M. Ettinger

Biomechanische Analyse der Press-fit-Fixierung von Kreuzbandtransplantaten

Press-fit fixation of anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. A total of 168 cadaveric human patellar, quadriceps and hamstring tendons (average age 49.2 +/- 18.5 years) were used and 15 different fixation methods were tested. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were compared. Some techniques showed comparable biomechanical qualities to interference screw fixation. All investigated double bundle fixation techniques were equal in terms of maximum load to failure, stiffness and elongation. All techniques exhibited greater elongation during initial cyclical loading. Some of the press-fit fixation techniques investigated exhibited comparable biomechanical properties and preconditioning of the constructs is critical. Press-fit fixation enhances tendon to bone contact at the entry of the bone tunnel to the joint.

[Kinematic alignment in total knee arthroplasty : Concept, evidence base and limitations].

ZusammenfassungHintergrundVor dem Hintergrund weiterhin rund 20 % unzufriedener Patienten nach endoprothetischem Kniegelenkersatz ist eine neue Diskussion um das optimale Alignment in der Knieendoprothetik entfacht. Ein vielversprechender Ansatz ist dabei das kinematische Alignment (KA), das eine Prothesenpositionierung streng anhand der Drehachsen des natürlichen Knies vorsieht.MethodikIn dieser Arbeit wird anhand eines eingehenden Literaturreviews und eigener Forschungsergebnisse das Konzept des KA, einschließlich der Limitationen und der vorhandenen klinische Evidenz erläutert.Ergebnisse und DiskussionErste klinische Studien zeigen eine schnellere Patientenrehabilitation, eine verbesserte Kniefunktion und höhere Patientenzufriedenheit. Allerdings muss auf die noch dünne Evidenzlage hingewiesen werden. Die aus der Technik resultierenden Achsabweichungen zur mechanischen Achse scheinen zumindest kurzfristig keinen negativen Einfluss zu haben, Langzeitergebnisse liegen allerdings noch nicht vor. Dennoch scheint das KA nicht für jeden Patienten geeignet und weitere Untersuchungen für die Formulierung von Ein- und Ausschlusskriterien scheinen sinnvoll.AbstractBackgroundAgainst the background that 20 % of patients are dissatisfied after total knee arthroplasty, there is ongoing controversy about optimal alignment. In this context, orientating the prosthetic components to the natural kinematic axes of the knee appears to be an interesting new concept.MethodsThe objective of this paper is to provide a critical review of the current literature and our own research data regarding the concept of kinematically aligned total knee arthroplasty with the current evidence base and potential limitations.Results and discussionIn the recent literature faster rehabilitation, better knee function, and higher patient satisfaction are described compared to conventional alignment, even if the postoperative alignment deviates more than 3° from the mechanical axis. However, the technique may not be suitable for every patient and pathology, and further research is necessary to set the correct indication.BACKGROUND Against the background that 20 % of patients are dissatisfied after total knee arthroplasty, there is ongoing controversy about optimal alignment. In this context, orientating the prosthetic components to the natural kinematic axes of the knee appears to be an interesting new concept. METHODS The objective of this paper is to provide a critical review of the current literature and our own research data regarding the concept of kinematically aligned total knee arthroplasty with the current evidence base and potential limitations. RESULTS AND DISCUSSION In the recent literature faster rehabilitation, better knee function, and higher patient satisfaction are described compared to conventional alignment, even if the postoperative alignment deviates more than 3° from the mechanical axis. However, the technique may not be suitable for every patient and pathology, and further research is necessary to set the correct indication.

[Computer-assisted systems in total knee arthroplasty. Useful aid or only additional costs].

BACKGROUND The primary goal of computer-assisted surgery (CAS) in total knee arthroplasty is to increase the accuracy in terms of prosthesis positioning. In theory, this would lead to longer implant survival and a reduction of malpositioning. Thus, a better clinical outcome and lower revision rates would be expected. However, the necessary technical equipment represents significant additional effort and cost factors which are not included in the current diagnosis-related groups (DRG) system. OBJECTIVE The objective of this article is a critical review of the current literature to examine whether these costs are reasonable by taking the additional benefits of the technology into account. METHODS This review is based on a selective PubMed search on CAS and navigation in primary total knee arthroplasty. RESULTS The current evidence base on CAS suggests that at least the primary outcome parameter, the improvement of the radiological alignment, is achieved by the technique. However, the claimed secondary effects are not yet proven. In particular, an improvement of clinical outcome and patient satisfaction has not been demonstrated so far. Furthermore, there is some evidence of increased complication rates by the use of CAS. CONCLUSION Against this background and with respect to further cost-benefit analyses, the technology has to be reviewed critically. In particular, low-volume units do not seem to benefit from the use of CAS. However, the assessment of long-term effects is still pending.ZusammenfassungHintergrundDas primäre Ziel der Verwendung von Computerassistenzsystemen (CAS) in der Knieendoprothetik ist die Erhöhung der Implantationsgenauigkeit in Bezug auf die Prothesenpositionierung. In der Theorie verspricht man sich hierdurch eine längere Implantatstandzeit und durch Reduzierung von Fehlpositionierungen letzten Endes auch ein besseres Patientenoutcome sowie geringere Komplikations- und Revisionsraten. Allerdings stellt die erforderliche technische Ausstattung einen Mehraufwand dar, der im aktuellen DRG-System (Diagnosis-Related Groups) nicht abgebildet ist.FragestellungIn dieser Arbeit soll durch ein eingehendes Literaturreview kritisch der Frage nachgegangen werden, ob dieser Mehraufwand durch den zusätzlichen Nutzen der Technik gerechtfertigt ist.Material und MethodeDiese Arbeit basiert auf einer selektiven Literaturrecherche in der Datenbank PubMed zu CAS und Navigationssystemen in der primären Endoprothetik des Kniegelenks.ErgebnisseAus der verfügbaren Evidenz zu den CAS lässt sich schließen, dass zumindest der genannte primäre Zielparameter – die Verbesserung des radiologischen Outcomes – durch die Technik erreicht wird. Allerdings lassen sich die genannten sekundären Effekte in der aktuellen Literatur nicht sicher nachweisen. Insbesondere eine Verbesserung von klinischem Patientenoutcome und -zufriedenheit kann nicht belegt werden. Weiterhin gibt es Hinweise auf erhöhte Komplikationsraten bei der Verwendung von CAS.SchlussfolgerungVor diesem Hintergrund und auch hinsichtlich der Kosten-Nutzen-Analyse muss die Technik entsprechend kritisch betrachtet werden. Insbesondere Kliniken mit kleinen Fallzahlen scheinen nicht von den CAS zu profitieren. Allerdings steht die Bewertung von Langzeiteffekten noch aus.AbstractBackgroundThe primary goal of computer-assisted surgery (CAS) in total knee arthroplasty is to increase the accuracy in terms of prosthesis positioning. In theory, this would lead to longer implant survival and a reduction of malpositioning. Thus, a better clinical outcome and lower revision rates would be expected. However, the necessary technical equipment represents significant additional effort and cost factors which are not included in the current diagnosis-related groups (DRG) system.ObjectiveThe objective of this article is a critical review of the current literature to examine whether these costs are reasonable by taking the additional benefits of the technology into account.MethodsThis review is based on a selective PubMed search on CAS and navigation in primary total knee arthroplasty.ResultsThe current evidence base on CAS suggests that at least the primary outcome parameter, the improvement of the radiological alignment, is achieved by the technique. However, the claimed secondary effects are not yet proven. In particular, an improvement of clinical outcome and patient satisfaction has not been demonstrated so far. Furthermore, there is some evidence of increased complication rates by the use of CAS.ConclusionAgainst this background and with respect to further cost-benefit analyses, the technology has to be reviewed critically. In particular, low-volume units do not seem to benefit from the use of CAS. However, the assessment of long-term effects is still pending.

[Biomechanical analysis of press-fit fixation of anterior cruciate ligament transplants].

Press-fit fixation of anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. A total of 168 cadaveric human patellar, quadriceps and hamstring tendons (average age 49.2 +/- 18.5 years) were used and 15 different fixation methods were tested. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were compared. Some techniques showed comparable biomechanical qualities to interference screw fixation. All investigated double bundle fixation techniques were equal in terms of maximum load to failure, stiffness and elongation. All techniques exhibited greater elongation during initial cyclical loading. Some of the press-fit fixation techniques investigated exhibited comparable biomechanical properties and preconditioning of the constructs is critical. Press-fit fixation enhances tendon to bone contact at the entry of the bone tunnel to the joint.

Knieprothesendesign und Kinematik: Unterschiede in Radien, Konformität und Rotation/Pivot

Today, there is an almost endless variety of knee prosthesis models on the market from which the surgeon can choose. Although the designs appear closer and closer to one another, the industry makes a great effort to emphasise different features as beneficial and a stand-alone. It is increasingly difficult to keep an overview and to assess the clinical relevance of the diverse features. There is a clear lack of independent comparative studies and evidence is low. Nevertheless, different design philosophies require special surgical techniques, so that the surgeon must be familiar with the peculiarity of his/her prosthesis. Also, a differentiated indication for different designs appears to be an interesting concept. The aim of this essay is to give a brief overview of the major design concepts of current unconstrained knee prosthesis designs and their differences regarding biomechanics and kinematics.

Kinematisches Alignment in der Knieendoprothetik@@@Kinematic alignment in total knee arthroplasty: Konzept, Evidence und Limitation@@@Concept, evidence base and limitations

ZusammenfassungHintergrundVor dem Hintergrund weiterhin rund 20 % unzufriedener Patienten nach endoprothetischem Kniegelenkersatz ist eine neue Diskussion um das optimale Alignment in der Knieendoprothetik entfacht. Ein vielversprechender Ansatz ist dabei das kinematische Alignment (KA), das eine Prothesenpositionierung streng anhand der Drehachsen des natürlichen Knies vorsieht.MethodikIn dieser Arbeit wird anhand eines eingehenden Literaturreviews und eigener Forschungsergebnisse das Konzept des KA, einschließlich der Limitationen und der vorhandenen klinische Evidenz erläutert.Ergebnisse und DiskussionErste klinische Studien zeigen eine schnellere Patientenrehabilitation, eine verbesserte Kniefunktion und höhere Patientenzufriedenheit. Allerdings muss auf die noch dünne Evidenzlage hingewiesen werden. Die aus der Technik resultierenden Achsabweichungen zur mechanischen Achse scheinen zumindest kurzfristig keinen negativen Einfluss zu haben, Langzeitergebnisse liegen allerdings noch nicht vor. Dennoch scheint das KA nicht für jeden Patienten geeignet und weitere Untersuchungen für die Formulierung von Ein- und Ausschlusskriterien scheinen sinnvoll.AbstractBackgroundAgainst the background that 20 % of patients are dissatisfied after total knee arthroplasty, there is ongoing controversy about optimal alignment. In this context, orientating the prosthetic components to the natural kinematic axes of the knee appears to be an interesting new concept.MethodsThe objective of this paper is to provide a critical review of the current literature and our own research data regarding the concept of kinematically aligned total knee arthroplasty with the current evidence base and potential limitations.Results and discussionIn the recent literature faster rehabilitation, better knee function, and higher patient satisfaction are described compared to conventional alignment, even if the postoperative alignment deviates more than 3° from the mechanical axis. However, the technique may not be suitable for every patient and pathology, and further research is necessary to set the correct indication.BACKGROUND Against the background that 20 % of patients are dissatisfied after total knee arthroplasty, there is ongoing controversy about optimal alignment. In this context, orientating the prosthetic components to the natural kinematic axes of the knee appears to be an interesting new concept. METHODS The objective of this paper is to provide a critical review of the current literature and our own research data regarding the concept of kinematically aligned total knee arthroplasty with the current evidence base and potential limitations. RESULTS AND DISCUSSION In the recent literature faster rehabilitation, better knee function, and higher patient satisfaction are described compared to conventional alignment, even if the postoperative alignment deviates more than 3° from the mechanical axis. However, the technique may not be suitable for every patient and pathology, and further research is necessary to set the correct indication.

Computerassistenzsysteme in der Knieendoprothetik@@@Computer-assisted systems in total knee arthroplasty: Sinnvolle Hilfsmittel oder nur Mehraufwand@@@Useful aid or only additional costs

BACKGROUND The primary goal of computer-assisted surgery (CAS) in total knee arthroplasty is to increase the accuracy in terms of prosthesis positioning. In theory, this would lead to longer implant survival and a reduction of malpositioning. Thus, a better clinical outcome and lower revision rates would be expected. However, the necessary technical equipment represents significant additional effort and cost factors which are not included in the current diagnosis-related groups (DRG) system. OBJECTIVE The objective of this article is a critical review of the current literature to examine whether these costs are reasonable by taking the additional benefits of the technology into account. METHODS This review is based on a selective PubMed search on CAS and navigation in primary total knee arthroplasty. RESULTS The current evidence base on CAS suggests that at least the primary outcome parameter, the improvement of the radiological alignment, is achieved by the technique. However, the claimed secondary effects are not yet proven. In particular, an improvement of clinical outcome and patient satisfaction has not been demonstrated so far. Furthermore, there is some evidence of increased complication rates by the use of CAS. CONCLUSION Against this background and with respect to further cost-benefit analyses, the technology has to be reviewed critically. In particular, low-volume units do not seem to benefit from the use of CAS. However, the assessment of long-term effects is still pending.ZusammenfassungHintergrundDas primäre Ziel der Verwendung von Computerassistenzsystemen (CAS) in der Knieendoprothetik ist die Erhöhung der Implantationsgenauigkeit in Bezug auf die Prothesenpositionierung. In der Theorie verspricht man sich hierdurch eine längere Implantatstandzeit und durch Reduzierung von Fehlpositionierungen letzten Endes auch ein besseres Patientenoutcome sowie geringere Komplikations- und Revisionsraten. Allerdings stellt die erforderliche technische Ausstattung einen Mehraufwand dar, der im aktuellen DRG-System (Diagnosis-Related Groups) nicht abgebildet ist.FragestellungIn dieser Arbeit soll durch ein eingehendes Literaturreview kritisch der Frage nachgegangen werden, ob dieser Mehraufwand durch den zusätzlichen Nutzen der Technik gerechtfertigt ist.Material und MethodeDiese Arbeit basiert auf einer selektiven Literaturrecherche in der Datenbank PubMed zu CAS und Navigationssystemen in der primären Endoprothetik des Kniegelenks.ErgebnisseAus der verfügbaren Evidenz zu den CAS lässt sich schließen, dass zumindest der genannte primäre Zielparameter – die Verbesserung des radiologischen Outcomes – durch die Technik erreicht wird. Allerdings lassen sich die genannten sekundären Effekte in der aktuellen Literatur nicht sicher nachweisen. Insbesondere eine Verbesserung von klinischem Patientenoutcome und -zufriedenheit kann nicht belegt werden. Weiterhin gibt es Hinweise auf erhöhte Komplikationsraten bei der Verwendung von CAS.SchlussfolgerungVor diesem Hintergrund und auch hinsichtlich der Kosten-Nutzen-Analyse muss die Technik entsprechend kritisch betrachtet werden. Insbesondere Kliniken mit kleinen Fallzahlen scheinen nicht von den CAS zu profitieren. Allerdings steht die Bewertung von Langzeiteffekten noch aus.AbstractBackgroundThe primary goal of computer-assisted surgery (CAS) in total knee arthroplasty is to increase the accuracy in terms of prosthesis positioning. In theory, this would lead to longer implant survival and a reduction of malpositioning. Thus, a better clinical outcome and lower revision rates would be expected. However, the necessary technical equipment represents significant additional effort and cost factors which are not included in the current diagnosis-related groups (DRG) system.ObjectiveThe objective of this article is a critical review of the current literature to examine whether these costs are reasonable by taking the additional benefits of the technology into account.MethodsThis review is based on a selective PubMed search on CAS and navigation in primary total knee arthroplasty.ResultsThe current evidence base on CAS suggests that at least the primary outcome parameter, the improvement of the radiological alignment, is achieved by the technique. However, the claimed secondary effects are not yet proven. In particular, an improvement of clinical outcome and patient satisfaction has not been demonstrated so far. Furthermore, there is some evidence of increased complication rates by the use of CAS.ConclusionAgainst this background and with respect to further cost-benefit analyses, the technology has to be reviewed critically. In particular, low-volume units do not seem to benefit from the use of CAS. However, the assessment of long-term effects is still pending.

Spätzustände nach komplexer Bandverletzung am Kniegelenk@@@Trauma sequalae after complex knee ligament injuries

Complex ligament injuries can compromise a knee joint and residual conditions comprise stiffness (arthrofibrosis), instability, cartilage damage leading to osteoarthritis and bone deformity. Accurate diagnosis must address the direction and extent of the instability, the severity of any cartilage lesion and an analysis of the axis and bone deformity as well as important cofactors. Therapeutic options are adhesiolysis, ligament reconstruction, cartilage regeneration and axis correction. As a consequence patients mostly profit from the procedure but there is never a return to the functional level that existed before injury.ZusammenfassungSpätzustände ligamentärer Bandverletzungen können in 4 Themenkomplexe unterteilt werden: Bewegungseinschränkungen, knöcherne Fehlstellungen, ligamentäre Instabilitäten und Knorpel-/Meniskusschäden. Das Behandlungskonzept umfasst die systematische Erfassung der knöchernen Deformität, ligamentären Instabilität und der Knorpelschäden. Die Therapie erfolgt differenziert und stufenweise und erfordert eine prolongierte Rehabilitation. Die Limitierung des Endergebnisses durch die Schwere der Verletzung muss dabei sowohl dem Behandler, als auch dem Patienten bewusst sein.AbstractComplex ligament injuries can compromise a knee joint and residual conditions comprise stiffness (arthrofibrosis), instability, cartilage damage leading to osteoarthritis and bone deformity. Accurate diagnosis must address the direction and extent of the instability, the severity of any cartilage lesion and an analysis of the axis and bone deformity as well as important cofactors. Therapeutic options are adhesiolysis, ligament reconstruction, cartilage regeneration and axis correction. As a consequence patients mostly profit from the procedure but there is never a return to the functional level that existed before injury.

Trauma sequalae after complex knee ligament injuries

Complex ligament injuries can compromise a knee joint and residual conditions comprise stiffness (arthrofibrosis), instability, cartilage damage leading to osteoarthritis and bone deformity. Accurate diagnosis must address the direction and extent of the instability, the severity of any cartilage lesion and an analysis of the axis and bone deformity as well as important cofactors. Therapeutic options are adhesiolysis, ligament reconstruction, cartilage regeneration and axis correction. As a consequence patients mostly profit from the procedure but there is never a return to the functional level that existed before injury.ZusammenfassungSpätzustände ligamentärer Bandverletzungen können in 4 Themenkomplexe unterteilt werden: Bewegungseinschränkungen, knöcherne Fehlstellungen, ligamentäre Instabilitäten und Knorpel-/Meniskusschäden. Das Behandlungskonzept umfasst die systematische Erfassung der knöchernen Deformität, ligamentären Instabilität und der Knorpelschäden. Die Therapie erfolgt differenziert und stufenweise und erfordert eine prolongierte Rehabilitation. Die Limitierung des Endergebnisses durch die Schwere der Verletzung muss dabei sowohl dem Behandler, als auch dem Patienten bewusst sein.AbstractComplex ligament injuries can compromise a knee joint and residual conditions comprise stiffness (arthrofibrosis), instability, cartilage damage leading to osteoarthritis and bone deformity. Accurate diagnosis must address the direction and extent of the instability, the severity of any cartilage lesion and an analysis of the axis and bone deformity as well as important cofactors. Therapeutic options are adhesiolysis, ligament reconstruction, cartilage regeneration and axis correction. As a consequence patients mostly profit from the procedure but there is never a return to the functional level that existed before injury.

Spätzustände nach komplexer Bandverletzung am Kniegelenk

Complex ligament injuries can compromise a knee joint and residual conditions comprise stiffness (arthrofibrosis), instability, cartilage damage leading to osteoarthritis and bone deformity. Accurate diagnosis must address the direction and extent of the instability, the severity of any cartilage lesion and an analysis of the axis and bone deformity as well as important cofactors. Therapeutic options are adhesiolysis, ligament reconstruction, cartilage regeneration and axis correction. As a consequence patients mostly profit from the procedure but there is never a return to the functional level that existed before injury.ZusammenfassungSpätzustände ligamentärer Bandverletzungen können in 4 Themenkomplexe unterteilt werden: Bewegungseinschränkungen, knöcherne Fehlstellungen, ligamentäre Instabilitäten und Knorpel-/Meniskusschäden. Das Behandlungskonzept umfasst die systematische Erfassung der knöchernen Deformität, ligamentären Instabilität und der Knorpelschäden. Die Therapie erfolgt differenziert und stufenweise und erfordert eine prolongierte Rehabilitation. Die Limitierung des Endergebnisses durch die Schwere der Verletzung muss dabei sowohl dem Behandler, als auch dem Patienten bewusst sein.AbstractComplex ligament injuries can compromise a knee joint and residual conditions comprise stiffness (arthrofibrosis), instability, cartilage damage leading to osteoarthritis and bone deformity. Accurate diagnosis must address the direction and extent of the instability, the severity of any cartilage lesion and an analysis of the axis and bone deformity as well as important cofactors. Therapeutic options are adhesiolysis, ligament reconstruction, cartilage regeneration and axis correction. As a consequence patients mostly profit from the procedure but there is never a return to the functional level that existed before injury.