Patellofemoral surgeons know the drill.
You perform a technically demanding Bereiter trochleoplasty for high-grade trochlear dysplasia. The groove looks beautiful. Tracking is restored. Instability is addressed.
And then, at three months, the knee won’t bend.
Post-operative stiffness after trochleoplasty is common enough — especially when arthroscopically assisted manipulation (AAM) enters the picture. Historically, subsequent surgery has been associated with worse outcomes.
A new prospective cohort study of 374 Bereiter trochleoplasties asks a straightforward but clinically important question: If a patient develops stiffness and requires AAM, are their 2-year patient-reported outcomes worse?
The answer may surprise you.
Copenhagen’s Algorithm Under the Microscope
The study followed 374 consecutive knees with high-grade trochlear dysplasia treated according to the Copenhagen patellofemoral instability (PFI) algorithm.
At three months: Extension deficit >10° and/or Flexion <120°…qualified as post-operative stiffness.
Those patients underwent AAM with removal of adhesions and scar tissue.
Outcomes were measured using: Kujala score, KOOS and Lysholm score.
Assessed at 1 and 2 years.
How Common Is Stiffness?
Out of 374 knees: 49 patients (12%) developed stiffness requiring AAM, 9 required additional AAM procedures, 75% regained full extension and flexion >135° and 25% of AAM patients (3% of the entire cohort) did not regain full ROM.
So yes — stiffness is common. And no — not everyone fully normalizes their range. That’s the part that usually triggers concern.
The Outcome Curve Doesn’t Care
Here’s the key finding: Both groups — those who required AAM and those who did not — showed clinically relevant improvements in Kujala, KOOS and Lysholm scores at 1 and 2 years.
There were no statistically significant differences in improvement between groups.
Needing an arthroscopic manipulation did not translate into worse patient-reported outcomes at two years. Even more interesting, this challenges earlier literature suggesting that secondary surgery after trochleoplasty predicts inferior results.
What This Means in Practice
For surgeons performing trochleoplasty — already a high-level patellofemoral procedure — stiffness is part of the discussion.
The concern isn’t just lost ROM. It’s what that stiffness represents: failed rehab, arthrofibrotic biology, technical overcorrection — or ultimately, a dissatisfied patient.
This cohort suggests that, at 2 years, an episode of early stiffness requiring arthroscopically assisted manipulation does not meaningfully compromise patient-reported improvement.
That doesn’t erase the rehab burden. And 25% of AAM patients did not fully regain ROM. But it reframes stiffness as a detour — not necessarily a long-term outcome driver.
A Complication — Not a Catastrophe
Trochleoplasty remains technically demanding, and stiffness is not rare.
In this series: About 1 in 8 patients required AAM. Most regained functional ROM. And 2-year improvements matched those without stiffness.
For surgeons watching a tight trochleoplasty knee at three months, that distinction matters. Stiffness may complicate the recovery curve. It does not automatically compromise the destination.
Origin Study Title Link: Post-operative joint stiffness after Bereiter trochleoplasty does not affect 2-year improvement in patient-reported outcomes. A prospective cohort study of 374 Bereiter trochleoplasties
Authors: Christian Dippmann, Christos Soleas, Anke Simone Rechter, Volkert Siersma, Kristoffer Weisskirchner Barfod, Peter Lavard