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Examination under anesthesia may help surgeons decide appropriate surgery for patellar instability

According to recently published results, patients would unlikely benefit from isolated medial patellofemoral ligament reconstruction if their patella remained dislocated past 30° of flexion. However, examination under anesthesia may offer information that could help surgeons decide on the appropriate surgical approach.

Researchers retrospectively reviewed information about examination under anesthesia for 23 patients who underwent isolated medial patellofemoral ligament (MPFL) reconstruction for recurrent patella dislocation. The mean patient age was 17.4 years. The need for revision surgery due to recurrent instability was the primary outcome of the study. The median trochlea tuberosity-trochlear groove was 15 mm. The median Caton-Deschamps ratio was 1.3.

MPFL reconstruction failed in nine patients. Investigators noted the median time to failure was 10.5 months. Patients who failed MPFL reconstruction had a dislocating patella on examination under anesthesia of more than 30° of flexion.

“Radiological assessment of the knee to assess its morphology is essential for preoperative surgical planning for patients with recurrent patellar instability,” the authors wrote. “Cutoff values to determine the need for surgical procedures require a consistent method of imaging and are prone to flaws in measurement.” – by Monica Jaramillo

 

Disclosures: The researchers report no relevant financial disclosures.

 

According to recently published results, patients would unlikely benefit from isolated medial patellofemoral ligament reconstruction if their patella remained dislocated past 30° of flexion. However, examination under anesthesia may offer information that could help surgeons decide on the appropriate surgical approach.

Researchers retrospectively reviewed information about examination under anesthesia for 23 patients who underwent isolated medial patellofemoral ligament (MPFL) reconstruction for recurrent patella dislocation. The mean patient age was 17.4 years. The need for revision surgery due to recurrent instability was the primary outcome of the study. The median trochlea tuberosity-trochlear groove was 15 mm. The median Caton-Deschamps ratio was 1.3.

MPFL reconstruction failed in nine patients. Investigators noted the median time to failure was 10.5 months. Patients who failed MPFL reconstruction had a dislocating patella on examination under anesthesia of more than 30° of flexion.

“Radiological assessment of the knee to assess its morphology is essential for preoperative surgical planning for patients with recurrent patellar instability,” the authors wrote. “Cutoff values to determine the need for surgical procedures require a consistent method of imaging and are prone to flaws in measurement.” – by Monica Jaramillo

 

Disclosures: The researchers report no relevant financial disclosures.

 

    Perspective
    Matthew J. Bollier

    Matthew J. Bollier

    This paper raises several interesting questions regarding the operative treatment of patellofemoral instability. When is isolated MPFL reconstruction enough? When is bony realignment necessary? Does the EUA matter? 

    Unfortunately, I am not sure we can make any definitive conclusions from this study despite the conclusion that patients in whom the patella remains dislocated past 30° on the EUA are unlikely to benefit from isolated MPFL reconstruction. This was a retrospective case series of 23 patients by as single surgeon. There are many more factors that play a role in the pathophysiology of patellofemoral instability and surgical outcomes that weren’t accounted for in this study including hyperlaxity, activity level/type of sport, tension of MPFL graft and the location of the femoral tunnel. In addition, the definition of failure after MPFL reconstruction wasn’t clear. 

    I currently use the EUA in MPFL reconstruction cases to confirm the diagnosis of MPFL laxity/insufficiency. It could be true that patients who remain dislocated past 30° of flexion have a higher risk of failure, but this paper doesn’t provide enough evidence to make that conclusion.

     

    • Matthew J. Bollier, MD
    • Ralph and Marcia Congdon Professor in Orthopaedic Surgery
      Sports Medicine Fellowship Director, Team Physician
      University of Iowa Hospital and Clinics

    Disclosures: Bollier reports no relevant financial disclosures.

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