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Radiographs for HTO

This is a presentation of a medial opening wedge tibial osteotomy for isolated medial compartment osteoarthritis in a 52 year old man who works in heavy labour.

In such a case it would be undesirable to consider arthroplasty as a surgical solution to his arthritis. Due to his young age and heavy work he is likely to fail a knee replacement at a young age requiring revision surgery, most likely in his sixties. The result of primary knee replacements are good however patients undergoing revision surgery can expect poor function with low PROMs scores. He may well still be at work at the age he requires an arthroplasty.

Being in mind also that the knee has some healthy cartilage in the lateral compartment it would be shame not to “sweat the asset” of the knee and delay arthroplasty surgery for as long as possible. Osteotomy to offload the medial compartment has been shown to be an excellent procedure in these cases. By shifting the weight-bearing axis onto the lateral side of the knee excellent pain relief can be expected and can last for over 10 years. This can be achieved by essentially swinging the ankle laterally by opening a wedge in the medial tibia or closing a wedge in the lateral tibia. This is a description of the opening osteotomy.

The presentation describes a biplanar osteotomy, so called as the opening is created in two planes. The opening osteotomy runs across the tibia from medial to lateral at a level proximal to the pes anserinus. The second osteotomy runs up behind the tibial tubercle. The advantage of this technique is that the anterior osteotomy controls sagittal and rotational displacement.

OrthOracle readers will also find the following instructional techniques of interest:

Proximal Tibial Osteotomy using a Newclip plate.

Patella stabilisation: Rotational proximal tibial Osteotomy

Unicompartmental Knee replacement: Persona Partial Knee Replacement (Zimmer-Biomet)

Unicompartmental Knee replacement: Journey Uni (Fixed Bearing). Smith and Nephew

Author: Andrew Pearse FRCS (Tr & Orth)

Institution: The Worcestershire Acute NHS Trusts, Uk.

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- See: PreOp Planning:

- Discussion:
- a candidate for HTO should have relatively normal lateral and patellofemoral compartments;
- degenerative changes confined to medial compartment should be apparent in x-rays, although minor arthritic changes in lateral
compartment or patellofemoral joint are not absolute contraindications
- HTO is contraindicated w/ lateral compartment or patellofemoral symptoms along with associated radiographic changes;
- Radiographs:
- full-length, wt bearing x-rays are used to determine the desired amount of correction;
- to unload the arthritic medial compartment, a relative valgus knee alignment is created;
- radiographic methods for planning the osteotomy:
- mechanical axis method:
- requires long cassett;
- the mechanical axis is represented by the angle formed by the line joining the femoral head to the center
of the the intercondylar notch and the line joining the interspinous region to the center of the ankle;
- normally this line should be superimposed over the wt bearing axis;
- if neutral alignment is considered noral, 2-3 deg overcorrection would be indicated for the patient with medial joint arthrosis;
- anatomic axis method:
- formed by the intersection of lines formed by the axis of the femur to the intercondylar notch and the line formed by the
interspinous region to the center of the ankle;
- goal is to achieve 8 deg of valgus;
- wt bearing axis is represented by the line drawn thru center of femoral head to the center of the ankle;
- normally it should pass just medial to the center of the knee joint;
- if neutral alignment is considered normal, 2-3 overcorrection would be indicated for the patient with medial joint arthrosis;
- supine over correction method:
- motivation for this technique is based on the premise that patients whose varus deformity is based in part on ligamentous laxity
need less correction than patients w/o laxity;
- assumptions: the mechanical axis value just prior to heel strike is similar to the supine mechanical axis measurement;
- measure the supine mechanical axis and add 10 deg of correction (supine overcorrection);

- Anatomy:
- varus or valgus angulation of arthritic knee usually results from 3 components:
- geometric alignment of femur & tibia;
- narrowing or loss of bone & cartilage in one compartment;
- widening of other compartment's joint space because of slack ligamentous and soft-tissue structures;
- detected by measuring difference between involved knee and the opposite, uninvolved knee.
- each millimeter of excessive joint space separation causes an apparent 1 deg of angular deformity on weightbearing x-ray;
- if widening is not taken into consideration malalignment may be overcorrected;

- Technical Considerations:
- its essential to have good quality radiographs both supine and standing;
- ensure that radiographs are taken w/ the patella facing forward (rather than the patient's feet);
- note the difference between wt bearing and non wt bearing radiographs

Results of proximal tibial osteotomy. The effects of tibiofemoral angle, stance- phase flexion-extension, and medial-plateau force.

Axial parameters affecting lower limb alignment after high tibial osteotomy.

Axial lower limb alignment: comparison of knee geometry in normal volunteers and osteoarthritic patients.