_Article_  
**Postural Stability and Regulation before and after High Tibial Osteotomy and Rehabilitation**  
**[PERSON] 1, [PERSON] 1, [PERSON] 1, [PERSON] 2, [PERSON] 2, [PERSON] 3 and [PERSON] 2,*\({}^{\copyright}\)**  
* Sports Clinic Halle, Center of Joint Surgery, 06108 Halle (Saale), Germany; [EMAIL_ADDRESS] (K.B.); [EMAIL_ADDRESS] (T.B.); [EMAIL_ADDRESS] (M.P.)
* Department of Orthopaedic and Trauma Surgery, Martin-Luther-University Halle-Wittenberg, Ernst-Grube-Str. 40, 06120 Halle (Saale), Germany; [PERSON]ESS] (M.J.); [EMAIL_ADDRESS] (K.-S.D.)
* Department of Health Sciences, University of Colorado, Colorado Springs, CO 80918, USA; [EMAIL_ADDRESS]
* Correspondence: [EMAIL_ADDRESS]; Tel.: +49-345-557-1317; Fax: +49-345-557-4899 check for updates  
Received: 31 August 2020; Accepted: 15 September 2020; Published: 18 September 2020  
**Featured Application: Knee osteoarthritis (OA) is a common orthopedic problem often surgically treated using a high tibial osteotomy (HTO). Unfortunately, little is known regarding the effects of HTO on postural stability and regulation. The purpose of our study was to provide a better understanding of the underlying mechanisms of postural regulation, especially the potential change in postural subsystems following HTO.**  
**Abstract: Knee osteoarthritis (OA) is a widespread orthopedic problem and a high tibial osteotomy (HTO) is a common treatment to minimize degeneration of the affected compartment. The primary aim of this study was to evaluate the postural regulation and stability among patients who underwent HTO and rehabilitation. This prospective study included 32 patients (\(55.3\pm 5.57\) years) diagnosed with medial tibofemoral OA. Each subject completed postural regulation and stability testing (Interactive Balance System), as well as pain intensity (visual analogue scale) and quality of life questionnaires (SF-36) prior to HTO (exam 1), and at six weeks (exam 2), twelve weeks (exam 3) and six months (exam 4) post HTO. For postural comparison, all patients were matched (sex, age, height) with asymptomatic subjects. Significant time effects (exam 1 vs. exam 4) were found for weight distribution index (WDI; \(\eta_{\text{p}}^{2}=0.152\)), mediolateral weight distribution \(\eta_{\text{p}}^{2}=0.163\)) and anterior-posterior weight distribution \(\eta_{\text{p}}^{2}=0.131\)). The largest difference (exam 3: \(\eta_{\text{p}}^{2}=0.251\)) and the most significant differences to the matched sample were calculated for the stability indicator (exam 1: \(\eta_{\text{p}}^{2}=0.237\); exam 2: \(\eta_{\text{p}}^{2}=0.215\); exam 3: \(\eta_{\text{p}}^{2}=0.251\); exam 4: \(\eta_{\text{p}}^{2}=0.229\)). Pain intensity showed a significant reduction (\(\eta_{\text{p}}^{2}=0.438\)) from exam 1 (\(50.7\pm 20.0\) mm) to exam 4 (\(19.3\pm 16.0\) mm). Physical pain was the quality of life parameter with the largest improvement between exams 1 and 4 (\(\eta_{\text{p}}^{2}=0.560\)). HTO allows patients to improve their mediolateral weight distribution, whereas postural stability is consistently lower than in asymptomatic subjects. This surgery leads to marked improvements in quality of life and pain.**  
**Keywords: knee osteoarthritis; surgery; posturography; postural subsystems; pain; quality of life**