## 3 Results
Using the observed between-group effect size for the primary outcome (Cohen's d = 1.71), a two-tailed independent-samples _t_-test with \(\alpha\) = 0.05 and \(n\) = 17 participants per arm (total N = 34) yielded a non-centrality parameter of \(\delta\) = 4.99 and an achieved statistical power of 0.998 (99.8%), as computed in G*Power 3.1. When the primary outcome was analysed within each surgical category, the tactile incentiviser consistently lowered the load error relative to standard care. The largest absolute benefit was observed after total hip arthroplasty (-11.0 kg; [PERSON]'s d = 3.97), followed by femoral-shaft fracture fixation (-15.2 kg; d = 1.75) and hip hemi-arthoplasty (-12.7 kg; d = 1.46). Pelvic-fracture patients also improved (-10.1 kg), but the subgroup was too small for a reliable effect-size estimate, and only a single trimalleolar-fracture patient received the device, precluding comparison. A treatment-by-diagnosis interaction test was not significant (_p_ = 0.21), indicating that the incentiviser's efficacy did not differ meaningfully between surgery types within the limits of the pilot sample (Table 5). Secondary outcomes showed no statistically significant differences between groups. NRS scores decreased from 4.2 \(\pm\) 1.7 to 2.0 \(\pm\) 1.9 in the control group and from 4.2 \(\pm\) 2.5 to 1.6 \(\pm\) 1.4 in the intervention group (_p_ = 0.48). Similarly, 6 MWT distance improved from 45.9 \(\pm\) 74.4 m to 181.1 \(\pm\) 92.3 m in controls and from 35.4 \(\pm\) 66.1 m to 206.2 \(\pm\) 90.2 m in the intervention group (_p_ = 0.51). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Outcome** & **Treatment Mean \(\pm\) SD** & **Control Mean \(\pm\) SD** & **Mean Diff (95\% CI)** & **Cohen d** & _p-Value_ \\ \hline \(\Delta\)**loaded** & & & & & & \\
**weight T1 (kg)** & 2.02 \(\pm\) 2.98 & 14.17 \(\pm\) 8.96 & \(-\)12.15 (\(-\)17.84 to \(-\)6.46) & 2.099 & 0 \\
**NRS T1** & 1.55 \(\pm\) 1.43 & 2.09 \(\pm\) 2.12 & \(-\)0.54 (\(-\)2.00 to 0.92) & 0.318 & 0.404 \\
**6 MWT T1 (m)** & 206.19 \(\pm\) 90.16 & 183.33 \(\pm\) 102.96 & 22.86 (\(-\)52.84 to 98.57) & 0.241 & 0.525 \\ \hline \end{tabular}
\end{table} 
Table 4: Intra-group comparison. Abbreviations: NRS, Numeric Rating Scale; 6 MWT, 6—Minute Walking Test; SD, Standard Deviation; CI, Confidence Interval; T1, discharge (postoperative day 14 \(\pm\) 2); [PERSON] d, effect size. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Diagnosis** & **n\_Treat** & **Mean\_Treat** & **SD\_Treat** & **n\_Control** & **Mean\_Control** & **SD\_Control** & **Mean\_Diff** & **Cohen\_d** \\ \hline
**Femoral** & & & & & & & \\
**fracture** & & & & & & & \\
**Pelvic** & & & & & & & \\
**fracture** & & & & & & & \\
**total hip** & & & & & & & \\
**arthro-** & & & & & & & \\
**plasty** & 6 & 2.22 & 3.23 & 3 & 13.23 & 0.96 & \(-\)11.01 & 3.97 \\
**(THA)** & & & & & & & \\
**flip hemi-** & & & & & & & \\
**arthroplasty** & 2 & & & & & & \\
**Timalleolar** & & & & & & \\
**ankle** & 1 & 2.58 & & 1 & 11.7 & \(-\)9.12 & \\
**fracture** & & & & & & & \\
**Total knee** & & & & & & & \\
**arthro-** & & & & & & & \\
**plasty** & 0 & & & & & \\
**(TKA)** & & & & & & & \\ \hline \end{tabular}
\end{table} 
Table 5: Diagnosis-stratified findings. Abbreviations: n_Treat/n_Control, number of patients in treatment/control group; Mean_Treat/Mean_Control, mean \(\Delta\) loaded weight at discharge; SD_Treat/SD_Control, standard deviation; Mean_Diff, mean difference between groups; [PERSON] d, effect size.