Working Diagnosis:
Acute PCL tear with exensive bone bruising and an incidental loose body.

Treatment:
Initial treatment involved a brace and non weight bearing status secondary to the bone bruising. The patient was referred to orthopedic surgery for evaluation. Because of it being an isolated PCL tear and the patient being skeletally immature, the initial treatment is conservative. The tibial physis is easily disrupted by PCL reconstructive surgery because of the PCL's location, and this can lead to growth arrest in that limb. With the patient's age there is a strong chance of healing via spontaneous PCL scarring and restoration of functional stability without surgery.

The patient began a course of physical therapy to strengthen knee musculature, focusing on quadriceps strength. Repeat orthopedic evaluation will take place three months after the initial injury, and surgery would be indicated if the patient is still symptomatic. Often these patients are followed annually due to the high incidence of developing chronic knee symptoms.

Outcome:
The patient was unable to return to the 2010 football season, and he could not skateboard for at least three to four months. If the patient eventually receives surgery, expected recovery to full athletic participation is nine to twelve months.

Author's Comments:
Isolated PCL tears in the skeletally immature athlete are rare and studies on treatment are limited. Often the PCL is injured in concert with other ligamentous damage. Isolated PCL tears in the young athlete have a strong chance of healing via spontaneous scarring of the PCL to restore functional stability to the knee. In addition, the initial treatment is often conservative in cases like this one because of the risk of tibial physis disruption with PCL reconstructive surgery.

Editor's Comments:
The PCL is an important stabilizer of the knee, as the primary restraint to posterior translation and a secondary restraint to external rotation of the tibia. This case illustrates a classic sporting mechanism of injury with a forceful anterior impact to a flexed knee. The subsequent pain, instability, effusion, and mechanical symptoms are additional key features in the history pointing to a significant ligamentous injury. Physical examination should include the posterior drawer test, posterior sag test. The quadriceps active test and reverse pivot shift tests can also aid in diagnosis. The dial test can help to different a lone PCL injury from a more significant posterolateral corner injury.
As the author discussed isolated PCL tears are rare in skeletally immature patients. Non-operative treatment is often favored initially to see if scarring and stability can be obtained without potential disruption to the physis which can occur in surgery.

References:
1. Cosgarea AJ; Jay PR. "Posterior Cruciate Ligament Injuries: Evaluation and Management". J Am Acad Orthop Surg. 9:297-307, October 2001.

2. DeLee. "Posterior Cruciate Ligament Injuries". DeLee and Drez's Orthopaedic Sports Medicine. 3rd Edition. 2009.

3. Green and Swiontkowski. "Posterior Cruciate Ligament". Skeletal Trauma in Children. 4th Edition, 2008.

4. Rigby JM; Porter KM. "Posterior Cruciate Ligament Injuries". Trauma. 12:175-81, 9 August 2010.

5. Watsend A; Osestad T; Jacobsen R; Engebretsen L. "Clinical Studies on Posterior Cruciate Ligament Tears Have Weak Design". Knee Surg Sports Traumatol Arthrosc. 17:140-9, 2009.

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