Mayo Clinic's researchers in sports medicine have determined the predisposing factors that lead to patellar subluxation and dislocation. Individualized treatment by a multidisciplinary team improves pain, prevents recurrent instability and restores function.
Faculty members collaborating on research related to patellar instability treatment include:
The RIP score predicts risk for recurrent patellar instability based on age, skeletal maturity, trochlear dysplasia and TT-TG/PL ratio.
Hevesi M, Heidenreich MJ, Camp CL, Hewett TE, Stuart MJ, Dahm DL, Krych AJ. The recurrent instability of the patella score: A statistically based model for prediction of long-term recurrence risk after first-time dislocation. Arthroscopy. 2019;35:537.
Combining TTO and MPFL reconstruction results in a high rate of stability and return to sport, despite the presence of trochlear dysplasia in nearly three-fourths of patients.
Allen MM, Krych AJ, Johnson NR, Mohan R, Stuart MJ, Dahm DL. Combined tibial tubercle osteotomy and medial patellofemoral ligament reconstruction for recurrent lateral patellar instability in patients with multiple anatomic risk factors. Arthroscopy. 2018;34:2420.
MPFL reconstruction reduces patellar height in two-thirds of patients with patella alta, perhaps making distalization unnecessary in a subset of operatively treated patients with patellar instability.
Woodmass JM, Johnson NR, Cates RA, Krych AJ, Stuart MJ, Dahm DL. Medial Patellofemoral Ligament Reconstruction Reduces Radiographic Measures of Patella Alta in Adults. Orthopaedic Journal of Sports Medicine. 2018;6:2325967117751659.
First-time patellar dislocation is similar among male and female patients and highest in ages 14 to 18 years.
Sanders TL, Pareek A, Hewett TE, Stuart MJ, Dahm DL, Krych AJ. Incidence of first-time lateral patellar dislocation: A 21-year population-based study. Sports Health. 2018;10:146.
Recurrence over 20 years after first-time patellar dislocation is influenced by age younger than 18, trochlear dysplasia, TT-TG distance, patella alta and female sex.
Christensen TC, Sanders TL, Pareek A, Mohan R, Dahm DL, Krych AJ. Risk factors and time to recurrent ipsilateral and contralateral patellar dislocations. The American Journal of Sports Medicine. 2017;45:2105.
Twenty percent of skeletally immature patients with patellar dislocation will develop symptomatic patellofemoral arthritis by age 20 years.
Sanders TL, Pareek A, Hewett TE, Stuart MJ, Dahm DL, Krych AJ. High rate of recurrent patellar dislocation in skeletally immature patients: A long-term population-based study. Knee Surgery, Sports Traumatology, Arthroscopy. 2018;26:1037.
Concomitant TTO may delay return to sport after MPFL reconstruction in athletes.
Krych AJ, O'Malley MP, Johnson NR, Mohan R, Hewett TE, Stuart MJ, Dahm DL. Functional testing and return to sport following stabilization surgery for recurrent lateral patellar instability in competitive athletes. Knee Surgery, Sports Traumatology, Arthroscopy. 2018;26:711.
Nearly half of patients with patellar dislocation have evidence of patellofemoral arthritis at 25 years, and those with osteochondral injury, recurrent instability and trochlear dysplasia are at highest risk.
Sanders TL, Pareek A, Johnson NR, Stuart MJ, Dahm DL, Krych AJ. Patellofermoral arthritis after lateral patellar dislocation: A matched population-based analysis. The American Journal of Sports Medicine. 2017;45:1012.
Patellar instability ratios may be more effective in predicting recurrence of instability than TT-TG distance alone.
Camp CL, Heidenreich MJ, Dahm DL, Stuart MJ, Levy BA, Krych AJ. Individualizing the tibial tubercle-trochlear groove distance: Patellar instability ratios that predict recurrent instability. The American Journal of Sports Medicine. 2016;44:393.
A TT-PCL distance greater than 24 is less predictive of recurrent patellar instability than a TT-TG distance greater than 20, and measuring TT-PCL distance may prove useful in the setting of a TT-TG distance less than 20.
Heidenreich MJ, Camp CL, Dahm DL, Stuart MJ, Levy BA, Krych AJ. The contribution of the tibial tubercle to patellar instability: Analysis of tibial tubercle-trochlear groove (TT-TG) and tibial tubercle-posterior cruciate ligament (TT-PCL) distances. Knee Surgery, Sports Traumatology, Arthroscopy. 2017;25:2347.