Objectives: Cerebral Palsy (CP) is the most common cause of motor deficiency in children and has a significant effect on gait. Crouch gait, defined as excessive knee flexion during stance phase, has a prevalence of 72%-76% and if left untreated leads to pain and potentially loss of independent gait (O'Sullivan et al., 2010). Consequently, improving knee extension in stance phase is an integral aim of orthopaedic surgery. Understanding the natural progression of pathological gait in CP is important to provide a baseline against which intervention can be assessed. The primary aim of this systematic review was to determine the natural progression of knee flexion during gait in bilateral CP. A secondary aim was to review any relationship between clinical variables and progression of knee flexion.
Methods: The protocol for this review was registered with the PROSPERO register of systematic reviews (registration number CRD42016035766). A search was conducted using - PubMed, CINAHL, EMBASE, and Web of Science. Allowing for syntactical differences between databases, terms related to “Cerebral Palsy” AND “crouch knee” AND “gait” were searched in both titles and abstracts.
Included studies reported on participants with bilateral CP who had 3-dimensional gait analysis on at least two occasions with no surgical interventions between analyses.
Two authors independently reviewed titles and abstracts and full text studies where necessary. Quality assessment was performed using a modified version of the Downs and Black checklist apart from one included case report where the Joanna Briggs Institute critical appraisal checklist was used
Results: The search strategy yielded 1259 citations and five papers (4 retrospective cohort studies; 1 case report) comprised the final selection.
Mean time between gait analyses was 3.28 years (range 1.05 to 8 years) and the mean sample size was 15.2 participants (range 1-30).
Increased knee flexion over time was reported in four studies (14.58o - 23.64o) and only the case-study reported improved knee extension between first and last assessment (36.1o and 21.4o respectively). Due to study heterogeneity, it was not possible to combine the data but there appeared to be two distinct patterns of crouch progression - a gradual increase over time and a larger, more rapid increase.
Four studies demonstrated increased hamstring tightness over time (mean increase 5.28o; range 2.5 o - 13.3 o) with the biggest increases related to longer follow-up time rather than increase in crouch.
The increase in Body Mass Index (BMI) in three studies was negligible and within normal range (16.05-17.96).
Conclusion: Apart from the case report, the other four studies demonstrated that the natural history of crouch gait is increased knee flexion over time. Two distinct patterns are seen. These are a gradual increase in knee flexion, which may not require intervention, and a more significant, rapid deterioration, which may require orthopaedic intervention. Knee flexion in stance appears to best differentiate these two groups with values ≥ 20o of particular concern. While it is not possible to be definitive due to the small number of studies there does not appear to be a link between crouch and BMI and hamstring tightness appears to occur over time secondary to knee crouch rather than causing it.
O'SULLIVAN, R., WALSH, M., KIERNAN, D. & O'BRIEN, T. 2010. The knee kinematic pattern associated with disruption of the knee extensor mechanism in ambulant patients with diplegic cerebral palsy. Clin Anat, 23, 586-92.
