*4.1.1 Anteromedial approach*

As 90% of knee arthroplasties are associated with varus deformity, the anteromedial approach is more frequently practiced by surgeons. Therefore, even in valgus deformities, most surgeons opt for the anteromedial approach.

The advantage of this approach is that it allows a wide view of the joint cavity and does not require any additional training by the surgeon.

The disadvantage of this approach is that it does not directly address the lateral contracture structures. In cases of mild deformity, Ranawat grade 1, small surgical gestures such as releasing the iliotibial band (ITB) and pie crusting the lateral capsule may be sufficient. In developed countries in Europe and North America, this is perhaps the majority of cases. But in Latin American, African, and Asian countries, severe cases classified as Ranawat grade 2 or 3 are frequent. To correct these major deformities, the medial approach can cause problems not only with ligament balance, but mainly with patellar tracking.

To compare the clinical and radiological outcomes of anteromedial and anterolateral approaches for valgus TKA, a pilot randomized clinical trial evaluated the radiographic patellar tilt, the visual analog scale of pain, postoperative levels of hemoglobin, and clinical aspect of the operative wound. Mean lateral tilt of the patella was 3.1° (SD ± 5.3) in the lateral approach group and 18° (SD ± 10.2) in the medial approach group (*p* = 0.02). There were no differences regarding other outcomes [4].

In severe deformities, release of lateral patellar retinaclum is necessary in most cases in order to prevent patellar instability. Lateral release in combination with medial capsulotomy results in significant impairment of the extensor mechanism blood supply and could cause avascular necrosis of the patela [11].

#### *4.1.2 Anterolateral approach*

The anterolateral approach proposed by Keblish in 1991 allows for a better exposure of the lateral and posterolateral structures, which are contracted in valgus deformities and should be released for proper ligament balance; it also has the advantage of including the release of lateral patellar retinaculum, which is necessary in most cases with valgus deformity [12].

After proper preparation and placement of drapes and with the knee positioned at 90°, the technique begins with the skin incision, which must follow the direction of the deformity (so that at the end of the procedure and consequent correction of the deformity, the incision is straight). An incision between 15 and 20 centimeters is usually sufficient, starting over the superior pole of the patella, going to the anterior tibial tuberosity (ATT) (laterally). Skin and subcutaneous tissue should be detached together and to a sufficient extent just to access the lateral border of the patella, avoiding unnecessary tissue damage. The arthrotomy is performed starting at the center of the quadriceps tendon, going down the lateral border of the patella, to the lateral border of the ATT. It is essential to maintain Hoffa's fat connected by its pedicle to the lateral portion of the capsule, as this tissue will be necessary for its closure. Nikolopoulos et al. in 2015 provided a detailed description of the lateral approach technique, along with its advantages and disadvantages [6].

As in the classic medial arthrotomy, in which the deep medial collateral is released as part of the approach, we recommend, in the lateral approach, desperiostization of the lateral portion of the tibia, thus detaching the distal insertion of the iliotibial tract from the tubercle of Gerdy. This step already releases one of the three major soft tissue structures involved in valgus deformity (the other two being the lateral collateral ligament and the popliteal tendon). In cases of mild and reducible deformity, this already resolves the ligament balance. For this reason, we strongly believe that the indication of the lateral approach is advantageous even in milder cases, solving at the same time the ligament balance and patellar tracking.

Exposing the tibia is actually a little more difficult with this access. This is mainly due to the fact that the TAT is lateralized, which opens a smaller window of vision (the space between the TAT and the lateral collateral is much smaller than the space between the TAT and the medial collateral). For the same reason, patellar eversion is a more difficult maneuver to perform, which makes the exposure of the tibia more

#### *Total Knee Arthroplasty in Valgus Knee DOI: http://dx.doi.org/10.5772/intechopen.109573*

difficult. We recommend spending a little more time on this step for adequate exposure of the tibia and consequent correct understanding of the structures and their relationships.

Keblish's original description includes an anterior tibial tubercle osteotomy (ATT) for further exposure. We do not believe it to be necessary in the vast majority of cases. However, in certain situations such as in severe valgus knees or after a previous tibial osteotomy, patella's eversion may be compromised and the patellar ligament may be particularly prone to spontaneous avulsion by forceful retraction, especially if patella cannot be everted with the knee flexed at 90°. In these situations, the surgeon should not hesitate to perform an ATT. This is a safe and effective procedure. It also may simplify proper positioning of the tibial component in severe valgus knees, avoiding internal rotation of the tibial component. However, careful fixation of the tuberosity is mandatory [11].

### **4.2 Soft tissue balancing**

The goal of ligament balance is to achieve symmetrical rectangular extension and flexion gaps. This can be achieved through several techniques, summarized in just two main philosophies: "Mesaured ressection" and "Gap balancing." Gap balancing relies on ligament releases prior to bone cuts. There are basically two gap balancing sequences. One relies on balancing the flex gap first, and the other technique initially balances the knee in extension. On the other hand, bony landmarks such as the transepicondylar axis and the posterior condylar axis are used to set femoral component rotation when using a measured resection technique. Bone cuts are initially made independent of soft tissue tension.

Regardless of the philosophy used, gap balancing, or measured resection or a combination of both, in general we can say that the ligament balance of valgus deformity depends on the release of tense lateral structures and the tensioning of attenuated medial structures. Unfortunately, many authors have described several sequences for the serial release of these structures, and there is still no consensus on the best technique.

#### *4.2.1 Release of lateral structures*

Ligaments can be released through pie-crusting, subperiosteal release, transverse section, or osteotomy. Unfortunately, there is no consensus among the authors on a sequence for carrying out the releases. The releases should be performed in full extension, by using spreaders to check the tension of the medial and lateral compartments. After each release, the surgeon should evaluate the alignment and the stability of the knee, in order to achieve a symmetrical rectangular extension and flexion gaps [6].

Krackow et al. [5] advocate the release of the ilio tibial band (ITB), followed by the lateral colateral ligament (LCL), next by the posterolateral corner structures (PLC) and the gastrocnemius muscle lateral head (LHG).

Buechel [13] presented a sequential three-step lateral release, which included elevation: (1) the ITB from Gerdy's tubercle; (2) the LCL and popliteous tendon (POP); and (3) the entire periosteum of the fibular head.

Ranawat et al. [1] described a stepwise technique in which the first structure to be released is the posterior cruciate ligament (PCL). When necessary, the ITB and the LCL are released with multiple stab incisions, the so-called "pie-crusting" technique. The POP is normally preserved.

Favorito et al. [14] proposed that LCL is the first structure to be released. The next sequential release follows the POP (an important structure for rotational and valgus stability in flexion), the PLC, the femoral insertion of the LHG, and finally, the ITB.

Whiteside [15] described a release sequence based on the tension of ligaments in flexion and extension: For tight knees both in flexion and extension, the LCL and POP tendon are released. For those knees, tightness remains in extension and only ITB is released. Posterior capsular release is performed only when necessary for persistent lateral tightness.

An alternative technique for lateral structure release was described by Brilhault et al. [16]. A sliding osteotomy of the lateral epicondyle contains LCL and POP insertions.
