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Trochleoplasty improves knee flexion angles and quadriceps function during gait only if performed bilaterally



To investigate if a trochleoplasty increases knee flexion angles and extensor moments in the gait of patients with patellar instability and to compare postoperative gait to a healthy control group.


A bilateral dislocation group (6 patients) and a unilateral dislocation group (14 patients) were treated with bilateral and unilateral trochleoplasty, respectively. Kinematics and kinetics of the lower extremity were captured using 3D-gait analysis (VICON, 12 cameras, 200 Hz, plug-in-gait, two force plates). The mean of six trials was computed. The gait cycles were compared pre to postoperatively for each group. The gait of the two groups was compared to each other and the gait of a healthy population (54 knees).


After trochleoplasty, the knee flexion angles and knee extensor moments only increased in the bilateral dislocation group, whereas the gait pattern of the unilateral dislocation group remained unchanged. Compared to the healthy population, the postoperative gait pattern of the bilateral dislocation group did not differ. In contrast, knee flexion angles and extensor moments of the unilateral dislocation group were still lower.


In adolescents with bilateral recurrent patellar dislocations, trochleoplasty of both knees increases knee flexion angles and knee extensor moments comparable to normal gait. Unilateral symptomatic patients undergoing a unilateral trochleoplasty did not achieve normal walking. These findings point out that patellar instability should be considered as a bilateral problem, even in patients with unilateral dislocations.

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Correspondence to Carlo Camathias.

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This experimental research has been performed with the approval of the local ethics committee (Ethics Committee of Basel, Nr. 2013/112). Research is in compliance with the Helsinki Declaration.

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Ammann, E., Meier, R.L., Rutz, E. et al. Trochleoplasty improves knee flexion angles and quadriceps function during gait only if performed bilaterally. Knee Surg Sports Traumatol Arthrosc 28, 2067–2076 (2020).

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  • Patella dislocation
  • Patellar dislocation
  • Patellar instability
  • Recurrent dislocation
  • Knee
  • Trochlear dysplasia
  • Trochleoplasty
  • Kinematics
  • Kinetics
  • Gait analysis
  • Quadriceps avoidance
  • Adolescents