posterolateral rotatory instability of the knee steven a. seeker, m.d

Posterolateral Rotatory Instability of the Knee

Steven A. Seeker, M.D.

ObjectivesDefine posterolateral rotatory instability

of the kneeEvolution of the human kneeAnatomy and biomechanics of the

posterolateral cornerClinical presentation and treatment

options for acute and chronic instability of the posterolateral corner of the knee

DefinitionHughston et al. JBJS 1976Posterior subluxation of the lateral tibial

plateau that can occur with an external rotation torque in knees with pathologic laxity of the posterolateral corner

Symptoms can occur acutely after violent injury or develop insidiously after relatively mild injury

Evolution of human knee Complex anatomy due

to evolution Early on, both the tibia

and fibula articulated with the femur

As the human knee evolved, the fibula and attached capsule moved distally

Evolution of human knee The popliteus

attachment moved from the fibular head to the femur creating an intra-articular portion

Biceps attachment moved from the capsule and tibia to the fibula

Posterolateral corner

“ Dark side of the knee “Andrews 1988

Varying anatomy and inconsistent terminology of the popliteofibular ligament

Anatomy of the posterolateral corner

Three distinct layers

Anatomy of the posterolateral corner

First layer Iliotibial tract

attaching to the tibia at Gerdy’s tubercle

Biceps femoris attaching to the fibular head

Second layer Quadriceps

retinaculum anteriorly

Patellofemoral and patellomeniscal ligaments posteriorly

Third layer Superficial lamina:

Lateral collateral ligament

Fabellofibular ligament

Third layer Deep lamina:

Coronary ligament and popliteal hiatus

Popliteus

Arcuate ligament

Popliteofibular ligament

Oblique popliteal ligament

Third layer Deep lamina:

Coronary ligament and popliteal hiatus

Arcuate ligament

Popliteofibular ligament

Oblique popliteal ligament

Variable anatomySeebacher et al. JBJS 198235 cadaver kneesConclusions:

arcuate ligament alone in 13%fabellofibular ligament alone in 20%both in 67%no mention of popliteofibular ligament

Variable anatomySudasna and Harnsiriwattanagit 1990Dissection of fifty cadaver kneesConclusions:

“Fibular origin of the popliteus” (Popliteofibular ligament) in 98%Fabellofibular ligament in 68%Arcuate ligament in 24%

Variable anatomyWatanabe et al. arthroscopy 1993115 cadaver dissectionsConclusions:

lateral collateral and popliteus present in all knees“popliteus muscle with origin from the fibular head” (popliteofibular ligament) present in 94% of knees

Popliteofibular ligament (PFL)

Oversight in anatomy texts resulted in disappearance of this structure until only recently

Maynard et al. Am J Sports Med 1996 reported on the “rediscovery of the PFL”


This appears to be an important static stabilizer of the posterolateral corner


Maynard et al. Am J Sports Med 1996Cross sectional area of PFL only slightly

less than FCLMaximal force to failure PFL (425 N)

FCL (747 N)

Popliteofibular ligament (PFL)Veltri et al. Am J Sports Med 1996

PFL and popliteus were important in resisting posterior translation, primary varus rotation, and external rotation

Blood supply

Popliteal artery

Genicular arteries

Review of anatomy

Three layers of the posterolateral corner

First layer are dynamic stabilizers

Second layer relatively unimportant

Review of anatomyThird layer: static stabilizers and most

important layerFCL and popliteus are always presentPFL present in majority of kneesarcuate and fabellofibular ligaments are variablecoronary ligaments are very loose to allow for very mobile lateral meniscus

Biomechanics

Biomechanics Nielson et al. Arch Orthop Trauma Surg

1984, 1985 Lateral collateral and posterolateral capsule

resist varus and external rotation of the tibia Popliteus resists varus from 0-900 and resists

external rotation from 20-1300 of flexion PLC also is a secondary restraint to posterior

translation, but isolated sectioning of the PCL does not affect varus or external rotation

Biomechanics Gollehon et al. JBJS 1987 PCL resists posterior translation Sectioning of PLC/FCL causes the greatest

increase in varus and external rotation at 30o of flexion

Additional sectioning of PCL causes greater increase in varus and external rotation

ACL/PLC sectioning causes tibial internal rotation and anterior translation to be increased at 30o and 60o

ACL or PLC sectioning alone does not increase tibial internal rotation

BiomechanicsMarkolf et al. JBJS 1993

Sectioning of PLC significantly increases the force on the PCL between 45o and 90o of flexion

Sectioning of PLC increases mean force on ACL at all flexion angles

BiomechanicsNoyes et al. Am J Sports Med 1993Sectioning PLC increases lateral tibial

plateau posterior translation at 30o but not at 90o

Sectioning of PLC and PCL increases posterior subluxation of both plateaus at both 30o and 90o

BiomechanicsLaPrade et al. Am J Sports Med 1999Forces in ACL grafts when the

posterolateral corner had been sectioned were increased with coupled varus and external rotation at 0o and 30o

of flexion

BiomechanicsSkyhar et al. JBJS 1993Ten cadaver kneesCombined sectioning of PLC and PCL

resulted in significantly more patellofemoral contact force than sectioning of the PCL alone

BiomechanicsSummary: Isolated PCL tear does not increase

primary varus or external rotation Isolated FCL tear causes a mild

increase in varus angulation which is greatest at 30o of flexion

Injury of PLC with intact PCL results in maximal increase of varus, external rotation and posterior translation at 30o of flexion

BiomechanicsSummary:However, at 90o, the PCL fibers become

tight and exert a secondary constraint on varus and external rotation

PCL and PLC complete injury cause increased varus, external rotation and posterior translation at all flexion angles

Cruciate ligament grafts are at increased risk of failure in knees with posterolateral rotatory instability

Examination of the posterolateral corner

History and physical examspecial tests

Radiographic evaluationMagnetic resonance imagingArthroscopic evaluation

HistoryPain in posterolateral kneePeroneal nerve symptoms?May have medial or lateral joint line pain Instability with knee in extension

Physical examinationEdema, ecchymosis, induration and

tendernessFull ligament exam and neurovascular

exam in all patientsMay have standing varus alignment or a

varus thrust with walking May walk a flexed knee due to pain and

instability with knee hyperextension

Special testsPosterior drawerTibial external rotation (dial) testPosterolateral external rotation testReverse pivot shift testExternal rotation recurvatum test

Posterior drawer Performed at 30o and

90o

Laxity at 30o indicates PLC injury

Laxity at 90o indicates PCL injury

May appear like an ACL injury, but tibia is posterior and ACL endpoint is good

Tibial external rotation (dial) test

Performed while prone at 30o and 90o

PLC only:increased at 30o only

PCL only: no side to side difference

PCL and PLC: increased at 30o and 90o

Posterolateral external rotation test

Performed at 30o and 90o with coupled posterior and external rotation force

Similar results to drawer and dial tests

Reverse pivot shift test Sensation of

reduction when the flexed, externally rotated tibiaknee is extended with a valgus applied force

May be positive in up to 35% of normal knees during EUA

May be PLC or PCL injury

External rotation recurvatum test

Elevation of lower extremity by great toe results in hyperextension, varus and external rotation

PCL vs. PLC vs. Both

Radiographic evaluation Plain film

radiographs may show avulsion fractures, widened lateral joint lineSegond fracture (lateral capsular sign may be present)

Magnetic resonance imaging Yu et al. Radiology

1996 T2 weighted coronal

oblique MRI give best resolution of PLC

LaPrade et al. Am J Sports Med 2000

Developed protocol for PLC imaging

Arthroscopy Valuable to evaluate

popliteus and meniscus, as well as articular surface injuries prior to open repair

“Drive through sign” Caution:

fluid extravasation

Grading of injuryGrade 1: no abnormal motion with 0 –

5mm of joint opening, and definite end point

Grade 2: slight to moderate abnormal joint motion with 6 – 10 mm joint opening, and definite end point

Grade 3: markedly abnormal joint motion with greater than 10 mm joint opening, and no endpoint

Grading of injuryKannus Am J Sports Med 198923 patients with grade 2 and 3 injuries

treated non-operatively8 year follow-up11 patients with grade 2 lesions

excellent or good knee scores, 9 were asymptomatic, all had residual laxity, no DJD

12 patients with grade 3 lesions fair or poor knee scores, but not all isolated PLC injury, DJD in 6 patients

TreatmentNon-operative treatmentOperative treatment

1. Acute injury2. Chronic instability

Non-operative treatment Isolated posterolateral corner injuries

are treated with a hinged knee brace to prevent varus and external rotation

The literature supports non-operative management of all grade 1 and 2 isolated PLC injuries

However, may consider operative management of grade 2 lesion if cruciate reconstruction is planned

Operative treatmentAcute injury:

Direct repair within 3 weeks to avoid “matted mess” has best outcome+/- augmentation

Chronic instability:Reconstruction

Surgical approach

Incision

Surgical approach

Internervous plane: between ITB and BF

May osteotomize Gerdy’s tubercle for better visualization

Must see the common peroneal nerve

Direct repair

Skin incision often is the only dissection needed in acute injuries

Repair deep structures first, followed by superficial structures

Direct repair

May need to augment structures with autograft or allograft if structures are not repairable

Combination of techniques used to repair all structures

Order of evaluation / repairCoronary ligament: evaluate for tears or

avulsion from tibia – fix with sutures or anchors

Popliteus and popliteofibular ligaments: fix with anchors or pull-out sutures if avulsed or Kessler sutures if torn

FCL: sutures or anchorsArcuate and fabellofibular ligaments:

variable, but should be repaired if torn or avulsed

Reconstruction of chronic instability

Often needed after grade 3 injuries treated non-operatively

Surgical dissection more difficult secondary to scar

Goals: restore function and stability to the knee

Special considerations for reconstruction

Alignment: full length x-rays of lower extremity to evaluate

Varus with lateral thrust: HTO prior to reconstruction of posterolateral structures or repair will stretch out

High tibial osteotomy

Not like HTO for DJD

Long lateral incision centered over ITB

Gerdy’s tubercle advanced with bone plug

Avoid disruption of proximal tib-fib joint, as this will worsen PLC symptoms

High tibial osteotomy Gerdy’s fixed with

6.5mm screw Osteotomy fixed

with staples Fibular osteotomy

should be performed at the mid fibula level

Reassess PLC at 6 months, symptoms may resolve with re-alignment

High tibial osteotomyAlternatively, a medial opening wedge

osteotomy of the proximal tibia can be performed

Advantages: avoids the proximal tib / fib joint and posterolateral structures

Disadvantages: 2 surfaces to heal+/- use of allograft or ICBG

Posterolateral corner reconstruction

Advancement of femoral attachment of FCL and PTHughston and Jacobson

Advancement of FCL / popliteus and lateral gastroc origin with suturing of FCL to gastroc

96 knees follow-up 4 years85% objectively good78% subjectively good80% functionally good


Advancement fixed with knee at 90o

Criticized because it does not address PFL or popliteus musculotendinous junction


Knee is placed in a controlled motion brace with 45 degree extension block

Flexion is encouraged to prevent patellofemoral problems

Biceps tenodesis (Clancy and Sutherland)

Anchor the biceps to the lateral femoral condyle to reduce the deforming force in external rotation and to recreate the FCL

39 patients, average follow-up of 32 months77% no ADL restriction54% return to sports


Wascher Am J Sports Med 1993 biomechanical study showed that this was effective, but it overconstrained the joint

Veltri et al. Am J Sports Med 1996this does not address the popliteus or PFL


Many authors have been reluctant to attempt this because of the difficulty in salvaging the knee if this fails

Recession of PT and FCL (Jakob and Warner)

When the popliteus and FCL are stretched, but intact, the femoral attachment may be recessed and fixed by a screw / washer

Advantage is isometric placement

Recession of PT and FCL (Jakob and Warner)

If the PFL is intact, this procedure should tighten this structure as well

Posterolateral corner sling(Albright and Brown)

Uses autograft or allograft to recreate the static effect of the popliteus

Central third of the ITB is harvested and left attached to Gerdy’s tubercle

Tunnel drilled through lateral tibia to the point of normal popliteus passage on the posterior lateral plateau

Posterolateral corner sling(Albright and Brown)

Graft is fixed just proximal to the origin of the FCL

30 patients 8 excellent (no joint pathology)10 poor (joint pathology or instability)6 additional procedures

Does not address PFL or FCL

Anatomic reconstruction of PT and/or PFL and/or FCL

(Veltri and Warren) Suggested anatomic

reconstruction of all injured / attenuated structures

Popliteus: reconstruct with allograft (achilles) similar to Albright’s procedurefix with suture and buttons or interference screws


(Veltri and Warren) Popliteofibular ligament:

similar, but tunnel drilled through fibula to recreate origin of PFL ligamentfixed to lateral epicondyle just proximal to FCL originsecured with buttons or interference screws


(Veltri and Warren) Popliteus and PFL:

combine both reconstructions with a single split achilles allograft with bone end of the graft secured to the femur


(Veltri and Warren) Popliteus, PFL and

FCL: If FCL also requires reconstruction, use distally based segment of the biceps femoris with fixation to the epicondyle with screw and soft tissue washer


(Veltri and Warren) Patient is placed in

a hinged knee brace to prevent varus and external rotation

Toe touch weight-bearing with brace locked in extension

Allowed motion when NWB


(Veltri and Warren) Bike at 4 weeks Closed chain at 6

weeks Jogging at 4 months Brace worn for 6

months Return to sports at

6-9 months


(Veltri and Warren) This technique is

relatively new and there are no long term follow-up studies

Promising because of anatomic reconstruction of injured structures

Order of repair of the multiply ligamentously injured knee

Most authors at the recent AAOS suggested fixing the PLC prior to ACL or PCL repair

If all three are injured, fix the PLC first at 300, followed by the PCL

ACL may be fixed at a later date

Review of Posterolateral corner

Anatomy is variable, but the FCL, popliteus and popliteofibular ligaments are present in most knees

Careful physical examination of all ligaments will allow the diagnosis of injury to the PLC

PLC laxity is greatest at 30o of knee flexion

Arthroscopy and MRI are useful adjuncts to physical exam


Grade 1 and 2 isolated lesions can be treated conservatively

Grade 3 lesions should be treated operatively

Early operative intervention has the best chance of a good result

Late reconstruction is a salvage procedure

Prognosis is related to other related pathology (ie. DJD, meniscus tear, etc.)


Multiple methods of reconstruction are available

Anatomic reconstruction is a promising new method of reconstruction, but follow-up studies are not yet available

posterolateral rotatory instability of the knee steven a. seeker, m.d

Documents

coronary ligament

posterolateral cornersymptoms

popliteus present

knees popliteus muscle

fibular origin

j sports med

cadaver kneesconclusions

human kneeanatomy