This is, to our knowledge, the first study of postural asymmetries in a total population of adults with CP.
Postural asymmetries were present in adults at all GMFCS level, but more frequent at lower levels of motor function and varied in different positions. Normally a standing position requires more postural ability, and those at GMFCS level I to III demonstrated more asymmetries in standing compared to sitting and supine lying. However the reverse was seen at GMFCS level V with a higher proportion of postural asymmetries in supine and sitting compared to supported standing, indicating a lack of postural support while lying and sitting.
The time spent in different positions may have a great impact on the development of contractures and deformities. In this study no one who used standing support stood more than 1 to 2
hours per day. This implies that 22 to 24 out of the 24
hours per day were spent in a more asymmetric position in sitting or lying for those at GMFCS level V. In addition they could not change their position while lying or sitting. Of those who were unable to change position in lying half had only one lying position, indicating that they were not assisted in changing position. Porter et
showed that preferred lying postures influence the direction of deformity with windsweeping, hip dislocation, and spinal curve in children with CP unable to move out of their preferred posture. A study by Pountney et
on posture management to prevent hip dislocation supports the importance of maintaining symmetry without compromising function for those unable to change position. This highlights the need for a proper assessment of posture, and provision of postural support when needed, to prevent a sustained asymmetric posture.
Pain was reported by 63 of the 102 participants but no significant association between posture and pain was found in this study. There was less reported pain compared to previous studies of adults with CP by Jahnsen et
(82%) and Andersson and Mattsson12
(79%). It may be due to the older age of participants in their studies (mean age 34y and 36y respectively). Another reason could be that pain may be unrecognized in some of the participants in the present study, as people with severe intellectual and communication disabilities were included.
Limited hip and knee extension were highly associated with postural asymmetries. Andersson and Mattson12
reported contractures in 80% of 221 adults with CP; knee contractures were most frequent. In the present study knee contractures were also most common; 60 of the 102 adults with CP could not passively extend one or both knees to 0 degrees. Limited hip and knee extension were associated with postural asymmetries in both supine and standing positions which require extended legs.
indicate that a sustained asymmetric posture may cause progressive deformities in people with CP. This study showed an association between posture and limited ROM but did not reveal if the contractures were caused by asymmetric posture or if the limited ROM caused the postural asymmetries. However, this illustrates the importance of continuous monitoring of ROM and posture in people with CP, to allow early identification and preventive treatment to maintain ROM and symmetric posture.
Scoliosis and hip dislocations were associated with postural asymmetries in all three positions. The prevalence of hip dislocations (10/102) in this material, not included in the hip prevention program, corresponds to reports from other areas.24
Hip dislocation, windswept-deformity, and scoliosis are interrelated16
and can be reduced with a hip surveillance program. Progression of scoliosis increases with age even after skeletal maturity. Risk factors are early onset, large curve magnitude, thoracolumbar curve, total body involvement, and being confined to bed.7
Since 1995 all children in the study area born 1992 and later are included in a hip surveillance program, which have reduced the proportions of hip dislocations, windswept deformities, and scoliosis.14,16
The association between these deformities and postural asymmetries shows the value of hip surveillance programs.
A limitation of this study is the lack of radiographs of the spinal curves defined as scoliosis. Structural scoliosis are rare at GMFCS level I and flexible spinal curves of postural origin are found to be more frequently rated as scoliosis at clinical examination than at radiographs.25
Since no radiographs of the spine were available, we chose to include all spinal curves rated as mild, moderate, or severe by the local physiotherapist and individuals operated with spinal fusion. This is likely to give a higher frequency of scoliosis compared to other studies with different definitions of scoliosis.
Another limitation is the restricted number of participants when analyzing the results for each GMFCS level separately. Although the proportion of participants may seem low (63% of the 162 invited), it is compensated by the total population approach, which is a strength of the study. According to the drop-out analysis the study group is a representative part of the total population, with the CP prevalence 2.3 per 1000 at 17 to 20
years of age. Part of the study population was included in the cohort born 1990 to 1993 with CP prevalence 2.4 per 1000 at 4 to 7
years and 2.8 per 1000 at 8 to 11
years of age.17
The distribution of subtypes in the present study almost equals that of the previous studies. According to the prevalence and distribution of sex, subtypes, and GMFCS levels, the study population is likely to be representative for other areas and countries with similar development.17
This study illustrates the importance of monitoring ROM and posture from an early age, but also continuously in adults with CP, to allow early identification and preventive treatment of contractures and postural asymmetries.