Understanding Common Knee Injuries And Lower Extremity Implications In Runners

By John F. Connors, DPM, and Ana J. Sanz, DPM

To have a successful sports medicine practice, it is crucial to understand not only the foot and ankle but also the knee and hip, and the mechanism of injuries affecting these areas. Having the opportunity to treat and travel with the best runners in the world has forced me to have a stronger understanding of lower extremity biomechanics, the mechanics of running and the injuries associated with running.

The knee is the most commonly injured part of the body in runners. Most of these injuries are chronic, overuse type of injuries. Knee injuries are often caused by a failure of the involved tissues to adapt to the repetitive stress applied.

Accordingly, let us take a closer look at common injuries affecting the runner’s knee and relevant lower extremity implications, and review pertinent case studies that illustrate some of the links between knee injuries and the lower extremity.

Oftentimes, the performance of a runner is based on foot type. Basically, long distance running requires a neutral foot. Overpronated feet lead to overuse injuries/syndromes. Excessive supination results in overstress. With running, the amount of force going through the lower extremity is at least three times one’s body weight. Biomechanical imbalances are accompanied by dynamic imbalances.

Clinically, a weak vastus medialis muscle (the only medial stabilizer of the patella) is associated with patellar femoral pathology and lateral maltracking of the patella in runners.

Tight hamstrings are characteristic of long distance runners. When hamstrings become too short, they limit hip and knee extension, thereby shortening stride length. This may predispose runners to inefficient stride or injury. Appropriate stretching and strengthening of all muscles of the lower extremity provide for more efficient, biomechanically sound gait.

After performing a full lower extremity biomechanical exam, we often perform a video gait analysis to assess the running mechanics of our running patients. We use Dartfish running software with a treadmill, a flat screen TV and video cameras around the runner. We perform a full lower extremity biomechanical exam before the video gait analysis. This has proven to be very beneficial to the runner.

Indeed, our goal as sports medicine specialists is injury prevention.

What You Should Know About Patellofemoral Syndrome
Patellofemoral syndrome (PFS) is the most common overuse injury among runners. More commonly known as “runner’s knee” or chondromalacia patella, this condition occurs when a mistracking patella irritates the femoral groove where it rests on the femur.

While this condition is more common among young female distance runners, it can occur at any age in either gender.

Patients usually present with vague pain in and around the anterior knee. This pain can be diffuse or localized. Patients typically complain of patella instability, painful cracking from the patella and the knee giving way. Their pain increases when climbing stairs and hills.

Crepitus is usually present with the grind test. This test involves compressing the patella into the trochlear groove with the quadriceps relaxed and asking the patient to contract the quadriceps, actively pulling the patella proximally in the trochlear groove. This patellofemoral compression can cause discomfort. In my experience treating runners, PFS is usually due to overpronation, weakness of the vastus medialis oblique (VMO) muscle and femoral anteversion. Other causes include wide hips (high Q angle), patella alta, limb length discrepancy, improper training or worn/inadequate running shoes.

One often makes the diagnosis clinically and with a biomechanical examination. Imaging studies are of limited value except to rule out a differential diagnosis or an associated pathologic condition.

As far as treatment goes, it is very important to understand the cause of PFS. After assessing this, one can institute a treatment plan.

Again, the leading causes of PFS are overpronation, a weak VMO and femoral anteversion. One must address all three of these issues.

Custom running orthotics should control the amount of overpronation. Studies have shown that orthoses are very effective in the treatment of PFS. Physical therapy is extremely helpful in the rehabilitation plan for the patient.

Keys To Recognizing Stress Fractures In Runners
With distance runners, stress reactions and fractures within the tibia are common. They occur less frequently in the medial tibial plateau than in the diaphysis. Medial tibial plateau stress injuries are often misdiagnosed as pes anserinus tendinitis or bursitis. While distal femoral stress fractures are not common, they do exist. Femoral stress fractures are more common proximally. The “fulcrum test” is very useful to assess femoral stress fractures.

In regard to patients with stress fractures in the tibia, I do allow them to cross-train (i.e. with deep water running). The use of electrical bone stimulators such as the Exogen Bone Healing System (Smith and Nephew) has proven to be beneficial with these injuries as well.

What About Symptomatic Synovial Plica?
Symptomatic synovial plica is another cause of knee pain in runners. A plicae is an embryonic synovial fold or septum which normally separates the suprapatellar pouch from the major part of the knee.

This usually disappears but may become a fibrous band due to trauma. During knee flexion and extension, the fibrous plicae rubs across the medial femoral condyle, causing pain that mimics a medial meniscus tear as well as degenerative changes in the medial femoral condyle.

There are three types of plicae: medial plicae (which is the most common), and suprapatellar and intrapatellar plicae (which are less common). The key finding in a knee with plicae syndrome is tenderness along the midmedial retinaculum. The medial joint line is not tender. If fibrous hypertrophy has occurred, one may be able to palpate a reproducible tender band. No effusion, ligament laxity or loss of motion is present. Foot type is not a factor with these injuries.

One often makes the diagnosis clinically. Magnetic resonance imaging studies are also useful. Conservative treatment consisting of physical therapy, NSAIDs and injection therapy has proven to be helpful. If conservative treatment fails and symptoms persist, one should consider referral for arthroscopic resection of the symptomatic plicae.

Understanding The Signs And Symptoms Of Iliotibial
Band Syndrome
The iliotibial band (ITB) is a fascia strip that passes down the lateral aspect of the thigh from the crest of the ilium and inserts into Gerdy’s tubercle of the lateral tibial condyle. As the knee flexes and extends during running, this band repeatedly rubs over the lateral femoral condyle. This causes inflammation and pain. The resulting knee pain is just above the joint line. Runners with these injuries usually have increased their mileage too soon, have biomechanical imbalances, run on hills and/or run on a banked surface.

The ITB moves anteriorly onto the lateral femoral condyle as the knee extends and slides posteriorly as the knee flexes. However, it remains under tension in both positions. This makes the ITB susceptible to inflammation. The symptoms usually consist of sharp pain or burning on the lateral aspect of the knee.

One would make this diagnosis clinically. Magnetic resonance imaging studies can show a focus of soft tissue edema adjacent to the ITB, usually on the deep aspect near the lateral femoral epicondyle.
The key to successful treatment of ITBS is an aggressive stretching program, which reduces the compression force between the band and the lateral epicondyle, according to Gary Guerriero, PT, the Head Physical Therapist and Director of the U.S. Athletic Training Center in New York City. Other treatment options include physical therapy modalities, injection therapy and orthotics. In my experience, only two patients with this injury required surgical management in 17 years of practice.

How To Recognize Meniscal Injuries
The menisci of the knee are C-shaped cartilaginous wedges covering 30 percent of the medial and 50 percent of the lateral tibial plateau. Menisci are mobile buffers that absorb shock and also help guide knee motion by providing stability. Meniscal injuries can be acute or chronic in nature. The meniscus is composed of fibrocartilage, which has minimal healing potential. The only vascularity is in the peripheral 20 to 30 percent of the meniscus. With time, micro-damage can occur in the meniscus. These microtears can eventually lead to a more complex tear. The patient usually complains of a “catching or locking” feeling in the knee. Diagnostic methods range from McMurry’s test to MRI studies.

The severity of meniscal damage will dictate if conservative treatment or surgical management via arthroscopy will help. While MRI is a very useful test, Jordan Metzl, MD, a sports medicine physician at the Hospital for Special Surgery in New York City, says physicians should be cautious about false positives in runners who have been running for many years.

Case Studies: Treating Three Competitive Runners
Case one involves a 21-year-old female runner who presented to my office complaining of right proximal shin/knee pain. The patient was running many miles with high intensity. There was a history of trauma where the patient fell and hit her knee. She was having difficulty with running. Pain was present with impact and also with knee flexion and extension. The patient was experiencing a “catching” feeling when running.

The clinical examination revealed discomfort around the medial knee. The differential diagnosis was possible stress fracture, pes anserine bursitis, mensical injury and plicae syndrome. The MRI studies revealed a medial tibial stress fracture. There was no mensical damage but a medial plicae did show up on MRI studies.

Treatment consisted of rest with cross training and physical therapy. After receiving two failed cortisone injections from the patient’s sports orthopedic doctor to decrease symptomatic plicae, the patient underwent the surgical removal of symptomatic plicae and is now running pain-free.

The second case involves a 30-year-old elite female runner who presented to our office complaining of left foot and left knee pain. She was having difficulty training and it was limiting her performance.

Upon the clinical examination, it was clear the patient had a neutral foot type on her right side but a slightly overpronated left foot. She had patellofemoral syndrome on her left knee. I diagnosed limb length discrepancy as the patient’s left leg was structurally longer than her right leg. I subsequently performed video gait analysis.

I casted the patient for custom-molded running orthoses and incorporated a lift into the right orthosis. The patient won a medal at the 2000 Summer Olympic Games and also triumphed at the London and New York marathons.

The third case is a 31-year-old elite female runner who presented to my office with plantar fasciitis and medial knee pain. The clinical examination revealed an overpronated foot type, a weak VMO and weak gluteal muscles.

After performing a video gait analysis, we provided custom-molded orthoses and had the patient institute aggressive physical training consisting of VMO and gluteal strengthening. The patient is currently a very highly ranked runner and is able to train pain-free.

In Conclusion
Many runners will consult a sports podiatrist for their lower extremity injuries. It is very important to have an understanding of lower extremity biomechanics and the mechanisms behind running injuries. Our job as sports medicine specialists is injury prevention. The use of video gait analysis has proven to be extremely beneficial to our practice.

Elite runners from all over the world come to our office to have this valuable test performed. Surrounding yourself with other sports medicine specialists, such as orthopedists, physical therapists, massage therapists, chiropractors and nutritionists, is also very important in facilitating appropriate referrals and the best multidisciplinary care.

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