High tibia osteotomy for early medial knee arthritis is a surgical intervention that shifts the mechanical axis from the medial to the lateral side of the knee joint, thereby unloading the medial early degenerative knee compartment by shifting the force/area from the medial compartment to the lateral outer 1/3 of the knee joint.

Patient suitable for osteotomy include:

• ≤ 60 – 65 years
• ≤ Grade I or II unicompartmental osteoarthritis
• Range of motion ≥ 90º
• Flexion deformity of <15º
• Mechanical axis deviation <15º

This intervention is also an augment to address knee instability
Ideal for the relatively young active individual with early medial knee arthritis that meets the osteotomy criteria (Feeley B T et al)

• A: closing wedge osteotomy
• B: opening wedge osteotomy

Valgus knee arthritis with an abnormal lateral femoral condyle may be addressed by a distal femur osteotomy procedure.

• • ICRS 0: normal.
  • ICRS 1a: Intact surface but fibrillation ± softening.
  • ICRS 1b: fissuring.
  • ICRS 2: Defect < 50%.
  • ICRS 3: Lesions > 50%.
  • 3a: lesions > 50% but not to calcified layer.
  • 3b: lesions > 50% to calcified layer but not through subchondral bone.
  • 3c: lesions extending to subchondral bone plate.
  • 3d: blisters.

ICRS 4: full thickness osteochondral lesions.

Osteochondritis dissecans (OCD) excluded from this classification system.

• • OCD classification
  • Type 1: stable but softened area covered by intact cartilage
  • Type 2: partial discontinuity but stable on probing
  • Type 3: complete discontinuity but in situ
  • Type 4: empty defect with dislocated fragment or loose fragment in situ

Subgroup ICRS OCD 1-4 B: defects >10mm in depth

Top left arthroscopy pic of cartilage wear. Top right surgery technique using microfracture. Healing 9bottom right) with fibrocartilage.

HTO surgery option for Ahlbäck < Grade 3

X-rays:

• Mechanical axis: measure osteotomy angle
• AP weight bearing in full extension
• Rosenberg views at 30° & 40°- 45° knee flexion
• Lateral view

MRI:

• Provides additional information regarding meniscus, cartilage wear & bone oedema

Osteotomy angle calculation

Dugdale technique:

• Line drawn from the centre of femoral head to outer 62.5 % tip of tibia width
• Second line drawn from centre of the ankle to the outer 62.5 % tip of tibia width
• The bisector angle is the osteotomy angle

Right knee skin incision

After skin incision, release superficial MCL at the level of the osteotomy site.
Release yet protect the Pes tendons

Use 2 parallel K wires, this is a guide for the osteotomy bone incision. Drill with oscillating saw below the K wires. Do not saw through the outer tibia cortex as this must remain intact & serves as the centre of rotation of the opening wedge osteotomy

Protect neurovascular & infrapatellar tendon soft tissue structures

X-ray showing the osteotomy with osteotomy wedge in situ.
Calculated osteotomy wedge inserted. Allow adequate time for bone expansion when preparing the osteotomy

If osteotomy angle ≥12° consider bone grafting at the osteotomy site