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O79: Tibialis anterior muscle in swing phase of gait before and after tendon shortening with simultaneous Achilles tendon lengthening in patients with hemiplegic cerebral palsy
Gait & Posture xxx (xxxx) xxx–xxx
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
O79
Tibialis anterior muscle in swing phase of gait before and after tendon shortening with simultaneous Achilles tendon lengthening in patients with hemiplegic cerebral palsy Reinald Brunnera,b,⁎, Erich Rutza,b, Christian Wyssa,b a b
University Children's Hospital Basel, Basel, Switzerland Basel University, Basel, Switzerland
1. Introduction In severe equinus deformity due to spastic hemiplegic cerebral palsy we described a surgical correction by simultaneously lengthening the Achilles tendon (ATL) and shortening of the tendon of the tibialis anterior muscle (TAS). The results are clinically satisfying proven by gait analysis [1] and remain so even at the long term [2]. 2. Research question Is tibialis anterior activity more normal with a powerful dorsiflexion especially during swing after ATL and TAS? 3. Methods All patients from the first cohort study (n = 12) were included and their data anonymised. Patients with too poor data were excluded (10 patients remained). The data before and at the time for the long-term follow-up study were considered. The gait data were imported in a slightly changed Lower Leg extremity Model of AnyBody Technology software. The mean of five trials for every patient was compared pre- to postoperative and to normal data (which was equally handled, n=10). Not overlapping standard deviation was considered significant.
Fig. 1. Shift of kinematic curve in swing postop. To dorsiflexion but premature plantarflexion remains.
4. Results Ankle joint dorsiflexion increases postoperatively by about 15 degrees. The shape of the curve in swing phase remains similar compared to preoperative with a drop in the second half of swing. This indicates a shift of this part of the curve only. Musculoskeletal modelling shows no change of tibialis anterior force pre- to postoperatively but an increase of the muscle moment almost to normal values during swing.
⁎
Corresponding author.
http://dx.doi.org/10.1016/j.gaitpost.2017.06.332
0966-6362/ © 2017 Published by Elsevier B.V.
Fig. 2. Muscle force of the tibialis anterior remains unchanged postop.
Gait & Posture xxx (xxxx) xxx–xxx
R. Brunner et al.
remains unchanged. This is shown by the unchanged foot dropping in swing and the missing change of force production of this muscle. Our hypothesis thus is rejected. However, the moment of the tibialis anterior in swing gets almost normal due to the improved foot position (change of lever arm and direction of action). We conclude that tibialis anterior tendon shortening does not improve the function of the muscle also the patients show good active dorsiflexion in clinical exam. In spite of the lack of improved active (dynamic) function, however, there is a static tenodesis function with the same force as preoperatively. This tenodesis nevertheless is sufficient to improve the foot position in swing phase. Weakness of the tibialis anterior due to tendon overlength is not the only reason for the dropfoot in hemiplegic cerebral palsy.
Fig. 3. Muscle moment of the tibialis anterior reaches normal values postop.
References Figs. 1–3: Stance phase covered by grey area (not of interest), black = normal, red = preop., blue = postop.
[1] E. Rutz, R. Baker, O. Tirosh, J. Romkes, C. Haase, R. Brunner, Tibialis anterior tendon shortening in combination with Achilles tendon lengthening in spastic equinus in cerebral palsy, Gait Posture 33 (2) (2011) 152–157. [2] M. Kläusler, O. Tirosh, B. Speth, R. Brunner, E. Rutz, Long-term follow-up after Tibialis Anterior Tendon Shortening in combination with Achilles Tendon Lengthening in spastic equinus in cerebral palsy, Gait Posture 49S (2016) 5.
5. Discussion In spite of a clinical improvement of gait due to the increased dorsiflexion postoperatively the function of the tibialis anterior muscle
2
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
O79
Tibialis anterior muscle in swing phase of gait before and after tendon shortening with simultaneous Achilles tendon lengthening in patients with hemiplegic cerebral palsy Reinald Brunnera,b,⁎, Erich Rutza,b, Christian Wyssa,b a b
University Children's Hospital Basel, Basel, Switzerland Basel University, Basel, Switzerland
1. Introduction In severe equinus deformity due to spastic hemiplegic cerebral palsy we described a surgical correction by simultaneously lengthening the Achilles tendon (ATL) and shortening of the tendon of the tibialis anterior muscle (TAS). The results are clinically satisfying proven by gait analysis [1] and remain so even at the long term [2]. 2. Research question Is tibialis anterior activity more normal with a powerful dorsiflexion especially during swing after ATL and TAS? 3. Methods All patients from the first cohort study (n = 12) were included and their data anonymised. Patients with too poor data were excluded (10 patients remained). The data before and at the time for the long-term follow-up study were considered. The gait data were imported in a slightly changed Lower Leg extremity Model of AnyBody Technology software. The mean of five trials for every patient was compared pre- to postoperative and to normal data (which was equally handled, n=10). Not overlapping standard deviation was considered significant.
Fig. 1. Shift of kinematic curve in swing postop. To dorsiflexion but premature plantarflexion remains.
4. Results Ankle joint dorsiflexion increases postoperatively by about 15 degrees. The shape of the curve in swing phase remains similar compared to preoperative with a drop in the second half of swing. This indicates a shift of this part of the curve only. Musculoskeletal modelling shows no change of tibialis anterior force pre- to postoperatively but an increase of the muscle moment almost to normal values during swing.
⁎
Corresponding author.
http://dx.doi.org/10.1016/j.gaitpost.2017.06.332
0966-6362/ © 2017 Published by Elsevier B.V.
Fig. 2. Muscle force of the tibialis anterior remains unchanged postop.
Gait & Posture xxx (xxxx) xxx–xxx
R. Brunner et al.
remains unchanged. This is shown by the unchanged foot dropping in swing and the missing change of force production of this muscle. Our hypothesis thus is rejected. However, the moment of the tibialis anterior in swing gets almost normal due to the improved foot position (change of lever arm and direction of action). We conclude that tibialis anterior tendon shortening does not improve the function of the muscle also the patients show good active dorsiflexion in clinical exam. In spite of the lack of improved active (dynamic) function, however, there is a static tenodesis function with the same force as preoperatively. This tenodesis nevertheless is sufficient to improve the foot position in swing phase. Weakness of the tibialis anterior due to tendon overlength is not the only reason for the dropfoot in hemiplegic cerebral palsy.
Fig. 3. Muscle moment of the tibialis anterior reaches normal values postop.
References Figs. 1–3: Stance phase covered by grey area (not of interest), black = normal, red = preop., blue = postop.
[1] E. Rutz, R. Baker, O. Tirosh, J. Romkes, C. Haase, R. Brunner, Tibialis anterior tendon shortening in combination with Achilles tendon lengthening in spastic equinus in cerebral palsy, Gait Posture 33 (2) (2011) 152–157. [2] M. Kläusler, O. Tirosh, B. Speth, R. Brunner, E. Rutz, Long-term follow-up after Tibialis Anterior Tendon Shortening in combination with Achilles Tendon Lengthening in spastic equinus in cerebral palsy, Gait Posture 49S (2016) 5.
5. Discussion In spite of a clinical improvement of gait due to the increased dorsiflexion postoperatively the function of the tibialis anterior muscle
2