Carpal Sheath Research Articles

Arthroscopic removal of palmar intermediate carpal bone fracture fragments in four horses using a transthecal approach through the carpal flexor tendon sheath

ObjectiveTo describe the removal of palmar intermediate carpal bone (ICB) fracture fragments using a transthecal approach through the carpal flexor tendon sheath.Study designCase series.AnimalsFour horses with fractures of the palmar aspect of the ICB.MethodsTwo horses were injured when falling and two during recovery from general anesthesia. Three horses underwent MRI to supplement conventional imaging. Three horses had concurrent fractures of the radial and/or accessory carpal bones. Conventional proximolateral carpal sheath arthroscope and instrument portals were used, supplemented with a medial instrument portal through the carpal flexor retinaculum to access the palmar carpal ligament. Optimized dissection through the latter was facilitated by needle guidance and radiography. The fragment was dissected from the soft tissue attachments and the palmar ICB fragments retrieved through the carpal sheath in all horses. Surgery time was 85 to 142 min.ResultsLimitations of this technique include a long surgery time and the potential for hemorrhage to impair visibility during surgery. All four horses were discharged 3 to 8 days postoperatively. Three horses returned to full athletic work within 9 months postoperatively and one horse was euthanized due to persistent lameness.ConclusionA tenoscopic transthecal carpal flexor tendon sheath approach provides access for removal of palmar ICB fracture fragments but should be viewed as an advanced arthroscopic procedure.Clinical significanceA transthecal approach through the carpal flexor tendon sheath offers an alternative technique for removal of palmar ICB fracture fragments.

Accessory carpal bone fracture repair by means of computer‐assisted orthopaedic surgery in a Warmblood stallion

SummaryA 10‐year‐old, 595 kg Irish Warmblood stallion used for showjumping was presented with a marked right forelimb lameness at walk. The horse sustained a dorsal plane fracture of the accessory carpal bone (ACB) when falling with both carpi in flexion. The fracture was repaired by means of computer‐assisted orthopaedic surgery (CAOS) using two cortex screws placed in lag fashion. In a second CAOS procedure, a dorsoproximal fragment of the ACB was removed after further proximal displacement had become apparent. Both surgical procedures were facilitated by the application of a fibreglass cast to immobilise the carpus in extension and to allow for the placement of the patient tracker distant from the surgical site. One year after surgery, the horse had returned to full athletic activity. Neither the antebrachiocarpal joint nor the carpal sheath were distended. Control radiographs and standing cone beam computed tomography showed complete osseous union of the fracture and osteophyte formation on the caudal aspect of the radius and the proximal border of the ACB.

Intratendinous Fibroma of the Superficial Digital Flexor Tendon within the Carpal Sheath of a Horse

A 20-year-old British Warmblood gelding was presented for a progressively worsening right forelimb lameness which developed following an intense dressage training session. Initial ultrasound examination revealed a triangular, intrathecal, hypoechoic region within the superficial digital flexor tendon (SDFT) in the proximal, palmar carpal region distal to the accessory carpal bone (ACB), extending 7cm distally into the proximal metacarpal region. No significant improvement in clinical presentation was observed following an eight-week rehabilitation programme. Repeat ultrasound examination revealed an enlarged cross-sectional area of affected tendon. Due to a poor clinical response to conservative treatment, combined with increasingly marked severity of the lameness, the horse was humanely euthanised and the affected SDFT was submitted for macroscopic and histopathological examination at the University of Liverpool. This revealed an approximately 70mm-elongated, focally extensive mass located within the SDFT. On cross-section, the mass was poorly delineated, irregularly triangular, focally haemorrhagic, firm, 15 × 12mm wide and eccentrically placed towards the palmar aspect of the tendon. Histopathological examination identified a moderately to highly cellular, infiltrative, poorly demarcated mesenchymal neoplasm comprised of streams of moderately atypical spindloid cells including bizarre mitoses. Intratendinous fibroma is an uncommonly recorded human neoplasm and this case represents the third reported case of this entity in the horse, the first in an adult horse and the first to be identified in the SDFT.

Desensitisation of the distal forelimb following intrathecal anaesthesia of the carpal sheath in horses.

The effect of intrathecal anaesthesia of the carpal sheath on distal forelimb sensitivity in horses remains unknown. To assess the effect of carpal sheath anaesthesia on skin sensitivity of the distal forelimb and to determine potential locations for desensitisation of palmar nerves. In vivo experimental and descriptive anatomical studies. Mepivacaine hydrochloride 2% (0.6mg/kg) was injected unilaterally in the carpal sheath of 8 horses. Mechanical nociception of the distal forelimb was measured with a dynamometer and compared with the control limb at t0, t15, t30, t60, t90, t120 and t180minutes . Additionally, the carpal sheath of 10 pairs of cadaveric limbs was injected with latex and potential locations for anaesthetic diffusion to the neighbouring nerves were identified during longitudinal dissection (one limb) and in 3-cm-thick transverse cuts (opposite limb). Six of 8 horses (75%) were completely desensitised at the level of both heel bulbs. Anaesthetic injection was not smooth in the 2 horses without desensitisation. Desensitisation started between 30 and 60minutes in 67% of desensitised heel bulbs (8/12), and 50% (6/12) of them were still completely desensitised at 180minutes. Cadaveric specimens revealed close proximity between the sheath and the medial palmar nerve as it travels inside the mesotenon of the digital flexor tendons in the carpal region and with both palmar nerves at the proximal metacarpal region. Skin mechanical nociception does not necessarily correlate with deep pain but remains the main clinical tool used by practitioners to assess distal limb anaesthesia. Intrathecal anaesthesia of the carpal sheath led to distal limb skin desensitisation through diffusion to the palmar nerves at 2 possible locations. Carpal sheath anaesthesia should be interpreted within 15minutes following injection and anaesthetic blocks distal to the carpus should be delayed for more than 3hours following carpal sheath anaesthesia.

Ultrasound findings in tendons and ligaments of lame sport horses competing or training in South Florida venues during the winter seasons of 2007 through 2016

SummaryKnowledge of common soft tissue lesions in sport horses in training should prove beneficial for evaluating lameness and developing training and management regimens to avoid injury and aid rehabilitation. Medical records were reviewed from 2007 to 2016 to describe tendon/ligament lesions in lame sport horses training and competing at the same venues during the winter show circuit and identified by lameness and ultrasonographic examinations. Season, discipline, breed, age, gender, limb and ultrasound findings were recorded. Descriptive statistics were used to describe the population of horses. Significance of association of gender, discipline and limb with lesion type was evaluated using chi‐squared analyses. Values were considered significant at P ≤ 0.05. Lesions were identified in 296 horses: 176 dressage and 120 hunter/jumpers. Ninety‐two horses (31%) had multiple lesions. Suspensory ligament lesion locations (n = 281) were categorised as proximal (n = 144), body (n = 22) and branches (n = 115). Superficial digital flexor tendon (SDFT; n = 37), deep digital flexor tendon (DDFT; n = 27), inferior check ligament (ICL; n = 34), digital flexor tendon sheath (n = 17), distal sesamoidean ligament (n = 10), lower limb collateral ligament (n = 14), carpal sheath (n = 2), superior check ligament (n = 2) and tarsal sheath (n = 1) lesions were noted. Remaining lesions identified were medial branch SDFT (n = 2), lateral branch SDFT (n = 2), palmar annular ligament (n = 3), lateral plantar ligament (n = 2) and inter‐sesamoidean ligament (n = 1). Rear limb proximal suspensory abnormalities, specifically the right hindlimb (n = 68), were significantly over‐represented (P = 0.03). Suspensory origin, suspensory branch, ICL, SDFT and DDFT accounted for 82% of the abnormal findings identified. SDFT, DDFT and ICL lesions were most often identified in the front limb. The lesion type and location may provide insight in assessing training regimens, patient monitoring and rehabilitation guidelines.

Diagnostic tenoscopy of the carpal sheath with a needle arthroscope in standing sedated horses.

To investigate the use of a needle arthroscope for diagnostic tenoscopy of the carpal sheath in standing horses. Experimental study. Six forelimbs for the cadaveric part of the study and six horses for the in vivo part of the study. Six cadaveric limbs were used to perform carpal sheath tenoscopy with a 1.2-mm-diameter needle arthroscope (65 and 100 mm long), followed by tenoscopy with a 4-mm arthroscope through a standard proximolateral approach. Then, unilateral standing carpal sheath tenoscopy was performed in six healthy sedated horses with a 65-mm-long needle arthroscope. Limbs were maintained in flexion during the procedure by using a custom-made splint and base. Degree of tenoscopic evaluation, safety, horse tolerance, and complications were recorded. Visibility at the most distal aspect of the sheath was absent for the needle arthroscopes vs a standard arthroscope. The maneuverability with a 65-mm needle arthroscope was excellent and allowed exhaustive visualization of the proximal region of the carpal sheath in cadaveric limbs and standing horses (six of six). However, visualization of the intertendinous recess was partial in most horses (four of six) vs cadavers (complete in six of six) because of remaining flexor tendon tension in standing horses. No major complications were encountered. Standing carpal sheath tenoscopy allowed a safe and thorough evaluation of most structures in the proximal region of the sheath and offers an alternative diagnostic technique. Horses with unrewarding results after traditional imaging or that require an accurate diagnosis before treatment may benefit from this alternative procedure.

The influence of tenoscopic approaches on radiocarpal joint perforation during carpal sheath tenoscopy in horses.

To report the frequency of radiocarpal joint (RCJ) perforation during two proximolateral carpal sheath (CS) approaches and to investigate whether the presence or absence of a natural communication between the RCJ and CS. Experimental, randomized, controlled study. Twelve adult horses and 12 cadaver front limbs. Proximolateral CS tenoscopy was performed on both carpi of 12 horses under general anaesthesia. Limbs were randomly assigned into two groups. In group 1, the instrument portal was centered at the level of the distal radial physeal remnant (PR). In group 2, the instrument portal was centered 2 cm proximal to the PR. Immediately after tenoscopy, dye-coloured fluid was instilled arthroscopically into the dorsolateral RCJ, and the open tenoscopic portals were evaluated for leakage. Twelve cadaver front limbs were examined for naturally occuring RCJ and CS communication by using positive-contrast computed tomography (CT). Frequency of perforations were compared with McNemar's test for two matched proportions. In group 1, 10 of 12 RCJ were perforated during tenoscopy, and, in group 2, four of 12 RCJ were perforated (P = 0.03). No diffusion of contrast from the RCJ to the CS was detected by CT. Perforation of the RCJ was common when CS instrument portals were placed at the level of the PR. No natural communication was detected between the RCJ and CS. Carpal sheath tenoscopic instrument portals may need to be placed >2 cm proximal to the PR to prevent inadvertent RCJ perforation, especially in horses undergoing tenoscopic treatment of a septic CS.

Rice body formation without rheumatic disease or tuberculosis infection in a sausage ring finger – a case report

Subcutaneous masses in the finger gather numerous lesions, among which tumors, inflammation-induced lesions, and post-traumatic lesions. Rice bodies are very unfrequent lesions, encountered in rheumatoid or tuberculous chronic synovitis. We present the case of a young patient with no history of tuberculosis infection or rheumatoid pathology who required surgical treatment for a rice body formation localized on the palmar side of the fourth left finger. A 31-year old, right dominant hand man presented with a 15 years history of progressively growing “sausage-like swelling” of the finger. There was an inamovible, painless mass with restriction of the DIP and PIP joints range of motion, without skin lesion, redness or stiffness. Imaging showed a large non-agressive mass within the tendon sheath. We realized a complete excision of the mass. Histopathological examination showed synovial villus with body rice shape and central necrosis evoking tuberculous synovitis or reumatoid arthritis. However, there was no argument for mycobacterial infection nor rheumatoid pathology. Rice bodies mostly evoke chronic synovitis or arthritis in northern countries, but may also be found in infectious diseases such as mycobacterial infections, related to chronic bursitis. No physiopathological mechanism has been formally identified (microinfarctions after intra-articular synovial inflammation and ischemia + de novo formation and progressive enlargement by fibrin + alteration in fluid viscosity and fibrinogen content of the synovial fluid). Different locations of rice bodies have been documented such as shoulder, knee, extensor tendon in the hand, wrist and carpal tunnel and flexor tendon sheath, but at the knowledge of the authors, this is the first reported case of digit flexor sheath rice body formation not related to inflammatory disease such as mycobacteria infection or rheumatoid arthritis. Differential diagnosis include synovial chondromatosis, pigmented villonodular synovitis, gout, sarcoidosis, systemic lupus erythematosus, chronic fungal infection and atypical mycobacterial infection, but the absence of suggestive complications, negative bacterial and fungal cultures, and laboratory test results, allowed us to assume the absence of classic etiology. In a case like ours, even less described than tuberculosis or arthritis, there is no established treatment standard. Despite the absence of associated systemic therapy, radical excision of the mass should provide definitive treatment. Therefore, prolonged observation will be necessary to confirm absence of recurrence with radical excision. Rice body formation should be better known as a muskulosqueletal form of mycobacterial infection or rheumatoid affection either by radiologists, surgeons and pathologists to provide optimal care for patients.

Didatic approach of ultrasonographic examination for evaluation of the carpal joint in horses

ABSTRACT: The carpus is a complex articulation, which is often involved in injuries in equine athletes. The objective of this study was to suggest a didactic approach for ultrasonography training for the examination of the carpal joint in horses. Ultrasonograhy examination was performed in a healthy 14-year-old horse. The images were compared with those of a dissected anatomic specimen of the carpal region of a senior horse and with those reported in the literature. Identifiable structures were as follows: (dorsal) tendon of the muscle extensor carpi radialis, tendon of the muscle extensor carpi obliquus, tendon of the muscle commom digital extensor, dorsal synovial outpouchings, joint capsule and fat cushion, (lateral) tendon of the muscle lateral digital extensor, lateral collateral ligament (deep and superficial components), (medial) medial collateral ligament (deep and superficial components) and (palmar) palmar intercarpal ligament, carpal sheath, carpal tunnel, superficial digital flexor tendon, proximal origin of the deep digital flexor tendon, and palmar carpal ligament. Prior knowledge of the anatomy in combination with the study of anatomical specimens is essential for recognizing musculoskeletal structures during ultrasound examination, contributing to the training and learning processes.

Radial Osteochondroma in a Chilean Pure Breed Rodeo Horse: First Case Reported in this Breed

A 5 year-old Chilean pure breed rodeo gelding was evaluated for lameness in the right forelimb and effusion of the common carpal sheath of the digital flexor tendons. Radiographs revealed exostosis with rounded margins arising from the palmar cortex of the distal metaphysis of the radius. Ultrasonographic examination revealed a thickened and proliferative synovium, excessive anechoic fluid and a hiperechogenic mass protruding from the cortical bone. Tenoscopic exploration confirmed the presence of the mass, and removal was successfully performed through thecotomy. At 4 months postoperatively, the horsed was successfully competing although present mild right forelimb lameness and improving.

Post operative synovial sepsis following endoscopic surgery: Increased risk associated with the carpal sheath.

The overall rate of sepsis following endoscopic surgery of synovial structures has not previously been documented. Clinical observation has led to the conjecture that tendon sheaths, in particular the carpal flexor tendon sheath, are more prone to post operative synovial sepsis than other synovial structures. To document and investigate the rate of post operative synovial sepsis following elective endoscopic surgery. Retrospective case series. The medical records of horses that underwent arthroscopy, tenoscopy or bursoscopy at Donnington Grove Veterinary Surgery between January 1999 and July 2012 were reviewed. The signalment, anatomical structure involved, use of electrosurgery, tourniquet or motorised resector, presence of a fracture, whether surgery was performed with the horse standing or under general anaesthesia and the number of structures examined were recorded. Multivariable logistic regression was used to test the association between the selected variables and synovial sepsis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. Level of significance was P<0.05. There were 1670 horses that underwent endoscopic surgery of 3159 synovial structures: 2517 joints, 583 tendon sheaths and 59 bursae. There were 16 cases of post operative sepsis in 16 horses; therefore, the infection rate was one per 100 horses or 5 per 1000 procedures. Carpal sheath tenoscopy was associated with an OR of developing post operative synovial sepsis of 14.9 (95% CI 4.8-45.9, P<0.001) compared to other synovial structures. Tendon sheath endoscopy had an OR of developing post operative synovial sepsis of 5.21 (95% CI 1.24-21.91, P<0.02) compared to other synovial structures. Surgeons should be aware that tendon sheaths and the carpal sheath in particular appear to have higher odds of developing sepsis following endoscopic surgery.

Radiofrequency Probe and Sharp Transection for Tenoscopic-Guided Desmotomy of the Accessory Ligament of the Superficial Digital Flexor Tendon.

To compare intra and postoperative clinical features of desmotomy of the accessory ligament of the superficial digital flexor tendon (ALSDFT) using the Saber radiofrequency (SaberRF) electrosurgical probe versus sharp transection with a tenotomy knife. Randomized, controlled, blocked (horse) design. Adult horses (n = 6). Each horse received bilateral, tenoscopic-guided ALSDFT desmotomy with a SaberRF and tenotomy knife, randomly assigned to left, or right limb. The desmotomy duration and intraoperative hemorrhage grades were recorded. Postoperatively, the grades for surgical incision, carpal sheath effusion, carpal range of motion, flexion pain, and lameness were recorded. Light microscopy using hematoxylin and eosin, and viability staining were performed on the ALSDFT, flexor carpi radialis tendon, radial head of the deep digital flexor tendon, and the deep digital flexor tendon. Variables were compared between desmotomy methods with a paired t-test, Wilcoxon signed rank test, or a repeated measures mixed model. Statistical significance was set at P < .05. Desmotomy of the ALSDFT was completed in all horses. Only mild hemorrhage was observed and not different between methods (SaberRF 2/5 limbs; tenotomy knife 5/6 limbs, P = .078). Carpal sheath effusion was greater for SaberRF at Day 1 (P = .019) but not different from tenotomy knife at any later time. There was no significant difference between methods for viability staining or other measured outcomes. Tenoscopic-guided ALSDFT desmotomy with the SaberRF probe showed no difference in measured outcomes to sharp transection with a tenotomy knife and minimal collateral tissue damage was observed.

Ultrasonographic assessment of the equine palmar tendons.

Aim:The present study was conducted to evaluate the equine palmar tendon by ultrasonography (USG) in standing the position.Materials and Methods:USG of palmar tendons was performed in 40 adult horses using linear transducer having frequency of 10-18 MHz (e-soate, My Lab FIVE) and L52 linear array transducer (Titan, SonoSite) with frequencies ranging from 8 to 10 MHz. Palmar tendon was divided into 7 levels from distal to accessory carpal bone up to ergot in transverse scanning and 3 levels in longitudinal scanning.Results:The USG evaluation was very useful for diagnosis of affections of the conditions such as chronic bowed tendon, suspensory ligament desmitis, carpal sheath tenosynovitis and digital sheath effusions. The mean cross-sectional area (cm2) of affected tendons was significantly increased in affected than normal tendons. The echogenicity was also found reduced in affected tendons and ligaments along with disorganization of fiber alignment depending on the severity of lesion and injury.Conclusion:USG proved ideal diagnostic tool for diagnosis and post-treatment healing assessment of tendon injuries in horses.

Musculoskeletal lesions and lameness in 121 horses with carpal sheath effusion (1999-2010).

Equine carpal sheath effusion has multiple etiologies. The purpose of this retrospective study was to describe the prevalence of distinct musculoskeletal lesions lameness in a sample of horses with a clinical diagnosis of carpal sheath effusion. A total of 121 horses met inclusion criteria. Seventy-four percent (89/121) of horses were lame at presentation; middle-aged (9-18 years, 80%) and older (> 18 years, 85%) horses were lame more frequently than young horses (< 9 years, 44%). Ninety-three percent (113/121) were diagnosed with osseous and/or soft tissue abnormalities. Of these 113 horses, 10 exhibited osseous abnormalities, whereas 111 were diagnosed with soft tissue lesions. Eighty-four percent (93/111) of the soft tissue injuries extended from the caudodistal antebrachium to the palmar metacarpus. The superficial digital flexor tendon (98/111; 88%) and accessory ligament of the superficial digital flexor tendon (64/111; 58%) were the most commonly injured structures, with both structures affected in 41 (41/111; 37%) horses. Injuries within the caudodistal antebrachium included the superficial digital flexor musculotendinous junction (66), the accessory ligament of the superficial digital flexor tendon (64), and deep digital flexor muscle (21), in isolation or in combination with other structures. Increased echogenicity in the medial superficial digital flexor musculotendinous junction was detected in 40 horses and was significantly associated with increasing age (middle-aged, 19/40; old, 18/40). Findings from this study indicated that age should be taken into consideration for horses presented with carpal sheath effusion and that adjacent structures within the caudodistal antebrachium should be included in evaluations.

Diagnosis and treatment of intrathecal tears of the accessory ligament of the superficial digital flexor

SummaryReasons for performing studyTears of the accessory ligament of the superficial digital flexor (ALSDF) that communicate with the carpal sheath are not reported in the literature. The study describes ultrasonographic techniques for evaluation of the ALSDF and reports clinical, ultrasonographic and endoscopic features associated with intrathecal tears of the ligament.ObjectivesTo investigate whether tearing of the ALSDF can be: 1) intrathecal with respect to the carpal sheath; 2) cause lameness and distension of the carpal sheath; and 3) result in intrathecal haemorrhage by tearing vessels that appear to be direct branches of the median artery, as well as to confirm that these lesions are reliably predicted by ultrasonography.Study designRetrospective case series.MethodsCase records and diagnostic images of horses with ALSDF injuries were reviewed retrospectively, and follow‐up information was obtained.ResultsUltrasonographic examination using a combination of linear and curved array transducers identified 10 cases with intrathecal tears of the ALSDF. This was confirmed in 7 cases that underwent tenoscopy. Tears were consistently in the caudal ALSDF and in 3 cases exposed the median artery. Extruded torn fibres were removed. Of the 7 surgical cases, one horse returned to competitive work, one was back in full training, 2 were retired from racing but performing riding club activities, 2 were convalescing and one was lost to follow‐up. Of the 3 cases that did not undergo surgery, one was subjected to euthanasia and the other 2 failed to return to training.ConclusionsTears of the ALSDF can communicate with the carpal sheath, resulting in lameness and intrathecal haemorrhage. The latter appears to result from vessels that are primary branches of the median artery, and tears in the ALSDF can extend to this. These injuries are reliably predicted by multimodal ultrasonography, which also allows assessment of the proximity of tears to the median artery.

Frontal plane fractures of the accessory carpal bone and implications for the carpal sheath of the digital flexor tendons

Accurate radiological and ultrasonographic descriptions of frontal plane fractures of the accessory carpal bone (ACB) are lacking, and implications of these fractures for the carpal sheath and its contents have not previously been reported. Aims were as follows: 1) to describe the location and radiological features of frontal plane fractures of the ACB; 2) to document communication of displaced fractures with the carpal sheath and consequent injury to the deep digital flexor tendon (DDFT); 3) to describe ultrasonographic identification of lesions; and 4) to report tenoscopic evaluation and treatment. Retrospective case series. Analysis of frontal plane fractures of the ACB referred to a single hospital between 2006 and 2012, including review of radiographic, ultrasonographic and tenoscopic images. Nine fractures were identified, of which 8 displaced fractures all communicated with the carpal sheath. Comminuted fragments and/or protruding fracture margins lacerated the lateral margin of the enclosed DDFT. This was identifiable ultrasonographically and confirmed at tenoscopy in 7 cases. Treatment in these horses consisted of removal of torn tendon tissue together with fragmentation and protuberant fracture edges, and 7 of 7 cases returned to work. One horse with a nondisplaced fracture was managed with immobilisation; the fracture healed, and the horse returned to work. One horse with a displaced fracture was retired to stud. Frontal plane fractures of the ACB occur palmar to the groove in its lateral margin for the tendon of insertion of ulnaris lateralis. Comminuted fragments can displace distally within the carpal sheath to a mid-metacarpal level or abaxially to lie extrathecally, lateral to the parent bone. Displaced fractures communicate with the carpal sheath and traumatise the DDFT.

Carpal hyperextension in a Percheron mare caused by a palmar carpal ligament tear

SummaryA Percheron mare was presented for acute, severe lameness and marked swelling of the right forelimb after being cast. The mare was initially diagnosed with cellulitis of the forelimb but as her condition improved and the affected limb was able to bear more weight it became apparent that the limb was hyperextended at the level of the carpus. Widening of the palmar aspect of the middle carpal joint was observed radiographically. During ultrasonographic examination, excessive fluid in the carpal sheath and perithecal swelling were noted and tearing of the palmar carpal ligament was suspected. A dynamic brace was fabricated to prevent hyperextension of the carpus. After discontinuation of systemic antibiotics, the mare became febrile and forelimb lameness worsened. Cytology of fluid from the middle carpal joint confirmed joint sepsis and the mare was anaesthetised for arthroscopic examination. A tear in the palmar carpal ligament, characterised by focal fibre disruption and fibrillation, was identified during arthroscopic and tenoscopic examination. Communication between the carpal flexor tendon sheath and middle carpal joint was identified during these procedures. Both the middle carpal joint and carpal flexor tendon sheath were lavaged with physiological saline solution. Post operatively, swelling and lameness slowly resolved. Four months after discharge, the mare was sufficiently sound to be maintained at pasture. Viewed from its lateral aspect, the limb no longer appeared to be hyperextended from the carpus.

Tears of the Accessory Ligament of the Superficial Digital Flexor and Their Relationship to the Carpal Sheath

AimsThe study aimed to describe an ultrasonographic technique for evaluation of the accessory ligament of the superficial digital flexor (ALSDF) and to report the presentation, clinical, ultrasonographic and endoscopic features associated with intrathecal tears of the ligament.MethodsThe case records of 83 horses that underwent ultrasonography of the carpal sheath by the author between 2008 and 2012 were evaluated. Injuries of the ALSDF were identified and reviewed.ResultsTen horses had injuries to the ALSDF. All cases were assessed using linear and curved array transducers in caudomedial to craniolateral orientations. The former was used in transverse and longitudinal orientations and with colour Doppler to assess intra‐ and periligamentous vasculature. The curved array transducer was used for transverse studies both with the limb weightbearing and with slight carpal flexion. This combination of imaging studies detected tearing of the ALSDF which communicated with the carpal sheath in all 10 cases. Seven of the 10 cases underwent tenoscopic examination which confirmed the ultrasonographic findings. The areas of torn ALSDF were in consistent locations and with similar lesion morphology.ConclusionsDisruption of the ALSDF can communicate with the carpal sheath resulting in lameness and intrathecal haemorrhage. The latter appears to result from vessels which are primary branches of the median artery and tears in the ALSDF can extend to this. The injuries are reliably predicted by ultrasonography. This also allows assessment of the proximity of the tear to the median artery which in turn is an important guide for subsequent tenoscopic surgery.Practical significanceUltrasonographic evaluation of the ALSDF can identify tears which communicate with the carpal sheath. Tenoscopy should then be considered as a treatment option.Ethical animal researchNot required by this Congress: retrospective clinical study. Sources of funding: None. Competing interests: None.

COMPUTED TOMOGRAPHIC ARTHROGRAPHY OF THE INTERCARPAL LIGAMENTS OF THE EQUINE CARPUS

Injuries of the intercarpal ligaments are an important cause of lameness in performance horses. The purpose of this prospective cadaver study was to determine whether computed tomography (CT) arthrography would be a feasible method for visualizing and characterizing intercarpal ligaments in the horse. One cadaver limb from each of eight nonlame horses was collected immediately after euthanasia. For each limb, overlapping 2.0 mm CT images were acquired before and after injection of iodinated contrast medium into the antebrachiocarpal joint, middle carpal joint, and carpal sheath. Spin echo magnetic resonance imaging (MRI) sequences were acquired in three planes using a 1.5 Tesla MRI scanner in three limbs. Following MRI, colored resin was injected into the synovial structures of these three limbs, limbs were frozen, and anatomic sections were obtained in three planes. Findings from CT arthrograms were compared to findings from precontrast CT, MRI, anatomic slices, and arthroscopy. Medial and lateral palmar intercarpal ligaments, radiocarpal and transverse intercarpal ligaments, and palmar carpal ligament were visible in CT arthrograms of all limbs. The proximal and distal entheses of all ligaments were readily identifiable. Findings indicated that CT arthrography is feasible for visualizing intercarpal ligaments and may be a useful adjunct imaging technique for diagnosing lameness due to suspected carpal ligament injury in horses.

Diffusion of contrast medium after four different techniques for analgesia of the proximal metacarpal region: an in vivo and in vitro study

There is limited information on potential diffusion of local anaesthetic solution after various diagnostic analgesic techniques of the proximal metacarpal region. To document potential distribution of local anaesthetic solution following 4 techniques used for diagnostic analgesia of the proximal metacarpal region. Radiodense contrast medium was injected around the lateral palmar or medial and lateral palmar metacarpal nerves in 8 mature horses, using 4 different techniques. Radiographs were obtained 0, 10 and 20 min after injection and were analysed subjectively. A mixture of radiodense contrast medium and methylene blue was injected into 4 cadaver limbs; the location of the contrast medium and dye was determined by radiography and dissection. Following perineural injection of the palmar metacarpal nerves, most of the contrast medium was distributed in an elongated pattern axial to the second and fourth metacarpal bones. The carpometacarpal joint was inadvertently penetrated in 4/8 limbs after injections of the palmar metacarpal nerves from medial and lateral approaches, and in 1/8 limbs when both injections were performed from the lateral approach. Following perineural injection of the lateral palmar nerve using a lateral approach, the contrast medium was diffusely distributed in all but one limb, in which the carpal sheath was inadvertently penetrated. In 5/8 limbs, following perineural injection of the lateral palmar nerve using a medial approach, the contrast medium diffused proximally to the distal third of the antebrachium. Inadvertent penetration of the carpometacarpal joint is common after perineural injection of the palmar metacarpal nerves, but less so if both palmar metacarpal nerves are injected using a lateral approach. Following injection of the lateral palmar nerve using a medial approach, the entire palmar aspect of the carpus may be desensitised.