Postoperative: Surgical Complications (Stiffness, Graft Rupture)

Preoperative Consideration

The goal of anterior cruciate ligament reconstruction (ACLR) is to stabilize a loose knee so the patient can return to desired activities, often involving pivoting and cutting. Additionally, many patients desire to return to competitive sports. ACLR is performed on a loose knee that either demonstrates or is at risk for instability. A knee that buckles or gives way does not allow the athlete to comfortably or safely return to athletic activities. However, a stiff knee is equally, and often more significantly, disabling than a loose knee. Postoperative stiffness after ACLR is an uncommon but difficult problem. Currently, arthrofibrosis and the best treatment options are poorly defined. Given the lack of consensus regarding the definition of arthrofibrosis, it is difficult to estimate the true incidence. One recent study noted an incidence of 1.7% of patients receiving intervention after ACLR. Female patients were 2.5 times more likely to have arthrofibrosis than males. Arthrofibrosis has both primary and secondary causes. Primary arthrofibrosis, which accounts for less than 5% of arthrofibrosis cases, is caused simply by an exaggerated inflammatory response to injury or surgical insult. Treatment for these cases is clearly nonsurgical. Paulos et al. described infrapatellar contracture syndrome after knee surgery as a combination of loss of flexion and extension and patellar entrapment. They proposed a primary mechanism of an exaggerated pathologic hyperplasia of the anterior soft tissues or secondary to immobilization postoperatively. Secondary causes of arthrofibrosis are directly under the surgeon’s or patient’s control. Many of these cases may be improved by surgical intervention. Stiff knees are frequently persistently painful and do not allow for a functional range of motion (ROM) acceptable to an athlete. With a more significant loss of motion, not only will a patient’s athletic performance suffer, but the patient may have difficulty with activities of daily living. With a significant flexion contracture, a patient will have gait abnormalities and persistent limp. Thus it is important to make certain that a successful ACLR adequately stabilizes the knee, but does not convert it to a knee that is overly stiff. This requires meticulous attention to detail. It is important to consider factors that lead to postoperative stiffness preoperatively, intraoperatively, and postoperatively.

To minimize the risk of postoperative stiffness, it is important to minimize preoperative risk factors. Patients often present to the training room or the office with an acute anterior cruciate ligament (ACL) tear with an inflamed knee, hemarthrosis, and loss of ROM. During the preoperative visit, the timing of surgery must be discussed, and will be dependent on several factors including swelling, ROM, and associated injuries. Historically, it was felt that ACLR surgery should be delayed several weeks from the injury to avoid arthrofibrosis and a suboptimal outcome. Additional studies have substantiated this claim. More recently several studies have supported the safety of early reconstruction. In a prospective randomized clinical trial, Bottani et al. compared early (within 21 days) versus delayed (>6 weeks) ACLRs using hamstring tendon autografts. They concluded that early ACLRs do not result in loss of motion or suboptimal clinical results as long as the postoperative protocol includes early ROM, especially extension. Also, looking at autogenous hamstring reconstructions, Eriksson et al. proposed that acute ACLR within 8 days of injury is safe and does not adversely affect ROM relative to delayed surgery. Furthermore, the patients with acute reconstruction had significantly less hypotrophy in the early phase of rehabilitation, and no difference was found in the other clinical assessments. In an even more aggressive approach, Herbst et al. advocated for acute ACLR within 48 hours in highly active patients or competitive athletes. They compared ACLR within 48 hours after injury versus waiting for the inflammatory-free interval and concluded that the inflammatory state of knee is critical in determining an appropriate time for surgery, as opposed to an absolute temporal cutoff.

With an increasing number of concomitant injuries, it is critical to be diligent in selecting an optimal time for surgery. Identifying an ideal time of surgery is more straightforward with an isolated ACL tear, but with associated meniscal, articular cartilage, or other ligament tears a heightened awareness is critical.

With acute isolated ACL tears, typically the patient is permitted to bear weight as tolerated preoperatively in a hinged knee sleeve. Given that patients typically have hemarthrosis and diminished ROM, they are encouraged to ice their knees and are asked to attend “prehabilitation” or “prehab.” The goal of prehab is for the physical therapist to assist the athlete with edema control and ROM exercises. This uniformly includes a home exercise program component. The patient is ready for surgery when swelling is minimal and nearly full ROM is obtained. An acceptable preoperative ROM includes full extension and approximately 120 degrees of flexion. It is critically important that the patient has normal patellofemoral motion equal to the uninvolved knee before surgery, particularly if a patellar tendon autograft is employed. If the patient fails to regain normal passive patellar motion, including glides and tilts, then patellofemoral pain will likely be a lifelong issue. Typically, if these parameters are achieved, the patient can ambulate with minimal to no limp. The authors do not recommend reconstructing the ACL in the face of a significant ROM deficit, particularly extension. Some patients may require up to 4 to 6 months to regain their normal motion after injury. Clearly this patient may have “primary arthrofibrosis.” Waiting for the entire knee inflammatory process to quiet down is of paramount importance. This is also an ideal time for the patient to develop a relationship with a physical therapist, which will assist with postoperative recovery.

Because associated injuries become additive, the situation becomes more complex. Meniscal injuries can be anticipated based on the preoperative magnetic resonance imaging (MRI). As secondary stabilizers of the knee, it is important to save as much meniscal tissue as possible, especially given injury to one or more of the primary stabilizers. The importance of the meniscus in ACLR has been well documented. ^, A substantial repair of one or both menisci will often necessitate partial weight bearing and will increase the likelihood of postoperative stiffness. If meniscal repair is anticipated, it is important that the surgeon is even more diligent in mandating that prehabilitation goals are met before surgery. A special circumstance relative to meniscal surgery is the bucket handle tear or any tear with a significantly displaced fragment that acts as a mechanical block. The patient will never achieve full preoperative motion, most notably extension, without alleviation of this mechanical block. Furthermore, bucket handle tears frequently involve a large portion of the meniscus, and therefore are frequently repairable. If the patient and therapist can get the acutely inflamed ACL-deficient knee calmed down in a reasonable period of time, the ACLR and meniscal surgeries can be performed acutely in a single stage. If this is not possible, then staged surgery is recommended, with meniscal repair as the first stage, and ACLR performed in a delayed fashion once full motion is obtained. Note that there is risk of significantly delaying surgery. Chhadia et al. have demonstrated a strong association of increased risk of medial meniscal injury and decreased repair rate, as well as increased risk of cartilage injury, with increasing time to surgery.

Whereas a detailed discussion of the multiligamentous knee injury is beyond the scope of this chapter, a combined ACL tear and associated medial collateral ligament (MCL) injury is commonly encountered. It is paramount to have an early discussion with the patient regarding the risk for both persistent instability and postoperative stiffness. Associated ACLR and MCL repair will put the patient at substantial risk for stiffness. This underscores the importance of compliance with both preoperative and postoperative physical therapy.