Open debridement, irrigation with implant retention and antibiotic treatment (DAIR) is an accepted approach for early prosthetic joint infections (PJI). Our aim was to design a score to predict patients with a higher risk of failure. From 1999 to 2014 early (<90 days) PJIs without signs of loosening of the prosthesis were treated with DAIR and were prospectively collected and retrospectively reviewed. The primary end-point was early failure defined as: 1) the need of an unscheduled surgery, 2) death-related infection within the first 60 days after debridement or 3) the need for suppressive antibiotic treatment. A score was built-up according to the logistic regression coefficients of variables available before debridement. A total of 222 patients met the inclusion criteria. The most frequently isolated microorganisms were coagulase-negative staphylococci (95 cases, 42.8%) and Staphylococcus aureus (81 cases, 36.5%). Fifty-two (23.4%) cases failed. Independent predictors of failure were: chronic renal failure (OR:5.92, 95%CI:1.47–23.85), liver cirrhosis (OR:4.46, 95%CI:1.15–17.24), revision surgery (OR:4.34, 95%CI:1.34–14.04) or femoral neck fracture (OR:4.39, 95%CI:1.16–16.62) compared to primary arthroplasty, CRP >11.5 mg/dL (OR:12.308, 95%CI:4.56–33.19), cemented prosthesis (OR:8.71, 95%CI:1.95–38.97) and when all intraoperative cultures were positive (OR:6.30, 95%CI:1.84–21.53). Furthermore, CRP showed a direct relationship with the percentage of positive cultures (Linear equation, R2=0,046, P=0.002) and an inverse association with the time between the debridement and failure (Logarithmic equation, R2=0.179, P=0.003). A score for predicting the risk of failure was done using pre-operative factors (KLIC-score, figure 1) and it ranged between 0–9.5 points. Patients with a score ≤2, >2–3.5, 4–5, >5–6.5 and ≥7 had a failure rate of 4.5%, 19.4%, 55%, 71.4% and 100%, respectively. The KLIC-score was highly predictive of early failure after debridement. In the future, it would be necessary to validate our score using cohorts from other institutions

Over the past ten years we have seen a move to less invasive surgical approaches and simplification of OR procedures; hence, there has been a renewed interest in the use of rectangular wedge-taper design hip stems. I present a personal series of over five hundred Accolade (Stryker) stems with a high (6%) early failure rate. Cases are drawn from a personal database. These patients presented with either pain or difficulty with stair-climbing. Several remain asymptomatic, but radiographs are early identical in all cases. Impressive radio-lucent and sclerotic lines are seen on the lateral radiograph in Gruen zones VIII and XIV at between three and six months, and later appear in Gruen I. Most occurred in type A or AA bone. These failures are interesting as they are due to rotational loosening, not axial subsidence. To date, 6 of 12 have been revised, all showing complete lack of ingrowth to proximal porous coating. Rectangular wedge-taper design stems have enjoyed high success rates in several published series. However, the author believes that the use of this stem in Type A or AA bone leads to preferential distal (diaphyseal) taper engagement, which negates proximal (meta-diaphyseal) taper engagement, and predisposes the stem to rotational micromotion, failure of ingrowth, and subsequent loosening. To our knowledge, this is the first paper to recognise this mode of failure. The authors strongly believe stems of this type should be used with caution in males with type A or AA bone

Modularity of femoral components has been widely accepted at the head neck junction, most commonly combining two unlike metals with only sporadic reporting of compatibility issues and corrosion. The development and introduction of a new and improved modular neck junction (Rejuvenate Modular Femoral component, Stryker Orthopedics) provided the option of fine-tuning leg lengths, offset and stability. The surgical technique did indeed provide the desired endpoints, however, the early recognition of problems with the junction causing corrosion and Adverse Local Soft Tissue Reaction (ALTR) and subsequent revision has led to the product being voluntarily withdrawn from the market. My experience as an early user of this stem is described in this manuscript providing a better early recognition and treatment of this potentially very destructive process. Methods. A retrospective review of one hundred and ninety one Rejuvenate Stems that were implanted between January 2010 and January of 2012. However, after March 2011, this stem was only used on those patients who had a rejuvenate stem on the contralateral side. They were all implanted through a mini posterior incision with the first 82 patients receiving a Tritanium cluster hole cup (Stryker Orthopedics) with between two and three screws. The remaining 109 patients had an ADM (Anatomic Dual Mobility, Stryker Orthopedics). All patients were allowed to bear weight as tolerated and were followed up with Xrays at six weeks and one year. Clinical visits were recorded at 2 weeks and 6 months postop. Additional follow up was scheduled every two years following the first annual visit. Results. One hundred and seventy four of the 191 hips were available for review at the one-year follow-up. Fourteen patients have undergone revision of the hip due to increased pain and formation of an avascular pseudo capsule due to corrosion at the neck stem junction. All patients have demonstrated a black flaky residue at the taper junction and all have had a large, tense effusion with a milky colored fluid. A neo caspsule has formed in all patients that appeared avascular and thickened. Seven of the eight tritanium cups in the revision cases were loose and required revision, while none of the ADM cups were loose. One patient has undergone two revisions since the initial cause of failure was not recognized and she subsequently developed pain within three months following placement of a new modular neck at the initial revision. One patient who underwent revision developed a deep infection and is currently on antibiotics but has not cleared the infection as of this writing. Conclusion. There has been catastrophic early failure of a modular femoral component due to corrosion at the neck stem junction during the very early stages of follow up. An intense reaction appears to begin early on, perhaps contributing to failure of bony ingrowth in certain cup designs but not others. Patients who develop early onset of discomfort progress to a poorly functioning hip that presents with pain, swelling and decreased ROM. These patients need to be assessed with serum ion levels, joint aspiration for infection and ion levels if possible. A MRI with MARS technology is useful in identifying joint fluid and neo caspsule expansion. These patients should be advised on the adverse reaction that can develop and revision of the hip should be expeditiously carried out

Background. A commonly held belief amongst surgeons and patients is that progression of disease (arthritis) to other compartments is a major cause of early failure of UKRs. Methods. We analysed the NJR database records of 17,643 primary UKRs performed between April 2003 and April 2009. Where these had been revised the reason for revision was noted. Results. Of the 17,643 primary UKRs, 308 had died and were excluded from the analysis. Of the living, 505 had been revised (3%) at a mean 3.45 years (range 2-6 years) following the primary procedure. Reason for revision was recorded in 472 cases (93%). Aseptic loosening was the commonest cause for revision in 154 cases (33%), followed by non specific pain in 129 cases (27%), bearing dislocation in 58 cases (12%), Instability in 33 cases (7%), Infection 28 cases (6%), progression of disease 23 cases (5%), periprosthetic fracture 19 cases (4%) and malalignment 15 cases (3%). 35% failed within 1 year, 38% within 2 years and 16% within 3 years of the index operation. Conclusion. Similar findings has been reported on the New Zealand Registry 10 year report where the overall revision rate was 284/4,826 (5.9%), and revision due to disease progression 7.7%. Progression of disease is not a major cause of early failure of UKRs. 73% of the failures occurred within two years of surgery. Other causes such as aseptic loosening, bearing dislocation and instability are more common and could be possibly ameliorated by improved surgical technique, better patient selection and component choice

Introduction. Although good mid-term results have been reported with some metal on metal hip replacements, reported complications due to metal on metal (MOM) related reactions are a cause for concern. We have assessed the early clinical outcome and results of routine metal artefact reduction MRI findings in a consecutive series of patients with a modern large head metal on metal hip replacement. Methods. 62 ASR XL Corail total hip replacements (THR) and 17 ASR resurfacings were performed at our hospital between 2005 and 2008. All patients were reviewed and assessed with an Oxford hip score (OHS), a plain radiograph and a MRI imaging was obtained on 76 (96%) hips. Implant position was assessed using Wrightington cup orientation software. Results. At a mean follow-up of 32 months, 8 ASR XL Corail THRs had been revised. 6 revisions were performed for MRI-confirmed MOM-related pathology. Histology confirmed a MOM reaction in all 6 cases. Of the 76 hips that were MRI scanned, 27 (36%) had typical features of a MOM reaction. These were classified as mild in 5 (7%), moderate in 18 (24%) and severe in 4 (5%). 78 patients completed an OHS and the mean score was 21. The mean OHS was 37 pre-operatively in those that had been revised, 19 in patients with abnormal MRI findings and 23 in those with a normal MRI. 10 patients with abnormal MRIs had a near perfect OHS (15 or less). Conclusion. The ASR XL Corail THR has an unacceptably high early failure rate. MRI detected metal debris related soft tissue related reactions were very common and often asymptomatic. We recommend that patients with this implant should be closely followed up and undergo routine metal artefact reduction MRI screening

Background. There are different opinions amongst surgeons as to the selection criteria for UKR with regards to age and BMI. Many surgeons perceive higher rates of failure in young or overweight patients or often choose TKR for elderly patients. Methods. We analysed the registry records (UK National Joint Registry) of 10,104 patients who had undergone UKR with a minimum of two years follow-up from their primary surgery. BMI data was recorded in 1,831 (18%) and age in all. There were 295 deaths and these patients were excluded from our analysis. Patients' BMI were categorised according to Department of Health and WHO (2004) classification (Normal, Pre-Obese, Obese I, Obese II, Obese III). Results. For the 1,831 patients with BMI data recorded, 4.74% had been revised at a mean 3 years post-primary UKR. BMI Category had no significant effect on revision rates. Age less than 50 was a predictor of a significantly higher rate of revision: 35 out of 488 primary UKRs (7%) compared with 138 out of 2,618 (5.5%) in 50-59 year age group, 154 out of 3,810 (4.1%) in 60-69 year age group and 85 out of 2,505 (3.6%) in 70-79 year age group. Revision rates were lowest in patients with age greater than 80 years: 14 out of 562 (2.49%). Conclusion. UKR should be recommended with caution in patients with age less than 50. Revision rate decreases significantly with age. BMI Category was found to have no significant correlation with early failure

There is a report that higher failure rate in uncemented total knee replacement components due to loosening. However, uncemented fixation has been an attractive concept because of bone preservation and revision surgery, potential improved load transfer, and decreased surgical time. “Regenerex” is a porous titanium layer with excellent initial fixation, and the promise of providing favourable biological fixation. This is used with the Biomet Vanguard total knee replacement.

14 patients had undergone total knee replacement surgery comprising 11 men and three women with an average age of 63.07 years, and a body mass index of 30.33. Three of these patients required revision, because of tibial component loosening within 12 months of surgery. There were two men and one woman with an average age of 63.33 and BMI of 34.55. Clinically, patients developed pain and a gradual deformity as a result of a symmetrical collapse of the proximal tibial bony support surface.

Histopathology on the removed specimens shows the development of fibre cartilaginous metaplasia with evidence of necrotic bone. This was similar in all patients. There was no foreign body giant cell reaction, and no evidence of infection. The appearance was suggested of osteonecrosis, occurring gradually.

The incidence of frequency of this complication with this component in our experience is of concern, and the aim of this presentation is to determine whether this is a more widespread phenomenon.

During a retrospective case note analysis, a significant difference was found in prosthesis survival, between two cohorts of patients who underwent different total knee replacements. The first cohort included 70 patients who underwent Kinemax Plus total knee replacement, the second cohort included 58 patients who underwent PFC Total Knee replacement. All patients were under the care of one Consultant Orthopaedic Surgeon. Interestingly, the Kinemax Plus cohort was found to have a higher rate of revision compared to the PFC cohort. A detailed comparison was carried out between the two groups to identify any obvious cause for the disparity.

The two cohorts were found to be well matched with respect to age, sex, ASA grade, underlying pathology and operative technique. Median follow up being 6 years and 5 years for the Kinemax Plus and PFC groups respectively.

There were 11 failed prostheses in the Kinemax Plus cohort, 7 undergoing revision with the remaining 4 patients offered revision but unwilling to have surgery. Wear of the polyethylene tibial insert was the most obvious finding at revision, present in six of the seven revisions. 97% of the Kinemax Plus Prostheses were intact at 5 years but by 8 years only 87% were intact. There were no revisions performed in the PFC cohort.

Post-operative x-ray analysis was undertaken to rule out prosthesis malalignment as a cause for the increased failure rate. The coronal alignment of the prostheses (CAK) was calculated and all post operative x-rays were within the normal limits of 4-10 degrees.

Analysis of the explanted Kinemax Plus polyethylene liners was undertaken. In six cases, the polyethylene bearing surfaces displayed severe surface and subsurface delamination. This suggests massive fatigue and fatigue wear. Only one implant showed localised delamination.

These findings suggest the hypothesis of weak polyethylene particle interface strength.

Background. The direct anterior approach (DAA) for total hip arthroplasty (THA) is marketed with claims of superiority over other approaches. Femoral exposure can be technically challenging and potentially lead to early failure. We examined whether surgical approach is associated with early THA failure. Methods. A retrospective review of 478 consecutive early revision THAs within five years of primary THA at three academic centers from 2011 through 2014 was performed. Exclusion criteria resulted in a final analysis sample of 341 early failure THAs. Primary surgical approach was documented for each revision, along with time to revision, and failure etiology. Results. Early femoral component failure was more common with the DAA (49.6%) than the direct lateral (36.6%) and posterior (13.8%) approaches (p = 0.001). In multivariate regression controlling for age, sex, laterality, Dorr bone type, BMI at revision, bilateral procedure (yes/no), and femoral stem type, the DAA remained a significant predictor of early femoral failure (p = 0.001). The majority of early revisions for instability were associated with the posterior approach (47.5%) and the DAA (37.5%) compared to the direct lateral approach (15.9%, p = 0.0002). Conclusions. Despite claims of early recovery and improved outcomes with the DAA, our findings indicate the DAA likely confers greater risk for early femoral failure and, along with the posterior approach, a greater risk of early instability compared to the direct lateral approach following THA

Purpose

The NexGen® legacy posterior stabilized (LPS)-Flex total knee system (Zimmer, Warsaw, IN) is designed to provide 150° of flexion following total knee arthroplasty (TKA). But, recent reports found a high incidence of loosening of the femoral component related to the deep flexion provided. We evaluated 9- to 12-year clinical and radiological follow-up results after NexGen® LPS-Flex TKA.

Joint registries suggest a downward trend in the use of uncemented Total Knee Replacements (TKR) since 2003, largely related to reports of early failures of uncemented tibial and patella components. Advancements in uncemented design such as trabecular metal may improve outcomes, but there is a scarcity of high-quality data from randomised trials. 319 patients <75 years of age were randomised to either cemented or uncemented TKR implanted using computer navigation. Patellae were resurfaced in all patients. Patient outcome scores, re-operations and radiographic analysis of radiolucent lines were compared. Two year follow up was available for 287 patients (144 cemented vs 143 uncemented). There was no difference in operative time between groups, 73.7 v 71.1 mins (p= 0.08). There were no statistical differences in outcome scores at 2 years, Oxford knee score 42.5 vs 41.8 (p=0.35), International Knee Society 84.6 vs 84.0 (p=0.76), Forgotten Joint Score 66.7 vs 66.4 (p=0.91). There were two revisions, both for infection one in each group (0.33%). 13 cemented and 8 uncemented knees underwent re-operation, the majority of these being manipulation under anaesthetic (85.7%), with no difference (8.3% vs 5.3%, 95% CI -2.81% to 8.89%, p = 0.31). No difference was found in radiographic analysis at 2 years, 1 lucent line was seen in the cemented group and 3 in the uncemented group (0.67% v 2.09%, 95%CI -4.1% to 1.24%, p = 0.29). We found no difference in clinical or radiographic outcomes between cemented and uncemented TKR including routine patella resurfacing at two years. Early results suggest there is no difference between cemented and uncemented TKR at 2 years with reference to survivorship, patient outcomes and radiological parameters

Aim. Our aim was to evaluate the prevalence and impact of unexpected intraoperative cultures on the outcome of total presumed aseptic knee and hip revision surgery. Method. Data regarding patients prospectively recruited in our center, who had undergone elective complete hip and knee revision surgery from January 2003 to July 2017 with a preoperative diagnosis of aseptic loosening was retrospectively reviewed. Partial revisions and patients with follow up below 60 months were excluded from the study. The protocol of revision included at least 3 intraoperative cultures. Failure was defined as the need for re-revision due to any-cause at 5 years and/or the need for antibiotic suppressive therapy. Results. A total of 608 cases were initially included in the study, 53 patients were excluded. 123 hip and 432 knee revision surgeries were included. 420 cases (75.7%) had all cultures negative, 114 (20.5%) a single positive culture or two of different microorganisms and 21 (3.8%) had at least 2 positive cultures for the same microorganism. Early failure was found in 4.8% (1/21) of the patients with missed low grade infection. The presence of positive cultures during total exchange was not associated with a higher failure rate than in those with negative cultures (44 of 420, 10.5%). In contrast, patients revised before 24 months had a significant higher rate of re-revision, 18% (15/83) vs. 8.4%. Conclusions. Total hip and knee revisions with unexpected positive cultures were not significantly associated with a higher re-revision risk at 5 years of follow-up. Representing an overall good prognosis. However, revision surgeries performed within the first 24 months have a higher rate of failure

Introduction. Satisfaction and survival rates after total knee arthroplasty were high according to literatures. However, around 8% of revision surgeries were still noted and almost half of them were early failures, which were most seen in 2 years after primary surgery. This study aimed to find out the factors lead to early failures after total knee arthroplasty. Materials and Methods. Data were collected based on the National Health Insurance Research Data Base of Taiwan from 1996 to 2010. Primary total knee arthroplasty surgeries were included. Revisional total knee arthroplasty, removal of total knee implant and arthrotomy surgeries registered after primary total knee surgeries are seen as failures. Results. 1. Overall prevalence. Total failure rate is 3.67% (4820 in 131441) and 44.46% of them are early failures in two years after primary surgery (2143 in 4820). 2. Characters of patient. Higher early failure rates were found in patients who accepted primary surgery under 56 years old, compared to 56∼64 years old and <65 years old groups (>65years/old compared to <56years/old, HR:0.51 [95% CI 0.44–0.58]; 56–64 years/old compared to <56years old, HR:0.61 [95% CI 0.52–0.72]). Male patients were found to have higher early failure rates compared to female group (compared to female, HR:1.55, [95% CI 1.41–1.69]). 3. Character of disease. Diagnosis of Osteoarthritis or rheumatoid arthritis would have no difference in failure rates, but gouty arthritis and other reasons would lead to higher early failure rates (compared to osteoarthritis, HR:1.94, [95% CI 1.55- 2.42]). 4. Influences of comorbidity. Diabetes Mellitus would lead to higher early failure rate (compared to non-DM, HR:1.28, [95% CI 1.13–1.46]). No significant differences were found in Renal disease and higher Charlson Comorbidity Index. 5. Character of Health Care Provider. 41.50% surgeries were performed in Medical Centers(>500 beds), 27.20% in Metropolitan Hospitals(>250 beds) and 31.20% in Local Community Hospitals(>20 beds). Surgeries performed in Metropolitan and Local Community Hospitals would have higher early failure rates (Local compared to center H, HR:1.42 [95% CI 1.28 −1.57]; Metropolitan compared to center H, HR:1.23 [95% CI 1.11 −1.37]). 83.40% surgeries were performed by high volume surgeons. High volume surgeons would have lower early failure rates (compared to low volume, HR:0.62, [95% CI 0.52–0.75]). 87.20% surgeries were performed in high volume hospitals. High volume hospitals would have lower early failure rates (compared to low volume, HR:0.51, [95% CI 0.41- 0.63]). Conclusion and Discussion. Early failure rate (<2 years after primary surgery) in Taiwan is compatible to global data. Younger patients accepted total knee arthroplasty would have more failures, which might be a result of higher activity demand. Reasons other than osteoarthritis and rheumatoid arthritis such as gouty arthritis, hemophilia, post-traumatic arthritis and osteonecrosis can complicate the surgery and lead to higher failure rates. Patients with diabetes mellitus would have more infection risks and therefore lead to higher failures. High volume surgeons, high volume hospitals and even non-local hospitals could provide better trainings and facilities to patients, which can therefore lead to lower failures

Introduction. Stryde® lengthening nail has been recently withdrawn because of concerns about osteolysis and other bone lesions that have been observed early after implantation. The present study analyses the incidence and features of these bone lesions in our patients. Materials and Methods. This is a retrospective review of a series of patients from two centres specializing in limb reconstruction. Inclusion criteria was a history of surgery with Stryde® lengthening nail with more than one year follow-up available. All postoperative x-rays were and clinical notes were reviewed. Results. 36 patients with 75 bone segments were included. 11 (30.5%) patients and 32 (42.6%) bone segments were without any lesion. In 3 (8.3%) patients and 3 (4%) segments, osteolytic lesions only were noticed. 11(30.5%) patients and 14 (18.6%) segments had combined lytic lesions and periosteal reaction or cortical thickening. 12 (33.3%) patients and 26 (34.6%) segments developed only periosteal reaction or cortical thickening. 54.8% of patients with bilateral nailing had bilateral lesions. 52% of the patients with bone lesions reported late onset of pain after the completion of the lengthening. The average earliest interval that any of the lesions was noticed was 10.2 months post-surgery. Conclusions. Patients with Stryde® nails should be monitored clinically and radiologically at regular intervals until removal. The early failure and withdrawal of Precise Stryde® nail, is a significant event in the field of limb reconstruction; this study adds useful data to the growing pool of published data related to the this event

The Accolade®TMZF is a taper-wedge cementless metaphyseal coated femoral stem widely utilized from 2002-2012. In recent years, there have been reports of early catastrophic failure of this implant. Establishing a deeper understanding of the rate and causes of revision in patients who developed aseptic failure in stems with documented concerns about high failure rates is critical. Understanding any potential patient or implant factors which are risk factors for failure is important to inform both clinicians and patients. We propose a study to establish the long-term survival of this stem and analyze patients who underwent aseptic revision to understand the causes and risk factors for failure. A retrospective review was undertaken of all patients who received a primary total hip arthroplasty with an Accolade® TMZF stem at a high-volume arthroplasty center. The causes and timing of revision surgery were documented and cross referenced with the Canadian Institute of Health Information Discharge Abstract Database to minimize loss to follow-up. Survivorship analysis was performed with use of the Kaplan-Meier curves to determine the overall and aseptic survival rates at final follow-up. Patient and implant factors commonly associated with aseptic failure were extracted and Cox proportional hazards model was used. A consecutive series of 2609 unilateral primary THA patients implanted with an Accolade®TMZF femoral hip stem were included. Mean time from primary surgery was 12.4 years (range 22 days to 19.5 years). Cumulative survival was 96.1% ± 0.2 at final follow-up. One hundred and seven patients underwent revision surgery with aseptic loosening of the femoral component was the most common cause of aseptic failure in this cohort (33/2609, 1.3%). Younger age and larger femoral head offset were independent risk factors for aseptic failure. To our knowledge, this is the largest series representing the longest follow-up of this taper-wedge cementless femoral implant. Despite early concerns, the Accolade® TMZF stem has excellent survivorship in this cohort. Trunnionosis as a recognized cause for revision surgery was rare. Younger age and larger femoral head offset were independent risk factors for aseptic failure

Aim. Synovial fluid investigation is the best alternative to diagnose prosthetic joint infection (PJI) before adequate microbiological/histology sampling during revision surgery. Although accurate preoperative diagnosis is certainly recommended, puncturing every patient before revision arthroplasty raises concerns about safety and feasibility issues especially in difficult to access joint (e.g., hip), that often require OR time and fluoroscopy/ultrasound guidance. Currently there is no clear guidelines regarding optimal indications to perform preoperative joint aspiration to diagnose PJI before revision surgery. The main goal of this study is to determine the accuracy of our institutional criteria using the new European Bone and Joint Infection Society (EBJIS) PJI definition. Method. We retrospectively evaluated every single- or first-stage for presumed aseptic or known infected revision total hip/knee arthroplasty procedures between 2013–2020. Preoperative clinical and laboratory features were systematically scrutinized. Cases with insufficient information for accurate final PJI diagnosis (i.e., no perioperative synovial fluid examination or no multiple cultures including sonication of removed implant) were excluded. Preoperative joint aspiration is recommended in our institution if any of the following criteria are met: 1) elevated CRP and/or ESR; 2) early failure (<2 years) or repeat failure; 3) high clinical suspicion/risk factors are present. Performance of such criteria were compared against final postoperative EBJIS definition PJI diagnosis. Results. A total of 364 revision THAs or TKAs were performed during the study period. After excluding 258 cases with insufficient information, a total of 106 patients were ultimately included. 38 (35,8 %) were classified as confirmed infections, 10 (9.4 %) as likely infected and 58 (54.7%) as infection unlikely. Of those, 37 confirmed infection cases, 9 likely infected cases and 32 infection unlikely cases did have indication for preoperative synovial fluid collection before revision surgery. Institutional criteria showed 95.8 % Sensitivity, 44.83 % Specificity, 92.9 % Negative Predictive Value (NPV) and 59 % Positive Predictive Value (PPV). Conclusions. Sensitivity and NPV of the aforementioned institutional criteria are very high even with the use of the more sensitive EBJIS PJI definition. As such they seem to be a valid alternative in selecting patients that should be punctured before revision arthroplasty. They identify the vast majority of infected patients while saving a significant number of patients from unnecessary procedures

Introduction. Dislocation is a major cause of Total Hip Arthroplasty (THA) early failure and is highly influenced by surgical approach and component positioning. Robotic assisted arthroplasty has been developed to improve component positioning and therefore reduce post-operative complications. The purpose of this study was to assess dislocation rate in robotic total hip arthroplasty performed with three different surgical approaches. Methods. All patients undergoing Robotic Arm-Assisted THA at three centers between 2014 and 2019 were included for assessment. After exclusion, 1059 patients were considered; an anterior approach was performed in 323 patients (Center 2), lateral approach in 394 patients (Center 1 and Center 2) and posterior approach in 394 patients (Center 1 and Center 3). Episodes of THA dislocation at 6 months of follow up were recorded. Stem anteversion, Cup anteversion, Cup inclination and Combined Anteversion were collected with the use of the integrated navigation system. Cumulative incidence (CI), incidence rate (IR) and risk ratio (RR) were calculated with a confidence interval of 95%. Results. Three cases of dislocation (2 posterior approach, 1 anterior approach) were recorded, with a dislocation rate of 0.28% and an IR of 0.14%. Placement of cup in Lewinnek safe zone rate was 82.2% for posterior approach, 82.0% for lateral approach and 95.4% for anterior approach. Placement in the Combined Version safe zone rate was 98.0% for posterior approach, 73.0% for lateral approach and 47.1% for anterior approach. Despite the difference, dislocation IR was 0.30% for anterior approach, 0.34% for posterior approach and 0% for lateral approach. Conclusion. Robotic assisted technique is associated with low dislocation risk, especially in posterior approach. The Combined version technique appears to be a reliable way to reduce dislocation risk in the posterior lateral approach, but does not appear to be essential for lateral and anterior approaches

Introduction. Distal femoral and proximal tibial osteotomies are effective procedures to treat degenerative disease of the knee joint. Previously described techniques advocate the use of bone graft to promote healing at the osteotomy site. In this present study a novel technique which utilises the osteogenic potential of the cambial periosteal layer to promote healing “from the outside in” is described. Materials and Methods. A retrospective analysis of a consecutive single-surgeon series of 23 open wedge osteotomies around the knee was performed. The median age of the patients was 37 years (range 17–51 years). The aetiology of the deformities included primary genu valgum (8/23), fracture malunion (4/23), multiple epiphyseal dysplasia (4/23), genu varum (2/23), hypophosphataemic rickets (1/23), primary osteoarthritis (1/23), inflammatory arthropathy (1/23), post-polio syndrome (1/23), and pseudoachondroplasia (1/23). Results. There were two cases lost to follow-up with a median follow-up period 17 months (range 1–32 months). Union was achieved in all cases, with 1/23 requiring revision for early fixation failure for technical reasons. The median time to radiographic union 3.2 months (95% Confidence Interval (CI) 2.5–3.8 95% CI). CT scans demonstrated early periosteal callus, beneath the osteoperiosteal flap, bridging the opening wedge cortex. Clinical union occurred at 4.1 months (95% CI 3.9–4.2 months). Complications included superficial surgical site infection (1/23), deep vein thrombosis (1/23), and symptomatic metalwork requiring removal (7/23). Conclusions. The osteoperiosteal flap technique was a safe and effective technique for opening wedge osteotomies around the knee with a reliable rate of union

The value of joint registries is to (1) provide large scale longitudinal follow-up of classes of implants and individual implants—thereby providing potential for improved performance—and (2) serve as a tripwire for unexpected problem implants which is well appreciated. The purpose of this talk is not to reiterate the value of joint arthroplasty registries, but rather to look at several key findings from joint registries around the world and discuss what these mean for orthopaedic surgery today. Observation #1: Registries can tell us where the biggest problems are so we can act on them: Example: Early failures—those occurring in the first two years—account for about half of all failures by ten years. Early failures consist of mainly technically related problems and infections. If we can reduce these problems, we can reduce the number of patients having a second surgery after joint replacement by almost half. For one type of early failure (infection), the registry data show rate of infection after THA and TKA has not declined substantially in the last 20 years. We need major innovation in this area to solve this problem. On the other hand, registry data show early failures in older patients after THA are often due to periprosthetic femur fracture: we can solve this problem now with choice of stem fixation or prophylactic wires in high risk patients. Observation #2: Innovation can and does work! It is not correct to suggest that no new implants have led to improved results. Example: Registry data demonstrate that cross-linked polyethylene bearings have reduced the risk of revision after THA dramatically, especially in younger patients. Observation #3: Gathering more detailed information, such as patient reported outcomes, at least on limited samples of patients, can provide further insights. Example: Registry data demonstrate much greater variability in clinical outcomes of TKA in younger patients compared to older patients. Observation #4: Having national registries from different countries provides synergistic information. Example: Combining data from several national registries provides information on performance of femoral heads of different diameter and material that are not available from just one source. Observation #5: Registries may provide unexpected information that opens unexpected avenues for study. Example: Several registries demonstrate men have a 1.5–2 times higher risk of infection after TKA. We did not know this before. Why is this? Can we reduce it?

Unicompartmental knee replacement (UKR) is an established treatment for single compartment end-stage knee arthrosis with good recorded survivorship. Although often used in more active, younger patients, patient selection remains controversial. To identify risk factors for early failure we compared patients with UKR failure requiring revision to total knee replacement (TKR) with a control group. Between September 2002 and 2008, 812 Oxford Mobile Bearing Medial UKRs were implanted. 21 implants (20 patients) required revision to TKR within 5 years. The leading cause for revision was lateral compartment disease progression (11 patients). In the revision group, 17 patients were female (81%), average age at index surgery was 64.1 (range 48–81) and average BMI 31.8 (range 24.4–41.5). Our UKR patients with early failure requiring revision were more likely to be female (p=0.0012) whilst age and BMI were similar between groups. Although the change in tibio-femoral valgus angle was similar, control group patients started in varus becoming valgus post-operatively, whereas revision group patients started in valgus and became more valgus post-operatively. This might explain lateral compartment disease progression as our leading cause of early failure. We believe females with medial compartment disease but valgus alignment are at greater risk of early failure and it is particularly important not to overstuff the medial compartment