Modern management of patellar instability

Abstract

Recurrent patellofemoral instability is a disabling condition, attributed to a variety of anatomical aetiologies. Trochlear dysplasia, patella alta, an increased tibial tubercle trochlear groove distance of greater than 20 mm and soft tissue abnormalities such as a torn medial patellofemoral ligament and inadequate vastus medialis obliquus are all factors to be considered. Management of this condition remains difficult and controversial and knowledge of the functional anatomy and biomechanics of the patellofemoral joint, a detailed history and clinical examination, and an accurate patient assessment are all imperative to formulate an appropriate management plan. Surgical treatment is based on the underlying anatomical pathology with an aim to restore normal patellofemoral kinematics. We summarise aspects of assessment, treatment and outcome of patellofemoral instability and propose an algorithm of treatment.

Clinics in diagnostic imaging (163)

“…(3,5,7) Using the Insall-Salvati method, patella alta is present when the length of the patellar tendon divided by the maximal diagonal length of the patella on a lateral knee radiograph produces a ratio of more than 1.2 (normal ratio: 1.0) (Fig. 3).…”

“…(5) A borderline measurement is between 15 mm and 20 mm; when the TT-TG distance exceeds 20 mm, it is nearly always associated with patellar instability. (5,7) Lateral patellar dislocation, which most commonly affects adolescent females, usually occurs when the aforementioned predisposing factors are present. (1,5,12) It most often results from a twisting injury with knee flexion, as the femur rotates internally on a fixed tibia.…”

“…4). (5,7,10) On axial CT and MR imaging at the apex of the intercondylar notch, the lateral trochlear inclination is measured by drawing two lines: (a) along the subchondral bone of the lateral trochlear facet; and (b) along the posterior aspects of the femoral condyles, i.e. the posterior condylar axis (Fig.…”

Magnetic resonance mapping of the rim of articular cartilage defects of the patella

“…Various studies have reported a frequency of cartilage defects between 11 % and 36 % located on the patella, with a mean size of 2.1 cm 2 [1][2][3]. These defects can result from macrotrauma and repetitive microtrauma, are often associated with abnormal patellofemoral stress due to dysplastic morphology of the trochlea groove, and impairment of the soft tissue static stabilisers [4]. Cartilage defects can also occur in combination with varus and valgus malalignment of the tibiofemoral axis and rotational differences in femoral version [5].…”

Acute Compartment Syndrome Following Fulkerson Surgical Technique in Patellofemoral Instability

“…Over one hundred different surgical techniques exist in the treatment of patellar instability yet no gold standard has emerged in the literature [1]. Fulkerson osteotomy technique was designed to restore abnormal force vectors on the patella and decrease pressure on involved cartilage [2].…”