Effect of the upper instrumented vertebral level (upper vs. lower thoracic spine) on gait ability after corrective surgery for adult spinal deformity

Publication date: Available online 29 June 2017
Source:The Spine Journal
Author(s): Mitsuru Yagi, Nobuyuki Fujita, Osahiko Tsuji, Narihiro Nagoshi, Yoshiyuki Yato, Takashi Asazuma, Ken Ishii, Masaya Nakamura, Morio Matsumoto, Kota Watanabe
Background ContextThe relationship between gait pattern and the level of upper instrumented vertebra (UIV) in surgically treated patients with adult spinal deformity (ASD) has not been fully documented.PurposeTo assess the effect of UIV level for the gait pattern in ASDStudy Design/SettingProspective case series.Patient SampleThirty surgically treated consecutive female ASD with lumbosacral fusion (age 67.0±8.4 years; body mass index (BMI) 22.7±2.4 kg/m²; Cobb angle 49.9±21.3°; CVA 1.5±3.6 cm; C7SVA 9.3±5.3 cm; PI-LL 35.4±25.8°; and lean volume of the lower leg 5.5±0.9 kg) were categorized into UT group or TL group based on the level of UIV (UT; UIV T2-T5, LT; UIV T9-T11) and the gait pattern were compared before and after corrective spine surgery.Outcome MeasuresSRS22, ODI, and forceplate analysisMethodsAll subjects underwent gait analysis on a custom-built force plate using optical markers placed on all joints and spinal processes. In addition to the gait ability, shoulder and lower extremity joints kinetics and head vertical deviation were analyzed. DXA scores were used to calculate the lean composition of the lower legs. Subjects were followed for at least 2 years post-op.ResultsUT group had larger baseline Cobb angle, whereas LT group had larger C7SVA (UT vs TL; Cobb angle: 59.2±22.9 vs 44.6±17.4deg, p=0.03, C7SVA: 10.9±8.7 vs 12.0±7.1cm, p=0.03). Preoperatively, no difference was found in gait velocity and stride between UT and LT group, whereas the right and left difference of step length was significantly large in UT group (velocity: 55.0±12.5 vs 53.6±9.0 m/min, stride: 99.7±13.0 vs 97.8±13.6cm, step length; 10.4±4.9 vs 5.6±3.3%). Coronal and sagittal alignments were significantly improved in both groups (total; Cobb angle: 19.4±10.6deg, C7SVA: 5.3±2.9cm, PI-LL: 12.1±5.1deg). Gait pattern, stride, and velocity all improved significantly after surgery (total; velocity:62.3±8.9m/min, stride:106.8±12.3cm, p=0.01). The knee angle at the heel contact phase and hip ROM were also significantly improved at post-op (total; hip ROM: pre-op:29.2±9.1deg, post-op:36.2±4.8deg, knee angle; pre-op:10.6±6.6deg, post-op:4.4±2.8deg). No difference was observed for the pelvis and shoulder rotation on the horizontal plane at post-op in both groups (total; pelvis rotation; pre-op:7.4±3.4deg, post-op:7.9±2.4deg, shoulder rotation; pre-op:7.4±2.9deg, post-op:8.7±3.6deg). The head vertical deviation was also not changed post-operatively in both groups (pre-op:3.1±0.9cm, post-op:3.1±0.8cm).ConclusionsBoth UT and LT groups achieved similar improvement of gait ability and pattern after surgery. Additional studies will be needed to further define the effect of UIV for the activity of daily living such as fast walking, stepping the stairs or standing from the chair in ASDs.



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