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            The Role of Lateral Retinacular Release in the

                     Treatment of Patellar Instability.

                  Christian Lattermann, MD1; John Toth, DO2;

                          and Bernard R. Bach Jr., MD3


1) Assistant Professor
University of Kentucky, Orthopaedic Sports Medicine
Director, University of Kentucky Center for Cartilage Repair and Restoration
Kentucky Clinic K401
Lexington KY 40536


2) Resident, Orthopaedic Surgery
Botsford General Hospital
28050 Grand River Ave.
Farmington Hills , MI 48336


3) Professor and Chief, Division of Sports Medicine
Department of Orthopedic Surgery
Rush University Medical Center
1725 W. Harrison Street, Suite 1063
Chicago IL 60612


ADDRESS FOR REPRINTS/CORRESPONDENCE:

Bernard R. Bach, Jr., M.D.
Division of Sports Medicine
Rush University Medical Center
1725 W. Harrison St., Suite 1063
Chicago, IL 60612
e-mail: brbachmd@comcast.net
Phone: 312-432-2353
Fax: 312-942-1517


Running Title: Lateral retinacular release for patella instability
                                          -2-


Introduction:

       Anterior knee pain is generally perceived as a difficult condition to treat for

Orthopaedic surgeons. Treatment regimens have been described since the

roman times (Galen 129-200 AD)1. Even though our understanding of the

extensor mechanism and the patellofemoral joint has improved tremendously

many questions remain open and continue to be investigated. One of these

questions is the role of a lateral retinacular release in the treatment of anterior

knee pain. This procedure, performed open, mini-open or arthroscopically has

been proposed as an isolated procedure, in combination with proximal

realignment procedures of the patella or in combination with distal realignment
             2-17
procedures          . While several authors have been able to show that the isolated

lateral release can be a successful procedure in patients with isolated lateral

patellar tightness the role of lateral release for the treatment of patella instability

is much less clearly established.

       The goal of this review article is to shed light on the role of the lateral

retinacular release for the treatment of patellar instability.



Diagnosis of patella instability:

       The clinical diagnosis of patella instability can be challenging. Merchant

and Mercer described the first lateral retinacular release in 1974 but did not

emphasize the importance of history and physical exam findings for the indication

of this procedure 9. Hughston et al. first stressed the importance of history and

physical exam findings and also described what they called the “passive lateral
                                              -3-


hypermobility” of the patella. They described a “loose” and a “tight” retinaculum 1.

Post outlined the key physical exam findings that need to be established for the

evaluation of clinical instability in his excellent review 18 .

       In brief, the entire involved lower extremity has to be taken into account.

Factors such as core weakness, increased valgus alignment, generalized

ligamentous laxity and increased foot pronation as well as increased femoral

anteversion have shown to be factors that can contribute to anterior knee pain

and patella instability. History of the initial onset of pain, symptoms of

subluxation, specific injuries or painful positions or activities (i.e. ascending /

descending stairs) have to be recorded It has been clearly established that

muscular tightness (quadriceps, hamstring, IT band, hip extensors) plays a

significant role for patellar stability. The muscle balance of the VMO versus the

vastus lateralis is important since a significant imbalance between VMO and

vastus can lead to a dynamic instability of the patella during active extension of

the knee. This can be assessed clinical by looking for the J-sign. This describes

the course of the patella coming from full extension and a lateral position and

suddenly reducing to a medial or centered position in the trochlea with further

flexion. This inverted –J course of the patella is called the “J-sign”. While the true

anatomical correlation of this phenomenon is unclear Johnson could show that

this is a finding that is unique to patients with anterior knee pain indicating
                               19
abnormal patella tracking           . Patella mobility is another major factor that needs

to be evaluated. The assessment of medial/ lateral patella glide (also know as
               20
“Sage sign”)        as well as patellar tilt help determine if the peripatellar soft tissue
                                        -4-


restraints predispose the patella to lateral subluxation. The assessment of the
                                                                           21
overall extensor alignment can be performed by assessing the Q-angle            . This

should be done at 30º and 90º in order to assess the dynamic component of the

Q-angle. This dynamic assessment of the Q-angle mimics what may happen

when a patient plants their foot, flexes the knee and externally rotates the tibia.

Post concludes that the simple determination of the position of the tibial tubercle

in line or lateral to the midline of the patella may be just as helpful since no

reliable data exists that determines the exact value of a “pathologic” Q-angle 14.

       Once the clinical diagnosis of patella instability has been made imaging

modalities may help to corroborate the clinical findings.



Imaging:

       While static imaging of the patello-femoral joint is helpful one has to keep

in mind that the pathology may be mainly a dynamic one. The examiner therefore

has to take the physical findings into account while assessing the radiographic

studies.

The routine standing anteroposterior views may help in the overall assessment of

knee alignment but generally do not yield much information concerning the

stability of the patella. More informative is the evaluation of patellar height, the

relationship of the patella to the trochlea and the anatomic shape of the trochlear

groove in the 30° flexion lateral view of the knee. This view allows the

assessment of patellar height by any of the published parameters (Insall/Salvati,

Blackburn/Peel or Caton / Linclau). In addition this view allows for the analysis of
                                          -5-


the trochlear groove as described by Dejour et al. 1. The requirements are a

perfect lateral radiograph (posterior condyles overlapping). The sunrise view of

the patella in 30° of flexion (Merchant view) has been advocated to evaluate

patellar tracking in the trochlea. Teitge described a bilateral stress-radiograph in

this position utilizing a standardized lateral force 23.

       A CT scan of the patellofemoral joint at 0°, 15°, 30° and 45° knee flexion

providing precise midpatellar transverse images has been found helpful and
                                                      24-25
sensitive in the evaluation of patellar instability           .In addition if a CT scan slice

of the trochlear groove is overlayed with a CT slice of the proximal tibia showing

the tibial tubercle, the trochlea tibial tubercle distance (TG/TT) can be

determined. This parameter helps to diagnose excessive lateralization of the

tibial tubercle 26.

       An MRI scan may provide useful information about the status of the lateral

retinaculum (thickening) or the medial restraints (MPFL) as well as cartilage

injuries in the patellofemoral joint.



Isolated lateral release for patella instability:

       Throughout the last two decades it became clear that anterior knee pain is

more than just one entity. The history of the isolated lateral retinacular release

portrays this evolution of knowledge in a typical fashion. The lateral retinacular

release was initially indiscriminantly used for anterior knee pain, patella instability

and also as a treatment for osteoarthritis of the patellofemoral joint (2-17). Ficat
                                                                                    27
introduced the concept of the “excessive lateral pressure syndrome”                      which
                                        -6-


helped to redefine the indication for an isolated lateral release. It has now been

recognized that this condition is an acceptable indication for an isolated lateral

retinacular release that yields reproducible and predictably good results 28.

       To this date there are no published randomized controlled clinical trials

(Level 1 evidence) assessing the effect of an isolated lateral retinacular release

on the outcome of patellar instability. All currently available material is at best

level 4 evidence (retrospective case series, or review articles). A formal

systematic review is therefore not possible.

       Evaluating the published case series, numerous authors have reported

their results. While some authors initially reported acceptable success of this

procedure for patella instability most studies showed disappointing mid and long-

term results. The average percentage of satisfaction of patients in studies with

more than 4 years follow up is only 63.5% whereas the short term (< 4 years)

satisfaction is 80% (Table 1). Aglietti et al. compared three different treatment

options for recurrent patella dislocations in a retrospective study He found that

the isolated lateral release showed by far the worst long term outcomes and led
                                                     29
to recurrent dislocations in 35% of their patients        . This finding is corroborated

by Dainer et al. who showed that an isolated lateral release as treatment for

recurrent patella dislocation is as effective as a diagnostic knee scope and does
                                       30
not improve the clinical outcome            . Kolowich et al. performed a study

investigating patients after isolated lateral retinacular release. They divided the

results into two groups. Group 1 consisted of patients that had a good or

excellent outcome and group 2 consisted of patients with average or poor
                                        -7-


outcome. In this study she could show that patients doing poorly after isolated

lateral release predominantly had symptoms of patella instability in addition to

pain 21.

       Furthermore it has been recognized that overzealous lateral release or

failure to assess concomitant pathology of the patellofemoral joint can lead to

catastrophic results. If the lateral retinacular release is carried out further

proximal than the superior patella pole, it can cause medial patellar instability. In

the presence of severe medial patellar articular lesions (as can often be seen in

patients who suffered numerous patella dislocations) a lateral retinacular release

may increase the load to the defect which may be detrimental.        Furthermore, if

the patient has an increased Q angle, isolated lateral release may in fact

increase the Q angle resulting in increasing symptoms of instability.

       Fithian, Fulkerson and others have therefore recommended the lateral

release as an adjunct procedure for a proximal patellar alignment in combination

with medial retinacular reefing or reconstruction of the medial patellofemoral

ligament (MPFL) 22,28,32 .



Lateral release as adjunct to patellofemoral alignment procedures for

patellar instability:

       Lateral release of the retinaculum alone does not restore normal

orientation of the malaligned extensor mechanism. This is the reason why most

leading surgeons recommend a combined proximal realignment of the patella.

The most important factor in the assessment of these patients is the evaluation of
                                        -8-


the medial patellar restraints. If the medial patellofemoral ligament (MPFL) is felt

to be ruptured or absent a MPFL reconstruction may be necessary. If the MPFL

appears intact but an increased medial patellar glide is present an imbrication of

the medial retinaculum can be performed.            Insall first recommended an

imbrication of the medial retinaculum. Many authors today feel that the

imbrication and / or reconstruction of the MPFL should be adjusted to the original
                                                          28
anatomic length allowing a normal lateral patella glide        . Clinically this is difficult

to judge. The passive patellar glide can be utilized as a guideline when compared

to the opposite side. This can be done manually or with intrumented laxity

testing, as described by Fithian et al. 32. A lateral release is almost always added

to these medial imbrication procedures to allow a centered glide of the patella. It

is important that the lateral release is done cautiously and not in an excessive

fashion.

       In cases of anatomic malalignment of the extensor mechanism requiring a

distal or even a combined proximal and distal realignment a lateral release is

often added after the realignment has been perfomed. Particularly after a

tubercle anteromedialization (Fulkerson) the lateral retinaculum can capture the

patella tendon. In these cases the lateral retinacular release should be performed

under direct vision. The extent of the release is usually limited to the amount

necessary to allow a free passage of the patellar tendon throughout the entire

range of motion.
                                        -9-


Dangers of lateral retinacular release in patella instability:

         The lateral retinacular release is often looked at as a quick, small and

forgiving procedure that can be perfomed percutaneously or arthroscopically.

While there are technical errors during the surgical release that can lead to

excessive bleeding, skin injury or subcutaneous burns, the most imminent

danger and complication of an isolated lateral release is the overzealous or non-

indicated lateral release leading to medial patella instability.    Medial patellar

instability is a debilitating situation that can be frustrating to deal with for the

patients as well as for the surgeon. To avoid this problem Fulkerson advised

limiting the lateral release to the required amount as judged by the desired effect
20
     . He recommends that the retinaculum should not be released past the proximal

pole of the patella in order to avoid detachment of the vastus lateralis obliquus.

Historically, some authors recommended sufficient lateral release to evert the

patella anywhere from 45 to 90 degrees. In most cases this may be too much of

a release.
                                       - 10 -




Conclusion:

      Concluding this review of the literature it appears that the most important

question to ask may be when a lateral retinacular release can be recommended

for the treatment of patella instability? The answer to this question can be

summarized in a few bullet points:

          •   An isolated lateral retinacular release has little or no role in the

              treatment of acute or recurrent patella instability. This procedure

              should be reserved for the few patients with a clearly identified

              lateral patella compression syndrome in presence of a tight lateral

              retinaculum and clearly discernable lateral retinacular pain

          •   A lateral release procedure may be added as an adjunct procedure

              to a proximal or distal realignment of the extensor mechanism. In

              these cases the release has to be done judiciously and has to be

              gauged by the desired effect (i.e. release of contracted lateral

              retinaculum due to chronically ruptured MPFL)

          •   Care has to be taken that the lateral retinaculum is not “over-

              released” leading to a potentially devastating medial patellar

              instability.

          •   If a patient who has patellar instability and an increased Q angle

              undergoes isolated lateral release, increased patellar instability

              symptoms may occur secondary to a dynamic increase in the Q

              angle.
                                        - 11 -




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                                   - 12 -


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                                   - 13 -


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