The Relationship of the Medial Longitudinal Arch Height With Clinical Features of Knee Osteoarthritis

The goal of this observational study is to investigate the relationships between the medial longitudinal arch (MLA) height of the foot and clinical and radiological characteristics of knee osteoarthritis in adult patients 50 aged and over. The main questions it aims to answer are:

* Is there any relationship between knee pain and disability in knee osteoarthritis and MLA height?
* Is there any relationship between the radiologic severity of knee osteoarthritis and MLA height?
* Is there any relationship between knee joint alignment in knee osteoarthritis and MLA height?

Differences in hind and midfoot structures, including the medial longitudinal arch, affect lower limb alignment and biomechanics. However, the causal relationship between knee joint problems and foot deformities is controversial. Knee osteoarthritis, a common orthopaedic condition in the elderly population, tends to distort the lower limb alignment by narrowing the tibiofemoral joint space asymmetrically. Therefore, knee varus and medial longitudinal arch deformities may change gait biomechanics on knee osteoarthritis. However, there is insufficient evidence on the relationship between variation in foot posture and disease severity, knee varus deformity, knee pain and disability in knee osteoarthritis. In this study, investigators will examine the lower extremity alignment and osteoarthritis severity in terms of MLA height in adults with knee osteoarthritis.

The study sample will be formed by the simple random sampling method from adult patients with knee osteoarthritis who will be admitted to our clinics and outpatient clinics with knee pain. It was planned to include 93 participants to be able to detect the two-way correlation between the knee WOMAC score and the arch height index with an effect size of 0.3, a power of 90%, and a 5% margin of error.

Initially, demographic data, including age, gender, body mass index (BMI), limb dominance, and time from knee pain onset of participants, will be recorded. For both knees goniometric measurement of knee passive range of motion (ROM), visual analogue scale (VAS) for pain and Western Ontario and McMaster Universities Arthritis Index (WOMAC) will be applied. Kellgren/Lawrence stages, mechanical, and anatomical tibiofemoral angles for knee joints will be obtained from lower limb length X-ray. MLA height index measurement will be performed by an investigator blinded to the patient's clinical condition. According to the results of descriptive statistics, the relationship between MLA height measurement results (arch height index and arch height flexibility) and Kellgren-Lawrence stage, VAS, WOMAC and tibiofemoral angles will be examined by correlation analysis. In case of significant correlation, regression analyses for Kellgren-Lawrence, VAS and WOMAC scores as dependent variables will be applied.

Eligibility Criteria:
Inclusion Criteria:

* Being 50 years old or older
* Having a diagnosis of knee osteoarthritis according to the American College of Rheumatology

Exclusion Criteria:

* History of fracture or orthopaedic surgery involving lower limbs
* Presence of neurological condition resulting in lower limb sensorimotor deficit
* Having another inflammatory rheumatological disease
* Having a malignant tumour with bone metastasis
* Having lower limb oedema, lymphedema, skin and soft tissue loss that will prevent the evaluation of foot morphology (arch height index)
* Severe neuropsychiatric disease or condition that interferes with communication
* Having therapeutic injection into the knee joint in the last 3 months
* Presence of any major trauma that aggravated knee pain in the last 6 weeks