- Email: [email protected]
Combined MPFL Reconstruction and Tibial Tubercle Transfer for Patellofemoral Instability
e14
ABSTRACTS
asked to perform a cycle of knee extension from flexion while imaging data was acquired at 0.5 second intervals. Knee flexion angles and corresponding TTTG distances, bisect offset, and patellar tilt were measured for each image by a single observer. Results were grouped by flexion angles and paired t-tests were used to identify significant differences between TTTG distances at -5 to 5 and 25 to 35 of knee flexion. Linear regression models were used to assess for correlations between TTTG distance and bisect offset, as well as TTTG distance and patellar tilt. Results: In 51 symptomatic knees, the average TTTG distance at -5 to 5 was 18.8 1.6 mm and decreased to 11.9 1.4 mm at 25 to 35 of knee flexion. The TTTG measurements were 6.8 mm and 1.6 times greater at -5 to 5 than at 25 to 35 (p<0.001). Bisect offset (R2 tilt (R2¼ 0.57) correlated significantly (p <0.001) with TTTG distance over all flexion angles. At -5 to 5 of knee flexion, 77.8% (35/45) of knees had a TTTG measurement greater than 15 mm, whereas only 28.6% (14/49) exceeded this threshold at 25 to 35 of knee flexion. Conclusion: The angle of flexion while the knee is being imaged is a critical factor to consider when measuring TTTG distance in the evaluation of patellofemoral instability. In our study, we found that the TTTG distance was 1.6 times greater and varied by 6.8 mm between -5 to 5 and 25 to 35 of knee flexion in patients with symptomatic instability. Bisect offset and patellar tilt measurements mirrors this pattern, suggesting that TTTG distance influences patellar tracking in patients with patellar instability. An improved understanding of the relationship between TTTG distance and patellar tracking and variations in the TTTG distance with the flexion angle will help clinicians evaluate and treat patellofemoral instability. Combined MPFL Reconstruction and Tibial Tubercle Transfer for Patellofemoral Instability SS-26 Thursday, May 1, 5:45 PM CHRIS HADLEY, B.A., PRESENTING AUTHOR BRANDON ECK, B.S. FOTIOS TJOUMAKARIS, M.D. MATTHEW PEPE, M.D. LUKE AUSTIN, B.S., M.D. ROBERT FREDERICK, M.D. BRADFORD TUCKER, M.D. Introduction: Both medial patellofemoral ligament (MPFL) reconstruction and Tibial Tubercle Transfer (TTT) are established procedures for patients suffering from patellofemoral instability. In patients with a heightened Q angle, MPFL reconstruction performed in isolation may increase contact forces across the patellofemoral joint and not restore medial patellar tracking. The purpose of the present study is to determine the outcomes of combined MPFL and TTT for patellar instability with elevated Q angle. Methods: 32 patients were identified from a surgical database of having received combined MPFL reconstruction and TTT from 2008-2010. All patients were treated by one of four fellowship trained sports medicine physicians utilizing an identical surgical technique. Minimum follow-up was
24 months for inclusion in the study. Patients were evaluated for recurrence of instability, complications, and functional outcome (Kujala and Lysholm outcome scores). Results: Of the 32 patients (35 knees) that underwent this procedure during the time period studied, 20 patients (22 knees) met our inclusion criteria and are included in this analysis. The average length of follow-up was 39 months (range 28 to 50). There were 1 male(s) and 19 females in this analysis, with an average age of 25. The average Kujala and Lysholm scores at final follow-up were 81.09 and 75.41, respectively. One patient(s) (5.0%) sustained a recurrence of dislocation. There were 5 (25.0%) patients with complications: wound complications requiring repeat surgery (3/15.0%), stiffness (2/10.0%), chondroplasty (1/ 5.0%) and lysis of adhesions (1/5.0%). There were no infections in this series. 4 (16.7%) patients required a secondary procedure to remove painful hardware. Conclusion: MPFL reconstruction combined with tibial tubercle transfer has a high rate of success for patients presenting with patellar instability and extensor mechanism mal-alignment. The risk of recurrence with this technique was low (5.0%), and the risk of complications is equivalent to other techniques previously reported in the literature. Biomechanical Analysis of Current Medial Patellofemoral Ligament Reconstruction Techniques using Human Gracilis Allograft SS-27 Thursday, May 1, 5:50 PM PATRICK JOYNER, M.D., M.S., PRESENTING AUTHOR TRAVIS ROTH, M.S.I.V. SCOTT WINNIER, PH.D. LUKE WILCOX, D.O. RYAN HESS, M.D. JEREMY BRUCE, M.D. TIM FRERICHS, M.D. AARON MATES, M.D. CHARLES ROTH, M.D. Introduction: Medial patellofemoral ligament reconstruction is a common surgery for acute and chronic dislocating patellas. Current surgical techniques may employ suspensory cortical fixation as well as a human gracilis allograft. In this study we aim to examine the biomechanical strength of suspensory cortical fixation as it compares to the strength of the native medial patellofemoral ligament. As a secondary outcome measure, we examine the integrity of the human gracilis allograft. Methods: Six matched pair fresh human cadavers where used for the analysis of five different medial patellofemoral ligament reconstruction techniques: suspensory cortical fixation in patella and femur, suspensory cortical fixation patella interference screw femur, interference screw patella suspensory cortical fixation femur, interference screw patella and femur, two suture anchors patella suspensory cortical fixation femur. The vector force was directed laterally over the lateral femoral condyle, in an anatomic direction, while the knee was flexed 25 . Each method of fixation was examined six separate times; each reconstruction utilizing a new human gracilis allograft. Methods of fixation where
ABSTRACTS
asked to perform a cycle of knee extension from flexion while imaging data was acquired at 0.5 second intervals. Knee flexion angles and corresponding TTTG distances, bisect offset, and patellar tilt were measured for each image by a single observer. Results were grouped by flexion angles and paired t-tests were used to identify significant differences between TTTG distances at -5 to 5 and 25 to 35 of knee flexion. Linear regression models were used to assess for correlations between TTTG distance and bisect offset, as well as TTTG distance and patellar tilt. Results: In 51 symptomatic knees, the average TTTG distance at -5 to 5 was 18.8 1.6 mm and decreased to 11.9 1.4 mm at 25 to 35 of knee flexion. The TTTG measurements were 6.8 mm and 1.6 times greater at -5 to 5 than at 25 to 35 (p<0.001). Bisect offset (R2 tilt (R2¼ 0.57) correlated significantly (p <0.001) with TTTG distance over all flexion angles. At -5 to 5 of knee flexion, 77.8% (35/45) of knees had a TTTG measurement greater than 15 mm, whereas only 28.6% (14/49) exceeded this threshold at 25 to 35 of knee flexion. Conclusion: The angle of flexion while the knee is being imaged is a critical factor to consider when measuring TTTG distance in the evaluation of patellofemoral instability. In our study, we found that the TTTG distance was 1.6 times greater and varied by 6.8 mm between -5 to 5 and 25 to 35 of knee flexion in patients with symptomatic instability. Bisect offset and patellar tilt measurements mirrors this pattern, suggesting that TTTG distance influences patellar tracking in patients with patellar instability. An improved understanding of the relationship between TTTG distance and patellar tracking and variations in the TTTG distance with the flexion angle will help clinicians evaluate and treat patellofemoral instability. Combined MPFL Reconstruction and Tibial Tubercle Transfer for Patellofemoral Instability SS-26 Thursday, May 1, 5:45 PM CHRIS HADLEY, B.A., PRESENTING AUTHOR BRANDON ECK, B.S. FOTIOS TJOUMAKARIS, M.D. MATTHEW PEPE, M.D. LUKE AUSTIN, B.S., M.D. ROBERT FREDERICK, M.D. BRADFORD TUCKER, M.D. Introduction: Both medial patellofemoral ligament (MPFL) reconstruction and Tibial Tubercle Transfer (TTT) are established procedures for patients suffering from patellofemoral instability. In patients with a heightened Q angle, MPFL reconstruction performed in isolation may increase contact forces across the patellofemoral joint and not restore medial patellar tracking. The purpose of the present study is to determine the outcomes of combined MPFL and TTT for patellar instability with elevated Q angle. Methods: 32 patients were identified from a surgical database of having received combined MPFL reconstruction and TTT from 2008-2010. All patients were treated by one of four fellowship trained sports medicine physicians utilizing an identical surgical technique. Minimum follow-up was
24 months for inclusion in the study. Patients were evaluated for recurrence of instability, complications, and functional outcome (Kujala and Lysholm outcome scores). Results: Of the 32 patients (35 knees) that underwent this procedure during the time period studied, 20 patients (22 knees) met our inclusion criteria and are included in this analysis. The average length of follow-up was 39 months (range 28 to 50). There were 1 male(s) and 19 females in this analysis, with an average age of 25. The average Kujala and Lysholm scores at final follow-up were 81.09 and 75.41, respectively. One patient(s) (5.0%) sustained a recurrence of dislocation. There were 5 (25.0%) patients with complications: wound complications requiring repeat surgery (3/15.0%), stiffness (2/10.0%), chondroplasty (1/ 5.0%) and lysis of adhesions (1/5.0%). There were no infections in this series. 4 (16.7%) patients required a secondary procedure to remove painful hardware. Conclusion: MPFL reconstruction combined with tibial tubercle transfer has a high rate of success for patients presenting with patellar instability and extensor mechanism mal-alignment. The risk of recurrence with this technique was low (5.0%), and the risk of complications is equivalent to other techniques previously reported in the literature. Biomechanical Analysis of Current Medial Patellofemoral Ligament Reconstruction Techniques using Human Gracilis Allograft SS-27 Thursday, May 1, 5:50 PM PATRICK JOYNER, M.D., M.S., PRESENTING AUTHOR TRAVIS ROTH, M.S.I.V. SCOTT WINNIER, PH.D. LUKE WILCOX, D.O. RYAN HESS, M.D. JEREMY BRUCE, M.D. TIM FRERICHS, M.D. AARON MATES, M.D. CHARLES ROTH, M.D. Introduction: Medial patellofemoral ligament reconstruction is a common surgery for acute and chronic dislocating patellas. Current surgical techniques may employ suspensory cortical fixation as well as a human gracilis allograft. In this study we aim to examine the biomechanical strength of suspensory cortical fixation as it compares to the strength of the native medial patellofemoral ligament. As a secondary outcome measure, we examine the integrity of the human gracilis allograft. Methods: Six matched pair fresh human cadavers where used for the analysis of five different medial patellofemoral ligament reconstruction techniques: suspensory cortical fixation in patella and femur, suspensory cortical fixation patella interference screw femur, interference screw patella suspensory cortical fixation femur, interference screw patella and femur, two suture anchors patella suspensory cortical fixation femur. The vector force was directed laterally over the lateral femoral condyle, in an anatomic direction, while the knee was flexed 25 . Each method of fixation was examined six separate times; each reconstruction utilizing a new human gracilis allograft. Methods of fixation where