chapter 8: Patellar Tilt‑Compression and the Excessive Lateral Pressure Syndrome (ELPS)
Causes of Excessive Lateral Ligamentous Tension
Abnormal tension in the lateral retinaculum probably develops in the course of growth, only to be clinically revealed after an injury or with the passage of time. This concept is not so strange if one thinks about the more apparent anomalies that may remain clinically silent for many years, that is, genu varum, femoral anteversion, dysplasia of the hip, and so on. It also explains three clinical situations that are not rare: (1) a radiograph taken immediately or soon after an injury shows clearly evident lateral joint line narrowing. ELPS, therefore, pre‑existed the injury. (2) Conservative measures may render a patient with ELPS symptom‑free; however, the radiographic evidence remains unchanged. (3) There may be radiologic evidence of excessive lateral tilt on the clinically "normal" side. Thus, it appears that excessive lateral tilt may pre‑exist clinical symptoms, only to be revealed when additional factors add to the disequilibrium.
It is most likely, however, that lateral retinacular shortening occurs secondary to chronic lateralization and/or tilt of the patella. If there is a persistent lateral malalignment, there will be adaptive shortening of the lateral retinaculum. This adaptively shortened retinaculum will not only perpetuate, but may actually aggravate, an existing patellar lateralization or tilt of the patella. The adaptively shortened retinaculum ultimately causes articular problems (ELPS), particularly as the child grows into adolescence and adulthood.
K‑wire fixation for fracture treatment, local trauma, or capsulitis (dystrophy) may lead to the formation of abnormal lateral tethering forces that may be at the origin of excessive lateral tension. The same thing may happen also on the medial side. However, this is much less common.
We have seen that abnormal fascial bands may be responsible for congenital or recurrent dislocation of the patella. They may also, in a lesser form, be responsible for the excessive lateral tension that leads to ELPS. The latter two causes account for approximately 10% of cases.
Inside Chapter 8: