Positional plagiocephaly (PP) is a cranial deformity resulting from prolonged external pressure on the skull, leading to asymmetrical head flattening while the cranial sutures remain normally developed [1-3]. Severe plagiocephalic occipital flattening is often accompanied by ipsilateral frontal bossing, as well as an anterior displacement of the ipsilateral ear and cheek [4,5]. Key risk factors for PP include male sex, supine sleeping position, prematurity, assisted delivery, torticollis, restricted head mobility, and insufficient prone positioning ("tummy time") [6,7]. Cranial deformation is generally considered a cosmetic condition [3,8]. Although developmental delays are often reported in affected infants, current evidence suggests that cranial asymmetry serves as an indicator of underlying developmental issues rather than being the direct cause of these delays [9,10].

In light of increasing parental awareness and the growing availability of private treatment options, the management of PP has gained not only medical but also socioeconomic relevance. In recent years, the prevalence of PP has risen significantly, partly due to the "Back to Sleep" campaign promoting supine sleep positioning to prevent sudden infant death syndrome [11,12]. Consequently, there has been a notable increase in demand for treatment.

Helmet therapy (cranial orthosis) is frequently offered in private healthcare settings. In the United States, associated costs typically range from $1,000 to $4,000, with insurance coverage varying widely by provider and policy [13]. Reimbursement policies for helmet therapy in Europe are heterogeneous: in the United Kingdom, cranial orthotic treatment for PP is not funded by the National Health Service due to its classification as a cosmetic intervention [14], whereas in the Netherlands, costs are typically reimbursed when prescribed by a medical specialist [3]. This regulatory variability across healthcare systems leads to unequal access and may impose a financial burden on families, depending on national coverage policies.

This rise has led to ongoing debate regarding optimal treatment strategies. While some studies suggest that physiotherapy and repositioning are sufficient in mild to moderate cases [15,16], others highlight the advantages of helmet therapy, particularly in more severe deformities, as it may offer faster and more consistent correction [17-19].

Despite the widespread use of both approaches, a clear consensus regarding their comparative efficacy remains lacking. Some studies report similar correction outcomes between conservative and helmet therapy [3], while others suggest superior results with helmets in moderate to severe cases [20]. This study aims to provide a systematic comparison of both treatment modalities in infants with PP, focusing on correction speed, overall treatment success, and factors influencing outcome variability.

The high prevalence of PP, between 5% and 46%, has led to ongoing debate regarding the optimal treatment strategy [26-28]. This has sparked discussions regarding the necessity of intervention, with treatment strategies ranging from simple repositioning to cranial orthotic (helmet) therapy. While helmet therapy is widely used, concerns about cost, compliance, and necessity persist [13,29,30]. Furthermore, the primary focus of these treatments is often cosmetic rather than functional, raising the question of whether helmet therapy provides measurable benefits beyond aesthetic improvement [31,32]. In Germany, helmet therapy is not reimbursed by statutory health insurance. The costs must be covered by the families and typically range between 1,800 and 2,500 euros. This may influence the decision to decline helmet treatment despite clinical indication. Additionally, as the prevalence of plagiocephaly decreases significantly with age, the risk of overtreatment must be considered [33]. Despite the widespread use of both conservative and helmet therapy for PP, consensus on treatment indications remains elusive [15,17-19,21]. Our study contributes to this discussion by comparing both treatment modalities and identifying key factors influencing treatment success.

In our study, helmet therapy and conservative management effectively reduced cranial asymmetry, with no significant difference in the correction rate. The average correction rate was 0.66 CVAI per month in the helmet group and 0.64 CVAI per month in the conservative group. Similar correction rates between 0.1 and 0.2 CVAI per week were also observed by Graham et al. [34]. In this study, both methods achieved a sufficient reduction in CVAI without a significant difference between the techniques. Kim et al. [35] also confirmed similar correction rates with helmet therapy.

Nevertheless, our findings indicate a trend toward greater correction with helmet therapy compared to conservative management, both in terms of achieving the therapeutic goal — reduction to level 1 — and overall severity level reduction. Moreover, the overall reduction in severity was significantly greater with helmet therapy compared to conservative management. Although treatment duration was slightly longer in the helmet group, this difference did not reach statistical significance (P=0.100), suggesting that the observed therapeutic effect is likely attributable to the intervention. Although not statistically significant, the treatment goal was achieved more often in the helmet group (25%) than in the conservative group (11%). Given the overall low success rates in both groups, it is essential to clearly communicate the therapeutic goal and the realistic possibility of complete correction of the deformity to all families. Similarly, the rate of severity level reduction was numerically higher with helmet therapy (67%) than with conservative management (42%), but this difference also did not reach statistical significance. A possible explanation for this trend is again the slightly longer median treatment duration in the helmet group (21.9 weeks) compared to the conservative group (20.6 weeks).

Helmet therapy is generally well tolerated. Minor side effects such as sweating or skin irritation have been described and were also observed in our cohort. These effects were mild and manageable with routine care. No serious adverse events occurred.

At the same time, it is important to consider that PP tends to regress spontaneously over time, with a significant reduction in prevalence during early childhood. Therefore, the extent to which spontaneous correction contributed to the observed improvements in both groups remains unclear. Van Wijk et al. [3] demonstrated that there was no difference between the correction achieved with helmet therapy over a six-month period and the spontaneous development of cranial shape when assessed at the age of 2 years. Similarly, Akutsu et al. [36] observed that while the prevalence of cranial asymmetry decreases with growth, severe deformities tend to persist. Consequently, the study group recommends helmet therapy for the treatment of more severe cases.

However, our findings indicate that early initiation of treatment plays a crucial role in achieving favorable outcomes. In the helmet group, an earlier start of treatment was significantly correlated with a reduction in severity level, and more extended treatment duration was associated with greater CVAI correction. Similarly, in the conservative group, a more extended treatment duration correlated with a greater reduction in severity level, while an earlier treatment initiation was associated with a more substantial reduction in CVAI. Early therapy initiation following an early diagnosis—resulting in longer treatment duration and, consequently, better correction outcomes—is recommended in the literature [37,38]. Weersma et al. [39] demonstrated significantly better treatment outcomes for plagiocephaly in infants aged 4 to 6 weeks compared to older children. However, the balance between treatment duration and patient adherence should be considered, as extended treatment periods may present challenges in compliance [30].

The strengths of this study include a well-defined patient cohort and the use of objective severity grading scales to assess treatment outcomes. However, certain limitations must be acknowledged. First, the retrospective nature of the study introduces inherent biases, such as variability in treatment adherence and physician recommendations. In addition, treatment allocation was influenced not only by cranial shape at re-evaluation but also by parental preferences and financial considerations. As helmet therapy is frequently not reimbursed by statutory health insurance in Germany, some families chose to continue conservative treatment despite persistent asymmetry. This may introduce a selection bias that needs to be taken into account when interpreting the results. Second, while our sample size is comparable to similar studies, larger multicenter studies are needed to validate these findings. Due to the limited sample size, multivariate analysis was not performed. Therefore, potential confounding factors such as age at treatment initiation or duration of treatment could not be fully adjusted for. Finally, long-term follow-up data were not available, which limits our ability to assess the persistence of treatment effects over time.

Both helmet therapy and conservative management effectively reduce cranial asymmetry in infants with PP, with no significant difference in the correction rate between the 2 approaches. Early treatment initiation emerged as the most important predictor of improvement, emphasizing the need for timely intervention. Longer treatment duration was also associated with better outcomes, suggesting that sustained therapy supports greater cranial symmetry correction.

While both treatment modalities proved effective, a trend toward greater severity reduction was observed in the helmet therapy group, particularly in more severe cases. However, given the natural decline in plagiocephaly prevalence over time, the potential risk of overtreatment should be carefully considered. Future research should focus on refining treatment algorithms to optimize patient outcomes and establish individualized care strategies for infants with plagiocephaly.