Osteoarthritis is a common degenerative disorder of the articular cartilage . Risk factors include genetics, female sex, past trauma, advancing age, and obesity. The diagnosis is based on a history of joint pain worsened by movement, which can lead to disability in activities of daily living .

Diagnosis of knee osteoarthritis can be confirmed based on clinical and/or radiological features. The potential of a progressive disease can be prevented or decreased by earlier recognition and correction of associated factors. Obesity and alignment especially varus malalignment are recognized factors of a progressive disease.

High tibial osteotomy (HTO) is a widely performed procedure, and good results can be achieved with appropriate patient selection and precise surgical technique. It is reported to be an effective treatment for varus knee osteoarthritis (OA) by redistributing the load line within the knee joint . With an HTO, the surgeon aims to change the coronal alignment of the leg in order to shift the center of force passing axially through the knee from the arthritic region of the knee towards the unaffected side. The amount of alignment correction to be performed is calculated before surgery based on the extent of knee arthrosis and on the alignment of the patient's lower limbs on long-leg weight bearing radiographs .

Our study is focused on effectiveness of open wedge High tibial osteotomy on clinical and radiographic outcomes of patients with medial knee osteoarthritis.

The investigators will conduct a retrospective case-series study of at least 40 patients , who underwent medial open-wedge HTO for treatment of medial knee osteoarthritis between January 2016 and January 2019 in our Arthroscopy and Sports Injuries Unit in Orthopaedics Department of Assiut University. Inclusion criteria is Kellgren-Lawrence classification grades 1 to 3; symptomatic unicompartmental osteoarthritis

Pre-operative :

assessment of patients is done clinically using Knee society score (KSS) and visual analogue scale (VAS) (0 mm, no pain;100 mm, worst pain) and radiographic assessment according to Kellgren and Lawrence using anteroposterior (AP) and lateral x-ray views of the knee , a two-leg long standing view with or without slight flexion assessing Femoral-tibial angle (FTA) .

Intra-operative :

After anaesthesia is induced, an arthroscopic examination is performed to define the status of the menisci (excluding significant damage of the lateral compartment), cruciate ligaments, and articular cartilage. meniscal surgery (partial menisectomy/meniscal repair) is performed when necessary, then The medial open wedge high tibial osteotomy (MOWHTO) is performed.

Post-operative :

follow up after at least 1 year post-operative clinically using knee society score (KSS) , visual analogue scale (VAS),Knee Injury and Osteoarthritis Outcome Score(KOOS) , Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index scores and radiological assessment using Anteroposterior and lateral views xrays assessing union two-leg long standing view x ray with or without slight flexion assessing Femoral-tibial angle (FTA) and joint line .

Inclusion Criteria:

• Age above 30 years old.
• Patients who had MOWHTO for knee OA within the past 5 years .
• No response to non-surgical treatment (medical and physiotherapy) pre operatively for at least 3 months.
• Intact cruciate ligaments, and Collateral ligaments.

Exclusion Criteria:

• Age less than 30 years old.
• Patients who had HTO for another reasons other than knee OA.
• Combined injury to (collateral ligaments, cruciate ligament).

All patients older than 30 years old that underwent medial open wedge high tibial osteotomy due to medial osteoarthritis of the knee