Quadriceps Tendon Autograft for Anterior Cruciate Ligament Reconstruction: A Comprehensive Review of Current Literature and Systematic Review of Clinical Results

Systematic Review

Quadriceps Tendon Autograft for Anterior Cruciate Ligament Reconstruction: A Comprehensive Review of Current Literature and Systematic Review of Clinical Results Harris S. Slone, M.D., Spencer E. Romine, M.D., Ajay Premkumar, and John W. Xerogeanes, M.D.

Purpose: The autograft of choice for anterior cruciate ligament (ACL) reconstruction remains controversial. Recently, there has been an increase in interest in the quadriceps tendon as an autologous graft option for ACL reconstruction. The purposes of this study were to provide an in-depth review of quadriceps tendon anatomy, histology, and biomechanics and to synthesize reported clinical outcomes of ACL reconstructions using quadriceps tendon autografts. We hypothesize that (1) published studies on the anatomic, histologic, and biomechanical data regarding the quadriceps tendon support its use as a graft option for ACL reconstruction and (2) clinical outcomes of ACL reconstruction using quadriceps tendon autograft have similar clinical outcomes to boneepatellar tendonebone autografts with less donor-site morbidity. Methods: We performed a comprehensive review of the literature regarding the anatomy, histology, and biomechanical studies of the quadriceps tendon, as well as a systematic review of clinical studies (Level of Evidence I-III) evaluating outcomes after ACL reconstruction using quadriceps tendon autograft. Stability outcomes, functional outcomes, range of motion, patient satisfaction, morbidity, and complications were comprised. Results: Fourteen studies were included in the review of clinical results, including 1,154 ACL reconstructions with quadriceps tendon autograft. Six studies directly compared quadriceps tendon autografts (n ¼ 383) with boneepatellar tendonebone autografts (n ¼ 484). Stability outcomes (Lachman, pivot-shift, and instrumented laxity testing), functional outcomes (International Knee Documentation Committee and Lysholm scores), overall patient satisfaction, range of motion, and complications were similar between quadriceps tendon and other graft options. Less donor-site morbidity was seen in patients who underwent quadriceps tendon ACL reconstructions. Conclusions: Use of the quadriceps tendon autograft for ACL reconstruction is supported by current orthopaedic literature. It is a safe, reproducible, and versatile graft that should be considered in future studies of ACL reconstruction. Level of Evidence: Level III, systematic review of Level I, II, and III studies.

T

he autograft of choice for anterior cruciate ligament (ACL) reconstruction remains controversial. Despite well-documented morbidities such as anterior knee pain and the risk of patellar fracture, some orthopaedists consider the central-third patellar tendon autograft to be the gold standard for reconstruction.1

From the Department of Orthopaedic Surgery, Emory University (H.S.S., S.E.R., A.P., J.W.X.), Atlanta, Georgia; and Department of Orthopaedics, The Medical University of South Carolina (H.S.S.), Charleston, SC, U.S.A. The authors report the following potential conflict of interest or source of funding: J.W.X. receives support from Arthrex, Linvatec, Ossur, and DonJoy. Received August 1, 2014; accepted November 5, 2014. Address correspondence to John W. Xerogeanes, M.D., Emory University, 59 Executive Park South, Ste 1000, Atlanta, GA 30329, U.S.A. E-mail: [email protected] Ó 2015 by the Arthroscopy Association of North America 0749-8063/14667/$36.00 http://dx.doi.org/10.1016/j.arthro.2014.11.010

Proponents of hamstring autograft cite low donor-site morbidity, better extension strength,2 and a lower incidence of long-term degenerative joint disease3,4; however, weakness of terminal knee flexion,5 graft laxity, and variable sizes and lengths of grafts remain problematic.6 The advantages and disadvantages of autograft choices for ACL reconstruction have been previously reviewed in detail.7 The quadriceps tendon is the least studied and least used autograft for ACL reconstruction, although interest in and use of quadriceps tendon seem to be increasing. A poll at a recent American Academy of Orthopaedic Surgeons meeting showed that only 1% of orthopaedic surgeons used the quadriceps tendon as a graft for ACL reconstruction.8 In 2010 a systematic review on graft choice for anatomic ACL reconstruction showed that 2.5% of all anatomic ACL reconstructions used quadriceps tendon autograft.9 In 2014 Middleton

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et al.10 collected data on 35 surgeons from over 20 countries at an international summit on anatomic ACL reconstruction. The experts polled averaged over 2,100 ACL reconstructions over their careers, and quadriceps tendons are being used in 11% of all ACL reconstructions. In 1997 Harris et al.11 noted that a comprehensive evaluation of the anatomy, biomechanics, and clinical results of the quadriceps tendon autograft for ACL reconstruction had not been published. Seventeen years later, such a review has yet to be written. Recent studies have shown excellent clinical results and low morbidity with the use of the quadriceps tendon autograft, especially when harvested as a free tissue graft without a bone plug.12,13 The purposes of this article are to provide an in-depth review of quadriceps tendon anatomy, histology, and biomechanics and to synthesize reported clinical outcomes of ACL reconstructions using quadriceps tendon autografts. Furthermore, the gross anatomic findings from an ongoing study of autograft harvest techniques will be discussed.

Review of Quadriceps Tendon Anatomy The anatomy, histology, and imaging of the extensor mechanism have been studied extensively; however, anatomic implications for quadriceps autograft harvest have not been thoroughly discussed. An improved knowledge of the quadriceps tendon morphology, variations, and surrounding anatomy should improve graft-harvesting techniques. In addition, histologic as well as magnetic resonance imaging (MRI) studies examining the structure of the quadriceps tendon are important in further delineating the qualities of the tendon that make it a useful graft for ACL reconstruction. Gross Anatomy Apart from strictly descriptive studies, most gross anatomic studies of the quadriceps tendon have been performed for the purpose of improving results after a medial parapatellar incision used in total knee arthroplasty.14 These studies, as well as others, have shown that the quadriceps tendon anatomy is highly variable, often with unequal contributions from its tendinous constituents. Traditionally, the quadriceps tendon is described as trilaminar, with the most superficial fibers primarily composed of the rectus femoris and the deepest layer made up of the vastus intermedius. A thin fatty layer separates the rectus femoris and vastus intermedius. The most superficial fibers of the rectus femoris are believed to traverse the patella to join the patellar tendon whereas the deep fibers insert into the patella. The vastus medialis and vastus lateralis coalesce to form the middle layer, whereas distal expansion

of their fibers contributes to the patellar retinacula15 (Fig 1). The existence, structure, and function of the vastus medialis obliquus has been debated.16 Despite this classic description, Waligora et al.14 found that only 3 of 20 specimens exhibited the typical trilaminar pattern at the insertion into the patella. Bilaminar, tetralaminar, and complex trilaminar patterns were common. In addition, the tendinous portion of the articularis genus muscle occasionally contributes to the quadriceps tendon.17 An anatomic variant, this muscle is deep to the vastus intermedius, sometimes consisting of several separate muscular bundles, without distinct investing fascia, and ranges from 1.5 to 3.0 cm in width. Harris et al.11 examined 15 preserved and 6 freshfrozen cadaveric knees and found that the rectus femoris and vastus intermedius were joined (termed “common tendon length”) along with the vastus medialis and lateralis at approximately 6 cm from the superior pole of the patella (Fig 2). The average quadriceps tendon width was 27 mm, and the average thickness of the common tendon was approximately 8 mm. The authors also noted that the tendon tends to develop laterally from its insertion on the patella, suggesting that tendon harvest should err to the lateral side. Despite the variability in quadriceps tendon morphology, a graft of consistent length (7 to 8 cm), depth (6 to 7 mm), and width (9 to 10 mm) can be harvested with careful surgical technique without violation of the suprapatellar pouch.13 The anterior superficial portion of the tendon is extraarticular, whereas the posterior deepest portion is lined with synovium, which can be seen during routine arthroscopy18 (Fig 3). Gross dissection of 16 cadaveric knees found that with the knee flexed, the average length of the quadriceps tendon was 85 mm (95% confidence interval, 78 to 95 mm) measured from the patellar base to the myofascial junction of the rectus femoris.19 The articular cartilage of the patella is 7 to 10 mm from the insertion of the tendon to the base of the patella. Xerogeanes et al.20 recently showed that the length of the quadriceps tendon from the superior pole of the patella to the myotendinous junction of the rectus femoris was an average of 73.5  12.3 mm in female patients and 81.1  10.6 mm in male patients. These measurements were most highly correlated with patient height. The vascular anatomy of the quadriceps tendon is complex, with contributions from 3 arcades (medial, lateral, and peripatellar).21 The medial aspect of the tendon is supplied in a proximal-to-distal fashion by anastomoses among the muscular branches of the femoral artery, the descending geniculate artery, and the superior medial genicular artery division of the popliteal artery. The medial arcade runs between the muscular portions of the vastus medialis and the medial aspect of the rectus femoris and vastus intermedius.

QUADRICEPS TENDON AUTOGRAFT

3

Fig 1. Anterior view of the right knee of a cadaveric specimen of the quadriceps tendon with vastus musculature (A) intact and (B) reflected. The dotted line represents the proximal pole of the patella. The solid line is approximately 6 cm proximal to the superior pole of the patella. The wide expansion of the vastus medialis and lateralis tendinous contribution to the quadriceps tendon should be noted. (C) An 8-cm-long, 10-mm-wide partial-thickness graft has been harvested with the vastus intermedius remaining. (P, patella; RF, rectus femoris; VI, vastus intermedius; VL, vastus lateralis; VM, vastus medialis.)

Laterally, the arcade is formed by the long descending branch of the lateral femoral circumflex artery, which arises from the distal perforating artery of the vastus lateralis. The lateral femoral circumflex artery anastomoses with the superior lateral genicular artery, a branch of the popliteal artery. Similar to the medial aspect of the tendon, the lateral arcade courses between the rectus femoris and vastus lateralis. The medial and lateral vascular arcades anastomose within and below the rectus femoris musculature. The tendon has been shown to be relatively hypovascular in a region approximately 1 to 2 cm proximal to the superior pole of the patella, with vascularity within the superficial portion of the quadriceps tendon being more abundant than in the deep layers (vastus intermedius).22

Fig 2. Mid-sagittal view of the right knee distal quadriceps insertional anatomy showing the length of the common tendon (CT) consisting of the conjoined rectus femoris (RF) and vastus intermedius (VI) and the proximal extent of the suprapatellar pouch. (A) The suprapatellar pouch correlates with the approximate level of the common tendon origin (5 to 6 cm proximal to superior pole of patella). (B) The thickness of the distal quadriceps tendon is shown, which is often 7 to 10 mm. (F, femur; P, patella.)

Histology Hadjicostas et al.23 investigated the quadriceps and patellar tendon morphology using light and electron microscopy, immunohistochemistry, and morphometry. Harris et al.11 had previously used morphometric analysis to show that the thickness of the quadriceps tendon was 1.8 times that of the patellar tendon and that the quadriceps tendon had significantly higher ultimate strength. Twenty cadaveric specimens of the quadriceps and patellar tendons were harvested. The thickness of the collagen fibrils, fibril-interstitium ratio, density of blood vessels and fibroblasts, and distribution of collagen fibrils were analyzed. Statistically significant differences were found showing that the quadriceps

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Fig 3. Arthroscopic view of the undersurface of the quadriceps tendon (QT) viewed from the suprapatellar pouch before quadriceps tendon harvest.

tendon had a higher fibril-interstitium ratio (P ¼ .0004) and a higher fibroblast density (P ¼ .0011). The quadriceps tendon graft contained approximately 20% more collagen that the patellar tendon graft with the same thickness, which the authors concluded explained the difference in the higher ultimate strength of the quadriceps tendon graft. A similar study comparing patellar and hamstring tendon grafts showed that the semitendinosus and gracilis tendons provide a significantly higher density of collagen fibrils and fibroblasts than patellar tendons as well.24 Lee et al.25 performed biopsies of 37 quadriceps tendon autografts with bone plugs obtained at secondlook arthroscopy. The biopsy specimens showed a bimodal pattern of large- and small-diameter fibrils similar to the pattern present in the native ACL. A unimodal pattern of small collagen fibrils has been shown in allograft and mature boneepatellar tendonebone autograft. Large fibrils are necessary for high tensile strength; loss of these fibrils is associated with a high rate of ligament failure. Imaging The multilayered laminar appearance of the quadriceps tendon has been well described and is readily apparent with the use of MRI.26 As previous anatomic studies have shown, MRI evidence supports the fact that the quadriceps tendon is not simply a trilaminar structure. Zeiss et al.26 studied the MRI appearance of 52 knees with normal tendons and found that the number of laminations was variable, with either 4 layers (6%), 3 layers (56%),

or 2 layers (30%). In 8% of knees, the laminations were barely perceptible. Stäubli et al.19 have further explored the quadriceps tendon with analysis of 53 knees (21 female and 32 male patients) with intact extensor mechanisms with sagittal magnetic resonance arthrography. The average length of the quadriceps tendon measured from the superior pole of the patella to the most superior aspect of the suprapatellar pouch (i.e., intra-articular length) was 49  7 mm in women and 50  9 mm in men. The average thickness of the central portion of the quadriceps tendon at the superior aspect of the suprapatellar pouch measured 7  1 mm in women and 8  1 mm in men. Schweitzer et al.27 reported similar measurements, with the mean thickness of the tendon averaging 8 mm in male patients and less than 8 mm in female patients at the same level. In our recent series of 60 patients, we similarly found the thickness of the distal 6 cm of quadriceps tendon to be, on average, between 7 and 8 mm.20 As seen on gross dissection, the average thickness of the tendon at the patellar insertion is greatest, measuring 16  2 mm in female patients and 18  3 mm in male patients. In addition, we found the intra-articular volume of the proposed quadriceps tendon graft to be 187.5% greater than that of a similar-width patellar tendon graft taken from the same subject20 (Fig 4).

Observations With Respect to Harvesting Technique As the 4 tendons coalesce at the superior pole of the patella, this region of the tendon is the thickest and thins proximally as the contributing fibers separate. On the basis of data from imaging studies, the average thickness at the patellar insertion is 16  2 mm in female patients and 18  3 mm in male patients. As reported previously in anatomic and imaging studies, multiple laminar configurations of the quadriceps tendon were observed in our specimens. According to the MRI measurements performed by Stäubli,28 the suprapatellar pouch extends for a distance of approximately 5 cm as measured from the superior pole of the patella. In addition, we observed that the common tendon, composed of the rectus femoris and vastus intermedius, began at approximately the same level as the proximal aspect of the suprapatellar pouch; this was located at approximately 5 to 6 cm proximal to the superior pole of the patella in our specimens. As a result of this finding, violation of the suprapatellar pouch is unlikely with graft harvest proceeding proximal to the level of the common tendon (5 to 6 cm). Perforating vessels laterally and the descending branch of the lateral circumflex femoral artery (LCFA) are in danger during harvest. The descending branch of the LCFA, which is the basis of the anterolateral thigh flap,

QUADRICEPS TENDON AUTOGRAFT

5

Fig 4. Axial magnetic resonance images of a left knee are shown with a computer-generated 3-dimensional magnetic resonance imaging model of the distal quadriceps tendon (A) before and (B) after 10-mm-wide graft harvest. (VMO, vastus medialis obliquus.)

has a variable course but is most often found between the vastus lateralis and rectus femoris before traveling posterior to the rectus. Distally, the vessel anastomoses with the lateral superior genicular artery, a branch of the popliteal artery.29 The descending branch of the LCFA was not visualized coursing posterior to the rectus in our specimens as has been described. As mentioned previously, a thin fatty layer exists between the superficial rectus femoris and deep vastus intermedius. During dissection and harvesting, the fatty layer is most prominent proximally as the rectus femoris and vastus intermedius separate. The fatty layer can be followed distally to locate the common tendon and thus the proximal aspect of the suprapatellar pouch. As reported by Harris et al.,11 the separation of the rectus femoris and vastus intermedius into separate tendons

occurred reliably at approximately 6 cm proximal to the superior pole of the patella. Controversy exists as to which side of the quadriceps tendon should be harvested. DeAngelis and Fulkerson13 have recommended taking the graft from the medialcentral aspect because this is the thickest portion of the tendon. Harris et al.11 noted that the tendon tends to develop laterally from its insertion, suggesting that tendon harvest should err to the lateral side. No significant difference was noted in our specimens regarding tendon thickness or the development of a more robust tendon from the medial or lateral aspect of the insertion. Recently, Lippe et al.30 performed an anatomic study of 11 cadaveric knees to define guidelines for obtaining the maximum length and bulk of quadriceps autograft harvest for ACL reconstruction. The maximum tendon

Fig 5. Flow of studies through systematic review.

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Table 1. Study Characteristics

Study Akoto51 Chen52 Gorschewsky46

Year 2012 2006 2007

Journal BMC KSSTA KSSTA

Study Design Prospective cohort Retrospective cohort Retrospective comparative

Grafts Evaluated QTB QTB QTB BPTB

Gorschewsky53

2007

AJSM

Retrospective comparative

QTB

Han47

2008

CORR

Retrospective comparative

QTB BPTB

Kim45

2014

AJSM

Retrospective cohort

QTB BPTB QHS Allograft

Kim49

2009

JBJS

Retrospective comparative

DB QTB BPTB

Kim48

2009

Arthroscopy

Retrospective comparative

QTB BPTB

Kim54

2009

Arthroscopy

Retrospective comparative

QTB DB QTB

Kohl55 Lee56 Lee57 Lund50

2013 2007 2007 2014

Knee JBJS Arthroscopy Arthroscopy

Prospective cohort Prospective cohort Retrospective cohort Randomized controlled trial

Schulz58

2013

OAJSM

Prospective cohort

QT QTB QTB QTB BPTB QT

No. of Patients Completing Study 30 total 34 total 194 total 93 QTB 101 BPTB 193 total 144 total 72 QTB 72 BPTB 487 total 142 QTB 227 BPTB 65 QHS 53 Allograft 61 total 29 DB QTB 32 BPTB 48 total 21 QTB 27 BPTB 59 total 28 QTB 31 DB QTB 15 total 247 total 138 total 51 total 26 QTB 25 BPTB 55 total

Follow-up, mo 12 (minimum) 48 (minimum) 24 (minimum)

Age (Mean), yr 31 26 32

Minimum, 24 Mean, 29 24 (minimum)

33 28

24 (minimum)

31

24 (minimum)

27

24 (minimum)

29

24 (minimum)

26

49 24 24 12

(mean) (minimum) (minimum) (minimum)

13 29 27 31

24 (minimum)

32

AJSM, Am J Sports Med; BMC, BMC Musculoskelet Disord; BPTB, boneepatellar tendonebone; CORR, Clin Orthop Relat Res; DB, double bundle; JBJS, J Bone Joint Surg; KSSTA, Knee Surg Sports Traumatol Arthrosc; OAJSM, Open Access J Sports Med; QHS, quadruple hamstring; QT, quadriceps tendon; QTB, quadriceps tendonebone.

length and depth were located at approximately 61.6%  4.1% of the width of the tendon from the medial border of the quadriceps tendon insertion on the patella. This correlated with a lateral peak of the tendon proximally. The authors concluded that to obtain a maximum length of a 10-mm-wide, 7-mm-thick graft, harvest should proceed by centering the graft approximately 2 mm medial to this point.

Biomechanics Initial biomechanical data were unfavorable for the quadriceps tendon autograft. In 1984 Noyes et al.31 showed that it was significantly weaker than the native ACL, failing at 14% to 21% of the ultimate load of the ACL. It should be noted that initial testing by Noyes et al. used the quadriceps tendon “substitution” graft that was initially described by Marshall et al.32 The substitution graft consisted of the quadriceps tendoneprepatellar retinaculumepatellar tendon construct. This construct is significantly different than the quadriceps tendonebone

(QTB) construct used in subsequent studies. Several biomechanical studies in the late 1990s showed improved results with the use of the quadriceps tendonepatellar bone construct.11,19 Most biomechanical studies of the quadriceps tendon have been performed using a patellar bone block and not as a free graft. Harris et al.11 found that the load to tendon failure using a 1-cm-wide and 9-cm-long full-thickness quadriceps autograft with insertion to the intact patella occurred at 1,075  449 N, which was 1.36 times that of a comparable-width patellar tendon graft, although the difference was not statistically significant. Stäubli et al.19 analyzed sixteen 1-cm-wide full-thickness central quadriceps tendons and patellar tendons from paired knees of 8 male donors (mean age, 24.9 years). Half of the grafts were tested unconditioned, and the remaining grafts were tested after cyclic preconditioning (200 cycles between 50 and 800 N at 0.5 Hz). The mean cross-sectional areas of the quadriceps autografts were significantly larger than those of the patellar autografts. The mean ultimate tensile stress values of

7

QUADRICEPS TENDON AUTOGRAFT Table 2. Stability Outcomes Lachman Test Study Akoto51 Chen52 Gorschewsky46

Gorschewsky53 Han47 Kim45

Kim49 Kim48 Kim54 Kohl55 Lee56 Lee57 Lund50 Schulz58

Graft QTB QTB QTB

BPTB QTB (pin) QTB (screw) QTB BPTB QTB BPTB QHS Allograft DB QTB BPTB QTB BPTB QTB DB QTB QT QTB QTB QTB BPTB QT

Pivot-Shift Test

Anteroposterior Laxity (Side-to-Side Difference)

0 1þ 2þ 3þ 0 1þ 2þ 3þ Instrument (Force) 27 3 0 0 25 1 4 d Rolimeter (maximum) 30 3 1 0 d d d d KT-1000 (134 N) No difference No difference d KT-1000 (not specified)

Result Mean, 1.6 mm Mean, 1.7 mm; <3 mm, 82% No difference between QTB and BPTB (numbers not specified)

No difference No difference d d d d d d d d KT-1000 (maximum) 95% 0 to 1þ 95% 0 to 1þ 95% 0 to 1þ 95% 0 to 1þ 112 23 7 d 117 187 32 8 d 193 49 13 3 d 53 37 13 3 d 39 20 9 0 0 29 20 18 2 0 29 17 2 2 0 17 23 3 1 0 24 23 4 1 0 24 28 3 0 0 31 d d d d d 95% 0 to 1þ 95% 0 to 1þ d d d d d d d d d 14% Positive 38% Positive 23 21 10 1 0

20 5 28 6 9 3 11 3 0 0 3 0 2 2 1 2 3 1 0 0 d d

d d d d 0 0 0 0 0 0 d

d d d

0

0

0

Mean, 0.7 mm Mean, 0.7 mm KT-1000 (maximum) <3 mm, 66.6% <3 mm, 72.2% KT-2000 (134 N) Mean, 2.4 mm; <3 Mean, 2.3 mm; <3 Mean, 2.7 mm; <3 Mean, 2.8 mm; <3 KT-2000 (not specified) Mean, 3.4 mm; <3 Mean, 2.0 mm; <3 KT-2000 (134 N) Mean, 2.8 mm; <3 Mean, 2.7 mm; <3 KT-2000 (30 lb) Mean, 2.6 mm; <3 Mean, 1.8 mm; <3 KT-1000 (not specified) Mean, 1.4 mm KT-1000 (not specified) Mean, 2.4 mm; <3 KT-1000 (maximum) Mean, 2.4 mm KT-1000 (not specified) Mean, 1.1 mm; <2 Mean, 0.8 mm; <2 Rolimeter (not specified) Mean, 1.8 mm

mm, mm, mm, mm, mm, mm, mm, mm, mm, mm,

79% 82% 75% 66% 79% 41% 57% 67% 68% 77%

mm, 68% mm, 77% mm, 76%

BPTB, boneepatellar tendonebone; DB, double bundle; QT, quadriceps tendon; QTB, quadriceps tendonebone.

the unconditioned patellar ligaments were significantly larger than those of the unconditioned quadriceps tendons. Strain at failure was 14.4%  3.3% for preconditioned patellar ligaments and 11.2%  2.2% for preconditioned quadriceps tendons (P ¼ .0428). Preconditioned patellar ligaments exhibited a significantly higher elastic modulus than preconditioned quadriceps tendons. Given these findings, the authors concluded that the QTB construct represented a versatile alternative graft choice in ACL reconstruction. In an experimental laboratory study, Adams et al.33 compared the extension strength deficit after removal of 10-mm-wide central free tendon grafts from the quadriceps and patellar tendons. The tensile strength of the quadriceps tendon was reduced by approximately one-third after harvesting a partial-thickness 10mm-wide central free tendon graft. Interestingly, the post-harvest extension strength of the quadriceps tendon was higher than that of the intact patellar tendon. The authors concluded that harvesting the central quadriceps tendon leaves a stronger extensor mechanism than after harvest of a patellar tendon graft, which may help to explain the clinical findings discussed later. Recently, Sasaki et al.34 published a cadaveric study quantitatively evaluating knee biomechanics after quadriceps tendon versus quadrupled hamstring ACL reconstruction. Each knee was tested in the ACL-intact, ACL-deficient, and ACL-reconstructed states. After

reconstruction, both grafts restored anterior tibial translation to within 2.5 mm of the intact ACL, and there were no significant differences regarding rotatory instability compared with the native ACL. No statistical differences were seen between quadriceps tendon and quadrupled hamstring in any testing condition. It should be noted that in the past 10 years, there has been significant improvement in the ability to secure soft tissue for biomechanical testing, leading to more accurate results. We have recently completed biomechanical testing comparing the cross-sectional area, ultimate load, stiffness, and Young’s modulus of elasticity between quadriceps tendon and patellar tendon harvests.35 When comparing 10-mm strips of quadriceps tendon with patellar tendon, our results showed that the quadriceps tendon had a higher cross-sectional area (91.2 mm2 v 484 mm2) and higher ultimate load (2,185.9 N v 1,622.9 N). The quadriceps tendon was stiffer than the patellar tendon (466.2 N/mm v 287.3 N/mm); both of these values were significantly higher than the native ACL stiffness.

Historical Perspective The quadriceps tendon autograft has been revisited in the literature approximately every 5 to 10 years since its introduction in the late 1970s. Marshall et al.32 initially described the use of the quadriceps tendon for ACL reconstruction in 1979, although as discussed earlier, this substitution graft was different from that used in more

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H. S. SLONE ET AL.

Table 3. Functional Outcomes IKDC

Graft QTB QTB

Overall Score (Mean) 86.1 d

QTB BPTB QTB (pin) QTB (screw) QTB

d d d d d

11% 66% 23% 11% No difference between groups

72% 31% 60% 72%

Kohl55 Lee56

BPTB QTB BPTB QHS Allograft DB QTB BPTB QTB BPTB QTB DB QTB QT QTB

d 87.0 87.9 87.3 85.1 d d d d d d d d

38% 43% 45% 36% d d 38% 37% 39.3% 48.4% 0% 88%

44% 41% 37% 41% d d 48% 47% 46.4% 41.9% 87%

Lee57

QTB

d

d

Lund50

QTB BPTB QT

84 70 d

d d 23.6%

Study Akoto51 Chen52 Gorschewsky46 Gorschewsky53 Han47

Kim45

Kim49 Kim48 Kim54

Schulz58

Normal 53.3% 79%

Nearly Normal 43.3% 12%

Abnormal 3.3% 6%

Severely Abnormal 0% 3%

17% 3% 14% 17%

0% 0% 3% 0%

Lysholm Score (Mean) d 93.0 94.0 95.0 89.0 94.0 70.7

15% 14% 15% 17% d d 14% 15% 14.3% 9.7% 13% d

3% 2% 3% 6% d d 0% 0% 0% 0% 0% d

71.2 88.1 89.1 88.2 86.2 91.1 89.4 90.1 92.4 91.8 94.5 94.0 90

d

d

d

93.0

d d 41.8%

d d 30.9%

d d 3.6%

d d 89.0

Cybex Testing (Knee Extension) 91.7% of contralateral side at peak torque

No difference between groups

85.1% (60 /s) and 91.2% (180 /s) of contralateral side 84.7% of contralateral side

BPTB, boneepatellar tendonebone; DB, double bundle; IKDC, International Knee Documentation Committee; QT, quadriceps tendon; QTB, quadriceps tendonebone.

modern techniques. Five years later, Blauth36 reported his technique for harvesting the graft with a patellar bone block. Similar to biomechanical data, the initial clinical results when using the quadriceps tendon as a replacement graft for the ACL were poor. In the late 1990s, Fulkerson and Langeland,37,38 Stäubli,28 and Chen et al.39 reported favorable results with the use of the centralthird quadriceps with a patellar bone block for ACL reconstruction. Theut et al.40 described the use of a central quadriceps free tendon graft in 2003, citing multiple advantages of the free tendon technique. In 1984 Stanish et al.41 reported a 20% incidence of postoperative pivot shift with the use of the quadriceps tendon substitution graft. Howe et al.42 reported improved results with a similar graft, with 90% of patients having stable knees on clinical examination and 93% having mild to no functional deficits. Although clinical results seemed to improve, Yasuda et al.43 reported prolonged (3- to 7-year follow-up) weakness of knee extension strength after graft harvest, especially in women. With disappointing clinical and biomechanical results, the quadriceps tendon graft was largely abandoned.

Renewed interest in the quadriceps tendon autograft for ACL reconstruction began in the late 1990s when Stäubli28 published his series using the central-third quadriceps tendon with a patellar bone block. In 2003 Theut et al.40 described harvesting the tendon without a bone block (central quadriceps free tendon), thus eliminating the risk of patellar fracture during harvest and hoping to reduce the morbidity of graft harvest. They also cited a reduced operative time, easier postoperative rehabilitation, and less risk of anterior knee pain using a free graft technique. Results using this free graft were reported in 2007,13 and the authors showed good to excellent outcomes at more than 2 years’ follow-up (mean, 66 months). Decreased donor-site morbidity and an absence of anterior knee pain were reported, suggesting that the central quadriceps free tendon graft may be the least morbid of all currently used autografts for ACL reconstruction.

Systematic Review We performed a systematic review of all clinical studies regarding quadriceps tendon ACL reconstruction. The primary search was performed using PubMed.

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QUADRICEPS TENDON AUTOGRAFT Table 4. Overall Patient Satisfaction Study Gorschewsky46

Graft QTB

BPTB

Gorschewsky23

QTB (pin)

QTB (screw)

Han47 Kim48

QTB BPTB QTB

BPTB

Rating Very good, 44% Good, 52% Satisfactory, 3% Poor, 1% Very good, 62% Good, 33% Satisfactory, 2% Poor, 3% Very good, 51% Good, 33% Satisfactory, 12% Acceptable, 2% Unacceptable, 0% Very good, 44% Good, 52% Satisfactory, 3% Acceptable, 1% Unacceptable, 0% No difference between groups Fully satisfied, 47.6% Satisfied, 42.9% Unsatisfied, 9.5% Very unsatisfied, 0% Fully satisfied, 51.9% Satisfied, 40.7% Unsatisfied, 7.4% Very unsatisfied, 0%

BPTB, boneepatellar tendonebone; QTB, quadriceps tendonebone.

Articles containing “anterior cruciate ligament” and “quadriceps tendon” in either the title or abstract were identified. In addition, searches of the Cochrane Database and Google Scholar were performed, and the references of identified articles were reviewed for additional studies. Included in this systematic review are Level I, Level II, and Level III Evidence studies evaluating outcomes of arthroscopic primary ACL reconstruction using autologous quadriceps tendon published in peer-reviewed journals. The exclusion criteria included the following: studies with less than 12 months’ follow-up, early results of later published

follow-up studies, abstract publications, articles not available in the English language, studies of multiligamentous knee reconstruction, studies of open reconstruction, and Level IV and Level V studies. The level of evidence was determined first by the declaration of the level by the publishing journal. If this information was not declared, the level of evidence was determined according to the criteria of the Center for Evidence-Based Medicine.44 A total of 132 studies were identified through PubMed. Seven studies were identified through review of references from previously published articles. Additional searches of the Cochrane Database and Google Scholar were performed. No studies were identified through the Cochrane Database. The Google Scholar search yielded 72 studies. This search was repeated at a later date to ensure that no studies were missed. A total of 161 studies were evaluated after duplicates from each search were excluded. A total of 14 studies met our inclusion and exclusion criteria and were included in this systematic review (Fig 5). A significant amount of heterogeneity was found across studies regarding study design, surgical technique, and outcome measures used. The outcome measures most commonly used across studies are summarized in this review. Descriptive study characteristics are shown in Table 1. This review is composed of study designs including prospective, randomized controlled trials; prospective cohort studies; retrospective comparative studies; and retrospective cohort studies. A total of 1,756 ACL reconstructions were included in this review, including 1,154 using quadriceps tendon autograft. Results, when available, were divided into stability outcomes, functional outcomes, overall patient satisfaction, range of motion, morbidity, and complications. Stability In general, stability after ACL reconstruction with quadriceps tendon autograft yields results comparable

Table 5. Range of Motion Study Akoto51 Chen52 Gorschewsky46 Han47 Kim48 Kim54 Lee56 Lee57 Schulz58

Graft QTB QTB QTB BPTB QTB BPTB QTB BPTB QTB DB QTB QTB QTB QT

Average ROM d d No difference between groups

Flexion Loss 1 patient (mild) 3% with >5 No difference between groups

d d d d d d 137.5 139.5 d

No difference between groups 4.8% with >5 11.1% with >5 3.6% with >5 3.2% with >5 2.1% with 5 d 3.1 mean loss

Extension Loss 1 patient (mild) 3% with >5 4% with >5 12% with >5 No difference between groups 9.5% with 7.4% with 3.6% with 6.5% with 2.5% with 0.6 mean 1.2 mean

>5 >5 >5 >5 3 loss loss

BPTB, boneepatellar tendonebone; DB, double bundle; QT, quadriceps tendon; QTB, quadriceps tendonebone; ROM, range of motion.

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H. S. SLONE ET AL.

Table 6. Morbidity and Complications Study Akoto51 Chen52 Gorschewsky46 Gorschewsky53 Han47

Graft QTB QTB QTB BPTB QTB (pin) QTB (screw) QTB

BPTB

Kim49

DB QTB

Kim48

BPTB QTB BPTB

Kim54

QTB

Kohl55 Lee56

DB QTB QT QTB

Lund50

QTB

BPTB

Schulz58

QT

Morbidity d 9% with donor-site morbidity 15% with donor-site morbidity 51% with donor-site morbidity 24% with donor-site morbidity 16% with donor-site morbidity 8.3% with moderate to severe donor-site morbidity 5.5% with kneeling pain 39% with moderate to severe donor-site morbidity 35% with kneeling pain d 18.8% with anterior knee pain 19.0% with kneeling pain 9% with mild discomfort at graft site 48.1% with kneeling pain 44% with anterior tenderness, numbness, and/or irritation d

d d 9% with moderate to severe anterior knee pain with work/sport 9% with limited stair climbing due to anterior knee pain 9% with moderate to severe anterior knee pain with prolonged sitting 7% with moderate to severe pain with activities of daily living 10% with moderate to severe pain with kneeling 5% unable to knee walk 0% of patients with harvest-site pain 48% of patients with sensory loss 39-cm2 average area of sensory loss 34% unable to knee walk 30% of patients with harvest-site pain 73% of patients with sensory loss 62-cm2 average area of sensory loss 1.4% with numbness lateral to harvest site 11% with kneeling pain

Complication None 2 patients with stitch abscess 1 patient required tibial screw removal d d 2% rerupture rate 2% rerupture rate 1 patient with 40 loss of flexion 1 patient with nondisplaced patellar fracture 1 patient with postoperative infection

1 1 1 1 1

patient with femoral tunnel cortical breach patient required supplemental tibial fixation postoperative soft-tissue infection traumatic failure atraumatic failure

1 patient with short bone plugdno adverse outcome 1 patient with atraumatic failure 1 patient required supplemental tibial fixation No reruptures 2.9% revision rate: 4 traumatic and 3 atraumatic 1 patellar fracture due to fall 5 mo postoperatively 2 intraoperative patellar fractures treated with ORIF 2 patients required arthrolysis due to postoperative stiffness

1 patient with superficial infection 1 patient required tibial screw removal 1 patient with inflamed medial plica treated with plica excision 1 patient with traumatic failure 1 patient required tibial screw removal 1 patient with medial meniscal tear treated with partial meniscectomy No reruptures 5.5% reoperation rate (2 partial medial meniscectomies and 1 MUA)

BPTB, boneepatellar tendonebone; DB, double bundle; MUA, manipulation under anesthesia; ORIF, open reductioneinternal fixation; QT, quadriceps tendon; QTB, quadriceps tendonebone.

with commonly used alternative autografts (Table 2). Most comparative studies showed no difference between autografts regarding arthrometric testing, Lachman testing, or pivot-shift testing.45-48 Kim et al.49 showed better arthrometric testing findings for double-bundle quadriceps tendon autograft compared with singlebundle bone-tendon-bone (BTB) autograft in patients with generalized ligamentous laxity; however, no differences were seen on Lachman or pivot-shift testing. In the single prospective, randomized controlled trial

included in this review, Lund et al.50 found no significant difference in arthrometric testing between QTB and BTB autografts; however, patients with QTB autografts were much less likely (14%) to have a positive pivot shift compared with BTB patients (38%) (P ¼ .03). Functional Outcomes Primary functional outcome measures included the International Knee Documentation Committee (IKDC) score, Lysholm score, and Cybex testing (Lumex,

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Gorschewsky et al.46 found that patients undergoing ACL reconstruction with BTB autograft were more satisfied with the knee than patients receiving QTB (P ¼ .04). Han et al.47 and Kim et al.48 found no differences regarding patient satisfaction between the BTB and QTB groups. Range of Motion Nine studies reported range-of-motion outcomes after quadriceps tendon or QTB ACL reconstruction, including 3 studies comparing QTB with BTB (Table 5). No differences were seen regarding range of motion when the QTB and BTB groups were compared.46-48

Fig 6. Postoperative photograph of a distal thigh cosmetic deformity due to retraction of the rectus femoris muscle after quadriceps tendon harvest. This defect can be seen when the tendon is harvested proximally well into the rectus femoris muscle. No functional deficit was noted during postoperative follow-up.

Ronkonkoma, NY) (Table 3). Functional outcomes after ACL reconstruction with QTB or quadriceps tendon autograft showed results comparable with other autograft choices, with most knees classified as normal or nearly normal on IKDC assessment. Gorschewsky et al.46 found that patients receiving BTB autografts were more likely to have a normal or nearly normal score compared with QTB autograft patients (P  .001). In contrast, Han et al.,47 Kim et al.,45,48 and Lund et al.50 found no difference in IKDC scores between QTB and BTB autografts. Of the 14 studies included, 12 reported Lysholm scores for quadriceps tendon autografts, which ranged from 70.7 to 94.5. Similarly, 5 of the 14 studies included evaluated Lysholm scores for BTB autografts, which ranged from 71.2 to 95.0. No differences in Lysholm score were found between QTB and BTB autografts.45,46,48 The only prospective, randomized controlled study comparing BTB and QTB used the Knee Injury and Osteoarthritis Outcome Score and found no difference between groups.50 Four studies evaluated postoperative quadriceps strength by Cybex testing. Three noncomparative studies reported quadriceps strength as 84.7% to 94.7% of the contralateral side. Only 1 comparative study reported postoperative quadriceps strength after quadriceps and BTB ACL reconstruction, and no statistical difference was found between groups.47 Patient Satisfaction Four studies reported overall patient satisfaction, including 3 studies comparing BTB with QTB (Table 4).

Complications and Morbidity In general, quadriceps tendon autografts had lower morbidity and similar complication rates when compared with BTB autografts (Table 6). Twelve studies reported associated morbidities or complications (or both). Han et al.47 reported 1 intraoperative patellar fracture and Lee and colleagues25 reported 2 such fractures after QTB harvest. Five studies compared donor-site morbidity between QTB and BTB. In each of the 5 comparative studies, less donor-site morbidity was seen in the QTB group.46-50

Discussion Morbidities associated with boneepatellar tendone bone autograft have been well documented and include postoperative anterior knee pain, difficulty kneeling, and possible patellar fracture and patellar tendon rupture.59 Hamstring autograft concerns include damage to neurovascular structures, postoperative hematoma formation, tendon truncation during harvest, reduced initial fixation strength, numbness over the donor site, loss of terminal flexion strength, and increased objective laxity in female patients.60,61 Even with flawless harvesting technique, the size and length of the hamstring tendons are highly variable, although techniques have been developed to create 5- and 6-strand constructs if the length of the graft is greater than 25 cm. Allografts are often used for ACL reconstruction because of the lack of donor-site morbidity, but they are not always available. Allografts are also associated with increased cost, a slower incorporation time, risk of disease transmission, and a higher failure rate, especially in young active patients.62 Although the quadriceps tendon has less donor-site morbidity than BTB autografts as shown in this review, complications after quadriceps graft harvest still exist. In addition, we have observed some complications not identified in this review. If the quadriceps muscle is violated to a significant degree, especially laterally where the perforating vessels exist, extensive bleeding may occur after release of the tourniquet, leading to possible hematoma or compartment syndrome if not recognized.

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Similarly, if a full-thickness harvest is performed, intraarticular bleeding can extravasate through the defect and form a hematoma anterior to the remaining quadriceps tendon. One can minimize this risk by centralizing the graft harvest within the quadriceps tendon, performing partial-thickness harvesting, and limiting the proximal tendon harvest to the myotendinous junction of the rectus femoris (6 to 8 cm proximal to the tendon insertion on the patella). Although uncommon, retraction of the rectus femoris muscle may occur after full- or partial-thickness graft harvest. This seems to again correlate with tendon harvesting that spans the myotendinous junction of the rectus femoris. Although distal thigh cosmesis may be of concern, the deformity does not appear to have functional consequences (Fig 6). The quadriceps autograft remains the least studied and least used among orthopaedists today. Many orthopaedists do not even include the quadriceps tendon as a possible graft alternative when discussing graft options with surgical patients. With or without a bone block, it is a versatile and very suitable graft choice for ACL reconstruction with distinct advantages over other autograft choices. The clinical results of this systematic review support its use as an alternative graft choice for ACL reconstruction. To our knowledge, only 1 other systematic review has been performed evaluating quadriceps tendon in ACL reconstruction. In their review, which consisted of Level III and IV Evidence, Mulford et al.63 concluded that quadriceps tendon ACL reconstructions yield good results with minimal donor-site morbidity. Several relevant studies have been published since 2011 and were included in this review. Despite a better understanding of the quadriceps tendon anatomy and usefulness as a viable ACL graft alternative, several questions remain that will require future study. Harvesting technique can be challenging despite several well-described techniques.12,30 It is likely that many surgeons are unfamiliar with the insertional quadriceps anatomy and may not feel comfortable harvesting the tendon without specific instrumentation. In addition, it is unknown whether a partial- or fullthickness graft should be harvested. A full-thickness graft violates the suprapatellar pouch, which may lead to fluid extravasation during the remainder of the arthroscopic procedure if the defect is not closed properly. No authors have reported on whether closure of a partial- or full-thickness defect should be performed. It is also unknown whether a partial- versus full-thickness graft causes more pain and affects rehabilitation. Strengths of this study include the comprehensive review of anatomic, histologic, biomechanical, and clinical outcomes. No previous studies identified through our search systematically reviewed clinical outcomes of quadriceps ACL reconstruction in Level II-III studies. No Level I studies were identified through our search.

Limitations As with any systematic review, methodologic limitations exist regarding study design. This systematic review cannot compensate for study design deficiencies or statistical or methodologic shortcomings of the individual studies included. In addition, heterogeneity of individual studies made it difficult to pool data for comparative analysis. Only 6 studies compared quadriceps tendon with BTB autografts, and only 1 study compared quadriceps tendon with hamstring autografts and allografts. Moreover, it is possible that our systematic search did not identify all relevant studies that should have been included in this review.

Conclusions The quadriceps tendon autograft for ACL reconstruction is supported by current orthopaedic literature. It is a safe, reproducible, and versatile graft that should be considered in future studies of ACL reconstruction.

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