Commercially manufactured spacers for the treatment of periprosthetic joint infection of the hip.

BACKGROUND: Periprosthetic joint infection remains a common and serious complication after hip arthroplasty. To improve function and patient comfort after joint removal in two-stage revision, commercially manufactured spacers for the hip joint allow retention of the anatomical joint geometry thereby limiting soft tissue contraction and allow mobilization. INDICATIONS: Periprosthetic joint infection of the hip, septic arthritis with severe destruction of the hip cartilage and/or bone requiring arthroplasty. CONTRAINDICATIONS: Allergies to polymethylmethacrylate (PMMA) or antibiotics, severe hip dysplasia with insufficient cranial support, incompliant patient, large osseous defect of the acetabulum, insufficient metaphyseal/diaphyseal support of the femoral bone, resistance of the microbiological pathogen to spacer-inert antibiotic medication, inability to perform primary wound closure requiring temporary open-wound therapy. SURGICAL TECHNIQUE: Preoperative templating on radiograph; removal of joint prosthesis and thorough debridement with removal of all foreign material; trial spacer selection and insertion and trial reduction of the joint, fixing the spacer with PMMA to the proximal femur, final reduction, radiograph and stability test. RESULTS: Data were analyzed from patients treated between 2016 and 2021. In all, 20 patients were treated with preformed spacers and 16 with custom-made spacers. Pathogens were detected in 23 of the 36 cases (64%). Polymicrobial infections were present in 8 of 36 cases (22%). In patients who received preformed spacers, there were 6 cases of spacer-related complications (30%). Of the 36 patients (83%), 30 were reimplanted with a new implant; 3 patients died due to septic or other complications before reimplantation (8%). Average follow-up was 20.2 months after reimplantation. There were no major differences between the two groups of spacers. Patient comfort was not measured.

Video Based Assessment of Treatment Urgency in Outpatient Orthopaedic and Trauma Patients - a Pilot Trial. / Videobasierte Einschätzung der Behandlungsdringlichkeit - eine Pilotstudie für ambulante Patienten in der Orthopädie und Unfallchirurgie.

INTRODUCTION: When consulting a specialist in orthopaedics and trauma surgery, personal assessment and manual clinical examination by the doctor on site are essential. Nevertheless, implementation of video consultation hours has been made legally easier in Germany. The present pilot study examines the possibility of video-based assessment of the urgency of treatment in outpatient orthopaedic and trauma patients. MATERIALS AND METHODS: Within an ex ante study design, 40 patients with an orthopaedic clinical picture for trauma surgery with elective, urgent or emergency indication were selected from consultation hours. A short questionnaire was filled in based on the information provided and a medical colleague simulated a movement sequence based on the patient information. After modification to the "red flags" and "yellow flags" established in spinal orthopaedics, nine short questions were recorded, which inquire about the urgency of a medical consultation. The video-based movement sequence is based on a 60 s long instruction video in which motor tests and movement sequences are demonstrated: Cervical spine movement in all levels, elevation of the upper extremity, test of the finger-floor distance when "bending forward over-bending", possibility of crouching from standing and getting up again, standing on heels and toes. RESULTS: In 91.1% (n = 328) of the cases, the diagnosis was associated with the same joint or the same pathological entity. In 37.5% (n = 135) of the cases an emergency indication was seen, in 10.8% (n = 39) of the cases an urgent indication and in 51.6% (n = 186) of the cases it was seen to offer an elective indication. 12.5% (n = 45) of the cases were evaluated as "false positives" with regard to an emergency or urgent presentation. This means that the test persons were classified as "emergency" or "urgent", although there was no preventable dangerous course or medical emergency. 18 cases (5%) were evaluated as "false negative". DISCUSSION: The screening questionnaire presented and the short video assessment are technically feasible and practicable method for the initial evaluation in video-based online medical consultation. In addition, the questionnaire presented in combination with the short video assessment was suitable as an instrument for assessing the urgency of the consultation and selecting preventable dangerous processes and acute emergencies. CONCLUSION: The questionnaire, in combination with the short video assessment, is a suitable method for the social distancing requirements during limited accessibility of the medical system. Nevertheless, a false negative rate of 5% is too high to implement the questionnaire presented into daily clinics without further optimisation.

[Minimally invasive tibialis anterior tendon transfer in shuttle technique for the treatment of clubfoot recurrence in adolescent patients]. / Minimalinvasiver Tibialis-anterior-Sehnentransfer in Shuttle-Technik zur Behandlung des Klumpfußrezidivs im Wachstumsalter.

OBJECTIVE: Tibialis anterior transfer in shuttle technique using the tunnelator is an atraumatic surgical technique without injuring the extensor retinaculum. The technique allows for postoperative treatment with pain-adapted full weight-bearing for 6 weeks in a lower leg cast which is simplified compared to the current literature. INDICATIONS: Passive, correctable clubfoot recurrences in the event of muscular imbalance (overbalanced anterior tibial muscle). CONTRAINDICATIONS: Structural movement restrictions of the foot, muscular insufficiency of the anterior tibial muscle, infection or cancerous lesions in the surgical site. SURGICAL TECHNIQUE: Loosen the tibialis anterior muscle at the base of the first metatarsal. Guide the tendon proximally out of the extensor retinaculum, then shuttle the tendon below the retinaculum with the help of the "tunnelator" and transosseous fixation at the lateral cuneiform. POSTOPERATIVE MANAGEMENT: Pain-adapted full weight-bearing in a lower leg walking cast for 6 weeks postoperatively. RESULTS: In the course of a retrospective study, the above-mentioned surgical procedure was carried out in 20 patients (total n = 26 surgeries) between 2013 and 2019. After a follow-up of 12 months, complete correction of the clubfoot relapse was found in 88.5% of cases. There were no general or specific surgical complications.

The psychological burden of a two-stage exchange of infected total hip and knee arthroplasties.

Infection is one of the most challenging complications after total joint arthroplasties affecting up to 30,000 patients in the US per year. This study investigates the psycho-social burden induced by the two-stage intervention in infected hip or knee replacements. All patients were treated with a two-stage exchange and were assessed at three different timepoints regarding their psychological conditions. Our findings suggest that psychological sequelae after treatment of periprosthetic joint infection are clearly underestimated in the literature and psychological correlates and side effects should be further highlighted during the training process of young surgeons.

[Extension osteotomy of the lateral distal femur using the contralateral TomoFix® plate]. / Laterale distale femorale Extensionsosteotomie mit der kontralateralen TomoFix®-Platte.

OBJECTIVE: Supracondylar distal femoral osteotomy. Fixation with the contralateral TomoFix® (Fa. DePuy Synthes, Oberdorf, Switzerland) lateral distal femur plate. Use of the laterally reversed plate to improve the reconstruction of the sagittal anatomical axis of the leg. INDICATIONS: To correct knee flexion contractures with a deficiency of extension >20° at the age of 10 years. CONTRAINDICATIONS: Surgical site infections or tumors. SURGICAL TECHNIQUE: Ventral closed wedge osteotomy of the distal femur. Implantation of the locking compression TomoFix® lateral distal femur plate. POSTOPERATIVE MANAGEMENT: Full weight bearing. RESULTS: In all, 16 distal femoral osteotomies were performed in 9 patients. All patients had knee flexion contraction due to neurological disease. Patients with cerebral palsy showed a better GMFCS (gross motor function classification scale) level after surgery. Hardware was removed after 11.5 months (range: 9-18 months).

A Feasibility Pilot Study on the Use of Telemedicine for the Examination of the Knee Joint. / Eine Pilotuntersuchung zur Machbarkeit der Videosprechstunde bei muskuloskelettalen Beschwerden des Kniegelenks.

BACKGROUND: In times of a pandemic threat, such as COVID-19, and the need for reduced direct doctor-patient contact, internet-based telemedicine has attracted more and more attention as a surrogate service. Suspending the diagnosis and treatment of non-virus related diseases for longer periods of time is not a viable option since this would only exacerbate problems on the patient and national level. The need for alternative treatment modalities increased rather quickly. So far, telemedical applications have mainly focused on teleradiological diagnosis, follow-up and monitoring of psychiatric and internal diseases, as well as geriatric patient care. As far as these authors are aware, orthopaedic physical examination of the knee joint, including trauma work-up, has not been the subject of any studies to date. This feasibility study explores how video consultation can be designed and implemented in the context of history taking and physical examination in knee joint complaints. MATERIAL AND METHOD: 21 patient actors (PA) with simulated complaints of the knee joint were examined individually for each diagnosis, first via video consultation and then directly by a specialist (SP). One PA group has a medical background, the other was made up of laypersons. The time was measured for both types of consultation. The physician documented the detected symptoms, the quality of implementation of the self-examination steps, and the derived diagnosis on an assessment form. After completion of both consultation sessions, the PAs were handed a questionnaire on the respective examination modality. RESULTS: With the video consultation the examination lasted 8.63 (± 2.5) minutes on average and with the regular consultation in person 5.63 (± 1.7) minutes (p < 0.001). For the group with medical background the examination lasted 7.67 (± 1.4) minutes on average, while for the lay group the video consultation took 9.7 (± 3.1) minutes (p = 0.049). With increased age, the video consultation was prolonged (p = 0.032; r = 0.47). The mean value for self-examination of leg axis, gait pattern and degrees of freedom was 9.32 (± 0.4) of 10 points. The following functional tests resulted in lower mean values (points): Payr 7.2 (± 2.3), Merke 5.9 (± 2.8), no-touch Lachmann 6.4 (± 2.7), gravity sign-recurvatum 6.7 (± 2.4). The mean grade by the PAs for the feasibility of self-examination was 2.43 (± 0.98) out of 5 points. CONCLUSION: The video consultation for musculoskeletal complaints of the knee joint allows exploratory remote examination and helps to minimise the number of patients in hospitals and practices. It takes longer for the physician to perform and does not permit functional testing for ligament injuries of the knee joint. In its present form, telemedical examination is not able to fully replace personal consultation.

Treatment of partial rotator cuff lesions is associated with a higher frequency of post-operative shoulder stiffness. A prospective investigation on the role of surgery-related risk factors for this complication.

PURPOSE: Post-operative shoulder stiffness (SS) is a common complication after arthroscopic rotator cuff (RC) repair. The aim of this prospective study is to evaluate the role of surgical risk factors in the development of this complication, with special focus on the characteristics of the RC tears. METHODS: Two-hundred and twenty patients who underwent arthroscopic RC repair for degenerative posterosuperior RC tears were included. Surgery-related risk factors for development of post-operative SS belonging to the following five categories were documented and analyzed: previous surgery, RC tear characteristics, hardware and repair type, concomitant procedures, time and duration of surgery. The incidence of post-operative SS was evaluated according to the criteria described by Brislin and colleagues. RESULTS: The incidence of post-operative SS was 8.64%. The treatment of partial lesions by tear completion and repair technique was significantly associated with development of post-operative SS (p = 0.0083, pc = 0.04). A multivariate analysis revealed that treatment of partial lesions in patients younger than 60 years was associated to a higher risk of developing post-operative SS (p = 0.007). Previously known pre-operative risk factors such as female sex and younger age were confirmed. No other significant associations were documented. CONCLUSION: The treatment of partial lesions of the RC may lead to a higher risk of post-operative SS than the treatment of complete lesions, in particular in patients younger than 60 years. Possible explanations of this finding are the increased release of pro-inflammatory cytokines caused by the additional surgical trauma needed to complete the lesion and the different pain perception of the subgroup of patients who require surgical treatment already for partial tears. EVIDENCE: A higher risk of post-operative SS should be expected after tear completion and repair of partial lesions, especially in young patients. Appropriate pre-operative counseling and post-operative rehabilitation should be considered when approaching this subgroup of RC tears. LEVEL OF EVIDENCE: Prognostic study, level II.

sCD28, sCD80, sCTLA-4, and sBTLA Are Promising Markers in Diagnostic and Therapeutic Approaches for Aseptic Loosening and Periprosthetic Joint Infection.

Aseptic prosthetic loosening and periprosthetic joint infections (PJI) are among the most frequent complications after total knee/hip joint arthroplasty (TJA). Current research efforts focus on understanding the involvement of the immune system in these frequent complications. Different immune cell types have already been implicated in aseptic prosthetic loosening and PJI. The aim of this study was to systematically analyze aspirates from knee and hip joints, evaluating the qualitative and quantitative composition of soluble immunoregulatory markers, with a focus on co-inhibitory and co-stimulatory markers. It has been shown that these molecules play important roles in immune regulation in cancer and chronic infectious diseases, but they have not been investigated in the context of joint replacement. For this purpose, aspirates from control joints (i.e., native joints without implanted prostheses), joints with TJA (no signs of infection or aseptic loosening), joints with aseptic implant failure (AIF; i.e., aseptic loosening), and joints with PJI were collected. Fourteen soluble immunoregulatory markers were assessed using bead-based multiplex assays. In this study, it could be shown that the concentrations of the analyzed immunoregulatory molecules vary between control, TJA, AIF, and PJI joints. Comparing TJA patients to CO patients, sCD80 was significantly elevated. The marker sBTLA was significantly elevated in AIF joints compared to TJA joints. In addition, a significant difference for eight markers could be shown when comparing the AIF and CO groups (sCD27, sCTLA-4, sCD137, sCD80, sCD28, sTIM-3, sPD-1, sBTLA). A significant difference was also reached for nine soluble markers when the PJI and CO groups were compared (sLAG-3, sCTLA-4, sCD27, sCD80, sCD28, sTIM-3, sPD-1, IDO, sBTLA). In summary, the analyzed immunoregulatory markers could be useful for diagnostic purposes as well as to develop new therapeutic approaches for AIF and PJI.

Synovial Complement Factors in Patients with Periprosthetic Joint Infection after Undergoing Revision Arthroplasty of the Hip or Knee Joint.

The role and diagnostic value of the synovial complement system in patients with low-grade periprosthetic joint infection (PJI) are unclear. We sought to evaluate, for the first time, the usefulness of synovial complement factors in these patients by measuring the individual synovial fluid levels of complement factors (C1q, C3b/iC3b, C4b, C5, C5a, C9, factor B, factor D, factor H, factor I, properdin, and mannose-binding lectin [MBL]). The patients (n = 74) were classified into septic (n = 28) and aseptic (n = 46). Receiver-operator characteristic curves and a multiple regression model to determine the feasibility of a combination of the tested cytokines to determine the infection status were calculated. The synovial fluid levels of C1q, C3b/C3i, C4b, C5, C5a, MBL, and properdin were significantly elevated in the PJI group. The best sensitivity and specificity was found for C1q. The multiple regression models revealed that the combination of C1q, C3b/C3i, C4b, C5, C5a, and MBL was associated with the best sensitivity (83.3%) and specificity (79.2%) for a cutoff value of 0.62 (likelihood ratio: 4.0; area under the curve: 0.853). Nevertheless, only a combined model showed acceptable results. The expression patterns of the complement factors suggested that PJI activates all three pathways of the complement system.

Difficult-to-treat pathogens significantly reduce infection resolution in periprosthetic joint infections.

Periprosthetic joint infection (PJI) is a feared complication after arthroplasty. Our hypothesis was that PJI caused by difficult-to-treat (DTT) pathogens has a worse outcome compared with non-DTT PJI. Routine clinical data on 77 consecutive patients with confirmed PJI treated with 2-stage exchange arthroplasty were placed in DTT and non-DTT PJI groups and analyzed. The main outcome variable was that the patient was definitively free of infection after 2 years. We found definitive infection resolution in 31 patients in the DTT group (68.9%) and 28 patients (87.5%) in the non-DTT group (P < 0.05). The necessity for revision surgery until assumed resolution of infection was significantly more frequent in the DTT group with 4.72 ± 3.03 operations versus 2.41 ± 3.02 operations in the non-DTT group (P < 0.05). PJI caused by DTT bacteria is associated with significantly higher numbers of revision operations and significantly inferior definitive infection resolution.

Acetabular defects in revision hip arthroplasty: a therapy-oriented classification.

INTRODUCTION: The treatment of severe acetabular bone loss remains a difficult challenge. No classification system is available that combines intuitive use, structured design and offers a therapeutic recommendation according to the current literature and modern state of the art treatment options. The goal of this study is to introduce an intuitive, reproducible and reliable guideline for the evaluation and treatment of acetabular defects. METHODS: The proposed Acetabular Defect Classification (ADC) is based on the integrity of the acetabular rim and supporting structures. It consists of 4 main types of defects ascending in severity and subdivisions narrowing down-defect location. Type 1 presents an intact acetabular rim, type 2 includes a noncontained defect of the acetabular rim ≤ 10 mm, in type 3 the rim defect exceeds 10 mm and type 4 includes different kinds of pelvic discontinuity. A collective of 207 preoperative radiographs were graded according to ADC and correlated with intraoperative findings. Additionally, a randomized sample of 80 patients was graded according to ADC by 5 observers to account for inter- and intra-rater reliability. RESULTS: We evaluated the agreement of preoperative, radiographic grading and intraoperative findings presenting with a k value of 0.74. Interobserver agreement presented with a k value of 0.62 and intraobserver at a k value of 0.78. CONCLUSION: The ADC offers an intuitive, reliable and reproducible classification system. It guides the surgeon pre- and intraoperatively through a complex field of practice.

Postoperative Medical Complications and Intermediate Care Unit/Intensive Care Unit Admission in Joint Replacement Surgery: A Prospective Risk Model.

BACKGROUND: Postoperative complications are the main consumers of technical, medical, and human resources. Especially in the field of elective joint replacement surgery, a specialized, easy-to-obtain, and cost-efficient preoperative stratification and risk-estimation model is missing. METHODS: With preoperatively surveyed patient parameters, we identified the most relevant parameters to predict postoperative medical complications. We devised a prospective risk model, measuring the individual probability for intermediate care unit (IMC) or intensive care unit (ICU) admission. The study includes all patients (n = 649) treated with primary or revision total knee arthroplasty in our clinic from 2008 to 2012. RESULTS: The association between general comorbidity scores and mortality risk is well known. Among different comorbidity scores, the Charlson Comorbidity Index is not only relevant for overall postoperative complications (odds ratios [OR] = 2.20) but also predictive of specific complications such as the postoperative need for blood transfusion (OR = 1.94) and unexpected adverse events (OR = 1.74). Considering adverse events, c-reactive protein and leukocyte levels are also highly relevant. Upon predicting a necessary postoperative transfer to an IMC or ICU, the preoperative hemoglobin level, the Charlson Comorbidity Index, and the Index of Coexistent Disease stood out. The latter indicates an increased rate for an IMC/ICU stay by 341% per point. Condensing the most influential predictors, the probability for postoperative IMC/ICU transfer can be calculated for each individual patient. Using the routinely assessed patient's variables, no steadier prediction is possible. CONCLUSION: The introduced risk-estimation model offers a specialized preoperative resource-stratification method in knee joint replacement surgery. It condenses the most influential, individual risk factors to avoid clinical test redundancy and improve resource efficiency and presurgical care planning. A prospective follow-up study could help validating the risk model in clinical routine.

Medial patellofemoral ligament reconstruction fails to correct mild patella alta in cases of patellofemoral instability-a case-control study.

PURPOSE: Medial patellofemoral ligament reconstruction (MPFL-R) is the gold standard in patella soft tissue surgery for patellofemoral instability. Although claimed, recent reports indicate that MPFL-R may fail to distalize the patella in mild cases of patella alta. The present study is a retrospective case-control study to compare radiographic patella height between MPFL-R and historical Insall's proximal realignment (IPR) pre- and post-operatively with respect to distalization and assess redislocation rates at a mid-term follow-up. METHODS: Sixty-four patients were age/sex matched (1:1), yielding 32 patients for group 1 MPFL-R (cases) and 32 patients for group 2 IPR (controls). Insall-Salvati, Blackburne-Peel and Caton-Deschamps indices were analyzed for differences pre- and post-operatively. An additional inter-rater reliability analysis was performed by means of intra-class correlation (ICC). Redislocation rates were considered as treatment failures in this study. RESULTS: ICC was excellent for all three patella indices. MPFL-R failed to show significant differences if compared to IPR with respect to distalization in mild stages of patella alta. Moreover, redislocation rates significantly favored MPFL-R (3.1%) over IPR (12.5%; p < 0.0001). CONCLUSIONS: MPFL-R has become a popular option to restore native patellofemoral biomechanics after ligament rupture. However, the procedure's potential to correct concomitant patella alta should not be overestimated and indications considered carefully.

Systematic Reviews and Meta-analyses. / Systematische Reviews und Metaanalysen.

The rising number of medical publications makes it difficult to keep up-to-date on scientific knowledge. In recent years, reviews in the form of narrative or systematic publications and meta-analyses have increased. These can only be interpreted and evaluated if the reader understands the techniques used. This review article describes the differences between narrative and systematic reviews, together with the characteristics of meta-analysis, and discusses their interpretation. The concept of systematic reviews and meta-analysis includes a systematic literature search and summary, together with an appraisal of the quality of the publications. Systematic reviews are often considered to be original studies due to their structure and ability to reduce bias.

Relative radiographic bone density measurement in revision hip arthroplasty and its correlation with qualitative subjective assessment by experienced surgeons.

BACKGROUND: Conventional radiography (CR) is the imaging method of choice in monitoring bone remodelling and other stability parameters after total hip arthroplasty (THA). Quantitative roentgen- or computed-tomography-based methods to determine bone density are prone to metal artifacts and often very costly, which is why they are not used as standard in a clinical setting. Since subjective assessment of bone remodelling in CR also has a certain susceptibility to errors, semi-quantitative methods have been developed to help approximate periprosthetic bone density development via CR to open up an additional tool for documentation of radiographic THA follow-up. OBJECTIVE: Proof-of-principle of a newly designed imaging-software-aided method to measure relative bone density around the femoral stem in a series of conventional radiographs following THA. METHODS: Eighty-six patients with hip modular tapered, fluted titanium stems were selected from the clinical database and series of baseline and postoperative follow-up radiographs were obtained after 24 and 48 weeks. Relative bone densities were measured per Gruen zones G1-7 with the use of an open-source image analysis package (ImageJ) by means of greyscale histograms. In addition, subjective evaluation of selected cases was performed by three independent, blinded orthopedic surgeons. Besides descriptive and nonparametric analyses, intra-class correlation (ICC) was performed and objective and subjective results were compared by linear regression analysis. RESULTS: Two individual cases are presented as a proof-of-principle. Increase or decrease of bone density could be measured correctly over time in each case. In a collective analysis there were no significant differences in mean relative bone densities between groups after 24 and 48 weeks, although a positive tendency was visible towards increased bone formation over time. Individual analyses by Gruen zones revealed that some zones, namely the proximal ones (e.g. G6), exhibit a broader scattering than others over time. This could be explained by the design of the evaluated tapered revision stem that achieves distal fixation and allows for proximal micromotion. Correlation analysis with subjective ratings (inter-rater reliability ICC = 0.71) showed a positive correlation with objective results, suggesting a feasibility of the method for clinical use. CONCLUSIONS: In conclusion the presented method is an easy and accessible tool to quantify relative bone density changes during THA follow-up. It shows a positive correlation to established subjective assessment of bone remodelling and may therefore serve as a quantitative supplement in clinical documentation.

Pneumoscrotum after colorectal surgery: A case report.

Pneumoscrotum is a very rare complication. Currently, very little evidence-based medicine exists on treatment guidelines. We think a prophylactic antibiotic course and a 48 hours in hospital observation are justified in these rare cases.

Comparison of two-stage revision arthroplasty and intramedullary arthrodesis in patients with failed infected knee arthroplasty.

BACKGROUND: Failed total knee arthroplasty (TKA) with significant bone loss and compromised soft-tissues is challenging and the final results are often inferior to patient's expectation. The objective of this study was to present a comparison of outcomes in patients with failed infected TKA treated with two-stage revision TKA or knee arthrodesis and to assess clinical and functional results, implant survival and infection recurrence. The hypothesis was that an arthrodesis may result in beneficial effects on patients' outcome. METHODS: Clinical data of 81 patients with periprosthetic joint infection (PJI) of the knee joint were collected and analyzed retrospectively. Between 2008 and 2014, a total of 36 patients had been treated within a two-stage exchange procedure and reimplantation of a modular intramedullary arthodesis nail and 45 patients with revision TKA. Patients were treated according to the same structured treatment algorithm. Clinical and functional evaluation was performed using the Oxford knee score (OKS) and the visual analogue scale (VAS). RESULTS: The mean follow-up was 32.9 ± 14.0 months. The rate of definitely free of infection at last follow-up in the arthrodesis group was 32 of 36 (88.9%) and 36 of 45 (80.0%) in the revision TKA group (p = 0.272). Mean VAS for pain in the arthrodesis group was 3.1 ± 1.4 compared to 3.2 ± 1.6 in the revision TKA group (p = 0.636). The OKS in the arthrodesis group was 38.7 ± 8.9 and 36.5 ± 8.9 (p = 0.246) in patients with revision TKA. Rate of revisions in the revision-TKA group was 2.8 ± 3.7 compared to 1.2 ± 2.4 in the arthrodesis group (p = 0.021). CONCLUSION: Treatment of PJI needs a distinct therapy with possible fallback strategies in case of failure. A knee arthrodesis is a limb salvage procedure that showed no significant benefits on the considered outcome factors compared to revision TKA but is associated with significantly lower revision rate. After exhausted treatment modalities, a knee arthrodesis should be considered as an option in selected patients. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction.

In orthopedic patients, foreign body-associated infections, especially periprosthetic joint infections (PJIs), are a devastating complication of arthroplasty. Infection requires complex treatment, may result in long hospitalization and causes considerable costs. Multiple surgical revisions can be necessary in these patients, with a loss in function as well as in quality of life. The routine preoperative diagnostics include blood examination for C-reactive protein (CRP) and other biomarkers, as well as joint aspirate analysis for cell count, differentiation, and culture. Intraoperative specimens for histology and microbiology are also standard procedure. The microbiological examination of removed implants with sonication, in combination with the implementation of molecular biology techniques in microbiology, represent two novel techniques currently employed to enhance the differential diagnostics of PJI. We present here the step-wise procedure of analyzing joint aspirate and sonication fluid, using a cartridge-based multiplex polymerase chain reaction (PCR) system. Results were matched against conventional cultures and consensus criteria for PJI. Conventional microbiological cultures from tissue biopsies, joint aspirate and sonication fluid showed a sensitivity of 66.7%, 66.7%, and 88.9%, respectively, and a specificity of 82.3%, 54.6%, and 61.5%, respectively. The PCR diagnostic of the sonication fluid and the joint fluid showed a sensitivity of 50.0% and 55.6%, respectively, and both a specificity of 100.0%. Both PCR diagnostics combined had a sensitivity of 66.7% and a specificity of 100.0%. The multiplex PCR therefore presents a rapid diagnostic tool with moderate sensitivity but high specificity in diagnosing PJI.

Two-stage knee arthrodesis with a modular intramedullary nail due to septic failure of revision total knee arthroplasty with extensor mechanism deficiency.

BACKGROUND: Periprosthetic joint infection is a serious complication and reconstruction after failed revision total knee arthroplasty with significant bone loss and compromised soft-tissues can be challenging. Objective of this study was to assess clinical and functional results, implant survival and infection recurrence rates in patients treated with two-stage arthrodesis after failed revision TKA with extensor mechanism deficiencies due to PJI, and to identify the factors that affect outcomes after surgery. METHODS: Thirty seven patients with PJI treated within a two-stage exchange and reimplantation of an arthrodesis nail between 2008 and 2014 were included. Systemic and local risk factors were graded preoperatively according to McPherson et al. All patients were treated according to a structured treatment algorithm. Clinical and functional evaluation was performed using the Oxford Knee Score and the Visual Analogue Scale. RESULTS: Thirty two of 37 patients (86.5%) were graded as free of infection. Five patients (13.5%) had recurrent infection after arthrodesis with the need of revision surgery. Mean leg-length discrepancy was 2.2cm. The mean VAS for pain was three, the mean Oxford Knee Score was 38±9. Total implant survival at a 74month follow-up was 74.3% (95% CI: 45.4 to 91.1%), as determined by Kaplan-Meier survival curves. Local McPherson Score, as well as number of revisions was found to be of significant influence to the survival rate. CONCLUSIONS: Septic failure of revision knee arthroplasty can be effectively treated with two-stage arthrodesis using a modular intramedullary nail, providing a stable and painless limb with satisfactory functional results and acceptable infection eradication rates.