Table 1.
Definition of measurements
| Measurement | Abbreviation | Definition |
|---|---|---|
| Maximum length of the femur | MLF | Distance between the plane tangent to the lowest points of the medial and lateral condyles of the femur (referred to as plane α) and the plane parallel to plane α that is tangent to the upper end of the femur |
| Valuation angle | VA | Angle formed by the MA and the line segment connecting the center of the femoral diaphysis and the ICN when the femur is observed from the ventral side |
| Lordosis angle | LA | Angle formed by the MA and the line segment connecting the center of femoral diaphysis and the ICN when the femur is observed from the lateral side |
| Lateral anterior–posterior length | LAP | Distance between the two lines when lines parallel to the SEA are drawn to pass through the anterior and posterior ends of the lateral epicondyle when the femur is observed from the bottom side |
| Medial anterior–posterior length | MAP | Distance between the two lines when lines parallel to the SEA are drawn to pass through the anterior and posterior ends of the medial epicondyle when the femur is observed from the bottom side |
| Partial lateral anterior–posterior length | P-LAP | Distance between the two lines when lines parallel to the SEA is drawn to pass through the rearmost end of the lateral condyle and the posterior end of the intercondylar fossa when the femur is observed from the bottom side |
| Partial medial anterior–posterior length | P-MAP | Distance between the two lines when lines parallel to the SEA is drawn to pass through the rearmost end of the medial condyle and the posterior end of the intercondylar fossa when the femur is observed from the bottom side |
| Lateral distal resection amount | LRA | Distance between two lines when straight lines parallel to SEA are drawn through the lower end of the lateral condyle and the ICN when observed facing the plane created by SEA and MA (referred to as plane β) |
| Medial distal resection amount | MRA | Distance between two lines when straight lines parallel to SEA are drawn through the lower end of the medial condyle and the ICN when observed facing plane β |
| Cross-section partial lateral anterior–posterior length | C-P-LAP | Distance on CS A′ (which is a cross section that is orthogonal to plane β and approximates a horizontal section at a height that passes through the ICN) between the SEA and the straight line parallel to the SEA drawn so as to pass through the posterior end of the lateral condyle |
| Cross-section partial medial anterior–posterior length | C-P-MAP | Distance on CS A′ between the SEA and the straight line parallel to the SEA drawn so as to pass through the posterior end of the medial condyle |
| Posterior condyle axis angle | PCA-angle | Angle formed by the SEA and a straight line passing through the posterior ends of the medial and lateral condyles when the femur is observed from the bottom |
| Cross-section lateral-middle length | C-LML | Distance between the two lines when straight lines perpendicular to the SEA are drawn so as to pass through the lateral end of CS A′ and the ICN |
| Cross-section medial-middle length | C-MML | Distance between the two lines when straight lines perpendicular to the SEA are drawn so as to pass through the medial end of CS A′ and the ICN |
| Cross-section medial–lateral width | C-ML | Distance between the two lines when straight lines perpendicular to the SEA are drawn so as to pass through the medial end of CS A′ and the lateral end of CS A′ |
| Lateral distal anterior angle | LDA-angle | Angle formed on CS A′ by the straight line orthogonal to the SEA and line passing through points A and B, which are the intersections of a straight line parallel to the SEA through ICN and the SEA with the outermost side of CS A′ |
| Medial distal anterior angle | MDA-angle | Angle formed on CS A′ by the straight line orthogonal to the SEA and the line passing through points C and D, which are the intersections of a straight line parallel to the SEA through the ICN and the SEA with the innermost side of CS A′ |
| Medial distal radius of the curvature | MDAC | Radiation of the curvature of point C on CS A′ |
| Joint line angle | JL-angle | Angle formed by the line parallel to the SEA passing through the ICN and the straight line passing through the lower end of the lateral condyle and that of the medial condyle when the femur is observed from the ventral side |
| Medial superior-inferior length | MSI | Length from the top to the bottom of CS B′, which is a cross section formed on the medial condyle that is perpendicular to CS A′ and passes through the lateral and medial posterior ends of CS A′ |
| Lateral superior-inferior length | LSI | Length from top to bottom of CS C′, which is a cross section formed on the lateral condyle so as to be perpendicular to CS A′ and passes through the lateral and medial posterior ends of CS A′ |
| Medial condyle width | MCW | Length from the medial end to the lateral end of CS B′ |
| Lateral condyle width | LCW | Length from the medial end to the lateral end of CS C′ |
| Medial condyle to middle width | MCMW | Distance between two lines when the lines perpendicular to CS A′ are drawn so as to pass through the ICN and the medial end of CS B′ when observed so as to face CS B′ |
| Lateral condyle to middle width | LCMW | Distance between two lines when lines perpendicular to CS A′ are drawn so as to pass through the ICN and the lateral end of CS C′ when observed so as to face CS C′ |
| Middle-lateral outer angle | MLO-angle | Angle between the straight line that passes through the lateral end of CS C′ at the height of CS A′ and the lateral end of CS C′ at the height of the lateral epicondyle and the straight line perpendicular to CS A′ when observed so as to face CS C′ |
| Front protrusion length | FPL | Distance between two lines when two straight lines parallel to the MA are drawn so as to pass through the point perpendicular to CS D′, which is formed with a cross section that is parallel to SEA and perpendicular to CS A′, which passes through the anterior end of the intercondylar fossa surface of CS A′, from the ICN and the upper end of CS D |
| Coronal-section outer angle | CSO-angle | Angle formed by the straight line parallel to the MA and the straight-line EF, where point E is the lateral end of CS D′ and point F is the point where the curvature of the outer edge of CS D′ changes from convex to concave |
| Radiation of the curvature of the lateral anterior excision contour | RLAC | Radius of curvature at the midpoint between point F and the upper end of CS D′ |
| Lateral anterior excision contour width | LAEC | Distance between two lines when straight lines parallel to the MA are drawn on CS D′ so as to pass through point E and the ICN |
| Medial anterior excision contour width | MAEC | Distance between two lines when straight lines parallel to the MA are drawn on CS D′ so as to pass through the medial end of CS D′ and the ICN |
| Anterior excision middle-lateral length | AEML | Length of the line segment perpendicular to CS D′ from the front end of the lateral condyle |
| Anterior excision middle-medial length | AEMM | Length of the line segment perpendicular to CS D′ from the front end of the medial condyle |
| Patella coronal-section length | PCS | Length of the line segment connecting the point perpendicular to CS D′ from the point at the rear end of the margin connecting the front end of the medial condyle and that of the lateral condyle |
| Radiation of curvature of the lateral distal condyle | RLDC | Radius of curvature at the point where the straight line connecting the center of the femoral head and the lateral epicondyle intersects the base of the lateral epicondyle when the femur is observed from the lateral side |
| Radiation of curvature of the lateral posterior condyle | RLPC | Radius of curvature at the midpoint of side GH, where point G, which is orthogonal to CS A′, is the intersection of the edge of the shadow of the lateral condyle projected so as to be perpendicular to plane γ (which is the plane in contact with the lateral epicondyle and orthogonal to CS A′) and CS A′; point H is the intersection of a straight line from point G that is orthogonal to CS A′ and the upper edge of the shadow |
| Radiation of curvature of the medial distal condyle | RMDC | Radius of curvature at the point where the straight line connecting the center of the femoral head and the medial epicondyle intersects the base of the medial epicondyle when the femur is observed from the medial side |
| Radiation of curvature of the medial posterior condyle | RMPC | Radius of curvature at the midpoint of side IJ, where point I, which is orthogonal to CS A′, is the intersection of the edge of the shadow of the lateral condyle projected so as to be perpendicular to plane δ (which is the plane in contact with the lateral epicondyle and orthogonal to CS A′) and CS A′; point J is the upper edge of the shadow |
| Epicondyle axis angle | CEA-angle | Angle formed by a straight line connecting the lateral and medial epicondyles and a straight line passing through the posterior ends of the medial and lateral epicondyles |
| C-lateral anterior–posterior length | C-LAP | Distance between two lines when lines parallel to the SEA are drawn on the anterior and posterior ends of the lateral condyle on CS A′ |
| C-medial anterior–posterior length | C-MAP | Distance between two lines when lines parallel to SEA are drawn on the anterior and posterior ends of the medial condyle on CS A′ |
ICN intercondylar notch, which is located at the posterior 1/4 point on the midline of the recess between the medial and lateral condyles on the bottom surface of the lower end of the femur, MA mechanical axis, which is the axis passing through the center of the femoral head and ICN [29], SEA surgical epicondyle axis, which is the axis passing through the medial epicondyle process groove and the lateral epicondyle process [29, 70, 71]