Abstract
BackgroundTo investigate differences in the tibial tubercle-trochlear groove (TT-TG) and patellar tendon-posterior cruciate ligament (PT-PCL) distances in symptomatic patients with non-contact internal knee derangements (IKD) and symptomatic patients with internally intact knees (control).MethodsA retrospective review of MRI studies was completed by comparing 78 patients with meniscal and ligamentous derangements of the knee to 63 internally intact knees (age range, 13 to 50 years). MRI findings were reviewed independently by two board-certified radiologists to assess for agreement. TT-TG and PT-PCL distances were measured on proton density-weighted axial images by two independent observers blinded to the MRI and arthroscopic findings. Independent t tests were used to determine differences in TT-TG distance between the internal derangement and control groups. Chi-square tests were used to compare categorical variables for distributional equality between study groups.ResultsThe mean TT-TG distance averaged across the two raters in the IKD group was 11.5 mm (95% confidence interval [CI], 10.6–12.4), compared to 8.3 mm (95% CI, 7.6–9.0) in the control group (p < 0.001). The mean PT-PCL distance similarly averaged across both raters was 20.6 mm (95% CI, 19.7–21.5) for the IKD group compared to 18.2 mm (95% CI, 17.2–19.2) for the control group (p < 0.001). Among the IKD group, there were 51 meniscal tears, 12 cruciate ligament tears, and 15 tears with a combination of meniscal and cruciate findings. IKD was significantly correlated with greater TT-TG distance (p < 0.001) and greater PT-PCL distance (p < 0.003) when compared with control.ConclusionsIncreased TT-TG distances and PT-PCL distances are associated with both cartilaginous and ligamentous internal knee injuries in the present study, with TT-TG distances greater than the 12 mm representing a new threshold for concern.
Highlights
To investigate differences in the tibial tubercle-trochlear groove (TT-TG) and patellar tendon-posterior cruciate ligament (PT-PCL) distances in symptomatic patients with non-contact internal knee derangements (IKD) and symptomatic patients with internally intact knees
The two independent, blinded rater measurements of TT-TG and PT-PCL distances were assessed as having excellent reliability via a two-way ICC (2, k) mixed model for absolute mean agreement value of 0.985 (95%CI 0.979–0.990) and 0.945 for the TT-TG and PT-PCL measurements respectively and averaged (Fig. 3)
The mean TT-TG distance averaged across the two raters in the IKD group was 11.5 mm (95% confidence interval [CI], 10.6–12.4), compared to 8.3 mm in the control group (p < 0.001)
Summary
To investigate differences in the tibial tubercle-trochlear groove (TT-TG) and patellar tendon-posterior cruciate ligament (PT-PCL) distances in symptomatic patients with non-contact internal knee derangements (IKD) and symptomatic patients with internally intact knees (control). Described on plain film radiographs and later adapted to CT and MRI, the TT-TG distance has been described as a radiographic analog to the quadriceps angle (Q angle) [7,8,9] It has become an increasingly useful measurement given its excellent interrater reliability and ease of use. Given the primary focus on patellar dislocation in previous studies, the control groups have commonly included a variety of other internal knee derangements as long as the clinical history of patellar instability is absent. Building on the findings of Saper et al which raised the possibility of an association between internal derangement (other than a patella-femoral dislocation) and increased lateralization of the patella, this practice is being brought into question by the present study [16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
