## 3 Results
### Heel Strike  
The comparison between the hip angles of the treated side to the nontreated side showed that a preoperative tendency in the sagittal and transversal plane was balanced up to the last follow-up. In detail, the mean values in the sagittal/transversal planes of the treated leg tended, preoperatively, to be inferior compared to the untreated side, and approximated over the time. However, the results showed no statistical significance (\(p>\) 0.05). The values of the treated and nontreated sides in the frontal plane were nearly constant over time (\(p>\) 0.05). In spite of a preoperative trend to an inferior mean flexion, abduction and internal rotation in the presence of a cam deformity compared to patients without a FAI type CAM, the results showed no statistical significance (\(p>\) 0.05) (Table 2). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Mean \(\pm\) SD** & \(-\)**cam (n = 22)** & \(+\)**cam (n = 33)** & **95\% CI** \\ \hline Age & 59.5 \(\pm\) 8.2 & 56.7 \(\pm\) 8.5 & \(-\)1.8; 7.4 \\ BMI & 28.3 \(\pm\) 6.1 & 26.6 \(\pm\) 3.1 & \(-\)1.2; 4.5 \\ Gender (\(\mathcal{G}\)/\(\mathcal{G}\)) & 10/12 & 21/12 & \(-\)0.05 \\ Approach (Lat./Ant.-lat.) & 8/14 & 19/14 & \(>\)0.05 \\ Offset preop. & 44.9 \(\pm\) 10.1 & 47.7 \(\pm\) 6.4 & \(-\)7.2; 1.8 \\ Offset 12M FU & 52.6 \(\pm\) 7.8 & 54.0 \(\pm\) 7.5 & \(-\)5.7; 2.8 \\ difference offset & 7.7 \(\pm\) 6.6 & 6.2 \(\pm\) 6.5 & \(-\)2.1; 5.1 \\ CCD preop. & 131.8 \(\pm\) 9.7 & 130.7 \(\pm\) 5.2 & \(-\)1.0; 7.2 \\ CCD 12M FU & 130.9 \(\pm\) 5.9 & 130.8 \(\pm\) 4.6 & \(-\)2.8; 2.9 \\ Difference CCD & \(-\)0.9 \(\pm\) 6.9 & 0.09 \(\pm\) 5.7 & \(-\)5.5; 1.6 \\ HHS preop. & 51.7 \(\pm\) 11.9 & 53.7 \(\pm\) 11.4 & \(-\)8.4; 4.4 \\ HHS 12M FU & 95.7 \(\pm\) 7.0 & 94.6 \(\pm\) 9.9 & \(-\)3.9; 6.1 \\ Difference HHS & 43.6 \(\pm\) 13.9 & 42.9 \(\pm\) 15.8 & \(-\)7.8; 9.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Demographic data, approach data, hip morphology and clinical outcomes between both groups, \(+\)cam and \(-\)cam. Lat. = standard lateral hip approach, ant.-lat. = minimal-invasive antero-lateral hip approach. Both groups were comparable in terms of age, BMI, gender and approach (\(p>\) 0.05). The \(+\)cam group showed a tendency towards younger patient age (2.8 years) and lower BMI (1.7). Comparison between the baseline values and the 12-month results in all planes showed a greater increase in the +cam group for the frontal plane, with statistical significance (\(p=0.011\), Cohen's d = \(-0.73\), post-hoc power = 0.72) (Figure 2). \begin{table}
\begin{tabular}{c c c c c} \hline
**Heel Strike** & \(-\)**cam** & \(+\)**cam** & **Difference \(-\)/+cam** & **95\% CI** \\ \hline Hip sag. preop. & \(32.9\pm 6.2\) & \(30.5\pm 5.7\) & \(2.4\) & \(-0.89\pm 5.7\) \\ Hip sag. 12 M FU & \(34.6\pm 7.8\) & \(33.5\pm 6.2\) & \(1.1\) & \(-3.0\pm 5.0\) \\ difference preop. \(-12\) M & \(1.7\pm 10.7\) & \(3.1\pm 7.9\) & \(1.4\) & \(-6.4\pm 3.7\) \\ Hip front. preop. & \(1.7\pm 3.0\) & \(0.01\pm 4.2\) & \(1.69\) & \(-0.42\pm 3.8\) \\ Hip front. 12 M FU & \(-1.1\pm 3.1\) & \(-0.05\pm 3.6\) & \(1.05\) & \(-3.0\pm 0.8\) \\ difference preop. \(-12\) M & \(-2.8\pm 4.1\) & \(-0.06\pm 3.6\) & \(2.74\) & \(-4.9\pm 0.66\) \\ Hip trans. preop. & \(-12.1\pm 16.2\) & \(-10.8\pm 11.7\) & \(1.3\) & \(-8.8\pm 6.2\) \\ Hip trans. 12 M FU & \(-18.1\pm 17.0\) & \(-15.8\pm 11.5\) & \(2.3\) & \(-9.9\pm 5.4\) \\ difference preop. \(-12\) M & \(-5.9\pm 22.2\) & \(-5.0\pm 10.6\) & \(0.9\) & \(-9.9\pm 8.0\) \\ \hline \end{tabular}
\end{table} 
Table 2: Mean values and standard deviation at the heel strike of the treated hip before and 12 months after surgery dependent on a cam shaped femoral neck junction. The difference in the frontal plane was statistically significant with a lower reduction to the adduction after treatment in patients with an FAI type cam. The mean differences between the hip angles in presence of a cam deformity and absence ranged between 0.9–2.7\({}^{\circ}\). Figure 2: _Cont_.