Equine subchondral lucencies: Knowledge from the medial femoral condyle

Abstract

Equine subchondral lucencies (SCL) have been described since the first availability of suitable radiographic equipment. The initial clinical sign can be lameness, but SCLs are often first found on surveys of juvenile horses and are primarily a radiographic concern for public auctions. When lameness is present, it varies from subtle to obvious and can be intermittent. Some SCLs heal spontaneously, and some remain blemishes, but when the SCL and lameness are persistent, further damage to the joint and limitations to an athletic career are likely. SCLs were initially described in the distal limb followed by the stifle, and the medial femoral condyle (MFC) is now considered the most common location. The aim of this review is to highlight the initial pathology and discuss the clinical and experimental information available on equine SCLs. SCL treatment has evolved from rest alone and has progressed to debridement, grafting, intralesional injection, and most recently, transcondylar screw and absorbable implant placement. Comparison of success rates between techniques is difficult due to variations in follow‐up and outcome measures, and no single technique is best for all SCLs. Treatment appears to increase success by 15%–20% over rest alone, but the method chosen depends on many factors. This review emphasizes the need for further work to fully understand SCL formation and all aspects of trabecular bone healing to optimize surgical therapy and improve treatment success.

Treatment Comparison for Medial Femoral Condyle Subchondral Cystic Lesions and Prognosis in Yearling Thoroughbred Racehorse Prospects

“…Treatments for SCL have been extensively studied [10]. Current treatments for medial femoral condyle SCL include rest, intra-articular or SCL intralesional injection with corticosteroids, plasma-derived products or stem cells, arthroscopic or external debridement with or without filling of the defect with cancellous bone grafts, cartilage grafts, mosaic arthroplasty, and stainless-steel screws or composite absorbable transcondylar implants [4,9,[11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

“…SCL show marked variation in size and shape, which can change over time radiographically [1,25]. They are usually surrounded by mild to marked subchondral bone sclerosis, and complete radiographic resolution after treatment is rare and not always correlated with soundness or racing prognosis [1,9,10].…”