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Right ACL Reconstruction 6 month post op DARI Clinician Report
The DARI reporting can be helpful in determining whether a patient’s movement is still compromised due to an injury or surgical procedure. The clinician will generally consider any additional clinical information while reviewing the report. For example, if the quadriceps consistently tests weak, it may reflect in datapoints across the entirety of the screen. It is always helpful for the clinician to understand the biomechanical definition of each datapoint, but just as importantly, how an injury or surgical procedure may manifest in each datapoint. By providing case studies, we hope to elucidate some of the common deficiencies that we see at different time-stamps in the rehabilitation process to help the clinician work through the data in an efficient and effective manner.
This DARI Clinician Report is from a right ACL reconstruction patient who was 6 months post op. All of the compensations that will be discussed in this review are quite common from the data the DARI team has reviewed. Apart from the data discussed below, we expect to see increases in excursions (e.g. squat depth and jump height) as the patient progresses through rehab.
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Starting with the bilateral squat motion, we can see a 19.4% weight shift to the left. This is most likely an avoidance pattern that is common during bilateral movements. As we review the other bilateral movements in the screen, we will look for similar compensations to determine if this is a consistent pattern in the patient’s movement.
During the unilateral squat motions, the patient exhibited a 3.6 cm asymmetry in pelvic excursion, which was less on the right and crossed the 10% difference threshold to result in this value being flagged. We can see that the patient had 9.6° more hip flexion on the right, but 13.3° less knee flexion, and 11° less ankle flexion. Asymmetries in knee flexion are quite common among those patients who have had a knee procedure and often result in pelvic excursion asymmetries. We can also see the patient had elevated hip adduction and dynamic valgus bilaterally, which is a commonly identified risk factor for ACL injuries. Finally, the knee being highlighted indicates the patient loaded into their knees first, but the elevated trunk-to-shin flexion on the right indicates the patient loaded the knee less and the hip more to obtain more depth during the movement.
During the front lunge motions, the patient exhibited an 11.3° difference in knee flexion and 6.4° difference in ankle flexion, both of which were less on the right and crossed the 10% difference threshold. Large differences in knee flexion during this partially loaded motion are typically less common during advanced stages of rehabilitation and more common during early stages.
During the step down motions, the patient exhibited -18° degrees of pelvic obliquity (pelvic drop) with the right leg as the stance leg and -8.2° of pelvic obliquity with the left leg as the stance leg. This asymmetry (9.8°) in pelvic drop is a very common deficiency when the patient is uncomfortable placing high loads into the knee. This may be a result of pain, poor activation, or poor eccentric strength, but the patient will ultimately reach with the contralateral leg to avoid further loading the knee, resulting in pelvic drop. This is often accompanied by a sharp increase in the rate of descent (indicating a loss of control), which can be visualized in the SAGE tool. Increases in hip adduction and dynamic valgus are also very common during the step down.
During the vertical jump motion, the patient exhibited a 196 N difference in weight distribution during the takeoff phase and a 141 N difference during the landing phase, with more weight on the left leg during both phases. Here, we can see consistency with the bilateral squat and will continue to see this pattern during the other bilateral jumps.
During the unilateral vertical jump motions, hip, knee, and ankle loading and landing flexion all exceeded the 10% difference threshold with less flexion on the right. Meanwhile, there was only a 2.6 cm difference in the jump height. The asymmetry in the landing flexion angles resulted in a 14.5 cm difference in the landing excursion and a greater landing ground reaction force on the right. During the late stages of rehab, it is very common to see the jump height become more symmetrical, while the knee flexion and the variables under the category “stiffness" often remain asymmetrical. The high stress on the knee joint during the landing phase of motion makes mitigating this asymmetry of utmost importance.
During the drop jump motion, the patient exhibited a 329 N difference in weight distribution during the takeoff phase and a 306 N difference during the landing phase, with more weight on the left leg during both phases. The weight shifts during this motion tend to be more pronounced as the initial drop followed by the jump requires quick absorption and change in direction. The patient also demonstrated an increase in dynamic valgus during the “loading” phase of the jump. It’s important to note that this datapoint includes both the absorption and takeoff phases of the jump as the valgus collapse is common during amortization and the takeoff phase. The drop jump is a popular screening tool for ACL tear risk partially because it often elucidates valgus collapse.
During the concentric jump motion, the patient exhibited a 359 N difference in weight distribution during the takeoff phase and a 400 N difference during the landing phase, with more weight on the left leg during both phases. We have now seen an avoidance of the right leg during all of the bilateral movements in the screen.
During the lateral bound motions, the patient exhibited a 28.3° difference in hip flexion and a 9.4° difference in knee flexion during the landing phase of the first jump with less flexion on the right. Dynamic valgus was also elevated on the right side during the landing phase. The peak takeoff and landing ground reaction force was actually greater on the left leg, but since the landing presented is ultimately followed by a second jump, the “stiffness” category is not a pure representation of the patient’s ability to attenuate landing forces as with the other movements.
To summarize, the patient exhibited significant weight shifts to the left during all bilateral movements, demonstrated asymmetries in strength and control during the unilateral movements and subsequently had difficulty attenuating landing forces unilaterally.
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