Evaluation of patellar tracking in patients with suspected patellar malalignment: cine MR imaging vs arthroscopy.

Abstract

OBJECTIVE.The CONCLUSION.We conclude that motion-triggered cine MR imaging of active extension of the knee enables the dynamic evaluation of patellar bracing and is therefore suitable for noninvasive analysis of patellar tracking.

The Measurement of Patellar Alignment in Patellofemoral Pain Syndrome: Are We Confusing Assumptions With Evidence?

“…Logic would suggest there is a difference; science has yet to examine it. As McNally et al 56 7 demonstrated significant correlation between what they termed a "semi-quantitative" arthroscopic assessment of patellar tracking and patellar tracking as measured by non-weight-bearing dynamic MRI films. However, the semiquantitative assessment was itself solely based upon the arthroscopist's subjective impression of normal patellar tracking.…”

“…2,35 Other studies on the measurement of patellar alignment have restricted their subjects to only those with clinically proven subluxation/dislocation. 7,37,58,71 In contrast, when authors have differentiated between PFPS and patellar subluxation/dislocation, they have reported large and significant differences in patellar alignment between these 2 diagnostic groups, 1,28,50 as well as no difference between individuals with PFPS versus asymptomatic patellae. 92 Other definitions of patient populations for patellofemoral measurement studies include clinical subsets, such as "anterior knee pain resistant to conservative treatment," 56 and groups with a vague and unspecified collection of signs and symptoms, such as "suspicion of patellofemoral pain/malalignment, requiring tracking studies" 62 or "symptoms of pain or instability."…”

“…Qualitative methods of patellofemoral alignment measurement have been established, 7,85 but these inevitably involve a degree of subjectivity. 56 The most commonly used qualitative method of assessment has been described by Shellock et al 85 and defines normal patellar alignment in terms of the median ridge of the patella being positioned in the femoral trochlear groove, and the medial and lateral patellar facets articulating with the medial and lateral aspects of the femoral trochlea.…”

“…While reliability scores for the measurement of various indices on radiograph/ MRI/CT images have been documented, with results ranging from excellent, 100 to good, 12,69 to poor, 12,39,75 the reporting of reliability is by no means exhaustive. Many studies do not evaluate the reliability of their measurement techniques 1,7,28,56,84,85 or simply state that reliability was good without giving any details. 58,62 However, to the best of the author's knowledge, the reliability of the actual radiograph/CT/MRI imaging procedure itself in the assessment of patellar alignment (ie, the reliability over repeated testing sessions) has only been investigated in 3 studies.…”

“…56,62,100 Many authors see arthroscopy as the most logical option. 7,40,53,60,88 In their review of this area, Muhle et al 60 concluded that, "Arthroscopy is a valuable technique for assessing patellofemoral problems and is considered the gold standard for evaluating and visualizing patellar position and tracking." However, there remains a vitally important question that researchers have yet to address: how much does patellar tracking, as demonstrated passively at arthroscopy in the non-weight-bearing, grossly swollen, electromyographically silent knee of the unconscious patient, correlate with that performed actively in the weight-bearing, noneffused, electromyographically active knee of the conscious patient?…”