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      Calc Function

    • Calcs that help predict probability of a diseaseDiagnosis
    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
    • Disease is diagnosed: prognosticate to guide treatmentPrognosis
    • Numerical inputs and outputsFormula
    • Med treatment and moreTreatment
    • Suggested protocolsAlgorithm





    Chief Complaint


    Organ System


    Patent Pending

    Recurrent Instability of the Patella (RIP) Score

    Predicts risk of recurrent instability after primary patellar dislocation.
    When to Use
    Why Use

    Patients with a first-time patellar dislocation (adults and adolescents).

    • Does not take into account uncommon risk factors such as excessive femoral internal rotation, excessive valgus limb alignment, or generalized patholaxity (e.g. as in Ehlers-Danlos syndrome).

    • Not applicable for obligate flexion dislocation.

    • Chondral or osteochondral fractures are managed differently.

    • Relevant to most presentations of first-time patellar dislocations.

    • Includes physeal status (physeal closure may be imminent).

    • Does not take into account the site of the medial patellar restraint tear (femoral tears have a higher rate of recurrent patellar instability).

    • Can be used to educate patients and parents on the risk of future patellar dislocations after the first episode.

    • Aid in discussion during informed consent for operative and nonoperative management of first-time patellar dislocators.

    • Can be an objective factor in deciding between operative and nonoperative management of a first-time patellar dislocation.



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    Next Steps
    Creator Insights


    • Exam: in addition to standard knee examination plus patellar tracking, “J” and evidence of obligatory dislocation (flexion dislocators are appropriate for RIP scoring), assess internal rotation of the hip/femur in prone position. If >45 degrees, obtain rotational imaging study; assess laxity with Beighton scoring, and if elevated obtain a specific diagnosis, e.g. Ehlers-Danlos type.

    • Radiographs: in addition to assigning Dejour trochlear type, Caton Deschamps patellar height ratio, and tilt, assess mechanical axis for evidence of excessive limb valgus.

    • MRI: Assess TT-PCL in addition to TT-TG and patellar height; assess for chondral and osteochondral fracture and loose bodies (medial patella and lateral aspect lateral femoral condyle).


    Physical examination and imaging findings should be included to allow a rational final course of action.

    Critical Actions

    Assess for other factors that can influence the decision between operative and nonoperative management.

    About the Creator
    Dr. Mario Hevesi