Minimally Invasive Harvest of a Quadriceps Tendon Graft With or Without a Bone Block

Abstract

The quadriceps tendon (QT) as a graft source for anterior cruciate ligament (ACL) and posterior cruciate ligament reconstruction has recently achieved increased attention. Although many knee surgeons have been using the QT as a graft for ACL revision surgery, it has never gained universal acceptance for primary ACL reconstruction. The QT is a very versatile graft that can be harvested in different widths, thicknesses, and lengths. Conventionally, the QT graft is harvested by an open technique, requiring a 6 to 8 cm longitudinal incision, which often leads to unpleasant scars. We describe a new, minimally invasive, standardized approach in which the QT graft can be harvested through a 2- to 3-cm skin incision and a new option of using the graft without a bone block.

The quadriceps tendon (QT) as a graft source for anterior cruciate ligament (ACL)^1-5 and posterior cruciate ligament (PCL)⁶ reconstruction has recently achieved increased attention. Although many knee surgeons have been using the QT as a graft for ACL revision surgery,^7,8 it has never gained universal acceptance for primary ACL reconstruction. The main reason, in our opinion, is that QT graft harvest is technically more demanding and a scar on the thigh is cosmetically less favorable, despite excellent clinical results in the literature.^3,9-13 In the late 1990s Stäubli et al.,^14,15 from Switzerland, published anatomic and biomechanical details of the QT and were the first advocates of its use as a primary ACL graft. Excellent clinical outcomes have been documented for the use of the QT in ACL revision surgery as well.^7,8 The QT has also been successfully used for PCL reconstruction.⁶

The QT is a very versatile graft that can be harvested in different widths, thicknesses, and lengths and can be used with or without a bone block. If a preoperative magnetic resonance imaging study is available, it is helpful to examine the QT and evaluate the thickness.^16,17 Conventionally, the QT graft is harvested by an open technique, requiring a 6 to 8 cm longitudinal incision.¹⁸ We present a new, minimally invasive, standardized approach in which the QT graft can be harvested through a 2 to 3 cm skin incision and a new option of using the graft without a bone block.

Surgical Technique

In 90° of knee flexion, a 2.5 to 3 cm transverse skin incision (alternatively, a 3 cm longitudinal incision) is placed over the superior border of the patella. The prepatellar bursa is incised longitudinally, and the QT is then carefully exposed (Fig 1).

Fig 1.

Skin incisions. A 2.5 to 3 cm transverse skin incision (solid line) may be recommended for the best cosmetic result. Alternatively, a 2.5 to 3 cm longitudinal incision (dotted line) may be used.

A long Langenbeck retractor is introduced, and the QT is subcutaneously exposed proximal to the patella. A double knife (Karl Storz, Tuttlingen, Germany) 8 to 12 mm in width is then introduced, starting in the middle or slightly lateral to the middle of the superior patellar border and pushed up to a minimum of 6 cm (if used with bone block for ACL or 8 cm for PCL) (Fig 2). The thickness of the graft (5 mm) is determined using a tendon separator (Karl Storz). The knife is pushed proximal to the same mark (Fig 3). Finally, the tendon strip is cut subcutaneously by a special tendon cutter (Karl Storz) (Fig 4), and the graft is retrieved through the skin incision.

Fig 2.

A double knife is introduced starting slightly lateral to the middle of the superior patellar border^11,18 and pushed up (white arrow) to the desired tendon length. There are centimeter markings on the instrument.

Fig 3.

Graft thickness is determined using a 5 mm tendon separator. The tendon separator is then pushed proximally (white arrow) to the previously determined length. There are centimeter markings on the instrument.

Fig 4.

The tendon strip is cut subcutaneously by a special tendon cutter at the determined length (white arrow).

There are 2 options at this point: QT with a bone block and QT without a bone block (Table 1).

Table 1.

Pros and Cons of Bone Block Use

Bone block

Pro: quicker graft-to-tunnel healing

Con: risk of patellar fracture

Soft-tissue graft

Pros: No fracture risk; may be used in case of open physes

Con: slower graft-to-tunnel healing

Option 1: QT With Bone Block

The tendon strip is elevated and then followed distally to its bony attachment. The dimensions of the bone block (1.5 to 2 cm in length and respective graft width) are outlined. The bone cuts are made with an oscillating saw, starting with the longitudinal cuts. The graft is then elevated, and the final cut determining the thickness of the bone block is made from proximal to distal. The bone block is then easily elevated with a chisel (Fig 5). All the steps of the harvesting procedure are summarized in Video 1. These steps avoid extensive use of the chisel and hammer to remove the block and reduce the risk of a patellar fracture.

Fig 5.

The bone block is harvested using an oscillating saw. (A) First, the longitudinal and transverse cuts are made. (B) The last cut determines the thickness of the bone block and is made from proximal to distal. (C) Finally, the block is easily elevated.

We recommend harvesting the bone block last. Harvesting the bone block first is commonly associated with taking an unnecessary amount of bone, as well as an increased risk of opening the joint capsule.

The bone block is prepared to the appropriate size, and one or two 1.5 mm holes are drilled through. We prefer to use a square bone block rather than a round bone block.^2,19 The bone block can then be fixed to a flip-button device (e.g., EndoButton [Smith & Nephew, Andover, MA]) by strong nonresorbable sutures (e.g., No. 2 FiberWire [Arthrex, Naples, FL]) or by only a resorbable pullout suture if it is fixed later with an interference screw.

Option 2: QT Without Bone Block

The tendon strip is elevated and then followed distally to its bony attachment. The parallel longitudinal cuts are continued with a surgical knife toward the patella and 2 cm over the patellar surface. The QT graft is then subperiosteally elevated from the surface of the patella (Fig 6) and detached. The periosteal part of the graft is folded in the middle, and web-stitch sutures are placed on each side of the graft using strong No. 2 suture (e.g., No. 2 FiberWire) (Fig 7). This will result in a smooth, round end of the graft, which allows easier graft passage. It also gains about 1 cm of additional graft length. Both aspects are a major point for using the QT for PCL reconstruction. The sutures are then passed through a flip-button device (e.g., EndoButton) for later fixation. Alternatively, a soft-tissue interference screw may be used for femoral fixation.

Fig 6.

(A) After retrieving the QT graft, it is pulled distally, and (B) a strip of periosteum in the appropriate width is detached about 2 cm in length.

Fig 7.

Graft preparation without bone block. (A) Final graft with strip of periosteum measuring approximately 2 cm. (B) The periosteum is folded in the middle and (C) fixed in the clamp of a preparation board. (D) Web-stitch sutures are placed on each side of the graft using nonresorbable No. 2 suture material. (E, F) This results in a smooth, round end of the graft, which allows easy graft passage.

Closing Tendon Defect

A long Langenbeck retractor is reintroduced, and the tendon defect is closed. The stitches should be placed in the superficial aspect of the tendon to avoid shortening of the tendon (“fan-like closure”). The prepatellar bursa is carefully closed over a bony defect.

Discussion

QT harvest, following the aforementioned steps, is a safe and reliable procedure (Table 2). By use of this minimally invasive technique, the cosmetic outcome can be markedly improved and the surgical time reduced compared with conventional open harvesting techniques. As a soft-tissue graft, it may also be used in children with open physes.

Table 2.

Potential Complications

Graft is too short

Inspect the QT before harvesting to look for the longest tendon part (the surgeon may place the arthroscope in the skin incision).

Start harvesting slightly lateral to the center of the proximal border of the patella.

Angle the double knife and the tendon separator approximately 30° to the QT to avoid early cutout.

As a solution, use a different graft; note that in some cases, a second QT graft can be harvested adjacent to the first.

Patellar fracture

Avoid forceful action with the chisel and hammer to the front of the patella.

As a solution, perform ORIF (with 2 cannulated small-fragment screws).

ORIF, open reduction–internal fixation.

Whether the use of a bone block is advantageous over the use of the QT as a pure soft-tissue graft has yet to be established. The use of a periosteal strip was found to facilitate graft passage through the tunnels. Theoretically, the use of a periosteal tendon part might also lead to improved tendon-to-bone healing compared with a QT graft that is simply cut proximal to the patella.

We think that improving and simplifying QT harvest will make this graft increasingly attractive not only for revision but also for primary ACL/PCL reconstruction.

Supplementary Data

Video 1

Surgical technique for minimally invasive harvesting of QT graft: A 5 mm-thick and 10 mm wide strip of QT is harvested subcutaneously using special instrumentation from Karl Storz. The graft is harvested with a bone block from the patella in the appropriate dimensions.