## 3 Results
### Comparison with High Tibial Osteotomy  
HTO patients showed a significant increase in total WOMAC (+30.8; 95%CI 25.5-36.1; \(p\) < 0.001) and in MAC JSW (+0.32; 0.03-0.61; \(p\) = 0.034) as shown in Table 2. The WOMAC subscales showed a similar increase. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & **KJD** & **KJD\({}_{\text{HTO}}\)** & **HTO** & **CHECK** & **SF** \\  & **(_n_ = 58)** & **(_n_ = 20)** & **(_n_ = 36)** & **(_n_ = 44)** & **(_n_ = 17)** \\ \hline Age, mean (SD) & 51.4 (8.0) & 51.2 (5.8) & 49.1 (6.5) & 64.0 (4.3) & 53.8 (4.7) \\ \hline Male gender, \(n\) (\%) & 34 (59) & 15 (75) & 23 (64) & 5 (11) & 10 (59) \\ \hline BMI, mean (SD) & 28.0 (3.4) & 27.4 (3.3) & 27.0 (3.5) & 29.4 (4.6) & 29.0 (3.3) \\ \hline \multicolumn{6}{c}{Kellgren-Lawrence grade, \(n\) (\%)} \\ Grade 0 & 0 (0) & 0 (0) & 1 (3) & 2 (5) & 0 (0) \\ Grade 1 & 8 (14) & 5 (25) & 4 (11) & 18 (41) & 0 (0) \\ Grade 2 & 9 (16) & 4 (20) & 10 (28) & 16 (36) & 2 (12) \\ Grade 3 & 28 (48) & 10 (50) & 18 (50) & 8 (18) & 7 (41) \\ Grade 4 & 13 (22) & 1 (5) & 3 (8) & 0 (0) & 8 (47) \\ \hline \hline \end{tabular}  
KJD = all knee joint distraction patients with available osteophyte measurements; KJDHTO = subgroup of KJD patients who were included in the KJD vs. HTO clinical trial; HTO = high tibial osteotomy patients from the KJD vs. HTO clinical trial; CHECK = untreated knee osteoarthritis patients from the cohort hip and cohort knee trial who received a total knee arthroplasty during follow-up; SF = KJD patients from a separate clinical study who underwent synovial fluid aspirations.  
\end{table} 
Table 1: Baseline characteristics of the different patient groups. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & **KJD** & & **HTO** & & **CHECK** \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Total WOMAC, \\ mean (SD) \\ \end{tabular} } & **Baseline** & **2 Years** & _p-Value_ & **Baseline** & **2 Years** & _p-Value_ & **Baseline** & **2 Years** & _p-Value_ \\ \hline \multirow{2}{*}{
\begin{tabular}{c} JSW, mean (SD) \\ \end{tabular} } & **2.36 (15.7)** & **78.8 (19.3)** & **<0.001** & 2.44 (1.28) & 2.56 (1.37) & **0.034** & 3.18 (1.76) & 2.52 (1.72) & **<0.001** \\ \hline \hline \end{tabular}  
* WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index (scale 0–100); JSW = joint space width (mm); KJD = knee joint distraction; HTO = high tibial osteotomy; CHECK = cohort hip & cohort knee. P-values are calculated for two-year changes; bold p-values indicate statistical significance. The mean JSW of the most affected compartment is given.  
\end{table} 
Table 2: Baseline and two-year WOMAC and JSW for the KJD, HTO and CHECK patient groups. Figure 1: Change in osteophyte size in mm\({}^{2}\) before and one and two years after treatment with knee joint distraction (KJD, \(n=58\)) or high tibial osteotomy (HTO, \(n=36\)). (**A**) The total joint osteophyte area and (**B**) the osteophyte area per compartment after KJD. (**C**) Total joint osteophyte area after KJD or HTO and (**D**) osteophyte area per compartment after HTO. Mean and standard error of the mean (SEM) are shown, \({}^{*}\) indicates significant changes compared to baseline using repeated measures ANOVA (\(p<0.05\)). Figure 2: Representative radiograph of a patient before and two years after knee joint distraction treatment. Note the increase in osteophyte area over the two years as indicated by the arrows. HTO patients showed a significant osteophyte change after treatment (\(p<0.001\)), increasing from 29.6 (SD 16.5) mm\({}^{2}\) at baseline to 36.6 (17.4) mm\({}^{2}\) at two years (Figure 1C). The changes in the lateral femur (6.0 (4.6) mm\({}^{2}\) to 8.1 (5.7) mm\({}^{2}\); \(p<0.001\)) and medial tibia (8.0 (6.7) mm\({}^{2}\) to 11.0 (8.2) mm\({}^{2}\); \(p=0.006\)) were statistically significant (Figure 1D).