Preoperative, Intraoperative, and Postoperative Complications With Posterior Cruciate Ligament

Neurovascular Injury

Complications may occur with the initial injury. There are relatively high rates of neurvovascular injuries associated with multiligamentous knee injury and dislocation. Almost one-third of knee dislocations have an injury to the popliteal artery, ranging from a tear of the intima to a complete arterial transection. Minor injuries may not cause significant damage, but missed injuries affecting perfusion can have severe consequences including amputation. Evaluation and documentation of pulses is a critical step in the initial injury management. In the absence of abnormal physical examination findings, serial examination and ankle-brachial index assessment are important steps in patient observation in case of an evolving injury. Any abnormality in examination should investigated further using arteriography and imaging or immediate exploration as warranted by the severity of symptoms.

Neurological damage can also be associated with multiligamentous knee injury, and is most frequently encountered in the context of a dislocation. Rates of injury have been estimated between 16% and 40%. The common peroneal nerve is involved more often than the tibial nerve, and injury severity can range from neuropraxia to neurotmesis. Therefore careful neurologic assessment is necessary, and examination should be performed before and after any reduction maneuver if necessary. Patients with neurological injury should be counseled appropriately because there are low rates of recovery (31%), but young age has been shown to be a good prognostic factor.

Deep venous thrombosis (DVT) is a common complication in orthopedic surgery. Although there are relatively low rates of symptomatic DVT (0.3%) and pulmonary embolism ([PE], 0.18%) after ACL surgery, there is evidence of increased rates of DVT in asymptomatic patients who have suffered high-energy trauma even before undergoing surgery. ^, A series by Rong found a 10.9% preoperative incidence of proximal DVT on venography in patients with high-energy knee trauma, including injury to one or both of the cruciate ligaments. There was also evidence of increased risk for DVT in patients undergoing arthroscopic surgery for PCL injury alone (17.4%) and PCL with multiligamentous injuries (PCL + medial collateral ligament [MCL]/lateral collateral ligament [LCL], 23.5%; PCL + ACL, 25%) compared with ACL alone (7.2%). Although prospective studies tend to have higher rates owing to detection of asymptomatic DVT, it is important to consider this factor in the preoperative management of a patient with a PCL injury. Of course, traditional risk factors must always be accounted for when working up these patients. The senior author recommends routine evaluation for DVT with ultrasound preoperatively in patients with multiligamentous knee injury. If a clinically significant DVT is identified, and the patient is undergoing immediate surgery, then an inferior vena cava (IVC) filter can placed preoperatively to decrease the risk of PE. Once the patient is postoperatively stable and appropriately anticoagulated for treatment, the IVC filter can be retrieved to limit complications such as thrombosis or filter migration. If the patient’s knee ligament injury can be delayed, then the DVT can be treated without a filter, and the patient can undergo elective surgery at a later date. Postoperatively, appropriate DVT prophylaxis must be continued for prevention of recurrence.

Diagnosis

Beyond assessment of neurovascular status, a thorough physical examination for associated ligamentous injuries should be performed. However, in the acute setting this may be challenging. PCL injury can be evaluated in the office setting with the posterior sag test, quadriceps active test, posterior drawer test, and reverse pivot shift test. The amount of translation with posterior drawer should be noted in comparison with the contralateral limb. Lachman, pivot shift, and anterior drawer tests can all be used to assess the status of the ACL. Varus and valgus stress should be performed at 0 degrees and 30 degrees to examine the integrity of the LCL and MCL, respectively. The PLC (LCL, popliteus tendon, popliteofibular ligament) may be examined with the posterolateral drawer test and the dial test, which is performed at 30 degrees and 90 degrees (increased rotation at 30 degrees and 90 degrees is suggestive of PLC injury in addition to PCL).

Although an accurate history and physical examination are important, the final working diagnosis will require high-quality imaging studies. Radiographs must be carefully analyzed for both obvious and less obvious bony injuries ( Fig. 16.1 ). Subtle avulsion fractures, nondisplaced fractures, and subluxations must be recognized and, in most cases, treated surgically in the first 2 weeks ( Fig. 16.2 ). Postreduction radiographs are also critical to ensuring concentric reduction and reduction maintenance in the case of dislocation or subluxation. If reduction cannot be maintained, knee-spanning external-fixation may be necessary until the patient is ready for surgery. Magnetic resonance imaging (MRI) has high sensitivity and specificity for diagnosing PCL injury, and can identify other soft tissue pathology in the knee. In the setting of chronic injury, MRI imaging may not be sufficient to accurately diagnose the severity of injury. In this case stress radiographs may be required to assess true ligamentous involvement. Early detection of associated injuries to bone, soft tissue, and neurovascular structures will be critical to treatment decisions and successful outcomes with minimal complications.