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
Running Title: Lateral retinacular release for patella instability
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
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
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
abnormal patella tracking . Patella mobility is another major factor that needs
to be evaluated. The assessment of medial/ lateral patella glide (also know as
“Sage sign”) as well as patellar tilt help determine if the peripatellar soft tissue
restraints predispose the patella to lateral subluxation. The assessment of the
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.
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
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
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
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
introduced the concept of the “excessive lateral pressure syndrome” which
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
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
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
outcome. In this study she could show that patients doing poorly after isolated
lateral release predominantly had symptoms of patella instability in addition to
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
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
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
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
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.
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
. 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
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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
• 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
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