In most revision cases, a medial parapatellar arthrotomy is done. However, if a previous lateral parapatellar arthrotomy was used at primary TKR, it should be used for revision TKR to decrease the risk of patellar osteonecrosis.

During revision TKR, exposure may be facilitated by several additional steps, which are usually not routinely performed in a primary TKR. Following medial arthrotomy, wide resection of the intra-articular scar is performed by clearing any fibrous adhesions in the suprapatellar pouch and lateral and medial gutters. The proximal tibia should be exposed medially by subperiosteal dissection of the medial structures, with care taken to avoid complete release of the superficial medial collateral ligament; otherwise a more constrained prosthesis is needed.

Adhesions over the proximal aspect of the tibia, deep and proximal to the patellar tendon should be released. At this point, the surgeon has to decide if patellar eversion can be safely performed. If this is not the case, the patella can be laterally subluxated to give adequate exposure to facilitate TKR component removal. When components have been removed, tension in the quadriceps mechanism is reduced, leading to probably easier patellar eversion.

One must be careful not to avulse the patella tendon distally. Patellar tendon avulsion might occur when excessive tension is applied to the patellar tendon insertion. Thus, the tension applied to the patellar tendon insertion site at the tibial tubercle should be continuously monitored. The integrity of the patellar tendon insertion must be protected under all circumstances. A protective pin can be placed in the tibial tubercle to prevent avulsion, but it does not guarantee that the devastating complication of patellar tendon avulsion will not occur. Aiming for stress prevention to the patellar tendon insertion, Fehring et al. [5] described the “patella inversion method” for exposure in revision TKR. Hereby, a medial parapatellar arthrotomy is performed without eversion of the patella. In order to gain a wider exposure, an early lateral retinacular release is added. Furthermore, the tibia is progressively externally rotated and dissection is made below the periosteum to elevate the medial ligamentous sleeve until exposure is large enough to remove the primary TKR components. If necessary, dissection continues around the proximal tibia at the joint line level until the insertion of the posterior cruciate ligament. Stress on the patellar tendon insertion is released by external rotation of the proximal tibia. Once the components have been removed, the patella can be easily and safely everted to work on it. Fehring et al. reported that the patella inversion method was effective in 95 % of revision TKR [5].

If the exposure is still difficult, a number of other more invasive exposures can be used to facilitate the exposure and protect the extensor mechanism. These can be divided into proximal and distal exposure techniques. Proximal exposures include the rectus snip, the V-Y quadricepsplasty, the medial epicondylar osteotomy, and the femoral peel technique. The osteotomy of the tibial tubercle is the most commonly used distal exposure technique.

The quadriceps snip [6] is an excellent surgical maneuver to facilitate exposure of revision TKR without high risk of extensor lag noted in quadriceps turndown procedures (Fig. 43.4). The classic quadriceps snip is an oblique superior-lateral extension to the standard medial parapatellar arthrotomy. It is made at an angle of 45°. Care should be taken to maintain a significant part of the lateral vastus muscle, including the lateral retinaculum. The medial vastus muscle and the adjacent portion of the rectus femoris tendon should remain untouched. Performing an oblique snip as opposed to a transverse snip shows the advantage that a side-to-side suturing is stronger than end-to-end suturing. Performing a transverse quadriceps snip could weaken the tendon and increase the risk of extensor tendon tear. Finally, the quadriceps snip is closed in the routine fashion of a medial parapatellar arthrotomy. If a wider exposure is necessary, it can also be used in combination with a tibial tubercle osteotomy. The results after quadriceps snip extension are equivalent to those of patients undergoing a standard medial parapatellar arthrotomy [7]. There is no need for any change in the postoperative rehabilitation. Only a few complications have been reported. In a study comparing a quadriceps snip with the standard medial parapatellar approach, no significant difference was observed in terms of outcome, and no associated complications were reported [8]. The quadriceps snip has minimal associated complications and should be the first technique employed when a more invasive exposure is required in revision TKR.