Table 1.

Characteristics of 10 studies included, according to the methodology used.

Author (Year) Study Design	Objective	Participants	Rehabilitation Procedures (Duration)	Outcomes Measures	Evaluation Follow-Up	Participants Gender n (%)	Principal Findings
Cavaignac, E., et al., 2017 [48] Cohort study	To compare isokinetic strength test of HTA and QTA, stability, functional outcomes scores, anterior knee pain and reoperation rate.	95 patients QTA; n = 45; 32.1 ± 8 years HTA; n = 41; 30.9 ± 9 years.	–	Functional outcome (KOOS, Tegner and IKDC), Joint stability KT-1000, Lachman, pivot shift), anterior knee pain (Shelbourne-Trumper score), and isokinetic strength.	6 and 43 months post-surgery	QTA: 55% male HTA: 58% male	The use of a QTA graft in ACL reconstruction leads to equal or better functional outcomes than does the use of an HTA graft, without affecting morbidity.
Csapo, R., et al., 2019 [41] Retrospective cohort study	To assess the fitness of elite alpine skiers during recovery from ACL reconstruction and changes in performance level after return to competition.	46 athletes; QTA; n = 21; HTA; n = 25.	–	Isokinetic dynamometry, back in action test battery (knee function after ACL recovery), VAS Functional outcome (Lysholm score, Tegner activity scale)	15 days, 6, 12, and 24 months post-surgery	20 male vs. 26 female	The rate of recovery of knee extensor muscle function may be slower following ACL reconstruction using QTA. On overage, athletes returned to competition within one year after surgery and succeeded in surpassing their baseline performance level within the first year after return to competition.
Fischer, F., et al., 2018 [42] Randomized Controlled Study	To compare isokinetic strength test for Quadriceps in who received either QTA or HTA autografts at two-time intervals within the first year after surgery.	124 patients QTA; n = 61; 21.7 ± 7.4 years, HTA; n =63; 21.5 ± 6.9 years.	Isometric and closed chain exercises, bicycling running and sport-specific exercises post-operatively.	Isokinetic strength test.	5.5- and 7.6-months post-surgery	QTA: male 34 (55.7). HTA: male 47 (74.6)	ACL reconstruction with a QTA autograft have a significantly higher H/Q ratio within one year after surgery compared to the HTA group.
Guney-Deniz, H., et al., 2020 [45] Cross-sectional, case–control study	To compare isokinetic strength test, the active joint position sense and knee functions in individuals who had anterior cruciate ligament (ACL) reconstruction with QTA, HTA, TAA and healthy individuals.	67 subjects QTA; n = 22; 27.8 ± 2.8 years, HTA; n = 24; 26.7 ± 4.6 years, ATT; n = 21 26.4 ± 5.5 years, Control; n = 20 28.7 ± 3.1 years.	Post-operative protocol includes progressive quadriceps femoris strengthening with neuromuscular electrical stimulation, and neuromuscular control exercise training.	Isokinetic strength test and active joint position sense assessments	13.5 months post-surgery	–	Knee proprioception deficits and impaired muscle strength were evident among patients at a mean 13.5 months post-ACL reconstruction compared with healthy controls. QTA group may be more likely to actively over-estimate knee position near terminal extension.
Han, H.S., et al., 2008 [43] Retrospective comparative study	To compare the clinical outcomes of anterior cruciate ligament reconstructions using QTA and PTA autografts.	144 patients QTA; n = 72; 27.8 (15–51) * years, PTA; n = 72; 27.8 (15–51) * years	–	knee stability (KT-1000), Functional outcome (Lysholm and IKDC) and Isokinetic strength test.	Pre-surgery, 6, 12 and 24 months	QTA: 68 male vs PTA: 68 male.	QTA group showed clinical outcomes comparable to PTA group with anterior knee pain beingless severe in the former. The data indicate the quadriceps tendon can be a good alternative graft choice.
Hunnicut, J.K., et al., 2019 [49] Cohort Study	To compare quadriceps recovery and functional outcomes in patients with QTA versus PTA autografts.	30 patients QTA; n = 15; 25.0 (14.0–41.0) years PTA; n = 15; 18.0 (15.0–32.0) years	–	Isometric and isokinetic strength testcentral Activation, MRI, Spatiotemporal Gait Hop Test and Functional outcome (IKDC, Lysholm, and KOOS)	8 months post-surgery	QTA: male 12 vs. PTA: male 7	Patients with QTA autografts demonstrated similar short-term quadriceps recovery and postsurgical outcomes compared with patients with PTA autografts.
Lee, J.K., et al., 2016 [15] Cohort study	To compare functional outcomes and knee joint stability of anatomic ACL reconstruction with double-bundle hamstring tendon and bone–quadriceps tendon autografts	96 patients QTA; n = 48; 31.1 (17–57) * years, HTA; n = 48; 29.9 (17–58) * years	Post-operative protocol includes quadriceps-strengthening, continuous passive motion, open kinetic chain exercise and kinetic exercises. (6 months)	Knee stability (Manual laxity test, KT-2000) Functional outcome (IKDC, Tegner activity score, modified Lysholm score), anterior knee pain questionnaire, Isokinetic strength test and tunnel position evaluation by quadrant method.	Pre-surgery and 6 weeks, 3, 12 and 24 months post-surgery	QTA: male 44. PTA: male 44	QTA group showed similar knee stability and functional outcomes when compared with the HTA autograft. Better flexor muscle strength recovery was found in the QTA, indicating a potential advantage of the QTA autograft in ACL reconstruction.
Martín-Alguacil, J.L., et al., 2018 [44] Randomized Controlled Study	To compare the strength recovery and functional outcomes of an anatomic single bundle reconstruction with QTA and HTA autografts in competitive soccer players.	51 participants QTA; n = 26; 18.7 ± 3.6 years, HTA; n = 25; 19.2 ± 3.6 years.	Both groups followed the same pre-and-post rehabilitation protocol based on muscular strength, endurance and neuromuscular control. (24 weeks)	Isokinetic strength test Function outcome (Lysholm knee score and Cincinnati Knee Rating System) and knee stability with KT-2000.	Pre-surgery and 3, 6, 12 and 24 months post-surgery	QTA: male 23 (88.5). HTA: male 16 (54.0)	QTA group showed similar functional outcome results with a better isokinetic H/Q ratio compared to HTA group at 12 months of follow-up in soccer players.
Pigozzi E., et al., 2004 [14] Prospective randomized study	To compare the isokinetic recovery of thigh strength after ACL reconstruction by using patellar or quadriceps tendon as a graft.	48 patients QTA; n = 24; 33 (21–47) years PTA; n = 24 35 (23–41) * years	Post rehabilitation program: continuous passive motion, walking, swimming, cycling and running at the end of 6 months. (6 months)	Counter movement jump, leg press, knee stability (KT-1000) and isokinetic strength tests.	Pre-surgery and 6 months post-surgery.	QTA: 17 male vs. PTA: 19 male	Significant improvement of the lower limb strength deficit using QTA compared to PTA that could encourage the use of QTA in order to achieve an easier rehabilitation and a faster Return to sport.
Sinding, K.S., et al., 2020 [47] Prospective randomized controlled clinical trial	To investigate the effects of QTA vs. HTA on thigh muscle strength and functional capacity, and a patient-reported outcome 1 year after ACL-R, and to compare the results to healthy controls.	150 patients QTA; n = 50; 128.7 ± 6.4 years, HTA; n = 50; 28.3 ± 6.2 years, CON; n = 50; 28.3 ± 6.2 years	Post rehabilitation program: days 1–14: full support to pain threshold, free movement, no bandages; weeks 3–12: frequent movement exercises supervised by a physiotherapist, bicycle ergometer, full weight bearing; months 4–9: running allowed; months 10–12: contact sports. allowed. (12 months)	Isokinetic strength test, one leg hop test and Functional outcome with IKDC	12.5 months post-surgery	QTA: male 25 (60%) HTA: male 23 (53%) vs. CON: male 27 (54%)	HTA leading to impairments of knee extensor and knee flexor muscle strength, while QTA results in more pronounced impairments of knee extensor only. Functional capacity and functional outcome was unaffected by autograft type, with the former showing impairment compared to healthy controls.

ATT, tibialis anterior tendon; HTA hamstring tendon autograft; H/Q, Hamstring/quadriceps; IKDC, International Knee Documentation Committee; KOOS, Osteoarthritis Outcome Score; MRI, Cross-sectional Area; PTA, patellar tendon autograft; QTA, quadriceps tendon autograft; VAS, visual analogy scale. * Median (range). –: None.