Rationale

The ability to accurately diagnose a PCL tear in both the acute and the chronic setting is essential in guiding treatment by an orthopedic surgeon.

Clinical comment

PCL injury is often overlooked by both patients and clinicians, and for this reason it is important that sensitive and specific tools are used in the diagnostic process.¹ There is large variability in the reported rate of injury to the PCL with numbers ranging between 1 and 44% of all acute knee injuries depending on the population studied.²–⁴ The sensitivity, specificity, and accuracy of MRI have been found to approach 100% in the diagnosis of PCL injuries.⁵ However, accurate diagnosis via clinical exam would increase the ease and cost‐effectiveness of diagnosis and could facilitate the earlier detection and treatment of PCL injuries.

Available literature and quality of the evidence

• Level I: 1 retrospective cohort examining accuracy of MRI⁵ and 1 randomized controlled trial (RCT) examining physical exam versus MRI.⁶
  
• Level III: 1 systematic review examining physical exam versus reference standard: arthrotomy, arthroscopy, or MRI.⁷
  
• Level IV: 3 case series examining accuracy of MRI.⁸–¹⁰

Findings

The last double‐blinded, RCT examining clinical tests for PCL insufficiency was performed in 1994 by Rubinstein et al.⁶ Using direct comparison to MRI, the study found that there was a 96% overall clinical examination accuracy in diagnosing chronic PCL injuries amongst sports medicine fellowship‐trained orthopedic surgeons, with a 90% sensitivity and 99% specificity in detecting a PCL tear. However, interobserver disagreement about the grade of injury existed in 19% of cases. The posterior drawer test was found to be the most sensitive and specific clinical test; however, for grade 1 laxity it was found to only have a sensitivity of 70%. A systematic review of level II and III studies by Kopkow et al. concluded that the diagnostic accuracy of physical exam tests for PCL injury was largely unknown due to poor quality evidence with high risk of bias.⁷ Multiple level III⁵ and IV⁸,⁹ studies have suggested that the accuracy of MRI for the diagnosis of acute PCL injury approaches 100%. Its accuracy for chronic PCL injuries, on the other hand, has been shown to be as low as 57% in a level IV case series by Servant et al.¹⁰

Another method of diagnosis to consider for PCL injuries not included in the studies above is posterior stress radiography, which can be superior to arthrometric evaluation in quantifying posterior tibial translation.¹¹ Its efficacy and comparison to MRI need to be studied further.

Resolution of clinical scenario

• One level I study suggests that the overall clinical examination accuracy in diagnosing chronic PCL injuries is excellent (96%).
  
• The majority of studies examining diagnostic accuracy of physical exam for PCL injury are old and contain high risk of bias.
  
• Level III and IV studies suggest the accuracy, specificity, and sensitivity of MRI in detecting acute PCL injury approaches 100% but is much less accurate for chronic PCL injury.
  
• Return to case: for the male goalkeeper with a mechanism of injury concerning for PCL injury, MRI would be helpful in the acute setting for diagnosis. Clinical examination is nearly as accurate as MRI if assessed in the chronic setting. However, MRI may still be helpful to rule out associated pathology, such as posterolateral corner (PLC) injury, or for preoperative planning.

Rationale

All surgical procedures pose a risk to the patient. The orthopedic surgeon needs relevant evidence‐based data on long‐term outcomes and risks in order to determine whether the benefit of surgical reconstruction is greater than conservative treatment and whether the risk/benefit ratio is justifiable.

Clinical comment

PCL injuries can be classified based on grade. A grade 1 PCL injury has 1–5 mm of posterior translation of the tibia on the femur on posterior drawer test as compared to the contralateral knee, grade 2 has 6–10 mm of translation, and grade 3 has >10 mm.¹² Typically, nonsurgical management has been advocated for patients with isolated grade 1 or 2 PCL injuries or for those who have grade 3 injuries with mild symptoms or low activity demands.¹³ Nonoperative treatment involves use of a dynamic anterior drawer brace and focused rehabilitation.

Available literature and quality of the evidence

• Level III: 2 retrospective cohort studies.¹⁴,¹⁵
  
• Level IV: 3 case series on outcomes of nonoperative management of isolated PCL injury.¹²,¹⁶,¹⁷
  
• Level IV: 1 systematic review of level III and IV studies comparing long‐term outcomes after operative and nonoperative management of isolated PCL injuries.¹⁸