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Orthopaedic crossfire®—Can we justify unicondylar arthroplasty as a temporizing procedure? In the affirmative
The Journal of Arthroplasty Vol. 17 No. 4 Suppl. 1 2002
Orthopaedic Crossfire姞
Can We Justify Unicondylar Arthroplasty as a Temporizing Procedure? In the Affirmative Gerard A. Engh, MD
In 1972, unicondylar knee arthroplasty (UKA) was introduced, along with total knee arthroplasty (TKA), as an option for managing gonarthrosis. Although the early clinical results with the first generation of implants were equivalent to those of total knee arthroplasty, little interest in UKA was sustained. If unicondylar arthroplasty is to realize a role in the management of degenerative arthritis, even as a temporizing procedure, the results must be predictable and reproducible. Patient satisfaction must be equivalent to or better than that of TKA. Finally, the conversion of UKA to TKA must be uncomplicated, avoiding complex reconstructive procedures and the use of revision implants. As documented in the literature, UKA achieves these goals. Therefore, we cannot only justify UKA as a temporizing procedure, but also as a definitive procedure with long-term results that are comparable to TKA for gonarthrosis. Key words: unicondylar arthroplasty, knee, gonarthrosis. Copyright 2002, Elsevier Science (USA). All rights reserved.
In 1972, unicondylar knee arthroplasty (UKA) was introduced in conjunction with total knee arthroplasty (TKA) as a management option for gonarthrosis. The early clinical results with the firstgeneration UKA implants were variable and not as predictable as the results with TKA. Surgeons sustained little interest in this surgical option. In addition, implant manufacturers had no incentive to
develop better instruments and implants for UKA when the alternative treatment option, a TKA, was more profitable. If UKA is to be considered a legitimate means of managing degenerative arthritis, the results must be predictable and reproducible. Patient satisfaction must be equivalent to, or better than, that with TKAs. Revision of a UKA to a TKA must be straightforward and should not require the use of revision implants or more complex reconstructive techniques.
From the Anderson Orthopaedic Research Institute, Alexandria, Virginia. The study received no outside funding. The author’s financial affiliations with DePuy, Johnson & Johnson Professional, Inc, did not influence the nature of the study. Reprint requests: Gerard A. Engh, MD, Anderson Orthopaedic Research Institute, 2501 Parker’s Lane, Alexandria, VA 22306. E-mail: [email protected] Copyright 2002, Elsevier Science (USA). All rights reserved. 0883-5403/02/1704-1006$35.00/0 doi:10.1054/arth.2002.32448
Results of Unicompartmental Arthroplasty Studies have shown that UKAs have resulted in less morbidity than TKAs, as documented by reduced blood loss [1] and less risk of infection [2]. Other reports have shown higher patient satisfac-
54
Justify Unicondylar Arthroplasty • Gerard A. Engh
tion. Patients with a UKA in one knee and a TKA in the other generally prefer the knee with the UKA [3], in terms of superior range of motion and better function with activities such as stair climbing. Patients with UKAs have reported less pain than patients with TKAs [1]. The durability and clinical results after UKAs have been shown to be comparable to TKAs. Berger et al [4] reported a 98% survival rate at 10 years for either loosening or revision. Murray et al [5] reported 98% survivorship at 10 years for 143 mobile bearing implants in patients with an intact anterior cruciate ligament. Squire et al [6] reported a 90% survivorship for 140 Marmor unicondylar implants (Richards, Memphis, TN) with a mean follow-up of 18 years. The survivorship for 124 Oxford unicondylar implants performed in nonteaching hospitals was 95% at 10 years (95% confidence interval, 90.8 –99.3) [7]. These reports confirm that UKA can be as durable as TKA.
Revision of Unicompartmental Arthroplasty Most studies have shown that revisions of failed UKAs can be successful with primary TKA components. In a report of failed UKAs by Padgett et al [8], primary components were used in all of the revision procedures. Of these primary implants, 93% were cruciate-retaining designs. At a mean 5-year follow-up, 2 of 19 knees required rerevision surgery. Experience at the Anderson Orthopaedic Research Institute was similar. Primary femoral components were used in all conversions, with 81% being cruciate-retaining components [9]. At a mean follow-up of 4.4 years, 1 of 32 UKA conversions required rerevision surgery. Two additional patients underwent polyethylene insert exchange at 76 and 102 months. To my knowledge, osteolysis with failed UKA has not been reported in the literature. The extent of bone damage observed in failed UKAs usually is confined to the medial tibial plateau and is caused by tibial component subsidence. If tibial bone defects are present, it is necessary to use a revision tibial component with proper bone defect management. Occasionally, stems and wedges are needed when such bone deficiency is encountered. McAuley et al [9] reported the use of stemmed tibial
55
components in 44% of UKA revisions and the use of tibial wedges in 25% of UKA revisions. Structural bone– grafts were not necessary in studies done by the Anderson Orthopaedic Research Institute [9] and by Padgett et al [8].
Conclusion A UKA may be appropriate for younger patients whose only alternative is a TKA because the option for conversion to a TKA is reasonable. UKA yields results comparable with TKAs. Because of the high level of patient satisfaction and the lower incidence of complications and morbidity compared with TKA, UKA is an attractive alternative for patients with predominantly unicompartmental, noninflammatory arthritis. Patient interest in UKA is enhanced by the adaptation of the operative procedure to a minimally invasive incision with the possibility of outpatient surgery.
References 1. Rougraff BT, Heck DA, Gibson AE: A comparison of tricompartmental and unicompartmental arthroplasty for the treatment of gonarthrosis. Clin Orthop 273: 157, 1991 2. Knutson K, Lindstrand A, Lidgren L: Survival of knee arthroplasties. A nation-wide multicentre investigation of 8000 cases. J Bone Joint Surg Br 68:795, 1986 3. Laurencin CT, Zelicof SB, Scott RD, Ewald FC: Unicompartmental versus total knee arthroplasty in the same patient. A comparative study. Clin Orthop 273: 151, 1991 4. Berger RA, Nedeff DD, Barden RM, et al: Unicompartmental knee arthroplasty: clinical experience at 6- to 10-year followup. Clin Orthop 367:50, 1999 5. Murray DW, Goodfellow JW, O’Connor JJ: The Oxford medial unicompartmental arthroplasty: a tenyear survival study. J Bone Joint Surg Br 80:983, 1998 6. Squire MW, Callaghan JJ, Goetz DD, et al: Unicompartmental knee replacement. A minimum 15-year followup study. Clin Orthop 367:61, 1999 7. Svard UC, Price AJ: Oxford medial unicompartmental knee arthroplasty. A survival analysis of an independent series. J Bone Joint Surg Br 83:191, 2001 8. Padgett DE, Stern SH, Insall JN: Revision total knee arthroplasty for failed unicompartmental replacement. J Bone Joint Surg Am 73:186, 1991 9. McAuley JP, Engh GA, Ammeen DJ: Revision of unicompartmental knee arthroplasty. Clin Orthop 392: 279, 2001
Orthopaedic Crossfire姞
Can We Justify Unicondylar Arthroplasty as a Temporizing Procedure? In the Affirmative Gerard A. Engh, MD
In 1972, unicondylar knee arthroplasty (UKA) was introduced, along with total knee arthroplasty (TKA), as an option for managing gonarthrosis. Although the early clinical results with the first generation of implants were equivalent to those of total knee arthroplasty, little interest in UKA was sustained. If unicondylar arthroplasty is to realize a role in the management of degenerative arthritis, even as a temporizing procedure, the results must be predictable and reproducible. Patient satisfaction must be equivalent to or better than that of TKA. Finally, the conversion of UKA to TKA must be uncomplicated, avoiding complex reconstructive procedures and the use of revision implants. As documented in the literature, UKA achieves these goals. Therefore, we cannot only justify UKA as a temporizing procedure, but also as a definitive procedure with long-term results that are comparable to TKA for gonarthrosis. Key words: unicondylar arthroplasty, knee, gonarthrosis. Copyright 2002, Elsevier Science (USA). All rights reserved.
In 1972, unicondylar knee arthroplasty (UKA) was introduced in conjunction with total knee arthroplasty (TKA) as a management option for gonarthrosis. The early clinical results with the firstgeneration UKA implants were variable and not as predictable as the results with TKA. Surgeons sustained little interest in this surgical option. In addition, implant manufacturers had no incentive to
develop better instruments and implants for UKA when the alternative treatment option, a TKA, was more profitable. If UKA is to be considered a legitimate means of managing degenerative arthritis, the results must be predictable and reproducible. Patient satisfaction must be equivalent to, or better than, that with TKAs. Revision of a UKA to a TKA must be straightforward and should not require the use of revision implants or more complex reconstructive techniques.
From the Anderson Orthopaedic Research Institute, Alexandria, Virginia. The study received no outside funding. The author’s financial affiliations with DePuy, Johnson & Johnson Professional, Inc, did not influence the nature of the study. Reprint requests: Gerard A. Engh, MD, Anderson Orthopaedic Research Institute, 2501 Parker’s Lane, Alexandria, VA 22306. E-mail: [email protected] Copyright 2002, Elsevier Science (USA). All rights reserved. 0883-5403/02/1704-1006$35.00/0 doi:10.1054/arth.2002.32448
Results of Unicompartmental Arthroplasty Studies have shown that UKAs have resulted in less morbidity than TKAs, as documented by reduced blood loss [1] and less risk of infection [2]. Other reports have shown higher patient satisfac-
54
Justify Unicondylar Arthroplasty • Gerard A. Engh
tion. Patients with a UKA in one knee and a TKA in the other generally prefer the knee with the UKA [3], in terms of superior range of motion and better function with activities such as stair climbing. Patients with UKAs have reported less pain than patients with TKAs [1]. The durability and clinical results after UKAs have been shown to be comparable to TKAs. Berger et al [4] reported a 98% survival rate at 10 years for either loosening or revision. Murray et al [5] reported 98% survivorship at 10 years for 143 mobile bearing implants in patients with an intact anterior cruciate ligament. Squire et al [6] reported a 90% survivorship for 140 Marmor unicondylar implants (Richards, Memphis, TN) with a mean follow-up of 18 years. The survivorship for 124 Oxford unicondylar implants performed in nonteaching hospitals was 95% at 10 years (95% confidence interval, 90.8 –99.3) [7]. These reports confirm that UKA can be as durable as TKA.
Revision of Unicompartmental Arthroplasty Most studies have shown that revisions of failed UKAs can be successful with primary TKA components. In a report of failed UKAs by Padgett et al [8], primary components were used in all of the revision procedures. Of these primary implants, 93% were cruciate-retaining designs. At a mean 5-year follow-up, 2 of 19 knees required rerevision surgery. Experience at the Anderson Orthopaedic Research Institute was similar. Primary femoral components were used in all conversions, with 81% being cruciate-retaining components [9]. At a mean follow-up of 4.4 years, 1 of 32 UKA conversions required rerevision surgery. Two additional patients underwent polyethylene insert exchange at 76 and 102 months. To my knowledge, osteolysis with failed UKA has not been reported in the literature. The extent of bone damage observed in failed UKAs usually is confined to the medial tibial plateau and is caused by tibial component subsidence. If tibial bone defects are present, it is necessary to use a revision tibial component with proper bone defect management. Occasionally, stems and wedges are needed when such bone deficiency is encountered. McAuley et al [9] reported the use of stemmed tibial
55
components in 44% of UKA revisions and the use of tibial wedges in 25% of UKA revisions. Structural bone– grafts were not necessary in studies done by the Anderson Orthopaedic Research Institute [9] and by Padgett et al [8].
Conclusion A UKA may be appropriate for younger patients whose only alternative is a TKA because the option for conversion to a TKA is reasonable. UKA yields results comparable with TKAs. Because of the high level of patient satisfaction and the lower incidence of complications and morbidity compared with TKA, UKA is an attractive alternative for patients with predominantly unicompartmental, noninflammatory arthritis. Patient interest in UKA is enhanced by the adaptation of the operative procedure to a minimally invasive incision with the possibility of outpatient surgery.
References 1. Rougraff BT, Heck DA, Gibson AE: A comparison of tricompartmental and unicompartmental arthroplasty for the treatment of gonarthrosis. Clin Orthop 273: 157, 1991 2. Knutson K, Lindstrand A, Lidgren L: Survival of knee arthroplasties. A nation-wide multicentre investigation of 8000 cases. J Bone Joint Surg Br 68:795, 1986 3. Laurencin CT, Zelicof SB, Scott RD, Ewald FC: Unicompartmental versus total knee arthroplasty in the same patient. A comparative study. Clin Orthop 273: 151, 1991 4. Berger RA, Nedeff DD, Barden RM, et al: Unicompartmental knee arthroplasty: clinical experience at 6- to 10-year followup. Clin Orthop 367:50, 1999 5. Murray DW, Goodfellow JW, O’Connor JJ: The Oxford medial unicompartmental arthroplasty: a tenyear survival study. J Bone Joint Surg Br 80:983, 1998 6. Squire MW, Callaghan JJ, Goetz DD, et al: Unicompartmental knee replacement. A minimum 15-year followup study. Clin Orthop 367:61, 1999 7. Svard UC, Price AJ: Oxford medial unicompartmental knee arthroplasty. A survival analysis of an independent series. J Bone Joint Surg Br 83:191, 2001 8. Padgett DE, Stern SH, Insall JN: Revision total knee arthroplasty for failed unicompartmental replacement. J Bone Joint Surg Am 73:186, 1991 9. McAuley JP, Engh GA, Ammeen DJ: Revision of unicompartmental knee arthroplasty. Clin Orthop 392: 279, 2001