Management of degenerative osteoarthritis of the knee in the young, active patient remains challenging. Accelerated cartilage degeneration in this patient population is often associated with increased medial or lateral knee compartment pressures due to lower extremity malalignment. Realignment osteotomies of the distal femur and proximal tibia function to offload the affected compartment and, therefore, function to prevent further cartilage degradation and improve pain.¹ Despite the increasing utilization of knee arthroplasty procedures, there remain limitations in the use of arthroplasty in a young patient population due to the risk of early revision rates and lower return to high-impact activities.²,³ Osteotomies have garnered renewed attention in recent years as desirable alternatives to arthroplasty procedures due to the ability to preserve the native joint and potentially facilitate return to high-level activities and work.⁴,⁵,⁶,⁷ Additionally, osteotomies about the knee may be combined with various ligament reconstructions and meniscus and cartilage procedures to improve the success of these surgeries.

The most commonly performed osteotomies for the degenerative knee include proximal tibial osteotomies (“high tibial osteotomy,” HTO) for varus deformities and distal femoral osteotomies (DFOs) for valgus deformities. Advances in techniques and fixation devices have led to continued improvements in functional outcomes. The purpose of this chapter is to review the indications, preoperative planning strategies, and evolving surgical techniques for the various osteotomies utilized for treatment of the degenerative knee or realignment as part of cartilage repair/reconstruction.

Appropriate patient selection is paramount for optimal outcomes following osteotomy procedures. Although the specific indications for femoral and tibial osteotomies differ, general patient characteristics are important to consider when performing a realignment osteotomy. The ideal patient is a relatively young (<60 years old), active, nonsmoking individual with localized knee pain. The patient must be capable of enduring the average 6-month recovery and adhering to a rehabilitation protocol. Commonly accepted contraindications for realignment osteotomy include inflammatory arthritis, severe tricompartmental osteoarthritis, multiplanar ligamentous instability, extreme deformity, and bone loss.⁸,⁹ Anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) insufficiency is not considered to be a definite contraindication, as these ligaments deficiencies can be addressed concomitantly with the osteotomy.¹⁰,¹¹,¹²

The role of obesity in patient selection for realignment osteotomy has been debated within the literature. Obesity is defined as 1.32 times ideal weight and as body mass index (BMI) greater than 30 kg/m². Multiple studies have demonstrated an association between obesity and poor outcomes following lower extremity realignment osteotomy.¹³,¹⁴ Coventry et al¹³ reported probability of survival after HTO of only 38% after 5 years and 19% after 10 years in obese patients, compared with 90 and 65% probabilities in patients with average weight, respectively. A recent study by Liska et al¹⁵ demonstrated a significantly higher rate of nonunion in smokers and patients who underwent DFOs with BMI >30 kg/m². However, some authors argue that osteotomy is preferable to the high rate of complications in the obese patient population undergoing knee arthroplasty.⁹,¹⁶

The decision to perform a realignment osteotomy should be individualized. It is imperative that patients are counseled on their unique risks, and general health must be optimized.

Characterizing the nature of the deformity is critical for determining the optimal corrective osteotomy procedure for the degenerative knee. The surgeon must first determine the location, direction, and magnitude of the deformity. Knee alignment is analyzed by measuring the mechanical and anatomic axes of the lower extremity on standing alignment radiographs. The weight-bearing line of the knee is measured from a straight line drawn from the center of the femoral head to the center of the talus and crosses the tibial plateau at a point 48% to 62.5% of the distance from the medial proximal tibial edge in a normally aligned knee.²²,²⁶ The deformity is determined based of the location of the center of the knee in relation to the weight-bearing line (Fig. 26-1).

The location of the osteotomy is traditionally determined to avoid joint line obliquity. Varus deformities with medial compartment wear are typically treated with an HTO, and valgus deformities are managed with DFOs to offload the lateral compartment. However, the decision as to the optimal location and type of osteotomy is ultimately based upon the individual patient’s characteristics and degree of deformity. It is critically important to identify if the bony deformity is on the tibial versus femoral side, as this determines the site for the osteotomy. The mechanical lateral distal femoral angle and medial proximal tibial angle should be measured to more accurately identify the site of deformity (Fig. 26-2). For example, although a valgus deformity is felt to be usually associated with a degree of hypoplasia of the lateral femoral condyle and is thus typically corrected on the femoral side, Eberbach et al²⁷ measured coronal alignment on 420 standing long-leg radiographs of patients with valgus malalignment and found that 41% of valgus deformities were tibial based, 24% were femoral based, 27% were tibial and femoral based, and 9% were intra-articular/ligament based, suggesting that varus-producing osteotomy may need to be done on tibial side or as a double-level osteotomy in order to avoid an oblique joint line. Severe coronal deformities (greater than 10° to 15°) will often require combined tibial and femoral osteotomy to avoid joint line obliquity.²⁸ Schroter and colleagues²⁹ described the use of a double-level osteotomy in severe varus osteoarthritis (average 11°) and demonstrated good functional outcome with restoration of the joint line and improved angular measurements.

Opening wedge osteotomy is currently the preferred technique in the literature for both varus and valgus deformities. The opening wedge technique has the theoretical advantage of simplifying the procedure with a single bone cut, allowing for improved control over the degree of correction. The potential disadvantages include the risk of delayed union or nonunion. Closing wedge osteotomies have been suggested as a more favorable technique for patients with comorbidities that may increase the risk for nonunion, such as smoking and obesity.²²,³⁰ Another proposed benefit of the closing wedge technique is the ability to bear weight earlier than opening wedge osteotomies; however, these differences are now less of a consideration with the development of newer implant devices that allow earlier weight-bearing with both techniques. Disadvantages of closing wedge osteotomies include bone loss and the technical challenge of the technique for achieving a precise angular correction.