PURPOSE: The primary goal was to describe the injury patterns in a population of primary (first time) lateral patellar dislocators (LPD) to lend clarity to commonly held notions about injury patterns in this population. METHODS: A prospective study identifying @entity1 presenting with LPD between 2008 and 2012. Inclusion criteria were a history and physical exam consistent with primary LPD, and an MRI consistent with the diagnosis without other significant @entity130 . On MRI, location of cartilage, medial patellofemoral ligament (MPFL) injury, and bone @entity2981 were noted. Severity was categorized as partial or complete for MPFL and cartilage lesions. @entity4142 patellar instability risk factors ( @entity12352 , @entity6125 , @entity101 , and lateral patella tilt) were recorded and compared to the injury patterns. RESULTS: This study involved 157 @entity1 ; 107 @entity1 were skeletally mature. Of the 157 @entity1 , 26 had surgery for this injury due to clinician-perceived need for cartilage debridement. MPFL injury severity was @entity397 (N   =   69, 44%), partial (N   =   67, 43%), and none (N   =   19, 13%). MPFL injury location was isolated femoral (N   =   16, 10%), isolated patella (N   =   26, 17%), isolated mid-substance (0%), multiple locations (N   =   95, 61%), and none (N   =   20, 13%). @entity130 location was patella (N   =   67, 43%), lateral femoral condyle (N   =   11, 7%), multiple locations (N   =   53, 34%), and none (N   =   26, 17%). A majority (61%) of patellar chondral lesions were at its inferomedial aspect; all medial patellar retinacular partial injuries involved the inferomedial aspect of the patella, consistent with the insertion of the medial patellotibial ligament (MPTL). Skeletally immature @entity1 had a greater risk of isolated patellar MPFL and @entity130 . No clear relationship was found between/across the location and/or severity of bone @entity2981 , MPFL, or @entity130 . CLINICAL RELEVANCE: Underlying anatomic patellar instability risk factors defined by MRI, do not predict injury patterns. MPFL and @entity130 , as well as bone @entity2981 , are common following LPD. The medial patellotibial ligament is torn in patellar-based medial retinacular injuries, based on MRI injury location. Skeletal immaturity plays a role in the location of the injury pattern with isolated patellar-based MPFL/ @entity130 being more common in the skeletally immature @entity1 . Sex does not appear to be a factor in injury patterns after primary LPD. Knowledge of these injury trends will help focus the clinician in injury evaluation when managing primary @entity8043 . LEVEL OF EVIDENCE: Case series, Level IV.

@entity4142 patellar instability risk factors in primary XXXX do not predict injury patterns: an MRI-based study.

@entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity101 :: ('MESH:D006973', 'Disease') :: ['increased TT-TG'] @entity4142 :: ('MESH:D020763', 'Disease') :: ['Anatomic'] @entity397 :: ('MESH:D012421', 'Disease') :: ['complete rupture'] @entity12352 :: ('MESH:C535568', 'Disease') :: ['patella alta'] @entity6125 :: ('MESH:D020432', 'Disease') :: ['trochlear dysplasia'] @entity8043 :: ('MESH:D031222', 'Disease') :: ['patellar dislocations'] @entity2981 :: ('MESH:D003288', 'Disease') :: ['bruising'] @entity130 :: ('MESH:D014947', 'Disease') :: ['ligamentous injury', 'chondral injury', 'Chondral injury']
@entity8043 :: (MESH:D031222,Disease) :: ['lateral patellar dislocations']
