chapter 5: Arthroscopy of the patellofemoral joint

ARTHROSCOPIC LATERAL RELEASE

Isolated release of the lateral retinaculum was described by Merchant in 1974 (19). This was an open procedure, indicated at the time for patients with recurrent subluxation or dislocation.  The indications have changed.  Today, the primary indication for lateral release is clinical and radiographic tilt (or lateral rotation) of the patella (20), without subluxation (translation). We know now that lateral release can actually make subluxation worse! The release may be done open or arthroscopically, depending on the surgeon's preference and experience. An open lateral release has the advantage of better hemostasis, being technically easier, and affords the surgeon the ability to do a more complete release. In addition, looking at the patella under direct visualization is the most accurate way of determining the actual location and size of the lesion. It gives one the ability to stand back and look compared with an arthroscopic view that is from just millimeters away (Fig. 5.17). An arthroscopic release may give a subjectively better cosmetic result, but may lead to a higher rate of hemarthrosis, even with electrocautery.  In either case, strict hemostasis, after tourniquet and pressue release, is imperative.

The decision to do a lateral release is made preoperatively, not intraoperatively. One of the major reasons for failure of lateral release is a poor indication for the procedure. Patients with vague knee pain and no definitive diagnosis of tilt are poor candidates. Patients with moderate‑to‑severe subluxation are not optimal candidates. The purpose of the lateral release is to transect the posterolateral tethers of the patella. This will correct tilt (lateral rotation), but not subluxation (lateral tracking) (20).

Many techniques for arthroscopic lateral release have been described (1,2,5,19,21). The following technique is the author's preference. The patient is supine on the operating table, a tourniquet inflated around the proximal thigh, but is not usually inflated. The end of the table remains up, with the knee extended. A standard examination under anesthesia is performed, as well as a systematic arthroscopic inspection of the entire knee joint. A superomedial or inferomedial portal is used for visualization. The advantage of the superomedial portal is that you may look all the way down the lateral gutter from the suprapatellar pouch to the insertion of your electrocautery unit or knife inferolaterally.

A spinal needle may be placed at the most superior point of your proposed release (Fig. 5.18, A). This area is just superior and lateral to the most superolateral portion of the patella. This gives you an arthroscopic "key" for your release. You need to stay out of the vastus lateralis tendon, because cutting this may lead to quadriceps weakness and medial subluxation of the patella, a well‑described and potentially devastating complication (22). It is safer to stay more posterior proximally to stay out of the vastus lateralis. The release is started proximally and carried distally, staying a few millimeters lateral to the patella (Fig. 5.18, B). The release is carried through the synovium and lateral retinaculum only (Fig. 5.18, C). The release finishes distally at the inferolateral portal (Fig. 5.18, D). With the knee drained of fluid, one should be able to manually elevate the patella perpendicular to the trochlea. If you cannot obtain this amount of tilt, the release is inadequate and needs to be improved.

Areas frequently not released are the proximal epicondylopatellar band and the distal patellotibial band. The distal band may be reached by switching your electrocautery or knife to the superomedial portal and reaching distally while looking from below. In .some patients with tilt, the fat pad has become somewhat fibrotic and helps tether the patella distally. If you have completed your release and still are unable to elevate the lateral patella satisfactorily, this may be the problem. Releasing the fat pad is difficult arthroscopic ally. At this point, you need to extend your inferolateral portal for better visualization. The fat pad should be dissected off the patellar tendon posteriorly, and then you may cut across it from lateral to medial. Cutting across the fat pad approximately 50 to 75% of its diameter will usually free up the patella satisfactorily. This area is very vascular and will bleed when you let the tourniquet down. Hemostasis can be difficult to obtain with arthroscopic technique, and specific attention also needs to be paid to the geniculate arteries. If an adequate release cannot be obtained arthroscopically or hemostasis is difficult to obtain, convert to an open procedure for better visualization and direct palpation

When appropriate passive elevation of the lateral patella and hemostasis are obtained, the portals are closed and local anesthetic instilled. A compressive dressing is applied to aid in tamponade, and some form of cold therapy applied. The surgery is done on an outpatient basis, and the patient is discharged weightbearing as tolerated on crutches. The patient is encouraged to get motion back quickly, and no brace is used. Crutches may be discontinued when the patient is ambulating safely. Formal postoperative rehabilitation is covered elsewhere in this book. The most common reasons for failure of lateral release are poor indications, inadequate release, overzealous release (vastus lateralis), inadequate rehabilitation, and the surgeon missing concomitant pathology (mensicus tear, and so on). Most of these can be prevented with attention to detail preoperatively, intraoperatively, and postoperatively. Numerous complications from arthroscopic lateral release have been reported. These include hemarthrosis, deep vein thrombosis, infection, loss of range of motion, weakness, transection of the vastus lateralis, persistent or worse pain, reflex sympathetic dystrophy, excessive release causing medial patellar instability, and thermal injury (23). Small reported a 7% complication rate with lateral release (7).  The most common complication, hemarthrosis, is avoidable in the vast majority of patients.

Results of arthroscopic lateral release vary in the literature. Fabbriciani et al (2) reported on 50 patients who underwent arthroscopic lateral release, with a 36‑month average follow‑up. Seventy‑one percent of patients who underwent lateral release for patellar pain alone had satisfactory results. Seventy‑six percent satisfactory results were reported in patients who had the release done for complaints of instability. Incomplete release, severe articular changes, and inadequate rehabilitation were reasons the authors cited for unsatisfactory results (2). Henry et al reported 88% good results at 3‑year average follow‑up (21). Their primary indication was patellofemoral subluxation. The release was completed through the inferolateral portal under arthroscopy control with a Smillie meniscotome. These authors had a 13% complication rate (mostly hemarthrosis), and emphasized that arthroscopic lateral release is not an innocuous procedure (21). Lankenner et al reported 62% good/excellent results from arthroscopic lateral release for a diagnosis of patellofemoral stress syndrome. The release was done under arthroscopic control with a Mayo scissors. The average follow‑up was 25.6 months (24).

Much of the confusion in the literature about results of lateral release arises from the different indications and criteria of success. Whether open or arthroscopic, success of the lateral release depends more on proper patient selection than on technique.

 

        

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