Straight sesamoidean ligament desmopathy commonly occurs with proximal interphalangeal joint osteoarthritis.

Overview

• This study investigated how often and to what extent damage to the straight sesamoidean ligament (SSLD) occurs in horses that have osteoarthritis in their proximal interphalangeal joint (PIPJ), finding a significant correlation between the severity of these two conditions.

Background

• The proximal interphalangeal joint (PIPJ) osteoarthritis (OA) is a common issue that affects horses, particularly impacting their athletic performance.
• While bone changes in PIPJ OA are well-documented through radiographic imaging, the soft tissue structures like ligaments around this joint are less frequently studied.
• There has been a hypothesis that injuries to the straight sesamoidean ligament (SSL), a key soft tissue structure supporting the pastern area (near the PIPJ), might occur alongside PIPJ OA. However, the frequency and relationship of SSL injuries with PIPJ OA had not been thoroughly explored before this study.

Objectives

• The main aim was to determine how often straight sesamoidean ligament desmopathy (SSLD), which refers to ligament damage, occurs in horses diagnosed with PIPJ OA.
• Another goal was to see if there is a relationship or correlation between the severity of the ligament damage and the severity of the joint osteoarthritis.

Methods

• This was a retrospective clinical study, meaning researchers looked back at existing medical records and imaging data.
• Selection criteria included horses diagnosed with PIPJ OA that also had diagnostic imaging of the pastern soft tissues done either by ultrasonography or magnetic resonance imaging (MRI).
• Two board-certified radiologists reviewed the imaging to assess and grade the severity of SSLD and PIPJ OA separately.
• Both SSLD and OA were graded on a scale: absent, mild, moderate, or severe.
• Statistical analysis was performed using Spearman’s rank correlation to examine the relationship between the severity of SSLD and OA, as well as any link between ligament involvement and lameness severity.

Results

• A total of 58 horses (covering 60 limbs) met all inclusion criteria for the study.
• Out of these, 28 limbs (46.7%) showed evidence of SSLD along with PIPJ OA, indicating that nearly half of the cases with joint osteoarthritis also had ligament involvement.
• There was a statistically significant positive correlation (p = 0.015, r = 0.401) between the severity of PIPJ OA and the severity of SSLD—meaning worse osteoarthritis tended to be associated with worse ligament desmopathy.
• No significant correlation was found between how lame the horse was (lameness severity) and the presence of SSLD (p = 0.37, r = 0.1757), suggesting that ligament damage may not directly correspond to how obviously lame the horse appears.

Conclusions

• The study highlights that SSLD commonly occurs in horses diagnosed with PIPJ OA and that ligament damage severity tends to increase with the severity of joint osteoarthritis.
• These results suggest that careful evaluation of the supporting soft tissues, not just the bone, should be performed in horses with PIPJ OA—especially in those showing marked radiographic changes or poor response to treatment.
• The findings might lead to improved diagnostic and therapeutic approaches by including soft tissue assessment for more comprehensive management of pastern-related lameness and poor performance.
• Limitations noted include its retrospective nature, reliance on existing medical records, and a potential selection bias since only horses with both radiographic and soft tissue imaging were included.