# Are Electromyography Data a Fingerprint for Patients with Cerebral Palsy (CP)?
## 2 Materials and Methods
### Participants  
The data analyzed in this retrospective study were part of a larger database established at the local University Hospital in the years 2000-2022 when retrieval was stopped. Only personnel who had regular legal access to the medical records retrieved patient data, collected it, and anonymized it. After this step, individual participants could no longer be identified. They retrieved patient data from the records on 15 November, 1 December, and 13 December 2022, and anonymized it in the same year on 28 December.  
The database was filtered for patients with CP with at least two consecutive examinations in the local gait laboratory with orthopedic surgery in between. Examinations that did not show high-quality EMG data were excluded, and surgeries had to address gait disorders caused by CP. If multiple examinations were available, the dates closest to the surgery were selected. The first examination (E1) was conducted before the operation,and the second examination (E2) was typically conducted one year after the operation. Therefore, E1 and E2 pertain to the same individuals evaluated at different time points. For patients with hemiplegia, only data from the affected side were considered.  
Further primary inclusion criteria encompassed gait and clinical data for each examination, walking barefoot without assistive devices, and classification as Gross Motor Function Classification System (GMFCS) level I or II. Usually, the surgeries involved multiple procedures on different levels (hip, thigh, shank, and feet). If multiple surgeries were performed on different dates between the two examinations, all procedures were included in this study as they could be relevant for the second examination. Following the recommendation of [PERSON] et al. [5], to ensure a more homogeneous approach to surgical treatment, we focused on patients who, among other procedures, underwent soft tissue surgery on muscles located at the shank and foot level. For 91% of patients, this involved at least one surgery on the triceps surae muscle, such as the Baumann Procedure [22] (46%), Strayer Procedure [23] (46%), or Achilles Tendon Lengthening [24] (17%). Additionally, there were some muscle transfer surgeries, such as tibialis anterior transfer (13%) and tibialis posterior transfer (9%), and multiple muscle lengthening procedures, such as flexor digitorum longus lengthening (3%). In most cases, the surgery included further procedures on another level, i.e., legs and feet. The most prevalent additional procedures were femoral derotation (78%), bony foot procedures (38%), rectus transfer (30%), and hamstring lengthening (28%).  
Furthermore, according to [5], we chose to assess only the more involved side in each patient to maintain homogeneity regarding severity. This was defined as the side that underwent surgery, and in cases of bilateral involvement, the side with the lower GDI was selected for further analysis. Following the application of these criteria, 167 patients were recruited, along with 117 TD individuals serving as the reference group. Table 1 presents the characteristics of this study's participants.