John J Elias1, Miho J Tanaka2, Kerwyn C Jones3, Andrew J Cosgarea4. 1. Department of Research, Cleveland Clinic Akron General, 1 Akron General Ave, Akron, OH 44307, United States. Electronic address: eliasj@ccf.org. 2. Department of Orthopaedic Surgery, Johns Hopkins University, 10803 Falls Road, Suite 2100, Lutherville, MD 21093, United States. Electronic address: mtanaka5@mgh.harvard.edu. 3. Department of Orthopedic Surgery, Akron Children's Hospital, 1 Perkins Square, Akron, OH 44308, United States. Electronic address: kjones@akronchildrens.org. 4. Department of Orthopaedic Surgery, Johns Hopkins University, 10803 Falls Road, Suite 2100, Lutherville, MD 21093, United States. Electronic address: acosgar@jhmi.edu.
Abstract
BACKGROUND: Medial patellofemoral ligament reconstruction and tibial tuberosity anteromedialization are common treatment options for recurrent lateral patellar instability, although ligament reconstruction is not commonly applied to knees with lateral malalignment. METHODS: Multibody dynamic simulation was used to assess knee function following tibial tuberosity anteromedialization and medial patellofemoral ligament reconstruction for knees with lateral malalignment. Dual limb squatting was simulated with six models representing knees being treated for patellar instability with an elevated tibial tuberosity to trochlear groove distance. The patellar tendon attachment on the tibia was shifted medially (10 mm) and anteriorly (5 mm) to represent tibial tuberosity anteromedialization. A hamstrings tendon graft was represented for medial patellofemoral ligament reconstruction. Patellar tracking was quantified based on bisect offset index. The patellofemoral contact pressure distribution was quantified using discrete element analysis. Data were analyzed with repeated measures comparisons with post-hoc tests. FINDINGS: Both procedures significantly reduced bisect offset index, primarily at low flexion angles. The decrease was larger for tibial tuberosity anteromedialization, peaking at 0.18. Tibial tuberosity anteromedialization shifted contact pressures medially, significantly increasing the maximum medial contact pressure at multiple flexion angles, with the maximum pressure increasing up to 1 MPa. INTERPRETATION: The results indicate tibial tuberosity anteromedialization decreases lateral patellar maltracking more effectively than medial patellofemoral ligament reconstruction, but shifts contact pressure medially. Tibial tuberosity anteromedialization is likely to reduce the risk of post-operative instability compared to medial patellofemoral ligament reconstruction. The medial shift in the pressure distribution should be considered for knees with medial cartilage lesions, however.
BACKGROUND: Medial patellofemoral ligament reconstruction and tibial tuberosity anteromedialization are common treatment options for recurrent lateral patellar instability, although ligament reconstruction is not commonly applied to knees with lateral malalignment. METHODS: Multibody dynamic simulation was used to assess knee function following tibial tuberosity anteromedialization and medial patellofemoral ligament reconstruction for knees with lateral malalignment. Dual limb squatting was simulated with six models representing knees being treated for patellar instability with an elevated tibial tuberosity to trochlear groove distance. The patellar tendon attachment on the tibia was shifted medially (10 mm) and anteriorly (5 mm) to represent tibial tuberosity anteromedialization. A hamstrings tendon graft was represented for medial patellofemoral ligament reconstruction. Patellar tracking was quantified based on bisect offset index. The patellofemoral contact pressure distribution was quantified using discrete element analysis. Data were analyzed with repeated measures comparisons with post-hoc tests. FINDINGS: Both procedures significantly reduced bisect offset index, primarily at low flexion angles. The decrease was larger for tibial tuberosity anteromedialization, peaking at 0.18. Tibial tuberosity anteromedialization shifted contact pressures medially, significantly increasing the maximum medial contact pressure at multiple flexion angles, with the maximum pressure increasing up to 1 MPa. INTERPRETATION: The results indicate tibial tuberosity anteromedialization decreases lateral patellar maltracking more effectively than medial patellofemoral ligament reconstruction, but shifts contact pressure medially. Tibial tuberosity anteromedialization is likely to reduce the risk of post-operative instability compared to medial patellofemoral ligament reconstruction. The medial shift in the pressure distribution should be considered for knees with medial cartilage lesions, however.
Authors: Archana Saranathan; Marcus S Kirkpatrick; Saandeep Mani; Laura G Smith; Andrew J Cosgarea; Juay Seng Tan; John J Elias Journal: Knee Surg Sports Traumatol Arthrosc Date: 2011-12-02 Impact factor: 4.342
Authors: Alexander E Weber; Amit Nathani; Joshua S Dines; Answorth A Allen; Beth E Shubin-Stein; Elizabeth A Arendt; Asheesh Bedi Journal: J Bone Joint Surg Am Date: 2016-03-02 Impact factor: 5.284
Authors: Joseph N Liu; Michael E Steinhaus; Irene L Kalbian; William R Post; Daniel W Green; Sabrina M Strickland; Beth E Shubin Stein Journal: Am J Sports Med Date: 2017-10-06 Impact factor: 6.202