PROMs and Patellar Tracking After Isolated MPFL Reconstruction.

Patellar dislocations cause pain and functional decline in adolescents, which can be restored by a MPFL reconstruction. Yet, many reconstruction methods are being used clinically as consensus on the ideal MPFL reconstruction method is lacking. We propose a soft-tissue loop reconstruction method which potentially decreases the risk for of iatrogenic fracture of the patella and prevents femoral tunnel malposition.

Rationale: A patellar dislocation is one of the most common acute knee disorders in children and adolescents, causing pain and functional decline. In order to restore healthy kinematics and relieve pain, patients can receive a MPFL reconstruction. Still, there is no consensus on the ideal MPFL reconstruction method and many different variations exist. For a reliable comparison, each MPFL reconstruction method should be evaluated clinically. Within the Radboudumc, a soft-tissue loop method is used for MPFL reconstruction. The method has not yet been evaluated clinically, and the difference in patella tracking is largely unknown.

Objective: Evaluate pre- and postoperative reported outcomes in patients receiving an isolated soft-tissue loop MPFL reconstruction for the treatment of patellar instability. Additionally, it is aimed to investigate the difference in patella tracking before and 12 months after surgery measured with 4D CT imaging.

Study design: Prospective single centre observational study

Study population: 15 patients with recurrent patellofemoral instability who have received an isolated soft-tissue loop MPFL reconstruction within the Radboudumc.

Main study parameters/endpoints: the main study parameter is the pre- and postoperative difference in patient reported outcome measures (PROMs). The secondary aim is to assess changes in patellar tracking (measured before and 12 months after surgery).

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Patients will undergo a 4D CT scan of their knees after their surgery.

Whenever possible, the CT scans will be planned during a the regular 12 month check-up appointment day so patients do not have to come to the Radboudumc for the CT scan on itself. The preoperative 4D CT scan and PROMS that will be used in this study are part of standard care. CT scans exposes patients to radiation. For this study the level of radiation is estimated as an negligible risk. No additional risks are associated with this study. Potential burdens for patients are predominantly time and additional radiation exposure. No direct personal health benefit is expected. However, the knowledge generated with this study is expected to benefit future patients who need to undergo a MPFL reconstruction.

Eligibility Criteria:
Inclusion Criteria:

* Age of 16 years and older.
* Recurrent patellofemoral instability, for which:

  1. the patient will receive a primary isolated MPFL reconstruction, or
  2. the patient has received a primary isolated MPFL reconstruction \<12 months ago, on the condition that the patient has completed his/her questionnaires and received a usable preoperative 4D CT scan .
* Informed consent of the patient.

Exclusion Criteria:

* Patients below an age of 16 years.
* Patients that are pregnant.
* BMI \> 35
* Patients that are unable to actively flex and extend their knee.