Knee Dislocation

synonyms:

Knee Dislocation ICD-9

• 836.50(closed)
• 836.60(open)

Knee Dislocation Etiology / Epidemiology / Natural History

• High-energy (MVA, Falls from height) in young patients

Knee Dislocation Anatomy

• See Knee Anatomy.

Knee Dislocation Clinical Evaluation

• Either gross defomity or gross instability and extensive soft-tissue swelling if spontaneously reduced.
• Document neurovascular status and perform repeat NV exams in all patients with normal findings to ensure secondary thrombus does not form.

Knee Dislocation Xray

• A/P and Lateral knee xrays. Evaluate direction of dislocation and associated fractures.
• Ankel-Brachial index: patient must be normotensive. <0.9 high risk of vascular injury. Strongly consider angiography vs surgical exploration / repair. (Mills WJ, J Trauma 2004;56:1261).
• Arteriography not considered necessary if pulses are 2+ and symmetrical after reduction. (Harrell DJ Am Surg 1997;63:228-231) (Dennis JW,  J Trauma 1993;35:692-695)
• MRI

Knee Dislocation Classification / Treatment

• Classified by direction of tibial dislocations: anterior; posterior (increased risk of Popliteal A injury; medial; lateral (increased risk of Peroneal N injury; rotatory.
• With Vascular Injury: closed reduction ASAP followed by repeat NV exam. If vascular injury remains acute revascularization is indicated. Arteriogram can be performed in the OR to lessen ischemia time. Consider acute repair of posterolateral structures, capsular structures and avulsion fractures +/- temporary spanning external fixation with delayed ACL/PCL reconstruction.
• Open dislocation: immediate irrigation and debridement. Vascular repair as indicated. Consider acute repair of posterolateral structures, capsular structures and avulsion fractures +/- temporary spanning external fixation with delayed ACL/PCL reconstruction.
• Rec ACL &PCL allograft reconstruction. Wascher Am J Sports Med. 27(2):189,-1999
• compared surg to non-op. Rec ACL/PCL reconstruction Richter Am J Sports Med 30:718:2002

Knee Spanning Ex Fix  Knee External Fixation

• Tube-to-tube fixator
• 2 Schanz screws laterally into femur c carbon fiber rod
• 2 Schanz screws anteromedially into tibia c carbon fiber rod
• connect femoral and tibial carbon fiber robs with 2 addition short rods and bar to bar clamps
• Hold knee in @20 degrees flexion

Knee Dislocation Associated Injuries

• Vasular injury: 32% popliteal artery (OKU-8)
• Nerve: 20-30% peroneal (most common) or tibial nerves (OKU-8)
• Tibial plateu fracture
• Distal femur fracture
• Meniscal tear
• ACL tear
• MCL tear
• LCL tear
• Compartment Syndrome

Knee Dislocation Complications

• Amputation: limb ischemia >8hrs is likely to result in amputation.
• Vasular injury: popliteal artery
• Peroneal nerve palsy
• Tibial nerve palsy
• Compartment Syndrome
• Instability
• Stiffness
• Painful hardware
• Infection
• Arthritis
• Arthrofibrosis
• Complex Regional Pain Syndrome
• Hemarthrosis

Knee Dislocation Follow-up

• Immobilized in extension with non / partial weight bearing for 6 weeks.
• Physical therapy focused on ROM as soon as soft-tissue and vascular repair permit.

Knee Dislocation References

• Shelbourne KD, ICL 2003;52:413
• JAAOS:1995:3:2844=crappy