Arthroscopic patella realignment: Don’t forget minimally invasive stabilization
There has been great emphasis recently on invasive methods of medial patellofemoral ligament reconstruction for patella instability. Although these techniques can be effective and appropriate for severe cases of instability caused by medial patellofemoral ligament insufficiency, it is important to keep perspective on the appropriate indications for these techniques.
Medial patellofemoral ligament (MPFL) reconstruction with a graft is indicated when the native MPFL is incompetent, and the remaining native tissue is inadequate to be repaired or reefed primarily. However, in many cases of mild or moderate instability, a simple reefing of the MPFL is a highly successful procedure, whether done arthroscopically or by mini-open techniques, and is a much less invasive procedure.
Numerous studies have been published documenting the effectiveness of arthroscopic realignment for patella instability, with success rates of more than 90% and no or minimal complications. Although effective, MPFL reconstruction is an open invasive procedure fraught with potential complications including patella fracture, over-tightening, and non-isometric placement of the graft resulting in pain stiffness and medial tracking.
Principles of arthroscopic realignment
Anatomic studies and clinical experience have shown that the MPFL heals in an elongated fashion following subluxation or dislocation. Reefing of this lax MPFL is possible in a procedure similar to capsulorrhaphy of the shoulder for laxity of the glenohumeral ligaments. In an acute setting following a patella dislocation, direct open repair to the femoral attachment site may be necessary in addition to the reefing. However, we typically recommend initial rehab for at least 6 weeks to allow the MPFL to heal and then proceed with arthroscopic reefing.
Patients who are candidates for isolated arthroscopic reefing are patients with subluxation, or dislocators with mild to moderate instability, and who have an MPFL with good integrity. In our practice, patients who require MPFL reconstruction with a graft typically have failed a previous reefing procedure or have a severe J sign with 3-4 quadrant translation easily demonstrated on physical exam. For patients with patella instability associated with severe trochlea dysplasia or tibial tubercle malalignment, we would recommend a formal MPFL reconstruction with a graft (possibly in conjunction with a tubercle osteotomy). These patients require an extra strong MPFL in order to overcome the underlying dysplasia.
MPFL reconstruction has a place as a treatment option for patella instability, but is not the only option. It is important to remember that less invasive options that reef or repair the native MPFL also can be highly effective with fewer complications.
For patients with only mild or moderate instability, forgo the graft.