MDCalc

Recurrent Instability of the Patella (RIP) Score

Predicts risk of recurrent instability after primary patellar dislocation.

Age <25 years
Skeletal immaturity
Open distal femoral and proximal tibial physes on plain radiographs
Dejour A-D dysplasia
On plain radiographs and T2-weighted MRI
TT-TG/PL ≥0.5
On T2-weighted MRI

Result:

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Advice

  • 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).

Management

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.

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