Current Concepts for Patellar Dislocation

Abstract

Context:Patellar dislocation usually occurs to the lateral side, leading to ruptures of the Medial Patellofemoral Ligament (MPFL) in about 90% of the cases. Even though several prognostic factors are identified for patellofemoral instability after patellar dislocation so far, the appropriate therapy remains a controversial issue.Evidence Acquisition:Authors searched the Medline library for studies on both surgical and conservative treatment for patellar dislocation and patellofemoral instability. Additionally, the reference list of each article was searched for additional studies.Results:A thorough analysis of the anatomical risk factors with a particular focus on patella alta, increased Tibial Tuberosity-Trochlear Groove (TT-TG) distance, trochlear dysplasia as well as torsional abnormalities should be performed early after the first dislocation to allow adequate patient counseling. Summarizing the results of all published randomized clinical trials and comparing surgical and conservative treatment after the first-time patellar dislocation until today indicated no significant evident difference for children, adolescents, and adults. Therefore, nonoperative treatment was indicated after a first-time patellar dislocation in the vast majority of patients.Conclusions:Surgical treatment for patellar dislocation is indicated primarily in case of relevant concomitant injuries such as osteochondral fractures, and secondarily for recurrent dislocations.

Knee pain in a 15 year old boy

“…10 It is unusual for the patella to dislocate without a substantial injury, and up to 72% of first time patellar dislocations occur secondary to sports injuries. 11 However, there are risk factors for traumatic, non-traumatic, and recurrent patella dislocations.…”

“…12 Other reviews quote an equal distribution between sexes. 11 A review by Petri et al highlights several key anatomical risk factors that should be considered, including patella alta, trochlea dysplasia, an increased tibial tuberosity-trochlear groove distance and torsional abnormalities, 11 such as valgus knees and increased hip anteversion. Some of these have been previously analysed on knee CT scans in patients with symptomatic patellar instability and showed trochlear dysplasia in 85% of cases, an increased tibial tuberosity-trochlea groove distance in 56%, and patella alta in 24%.…”

Management of traumatic patellar dislocation in a regional hospital in Hong Kong

“…Reconstruction of MPFL alone is indicated in the presence of a physiological TT-TG distance (<20 mm) and no significant trochlear dysplasia. 25 Patients with increased TT-TG distance of >15 to 20 mm have been shown to have patellar instability. 26 Thus, tibial tubercle osteotomy procedures, aiming to shift the tibial tubercle medially to correct the TT-TG distance to within physiological limits of around 9 to 15 mm, with or without concomitant MPFL reconstruction have been advocated for these patients.…”

“…26 Thus, tibial tubercle osteotomy procedures, aiming to shift the tibial tubercle medially to correct the TT-TG distance to within physiological limits of around 9 to 15 mm, with or without concomitant MPFL reconstruction have been advocated for these patients. 25 The cut-off point of 20 mm above which tibial tubercle osteotomy is indicated has been well accepted by most orthopaedic surgeons. [26][27][28][29][30] One study has shown that 18% of recurrent patellar dislocators had TT-TG distances of >20 mm.…”

“…31 For patients with significant trochlear dysplasia, trochleoplasty procedures have been advocated. 25 There have been no prospective randomised controlled trials to date comparing conservative treatment and the various surgical treatment modalities for recurrent patellar dislocators. Short-term results of these various surgical procedures have been satisfactory, however.…”