Total knee arthroplasty (TKA) after high tibial osteotomy (HTO) is made challenging by prior skin incisions, patella baja, retained hardware, altered tibial anatomy, and altered knee kinematics.

Careful planning of the incision must be done to avoid necrosis between prior incisions while also facilitating exposure and allowing selective hardware removal.

In knees with patella baja or stiffness, a stepwise approach to surgical exposure is important to have in mind before surgery.

Painful hardware should be removed; otherwise, partial in situ removal of only the hardware that impedes implant placement is preferred.

Lateral tibial bone loss and distortion of proximal tibial anatomy causing an offset tibial canal after closing wedge HTO requires preoperative planning of the tibial cut and implant placement; the use of custom implants or corrective osteotomy may be necessary in severe deformities.

Altered knee joint kinematics requires attention and appropriate ligament balancing to achieve symmetric gaps; the use of a posterior-stabilized implant is recommended to facilitate this.

Careful assessment of previous skin incisions and planning of the operative skin incision is paramount for successful wound healing. Avoid far lateral incisions.

Because many prior HTOs are laterally based closing-wedge osteotomies, make a slightly more medial skin incision to leave a skin bridge of at least 6 cm between previous lateral incisions; in prior medially based osteotomies, the old medial incision is typically acceptable.

Cross transverse incisions perpendicularly, and for S-shaped or inverted L-shaped incisions, the vertical limb of the incision can be extended proximally.

For stiff knees or knees with patella baja (Figure 56.1), a stepwise approach is necessary to achieve adequate surgical exposure:

A baseline infection evaluation with a C-reactive protein and erythrocyte sedimentation rate along with a detailed history of postoperative wound healing should be standard in these patients with previous open knee surgery and retained hardware; a knee aspiration should be considered in any patient with abnormal inflammatory markers, a history of wound drainage, or a history of infection.

Assess the patient’s knee range of motion preoperatively; stiff knees will be more challenging to obtain safe surgical exposure, as described previously.

A careful varus-valgus ligamentous examination should be performed to ensure the prior surgery did not result in ligamentous insufficiency; if concerned, a varus-valgus constrained implant should be available.

Standard anteroposterior, lateral, and standing hip to ankle radiographs should be obtained to assess for retained hardware, patella baja, tibiofemoral deformity, and a medially offset tibial canal.

Patella baja or a posteriorly offset tibial plateau should alert the surgeon that adequate exposure may be more challenging.

Lateral tibial plateau deficiency (Figure 56.2) is often present; preoperative planning of the proximal tibial cut is necessary to avoid overresection of the medial tibial plateau.