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Endopearl augmentation of bioabsorbable interference screw fixation of a soft tissue tendon graft in a tibial tunnel
Technical Note
EndoPearl Augmentation of Bioabsorbable Interference Screw Fixation of a Soft Tissue Tendon Graft in a Tibial Tunnel Yavuz Kocabey, M.D., Akbar Nawab, M.D., David N. M. Caborn, M.D., and John Nyland, Ed.D.
Abstract: In this technical note, we introduce a new technique for tibial side soft tissue graft fixation using a bioabsorbable interference screw augmented with an EndoPearl (Linvatec, Largo, FL) for ACL reconstruction. This technique will enable the knee surgeon to use shorter grafts while minimizing slippage without reducing fixation strength. Key Words: Arthroscopy—ACL reconstruction—Interference screw—Knee joint.
T
o overcome the unfavorable side effects of bone– patellar tendon– bone (BPTB) graft use for anterior cruciate ligament (ACL) reconstruction, soft tissue tendon autografts have gained popularity. The most commonly used soft tissue grafts are hamstring tendon autografts consisting of tripled or quadrupled semitendinosus and gracilis tendon bundles.1,2 However, hamstring grafts may contribute to excessive postoperative knee laxity3,4 and may deprive the knee joint of 2 muscles that assist with dynamic knee and hip joint stability.5,6 Because of shortcomings associated with soft tissue autografts, an increasing interest in soft tissue tendon allografts has developed. Caborn and Selby7 suggested that double-bundle anterior tibialis allografts may be more effective in restoring the functionality of the native ACL. Many consider tibial side fixation to be the weak link during ACL reconstruction when soft tissue grafts are fixed with an interference screw. The
From the Division of Sports Medicine, Department of Orthopaedic Surgery, University of Louisville, Louisville, Kentucky, U.S.A. Address correspondence and reprint requests to John Nyland, Ed.D., Division of Sports Medicine, Department of Orthopaedic Surgery, University of Louisville, 210 East Gray Street, Suite 1003, Louisville, KY 40202, U.S.A. E-mail: [email protected] © 2004 by the Arthroscopy Association of North America 0749-8063/04/2006-3722$30.00/0 doi:10.1016/j.arthro.2004.04.066
658
initial strength of soft tissue allograft interference fit fixation might not allow for early and intensive rehabilitation.8 Soft tissue allografts have superior tissue strength characteristics to BPTB grafts when used in either double-, triple-, or quadruple-bundle configurations.1,2 Soft tissue allografts enable ACL reconstruction among nontraditional younger and older patients because concerns over associated tissue morbidity secondary to graft harvest and residual functional impairments are eliminated. Increasing evidence supports soft tissue tendon allograft use, especially if revision is necessary. Whether autogenous or allogeneic soft tissue is used, occasionally the graft is shorter than desired. Reasons for this may include use of only one hamstring tendon, incomplete autograft harvest, inadequate allograft length, or increased tibial tunnel length. When the surgeon is confronted with this situation, the internal interlocking provided by the combined use of a bioabsorbable interference screw and an EndoPearl (Linvatec, Largo, FL) may provide an effective tibial side fixation option. ALLOGRAFT PREPARATION The allograft is prepared on a back table. The graft is prepared after proper thawing, which is very impor-
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 20, No 6 (July-August), 2004: pp 658-661
ENDOPEARL AUGMENTATION
659
tant to maintain collagen fiber structural integrity.9 The graft is inspected for any gross defects. The tendon is measured and then doubled on itself. The free end is the femoral side of the graft, and the folded end is the tibial side. The ends of tendon are “whip stitched” 30 to 35 mm with No. 0 Fiberwire suture (Arthrex, Naples, FL). Suture passes interdigitate and encompass at least half the tendon width. Sutures are pulled tightly to help tubularize the flat end of the tendon, and both ends are compressed so the tendon is of uniform diameter after preparation.10 Frayed ends are excised to allow easy graft passage. The graft is sized through the entire length. An EndoPearl approximately 1 mm smaller than the tunnel diameter is sutured tightly to the femoral end of the graft. The EndoPearl must be securely affixed to the graft ends to function as an effective antislippage device. After EndoPearl attachment, the graft is tensioned to 10 lb/in for 15 to 20 minutes to reduce the amount of creep and allow for any viscoelastic microelongation. The graft is kept moist with sterile salinesoaked gauze until implantation. SURGICAL TECHNIQUE Anesthesia consists of regional block and laryngeal mask. The patient is supine with the treated extremity in an arthroscopic leg holder. A well-padded tourniquet is placed on the proximal thigh. Standard anteromedial and anterolateral portals are sharply established. Diagnostic arthroscopy is performed, including the suprapatellar pouch, patella, trochlea, medial and lateral gutters, medial and lateral compartments, and the notch. The ACL stump is lightly debrided, preserving the tibial footprint. Notchplasty is performed to the posterior horn of the lateral meniscus, ensuring adequate visualization. Care is taken not to lateralize the femoral tunnel. Roofplasty is performed to the level of the insertion of the posterior cruciate ligament (PCL). Using a tibial ACL guide set at 50°, the guide pin is drilled into the posterior aspect of the tibial footprint. The arm of the drill guide is kept parallel to the floor. The reamer corresponding to the graft size is passed over the guide pin. The femoral guide pin is placed so that, after femoral tunnel reaming, the tunnel is within 1 to 2 mm of the back wall of the notch at the 2:00 (left) or 10:00 (right) o’clock position. The guide pin is passed out the anterolateral femur and clamped to prevent inadvertent removal. An acorn reamer is passed over the guide pin to a depth of 40 to 45 mm, without breaching the lateral cortex of the femur. The
FIGURE 1.
EndoPearl use at tibial and femoral graft ends.
sutures of the graft with the EndoPearl is threaded through the pin eyelet and pulled out the anterolateral femur. Keeping tension on the tibial graft sutures, the surgeon pulls the graft into position. The guide pin for the bioabsorbable interference screw is placed along the anterior aspect of the femoral tunnel. After the first few threads of the screw are engaged, the guidewire is removed to prevent incarceration. The screw is sized 1 mm smaller than the femoral tunnel diameter, with the length so that the end of the screw abuts the EndoPearl while providing aperture fixation. The knee is cycled 20 times while tension is held on the tibial graft sutures. With the knee in full extension, a 35-mm bioabsorbable interference screw with a diameter 1 mm larger than the tibial tunnel is placed posterior to the graft (Fig 1). The guidewire is removed after the screw has achieved purchase in the tunnel to prevent wire incarceration. Screw placement is visualized with the arthroscope positioned adjacent to the graft in the tibial tunnel (Fig 2). A second sliding suture is passed through the tibial end of the graft before passage. After the end of the graft is fixed in the tunnel, the
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sliding suture is threaded through the eye of the EndoPearl. Using an arthroscopic knot pusher, the surgeon ties the EndoPearl to the end of the screw and graft. It is important to obtain a tactile feel for EndoPearl abutment against the screw. The arthroscope is placed into the tibial tunnel to confirm adequate abutment of the EndoPearl to the screw (Fig 3). The arthroscope is replaced, and the graft tension and placement is inspected one final time before closure. DISCUSSION The success of ACL surgery relies on patient selection, graft selection, fixation method, surgical technique (isometricity, tensioning, and surgical approach), and the postoperative rehabilitation program.11 Combined or “hybrid” tibial fixation may be particularly advantageous when soft tissue tendon grafts are used. Concern over tibial side fixation during ACL reconstruction among patients with low bone mineral densities has led to the development of a myriad of surgical alternatives. Both intra-articular methods using either metal or bioabsorbable interference screws, and supplemental extra-articular approaches using screws, staples, buttons, screw-washer or bioabsorbable tenodesis screw combinations have been developed. The structural properties of stiffness, slippage, and load to failure may affect the ability of a ligament replacement to restore and maintain the stability of the reconstructed knee, especially during the initial 8 to 12 weeks after surgery.12 Nagarkatti et al.13 reported
FIGURE 3.
EndoPearl-screw abutment.
using a bone disk or poly L-lactide ball with a biointerference screw to increase fixation strength and reduce soft tissue graft slippage. In a biomechanical study, Weiler et al.14 reported that soft tissue grafttunnel fixation using the EndoPearl device at the femoral side produced maximum load to failure values that were comparable to those obtained with conventional BPTB graft fixation. Researchers have also suggested that EndoPearl device use in the femoral tunnel may lead to increased load to failure and stiffness fixation, which prevents the bungee effect (Caborn DNM, unpublished data, 2001). Combining EndoPearl and bioabsorbable interference screw use in the tibial tunnel provides the knee surgeon with an all-inside hybrid fixation option that may be particularly useful when a graft of less than optimal length is used. We propose that this technique helps prevent tibial-side soft tissue tendon graft slippage by creating an interlocking between the top of the screw and the EndoPearl device. In contrast to washer, staples, or other extra-articular fixation supplementation methods, EndoPearl use does not contribute to palpable skin irritation and adjacent tissue morbidity that may require a second operation for removal. REFERENCES
FIGURE 2.
Adjacent graft-screw placement in tibial tunnel.
1. Caborn DN, Coen M, Neef R, et al. Quadrupled semitendinosus-gracilis autograft fixation in the femoral tunnel: A comparison between a metal and a bioabsorbable interference screw. Arthroscopy 1998;14:241-245.
ENDOPEARL AUGMENTATION 2. Haut Donahue TL, Howell SM, Hull ML, Gregersen C. A biomechanical evaluation of anterior and posterior tibialis tendons as suitable single-loop anterior cruciate ligament grafts. Arthroscopy 2002;18:589-597. 3. Barrett GR, Noojin FK, Hartzog CW, Nash CR. Reconstruction of the anterior cruciate ligament in females: A comparison of hamstring versus patellar tendon autograft. Arthroscopy 2002;18:46-54. 4. Corry IS, Webb JM, Clingeleffer AJ, Pinczewski LA. Arthroscopic reconstruction of the anterior cruciate ligament: A comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444-454. 5. Aune AK, Holm I, Risberg MA, et al. Four-strand hamstring tendon autograft compared with patellar tendon-bone autograft for anterior cruciate ligament reconstruction. A randomized study with two-year follow-up. Am J Sports Med 2001;29:722-728. 6. Nakamura N, Horibe S, Sasaki S, et al. Evaluation of active knee flexion and hamstring strength after anterior cruciate ligament reconstruction using hamstring tendons. Arthroscopy 2002;18:598-602. 7. Caborn DN, Selby JB. Allograft anterior tibialis tendon with bioabsorbable interference screw fixation in anterior cruciate ligament reconstruction. Arthroscopy 2002;18:102-105.
661
8. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel: A biomechanical and histological study in the dog. J Bone Joint Surg Am 1993;75:1795-1803. 9. Olson EJ, Harner CD, Fu FH, Silbey MB. Clinical use of fresh, frozen soft tissue allografts. Orthop 1992;15:1225-1232. 10. Charlick DA, Caborn DN. Technical note: Alternative softtissue graft preparation technique for cruciate ligament reconstruction. Arthroscopy 2000;16:E2010. 11. Rowden NJ, Sher D, Rogers GJ, Schindhelm K. Anterior cruciate ligament graft fixation: Initial comparison of patellar tendon and semitendinosus autograft in young fresh cadavers. Am J Sports Med 1997;25:472-478. 12. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35-43. 13. Nagarkatti DG, Mckeon BP, Donahue BS, Fulkerson JP. Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation. Am J Sports Med 2001;29:67-71. 14. Weiler A, Richter M, Schmidmair G, et al. The EndoPearl device increases fixation strength and eliminates construct slippage of hamstring tendon grafts with interference screw fixation. Arthroscopy 2001;17:353-359.
EndoPearl Augmentation of Bioabsorbable Interference Screw Fixation of a Soft Tissue Tendon Graft in a Tibial Tunnel Yavuz Kocabey, M.D., Akbar Nawab, M.D., David N. M. Caborn, M.D., and John Nyland, Ed.D.
Abstract: In this technical note, we introduce a new technique for tibial side soft tissue graft fixation using a bioabsorbable interference screw augmented with an EndoPearl (Linvatec, Largo, FL) for ACL reconstruction. This technique will enable the knee surgeon to use shorter grafts while minimizing slippage without reducing fixation strength. Key Words: Arthroscopy—ACL reconstruction—Interference screw—Knee joint.
T
o overcome the unfavorable side effects of bone– patellar tendon– bone (BPTB) graft use for anterior cruciate ligament (ACL) reconstruction, soft tissue tendon autografts have gained popularity. The most commonly used soft tissue grafts are hamstring tendon autografts consisting of tripled or quadrupled semitendinosus and gracilis tendon bundles.1,2 However, hamstring grafts may contribute to excessive postoperative knee laxity3,4 and may deprive the knee joint of 2 muscles that assist with dynamic knee and hip joint stability.5,6 Because of shortcomings associated with soft tissue autografts, an increasing interest in soft tissue tendon allografts has developed. Caborn and Selby7 suggested that double-bundle anterior tibialis allografts may be more effective in restoring the functionality of the native ACL. Many consider tibial side fixation to be the weak link during ACL reconstruction when soft tissue grafts are fixed with an interference screw. The
From the Division of Sports Medicine, Department of Orthopaedic Surgery, University of Louisville, Louisville, Kentucky, U.S.A. Address correspondence and reprint requests to John Nyland, Ed.D., Division of Sports Medicine, Department of Orthopaedic Surgery, University of Louisville, 210 East Gray Street, Suite 1003, Louisville, KY 40202, U.S.A. E-mail: [email protected] © 2004 by the Arthroscopy Association of North America 0749-8063/04/2006-3722$30.00/0 doi:10.1016/j.arthro.2004.04.066
658
initial strength of soft tissue allograft interference fit fixation might not allow for early and intensive rehabilitation.8 Soft tissue allografts have superior tissue strength characteristics to BPTB grafts when used in either double-, triple-, or quadruple-bundle configurations.1,2 Soft tissue allografts enable ACL reconstruction among nontraditional younger and older patients because concerns over associated tissue morbidity secondary to graft harvest and residual functional impairments are eliminated. Increasing evidence supports soft tissue tendon allograft use, especially if revision is necessary. Whether autogenous or allogeneic soft tissue is used, occasionally the graft is shorter than desired. Reasons for this may include use of only one hamstring tendon, incomplete autograft harvest, inadequate allograft length, or increased tibial tunnel length. When the surgeon is confronted with this situation, the internal interlocking provided by the combined use of a bioabsorbable interference screw and an EndoPearl (Linvatec, Largo, FL) may provide an effective tibial side fixation option. ALLOGRAFT PREPARATION The allograft is prepared on a back table. The graft is prepared after proper thawing, which is very impor-
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 20, No 6 (July-August), 2004: pp 658-661
ENDOPEARL AUGMENTATION
659
tant to maintain collagen fiber structural integrity.9 The graft is inspected for any gross defects. The tendon is measured and then doubled on itself. The free end is the femoral side of the graft, and the folded end is the tibial side. The ends of tendon are “whip stitched” 30 to 35 mm with No. 0 Fiberwire suture (Arthrex, Naples, FL). Suture passes interdigitate and encompass at least half the tendon width. Sutures are pulled tightly to help tubularize the flat end of the tendon, and both ends are compressed so the tendon is of uniform diameter after preparation.10 Frayed ends are excised to allow easy graft passage. The graft is sized through the entire length. An EndoPearl approximately 1 mm smaller than the tunnel diameter is sutured tightly to the femoral end of the graft. The EndoPearl must be securely affixed to the graft ends to function as an effective antislippage device. After EndoPearl attachment, the graft is tensioned to 10 lb/in for 15 to 20 minutes to reduce the amount of creep and allow for any viscoelastic microelongation. The graft is kept moist with sterile salinesoaked gauze until implantation. SURGICAL TECHNIQUE Anesthesia consists of regional block and laryngeal mask. The patient is supine with the treated extremity in an arthroscopic leg holder. A well-padded tourniquet is placed on the proximal thigh. Standard anteromedial and anterolateral portals are sharply established. Diagnostic arthroscopy is performed, including the suprapatellar pouch, patella, trochlea, medial and lateral gutters, medial and lateral compartments, and the notch. The ACL stump is lightly debrided, preserving the tibial footprint. Notchplasty is performed to the posterior horn of the lateral meniscus, ensuring adequate visualization. Care is taken not to lateralize the femoral tunnel. Roofplasty is performed to the level of the insertion of the posterior cruciate ligament (PCL). Using a tibial ACL guide set at 50°, the guide pin is drilled into the posterior aspect of the tibial footprint. The arm of the drill guide is kept parallel to the floor. The reamer corresponding to the graft size is passed over the guide pin. The femoral guide pin is placed so that, after femoral tunnel reaming, the tunnel is within 1 to 2 mm of the back wall of the notch at the 2:00 (left) or 10:00 (right) o’clock position. The guide pin is passed out the anterolateral femur and clamped to prevent inadvertent removal. An acorn reamer is passed over the guide pin to a depth of 40 to 45 mm, without breaching the lateral cortex of the femur. The
FIGURE 1.
EndoPearl use at tibial and femoral graft ends.
sutures of the graft with the EndoPearl is threaded through the pin eyelet and pulled out the anterolateral femur. Keeping tension on the tibial graft sutures, the surgeon pulls the graft into position. The guide pin for the bioabsorbable interference screw is placed along the anterior aspect of the femoral tunnel. After the first few threads of the screw are engaged, the guidewire is removed to prevent incarceration. The screw is sized 1 mm smaller than the femoral tunnel diameter, with the length so that the end of the screw abuts the EndoPearl while providing aperture fixation. The knee is cycled 20 times while tension is held on the tibial graft sutures. With the knee in full extension, a 35-mm bioabsorbable interference screw with a diameter 1 mm larger than the tibial tunnel is placed posterior to the graft (Fig 1). The guidewire is removed after the screw has achieved purchase in the tunnel to prevent wire incarceration. Screw placement is visualized with the arthroscope positioned adjacent to the graft in the tibial tunnel (Fig 2). A second sliding suture is passed through the tibial end of the graft before passage. After the end of the graft is fixed in the tunnel, the
660
Y. KOCABEY ET AL.
sliding suture is threaded through the eye of the EndoPearl. Using an arthroscopic knot pusher, the surgeon ties the EndoPearl to the end of the screw and graft. It is important to obtain a tactile feel for EndoPearl abutment against the screw. The arthroscope is placed into the tibial tunnel to confirm adequate abutment of the EndoPearl to the screw (Fig 3). The arthroscope is replaced, and the graft tension and placement is inspected one final time before closure. DISCUSSION The success of ACL surgery relies on patient selection, graft selection, fixation method, surgical technique (isometricity, tensioning, and surgical approach), and the postoperative rehabilitation program.11 Combined or “hybrid” tibial fixation may be particularly advantageous when soft tissue tendon grafts are used. Concern over tibial side fixation during ACL reconstruction among patients with low bone mineral densities has led to the development of a myriad of surgical alternatives. Both intra-articular methods using either metal or bioabsorbable interference screws, and supplemental extra-articular approaches using screws, staples, buttons, screw-washer or bioabsorbable tenodesis screw combinations have been developed. The structural properties of stiffness, slippage, and load to failure may affect the ability of a ligament replacement to restore and maintain the stability of the reconstructed knee, especially during the initial 8 to 12 weeks after surgery.12 Nagarkatti et al.13 reported
FIGURE 3.
EndoPearl-screw abutment.
using a bone disk or poly L-lactide ball with a biointerference screw to increase fixation strength and reduce soft tissue graft slippage. In a biomechanical study, Weiler et al.14 reported that soft tissue grafttunnel fixation using the EndoPearl device at the femoral side produced maximum load to failure values that were comparable to those obtained with conventional BPTB graft fixation. Researchers have also suggested that EndoPearl device use in the femoral tunnel may lead to increased load to failure and stiffness fixation, which prevents the bungee effect (Caborn DNM, unpublished data, 2001). Combining EndoPearl and bioabsorbable interference screw use in the tibial tunnel provides the knee surgeon with an all-inside hybrid fixation option that may be particularly useful when a graft of less than optimal length is used. We propose that this technique helps prevent tibial-side soft tissue tendon graft slippage by creating an interlocking between the top of the screw and the EndoPearl device. In contrast to washer, staples, or other extra-articular fixation supplementation methods, EndoPearl use does not contribute to palpable skin irritation and adjacent tissue morbidity that may require a second operation for removal. REFERENCES
FIGURE 2.
Adjacent graft-screw placement in tibial tunnel.
1. Caborn DN, Coen M, Neef R, et al. Quadrupled semitendinosus-gracilis autograft fixation in the femoral tunnel: A comparison between a metal and a bioabsorbable interference screw. Arthroscopy 1998;14:241-245.
ENDOPEARL AUGMENTATION 2. Haut Donahue TL, Howell SM, Hull ML, Gregersen C. A biomechanical evaluation of anterior and posterior tibialis tendons as suitable single-loop anterior cruciate ligament grafts. Arthroscopy 2002;18:589-597. 3. Barrett GR, Noojin FK, Hartzog CW, Nash CR. Reconstruction of the anterior cruciate ligament in females: A comparison of hamstring versus patellar tendon autograft. Arthroscopy 2002;18:46-54. 4. Corry IS, Webb JM, Clingeleffer AJ, Pinczewski LA. Arthroscopic reconstruction of the anterior cruciate ligament: A comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444-454. 5. Aune AK, Holm I, Risberg MA, et al. Four-strand hamstring tendon autograft compared with patellar tendon-bone autograft for anterior cruciate ligament reconstruction. A randomized study with two-year follow-up. Am J Sports Med 2001;29:722-728. 6. Nakamura N, Horibe S, Sasaki S, et al. Evaluation of active knee flexion and hamstring strength after anterior cruciate ligament reconstruction using hamstring tendons. Arthroscopy 2002;18:598-602. 7. Caborn DN, Selby JB. Allograft anterior tibialis tendon with bioabsorbable interference screw fixation in anterior cruciate ligament reconstruction. Arthroscopy 2002;18:102-105.
661
8. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon-healing in a bone tunnel: A biomechanical and histological study in the dog. J Bone Joint Surg Am 1993;75:1795-1803. 9. Olson EJ, Harner CD, Fu FH, Silbey MB. Clinical use of fresh, frozen soft tissue allografts. Orthop 1992;15:1225-1232. 10. Charlick DA, Caborn DN. Technical note: Alternative softtissue graft preparation technique for cruciate ligament reconstruction. Arthroscopy 2000;16:E2010. 11. Rowden NJ, Sher D, Rogers GJ, Schindhelm K. Anterior cruciate ligament graft fixation: Initial comparison of patellar tendon and semitendinosus autograft in young fresh cadavers. Am J Sports Med 1997;25:472-478. 12. Magen HE, Howell SM, Hull ML. Structural properties of six tibial fixation methods for anterior cruciate ligament soft tissue grafts. Am J Sports Med 1999;27:35-43. 13. Nagarkatti DG, Mckeon BP, Donahue BS, Fulkerson JP. Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation. Am J Sports Med 2001;29:67-71. 14. Weiler A, Richter M, Schmidmair G, et al. The EndoPearl device increases fixation strength and eliminates construct slippage of hamstring tendon grafts with interference screw fixation. Arthroscopy 2001;17:353-359.