Fig. 12.1
(a) Incision and (b) scar following conventional quadriceps tendon harvest
The minimally invasive harvest techniques described in this chapter, in conjunction with recent development of specialized instrumentation, allow for a reproducible, safe, and easy graft harvest with improved cosmetic appearance (Fig. 12.2).
Fig. 12.2
Cosmetic appearance following minimally invasive quadriceps tendon harvest via (a) longitudinal or (b) horizontal incision
12.2 Indications and Contraindications
The QT is an appropriate choice for most patients undergoing ACL reconstruction. We have used QT as a primary graft option for several years in patients of all ages and activity levels, including elite athletes. Patients who perform a significant amount of kneeling for sport or employment and those with coexisting medial collateral ligament injury are excellent candidates for QT ACL reconstruction as the anterior knee pain associated with BTB harvest can be avoided and the dynamic stability provided by the medial hamstrings can be preserved. Graft-tunnel mismatch can be avoided in patients with longer patellar tendons. Contraindications for QT ACL reconstruction are few. These include prior quadriceps tendon surgery or injury, quadriceps tendinopathy, untreated coagulopathy, or large cavitary lesions in the revision setting.
12.3 Anatomy
The anatomy of the quadriceps tendon has traditionally been described as trilaminar, with the superficial fibers coming from the rectus femoris, the vastus medialis and vastus lateralis coalescing to form the middle layer, and the deepest portion extending from the vastus intermedius. In reality, this is a simplification of the great variation in contribution and pattern of fibers [19]. While the deeper fibers insert on the anterior edge of the superior pole of the patella, the most superficial fibers continue anterior to the patella and join the patellar tendon, and the most medial and lateral fibers contribute to the patellar retinaculum. The synovial tissue lines the deep surface of the quadriceps tendon as it forms the roof of the suprapatellar pouch extending approximately 5 cm above the superior pole of the patella [15].
The quadriceps tendon is thickest at the patellar insertion, on average 16 mm in female patients and 18 mm in male patients, and thins proximally as the contributing fibers separate from a common tendon at about 5–6 cm proximal to the insertion [20]. The average thickness of the central portion of this common tendon is 7–8 mm, and the average width is 27 mm [6, 20]. The average total length of the quadriceps tendon from the superior pole of the patella to the myotendinous junction of the rectus femoris is around 8 cm and correlates highly with patient height [20]. This allows for a graft of consistent length (7–8 cm), depth (6–7 mm), and width (9–10 mm) to be harvested [2] with an intra-articular volume 187.5 % greater than that of a similar-width patellar tendon graft taken from the same subject [20]. The vascular supply to the quadriceps tendon includes contributions from medial, lateral, and peripatellar arcades [21]. The lateral perforating vessels tend to be at greatest risk of being encountered during harvest.
12.4 Preoperative Planning
The quadriceps tendon autograft has less variability in diameter when compared to hamstring autograft, and its thickness can be evaluated preoperatively on most routinely ordered knee MRIs. The quadriceps tendon should be measured at the midsagittal point of maximal thickness, 3 cm proximal to the superior pole of the patella (Fig. 12.3). It is unusual for the quadriceps tendon thickness to be inadequate for ACL reconstruction, as the intra-articular volume of graft tends to be larger and closer to anatomic than bone-tendon-bone reconstructions. Although partial-thickness grafts are preferred, a full-thickness graft should be planned if the tendon is less than 6 mm thick. We have not noticed any functional difference between patients who have received partial vs. full-thickness harvests if capsular rents are repaired.
Fig. 12.3
Midsagittal measurement of quadriceps tendon thickness is performed 3 cm proximal to the proximal pole of the patella
12.5 Surgical Technique
12.5.1 Exposure of the QT
Examination of the injured knee is performed following induction of general anesthetic. A tourniquet is applied to the operative leg, which is then placed in a circumferential leg holder. The operative leg should rest at ninety degrees of knee flexion, putting tension on the extensor mechanism during graft harvest. The operative leg is then prepped and draped in a sterile fashion (Fig. 12.4).
Fig. 12.4
Positioning with the operative leg in a circumferential leg holder and nonoperative leg in a lithotomy leg holder. The bony landmarks, arthroscopy portals, and harvest incision are marked
Diagnostic arthroscopy can be performed before or after graft harvest according to surgeon preference. The distal vastus medialis obliquus and proximal pole of the patella are marked. A 1.5–2-cm mark is made at the planned incision site, starting just lateral to the midpoint of the superior pole of the patella, extending proximally along the length of the tendon longitudinally (Fig. 12.4). Alternatively, a 2–3-cm transverse incision over the superior boarder of the patella may be used. If arthroscopy is performed prior to graft harvest, it is important to suction all arthroscopy fluid from the knee, as capsular distention can make full-thickness violations more likely. Local anesthetic is injected into the planned incision site, which helps to distend the subcutaneous and areolar tissue. A 15-blade scalpel is used to make the harvest incision, and the subcutaneous and areolar tissue is widely excised (Fig. 12.5). This step is critical for adequate visualization through the small incision. The paratenon is incised, and a RayTech sponge is used over a key elevator to sweep soft tissue off the anterior QT and anteriorly over the patella. An Army-Navy retractor or alternatively a long Langenbeck retractor is then placed. The arthroscope may be introduced into the wound with the fluid off, visualizing the tendon. The VMO, vastus lateralis, and distal rectus femoris musculotendinous junction are identified (Fig. 12.6). Crossing vessels should be coagulated with electrocautery or radiofrequency ablator to avoid postoperative hematoma at the harvest site. The arthroscope is advanced to the distal rectus femoris musculotendinous junction, and the arthroscope light source is used to transilluminate the skin over the anterior thigh. A mark is placed in the center of the point of maximum transillumination, which corresponds to the distal rectus femoris musculotendinous junction (Fig. 12.7). The distance from the proximal pole of the patella to the mark over the distal rectus femoris is measured. This distance represents the maximum length that is obtainable with an all soft tissue graft and usually measures over 8 cm.
Fig. 12.5
The subcutaneous tissue and areolar tissue are widely excised
Fig. 12.6
The arthroscope (with fluid off) is used to view the quadriceps tendon, vastus medialis obliquus, vastus lateralis, and rectus femoris
Fig. 12.7
The arthroscope is advanced to the level of the distal musculotendinous junction of the rectus femoris and light source turned to transilluminate the skin over the anterior thigh, and a mark is placed in the center of transillumination
Currently two different instrumentations for minimally invasive quadriceps tendon harvest are in clinical use:
12.5.2 Quad Tendon Harvesting System [Arthrex (Naples, FL)] [14]
With the knee at 90° of flexion, the Arthrex (Naples, FL) triple-blade harvest knife is used to incise the tendon starting just proximal to the superior pole of the patella, advancing toward the musculotendinous junction of the rectus femoris, which is identified by the mark previously placed on the anterior skin (Fig. 12.8). Markings on the knife handle allow for measurement of the QT incision. A 15 blade is used to extend the distal parallel incisions to the proximal pole of the patella, tapering the graft slightly, as graft diameter will increase slightly with later suture addition and graft preparation. The transverse limbs are connected, subperiosteally dissecting the tendon off of the patella. Proximal dissection is continued with metzenbaum scissors or scalpel. Tendon harvest depth is referenced off of the vertical limbs created by the triple-blade harvest knife. A layer of fat usually exists between the tendon and capsule. If fat is encountered, avoid deeper dissection or risk capsular violation if planning for a partial-thickness harvest. An Allis clamp can be placed on the distal tendon, which facilitates control and tension on graft as dissection is carried out proximally.
Fig. 12.8
The triple-blade harvest knife (Arthrex, Naples, FL) is used to incise the tendon longitudinally, starting proximal to the patella and advancing in the direction of the previously placed mark on the skin identifying the distal rectus femoris musculotendinous junction
Once 3 cm of tendon has been dissected free, an Arthrex Fiberloop (Naples, FL) suture is used to place 4 throws in the tendon, starting 1.5–2 cm proximal to the dissected tendon end, continuing distally, locking the last stitch, which exits the central portion of the tendon. The needle is left in place for later graft preparation. Tension is placed on these sutures during further proximal dissection, which is continued with metzenbaum scissors. Once 4–5 cm of tendon has been elevated, the Arthrex (Naples, FL) stripper/cutter is used to first strip and then cut the tendon, with firm tension on the previously placed sutures (Fig. 12.9). Currently, we harvest grafts 6.5–7 cm in length when performing anatomic ACL reconstruction with an accessory medial portal technique and suspensory fixation. The harvested graft is delivered from the wound and brought to the back table for graft preparation and sizing (Fig. 12.10).
