A lateral approach defect closure technique with deep fascia flap for valgus knee TKA

From 2009 to 2012, we performed nine valgus knee TKA surgeries through a lateral parapatellar approach in eight patients. There was one male patient and seven female patients with the average 66.6 years old (57–76 years). According to the knee valgus angle (femoral-tibial angle), there were four mild valgus knees, three moderate valgus knees, and two severe valgus knees. There were three rheumatoid arthritis valgus knees and six osteoarthritis valgus knees. The valgus deformity could be reduced in four mild valgus knees but could not be reduced (fixed valgus knee deformity) in three moderate valgus knees and two severe valgus knees.

A midline skin incision of the knee was performed instead of a lateral one in order not to interfere with the medial dislocation of the patella and preserve a midline access for future revision surgeries, whenever necessary. The staggeredness between midline skin incision and lateral parapatellar capsular approach is also good for preventing infection (Fig. 1).

Lateral parapatellar approach is performed as follows. The quadriceps tendon is clearly defined and incised longitudinally in the midline, starting 5 cm above the superior pole of the patella then curving along the lateral border of the patella down to the lateral side of tibial tubercle (Fig. 2). Any adhesions in suprapatellar pouch and medial/lateral gutters are excised. The incision in the quadriceps tendon is extended proximally beneath the subcutaneous fat tissue and skin for 2 to 3 cm with scissors in order to release the contracted vastus lateralis completely from the patella and quadriceps tendon. The patella is then displaced medially without eversion with a thin Homann retractor to keep it away from the medial femoral condyle, which gives exposure for the femoral bone resection (Fig 3). With lateral parapatellar approach, the valgus knee deformity would be corrected through release of lateral contracted soft tissue with the following sequence: (1) pie-crusting of iliotibial tract above the joint line which should be performed before incision of lateral capsular approach, (2) subperiosteal release of iliotibial tract insertion from Gerdy tubercle, (3) release of the posterolateral capsule around lateral tibial plateau, (4) subperiosteal release of lateral collateral ligament and popliteal tendon from the lateral femoral condyle working proximally, and (5) release of the lateral head of gastronemius muscle and the biceps tendon [4].

The aforementioned soft tissue balance should be performed in three stages. The first balance stage should be pie-crusting of iliotibial tract above joint line, elevating the iliotibial tract subperiosteally from Gerdy tubercle, and release of posterolateral capsule around lateral tibial plateau. If there is a correctable valgus deformity after first balance stage, the subperiosteal release of the posterolateral capsule should not continue to the anterior half of the lateral tibial plateau. The next two balance stages should not be performed until the knee prosthesis trial test is completed [2]. After the knee prosthesis trial, soft tissue balance should be checked again. If there is still valgus deformity especially in knee flexion, soft tissue balance should proceed to stage II as described by Buechel, including subperiosteal release of popliteal tendon and lateral collateral ligament from the lateral femoral condyle [3]. After sequential release of these tissues, it is very important to keep checking the balance both in knee extension and flexion. A stage III release, including release of lateral head of gastrocnemius muscle and biceps tendon release, has been described by Buchel, but has never been performed during our valgus knee TKA surgery.

The rotational alignment of the tibial plateau prosthesis should be determined according to the tibial prosthesis trial position in knee extension [1], because knee stability in extension is very important during walking on level. If the patella is to be resurfaced, it should be performed with the knee in extension because the patella will be everted easily. During cementing of the femoral and tibial components, the patella should be displaced medially to give adequate exposure.

After knee prosthesis replacement, the lateral capsular incision should be sutured with the knee in 30° flexion. The lateral cuff of the quadriceps tendon with proximal vastus lateralis should be sutured to the central quadriceps tendon under gentle tension, to effectively reposition the vastus lateralis proximally. The distal portion of lateral capsular incision is also sutured until the tension is too high to be sutured directly. So, there is often a defect in the midportion of the lateral parapatellar capsular incision.

Here, we introduce a new surgical technique to address the midportion defect of the lateral parapatellar capsular incision. According to the defect size at the midportion of the lateral parapatellar capsular incision, a deep fascia flap with about 2 mm thickness is dissected over the patella/quadriceps tendon/patellar tendon. Then, the deep fascia flap is flipped laterally with pedicle attachment preserved at the fascia flap base to cover the lateral capsular incision defect. The flipped deep fascia flap is sutured to the lateral capsule using 2–0 running absorbable suture. Then, the deep fascia flap pedicle is also sutured at the flap base for reinforcing to prevent rupture during postoperative knee flexion. After completing the suture, the lateral capsular defect should be covered with this deep fascia flap. The anti-tension capacity of the deep fascia flap is measured through full knee extension to 120° knee flexion, and should show good anti-tension capacity during full flexion (Fig. 4).