The Anterior Cruciate Ligament (ACL) is a major stabiliser of the knee. ACL rupture is being increasingly identified in children and skeletally immature patients. The current advice in younger patients is usually to undergo ACL reconstruction. The choice of an ideal graft in children is difficult

This study will use a technique involves the use of hamstring tendons from a living donor, where the adult (usually a parent) agrees to donate their hamstring tendons, which are dissected out of them and implanted into the child

The Anterior Cruciate Ligament (ACL) is a major stabiliser of the knee. ACL rupture is being increasingly identified in children and skeletally immature patients. Following rupture of this ligament, the current advice in younger patients is usually to undergo ACL reconstruction. Different tissue or materials can be used to reconstruct the ligament. In the majority of cases around the world, tendon material taken from somewhere else in the patient is preferred, particularly the hamstring or patellar tendons.

The choice of an ideal graft in children is difficult. Patients who have not fully grown have smaller tendons than adults, making them less suitable for use in reconstructive surgery. Another option for children's reconstructions is allograft - tendons taken from another human being. This has most commonly been from organ donation (taking tendons from a recently deceased individual) however the rerupture rate of allograft has been shown to be higher than in autograft (tendons taken from the patient themselves). The higher rate of rerupture may be related to the sterilising and storage processes of the harvested tendons.

This study will use a technique used by a leading hospital in Sydney, Australia, that sees and treats a large volume of these patients and has published good outcomes. The technique involves the use of hamstring tendons from a living donor, where the adult (usually a parent) agrees to donate their hamstring tendons, which are dissected out of them and implanted into the child. The technique has the advantage of leaving the child's own tendons intact, and having a larger sized tendon from a parent.

Patients & parents will be approached in clinic after MRI confirmation of an ACL rupture. If all inclusion and exclusion criteria have been passed and they consent to participate, screening documents & tests will be completed. The parent will undergo a hamstring tenotomy whilst the child is prepped for ACL reconstruction, then the hamstring donor graft will be inserted in the child patient, using the surgeon's routine fixation devices. All patients will be assessed for skeletal maturity prior to surgery and will be followed up for two years or until skeletal maturity, whichever happens latest. They will follow standard rehabilitation guidelines for paediatric patients at Maidstone & Tunbridge Wells National Health Service Trust (MTW NHS Trust) and be seen at set study intervals for clinical review, subjective and objective assessment. Any adverse events will be reported to the health regulation authority and Human Tissue Licence Authority.

Inclusion Criteria:

• Patients aged 8 to 17 years inclusive and have a clinically and radiologically confirmed ACL rupture that requires reconstruction.
• Patients who have had previous surgery for meniscal pathology .
• Patients with current meniscal pathology
• The child and their responsible adult are in agreement with the choice to undergo anterior cruciate ligament reconstruction using living donor allograft.
• Donors has not previously undergone tendon harvest on the chosen donor limb
• Patients are willing to attend follow up appointments and agree to fill in knee questionnaires and allow instrumented knee ligament testing.

Exclusion Criteria:

• Patients who have previously undergone ACL surgery on the same limb (and therefore require revision surgery)
• Patients who are immunosuppressed, or receiving immunosuppressive therapy
• Patients who are unable to attend follow-up appointments for continued research purposes.
• Donors who have previously undergone hamstring tendon surgery on the donor limb
• Patients and donors who have a positive screening blood test for any of the transmissible infections tested
• Donors whose answers to the 'Donor Documentation Questionnaire' indicate that there could be a risk of transmissible infection, may not included
• Donors who are not considered healthy enough to undergo a tenotomy under General anaesthetic