Updated: 4/16/2019

TKA Coronal Plane Balancing

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https://upload.orthobullets.com/topic/5015/images/coronal balancing.jpg
Introduction
  • Definition
    • both medial and lateral ligaments may be stretched or contracted with time
      • it is essential to balance these ligament in both the coronal and sagital plane to obtain an optimum outcome
  • Pathophysiology
    • concave side
      • tight ligaments that need release
    • convex side
      • stretched ligaments that need tightening
    • must test balancing in both flexion and extension
  • Kinematic alignment
    • principle of placing implants in more varus or valgus based on patient anatomy 
      • constitutionally varus = varus tibial implant
      • constitutionally valgus = valgus tibial implant
    • outcomes are roughly equivalent with neutrally aligned knees
Varus Deformity
  • Anatomy
    • medial side is tight (concave), lateral side stretched (convex)
  • Goals
    • create precise bone cuts
    • release the tight medial ligaments
    • tighten the lax lateral ligaments
    • balance flexion and extension gaps by adjustment of polyethylene bearing thicknesss 
  • Steps of medial release
    • Step 1
      • Deep MCL Release To Mid-Coronal Plane Of Tibia
    • Step 2
      • Medial Osteophyte Removal
    • Step 3
      • Release Posteromedial Corner (Posterior Oblique Ligament)
    • Step 4
      • Medial Tibial Reduction Ostectomy
    • Step 5:
      • Consider PCL Release/Substitution If Imbalance Persists At This Point (If Substitution Not Initially Chosen)  
    • Step 6
      • Release Semimembranosis (Especially If  There Is An Associated Flexion Contracture)  
    • Step 7
      • Pie Crust Superficial MCL (Favor Use Of 18 Gauge Needle)  
    • Step 8
      • Complete Superficial MCL Release / Pes Anserinus
        • Rarely Required Even In Severe Cases 
        • Destabilizes Medial Flexion Gap / Consider A Constrained Prosthesis
        • Differential release: performed with two components of superficial MCL
          • posterior oblique portion is tight in extension (release if tight in extension)
          • anterior portion is tight in flexion (release if tight in flexion)
  • Lateral tightening
    • use a prosthesis that is sized to "fill up" the gap and make the stretched lateral ligaments taut
    • if a polyethylene bearing thickness of >15mm is required to gain appropriate lateral ligamentous tension, consider use of a constrained prosthesis to avoid excessive joint line elevation
Valgus Deformity (lateral side is concave/tight)
  • Anatomy
    • lateral side is tight (concave), medial side stretched (convex)
  • Goals
    • create precise bone cuts
    • release the tight lateral ligaments
    • tighten the lax medial ligaments
    • balance flexion and extension gaps by adjustment of polyethylene bearing thicknesss 
  • Lateral release in order
    • Step 1
      • osteophytes
    • Step 2
      • posterolateral capsule
    • Step 3
      • iliotibial band if tight in extension 
        • with pie crust or release off Gerdy's tubercle
    • Step 4
      • popliteus if tight in flexion (release if tight in flexion)
        • release the anterior part of its insertion
        • for severe deformities release both the iliotibial band and the popliteus
    • Step 5
      • LCL  
        • some authors prefer to release this structure first if tight in both flexion and extension
        • other authors prefer to release the LCL last
          • if LCL & Popliteus require release, flexion gap stability is lost so consider constrained prosthesis
    • differential release: performed by differentially release the IT band and popliteus
  • Medial tightening
    • fill up medial side until medial ligament complex is taut
    • In severe cases, if a polyethylene bearing thickness >15mm is required to obtain appropriate medial tension, consider a constained prosthesis to avoid excessive joint line elevation
Flexion / Contracture Deformity
  • Anatomy
    • concave side is posterior- needs to be released
  • Posterior release order
    • 1) posterior femoral & posterior tibial osteophytes
    • 2) posterior capsule
    • 3) additional resection of distal femur
    • 4) gastronemius muscles (medial and lateral)
  • All releases are performed with knee at 90 degrees of flexion
    • allows the popliteal artery to fall posteriorly to decrease risk of injury
  • You do not want to address a contracture by removing more tibia
    • will change the joint line and lead to patella alta
Complications
  • Peroneal nerve palsy
    • correction of valgus and flexion contracture deformity has highest risk of peroneal nerve palsy 
    • if patient presents with a peroneal palsy in recovery room then
      • then take off dressing and flex the knee
      • watch for three months to see if function returns
      • if function does not return, consider nerve conduction studies or operative exploration to access for damage
  • Coronal plane deformities >20 degrees cannot be corrected by intra-articular bone cuts and soft-tissue balancing alone and require an extra-articular osteotomy 
 

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Technique Guides (3)
Questions (5)
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(OBQ05.117) A 65-year-old woman with painful knee arthritis and the deformity seen in Figure A, is scheduled to undergo a total knee arthroplasty. All the following are risk factors for a post-operative peroneal palsy EXCEPT: Review Topic

QID: 1003
FIGURES:
1

Pre-operative flexion contracture >10 degrees

1%

(33/2542)

2

History of lumbar laminectomy

37%

(948/2542)

3

Female gender

33%

(831/2542)

4

Valgus deformity of >12 degrees

2%

(61/2542)

5

Epidural anesthesia

26%

(656/2542)

ML 4

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PREFERRED RESPONSE 3
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(OBQ10.210) Performing an isolated release of the popliteus tendon during a total knee arthroplasty is most appropriate in which of the following scenarios? Review Topic

QID: 3303
1

Valgus deformity that is tight in extension

26%

(800/3123)

2

Varus deformity that is tight in extension

4%

(123/3123)

3

Valgus deformity that is tight in flexion

60%

(1884/3123)

4

Valgus deformity that is tight in both flexion and extension

7%

(223/3123)

5

Varus deformity that is tight in flexion

3%

(81/3123)

ML 3

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PREFERRED RESPONSE 3
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Topic COMMENTS (5)
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