Today, my chiropractic health assistant and I are writing about a rare and often misdiagnosed condition associated with the knee joint and tissue structure surrounding the knee. There are various knee conditions such as Anterior Cruciate Ligament Strain/Sprains/Tears (ACL), Posterior Cruciate Ligament Strain/Sprains/Tears (PCL), Meniscus irritation, and Patellofemoral Arthralgia that get diagnosed correctly. However, at times, a simple strain/sprain/tear injury to the muscles at the back of the knee goes undetected.
Just the other day, a 30 year old runner came into the clinic complaining of posterior (back of the knee) pain. The knee pain started after he ran 5km over the weekend. The patient went to his medical doctor and his doctor indicated to rest and ice the knee. The medical doctor referred the patient to our chiropractic clinic for further physical investigation.
We tested the knee for any Anterior Cruciate Ligament (ACL), Posterior Cruciate Ligament (PCL), Medical/Lateral Collateral Ligament, and menisci damage. All the tests were negative. The patient explained that he felt the pain most when we touched the back area of the knee (mushy area) while in a flexed position. No baker cysts (small ball like structure that can be felt at the back of the knee) were felt. The patient also explained that he felt pain while we tested his knee flexion. We quickly understood the cause of his pain. This rare condition is called Popliteus Syndrome or Popliteus Strain.
The Popliteus knee muscle is responsible for internal rotation of the shin bone (tibia) as well as for unlocking the knee joint when bending the knee from a fully straightened position (extended position). The popliteus muscle originates from outside surface of the knee and goes on to attach to the back aspect of the inside area below the knee joint.
This muscle is often injured through acute injury (sport injuries, car accident or fall) or overuse.
Acute injuries to the popliteus occur after a significant force to the knee. They are common in road traffic accidents or falls where the knee is extended. Popliteus injuries may occur in association with other knee injuries occurring to the ACL, PCL, Meniscus and Collateral ligament. Thus, it is important to screen for this muscle injury at all times and especially in the presence of other knee injuries.
Overuse injuries to the popliteus muscle develop gradually and are most common in runners. They tend to be due to biomechanical issues (foot issues) and tight hamstring muscles, quadriceps and calf muscles. We explained this to our patient.
We went forward by treating the patients knee joint. We started with therapeutic ultrasound, laser therapy and electrotherapy to the posterior/back area of the knee. Following this, we proceeded with soft tissue therapy (15 minutes) to the popliteus and stretched the calfs, hamstrings and quadriceps. The patient returned the next day for a second treatment. After the second treatment, the patient explained that he was much better and did not experience any more locking/pain in the knee joint. The patient went back into training in a progressive fashion (1km added to each day without pain). We made sure that the patient followed proper warm up and stretching instructions in order to prevent the injury from reoccurring. Two weeks following the injury, the patient returned to explain that he ran 5km with no issues.
As one can see, it can be easy to ignore this muscle especially with the other knee areas/injuries/concerns that are often more common. It is critical to always evaluate all the soft tissues in the knee area (fascia, tendons, muscle, and ligament) in order to avoid missing this often under/misdiagnosed injury. If you have any feedback or comments, please write to us.
MEDICAL DISCLAIMER: The following information is my personal notes about this subject matter. It is intended for informational purposes only. Consult a health practitioner to help you diagnose and treat injuries of any kind.
Dr. Luciano Di Loreto, HBSc., DC
Chiropractor in Woodbridge, Ontario