Is there a role for lateral hamstring lengthening in the era of ‘guided growth’?

Although our focus was on how the introduction of guided growth has changed decision-making and management of flexed knee gait in ambulant children and teenagers with cerebral palsy (CP), this of necessity included some discussion on soft tissue surgery. We apologise if our discussion of lateral hamstring lengthening (LHL) was incomplete or ambiguous.

In flexed knee gait, we think that evidence for or against the addition of LHL to medial hamstring lengthening (MHL) is incomplete and unconvincing because the relevant literature is of limited quality. In most published series, in which subgroup comparisons are made, the indications for MHL were not the same as for combined MHL and LHL. Most surgeons added LHL when knee flexion in gait was greater and crucially, when there was a greater degree of fixed flexion deformity at the knee (FFDKn). We are not aware of any high-level evidence from prospective comparison studies, in which groups were either randomised or well-matched at baseline.

In 2002, Kay et al. published data suggesting modest improvements in some knee outcomes by the addition of LHL to MHL, but the groups had baseline differences, and there was increased knee recurvatum in the LHL group. ¹ Twenty years later, Dr. Kay was the lead author on the consensus article for hamstring surgery in ambulatory children with CP using the Delphi method. ² It is this study that contains both Dr. Kay’s current views and the consensus views of the expert panel. The views can be summarised as follows: the panel supporting MHL if the hamstrings are demonstrably short and slow, and that the indications for combined medial and LHL are very limited for children functioning at Gross Motor Function Classification System (GMFCS) I–III. The reasons for this are that better options have been developed for the management of FFDKn than reliance on soft tissue surgery on its own. These options include anterior distal femoral hemi-epiphysiodesis (aka ‘guided growth’) for small FFDKn in children with 2 years or more growth remaining and distal femoral extension osteotomy for larger flexion deformities in skeletally mature individuals. The need to identify children with small FFDKn before skeletal maturity and before the onset of ‘peak height velocity’ is the rationale for promoting the concept of knee surveillance. To summarise, if there is an FFDKn sufficient to consider adding LHL to MHL, in the majority of cases, guided growth may be a safer and more effective option.

We agree with the author that every possible step should be taken to avoid nerve stretch injuries after soft tissue surgery for FFDKn. For this reason, we referred to ‘slowly and safely improve hamstring length’ (p. 10, line 297). The reference to long leg sitting is for knee extension but hip flexion is limited in the initial stages with children sitting in a reclined position with hip flexion in sitting gradually increased. This is particularly important in sitting up in bed and early mobilisation postoperatively. The importance of slow knee extension after soft tissue surgery is expanded in our references 40 and 49. ³

Word limits did not allow a detailed discussion regarding all the factors that may impact dynamic knee extension in stance, such as increased anterior trunk tilt in midstance, limited hip extension, excessive ankle dorsiflexion or the impact of transverse plane alignment. Our emphasis in this article is the early identification of FFDKn, a detailed evaluation of the causative factors leading to FFDKn, and an emphasis on early minimally invasive intervention to reduce the need for subsequent more invasive surgical procedures. Our article and, in particular, the conclusion section espouse a multilevel surgical approach. ³ We use knee surveillance to trigger a referral to the Motion Analysis Laboratory for a full three-dimensional gait analysis and comprehensive biomechanical assessment. From this, an individualised management plan is formulated to correct knee pathology as well as musculoskeletal pathology at the hip, foot and ankle levels in a multilevel surgery approach.

Supplemental Material

sj-pdf-1-cho-10.1177_18632521251396649 – Supplemental material for Is there a role for lateral hamstring lengthening in the era of ‘guided growth’?

Supplemental material, sj-pdf-1-cho-10.1177_18632521251396649 for Is there a role for lateral hamstring lengthening in the era of ‘guided growth’? by Kerr Graham, Pam Thomason, Ken Ye, Annette O’Donnell, Vedant Kulkarni, Jon R Davids and Erich Rutz in Journal of Children's Orthopaedics