How Would You Manage the Situation of Graft Amputation During Interference Screw Placement With a Patellar Tendon Graft?

Eric C. McCarty, MD

Brian Kerr, MD

Careful attention to detail when placing interference screws helps to avoid potential complications, specifically graft amputation. During femoral interference screw placement, we carefully observe the tendinous portion of the graft just inferior to the bone plug. If this area begins to rotate, we are in danger of lacerating the graft and make adjustments accordingly.1

If graft laceration does occur, whether through bone, at the tendon-bone junction, or through soft-tissue planes, one’s options are limited. The amount of remaining graft must be carefully examined to determine whether the graft itself is salvageable. If not, the operative plan can shift to an alternate graft source, with allograft replacement the most obvious and least invasive option—albeit expensive. Consideration can be given to using the contralateral graft choice, either patellar tendon or hamstring from the opposite knee. If a second graft is utilized, we recommend temporarily scrubbing out of surgery to disclose the complication and discuss this new plan with the patient’s family members. This is especially recommended if the decision is made to switch to an allograft source.

A thorough evaluation of the amputated segment can guide decision making if the graft is still viable. This should note how the bone plug is damaged or whether the graft is amputated at the tendon-bone interface. A plug broken in the longitudinal plane—rendering its diameter too small for adequate interference screw fixation—can be “piggy-backed” to an additional bone plug.2 This is accomplished by attaching the additional bone plug with suture through drill holes and allows for restoration of an adequately sized bone plug to be used with an interference screw (Figure 16-1). Alternatively, a whipstitch-type securing suture (Krackow, etc) can be placed through the soft tissue and bony parts of the graft. This can be secured via suspension-type fixation, such as with an EndoButton (Smith & Nephew, Andover, MA). A bone-plug fractured transversely, that is, shortening of the bone plug, may not allow enough bone-screw contact length for adequate interference fixation, particularly if the remaining bone is shorter than 15 mm.3 If this occurs, a Krackow stitch through tendon and bone with EndoButton fixation is our recommendation (Figure 16-2). For those surgeons familiar with 2-incision techniques and open lateral distal femoral fixation, these sutures can also be tied over a screw-and-washer post.4

Attachment of additional bone to fractured bone plug for additional bone interference fixation

Figure 16-1. Attachment of additional bone to fractured bone plug for additional bone interference fixation.

Short bone plug with Krackow stitches through tendon and bone plug

Figure 16-2. Short bone plug with Krackow stitches through tendon and bone plug.

If the amputation occurred at either the tendon-bone junction or in the tendon, we recommend removing the graft from the knee for thorough evaluation and removal of the amputated bone plug from the femoral tunnel. If adequate length remains, the graft may still be salvageable. If not, consideration again needs to be given to alternative graft choices. For grafts with adequate remaining length, a whipstitch-type suture should be used to secure the soft-tissue end. The graft should then be flipped, and the end with the remaining bone plug is placed into the femoral tunnel. The sutured end of the graft can then be secured to the tibia using preferred soft-tissue fixation, such as posts or screw and spiked washers.2 With this method, the amputated bone plug can then be placed into the tibial tunnel over the secured graft, acting as bone graft for additional fixation. Alternatively, secondary fixation with a bioabsorbable screw in the tibial tunnel can be used.

We have found that certain techniques help us to prevent this very serious problem from occurring. Prior to passing the graft, we prefer to place a notch in the anterior portion of the femoral tunnel where we expect to place the interference screw. This can be done with commercially available notching instruments, but we use the interference screwdriver for this purpose, usually to a depth of 10 mm. By doing this, we facilitate guide wire and screw placement. Prior to screw placement, we place the knee in maximum flexion to minimize the chance for screw divergence. During placement of the screw, we pull continuous tension on the tibial-side graft sutures to prevent femoral plug advancement and rotation. If undue resistance to screw advancement is noted, we stop to reevaluate our technique and the direction of the screw relative to the bone block and femoral tunnel. Commercially available graft protectors may also be utilized to decrease the chance for injury.

References

1.  D’Amato MJ, Bach BR. Anterior cruciate ligament injuries in the adult. In: DeLee JC, Drez D, Miller MD, eds. Orthopaedic Sports Medicine. Philadelphia, PA: Saunders; 2003:2012-2067.

2.  Cain LE, Gillogly SD, Andrews JR. Management of intraoperative complications associated with autogenous patellar tendon graft anterior cruciate ligament reconstruction. Instr Course Lect. 2003;52:359-367.

3.  Schock H, Freedman KB. Intraoperative complications: graft fixation problems. In Freedman KB, ed. AAOS Monograph Complications in Orthopaedics: Anterior Cruciate Ligament Surgery. Rosemont, IL: AAOS; 2005:9-19.

4.  Dalton J, Harner C. Surgical techniques to correct nonanatomic femoral tunnels. Oper Tech Sports Med. 1998;6:83-90.

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