-Comparison of MPTA on both Full-leg Standing and Rosenberg Radiographs .

The medial open wedge high tibial osteotomy (MOW-HTO) is awidely and successfully performed treatment for medial compartment osteoarthritis (OA) of the knee joint .

The primary goal of MOW-HTO is to alleviate mechanical stress onthe medial compartment of the knee joint by shifting the weight-bearing line (WBL) toward the lateral compartment .

Correct alignment is essential for achieving long-term success and favorable outcomes, making accurate preoperative planning crucial.

Accepted gold standard for preoperative coronal plane assessment of lower limb alignment are full-leg standing radiographs (FLSR) .

Measurement variables in the coronal plane include the mechanical lateral proximal femoral angle (mLPFA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle and mechanical lateral distal tibial angle.

However, alignment measurements are influenced by factors such as knee flexion, rotation, and loading conditions .

Identifying these factors prior to surgery is crucial to minimizing the risk of surgical error.

Posteroanterior weight-bearing radiographs taken with the knee in 45 degrees of flexion, commonly referred to as the Rosenberg view (RB), are routinely used preoperatively . This imaging technique not only facilitates the assessment of the severity of knee OA but also aids in evaluating the degree of soft tissue laxity contributing to varus alignment-a factor increasingly recognized for its clinical significance .

For knowledge, one study has investigated how knee alignment parameters used for planning of HTO differ when measured using the RB .

The invistegator hypothesize that the medial proximal tibial angle (MPTA) does not differ when measured on RB radiographs compared with FLSR. Being a widely accessible and commonly used imaging technique, if confirmed, this finding would suggest that the RB could serve as a com-plementary modality for preoperative planning for MOW-HTO.

Inclusion Criteria:

• All patients were screened for medial compartment OA of either the left or right knee joint.
• Availability of preoperative full-length standing radiograph and Rosenberg view.
• Completeness of patient records .
• Patient consent

Exclusion Criteria:

• Insufficient patient records .
• Previous ligamentous surgery or osteotomies .
• Known neuromuscular or metabolic disorder .
• Absence of a radiographic reference ball.

Outpatient clinics and inpatient ward of Orthopedics & Trauma Surgery Department , Asyut University Hospitals , Faculty of Medicine