The ABCs of PFD

When assessing and treating this painful knee condition, the obvious course is not always the best one.

By Daniel Cipriani & Jennifer Griest

Daniel Cipriani, MEd, PT, is an Assistant Professor of Physical Therapy at the Medical College of Ohio. He teaches in the areas of biomechanics, orthopedics, statistics, and research design. Jennifer Griest is a graduate student in physical therapy at the Medical College of Ohio.

Training & Conditioning, 12.3, April 2002, http://www.momentummedia.com/articles/tc/tc1203/abcpfd.htm

Patellofemoral Dysfunction (PFD) is a prevalent condition among athletes and the general population that is difficult to accurately diagnose and treat. It affects individuals of all ages and both genders, but it is more prevalent among females than males, and it occurs more often in running and court sports than in field sports.

Overall, PFD is a multifaceted pain condition of the anterior knee. Multifaceted means that many different factors can contribute to the onset of PFD as well as the ongoing irritation its symptoms create.

Since many factors may be involved in causing PFD, the best approach for treatment requires that you look beyond the obvious. The effectiveness of this approach can be illustrated by the strategies of the legendary golf coach Harvey Penick. Penick once coached a college golfer struggling with his putting game. The golfer lamented that he needed two or three putts on every green. Penick advised the golfer to work on his driving and approach shots to the green, but not on his putting game. Penick had observed that this golfer's problem was not necessarily poor putting, but rather that he was not able to get his ball close to the pin in the first place, leaving him with long, challenging putts. Penick's coaching strategy worked, resulting in fewer putts, even though this golfer did not work on his actual putting game.

Treating PFD is very similar to Penick's strategy: Even though PFD pain is experienced in the knee, the actual problems leading to this pain may be found elsewhere. This article addresses potential causes and treatment strategies for PFD using a multifaceted approach.

CAUSES & TREATMENTS
When assessing PFD, remember that many factors may be at fault.

Training error possibly is one of the most overlooked factors related to PFD. Often, a teenage athlete will enter a sport season in a deconditioned state and begin rigorous training to prepare for the upcoming competitive season. Whether it be basketball, cross country, track, or some other sport, the deconditioned athlete is subjected to running, sprinting, agility training, hill training, stair climbing, and other forms of demanding exercise programs to build strength, stamina, and responsiveness. Unfortunately, the patellofemoral joint (along with other joints and tissues) may not be prepared for this rapid onset of training stresses.

When a deconditioned athlete enters into sports or exercise programs without an appropriate progression of activity, he or she is very susceptible to PFD problems. This type of training does not take advantage of Wolfe's Law, which recognizes that all human tissues will adapt to stresses, given sufficient time and progression. Therefore, athletic trainers should be sure that their athletes and coaches follow a program of year-round fitness and training, as well as gradual progression of training.

A second potential factor related to PFD is faulty foot biomechanics. As with training error, this aspect often is overlooked because it is not readily recognized. However, research supports the notion that faulty foot biomechanics may be related to anterior knee pain. Specifically, Tiberio presented a very convincing biomechanical model of patellofemoral pain that linked PFD to foot biomechanics. In this model, abnormal (excessive) pronation of the foot, or subtalar joint (STJ), is related to the incidence of PFD in many individuals. Abnormal STJ pronation is manifested by an absence or decrease in the medial longitudinal arch of the foot and may be described as a valgus position of the calcaneus (heel bone) in stance.

Faulty foot biomechanics appears to be related to the sequence of events that occur with STJ pronation. It begins with an eversion of the calcaneus at foot contact during walking and running. This eversion results in an internal rotation of the talus. The stable articulation of the talus with the tibia and fibula then results in an internal rotation motion of the lower leg, and subsequently the entire leg. If pronation is excessive at the foot, internal rotation of the limb will then be greater than normal.

Excessive internal rotation of the limb then results in misalignment of the quadriceps mechanism at the knee, and of the patellofemoral joint itself. Quadriceps misalignment may be responsible for insufficient stability of the patellofemoral joint during dynamic activities. Also, a misaligned patella may result in abnormal wear of the contact surfaces of the femur or patella during flexion and extension of the knee. In either case, this abnormal patellar tracking may affect joint compression forces of the patellofemoral joint. Changes in joint compression forces can lead to changes in the tissue of the joint and possibly pain. Thus, while poor alignment at the knee may appear to be the problem, the excessive foot pronation is actually creating the pain.

Two treatment strategies for faulty foot biomechanics seem to be most effective. The first, and more costly approach, is to use custom-designed orthotic shoe inserts, which work well to minimize excessive subtalar joint motion. By reducing excessive foot pronation, the orthotic in turn reduces excessive internal rotation of the limb.

Other, less costly approaches are taping the longitudinal arch or fitting the runner with a more stable athletic shoe. In addition, over-the-counter shoe inserts have been shown to work well for some athletes. These approaches are often the first line of defense against PFD, because of cost and immediate response. However, a custom-designed orthotic may eventually prove to be a more permanent solution.

Hip factors are perhaps the least understood aspect of PFD. This may be because little research is available regarding the relationship between hip dysfunction and knee dysfunction. However, considering that the hip is a dynamic ball-and-socket joint with three full degrees of motion, it must be considered a factor in PFD. In fact, Iliotibial Band Friction Syndrome, a painful condition along the outside of the knee, is due to an imbalance of the tensor fascia lata, a lateral hip muscle. This shows how a hip muscle can cause a painful knee condition.

In terms of PFD, possible causal factors related to the hip include tightness of the hamstring muscles, tightness of the tensor fascia lata, weakness/slowness of the hip abductors, and weakness/slowness of the hip lateral rotators. Each of these hip muscle groups contributes to the normal timing and mechanics of the knee. Thus, each of these hip muscle groups can cause dysfunction at the knee. For example, tightness of the hamstrings may increase the effort required of the quadriceps during running and walking. This increased effort of the quadriceps might lead to increased patellofemoral joint compression, and resulting anterior knee pain.

Tightness of the tensor fascia lata (TFL), as mentioned above, has been shown to cause the overuse syndrome of Iliotibial Band Friction Syndrome at the knee. It is also thought that tightness of the TFL could result in faulty tracking of the patellofemoral joint via the iliotibial band (IT band). The IT band attaches to the patella retinacula and exerts a lateral pull of the patella relative to the femur. Thus, proximal muscle tightness of the TFL may result in poor alignment of the patellofemoral joint. Just as with the distal contribution of subtalar joint pronation on PFD, the proximal effect of the TFL could result in faulty patellofemoral alignment. This misalignment can lead to abnormal wear of the articular surfaces and PFD.

In addition to the above factors, muscle performance problems at the hip may lead to PFD. Consider weakness of the hip abductors or hip lateral rotators. In either case, excessive or poorly controlled motion at the hip will manifest at the knee. Weakness or poor timing of hip abductors (frontal plane muscles) may result in increased adduction of the femur, which then results in increased valgus at the knee. In the case of weakness or poor timing of the hip lateral rotators (transverse plane muscles), abnormal medial rotation of the femur may occur.

Thus, athletic trainers and clinicians should consider examining the hip for tightness or weakness that may result in faulty mechanics at the knee. Treatment strategies in these cases are fairly simple and well known, such as dynamic stretching of the hamstrings and IT band. Strengthening and performance training of the hip musculature is also recommended, including agility training, balance training, and general hip strength training.

Finally, we consider the patellofemoral joint and knee factors. Tightness of the lateral retinacula, resulting in lateral tracking of the patella, is a well-known cause of PFD. In addition, muscle imbalance of the quadriceps (namely between the vastus medialis oblique and the remaining quadriceps components) has also been shown to result in PFD.

In both of the above cases, the direct treatment approach seems to be the best option: Fitting individuals with knee sleeves to assist with patellar tracking may be effective. Proper fit is essential in allowing the knee sleeve to work sufficiently to stabilize the patella. Knee sleeves with patellar cutouts seem to work most effectively, provided the cutout is positioned directly over the patella. In fact, fully closed knee sleeves may actually increase knee pain by compressing the patellofemoral joint. Some knee sleeves may come with additional buttress pads, which may further assist in stabilizing the patella.

In addition, taping of the patella has been shown to be effective in controlling pain, especially while the athlete rehabilitates the knee. While taping requires some skill and practice, it can be taught to the athlete.

Strengthening the quadriceps is another effective technique for controlling PFD. However, it should be noted that certain traditional quadriceps-strengthening exercises, such as knee extensions, have been shown to create increased compressive forces to the patellofemoral joint. Instead, we recommend squatting exercises, which are naturally occurring motions in human function, and therefore, considered much safer in terms of patellofemoral joint compressive forces. As with all exercises, a gradual progression of force and motion is necessary to minimize the risk of injury during exercise.

CONCLUSION
Many clinicians and athletic trainers understand that the knee is an unfortunate joint caught in the middle between the mobile hip and the mobile ankle, with no place to hide. Thus, the knee is more susceptible to traumatic and overuse injuries than the hip and foot/ankle combined. In light of this, it is imperative that clinicians and athletic trainers pay close attention to the potential pathomechanics arising from the biomechanical relationship of the hip or foot/ankle and the knee. Remember, PFD is a condition of knee pain, but it also is a condition with many potential causes.