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Arthroscopic Anterior Cruciate Ligament Reconstruction Using a Flexible Guide Pin With a Rigid Reamer

Am J Orthop. 2015 April;44(4):167-171

References

1. Cain EL Jr, Clancy WG Jr. Anatomic endoscopic anterior cruciate ligament reconstruction with patella tendon autograft. Orthop Clin North Am. 2002;33(4):717-725.

2. Chhabra A, Starman JS, Ferretti M, Vidal AF, Zantop T, Fu FH. Anatomic, radiographic, biomechanical, and kinematic evaluation of the anterior cruciate ligament and its two functional bundles. J Bone Joint Surg Am. 2006;88(suppl 4):2-10.

3. Christel P, Sahasrabudhe A, Basdekis G. Anatomic double-bundle anterior cruciate ligament reconstruction with anatomic aimers. Arthroscopy. 2008;24(10):1146-1151.

4. Allen CR, Giffin JR, Harner CD. Revision anterior cruciate ligament reconstruction. Orthop Clin North Am. 2003;34(1):79-98.

5. Miller CD, Gerdeman AC, Hart JM, et al. A comparison of 2 drilling techniques on the femoral tunnel for anterior cruciate ligament reconstruction. Arthroscopy. 2011;27(3):372-379.

6. Seon JK, Park SJ, Lee KB, Seo HY, Kim MS, Song EK. In vivo stability and clinical comparison of anterior cruciate ligament reconstruction using low or high femoral tunnel positions. Am J Sports Med. 2011;39(1):127-133.

7. Steiner ME, Battaglia TC, Heming JF, Rand JD, Festa A, Baria M. Independent drilling outperforms conventional transtibial drilling in anterior cruciate ligament reconstruction. Am J Sports Med. 2009;37(10):1912-1919.

8. Kopf S, Forsythe B, Wong AK, et al. Nonanatomic tunnel position in traditional transtibial single-bundle anterior cruciate ligament reconstruction evaluated by three-dimensional computed tomography. J Bone Joint Surg Am. 2010;92(6):1427-1431.

9. Tompkins M, Milewski MD, Brockmeier SF, Gaskin CM, Hart JM, Miller MD. Anatomic femoral tunnel drilling in anterior cruciate ligament reconstruction: use of an accessory medial portal versus traditional transtibial drilling. Am J Sports Med. 2012;40(6):1313-1321.

10. Heming JF, Rand J, Steiner ME. Anatomical limitations of transtibial drilling in anterior cruciate ligament reconstruction. Am J Sports Med. 2007;35(10):1708-1715.

11. Harner CD, Honkamp NJ, Ranawat AS. Anteromedial portal technique for creating the anterior cruciate ligament femoral tunnel. Arthroscopy. 2008;24(1):113-115.

12. Lubowitz JH. Anteromedial portal technique for the anterior cruciate ligament femoral socket: pitfalls and solutions. Arthroscopy. 2009;25(1):95-101.

13. Basdekis G, Abisafi C, Christel P. Influence of knee flexion angle on femoral tunnel characteristics when drilled through the anteromedial portal during anterior cruciate ligament reconstruction. Arthroscopy. 2008;24(4):459-464.

14. Zantop T, Haase AK, Fu FH, Petersen W. Potential risk of cartilage damage in double bundle ACL reconstruction: impact of knee flexion angle and portal location on the femoral PL bundle tunnel. Arch Orthop Trauma Surg. 2008;128(5):509-513.

15. Farrow LD, Parker RD. The relationship of lateral anatomic structures to exiting guide pins during femoral tunnel preparation utilizing an accessory medial portal. Knee Surg Sports Traumatol Arthrosc. 2010;18(6):747-753.

16. Nakamura M, Deie M, Shibuya H, et al. Potential risks of femoral tunnel drilling through the far anteromedial portal: a cadaveric study. Arthroscopy. 2009;25(5):481-487.

17. Silver AG, Kaar SG, Grisell MK, Reagan JM, Farrow LD. Comparison between rigid and flexible systems for drilling the femoral tunnel through an anteromedial portal in anterior cruciate ligament reconstruction. Arthroscopy. 2010;26(6):790-795.

18. Steiner ME, Smart LR. Flexible instruments outperform rigid instruments to place anatomic anterior cruciate ligament femoral tunnels without hyperflexion. Arthroscopy. 2012;28(6):835-843.

Discussion

Successful ACL reconstruction depends heavily on anatomical tunnel positioning. Failure to place the femoral tunnel in the anatomical footprint of the native ACL results in incomplete restoration of knee kinematics, rotational instability, and graft failure.^1-7 Two common techniques for creating this tunnel, transtibial and anteromedial drilling, can reliably place it in an anatomical position. Each technique, however, has limitations. Transtibial drilling can place the tunnel too vertical and high in the notch, or produce a short tibial tunnel close to the joint line.^8-10 Anteromedial drilling requires knee hyperflexion, risks damaging the articular cartilage and nearby neurovascular structures, and makes visualization difficult.^13-16

One option for addressing some of the difficulties and limitations with anteromedial drilling is to use flexible guide pins and reamers, as first introduced by Cain and Clancy.¹ In a cadaveric study, Silver and colleagues¹⁷ demonstrated that interosseous tunnels drilled with flexible guide pins were on average more than 6 mm longer than those drilled with rigid pins and consistently were 40 mm or longer. In addition, all tunnels drilled with flexible guide pins were on average 42.3 mm away from the peroneal nerve and 26.1 mm away from the femoral origin of the lateral collateral ligament—safe distances.

Steiner and Smart¹⁸ compared flexible and rigid instruments used to drill transtibial and anteromedial (without hyperflexion) anatomical femoral tunnels in ACL reconstruction in cadaveric knees. Although transtibial drilling with flexible pins produced anatomical tunnels, the tunnels were shorter, and the pins exited more posterior in comparison with anteromedial drilling with flexible pins. Transtibial tunnels drilled with rigid pins were nonanatomical and exited more superior and anterior on the femur, resulting in longer tunnels. Anteromedial tunnels drilled with rigid and flexible pins were placed anatomically, but flexible pins produced longer tunnels, did not require hyperflexion (120°), could easily be placed with the knee in 90° of flexion, and did not violate the posterior femoral cortex.

Five times in our early experience with flexible guide pins and reamers, the reamer broke when LFC reaming was initiated. In each case, the broken reamer was retrieved. However, these complications resulted in increased surgical time and cost. In addition, an unretrievable reamer could have caused further injury and suboptimal outcomes. We subsequently developed an anteromedial technique that uses a flexible guide pin with a rigid reamer to place the femoral tunnel in an anatomical position (Figure 9). The flexible pin provides consistent placement of anatomical tunnels averaging 35 to 40 mm in length. Use of the flexible pin does not require constant hyperflexion of the knee, and it allows for better visualization of the posterior wall of the LFC, ensures anatomical graft placement, and decreases the risk of damaging articular cartilage and causing neurovascular injury. Use of the rigid reamer negates the risks and additional costs associated with reamer breakage. It is unclear why 5 flexible reamers broke during our early use of flexible guide pins and reamers, but it is possible that, because of the patients’ anatomy, placement of the pin in the correct anatomical position in the ACL footprint put a significant amount of abnormal stress on the reamer during tunnel reaming, leading to breakage and failure.

A short femoral tunnel is a common complication of using an anteromedial portal for tunnel drilling.^13-16 With the technique we have been using, tunnel lengths average 35 to 40 mm. To address the occasional shorter tunnel, we use Endobutton Direct (Smith & Nephew), which allows for direct fixation of the graft on the button, maximizing the amount of graft in the femoral tunnel and minimizing graft–tunnel length mismatch. In the event there is a lateral wall breach during overdrilling with the reamer, the femoral graft may be secured with screw and post, with interference screw, or with the larger Xtendobuton (Smith & Nephew).

We have successfully used this technique with bone–patellar tendon–bone (BPTB) and hamstring autografts, as well as allografts. Complications, such as graft–tunnel length mismatch, have been uncommon, but, when using BPTB grafts, passing the bone block into the femoral tunnel can be difficult because of the sharp turn required.

Conclusion

Successful ACL reconstruction depends heavily on placement of the graft within the anatomical insertion of the native ACL. With the development of techniques that use flexible guide pins and reamers, it has become possible to place longer anatomical femoral tunnels without the need for hyperflexion. Use of a flexible guide pin with a rigid reamer allows placement of longer anatomical tunnels through an anteromedial portal, reduces time spent with the knee in hyperflexion, provides better viewing, poses less risk of damage to the articular cartilage and neurovascular structures, and at a lower cost with less risk of reamer breakage. In addition, this technique can be used with a variety of graft options, including BPTB grafts, hamstring autografts, and allografts.