Surgical Repair of Acute Patellar Dislocation
Abstract & Commentary
Synopsis: Excellent results are reported with surgical repair of acute patellar dislocations. Unlike previous reports, primary repair of not only the medial patellofemoral ligament, but also the origin of the vastus medialis obliquus at the adductor magnus tendon is emphasized.
Source: Ahmad CS, et al. Immediate surgical repair of the medial patellar stabilizers for acute patellar dislocation. A review of eight cases. Am J Sports Med 2000;28(6):804-810.
Traditionally, acute patellar instability has been treated with prolonged immobilization, and more recently, with "functional" rehabilitation. Unfortunately, both of these treatment options are associated with recurrent instability and patellar pain. Recent studies have proven that the medial patellofemoral ligament (MPFL) is the primary stabilizer of the patella vs. lateral displacement. Surgical repair of this ligament, which is commonly ruptured with acute lateral patellar dislocation, has been proposed but is still not popular. Ahmad and colleagues of the current paper suggest that not only should the MPFL be addressed, but the origin of the vastus medialis obliquus along the adductor magnus tendon should also be repaired.
Eight consecutive patients with first-time acute patellar dislocations were evaluated with MRI scans. All scans demonstrated tears of the MPFL at the femoral epicondyle and injury to the vastus medialis obliquus (VMO). Operative repair consisted of primary repair of the MPFL to the adductor tubercle and the VMO to its tendinous origin. Patients were evaluated at an average of three years postoperatively with a special scoring questionnaire (Kujala system) developed specifically for evaluation of patellofemoral disorders. No patients had recurrent patellar dislocation, although two had subluxations, and the average Kujala score was 91.9. The average subjective satisfaction was 96%. Ahmad et al recommend primary repair of the MPFL and VMO origin in cases of acute patellar dislocation.
Comment by Mark D. Miller, MD
Recommending surgery for acute patellar dislocation is analogous to recent reports advocating surgery for acute shoulder dislocations. It is a new idea, and it will undoubtedly be met with initial skepticism before it finds its proper place in the management of this disorder. This paper, like the ones before it, lends support to the novel concept of primary repair for acute patellar dislocation. What is perhaps more important, is that this paper also suggests that the VMO origin be evaluated and repaired with the MPFL repair.
Of course, we must all recognize that this paper reports on a small group of patients with no control group. There are limited clinical data regarding the presence of anatomic predisposing risk factors for patellar instability. VMO dysplasia is discussed but not well defined. Nevertheless, this paper does provide additional evidence that acute patellar dislocations may be best treated with primary repair. Further investigation into this exciting possibility may ultimately affect our treatment paradigm for acute patellar dislocation.
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