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A 30-year-old man is the front seat passenger in a motor vehicle accident. He presents with deformity in his knee seen in Figures A and B. Radiographs are seen in Figures C and D. Examination reveals weak foot pulses. After unsuccessful attempts at closed reduction, it is noted that the pulses are no longer palpable and the foot is cool. What is the next step in treatment?
Open reduction through an anteromedial approach, spanning external fixation. If pulses do not return, perform popliteal artery exploration.
Closed reduction in the operating room using a femoral distractor. If pulses do not return, perform on-table angiogram.
Manual in-line skeletal traction using a calcaneal pin in the emergency room, provisional long-leg splinting. If pulses do not return, perform computed tomography angiography in the radiology suite.
Manual in-line skeletal traction using a proximal tibial pin in the emergency room, provisional long-leg splinting. If pulses do not return, perform standard angiography in the angiography suite.
Open reduction through a posterior approach, spanning external fixation. If pulses do not return, perform popliteal artery exploration.
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This patient has a posterolateral knee dislocation with a avascular limb. Urgent surgical intervention is warranted. The medial femoral condyle (MFC) has button-holed through the medial capsuloligamentous structures, leaving skin and medial subcutaneous tissues entrapped between the MFC and the joint cavity producing a ‘pucker sign’. An anteromedial approach is necessary. Stabilization is then best achieved with an external fixator. Persistent ischemia (absence of pulses after reduction) is an indication for popliteal artery exploration.
Posterolateral dislocations are caused by a posterior-directed and rotational force, and are often irreducible. Vascular injury arises because of proximal tethering (fibrous adductor hiatus tunnel) and distal tethering (fibrous soleus hiatus tunnel) at the popliteal fossa.
Rihn et al. outlined the treatment algorithm for acutely dislocated knees. If pulses return after reduction, radiographs and evaluation of ABI are indicated. If ABI<0.9, CT angiography or formal angiography is indicated. If ABI >0.9, a period of in-hospital observation is indicated. If pulses remain absent and the limb remains ischemic following reduction, emergent surgical exploration and revascularization in the operating room is necessary. The spanning external fixator supplies enough rigidity to maintain reduction and allows access for serial neurovascular examinations.
Patterson et al. examined knee dislocations with vascular injury in the Lower Extremity Assessment Project (LEAP) study. Of the 18 patients in this group, all required popliteal arterial repair. Overall, 14 patients were treated with limb salvage and 4 patients were treated with an amputation. Patients with salvaged limbs had moderate to high level of disability 2 years after injury.
Figures A and B show the clinical appearance of posterolateral knee dislocation with a ‘pucker sign’. Figures C and D are radiographs showing posterolateral knee dislocation. These radiographs classically show 1 view of the tibia, but another view of the femur. Thus, the AP XR shows an AP of the tibia, but an oblique of the femur. Similarly, the lateral XR shows a lateral of the tibia, and an oblique of the femur. This is because XR technologist determines the AP/lateral projection based on the position of the foot (which follows the tibia).
Answer 2: Closed reduction is contraindicated because of the risk of skin necrosis, and is also unlikely to be successful because of button-holing. While a femoral distractor is a useful tool to aid reduction, an external fixator is necessary to hold the reduction post-operatively.
Answers 3 and 4: While the limb may be splinted to aid transfer to the operating room, the next step must involve open reduction of the dislocated limb, which can only take place in the operating room. Skeletal traction is unlikely to be successful because of button-holing.
Answer 5: An anterior approach to the knee is necessary to free the entrapped structures.
Rihn JA, Groff YJ, Harner CD, Cha PS.
J Am Acad Orthop Surg. 2004 Sep-Oct;12(5):334-46. PMID: 15469228 (Link to Abstract)
Rihn, JAAOS 2004
Patterson BM, Agel J, Swiontkowski MF, Mackenzie EJ, Bosse MJ.
J Trauma. 2007 Oct;63(4):855-8. PMID: 18090017 (Link to Abstract)
Patterson, JTACS 2007
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Figures A and B are radiographs of a 20-year old male athlete that sustained a high impact tackle during a football game. What percentage of these injuries will present with an associated vascular injury?
Approximately 40% of low-velocity anterior knee dislocations are associated with popliteal vascular injury.
Anterior knee dislocations, which are the most common of all directional dislocations, are produced by a hyperextension mechanism. This causes the tibia to translate anterior to the femur and the popliteal vessels to stretch, causing intimal tears.
Wascher et al. reviewed the association of vascular injury with traumatic knee dislocations. They showed that 50% of all knee dislocations spontaneously reduce. However, patients who present with reduced knee dislocations have a similar risk of vascular injury (~ 40%) and other concurrent injuries as those who present with a dislocated knee.
Levy et al. reviewed the timing of treatment of multiligament-injured knee injuries arising from acute knee dislocations. They suggest that early operative treatment of the multiligament-injured knee yields improved functional and clinical outcomes compared with nonoperative management or delayed surgery. They noted that repair of the PLC, either acute or delayed, may yield higher revision rates compared with reconstruction options.
Figures A and B show AP and lateral radiographs of an anterior knee dislocation. A video is provided that gives a brief overview of knee dislocations.
Clin Sports Med. 2000 Jul;19(3):457-77. PMID: 10918960 (Link to Abstract)
Levy BA, Fanelli GC, Whelan DB, Stannard JP, MacDonald PA, Boyd JL, Marx RG, Stuart MJ.
J Am Acad Orthop Surg. 2009 Apr;17(4):197-206. PMID: 19307669 (Link to Abstract)
Levy, JAAOS 2009
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