Computed tomographic arthrography, gross anatomy and histology demonstrate a communication between synovial invaginations in the proximal aspect of the third interosseous muscle and the carpometacarpal joint in horses.
Abstract: This descriptive anatomical study investigates the relationship between the third interosseous muscle, also known as the suspensory ligament, and the carpometacarpal joint in forelimbs of horses, with the hypothesis that there was a direct synovial communication between these structures as shown by computed tomographic arthrography, histology, and gross anatomy sections. Computed tomography of the carpus and metacarpal region was performed on two groups. Group 1 consisted of eight cadaver limbs undergoing computed tomographic arthrography following injection of a mixture of positive contrast medium, saline, and color-pigmented fluid solution into the middle carpal joint. Group 2 consisted of eight forelimbs assessed using plain computed tomography. The images were interpreted subjectively for contrast medium distribution and objectively by comparing Hounsfield values of the proximal suspensory ligament at 0.5 cm intervals starting at the origin and extending 3 cm distal to the proximal subchondral bone plate of the third metacarpal bone. Of the 16 limbs, two were sectioned for gross anatomy and one was documented histologically. The proximal suspensory ligament was visualized with clear margins on computed tomography images. The positive contrast medium was found within the lateral and medial lobes of the suspensory ligament in all eight (100%) limbs. Hounsfield units within the suspensory ligament following contrast injection were significantly higher than in those in the plain CT group between 0.5 and 2.5 cm distal to the proximal subchondral bone plate of the third metacarpal bone ( < 0.05). The gross anatomy sections showed color pigmentation within the suspensory ligament correlating to the contrast medium distribution evident on computed tomography images. Histology confirmed a synovial lined cavity within the suspensory ligament. The demonstration of a direct synovial communication between the internal structure of the proximal suspensory ligament and the carpometacarpal joint in horses offers further explanation for commonly encountered interactions of diagnostic local anesthesia of the carpal and subcarpal regions. When performing diagnostic or therapeutic injections into the middle carpal joint, the likely effect on the proximal suspensory ligament should be considered. Furthermore, as the proximal suspensory ligament was identified clearly on CT images, further studies are needed to elucidate the utility of CT in clinical cases with suspected soft tissue pathology in the subcarpal region.
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The research investigates the connection between a horse’s third interosseous muscle (suspensory ligament) and the carpometacarpal joint, using various methods like CT arthrography, histology, and analysis of physical anatomy. The study suggests that these structures have a synovial interaction which can have implications for diagnostic and therapeutic interventions.
Methods
The researchers used two groups of horse limbs for the study. Group 1 consisted of eight cadaver limbs subject to CT arthrography after being injected with a contrast medium, saline, and a colored fluid. This was to help visualize the suspected synovial communication.
Group 2 included eight forelimbs, examined using plain computed tomography.
The researchers interpreted the results subjectively, looking for where the contrast medium distributed. They also compared Hounsfield units (a measure of radiodensity in CT imaging) within the suspensory ligament at consistent intervals.
Two of the 16 total limbs were dissected for gross anatomical study, and one was documented histologically.
Results
On the CT images, the suspensory ligament of all limbs was clearly visualized.
The contrast medium was present in all parts of the suspensory ligament across all limbs from Group 1.
The radiodensity (Hounsfield units) within the ligament after contrast injection was significantly higher, highlighting the potential for synovial communication.
The anatomy sections showed coloration corresponding to the contrast medium’s distribution on the CT images.
Upon histologic inspection, a synovial lined cavity within the suspensory ligament was confirmed.
Implications
The study proves that there is a direct synovial interaction between the proximal suspensory ligament and the carpometacarpal joint in horses.
This finding helps explain frequent interactions seen in diagnostic local anesthesia of horse’s carpal and subcarpal regions.
When veterinary practitioners perform diagnostic or therapeutic injections into the middle carpal joint, it is important to consider the potential effect on the suspensory ligament due to this synovial communication.
The fact that the suspensory ligament was clearly identifiable on CT images presents a potential for further study into its use in diagnosing soft tissue pathologies in the subcarpal region.
Cite This Article
APA
Gerdes C, Morgan R, Terry R, Foote A, Smith R.
(2022).
Computed tomographic arthrography, gross anatomy and histology demonstrate a communication between synovial invaginations in the proximal aspect of the third interosseous muscle and the carpometacarpal joint in horses.
Front Vet Sci, 9, 958598.
https://doi.org/10.3389/fvets.2022.958598
The Royal Veterinary College, London, United Kingdom.
Terry, Rebecca
Rossdales Laboratories, Newmarket, United Kingdom.
Foote, Alastair
Rossdales Laboratories, Newmarket, United Kingdom.
Smith, Roger
The Royal Veterinary College, London, United Kingdom.
Conflict of Interest Statement
Author CG is employed by Pferdeklinik Hochmoor GmbH. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
References
This article includes 27 references
Ross MW. The carpus. In: Ross MW, Dyson SJ. editor. Diagnosis and Management of Lameness in the Horse, 2nd edn., Missouri: Saunders; (2011). p. 426-449.
Dyson SJ, Genovese RL. The Suspensory Apparatus – Proximal Suspensory Desmitis in the Forelimb. In: Ross MW, Dyson SJ. editor. Diagnosis and Management of Lameness in the Horse, 2nd edn. Missouri: Saunders; (2011). p. 738–44.
Nickel R, Schummer A, Seiferle E. Eigenmuskulatur der Schultergliedmaße des Pferdes. in Nickel R, Schummer A, Seiferle E. editor. Lehrbuch der Anatomie der Haustiere, Bewegungsapparat, 8th edn., Stuttgart, Germany: Parey Co. (2003). p. 479-492.
Dyson SJ. The metacarpal region. In: Ross MW, Dyson SJ. editor. Diagnosis and Management of Lameness in the Horse, 2nd edn. Missouri: Saunders; (2011). p. 411-426..
Denoix JM, Coudry V, Jacquet S. Ultrasonographic procedure for a complete examination of the proximal third interosseous muscle (proximal suspensory ligament) in the equine forelimbs. Equine vet Educ (2008) 20:148–53.
Bassage LH, Ross MW. Diagnostic Analgesia. In: Ross MW, Dyson SJ. editor. Diagnosis and Management of Lameness in the Horse, 2nd edn. Missouri: Saunders; (2011). p. 93-123..
Mavrides E, Holden D, Bland JM, Tekay A, Thilaganathan B. Intraobserver and interobserver variability of transabdominal Doppler velocimetry measurements of the fetal ductus venosus between 10 and 14 weeks of gestation.. Ultrasound Obstet Gynecol 2001 Apr;17(4):306-10.
Garway-Heath DF, Poinoosawmy D, Wollstein G, Viswanathan A, Kamal D, Fontana L, Hitchings RA. Inter- and intraobserver variation in the analysis of optic disc images: comparison of the Heidelberg retina tomograph and computer assisted planimetry.. Br J Ophthalmol 1999 Jun;83(6):664-9.
Berner D, Gerlach K, Brehm W, Mülling C, Schöniger S, Lempe-Troillet A. Desmopathy of the front proximal suspensory ligament in conjuction with a metacarpal cortical fracture in a horse: a multi-modality imaging study. Pferdeheilkunde (2015) 31:352–56.
Bhattaram P, Chandrasekharan U. The joint synovium: A critical determinant of articular cartilage fate in inflammatory joint diseases.. Semin Cell Dev Biol 2017 Feb;62:86-93.
Saundrs J, Schwarz T. Principles of CT Image Interpretation. In: Saundrs J, Schwarz T. editor. Veterinary Computed Tomography, UK. West Sussex: Wiley-Blackwell; (2011). p. 29-34..
Levi C, Gray JE, McCullough EC, Hattery RR. The unreliability of CT numbers as absolute values.. AJR Am J Roentgenol 1982 Sep;139(3):443-7.
Lempe RA. Vergleichende magnetresonanztomographische Untersuchung am plantaren Aspekt des Tarsus des Pferdes – sonographische und histologische Kerrelation des M. interosseous medius an der Hintergliedmaße des Pferdes. Dissertation Veterinärmedizinische Fakultät der Universität Leipzig, Chirurgische Tierklinik. Leipzig (2007)..