Relationship between the goniometric alignment and articular cartilage damage in knee osteoarthritis.

Introduction: Osteoarthritis of the knee is common among the elderly. The alignment of the knee plays an important part in disease progression.

Objectives: The aim was to determine the relationship between goniometric measurement of malalignment and gross and histological damage to articular cartilages of osteoarthritic knees.

Methods: Anterior plane knee alignment was measured using a handheld metal goniometer in 84 patients awaiting knee replacement. Articular cartilages removed at surgery were stained and examined for macroscopic and microscopic damage which were quantified with macroscopic visual assessment score and Mankins histochemical score, respectively. The relationship between the type of knee angulation and macroscopic and microscopic damage to medial and lateral compartments was analyzed using analysis of variance (ANOVA), and the relationship between the degree of angulation and the degree of damage was determined using multiple linear regression models.

Results: Varus knees had markedly higher macroscopic damage scores in the medial than the lateralcompartment (p<0.0001), while valgus knees showed the opposite (p<0.0001). The knee angulation, together with age and BMI, predicted 54% of the macroscopic (p<0.0001) and 60% of the microscopic damage (p<0.0001) in varus knees.

Conclusions: Anterior plane goniometric knee alignment is a significant predictor of the articular cartilage damage present in an osteoarthritic knee. Goniometric measurement is a valuable tool in assessing the disease severity as it is a simple, safe and cost-effective method.