Valgus Knee Deformity

Kapil Mehrotra

Mark W. Pagnano

Key Concepts

Mild to moderate valgus knee deformities often can be corrected with soft tissue balancing by selectively releasing tight structures on the lateral side.
A very pragmatic approach to lateral releases is the inside-out multiple-puncture or “pie-crust” release. This is further simplified if the surgeon tensions the lateral side in extension, palpates the lateral structures to identify the tightest, and sequentially punctures the tightest remaining structure with a #15 blade until adequately released.
Severe valgus deformities result in stretching of the medial collateral ligament (MCL) and may require a constrained knee prosthesis.
A tiny subgroup of patients with large, fixed deformity may require a lateral epicondyle wafer osteotomy.
In contemporary practice, about 95% of valgus knees are amenable to the multiple-puncture technique; 5% of patients, particularly the elderly, are better served with deliberate undercorrection and use of a constrained knee; and a rare subset of younger patients with large, fixed deformity may require epicondylar osteotomy.

Sterile Instruments and Implants

Instruments

Routine knee retractors (e.g., bent Hohmann retractors, Z retractors, Chandler retractors, Pickle fork)
Large and small oscillating saw
Osteotome (3/4 inches curved, broad straight)
Lamina spreaders
Spacer blocks and alignment rods
Patella caliper
Cobb elevator

Implants

Cemented femoral, tibial, and patellar components (with instrumentation)
Constrained condylar implant design should be available for fixed deformities

Position

Supine
Thigh tourniquet

Surgical Approaches

Anterior midline incision starting 3 to 5 cm above the proximal pole of the patella to the distal end of the tibial tubercle.
Median parapatellar arthrotomy or a midvastus arthrotomy if correctable deformity.
Lateral parapatellar arthrotomy is not used in our practice but is described by others for use in the valgus knee.

Preoperative Planning

Physical Examination

Inspect the skin for any previous incisions. If less than 5 cm from the planned incision, it should typically be incorporated into the total knee incision.
Evaluate overall limb alignment in both the coronal and sagittal planes:
- Assess if the valgus deformity is correctable.
- Look for any recurvatum or flexion contracture.
- Determine the integrity of the posterior cruciate ligament and the MCL.
- Patients at highest risk for a postoperative peroneal nerve injury are those with substantial combined valgus deformity and flexion contracture.

Radiographs

Measure the tibiofemoral angle (angle created between the anatomic axis of the tibia and femur) to determine the severity of the valgus deformity (Figure 54.1).
In the valgus knee a weight-bearing posteroanterior flexed-knee radiograph will often reveal more substantial arthritis than the standard anteroposterior radiograph (Figure 54.2A and B).

Look for medial joint space widening, which may indicate MCL laxity.

Figure 54.1 ▪ A full-length standing radiograph that includes the hip-knee-ankle is useful in assessing the overall limb alignment and the presence or absence of extra-articular deformity.

Figure 54.2 ▪ A, A typical standing anteroposterior radiograph often underestimates the extent of lateral compartment degenerative arthritis. B, A weight-bearing posteroanterior view of the same knee reveals advanced lateral compartment degenerative arthritis with grade 4 bone-on-bone changes laterally.

Evaluate for lateral femoral condyle or lateral tibial plateau bone deficiencies.
Many patients with valgus deformity will also have substantial concomitant patellofemoral degenerative arthritis visible on a merchant or skyline radiograph.
Identify posterior osteophytes on the lateral radiograph.
Template femoral and tibial component size.
Consider the need for augments, stems, or constrained implants.

Bone, Implant, and Soft Tissue Techniques

Exposure

Median parapatellar approach (see Section III B, Chapter 1 for details of the surgical exposure).
Limited subperiosteal elevation of the medial soft tissue should be performed. Extensive medial release will contribute to the medial-sided laxity and will add to the complexity of soft tissue balancing.

Bone Cuts