1.Clin Orthop Relat Res. 2003 Sep;(414):157-61.

Archibeck MJ, Camarata D, Trauger J, Allman J, White Jr RE.

New Mexico Center for Joint Replacement Surgery, Albuquerque, USA. archibeckmj@ortholink.net

The rule of no thumb test was compared with the towel clip test in determining the need for lateral retinacular release in 200 consecutive primary total knee replacements. The towel clip test was positive in 13 knees (6.5%) and the rule of no thumb test was positive in 78 knees (39%). Using a positive towel clip test as the indication for lateral retinacular release, there was no radiographic evidence of patellar tilt, subluxation, or dislocation in any knee at 6 months postoperatively. Therefore, the rule of no thumb test falsely predicted the need for lateral release in 65 knees (32.5%). The authors advocate the towel clip test to determine the need for lateral retinacular release.

2.

Douglas W. Jackson, MD: What are the current indications for isolated lateral retinacular release?

Andrew J. Cosgarea, MD: The primary indication for isolated retinacular release is a symptomatic tight lateral retinaculum in someone who has failed to improve with nonoperative measures.

Patients usually present with anterior knee pain that is exacerbated by activities like stair climbing and prolonged sitting. When you examine these patients, they have decreased lateral patellar elevation during patellar tilt testing. With a normal knee you should be able to elevate the lateral edge of the patella to be parallel with the ground, whereas in these patients the tight lateral retinaculum will prevent this. While these patients have pain with patella loading, the apprehension sign is usually negative. In most cases, the patella is not unstable; in fact, it will usually have decreased lateral translation during patellar glide testing. X-rays are usually normal, or may show lateral traction spurs. CT scan axial images will show lateral tilt (see image), but the diagnosis can usually be made on a clinical basis. In patients who experience patellar instability episodes and also have a tight retinaculum, lateral release may be used in combination with a realignment procedure.

Jackson: It has been my assumption that there is a significant variation in how often this procedure is performed. I have heard of surgeons who do more than 20 a year. Do we have any information on how often it is done by experienced surgeons? How often do you see patients for whom you feel it is indicated as an isolated procedure?

Cosgarea: Most experienced surgeons agree that isolated retinacular release should be performed relatively infrequently. The best information we have in the literature comes from a study by Fithian and colleagues who surveyed the members of the International Patellofemoral Study Group, a group of surgeons who devote a large part of their practice to treating patellofemoral pathology.

Results of the survey showed that isolated release was estimated to account for only one to five cases, or about 2% of cases performed annually by these surgeons. The authors also reported a strong consensus among the group that lateral release requires objective clinical indications and specific preoperative informed consent.

Fewer than 20% felt that instability was an indication for release, and there was a strong consensus that hypermobility was a contraindication.In my practice I may perform one or two isolated releases per year, and most of my patellar stabilizations are done without concomitant lateral retinacular release.

Jackson: What are some key technical surgical considerations when performing this procedure?

Cosgarea: Both open and arthroscopic techniques can be successfully used to perform lateral retinacular releases. The open technique gives the surgeon the option of repairing the cut retinaculum in a lengthened state. Arthroscopic release has an obvious cosmetic advantage.

In both cases the surgeon must be careful not to be overly aggressive with the release, which could lead to iatrogenic medial instability. Generally the release should not extend into the vastus lateralis fibers, as this can predispose to extensor mechanism weakness or rupture. Electrocautery is important as hemarthrosis is a well-known and potentially serious postoperative complication.

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