Role of Quadriceps Tendon Autograft in Primary and Revision Anterior Cruciate Ligament Reconstruction

Abstract

• »The quadriceps tendon (QT) autograft is becoming increasingly popular in both primary and revision anterior cruciate ligament reconstruction (ACLR).
• »The biomechanical properties of the QT are similar to those of the native ACL, the hamstring tendon (HT), and bone-patellar tendon-bone (BTB) autografts.
• »QT autograft allows surgeons to be flexible with their graft size and reconstruction technique.
• »The QT autograft performs in a similar fashion to the BTB and HT autografts, with excellent patient-reported outcomes, consistent postoperative knee stability, and low rates of postoperative complications including graft failure and donor site morbidity.
• »There are emerging data that the QT autograft is a viable option in revision ACLR.

Anterior cruciate ligament reconstruction (ACLR) is one of the most commonly performed procedures among orthopaedic surgeons, as an estimated 250,000 cases are annually reported in the United States^1-3. The unique anatomy of the ACL allows for the ligament to play an important role in knee stability, providing both primary resistance to anterior tibial translation and rotational stability^4-8. When the ACL is torn, this stability is lost and the knee becomes prone to further injury. Poor longitudinal results from nonoperative management, including progression of arthritis and meniscal damage, have lead researchers and surgeons to search for operative solutions for the unstable ACL-deficient knee^8-10. Originally, surgical repair of the ACL was attempted, both primarily and with various supplemental experimental scaffolds; however, the poor healing environment surrounding the ACL led to poor clinical outcomes¹¹. Although there have been several recent advances in primary ACL repair with the assistance of biologically active scaffolds, ACLR remains the standard of care for the management of ACL ruptures worldwide^12-14. ACLR is performed with the goals of reproducing the native biomechanics of the affected knee and ensuring adequate fixation, healing, and integration of the graft, all while minimizing morbidity related to the autograft donor site^1,2.

Three sources of autograft are commonly used in ACLR: hamstring tendon (HT), bone-patellar tendon-bone (BTB), and quadriceps tendon (QT). Although the HT autograft remains the most commonly used autograft for ACLR worldwide, the BTB autograft has become the standard of care across the United States^1,15. The QT autograft, although far less commonly used than HT and BTB autografts, is becoming increasingly popular in both primary and revision ACLR because of several reasons, including length and thickness versatility, variability in fixation methods, and a growing body of evidence demonstrating excellent patient outcomes¹⁶.

The use of QT autograft was first described in 1979 by Marshall et al., using a technique that functioned as a substitution graft harvest, harvesting approximately 13 cm of the extensor mechanism including the QT, patellar tendon, and prepatellar retinaculum¹⁷. The clinical outcomes using this technique were poor because 20% of patients demonstrated positive pivot-shift tests, and rates of postoperative knee laxity and extensor mechanism weakness were exceedingly high^18,19. The technique was further refined, with Fulkerson publishing a technique for all-soft tissue QT autograft harvest in the early 2000s²⁰. Further refinements in the graft harvest technique have produced a large and versatile graft, with comparable clinical outcomes and biomechanical characteristics to both the BTB and HT autografts. The goal of this article is to review the anatomy of the QT autograft; evaluate its biomechanical properties; review the clinical data comparing the QT, HT, and BTB autografts; and review the literature evaluating the effectiveness of the QT autograft in revision ACLR.

Anatomy of the QT

The length, thickness, and unique orientation of the tendon fibers of the QT create an extremely versatile graft for ACLR. The QT extends from the myotendinous junction of the rectus femoris proximally to the superior pole of the patella distally, with anatomic studies measuring an average length of 7 to 8.5 cm^1,21,22. Furthermore, a cadaveric study by Lippe demonstrated the “twin peaks” configuration of the tendon, demonstrating varying lengths of available graft within the tendon itself (Fig. 1). At its widest point, which is approximately 2 to 3 cm proximal to the superior pole of the patella, the QT measures about 2.5 to 3 cm^21,23. The QT is uniquely thick, with a measured thickness of approximately 18 mm in males and 16 mm in females, compared with an average thickness of 6 mm for patellar tendon grafts when measured in cadaveric studies^21-23. Furthermore, the unique orientation of the fibers of the QT may be advantageous of ACLR because there is a natural layer of fatty tissue between the rectus femoris and vastus intermedius portions of the tendon, which create a natural plane that can be exploited when performing double-bundle ACLR^23-25 (Fig. 2). The size and thickness of the QT graft creates a more robust graft, with studies showing an intra-articular volume that was 87.5% greater than the harvested patellar tendon^1,24. It should also be noted that a recent biomechanical study evaluating the QT found that its cross-sectional area is approximately 2 times more than that of the patellar tendon with minimal variability, which is important as a predictable graft with consistent anatomical parameters is paramount in successful graft harvest^1,26. The QT allows surgeons to be flexible with their graft size and reconstruction technique because the unique anatomy of the QT allows for significant variation in graft size and thickness, as well as the options of performing single-bundle or double-bundle ACLR with or without the use of a bone plug.

Fig. 1.

Quadriceps tendon in a right knee showing the dual peaks (arrows) at the musculotendinous junction. Reproduced, with permission, from: Lippe J, Armstrong A, Fulkerson JP. Anatomic guidelines for harvesting a quadriceps free tendon autograft for anterior cruciate ligament reconstruction. Arthroscopy. 2012;28(7):980-4.

Fig. 2.

Bulky quadriceps tendon graft. The rectus femoris and vastus intermedius layers are separated by a fat stripe (asterisk). Reproduced, with permission, from: Lippe J, Armstrong A, Fulkerson JP. Anatomic guidelines for harvesting a quadriceps free tendon autograft for anterior cruciate ligament reconstruction. Arthroscopy. 2012;28(7):980-4.

Biomechanical Properties

The biomechanical properties of the QT autograft are similar to those of the native ACL, and compare similarly with the HT and BTB autografts. Woo et al. evaluated the ultimate load to failure of the native ACL and found this value to be 2,106 N²⁷. However, in the older populations, this value changed, averaging 1,503 N in patients aged 40 to 50 and 658 N for those aged 69 to 97 years²⁷. West and Harner first reported an ultimate load to failure of 2,352 N for the QT, and similar results have been reported in other studies². In a more recent study, Shani et al. evaluated the biomechanics of QT and BTB autografts and found an ultimate load to failure of 2,185 N and stiffness of 466 N/mm for the QT autograft, compared with an ultimate load to failure and stiffness of 1,580 N and 278 N/mm for the BTB autograft, respectively²⁶ (Table I). Although there has been some variability in the reported biomechanical properties of the BTB, QT, and HT autografts, it should be noted that that the HT autograft has consistently demonstrated the highest load to failure when compared to QT and BTB autografts, with values reaching as high as 4,000 N across several studies^1,27,28.

TABLE I.

Biomechanical Properties of ACL Autografts^*

Graft (Tissue Type)	Ultimate Load to Failure (N)	Stiffness (N/mm)	Cross-Sectional Area
Native ACL	2,160	242	44
QT	2,186	466	62
BTB	1,581	278	35
HT	4,090	776	53

^*ACL = anterior cruciate ligament, BTB = bone-patellar tendon-bone, HT = hamstring tendon, and QT = quadriceps tendon.

Reproduced, with permission, from: Mehran N, Damodar D, Shu Yang J. Quadriceps tendon autograft in anterior cruciate ligament reconstruction. J Am Acad Orthop Surg. 2020;28(2):45-52.

When considering the biomechanical properties of the QT autograft compared to HT and BTB, it should be noted that the fixation technique used for ACLR may alter the biomechanical properties of the autograft being used. For example, when using the QT autograft, the graft can be harvested with a patellar bone plug or can be harvest in an “all-soft tissue” fashion. This alters the biomechanics of the harvested graft as studies have shown that fixation strength changes based on the fixation technique. For example, studies have consistently shown that grafts secured with interference screw fixation, as typically performed with grafts involving bone plugs (BTB and QT if taken with a patellar bone plug), demonstrate improved graft incorporation and joint stability because of the point of fixation closer to the tunnel aperture^29,30. If the QT is taken without a patellar bone plug, fixation strategies should be considered. With many soft tissue grafts, suspension fixation with an adjustable-length cortical button is often chosen, and multiple biomechanical studies have shown that this fixation technique is able to provide adequate stability to facilitate effective healing of the graft, including with accelerated rehabilitation protocols^31,32. However, concern for increased graft motion leading to tunnel widening and compromised graft integration and healing has led many surgeons to avoid suspensory fixation with HT or all-soft tissue QT autografts, favoring the interference screw fixation of BTB^29,30.

Within the context of suspensory fixation, techniques should also be considered. In a study performed by Born et al., the strength of 2 adjustable femoral cortical suspensory fixation devices was compared in 6 matched pairs, and no significant differences were found between the 2 groups' laxity measures after cycling at any flexion angle³³. In a study performed by Johnson et al., the biomechanical properties of fixed and adjustable-loop cortical suspension devices were compared about femoral fixation and early cyclic loading of the knee as seen in early rehabilitation protocols³². This study found that while there were no significant differences in cyclic displacement between the adjustable-loop devices, the fixed-loop devices demonstrated significantly less cyclic displacement when compared to all adjustable-loop devices (p < 0.05), suggesting that early rehabilitation protocols should be carefully approached when performing ACLR with adjustable-loop cortical suspension devices³² (Table II).

TABLE II.

Biomechanical Properties of Femoral Cortical Suspension Devices^*†

	Preconditioning Displacement (mm)	Retensioned	Cumulative Peak Cyclic Displacement (mm)	Stiffness (N/mm)	Ultimate Strength (N)
ENDOBUTTON	0.06 ± 0.01	NA	1.05 ± 0.05	927 ± 15	1,530 ± 180
RIGIDLOOP	0.05 ± 0.03	NA	1.09 ± 0.16	1,628 ± 45	1,976 ± 229
TightRope	0.03 ± 0.02	No	2.20 ± 0.62	1,354 ± 35	784 ± 45
TightRope	0.04 ± 0.04	Yes	1.81 ± 0.51	1,353 ± 60	1,020 ± 421
ToggleLoc	0.67 ± 1.49	No	3.69 ± 2.39	1,480 ± 103	1,995 ± 217
ToggleLoc	0.24 ± 0.12	Yes	3.22 ± 1.41	1,538 ± 57	2,231 ± 511
XO Button	0.16 ± 0.05	NA	1.65 ± 0.43	1,747 ± 58	2,218 ± 114

^*NA = not applicable.

^†All data reported as mean ± SD.

Reproduced, with permission, from: Johnson JS, Smith SD, LaPrade CM, Turnbull TL, LaPrade RF, Wijdicks CA. A biomechanical comparison of femoral cortical suspension devices for soft tissue anterior cruciate ligament reconstruction under high loads. Am J Sports Med. 2015;43(1):154-60.

Although the anatomic versatility and experimental biomechanical properties of the QT autograft are promising, harvest techniques and fixation strategies should be carefully considered. The QT autograft with a bone block not only is believed to provide the most reliable fixation, with one point of bone-to-bone contact, but also puts the patient at risk of patella fracture and potentially increased knee pain³⁴. The bone-QT graft involves screw fixation of the bone plug into the tibia, although press-fit fixation has also been successfully used³⁵. The all-soft tissue QT graft, while also supported by several biomechanical studies, requires suspensory fixation that underperforms with in vitro cyclic loading as compared with bone block fixation. However, in one of the very few head-to-head comparison studies, Setliff et al. found no differences in failure rates or subjective outcome scores between BB and all-soft tissue QT when examining 195 patients (147 soft tissue and 48 BB) retrospectively. At this point, both techniques have yielded excellent results. The decision on graft type should be based on an informed discusssion with the patient regarding risks and benefits as well as surgeon experience.

Graft Harvest and Preparation

There are several QT autograft harvest techniques, including minimally invasive and open methods. Typically, a 2- to 5-cm incision is made on the midline superior to the patella. The skin and subcutaneous tissue are dissected sharply to reveal the paratenon and underlying tendon. The desired width and length of the graft is measured and drawn out (typically approximately 10 by 80 mm) and the tendon is harvested sharply in line with the fibers of the tendon. The graft may be made full or partial thickness without any clearly superior outcomes with either technique³⁶. If a bone block is harvested, an oscillating saw followed by an osteotome is sequentially used to harvest a partial-thickness trapezoidal-shaped bone plug³⁷. A series of 57 patients by Fu et al. revealed a patella fracture rate of 3.5% intraoperatively and 8.8% at 2 years while suggesting that potential risk factors for fracture were as follows: an eccentric harvest site, >50% of anteroposterior thickness, >50% of mediolateral width, failure of bone graft to incorporate, and the creation of a stress riser at the corner of the harvest site³⁴. After harvest, the tendon can be prepared per surgeon preference and bone graft can be applied to the patellar defect.

Once the graft has been harvested, preparation on the back table is very similar to that of a patellar tendon graft. The tendon is laid out and trimmed to the surgeon's preferred width. The bone block is drilled and sutures are passed. The tendonous side is prepared with nonabsorbable suture in any preferred fashion (i.e., krackow or whipstitch). If suspensory fixation is used, certain systems may have proprietary suturing techniques to correspond with their devices; otherwise, any preferred suture configuration can be performed and the suture limbs threaded into a deployable button-type device. From start to finish, the authors find that when compared to BTB patella, harvesting a QT graft with bone block is similar in both time and difficulty while harvesting an all-soft tissue QT graft is less onerous.

Clinical Outcomes

There are several methods to evaluate the effectiveness of ACLR in the clinical setting, including patient-reported outcome measures (PROMs), strength of the surgical limb in the postoperative period, postoperative knee stability and range of motion, and complications such as graft rupture rate and donor site morbidity. Many of these outcomes have been extensively studied in recent years, and comparative data are becoming more available as the QT autograft has become increasingly used in clinical practice. As researchers attempt to synthesize these data, it is important to note the difficulty of performing a systematic review on this topic; as the QT autograft can be harvested with or without a bone plug, comparative graft studies are heterogeneous and may preclude an effective systematic review.

PROMs are a useful method of evaluating the patient's subjective performance after ACLR and includes several different scoring systems, including the International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS), and Lysholm systems. There are several studies that demonstrate no differences in PROMs when comparing QT, HT, and BTB autografts^38-44. A recent retrospective cohort study performed by Runer et al. evaluated PROMs in 875 patients receiving ACLR with QT or HT autograft and found no difference in Lysholm scores, Tegner activity scores, and Visual Analog Scale pain scale; however, they did find that the odds of revision surgery were 2.7 times greater in the HT group compared with the QT group⁴⁵. Furthermore, a prospective randomized control study performed by Lund et al. evaluated 51 patients undergoing ACLR with QT or BTB autograft and found no statistical difference in subjective IKDC and KOOS scores between the 2 groups⁴². A recent retrospective cohort study performed by Cavaignac et al. compared 86 patients undergoing ACLR with QT and HT autografts and found significantly better KOOS and Lysholm scores in the QT group at minimum 3-year follow-up⁴¹ (Table III). One recent study conducted by Gorschewsky et al., however, compared 260 patients undergoing ACLR with QT (124 patients) or BTB (136 patients) and found that BTB patients were more likely to have a normal IKDC than QT patients, despite finding no differences in Lysholm and Noyes scores at minimum 2-year follow-up⁴⁰.

TABLE III.

Comparison of Postoperative Functional Scores^*†

	All (n = 38)	QT (n = 39)	HT (n = 39)	p Value
Lysholm	86.4 ± 6	89 ± 6.9	83.1 ± 5.3	<0.05
KOOS
Pain	89 ± 6.9	90 ± 6.8	86 ± 7.2	0.23
Symptoms	85 ± 10.7	90 ± 11.2	81 ± 10.3	0.017
ADL	93 ± 5.2	95 ± 5.3	90 ± 4.9	0.08
Sport	73 ± 14	82 ± 11.3	67 ± 12.4	0.003
QoL	79 ± 12.3	78 ± 14.7	79 ± 10.3	0.22
Tegner
Last follow-up	5.7 ± 1.5	5.9 ± 1.4	5.6 ± 2	0.42
Difference in preoperative	1 ± 1.4	1 ± 1.05	1.2 ± 1.8	0.24
IKDC subjective	83 ± 15	84 ± 13	80 ± 17	0.2

^*ADL = activities of daily life, HT = hamstring tendon, IKDC = International Knee Documentation Committee, KOOS = Knee Injury and Osteoarthritis Outcome Score, NA = not applicable, QoL = quality of life, and QT = quadriceps tendon.

^†All data reported as mean ± SD.

Reproduced, with permission, from: Cavaignac E, Coulin B, Tscholl P, Nik Mohd Fatmy N, Duthon V, Menetrey J. Is quadriceps tendon autograft a better choice than hamstring autograft for anterior cruciate ligament reconstruction? A comparative study with a mean follow-up of 3.6 years. Am J Sports Med. 2017;45(6):1326-32.

Knee instability and poor ROM after ACLR can lead to continued knee pain and poor clinical outcomes in the postoperative period. Review of the most updated literature demonstrates that there are no differences in rates of postoperative knee instability between QT, HT, and BTB autografts^39-42,46. A recent systematic review by Hurley et al. found no differences between QT, HT, and BTB when evaluating pivot shift, Lachman, and KT-1000⁴⁷. Furthermore, the aforementioned prospective randomized study performed by Lund et al. found no difference in KT-1000 values between QT and BTB groups⁴². One retrospective study performed by Cavaignac et al., however, found that patients in the QT group had significantly less laxity based on KT-1000 and a significantly higher rate of negative Lachman examination (90% vs 46%, p < 0.005) when compared to the HT group⁴¹. Finally, a study performed by Fischer et al. found no significant differences in the postoperative range of motion between QT, HT, and BTB⁴⁸.

Strength of the knee in both flexion and extension is an important factor when selecting an autograft in ACLR. Given the importance of the QT in the strength of the extensor mechanism, extension strength in the postoperative period after ACLR with QT autograft has gained interest with multiple recent studies. A systematic review by Johnston et al. evaluated the knee extension and flexion strength as a primary outcome after ACLR with QT autograft when compared to the nonreconstructed contralateral limb and alternative autograft types⁴⁹. The authors found that knee extensor strength did not reach 90% of the contralateral limb even at 24-month follow-up⁴⁹. A retrospective cohort study by Hunnicutt et al. compared quadriceps recovery in patients undergoing ACLR with QT vs BTB autograft and found no difference in knee extensor isokinetic strength, activation, cross-sectional area of the vastus medialis, single-leg hop test, and step length symmetry at 23-month follow-up⁵⁰. Furthermore, Lee et al. compared 96 patients who underwent ACLR with either HT or QT autograft and found better muscle strength recovery in the QT group when compared to the HT group while also finding no difference in extensor muscle recovery between the 2 groups⁴⁶. In addition, Fischer et al. evaluated knee muscle strength in 124 patients undergoing ACLR with either HT or QT and found a significantly higher hamstring/quadriceps isokinetic strength ratio in the QT group compared with the HT group⁴⁸. This is especially important to consider, as Griffin et al. found that hamstring weakness is a risk factor for ACL injury in the setting of normal QT strength, given that the hamstrings are a secondary stabilizer in anterior tibial translation prevention, and speculated that an increased hamstring/quadriceps ratio may be protective against ACL graft rupture^1,51.

Complications after ACLR can lead to revision surgeries and poor clinical outcomes and include graft failure, donor site morbidity, hematoma formation, patella fractures, and donor site cosmetic defects^1,40. Regarding graft failure rates, a recent prospective cohort study by Runer et al. evaluated clinical outcomes and complication rates in 875 patients after ACLR with HT and QT autografts and found a significantly higher rate of ipsilateral graft ruptures in the HT group when compared to the QT group with no difference in functional outcomes at 24-month follow-up⁴⁵. Several recent studies that compared outcomes between QT and BTB found overall complication rates of 2.28% and 3.48% in QT and HT groups, respectively^38-40,42. Furthermore, Cavaignac et al. compared QT and HT autografts in 85 patients and found graft failure rates of 2.22% and 4.44% in QT and HT groups, respectively, with 3.6-year follow-up⁴¹. The available literature does not seem to consistently report a difference in graft rupture rates between QT, HT, and BTB autografts and further studies are necessary to establish any clinically significant differences.

Patella fractures are a known risk of performing ACLR with BTB and QT autografts because of the bone plug included with harvesting the graft. One recent systematic review by Slone et al. found an overall patella fracture rate of 0.03% for QT autografts harvested with the bone plug⁵². Furthermore, a recent prospective study including 51 patients by Lund et al. found a higher rate of patella fractures in BTB when compared to QT^1,42. Although the data evaluating patella fractures after ACLR with QT autograft are less robust, one can minimize the risk of sustaining a patella fracture by avoiding using a bone plug and instead using an all-soft tissue QT autograft.

Donor site morbidity is common after ACLR with autograft harvest, particularly with the use of BTB autograft. In a recent retrospective cohort study, Han et al. evaluated 72 patients who underwent ACLR with BTB or QT autograft and found anterior knee pain rates of 39% and 8.3% for BTB and QT groups, respectively, at minimum 2-year follow-up⁵³. Furthermore, a recent systematic review and meta-analysis of over 600 patients performed by Mouarbes et al. found a significantly decreased rate of anterior knee pain in those undergoing ACLR with QT autograft (p < 0.001) when compared to a BTB autograft and found no difference in knee pain rates when comparing the QT group to the HT group⁵⁴ (Table IV). The aforementioned study by Lund et al. also noted significantly less anterior knee pain after ACLR with QT autograft when compared to a BTB autograft⁴². The location of the QT reduces the risk of iatrogenic nerve damage when compared to the patellar tendon, which places the infrapatellar branch of the saphenous nerve at risk¹.

TABLE IV.

Outcome Measures Analyzed From QT vs. BPTB Autograft Studies^*

	nQT:BPTB	Mean Difference (95% CI) QT-BPTB	Risk Ratio (95% CI) QT:BPTB	p Value
Side-to-side difference, mean	248:311	−0.18 (−0.65 to 0.29)		0.45
Side-to-side difference >3 mm	518:413		0.77 (0.49-1.18)	0.23
Lachman grade 0	390:316		1.02 (0.91-1.14)	0.76
Lachman grade 0 or 1	390:316		1.00 (0.97-1.03)	0.79
Pivot-shift grade 0	416:341		1.04 (0.98-1.1)	0.23
Pivot-shift grade 0 or 1	390:316		1.00 (0.97-1.02)	0.85
Lysholm score, mean	357:459	−0.81 (−1.77 to 0.15)		0.1
Objective IKDC A or B	328:427		0.97 (0.92-1.02)	0.2
Subjective IKDC, mean	168:252	2.08 (−2.38 to 6.55)		0.36
Donor-site pain	439:287		0.25 (0.18-0.36)	<0.0000
Graft failure	439:287		0.72 (0.28-1.84)	0.5

^*BTB = bone-patellar tendon-bone, CI = confidence interval, IKDC = International Knee Documentation Committee, and QT = quadriceps tendon.

Reproduced, with permission, from: Mouarbes D, Menetrey J, Marot V, Courtot L, Berard E, Cavaignac E. Anterior cruciate ligament reconstruction: a systematic review and meta-analysis of outcomes for quadriceps tendon autograft versus bone-patellar tendon-bone and hamstring tendon autografts. Am J Sports Med. 2019;47(14):3531-40.

Revision ACLR

Revision ACLR is a challenging clinical scenario and surgeons often must consider several factors when planning revision surgery: cause of failure (recurrent instability, infection, and stiffness), previous graft used and method of fixation, previous tunnel size and position, and additional pathologies that may be associated with graft failure. In 2022, Winkler et al. reported that the QT autograft is becoming an increasingly popular graft option in revision ACLR over recent years¹⁶. When considering graft selection for revision ACLR, one must consider the previous graft used, quality of available autografts, and the prospect of allograft and autograft fixation. Considering a QT autograft, there is some concern regarding a secondary insult to the extensor mechanism if previous ipsilateral BTB was performed for the index procedure⁵⁰. Overall, there is little literature evaluating the efficacy of QT autograft in revision ACLR; however, studies continue to report promising potential regarding this graft option.

Garofalo et al. retrospectively evaluated 28 patients who underwent ACLR with QT autograft (with bone plug) and found significant improvement in Lysholm scores and significantly reduced tibial translation with KT-1000 testing in the postoperative period, with all patients returning to previous level of activity at the end of their 9-month rehabilitation protocol⁵⁵. In addition, Noyes et al. reviewed a small series of 21 patient who underwent revision ACLR with QT autograft (with bone block) and found significant improvements in knee stability (through KT-1000 testing) and PROMs (including Cincinnati and IKDC scores) at mean 49-month follow-up⁵⁶. In a prospective study, Haner et al. evaluated 51 patients undergoing revision ACLR with QT or HT autograft and found no significant differences in KT-1000 measurements, Lysholm scores, and KOOS subscores at minimum 2-year follow-up⁵⁷. Hunnicutt et al. also performed a prospective analysis of 100 patients undergoing revision ACLR with all-soft tissue QT autografts, finding acceptable early-term and intermediate-term outcomes, no impairments to knee flexion or extension strengths after previous ipsilateral BTB vs. hamstring autograft ACLR, and 14% graft failure rate⁵⁸. In a study comparing QT, HT, and BTB autograft in revision ACLR, Meena et al. found similar functional outcomes between all graft types but noted a higher propensity for graft failure in the HT cohort⁵⁹. In a 2022 retrospective study of 58 revision ACLRs with over 2 years of follow-up, Brinkman et al. found that all-soft tissue QT autografts had similar clinical outcomes when compared to a BTB autograft and may permit faster return to play in athletes with earlier clinical patient-reported improvements⁶⁰.

Although limited, the available literature demonstrates that the QT autograft is an effective selection in the setting of revision ACLR. Currently, the literature indicates that autograft revision reconstructions perform better than allograft reconstructions. With the QT autograft being used less than BTB and HT autografts for primary ACLR, it is often available as an option in these challenging revision cases. In addition, because the QT autograft can be secured without a bone plug, there are no concerns regarding graft-tunnel mismatch. Finally, with the potentially large width and thickness of the QT autograft, it can often fill larger tunnels that have widened in the setting of revision ACLR.

Conclusion

ACLR is among the most commonly performed cases by orthopaedic surgeons worldwide. Although HT and BTB are the most commonly used autografts for primary ACLR, the QT autograft has become increasingly popular in recent years. The unique anatomy of the QT creates a predictable and versatile graft that allows surgeons flexibility in both graft harvest and method of fixation. Although initial outcomes after ACLR with QT autograft were poor, a surgical technique has been refined and the available literature clearly demonstrates that outcomes after ACLR with QT autograft are equivalent to those with HT or BTB autograft, with potentially fewer complications, including postoperative knee pain. Although there are little data available to evaluate the QT autograft in the setting of revision ACLR, the anatomic and clinical versatility of the often available QT makes it an attractive option, and further study of its effectiveness in revision ACLR is needed.

Source of Funding

There were no external sources of funding that contributed to the creation of this manuscript.