The relationship between tibial tuberosity-trochlear groove distance and abnormal patellar tracking in patients with unilateral patellar instability

Ariel A. Williams, John J. Elias, Miho J. Tanaka, Gaurav K. Thawait, Shadpour Demehri, John A. Carrino, Andrew J. Cosgarea

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41 Scopus citations


Purpose To evaluate the role of tibial tuberosity-trochlear groove (TT-TG) distance in patellofemoral kinematics by retrospectively reviewing the dynamic computed tomography scans of patients with unilateral patellofemoral instability and comparing unstable and contralateral asymptomatic knees. Methods We reviewed all dynamic computed tomography scans obtained at one tertiary care hospital from 2008 through 2013 and identified 25 patients with a history of recurrent unilateral patellofemoral instability. During the scans, subjects performed active knee extension against gravity. Both knees were imaged simultaneously. Lateral patellar tilt (LPT) and bisect offset (BO) were measured to assess tracking. TT-TG distance was measured to assess alignment. Measurements were made in full extension, maximum flexion, and approximately 10° increments in between. The significance level was set at P <.05. Results LPT, BO, and TT-TG distance were highest in extension and decreased with flexion. Measurements were higher in symptomatic than in asymptomatic knees, with significant differences identified for LPT, BO, and TT-TG distance at 5° and 15° and for TT-TG distance at 25° and 35° (P <.05). TT-TG distance was associated with LPT and BO, with r2 values in symptomatic knees of 0.55 for TT-TG distance and LPT and of 0.45 for TT-TG distance and BO. Conclusions In patients with unilateral patellar instability, LPT, BO, and TT-TG distance are higher on the unstable side. An association exists between TT-TG distance and the tracking parameters studied, suggesting that TT-TG distance relates to patellar tracking, and a laterally positioned tibial tuberosity may predispose to instability episodes. Level of Evidence Level IV, diagnostic study.

Original languageEnglish (US)
Pages (from-to)55-61
Number of pages7
JournalArthroscopy - Journal of Arthroscopic and Related Surgery
Issue number1
StatePublished - 2016

Bibliographical note

Funding Information:
The authors report the following potential conflicts of interest or sources of funding: J.A.C. receives support from GE, Bioclinica, and Pfizer. S.D. receives support from the General Electric Association of University Radiologists Radiology Research Academic Fellowship.

Publisher Copyright:
© 2016 Arthroscopy Association of North America.


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