See Differential Diagnosis for more details
As with any fracture, whether open or closed, it is important to assess the neurovascular status of the affected limb. The initial assessment should include palpation of the dorsalis pedis and posterior tibial pulses, light touch sensation over the first dorsal web space and lateral foot for the common peroneal nerve and the plantar aspect of the foot and medial instep for the tibial nerve, as well as motor function of the distal leg. Open fractures are considered surgical emergencies, with a need for a surgical irrigation and debridement within the first few hours after presentation. Appropriate prophylactic antibiotics are administered upon presentation, and tetanus prophylaxis is administered as necessary. Patients with vascular compromise need immediate referral and assessment by a trauma specialist or vascular surgeon. Fractures should be immobilised as necessary and orthopaedic consultation obtained as necessary. Open knee dislocations need assessment as to whether reduction in the emergency department or operating theatre is necessary.
Dislocated or spontaneously reduced knee dislocations constitute an urgent evaluation due to the high risk of associated vascular or neurological injury. CT angiograms are indicated for any cases of decreased pulses or high-velocity knee dislocation. Popliteal artery tears constitute a surgical emergency due to the high rate of amputation (>90%) if a limb is not revascularised within 8 hours. Popliteal artery intimal flap tears must be diagnosed and carefully evaluated for a minimum of 72 hours post-injury to verify that a clot does not form in the popliteal artery and block blood flow. In addition, knee dislocations and revacularised limbs after a knee dislocation must be carefully monitored for the possible development of compartment syndrome.
Patients with significant pain, redness, warmth, and swelling around the knee must be evaluated to exclude joint infection. Patients with these symptoms and signs may include those who have had recent surgery and those who have had recent open fractures or lacerations around the knee. Anterior-posterior x-rays may be normal. ESR and CRP are likely to be elevated. Aspiration of the joint is recommended to differentiate between bacterial infection, gout, or pseudogout. Aspiration must be performed under sterile conditions to prevent an inoculation of an infectious source from the overlying skin.