Results of arthroscopic medial retinacular release for treatment of medial subluxation of the patella

BACKGROUND: Medial subluxation of the patella is a rare, disabling condition that has iatrogenic and traumatic causation. To date, only open reconstructions have been reported for operative treatment of this condition, but these procedures have a high rate of complications, revisions, and subsequent surgery. This is the first study to present the results of arthroscopic medial retinacular release for treatment of this problem. HYPOTHESIS: Arthroscopic release will alleviate painful medial patellar subluxation. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Nine knees (7 patients) with painful, recurrent medial subluxation of the patella that occurred spontaneously (2 knees) or after a lateral release (5 knees) or an injury (2 knees) were treated with an arthroscopic medial retinacular release. The retinaculum was released 2 cm medial to the superior pole of the patella down to the anteromedial portal. At a mean follow-up of 2.7 years (range, 1-8 years), all knees were evaluated, and the results were graded according to the Merchant and Mercer rating scale. RESULTS: The mean age of the patients was 25 years (range, 15-38 years), and the mean duration of the subluxations before surgery was 28 months (range, 6-48 months). In all 7 patients (9 knees), the medial release relieved their medial subluxation and knee pain, and there were 6 excellent and 3 good results. There were no complications or further realignment surgery needed after this procedure. CONCLUSION: An arthroscopic medial retinacular release will successfully treat painful medial subluxation of the patella.     

Effect of a patellar realignment brace on patellofemoral relationships: Evaluation with kinematic MR imaging

The effect of a newly developed patellar realignment brace was evaluated in 21 patellofemoral joints (19 patients) with patellar subluxation (13 joints with lateral subluxation and eight with medial subluxation) by using active-movement, loaded kinematic magnetic resonance (MR) imaging. Sixteen patellofemoral joints (76%) demonstrated a qualitative correction of or improvement in patellar subluxation (ie, centralization of the patella or a decrease in the displacement of the patella) after application of the brace. Four of the five “failures” occurred in patellofemoral joints that had patella alta and/or dysplastic bone anatomy. These results indicate that the patellar realignment brace was able to counteract patellar subluxation in the majority of patellofemoral joints studied, as shown by active-movement, loaded kinematic MR imaging. This brace appears to be useful for conservative treatment of patients with patellofemoral joint pain secondary to patellar malalignment and maltracking.     

Patellar tracking abnormalities: clinical experience with kinematic MR imaging in 130 patients

A kinematic magnetic resonance (MR) imaging technique for assessment of malalignment of the patella, involving the acquisition of multiple sequential axial images of the patellofemoral joint during the early increments of passive knee flexion, was used to evaluate 130 patients (235 symptomatic patellofemoral joints) showing clinical evidence of having patellar tracking abnormalities. Twenty-three of the patellofemoral joints had undergone previous surgical procedures for patellar realignment. In addition, 14 (28 patellofemoral joints) asymptomatic control subjects were studied. Normal patellar tracking was observed in all of the asymptomatic subjects and in 43 (17%) of the 260 patellofemoral joints in the patient population, 18 (7%) of which were symptomatic. Sixty-nine (26%) of the patellofemoral joints had lateral subluxation of the patella, 106 (41%) had medial subluxation of the patella, 21 (8%) had excessive lateral pressure syndrome, 19 (7%) had lateral-to-medial subluxation of the patella, and two (1%) had dislocation of the patella. Of the 235 patellofemoral joints with suspected abnormalities, 217 (93%) had patellar malalignment. Of the 23 patellofemoral joints that had undergone prior surgery, 20 (87%) had abnormal patellar tracking. Thirteen of 14 (93%) patellofemoral joints that had undergone a prior arthroscopic lateral retinacular release had a medially displaced patella.     

Axial and lateral radiographs in evaluating patellofemoral malalignment.

This is a prospective study of 431 patients (862 knees) with patellofemoral pain, patellar dislocation, or other abnormalities of the knee joint. There were 217 asymptomatic knees with no contralateral problems for comparison. All patients had a history and physical and radiographic examination of both knees. The radiographs included standard anteroposterior views, axial views at 30 degrees of knee flexion, and standing lateral views at 0 degree and 30 degrees of flexion. The presence of patellar tilt or subluxation was noted on the axial view. The lateral view of the patella, with precise overlap of the posterior femoral condyles, allowed determination of relationships between the patella's medial edge, median ridge, and lateral edge to assess patellar tilt. Sixty-two percent of patients with patellar dislocations demonstrated subluxation on the axial view, while 98% demonstrated an abnormal lateral view. Eighteen percent of the control knees revealed evidence of subluxation on the axial view while 35% demonstrated subluxation on the extended lateral view. The axial view demonstrated 62% sensitivity for dislocation, while the lateral view taken in full extension demonstrated 98% sensitivity. The specificity for previous dislocation was 82% for the axial view and 93% for the lateral flexed view. Given the high sensitivity of the lateral view for detecting prior patellar dislocation, a normal result on this view can virtually eliminate the question of previous dislocation. Also, with the high specificity of the axial view and lateral view with knee flexion, the two views combined can confirm a clinical impression of patellofemoral malalignment.     

Diagnosis and surgical correction of medial patellar subluxation

This article reviews the clinical entity of medial patellar subluxation, including relevant anatomic andbiomechanical factors. Most cases of medial patellar subluxation occur as a late complication of lateral retinacular release. Symptoms include pain, disability, crepitus, and intermittent swelling. Clinical signs include subluxation of the patella with manual medial glide, an observable defect in the vastus lateralis tendon, and positive apprehension with medial patellar glide. The application of various imaging methods is also presented. Finally, the authors review several surgical procedures for correction of medial patellar subluxation.     

Medial dislocation of the patella

Medial dislocation of the patella is a previously unreported entity. This disorder can be disabling to the patient and may require a hospital visit for reduction. Three cases are presented in this article in which computed tomography demonstrated the dislocation. All three patients had undergone a lateral retinacular release to the involved knee for treatment of chronic knee pain or recurrent lateral patellar subluxation.     

MPFL reconstruction for recurrent patella dislocation: a new surgical technique and review of the literature

Recurrent dislocation, subluxation and functional instability due to patellofemoral pain might be present in 30 % to 60 % of patients managed non-operatively for posttraumatic patella instability. Disruption of the capsule, medial patella retinaculum and/or vastus medialis obliquus have been associated with recurrent patella instability but recently the medial patellofemoral ligament (MPFL) has been recognised as the most important ligamentous stabiliser preventing lateral dislocation of the patella. Many nonanatomical surgical techniques for the treatment of recurrent patellar dislocation have been described in the literature. These procedures alter the pre-morbid patella mechanics by several principles, including the release of tight lateral ligaments, tensioning of loose medial structures and distal realignment of the extensor mechanism or a combination of these. Very few address the principle site of pathology in patella dislocation, i.e., the torn MPFL. The outcomes are inconsistent and many studies have reported recurrent dislocations and patellofemoral pain and arthritis in up to 40 %. We describe a simple technique of MPFL reconstruction using a single hamstring tendon graft which is passed through the medial intermuscular septum at the adductor's magnus insertion and is fixed to the superomedial pole of the patella. A comprehensive review of the existing techniques of MPFL reconstruction using semitendinosus tendon autografts is also provided.     

Reducing the lateral force acting on the patella does not consistently decrease patellofemoral pressures

BACKGROUND: Extensor mechanism procedures that decrease the lateral component of the patellar tendon or quadriceps force acting on the patella do not consistently reduce pain. HYPOTHESIS: Patellofemoral treatments do not consistently decrease patellofemoral pressures because of variations in the moments acting on the patella. STUDY DESIGN: Computer simulation study. METHODS: Computational models of 4 knees were constructed to characterize the patellofemoral pressure distribution during simulated squatting from 40 degrees to 90 degrees. The knees were given an initial Q angle of 25 degrees. Patellofemoral treatments were simulated by increasing the percentage of the quadriceps force applied by the vastus medialis by 50% and by medializing the tibial tuberosity to decrease the Q angle to 15 degrees. RESULTS: Decreasing the Q angle caused a larger decrease in the lateral component of the force applied by the quadriceps and patellar tendon than did increasing the force applied by the vastus medialis and, therefore, was more effective at decreasing patellofemoral pressures and the force needed to resist lateral subluxation. Both treatments also decreased the moments acting to rotate the distal patella laterally and tilt the patella laterally during flexion. Variations in these moments increased patellofemoral pressures for some knees. CONCLUSIONS: Treatments that reduce patellofemoral subluxation can have an unexpected influence on patellofemoral pressures because of the moments acting on the patella. CLINICAL RELEVANCE: Extensor mechanism procedures that restore patellofemoral stability may not provide pain relief.     

Arthroscopic suture anchor repair for lateral patellar instability

Several all-arthroscopic techniques have been described to address patellar instability. Most arthroscopic procedures focus on soft tissue plication or “tightening” of the medial retinacular structures to correct lateral patellar instability. We found these techniques to be ineffective when the medial stabilizers were avulsed from the patella. As a result, we have developed an arthroscopic technique to repair medial patellofemoral ligament avulsions to the patella using suture anchors.     

Effect of bracing on patellar kinematics in patients with patellofemoral joint pain

PURPOSE: Bracing is commonly used to correct patellar malalignment syndromes. However, there are little objective data documenting the effect of such supports on patellofemoral joint relationships. The purpose of this study was to assess the effectiveness of an elastic patellofemoral sleeve brace in altering patellar tracking in subjects with patellofemoral pain. METHODS: Ten female subjects (12 patellofemoral joints) between the ages of 17 and 46 participated in this study. All subjects had a diagnosis of patellofemoral pain and demonstrated lateral patellar tracking based on magnetic resonance imaging (MRI) assessment. Each subject underwent kinematic MRI of the patellofemoral joint through a range of 45 to 0 degrees of knee flexion against a resistance of 15% body weight. Imaging was performed with and without a patellofemoral joint brace (Bauerfeind Genutrain P3 brace, Atlanta, GA). Measurement of medial/lateral patellar displacement, medial/lateral patellar tilt, and the depth of the trochlear groove (sulcus angle) were obtained with midpatellar image sections at 45, 36, 27, 18, 9 and 0 degrees of knee flexion. RESULTS: No statistically significant differences in medial/lateral patellar displacement or tilt were found between braced and unbraced trials across all knee flexion angles (P < 0.05). A small but statistically significant increase in sulcus angle was found across all knee flexion angles with the braced trials (P > 0.05). CONCLUSIONS: These results do not support the hypothesis that the brace used in this study corrects patellar tracking patterns in subjects with patellofemoral pain. However, the increased sulcus angle indicates a change in patella position within the trochlea. It is possible that the clinical improvements seen with bracing may be the result of subtle differences in joint mechanics and not gross changes in alignment.     

Lateral retinacular release in patellofemoral subluxation. Indications, results, and comparison to open patellofemoral reconstruction

A consecutive series of patients who have undergone arthroscopy and lateral retinacular release for patellofemoral subluxation was evaluated so that the results could be compared to an earlier series of open patellofemoral reconstructions. Of 96 patients, 4 had bilateral releases; therefore, 100 knees were evaluated. The average age was 28 years. Specific symptoms and signs were reviewed. All patients were initially treated conservatively with specific exercises. Failure of the exercise program to improve symptoms significantly, the patient's inability to perform normal daily activities, or expected associated pathology were indications for surgery. The surgical technique consisted of arthroscopy with treatment of associated pathology and lateral retinacular release using the Smillie meniscotome through the inferior lateral portal. The patella could be tilted approximately 90 degrees medially when the release was accomplished. Pain, function, and patellar instability were evaluated preoperatively and postoperatively by signs of tenderness on the retinaculum or bone, patellar mobility, effusion, muscle atrophy, and tone. Range of motion was also evaluated. Average followup was 36 months. When evaluated subjectively by the patients, pain improved from a mean preoperative grade of 3.4 to 1.7 postoperatively, function improved from 3.4 to 1.7, and instability from 3.4 to 1.6. Objective evaluation found that tenderness on the patella improved from a mean preoperative grade of 3.3 to 1.7 postoperatively. Tenderness on the retinaculum improved from 3.2 to 1.7. Patellar mobility improved from 3.3 to 1.7. Effusion dropped from 3.2 preoperatively to 1.5 postoperatively; quadriceps atrophy from a mean preoperative grade of 3.2 to 1.5, and quadriceps tone from 3.2 to 1.6.(ABSTRACT TRUNCATED AT 250 WORDS)     

Time dependent changes in patellar tracking with medial parapatellar and midvastus approaches

The aim of this study was to compare the alteration of patellar tracking by time, which was performed through two different approaches: midvastus and medial parapatellar. Twenty-one patients undergoing simultaneous bilateral primary total knee replacements were randomized prospectively to perform the surgery via a medial parapatellar approach on one knee and midvastus approach on the other knee. All of the patellae were resurfaced. Preoperative, early and late postoperative (mean 22 month) skyline views of the patellae were taken. We found that preoperative 2.24° lateral tilt of patella had not changed by time at the midvastus side (2.95° and 2.57°). Moreover, preoperative 0.48% lateral subluxation of the patella for midvastus approach had not changed (1.48% and 1.67%). Although 2.19° patellar lateral tilt had not significantly changed at the early postoperative period, which was performed via medial parapatellar approach, there had been a significant increase to 5.38° by time (P=0.037) compared to the preoperative radiographs. Additionally, the preoperative lateral subluxation of the patella (0.57%) at the medial parapatellar side had increased to 5.43% at the early (P=0.009) and 5.62% at the late (P=0.012) postoperative measurements. Midvastus approach is superior to medial parapatellar approach concerning the late patellar tracking.     

Medial patellofemoral ligament reconstruction using a hamstring graft

Recurrent lateral dislocation of the patella has been historically treated with a combination of multiple techniquesincluding lateral release, proximal realignment, medial reefing, and distal realignment. Poor-quality medial retinacular tissues and nonanatomic surgical attempts to restrain the patella may contribute to notable problems with redislocation and anterior knee pain. Recent biomechanical studies have identified the functional importance of the medial patellofemoral ligament as the primary restraint to lateral translation of the patella. A technique of reconstruction of this ligament with a single semitendinosis autograft, which provides a sturdy check-rein to lateral translation, is described. The authors' current indications for this procedure are (1) the recurrent lateral patellar dislocations in a patient with poor-quality medial soft tissues and no definable MPFL, and (2) the failure of previous proximal or proximal and distal realignment procedures with continued medial functional deficiency.     

Arthroscopic extraarticular reconstruction of the medial patellofemoral ligament with gracilis tendon autograft - surgical technique

The standard approach to reconstruct the medial patellofemoral ligament (MPFL) is by mini-open incision at its patellar insertion and femoral origin. At the medial patella rim, the MPFL insertion may be visualized in most cases by dissection during surgery. On the femur, it is more difficult to localize the MPFL remnants by a mini-open incision due to soft tissue covering the anatomical origin. Therefore, the femoral MPFL origin is usually identified by intraoperative lateral fluoroscopy. However, the insertion and origin of the MPFL at the patella and femur might be directly visualized using an arthroscopic extraarticular approach from the knee joint through a window of the synovial layer. This is especially helpful on the femoral side but also at the patella to find the individual anatomical MPFL footprints. Arthroscopic extraarticular reconstruction may then be performed using one additional medial mid-parapatellar portal. The major advantages of this technique are an individualized anatomical procedure, which is minimal invasive and cosmetically appealing. The aim of this study was to describe the arthroscopic extraarticular approach to the MPFL insertion at the patella and origin at the femur through synovial windows and to explain the procedure of arthroscopic MPFL reconstruction with a gracilis tendon autograft. Level of evidence Expert opinion, surgical technique, Level V.     

Current concepts of lateral patella dislocation

Surgical treatment of patellar dislocations, acute and chronic, has evolved significantly over the past decade with the advance of biomechanical knowledge of patellofemoral restraints and injury patterns identified by physical examination and improved imaging techniques. There continues to be no consensus on treatment parameters. Despite the presence of predisposing factors, such as dysplasia or generalized hyperlaxity, medial retinacular injury associated with primary (first-time) patellar dislocations represents a ligament injury, which may result in residual laxity of the injured structure. This residual laxity is defined objectively by an increase in passive lateral excursion of the patella. Repair or reconstructive procedures to restore this medial constraint is considered paramount in any procedure to stabilize the patella against subsequent dislocations. How best to accomplish this continues to be a matter of debate. The establishment of a medial check-rein by either repairing or reconstructing the MPFL is the procedure of choice for stabilizing a kneecap after first-time dislocation, largely because the literature to date does not provide clear guidelines about when more extensive surgery is indicated. Whether or not all first-time dislocators have improved outcome after surgical repair remains speculative, however. Improved outcome would involve both the elimination of recurrent instability episodes and continued satisfactory function of this patella in activities-of-daily-living and sporting activities. These outcomes have not been studied critically in operative versus nonoperative treatment of first-time patellar dislocation. For the first-time dislocator, most investigators would agree that an arthroscopy should be performed if intra-articular chondral damage is suspected. Nonoperative management of first-time patellar dislocations continues to be the preferred practice pattern in the United States. If surgical management is elected, because of individual characteristics of the injury pattern or the patient's lifestyle, it is important to inspect the MPFL along its length and repair any or all ligamentous disruptions. If the ligament is avulsed from the medial epicondyle, reattachment to bone is necessary to restore passive restraint to lateral patella motion. MRI may be useful in order to identify the location and degree of medial soft tissue injury preoperatively. The establishment of a medial check-rein by either repairing or reconstructing the MPFL is a necessary component of all surgical procedures performed to correct objective lateral instability of the patella. The addition of a LRR should be additive to this procedure only when it facilitates other procedures to recenter the patella or when objective lateral tilt by physical examination measurements is present. A practical approach to surgery after patellar dislocation is the minimal amount of surgery necessary to re-establish objective constraints of the patella. Correcting dysplastic factors, in particular tibial tubercle transfers and trochleoplasties, are best reserved if more minimal surgery has failed. This failure is defined as continued functional instability of the kneecap.     

Arthroscopic surgery and the lateral release for patellofemoral disorders

A 30° arthroscope, when placed from a portal 4 cm proximal to and in line with the medial edge of the patella,approaches the trochlea at a 30° angle, providing a straight-on view of the patellofemoral joint without distortion. By routinely placing the arthroscope through this portal, patellar tracking can be evaluated and patellar malalignment documented and corrected under direct vision. When a lateral release is performed, the scope is in the proximal superomedial portal and the electrosurgical unit is through the anterolateral portal without the tourniquet being inflated. If subluxation remains after lateral release is performed, the degree of medial imbrication to be done is judged arthroscopically to prevent undercorrecting or over-correcting the patellar realignment. When oblique anteromedialization osteotomy of the tibial tubercle is done, the arthroscopic view assists in determining the degree of medialization of the tubercle to be performed. The maximum medialization is believed to be one half the width of the tubercle and fixed with AO small fragment cancellous compression screws. A lateral release is always performed with this procedure and, if it fails to provide patellar realignment, medial imbrication is added. Postoperative positioning in flexion assists the recovery.     

Arthroscopic mediopatellar plicaectomy and lateral retinacular release in mechanical patellofemoral disorders

Arthroscopy was performed on 168 knees of 164 patients with anterior knee pain by a single arthroscopic surgeon between April 1993 and March 2000, with a mean follow-up of29 months. There were 168 mediopatellar plicae, 16 infrapatellar plicae, 8 suprapatellar plicae, and 30 lateral plicae, and all plicae were excised. Lateral retinacular release was performed in 74 patients with patellar lateral compression syndrome, patellar lateralization, and patellar lateral subluxation through anterolateral portal without using a third portal with the help of a hook knife. Débridement and drilling were performed in type 3 and 4 chondropathies (Outerbridge classification), and cartilage débridement was performed in type 2 chondropathies. We examined the effect on morbidity and prognosis of the arthroscopic lateral retinacular release through the standard anterolateral portal; the results of condylar chondropathies and débridement and drilling applied to the chondropathies were also evaluated. Mediopatellar plica was seen to play a mechanical role in the development of medial femoral chondropathy, which confirms that excision of plica is a prophylactic procedure. A further successful method is lateral retinacular release applied through the standard anterolateral portal with conventional methods without using a third portal at the cases with patellar lateral compression syndrome, patellar lateralization, and patellar lateral subluxation. Classical débridement and drilling methods are cheap and easy for the treatment of chondropathy. We consider these methods still to be useful methods of treatment.     

Medial retinacular flap advancement and arthroscopic lateral release for symptomatic chronic patellar lateral subluxation with tilting

Purpose

The purpose of this study was to investigate outcomes of surgical treatment in patients with symptomatic chronic patellar lateral subluxation with tilting.

Methods

Thirty-two patients (38 knees) underwent arthroscopic lateral release and mini-open advancement of medial retinacular flap for the treatment of symptomatic chronic patellar lateral subluxation with tilting with a mean follow-up of 52.0 ± 11.4 months. The mean age at surgery was 24.7 ± 8.8 years, and the duration of symptoms was 4.8 ± 4.1 years. The patellofemoral function of the knee was evaluated before surgery and at the clinical follow-up using the Kujala functional score.

Results

Thirty-six knees (95 %) showed excellent or good results after surgery. Two knees with grade IV chondromalacia of the patella had fair results with persistent apprehension signs and persistent pain. The Kujala patellofemoral functional scores improved by an average of 20.9 points from a mean value of 71.8 ± 12.1 preoperatively to 92.7 ± 10.7 postoperatively (P < 0.01). Radiographically, there were significant improvements in congruence angle from 23.4° ± 7.9° preoperatively to ?7.2° ± 6.4° postoperatively (P < 0.01) and in the lateral patellofemoral angle from ?8.6° ± 6.8° preoperatively to 6.3° ± 4.2° postoperatively (P < 0.01).

Conclusions

Medial retinacular flap advancement and arthroscopic lateral release offer a promising treatment for symptomatic chronic patellar lateral subluxation and tilt without frank traumatic episode.

Level of evidence

Retrospective study, Level IV.     

Acute patellar dislocation. What to do?

Acute patellar dislocation is a common knee injury that occurs most often in adolescents, frequently associated with sporting and physical activities. Patellar re-dislocation after the first episode appears to depend primarily on the medial patellofemoral ligament injury which represents the primary ligamentous restraint, providing about 50–60 % of the restraining force against lateral patellar displacement. Clinically, up to 94–100 % of patients suffer from medial patellofemoral ligament rupture after first-time patellar dislocation. Controversy regarding how patients with first patellar dislocation should be managed still exists. Though most authors have reported good results with the conservative treatment after a first-time dislocation, several circumstances may warrant surgical intervention. A surgical approach would be necessary in the presence of severe cartilage damage or a relevant disruption of the medial stabilizers with subluxation of the patella. In these cases, the repair/reconstruction of medial stabilizers should follow the treatment of the chondral injury. Medial patellofemoral ligament reconstruction may be a more reliable method of stabilizing the patella than its repair, which has limitations related to the medial patellofemoral ligament injury location. Nowadays, there is no evidence available where osseous abnormalities should be addressed in addition to restoring the medial patellofemoral ligament.     

Lateral release of the patella: indications and contraindications

Charts were reviewed on patients at the Salt Lake Knee and Sports Medicine Clinic who had had a lateral release of the patella. Patients were divided into two groups. Group I contained patients who were entirely satisfied with the procedure, and Group II included patients who were complete failures (defined as a need for further surgical procedures). In Group I, 74 patients were included in the subjective followup. Forty of the 74 patients also had an objective followup, including roentgenograms and a physical examination. Group II contained 43 patients. Results indicated that the most predictable criterion for success was a negative passive patellar tilt. Secondary criteria included a medial and lateral patellar glide of two quadrants or less and a normal tubercle-sulcus angle at 90 degrees of flexion. Patients had less predictable results after an isolated lateral release with a positive (greater than 5 degrees) passive patellar tilt and a three quadrant or greater medial and lateral patellar glide or an abnormal tubercle-sulcus angle at 90 degrees of flexion.