# Hamstring autografts favour knee extension strength recovery while quadriceps autografts optimise flexion strength recovery: A systematic review of randomised controlled trials

## TL;DR

Different tendon grafts used in ACL surgery affect recovery of knee strength differently, with hamstring grafts aiding extension and quadriceps grafts aiding flexion.

## Contribution

Identifies graft-specific strength recovery profiles after ACL reconstruction using systematic review of RCTs.

## Key findings

- Hamstring autografts favor knee extension strength recovery between 6 and 12 months post-surgery.
- Quadriceps autografts result in superior knee flexion strength recovery across all follow-up periods.
- Patellar tendon autografts showed inconsistent results with no consistent superiority.

## Abstract

Quadriceps tendon (QT), hamstring tendon (HT) and patellar tendon (PT) autografts are the most common grafts for anterior cruciate ligament reconstruction (ACLR). However, the specific impact of graft selection on postoperative knee extension and flexion strength remains controversial. This systematic review analysed randomised controlled trials (RCTs) comparing isokinetic muscle strength outcomes following primary ACLR using QT, HT or PT autografts.

A systematic review was conducted by searching Medline (PubMed), Epistemonikos and ScienceDirect (January 2014–10 May 2025) to identify RCTs that included patients aged ≥16 years undergoing primary, unilateral ACLR using an ipsilateral QT, HT or PT autograft. Studies had to report isokinetic strength outcomes at predefined postoperative intervals (approximately 3, 6, 12 and/or ≥ 24 months) and at one or more angular velocities. The PRISMA guidelines were followed for literature analysis. Two reviewers independently screened, extracted and appraised data using the JBI Checklist for RCTs. A narrative synthesis was performed due to significant clinical and methodological heterogeneity among the included studies.

Of 1509 records screened, 13 RCTs met the criteria, encompassing 5 studies using QT, 13 HT and 4 PT. The synthesis revealed distinct recovery patterns: HT autografts showed more favourable recovery of knee extension strength, particularly between 6 and 12 months postoperatively. Conversely, QT autografts consistently resulted in superior recovery of knee flexor strength across all follow‐up periods. The results for PT autografts were heterogeneous, showing some short‐term advantages but no consistent superiority. Patient‐reported outcomes (PROMs) generally improved in all groups, though patterns varied by instrument and time point.

Current evidence indicates graft‐specific profiles of strength recovery after ACLR, with HT autografts favouring knee extension and QT autografts favouring knee flexion recovery. However, heterogeneity in testing protocols, angular velocities and the reporting of limb symmetry indices limits the strength of these conclusions.

Level I.