T. Mumme

Assessment of leech therapy for knee osteoarthritis: A randomized study

Background and purpose Symptomatic treatment of osteoarthritis of the knee with leeches is presently undergoing a renaissance. Previous studies have shown methodical weaknesses. In the present study patients were blinded regarding the treatment, and a control group was included to explore possible differences in various subjective clinical scores and intake of pain medication over time between leech therapy and placebo control. Patients and methods 113 patients with advanced osteoarthritis of the knee were included. The patients were randomized to a single treatment group, group I (single leech application, n = 38), a double treatment group, group II (double application, n = 35), and a control group (n = 40). The second treatment in group II took place after an interval of 4 weeks. The treatment in the control group was simulated with the help of an “artificial leech”. Results were documented with the KOOS and WOMAC scores and also a visual analog scale (VAS) for pain. Changes in the use of pain medication were monitored over 26 weeks. Results An improvement in KOOS and WOMAC scores, and also in VAS, was found in all 3 groups following treatment. These improvements were statistically significant for treatment groups I and II during the complete follow-up period. The reduction in individual requirements for pain medication was also statistically significant. The greatest improvement was seen in the group treated twice with the leeches, with a long-term reduction of joint stiffness and improved function in the activities of daily living. Interpretation Leech therapy can reduce symptoms caused by osteoarthritis. Repeated use of the leeches appears to improve the long-term results. We have not determined whether the positive outcome of the leech therapy is caused by active substances released during the leeching, the placebo effect, or the high expectations placed on this unusual treatment form.

Klinische Drei-Jahres-Ergebnisse der matrixgekoppelten ACT zur Behandlung osteochondraler Defekte am Kniegelenk

AIM The aim of this study was to examine the clinical results after the treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation (ACT). METHOD In this study 13 patients with osteochondral defects of the knee (12 femoral, 1 tibial) with OCD ICRS grade IV or ICRS grade IV B were included. The osteochondral defects were reconstructed simultaneously with autologous monocortical cancellous bone cylinders or chips from cancellous bone and matrix-supported autologous chondrocyte transplantation (CaReS). Data were analysed in accordance with the ICRS criteria and the Brittberg score. Patients were followed up to 36 months after the operation. RESULTS The average age of the patients was 34.9 (16 - 47) years at the time of surgery. The size of the defect was 8.1 (3.8 - 13.5) cm(2). The subjective and objective IKDC scores, the Brittberg and the ICRS function score were statistically significantly improved during the observation time. In one patient the transplantation failed and another patient was not available for the follow-up at 36 months. The objective IKDC score and the ICRS function score increased from 0/13 (0 %) to 11/12 (91.7 %) in categories A and B, or I and II, respectively, after 3 years. At this point of time 83.4 % (10/12) of the patients voted the treatment as excellent or good. The subjective IKDC score improved from 38.4 (+/- 12.7) preoperatively to 66.1 (+/- 17.0) after 3 years. CONCLUSION The treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation shows promising results even for larger defects. But for a final decision about this therapy the present sample size was too small. There is a need for further long-term investigation with a larger number of patients.

Comparison of modern marker proteins in serum and synovial fluid in patients with advanced osteoarthrosis and rheumatoid arthritis

Numerous studies have focused on the significance of modern marker proteins in the synovial fluid of the knee joint and in the serum both, for osteoarthritis (OA) and rheumatoid arthritis (RA). The relationship between the serum concentrations and the concentrations in the synovial fluid is still unclear. Synovial fluid and serum samples were obtained from 13 patients with advanced OA and from 8 patients with severe RA and concentrations of MMP-1, MMP-3, MMP-13, TIMP-1, COMP and MIA/CD-RAP were determined. All values were normalized against the total protein concentrations. Serum concentrations of MMP-13 in the RA-group were statistically higher than the synovial values (P<0.05). MMP-13 was the only marker protein that revealed distinct higher levels in the serum than in the synovial fluid. The study design allows only conclusions about advanced stages of RA and OA. Longitudinal investigations may provide further information about the value of MMP-13 as a potential marker to monitor the course of RA and OA.

Condensed cellular seeded collagen gel as an improved biomaterial for tissue engineering of articular cartilage.

Three-dimensional autologous chondrocyte implantation based on collagen gel as matrix scaffold has become a clinically applied treatment for focal defects of articular cartilage. However, the low biomechanical properties of collagen gel makes intraoperative handling difficult and creates the risk of early damages to the vulnerable implant. The aim of the study was to create a stabilized form of collagen gel and to evaluate its biomechanical and biochemical properties.Collagen type-I gel was seeded with human articular chondrocytes. 20 samples were subject to condensation which was achieved mechanically by compression and filtration. Control samples were left uncondensed. From both types of gels 10 samples were used for initial biomechanical evaluation by means of unconfined compression and 10 samples were cultivated under standard conditions in vitro. Following cultivation the samples were evaluated by conventional histology and immunohistochemistry. The proliferation rate was calculated and matrix gene expression was quantified by real-time PCR.The biomechanical tests revealed a higher force carrying capacity of the condensed specimens. Strain rate dependency and relaxation was seen in both types of collagen gel representing viscoelastic material properties. Cells embedded within the condensed collagen gel were able to produce extracellular matrix proteins and showed proliferation.Condensed collagen gel represents a mechanically improved type of biomaterial which is suitable for three-dimensional autologous chondrocyte implantation.

Uncemented femoral revision arthroplasty using the modular revision prosthesis MRP-TITAN revision stem.

ZusammenfassungOperationszielWiederherstellung eines schmerzfrei belastbaren Hüftgelenks mit einem zementfrei implantierten, rotationsstabilen, diaphysär verankerten modularen Revisionsschaft.IndikationenProthesenschaftlockerungen mit osteolytischen Knochendefekten (Defektklassifikation nach Paprosky Typ I–III). Materialversagen mit Prothesenbruch.Sub- und/oder periprothetische Femurfrakturen.Tumoren.KontraindikationenAusgedehnte Osteolysen, die eine diaphysäre Prothesenverankerung nicht erlauben.OperationstechnikTransglutealer Zugang zum Hüftgelenk. Entfernen des gelockerten Prothesenschafts und — im zementierten Fall — des Knochenzements. Entfernen des intramedullären Granulationsgewebes. Aufbohren des Markraums mit flexiblen Bohrwellen und formschlüssige, zementfreie Implantation des sternförmigen modularen Revisionsschaftes mit diaphysärem „Press-fit‘ Bei ausgedehntem metaphysären Knochendefekt Augmentation mit autogenem/allogenem Knochen.WeiterbehandlungMobilisation an zwei Unterarmgehstützen ab dem 1. postoperativen Tag. Entfernen der einliegenden Redon-Drainagen nach 48 h. Teilbelastung mit 20 kg für 6 Wochen postoperativ. Bei nativradiologisch unverändertem Prothesensitz nach 6 Wochen Steigerung der Belastung um wöchentlich 10 kg bis zur Vollbelastung unter Fortführen der Thromboseprophylaxe. Röntgenkontrollen im weiteren Verlauf nach 3, 6 und 12 Monaten. Anschließend jährliche Verlaufskontrolle.ErgebnisseUntersucht wurden 45 Patienten (n = 48 Prothesen) mit einem durchschnittlichen Lebensalter von 67,2 Jahren (min.–max. 42,4–87,4 Jahre). Die mittlere Prothesenstandzeit der Modularen Revisions Prothese MRP-TITAN-Revisionsschaft betrug 4,7 Jahre (min.–max. 1,0–9,0 Jahre). Der Harris-Hip-Score — differenziert nach den Knochendefekttypen Paprosky I–III — stieg von 25,6 präoperativ auf 71,4 postoperativ zum Zeitpunkt der letzten Nachuntersuchung (≤0,05). 32 Patienten wiesen präoperativ einen ausgedehnten knöchernen Defekt auf (≥Paprosky IIB). 44 Patienten zeigten nativradiologisch eine stabile Verankerung ohne Migration. In einem Fall wurde der Schaft (Standzeit 2,36 Jahre) bei zunehmendem axialen Einsinken (≥5 mm) gewechselt. Bei allen Patienten mit Knochentransplantation (n = 30) zeigte sich ein guter Transplantateinbau mit konsekutiver Defektregeneration. Bei sechs Patienten kam es zu postoperativen Luxationen mit nachfolgender viermaliger geschlossener Reposition. Bei zwei Patienten wurde offen reponiert und der Antetorsionswinkel des Prothesenhalses ohne Ausbau der distal verankerten Prothesenschaftkomponente korrigiert. Mechanische Versagerquote im 9-Jahres-Nachuntersuchungszeitraum: eine von 48 prospektiv untersuchten Prothesen. Überlebensrate nach Kaplan-Meier 97%.AbstractObjectiveRestoration of a painless hip joint capable of bearing weight by uncemented implantation of a rotationally stable, modular revision stem anchored in the diaphysis.IndicationsProsthetic stem loosening with osteolytic bone defects (defect classification types I–III according to Paprosky). Material failure with broken prosthesis.Sub- and/or periprosthetic femoral fractures.Tumors.ContraindicationsExtensive osteolysis preventing diaphyseal anchorage of the prosthesis.Surgical TechniqueTransgluteal approach to the hip joint. Removal of the loose prosthetic stem and, if cemented, the bone cement as well. Excision of intramedullary granulation tissue. Reaming of the medullary cavity with flexible reaming shafts and form-fit, uncemented implantation of the star-shaped modular revision stem with diaphyseal press fit. If there is extensive loss of metaphyseal bone stock, augmentation with autogenous/allogenic bone should be performed.Postoperative ManagementMobilization on two underarm crutches from the 1st postoperative day. Removal of the Redon drains after 48 h. Partial loading with 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; thrombosis prophylaxis is continued throughout. Radiologic checkups after 3, 6, and 12 months. After that, the patient should be checked annually.Results45 patients (n = 48 prostheses) with an average age of 67.2 years (min.–max. 42.4–87.4 years) were investigated. The average implantation time of the Modular Revision Prosthesis MRP-TITAN revision stem was 4.7 years (min.–max. 1.0–9.0 years). The Harris Hip Score for Paprosky bone defect types I–III had increased from 25.6 preoperatively to 71.4 postoperatively at the time of the final follow-up (≤0.05). Extensively defective bone was diagnosed preoperatively in 32 patients (≥Paprosky IIB). Plain radiographs showed stable anchorage without migration in 44 patients. In one case, the stem (implantation time 2.36 years) was replaced due to increasing axial subsidence (≥5 mm). Good integration of bone graft with subsequent defect regeneration was seen in all patients with bone transplant (n = 30). Postoperative dislocation occurred in six patients and required closed reduction in four cases. Open reduction was performed in two patients, whereby the external rotation angle of the prosthetic neck was corrected without dismantling the distally anchored prosthetic stem components. The mechanical failure rate over the follow-up period of 9 years was one out of the 48 prospectively investigated prostheses. Rate of survival according to Kaplan-Meier was 97%.

Zementfreier Femurschaftwechsel mit der Modularen Revisions Prothese MRP-TITAN-Revisionsschaft

ZusammenfassungOperationszielWiederherstellung eines schmerzfrei belastbaren Hüftgelenks mit einem zementfrei implantierten, rotationsstabilen, diaphysär verankerten modularen Revisionsschaft.IndikationenProthesenschaftlockerungen mit osteolytischen Knochendefekten (Defektklassifikation nach Paprosky Typ I–III). Materialversagen mit Prothesenbruch.Sub- und/oder periprothetische Femurfrakturen.Tumoren.KontraindikationenAusgedehnte Osteolysen, die eine diaphysäre Prothesenverankerung nicht erlauben.OperationstechnikTransglutealer Zugang zum Hüftgelenk. Entfernen des gelockerten Prothesenschafts und — im zementierten Fall — des Knochenzements. Entfernen des intramedullären Granulationsgewebes. Aufbohren des Markraums mit flexiblen Bohrwellen und formschlüssige, zementfreie Implantation des sternförmigen modularen Revisionsschaftes mit diaphysärem „Press-fit‘ Bei ausgedehntem metaphysären Knochendefekt Augmentation mit autogenem/allogenem Knochen.WeiterbehandlungMobilisation an zwei Unterarmgehstützen ab dem 1. postoperativen Tag. Entfernen der einliegenden Redon-Drainagen nach 48 h. Teilbelastung mit 20 kg für 6 Wochen postoperativ. Bei nativradiologisch unverändertem Prothesensitz nach 6 Wochen Steigerung der Belastung um wöchentlich 10 kg bis zur Vollbelastung unter Fortführen der Thromboseprophylaxe. Röntgenkontrollen im weiteren Verlauf nach 3, 6 und 12 Monaten. Anschließend jährliche Verlaufskontrolle.ErgebnisseUntersucht wurden 45 Patienten (n = 48 Prothesen) mit einem durchschnittlichen Lebensalter von 67,2 Jahren (min.–max. 42,4–87,4 Jahre). Die mittlere Prothesenstandzeit der Modularen Revisions Prothese MRP-TITAN-Revisionsschaft betrug 4,7 Jahre (min.–max. 1,0–9,0 Jahre). Der Harris-Hip-Score — differenziert nach den Knochendefekttypen Paprosky I–III — stieg von 25,6 präoperativ auf 71,4 postoperativ zum Zeitpunkt der letzten Nachuntersuchung (≤0,05). 32 Patienten wiesen präoperativ einen ausgedehnten knöchernen Defekt auf (≥Paprosky IIB). 44 Patienten zeigten nativradiologisch eine stabile Verankerung ohne Migration. In einem Fall wurde der Schaft (Standzeit 2,36 Jahre) bei zunehmendem axialen Einsinken (≥5 mm) gewechselt. Bei allen Patienten mit Knochentransplantation (n = 30) zeigte sich ein guter Transplantateinbau mit konsekutiver Defektregeneration. Bei sechs Patienten kam es zu postoperativen Luxationen mit nachfolgender viermaliger geschlossener Reposition. Bei zwei Patienten wurde offen reponiert und der Antetorsionswinkel des Prothesenhalses ohne Ausbau der distal verankerten Prothesenschaftkomponente korrigiert. Mechanische Versagerquote im 9-Jahres-Nachuntersuchungszeitraum: eine von 48 prospektiv untersuchten Prothesen. Überlebensrate nach Kaplan-Meier 97%.AbstractObjectiveRestoration of a painless hip joint capable of bearing weight by uncemented implantation of a rotationally stable, modular revision stem anchored in the diaphysis.IndicationsProsthetic stem loosening with osteolytic bone defects (defect classification types I–III according to Paprosky). Material failure with broken prosthesis.Sub- and/or periprosthetic femoral fractures.Tumors.ContraindicationsExtensive osteolysis preventing diaphyseal anchorage of the prosthesis.Surgical TechniqueTransgluteal approach to the hip joint. Removal of the loose prosthetic stem and, if cemented, the bone cement as well. Excision of intramedullary granulation tissue. Reaming of the medullary cavity with flexible reaming shafts and form-fit, uncemented implantation of the star-shaped modular revision stem with diaphyseal press fit. If there is extensive loss of metaphyseal bone stock, augmentation with autogenous/allogenic bone should be performed.Postoperative ManagementMobilization on two underarm crutches from the 1st postoperative day. Removal of the Redon drains after 48 h. Partial loading with 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; thrombosis prophylaxis is continued throughout. Radiologic checkups after 3, 6, and 12 months. After that, the patient should be checked annually.Results45 patients (n = 48 prostheses) with an average age of 67.2 years (min.–max. 42.4–87.4 years) were investigated. The average implantation time of the Modular Revision Prosthesis MRP-TITAN revision stem was 4.7 years (min.–max. 1.0–9.0 years). The Harris Hip Score for Paprosky bone defect types I–III had increased from 25.6 preoperatively to 71.4 postoperatively at the time of the final follow-up (≤0.05). Extensively defective bone was diagnosed preoperatively in 32 patients (≥Paprosky IIB). Plain radiographs showed stable anchorage without migration in 44 patients. In one case, the stem (implantation time 2.36 years) was replaced due to increasing axial subsidence (≥5 mm). Good integration of bone graft with subsequent defect regeneration was seen in all patients with bone transplant (n = 30). Postoperative dislocation occurred in six patients and required closed reduction in four cases. Open reduction was performed in two patients, whereby the external rotation angle of the prosthetic neck was corrected without dismantling the distally anchored prosthetic stem components. The mechanical failure rate over the follow-up period of 9 years was one out of the 48 prospectively investigated prostheses. Rate of survival according to Kaplan-Meier was 97%.

Perioperatives Management in der ambulanten arthroskopischen Chirurgie des Kniegelenks

AIM Nowadays, complex arthroscopic procedures of the knee joint, such as ACL reconstruction, are routinely carried out on an outpatient basis. The reduced time spent with the patient places high demands on the surgeon with regard to the management of such cases. The aim of this study was to evaluate the current standards of perioperative management following outpatient arthroscopic surgery of the knee in Germany. METHODS A questionnaire consisting of 18 questions was sent to 215 members of the German Association of Outpatient Arthroscopy (BVASK e. V.), dealing with the following topics: antibiotic prophylaxis, DVT prophylaxis, use of a tourniquet and suction drain, physical therapy, physiotherapy, analgesia, anaesthesia and emergency management. More than 51% of the forms were returned and considered suitable for statistical analysis. RESULTS A total of 62% of the surgeons reported the use of an antibiotic prophylaxis (i. v. single shot) in every arthroscopic case, while 19% administer antibiotics only occasionally, especially in ACL reconstruction. Postoperative antibiotic treatment was reserved for special situations, such as prior joint infection. Prophylaxis of DVT by means of low molecular weight heparin was carried out in 96% of the cases. 51% prescribed anticoagulant agents for 1 week, 39% for the duration of reduced weight bearing. Half of the surgeons used a tourniquet cuff, 22% exsanguinate the limb prior to cuff inflation. A suction drainage was applied by 36% of the surgeons regularly and by 45% occasionally. The drain is left for one day by 79% of the surgeons, while 11% reported a shortened use of only several hours. With regard to analgesia, 66% of all surgeons apply some kind of local anaesthetic into the knee joint post surgery. Systemic preoperative analgesics or anti-inflammatory agents are given regularly in 56 % of the cases. A total of 92% of the procedures are carried out under general anaesthesia. In 36% of the cases, some kind of additional regional peripheral anaesthesia is used. With regard to postoperative care, cryotherapy is considered standard (97%) and 64% of the surgeons recommend physiotherapy. Nearly all surgeons (97%) offer the patients the opportunity to reach them personally via mobile phone during the first night following arthroscopic surgery. CONCLUSIONS DVT prophylaxis with LMWH, general anaesthesia, postoperative cryotherapy and personal availability by phone can be considered part of the standard perioperative management following outpatient knee arthroscopy in Germany. However, a wide variety of treatment options can be found regarding topics such as analgesia, antibiotic prophylaxis, tourniquet, knee drainage and physiotherapy.

Measures for reducing ultra-high-molecular-weight polyethylene wear in total knee replacement: a simulator study.

Abstract Wear of ultra-high-molecular-weight polyethylene (UHM-WPE) inlays is associated with aseptic loosening in total knee replacement (TKR). The aim of this study was to investigate the in vitro performance of a TKR system that combines several measures to decrease UHMWPE wear. Tests were carried out on a BPK-S Integration system (R&D, P. Brehm Chirurgie-Mechanik, Weisendorf, Germany) according to ISO 14243-1 in a knee joint simulator. Calf serum with a high protein concentration of 30 g/l was chosen as the test lubricant. PE wear was measured gravimetrically. Particle analysis was performed by scanning electron microscopy, with measurement of particle size and shape. Low mean wear rates of 1.20 mg per million cycles were found for the fixed bearing type and 2.47 mg per million cycles for the rotating-platform bearing design. Anteroposterior deflection was low. The contact areas for both types of bearings were large and showed a constant pattern throughout the test. Backside wear was obvious on rotating platforms. Particle analysis revealed equally sized and round-shaped particles in both types of bearings (fixed, 0.35 μm; mobile, 0.32 μm). In conclusion, the combination of design features and surface modifications of the BPK-S integration TKR system leads to low gravimetric UHMWPE wear. Zusammenfassung Abrieb von Ultra-High-Molecular-Weight Polyethylen (UHMWPE) gilt als eine der wesentlichen Ursachen für die aseptische Lockerung von Knieendoprothesen. Das Ziel dieser Studie ist es, das Abriebverhalten eines Knieendoprothesensystems zu untersuchen, welches verschiedene Ansätze zur Abriebsminimierung vereint. Getestet wurde das BPK-S Integration-System der Firma R&D, P. Brehm Chirurgie-Mechanik (Weisendorf, Germany), gemäß ISO 14243-1, in einem Kniesimulator. Es wurde Kälberserum mit einer erhöhten Proteinkonzentration von 30 g/l eingesetzt. Der PE-Abrieb wurde gravimetrisch bestimmt. Die Abriebpartikel wurden mittels Elektronenmikroskopie nach deren Form und Größe analysiert. Es fanden sich insgesamt geringe Abriebraten von 1,2 mg pro 1 Mio. Zyklen beim „fixed bearing”- und 2,47 mg pro 1 Mio. Zyklen beim „mobile bearing”-System. Die a.-p.-Auslenkung war gering. Die femorotibialen Kontaktflächen zeigten bei beiden ultrakongruenten Systemen keine wesentliche Veränderung über den Prüfungszeitraum. An den Inlays des „mobile bearing”-Systems fanden sich Zeichen des „backside wear”. Die Partikelanalyse zeigte vergleichbar große, überwiegend runde Abriebpartikel („fixed”, 0,35 μm; „mobile”, 0,32 μm). Zusammenfassend fand sich als Folge der Oberflächenbehandlung und des Designs des BPK-S Integration-Systems ein sehr geringer gravimetrischer Abrieb im Vergleich zu Angaben über andere, ebenfalls nach ISO 14243-1 gemessene Kniesysteme.

Trackerless ultrasound-integrated bone cement detection using a modular minirobot in revision total hip replacement:

Abstract Medical robots are superior to freehand manipulation if an accurate, precise, and time-efficient implementation of a preplanned intervention is required. In the first part of this contribution a new modular minirobot for automatic ultrasound-based bone cement detection followed by subsequent cement milling in revision total hip replacement is presented. A minirobot integrated ultrasound module eliminates the need for external position tracking (e.g. by an optical system) as well as patient registration since the scanned contours can be directly provided within the robots coordinate system. Further, the modular minirobot concept allows kinematics, workspace, and mechanical parameters to be easily adapted to the requirements of related or even new surgical applications. In the experimental part, the impact of ultrasound module integration on the implementation of optimized scanning strategies is investigated and evaluated in a laboratory set-up. As wave mode conversion and refraction artefacts due to angular sound incidence influence the detection accuracy, the transducer alignment can be optimized with respect to the number of degrees of freedom (DOFs) provided by the minirobot. A model-based scanning approach using two degrees of freedom (2DOFs), three degrees of freedom (3DOFs), and four degrees of freedom (4DOFs) respectively is presented. For automated scanning path calculation, a 2DOF distal—proximal prescan has been performed to estimate the principal components of the cement cavitys geometry using either a model-based or a statistical approach. In a cadaver study, the model-based approach consistently outperformed the statistical approach. The 3DOFs and 4DOFs scanning strategies yielded a significantly higher scanning accuracy if compared with the 2DOFs approach whereas the 3DOFs approach represents a trade-off between system complexity and detection accuracy.

Funktionalität und Genauigkeit eines fluoroskopischen Navigationssystems zur Implantation von Hüftkopf-Oberflächenersatzprothesen: Eine Anatomiestudie

INTRODUCTION Resurfacing arthroplasty represents an alternative method to total hip replacement especially for the young and active patient. The main reasons for early implant failure are mal-positioning of the femoral component and notching of the femoral neck during femoral head preparation. MATERIAL AND METHODS In the context of a cadaver study of formalin-fixed cadaveric full body specimens 6 DUROM -Hip-Resurfacing prosthesis have been implanted under navigation control. The aim of the study was an evaluation of the functionality and accuracy of the computer-assisted planning and navigation system on the basis of a navigation module library from Surgitaix AG Aachen, Germany. RESULTS The main angulation error between planning (135.2 +/- 3.6 degrees ) and navigation (136.2 +/- 2.8 degrees ) was 1.9 +/- 1.1 degrees , the main anterior offset error between planning (2.2 +/- 1.3 mm) and navigation (2.7 +/- 2.3 mm) was 1.2 +/- 1.9 mm. The main distance error between planning and navigation was 2.7 +/- 1.3 mm. The mean time for all five planning and navigation steps was 20.2 +/- 2.5 min. Against the background of a acetabular bone-saving approach in all 6 cases the smallest possible femoral component could be implanted. CONCLUSION The computer-assisted fluoroscopic planning and navigation system for hip resurfacing showed within the scope of this cadaver study first promising results. The system approaches a practicable intraoperative planning with a high accuracy in operative implementation. Nevertheless, the potential benefit has to be evaluated in further clinical studies, especially from the perspective of a possible integration of this navigation system into the clinical work-flow. Further studies should consider a fluoroscopic-assisted range of motion assessment under consideration of an additional cup-module to enhance the postoperative range of motion after hip resurfacing procedures.