- Email: [email protected]
Restoring the joint line in revision TKA: does it matter?
The Knee 11 (2004) 3–5
Review
Restoring the joint line in revision TKA: does it matter? J. Bellemans* Department of Orthopaedic Surgery, University Hospital Pellenberg, Katholieke Universiteit Leuven, Weligerveld 1, 3012 Pellenberg, Belgium Received 10 April 2003; accepted 6 June 2003
Abstract The importance of joint line restoration in revision TKA is much debated today. This review paper gives an overview of the reasons why joint line elevation occurs so frequently in contemporary revision TKAs, what the theoretical and clinical consequences are of an elevated joint line and how it can be avoided. 䊚 2003 Elsevier B.V. All rights reserved. Keywords: Revision TKA; Joint line; Elevation
1. Introduction It seems logical that restoration of the normal joint line position should be attempted both in primary and revision total knee arthroplasty. Normal knee kinematics indeed require a correct interrelationship between the bony anatomy and the surrounding soft tissues. In recent years it has, however, become clear that even in patients with well performed primary knee arthroplasty, normal knee function and kinematics cannot generally be obtained despite correct restoration of the joint line position. It can, therefore, be questioned whether restoration of the joint line is indeed so important in revision TKA, especially since this is not always so easily achievable in the revision situation. 2. Why does joint line elevation occur in revision TKA? In revision TKA there is a natural tendency for the surgeon to proximalise the joint line w1,2x. There are three main reasons for this. First of all, there is always *Tel.: q32-16-33-88-00; fax: q32-16-56-45-36. E-mail address: [email protected] (J. Bellemans).
inevitable distal femoral bone loss, even after gentle removal of the primary femoral component. Secondly, the surgeon has the tendency to undersize the femoral component in revision TKA. This is the consequence of the fact that after extraction of the primary femoral component, the surgeon will also be faced with posterior bone loss, and will have a tendency to choose a smaller femoral component size in order to obtain direct seating of the component against the remaining bone (Fig. 1). To obtain stability both in flexion and extension, the use of a thicker tibial insert will subsequently be needed, leading to proximalisation of the joint line. The third reason is that in revision TKA the surgeon will commonly be confronted with a relatively larger flexion space after component removal and joint debridement, compared to the extension space. This occurs because of the fact that in the revision situation the capsuloligamentous structures that are effective in extension are usually much better preserved than those that control the knee in flexion. The surgeon may, therefore, decide to fill up the flexion space by using a thicker insert and compensatory increase of the extension space by proximalising the femoral component, in order to obtain a balanced flexion and extension gap, resulting in elevation of the joint line. The use of a straight diaphyseal femoral fixation stem may further increase this tendency towards an excessive flexion gap, since
0968-0160/04/$ - see front matter 䊚 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0968-0160Ž03.00099-1
4
J. Bellemans / The Knee 11 (2004) 3–5
Fig. 1. After removal of the primary components, the surgeon has a natural tendency to choose an undersized femoral component to achieve direct bone contact. This leads to an increased flexion space, and requires proximalisation of the femur to balance the flexion and extension gaps.
these stems tend to position the femoral component anteriorly and increase the flexion space (Fig. 2). In this circumstance as well, a stable and functional joint can be obtained if the surgeon is prepared to use a thick polyethylene insert and accept an elevated joint line. 3. Is elevation of the joint line bad? Today it is not fully clear what the consequences are of joint line elevation. Certainly there are some theoretical concerns. Optimal knee joint function obviously requires a delicate balance between the osseous anatomy and the surrounding soft tissues, which is dramatically distorted in the case of joint line elevation. This may lead to both tibiofemoral and patellofemoral dysfunctioning w2–4x. Impingement of the inferior pole of the patella against the tibial insert can occur, as well as impingement of the patellar tendon against the front of
Fig. 2. A straight diaphyseal stem provokes anterior seating of the femoral component, and also leads to an increased flexion space.
the tibial component, causing pain, structural tendon damage and limited knee flexion w5x. A number of clinical retrospective data have to some extent confirmed some of these concerns. Partington et al. noted in a study of 99 revision patients a marginal statistical difference in clinical score in cases with more than 8 mm joint line elevation, but failed to find a direct correlation between joint line elevation and clinical performance w1x. Much earlier in 1986, Figgie et al. had noted in their classical paper on primary TKA a significant correlation between joint line elevation and knee score, range of motion and anterior knee pain w6x. Apart from these studies, no other data are available that show an important impact of joint line elevation on the clinical outcome after revision TKA w7x. In a personal review of 86 revision knees at our institution, we failed to detect any correlation between joint line elevation and any clinical parameter, not even after stratification for diagnosis, magnitude of joint line elevation, patellar height, etc. 4. How to avoid joint line elevation? Although based upon the above-mentioned clinical data some joint line elevation may be considered as not necessarily detrimental to clinical performance, it is generally believed that excessive joint line elevation should be avoided if possible. To do so, the surgeon needs to overcome his tendency to undersize the femoral component, and secondly, he should attempt to control the size of the flexion space. This can be achieved with the help of the following surgical tips: (1) Choosing the correct femoral component size should not be based upon the remaining anteroposterior bone stock, but rather upon the mediolateral dimension of the condylar bone. The size of the removed femoral component can be used as an extra control. If in-between two sizes, choose the largest size. (2) Keep the flexion space as small as possible. Bring the femoral component, therefore, as posterior as possible without notching. When a femoral fixation stem is used, consider an offset-stem or a thinner stem to avoid anteriorisation of the femoral component. (3) Consider the systematical use of distal femoral component augments in your revision TKAs. Remember that in 80% of current TKA revisions, proximalistion of the joint line occurs w1x. The appropriate thickness of the augment can be based upon the knowledge that the normal joint line lies approximately 25 mm distal to the medial femoral epicondyle and 10 mm proximal to the fibular head w2x.
J. Bellemans / The Knee 11 (2004) 3–5
(4) In case of persistent problems of flexion space laxity after joint line restoration with distal femoral augments, consider one of the two following compromises: (a) the use of a mediolateral constraint (CCKtype) implant to guarantee stability in flexion, or (b) increase the extension space until balanced with the flexion space by proximalising the femoral component and accepting elevation of the joint line. 5. Conclusion Joint line elevation is today seen in most revision TKA patients. Although there are certainly valid theoretical concerns, this does not seem to lead to detrimental clinical consequences, at least not in cases with moderate elevation (under 8 mm). More dramatic joint line proximalisation can in most cases be avoided using the above-mentioned principles.
5
References w1x Partington P, Sawhney J, Rorabeck C, Barrack R, Moore J. Joint line restoration after revision total knee arthroplasty. Clin Orthop 1999;367:165 –171. w2x Laskin R. Joint line position restoration during revision total knee replacement. Clin Orthop 2002;404:169 –171. w3x Martin J, Whiteside L. The influence of joint line position on knee stability after condylar knee arthroplasty. Clin Orthop 1990;259:146 –156. w4x Singerman R, Heiple K, Davy D, Goldberg V. Effect of tibial component position on patellar strain following total knee arthroplasty. J Arthropl 1995;10:651 –656. w5x Yoshii I, Whiteside L, White L, Milliano M. Influence of prosthetic joint line position on knee kinematics and patellar position. J Arthropl 1991;6:169 –177. w6x Figgie H, Goldberg V, Heiple K, Moller H, Gordon N. The influence of tibial patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis. J Bone Joint Surg Part A 1986;68:1035 –1040. w7x Grelsamer R. Patella baja after total knee arthroplasty. Is it really patella baja? J Arthropl 2002;17:66 –69.
Review
Restoring the joint line in revision TKA: does it matter? J. Bellemans* Department of Orthopaedic Surgery, University Hospital Pellenberg, Katholieke Universiteit Leuven, Weligerveld 1, 3012 Pellenberg, Belgium Received 10 April 2003; accepted 6 June 2003
Abstract The importance of joint line restoration in revision TKA is much debated today. This review paper gives an overview of the reasons why joint line elevation occurs so frequently in contemporary revision TKAs, what the theoretical and clinical consequences are of an elevated joint line and how it can be avoided. 䊚 2003 Elsevier B.V. All rights reserved. Keywords: Revision TKA; Joint line; Elevation
1. Introduction It seems logical that restoration of the normal joint line position should be attempted both in primary and revision total knee arthroplasty. Normal knee kinematics indeed require a correct interrelationship between the bony anatomy and the surrounding soft tissues. In recent years it has, however, become clear that even in patients with well performed primary knee arthroplasty, normal knee function and kinematics cannot generally be obtained despite correct restoration of the joint line position. It can, therefore, be questioned whether restoration of the joint line is indeed so important in revision TKA, especially since this is not always so easily achievable in the revision situation. 2. Why does joint line elevation occur in revision TKA? In revision TKA there is a natural tendency for the surgeon to proximalise the joint line w1,2x. There are three main reasons for this. First of all, there is always *Tel.: q32-16-33-88-00; fax: q32-16-56-45-36. E-mail address: [email protected] (J. Bellemans).
inevitable distal femoral bone loss, even after gentle removal of the primary femoral component. Secondly, the surgeon has the tendency to undersize the femoral component in revision TKA. This is the consequence of the fact that after extraction of the primary femoral component, the surgeon will also be faced with posterior bone loss, and will have a tendency to choose a smaller femoral component size in order to obtain direct seating of the component against the remaining bone (Fig. 1). To obtain stability both in flexion and extension, the use of a thicker tibial insert will subsequently be needed, leading to proximalisation of the joint line. The third reason is that in revision TKA the surgeon will commonly be confronted with a relatively larger flexion space after component removal and joint debridement, compared to the extension space. This occurs because of the fact that in the revision situation the capsuloligamentous structures that are effective in extension are usually much better preserved than those that control the knee in flexion. The surgeon may, therefore, decide to fill up the flexion space by using a thicker insert and compensatory increase of the extension space by proximalising the femoral component, in order to obtain a balanced flexion and extension gap, resulting in elevation of the joint line. The use of a straight diaphyseal femoral fixation stem may further increase this tendency towards an excessive flexion gap, since
0968-0160/04/$ - see front matter 䊚 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0968-0160Ž03.00099-1
4
J. Bellemans / The Knee 11 (2004) 3–5
Fig. 1. After removal of the primary components, the surgeon has a natural tendency to choose an undersized femoral component to achieve direct bone contact. This leads to an increased flexion space, and requires proximalisation of the femur to balance the flexion and extension gaps.
these stems tend to position the femoral component anteriorly and increase the flexion space (Fig. 2). In this circumstance as well, a stable and functional joint can be obtained if the surgeon is prepared to use a thick polyethylene insert and accept an elevated joint line. 3. Is elevation of the joint line bad? Today it is not fully clear what the consequences are of joint line elevation. Certainly there are some theoretical concerns. Optimal knee joint function obviously requires a delicate balance between the osseous anatomy and the surrounding soft tissues, which is dramatically distorted in the case of joint line elevation. This may lead to both tibiofemoral and patellofemoral dysfunctioning w2–4x. Impingement of the inferior pole of the patella against the tibial insert can occur, as well as impingement of the patellar tendon against the front of
Fig. 2. A straight diaphyseal stem provokes anterior seating of the femoral component, and also leads to an increased flexion space.
the tibial component, causing pain, structural tendon damage and limited knee flexion w5x. A number of clinical retrospective data have to some extent confirmed some of these concerns. Partington et al. noted in a study of 99 revision patients a marginal statistical difference in clinical score in cases with more than 8 mm joint line elevation, but failed to find a direct correlation between joint line elevation and clinical performance w1x. Much earlier in 1986, Figgie et al. had noted in their classical paper on primary TKA a significant correlation between joint line elevation and knee score, range of motion and anterior knee pain w6x. Apart from these studies, no other data are available that show an important impact of joint line elevation on the clinical outcome after revision TKA w7x. In a personal review of 86 revision knees at our institution, we failed to detect any correlation between joint line elevation and any clinical parameter, not even after stratification for diagnosis, magnitude of joint line elevation, patellar height, etc. 4. How to avoid joint line elevation? Although based upon the above-mentioned clinical data some joint line elevation may be considered as not necessarily detrimental to clinical performance, it is generally believed that excessive joint line elevation should be avoided if possible. To do so, the surgeon needs to overcome his tendency to undersize the femoral component, and secondly, he should attempt to control the size of the flexion space. This can be achieved with the help of the following surgical tips: (1) Choosing the correct femoral component size should not be based upon the remaining anteroposterior bone stock, but rather upon the mediolateral dimension of the condylar bone. The size of the removed femoral component can be used as an extra control. If in-between two sizes, choose the largest size. (2) Keep the flexion space as small as possible. Bring the femoral component, therefore, as posterior as possible without notching. When a femoral fixation stem is used, consider an offset-stem or a thinner stem to avoid anteriorisation of the femoral component. (3) Consider the systematical use of distal femoral component augments in your revision TKAs. Remember that in 80% of current TKA revisions, proximalistion of the joint line occurs w1x. The appropriate thickness of the augment can be based upon the knowledge that the normal joint line lies approximately 25 mm distal to the medial femoral epicondyle and 10 mm proximal to the fibular head w2x.
J. Bellemans / The Knee 11 (2004) 3–5
(4) In case of persistent problems of flexion space laxity after joint line restoration with distal femoral augments, consider one of the two following compromises: (a) the use of a mediolateral constraint (CCKtype) implant to guarantee stability in flexion, or (b) increase the extension space until balanced with the flexion space by proximalising the femoral component and accepting elevation of the joint line. 5. Conclusion Joint line elevation is today seen in most revision TKA patients. Although there are certainly valid theoretical concerns, this does not seem to lead to detrimental clinical consequences, at least not in cases with moderate elevation (under 8 mm). More dramatic joint line proximalisation can in most cases be avoided using the above-mentioned principles.
5
References w1x Partington P, Sawhney J, Rorabeck C, Barrack R, Moore J. Joint line restoration after revision total knee arthroplasty. Clin Orthop 1999;367:165 –171. w2x Laskin R. Joint line position restoration during revision total knee replacement. Clin Orthop 2002;404:169 –171. w3x Martin J, Whiteside L. The influence of joint line position on knee stability after condylar knee arthroplasty. Clin Orthop 1990;259:146 –156. w4x Singerman R, Heiple K, Davy D, Goldberg V. Effect of tibial component position on patellar strain following total knee arthroplasty. J Arthropl 1995;10:651 –656. w5x Yoshii I, Whiteside L, White L, Milliano M. Influence of prosthetic joint line position on knee kinematics and patellar position. J Arthropl 1991;6:169 –177. w6x Figgie H, Goldberg V, Heiple K, Moller H, Gordon N. The influence of tibial patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis. J Bone Joint Surg Part A 1986;68:1035 –1040. w7x Grelsamer R. Patella baja after total knee arthroplasty. Is it really patella baja? J Arthropl 2002;17:66 –69.