Distal interphalangeal joint capsule enthesopathy of the middle phalanx and articular cartilage loss

Significant distal interphalangeal joint (DIPJ) pathology, particularly
affecting soft tissue and articular cartilage, is often not identifiable
on radiographs but can be accompanied by joint capsule enthesopathy on the
middle phalanx (P2) that can be readily identified. We retrospectively
examined the frequency and correlations between DIPJ capsule enthesopathy
identified on MRI and radiographs and DIPJ articular cartilage
abnormalities and other concurrent soft tissue or osseous pathology within
the foot found on high-field magnetic resonance imaging (MRI).
Abnormalities were graded using a 4-point scale. Descriptive statistics
and Spearman’s rank correlations were used to analyze the relationship
between the presence and grade of DIPJ capsule enthesopathy, lameness, and
DIPJ intra-articular and collateral ligament abnormalities seen on MRI. We
identified DIPJ articular cartilage lesions in the majority of horses with
DIPJ capsule enthesopathy (20/21 limbs, 95%). However, no significant
correlation between the degree of DIPJ capsule enthesopathy and severity
of articular cartilage lesions was identified. DIPJ proliferative
synovitis and osteophytes were present in most cases (91% and 95%,
respectively). DIPJ collateral ligaments were abnormal in 52% of the
limbs. Additionally, DIPJ collateral ligament abnormality grade was
moderately positively correlated with DIPJ capsule enthesopathy severity
(r=0.53, p= 0.01). In summary, our findings support that the presence of
DIPJ capsule enthesopathy on radiographs is frequently seen with articular
cartilage loss.