
Illustration of a torn anterior cruciate ligament, where the ligament has ruptured through its mid-substance.
A cruciate ligament injury may affect anterior or posterior cruciate ligament or both. The ligament may tear, stretch or avulse from the bony attachment. Page updated June 2024 by Dr Sheila Strover (Clinical Editor)

Illustration of a torn anterior cruciate ligament, where the ligament has ruptured through its mid-substance.
Usually one is unable to continue with the activity, with pain, immediate instability and early swelling.
Peer-reviewed papersQuote from peer-reviewed paper:
Citation: Rodriguez K, Soni M, Joshi PK, Patel SC, Shreya D, Zamora DI, Patel GS, Grossmann I, Sange I. Anterior Cruciate Ligament Injury: Conservative Versus Surgical Treatment. Cureus. 2021 Dec 6;13(12):e20206. doi: 10.7759/cureus.20206. PMID: 35004026; PMCID: PMC8730351.
Quote from peer-reviewed paper:
Citation: Smith HC, Vacek P, Johnson RJ, Slauterbeck JR, Hashemi J, Shultz S, Beynnon BD. Risk factors for anterior cruciate ligament injury: a review of the literature - part 1: neuromuscular and anatomic risk. Sports Health. 2012 Jan;4(1):69-78. doi: 10.1177/1941738111428281. PMID: 23016072; PMCID: PMC3435896.
The cruciate ligaments are important stabilisers of the knee, and damage may lead to instability. The ligament has a good blood supply, so injury may also cause rapid bleeding into the knee - the blood will be contained within the capsule, leading to a balloon-like sudden swelling. A loud 'pop' may be heard at the time of the injury. There may be an immediate feeling of instability.
Peer-reviewed papersQuote from peer-reviewed paper:
Citation: Rodriguez K, Soni M, Joshi PK, Patel SC, Shreya D, Zamora DI, Patel GS, Grossmann I, Sange I. Anterior Cruciate Ligament Injury: Conservative Versus Surgical Treatment. Cureus. 2021 Dec 6;13(12):e20206. doi: 10.7759/cureus.20206. PMID: 35004026; PMCID: PMC8730351.
The decision to repair or reconstruct is not an emergency. Once the diagnosis of a cruciate ligament tear has been made, the knee is put into a functional brace, where it is still possible to walk with some restraint but twisting movements are restricted. This period in a brace allows the knee to settle and blood to be resorbed. Then patient and surgeon can discuss the issues and decide on surgery to repair or reconstruct the ligament.
Peer-reviewed papersQuote from peer-reviewed paper:
Citation: Rodriguez K, Soni M, Joshi PK, Patel SC, Shreya D, Zamora DI, Patel GS, Grossmann I, Sange I. Anterior Cruciate Ligament Injury: Conservative Versus Surgical Treatment. Cureus. 2021 Dec 6;13(12):e20206. doi: 10.7759/cureus.20206. PMID: 35004026; PMCID: PMC8730351.
Quote from peer-reviewed paper:
Citation: Paschos NK, Howell SM. Anterior cruciate ligament reconstruction: principles of treatment. EFORT Open Rev. 2017 Mar 13;1(11):398-408. doi: 10.1302/2058-5241.1.160032. PMID: 28461919; PMCID: PMC5367541.
A cruciate beginner wanting to understand more.