Diagnosis and treatment of rotatory knee instability

Abstract

Background: Rotatory knee instability is an abnormal, complex three-dimensional motion that can involve pathology of the anteromedial, anterolateral, posteromedial, and posterolateral ligaments, bony alignment, and menisci. To understand the abnormal joint kinematics in rotatory knee instability, a review of the anatomical structures and their graded role in maintaining rotational stability, the importance of concomitant pathologies, as well as the different components of the knee rotation motion will be presented.

Main body: The most common instability pattern, anterolateral rotatory knee instability in an anterior cruciate ligament (ACL)-deficient patient, will be discussed in detail. Although intra-articular ACL reconstruction is the gold standard treatment for ACL injury in physically active patients, in some cases current techniques may fail to restore native knee rotatory stability. The wide range of diagnostic options for rotatory knee instability including manual testing, different imaging modalities, static and dynamic measurement, and navigation is outlined. As numerous techniques of extra-articular tenodesis procedures have been described, performed in conjunction with ACL reconstruction, to restore anterolateral knee rotatory stability, a few of these techniques will be described in detail, and discuss the literature concerning their outcome.

Conclusion: In summary, the essence of reducing anterolateral rotatory knee instability begins and ends with a well-done, anatomic ACL reconstruction, which may be performed with consideration of extra-articular tenodesis in a select group of patients.

Keywords: Anterolateral; Lateral tenodesis; Rotatory knee instability.

Fig. 1

Radiograph (a) and magnetic resonance imaging exam (b) of a Segond fracture with injury to the anterolateral capsule. The black star denotes the Segond fracture, or an avulsion fracture off the lateral tibial plateau. The black and white errors denote the iliotibial band, while the black arrows demonstrate the anterolateral capsule

Fig. 2

A magnetic resonance imaging of a medial meniscus root tear in conjunction with an anterior cruciate ligament tear. The white arrows point to the meniscus root as it enters its insertion on the tibia. On the top images (a and b), there is fluid underneath the root with no clear attachment to the tibia. The bottom image (c) demonstrates no clear attachment of the root to the tibia

Fig. 3

A ramp lesion on a sagittal magnetic resonance imaging exam (MRI). The white arrow points to a peripheral tear in the posterior horn of the medial meniscus, aka a ramp lesion. These lesions are often missed on MRI, and even during arthroscopic examination

Fig. 4

An anatomic dissection of the lateral aspect of a right knee, with the iliotibial band (ITB) cut and reflected posteriorly (within clamps). The Kaplan fibers (arrow) can be seen running from the superficial ITB, which play a role in rotatory knee stability. The posterior fibers of the ITB (star) blend with the capsulo-osseous layer and the deep ITB to insert on Gerdy’s tubercle. The lateral knee capsule (dotted circle) is also identified

Fig. 5

Anatomic anterior cruciate ligament (ACL) reconstruction on a left knee. a demonstrates 3-4 mm of posterior wall remaining after reaming the femoral tunnel, viewed from the anteromedial portal. b shows the anatomic position of the femoral tunnel viewed from the anteromedial portal, placed within the femoral footprint on the posterior aspect of the condyle. c, viewed from the anterolateral portal, demonstrates the tip aimer placed in the center of the tibia footprint. d demonstrates the final anatomic ACL reconstruction

Fig. 6

The modified Lemaire technique on a left knee. A 1 cm × 8 cm strip of iliotibial band is harvested and detached proximally. The graft is passed deep to the LCL (black arrow) and attached superolaterally to the distal femur at Lemaire’s point with a staple (forceps)