Case Report: Female Runner with Bilateral Knee Pain, Part 2

Prior to reading, please check out Case Report: Female Runner with Bilateral Knee Pain, Part 1.

The patient described was a friend that I evaluated after her symptoms continued to worsen, even after over a month of physical therapy and a cortisone shot. Following my initial evaluation, I instructed and prescribed a home exercise program (HEP) that targeted the ‘weak’ hip musculature and altered biomechanics, especially evident during running. I also recommended holding back on her current training program until her symptoms were under control. Once under control, a proper well progressed aerobic training program would be initiated.

A few weeks following the evaluation, she returned to her physician who ordered an MRI to rule out any significant underlying pathology. The MRI report was negative for any significant meniscal or articular cartilage pathology. However, the report did find substantial Bilateral Femoral Shaft Stress Fractures, which were not picked up on the initial x-ray report!

According to Monteleone et al and Matheson et al, femoral shaft stress fractures make up only 5-7% of all stress fractures. They also found that the overall incidence of bilateral stress fractures is ~16.6% of all cases, but I have to imagine there is an even smaller population suffering from fractures to the femoral shaft. Not only is this a rare pathology, but it is an equally difficult injury to diagnose. Harrast et al report that the referral pattern is highly variable, potentially affecting the groin, thigh, and/or knee regions. Additionally, palpation of the affected area is unreliable due to the amount of soft-tissue that overlies the femoral shaft. This is almost always caught as a diagnosis of exclusion or as a result of failed conservative treatment. The difficulty in diagnosis does not stop at the physical examination as initial radiological testing only has a sensitivity of 15-35%. This injury is typically not found until symptoms continue to worsen and an MRI is ordered (sensitivity of 100%, specificity of 85%). So, just because the x-ray report is negative does not mean it should be ruled out as a potential causative factor.

So, what causes a femoral shaft stress fracture?

A biomechanical study published by Edwards et al found that the largest bending moments about the A-P axes of the proximal femur occur during the impact phase of loading response. The direction of this bending moment in addition to the axially oriented compressive force would place the largest stress on the medial aspect of the femur. This stress may become even more pronounced during training after the hip abductors (resist the AP bending moment) begin to fatigue or are already weak prior to activity.

Obviously, this is not a typical case, but what could have been done to arrive at this conclusion from day one?

Johnson et al investigated the utility of a new (at the time) clinical test to aid in the early diagnosis of femoral stress fractures. The fulcrum test is conducted with the patient seated with legs dangling over the edge of the table. The therapist’s arm is positioned under the thigh and is used as a fulcrum as gentle inferiorly directed pressure is applied to the anterior knee by the opposite hand, just proximal to the patella. A positive finding is a sharp pain produced at the site of potential fracture (video demonstration provided below). Unfortunately this was a case series and only mentioned the use of the test, but did not provide data on specificity, sensitivity, or positive predictive value, nor has there been a study done to determine these values since. Speaking in terms of biomechanical/pathological plausibility, this test does seem to be worth incorporating in individuals who have a suspected femoral stress fracture, but there is currently no evidence to support its widespread use. Additionally, Clement et al found that approximately 70% of individuals with a femoral stress fracture will complain of anterior thigh pain during the single-leg hop test (video demonstration provided below). These additional clinical tests could have increased the likelihood of early detection, but the ability to consistently catch this injury remains allusive.

This case shows us that we, as healthcare providers, must continually assess and reassess our patients. If our conservative measures are not improving or are potentially worsening symptoms, a change needs to be made. The plan of care provided was appropriate for the patient’s clinical presentation, but unfortunately it was not as simple as it originally seemed. Sometimes, a patient’s pain is secondary to serious pathology and without reassessment, it would have never been found and appropriate treatment would not have been provided.

Now that a diagnosis is firmly in place, where would you go from here?

(Video Credit: DPT2012diffd)

(Video Credit: Brian Schiff)

Case Report: Female Runner with Bilateral Knee Pain, Part 1

Subjective Interview:

This patient is a healthy, young female who presents with a primary complaint of bilateral anterior knee pain. These symptoms began shortly after beginning intensive training for a half-marathon, which she has been participating in for a few months now. In the beginning, the pain would not begin until the end of the run, then progressed to the middle of the run, and finally now is present throughout the entire run. She actually experiences pain during activities of daily living at this point as well. This pain is described as diffuse general knee pain that can vary between anterior and posterior knee regions with the right knee being more symptomatic than the left. The pain has not radiated distal or proximal to the knee region. There was no traumatic incident that brought on the symptoms. Additionally, she experiences pain during weight-bearing functional activities (squats, lunges, ect.) with increasing angles of knee flexion leading to increased pain. Her primary goal at the time of evaluation was to be pain-free and prepared to complete her half-marathon (~1 month away). Her primary care physician performed x-ray imaging and found minimal joint space narrowing of the medial tibiofemoral compartments bilaterally. There were no other significant findings from this radiological report.

Examination Findings:

Upon static observation, she demonstrates fairly significant genu varum, squinting patellae, and ‘toe-in’ bilaterally. Prior to beginning examination, fracture at the knee region was ruled out via the Ottawa Fracture Rules and prior radiological findings.

Movement analysis utilizing the lateral step-down and drop jump tasks showed several areas of concern. The lateral step down showed an uncompensated trendelenburg posture at the pelvis with a forward trunk lean. Additionally, the drop jump task showed decreased knee flexion with her knees extending well past her toes at impact. Both tasks elicited pain with the drop jump being most problematic.

During the physical examination, she stated tenderness to palpation of medial and lateral joint-lines bilaterally, but no significant findings with palpation to the soft tissue structures in the knee region.

Range of motion testing indicated a small deficit bilaterally in knee flexion/extension with increased pain associated with end-range knee flexion. There were no significant findings at either the hip or ankle in terms of ROM limitation. Crepitiation was noted throughout entire knee flexion/extension ROM. Accessory motion was WNL for tibiofemoral, patellofemoral, and tibiofibular motion.

Manual muscle testing results seem to indicate a bilateral limitation in hip abduction, external rotation, and extension strength with no deficits found in the musculature at the knee. She did experience pain with knee flexion and extension, but this pain did not implicate the hamstring or quadriceps musculature as the pain was once again a diffuse general knee pain and could not be localized to these specific muscle groups or their associated connective tissue.

Based on the prior examination findings, meniscal pathology seemed to be a likely hypothesis as 2 variables identified by Lowery et al to be indicative of a meniscus tear were present (pain with passive knee flexion and joint-line tenderness). With these 2 findings alone, they found that there was a specificity of 71.6%, sensitivity of 51.4%, and a positive predictive value of 65.5%. Unfortunately, no other factors were present in this patient to help increase the likelihood of this diagnosis (McMurray Test, pain with Modified Bounce-Home Test, and history of catching/locking were all negative). Patellofemoral special testing indicated a lateral pull of the patella and pain following the patellar compression test. Both of these implicate potential mal-tracking and subsequent altered patellofemoral contact area and articular cartilage damage. This suspected altered contact area did correlate well with the findings of the movement analysis and manual muscle testing.

So, if this was your patient, what would you hypothesize the underlying pathology to be? What else would you test? How would you move forward with treatment?