Traumatic KneeDislocations

Evaluation, Management, and SurgicalTreatment

James R. Lachman, Saqib Rehman,Paul S. PipitoneOrthop Clin N Am - (2015)

PRESENTED BY:DHRUV GOEL

INTRODUCTION• Incidences :< 0.02% of all musculoskeletal injuries.

• This number is most likely an underestimate caused by spontaneous reductions and missed diagnosis.

• Most knee dislocations are the result of high-energy mechanisms .

• Careful history and physical examination in a systematic approach will aid in identifying patients at risk for this injury.

MECHANISM• M:F=2.5 :1

• High-energy mechanism, the most common:• motor vehicle collision (up to 50%). • sports injuries (up to 33%) • simple falls(up to 12%)

• fourth subset, designated ultralow energy, has been recently described.

Classification:

The first description of a knee dislocation : closed versus open

Incidence : open knee dislocations varies between sources from 15% to >35%

LATERAL DISLOCATION

ANTEROLATERAL DISLOCATION

V

C

N

III L ACL / PCL / LCL+PLC MCL intact

IV ACL / PCL / MCL / LCL+PLC

III M ACL / PCL / MCL LCL+PLC intact

Schenck 1992

II

arterial injury

nerve injury

fracture dislocation

Anatomic Classification of Knee Dislocations

I single cruciate + collateralACL + collateralPCL + collateral

ACL / PCL collaterals intact

EVALUATIONAcute Assessment Initial evaluation

PRIMARY SURVEY

ATLS support protocol

SECONDARY SURVEY

careful evaluation of theneurologic and vascular status of the

affected limb

• In patients with a spontaneously reduced knee dislocation, identifying those at risk for vascular or soft tissue compromise is much more difficult.

• Subtle signs of bruising or swelling surrounding the knee may suggest capsular disruption.

Vascular Examination• The incidence ranges in the literature from less than 5% up to 65%.

• Historically,high-energy mechanisms resulting in a hyperextension moment were thought to be more likely to cause vascular compromise.

• Recent review of available literature did not demonstrate an association between direction of dislocation and vascular insult.

• A standard examination includes palpating dorsalis pedis and posterior tibial pulses bilaterally and assessing for any asymmetry.

• In the absence of any asymmetry, further assessment is not necessary.

• Bilateral ankle-brachial-indices (ABI) evaluations in the initial assessment is critical.

• cutoff <0.9, the sensitivity of ABI in detecting vascular injury requiring surgical intervention approaches 100%.

Routine Angiogram• concept of a routine angiogram for all suspected knee dislocations has been

the matter of debate.

Currently, Angiography(routine computed tomographic angiography [CTA] or magnetic resonance angiography [MRA] )

is recommended for patients demonstrating insufficient perfusion or any asymmetry in physical examination

• Green and Allen described the importance of timely identification of vascular injury.

• Of the patients who were identified with vascular compromise, those treated surgically within 8 hours had a significantly lower amputation rate (11%) than those treated after 8 hours (86%)

Vascular Anatomy

• Popliteal artery at risk for being tethered • Adductor hiatus• Soleus arch

• If blood flow through popliteal artery disrupted :blood supply is inadequate distally

Neurologic Examination• The physical examination should include a detailed neurologic examination

including

Sensory examination:Sensation in the

TibialDeep peroneal Superficial peroneal

distributions to light touch, pinprick, and temperature if available

Motor examinationincluding

flexor and extensor hallucis longus,tibialis anteriorgastrocnemius

is important to establish the baseline function

• The incidence of nerve injury : 4.5% to 40.0%.

• Most commonly, the common peroneal is the injured nerve, though isolated tibial nerve palsy has been reported.

• The fibular neck tethers the CPN proximally, and the fibrous arches of the intermuscular septum tethers distally.

• Contrary to intuition, the reported incidence of nerve injury in ultralow-energy knee dislocations is higher (44.4%) than the incidence in the higher-energy trauma patients.

Intraoperative photograph showing near-complete disruption of the common peroneal nerve at the popliteal hiatus after knee dislocation

RADIOGRAPHIC EVALUATIONImmediate• After confirmation of limb perfusion and before physical examination

of ligamentous integrity, standard views of the knee are obtained immediately after reduction.

• Associated fracture has a reported incidence ranging from 10% to 20%.

• Fibular head (arcuate fracture), tibial spine, and lateral tibial condyle (Segond fracture)avulsions are common.

Medial joint space widening Classic arcuate fragment Segond fracture

Secondary

• After the limb is reduced, vascular injury is ruled out and grossly unstable knees are stabilized advanced imaging is appropriate.

• Computed tomography (CT), MRI, or both may be appropriate

EXAMINATION OF KNEE STABILITYClues to ligament injury in a spontaneously reduced knee dislocation are • any asymmetry in the joint space• minor subluxations in any direction• Segond fractures.

• Examination of ligamentous integrity is often limited secondary to patient discomfort.

• Intra-articular injection of lidocaine after aspiration of any hemarthrosis can aid in patient comfort.

Anatomy – 4 groups of ligaments

• ACL• PCL• MCL, posteromedial capsule• LCL & PLC (popliteofibular

ligament, popliteus, capsule, ITB, biceps femoris)

Knee Examination• Special Tests (ligaments)• Valgus and Varus Stress Tests

(MCL/LCL)

• Lachman’s & Anterior Drawer (ACL)

• Posterior Drawer & Posterior Sag Test (PCL)

• Postero-lateral corner

MCL Stability

Apply Valgus or Medial Stress

AT 30° FLEXION

LCL Stability

Apply Varus or Lateral Stress

Test of ACL

At 90° Flexion

At 30° Flexion

(more sensitive)

Posterior Sag

Posterior Drawer

• The Lachman test and anterior drawer :ACL rupture. • Varus/Valgus stressing : MCL/LCL compromise.• Posterior sag :PCL disruption • are the most reliable maneuvers in the acute setting.

• The most common ligament injury pattern is both cruciates and the medial ligament complex .• The posterolateral corner (PLC) is second most common.

• In addition, reports of tendon injury (patella, popliteus, and biceps femoris) are present.

• Intraoperative photographs demonstrating varus and valgus stress examination and fluoroscopic images:

Reduction Technique After palpation of the surface anatomy, gentle in-line traction attempting to bring the knee into extension is enough to reduce a dislocated knee.

• No manual pressure be used to aid in any direction,especially in the popliteal fossa, to avoid iatrogenic neurovascular injury.

• DIMPLE SIGN: closed reduction will be unsuccessful.

SKIN DIMPLINGDIMPLE SIGNButtonhole of medial femoral condyle through soft tissues (capsule, MCL, retinaculum, vastus medialis)

Closed Reduction ManeuverPOSITION of DISLOCATION

(Tibia relative to Femur)

•Anterior• Traction & elevation of distal femur

•Posterior• Traction & extension of proximal tibia

•Lateral / Medial• Traction & correctional translation

•Rotational• Traction & correctional derotation

• Once the knee is reduced, repeat neurolovascular examination.

• With any vascular compromise or asymmetry in ABI(< 0.9), surgical exploration is warranted.

TREATMENTNonoperative Versus Operative Treatment• Management of knee dislocations is a topic of hot debate.

• Direct ligament repair versus ligament reconstruction• use of autograft versus allograft tissue for reconstruction • arthroscopic versus open treatment• and timing of treatment are all areas of controversy

Early TreatmentArterial injuries• Arterial injuries require immediate exploration and vascular surgery

consultation.

• Reexamination is an important mechanism to prevent a missed arterial injury.

• An evolving ischemia, changing pulse examination, or change in ABI measurements can all be detected if routine reexamination is part of standard treatment

Ligament injuries• Determination of ligamentous injury in the emergency room will

govern the next step.

Postreduction knee

UNSTABLETemporizing knee-spanning

external fixator may be placed to provide stability

and allow soft tissues to calm down

STABLE

Placement into a kneeimmobilizer is recommended

instead of circumferentialsplinting or casting

SURGICAL TECHNIQUEAcute Surgical Intervention• Acute ligament reconstruction (earlier than 3 weeks), should be done as an

open procedure because of the capsular disruption precluding arthroscopic assistance.

• If the PLC is involved, a lateral curvilinear incision is used.

• Access to the cruciates and MCL : a midline skin incision with medial para-patellar arthrotomy.

• Posteromedial corner :Posteromedial approach

Sequence of Ligament Reconstruction• Cruciate ligament reconstruction typically precedes PLC reconstruction

• PCL ACL COLLATERAL LIGAMENTS PLC RECONSTRUCTION

Delayed Surgical Intervention Arthroscopy is a preferred method

• Direct repair of the collaterals is no longer possible and reconstruction with autograft or allograft is necessary.

Postoperative Complications• Neurovascular injury• tourniquet problems• wound problems• compartment syndrome• complex regional pain syndrome• knee stiffness• persistent laxity• osteonecrosis• posttraumatic osteoarthritis• Deep vein thrombosis

Outcomes• Levy and colleagues conducted a systematic review that supports early

operative intervention defined as within 3 weeks compared with delayed intervention

• Higher-energy injuries were shown to have inferior outcomes to lower-energy mechanisms

• Lower-energy injuries were correlated with an increased incidence of neurological injuries

• The incidence of posttraumatic osteoarthritis has been reported as high as 87%

Key points• Knee dislocation is a relatively uncommon but often missed diagnosis

leading to significant morbidity.

• Serial examination of a suspected knee dislocation is essential in the prevention of missed arterial injury.

• Currently, angiography is recommended for patients demonstrating insufficient perfusion or any asymmetry in physical examination.

• Clinicians must be aware of the existence of an irreducible knee dislocation.

• Use caution during reduction and cognizant of signs (dimple sign, excessive force required for reduction, joint asymmetry after reduction attempt).

THANK YOU