Mohammad Ayati,M.D Department of Orthopaedics, Yazd University of Medical Science.

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1 IN THE NAME OF GOD

2 Mohammad Ayati,M.D Department of Orthopaedics, Yazd University of Medical Science.

3 Devastating injury resulting from : high-energy usually from MVC or fall from height commonly a dashboard injury resulting in axial load to flexed knee low-energy often from athletic injury generally has a rotational component morbid obesity is a risk-factor

4 Pathoanatomy

5 associated with significant soft tissue disruption 3/4 of ligaments generally disrupted

6 Associated injuries

7 vascular injury 5-15% in all dislocations 50-60% in anterior/posterior dislocations due to tethering at the politeal fossa proximal - fibrous tunnel at the adductor hiatus distal - fibrous tunnel at soleus muscle

8 nerve injury usually common peroneal nerve injury (25%) tibial nerve injury is less common

9 fractures present in 60% tibia and femur most common

10 Prognosis

11 complications frequent rarely does knee return to pre-injury state

12 Classification

13 Descriptive Schenck Classification

14 Descriptive based on direction of displacement of the tibia

15 Anterior Knee Dislocation most common type of dislocation (30-50%) due to hyperextension injury usually involves tear of PCL arterial injury is generally an intimal tear due to traction

16 Posterior Knee Dislocation 2nd most common type (25%) due to axial load to flexed knee (dashboard injury) highest rate of complete tear of popliteal artery

17 Lateral Knee Dislocation 13% of knee dislocations due to varus or valgus force usually involves tears of both ACL and PCL highest rate of peroneal nerve injury

18 Medial Knee Dislocation varus or valgus force usually disrupted PLC and PCL

19 Rotational Knee Dislocation posterolateral is most common rotational dislocation usually irreducible

20 Schenck Classification based on pattern of multiligamentous injury of knee dislocation (KD)

21 Schenck Classification KD I KD II KD III KD IV KD V ligamentous injury with involvement of ACL or PCL Injury to ACL and PCL only (2 ligaments) Injury to ACL, PCL, and PMC or PLC (3 ligaments) Injury to ACL, PCL, PMC, and PLC (4 ligaments) Multiligamentous injury with periarticular fracture

22 Presentation

23 Symptoms history of trauma and deformity of the knee knee pain & instability

24 Physical exam

25 appearance no obvious deformity 50% spontaneously reduce before arrival to ED (therefore underdiagnosed) may present with subtle signs of trauma (swelling, effusion, abrasions)

26 appearance obvious deformity do not wait for radiographs, reduce immediately, especially if absent pulses "dimple sign" - buttonholing of medial femoral condyle through medial capsule» indicative of an irreducible posterolateral dislocation» a contraindication to closed reduction due to risks of skin necrosis

27 stability diagnosis based on instability on exam (radiographs and gross appearance may be normal) may see recurvatum when held in extension assess ACL, PCL, MCL, LCL, and PLC

28 vascular exam priority is to rule out vascular injury on exam both before and after reduction serial examinations are mandatory palpate the dorsalis pedis and posterior tibial pulses

29 vascular exam if pulses are present and normal does not indicate absence of arterial injury» collateral circulation can mask a complete politeal artery occlusion measure Ankle-Brachial Index (ABI) if ABI >0.9 then monitor with serial examination (100% Negative Predictive Value) if ABI <0.9 perform arterial duplex ultrasound or CT angiography if arterial injury confirmed then consult vascular surgery

30 vascular exam If pulses are absent or diminished confirm that the knee joint is reduced or perform immediate reduction and reassessment immediate surgical exploration if pulses are still absent following reduction ischemia time >8 hours has amputation rates as high as 86% if pulses present after reduction then measure ABI then consider observation vs. angiography

31 Imaging

32 Radiographs may be normal if spontaneous reduction look for asymmetric or irregular joint space look for avulsion fxs (Segond sign - lateral tibial condyle avulsion fx) osteochondral defects

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36 MRI o required to evaluate soft tissue injury (ligaments, mensicus) and for surgical planning o obtain MRI after acute treatment

37 THANK YOU