Clinical Cases ProbeFix Dynamic


1 Use case: ACL injury

For a young woman, starting a professional football career at RCD Espanyol, a ruptured ACL injury will be devastating. Such injury is quite common among athletes and individuals engaged in physical activities. The road of recovery consists of a rehabilitation program to get the athlete back on the field as soon as possible. In such programs, the Usono ProbeFix Dynamic offers a unique opportunity to effectively monitor the injury for optimal recovery.

Rubén Cabanillas, a physiotherapist and ACL rehab specialist, uses the ProbeFix Dynamic and a GE Vscan air to visualize the speed of the quadriceps contraction during exercise in real time. Shortly after the ACL rupture, the speed will be rather slow, but will increase with the progression of the ACL recovery.



As soon as the athlete experiences unease or pain; this is characterized by indicators such as a swollen, unstable knee that is too painful to bear weight on, in case of an ACL injury, a doctor is first consulted to form a diagnosis. Static ultrasound may be used to come to the diagnosis of a ruptured ACL.

Treatment plan

Based on the diagnosis, a treatment plan is proposed by the medical team. This plan consists of multiple different exercises to regain strength and stability. Depending on the athlete, one or multiple sessions are planned each week. Then over a couple of weeks, the pain and movement of the client is tracked, and the exercises are adjusted accordingly. The ProbeFix Dynamic is particularly helpful in providing additional information about the progress of ACL recovery, with the goal of improving the decision-making process in the treatment plan.

To identify the speed of contraction, the athlete is asked to execute a simple exercise, such as an isolated knee extension, while a ProbeFix Dynamic and an ultrasound probe are attached to the quadriceps. The probe is placed over the Rectus Femoris, perpendicular to the fascicles of this muscle. These fascicles are visualized in the ultrasound image.

The first session will take place within the first few days after the injury, in which a suitable exercise is determined. During this session, the baseline is determined of the state of the muscle. In most cases, the muscle does have a shaky and slow contraction right after surgery.
During each next session, the exact same exercise will be performed, and the speed of contraction is qualitatively compared to prior assessments. Because the contraction is fast for a healthy ACL and slow and shaky for an injured ACL, the physiotherapist is able to track the progress of the ACL. For the comparison over time, it is particularly important that the exercise is performed under similar conditions as during prior sessions, because the speed of the contraction is strongly dependent on factors such as the type of exercise, and the length of the muscle at which the speed is qualified.

In the initial treatment plan, the rehabilitation is expected to take 9 to 12 months to regain full strength and stability. After 5 months, the ultrasound already showed a relatively fast contraction of the Rectus Femoris. This knowledge is used to adjust the prescribed exercises to the capabilities of the athlete, with as end result a shorter rehabilitation period.


Key Findings

With the ProbeFix Dynamic, a physiotherapist can use imaging during sport specific exercises to qualify the speed of contraction in the Rectus Femoris in real time. Such measurements can be performed over time to identify the actual state of the ACL recovery progress. The rehabilitation exercises can be adjusted accordingly. This is particularly beneficial for professional athletes, as it has been shown to shorten the return to play time with days.

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