**4.2. Valgus deformity**

**4. Management of deformities**

**Figure 11.** Kinematics axis of the knee (from Howell's studies with authorization).

During the arthritic course, there are expected modifications in native alignment and ligament function. Loss of cartilage can create an asymmetrical compartment balance, leading to contracture of soft tissues on the concave side and contralateral loosening on the convex side. As the deformity progresses, these modifications tend to establish into fixed deformities. In varus knees, contraction of medial side involves medial collateral ligament and the whole medial periosteal sleeve, including hamstrings, posteromedial capsule, and PCL. As the deformity progresses, the lateral compartment becomes insufficient, causing abnormal

Instability of the arthritic knee may be viewed as symmetrical or asymmetrical. Symmetrical instability is seen during early arthritis, when there is erosion of cartilage or bone without associated adaptive soft tissue changes. During physical examination, the deformity can be corrected under active reciprocal stress on physical examination. This kind of instability is

As the deformity progresses it tends to turn into an asymmetrical instability, which is not corrected by active reciprocal stress during physical examination. This kind of fixed deformity occurs when cartilage and bone loss lead to adaptive ligamentous changes. In order to correct this kind of deformity, ligamentous release is mandatory, turning a trapezoidal gap into a rectangular gap. In asymmetrical instabilities, the bone cuts alone are not sufficient to

Instead of only releasing ligaments from the contracted concave side someone could advocate to advance ligament complexes on the convex side, especially when the opposing ligaments are stretched to the point of being incompetent. These authors do not favor ligament advances or reconstructions on the convex side since the functional outcomes have not been acceptable in most series. In such cases, the authors advise considering a more constrained knee design (**Figure 12**).

easily corrected during surgery without needing extensive ligament releasing.

**4.1. Varus deformity**

14 Primary Total Knee Arthroplasty

lateral opening and instability.

accomplish articular balance.

In the valgus knee, the lateral structures contract, while the medial soft tissues stretch. Differing from varus knees, where the bone erosion occurs more in the tibial bone, in valgus knees most of the bone deformity comes from the femoral side (**Figure 13**). As the deformity progresses it tends to involve the tibial bone and cartilage as well.

Lateral soft tissue structures, including the lateral collateral ligament (LCL), iliotibial band (ITB), and the lateral capsule, contract, while the medial soft tissues stretch. When this

**Figure 13.** Most part of the bone wear occurs on lateral femoral condyle, although it could involve tibial bone as well.

imbalance becomes permanent it may result in medial thrust during gait. In both varus and valgus deformities, it could be associated with flexion contractures (**Figure 14**).

After bone cuts, posterior capsule can be released. For those who agree with principles of KA, the preservation of PCL is desirable. That could hamper flexion contracture correction but

Planning Primary Total Knee Arthroplasties http://dx.doi.org/10.5772/intechopen.72775 17

Small contractures can be reduced by removal of posterior osteophytes, but posterior capsulotomy is necessary for moderate and severe flexion contractures. These authors advise the

Stiff knees are a challenging situation even for the most experienced knee surgeons. Typically, the techniques described for difficult exposures are necessary. Sometimes, everting the patella is not possible, leading the surgeon only to subluxate it laterally. The soft tissue releases applied for varus and valgus techniques are used and extensive soft tissue release is usually

Recurvatum is usually mild and it's treated with under-resection of the distal femoral and proximal tibia. However, in patients with neuromuscular diseases, such as poliomyelitis and Ehler-Danlos, even under-resection and use of thicker components are insufficient to correct recurvatum. For these extreme conditions, the authors recommend the use of constrained

As osteoarthritis advances, bone defects can distort the natural anatomy of the knee and cause

**Figure 15.** Peripheral medial bone defect on medial tibial plateau. One must avoid over-resection of the medial tibial

plateau as it could fracture proximal fibula. Cancellous bone is insufficient to support the tibial implant.

changing the slope orientation could in part correct that kind of deformity.

resection of PCL when the mechanical alignment theory is chosen.

**4.4. Extension contracture**

**4.5. Genu recurvatum**

prosthesis or hinged implants.

**5. Management of bone defects**

to difficult alignment and implant set.

necessary.

Krackow has classified valgus deformities into three stages: type I involves lateral femoral bone loss, lateral soft tissue contracture, and intact medial soft tissues; type II adds medial lengthened soft tissues; and type III represents alteration of the proximal tibial joint line, that usually happens as a result of a high tibial osteotomy. As the ITB gets contracted, external rotation is often observed.

Insall and colleagues traditionally recommended releasing lateral capsule, LCL, arcuate ligament, popliteus tendon, lateral femoral periosteum, distal ITB, and the adjacent lateral intermuscular septum from their bone attachments. Some degree of lateral laxity after an extensive lateral release was typically well tolerated. Although extensive release generally corrects the deformity, posterolateral flexion instability may still occur postoperatively. These authors do not favor extensive releasing from bone attachments. Instead, the authors recommend progressively intra-articular liberations ahead of the popliteus tendon, using the pie-crusting technique.

#### **4.3. Flexion contracture**

As the degenerative disease progresses, it involves posterior capsule, PCL, and musculotendinous at the posterior aspect of the knee. Bone erosion of posterior femoral condyles and osteophytes may contribute to flexion contracture on arthritis. Despite the fact that some authors understand that postoperative residual flexion contractures are well tolerated, these authors do not favor residual flexion contractures, since residual deformities tend to worsen with time.

**Figure 14.** Valgus deformity. Contraction of the lateral compartment causes bone erosion and an imbalance of natural kinematics.

After bone cuts, posterior capsule can be released. For those who agree with principles of KA, the preservation of PCL is desirable. That could hamper flexion contracture correction but changing the slope orientation could in part correct that kind of deformity.

Small contractures can be reduced by removal of posterior osteophytes, but posterior capsulotomy is necessary for moderate and severe flexion contractures. These authors advise the resection of PCL when the mechanical alignment theory is chosen.

#### **4.4. Extension contracture**

imbalance becomes permanent it may result in medial thrust during gait. In both varus and

Krackow has classified valgus deformities into three stages: type I involves lateral femoral bone loss, lateral soft tissue contracture, and intact medial soft tissues; type II adds medial lengthened soft tissues; and type III represents alteration of the proximal tibial joint line, that usually happens as a result of a high tibial osteotomy. As the ITB gets contracted, external

Insall and colleagues traditionally recommended releasing lateral capsule, LCL, arcuate ligament, popliteus tendon, lateral femoral periosteum, distal ITB, and the adjacent lateral intermuscular septum from their bone attachments. Some degree of lateral laxity after an extensive lateral release was typically well tolerated. Although extensive release generally corrects the deformity, posterolateral flexion instability may still occur postoperatively. These authors do not favor extensive releasing from bone attachments. Instead, the authors recommend progressively intra-articular liberations ahead of the popliteus tendon, using the pie-crusting

As the degenerative disease progresses, it involves posterior capsule, PCL, and musculotendinous at the posterior aspect of the knee. Bone erosion of posterior femoral condyles and osteophytes may contribute to flexion contracture on arthritis. Despite the fact that some authors understand that postoperative residual flexion contractures are well tolerated, these authors do not favor residual flexion contractures, since residual deformities tend to worsen

**Figure 14.** Valgus deformity. Contraction of the lateral compartment causes bone erosion and an imbalance of natural

valgus deformities, it could be associated with flexion contractures (**Figure 14**).

rotation is often observed.

16 Primary Total Knee Arthroplasty

**4.3. Flexion contracture**

technique.

with time.

kinematics.

Stiff knees are a challenging situation even for the most experienced knee surgeons. Typically, the techniques described for difficult exposures are necessary. Sometimes, everting the patella is not possible, leading the surgeon only to subluxate it laterally. The soft tissue releases applied for varus and valgus techniques are used and extensive soft tissue release is usually necessary.

#### **4.5. Genu recurvatum**

Recurvatum is usually mild and it's treated with under-resection of the distal femoral and proximal tibia. However, in patients with neuromuscular diseases, such as poliomyelitis and Ehler-Danlos, even under-resection and use of thicker components are insufficient to correct recurvatum. For these extreme conditions, the authors recommend the use of constrained prosthesis or hinged implants.
