• MPFL reconstruction is not recommended for the management of patellofemoral pain; therefore, patients with anterior knee pain and no objective lateral patellar instability are not candidates for this procedure.

• Preexisting osteoarthritis is a relative contraindication to MPFL reconstruction.

• Although a trial of conservative treatment is a common approach for treating first-time dislocations, in light of the increased risk of recurrent instability after initial dislocation, the utility of MPFL reconstruction in this setting is currently evolving.

• Plain radiographs, including lateral, Merchant, and standard weight-bearing anteroposterior (AP) views, are used to evaluate limb alignment, trochlear dysplasia, and patella alta (Figs. 53-1 and 53-2).

• Various measures for diagnosing patella alta have been described in the literature¹:

• An Insall-Salvati ratio (patellar tendon length/patellar length) >1.2 is indicative of patella alta.

• The Blackburne-Peel ratio is calculated from a lateral radiograph taken with the knee in 30 degrees of flexion. A horizontal line is drawn at the level of the tibial plateau. Perpendicular to this horizontal line, the distance between the inferior aspect of the patellar articular surface and the horizontal line is measured (B). A second measurement is made along the length of the patellar articular surface (A). B/A represents a measure of patellar height, with a ratio of 0.8 being normal and a ratio >1.0 being indicative of patella alta.

• A Caton-Deschamps ratio (distance between lower pole of patella and upper limit of tibia/length of patellar articular surface) >1.3 is indicative of patella alta.

• If patella alta is present, concomitant or staged tibial tubercle osteotomy and distalization should be considered.

• Magnetic resonance imaging (MRI) is useful in determining the location and extent of soft tissue injury.

• Computed tomography (CT) scan can be used to further evaluate osteochondral injuries.

• CT or MRI axial imaging should be used to assess the tibial tuberosity-trochlear groove (TT-TG) distance and tibial tuberosity-posterior cruciate ligament (TT-PCL) distance.

• Concomitant or staged medialization of the tibial tubercle may be indicated in patients with TT-TG offsets of 20 mm or greater.²

• In addition, a TT-PCL distance >24 mm may be pathologic.³

• Examination under anesthesia should be routinely performed to assess patellar mobility and laxity of the surrounding retinacular structures.

• Patellar mobility should be assessed with the knee at both 0 and 30 degrees of flexion.

• Displacement of the patella of more than 10 mm laterally from the centered position and the presence of either a soft end point or no end point with the knee extended is confirmatory.

• If excessive lateral retinacular tightness is noted, concomitant arthroscopic or open lateral retinacular release should be considered.

• Good to excellent short-term and midterm outcomes have been reported regardless of graft type.

• The general consensus is that graft selection should be individualized based on patient characteristics and both patient and surgeon preferences.

• A recent meta-analysis of 31 studies (total of 1065 MPFL reconstructions) noted the following⁴:

• Autograft MPFL reconstructions were associated with greater improvements in Kujala scores when compared to allograft reconstructions; however, the rates of recurrent instability and revisions did not differ significantly between the groups.

• Double-limbed anatomical reconstructions were associated with better Kujala scores and a lower failure rate than single-limbed isometric reconstructions.

• Drill set, guide pins, and reamers

• Ablation device for lateral release

• Instruments for graft harvesting/preparation and graft sizers

• Anchors/screws for graft docking in the patella

• Adjustable loop cortical button (ToggleLoc, Zimmer Biomet; Warsaw, IN)

• Standard arthroscopy tower and instruments

• C-arm fluoroscopy unit

• The patient is positioned supine on a standard operating room table.

• A sterile bump can be placed under the knee to maintain 30 degrees of knee flexion and to assist in obtaining a lateral fluoroscopy view.

• While currently there is no consensus regarding the optimal knee flexion angle during graft fixation, the 30- to 60-degree range is most frequently recommended.⁵