Scott C E Brandon1, Darryl G Thelen2, Colin R Smith3, Tom F Novacheck4, Michael H Schwartz4, Rachel L Lenhart5. 1. Department of Mechanical Engineering, University of Wisconsin-Madison, USA; School of Engineering, University of Guelph, Canada. 2. Department of Mechanical Engineering, University of Wisconsin-Madison, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, USA; Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, USA. Electronic address: dgthelen@wisc.edu. 3. Department of Mechanical Engineering, University of Wisconsin-Madison, USA. 4. Gillette Children's Specialty Healthcare, USA; Department of Orthopaedic Surgery, University of Minnesota, Twin Cities, USA. 5. Department of Mechanical Engineering, University of Wisconsin-Madison, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, USA.
Abstract
BACKGROUND: Elevated tibiofemoral and patellofemoral loading in children who exhibit crouch gait may contribute to skeletal deformities, pain, and cessation of walking ability. Surgical procedures used to treat crouch frequently correct knee extensor insufficiency by advancing the patella. However, there is little quantitative understanding of how the magnitudes of crouch and patellofemoral correction affect cartilage loading in gait. METHODS: We used a computational musculoskeletal model to simulate the gait of twenty typically developing children and fifteen cerebral palsy patients who exhibited mild, moderate, and severe crouch. For each walking posture, we assessed the influence of patella alta and baja on tibiofemoral and patellofemoral cartilage contact. RESULTS: Tibiofemoral and patellofemoral contact pressures during the stance phase of normal gait averaged 2.2 and 1.0 MPa. Crouch gait increased pressure in both the tibofemoral (2.6-4.3 MPa) and patellofemoral (1.8-3.3 MPa) joints, while also shifting tibiofemoral contact to the posterior tibial plateau. For extended-knee postures, normal patellar positions (Insall-Salvatti ratio 0.8-1.2) concentrated contact on the middle third of the patellar cartilage. However, in flexed knee postures, both normal and baja patellar positions shifted pressure toward the superior edge of the patella. Moving the patella into alta restored pressure to the middle region of the patellar cartilage as crouch increased. CONCLUSIONS: This work illustrates the potential to dramatically reduce tibiofemoral and patellofemoral cartilage loading by surgically correcting crouch gait, and highlights the interaction between patella position and knee posture in modulating the location of patellar contact during functional activities.
BACKGROUND: Elevated tibiofemoral and patellofemoral loading in children who exhibit crouch gait may contribute to skeletal deformities, pain, and cessation of walking ability. Surgical procedures used to treat crouch frequently correct knee extensor insufficiency by advancing the patella. However, there is little quantitative understanding of how the magnitudes of crouch and patellofemoral correction affect cartilage loading in gait. METHODS: We used a computational musculoskeletal model to simulate the gait of twenty typically developing children and fifteen cerebral palsypatients who exhibited mild, moderate, and severe crouch. For each walking posture, we assessed the influence of patella alta and baja on tibiofemoral and patellofemoral cartilage contact. RESULTS: Tibiofemoral and patellofemoral contact pressures during the stance phase of normal gait averaged 2.2 and 1.0 MPa. Crouch gait increased pressure in both the tibofemoral (2.6-4.3 MPa) and patellofemoral (1.8-3.3 MPa) joints, while also shifting tibiofemoral contact to the posterior tibial plateau. For extended-knee postures, normal patellar positions (Insall-Salvatti ratio 0.8-1.2) concentrated contact on the middle third of the patellar cartilage. However, in flexed knee postures, both normal and baja patellar positions shifted pressure toward the superior edge of the patella. Moving the patella into alta restored pressure to the middle region of the patellar cartilage as crouch increased. CONCLUSIONS: This work illustrates the potential to dramatically reduce tibiofemoral and patellofemoral cartilage loading by surgically correcting crouch gait, and highlights the interaction between patella position and knee posture in modulating the location of patellar contact during functional activities.
Authors: N A Segal; A M Kern; D D Anderson; J Niu; J Lynch; A Guermazi; J C Torner; T D Brown; M Nevitt Journal: Osteoarthritis Cartilage Date: 2012-06-12 Impact factor: 6.576
Authors: Rachel L Lenhart; Scott C E Brandon; Colin R Smith; Tom F Novacheck; Michael H Schwartz; Darryl G Thelen Journal: J Biomech Date: 2016-11-22 Impact factor: 2.712