Quadricepsplasty for Congenital Dislocation of The Patella and Patellar Tendon Shortening for Patella Alta
Jack Andrish
QUADRICEPSPLASTY
Pathogenesis
Congenital dislocation of the patella may be classified as obligatory or fixed.1
Obligatory patellar dislocations may further be characterized as those that dislocate in extension and those that dislocate in flexion.
Whether the dislocations are fixed (permanent) or obligatory as the knee is flexed, contracture of the quadriceps is most often an associated deformity.2
These extensor mechanism contractures are an integral part of the pathology, and patellar alignment procedures that fail to recognize this can result in failure.3,4,5,6
Typically, if one attempts to manually maintain reduction of an obligatory patellar dislocation in flexion when the knee is flexed beyond 30° to 50°, the reduction cannot be maintained. Either the knee will be unable to flex fully or the knee will continue into flexion, but at the expense of allowing the patella to redislocate.
The same condition exists with the surgical alignment of a permanent (fixed) congenital patellar dislocation. Once the extensive lateral releases permit relocation of the patella, attempts to flex the knee will result in either a limitation of flexion or the continuation of knee flexion at the expense of redislocation of the patella.
With this understanding of the pathoanatomy, lengthening of the quadriceps will often be required in order to maintain a successful patellar alignment while maintaining adequate motion.
Extension contractures of the quadriceps that may require quadriceps lengthening can also exist in conditions such as congenital dislocation of the knee, arthrogryposis, and arthrofibrosis.5,6,7,8,9,10,11,12,13
In addition to quadriceps contracture, congenital dislocation of the patella can be complex and involve a number of pathoanatomies that need to be addressed during a surgical correction.1,3,4 These include contracture of the vastus lateralis, the iliotibial tract, and, at times, excessive knee valgus (Figure 31.1). Therefore, in order to obtain proper balance of the extensor mechanism, differential releases and lengthenings are considered.
Figure 31.1 With fixed lateral dislocation of the patella, the displacement of the extensor mechanism promotes knee flexion and external rotation rather than extension. Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2007-2018. All Rights Reserved.
TABLE 31.1 Indications and Contraindications for Quadricepsplasty
Indications
Contraindications
Fixed (congenital) lateral patellar dislocation
Obligatory patellar dislocation in flexion
Arthrofibrosis, arthrogryposis with quadriceps contracture
Severe patella alta requiring distalization
Absence of quadriceps contracture
Noncompliant patient
In the technique described next, we attempt to maintain the width of the quadriceps, but allow for a differential lengthening of the vastus lateralis versus the vastus medialis.
In summary, quadriceps lengthening is required during the surgical treatment of obligatory or fixed patellar dislocations whenever, following relocation, the knee cannot be flexed at or beyond 90° without inducing another obligatory redislocation; or, when patellar relocation is maintained, flexion to 90° is prevented. Quadriceps lengthening is also indicated in patients with an extension contracture that prevents flexion beyond 90°.
Table 31.1 lists indications and contraindications for quadricepsplasty.
Surgical Technique (Video 31.1 
)
)Incision
An anterolateral incision is made that extends from the tibial tuberosity (or distal) to 6 to 10 cm proximal to the patella.
Extensive Lateral-Sided Releases
The initial objective is to perform the necessary lateral releases that will allow relocation of the patella.
One may start by performing dissection between the superficial oblique lateral retinaculum and the deep transverse lateral retinaculum, as described by Larson et al14 (Figure 31.2). This is not always possible because many times these knees have been previously operated upon that had included lateral retinacular release. That said, when dealing with patellar instability, in addition to relocation and rebalancing of the patella, final closure should include recognition of the lateral retinaculum as a contributor to lateral patellar stability. This may require lengthening rather than the release of the lateral retinaculum or, at times, reconstruction of the lateral retinaculum.1,5,13
Next, a complete release of the lateral capsule is made and then dissection is carried out distally into the lateral infrapatellar fat pad where the lateral patellomeniscal ligaments are released (Figure 31.2). This is the final aspect of the lateral release that allows for the peaceful relocation of the patella.
Next, attention is directed proximally where the posterior muscular attachments of the vastus lateralis oblique can be released by sharp and blunt dissection from the lateral intermuscular septum (Figure 31.3).
Quadriceps Lengthening
The method of quadriceps lengthening is first initiated by detaching the vastus lateralis from the proximal/lateral boarder of the patella to 6 to 10 cm proximally (Figure 31.4).
Next, a transverse incision is made across the tendon of the rectus femoris just proximal to the patella. The incision is made to release the rectus tendon but preserving the underlying tendon of the vastus intermedius.
Dissection is then carried out proximally for a distance of about 6 to 8 cm where the release is then carried through the underlying tendon of the vastus intermedius.
The vastus medialis may or may not be required to be incised along the medial boarder of this lengthening.Related posts:
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