Contrast Arthrography Research Articles

Osseous cyst‐like lesions in an unusual location in the equine distal phalanx

SummaryOsseous cyst‐like lesions (OCLLs) of the distal phalanx commonly occur around midline. The dorsopalmar location can be challenging to identify radiographically; however, advanced imaging has shown they are typically located in the central and palmar thirds of the bone. This study reports unusually located OCLLs in the dorsal, axial aspect of the palmar processes of the distal phalanx in three horses, with communication with the distal interphalangeal (DIP) joint confirmed by contrast arthrography in two horses. All horses were lame and had lameness localised to the distal limb with diagnostic anaesthesia. A rounded radiolucency with a surrounding rim of increased opacity was identified in the dorsal aspect of a palmar process on radiographs, with the palmaroproximal–palmarodistal oblique (PaPrPaDiO) view being most useful. On magnetic resonance imaging (MRI), the lesions were seen as hyperintense structure on T2*, T2 FSE and STIR sequences; a thin rim of intermediate signal surrounding a low signal centre was seen on T1 images. A rim of low T1/T2 FSE signal was seen in the surrounding bone in all cases, consistent with sclerosis, and mildly increased STIR signal was present in the surrounding trabecular bone in two cases. Two horses underwent standing cone‐beam computed tomography (CT) examination of the affected foot, revealing a well‐defined hypoattenuating region within the dorsal, axial aspect of the palmar process of the distal phalanx, with surrounding rim of increased attenuation. Contrast arthrography was performed in two cases, one using radiographs and the other CT, and confirmed communication of the cystic lesion with the DIP joint in both cases. Although advanced imaging provided further information and allowed other possible causes of lameness to be identified, careful assessment of radiographs allowed these unusually located OCLLs to be identified in all cases.

Contrast arthrography of the equine temporomandibular joint.

Disorders of the equine temporomandibular joint (TMJ) cause clinical problems and detailed investigations of this joint are becoming more common. Specialist radiographic projections have the potential to highlight osseous abnormalities; however, the ability to assess the intra-articular soft tissue structures is currently limited to computed tomography (with, or without contrast enhancement) or magnetic resonance imaging. Both modalities are expensive and not readily accessible. To develop a technique of contrast arthrography of both compartments of the equine TMJ in cadavers and then perform the refined technique in three living horses as a proof-of-principle. A descriptive, experimental, study. Contrast arthrography of the discomandibular and discotemporal joint compartments of both TMJs was performed in 12 cadaveric equine heads using needles placed in the caudal pouches of the respective joint compartments. Radiographs were taken using previously published techniques, repeated with the mouth open and after air had been injected into the joints, to perform a double-contrast study. The TMJs of three healthy horses were subsequently examined to determine the validity of the procedure in live animals. Single and double-contrast arthrography allowed delineation of the dorsal and ventral surfaces of the intra-articular disc in addition to filling the rostral and caudal joint pouches of the independent joint compartments. Contrast extravasation was common, and in two instances iatrogenic disc penetration resulted in the false diagnosis of pathologic disc perforation. The techniques were well tolerated in all three live horses. Low number of horses. Contrast arthrography allows interpretation of intra-articular soft tissue structures, but caution is advised in diagnosing intra-articular disc perforation. Even with experience, accessing the discomandibular joint can be challenging.

Quantitative assessment of the knee joint from weight bearing computed tomography

In recent years weight bearing computed tomography (WBCT) has been applied to the knee, delivering 3-D imaging in a physiologically loaded stance. Several quantitative approaches have been used to evaluate this data, with the greatest focus on joint space width (JSW) leading to 3-D JSW being potentially sensitive enough as a useful structural biomarker. Studies of JSW and lower limb alignment have been facilitated by novel technologies and have demonstrated significant differences between the non-weight bearing and weight bearing positions. Further work is needed to look at whole lower limb alignment that involves the interplay of all the joints of the lower limb. Steps are being taken to quantify bone parameters from cone beam technology, while there is an opportunity for contrast arthrography to evaluate articular cartilage and the meniscus in a weight bearing position. The concept of weight bearing imaging has also led to the evolution of different technology solutions, including different types of cone beam set up, upright and supine-loaded multidetector CT techniques. This latter approach has included kinematic CT with gating for acquisitions in different angles of flexion. WBCT has also been combined with MRI for finite element analysis of the meniscus. The increasingly varied applications of WBCT at the knee broadens its definition and hold potential for enhancing our understanding of factors in the onset and progression of osteoarthritis. However a consensus on standardized protocols will be required to facilitate these advances.

The value of combined ultrasound contrast arthrography and subacromial-subdeltoid bursography for detecting and differentiating the rotator cuff tear subtypes in patients with the uncertain rotator cuff tear.

In this study, ultrasound (US) contrast arthrography and subacromial-subdeltoid bursography with the contrast agent of SonoVue were performed to evaluate their value for detecting and differentiating the rotator cuff tear (RCT) subtypes in patients with the uncertain RCT. A total of 102 patients with the clinically suspected RCTs in the orthopedic clinic were prospectively recruited and underwent conventional high-frequency US for the category of undoubted full-thickness RCT, uncertain RCT, and intact rotator cuff. Among these patients, the patients with uncertain RCT underwent the subsequent US contrast arthrography and subacromial-subdeltoid bursography. The arthroscopic findings were used as the gold standard in this study. After the conventional US screening, 62 patients with uncertain RCT underwent the subsequent US contrast arthrography and subacromial-subdeltoid bursography. All the US contrast arthrography and subacromial-subdeltoid bursography were successfully performed and no severe side effects were observed in all the patients. For full-thickness tears, the sensitivity and specificity of the combined US contrast arthrography and subacromial-subdeltoid bursography were 94.7% (CI: 0.72-1.0) and 81.4% (CI: 0.66-0.91), respectively, and for articular-side tears 100% (CI: 0.51-1) and 100% (CI: 0.92-1), respectively, and for the bursal-side tears 84.6% (CI: 0.54-0.97) and 97.9% (CI: 0.88-1.0), respectively. The main inconsistency between the contrast-enhanced US and arthroscopy was that 7 patients with arthroscopic proved concurrent articular- and bursal-side tears were indicated as full-thickness RCTs on contrast-enhanced US. Combined US contrast arthrography and subacromial-subdeltoid bursography are useful for detecting the RCT subtypes in patients with the uncertain RCTs. When conventional high-frequency US has some difficulty in differentiating the full-thickness from partial-thickness RCTs, combined US contrast arthrography and subacromial-subdeltoid bursography could be used to improve the detection accuracy of RCT subtypes. • This is the first study by injection of the US contrast agent SonoVue into the shoulder joint cavity and subacromial-subdeltoid bursa for the detection and differentiation of the RCT subtypes among the people with the uncertain RCT by conventional US screening. • The SonoVue was injected into the glenohumeral joint cavity under US guidance to differentiate the full-thickness RCTs from partial-thickness RCTs. • Combined US contrast arthrography and subacromial-subdeltoid bursography are useful for detecting the RCT subtypes in patients with the uncertain RCTs.

Diagnosis of medial meniscal lesions in the canine stifle using multidetector computed tomographic positive-contrast arthrography.

To assess diagnostic value and clinical utility of multidetector computed tomographic positive contrast arthrography (CTA) for meniscal lesions in dogs. Prospective case series. Client-owned dogs (n = 55) with cranial cruciate ligament injuries. Sedated dogs underwent CTA using a 16-slice scanner, and subsequently received mini-medial arthrotomy for meniscal assessment. Scans were anonymized, randomized, and reviewed twice for meniscal lesions by three independent observers with varying experience. Results were compared with surgical findings. Reproducibility and repeatability were assessed with kappa statistics, intraobserver changes in diagnosis by McNemar's test, and interobserver differences using Cochran's Q test. Test performance was calculated using sensitivity, specificity, proportion correctly identified, and positive and negative predictive values and likelihood ratios. Analysis was based on 52 scans from 44 dogs. Sensitivity for identifying meniscal lesions was 0.62-1.00 and specificity was 0.70-0.96. Intraobserver agreement was 0.50-0.78, and interobserver agreement was 0.47-0.83. There was a significant change between readings one and two for the least experienced observers (p < .05). The sum of sensitivity and specificity exceeded 1.5 for both readings and all observers. Diagnostic performance was suitable for identifying meniscal lesions. An effect of experience and learning was seen in this study.

Imaging and Gross Pathological Appearance of Changes in the Parasagittal Grooves of Thoroughbred Racehorses.

Simple SummaryEarly detection of racehorses at risk of stress fracture is key to reducing the number of horses with catastrophic fractures while racing. Bone changes are often visible in the limbs of Thoroughbred racehorses in work, particularly in the fetlock region. However, it is currently unknown whether some of these changes indicate an impending fracture or are a healthy adaptation to high-speed exercise. This study looks at imaging and gross changes in a specific area (parasagittal grooves (PSGs) of the cannon bone) and the utility of X-ray, computed tomography (CT) and magnetic resonance imaging (MRI) to detect the changes. All fetlock joints were assessed from twenty horses that died during racing or training, including horses with and without fetlock fracture. Overall, X-ray was poor for detecting PSG changes. Some PSG changes on CT and MRI were common in Thoroughbred racehorses and possibly represent normal bone adaptation when seen in clinical cases. However, certain CT and MRI findings were more prevalent in horses with a fracture, possibly indicating microdamage accumulation and increased risk of fracture. Bilateral advanced imaging is recommended in clinical cases of suspected fetlock pathology.(1) Background: Parasagittal groove (PSG) changes are often present on advanced imaging of racing Thoroughbred fetlocks and have been suggested to indicate increased fracture risk. Currently, there is limited evidence differentiating the imaging appearance of prodromal changes in horses at risk of fracture from horses with normal adaptive modelling in response to galloping. This study aims to investigate imaging and gross PSG findings in racing Thoroughbreds and the comparative utility of different imaging modalities to detect PSG changes. (2) Methods: Cadaver limbs were collected from twenty deceased racing/training Thoroughbreds. All fetlocks of each horse were examined with radiography, low-field magnetic resonance imaging (MRI), computed tomography (CT), contrast arthrography and gross pathology. (3) Results: Horses with fetlock fracture were more likely to have lateromedial PSG sclerosis asymmetry and/or lateral PSG lysis. PSG lysis was not readily detected using MRI. PSG subchondral bone defects were difficult to differentiate from cartilage defects on MRI and were not associated with fractures. The clinical relevance of PSG STIR hyperintensity remains unclear. Overall, radiography was poor for detecting PSG changes. (4) Conclusions: Some PSG changes in Thoroughbred racehorses are common; however, certain findings are more prevalent in horses with fractures, possibly indicating microdamage accumulation. Bilateral advanced imaging is recommended in racehorses with suspected fetlock pathology.

Traumatic communication of the extensor carpi radialis tendon sheath and antebrachiocarpal joint in two horses

SummaryTwo horses were examined due to lacerations at the level of the craniodistal antebrachii. Further evaluation of the lacerations revealed communication with the extensor carpi radialis tendon sheath and potentially the antebrachiocarpal joint. Positive contrast arthrography performed via the palmarolateral pouch of the antebrachiocarpal joint was used to diagnose communication with the extensor carpi radialis tendon sheath. Both the joints and tendon sheaths were treated aggressively with surgical debridement and lavage, followed by post operative medical management and rehabilitation. Both horses made a full recovery and are performing in their intended level of use with acceptable cosmetic results. Traumatic communication with the carpal joints should be considered when evaluating lacerations involving the forelimb extensor tendon sheaths.

Humeral avulsion of the glenohumeral ligament: The J sign

The lesion resulting from humeral avulsion of the glenohumeral ligament (HAGL) is an important cause of anterior glenohumeral instability and can be seen in isolation or combination with an antero-inferior labral complex lesion. A conclusive magnetic resonance imaging diagnosis is aided when either a joint effusion is present or a contrast arthrography of the shoulder is performed.It is important to be familiar with the J sign as it represents contrast leaking through the defect in the lateral attachment of the joint capsule.

Synovial herniation as a complication of arthroscopy in a Thoroughbred yearling

Summary This paper reports the successful use of a half limb cast to treat prior failures in healing of a synovial hernia in a Thoroughbred yearling. The hernia was due to a nonhealing arthroscopy portal and was confirmed using ultrasonography and positive contrast arthrography to visualise the communication between the metacarpophalangeal joint and subcutaneous space. Surgery was performed 3 times, due to failure of healing of the joint capsule and recurrence of clinical signs. A half limb cast applied following the final surgery effected a repair. At 2 months post surgery there was no recurrence of the subcutaneous swelling and at 3 months post surgery a repeat positive contrast arthrogram confirmed healing of the hernia.

Anaesthetic arthrography of the shoulder joint in dogs

To evaluate the use of intra-articular anaesthesia combined with positive contrast arthrography (collectively called 'anaesthetic arthrography' [AA]) in the shoulder in order to identify and confirm the source of pain in lame dogs. Anaesthetic arthrography was performed in 30 dogs with shoulder joint lameness with a mixture of contrast medium (iohexol: 240 mg I/ml) and a local anaesthetic (mepivacaine 2%: 20 mg/ml). The effect of intra-articular anaesthesia was evaluated by an objectified visual scoring system and the arthrograms were evaluated for their diagnostic value. This study showed that AA was positive in 28 out of 30 dogs. Dilution of the contrast medium with a local anaesthetic produced an arthrogram of good quality for each shoulder joint. In 16 out of 18 cases of osteochondritis dissecans, a cartilage flap could be identified following arthrography. In all cases the flap was not identified from plain radiographs. Biceps brachii tendon pathology was diagnosed on arthrography in seven dogs but was missed in two dogs. Calcification at the caudal rim of the glenoid cavity was diagnosed in three dogs, but was of clinical importance in only two dogs. In addition one infection was diagnosed during synovial aspiration. Anaesthetic arthrography of the shoulder is a simple, safe, and reliable diagnostic test to confirm shoulder joint pain and simultaneously identify a lesion. This procedure may be of particular importance in cases of occult shoulder joint lameness when clinical findings and plain radiographs are inconclusive.

Functional MRI in pre-surgical planning: Case study and cautionary notes

The lesion resulting from humeral avulsion of the glenohumeral ligament (HAGL) is an important cause of anterior glenohumeral instability and can be seen in isolation or combination with an antero-inferior labral complex lesion. A conclusive magnetic resonance imaging diagnosis is aided when either a joint effusion is present or a contrast arthrography of the shoulder is performed.It is important to be familiar with the J sign as it represents contrast leaking through the defect in the lateral attachment of the joint capsule.

A Descriptive Study of the Equine Proximal Interphalangeal Joint Using Magnetic Resonance Imaging, Contrast Arthrography, and Arthroscopy

To describe regions of the thoracic and pelvic limb proximal interphalangeal (PIP) joints that are arthroscopically accessible and identify soft tissue structures that should be avoided during arthroscope and instrument placement. Experimental ex vivo descriptive study. Horses (n = 15). Cadaver limbs (n = 36) were used for anatomic modeling, magnetic resonance imaging (MRI) with MRI-compatible needles, computed tomography with contrast arthrography, and arthroscopy of the PIP joint. Two arthroscopic approaches to the dorsal joint pouch were compared. With arthroscopy, 62.4% of the joint perimeter could be observed from the dorsal and palmar/plantar joint pouches with no significant difference in the amount of joint observed when using the more proximal or distal approach to the dorsal joint pouch (P =.59). The dorsal and palmar/plantar joint pouches provide adequate arthroscopic visibility for the axial portions of the articular surface of the proximal and middle phalanx. The abaxial portions of the articular surface were difficult to view because of narrowing of the joint pouches abaxially. When comparing the proximal and distal approach to the dorsal joint pouch, arthroscope insertion 1.5 cm proximal to the joint allowed the easiest manipulation of the arthroscope. Palmar/plantar portals were placed dorsal to the neurovascular bundle, proximal to the epicondyle of the middle phalanx to prevent tendon and ligament injury.

A study of the anatomy and injection techniques of the ovine stifle by positive contrast arthrography, computed tomography arthrography and gross anatomical dissection

Although ovine stifle models are commonly used to study osteoarthritis, meniscal pathology and cruciate ligament injuries and repair, there is little information about the anatomy of the joint or techniques for synovial injections. The objectives of this study were to improve anatomical knowledge of the synovial cavities of the ovine knee and to compare intra-articular injection techniques. Synovial cavities of 24 cadaver hind limbs from 12 adult sheep were investigated by intra-articular resin, positive-contrast arthrography, computed tomography (CT) arthrography and gross anatomical dissection. Communication between femoro-patellar, medial femoro-tibial and lateral femoro-tibial compartments occurred in all cases. The knee joint should be considered as one synovial structure with three communicating compartments. Several unreported features were observed, including a communication between the medial femoro-tibial and lateral femoro-tibial compartments and a latero-caudal recess of the lateral femoro-tibial compartment. No intermeniscal ligament was identified. CT was able to define many anatomical features of the stifle, including the anatomy of the tendinous synovial recess on the lateral aspect of the proximal tibia under the combined tendon of the peroneus tertius, extensor longus digitorum and extensor digiti III proprius. An approach for intra-articular injection into this recess (the subtendinous technique) was assessed and compared with the retropatellar and paraligamentous techniques. All three injection procedures were equally successful, but the subtendinous technique appeared to be most appropriate for synoviocentesis and for injections in therapeutic research protocols with less risk of damaging the articular cartilage.

Detection of Articular Pathology of the Distal Aspect of the Third Metacarpal Bone in Thoroughbred Racehorses: Comparison of Radiography, Computed Tomography and Magnetic Resonance Imaging

To compare digital radiography (DR), computed tomography (CT), and magnetic resonance imaging (MRI) for detection of pathology of the distal aspect of the third metacarpal bone (MC3) and to assess whether arthrography would improve detection of articular cartilage or subchondral bone cracking. Cross-sectional study. Limb specimens from 17 Thoroughbred horses after catastrophic injury and 4 age-matched control horses. Standard DR, CT, and MRI images of the metacarpophalangeal joint were acquired before and after iohexol injection. Pathologic features detected with imaging and on visual inspection of cartilage and subchondral bone of the distal aspect of MC3 were graded. Imaging observations were compared with pathologic abnormalities. Inspection revealed obvious changes in the cartilage and subchondral bone surfaces in Thoroughbreds. Both CT and MRI were superior to DR for detection of subchondral bone pathology. Cracking of cartilage was not detected by any imaging modality. Signal changes associated with cartilage loss and development of repair tissue were evident on MRI in 9/19 cases. There was significant correlation (P < .05) between subchondral bone pathology detected on both CT and MRI, and cartilage pathology on gross examination. Contrast arthrography did not improve the detection of articular cartilage or subchondral plate cracking. Both CT and MRI are superior to DR for detection of subchondral bone pathology, but underestimate the extent of joint adaptation and pathologic damage. MRI was able to detect cartilage degeneration.

Sinovite proliferativa crônica da articulação metacarpofalangiana em equinos: relato de caso

A Mangalarga foal was examined presenting both front limb lameness. The clinical examination revealed angular limb deformity and increased pain sensation, notably on the front left limb, which showed a reduced range of motion on the metacarpophalangeal joint. X-ray images indicated chronic proliferative synovitis in the above mentioned joint. Positive contrast arthrography confirmed a space occupying mass on the dorsoproximal surface of the joint. Due to the severity of the lesion, arthrostomy was performed followed by the removal of the proliferative tissue, to reduce the risk of pathological fracture on the distal end of the metacarpus III.

Hip Joint Arthrography with Double Contrast in Children and Adolescents

Experience in use of hip joint double contrast arthrography in 207 patients (236 joints), aged 2-14 years, with Perthes disease and various forms of hip dysplasia was analyzed. Basing on the study of contrast arthrograms the roentgenologic signs reflecting the joint state in the abovementioned pathology were detected and described. It was stated that the data of contrast examination enabled to work out in details the notion of hip joint pathology with regard for soft tissues condition and in some cases were the most important when choosing the treatment tactics. Diagnostic signs, which were to be taken into account while working out the surgical intervention protocol - that is of great practical importance, were determined.

Axial STIR MRI: A faster method for confirming femoral head reduction in DDH

Non-concentric reduction of the femoral head within the acetabulum is detrimental to its delicate cartilaginous structure and may result in a growth disturbance. Successful relocation of the dislocated femoral head depends on subtle clinical findings and radiography. The combination of a dislocated femoral head and a severely dysplastic acetabulum can result in a clinical examination that is unhelpful in confirming reduction under anaesthesia. In cases where uncertainty existed regarding head reduction in a spica cast, we performed axial short inversion time inversion recovery (STIR) and axial proton density magnetic resonance imaging (MRI) scans. We retrospectively reviewed the efficiency and accuracy of MRI in confirming femoral head location after closed reduction and spica application in eight children. One hundred and fifty-three cases of developmental dysplasia were treated with examination under anaesthesia and spica application in our unit over a 3-year period. Eight cases where MRI scanning was performed were identified. Before application of the spica cast, we used radiographic screening to assess the stability of the reduction. Absence of the ossific nucleus within the femoral head made confirmation of the location with the image intensifier unreliable. To confirm concentric femoral head location after closed reduction and spica application, we performed an MRI scan in the immediate post-anaesthesia period. All scans were performed within 30 min of application of the spica, and the average time for each scan was 5 min. All eight children who had MRI post-application of the spica had concentric reduction of the femoral head. MRI allowed three-dimensional appreciation of the acetabulum and femoral head. Use of the axial STIR images allows accurate assessment of the cartilaginous ossific nucleus. All patients were discharged the same afternoon and followed up as outpatients. No patient in our group required contrast arthrography. While not indicated in all cases of femoral head dislocation, MRI is useful to confirm concentric reduction of the femoral head in a dysplastic acetabulum when examination under anaesthesia and radiographic screening have been uncertain. In our series, 1 in 20 cases needed MRI. This is a reliable, non-invasive method confirming definite reduction of the femoral head prior to discharge in all of our patients. In this initial series, all patients had axial and coronal STIR and proton density MRI. We now only use axial STIR images because they provide adequate information regarding the position of the femoral head relative to the acetabulum.

The clinical importance of arthrography after lesions of the meniscus and capsular ligament (author's transl)

Clinical, arthrographic and operative findings of 100 patients were compared and analyzed by a study group with the result, that in questionable lesions of the meniscus, the indication for a double contrast arthrography was markedly reduced when plain films of the knee, an exact case history and a physical examination of the knee joint were performed. Above all, the improved examination technique, with the knowledge of the functional anatomy of the capsular ligament apparatus and the correlation of all stabilizing forces of the knee joint had reduced clinical errors in diagnosis. Clinically clearly analyzed meniscus lesions are therefore no indication for arthrography. In our clinic the indicatin will be reduced to those cases where there are still complaints after meniscectomy. There is a great advantage, if the examinating physician, the radiologist and the orthopedic surgeon cooperate closely together.

Considerations about the knee arthrography for detection of meniscal tears

Dear Editor,We have read with great interest the article entitled:‘‘The value of magnetic resonance imaging in our currentmanagement of ACL and meniscal injuries’’ [14]. Weagree with authors that magnetic resonance (MR) would bebeneficial in those patients where the clinical diagnosis of ameniscal tear is unclear and that it is expensive andrequires a long waiting time of 6–8 weeks. Some authors[15] report that MR findings do not always agree withsurgical findings and that false-positive and false-negativediagnoses may be due to MR interpretation error or due tothe insensitivity of MR in detecting some tears. In partic-ular, among meniscal types of lesions, radial lesions aredifficult to visualize on MRI [2]. In our opinion a relativelyold technique, low-cost and quick to perform, such as thedouble-contrast arthrography (Fig. 1) should be reminded,at least under a perspective historical view, for detection ofmeniscal tears, in particular for radial tears. As reported byFreiberger et al. [4], the arthrographic finding of a radialtear is subtle and the only abnormality detected is a relativeincrease in density of the inner portion of the wedge, whosearea has a relatively sharply defined outer margin, so thatthe difference in the density is easily identified as a radialtear. After this consideration, it should be pointed out thatwhereas MR and CT are high costs procedures, arthrog-raphy is relatively inexpensive and does not needscheduling [6]. Although it is an invasive method, double-contrast arthrography permits to evaluate meniscal tearswhen patients are operated on with metal devices in theirbody (namely: artificial heart valves, cochlear ear implants,intracranial aneurysm clips, tattoos made from iron oxidepigments, cardiac pacemakers, prosthetic hip and knees,metal body piercings and so on). In fact MR is contrain-dicated in the presence of internal metallic objects, becausethe constant strong magnetic field used for MR canpotentially pull on any ferromagnetic metal object, there-fore shifting its position. Accidents are uncommon, butmost accidents that do occur are potentially severe, namely :burns, ecchymosis, extrusion of a magnetic implant,anaphylactoid reactions to MR intravenous contrast agentsand even death [1]. While MR can cause long-termclaustrophobia [1] from the patient being within theenclosed space of the MR machine, Otto and Kallenber-ger [11] describe knee arthrography as a safe procedurethat cause very little discomfort to the patient. Thijn [13]reports double-contrast arthrography as superior toarthroscopy in the diagnosis of medial meniscus lesion,provided that the arthroscopy is carried out only from theanterolateral side. In our opinion this is an interestingdiagnostic aspect, considering that bucket-handle tearsinvolve the medial meniscus more frequently than thelateral meniscus [16]. Stoker [12] and Kempf [7] report95% diagnostic accuracy of the double contrast arthrog-raphy in lesions of the menisci, highlighting its role indemonstrating certain areas of the menisci which arevisualized with difficulty on arthroscopy. This aspect isconfirmed by Evans et al. [3] where the difficulty of thearthroscopist in reaching the posterior horn of the medial

COMPARISON OF MAGNETIC RESONANCE CONTRAST ARTHROGRAPHY AND ARTHROSCOPIC ANATOMY OF THE EQUINE PALMAR LATERAL OUTPOUCHING OF THE MIDDLE CARPAL JOINT

The objective of this report was to provide an anatomic description of the equine palmar lateral outpouching of the middle carpal joint by comparing its arthroscopic and magnetic resonance (MR) contrast arthrography appearance and to define the structures within the palmar lateral outpouching of the middle carpal joint that can be assessed arthroscopically. MR contrast arthrography was performed on seven cadaveric limbs; images were compared with those obtained during arthroscopic exploration of the palmar lateral outpouching of the middle carpal joint. Gross dissection was performed to confirm identification of intra-articular structures. The MR images compared well with the arthroscopic and gross appearance of the palmar lateral outpouching of the middle carpal joint. Portions of the ulnar carpal bone, fourth carpal bone, fourth metacarpal bone, lateral palmar intercarpal ligament, and lateral collateral ligament of the carpus were identified within the palmar lateral outpouching of the middle carpal joint in all limbs. In addition, in three limbs areas of the third carpal bone and intermediate carpal bone could be seen. MR arthrography was a useful tool for helping to define the anatomy of the palmar lateral outpouching of the middle carpal joint. The arthroscopic approach to the palmar lateral outpouching of the middle carpal joint is technically easy, but the intra-articular anatomy can be confusing. Use of a motorized arthroscopic blade to remove excess synovial tissue is necessary to view all of the structures within the palmar lateral outpouching of the middle carpal joint. Arthroscopic removal of osteochondral fragments from this location may be facilitated by the information obtained from this study.