[Acetabular metastatic defect reconstruction using the modular revision support cup MRS-C]. / Rekonstruktion von metastasenbedingten Defekten des Azetabulums mittels der MRS-C-Abstützschale.

OBJECTIVE: Stabilization of metastatic acetabular defects with a bone cement-augmented revision support cup for remobilization of oncological patients in advanced cancer stages. INDICATIONS: Metastatic acetabular defects (Metastatic Acetabular Classification, MAC 2-4) in patients with a prognostic medium or long-term survival. CONTRAINDICATIONS: Highly limited survival due to metastatic disease (< 6 weeks). Local bone or soft tissue infection. Primary bone tumor with curative treatment option. Advanced pelvic discontinuity. Recent wound compromising systemic therapy. SURGICAL TECHNIQUE: Standard hip approach. Curettage of the metastatic defect and careful reaming of the acetabulum before insertion of the cup. Predrilling of the dome und flange screws before application of the bone cement through the center hole of the implant and filling of the acetabular defect. Complete insertion of the screws for compound osteosynthesis. Implant of a modular inlay or dual mobility system. POSTOPERATIVE MANAGEMENT: Full weight bearing or mobilization with two crutches according to the level of pain. Adjuvant local radiation therapy after wound consolidation. Continuation of systemic therapy according to tumor board decision. RESULTS: Between 2012 and 2019, we treated 14 patients with metastatic acetabular defects using the modular revision support cup "MRS-TITAN® Comfort", MRS-C, Peter Brehm GmbH, Weisendorf, Germany) at our institution. Mean Harris Hip Score improvement was 23.2 with a mean patient's survival of 9.7 months due to the reduced cancer-related prognosis; 13 of the 14 implants endured the patient's prognosis. One implant had to be removed due soft tissue defect-related periprosthetic joint infection.

Analysis of synovial biomarkers with a multiplex protein microarray in patients with PJI undergoing revision arthroplasty of the hip or knee joint.

INTRODUCTION: Diagnosing a (low-grade) periprosthetic joint infection (PJI) after hip or knee arthroplasty remains a diagnostic challenge. The aim of this study was to evaluate the utility of using a novel multiplex protein microarray system for synovial biomarkers in determining PJI in patients undergoing revision knee or hip arthroplasty. MATERIALS AND METHODS: The individual synovial fluid levels of 12 cytokines (IL-1b, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-17, GM-CSF, TNF-α, and INF-γ) were analysed with a novel multiplex protein microarray system in 32 patients undergoing revision hip (n = 22) or knee (n = 10) arthroplasty. Cases were classified into septic and aseptic groups on basis of pre- and interoperative findings: [PJI (n = 14) vs. non-PJI (n = 18)]. Receiver operator characteristic (ROC) curves were calculated to assess the discriminatory strength of the individual parameters. A multiple regression model was used to determine the utility of using a combination of the tested cytokines to determine the infection status. RESULTS: The levels of all of the evaluated cytokines were significantly elevated in the PJI-group. Best sensitivity and specificity were found for IL-6, followed by IL-1b, IL-10, and IL-17. The multiple regression models revealed a combination of IL-2, IL-4, IL-5, IL6, lL-12, and GM-CSF to be associated with the best sensitivity (100%) and specificity (88.9%) for a cut-off value of 0.41, with a likelihood ratio of 9.0. CONCLUSION: Analysis of individual synovial fluid cytokine levels showed both high sensitivity and high specificity in diagnosing PJI. A combined model using several cytokines showed even higher sensitivity and specificity in diagnosing PJI and could thus be a useful predictive tool to determine the probability of PJI in patients with a painful prosthesis. LEVEL OF EVIDENCE: Diagnostic IV.

[Modular arthrodesis system TITAN (KAM-TITAN) after failed revision total knee arthroplasty : Operative technique and clinical experience]. / Modulares Kniearthrodesesystem TITAN (KAM-TITAN) nach fehlgeschlagener Knieendoprothetik : Operative Technik und klinische Ergebnisse.

OBJECTIVE: Restoration of a painless, weight-bearing extremity with a modular knee arthrodesis system based on a cementless modular revision stem for rotationally stable, diaphyseal anchorage. INDICATIONS: Severe bone loss and compromised soft tissue after failed total knee arthroplasty, two-stage revisions and non-reconstructible knee extensor mechanism deficiency. CONTRAINDICATIONS: Extensive osteolysis preventing diaphyseal anchorage of the prosthesis. Contralateral arthrodesis of the knee joint and/or ipsilateral arthrodesis of the hip joint and contralateral lower extremity amputation. SURGICAL TECHNIQUE: In revision cases, removal of the total knee arthroplasty, spacer, the bone cement and all intramedullary granulation tissue. Reaming the medullary cavity with intramedullary reamers to cortical contact. Restoring leg length and rotation with trial implants. After implantation of the femoral and tibial stems, placing and tensioning of the rotationally aligned coupling elements. POSTOPERATIVE MANAGEMENT: Mobilization on two forearm crutches from postoperative day 1. Removal of the Redon drains after 48 h. Partial weight bearing of 20 kg for 6 weeks postoperatively. If plain radiographs show unchanged seating of the prosthesis after 6 weeks, loading can be increased by 10 kg per week until full weight bearing is achieved. RESULTS: Between 2007 and 2012 clinical data were collected and analyzed retrospectively. A total of 27 patients had been treated within a two-stage exchange procedure with implantation of a modular intramedullary arthodesis nail TITAN (KAM-TITAN). The mean follow-up was 30.9 ± 12.0 months. A functional evaluation was performed using the Oxford Knee Score (OKS). The analyzed patients showed a mean score of 39.2 ± 8.3. To determine the pain level the Visual Analog Scale (VAS) for pain was used and showed a mean score of 2.9 ± 1.3. The rate of definitely free of infection (using Laffer criteria) at last follow-up was 85.2%.

Mid-term results after revision total hip arthroplasty with custom-made acetabular implants in patients with Paprosky III acetabular bone loss.

INTRODUCTION: Severe acetabular bone loss, both with or without pelvic discontinuity, remains a challenge in revision total hip arthroplasty (RTHA). The goal of our study was to evaluate the mid-term results for consecutive patients with Paprosky III acetabular bone loss with or without pelvic discontinuity who needed RTHA with custom-made acetabular implants and to compare the results to those of other studies. MATERIALS AND METHODS: Sixty-eight (68) patients with severe acetabular bone loss (Paprosky Type IIIa and IIIb), who required RTHA, were included in our study. All prostheses were constructed on the basis of thin-layer computed tomography (CT) scans of the pelvis. The visual analogue scale (VAS), Harrison hip score (HHS), and clinical and radiographic follow-up assessments were used to evaluate the outcome. RESULTS: The average follow-up time was 43 months (range 1-120 months). Implant survival at last follow-up was 75% (51 of 68). Kaplan-Meier survival analysis, with explantation as the endpoint, revealed survival rates of 82.7% (3 years) and 77% (5 years). Patients with revision of the acetabular component only had a significant higher survival rate (p 0.012). Overall revision rate was 36.7%. Reinfection rate was 34.4%. Complications included 15 (22%) periprosthetic joint infections (PJI), 7 dislocations (10.2%), and 2 aseptic loosenings (2.9%). Mean VAS at last follow-up was 1.45 compared to 3.2 preoperatively, while mean HHS improved from 21.1 points preoperatively to 61 at last follow-up. The change in both scores was thus significant (p < 0.001). CONCLUSION: Defect reconstruction with custom-made modular acetabular implants can be a good, nevertheless expensive, treatment option with clinically and radiologically satisfying results in comparison to recent studies in the literature. Nevertheless, high postoperative complication rates, especially in terms of PJI, remain a challenge.

Staphylococcus aureus versus Staphylococcus epidermidis in periprosthetic joint infection-Outcome analysis of methicillin-resistant versus methicillin-susceptible strains.

Periprosthetic joint infections (PJIs) are a major complication in total joint arthroplasty. Staphylococcus aureus and coagulase-negative staphylococci are known to cause the majority of all PJIs. This study aimed to analyze the eradication rates of S. aureus and S. epidermidis with methicillin susceptibility and methicillin resistance in a 2-stage therapy algorithm. Seventy-four patients with PJI caused by methicillin-resistant S. aureus (MRSA), methicillin-resistant coagulase-negative staphylococci (MRSE), methicillin-susceptible S. aureus (MSSA), and methicillin-susceptible coagulase-negative staphylococci (MSSE) were included, and the outcome was analyzed retrospectively. After a minimal follow-up of 2 years, n = 56 patients (75.7%) were definitively free of infection. The analysis revealed significant differences between the groups, with eradication rates as follows: MSSA (92.6%), MSSE (95.2%), MRSA (80%), and MRSE (54.2%). MRSE showed a significantly lower rate of patients graded as "definitively free of infection" as compared to patients with infections caused by MSSA, MSSE, and MRSA.

Osseous hydatidosis of the proximal femur: a rare diagnosis in revision total hip arthroplasty.

Musculoskeletal hydatidosis is a rare but severe disease in central Europe. This case report presents the incidental finding of an osseous hydatidosis after cementless revision total hip arthroplasty in a patient without a preoperative history of hydatidosis or any clinical symptoms. Revision total hip arthroplasty had been necessary due to a septic osteonecrosis of the femoral head 2 years after osteosynthesis of a traumatic proximal femur fracture with a sliding hip screw. The positive sample was taken out of the greater trochanter in the area of the possible former entry point for the lag screw, which was macroscopic inconspicuous. Sero-analysis could afterwards confirm the suspected diagnosis. Postoperative chemotherapy with albendazole was performed for 6 months. A full-body MRI did not reveal any further cysts. This case demonstrates a possible impact of migration on the expected pathogens in revision arthroplasty. This demonstrates that in revision arthroplasty, an infection with this parasite also has to be taken into account, if the patients come from an area endemic for hydatidosis.

Fluid collection bags pose a threat for bacterial contamination in primary total hip arthroplasty: a prospective, internally controlled, non-blinded trial.

INTRODUCTION: Surgical equipment, and especially the so-called 'splash basins' that are used intraoperatively, are a potential source of bacterial contamination in primary total hip arthroplasty (THA). With this risk in mind, many commercially available draping kits include plastic bags that can be used to collect fluid or to temporarily store instruments. Following this rationale, we hypothesised that first: the fluid collection bags are a potential reservoir of bacteria and second: there is a time dependency for bacterial contamination. MATERIALS AND METHODS: After ethics approval, we investigated in a prospective, internally controlled, non-blinded trial 43 patients who received primary THA. At the beginning of the surgery, we took deep, representative, intracapsular tissue samples, which served as negative controls. At the end of surgery, tissue samples were taken from the bottom of the 'fluid collection bag' for microbiological analysis. RESULTS: All 86 control samples were negative. Out of the samples taken from the bags, a pathogen could be detected in four patients (9.3%). All pathogens were detected after a surgery time lasting longer than 90 min. CONCLUSION: We were able to show that fluid collection bags are a potential reservoir for bacteria in THA when surgery time was greater than a 90-min threshold. Our data suggest that the risks from fluid collection bags outweigh the advantages of using them. Therefore, we recommend against the use of fluid collection bags intraoperatively in primary THA.

[Biological downsizing : Acetabular defect reconstruction in revision total hip arthroplasty]. / Biologisches Downsizing : Azetabuläre Knochendefekte in der Hüftrevisionsendoprothetik.

BACKGROUND: Periacetabular bony defects remain a great challenge in revision total hip arthroplasty. After assessment and classification of the defect and selection of a suitable implant the primary stable fixation and sufficient biological reconstitution of a sustainable bone stock are essential for long term success in acetabular revision surgery. Biological defect reconstruction aims for the down-sizing of periacetabular defects for later revision surgeries. TECHNIQUE: In the field of biological augmentation several methods are currently available. Autologous transplants feature a profound osseointegrative capacity. However, limitations such as volume restrictions and secondary complications at the donor site have to be considered. Structural allografts show little weight bearing potential in the long term and high failure rates. In clinical practice, the usage of spongious chips implanted via impaction bone grafting technique in combination with antiprotrusio cages for the management of contained defects have shown promising long time results. Nevertheless, when dealing with craniolateral acetabular and dorsal column defects, the additional implantation of macroporous metal implants or augments should be considered since biological augmentation has shown little clinical success in these particular cases. PROSPECT: This article provides an overview of the current clinically available biological augmentation methods of peri-acetabular defects. Due to the limitations of autologous and allogeneic bone transplants in terms of size and availability, the emerging field of innovative implantable tissue engineering constructs gains interest and will also be discussed in this article.

The QuickLine IL-6 lateral flow immunoassay improves the rapid intraoperative diagnosis of suspected periprosthetic joint infections.

BACKGROUND: When deciding upon the best treatment strategy in revision arthroplasty, it is absolutely crucial to use the best possible preoperative detection whether a periprosthetic joint infection (PJI) is present or not. New molecular markers investigated in serum samples and synovial fluid can help to improve the preoperative diagnosis. In 2001, a novel IL-6 lateral flow immunoassay testing device was introduced which has never been tested in synovial fluid so far. OBJECTIVE: For our study we investigated whether the test can be used safely, feasibly and time effectively with synovial fluid gathered from potentially infected THAs or TKAs and whether the already published cutoff for IL-6 in synovial fluid predicting a PJI can be reproduced using the QuickLine IL-6 immunoassay. METHODS: After ethic approval and within the scope of a prospective controlled trial we investigated 26 patients (m = 9, 34.6%; f= 17, 65.4%) with n = 13 (50%) potentially infected total hip arthroplasties (THAs) and n = 13 (50%) suspected PJIs of total knee arthroplasties (TKAs). Sterile aspirated synovial fluid was examined for total leukocyte count and cell differentiation by a blood count analyzer in body fluid mode as well as for IL-6 (Immulite, Siemens Medical Solutions Diagnostics GmbH, Eschborn, Germany). Another part of the joint aspirate was tested using the QuickLine IL-6 Test by Milenia Biotec (Milenia Biotec, Gießen, Germany). RESULTS: The mean concentration of IL-6 as determined from our reference laboratory testing (Siemens Immulight) for aseptic cases was 1,219 pg/mL (SD 1,369 pg/mL, min 134 pg/mL-max 4,214 pg/mL). The mean IL-6 concentration measured via the IL-6 QuickLine for aseptic cases was 410 pg/mL (SD 371 pg/mL, min 100 pg/mL-max 1562 pg/mL). The test showed no false negative or false positive results in the cases tested. In six patients, PJI was considered proven. The QuickLine Test indicated IL 6 concentrations > 10,000 pg/mL in these cases without further quantification above this maximum detection threshold. Results from the QuickLine Test and the laboratory tests were matched and a non-linear best fit curve (log-log-curve) was applied. The subsequent Spearman correlation showed a correlation coefficient of r = 0.92 (95% CI 0.81-0.97) which corresponds to a two-tailed p-value of < 0.0001, respectively. As a primary finding we were able to show that the Milenia QuickLine IL-6 Test can be used safely, feasibly and time effectively with synovial fluid gathered intraoperatively from potentially infected THAs or TKAs. The test as provided worked well in 84.6% of the samples tested and failed only due to very viscous synovial fluid. As a secondary result we found that the previously published cut-off for IL-6 in synovial fluid predicting a PJI with a sensitivity of 46.88% and a specificity of 97.62% can be reproduced using the QuickLine IL-6 immunoassay. CONCLUSION: Taking the limitations of the low sample size as a given this relatively simple point of care (POC) assay showed promising results in our pilot trial and may help diagnosing PJI. It may help physicians and surgeons to choose the best and least invasive treatment strategy for patients presenting with painful arthroplasty.

[Intra-articular Sampling with Novel Biopsy Forceps: a Simple and Reliable Diagnostic Procedure for Patients with Periprosthetic Infections of the Knee Joint]. / Intraartikuläre Probenentnahme mit einer neuartigen Biopsiezange: ein leichtes und sicheres diagnostisches Verfahren bei Patienten mit periprothetischen Infektionen des Kniegelenks.

Introduction: Rapid and reliable differentiation between septic and aseptic presentations can be challenging in patients with painful total knee arthroplasties. Clinical symptoms, serum tests, as well as the analysis of synovial fluid, are important parameters. Nevertheless, deep intra-articular tissue samples exhibit greater sensitivity and specificity regarding the diagnosis of a suspected periprosthetic joint infection. In 2014, Hügle et al. introduced novel retrograde forceps to acquire tissue samples and synovial fluid simultaneously in an outpatient setting. In this article, we present the first use of their device in patients with total knee arthroplasty. Methods: After approval by a local ethics board, retrograde forceps were used via the standard lateral suprapatellar approach. The technique was comparable to conventional aspiration of a total knee arthroplasty. Beside joint aspiration, tissue samples were gathered for further microbiological and histopathological examination. Results and Discussion: It is easy to collect synovial fluid and tissue samples using the retrograde forceps in patients with suspected periprosthetic infections of the knee joint. This is a safe and feasible method and can be performed in an outpatient setting. We have not yet observed any complications and consider that the risks are comparable to those with conventional joint aspiration. In our opinion, this technique may be useful in detecting infections in patients with painful total knee arthroplasty.

[Intercalary reconstruction for diaphyseal bone defects with a modular replacement system: Clinical results]. / Interkalare Rekonstruktion diaphysärer Knochendefekte mit einem modularen Diapyhsenersatzsystem: Klinische Ergebnisse.

OBJECTIVE: Reconstruction and long-term stabilization of segmental diaphyseal bone defects of the humerus, femur, and tibia. INDICATIONS: Segmental bone defects due to aggressive benign or primary malignant bone tumors, trauma, pathological fractures, osteomyelitis, or failed osteosynthesis. CONTRAINDICATIONS: Acute or chronic local infections, large metadiaphyseal bone defects preventing adequate anchorage of the prosthesis, very short life expectancy (<3 months). SURGICAL TECHNIQUE: Exposure and resection of the bony defect according to the preoperative planning. Reaming of the intramedullary canals proximally and distally followed by implantation of the stems (cemented or noncemented). Reducing sleeves can be used to bridge the difference in diameter between the nail and the spacer. Mounting of the spacer half shell with the threaded holes from underneath after adjusting for alignment and rotation. Assembling of the other half shell by guided pins to ensure proper alignment. Tightening of the clamping screws using a torque screwdriver. Connection of two spacers is possible. POSTOPERATIVE MANAGEMENT: Active physiotherapy and full weight bearing; antibiotic prophylaxis. RESULTS: The results of 14 consecutive patients treated with 15 modular intercalary endoprostheses (Osteobridge™, Merete, Berlin, Germany) between January 2007 and January 2012 with a mean follow up of 24 ± 12 months (range 12-51 months) were evaluated retrospectively. One patient had a primary malignant bone tumor, while all the other patients underwent resection for metastatic disease. The mean age at surgery was 65.9 ± 15.7 years (range 25-83 years). The mean diaphyseal reconstruction length was 110 ± 50 mm (range 50-190 mm). Three patients (20%) required revision of the distal stem due to aseptic loosening. Evaluation of the functional outcome using the MSTS score by Enneking revealed 3 very good (22%), 7 good (50%), 4 fair (28%), and no poor results.

[Stem cell-based therapy in orthopaedics and trauma surgery - current concepts]. / Aktueller Stand der Stammzelltherapie in Orthopädie und Unfallchirurgie.

Over the last few years, numerous new treatment methods have been developed for musculoskeletal diseases. Some of these new methods are based on the targeted use of stem cells to initiate healing processes, to compensate for deficits or to activate the regeneration of tendons, muscles, bones and cartilage. This goal can be achieved through the direct use of stem cells on or in a carrier material or through a combination with tissue engineering. In this article, we give a short overview of the possible fields of application of inducible pluripotent haematopoietic, and adult stem cells as well as on their use in musculoskeletal tissue. Furthermore, we provide a summary of the current legal situation concerning the application of stem cells in humans.

[Low-intensity pulsed ultrasound for treatment of fractures and nonunions - current evidence and insights from basic research and clinical application]. / Niedrigintensiver gepulster Ultraschall zur Behandlung von Frakturen und Pseudarthrosen - Evidenz und Erkenntnisse aus Forschung und Klinik.

In Germany, 800,000 fractures are treated per year, and up to 10 % of these patients may suffer subsequently from a delayed union or a nonunion at the fracture site. Surgical treatment of these complications is tedious and associated with high costs. Therefore non-operative treatment is recently receiving more scientific and clinical attention. The adjuvant treatment with ultrasound has been propagated for the past years to enhance fracture healing and bony union, and has been discussed controversially. This review article demonstrates the significance of the low intensity pulsed ultrasound application in fracture treatment, on the basis of basic science results, animal experiments and the results of clinical trials.

Hip resurfacing using a modified lateral approach with limited splitting of the gluteus medius muscle results in significant impairment of hip abductor strength.

BACKGROUND: A lateral, transgluteal approach for hip resurfacing carries the risk of approach-related weakening of the hip abductors due to unsuccessful re-adaptation of the gluteal muscles to the greater trochanter or to injury to the inferior nerve branch of the superior gluteal nerve. OBJECTIVE: We investigated whether hip resurfacing using a soft tissue-sparing, modified transgluteal approach with limited cranial splitting of the gluteus medius muscle reduces hip abductor strength and the risk of approach-related injury to the superior gluteal nerve. METHODS: Thirty-one patients (14 female, 17 male; mean age 53.5 ± 5.2 years) underwent hip resurfacing using a modified transgluteal approach with limited cranial splitting of the gluteus medius muscle. Nerve conduction signals were measured by surface electromyography (EMG), hip abductor strength by isokinetic testing a mean 36.2 months (± 11 mos) after surgery. The unoperated side was used as control. RESULTS: Surface EMG disclosed no neural lesions of the inferior branch of the superior gluteal nerve. Isokinetics revealed a significant reduction in muscle strength on the operated versus the contralateral side. CONCLUSIONS: Even a limited incision of the gluteus medius muscle resulted in significant impairment of hip abductor strength 2.5 years after surgery.

[Comparison of clinical and radiological data in the treatment of patients with osteoporotic vertebral compression fractures using radiofrequency kyphoplasty or balloon kyphoplasty]. / Vergleich klinischer und radiologischer Daten bei der Behandlung von Patienten mit osteoporotischen Wirbelkörper-Kompressionsfrakturen mit Radiofrequenz-Kyphoplastie oder mit Ballon-Kyphoplastie.

PURPOSE: Since the 1990s, balloon kyphoplasty has been proven as an effective method of treating patients with painful vertebral compression fractures (VCF). The radiofrequency kyphoplasty is an innovative procedure available since 2009, for which an ultra-high viscosity cement is used. For the statistical comparison of the two methods of augmentation, the clinical and radiological data of 2 larger patient groups were evaluated. MATERIALS AND METHODS: As part of the surgical treatment of patients with conservative therapy-resistant osteoporotic vertebral fractures, a prospective study of radiofrequency kyphoplasty (RFK) was performed between 2009 and September 2010. The treatment was minimally invasive using the StabiliT® Vertebral Augmentation System by DFine for which the StabiliT® multiplex controller, the articulating VertecoR® Midline Osteotome, and the radiofrequency-sensitive StabiliT® ER2 bone cement were applied. From the clinical aspect, measurement parameters for efficacy and safety were the course of pain intensity using a visual analogue scale (VAS: 0 to 100 mm) and the Oswestry disability score (0-100%). For the radiological outcome the increase in the middle and anterior parts of the treated vertebra and also the reduction of kyphosis after surgery and after 6 months were evaluated. Furthermore, the extent of cement extrusion and the duration of operation time were compared. There were 2 groups of patients chosen with the same indication, and with the same average VAS prior to treatment. For the balloon kyphoplasty (BKP) the Kyphon® technology was used. For the BKP group the same parameters as in the first group were evaluated (matched pairs). To compare the data statistically, parametric and non-parametric tests were applied. RESULTS: For the radiofrequency kyphoplasty group (RFK) 114 patients were recruited, and for the balloon kyphoplasty group (BKP) 114 appropriate patients were selected. In 48% of the RFK patients and in 44% of the BKP patients more than one vertebral body were treated (thoracic or lumbar). Prior to treatment 84 mm on the VAS were calculated in both groups. The decrease in VAS values (RFK vs. BKP) immediately after surgery was 58.8 vs. 54.7 mm (p = 0.02), and 73.0 vs. 58.9 mm after 6 months (p < 0.001). In both groups improvements in the Oswestry scores were registered after 6 months without a statistically significant difference. In both groups, the middle part of the vertebral bodies was increased by an average of 3.1 mm. RFK yielded a decrease in the average kyphosis angle of 4.4, the BKP resulted in about 3.8 degrees. Concerning cement leakage a key difference in favor of the radio frequency kyphoplasty was detected (6.1 % vs. 27.8%; p < 0.0001). For RFK a significant shorter duration of operation time was calculated (28.2 vs. 49.6 min; p < 0.001). CONCLUSIONS: The RFK has proven to be a clinically very effective procedure that does somewhat better than BKP in long-lasting pain relief. No differences could be detected regarding improvement of functioning and the mean restoration of mid- and anterior vertebral height. As far as the safety aspect is concerned the RFK offers the advantage of a statistically significant lower proportion of cement extrusion.