Posterior Cruciate Ligament (PCL) Injury and Treatments
The posterior cruciate ligament (PCL) is one of four ligaments of the knee which function to keep the knee stable.
The anterior cruciate ligament sits in front of the PCL and together the ACL and PCL keeps the tibia (shin bone) from sliding too far forward, these ligaments keep the tibia in position below the femur (thigh bone). The PCL, the knee’s basic stabilizer and almost twice as strong as the ACL, provides a central axis about which the knee rotates.
Posterior cruciate ligament (PCL) injuries make up between 3 and 20 percent of all knee ligament injuries. However, PCL injuries are often left diagnosed. Why it is left undiagnosed and untreated is that even in 2016, the PCL is not well understood. Listen to this research:
The posterior cruciate ligament PCL is the strongest ligament of the knee, serving as one of the major passive stabilizers of the tibio-femoral joint. However, despite a number of experimental and modelling approaches to understand the kinematics and kinetics of the ligament (how it moves and stabilizes), the normal loading conditions of the PCL and its functional bundles are still controversially discussed.1
PCL injuries frequently involve a blow to the knee when the knee is bent. Most athletic PCL injuries occur during a fall on the flexed knee with the toes pointing down and the top of the foot in line with the front of the leg. The shin, or tibia, hits the ground first and is pushed backward. During a motor vehicle accident, the dashboard may drive the shin backward on the flexed knee.
PCL injuries are commonly seen with severe trauma and may occur in conjunction with injuries to other ligaments of the knee, such as an anterior cruciate ligament (ACL) injury, a medial collateral ligament (MCL) injury or a lateral collateral ligament (LCL) injury. These types of injuries stress the PCL, and if the force is high enough, a PCL tear can be the result.
Hyperflexion of the knee without a direct blow to the tibia can also cause an isolated PCL injury, one in which no other ligaments are damaged.
Isolated PCL injuries have also recently come under scrutiny. Untreated knee instability from an undiagnosed PCL tear can lead to meniscal tears and osteochondral injuries which are relatively prevalent in isolated acute PCL injury of the knee.
PCL injury diagnosis
It is important for the physician to know how the injury occurred in order to make a diagnosis. For instance was the knee bent or straight. A common test called the posterior drawer test is very helpful in making the diagnosis. With the knee bent, the doctor presses the tibia backwards to stress the PCL. Abnormal movement can suggest an injury to the PCL. The doctor will also look for an abnormal gait.
X-rays may be ordered to detect pieces of bone that may have broken loose from the injury. MRI’s may be ordered to verify the injury, detect the location of a tear and to visualize whether there is damage to any other structures in the knee.
An injury to the PCL can cause mild to severe damage, and is graded by the severity of injury, grade I through IV. The extent of laxity measured during the examination determines the grade. The classification is as follows:
- Grade I: The PCL has a partial tear.
- Grade II: The PCL is partially torn and is looser than in Grade I.
- Grade III: The PCL is completely torn and the knee is unstable.
- Grade IV: The PCL is damaged along with another ligament in the knee.
PCL Surgery and Controversial Results
Orthopedic surgeons do not agree about the benefit of reconstruction, especially considering the technical difficulty of the surgery due to the position of the PCL in the knee. It is difficult to place grafts in this position, and the grafts tend to stretch out and fail. Generally, surgical reconstruction is reserved for severe injuries involving several major ligaments or for those with persistent knee instability. Even then, surgery involves replacing the torn PCL with either a piece of another tendon removed from elsewhere in the body, or from a cadaver. This is major surgery, not a benign treatment, and one that may leave the sufferer with continued knee pain.
Doctors in Germany released their new findings which found that athletes need realistic expectations when it comes to PCL reconstruction.
“Patients with operatively treated PCL injuries can return to sport. However, for competitive athletes an injury to the PCL can lead to the end of their career.
A reduction of sporting activities and a change from high-impact sports to low-impact sports can be expected (in many cases).”3
A new paper found that doctors need realistic expectations when it comes to PCL reconstruction success.
“The surgical outcome of PCL reconstruction was inferior to that of ACL reconstruction both in patient-based and conventional doctor-based assessments. An improved surgical technique for PCL is required.”4
Please see our article the anterior cruciate ligament for the latest research on ACL reconstruction surgery.
In one new study doctors compared these treatfound that surgery offered more satisfactory and consistent stability in the reconstructive treatment group. However, more complications and small differences of stability between groups should be also considered.
Conservative approaches to PCL Injury
Initial treatment of the pain and swelling consists of the use of crutches, ice, and elevation. This treatment may temporarily relieve the symptoms of the injury, but they do not treat the ligament, which is the source of the injury. Immobilization, ice, and elevation are all designed to decrease inflammation; however, the injured ligament needs the blood supply and healing factors that occur with inflammation. The injured ligament also needs motion for healing.
Treatment may also include anti-inflammatory medications or cortisone injections. Once again, these medications may provide some pain relief, but they both have been shown to inhibit healing and contribute to the degenerative process.
Physical therapy is commonly recommended to improve knee motion and strength. Although a great treatment modality, physical therapy is unable to heal the injured ligament.
As unsatisfactory as these treatments may be to the athlete, a new study comparing these treatments to PCL surgery found more satisfactory and consistent stability in the reconstructive treatment group. However, more complications and the small differences of stability between groups should be also considered.5 In other words, there was not much difference between the two groups except the surgical group had more complications.
The regenerative approach to a Posterior Cruciate Ligament injury with Prolotherapy
In the case of an overstretched or partially torn ligament, a treatment approach to strengthen and heal the injured ligament should be utilized. The treatment that stimulates ligament healing and regeneration is Prolotherapy. Prolotherapy injections directed at the injured PCL will cause a mild inflammatory reaction at the site of the weakened ligament. If other ligaments are involved, they will be treated as well.The body responds by increasing blood supply and regenerative cells to the injured site. A normal wound healing cascade is stimulated by this process. In this healing process the body also deposits collagen in the area of injury. The PCL ligament is made up of a lot of collagen, and as these new collagen cells mature, the ligament becomes stronger. Once the PCL is strong and stable, the symptoms resolve.
Motion and controlled exercise will also be recommended, since the ligament needs to continue moving for proper healing.
In the event of a complete tear or if bone has broken off, requiring surgery, Prolotherapy can also be a healing complement to surgery. Most likely, the other ligaments are at minimum stretched during surgery, and would require strengthening to stabilize the knee. Ideally, a Prolotherapist is sought as a first-line treatment for a posterior cruciate ligament injury.
1 Hosseini Nasab SH, List R, Oberhofer K, Fucentese SF, Snedeker JG, Taylor WR. Loading Patterns of the Posterior Cruciate Ligament in the Healthy Knee: A Systematic Review. PLoS One. 2016 Nov 23;11(11):e0167106. doi: 10.1371/journal.pone.0167106. eCollection 2016.
2 Ringler MD, Shotts EE, Collins MS, Howe BM. Intra-articular pathology associated with isolated posterior cruciate ligament injury on MRI. Skeletal Radiol. 2016 Dec;45(12):1695-1703. Epub 2016 Oct 4.
3 Ahrend M, Ateschrang A, Döbele S, et al. Return to sport after surgical treatment of a posterior cruciate ligament injury : A retrospective study of 60 patients Orthopade. 2016 Dec;45(12):1027-1038.
4 Ochiai S, Hagino T, Senga S, Yamashita T, Ando T, Haro H. Prospective analysis using a patient-based health-related scale shows lower functional scores after posterior cruciate ligament reconstructions as compared with anterior cruciate ligament reconstructions of the knee. Int Orthop. 2016 Sep;40(9):1891-8. doi: 10.1007/s00264-016-3189-0.
5. Ahn S, Lee YS, Song YD, Chang CB, Kang SB, Choi YS. Does surgical reconstruction produce better stability than conservative treatment in the isolated PCL injuries? Arch Orthop Trauma Surg. 2016 Jun;136(6):811-9. doi: 10.1007/s00402-016-2454-4. Epub 2016 Apr 15.