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Managing the lateral side of the patellofemoral joint


OVERVIEW

Chapter synopsis

  • Pathologic tightness of the lateral retinaculum can result in maltracking and hypercompression. After clinical assessment of overall bony alignment and integrity of chondral surfaces, the patient may benefit from a procedure addressing the lateral side of the patellofemoral joint. In this chapter, lateral retinacular lengthening and release techniques are described. Based on outcomes, lengthening is strongly recommended over release to decrease the risk of iatrogenic medial instability or accentuating lateral instability

Important points

Indications

  • Lateral Retinacular Lengthening

    • Lateral patellar maltracking, patellar hypercompression syndrome, lateral patellar instability with lateral retinacular contracture

  • Lateral Release

    • Historically used for patellar hypercompression syndrome, retropatellar crepitus, patellar instability, and patellar maltracking or malalignment

    • Partial lateral release may be indicated in postoperative arthrofibrosis with decreased patellar mobility

    • Complete release is rarely indicated due to the risk of iatrogenic medial patellar instability. When necessary due to too much deformity to lengthen, consider acute reconstruction

Contraindications

  • Medial patellar instability or medial translation greater than one quadrant on physical exam

  • Unaddressed bony malalignment

Surgical technique

  • A lateral release can be performed with either an open or arthroscopic approach. The lateral retinaculum is sectioned approximately 1 cm lateral to the patella at the area of maximal tightness

  • In a lateral lengthening procedure, the superficial and deep layers of the lateral retinaculum are dissected and separated via an open approach. The deep layer is sectioned 1 to 2 cm lateral to the incision in the superficial layer. This creates medial and lateral flaps of the superficial and deep retinacular layers. The free end of the lateral superficial retinacular flap and free end of the medial deep retinacular flap are sutured, creating a lengthened retinacular closure

Clinical/surgical pearls

  • If a lateral release procedure must be performed, a benefit of the open approach is that it allows for the joint capsule to remain intact

Clinical/surgical pitfalls

  • Lateral release procedures should be used with caution due to their high rate of iatrogenic medial instability

  • Diagnostic arthroscopy should be performed at the beginning of the case to assess for the presence of a focal chondral defect that may not have been perceived on magnetic resonance imaging (MRI) as this may necessitate a separate procedure

  • Preoperative assessment of mechanical alignment should rule out additional causative factors, such as genu valgum

Common conditions (epidemiology, pathology, relevant anatomy)

The patella remains centered along the trochlear groove during knee motion through a balance of static and dynamic forces. The primary static restraints to patellar translation are the medial patellofemoral ligament (MPFL), the lateral patellofemoral ligament (LPFL), and the patellofemoral articulation. , The MPFL is the primary restraint to lateral patellar translation and the LPFL is the primary restraint to medial patellar translation. The LPFL additionally functions as a secondary restraint to lateral patellar translation. , Overall, the LPFL and MPFL act in tandem to resist patellar movement in the coronal and axial plane and to ensure central patellar tracking within the trochlear groove. Imbalance of these medial and lateral restraints can be associated with patellar maltracking or instability.

Patellofemoral ligament imbalance can result from either increased laxity of one structure relative to its antagonist, or from over-constraint. Increased laxity of the MPFL can occur from traumatic injury, systemic ligamentous hyperlaxity, or attrition. Increased laxity of the LPFL is most often the iatrogenic result of excessive lateral retinacular release. Evaluation and management of increased laxity in patellofemoral structures are discussed in detail elsewhere. The focus of this chapter is the treatment of lateral retinacular and LFPL contractures resulting in lateral over-constraint.

Contractures of the lateral retinacular structures and LPFL can result in lateral maltracking, increased lateral contact pressures, and lateral patellar tilt. Pathologic contractures of the lateral stabilizers can occur as a result of bony malalignment, such as valgus knee alignment. Evaluation requires careful consideration of the entire extremity. Important factors include femoral anteversion, Q-angle, trochlear dysplasia, tibial-tubercle-trochlear-groove relationship, and MPFL and LPFL integrity. It is important to take a comprehensive approach to rule out or treat all contributing causes of patellar maltracking or instability.

In this chapter, we will review the initial evaluation of the lateral side of the patellofemoral joint. We will then discuss surgical management of excessive lateral retinacular constraint with two commonly performed surgeries—a lateral retinacular release and a lateral lengthening. Preoperative considerations and indications will be outlined, followed by surgical techniques and postoperative outcomes.

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