The posterior cruciate ligament (ACL) is one of 4 major static stabilisers of the knee. It is primary function is preventing posterior (backwards) translation of the tibia (shin bone) on the femur ( thigh bone). It also plays a secondary role with varus and valgus (sideways) and an important role in rotational stability.
The anterior cruciate ligament consists in the human knee of 2 definite bundles; anterolateral and postero- medial bundles.
The posterior cruciate ligament functions as secondary stabiliser to support the lateral (outside) and medial (inside) collateral ligaments.
The anterior cruciate ligament prevents anterior (forwards) movement of the tibia (shin bone) on the femur (thigh bone) and forms a cross in the notch (middle of the knee between the 2 femoral condyles)
|Grade 1||partial PCLrupture ( less than 1cm posterior translation in 90ᴼ flexed knee)|
|Grade 2||partial (1-2 cm posterior translation in 90ᴼ flexed knee)|
|Grade 3||more than 2 cm translation in 90ᴼ flexed knee|
Avulsion injury when bony attachment of the PCL on tibia fractures (breaks) off and is pulled away from its position.
X-rays can show bony avulsions and special stress view posterior displacement
MRI scan is the gold standard in diagnosis of PCL and associated injuries
Partial or grade 1-2 isolated PCL injuries can be treated conservatively with excellent results. The treatment involves 4 weeks of bracing in extension with 3 months rehabilitation.
The results of PCL reconstructions, by modern methods, are improving all the time. There are many examples of high performance athletes that have returned to high demand sports at the highest level after PCL reconstructions. There is also a constant search for improvement in the results of PCL reconstruction, due to the fact that obliteration of posterior sag is very seldom achieved. PCL injuries are less common than ACL injuries and participation in high performance sport can be maintained with a grade 1 PCL laxity. Substituting the PCL ligament with the patient’s own substitute tendon (hamstrings, quadriceps or patellar tendons) still gives the best results when surgery is indicated.
The key of this surgery is to use a graft of comparable strength to the native PCL, anatomic placement of the drill holes in the bones, secure fixation and tensioning of the graft.
Doubling or tripling 2 hamstring tendons (semitendinosus and gracilis) provides a strong and long enough graft that is used and the majority of PCL reconstructions these days. Quadriceps tendon with 2 cm patellar bone block also provides an excellent graft.
The only downside to using the patient’s own tendons (autograft) is donor site complications. Each of these particular graft materials has their own set of complications/side effects.
Allograft (cadaver tendons treated to make it safe for reimplantation) and synthetic ligaments (LARS ligaments) do not give the same outcomes as autografts, at this stage and is only used for salvage procedures.
Arthroscopic (keyhole) fibreoptic instruments and specially designed precise jigs allow surgeons to place the femoral drill holes accurately, whilst following the procedure on monitors.
The graft is harvested through small incisions, making rehabilitation quicker and minimising scars.
In most cases one night stay in the hospital and sufficient and the patient can mobilise safely.
Partial weight-bearing with crutches for 6 weeks and the knee is usually brace in a dedicated brace in extension for 4 weeks,
A structured rehabilitation program is followed and return to running at 8 months.
Integration of the graft is a biological process and return to cutting and contact sport is from 9-12 months. It is essential that the athlete/patient recovers full sense of position and 90% of the strength of the other leg before he or she can return to the chosen sport.
Isolated PCL rupture in sedentary patients can certainly be treated conservatively. It will mean an adjustment in sports participation and diligent conditioning of dynamic stabilisers of the knee. When there is associated injuries, (for instance MCL, ACL, posterolateral corner and meniscus injuries) then the PCL would need to be reconstructed.
here is certainly a higher incidence of ACL injuries with female athletes and certain sports, for instance netball and female soccer. A specific injury prevention program focusing on core stability, prevention of valgus knee movement on jumps and generalised hamstring conditioning/centralisation can prevent ACL injuries. Hamstring fatigue and loss of footing or too much grip of the shoes on playing surface are all factors that can lead to ACL being at risk. Wearing the correct shoe for each surface is also important. All young female athletes that participate in high risk sports, like netball in female soccer, should follow an ACL injury prevention program.
There is usually a definite injury, forcing the athlete not to finish the match or training session. Often this injury is slipped of the foot or twist of the knee whilst changing direction. The knee swells up acutely in isolated ACL injuries. The swelling can subside quite quickly, but the knee will tend to buckle as soon as athlete returns to running. ACL is injuries also happen during high velocity injuries in extreme sports and motor vehicle accidents. There are 3 clinical tests, anterior drawer, Lachmann and pivot shift tests that helps with the diagnosis. Sometimes these clinical test can be difficult in very muscular patients or when the knee is still too painful. X-rays can have subtle bony injuries that are associated with ACL injuries (avulsion fracture or Second fractures) but the gold standard special investigation to diagnose ACL, and associated injuries, is the MRI scan
In most cases an isolated PCL ligament reconstruction can be staged, as long as the knees mobility and quadriceps and hamstring strength is maintained. There are special cases where earlier reconstructions will give better results. When the lateral collateral (LCL) and posterolateral corner PLC (knee ligament complex at outside of knee) are also torn, the results with an accurate PCL, LCL and PLC reconstruction within 1 month achieve better results. PCL ligament injuries in combination with medial collateral ligament MCL also lead to better results when reconstructed early. The PCL needs to be reconstructed when an associated meniscus tear is to be repaired.
Excellent results can be achieved with all 3 different autograft options (hamstrings, patellar tendon and quadriceps tendon) and there is no much to choose between the 3 options. Donor site morbidity plays a role in the surgeon’s decision which graft to select. Patellar tendon graft harvesting as a reported higher incidence of knee pain in the long run. Hamstring tendon harvesting, although strength returns within a year as an incidence of sprains and in certain studies a higher recurrence rate. Quadriceps tendon harvesting seems to have surgical scars issues and longer period of quadriceps atrophy. The contact sportsman and high demand patient certainly requires a lower recurrence rate and low donor site complications incidence.
A special brace is locked for 4 weeks in extension and wear unlocked for another 2 weeks in most cases.
Physiotherapists plate of important role in ensuring full range of motion and an exercise program to protect the knee before the index procedure and in the immediate 6 weeks following the surgery. Biokinetics is important from 5 weeks to 1 year when the athlete can return to his were chosen sport
The incidence of complications with soft tissue arthroscopic knee procedures are generally low and include; deep vein thrombosis, infections, bone marrow oedema and Complex region pain syndrome. Specific complications of ligament reconstructions include recurrence of instability and post-operative knee stiffness. Intra-operative X-rays are done to prevent vascular injuries.