High Tibial Osteotomy - Recon

Introduction

High tibial osteotomy (HTO)
- predominately done for varus deformities
- less common for valgus deformities
Angular deformity in the knee leads to abnormal distribution of weight bearing stresses
- can accelerate wear in medial or lateral compartments of the knee and lead to degeneration
- HTO is commonly combined with cartilage restoration procedures to provide better mechanical environment for biologic repair
Prognosis
- varus-producing high tibial osteotomy
  - success rate is 87% in 10 years
- valgus-producing high tibial osteotomy
  - success rate is 50-85% in 10 years

Indications

Indications
- young, active patient (<50 years) in whom an arthroplasty would fail due to excessive wear
- healthy patient with good vascular status
- non-obese patients
- pain and disability interfering with daily life
- only one knee compartment is affected
- compliant patient that will be able to follow postop protocol
General contraindications
- inflammatory arthritis
- obese patient BMI>35
- flexion contracture >15 degrees
- knee flexion <90 degrees
- procedure will need >20 degrees of correction
- patellofemoral arthritis
- ligament instability
- varus thrust during gait

Anatomy

Mechanical axis of lower extremity
- can be assessed by drawing straight line from center of femoral head to the center of the ankle joint
- line axis should pass just medial to the medial tibial spine

Presentation

Symptoms
- pain on medial or lateral side of knee
Exam
- knee malalignment

Imaging

Radiographs
- show knee malalignment using mechanical axis line

Varus-producing tibial osteotomy

Surgical goals
- unload the involved joint compartment by correcting tibial malalignment
- maintain the joint line perpendicular to mechanical axis of the leg
Indications
- can be done for valgus knee with lateral compartment degeneration
  - deformity should be <12 degrees or else the joint line will become oblique
- specific contraindications
  - medial compartment arthritis
  - loss of medial meniscus
  - distal femoral osteotomy better if lateral femoral condyle hypoplasia present

Valgus-producing tibial osteotomy

Goals
- unload the involved joint compartment by correcting tibial malalignment
  - A medial unloader brace can be used for therapeutic and diagnostic purposes. If a patient benefits from the brace, they are likely to benefit from surgery.
- maintain the joint line perpendicular to mechanical axis of the leg
Indications
- can be done for varus knee with medial compartment degeneration (more common)
- best results achieved by overcorrection of the anatomical axis to 8-10 degrees of valgus
- specific contraindications
  - narrow lateral compartment cartilage space with stress radiographs
  - loss of lateral meniscus
  - lateral tibial subluxation >1cm
  - medial compartment bone loss >2-3mm
  - varus deformity >10 degrees
Technique
- lateral closing wedge technique
  - most common technique
  - wedge of bone removed with tibia via an anterolateral approach
  - ORIF of wedge
  - has advantages
    - more inherent stability allows for faster rehab and weight bearing
    - no required bone grafting
- medial opening wedge technique
  - transverse bone cut made in proximal tibia, and wedged open on medial side
  - ORIF of wedge
  - has advantages
    - of maintaining posterior slope
    - avoids proximal tibiofibular joint
    - avoids peroneal nerve in anterior compartment
- focal dome osteotomy (concavity proximal)
  - the center of the dome is located at the center of rotation of angulation (CORA)
  - has advantages
    - corrects limb alignment with the least translation of bone ends
    - least translation of anatomical axis
    - minimal shortening

Complications

Recurrence of deformity
- 60% failure rate after 3 years when
  - failure to overcorrect
  - patients are overweight
Loss of posterior slope
Patella baja
- refers to a shortened patellar tendon which decreases the distance of the patellar tendon from the inferior joint line
  - can be caused by raising tibiofemoral joint line in opening wedge osteotomies
  - can be caused by retropatellar scarring and tendon contracture
  - can cause bony impingement of patella on tibia
Compartment syndrome
Peroneal nerve palsy
- more common in lateral opening wedge osteotomy and lateral closing wedge osteotomy
- minimal risk in medial opening wedge osteotomy
Malunion or nonunion