Anterior cruciate ligament (ACL) ruptures are a common and potentially devastating injury in the athletic and active population. The incidence of ACL tears is rising in the United States, with recent estimates of 43.5 to 68.6 per 100,000 person-years. , Peak incidences occur in males aged 19 to 25 years (241 per 100,000) and females aged 14 to 18 years (227 per 100,000). , These injuries can be psychologically and physically devastating to patients who wish to return to athletics or an active lifestyle. ACL reconstruction is highly successful in returning patients to activities, , , but return to preinjury activity level is more challenging. , , , Many factors, including age, body mass index, sex, and concomitant injury, cannot be modified following an ACL injury. The purpose of this chapter is to discuss knee optimization before undergoing ACL reconstruction to provide the best foundation for postoperative outcomes.
An ACL tear is a highly traumatic event that typically results in large inflammatory response and hemarthrosis with associated soft-tissue swelling and effusion. The inflammation then contributes to generalized irritability of the knee that may result in loss of range of motion (ROM), influence the time of surgery, and increase the risk of postoperative complications if normal knee motion and full weight bearing are not obtained before surgery.
Timing of Surgical Intervention
Inappropriate timing of surgical intervention may contribute to the development of arthrofibrosis. , , Although many studies have reported on the timing of surgical intervention and its relationship to arthrofibrosis, currently most surgeons believe that motion restoration, quadriceps recovery, and resolution of posttraumatic edema and effusion are the critical determinants that can preoperatively impact the likelihood of arthrofibrosis development. An initial study demonstrated that ACL reconstruction within one week of injury was significantly associated with postoperative arthrofibrosis compared with reconstruction more than 21 days after injury. Several additional studies have also confirmed that early reconstruction (<7 days from injury) places patients at increased risk for postoperative complications compared with delayed reconstruction. , ,
Mayr and colleagues further showed that the degree of residual swelling, effusion, and local hyperemia was strongly and significantly associated with postoperative arthrofibrosis. The persistence of inflammation may be a more important measurement of the patient’s readiness for reconstruction: if the knee is found to be inflamed at the time of surgery at more than four weeks after injury, the patients have even greater risk for developing postoperative arthrofibrosis.
The Irritable Knee
Persistence of an effusion, hyperemia, and soft-tissue swelling indicates an inflamed, irritated knee. Noyes et al. described the at-risk knee with an exaggerated inflammatory soft-tissue response that involves excessive pain, limited ROM, and soft tissue edema which leads to knee stiffness. An irritable knee is more likely to experience a heightened response to the inflammatory factors released at the time of surgery, which increases the risk of arthrofibrosis through a complex molecular cascade. Arthrofibrosis is a T-cell mediated process, and the inflammatory cytokines and chemokines released at the time of injury and surgery may result in the continuation of pathological inflammation. Following ACL injury, an increase in synovial lining cell depth, synovial hyperplasia, vascular hyperplasia, lymphocyte infiltration, and the expression of cell adhesion molecules may be observed in the infrapatellar fat pad. Fibrogenic cytokines, platelet-derived growth factor (PDGF), and transforming growth factor (TGF)-β are also detected at fibrotic sites in the knees and are associated with pathological fibrosis. , Although the precise mechanism of arthrofibrosis is yet to be elucidated, the development of a stiff, fibrotic knee after ACL injury or surgery is clearly associated with a pathological vigor in the inflammatory process; it is necessary to modulate the response and restore joint homeostasis before surgical intervention to minimize the postoperative complications.
The presence of a bone bruise is an associated risk factor for increased inflammation and postoperative ROM deficits. A typical bone bruise pattern is seen on the lateral femoral condyle and posterolateral tibial plateau ( Fig. 4.1 ). This pattern of injury may be observed in up to 80% of ACL tears; however, the severity of the bony and periarticular injury is variable. As the ACL rupture occurs, a transient rotatory subluxation results, causing the lateral femoral condyle to impact the posterolateral tibial plateau. The trauma results in trabecular microfractures, local hemorrhage, and medullary edema which may also involve the chondral surface. , The additional local trauma results in a highly inflammatory pattern in the knee which results in a prolonged time to recover normal knee homeostasis. , The bone bruising pattern may take from 6 weeks and up to 2 years to fully resolve. , , , A bone bruise is strongly correlated with persistent postoperative ROM deficits regardless of restored preoperative ROM. Preoperative ROM deficit in the presence of a bone bruise is strongly correlated with arthrofibrosis. Limited ROM at the time of ACL reconstruction is also correlated with postoperative arthrofibrosis of the knee. Range of motion deficits are correlated with prolonged postoperative ROM deficits. Loss of full extension compared with the uninjured leg is also a significant independent predictor for failure to regain full postoperative knee motion. These findings again suggest that restoration of full ROM in the absence of inflammation is the primary preoperative goal.
Although the presence of an isolated bone bruise is a risk factor for decreased ROM and postoperative stiffness, additional injuries to the knee can predispose the patient to ROM deficits. Concomitant injuries to the medial collateral ligament (MCL) commonly occur with ACL motion, but may be overlooked if they are incomplete or more subtle. These may be seen with an intact superficial MCL and an injury to the deep MCL ( Fig. 4.2 ). A careful physical examination will demonstrate tenderness to palpation of both the medial joint line and proximally to the medial epicondyle. Medial ecchymosis should heighten the suspicion of an MCL injury regardless of the mechanism of injury. These injuries should be placed in a hinged knee brace preoperatively, and patients should continue to work with a physical therapist to regain full ROM before undergoing ACL reconstruction.