Jörg Lützner

European multidisciplinary consensus statement on the use and monitoring of metal-on-metal bearings for total hip replacement and hip resurfacing.

INTRODUCTION There is an ongoing debate about the optimal use of metal-on-metal (MoM) bearings in total hip replacement, since there are uncertainties about local and systemic adverse effects due to wear and corrosion of these bearings. Despite various national recommendations, efforts to achieve international harmonization of specific evidence-based recommendations for best practice are still lacking. HYPOTHESIS An international consensus study group should be able to develop recommendations on the use and monitoring of MoM bearings, preferably at the European level, through a multidisciplinary approach, by integrating the perspectives of various stakeholders. MATERIALS AND METHODS Twenty-one experts representing three stakeholder groups and eight countries participated in this European consensus study, which consisted of a consensus meeting, subsequent structured discussion, and consensus voting. RESULTS The current statement defines first of all benefits, local and systemic risks, as well as uncertain issues related to MoM bearings. Safety assessment after implantation of MoM comprises all patients. A closer follow-up is recommended for large head MoM (≥36mm) and resurfacing. In these implants basic follow-up should consist of x-rays and metal ion measurement of cobalt in whole blood, performed with GF-AAS or ICP-MS. Clinical and/or radiographic abnormality as well as elevated ion levels needs additional imaging (ultrasound, CT-scan and/or MARS-MRI). Cobalt values less than 2 μg/L are probably devoid of clinical concern, the threshold value for clinical concern is expected to be within the range of 2-7 μg/L. DISCUSSION This is the first multinational, interdisciplinary, and multiprofessional approach for developing a recommendation for the use and monitoring of MoM bearings in total hip replacement. The current recommendations are in partial agreement with previous statements regarding the extent of follow-up and imaging techniques. They however differ from previous communications regarding measurement of metal ions and especially the investigated medium, technique, and eventual threshold levels. LEVEL OF EVIDENCE Level V, expert opinion/agreement conference.

Surgical options for patients with osteoarthritis of the knee.

Osteoarthritis (OA) of the knee is a progressive disease that ultimately damages the entire joint. Knee OA should initially be treated conservatively, but surgery should be considered if symptoms persist. Surgical treatments for knee OA include arthroscopy, osteotomy and knee arthroplasty; determining which of these procedures is most appropriate will depend on several factors, including the location and severity of OA damage, patient characteristics and risk factors. Arthroscopic lavage and debridement do not alter disease progression, and should not be used as a routine treatment for the osteoarthritic knee. Bone marrow stimulation techniques such as microfracture are primarily used to treat focal chondral defects; the evidence for the use of these techniques for knee OA remains unclear. The goal of osteotomy for unicompartmental knee OA is to transfer the weight load from the damaged compartment to undamaged areas, delaying the need for joint replacement. This procedure should be considered in young and active patients who are not suitable candidates for knee arthroplasty. For patients with severe OA, total knee arthroplasty can be a safe, rewarding and cost-effective treatment. In selected patients with isolated medial or patellofemoral OA, unicompartmental knee arthroplasty and patellofemoral replacement, respectively, can be successful.

Metal ion concentrations in body fluids after implantation of hip replacements with metal-on-metal bearing--systematic review of clinical and epidemiological studies.

Introduction The use of metal-on-metal (MoM) total hip arthroplasty (THA) increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds) in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. Objective To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. Methods Systematic review of clinical trials (RCTs) and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum) in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor), patient characteristics as well as study quality characteristics (secondary explanatory factors). Results Overall, 104 studies (11 RCTs, 93 epidemiological studies) totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine) irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L). Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. Discussion Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed „time out“ for stemmed large-head MoM-THA and recommend a restricted indication for hip resurfacing arthroplasty. Patients with implanted MoM-bearing should receive regular and standardized monitoring of metal ion concentrations. Further research is indicated especially with regard to potential systemic reactions due to accumulation of metal products.

Rotational alignment of the tibial component in total knee arthroplasty is better at the medial third of tibial tuberosity than at the medial border

BackgroundCorrect rotational alignment of the femoral and tibial component is an important factor for successful TKA. The transepicondylar axis is widely accepted as a reference for the femoral component. There is not a standard reference for the tibial component. CT scans were used in this study to measure which of 2 tibial landmarks most reliably reproduces a correct femoro-tibial rotational alignment in TKA.Methods80 patients received a cemented, unconstrained, cruciate-retaining TKA with a rotating platform. CT scans were performed 5-7 days postoperatively but before discharge. The rotational mismatch between the femoral and tibial components was measured. Furthermore, the rotational variance between the transepicondylar line, as a reference for the orientation of the femoral component and different tibial landmarks, was measured.ResultsThere was notable rotational mismatch between the femoral and tibial components. The median mismatch was 0° (range: 16.2 degrees relative external to 14.4 degrees relative internal rotation of the femoral component).Using the transepicondylar line as a reference for femoral rotational alignment and the medial third of the tuberosity as a reference for tibial rotational alignment, 67.5% of all TKA had a femoro-tibial variance within ± 5 degrees, 85% within ± 10 degrees and 97.5% within ± 20 degrees. Using the medial border of the tibial tubercle as a reference this variance was greater, only 3.8% had a femoro-tibial variance within ± 5 degrees, 15% within ± 10 degrees and 68.8% within ± 20 degrees.ConclusionUsing fixed bone landmarks for rotational alignment leads to a notable variance between femoral and tibial components. Referencing the tibial rotation on a line from the medial third of the tibial tubercle to the center of the tibial tray resulted in a better femoro-tibial rotational alignment than using the medial border of tibial tubercle as a landmark. Surgeons using fixed bearings with a high rotational constraint between the inlay and the femoral component should be aware of this effect to avoid premature polyethylene wear.Trial RegistrationClinical trials registry NCT01022099

Consensus statement “Current evidence on the management of metal-on-metal bearings” - April 16, 2012

The following recommendations are based on expert opinions of an international multidisciplinary panel endorsed by the “European Federation of National Associations of Orthopaedics and Traumatology” (EFORT), the “European Hip Society” (EHS), the German “Arbeitsgemeinschaft Endoprothetik” (AE) and the “Deutsche Arthrosehilfe” (DAH)

Efficacy and safety of thromboprophylaxis with low-molecular-weight heparin or rivaroxaban in hip and knee replacement surgery

Prospective trials have shown that rivaroxaban thromboprophylaxis is superior over low-molecular-weight heparin (LMWH) in patients undergoing hip and knee replacement surgery. However, patients treated under trial conditions are different from unselected routine patients, which may affect efficacy and safety of thromboprophylaxis. The objective was to evaluate the efficacy and safety of rivaroxaban or LMWH thromboprophylaxis in unselected patients undergoing hip and knee replacement surgery in daily care. In a monocentric, retrospective cohort study in 5,061 consecutive patients undergoing hip and knee replacement surgery a comparison of LMWH (hospital standard in 2006-2007) and rivaroxaban (since 2009) was made with regard to rates of symptomatic VTE, bleeding and surgical complications and length of hospital stay. Rates of symptomatic VTE were 4.1 % (LMWH) and 2.1 % (rivaroxaban; p=0.005) with rates for distal DVT 2.5 vs. 1.1 % (p<0.001). Rates of major VTE were numerically higher with LMWH (1.7 vs. 1.1%, not statistically significant). Rates of major bleeding (overt bleeding leading to surgical revision or death, occurring in a critical site, or transfusion of at least two units of packed red blood cells) were statistically lower with rivaroxaban (2.9 vs. 7.0%; p<0.001). Rivaroxaban patients had fewer surgical complications (1.1 vs. 3.7%; p<0.001) and a shorter length of hospitalisation (8.3 days; 95% CI 8.1- 8.5 vs. 11.1 days; 10.7- 11.5; p< 0.001). We conclude that rivaroxaban thromboprophylaxis is more effective than LMWH in unselected patients undergoing hip and knee replacement surgery in daily care and that switching from LMWH to rivaroxaban could be beneficial. Prospective comparisons are warranted to confirm our findings.

Metal hypersensitivity and metal ion levels in patients with coated or uncoated total knee arthroplasty: a randomised controlled study

PurposeMetal ion release by orthopaedic implants may cause local and systemic effects and induce hypersensitivity reactions. Coated implants have been developed to prevent or reduce these effects. This study was initiated to investigate the safety of a novel coating for total knee arthroplasty (TKA) implants.MethodsA total of 120 patients undergoing primary TKA with no history of hypersensitivity and no other metal implant were randomised to receive either a coated or uncoated implant. Chromium (Cr), cobalt (Co), molybdenum (Mb) and nickel (Ni) hypersensitivity patch testing and plasma ion concentrations were evaluated pre-operatively and one year post-operatively.ResultsAt the one year follow-up both groups demonstrated significant improvement in knee function and quality of life. One new weakly positive reaction to Co in the TKA group with coated implant and two doubtful skin reactions to Ni (one in each group) were noted. Even with sensitisation to implant materials no skin reactions were observed. Plasma metal ion concentrations did not increase and were not elevated at the one year follow-up in either group.ConclusionsSensitisation after TKA was rare and had no influence on clinical results. TKA with coated implant and standard TKA demonstrated no plasma metal ion elevation.

Prosthesis alignment affects axial rotation motion after total knee replacement: a prospective in vivo

BackgroundClinical consequences of alignment errors in total knee replacement (TKR) have led to the rigorous evaluation of surgical alignment techniques. Rotational alignment in the transverse plane has proven particularly problematic, with errors due to component malalignment relative to bone anatomic landmarks and an overall mismatch between the femoral and tibial components’ relative positions. Ranges of nominal rotational alignment are not well defined, especially for the tibial component and for relative rotational mismatch, and some studies advocate the use of mobile-bearing TKR to accommodate the resulting small rotation errors. However, the relationships between prosthesis rotational alignment and mobile-bearing polyethylene insert motion are poorly understood. This prospective, in vivo study evaluates whether component malalignment and mismatch affect axial rotation motions during passive knee flexion after TKR.MethodsEighty patients were implanted with mobile-bearing TKR. Rotational alignment of the femoral and tibial components was measured from postoperative CT scans. All TKR were categorized into nominal or outlier groups based on defined norms for surgical rotational alignment relative to bone anatomic landmarks and relative rotational mismatch between the femoral and tibial components. Axial rotation motion of the femoral, tibial and polyethylene bearing components was measured from fluoroscopic images acquired during passive knee flexion.ResultsAxial rotation motion was generally accomplished in two phases, dominated by polyethylene bearing rotation on the tibial component in early to mid-flexion and then femoral component rotation on the polyethylene articular surface in later flexion. Opposite rotations of the femur-bearing and bearing-baseplate articulations were evident at flexion greater than 80°. Knees with outlier alignment had lower magnitudes of axial rotation and distinct transitions from external to internal rotation during mid-flexion. Knees with femoral-tibial rotational mismatch had significantly lower total axial rotation compared to knees with nominal alignment.ConclusionsMaintaining relative rotational mismatch within ±5° during TKR provided for controlled knee axial rotation during flexion. TKR with rotational alignment outside of defined surgical norms, with either positive or negative mismatch, experienced measurable kinematic differences and presented different patterns of axial rotation motions during passive knee flexion compared to TKR with nominal mismatch. These findings support previous studies linking prosthesis rotational alignment with inferior clinical and functional outcomes.Trial RegistrationClinical Trials NCT01022099

Prosthesis alignment affects axial rotation motion after total knee replacement: a prospective in vivo study combining computed tomography and fluoroscopic evaluations

BackgroundClinical consequences of alignment errors in total knee replacement (TKR) have led to the rigorous evaluation of surgical alignment techniques. Rotational alignment in the transverse plane has proven particularly problematic, with errors due to component malalignment relative to bone anatomic landmarks and an overall mismatch between the femoral and tibial components’ relative positions. Ranges of nominal rotational alignment are not well defined, especially for the tibial component and for relative rotational mismatch, and some studies advocate the use of mobile-bearing TKR to accommodate the resulting small rotation errors. However, the relationships between prosthesis rotational alignment and mobile-bearing polyethylene insert motion are poorly understood. This prospective, in vivo study evaluates whether component malalignment and mismatch affect axial rotation motions during passive knee flexion after TKR.MethodsEighty patients were implanted with mobile-bearing TKR. Rotational alignment of the femoral and tibial components was measured from postoperative CT scans. All TKR were categorized into nominal or outlier groups based on defined norms for surgical rotational alignment relative to bone anatomic landmarks and relative rotational mismatch between the femoral and tibial components. Axial rotation motion of the femoral, tibial and polyethylene bearing components was measured from fluoroscopic images acquired during passive knee flexion.ResultsAxial rotation motion was generally accomplished in two phases, dominated by polyethylene bearing rotation on the tibial component in early to mid-flexion and then femoral component rotation on the polyethylene articular surface in later flexion. Opposite rotations of the femur-bearing and bearing-baseplate articulations were evident at flexion greater than 80°. Knees with outlier alignment had lower magnitudes of axial rotation and distinct transitions from external to internal rotation during mid-flexion. Knees with femoral-tibial rotational mismatch had significantly lower total axial rotation compared to knees with nominal alignment.ConclusionsMaintaining relative rotational mismatch within ±5° during TKR provided for controlled knee axial rotation during flexion. TKR with rotational alignment outside of defined surgical norms, with either positive or negative mismatch, experienced measurable kinematic differences and presented different patterns of axial rotation motions during passive knee flexion compared to TKR with nominal mismatch. These findings support previous studies linking prosthesis rotational alignment with inferior clinical and functional outcomes.Trial RegistrationClinical Trials NCT01022099

Revision of unicompartmental knee arthroplasty

ZusammenfassungDeutlich gestiegene Implantationszahlen unikondylärer Knieprothesen bei der Gonarthrose lassen trotz insgesamt guter Überlebensraten einen zukünftigen Anstieg von Revisionseingriffen erwarten. Die Versagensgründe nach unikondylären Knieprothesen unterscheiden sich hinsichtlich Ursache und Häufigkeitsverteilung deutlich von bikondylären Prothesen. Neben einer aseptischen Lockerung stellt häufig das Fortschreiten der Arthrose im unversorgten Kompartiment eine Indikation für die Wechseloperation dar. Die Revision einer unikondylären Knieprothese wird in der Regel auf eine bikondyläre Knieprothese erfolgen.Die präzise Feststellung des Versagensgrundes ist wesentlich für eine erfolgreiche Revision. Bei gedeckten Knochendefekten kann die Auffüllung mit Knochentransplantaten erfolgen. Bei ungedeckten Knochendefekten ist die Versorgung mit Augmentationen und Stielverlängerungen zu empfehlen. Das Revisionsimplantat sollte modular an das Ausmaß von Knochendefekten angepasst werden können.AbstractDespite the good midterm survivorship reported for unicondylar knee arthroplasty, an increase in revision surgery has to be expected due to increased replacement rates. The reasons for failure as well as distribution are different for unicondylar knee arthroplasty compared to total knee arthroplasty.The main reasons for revision are aseptic loosening and the progression of osteoarthritis. In most cases, unicondylar knee arthroplasty will be revised to total knee arthroplasty. To obtain good revision results, the cause of implant failure has to be analysed carefully. In the case of contained bone defects, the reconstruction can be supported with bone grafting. For those cases with uncontained defects, implants with augmentation and, in some cases, stem extensions are needed. The modularity of the revision implant should cover different intraoperative requirements.