- Email: [email protected]
UKR—time for caution?
The Knee 11 (2004) 337 – 339 www.elsevier.com/locate/knee
Editorial review
UKR—time for caution? J.H. Newman* 2 Clifton Park, Clifton, Bristol BS8 3BS, United Kingdom Accepted 11 June 2004
Shortly before taking over as editor of The Knee in 2000, I wrote a review article on unicompartmental knee replacement [1]. I make no apology for doing so again just before relinquishing the Editor’s position, because so much has changed in the last 5 years. The initial review was largely concerned with whether unicompartmental replacement was a reasonable procedure to undertake. In the USA, UK and Australia, there has been a major increase in the prevalence of this procedure, which had always been more popular in mainland Europe. Large numbers of UKRs are now being inserted by surgeons of varying experience, which inevitably means more failures are occurring. Debate now centres not on whether UKR should be performed but on the specific indications, which type, by whom and with what expectation; particularly in relation to rapidity of rehabilitation, function and long-term survivorship. Undoubtedly the current enthusiasm for minimally invasive surgery (MIS) has been a major factor in the recent explosion of interest. This was perhaps initiated by Reppici and Eberle [2] and followed by others. Although rehabilitation is faster if an incision which does not violate the quadriceps is used [3], the procedure is more difficult. Price et al. [4] have demonstrated an ability of their experienced surgeons to insert the Oxford UKR as accurately through a minimal incision as through a traditional one, but the same unit has shown less satisfactory results with the Oxford UKR when performed by an inexperienced surgeon [5], and Fisher et al. [6] have shown less accurate placement when using a minimally invasive approach. Jenny and Boeri [7] have shown that consistently accurate alignment can be obtained using computer-assisted navigation, and it may well be that the use of this technique will prove of great value when inserting a UKR through a * Tel.: +44 117 9064213; fax: +44 117 973 0887. E-mail address: [email protected]. 0968-0160/$ - see front matter D 2004 Published by Elsevier B.V. doi:10.1016/j.knee.2004.06.002
minimally invasive approach. However, increased complication rates have been reported with MIS hip replacement, and because the function is the same by six weeks post-op, the use of MIS, rather than the implants performance, should perhaps be questioned. UKRs have traditionally been advocated purely for patients with isolated unicompartmental disease, but recently Hendel et al. [8] have advocated its use in lowdemand elderly patients with tricompartmental disease because of the short incision, low blood loss and easier rehabilitation. However, most surgeons would feel that a TKR would serve the patient well. At the other end of the scale, Hallock and Fell [9] propose the use of the Uni spacer (Centre Pulse Orthopaedics) as a bridging procedure in 35to 55-year olds even if mild arthritic changes exist elsewhere; however, their reported complication rate was high especially in their initial group of patients when dislocation appeared to be a major problem. As with total knee replacement, debate continues about the relative merits of fixed- and mobile-bearing UKR with respect to wear rates, kinematics, longevity and complications. Traditionally, it has been felt that fixed-bearing UKRs would wear and fail especially in younger patients, but recent publications have suggested this is not necessarily so and have demonstrated a 95% 10-year survivorship with the Marmor prosthesis [10] and a 92% 11-year survivorship in patients aged 60 or less using the Miller– Galante UKR system [11]. Although these results are not as good as a 97% 10-year survivorship reported with the Oxford mobilebearing UKR [12], not everyone seems able to obtain similar results [13], and Robertsson et al. [14] have pointed out that mobile-bearing UKR is a technically demanding procedure, and unless surgeons perform an adequate number, the results are likely to be inferior; although, the paper from Keys et al. [15] demonstrates that this is not inevitable.
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J.H. Newman / The Knee 11 (2004) 337–339
Fixed-bearing UKRs would be expected to wear at a fast rate, and polyethylene wear is a cause of failure in most series. However, Ashraf et al. [16] have shown a surprisingly low rate of wear, which would fit with the good 10-year survivorships being reported. Interestingly, although the linear or penetrative wear is substantially greater than that reported for the fully congruent mobilebearing Oxford UKR, the volumetric wear is a little different [17], perhaps because of the very large contact area with the mobile-bearing prosthesis. Wear rates are going to be of increasing importance as younger patients place greater demands on their prosthesis; hence, it is gratifying to see the development of an in vivo method which can perhaps monitor this potential problem in the future [18]. In addition, the shelf age of the polyethylene has recently been emphasized as a factor affecting UKR survival [29]. Although many papers have reported the outcome of Oxford mobile-bearing UKR, virtually no literature exists about other mobile-bearing devices. Preliminary innovators results for the AMC UKR were published in 2001 [19], but little data exists for the LCS UKR, which has also been in existence for many years. It is therefore gratifying to be able to report the 5-year results from a surgeon with considerable experience of this device [20]. Also in this issue, Saxler et al. [21] outline the principles of the AMC UKR, which is based on an attempt to replicate normal anatomy and uses TiN surface coating, which should reduce polyethylene wear further [22]. The 5-year results reported are commendable especially as a number of lateral UKRs are included. However, whether the results of these technically demanding mobile-bearing UKRs will prove superior to a modern fixed-bearing device remains to be seen. Emerson et al. [23] in a nonrandomised comparative study showed better survivorship for the mobile-bearing device at 11 years, but in a properly controlled trial from Milan, there was no difference between a fixed and mobile prosthesis at 5 years [24]. The Bristol study showed more complications amongst the mobile-bearing group in a short follow-up [25], although this may yet be balanced by better long-term survivorship. However, with the large number of UKRs being performed, complications are inevitable, particularly when more technically demanding mobile-bearing prostheses are used. In this issue Vardi and Strover [26] give a very honest account of problems which can occur, although it must be noted that many of their cases were performed for somewhat bextendedQ indications. Undoubtedly, the results of UKR can be most gratifying with near normal kinematics, rapid recovery and better function including kneeling ability [27]. In addition, the cost is less than TKR [28]. However, mobile-bearing UKR is a technically demanding procedure, particularly when used with a minimally invasive incision. There is probably nothing to be gained by using a mobile bearing in an elderly patient, although there may be in the younger group.
I believe UKR systems need to evolve to offer both options with the same instruments so that familiarity is maintained, but the additional risks of a mobile-bearing implant can be avoided in the less-energetic patient. Undoubtedly, UKR is here to stay, but possibly the current surgical enthusiasm for the procedure needs to be reined back if too many problems are not to be produced. It also behoves surgeons to remember the strict indications traditionally required for UKR, that initially minimally invasive approaches should be used with caution and that adequate training in the use of new systems is essential [20]. J H Newman-avon Orthopaedic Centre, Bristol.
References [1] Newman JH. Unicompartmental knee replacement. Knee 2000;7: 63 – 70. [2] Reppici JA, Eberle RW. Minimally McVarne invasive technique for unicondylar knee arthroplasty. J South Orthop Assoc 1999;8:20 – 7. [3] Beard DJ, Murray DW, Rees JL, Price AJ, Dodd CAF. Accelerated recovery for unicompartmental knee replacement. Knee 2002;9: 221 – 224. [4] Price AJ, Webb J, Toh H, Dodd CA, Goodfellow JW, Murray DW. Rapid recovery after Oxford unicompartmental arthroplasty through a short incision. J Arthroplasty 2001;16:970 – 6. [5] Rees J.L., Price A.J., Beard D.J., Dodd C.A., Murray D.W.. Minimally invasive Oxford unicompartmental knee, arthroplasty: functional results at 1 year and the effect of surgical inexperience. Knee 2004;11: S0968-0160(04)00007-9. [6] Fisher DA, Watts M, Davis KE. Implant position in knee surgery: a comparison of minimally invasive, open unicompartmental and total knee arthroplasty. J Arthroplasty 2003;18:2 – 8. [7] Jenny JY, Boeri C. Unicompartmental knee prosthesis implantation with a non-image-based navigator system: rationale, technique, casecontrol comparative study with a conventional instrumented implantation. Knee Surg Sports Traumatol Arthrosc 2003;11:40 – 5. [8] Hendel D, Beloosesky Y, Gart A, Weisbort M. Medial unicompartmental replacement for tricompartmental disease in the elderly. Knee 2003;10:363 – 5. [9] Hallock RH, Fell BM. Metallic tibial hemi-arthroplasty utilizing the Unispacer Knee system. Tech Knee Surg 2003;2:200 – 12. [10] Yang S, Hadlow S. Unicompartmental knee arthroplasty: is it durable? N Z Med J 2003;116:627. [11] Pennington DW, Swienckowski JJ, Lutes WB, Drake GN. Unicompartmental knee arthroplasty in patients sixty years of age or younger. J Bone Joint Surg 2003;85A:1968 – 73. [12] Murray D.W., Goodfellow J.W., O’Connor J.J.. The Oxford medial unicompartmental arthroplasty: a ten-year survical study. J Bone Joint Surg 1998;80B:983 – 9. [13] Lewold S, Goodman S, Knutson K, Robertsson O, Lidgren L. Oxford meniscal bearing knee vs. the Marmor knee in unicompartmental arthroplasty for arthrosis. A Swedish Multicentre survival study. J Arthroplasty 1995;10:722 – 31. [14] Robertsson O, Knutson K, Lewold S, Lidgren L. The routine of surgical management reduces failure after unicompartmental knee arthroplasty. J Bone Joint Surg 2001;83:45 – 9. [15] Keys GW, Abiddin ZU, Toh EM. Analysis of the first forty Oxford medial unicompartmental knee replacements from a small District General Hospital. Knee 2004;11:5. [16] Ashraf T, Newman JH, Desai V, Beard D, Nevelos JE. Polyethylene wear in a non congruous unicompartmental knee replacement. Knee 2004;11:177 – 81.
J.H. Newman / The Knee 11 (2004) 337–339 [17] Psychoygios V, Crawford RW, O’Connor JJ, Murray DW. Wear of congruent meniscal bearings in unicompartmental arthroplasty. J Bone Joint Surg 1998;80B:976 – 82. [18] Kellett CF, Short A, Price A, Gill HS, Murray DW. In vivo measurement of total knee replacement wear. Knee 2004;11:183 – 7. [19] Bontemps G, Temmen D. Mid term results with the AMC Unicondylar prosthesis. Orthop Prax 2001;8:543 – 6 (German). [20] Jeer P.J.S., Keene G.C.R., Gill P.. LCS Unicompartmental knee replacementanalysis of survivorship and failures after initial introduction. Knee 2004;11: S0968-0160(04)00129-2. [21] Saxter G, Temmen D, Bontemps G. Medium term results of the AMC unicompartmental knee, arthroplasty. Knee 2004;11. [22] Nevelos J. Surface engineering of prosthetic knee components. Knee 2004;11:163 – 7. [23] Emerson Jr RJ, Hansborough J, Reiman RD, Rosenfeldt W, Higgins JL. Comparison of a mobile with a fixed-bearing unicompartmental knee implant. Clin Orthop 2002;404(108):12.
339
[24] Confalomieri N., Manzotti A., Pullen C.. Comparison of a mobile with a fixed bearing unicompartmental knee prosthesis. Knee 2004;11: S0968-0160(04)00018-3. [25] Newman J.H., Gleeson R.E., Evans R., Ackroyd C.E., Webb J.N.. Fixed or mobile unicompartmental knee replacement. Knee 2004;11: S0968-0160(04)00132-2. [26] Vardi G., Stover A.E.. Early complications of unicompartmental knee replacement. Knee 2004;11: S0968-0160(04)00078-X. [27] Porteous AJ, Hassaballa MA, Newman JH. Can knees kneel? Kneeling ability after total, unicompartmental and patello-femoral arthroplasty. Knee 2003;10:155 – 60. [28] Shakespeare D, Jeffcote B. Unicondylar arthroplasty of the kneecheap at half the price? Knee 2003;10:357 – 61. [29] Collier MB, Engh CA, Engh GA. Shelf age of the polyethylene tibial component and outcome of unicondylar knee arthroplasty. J Bone Joint Surg 2004;86A:763 – 9.
Editorial review
UKR—time for caution? J.H. Newman* 2 Clifton Park, Clifton, Bristol BS8 3BS, United Kingdom Accepted 11 June 2004
Shortly before taking over as editor of The Knee in 2000, I wrote a review article on unicompartmental knee replacement [1]. I make no apology for doing so again just before relinquishing the Editor’s position, because so much has changed in the last 5 years. The initial review was largely concerned with whether unicompartmental replacement was a reasonable procedure to undertake. In the USA, UK and Australia, there has been a major increase in the prevalence of this procedure, which had always been more popular in mainland Europe. Large numbers of UKRs are now being inserted by surgeons of varying experience, which inevitably means more failures are occurring. Debate now centres not on whether UKR should be performed but on the specific indications, which type, by whom and with what expectation; particularly in relation to rapidity of rehabilitation, function and long-term survivorship. Undoubtedly the current enthusiasm for minimally invasive surgery (MIS) has been a major factor in the recent explosion of interest. This was perhaps initiated by Reppici and Eberle [2] and followed by others. Although rehabilitation is faster if an incision which does not violate the quadriceps is used [3], the procedure is more difficult. Price et al. [4] have demonstrated an ability of their experienced surgeons to insert the Oxford UKR as accurately through a minimal incision as through a traditional one, but the same unit has shown less satisfactory results with the Oxford UKR when performed by an inexperienced surgeon [5], and Fisher et al. [6] have shown less accurate placement when using a minimally invasive approach. Jenny and Boeri [7] have shown that consistently accurate alignment can be obtained using computer-assisted navigation, and it may well be that the use of this technique will prove of great value when inserting a UKR through a * Tel.: +44 117 9064213; fax: +44 117 973 0887. E-mail address: [email protected]. 0968-0160/$ - see front matter D 2004 Published by Elsevier B.V. doi:10.1016/j.knee.2004.06.002
minimally invasive approach. However, increased complication rates have been reported with MIS hip replacement, and because the function is the same by six weeks post-op, the use of MIS, rather than the implants performance, should perhaps be questioned. UKRs have traditionally been advocated purely for patients with isolated unicompartmental disease, but recently Hendel et al. [8] have advocated its use in lowdemand elderly patients with tricompartmental disease because of the short incision, low blood loss and easier rehabilitation. However, most surgeons would feel that a TKR would serve the patient well. At the other end of the scale, Hallock and Fell [9] propose the use of the Uni spacer (Centre Pulse Orthopaedics) as a bridging procedure in 35to 55-year olds even if mild arthritic changes exist elsewhere; however, their reported complication rate was high especially in their initial group of patients when dislocation appeared to be a major problem. As with total knee replacement, debate continues about the relative merits of fixed- and mobile-bearing UKR with respect to wear rates, kinematics, longevity and complications. Traditionally, it has been felt that fixed-bearing UKRs would wear and fail especially in younger patients, but recent publications have suggested this is not necessarily so and have demonstrated a 95% 10-year survivorship with the Marmor prosthesis [10] and a 92% 11-year survivorship in patients aged 60 or less using the Miller– Galante UKR system [11]. Although these results are not as good as a 97% 10-year survivorship reported with the Oxford mobilebearing UKR [12], not everyone seems able to obtain similar results [13], and Robertsson et al. [14] have pointed out that mobile-bearing UKR is a technically demanding procedure, and unless surgeons perform an adequate number, the results are likely to be inferior; although, the paper from Keys et al. [15] demonstrates that this is not inevitable.
338
J.H. Newman / The Knee 11 (2004) 337–339
Fixed-bearing UKRs would be expected to wear at a fast rate, and polyethylene wear is a cause of failure in most series. However, Ashraf et al. [16] have shown a surprisingly low rate of wear, which would fit with the good 10-year survivorships being reported. Interestingly, although the linear or penetrative wear is substantially greater than that reported for the fully congruent mobilebearing Oxford UKR, the volumetric wear is a little different [17], perhaps because of the very large contact area with the mobile-bearing prosthesis. Wear rates are going to be of increasing importance as younger patients place greater demands on their prosthesis; hence, it is gratifying to see the development of an in vivo method which can perhaps monitor this potential problem in the future [18]. In addition, the shelf age of the polyethylene has recently been emphasized as a factor affecting UKR survival [29]. Although many papers have reported the outcome of Oxford mobile-bearing UKR, virtually no literature exists about other mobile-bearing devices. Preliminary innovators results for the AMC UKR were published in 2001 [19], but little data exists for the LCS UKR, which has also been in existence for many years. It is therefore gratifying to be able to report the 5-year results from a surgeon with considerable experience of this device [20]. Also in this issue, Saxler et al. [21] outline the principles of the AMC UKR, which is based on an attempt to replicate normal anatomy and uses TiN surface coating, which should reduce polyethylene wear further [22]. The 5-year results reported are commendable especially as a number of lateral UKRs are included. However, whether the results of these technically demanding mobile-bearing UKRs will prove superior to a modern fixed-bearing device remains to be seen. Emerson et al. [23] in a nonrandomised comparative study showed better survivorship for the mobile-bearing device at 11 years, but in a properly controlled trial from Milan, there was no difference between a fixed and mobile prosthesis at 5 years [24]. The Bristol study showed more complications amongst the mobile-bearing group in a short follow-up [25], although this may yet be balanced by better long-term survivorship. However, with the large number of UKRs being performed, complications are inevitable, particularly when more technically demanding mobile-bearing prostheses are used. In this issue Vardi and Strover [26] give a very honest account of problems which can occur, although it must be noted that many of their cases were performed for somewhat bextendedQ indications. Undoubtedly, the results of UKR can be most gratifying with near normal kinematics, rapid recovery and better function including kneeling ability [27]. In addition, the cost is less than TKR [28]. However, mobile-bearing UKR is a technically demanding procedure, particularly when used with a minimally invasive incision. There is probably nothing to be gained by using a mobile bearing in an elderly patient, although there may be in the younger group.
I believe UKR systems need to evolve to offer both options with the same instruments so that familiarity is maintained, but the additional risks of a mobile-bearing implant can be avoided in the less-energetic patient. Undoubtedly, UKR is here to stay, but possibly the current surgical enthusiasm for the procedure needs to be reined back if too many problems are not to be produced. It also behoves surgeons to remember the strict indications traditionally required for UKR, that initially minimally invasive approaches should be used with caution and that adequate training in the use of new systems is essential [20]. J H Newman-avon Orthopaedic Centre, Bristol.
References [1] Newman JH. Unicompartmental knee replacement. Knee 2000;7: 63 – 70. [2] Reppici JA, Eberle RW. Minimally McVarne invasive technique for unicondylar knee arthroplasty. J South Orthop Assoc 1999;8:20 – 7. [3] Beard DJ, Murray DW, Rees JL, Price AJ, Dodd CAF. Accelerated recovery for unicompartmental knee replacement. Knee 2002;9: 221 – 224. [4] Price AJ, Webb J, Toh H, Dodd CA, Goodfellow JW, Murray DW. Rapid recovery after Oxford unicompartmental arthroplasty through a short incision. J Arthroplasty 2001;16:970 – 6. [5] Rees J.L., Price A.J., Beard D.J., Dodd C.A., Murray D.W.. Minimally invasive Oxford unicompartmental knee, arthroplasty: functional results at 1 year and the effect of surgical inexperience. Knee 2004;11: S0968-0160(04)00007-9. [6] Fisher DA, Watts M, Davis KE. Implant position in knee surgery: a comparison of minimally invasive, open unicompartmental and total knee arthroplasty. J Arthroplasty 2003;18:2 – 8. [7] Jenny JY, Boeri C. Unicompartmental knee prosthesis implantation with a non-image-based navigator system: rationale, technique, casecontrol comparative study with a conventional instrumented implantation. Knee Surg Sports Traumatol Arthrosc 2003;11:40 – 5. [8] Hendel D, Beloosesky Y, Gart A, Weisbort M. Medial unicompartmental replacement for tricompartmental disease in the elderly. Knee 2003;10:363 – 5. [9] Hallock RH, Fell BM. Metallic tibial hemi-arthroplasty utilizing the Unispacer Knee system. Tech Knee Surg 2003;2:200 – 12. [10] Yang S, Hadlow S. Unicompartmental knee arthroplasty: is it durable? N Z Med J 2003;116:627. [11] Pennington DW, Swienckowski JJ, Lutes WB, Drake GN. Unicompartmental knee arthroplasty in patients sixty years of age or younger. J Bone Joint Surg 2003;85A:1968 – 73. [12] Murray D.W., Goodfellow J.W., O’Connor J.J.. The Oxford medial unicompartmental arthroplasty: a ten-year survical study. J Bone Joint Surg 1998;80B:983 – 9. [13] Lewold S, Goodman S, Knutson K, Robertsson O, Lidgren L. Oxford meniscal bearing knee vs. the Marmor knee in unicompartmental arthroplasty for arthrosis. A Swedish Multicentre survival study. J Arthroplasty 1995;10:722 – 31. [14] Robertsson O, Knutson K, Lewold S, Lidgren L. The routine of surgical management reduces failure after unicompartmental knee arthroplasty. J Bone Joint Surg 2001;83:45 – 9. [15] Keys GW, Abiddin ZU, Toh EM. Analysis of the first forty Oxford medial unicompartmental knee replacements from a small District General Hospital. Knee 2004;11:5. [16] Ashraf T, Newman JH, Desai V, Beard D, Nevelos JE. Polyethylene wear in a non congruous unicompartmental knee replacement. Knee 2004;11:177 – 81.
J.H. Newman / The Knee 11 (2004) 337–339 [17] Psychoygios V, Crawford RW, O’Connor JJ, Murray DW. Wear of congruent meniscal bearings in unicompartmental arthroplasty. J Bone Joint Surg 1998;80B:976 – 82. [18] Kellett CF, Short A, Price A, Gill HS, Murray DW. In vivo measurement of total knee replacement wear. Knee 2004;11:183 – 7. [19] Bontemps G, Temmen D. Mid term results with the AMC Unicondylar prosthesis. Orthop Prax 2001;8:543 – 6 (German). [20] Jeer P.J.S., Keene G.C.R., Gill P.. LCS Unicompartmental knee replacementanalysis of survivorship and failures after initial introduction. Knee 2004;11: S0968-0160(04)00129-2. [21] Saxter G, Temmen D, Bontemps G. Medium term results of the AMC unicompartmental knee, arthroplasty. Knee 2004;11. [22] Nevelos J. Surface engineering of prosthetic knee components. Knee 2004;11:163 – 7. [23] Emerson Jr RJ, Hansborough J, Reiman RD, Rosenfeldt W, Higgins JL. Comparison of a mobile with a fixed-bearing unicompartmental knee implant. Clin Orthop 2002;404(108):12.
339
[24] Confalomieri N., Manzotti A., Pullen C.. Comparison of a mobile with a fixed bearing unicompartmental knee prosthesis. Knee 2004;11: S0968-0160(04)00018-3. [25] Newman J.H., Gleeson R.E., Evans R., Ackroyd C.E., Webb J.N.. Fixed or mobile unicompartmental knee replacement. Knee 2004;11: S0968-0160(04)00132-2. [26] Vardi G., Stover A.E.. Early complications of unicompartmental knee replacement. Knee 2004;11: S0968-0160(04)00078-X. [27] Porteous AJ, Hassaballa MA, Newman JH. Can knees kneel? Kneeling ability after total, unicompartmental and patello-femoral arthroplasty. Knee 2003;10:155 – 60. [28] Shakespeare D, Jeffcote B. Unicondylar arthroplasty of the kneecheap at half the price? Knee 2003;10:357 – 61. [29] Collier MB, Engh CA, Engh GA. Shelf age of the polyethylene tibial component and outcome of unicondylar knee arthroplasty. J Bone Joint Surg 2004;86A:763 – 9.