Posterior Cruciate Ligament
The posterior cruciate ligament is one of the main ligaments of the knee.
Posterior cruciate ligament (PCL) injuries typically occur during hyperflexion or with a blow to the knee during hyperextension. Physical findings such as a positive posterior drawer test or posterior sag and standard x-rays are keys to diagnosis.
Acute isolated PCL injuries often are treated conservatively with strengthening and proprioceptive exercises.
Chronic isolated PCL injuries and combined ligament injuries usually require surgical reconstruction.
Although the posterior cruciate ligament (PCL) is thought to be the strongest ligament in the knee, injury to this ligament is more common than many believe. In fact, PCL injuries may represent up to 20 percent of all knee ligament injuries.
Three types of injuries result in PCL rupture:
- hyperflexion, with or without an anterior tibial force just below the knee
- hyperflexion with a downward force applied to the thigh
- hyperextension, often with varus (bent inward) or valgus (bent outward) force applied to the knee.
Patients who sustain an acute PCL injury may not even be aware that they have experienced a significant knee injury.
Patients with combined injuries to the PCL and one or more other ligaments will have an acutely swollen, unstable knee.
Patients who have chronic PCL injuries may report anterior and/or medial knee pain (from early arthritis) and occasionally instability, especially with twisting and jumping. In these patients, the physical examination is especially critical to the diagnosis.
For patients with chronic PCL injuries, a careful physical examination is essential to avoid missing this injury. The exam also helps identify associated injuries. MRI (Magnetic Resonance Imaging) can be useful.
One option is nonoperative treatment. This does not mean no treatment. Rather, strengthening, proprioceptive, and functional training is required.
Although it varies depending on injury severity, training can usually be initiated within a few weeks of the injury.
It is essential that the rehabilitation program emphasize quadriceps strengthening. “Closed chain” rehabilitation can be used in which the foot is fixed during exercise.
Recommended exercises include minisquats, wall slides, step ups, leg presses, and treadmill exercises.
Proprioceptive exercises such as balance-board therapy, minitrampoline balancing, and plyometrics are also encouraged.
Functional training is initiated, beginning with forward and backward running and progressing to lateral movements, cutting, and sport-specific activities. Functional bracing has not been shown to be effective for PCL-deficient knees.
Most physicians continue to treat isolated PCL injuries nonoperatively. However, a recent long-term follow-up study of patients with this injury reported significant activity-related pain and degenerative changes - especially in the medial compartment - following nonoperative treatment.
Surgical Indications And Outcome
At present, most orthopedists reserve surgical reconstruction for symptomatic chronic PCL injuries and acute combined injuries. Patients who have acute combined injuries should be referred to an orthopedist immeiately because they may have a knee dislocation, which is a surgical emergency.
As knowledge of the PCL increases and techniques improve, reconstruction of acute PCL injuries may be more common, as is currently the case for ACL injuries in athletes. The role of surgery in the acute setting is controversial, however, and further studies of the natural history of the PCL-deficient knee and long-term results of PCL reconstruction will be necessary to resolve this question.
A variety of both extra-articular and intra-articular reconstruction techniques have been used, most with inconsistent results. As with much of orthopedic surgery, re-creation of the original anatomy yields the most consistent results.
After considerable success with arthroscopic techniques for reconstruction of the anterior cruciate ligament (ACL), attempts have been made at similar reconstruction of the posterior cruciate ligament.
Arthroscopic techniques using autograft (tissue or an organ transferred by grafting into a new position in the body of the same individual) or allograft (a graft from a donor of the same species as the recipient) substitution for the PCL probably bear more physiologic and anatomic likeness to the normal ligament than to tissue transfers posteriorly.
The arthroscopic procedure is exacting and technically demanding. Experience is sparse, however, because PCL injuries are uncommon and patients with slight to moderate posterior instability are often able to compensate adequately with good quadriceps function.
Do any tests need to be done to diagnose or to determine the severity of the sprain?
What type of injury is it and how severe is it?
What treatment do you recommend?
What rehabilitation program do you recommend?
Will surgery be recommended?
Can conservative treatment be tried first?
Will the knee ligaments be permanently weak or susceptible to injury?