الفهرس 
Anatomy & Dynamics of the Patellofemoral JointOnly 14 pages are availabe for public view
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Abstract
T
he PF joint is one of the most complex joints in the body. Because of its complicated biomechanical structure, the joint is highly subjected to instability and dislocation. The recent increase in various sport activities raises the incidence of PF joint problems.
The MPFL plays a chief role in patellar instability, damage to the ligament as well as bony avulsion fractures can be demonstrated on US scans. Even with acute injuries in the presence of edema and hematoma, the disruption to the anatomy of the MPFL can be reliably assessed on sonography. In case the initial diagnosis of transient patellar dislocation is uncertain or if the injury is recurrent, sonography can assess the degree of disruption to the anatomy of the medial retinaculum, if present.
Trochlear dysplasia is one of the leading risk factors to developing patellar instability and can be assessed by measuring the sulcus angle on digital radiography as well as sonography; in that case the patient is spared from exposure hazards.
High resolution US shows a promising role in detecting the integrity and course of the MPFL ligament. The LPFL however, was not also detected by ultrasonography and this was in agreement with previous studies done to assess that ligament.
Patellar position was assessed through X-ray and US. The former evaluated patellar height in the superio-inferior direction using Insall-Salvati ratio. The latter defined patellar position in the medio-lateral direction as the lateral PCD.
Dynamic US examination of the patella in those patients within the objective instability group demonstrated a rather exaggerated lateral movement of the patella overriding the lateral femoral condyle.
In conclusion:
For the patient with pain in the anterior knee attributable to the PF joint, plain radiography is most likely to be the first investigation. It is important to note that a significant amount of information can be gained from radiographic studies, but they are limited in that they provide static images of a dynamic joint and subject patients to radiation.
High Resolution US is emerging as a viable imaging modality in the diagnosis and assessment of the musculoskeletal system. Advantages of ultrasound include it is non invasive, well accepted by patients, available, the ability to compare easily with the contralateral side, multi planar and dynamic evaluation, as well as its economic advantages. Unlike other modalities such as MRI & CT, the patient’s exact point of clinical tenderness can be correlated with underlying anatomical structures and associated pathology.
Dynamic US has a promising role in assessing patellar instability but further work is needed to establish solid diagnostic grounds. Dynamic US offers a relatively cheap and safe method to assess joint mobility and that makes it exceptional and worth exploring further.