The patient is placed in the supine position and carefully prepped and draped. I fold a cuff into the sterile drape, under the thigh, so that the drapes will not be disturbed or restrictive when I move or flex the knee (Fig. 5-1A,B). I use an anterior medial incision of approximately 12 to 15 cm. It may begin 3 cm above the patella and end 1 cm below the top of the tibial tubercle (Fig. 5-2). The length of the incision is not important as long as it allows adequate exposure to perform the procedure efficiently and safely. Proximally, the margins of the quadriceps tendon are identified with a right angle retractor slid on the quadriceps tendon and beneath Scarpa’s fascia. I make a median parapatellar incision, which is extensile and can be extended, if necessary, in obese, muscular, or stiff joints. (Fig. 5-3). The knee joint is entered and briefly inspected. Some of the fat pad is removed (Fig. 5-4). The surgeon enters the bursa below the retroperitoneal fat pad and incises the anterior lateral capsule (Fig. 5-5). Medially, the soft tissue sleeve is dissected from the proximal medial tibial metaphysic, on top of the periosteum, and follows within the natural plane of the pes anserinus bursa (Fig. 5-6). This dissection is extended back to the posterior corner of the knee. The only structure that requires sharp dissection in this plane is the meniscal tibial ligament. The edge of the medial soft tissue sleeve is kept intact so that a watertight closure can be obtained at the end of surgery. With this approach into the knee, the blood supply in the periosteum on the anterior and medial side of the tibia is essentially left undisturbed.

The knee is extended, and the patella is everted in extension. With a Lahey clamp holding the eversion, and a Homan retractor stabilizing the patella, the retropatellar osteotomy is carried out (Figs. 5-7A,B, 5-8, and 5-9).

The knee is then flexed, and the surgeon excises the anterior cruciate ligament. If the surgeon is preserving the posterior cruciate ligament (PCL), it should be left undisturbed. I release the lateral meniscus and place a Homan retractor under the meniscus retracting the meniscus and extensor mechanism laterally. The patella is not everted, as it is not necessary for good exposure of the knee. With flexion, external rotation, and anterior displacement, the tibia can be subluxed forward, and excellent exposure of the tibial plateau and femoral condyles can be obtained (Fig. 5-10). If there is too much tension on the skin, I lengthen the incision as needed.

In the total knee procedure, the surgeon uses the same five bone cuts whether the prosthesis is cemented in place, fixed with porous ingrowth, and/or if the PCL is saved or preserved (Fig. 10B). The only difference is the sixth step for removing the intercondylar notch for posterior cruciate-substituting prosthesis. These essential bone cuts are made regardless of the amount of bone loss, ligament imbalance, or osteophytes present around the joint. For a routine TKA, I perform a measured resection technique in which the osteotomies are calculated to reproduce the joint lines with the thickness of the metal prosthesis. I will make the bone cuts, remove all osteophytes, and then evaluate and compensate for any soft tissue imbalance. In general, after the osteophytes are removed and normal anatomic boundaries have been re-established, no specific releases or additional balancing is necessary. For knees with severe deformities, or when soft tissue imbalances are a major problem, however, only then soft tissue releases are considered (see Chapter 7).

The five essential cuts for any TKA are as follows (Fig. 5-10B):

The retroperitoneal osteotomy is completed early in the case with the knee in extension (Fig. 5-7). This debulks the patella and allows it to be subluxed without eversion and reduces the tension on the tibial tubercle. It almost eliminates the risk of patellar tendon peel from the tubercle. I try to reproduce the native thickness of the patella with 10 to 15 mm of patella remaining. A caliper can be used
to determine the thickness of the patella before and after the osteotomy (Fig. 5-8), however, with experience, this becomes less necessary. There are clamps that can be used to guide in this retroperitoneal osteotomy. Again, with experience, the guides become less necessary. The synovial/fat soft tissue mass at the superior pole of the patella should be excised to avoid a postoperative “clunk syndrome” (Fig. 5-7A). After the osteotomy has been completed, drill holes can be placed into the retroperitoneal surface to accept the patellar button (Fig. 5-9). I generally use a patellar button in my total knee replacements.

The femoral and tibial osteotomies are independent of each other, so either may be performed first. I recommend that the tibia be osteotomized first, however, to accurately determine the femoral rotation and establish equal medial and lateral gaps in flexion by tension. Rarely, if the knee is tight or if good exposure is difficult to obtain, will I osteotomize the femoral condyles first.