Short Oblique Patellar Tunnels for Patellar Fixation Do Not Increase Fracture Risk in MPFL Reconstruction: A Retrospective Cohort Study

OBJECTIVES: The current standard of care for recurrent patellar instability is reconstruction of the medial patellofemoral ligament (MPFL), the primary soft tissue constraint to lateral subluxation of the patella. Historically, transpatellar bone tunnels have been associated with increased rates of patella fracture. To avoid this dreaded outcome, many surgeons now employ suture anchors to affix the MPFL graft to the patella. This study aims to evaluate the costs and outcomes associated with short oblique patella tunnels as compared to suture anchor fixation in MPFL reconstruction. METHODS: A total of 467 knees in 419 patients undergoing MPFL reconstruction between 2011 and 2018 were included in the study. A single institution electronic medical record queried for all patients undergoing extra-articular ligament reconstruction using Current Procedural Technology codes 27422 and 27427. Chart review of operative reports was utilized to identify those who had undergone MPLF reconstruction. Patients undergoing revision MPFL reconstruction were excluded, as were patients for whom fully transpatellar bone tunnels were employed for patellar fixation. This left two groups: those for whom small, oblique tunnels (n = 277) and suture anchors (n = 190) for patellar fixation were compared. Implant pricing for the 3.2 mm drill bit, suture anchors, and allograft were obtained through publicly available databases and prior published research. RESULTS: Short oblique tunnels showed no significant increase in risk of patellar fracture compared to suture anchors for patellar fixation (P = 1.00). Use of suture anchors was associated with an increased risk of subluxation or dislocation compared to small, oblique tunnels (OR = 3.34, P = 0.021). No significant difference in the need for revision MPFL reconstruction surgery was found (OR = 1.964, P = 0.45) [Table 1]. The cost difference between allo- and autograft in ligament reconstruction has been analyzed in multiple prior studies and found to be $1100. The 3.2mm drill bit used to create the tunnels cost $84 but is reusable, while the average cost of two suture anchors was $500, leading to a material cost savings of $1600 per case in which transpatellar tunnels were used for MPFL autograft fixation when compared to a suture anchor and allograft combination. Regardless of the graft choice, material cost savings exceeds $400 per case simply by conversion to short oblique tunnels rather than suture anchors. CONCLUSION: The use of small, oblique tunnels with hamstring autograft is a safe and cost effective method for patellar fixation in MPFL reconstruction. Value in healthcare is defined as quality divided by cost. As surgeons and institutions are increasingly judged not only by the quality of the care they provide, but also in its cost, employment of this high-value technique should be considered by surgeons performing MPFL reconstruction.