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Patellofemoral pain is one of the more common complaints of young, active adolescents and adults. It can be a challenge for the orthopaedic surgeon to delineate the etiology of a patient’s anterior knee pain and an even greater challenge to successfully treat these complaints.
Arthroscopic release of the lateral retinaculum of the knee is a relatively uncommon procedure that is indicated only for patients who have patellofemoral pain, a tight lateral retinaculum, and lateral patellar tilt and who have failed conservative treatment. Experienced surgeons with specific interest in the patellofemoral joint have reported that they perform arthroscopic release of the lateral retinaculum of the knee as an isolated procedure an average of one to five times per year, accounting for approximately 2% of annual case volume.1
The differential diagnosis for anterior knee pain can include:
- Patellofemoral pain with or without excessive lateral pressure syndrome
- Patellar instability
- Lateral meniscus tear
- Patellar fracture
- Iliotibial band syndrome
- Prepatellar bursitis
- Osteochondritis dissecans of the patella or trochlea
Patellofemoral pain can be attributed to trauma, instability, overuse, or a tight lateral retinaculum causing excessive pressure between the patella and the femur. The latter scenario, coined excessive lateral pressure syndrome (ELPS),2 patellar compression syndrome,3 or patellofemoral stress syndrome,4 is the focus of this discussion. Symptoms often found ELPS include insidious onset of anterior knee pain, worse with stair climbing or prolonged sitting.
Physical exam findings and patient history play a significant role in identifying patients with ELPS who might be appropriate for the lateral retinacular release procedure. The surgeon must identify other factors associated with anterior knee pain such as core weakness, valgus alignment, ligamentous laxity, relative strength of the vastus medialis obliquus versus the vastus lateralis, and increased femoral anteversion.5 Physical exam findings consistent with ELPS include pain with patellar loading, lateral retinacular tightness, quadricep tightness and specific areas of point tenderness.
Patients with patellofemoral pain, a tight lateral retinaculum, and lateral patellar tilt should first be treated with a rehabilitation program. Symptoms will improve substantially in many patients with rigorous therapy to strengthen hip external rotators, improve proprioception, improve strength in a balanced manner, and stretch the quadriceps muscles. Taping or bracing the patella and the use of orthotic devices may also provide relief.6 Only after failure of non-operative treatment should lateral retinacular release be considered.
Radiographic examination of the knee should include anteroposterior, axial view (sunrise view in 30 to 45 degrees of knee flexion), and a 30-degree lateral view. The lateral view is particularly useful, as it demonstrates the shape of the trochlear groove, the patellar height, and the relationship of the patella to the trochlear groove.5 The fourth view is a notch view, which may demonstrate a subtle OCD lesion. The notch view can be replaced by a posteroanterior flexed 45-degree view if osteoarthritis is suspected.
The best radiographic modality to assess patellar tilt is a CT scan. On an axial cut of the knee, a line drawn parallel to the posterior femoral condyles that converges laterally with a line drawn on the lateral patellar facet indicates excessive lateral tilt of the patella and suggests an excessively tight lateral retinaculum (Figure 1). An MRI can also be useful in determining the presence or absence of ligamentous injury and can also help identify articular cartilage pathology.7
Figure 1. Using an axial CT cut of the knee, a line (A) is drawn connecting the posterior femoral condyles. A second line (B) is drawn parallel to line A, and is placed at the lateral trochlear ridge. A third line (C) is drawn along the lateral patellar facet. If lines B and C converge laterally, this is radiographic confirmation of an excessively tight lateral retinaculum.
The patient is positioned supine on the operating table, with the operative extremity positioned to allow adequate knee range of motion (Figure 2). A nonsterile tourniquet is placed around the thigh. The patient is then prepped and draped in the usual fashion used for knee arthroscopy using an extremity drape and sterile stockinette covering the foot to mid-tibia which is secured with coban wrap.
Figure 2. Patient positioning and draping on the operating table.
Standard arthroscopic portals are utilized. These include a superolateral inflow portal place lateral to the vastus lateralis obliquus and inferomedial and inferolateral portals.
First, diagnostic arthroscopy is completed using a 30-degree arthroscope placed in the inferolateral portal. The Gillquist technique is routinely used to visualize the posteromedial and posterolateral compartments. If intra-articular pathology is identified and intervention is indicated, surgical debridement/repair is performed at that time. The knee is ranged so that patellofemoral tracking can be visualized.
Upon completion of the diagnostic arthroscopy, an Esmarch bandage is tightly wrapped around the leg and the tourniquet is inflated. The arthroscope is placed in the inferomedial portal, a coagulation device (Figure 3) is placed in the inferolateral portal, and once direct visualization of the operative site is established, the start point is identified just distal to the inflow cannula. The synovium is cut first to provide more direct access to the retinaculum, and then the retinaculum is cut down to the inferolateral portal with multiple passes of the coagulation device.
Figure 3. An arthroscopic image of the coagulation device utilized in this procedure.
Note: It is very important to avoid cutting the vastus lateralis muscle or tendon. The superior lateral geniculate vessels, if cut, tend to bleed significantly. Placement of a drain is at the surgeon’s discretion and this decision is made on a case-by-case basis.
Once the procedure is complete, the knee is brought into full extension and patellar tilt is reassessed. Passive tilt of the patella should be between 30 and 45 degrees. The tourniquet is deflated, hemostatis is confirmed, portals are closed, and a sterile compression dressing with cryotherapy device are placed on the knee.
Patients undergoing patellar realignment surgery for recurrent instability may also require lateral retinacular release as a concomitant procedure. In this case, it may be done as an arthroscopic or open procedure. When an open lateral retinacular release is performed, the surgeon has the option of doing a lateral retinacular lengthening rather than a simple release. In a lateral retinacular lengthening procedure, the surgeon repairs the transected lateral retinaculum in a lengthened fashion, which prevents the potential complication of iatrogenic medial instability.8,9
Pearls and Pitfalls
- This procedure is not indicated for patellar instability alone, and it should not be performed to treat isolated patellar instability.1,5,10,11
- If the vastus lateralis obliquus muscle and tendon are cut, the patient may develop iatrogenic medial instability.
- Hemarthrosis is a complication that may be seen if appropriate hemostasis is not achieved.
- In this procedure the vessels most at risk are the superior lateral geniciulate vessels. Aggressive cauterization of these vessels if transected during the procedure, deflating the tourniquet prior to closure, and application of both a compressive dressing and cryotherapy device can all decrease the risk of hemarthrosis.12
Patients are allowed to weight-bear as tolerated immediately after surgery; however, they may use crutches for the first day or two post-operatively if desired. Follow-up about 1 week after surgery allows for appropriate post-operative assessment, wound check, and removal of sutures. Physical therapy focused on range of motion and quadriceps strengthening may also benefit some patients.
Appropriately chosen patients generally do very well after lateral retinacular release, and success rates have been quoted high as 93-100%.11,13 The arthroscopic lateral retinacular release has a success rate that is similar to that of open lateral retinacular release.13 Variation in outcome stems in part from the multiple causes of anterior knee pain and the difficulty in isolating one specific etiology. Certain factors do tend to predict poorer outcomes. In a review of the literature, women had worse outcomes than men, and women who failed to maintain quadriceps strength had an even worse outcome. Hypermobilty, presence of grade III or grade IV chondral lesions, and a Q angle greater than 20 degrees also predicted poorer outcomes. Adequate realignment of the patella, as noted on post-operative radiographic studies, as well as a positive Sage sign (when attempting to displace the patella medially, less than 25% of the width of the patella displaces medially) predict a better outcome.11
The most common complication associated with lateral retinacular release is hemarthrosis, often attributed to the superior lateral geniculate arteries. Incidence of hemarthrosis ranges between 1-42%.11,12 Other complications include medial subluxation of the patella from overaggressive release. Complex regional pain syndrome may also occur post-operatively and needs to be recognized early on.13 Other complications that have been described include arthrofibrosis, quadriceps tendon rupture, infrapatellar contracture syndrome, and thermal injury.12
- Fithian DC, Paxton EW, Post WR, et al. Lateral retinacular release: a survey of the International Patellofemoral Study Group. Arthroscopy
- Ficat P. The syndrome of lateral hyperpressure of the patella. Acta Orthop Belg 1978;44:65--76.
- Larson RL, Cabaud HE, Slocum DB, et al.The patellar compression syndrome: surgical treatment by lateral retinacular release. Clin Orthop Rel Res 1978;134:158--167.
- O’Neill DB, Micheli LJ, Warner JP. Patellofemoral stress. A prospective analysis of exercise treatment in adolescents and adults. Am J Sports Med 1992;20:151--156.
- Lattermann C, Toth J, Bach BR Jr. The role of lateral retinacular release in the treatment of patellar instability. Sports Med Arthrosc. 2007 Jun;15(2):57-60.
- Fulkerson JP. Diagnosis and treatment of patients with patellofemoral pain. Am J Sports Med. 2002 May-Jun;30(3):447-56.
- Miller, MD and Wiesel, SW Ed. (2011) Operative techniques in sports medicine surgery. Philadelphia. Lippincott, Williams and Wilkins. (Ch 51: Arthroscopic lateral release of the knee. pp 416-419)
- O'Neill DB. Open lateral retinacular lengthening compared with arthroscopic release. A prospective, randomized outcome study. J Bone Joint Surg Am. 1997 Dec;79(12):1759-69.
- Tom A, Fulkerson JP. Restoration of native medial patellofemoral ligament support after patella dislocation. Sports Med Arthrosc. 2007 Jun;15(2):68-71.
- Christoforakis J, Bull AM, Strachan RK, Shymkiw R, Senavongse W, Amis AA. Effects of lateral retinacular release on the lateral stability of the patella. Knee Surg Sports Traumatol Arthrosc. 2006 Mar;14(3):273-7. Epub 2005 Nov 26.
- Clifton R, Ng CY, Nutton RW. What is the role of lateral retinacular release? J Bone Joint Surg Br. 2010 Jan;92(1):1-6.
- Kunkle KL, Malek MM. Complications and pitfalls in lateral retinacular release. In: Malek MM, ed. Knee Surgery: Complications, Pitfalls and Salvage. New York: Springer-Verlag, 2001:161--170.
- O’Neill DB. Open lateral reinacular lengthening compared with arthroscopic release. J Bone Joint Surg Am 1997;79A:1759--1769.