Radiographic analysis of the angle in the lateromedial projection of the metacarpophalangeal joint and the distal interphalangeal joint in metacarpophalangeal flexural deformities in calves

The bone alignment of the metacarpophalangeal joint (MPJ) of the distal interphalangeal joint (DIPJ) in metacarpophalangeal flexural deformity (MPFD) in calves was evaluated by radiography. This study was designed by retrospective study of radiographs. Lateral to medial radiographs of distal forelimbs were taken from 19 MPFD affected calves (35 forelimbs) and 21 normal calves (42 forelimbs). Based on the radiographs, the lateral angles of MPJ were measured from the metacarpal bone axis and proximal phalanx axis, and lateral angles of DIPJ were measured from the middle phalanx axis and distal phalanx axis. Mean lateral angle of MPJ in the normal limbs was 175.9 (95% CI 174.5 to 177.4). Mean lateral angles of MPJ in MPFD were as follows: mild: 167.1 (158.9–175.2), moderate: 165.1 (158.5–171.7) and severe: 150.6 (146–155.1). MPJ angle in MPFD limbs was narrower than that in the normal limbs (mild, moderate and severe: P=0.017, P=0.003 and P<0.001, respectively). Mean lateral angle of DIPJ in the normal limbs was 211.9 (210.7–213.2). Mean lateral angles of DIPJ in moderate: 200.6 (195.2–206.1) and severe: 204.9 (203.3–206.5) MPFD were narrower than that in the normal limbs (both P<0.001). There was no significant difference between the normal limbs and mild: 210.3 (206.9–213.7) MPFD limbs (P=0.7). The clinical severity of MPFD corresponded well with the lateral angle of MPJ. The flexion of DIPJ in moderate and severe MPFD was similar to the flexion of MPJ in MPFD. This suggested that the lateral to medial radiographs accurately reflected the MPJ flexion and the DIPJ in MPFD in calves, providing useful information for the treatment of MPFD.