A detailed medical history should be obtained to elucidate any details of previous surgeries on the knee with special attention paid to any wound healing problems, wound drainage, or extended use of postoperative antibiotics. The surgeon should document the location of the most recently used incision and any history of wound healing problems with use of that incision. Discoloration of previous wound edges with hemosiderin may shed light on previous wound healing complications. A history of knee stiffness or loss of knee motion is important to determine as well as inquiring when the stiffness began and what methods of management, if any, were employed to restore motion.

Knee range of motion, flexion contractures, and extensor lag should all be measured and documented carefully. A knee with extensor lag may suggest extensor mechanism dysfunction and is associated with poor long-term results. A stiff knee is at risk for patellar tendon rupture at the time of surgery. Patellar mobility should be examined with special regard to limited motion in the coronal plane as this may indicate scarring of the extensor mechanism. Location of the patella is also important, as the finding of patella baja will make subluxation or dislocation of the patella more difficult at the time of surgery and may necessitate further exposure options discussed in detail later.

If there is concern about the pliability of the soft tissue envelope that may result in a tenuous wound closure at the conclusion of the case, a preoperative plastic surgery consultation should be considered. Although tissue expansion or use of a sham incision are generally carried out by plastic surgeons, many orthopaedic surgeons prefer to do these procedures themselves as they have the best understanding of their requirements relative to the skin and soft tissues for wound closure. In order to avoid last minute decision making in the operating room, details of the planned surgical approach should be documented in the preoperative notes so the surgeon can implement this plan on the day of surgery.

Preoperative radiographs are useful in determining if there is a bony restriction to knee flexion. In most instances, standard anterior-posterior (AP) and lateral radiographs provide satisfactory visualization of the knee components. The lateral radiograph is particularly helpful in identifying posterior osteophytes or heterotopic bone that may block flexion and in determining the location of the patella. An Insall-Salvati ratio of less than one indicates a shortened patellar tendon that will make patellar displacement difficult. The AP radiograph is useful in identifying capsular ossification, periosteal new bone formation, and component subsidence. Full-limb standing radiographs of the extremity may be required to evaluate the quality of fixation and the location of the femoral and tibial stems. The surgeon should pay particular attention to the fixation of the tibial stem. In some circumstances, a tibial tubercle osteotomy is necessary to access a well-fixed tibial stem. Given a well-fixed femoral stem, it may be necessary to breach the anterior femoral cortex to access the stem-cement interface.

If during the preoperative evaluation the patient is noted to have flexion limited to 90° or less, a modification to the routine surgical approach is warranted. This is carried out in a logical, systematic way to enhance visualization while doing so in a safe and reasonable manner.

Whenever the knee lacks 90° of flexion, the extensor mechanism is at risk of avulsion or rupture when vigorous efforts are made to retract the patella to achieve exposure. If the extensor mechanism is not relaxed, avulsion of the patellar tendon at its insertion to the tibial tubercle may occur. This is the weakest point of the structure, as the surgical approach alone devascularizes a majority of the tendon [7]. Avulsion or rupture of the patellar tendon that occurs intraoperatively is a difficult complication to manage. Direct suture or staple repair has a high rate of failure and has resulted in high rates of deep infection, tendon re-rupture, and extensor lag [8, 9]. In the setting of poor tissue quality, augmented repair with a hamstring autograft requires prolonged postoperative knee immobilization [10]. Although the extensor mechanism can be stabilized, immobilization of an already stiff knee is likely to result in less than satisfactory postoperative knee motion.

Relaxing tension from the extensor mechanism should not be an afterthought performed only after struggling with a difficult surgical exposure. Methods of relaxing tension include quadriceps snip, quadriceps (patellar) turn down, and a tibial tubercle osteotomy. Each of the three options has indications based upon patellar location and where along the extensor mechanism the primary location of immobility is. Thus, the decision of which adjunct procedure to use should be thoroughly considered in the preoperative planning and carried out strategically during the surgical exposure. When patella baja is present, a distal release with a tibial tubercle osteotomy should be considered. In severe patella baja, no amount of proximal release may be sufficient to translate the patella laterally. In addition, the osteotomized tubercle can be translated as much as 2 cm proximally, which will improve both range of motion and patellar impingement against the tibial component. When the patella is in a normal or elevated position, the scarring that limits knee motion is most severe in the quadriceps tendon. A proximal release provides direct access to the scarred area and is more likely to aid in the recovery of knee motion. In a study by Barrack et al., patients who underwent a full quadriceps turndown were compared with a group of patients managed with tibial tubercle osteotomies [11]. The group of patients who had quadriceps turndown had a significantly greater increase in the arc of motion.