Anatomic patellar instability risk factors in primary lateral patellar dislocations do not predict injury patterns: an MRI-based study

Abstract

for this injury due to clinician-perceived need for cartilage debridement. MPFL injury severity was complete rupture (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%). Chondral injury 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 patients had a greater risk of isolated patellar MPFL and chondral injury. No clear relationship was found between/across the location and/or severity of bone bruising, MPFL, or chondral injury. Clinical relevance Underlying anatomic patellar instability risk factors defined by MRI, do not predict injury patterns. MPFL and chondral injury, as well as bone bruising, 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/chondral injury being more common in the skeletally immature patient. 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 patellar dislocations. Level of evidence Case series, Level IV. AbstractPurpose 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 patients 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 ligamentous injury. On MRI, location of cartilage, medial patellofemoral ligament (MPFL) injury, and bone bruising were noted. Severity was categorized as partial or complete for MPFL and cartilage lesions. Anatomic patellar instability risk factors (patella alta, trochlear dysplasia, increased TT-TG, and lateral patella tilt) were recorded and compared to the injury patterns. Results This study involved 157 patients; 107 patients were skeletally mature. Of the 157 patients, 26 had surgery

Operative Repair of Medial Patellofemoral Ligament Injury Versus Knee Brace in Children With an Acute First-Time Traumatic Patellar Dislocation: A Randomized Controlled Trial

“…5,29,64 In adults, there are more femoral-based lesions than in children, but the injury is most commonly multifocal and often involves the patellar attachment site. 21,51,60,62,65 The association of APIFs and a redislocation is well established in the adult population. 3,8,14,19,22,38,52 A high incidence of APIFs has also been described in children, but surgery in children with open growth plates faces limitation when addressing the correction of APIFs.…”

Evaluation of risk correlation between recurrence of patellar dislocation and damage to the medial patellofemoral ligament in different sites caused by primary patellar dislocation by MRI: a meta-analysis

“…For example, the sample size of Sillanpaa et al was relatively small, among which only a total of 6 patients had patellar attachment injury, which resulted in no recurrence of patellar dislocation [23]. It is also believed that the probability of MPFL injury is higher in children or adolescents with primary traumatic patellar dislocation, and the injury sites are mostly located at their patellar attachment, while the probability of femoral attachment or combined of MPFL injury in adults is higher than that in children or adolescents [6,[28][29][30][31][32]. In the included study, only one article limited the patient population to adolescents [24], while the other four articles were a combination of adolescents and adults, which might be an important cause of the inapparent difference found among the Fig.…”

Isolated Avulsion Fracture of Patellar Attachment of Medial Patellotibial and Medial Patellomeniscal Ligaments in the Presence of Trochlear Dysplasia: An Indication for Acute Surgical Repair

“…Current knowledge supports that MPML/MPTL injury may be a prerequisite for the patella to dislocate [1,2,13]. MPTL and MPML are stiffer than MPFL and, therefore, may rupture with less deformation, or even without patellar dislocation and MPFL injury [2,11,13]. In the presented case, avulsion of the common patellar attachment of MPTL/MPML, combined with a dysplastic, shallow trochlea and a hypoplastic medial condyle, resulted in patellar dislocation without concomitant MPFL rupture.…”