Is there an association between ossification of the cartilages of the foot and collateral desmopathy of the distal interphalangeal joint or distal phalanx injury?

Reasons for performing study: Associations between degree of ossification of the cartilages of the foot and injuries to other structures of the foot have been suggested, but have not been investigated by large scale studies. Objectives: To describe the frequency of grade >3 ossification of the cartilages of the foot (possibly significant ossification, PSO), mediolateral symmetry of ossification and left‐right symmetry between feet; and to investigate associations between PSO and injury of either the collateral ligaments (CLs) of the distal interphalangeal (DIP) joint or the distal phalanx. Hypotheses: Possibly significant ossification of the cartilages of the foot is associated with CL and distal phalanx injury. Distal phalanx injury is associated with a mediolateral difference in ossification grade of ≥2. Methods: Horses were examined for lameness localised to the foot by perineural analgesia, and underwent radiographic and magnetic resonance imaging examinations. Age, breed, occupation, duration of lameness, lame(st) limb, primary cause of lameness, and presence or absence of CL injury were recorded. Dorsopalmar (dorsoplantar) radiographs were examined and ossification of the cartilages of the foot graded using a modification of a previously published scale. Results: One foot from each of 462 horses was included for analysis. There was left‐right symmetry of ossification between feet, and significant association between grades of each foot, with lateral ≥medial cartilages. Possibly significant ossification occurred in the maximally ossified cartilage in 59 (12.8%) feet. There were significant associations between PSO of the maximally ossified cartilage of the foot and injuries of both the CLs of the DIP joint and the distal phalanx. There was no association between distal phalanx injury and marked asymmetry of the ossified cartilages of the foot. Conclusions and clinical relevance: Extensively ossified cartilages of the foot are significantly associated with CL or distal phalanx injury. Markedly asymmetric ossification did not increase the likelihood of distal phalanx injury and should be considered at a prepurchase examination.     

AN INNOVATIVE TECHNIQUE FOR DISPLAYING THREE DIMENSIONAL RADIOGRAPHIC ANATOMY OF SYNOVIAL STRUCTURES IN THE EQUINE DISTAL LIMB

Radiography is the most commonly applied imaging modality in equine practice and forms an essential part of the diagnostic work-up of lame horses. Radiographic signs of musculoskeletal pathology are frequently localized at sites of soft tissue attachment, which are often not clearly visible on radiographs. Different lesions carry different prognoses and require a variety of treatments, and a good knowledge of the position of the synovial structures in the distal limb of the horse is essential for practitioners in the interpretation of radiographs. This study describes a new technique for creating three-dimensional (3D) models of the synovial structures and superimposing them onto radiographs for the purpose of teaching radiographic anatomy. A set of standard radiographs was acquired of the metacarpophalangeal and the distal interphalangeal joints of a fresh cadaver leg while the leg was positioned in a material-testing machine to mimic the weight-bearing horse. Computed tomography of the same regions was performed after injection of negative contrast medium into the joints. 3D reconstructions of the joints were created using grayscale thresholding and polynomial surface meshing in Mimics. The resulting 3D reconstructions were superimposed on top of the radiographs using Adobe^© Photoshop^© CS3 Extended, thus allowing the visualization of the joint anatomy in relation to the bone on all projections. The main advantage of this technique is that it allows synovial structures to be visualized on radiographs where they are normally indistinct, which will serve as a teaching aid for anatomy.     

Penetrating injuries of the foot

Penetrating injuries to the foot are potentially serious injuries in the horse. Diagnosis is usually straightforward and a combination of radiography (including positive contrast studies) and synoviocentesis usually is necessary to determine which structures within the foot are involved. Superficial punctures usually carry a good prognosis but involvement of deep structures such as the distal phalanx or deep digital flexor tendon and navicular bursa adversely influence this. Knowledge of wound healing in the foot and a rational approach to antimicrobial selection and surgical intervention are all necessary for successful case management.     

Ultrasonographic examination of the dorsal aspect of the distal interphalangeal joint of the horse

Ultrasonographic examination of the dorsal aspect of the distal interphalangeal joint is part of the routine examination of the foot structures. The purpose of this paper is to describe the ultrasonographic anatomy of the area, and normal transverse and longitudinal images. Clinical cases are presented to illustrate abnormal findings and lesions of the dorsal aspect of the joint. Ultrasonography can complement radiography for the diagnosis and documentation of many soft tissue and joint abnormalities such as synovitis, fluid distension, cartilaginous defects, periarticular osteophytes and bone fragments.     

Comparison of conventional and alternative arthroscopic approaches to the palmar/plantar pouch of the equine distal interphalangeal joint

Reasons for performing the study: The conventional arthroscopic approach to the palmar/plantar aspect of the distal interphalangeal joint (DIPJ) may result in the inadvertent penetration of the digital flexor tendon sheath (DFTS) and the navicular bursa (NB). This iatrogenic communication would be undesirable subsequent to arthroscopic lavage of a septic DIPJ. Hypothesis: A lateral/medial approach to the palmar/plantar aspect of the DIPJ will result in a significantly lower rate of inadvertent penetration of the DFTS and NB, whilst still providing adequate intra‐articular evaluation. Methods: The conventional palmar/plantar approach or a novel lateral/medial approach to the DIPJ was performed on cadaver fore‐ and hindlimbs (30 limbs/approach). Subsequently, India ink was injected into the dorsal pouch of the DIPJ, and the DFTS (n = 60) and NB (n = 20) were examined for the presence/absence of ink. In addition, observations of the number of attempts made to access the joint, evidence of iatrogenic intra‐articular trauma and occurrence of incomplete visualisation of the palmar/plantar pouch were recorded. Results: With the conventional approach, DFTS penetration was noted in 18/30 (60%) of the limbs, compared to 1/30 (3.3%) with the lateral/medial approach (P≤0.001). NB penetration was seen in 5/10 limbs with the palmar/plantar approach compared to 0/10 with the lateral/medial approach (P = 0.01). No significant differences were found between the approaches in the number of attempts made to access the joint, the incidence of iatrogenic intra‐articular trauma, or the occurrence of incomplete visibility of the palmar/plantar pouch. Conclusions: The novel lateral/medial approach to the DIPJ significantly decreases the risk of inadvertent penetration of the DFTS and NB. Potential relevance: The novel lateral/medial approach to the DIPJ is an effective technique to gain access to the palmar/plantar pouches, and is particularly advantageous for arthroscopic lavage of a septic DIPJ.     

RADIOGRAPHIC APPEARANCE OF THE NAVICULAR BONE AND DISTAL INTERPHALANGEAL JOINT AND THEIR RELATIONSHIP WITH OSSIFICATION OF THE COLLATERAL CARTILAGES OF THE DISTAL PHALANX IN FINNHORSE CADAVER FOREFEET

Radiographic findings in the navicular bone and distal interphalangeal joint as well as the ossification status of the collateral cartilages of the distal phalanx were evaluated in 100 Finnhorse cadaver forefeet. The most common shapes of the proximal articular margin of the navicular bone were convex and straight. Remodeling of the navicular bone was common, especially on the lateral extremity. No bony fragments were identified at the distal flexor margin even though this area appeared irregular in several feet. Several large, rounded or lollipop-shaped synovial invaginations were identified in only six feet. The thickness of the flexor cortex varied considerably, and the corticomedullary junction was uni- or bilaterally indistinct in nine feet. The shape of the sagittal ridge of the flexor cortex was commonly flat but varied. It appeared locally irregular or indistinct in 17 feet, but changes elsewhere along the flexor cortex were rare. Osteophytosis on the dorsal and palmar margins of the distal interphalangeal joint and entheseophytosis on the dorsal aspect of the middle phalanx and on the extensor process of the distal phalanx were common. "Possibly significant" ossification of the collateral cartilages (high side-bones or separate centers of ossification) was present in 36 feet; all grades of ossification in the proximal/ palmaroproximal direction as well as palmar ossification were seen. A statistically significant relationship was found between entheseophytosis on the proximal flexor margin of the navicular bone and "possibly significant" ossification. Osteophytosis on the palmarodistal margin of the middle phalanx was more common in feet with a relatively long distal phalanx, suggestive of palmar ossification. Radiographic changes in the navicular bone or in the distal interphalangeal joint did not otherwise appear to be associated with ossification of the collateral cartilages of the distal phalanx in Finnhorses.     

A review of how magnetic resonance imaging can aid in case management of common pathological conditions of the equine foot

Magnetic resonance imaging (MRI) has become a valuable tool for the diagnosis of a multitude of conditions previously grouped into the vague diagnosis of palmar heel pain based on the response to palmar digital nerve diagnostic analgesia. The use of MRI not only determines a specific pathological diagnosis of the numerous structures within the foot but also the findings of the MRI help direct treatment and rehabilitation protocols, as well as providing prognostic information. Common injuries include damage to the navicular apparatus, deep digital flexor tendon, arthropathy of the distal interphalangeal joint and desmopathy of the collateral ligaments of the distal interphalangeal joint. This article reviews common MRI abnormalities in the equine foot and how treatment can be directed by the findings. Medical and surgical treatment options, as well as shoeing and rehabilitation protocols, are also discussed in relation to MRI findings. Using MRI can help create a more individually tailored and case‐specific treatment regimen, which can, in turn, promote a more positive outcome in equine cases.     

双峰驼指关节解剖

运用大体解剖学方法对双峰驼三十个指关节进行解剖研究,发现如下特征:籽骨间韧带只连接同一指上的两枚籽骨,无连于籽骨与对侧近指节骨近端的指关节籽骨韧带,也无籽骨直韧带;第二指近指节骨与第四指的近指节骨之间无韧带连接;近指节间关节缺掌侧韧带;远指节无远籽骨,但有软骨板,还有一对背侧韧带。     

INJURY OF THE COLLATERAL LIGAMENTS OF THE DISTAL INTERPHALANGEAL JOINT DIAGNOSED BY MAGNETIC RESONANCE

We describe the clinical, imaging, and necropsy findings of two horses with severe injury of the collateral ligaments of the distal interphalangeal (DIP) joint diagnosed using magnetic resonance (MR) imaging. In MR images it was possible to examine the collateral ligaments of the DIP joint from the origin at the middle phalanx to the insertion on the distal phalanx. Both horses in this report had abnormal high signal intensity within the collateral ligaments of the DIP joint, and one horse had abnormal high signal intensity within the bone of the distal phalanx on short tau inversion recovery (STIR) and T2-weighted imaging sequences. High signal intensity on STIR and T2-weighted images represents abnormal fluid accumulation indicative of inflammation, within ligament, tendon, or bone on these imaging sequences. Abnormalities were confirmed on necropsy in both horses. Injury of the collateral ligaments of the DIP joint should be considered as a source of pain in horses with lameness localized to the foot.