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© 1999 The Journal of Bone and Joint Surgery, Inc.
Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Specialized Exposure for Revision Total Knee Arthroplasty: Quadriceps Snip and Patellar Turndown*
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Adequate exposure of the knee is the first step in the successful performance of a revision total knee arthroplasty. In order to safely and expeditiously remove the implants that are in place and insert trial and actual components, flexion well beyond 90 degrees (to about 110 degrees) is needed13. In addition, it is preferable to be able to evert the patella and dislocate the tibia anteriorly. If a patient has less than 80 to 90 degrees of passive flexion under anesthesia, the standard medial parapatellar approach may not provide adequate exposure. Initially, it is useful to start the midline incision more proximally than the previous incision in order to establish normal tissue planes proximal to the extensor mechanism. It is also useful to take additional time to define the borders of the rectus femoris tendon and the vastus lateralis and medialis insertions into the patella. The medial parapatellar capsular incision begins at the proximal extent of the rectus tendon and ends distally one centimeter medial to the tibial tubercle. After a medial arthrotomy, release of any adhesions in the suprapatellar pouch and the medial and lateral gutters should be performed. Careful release or excision of scarred or contracted tissue leads to increased flexion and easier eversion of the patella and provides adequate exposure in many patients. Access to the lateral gutter is more difficult after a standard medial arthrotomy. A medial capsular release from the tibia is typically extended past the mid-coronal plane, usually to the posteromedial corner of the knee just anterior to the semimembranosus insertion. External rotation of the tibia after medial release and clearing of the gutters and the suprapatellar pouch usually increases knee flexion to some degree. The next maneuver that improves exposure is the application of traction on the patella as the knee is flexed and an attempt is made to evert the patella. This places the fibers of the patellofemoral ligament, which extends from the lateral epicondyle to the lateral border of the patella, under tension. This band of tissue has been described as a separate entity from the lateral retinaculum6. Routine release of these fibers assists in patellar eversion, allows easier lateral retraction of the patella (thus improving exposure), and often improves patellar tracking6,9. After all of these maneuvers, passive knee flexion and patellar eversion are assessed. If the knee cannot be flexed well beyond 90 degrees without excessive tension on the patellar ligament (patellar tendon) and patellar eversion is not possible, additional steps must be taken in order to accomplish these goals.
There are two basic approaches to achieving more flexion: it can be achieved proximally through the extensor mechanism or distally through the tibial tubercle. If the proximal approach is elected, the options include dividing the quadriceps tendon, the lateral retinaculum, or the vastus lateralis tendon, or some combination of the three. Isolated division of the rectus tendon to improve exposure during knee arthroplasty has been called the quadriceps snip and is attributed to Insall5. Early on, this was described as a transverse cut across the proximal portion of the rectus tendon9 (Fig. 1). Later, it was modified to be a 45-degree oblique incision extending from the lateral aspect of the quadriceps tendon proximally to the medial aspect of the quadriceps tendon distally4 (Fig. 2). This incision has a number of potential advantages in that it is directed in line with the vastus lateralis muscle and away from the lateral superior genicular artery and the vastus lateralis tendon. It also provides more leeway in closing the defect4. If adequate exposure is not obtained with the quadriceps snip, it can be combined with a lateral retinacular release placed longitudinally approximately one centimeter lateral to the lateral border of the patella9 (Fig. 3). A more recent modification of the quadriceps snip angles the lateral portion of the 45-degree oblique incision distally rather than proximally9 (Fig. 4). This has the advantage of being more extensile (versatile) because it can more easily be converted into a complete patellar turndown. The advantages of the quadriceps snip are that it is technically easy, it spares the major vascular supply to the patella (the lateral superior genicular artery), it has not been associated with postoperative complications such as extension lag, and the postoperative rehabilitation does not have to be modified.
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In one study, objective assessment consisting of isokinetic testing of patients who had had a total knee arthroplasty with a quadriceps snip revealed that the involved knee was not as strong as the normal, contra-lateral knee4. However, with the numbers available for study, the authors could detect no significant difference (although there was a trend) in terms of peak torque (p = 0.06) or work (p = 0.07) between the knees that had been treated with a total knee arthroplasty through a standard approach and those treated with a total knee arthroplasty and a quadriceps snip4. In another review, the results of thirty-one revision total knee arthroplasties performed with a quadriceps snip were found to be equivalent to those of sixty-three revision total knee arthroplasties performed with a standard medial parapatellar approach; these results were measured in terms of the clinical, functional, and total scores of the Knee Society rating system; range of motion; extension lag; patellofemoral pain; and patient satisfaction2. The quadriceps snip has been reported to be applicable to most, if not all, knees with limited motion4. Other authors have reported that this technique is effective only for knees with mild-to-moderate stiffness and that more extensive procedures are necessary for very stiff knees9,13. In this scenario, the quadriceps snip can be combined with an osteotomy of the tibial tubercle or it can be converted to a patellar turndown.
In 1983, Insall performed a modification of the approach of Coonse and Adams4. This modification, the patellar turndown, consists of a standard medial parapatellar capsular incision combined with an oblique distal cut from the proximal extent of the arthrotomy across the rectus tendon, the vastus lateralis tendon, and the lateral retinaculum (Fig. 5). It provides rapid, wide exposure of knees that have a moderate-to-severe degree of stiffness and gives easy access to the lateral gutter through the oblique arm of the incision. This allows lysis of dense adhesions and rapid mobilization of the extensor mechanism. It releases all tension on the insertion of the patellar ligament and all but eliminates the risk of avulsion of the patellar ligament. This approach also allows for easy access to the central anterior portion of the proximal part of the tibia, which is particularly helpful during trial reductions because most revision tibial components are modular and require the tibial insert to be slid in parallel to the base-plate and directly from the front. This can place very high tension on the patellar ligament in a stiff knee as retractors are levered laterally to allow placement of the insert. The patellar turndown makes this potentially dangerous portion of the procedure safe and easy.
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The site of the patellar turndown should be repaired with heavy, nonabsorbable suture. The so-called V-Y incision allows advancement of a centimeter or more, if necessary. The rectus and vastus lateralis tendons are repaired, but some or all of the lateral retinaculum is typically left open to improve flexion and patellar tracking. It is prudent to use three or four sutures and to test the tension of the repair during flexion. Releasing the tourniquet before testing the repair probably gives a more accurate estimate of the excursion of the extensor mechanism. Reattachment at the appropriate level of tension can be difficult. If the knee easily flexes beyond 90 degrees, the repair should be redone with less advancement. If the quadriceps is lengthened too much, an extension lag can result and may impair function. An extension lag of 10 degrees or more was reported in three of fourteen cases in one series2 and in two of sixteen cases in another12. Trousdale et al. reported severe weakness of knee extension after a V-Y quadricepsplasty compared with extension of the normal, contralateral knee (p < 0.05) but not compared with extension of a knee after a total knee arthroplasty12. Garvin et al. reported similar findings with the quadriceps snip4,12.
The patellar turndown approach necessitates a modification of the postoperative rehabilitation to protect the repair. Originally, two weeks of immobilization was recommended after a patellar turndown1,5. More recently, immediate continuous passive motion starting at 0 to 30 degrees has been recommended12. The point at which the original repair comes under tension should be noted, and passive motion with the continuous-passive motion machine can be increased 10 degrees per day until that degree of flexion is obtained2. Active flexion and passive extension can be started immediately, but it is probably prudent to delay straight-leg raising and other active extension exercises until there has been adequate time for early healing of the tendon (normally within four to six weeks).
There are other potential difficulties with the patellar turndown, including difficulty in using it more than once11. If a knee is infected and repeated operative exposures are needed, performing and repairing a patellar turndown several times may be difficult. Another potential problem that has been noted is devascularization of the patella and the extensor mechanism by extending an oblique incision through the lateral retinaculum10. This invariably transects the lateral superior genicular artery. The patellar turndown approach is thought by some to spare the lateral inferior genicular blood supply to the extensor mechanism7. Other authors, however, have noted that this vessel is normally cut during a lateral meniscectomy13. Scott and Siliski modified the patellar turndown to avoid interruption of the vascular supply to the patella10. The distal extent of the incision that they described carried the apex distally for three centimeters along the insertion of the vastus lateralis muscle (Fig. 6). It therefore stops proximal to the lateral superior genicular artery and does not include a lateral retinacular release. Many patients with stiff knees have lateral retinacular tightness and associated maltracking of the patella that necessitate extensive lateral release. This approach was termed the modified V-Y quadricepsplasty10. Although it preserves the blood supply to the patella by sparing the lateral superior genicular artery, it does not provide as extensive an exposure and it does not relieve tension on the patellar ligament. Maintenance of the blood supply may be more of a theoretical advantage, as Ritter et al. found no difference in the rate of patellar complications, including radiolucency, loosening, and fracture, with preservation of the lateral superior genicular artery8. They concluded that preserving the lateral superior genicular artery was not necessary.
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The combination of a quadriceps snip and a lateral retinacular release provides adequate exposure for most revision total knee arthroplasties2. Conversion to a patellar turndown may be necessary for knees with moderate or severe stiffness. This approach greatly expedites the performance of a revision knee replacement in an ankylosed joint and minimizes the risk of avulsion of the patellar ligament, which is among the most devastating complications of knee arthroplasty. The reconstruction is performed proximally in the thigh, where the vasculature and soft-tissue coverage are excellent, so that problems related to wound-healing do not occur. The only important complications are weakness of extension and extension lag, which are transient most of the time and are rarely functionally debilitating in the few patients in whom they persist2,12.
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Footnotes |
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*Printed with permission of the American Academy of Orthopaedic Surgeons. This article will appear in Instructional Course Lectures, Volume 48, American Academy of Orthopaedic Surgeons, Rosemont, Illinois, March 1999.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
Department of Orthopaedic Surgery, Tulane University School of Medicine, 1430 Tulane Avenue, SL32, New Orleans, Louisiana 70112.
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References |
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TopIntroductionReferences |
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Aglietti, P.; Windsor, R. E.; Buzzi, R.; and and Insall, J. N.: Arthroplasty for the stiff or ankylosed knee. J. Arthroplasty, 4: 1-5, 1989.[Medline]
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Barrack, R. L.; Smith, P.; Munn, B.; Engh, G. A.; and Rorabeck, C.: Comparison for surgical approaches in TKA. Unpublished data.
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Coonse, K., and and Adams, J. D.: A new operative approach to the knee joint. Surg., Gynec. and Obstet., 77: 344-347, 1943.
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Garvin, K. L.; Scuderi, G.; and and Insall, J. N.: Evolution of the quadriceps snip. Clin. Orthop., 321: 131-137, 1945.
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Insall, J. N.: Surgical approaches to the knee. In Surgery of the Knee, edited by J. N. Insall, R. E. Windsor, W. N. Scott, M. A. Kelly, and P. Aglietti, Ed. 2, vol. 1, pp. 135-148. New York, Churchill Livingstone, 1993.
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Krackow, K. A.: Surgical procedure. In the Technique of Total Knee Arthroplasty, pp. 168-237. Edited by E. A. Klein. St. Louis, C. V. Mosby, 1990.
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Peters, P. C., Jr.: Surgical exposure for revision total knee arthroplasty. In Revision Total Knee Arthroplasty, pp. 195-204. Edited by G. A. Engh and C. H. Rorabeck. Baltimore, Williams and Wilkins, 1997.
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Ritter, M. A.; Herbst, S. A.; Keating, E. M.; Faris, P. M.; and and Meding, J. B.: Patellofemoral complications following total knee arthroplasty. Effect of a lateral release and sacrifice of the superior lateral geniculate artery. J. Arthroplasty, 11: 368-372, 1996.[Medline]
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Rosenberg, A. G.: Surgical technique of posterior cruciate sacrificing, and preserving total knee arthroplasty. In Total Knee Arthroplasty pp. 115-153. Edited by J. A. Rand. New York, Raven Press, 1993.
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Scott, R. D., and and Siliski, J. M.: the use of a modified V-Y quadricepsplasty during total knee replacement to gain exposure and improve flexion in the ankylosed knee. Orthopedics, 8: 45-48, 1985.[Medline]
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Stiehl, J. B.; Anouchi, Y.; Dennis, D. A.; Greenwald, A. S.; Krackow, K. A.; Rosenberg, A. G.; Stulberg, S. D.; and and Whiteside, L. A.: Symposium: revision total knee replacement. Contemp. Orthop., 30: 249-276, 1995.[Medline]
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Trousdale, R. T.; Hanssen, A. D.; Rand, J. A.; and and Cahalan, T. D.: V-Y quadricepsplasty in total knee arthroplasty. Clin. Orthop., 286: 48-55, 1993.
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Younger, A. S. E.; Duncan, C. P.; and and Masri, B. A.: Surgical exposures in revision total knee arthroplasty. J. Am. Acad. Orthop. Surgeons, 6: 55-64, 1998.[Abstract]
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