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Study Design: A new rod-plate anterior implant was designed to provide plate fixation at the cephalad and caudal-end segments of a 5-level anterior spine construct. Biomechanical testing was performed on calf spines instrumented with 5-segment anterior scoliosis constructs. OBJECTIVES.: To analyze the initial and post-fatigue biomechanical performance of the new implant, and compare it to an anterior dual-rod construct and a single-rod construct with interbody cages., Summary of Background Data: Using single-rod anterior instrumentation for thoracolumbar and lumbar scoliosis, an unacceptable incidence of loss of correction, segmental kyphosis, and pseudarthrosis has been reported. Inadequate construct stiffness due to early postoperative bone-screw interface failure, especially at cephalad and caudal-end vertebrae, has been implicated as the cause of these complications., Methods: Thirty calf spines were instrumented over 5 segments with: (1) single-rod augmented with rod-plate implants, (2) dual-rod construct, and (3) single-rod with titanium mesh cages. Stiffness in flexion-extension and lateral bending modes was determined initially and post-cyclical loading by measuring segmental range of motion (ROM). Post-fatigue screw pullout tests were also performed., Results: In lateral bending, the caudal-end segmental ROM for rod-plate construct was 54% less than single-rod with cages construct (P < 0.05), with no difference between rod-plate and dual-rod constructs. In flexion-extension, the rod-plate construct showed 45% to 91% (initial test) and 84% to 90% (post-fatigue) less ROM than the single-rod with cages construct (P < 0.001). Again, there was no difference between rod-plate and dual-rod constructs at the cephalad and caudal-end segments. Post-fatigue screw pullout strengths of the rod-plate construct were significantly greater than those of the dual-rod and single-rod with cages constructs (P < 0.05)., Conclusions: The rod-plate construct was significantly stiffer and provided greater stability of bone-screw interface than the single-rod with cages construct. It achieved similar stiffness and improved bone-screw interface stability compared to dual-rod construct.

VICON Clinical Manager software is widely used for gait analysis and has four methods for computing ankle plantarflexion-dorsiflexion motion and transverse plane ankle rotation profiles. The authors evaluated 14 subjects with a diagnosis of spastic cerebral palsy and tibial torsion ranging from 39 degrees internal torsion to 90 degrees external torsion, using the four different processing methods. It was found that clinically measured tibial torsion >20 degrees external or >15 degrees internal led to significant differences in the calculated ankle plantarflexion-dorsiflexion and transverse plane ankle rotation measurements between the four methods. Pearson correlations indicated that these differences increased with increasing external or internal tibial torsion. The variability was enough to affect conclusions of published articles and clinical decision making.

Twelve patients with healed congenital pseudarthrosis of the tibia underwent gait analysis and muscle strength testing to determine the functional result of treatment. Six children younger than 4 years of age presented with pseudarthroses (early onset), and six children first fractured at older than 4 years of age (delayed onset). Four children with amputations as final treatment for congenital pseudarthrosis were studied for comparison. The early-onset group had undergone an average of 4.2 surgeries and all required transankle fixation. The delayed-onset group had undergone an average of 1.5 surgeries, with one child requiring fixation across the ankle. Lack of ankle push-off and foot drop occurred in the early-onset group. Terminal stance phase ankle power generation was greatly diminished in the early-onset group. Total mechanical work performed by the affected limb, when compared to the uninvolved contralateral limb, was symmetric in delayed-onset patients and reduced by 68% in early-onset patients and by 85% in amputees. Gastrocsoleus strength was reduced by 40%. Gait and muscle strength of patients with "healed" congenital pseudarthrosis of the tibia are markedly disturbed. Early onset of disease, early surgery, and transankle fixation lead to an inefficient gait comparable to that of amputees.