High tibial osteotomy surgery is considered to delay the time before a total knee replacement is necessary and is typically reserved for younger patients with osteoarthritis pain resulting from malalignment.
Is high tibial osteotomy a major surgery?Yes, high tibial osteotomy is a major surgical procedure.
Preoperative Radiography
X rays
AP, Lateral, long standing films to assess malalignment
MRI
to accurately assess the lateral compartment articular cartilage.
Pre-operative planning of high tibial osteotomy surgery
Weight-bearing axis (Mechanical axis): A line drawn from the center of the femoral head to the center of ankle joint.weight-bearing ratio is calculated by measuring the distance from the medial edge of the proximal tibia to this line divided by the entire width of the tibia.
Correction angle calculation of high tibial osteotomy surgery
The ideal postoperative lower limb alignment is considered as 3°-5° of valgus from the mechanical axis.
Some authors suggest that the post-operative mechanical axis should pass through the lateral one third of the tibial plateau.
Other authors suggest that the degree of correction depends on the thickness of the articular cartilage of the medial compartment.
Dugdale et al suggested that the post-operative weight-bearing line should be located at 62.5% between the medial and lateral compartment of the proximal tibia.
Indications of HTO
- an age between 40 and 70 years
- a knee flexion range more than 90° and, a lack of extension less than 10°
- non reducible deformity
- an active patient
- no contralateral femorotibial joint space narrowing or patellofemoral joint space narrowing
- significant symptomatic chondral injury to the patellofemoral or lateral compartments
Contraindications:
- any inflammatory joint disease
- high BMI
- smoking
- Severe OA of the medial compartment
- total meniscectomy or osteoarthritis in the lateral or patellofemoral compartment
- a tibial subluxation more than 1 cm.
- age more than 60 is a controversial contraindication.
- severe extra-articular deformity
Technique of open wedge high tibial osteotomy surgery
A diagnostic arthroscopy can be used to diagnose and treat intraarticular lesions.
A five cm vertical incision is made over the center between the medial aspect of the tibial tuberosity and the posteromedial aspect of the proximal tibia. The pes anserinus insertion is detached from the tibia and a blunt retractor is inserted subperiosteally posterior to the tibia and also a subperiosteal dissection is performed from the tibial tuberosity to the posteromedial aspect of the tibia.
Under C arm guidance, two guide wires or K wires are inserted at a point about 4 cm below the medial joint line and passed obliquely 1 cm below the lateral articular margin of the tibia towards the tip of the fibular head.
Tibial osteotomy is performed just below the guide wires using an oscillating saw or an osteotome. The osteotomy extends from the medial cortex to one cm medial to the the lateral tibial cortex should be parallel to the posterior tibial slope.
Gradual vulgus force and 2 or 3 stacked osteotomes or calibrated wedge are used to open the osteotomy site.
Once the desired degree of correction is achieved, internal fixation of a metal plate is performed.
Spacer plates with metal block are identical to calibrate the wedge.
Relationship between ACL or PCL injury and tibial slope
PCL injury and it's associated posterior tibial translation are accentuated by an increased tibial slope, while in an ACL injury and it's associated anterior tibial translation are accentuated by an decreased tibial slope.