Prior to study initiation a sample size calculation was performed.

The standard deviation as well as the difference of the mean values of the patient-rated wrist evaluation (PRWE) score was derived from the publication by Walenkamp et al.[11].

Considering a Wilcoxon test with non-normal data distribution, an α of 0.05%, power of 80%, a difference in means of 11 points and a standard deviation of 14, which was published by Walenkamp et al. [11], a minimum of n = 31 patients in each group was required for this study. Thus, on the basis of the sample size calculations performed, including a drop-out rate of 30%, a case number of 40 patients per group was calculated.

The study was designed according to the Consolidated Standards of Reporting Trials (CONSORT) principles [12].

The study was approved by the local regional ethical committee.

In a prospective manner, 80 patients older than 65 years who presented at our level-1 trauma centre between January 2021 and March 2022 with an isolated distal radius fracture AO classification type C1 or C2 were included in our study. Exclusion criteria were open fractures and absolute indication for surgery, pathologic fractures, refractures, patients with terminal illness, advanced dementia, pre-existing limitation of motion of the affected limb and patient preference against surgical treatment.

After confirmation through x-ray, every patient was treated by primary closed reduction under hematoma block anaesthesia and with a forearm cast. Study-specific informed consent was performed, and written patients’ consent was obtained. Patients were assigned to one of two groups (n = 40) – the surgery group and the conservative group – using permuted block randomization with blocks of 10 patients.

Pre-interventionally, the following data were collected: age, sex, dominant hand, classification of the fracture, side of injury, computed tomography (CT) assessment. Moreover, patient-rated wrist evaluation (PRWE) score and disabilities of arm, shoulder, and hand (DASH) score as well as range of motion (ROM) including dorsal extension, palmar flexion, ulnar deviation and radial deviation, and grip strength were assessed on the basis of the non-injured wrist.

The treatment of the conservative group involved further immobilization with a forearm cast for 5–6 weeks, accompanied by regular follow-up examinations including x-ray controls. After cast removal, mobilization started through occupational therapy sessions.

Patients assigned to the surgical group were treated with volar plate osteosynthesis after adequate decongestion, typically 1 week post-traumatically. A dorsal plaster splint was applied for another 2 weeks. After completed wound healing and suture removal, occupational therapy was started. Intraoperative data such as surgery date, implant, surgery duration, and complications were recorded.

Follow-up (f/u) was conducted in both groups at 6 weeks and 3, 6 and 12 months. During these assessments, patient satisfaction with wrist function was assessed using a five-item Likert scale (1 – very satisfied, 2 – satisfied, 3 – neither satisfied nor dissatisfied, 4 – dissatisfied, 5 – not satisfied at all), range of motion, grip strength and pain measured by a visual analogue scale (VAS) ranging from 0 to 10. At 3, 6 and 12 months post-interventionally, patient reported outcome measures (PROMs) including PRWE score and DASH score were evaluated. Any complications that occurred were documented.

Statistical analysis was performed using IBM SPSS Statistics 29.0 (Chicago, IL, USA). The evaluation included the planned 80 patients in the above-mentioned observation period. All demographic and pre-, intra-, and post-interventional data were considered.

Data are presented using standard methods of descriptive statistics: Metric parameters with normal distribution are presented as mean ± standard deviation (SD) and in the case of a non-normal distribution as median (interquartile range [IQR]). The primary hypothesis was tested using the unpaired t-test in the case of normal data distribution and the Mann–Whitney U test in the case of non-normal distribution. These two tests were used to compare metric variables. Ordinal parameters were investigated using the Mann–Whitney U test. Nominal parameters were compared using the chi-squared test. If the requirements of this test were not fulfilled, the Fisher’s exact test was performed.

A significance value of p < 0.05 was deemed to be statistically significant for assessing the primary hypothesis. Other p-values smaller than 0.05 indicate a statistically relevant difference between groups.