A tear of a cruciate ligament will represent a major injury to any patient. This multi-page Primer highlights the key issues.
- The cruciate ligaments
- Cruciate ligament tears
- The torn anterior cruciate ligament (ACL)
- The torn posterior cruciate ligament (PCL)
- Multiligament instability of the knee
- Cruciate ligament repair
Cruciate ligament reconstruction
- Cruciate ligament rehabilitation
- Complications of cruciate reconstruction
Page updated July 2023 by Dr Sheila Strover (Clinical Editor)
Cruciate ligament reconstruction involves using a graft to refashion a cruciate replacement.
Torn cruciates - is reconstruction always necessary?
There is controversy amongst surgeons regarding the need to reconstruct all cruciate ruptures.
Because it is now well established that the laxity one gets with a torn cruciate is associated with a high incidence of meniscal tears, many surgeons will not hesitate to advise reconstruction in ALL cases. But other surgeons will assess the degree of risk in relation to the level of activity of the patient, arguing that a sedentary middle aged or elderly patient can cope with the laxity and is not likely to engage in activities forceful enough to go on to meniscal damage.
Primary repair has largely been discredited - sewing the two ends of the old ligament together just does not work adequately - but there is renewed interest in selected cases in repairing in conjunction with 'internal bracing'. Occasionally if the cruciate and its bony attachment have broken away from the main bone a surgeon may get away with a repair that screws back the bony fragment. But mostly the old ligament is replaced with a graft. The most commonly performed procedure for a torn cruciate is the patellar tendon graft (PTG), also called bone-patellar tendon-bone (BPTB) graft, although the leading centres have probably all moved on to use hamstrings grafting. Each has its own complications and indications.
There is general agreement that in skilled hands most people can get close to a return to normal function if the procedure is without complications and the post-operative physiotherapy protocol is adhered to.
Operative Versus Conservative Treatment of Anterior Cruciate Ligament Rupture. Krause M, Freudenthaler F, Frosch K-H, Achtnich A, Petersen W and Akoto R. Dtsch Arztebl Int. 2018 Dec; 115(51-52): 855–862.
Graft choice for cruciate ligament reconstruction
An autograft means that the graft material is taken from the patient and not from a donor. There are different kinds of cruciate autograft:
Bone-patellar tendon-bone graft
In a bone-patellar tendon-bone (B-PT-B) graft a strip of patellar tendon is taken, usually from the same knee (but it could be from the good knee) so that at the upper end there is a piece of bone from the patella and at the lower end there is a piece of bone from the tibia. The chunk of bone at each end allows a strong fixation to be achieved, as the bone heals onto the bone in the graft tunnels. The downside of this graft is that the patella and patellar tendon are weakened. There is some regeneration of these structures, but complications such as patellar fracture are possible.
This graft was known for many years as the 'gold standard'.
Anterior Cruciate Ligament Reconstruction Basics: Bone–Patellar Tendon–Bone Autograft Harvest. Frank RM, Higgins J, Bernardoni E, Cvetanovich G, Bush-Joseph CA, Verma NN and Bach BR. Arthrosc Tech. 2017 Aug; 6(4): e1189–e1194.
Four-strand semitendinosus-gracilis hamstrings graft
The use of the hamstrings tendon followed the use of the bone-patellar tendon-bone graft as it caused less problems at the site of graft harvest. The tendons of the semitendinosus muscle and the gracilis muscle are harvested and then folded in half, creating four strands which are then sewn to one another to create a shorter but strong graft material. There is no bone block on either end, so the fixation is very different from the B-PT-B graft, and may involve for example an endobutton or a transfixation device on the femoral side and an interference screw on the tibial side.
The quadriceps tendon above the patellar can also be used as a cruciate graft. Unlike that bone-patellar tendon-bone graft from below the patella, the quadriceps tendon has a bone plug from its patellar attachment, but the other end has none. This graft tends to be reserved for revision (repeat graft) surgery rather than for the original cruciate reconstruction.
Xenografts are seldom used. A xenograft is a graft harvested from an animal.
Synthetic grafts are still used in certain circumstances, but seldom. They were commonly used in the 1980s.
Management of Anterior Cruciate Ligament Injury: What's In and What's Out? Raines BT, Naclerio E and Sherman SL. Indian J Orthop. 2017 Sep-Oct; 51(5): 563–575.
Anterior cruciate ligament reconstruction in children
The issue of cruciate ligament reconstruction in children all revolves around the issue of the growth plates, and efforts to not damage them. A 'maturity index' called the Tanner staging helps to determine the risk to the cruciate ligaments. See this useful article by Professor Adrian Wilson.
Intrasubstance Anterior Cruciate Ligament Injuries in the Pediatric Population. Aylyarov A, Tretiakov M, Walker SE, Scott CB, Hesham K and Maheshwari AV. Indian J Orthop. 2018 Sep-Oct; 52(5): 513–521.
SAMBBA ACL procedure
Recent appreciation of the importance of the stump of the torn ACL in ligamentisation and proprioception and of the sheath around the ligament in vascularisation has led to the development of the SAMBBA procedure, where semitendinosus tendon is used as a graft but threaded through the stump, which is retained.
Anterior Cruciate Ligament Reconstruction and Preservation: The Single–Anteromedial Bundle Biological Augmentation (SAMBBA) Technique. Sonnery-Cottet B, Freychet B, Murphy CG, Pupim BHB and Thaunat M. Arthrosc Tech. 2014 Dec; 3(6): e689–e693.
Posterior cruciate ligament reconstruction
Posterior cruciate ligament (PCL) surgery is the domain of the specialist knee surgeon.
This is because the surgical approach to the damaged ligament is dangerously close to blood vessels and nerves and the techniques are demanding.
If a PCL has torn itself from the bone, it can be re-attached if diagnosed early enough. A tear through the middle of the ligament can also often be repaired if found early enough, as the blood supply in this region is good.
Many PCL tears, however, are only diagnosed late, for a number of reasons, and then it is necessary to do a ligament replacement procedure. Like the ACL the procedure most frequently done in good units these days is a hamstrings graft using hamstrings tendons taken from the patient on the same side as the injury ('autograft').
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