Role of high tibial osteotomy in chronic injuries of posterior cruciate ligament and posterolateral corner

Abstract

High tibial osteotomy (HTO) is a surgical procedure used to change the mechanical weight-bearing axis and alter the loads carried through the knee. Conventional indications for HTO are medial compartment osteoarthritis and varus malalignment of the knee causing pain and dysfunction. Traditionally, knee instability associated with varus thrust has been considered a contraindication. However, today the indications include patients with chronic ligament deficiencies and malalignment, because an HTO procedure can change not only the coronal but also the sagittal plane of the knee. The sagittal plane has generally been ignored in HTO literature, but its modification has a significant impact on biomechanics and joint stability. Indeed, decreased posterior tibial slope causes posterior tibia translation and helps the anterior cruciate ligament (ACL)-deficient knee. Vice versa, increased tibial slope causes anterior tibia translation and helps the posterior cruciate ligament (PCL)-deficient knee. A review of literature shows that soft tissue procedures alone are often unsatisfactory for chronic posterior instability if alignment is not corrected. Since limb alignment is the most important factor to consider in lower limb reconstructive surgery, diagnosis and treatment of limb malalignment should not be ignored in management of chronic ligamentous instabilities. This paper reviews the effects of chronic posterior instability and tibial slope alteration on knee and soft tissues, in addition to planning and surgical technique for chronic posterior and posterolateral instability with HTO.

Fig. 1

Posterolateral chronic instability

Fig. 2

Closing wedge HTO causes a decrease in posterior tibial slope, and posterior translation of the tibia; it stabilizes a knee with anterior instability

Fig. 3

Opening wedge HTO causes an increase in posterior tibial slope, and anterior translation of the tibia; it stabilizes a knee with posterior instability

Fig. 4

Relationship between tibial slope and kind and site of osteotomy

Fig. 5

The angle α represents the correction required

Fig. 6

Schematic representation of the radiographic methods for evaluation of posterior tibial slope: aATC anterior tibial cortex, bPTAA proximal tibial anatomical axis, cPTC posterior tibial cortex, dPFAA proximal fibular anatomical axis, eFSA fibular shaft axis

Fig. 7

A guide wire is placed from the superior aspect of the tibial tubercle to about 1 cm below the lateral articular margin of the tibia

Fig. 8

Cortical osteotomy is performed with an oscillating saw, inferior to the guide wire, and it will be continued with an osteotome

Fig. 9

When the osteotomy is completed, the medial tibia is opened with a wedge of suitable width

Fig. 10

An image intensifier and an alignment rod are used to control coronal and sagittal alignment during axial loading of the joint

Fig. 11

To fill the osteotomy gap, a carefully shaped bone block from a donor is used

Fig. 12

When correction in the two planes is achieved, the osteotomy is stabilized using a plate with four screws