Is Prematurity a Protective Factor Against Developmental Dysplasia of the Hip? A Retrospective Analysis of 660 Newborns.

PURPOSE: In Middle Europe developmental dysplasia of the hip (DDH) has an incidence of up to 5.9 %. The rate of congenital hip dislocation as the worst complication of a growth disorder of the hip is between 1.5 % and 2.5 %. Among known risk factors of DDH are breech position, multiples, foot deformities and family history. The aim of this retrospective study was to investigate prematurity as a risk factor for developmental dysplasia of the hip (DDH). MATERIALS AND METHODS: The hips of 283 infants who were born before the 38th week of gestation or earlier, and those of 377 infants who were born after the 37th week of gestation, none of whom had other risk factors for DDH, were compared using the ultrasound technique according to Graf et al., within the first week after birth. Both hips of all infants were included in the study. RESULTS: Surprisingly, the difference in alpha angles between the two groups was statistically extremely significant, favoring the preterm infants. Moreover, we found a physiological curve of alpha angle development with a peak after the 31st week of gestation. The incidence of pathological dysplasia was not significantly different in the two groups. CONCLUSION: Our results suggest that prematurity is not a predisposing factor for DDH, but rather is protective for hip development.

Biomechanical evaluation of temporary epiphysiodesis at the femoral epiphysis using established devices from clinical practice.

The aim of this study is to compare biomechanical features of different devices used in clinical routine for temporary epiphysiodesis (eight-Plate® and FlexTackTM). The tested implants were divided into four different groups (eight-Plate® vs. FlexTackTM for lateral and anterior implantation) á 10 samples for testing implanted eight-Plate® vs. FlexTackTM in fresh frozen pig femora for maximum load forces (Fmax) and axial physis distance until implant failure (lmax). A servo hydraulic testing machine (858 Mini Bionix 2) was used to exert and measure reproducible forces. Statistical analyses tested for normal distribution and significant (p < 0.05) differences in primary outcome parameters. There were no significant differences between the eight-Plate® lateral group and the FlexTackTM lateral group for neither Fmax (p = 0.46) nor lmax (p = 0.65). There was a significant higher Fmax (p < 0.001) and lmax (p = 0.001) measured in the eight-Plate® group compared to the FlexTackTM group when implanted anteriorly. In anterior temporary ephiphysiodesis, eight-Plate® demonstrated superior biomechanical stability. At this stage of research, there is no clear advantage of either implant and the choice remains within the individual preference of the surgeon.

Outcome evaluation of new calcium titanate schanz-screws for external fixators. First clinical results and cadaver studies.

OBJECTIVE: External fixators are important for correcting length discrepancies and axis deformities in pediatric or trauma orthopedic surgery. Pin loosening is a common pitfall during therapy that can lead to pain, infection, and necessary revisions. This study aims to present clinical data using calcium titanate (CaTiO3) Schanz screws and to measure the fixation strength. PATIENTS AND METHODS: 22 titanate screws were used for external fixators in 4 pediatric patients. Therapy was initiated to lengthen or correct axial deformities after congenital abnormalities. The maximum tightening torque was measured during implantation, and the loosening torque was measured during explantation. In addition, screws of the same type were used in a cadaver study and compared with stainless steel and hydroxyapatite-coated screws. 12 screws of each type were inserted in four tibias, and the loosening and tightening torque was documented. RESULTS: The fixation index in the in vivo measurement showed a significant increase between screw insertion and extraction in three of the four patients. The pins were in situ for 91 to 150 days, and the torque increased significantly (P = 0.0004) from insertion to extraction. The cadaveric study showed lower extraction torques than insertion torques, as expected in this setting. The calculated fixation index was significantly higher in the CaTiO3 group than in the other groups (P = 0.0208 vs. HA and P < 0.0001 vs. steel) and in the HA group vs. plain steel group (P = 0.0448). CONCLUSION: The calcium titanate screws showed favorable fixation strength compared to HA and stainless steel screws and should be considered in long-term therapy of external fixation.

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.

Pre-operative intra-articular deep tissue sampling with novel retrograde forceps improves the diagnostics in periprosthetic joint infection.

BACKGROUND: Histopathological tissue analysis is a key parameter within the diagnostic algorithm for suspected periprosthetic joint infections (PJIs), conventionally acquired in open surgery. In 2014, Hügle and co-workers introduced novel retrograde forceps for retrograde synovial biopsy with simultaneous fluid aspiration of the knee joint. We hypothesised that tissue samples acquired by retrograde synovial biopsy are equal to intra-operatively acquired deep representative tissue samples regarding bacterial detection and differentiation of periprosthetic infectious membranes. METHOD: Thirty patients (male n = 15, 50%; female n = 15, 50%) with 30 suspected PJIs in painful total hip arthroplasties (THAs) were included in this prospective, controlled, non-blinded trial. The results were compared with intra-operatively obtained representative deep tissue samples. RESULTS: In summary, 27 out of 30 patients were diagnosed correctly as infected (17/17) or non-infected (10/13). The sensitivity to predict a PJI using the Retroforce® sampling forceps in addition to standard diagnostics was 85%, the specificity 100%. CONCLUSIONS: Retrograde synovial biopsy is a new and rapid diagnostic procedure under local anaesthesia in patients with painful THAs with similar histological results compared to deep tissue sampling.

Polymicrobial infections reduce the cure rate in prosthetic joint infections: outcome analysis with two-stage exchange and follow-up ≥two years.

PURPOSE: Prosthetic joint infections (PJI) are a serious and challenging complication after total joint arthroplasty. According to the literature, most PJI are monomicrobial infections caused by gram-positive cocci. The number of polymicrobial PJI might be underrepresented in the literature and only limited data are available regarding the outcome of polymicrobial PJI. Our hypothesis was that polymicrobial PJI are associated with a reduced cure rate compared with monomicrobial PJI. METHODS: Routine clinical data were collected and analysed retrospectively as anonymised, aggregated data. A total of 77 consecutive patients with 77 confirmed PJI and proven infectious organism of the hip and knee joint treated within a two-stage exchange concept and a follow-up ≥ two years were investigated. Detection of the infectious organism was based on multiple microbiological cultures taken intra-operatively. Superficial wound swabs or swabs from sinus tracts were not taken into account. Data were grouped into polymicrobial and monomicrobial PJI. The main outcome variable was "definitively free of infection after two years" as published. Second, we considered several variables as potential confounders or as risk factors. RESULTS: A total of 42 men and 35 women with 46 infected total hip arthroplasties and 31 infected total knee arthroplasties were evaluated. In 37 (46.6 %) of our 77 patients a polymicrobial PJI could be detected. We found a significant association between polymicrobial PJI and the outcome parameter definitively free of infection after two years with an odds ratio (OR) of 0.3 [95 % confidence interval (CI) 0.1-1.0]. The rate of patients graded as definitively free of infection after two years was 67.6 % for polymicrobial infections vs. 87.5 % for monomicrobial infections. The American Society of Anesthesiologists (ASA) score (OR 0.4, 95 % CI 0.2-1.0, p = 0.062) was identified as a borderline significant covariable. CONCLUSIONS: Our data suggest that polymicrobial PJI might be underrepresented in the current literature. Additionally, the presence of multiple infectious organisms is associated with a reduced rate after two years with 67.6 vs 87.5 % for monomicrobial infections. Special attention and extra care should be considered for these patients.

Outcome Predictors in Prosthetic Joint Infections--Validation of a risk stratification score for Prosthetic Joint Infections in 120 cases.

Prosthetic joint infections are a major challenge in total joint arthroplasty, especially in times of accumulating drug resistancies. Even though predictive risk classifications are a widely accepted tool to define a suitable treatment protocol a classification is still missing considering the difficulty in treating the -causative pathogen antibiotically. In this study, we present and evaluate a new predictive risk stratification for prosthetic joint infections in 120 cases, treated with a two-stage exchange. Treatment outcomes in 120 patients with proven prosthetic joint infections in hip and knee prostheses were regressed on time of infection, systemic risk factors, local risk factors and the difficulty in treating the causing pathogen. The main outcome variable was "definitely free of infection" after two years as published. Age, gender, and BMI were included as covariables and analyzed in a logistic regression model. 66 male and 54 female patients, with a mean age at surgery of 68.3 years±12.0 and a mean BMI of 26.05±6.21 were included in our survey and followed for 29.0±11.3 months. We found a significant association (p<0.001) between our score and the outcome parameters evaluated. Age, gender and BMI did not show a significant association with the outcome. These results show that our score is an independent and reliable predictor for the cure rate in prosthetic joint infections in hip and knee prostheses treated within a two-stage exchange protocol. Our score illustrates, that there is a statistically significant, sizable decrease in cure rate with an increase in score. In patients with prosthetic joint infections the validation of a risk score may help to identify patients with local and systemic risk factors or with infectious organisms identified as "difficult to treat" prior to the treatment or the decision about the treatment concept. Thus, appropriate extra care should be considered and provided.

Description of Standardized Planes and Angles for Percutaneous Supra-acetabular Screw Placement.

BACKGROUND: Percutaneous screw fixation for pelvic fractures has become a minimally invasive alternative to an open operation. The complex anatomy of the pelvis renders this procedure challenging. The objective of this study was to assess standardized angles and dimensions of safety zones within a 3 D computed tomography model for optimal supra-acetabular screw placement. METHODS: Computed tomography scans of 107 patients that suffered major trauma without showing any bone injury of the pelvis were collected. Using a software-based analysis, raw computed tomography data were transformed into 3 D models to set standardized landmarks and determine the possible insertion corridor. RESULTS: Screws not exceeding a length of 97 mm in females and 106.4 mm in males were, in 95% of the evaluated cases, insertable without cortical bone penetration. The safety zone was 6.6 mm for females and 7.9 mm for males. Screws not exceeding these diameters were safely insertable in 95% of the cases. For the midsagittal plane, the angle was 36.4 ± 5.1 on the left and 34.7 ± 2.9 on the right (p = 0.008). For the anterior pelvic plane, the angle was 31.3 ± 4.5° on the left and 34.0 ± 4.8° on the right (p = 0.008). CONCLUSIONS: Percutaneous fixation using supra-acetabular screws is a promising method to treat simple supra-acetabular fractures. These results may improve its safe utilization and could facilitate its broader clinical application.

[Surgical treatment of congenital muscular torticollis]. / Operative Behandlung des Torticollis muscularis congenitus.

OBJECTIVE: Surgical treatment of congenital muscular torticollis with tripolar release of the sternocleidomastoid muscle, followed by modified postoperative treatment with a special orthosis. INDICATIONS: Muscular torticollis due to contracture of the sternocleidomastoid muscle; failure of conservative therapy. CONTRAINDICATIONS: Torticollis due to bony anomaly or other muscular contractures. SURGICAL TECHNIQUE: Tenotomy of the sternocleidomastoid muscle occipitally and resection of at least 1 cm of the tendon at the sternal and clavicular origin. POSTOPERATIVE MANAGEMENT: Orthosis must be worn for 6 weeks 24 h/day, then for another 6 weeks 12 h/day. RESULTS: A total of 13 patients were treated with tripolar release of the sternocleidomastoid muscle and modified postoperative management. Average follow-up time was 25.7 months. One patient presented with recurrence after 3 years. No intra- or postoperative complications were observed.

It is (not) always on Friday: inter-hospital patient transfers in orthopedic and trauma surgery.

BACKGROUND: While inter-hospital transfers for patients who have suffered major trauma have been well investigated, patient flows for other injured patients, or cases with orthopedic complications, are rarely described. This study aims to analyze the affected collective and to show possible reasons, patterns, and pitfalls to optimize the process in future. MATERIALS AND METHODS: In a prospective cohort study, all consecutive transfers to a Level I trauma center in Germany were documented and assessed. Patients suffering a major trauma were excluded. Data on the primary treating hospital, patient characteristics, and differences between emergency and elective surgery were analyzed. RESULTS: A total of 227 patients were included; 162 were injured, while 65 had suffered a complication after elective orthopedic surgery or had a complex orthopedic pathology. The most common diagnoses leading to transfer were pathologies of the extremities (n = 62), pathologies of the spine (n = 50), and infections (n = 18). The main reasons stated by the transferring hospitals were a lack of expertise (137 cases) and a lack of capacity (43 cases). There was a significantly higher rate of transfers due to trauma (n = 162) than for orthopedic patients (n = 65), p < 0.0001. CONCLUSION: There is currently no structured procedure or algorithm for transferring patients in orthopedics and trauma surgery.

[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.

[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).

Proximal Femoral Osteotomies in the Adolescence: Indications and Treatment Strategies. / Proximale Femurosteotomien im Wachstumsalter: Wann indiziert? Wie operieren?

Proximal femoral osteotomies are common surgical interventions to treat hip deformities in pediatric orthopedics. The aim of proximal femoral osteotomies is to optimise hip containment by using varus or valgus osteotomy, flexion or extension osteotomy with shortening, lengthening or derotation of the femoral neck. Furthermore improved muscular dysbalance by enhancing the femoral offset, extension of the range of motion and pain reduction are important surgical intentions. In the long term, a proximal femoral osteotomy is meant to minimize the probability of an early osteoarthritis of the hip. In the current literature many different types of proximal femoral osteotomies are described. They can be divided concerning their anatomical localization into subcapital, base of the femoral neck, intertrochanteric and subtrochanteric osteotomies. A profound knowledge about the deformity and the anatomical situation is essential to choose the appropriate osteotomy. The aim of this review is to show the different ways of proximal femoral osteotomies and their indications after having done a selective literature research. Furthermore over the last years the osteosynthesis materials have changed from blade plates (non-locking) to locking compression plates which allow an early re-mobilization without hip spica casts.

Comparison of the Subjective Elbow Value with the DASH, MEPS und Morrey Score after Olecranon Fractures. / Vergleich der subjektiven Ellenbogenfunktion mit dem DASH-Score, MEPS und Morrey-Score nach operativer Versorgung von Olekranonfrakturen.

BACKGROUND: Olecranon fractures are common injuries that can occur in patients of any age. To assess the postoperative outcome, multiple scoring systems like the DASH, MEPS und Morrey Score have been described. The goal of this paper is to compare the subjective elbow value (SEV) to these commonly used scoring systems. We hypothesized that the SEV would have a high correlation and practicability for the evaluation of elbow function after isolated olecranon injury. PATIENTS AND METHODS: Clinical data of 40 patients were collected and retrospectively analysed. All patients suffered an isolated olecranon fracture and were surgically treated by tension band wiring or plate fixation. In the follow-up examinations the Mayo Score, DASH Score, Morrey Score and SEV were measured for correlation purposes. RESULTS: The mean follow-up time was 70.5 ± 45.6 months. The median DASH Score was 9.9 (4.1 - 20.4) and 100 (85 - 100) for the MEPS. The median Morrey Score was 98 (92 - 100). The median SEV was 90% (80 - 95%). The Pearson correlation between the DASH and SEV was -0.85 and 0.80 between the MEPS and the SEV. CONCLUSIONS: The SEV shows a high correlation to the most commonly used scoring systems for outcome evaluation after elbow injury. It is easy to use and can be seen as a valuable tool to assess patients after olecranon fractures.

What Are the Indications for Aspiration of a Possibly Infected Total Ankle Arthroplasty (TAA)?

RECOMMENDATION: Whenever a periprosthetic joint infection (PJI) of a total ankle arthroplasty (TAA) is clinically possible or suspected, especially when elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) levels exist, and in correspondence to the literature on PJI in total hip and knee arthroplasties, joint aspiration is indicated. LEVEL OF EVIDENCE: Consensus. DELEGATE VOTE: Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus).

3-D Optics for Thoracoscopic Vertebral Body Replacement - Essential Technical Progress or Just Nice to Have? / Die dreidimensionale Optik für den thorakoskopischen ventralen Wirbelkörperersatz ­ notwendiger Fortschritt oder nur "nice to have"?

BACKGROUND: Three-dimensional (3-D) endoscopic optics use 2 cameras to simulate the different perspectives of the right and left eye, creating the illusion of spatial depth. Optimised orientation as well as improved hand-eye coordination compared to 2-D-optics could be proven in standardised test setups (black box) and in laparoscopic use. This retrospective study examines whether these results can also be applied to thoracoscopic vertebral body replacement at the thoracolumbar junction. HYPOTHESES: 1. Ventral vertebral body replacement using 3-D-thoracoscopy results in a shorter operation time than with 2-D-thoracoscopy. 2. Perioperative blood loss is less, due to better spatial orientation (faster haemostasis) and reduced tissue laceration. MATERIAL AND METHODS: 29 patients met the inclusion criteria of this retrospective study. Between 08 - 2012 and 08 - 2017, all of these received ventral thoracoscopic vertebral replacement at the thoracolumbar junction (Th11 to L2). Patients with additional anterior procedures (e.g. anterolateral plate) were excluded. Perioperative data such as blood loss, duration of surgery and length of hospital stay were analysed. Conventional 2-D-optics were used in n = 14 patients and 3-D-optics in 15 patients. Aesculap EinsteinVision® 2.0 was used as the 3-D-optics. Statistical significance was calculated using Student's t-test. RESULTS: The most common diagnosis was a L1 fracture (n = 18, 62%). Mean OR time was 24 minutes shorter in the 3-D group (149 ± 29, 107 - 198 min) than in the 2-D group (173 ± 39, 125 - 260 min), but this difference was not significant. Total perioperative blood loss in the 3-D group was significantly lower than in the 2-D group (**p = 0.043). Proportional intraoperative blood loss in the 3-D group was also lower (mean around 115 ml), but not significantly so. Significantly lower values were found for the delivery rate of the thoracic drainage in the 3-D group (248 vs. 560 ml, *p = 0.195). Inpatient stay with the 3-D group was on average 1.5 days (d) shorter (8.7 d for the 3-D group, 10.2 d for the 2-D group) but this difference was not significant (p = 0.27). CONCLUSION: Thoracoscopic-assisted vertebral body replacement at the thoracolumbar junction is a safe and reliable surgical procedure using conventional 2-D-optics or the new 3-D-optics. Both methods allow thoracoscopic vertebral body replacement in comparable operation times but in our study the 3-D group presented with significantly lower postoperative blood loss. Due to the small number of cases and because of the retrospective design, the present study is considered to be a pilot study only.

[Obesity in Revision Total Knee Arthroplasty - a Systematic Review and Legal Assessment]. / Adipositas in der Revisionsendoprothetik des Kniegelenks ­ eine systematische Literaturübersicht und rechtliche Bewertung.

BACKGROUND: In recent years, the incidence of overweight and obesity has increased in the German population. Thus the number of obese patients treated with primary total joint arthroplasty has also increased. It is therefore predicted that the number of obese patients undergoing revision total joint arthroplasty will also increase. Nevertheless almost every manufacturer of commercially available revision arthroplasty implants states in his product safety guarantee that obesity is a relative or absolute contraindication. Data on revision total joint arthroplasty in obese patients are sparse. The aim of this systematic review is to assess the current literature on re-revision rate, infection rate, postoperative clinical outcome, and implant survival rate in obese patients undergoing revision total knee arthroplasty. Moreover, potential legal consequences and aspects are discussed which are essential for the surgeon. MATERIAL AND METHODS: We conducted a systematic review of the online databases PubMed and identified clinical studies on obesity and overweight in revision total knee arthroplasty. Study quality was assessed using levels of evidence and the modified Jadad score. We also included descriptive data on case numbers, age, gender, height, weight and follow-up time. Current legal aspects were also analysed. RESULTS/DISCUSSION: Five studies met the inclusion criteria and were included in the systematic review. The average Jadad score was 1, the average level of evidence 3. In two studies, infection and revision occured more often in obese patients. Patients with morbid obesity had a higher risk of wound revision and periprosthetic joint infections. Three studies showed that obese patients had significantly lower scores for clinical outcome measures in function and pain. The legal aspect was not discussed in any of the five studies. Overall, published data are sparse and very heterogeneous. Therefore comparing these five studies is difficult. However, the results of our review suggest that obesity in revision total knee arthroplasty may have a negative influence on reoperation rate, infection rate and postoperative functional outcome. From a legal point of view, potential weight limitations of the implants intented for use have to be part of the oral preoperative discussion. The patient's informed consent has to be received and documented prior to revision total joint arthroplasty.

RANK-ligand and osteoprotegerin as biomarkers in the differentiation between periprosthetic joint infection and aseptic prosthesis loosening.

AIM: To assess serum levels of RANK-ligand (RANKL) and osteoprotegerin (OPG) as biomarkers for periprosthetic joint infection (PJI) and compare their accuracy with standard tests. METHODS: One hundred and twenty patients presenting with a painful total knee or hip arthroplasty with indication for surgical revision were included in this prospective clinical trial. Based on standard diagnostics (joint aspirate, microbiological, and histological samples) and Musculoskeletal Infection Society consensus classification, patients were categorized into PJI, aseptic loosening, and control groups. Implant loosening was assessed radiographically and intraoperatively. Preoperative serum samples were collected and analyzed for RANKL, OPG, calcium, phosphate, alkaline phosphatase (AP), and the bone-specific subform of AP (bAP). Statistical analysis was carried out, testing for significant differences between the three groups and between stable and loose implants. RESULTS: All three groups were identical in regards to age, gender, and joint distribution. No statistically significant differences in the serum concentration of RANKL (P = 0.16) and OPG (P = 0.45) were found between aseptic loosening and PJI, with a trend towards lower RANKL concentrations and higher OPG concentrations in the PJI group. The RANKL/OPG ratio was significant for the comparison between PJI and non-PJI (P = 0.005). A ratio > 60 ruled out PJI in all cases (specificity: 100%, 95%CI: 89, 11% to 100.0%) but only 30% of non-PJI patients crossed this threshold. The positive predictive value remained poor at any cut-off. In the differentiation between stable and loose implants, none of the parameters measured (calcium, phosphate, AP, and bAP) showed a significant difference, and only AP and bAP measurements showed a tendency towards higher values in the loosened group (with P = 0.09 for AP and P = 0.19 for bAP). CONCLUSION: Lower RANKL and higher OPG concentrations could be detected in PJI, without statistical significance.

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.