. The more the ligaments retain function, the less the implant constraint is needed to achieve stability. With increased constraint, the transfer of joint reaction forces to implant-bone interface may lead to mechanical loosening of the implant. Constrained condylar knee (CCK) prosthesis provides more constraint compared with posterior stabilized (PS) prosthesis. The purpose of this study was to compare the clinical, radiological outcome and survivorship of CCK and PS prosthesis in revision TKA. Materials and Methods. One hundred and twenty-one consecutive revision TKAs using CCK (79 knees) and PS (42 knees) were included. The mean follow-up period was 63.2 months for CCK and 64.8 months for PS. The mean age was 69.5 years and 70.6 years in CCK and PS, respectively. Range of motion (ROM), American Knee Society (AKS) score, Hospital for Special Surgery (HSS) score, complications and failure rate were assessed. Radiographic measurements included tibiofemoral angle and radiolucent lines. The Kaplan-Meier survivorship analysis was performed with an end point of re-revision surgery for any reason and compared between CCK and PS using the Log-rank test. Results. The mean range of motion improved from 97.5° to 115.9° in PS, from 89.5° to 110.1° in CCK. The mean Knee Society knee and functional scores improved from 47.6 and 36.4 to 89.7 and 66.1 with PS, from 53.5 and 41.7 to 79.2 and 66.8 with CCK. The mean Hospital for Special Surgery knee score also improved from 57 to 76.9 and 59.7 to 77.6, respectively. The complication rate was 7.5% (4 cases; 3 recurred infections, 1 instability) in PS and 10.3% (7 cases; 4 recurred infections, 1 periprosthetic fracture, 2 stem tip pains) in CCK. The Kaplan–Meier survivorship analysis revealed that ten year survival of the components was 85.4% for PS and 80.0% for CCK. In all aspects, there were no statistical difference (a p-value of more than 0.05) between PS and CCK. Conclusion. Revision TKA using CCK prosthesis showed comparable outcome to PS prosthesis in clinical and radiological results. CCK prosthesis is a reliable and successful option for prosthesis selection in revision TKA when PS prosthesis is not enough for management of instability

Aim. Shoulder prosthesis chronic infection is a rare but serious complication, likely to lead to re-interventions and poor functional outcome. Two-stage exchange surgery is considered the standard procedure by most authors. Our hypothesis was that one-stage revision procedure is a valid therapeutic option in the management of chronic infections of shoulder arthroplasty. Method. This was a mono-center retrospective cohort study. All patients who underwent, during the inclusion period, a one-stage revision procedure for a chronic infection of shoulder arthroplasty were included. All patients underwent clinical evaluation (Constant-Murray score), radiological examination (standard X-rays) and a blood test (Complete Blood Count and C-reactive protein), at a minimal one-year follow-up. Primary endpoint of this study was the infectious outcome and secondary endpoints were the functional and radiographic outcomes. Results. 16 shoulder prosthesis in 14 patients (5 females, 9 males) were included. Mean time between primary prosthesis implantation and exchange surgery was 40 months (1–145). Mean follow up was 30,5 months. The principal micro-organism involved was Propionibacterium acnes (9/16) and multiple organisms were found in 6 patients. In 14/16 (87,5%) shoulders, we found no sign of persistent infection at last follow-up. 2/16 (12,5%) shoulders were considered as still infected. On these 2 patients still infected, one refused further revision and the other was not in a good enough medical condition to undergo another procedure. 2 patients required an additional one-stage procedure for a new infection (new pathogen) after a period of two years, both free of infection at last follow-up. At last follow-up, mean Constant score was 54,8 (23–82). 7/14 (50%) patients were satisfied or very satisfied with the global fonctionnal result. Conclusions. One-stage revision procedure seems to be a valid therapeutic option in the management of infected shoulder prosthesis, as it allowed us to eradicate the infection in 87,5% patients in our serie, with a fair clinical result

Purpose. This study compares outcomes in patients with complete congenital fibula absence, associated with severe lower limb deformity, treated with an amputation protocol to those using an extension prosthesis. Method. 32 patients were identified. 9 patients (2M: 7F, median age at presentation of 22 yrs) utilized an extension prosthesis. 23 patients (16M: 7F, median age at presentation of 10 months) underwent 25 amputations during childhood: only two underwent tibial kyphus correction to facilitate prosthetic wear. Mobility was assessed using the SIGAM and K scores. Quality of life was assessed using the PedsQL inventory questionnaire; pain by a verbal severity score. Patients undergoing amputation were further subdivided by age, below and above 2 yrs at the time of surgery. Results. 19 Syme and one Boyd amputation in 19 patients were performed early (mean age 15 months). 4 Syme and one trans-tibial amputation in 4 patients took place in older children (mean age 6.6 years). K Scores were significantly higher (mean 4 versus 2) and pain scores lower in the amputation group allowing high impact activity compared to community ambulation with an extension prosthesis. The SIGAM and PedsQL scores were all better in the amputation group, but not significantly so. There was no significant difference in the scores based on the time of amputation. Conclusion. Complete fibula absence can present with significant lower limb deformity. Parental counselling regarding management is paramount in achieving the optimum functional outcome. Childhood amputation for severe limb length inequality and foot deformity in congenital fibula absence offers excellent short term functional outcome with prosthetic support. The tibial kyphus deformity does not need routine correction and facilitates prosthetic suspension. Accommodative extension prosthesis does offer reasonable long term function but outcome scores are lower

Summary Statement. The constraint behavior of total knee arthroplasty (TKA) prosthesis usually has to be physically tested. This study presents a computer simulation model using finite element analysis (FEA) and demonstrates its effectiveness in predicting the femorotibial constraint behavior of TKA implants. Introduction. TKA prostheses are semi-constrained artificial joints. A well-functioning TKA prosthesis should be designed with a good balance between stability and mobility, meaning the femorotibial constraint of the artificial joint cannot be excessive or too lax. To assess the constraint behavior of a TKA prosthesis, physical testing is usually required, and an industrial test standard has been developed for this purpose. Benefiting from technological advancement, computer simulation has become increasingly useful in many industries, including medical device research and development. FEA has been extensively used in stress analysis and structural evaluation of various orthopaedic implants. This study presented an FEA-based simulation to evaluate the femorotibial constraint behavior of TKA prosthesis, and demonstrated the effectiveness of the method by validating it through physical testing. Methods. A Cruciate Retaining (CR) TKA prosthesis design (Optetrak Logic CR, size 3, Exactech, FL, USA) was used in this study. The prosthesis system consists of a femoral component, a tibial insert, and a tibial baseplate. CAD models of the implants assembled at 0° of flexion were used for the simulation. Finite element models were generated using 10-node tetrahedral elements, with all materials considered linear elastic. Boundary conditions were set up according to the ASTM F1223 standard. The tibial baseplate was fixed distally. A constant compressive force (710 N) was applied on the femoral component. Nonlinear Surface-Surface-Contact was defined at the femorotibial articulating surfaces as well as between the tibial insert and tibial baseplate. A coefficient of friction of 0.2 determined from the physical test was input into the simulation. The femoral component was driven under a displacement-controlled scheme to slide along the anterior-posterior (AP) direction on the tibial insert. At each time step, constraint force occurring at the articulating surface was derived from the reaction force at the distal fixation of the tibial baseplate. The force-displacement curve was plotted by combining the results of all time steps to characterize the constraint behavior of the prosthesis. A nonlinear FEA solver (NX Nastran SOL601, Siemens, TX, USA) was used to solve the simulation. In addition, five samples of the prostheses were physically tested per ASTM F1223. Simulation results were compared to the physical testing. Results. The simulation successfully captured the movement of contact location and pressure along the movement of the femoral component. The force-displacement curve predicted by the simulation exhibited a very close hysteresis loop profile as the results of physical testing. Using the curve slope from 0 to 5 mm to characterise the constraint in the most relevant displacement range, the simulation predicted 45.7 N/mm anteriorly and 36.4 N/mm posteriorly, which are less than 10% different from the physical testing results (46.4 N/mm anteriorly and 39.6 N/mm posteriorly). Discussion/Conclusion. This study demonstrated that the simulation was able to closely predict the femorotibial constraint behavior of the TKA prosthesis under ASTM F1223 testing. The simulation results resembled the physical test results not only in the general profile of the curve but also in the magnitude of slope values. The increased difference at the far anterior region could be related to the fact that no material nonlinearity was considered in the current simulation, a factor that could be improved in future studies. A validated simulation method could be very useful in TKA prosthesis design. Since no physical prototypes are required, design evaluation and optimization can be achieved in a much easier and faster manner

Introduction. Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE in the human body after total joint replacement causes serious clinical and biomechanical reactions. Therefore, the wear phenomenon of UHMWPE is now recognized as one of the major factors restricting the longevity of artificial joints. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear mechanism of UHMWPE. Materials and Methods. In a previous study (Cho et al., 2016), it was found that roundness (out-of-roundness) of the retrieved UHMWPE acetabular cup liner [Figure 1(a)] had a tendency to increase with increasing roundness of the retrieved metal femoral head [Figure 1(b)]. It appears that roundness of the femoral head contributes to increase of wear of the polyethylene liners. We focused on the roundness of femoral head as a factor influencing the wear of polyethylene liner in hip prosthesis. In this study, further roundness measurements for 5 retrieved metal femoral heads were performed by using a coordinate measuring machine. The elasto-plastic contact analyses between femoral head and polyethylene liner using the finite element method (FEM) were also performed in order to investigate the influence of femoral head roundness on the mechanical state and wear of polyethylene liner in hip prosthesis. Results. The range of roundness of the 5 retrieved metal femoral heads measured in this study was 14.50∼44.70 µm. Two examples of the results of FEM contact analyses are shown in Figure 2. Figure 2(a) is the results of the repeated contact analysis between femoral head and polyethylene liner under constant axial loading of 1000 N. Figure 2(b) is the results of the repeated contact analysis between femoral head and polyethylene liner under hip joint loading during normal gait. These figures show the distribution of the contact stress (von Mises equivalent stress) in the polyethylene liner. The graph in Figure 3 shows the changes in the maximum contact stress in the polyethylene liner with the flexion/extension angle of femoral head. Discussion and Conclusions. As the results of a series of the FEM contact analyses, it was found that repeated high contact stresses which exceed the yield stress of UHMWPE caused by roundness of the metal femoral head occurred in the polyethylene liner as shown in Figures 2 and 3. It was also found that the magnitude and amplitude of the repeated contact stresses had a tendency to increase with increasing roundness of the femoral head and axial loading applied to the femoral head. The results of this analytical study suggest that the roundness (out-of- roundness) of the femoral head is associated with accelerating and/or increasing wear of the UHMWPE acetabular cup liner in a hip prosthesis after total hip replacement. For any figures or tables, please contact authors directly