Tips for Diagnosis and Management
Timothy S. Petsche, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 30 - NO. 8 - AUGUST 2002
In Brief: Recognizing and correctly diagnosing popliteus tendinitis is important because this condition can be painful, may significantly limit athletic performance, and can lead to unnecessary surgery if misdiagnosed. The diagnosis is largely established with a careful history and physical examination. Usually patients have symptoms that include tenderness along the course of the proximal popliteus tendon and pain with resisted external rotation. Treatment is directed at eccentric strengthening of the quadriceps to reduce strain on the popliteus. Most patients respond well to physical therapy and NSAIDs; however, recalcitrant cases may require local corticosteroid injection.
Inflammation of the tendinous portion of the popliteus muscle (popliteus tendinitis) is rare but can produce significant clinical symptoms.1,2 Patients who have the disorder typically have pain along the posterolateral aspect of the knee.1 Popliteal tendinitis symptoms can be severe enough to limit or prevent athletic participation. Because pain is so close to the joint line, patients are sometimes misdiagnosed as having a meniscal tear and occasionally have been treated with arthroscopy or arthrotomy.1
Two cases serve to highlight diagnostic and treatment specifics. We offer an overview of popliteus muscle functional anatomy and provide tips for taking the history, performing examinations, and providing treatment of patients with popliteus tendinitis.
Two Illustrative Cases
Case 1. A 31-year-old National Football League (NFL) wide receiver presented to his team physician complaining of pain along the posterolateral aspect of his right knee. He denied any specific injury or knee locking or buckling. He experienced pain for approximately 3 months during the football season. When seen by physicians, the player had already undergone extensive physical therapy, including topical modalities, massage, flexibility and stretching regimens, and generalized strength training of the lower legs, without any relief. Additionally, several courses of nonsteroidal anti-inflammatory drugs (NSAIDs) failed to relieve any of the player's symptoms.
His pain was only mild at rest, but it was very significant during competition and affected his ability to run and cut. During the season, the patient had two magnetic resonance imaging (MRI) scans performed on the knee that were both reported to be negative. Since conservative treatment had failed, the player had been recommended for arthroscopic intervention, at which time he presented to the authors for a second orthopedic opinion.
Physical examination showed that he had full active range of motion, no ligamentous instability, and no effusion. He had slight tenderness along the posterolateral joint line just posterior to the lateral collateral ligament and also had tenderness along the course of the proximal popliteus tendon. The player exhibited a positive Garrick test: Pain in the posterolateral knee occurred with resisted external rotation of the leg.3 Review of one of the MRI scans showed intact menisci and ligaments with a small fluid collection adjacent to the popliteus musculotendinous junction (figure 1). The fluid was thought to lie within the synovial bursa surrounding the proximal popliteus.
The diagnosis of popliteus tendinitis was made on the basis of the positive test and MRI review. Because an appropriate rehabilitation program and conservative treatment modalities had already failed, corticosteroid injection was recommended. The player received an injection of 1 mL 2% plain lidocaine hydrochloride combined with 10 mg of triamcinolone and felt immediate relief of pain and tenderness. To supplement the injection, he rested for 1 week.
The player began a physical therapy program to selectively improve quadriceps strength and enhance limb flexibility. One week after the injection, he was able to return to full competition. He has continued to compete in the NFL for the past two seasons without any recurrence of his symptoms.
Case 2. A 26-year-old professional jai alai player presented to the authors with posterolateral left knee pain. He denied any specific trauma and described a gradual onset of symptoms. The pain worsened the more that he played, but he had only mild discomfort at rest. When pain progressed to the point that it was limiting his ability to participate in jai alai, he sought an orthopedic consultation.
Examination of the left knee revealed full active range of motion. There was no ligamentous instability or effusion. The patient had mild posterolateral joint-line tenderness, but a McMurray test was negative. In the prone position, the knee was focally tender along the course of the popliteus tendon. A Garrick test3 was positive, and a diagnosis of popliteus tendinitis was established.
The patient sat out jai alai games for 2 weeks and underwent formal physical therapy to improve flexibility and strengthen quadriceps function. The player was also given a prescription for a 2-week course of diclofenac (75 mg, twice a day). After 10 days, he had significant pain relief and was able to return to running and throwing the jai alai ball. He returned to full competition 14 days after his initial presentation and since then has had no recurrence in 5 years of professional competition.
Popliteus Tendon Biomechanics
Anatomy. Proximally, the popliteus inserts primarily on the lateral femoral condyle anterior and inferior to the fibular collateral ligament origin and is separated from the collateral ligament, capsule, and condyle by a synovial bursa. The popliteus also has secondary attachments proximally to the fibular head and lateral meniscus (figure 2). The part of the popliteus arising from the femur and attaching to the fibula has been termed the popliteal fibular ligament. The secondary proximal attachments are quite variable.4,5 Distally, the popliteus arises from the proximal, posterior, medial border of the tibia as a broad flat muscle. From this point, the muscle passes beneath the lateral head of the gastrocnemius.
Function. The popliteus muscle has been shown by electromyographic (EMG) studies to be the primary internal rotator of the tibia, and during initial flexion from an extended position, it will "unlock" the knee.6 The popliteus also assists in providing varus and valgus stability, controlling lateral meniscus displacement, and resisting coupled external rotation and posterior tibial displacement.4,6,7 Some controversy exists as to the degree that the popliteus contributes to withdrawing the lateral meniscus during knee flexion.2,4-6
Popliteus tendinitis has been associated with downhill running or other deceleration activities,2,3 and some authors1,2,6 have suggested that this may stem from the popliteus' functioning to prevent excessive posterior tibial translation relative to the femur. EMG studies1 show that the popliteus functions throughout most of the stance phase of the gait cycle, suggesting again that the muscle acts with the quadriceps and posterior cruciate ligament to stabilize the femur from displacing anteriorly off the tibial plateau surfaces during the stance phase.1 In sum, the popliteus assists the quadriceps and posterior cruciate ligament to maintain normal tibial and femoral orientation.
Managing Popliteus Tendinitis
History. Some authors1-3 have suggested that overuse or fatigue of the quadriceps may lead to inflammation of the popliteus. When the fatigued quadriceps cannot adequately resist forward displacement of the femur on the tibia, undue stress occurs on the secondary restraints, overwhelming the relatively small popliteus muscle.2 Typically, popliteus tendinitis has a gradual onset of symptoms, but often patients' pain will begin during or after a single day of activity. Popliteus tendinitis does not occur from an acute knee injury; however, isolated complete or partial rupture of the popliteus tendon has been occasionally reported.5,8,9
Typically, patients are able to run for short distances, but with continued running, posterolateral knee pain develops. Many patients will report pain in the back of the knee, but they will almost always point to the posterolateral area. Sports that require frequent deceleration result in eccentric loading of the quadriceps, which may fatigue them. Downhill running or hiking that produces deceleration will often initiate or exacerbate symptoms.2,3 Other sports that may cause quadriceps fatigue include basketball and tennis.
Physical exam. The main finding is tenderness along the proximal aspect of the popliteus tendon. This can occur at the femoral origin or distally, posterior to the fibular collateral ligament. In the experience of the senior author (F.H.S.), the best method of palpation is with the patient prone. The examiner begins near the posterolateral corner, medial to the biceps femoris tendon, and palpates along the joint line. Some authors recommend palpating while the patient is sitting up with the leg crossed in the "figure of four" position.1-3 This makes the lateral collateral ligament more prominent and enables the examiner to better identify the soft-tissue structures. Garrick and Webb3 describe an active functional test of the popliteus (figure 3). The knee is flexed to 90°, and the patient is asked to resist the examiner's external rotation force on the tibia. This action will result in pain if the popliteus is inflamed. Simple passive external rotation may also elicit pain.
Differential diagnosis. It is important to consider the possibility of a lateral meniscus tear or lateral compartment articular damage when a patient reports posterolateral joint pain. Although more common medially, a popliteal cyst can present a similar pattern of symptoms. However, patients with popliteus tendinitis should have no catching, locking, giving way, or effusion. Injuries or inflammation of the lateral head of the gastrocnemius, biceps femoris tendon, or iliotibial band may be mistaken for popliteus tendinitis, but these conditions can be differentiated by careful palpation and by specific muscle functional testing. If physicians are uncertain, radiographs and MRI may be helpful.8
Treatment. As noted, the popliteus helps to prevent posterior tibial translation1,2,6 and, like the quadriceps, is a dynamic stabilizer subject to fatigue. Thus, excessive quadriceps fatigue strains the popliteus. This phenomenon provides a rationale for treating popliteus tendinitis: a rehabilitation program emphasizing eccentric strengthening of the quadriceps muscle. In addition to strengthening, various treatment modalities that have been recommended include rest, NSAIDs, and localized corticosteroid injection.1,2
We prescribe a program of supervised physical therapy focusing on eccentric strengthening of the quadriceps. Flexibility is also evaluated, and patients are instructed in ways to stretch adequately before their activities. When the diagnosis is first established, patients are prescribed a short course (usually 2 weeks) of NSAIDs, which are usually given in conjunction with the initiation of a physical therapy program. Most patients will respond quickly and be able to return to their sport.
Return to play is determined by symptoms. As the pain resolves, patients are allowed to participate in any activity that does not cause pain. Some patients will be slower to respond to treatment and may require additional rehabilitation or rest from exacerbating activities.
Patients who do not respond to this initial regimen are treated with injection of low-dose triamcinolone acetonide. The senior author (F.H.S.) prefers to use 1 mL of 2% plain lidocaine hydrochloride and 10 mg of cortisone, injected posteriorly, int the region of maximal tenderness (see figure 2). If the injection is placed properly, the peroneal nerve should not be at risk of injury.4,5 Typically, the injection is both therapeutic and diagnostic because most patients report near complete resolution of pain and tenderness.
The Current Status
Popliteus tendinitis is important to recognize because it often is severe enough to prevent athletic participation, but it also usually responds quickly to appropriate management. Diagnosis is based on a careful history and examination. Inflammation can be treated with NSAIDs, but injection is reserved for refractory cases. The key to successful and lasting improvement is inclusion of a therapy program for the quadriceps that strengthens and improves muscle endurance.
We thank Michael Thorpe, MD, for his assistance in reading the MRI results.
Dr Petsche completed a sports medicine fellowship at HealthSouth Doctors' Hospital in Miami and is now an orthopedic surgeon in private practice in Geneva, Illinois. Dr Selesnick is an orthopedic surgeon and director of the Miami Sports Medicine Fellowship at the HealthSouth Doctors' Hospital in Miami. He is also team physician for the National Basketball Association's Miami Heat. Address correspondence to F. Harlan Selesnick, MD, 1150 Campo Sano Ave, Suite 301, Coral Gables, FL 33146.
Disclosure information: Drs Petsche and Selesnick disclose no significant relationship with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.