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Scientific Articles:
Jean L. Stout, James R. Gage, Michael H. Schwartz, and Tom F. Novacheck
Distal Femoral Extension Osteotomy and Patellar Tendon Advancement to Treat Persistent Crouch Gait in Cerebral Palsy
J Bone Joint Surg Am 2008; 90: 2470-2484 [Abstract] [Full text] [PDF]
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Electronic letters published:

[Read Letter to the Editor] Dr. Novacheck and colleagues respond to Dr. Morais Filho
Tom F. Novacheck, MD, Jean L. Stout, PT, MS; Michael H. Schwartz, PhD; and James R. Gage, MD   (1 December 2008)
[Read Letter to the Editor] The use of distal femur extension osteotomy in cerebral palsy
Mauro C Morais Filho   (12 November 2008)

Dr. Novacheck and colleagues respond to Dr. Morais Filho 1 December 2008
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Tom F. Novacheck, MD,
Orthopaedic Surgeon
Gillette Children's Specialty Healthcare, University of Minnesota Dept of Orthopaedics,
Jean L. Stout, PT, MS; Michael H. Schwartz, PhD; and James R. Gage, MD

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Re: Dr. Novacheck and colleagues respond to Dr. Morais Filho

novac001{at}umn.edu Tom F. Novacheck, MD, et al.

We appreciate Dr. Morais Filho’s interest in this topic and his letter to the editor. His article(1) was published after our article was submitted, so we regret not being able to include it in our literature review. Their approach is different from ours. If full passive knee motion was not obtained with hamstring lengthening, then a femoral extension osteotomy was performed during the same surgical event. Despite this important difference, their findings were similar. Extension osteotomy without retensioning the quadriceps mechanism carries a high risk of persistence of crouch and recurrence of contracture. The similar results in these two publications lends further support to this finding. The ability of patellar advancement to create better correction of crouch and to minimize the risk of recurrence was reported by us and suggested by Morais Filho et al.

We don't routinely lengthen hamstrings as they are frequently not short in crouch gait(2,3). In addition, we believe that maintaining some tension in the hamstrings may protect the sciatic nerve from stretch injury. We have three comments about the addition of routine hamstring lengthening reported by Morais Filho et al. First, it may explain the finding of better knee extension in stance phase in their study when compared with our report. However, we are concerned that the addition of hamstring lengthening still did not correct crouch and the risk of recurrent knee contracture is not avoided. It is not clear from their article if the single variable, knee extension in stance, was associated with worsening of other gait parameters. The use of global outcomes measures like the GGI addresses this concern.

Secondly, the concern about the tendency for increased anterior pelvic tilt (reported in both studies) has led us to be cautious in performing hamstring lengthening. Only one-fifth of our patients underwent concomitant hamstring lengthening. As Dr. Morais Filho points out, we were not able to determine risk factors for increased anterior pelvic tilt. Like Dr. Morais Filho’s report, psoas lengthening does not seem to be protective. 45% of our subjects had psoas lengthening. Pelvic tilt outcomes were similar when we compared those who did with those who did not undergo psoas lengthening. Dr. Morais Filho suggests that the use of walking aids after surgery may explain this, as they had two patients who were independent ambulators before surgery who were dependent on crutches or walker postoperatively. Only 2 of our 73 patients changed from independent to dependent ambulation so it seems unlikely that this is a complete explanation. However, we agree that the use of walking aids can significantly alter gait data.

Finally, we are currently reviewing our hamstring length data before and after distal femoral extension osteotomy and patellar advancement in an effort to further refine the indications for hamstring lengthening in conjunction with these procedures.

References:

1. Morais Filho MC, Neves DL, Abreu FB, Juliano Y, Guimarăes L. Treatment of fixed knee flexion deformity and crouch gait using distal femur extension osteotomy in cerebral palsy. J Child Orthop (2008) 2:37-43.

2. Arnold AS, Liu MQ, Schwartz MH, Ounpuu S, Delp SL. The role of estimating muscle-tendon lengths and velocities of the hamstrings in the evaluation and treatment of crouch gait. Gait & Posture 2006;23:273- 281.

3. Delp SL, Arnold AS, Speers RA, Moore CA. Hamstrings and psoas lengths during normal and crouch gait: implications for muscle-tendon surgery. Journal of Orthopaedic Research. 1996;14:144–151.
The use of distal femur extension osteotomy in cerebral palsy 12 November 2008
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Mauro C Morais Filho,
Orthopedic Surgeon
AACD- Săo Paulo- Brazil

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Re: The use of distal femur extension osteotomy in cerebral palsy

mfmorais{at}terra.com.br Mauro C Morais Filho

To the Editor:

I am writing regarding the recent article published in the Journal, "Femoral Extension Osteotomy and Patellar Tendon Advancement to Treat Persistent Crouch Gait in Cerebral Palsy”(1). The topic is controversial and the paper added important information about the treatment of crouch gait in patients with cerebral palsy. In the introduction the authors stated that reports about the use of distal femur extension osteotomy in cerebral palsy are limited; however, they did not cite our article published earlier this year in the Journal of Children’s Orthopaedics (2).

In that paper, we retrospectively reviewed 12 patients with cerebral palsy (average follow-up of 28 months) who received distal femur extension osteotomy and hamstring lengthening as part of treatment for crouch gait. Our results regarding knee static deformity, hip extension in stance phase, and pelvic anteversion were very similar to the results described by Stout et al.(1)at their average follow-up of 14 months. However, our patients achieved better knee extension in stance phase when compared with the patients in Stout’s study who received only distal femur extension osteotomy. The mean knee flexion in stance phase was reduced from 43 to 22 degrees after treatment in our study; in contrast, Stout et al. reported a decrease in knee flexion from 40 to 31 degrees.

Considering the definition of crouch gait (3), our use of distal femoral extension osteotomy combined with hamstring lengthening in this population was sufficient to achieve a more normal the gait pattern. However, recurrence of knee flexion contracture occurred in 27% of our cases. We suggest that patellar tendon advancement or shortening may play a role in preventing that recurrence.

Finally, as described by Stout et al.(1), we also found a substantial postoperative increase (from 12 to 21 degrees) of pelvic anteversion in the sagittal plane in our patients, despite the fact that the majority of patients had received psoas surgical lengthening. The cause of this adverse effect was not determined in Stout’s study. We suspect that there is a relationship between this finding and the use of walking aids after surgery. In our study of 12 patients, the number of patients who required use of crutches or walkers increased from 5 to 7 postoperatively. We believe that use of these walking aids can produce a more anterior position of pelvis,

The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated.

References:

1.Jean L. Stout, James R. Gage, Michael H. Schwartz, and Tom F. Novacheck Distal Femoral Extension Osteotomy and Patellar Tendon Advancement to Treat Persistent Crouch Gait in Cerebral Palsy J Bone Joint Surg Am 2008; 90: 2470-2484

2. Morais Filho MC, Neves DL, Abreu FB, Juliano Y, Guimarăes L. Treatment of fixed knee flexion deformity and crouch gait using distal femur extension osteotomy in cerebral palsy. J Child Orthop (2008) 2:37- 43.

3. Sutherland DH, Davids JR. Common gait abnormalities of the knee in cerebral palsy. Clin Orthop (1993) 288:139-147.