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Orthopaedic Rehabilitation
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Anterior Cruciate Ligament Injuries Basic Science and Biomechanics The ACL is the primary restraint to anterior translation of the tibia and a secondary restraint to tibial rotation and to varus and valgus stress. An intact ACL resists forces up to 2500 N and strain of about 20% before failing. Older ACLs fail under lower loads than younger ACLs. The forces placed on an intact ACL range from about 100 N during passive knee extension to about 400 N with walking and 1700 N with cutting and acceleration-deceleration activities. Loads exceed the ACLs failure capacity only with unusual combinations of loading patterns on the knee. Graft Material Properties The central third bone–patellar tendon bone graft has an initial failure strength of up to 2977 N, and the strength of a quadrupled semitendinosis–gracilis graft complex has been estimated as high as 4000 N. However, these strengths are greatly reduced after surgical implantation. Current thought is that the initial graft strength must exceed that of the normal ACL to maintain sufficient strength, because strength is lost during the healing phase, and that a stronger graft will allow for a safer rehabilitation and return to activity. Graft Healing After implantation, ACL grafts undergo sequential phases of avascular necrosis, revascularization, and remodeling. The graft material properties change as the process of ligamentization proceeds. Ultimate load to failure in a patellar tendon autograft can drop as low as 11% of the normal ACL, and the graft stiffness can fall to as low as 13% of the normal ACL during graft maturation. Data on human grafts indicate that implanted grafts begin to resemble a native ACL structure as early as 6 months after implantation, but that final maturation does not occur until after 1 year. Graft Fixation In the first 6 to 12 weeks of rehabilitation, the fixation of the graft rather than the graft itself is the limiting factor for strength in the graft complex. The exercises and activities used in rehabilitation during this time must be carefully chosen so as not to exceed the ability of the fixation to resist graft slippage. For central third–patellar tendon grafts, interference screw fixation of the bone blocks in the femoral and tibial tunnels has been shown to exceed 500 N for both metallic and bioabsorbable screws. Graft slippage has not been a problem with this construct. With hamstring grafts, soft tissue fixation and graft slippage vary greatly depending on the fixation (Fig. 4–13). The strongest fixation, with the least amount of graft slippage, is with soft tissue washers, which can provide a construct strength above 768 N. Interference screw fixation has not been as successful, with yield strengths less than 350 N and graft slippage or complete fixation failure with low-level loading. Open– and Closed–Kinetic Chain Exercise Considerable debate has occurred in recent years regarding the use of closed–kinetic chain activity versus open–kinetic chain activity after ACL reconstruction (see Glossary for definition of open- and closed-chain exercises). An example of an open–kinetic chain exercise is the use of a leg extension machine (Fig. 4–14). An example of closed–kinetic chain exercise is the use of a leg press machine (Fig. 4–15). In theory, closed–kinetic chain exercises provide a more significant compression force across the knee while activating cocontraction of the quadriceps and hamstring muscles. It has been suggested that these two factors help decrease the anterior shear forces in the knee that would otherwise be placed upon the maturing ACL graft. Because of this, closed–kinetic chain exercises have been favored over open– kinetic chain exercises during rehabilitation after ACL reconstruction. However, the literature supporting this theory is not definitive. Many common activities cannot be clearly classified as open– or closed–kinetic chain, which adds to the confusion. Walking, running, stair climbing, and jumping all involve a combination of open– and closed–kinetic chain components to them. Jenkins and colleagues (1997) measured side-to-side difference in anterior displacement of the tibia in subjects with unilateral ACL-deficient knees during open–kinetic chain exercise (knee extension) and closed–kinetic chain exercises (leg press) at 30 and 60 degrees of knee flexion and concluded that open-chain exercises at low flexion angles may produce an increase in anterior shear forces, that may cause laxity in the ACL.
Yack and colleagues (1993) also found increased anterior displacement during open–kinetic chain exercise (knee extension) compared with closed–kinetic chain exercise (parallel squat) through a flexion range of 0 to 64 degrees. Kvist and Gillquist (1999) demonstrated that displacement occurs with even low levels of muscular activity: generation of the first 10% of the peak quadriceps torque produced 80% of the total tibial translation seen with maximal quadriceps torque. Mathematical models also have predicted that shear forces on the ACL are greater with open-chain exercises. Jurist and Otis (1985), Zavetsky and coworkers (1994), and Wilk and Andrews (1993) all noted that changing the position of the resistance pad on isokinetic open–kinetic chain devices could modify anterior shear force and anterior tibial displacement. Wilk and Andrews also found greater anterior tibial displacements at slower isokinetic speeds. Prevention is the first and most effective method of treatment for loss of motion after surgery. Many of the factors leading to loss of knee motion can be prevented with proper surgical timing and technique. Anterior placement of the tibial tunnel and inadequate notchplasty both can lead to impingement of the graft on the roof of the intercondylar notch with a subsequent loss of extension (Fig. 4 – 16). Anterior femoral tunnel placement may lead to increased graft tension in flexion with subsequent limitation of flexion. Inappropriate tensioning of the graft may overconstrain the knee and also lead to difficulty regaining terminal motion. Inadequate notch preparation and ACL stump débridement may predispose the patient to formation of a fibroprolifer-ative scar nodule, called a “cyclops” lesion, which may impinge anteriorly in the knee causing pain and limiting extension (Fig. 4 – 17). Symptoms suggestive of a cyclops lesion include loss of extension and a large, painful clunk on attempted terminal extension of the knee. ACL reconstruction should be delayed until the acute posttraumatic inflammation and swelling have subsided, full ROM has returned, and the patient has regained strong quadriceps activation. To meet these goals, preoperative rehabilitation should be started shortly after injury. Modalities to control pain and swelling, such as cryotherapy, elevation, compression, and anti-inflammatory medication, are helpful in eliminating reflex muscular inhibition of the quadriceps. Quadriceps setting, SLR, and closed-chain exercises, accompanied by electrical muscle stimulation and biofeedback, are useful to reactivate the lower extremity musculature, prevent atrophy, and promote strength gain. Proprioception activities can also be started to improve neuromuscular retraining. Activities to increase motion, aided by modalities such as prone hangs, wall slides, and the use of extension boards, are also used in the preoperative period. There is no single time frame (such as 3 weeks) for surgical delay to avoid postoperative arthrofibrosis. The condition of the patient’s knee rather than any predetermined waiting period determines the appropriate timing for surgery. Less motion loss and faster return of quadriceps strength have been reported when surgery was delayed until motion was restored. Early ACL reconstruction, before return of motion and “cooling” of the knee, increases the risk of postoperative arthrofibrosis. Early passive and active ROM are begun immediately after surgery and may be augmented with the use of a continuous passive motion (CPM) machine. Postoperative immobilization increases the risk that later manipulation will be required to regain motion. Control of pain and swelling, early reactivation of the quadriceps musculature, and an early return to weight-bearing all improve the return of motion. Patellar mobilization techniques should be started to prevent patellar tendon shortening or retinacular contracture, both of which can lead to motion loss. The most important immediate goal is to obtain and maintain full knee extension almost immediately after surgery. Knee flexion to 90 degrees should be achieved by 7 to 10 days after surgery. Failure to do so should prompt the early initiation of countermeasures to prevent a chronic problem from occurring. These are discussed in detail in the complications/troubleshooting section. Continuous Passive Motion The efficacy of CPM after ACL reconstruction is controversial (Fig. 4–18). Historically, its use was advocated to improve cartilage nutrition and limit motion loss during a time when immobilization was common after surgery. With the growing popularity of accelerated rehabilitation emphasizing early motion and weight-bearing, the benefits of CPM have waned. Few recent studies have demonstrated a significant long-term benefit of CPM. We currently do not believe the added cost is justified by any short-term benefit and, since 1993, have not routinely recommended the use of CPM. However, there is a role for CPM after manipulation and arthroscopic surgery in patients who have developed arthrofibrosis. Weight-bearing Status Theoretical advantages of weight-bearing include improved cartilage nutrition, decreased disuse osteopenia, reduced peripatellar fibrosis, and quicker quadriceps recovery. Tyler and colleagues (1998) showed that immediate weight-bearing reduced muscle inhibition at the knee joint in the early postoperative period, as demonstrated by an increased return of electromyographic (EMG) activity in the vastus medialis oblique (VMO) muscle within the first 2 weeks after surgery. They also demonstrated a reduction in the development of anterior knee pain in patients who began immediate weight-bearing. No differences in knee laxity, ROM, or functional scores were noted between weight-bearing and non–weight-bearing groups. One theoretical concern about weight-bearing in the first 4 to 6 weeks after surgery is donor site morbidity in patients in whom a bone–patellar tendon–bone autograft is used. The frequency of proximal tibial fracture, patellar fracture, and patellar tendon rupture in association with weight-bearing is unknown at this time, but certainly is less than 1%. Although rare, these complications can be difficult to treat and can lead to poor results. We currently recommend maintaining the knee in a brace locked in full extension during ambulation for the first 4 to 6 weeks after surgery to limit the forces transmitted through the extensor mechanism and to protect the extensor mechanism if the patient slips or falls. Note: The editors maintain the knee locked in full extension during ambulation for only 2 to 3 weeks. Muscle Training The early initiation of muscle training is crucial to prevent muscle atrophy and weakness. Electrical muscle stimulation may be helpful to initiate muscle activation in patients who are unable to voluntarily overcome reflex inhibition. Biofeedback (such as VMO biofeedback) can be used to enhance the force of muscular contraction. Weight-bearing has also been shown to be beneficial in promoting muscle reactivation. Muscle balance, achieving the appropriate hamstring-to-quadriceps ratio, improves dynamic protection of the ACL. Barratta and colleagues (1988) reported an increased risk of injury with reduced hamstring antagonist activity and demonstrated improved coactivation ratios in response to exercise. Fatigue has been shown to significantly affect not only the strength of muscular contraction but also the electromechanical response time and rate of muscular force generation. Because deficits in these critical elements of dynamic knee stabilization reduce the ability to protect the knee during activity, endurance training should be included in the rehabilitation program. Electrical Muscle Stimulation and Biofeedback Electrical muscle stimulation (Fig. 4–19) and biofeedback (Fig. 4–20) may be useful as adjuncts to conventional muscle training techniques. Although there is no convincing evidence that electrical muscle stimulation alone is superior to voluntary muscle contraction alone in promoting muscle strength after surgery, it may be of benefit in the early postoperative period when reflex inhibition of the quadriceps owing to pain and swelling prevents the initiation of voluntary muscle activity. Anderson and Lipscomb (1989) noted a positive effect of electrical muscle stimulation in limiting quadriceps strength loss and patellofemoral crepitus after ACL reconstruction. The most appropriate use of electrical muscle stimulation seems to be in combination with volitional muscle activity in the early postoperative period. Biofeedback may be useful for reeducation of the muscles. Using EMG monitoring, a visual or auditory signal is provided to the patient when a preset threshold of muscle activity is achieved. The threshold limits can be modified as the patient progresses. Through the use of positive “rewards,” biofeedback encourages increased muscular contraction, which is beneficial during strength training. It can also promote the improved timing of muscle activation, which in turn benefits dynamic stabilization of the knee. Proprioception The role of the ACL in proprioception of the knee is still under investigation. Altered proprioception has been reported to reduce the effectiveness of the individual to protect the knee and perhaps predispose the ACL to repetitive microtrauma and ultimately failure. Patients with ACL-deficient knees have been shown to have decreased proprioceptive abilities, which in turn has a detrimental effect on the dynamic hamstring stabilization reflex. Differences in proprioception have been demonstrated in asymptomatic and symptomatic patients after ACL injury, and a relationship between proprioception and outcome after ACL reconstruction has been noted. The mechanism by which rehabilitation after ACL reconstruction has a beneficial effect on improving proprioception is not clear. However, improvement has been shown in both ACL-reconstructed and ACL-deficient patients after proprioceptive training programs. Lephart and coworkers (1992 and 1998) recommended a program designed to affect all three levels of neuromuscular control. Higher brain center control is developed through conscious, repetitive positioning activities, which maximize sensory input to reinforce proper joint stabilization activity. Unconscious control is developed by incorporating distraction techniques into the exercises, such as the addition of ball throwing or catching while performing the required task (Fig. 4–21). To improve brain stem control, balance and postural maintenance activities are implemented, beginning with visual activities with the eyes open and progressing to exercises with the eyes closed to remove the visual input. The rehabilitation program also includes a progression of activities from stable to unstable surfaces and from bilateral to unilateral stance. To enhance proprioceptive control at the spinal level, activities involving sudden changes in joint position are used. Plyometric activities and rapid movement exercises on changing surfaces improve the reflex dynamic stabilization arc. ACL Bracing The effectiveness of and need for bracing after ACL reconstruction are controversial. Two forms of braces are currently in use, rehabilitation (transitional) braces (Fig. 4–22A) and functional braces (Fig. 4–22B). Rehabilitation braces are used in the early postoperative period to protect the donor site while ROM, weight-bearing, and muscle activity are initiated. Functional braces are used when the patient returns to strenuous activity or athletics to provide increased stability to the knee and to protect the reconstructed ligament while it matures. The efficacy of prophylactic functional bracing preventing reinjury after graft maturation has not been supported in the literature and is not recommended. Beynnon and associates (1997) demonstrated a protective effect from bracing under low-level loading conditions, but this effect was diminished with progressively increasing loads. Bracing has been shown to increase quadriceps atrophy and inhibit the return of quadriceps strength after surgery. These effects appear to resolve once brace use is discontinued. No long-term benefits of bracing on knee laxity, ROM, or function have been demonstrated. We currently recommend use of a drop-lock rehabilitation brace for the first 4 to 6 weeks after surgery. The brace is locked in extension during sleep to prevent potential loss of extension, and for patients with bone–patellar tendon–bone autografts, it is locked in extension during weight-bearing to protect the extensor mechanism. The brace is removed or unlocked several times a day during ROM and non–weight-bearing exercises. We believe that the risk of postoperative patellar fracture or patellar tendon rupture, although rare, outweighs the cost and inconvenience of transitional brace use. Gender Issues In recent years, a tremendous increase in women’s participation in athletics has made it apparent that women are at an increased risk for ACL injury. A number of differences between women and men have been hypothesized as possible causes for this increased susceptibility. Specific rehabilitation modifications may help to compensate for these anatomic, neuromuscular, and flexibility differences and should be incorporated into the standard protocol being used. The anatomic differences (a wider pelvis, increased genu valgum, increased external tibial torsion, and underdeveloped musculature) place a woman’s ACL at an inherent mechanical disadvantage, especially during jumping activities when increased rotational forces at landing may overload the ligament. Among the differences in neuromuscular characteristics of men and women is a decreased ability in women to generate muscular force, even when corrections are made for size differences. This limits the ability to resist displacing loads through dynamic stabilization of the knee. Other differences in dynamic knee stabilization that place women at greater risk for ACL injury include slower muscle activation and force generation, and the recruitment of the quadriceps muscles rather than the hamstrings or gastrocemius muscles. An inherently lower hamstring-to-quadriceps muscle ratio may further strain the ACL. Women have greater laxity than men. There may be a hormonal basis for this difference because changes in laxity have been documented during the menstrual cycle. As a result, women have increased hyperextension at the knee, placing the knee in a less favorable position for the hamstrings to generate a protective force. Women also generate less dynamic knee stability than men in response to muscle contraction. These factors lead to greater anterior tibial displacement in women and may place the ACL at greater risk for injury. Hewett and colleagues (1996) developed a prophylactic training program designed specifically for women to try to reduce the risk of knee injury. They demonstrated a reduction in landing forces, increased muscle power, and improved hamstring-to-quadriceps ratio with a 6-week training program. They also found that the program, when done before a sport season, significantly reduced the number of knee injuries in women athletes. Wilk and colleagues (1999) proposed eight key factors that should be considered during rehabilitation after reconstruction of the ACL in women and designed a set of specific exercises to counteract problem areas. Another key to avoiding ACL injuries in female athletes is to train the athlete to land from a jump with both knees slightly flexed. This will help avoid a hyperextension mechanism and reduce the risk of ACL injury. Older Patients with Anterior Cruciate Ligament Injuries An awareness of the health benefits of improved physical fitness has led to an increase in the activity level of the older population and an increase in ACL injuries. Traditionally, ACL injuries in older patients were treated non-operatively, but much better outcomes have been demonstrated with surgical treatment. Patients older than 35 years do benefit from ACL reconstruction and can expect results comparable with those of younger patients; however, the ACL deficiency must be treated early after injury, before chronic degenerative changes occur. Results of ACL reconstruction in older patients with long-term, chronic ACL deficiency are not as predictable. Rehabilitation protocols developed specifically for the older population have not been studied, and it is unclear whether modifications in the standard programs are needed. Patients older than 26 years have been shown to have decreased muscle strength after reconstructive surgery compared with younger patients. An awareness of this fact and emphasis on quadriceps along with hamstring strengthening may help to improve outcomes in older patients. We routinely offer the option of nonirradiated patellar tendon allografts to patients older than 40 years to further reduce potential extensor mechanism complications. Effect of Graft Selection on Postoperative Rehabilitation Protocol We currently use a single rehabilitation protocol after all ACL reconstructions regardless of graft material, with only slight weight-bearing and bracing modification depending on the graft source (see p. 284). The current trend in rehabilitation after ACL reconstruction has been toward an increasingly aggressive restoration of motion and strength, with an accelerated return to sporting activities at 4 months after surgery. A number of prospective studies have demonstrated the efficacy and safety of these accelerated programs for patients with patellar tendon autografts. The benefits of hamstring grafts have been cited as decreased donor site morbidity, improved cosmesis, and less residual anterior knee pain. However, questions have arisen regarding fixation strength, residual graft laxity, and the safety of accelerated rehabilitation protocols. Improved fixation methods for soft tissue grafts continue to be developed and currently approach the strength of patellar tendon–bone fixation. Studies comparing patellar tendon autografts with hamstring autografts show a trend toward greater laxity with the use of hamstring grafts, but this has not correlated consistently with a functional deficit. Howell and Taylor (1996) demonstrated the safety of an accelerated rehabilitation protocol with hamstring autografts. They allowed full return to sports at 4 months after brace-free rehabilitation, with clinical results similar to those with patellar tendon autografts. Results did not deteriorate between evaluations at 4 months and 2 years after surgery. Allografts typically have been reserved for use in multiple ligament injuries or in revision surgery. Initially, fears of disease transmission and questions about weakened structural properties or delayed healing discouraged the use of allografts in primary reconstructions. Advances in screening techniques have virtually eliminated the risk of disease transmission, and the abandonment of ethylene oxide and irradiation for sterilization has resulted in stronger graft properties. The advantages of allografts are no donor site morbidity, larger graft constructs, and shorter surgical time. Although questions about the increased time for graft incorporation in the host remain, comparison studies of nonirradiated, fresh-frozen patellar tendon allografts and patellar tendon autografts have demonstrated few differences in outcomes using similar accelerated rehabilitation protocols. Functional Testing after Anterior Cruciate Ligament Reconstruction After ACL reconstruction and rehabilitation, clinical testing, including strength testing and laxity measurements, does not correlate well with functional ability in all patients. Functional testing was developed to help evaluate surgical and therapeutic outcomes and a patient’s readiness to return to unrestricted activity. The most commonly used tests are the single hop for distance, the triple hop for distance, and the 6-m timed hop. Other proposed tests include the vertical jump, the cross-over hop for distance, and the figure-of-eight hop. The literature supporting the reliability and reproducibility of many of the functional tests is limited. No single test has been shown to be adequate for evaluating the dynamic function of the knee, and many surgeons recommend the use of a series of functional tests for testing dynamic function. Noyes and coworkers (1991a) developed a battery of functional tests consisting of the single hop for distance, the triple hop for distance, the cross-over hop for distance, and the 6-m timed hop (Table 4–2). Independent testing has shown good reliability and reproducibility for this combination of testing. More recently, it has been suggested that force absorption may be a more important factor in knee function than force production. Alternative functional tests are being developed and tested, but at this time, the support for these tests is limited. We currently use a battery consisting of the single-leg hop, the timed single-leg hop for 20 feet, and the vertical jump (see p. 280). Criteria for Return to Sports after Anterior Cruciate Ligament Reconstruction Correlation between functional testing, clinical testing, and subjective testing methods is poor when evaluating a patient after ACL reconstruction, perhaps because each method evaluates a different aspect of the recovery process. For this reason, we advocate the use of multiple criteria, drawn from each area of evaluation, in determining when a patient can return to full activity. Complications and Troubleshooting after Anterior Cruciate Ligament Reconstruction Loss of Motion Loss of motion is often cited as the most common complication after ACL reconstruction and can result for a number of causes as shown in the next paragraph. The definition of loss of motion varies in the literature. Harner and colleagues (1992) use a loss of knee extension of 10 degrees or knee flexion of less than 125 degrees to define loss of motion, and Shelbourne and coworkers (1996b) define loss of motion as any symptomatic deficit of extension or flexion compared with that of the opposite knee. The term “arthrofibrosis” has been used when the limitation of motion is symptomatic and resistant to rehabilitative measures. Often, it is used synonymously with loss of motion in the literature. Shelbourne and coworkers also developed a classification system for arthrofibrosis or loss of motion: Type 1 ≤10 degrees flexible extension loss and normal flexion; no capsular contracture; anterior knee pain common. Type 2 >10 degrees fixed extension loss and normal flexion; possibly mechanical block to motion and posterior capsular tightness. Type 3 >10 degrees extension loss and >25 degrees flexion loss with decreased medial and lateral movement of the patella (patellar tightness). Type 4 >10 degrees extension loss and ≥30 degrees of flexion loss and patella infera with marked patellar tightness. Patella infera, or “infrapatellar contracture syndrome” as Paulos and associates (1987) first called it, results from a hypertrophic healing response in the anterior soft tissues of the knee. The exuberant fibrosclerotic tissue entraps and tethers the patella, limiting knee motion. The term “patella infera” refers to the lower position of the affected patella on a lateral radiograph when compared with the uninvolved side (Fig. 4–23). A painful, restricted ROM, inflammation and induration of the peripatellar soft tissues, an extensor lag, and a “shelf sign,” which is a step-off between the swollen patellar tendon and the tibial tubercle, all should raise the suspicion of a developing patella infera. The most effective prevention or treatment is early quadriceps activity and knee flexion. The quadriceps maintains tension in the patellar tendon, which limits shortening or contracture of the tendon. Knee flexion stretches the tendon and surrounding soft tissues, which also prevents any shortening or contracture from developing. Prevention of arthrofibrosis is the most effective treatment. If any of the criteria are not met, aggressive counter-measures should be implemented to prevent fixed motion loss. To improve extension, prone hangs, an extension board, manual pressure extension against a theraband, and backward walking can be used (Fig. 4–24). To improve flexion, wall and heel slides, supine, prone, or sitting leg hangs, and manual pressure are used (Fig. 4–25). CPM and extension bracing, modalities to control pain and inflammation and to increase quadriceps and hamstring activity, and the judicious use of cryotherapy, nonsteroidal anti-inflammatory drugs (NSAIDs), electrical stimulation, ionophoresis, and phonophoresis are all helpful. If inflammation is prolonged after surgery, we occasionally use a Medrol Dose-Pak. Surgical intervention is required when the motion loss becomes fixed and progress through nonoperative therapy has reached a plateau. When surgical intervention is necessary, aggressive rehabilitation to gain motion should be slowed to allow reduction of the inflammation in the knee, although strengthening should continue as tolerated. Surgery for arthrofibrosis is contraindicated in an acutely inflamed knee according to some surgeons who believe a better outcome is gained by waiting for the inflammation to resolve. The first step in surgical management of arthrofibrosis is examination of the knee with the patient under anesthesia to delineate the extent of motion loss with the patient fully relaxed. Arthroscopy in conjunction with manipulation under anesthesia allows the direct examination of the knee joint to confirm the presence of a cyclops lesion, areas of exuberant scar formation, or other lesions that may be blocking motion. Any abnormal scar tissue or hypertrophic fat pad is débrided. For more severe motion loss, medial and lateral patellar releases may be performed, and an open posterior capsular release may be necessary. Depending on the severity of the arthrofibrosis, multiple manipulations may be required during the arthroscopic procedure to evaluate the progress of the débridement. (Recommended reading for indications and surgical techniques for treatment of arthrofibrosis includes Shelbourne and associates [1996b].) Rehabilitation must start immediately after surgical resection for arthrofibrosis, with emphasis on maintaining and improving ROM. Particular attention should be given to maintaining extension, before directing efforts toward flexion. An extension brace may be beneficial, particularly in patients with severe arthrofibrosis. Anterior Knee Pain Anterior knee pain is another common problem after ACL reconstruction. Symptoms can occur anywhere along the extensor mechanism. It has been suggested that anterior knee pain after ACL reconstruction may be related to the choice of graft material. Whereas the literature remains mixed on this subject, most studies show a significant tendency for a decrease in anterior knee pain with the use of hamstring autografts when compared with patellar tendon autografts. Interestingly, no difference has been noted between patellar tendon autografts and allografts, suggesting that the relationship between donor site morbidity and anterior knee pain may not be as clear as previously thought. Early rehabilitation to regain ROM and promote quadriceps control is important in the prevention of patellofemoral symptoms. Patellar mobilization techniques should be included to prevent contracture of the retinacular structures surrounding the patella, which may irritate the patellofemoral joint. For a patient who begins to show signs of anterior knee pain, the rehabilitation program should be modified to eliminate exercises that may place undue stress on the patellofemoral joint. Activities that increase the patellofemoral joint reaction forces (PFJRFs) should be avoided; these include deep squats, Stairmaster use, jogging, and excessive weight during leg presses. Terminal knee extension exercises also often elicit anterior knee pain. |
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