Primum non nocere: MPFL reconstruction complications
This case series by Panikh and colleagues reviews the authors’ experience with complications after medial patellofemoral ligament reconstruction. I greatly appreciate their honestly and willingness to publish and emphasize complications related to this procedure. Much too often authors emphasize and readers remember only the success rates of surgical procedures.
The patient population included 179 patients with recurrent patellar instability. They determined by retrospective record review with more than 3-year follow-up that 16% of their patients developed complications including recurrent instability, stiffness, pain and patella fractures. Their medial patellofemoral ligament (MPFL) technique evolved somewhat away from more aggressive patellar tunnels (to avoid fracture), but for the sake of consistency it did not include lateral release in any patients. According to the Materials and Methods section, the preoperative evaluation included tibial tuberosity-trochlear groove (TTTG) analysis although those results were not reported. It would be interesting to know if the patients who had recurrent instability had increased TTTG measurements compared to the more successfully treated patients.
William R. Post
Analysis showed 47% of the complications were related to technical errors, a sobering fact and an important call to precision in execution of this procedure. The most common issue was the placement of the femoral tunnel. They nicely discuss current concepts regarding placement of the femoral tunnel and the need to check length tension behavior of the graft placement before accepting tunnel location intraoperatively.
They also concluded, as have other experienced patellofemoral surgeons, that intraoperative fluoroscopy is wise and appropriate to confirm proposed tunnel location as well. I would hasten to add that precise knowledge of the actual anatomical location based on surgical dissection is critical. Fluoroscopy should confirm not direct the dissection. While it is somewhat disconcerting that so many complications are related to technical error, this fact also represents the opportunity to prevent such problems by proper study and surgical precision. In fact, the learning curve for the technique and the evolving understanding for tunnel placement and length/tension relationships parallel our profession’s early experience with ACL reconstruction procedures.
How to avoid complications
Here are key points on how to avoid complications with MPFL reconstructions:
- Remember normal MPFL is tighter in extension than in flexion. If the graft tightens when the knee is flexed, stiffness, pain and patellar overload will occur and intraoperative correction is mandatory. This usually involves adjustment in femoral tunnel position. Confirm position fluoroscopically.
- Use the trochlea to reduce the patella when the graft is fixed by having the patella fully engaged in the trochlea at this point. Flexion of 30° to 45° is generally sufficient to accomplish this. Do not pull the graft tight at the time of fixation. If the other knee is asymptomatic, aim to reproduce that degree of patellar mobility. Tighter is never better in this operation.
- Avoid drilling tunnels across the patella. Alternative fixation to the patella, including suture anchor fixation, has provided equivalent biomechanical results, according to Lenschow and colleagues.
High complication rate with MPFL reconstruction are not news. Shah and colleagues published a meta-analysis in 2012 of 25 articles and found 26% complications. The complications described in both articles can be more disabling than the primary problem being treated (the recurrent dislocation). Many patients who have experienced more than one patellar dislocation are very functional and may not need surgery, thus avoiding such complications. Only when patients are significantly limited in their activities of daily living or more aggressive activities should major surgery such as MPFL reconstruction be considered. We, as a profession, need to be extremely careful recommending this procedure to patients who must be clearly apprised of the relatively high rate of complications and secondary procedures.
Lenschow S. Arthroscopy. 2013;doi:10.1016/j.arthro.2012.12.004.
Parikh SN. Am J Sports Med. 2013;doi:10.1177/0363546513482085.
Shah JN. Am J Sports Med. 2012;doi:10.1177/0363546512442330.