Miho J Tanaka1, John J Elias2, Ariel A Williams3, John A Carrino3, Andrew J Cosgarea4. 1. Regeneration Orthopedics, St. Louis, Missouri, U.S.A. 2. Department of Orthopaedic Surgery, Akron General Medical Center, Akron, Ohio, U.S.A. 3. Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland, U.S.A. 4. Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland, U.S.A.. Electronic address: editorialservices@jhmi.edu.
Abstract
PURPOSE: The purpose of this study was to evaluate changes in tibial tuberosity-trochlear groove (TTTG) distance with knee flexion in patients with patellar instability and correlate it with patellar position. METHODS: Patients with symptomatic patellar instability underwent dynamic kinematic computed tomography (CT) during a cycle of knee extension from flexion. Knee flexion angles and corresponding TTTG distances, bisect offset, and patellar tilt were measured. Of the 51 knees, 37 had data available for interpolation between 5° and 30°. Results were interpolated to standardized intervals between 5° and 30° of knee flexion. Repeated-measures analysis (to identify differences between TTTG measurements at various knee flexion angles) and linear regression models (to assess for correlations between TTTG distance and bisect offset and between TTTG distance and patellar tilt) were used. RESULTS: Fifty-one symptomatic knees in 38 patients were available for analysis. Bisect offset and patellar tilt correlated significantly (P < .001) with TTTG distance over all flexion angles. Interpolated results for comparison resulted in 37 knees in which the mean TTTG distance of 17.2 ± 5.8 mm at 5° decreased to 15.5 ± 5.7, 13.0 ± 5.5, and 11.5 ± 4.9 mm at 10°, 20°, and 30° of knee flexion, respectively. Mean TTTG at 5° was 1.5 times greater than that at 30° (P < .001). At 5°, 70.3% (26 of 37) of knees had a TTTG distance of more than 15 mm; at 30°, only 24.3% (9 of 37) exceeded this threshold. CONCLUSIONS: Knee flexion angle during imaging is a critical factor when measuring TTTG distance to evaluate patellofemoral instability. We found that the mean TTTG distance varied by 5.7 mm between 5° and 30° of flexion in patients with symptomatic instability, although this relationship was not completely linear. Bisect offset and patellar tilt measurements mirrored this pattern, suggesting that TTTG distance influences patellar tracking in these patients. LEVEL OF EVIDENCE: Level IV, prognostic case series.
PURPOSE: The purpose of this study was to evaluate changes in tibial tuberosity-trochlear groove (TTTG) distance with knee flexion in patients with patellar instability and correlate it with patellar position. METHODS:Patients with symptomatic patellar instability underwent dynamic kinematic computed tomography (CT) during a cycle of knee extension from flexion. Knee flexion angles and corresponding TTTG distances, bisect offset, and patellar tilt were measured. Of the 51 knees, 37 had data available for interpolation between 5° and 30°. Results were interpolated to standardized intervals between 5° and 30° of knee flexion. Repeated-measures analysis (to identify differences between TTTG measurements at various knee flexion angles) and linear regression models (to assess for correlations between TTTG distance and bisect offset and between TTTG distance and patellar tilt) were used. RESULTS: Fifty-one symptomatic knees in 38 patients were available for analysis. Bisect offset and patellar tilt correlated significantly (P < .001) with TTTG distance over all flexion angles. Interpolated results for comparison resulted in 37 knees in which the mean TTTG distance of 17.2 ± 5.8 mm at 5° decreased to 15.5 ± 5.7, 13.0 ± 5.5, and 11.5 ± 4.9 mm at 10°, 20°, and 30° of knee flexion, respectively. Mean TTTG at 5° was 1.5 times greater than that at 30° (P < .001). At 5°, 70.3% (26 of 37) of knees had a TTTG distance of more than 15 mm; at 30°, only 24.3% (9 of 37) exceeded this threshold. CONCLUSIONS: Knee flexion angle during imaging is a critical factor when measuring TTTG distance to evaluate patellofemoral instability. We found that the mean TTTG distance varied by 5.7 mm between 5° and 30° of flexion in patients with symptomatic instability, although this relationship was not completely linear. Bisect offset and patellar tilt measurements mirrored this pattern, suggesting that TTTG distance influences patellar tracking in these patients. LEVEL OF EVIDENCE: Level IV, prognostic case series.
Authors: Anna Hirschmann; Florian M Buck; Ramin Herschel; Christian W A Pfirrmann; Sandro F Fucentese Journal: Knee Surg Sports Traumatol Arthrosc Date: 2015-11-04 Impact factor: 4.342
Authors: Kristin H Graf; Marc A Tompkins; Julie Agel; Elizabeth A Arendt Journal: Knee Surg Sports Traumatol Arthrosc Date: 2017-04-04 Impact factor: 4.342
Authors: Victor R Carlson; Frances T Sheehan; Aricia Shen; Lawrence Yao; Jennifer N Jackson; Barry P Boden Journal: Am J Sports Med Date: 2017-04-18 Impact factor: 6.202
Authors: John J Elias; Kerwyn C Jones; S Cyrus Rezvanifar; Joseph N Gabra; Melanie A Morscher; Andrew J Cosgarea Journal: Knee Date: 2018-03-13 Impact factor: 2.199
Authors: Arya Haj-Mirzaian; Ali Guermazi; Michael Hakky; Christopher Sereni; Bashir Zikria; Frank W Roemer; Miho J Tanaka; Andrew J Cosgarea; Shadpour Demehri Journal: Eur Radiol Date: 2018-04-30 Impact factor: 5.315
Authors: Alex E White; Peters T Otlans; Dylan P Horan; Daniel B Calem; William D Emper; Kevin B Freedman; Fotios P Tjoumakaris Journal: Orthop J Sports Med Date: 2021-05-20