Anatomy of the collateral ligaments of the feline elbow joint: functional implications

Cats show a higher capability to supinate their forearms than dogs. This suggests a special arrangement of the collateral ligaments of the feline elbow joint. Therefore, the course of the ligaments was examined in 13 adult cats. The size of the ligaments was measured, and effects of passive joint movements were studied. Ligaments of five additional cats were examined histologically. The lateral collateral ligament (LCL) had a superficial and deep part, both originating from the humerus. The free humeral portion of the LCL was short and contained fibrous cartilage. Fibre bundles of the deep part inserted into the annular ligament, while the remaining deep fibres and the superficial part inserted with a long antebrachial portion on the radius. The medial collateral ligament (MCL) originated from the humeral epicondyle and divided into cranial and caudal parts. The caudal part inserted medioproximally on the ulna, while the cranial part attached primarily with a long thin part to the caudal aspect of the radius. During supination, the MCL loosened thus allowing medial widening of the joint space, up to 2 mm. A specific feature of the feline elbow is the long thin part of the MCL. Its course through a special furrow distal to the medial coronoid causes the tightening of the feline MCL during pronation. Apart from that, the feline collateral ligaments combine the features of both human and canine cubital anatomy. This explains the range of supination in cats, which is intermediate between humans and dogs.     

In vitro biomechanical study of rotational stabilizers of the canine elbow joint

OBJECTIVE: To develop a model for measuring rotary stability of the canine elbow joint and to evaluate the relative contribution of the anconeal process (AN), lateral collateral ligament (LCL), and medial collateral ligament (MCL). SAMPLE POPULATION: 18 forelimbs from 12 canine cadavers. PROCEDURE: Forelimbs were allocated to 3 experimental groups (6 forelimbs/group). Each intact forelimb was placed in extension at an angle of 135 degrees and cycled 50 times from -16 degrees (pronation) to +28 degrees (supination) in a continuous manner at 2.0 Hz. Cycling was repeated following sectioning of the structure of interest (group 1, AN; group 2, LCL; and group 3, MCL). Torque at -12 degrees (pronation) and +18 degrees (supination) was measured for each intact and experimentally sectioned limb. A Student t test was performed to compare torque values obtained from intact verses experimentally sectioned limbs and for comparison with established criteria for differentiation of primary (> or = 33%), secondary (10 to 33%), and tertiary rotational stabilizers (< 10%). RESULTS: In pronation, the AN was the only primary stabilizer (65%). For supination, the LCL was a primary stabilizer (48%), AN was a secondary stabilizer (24%), and MCL was a tertiary stabilizer (7%). CONCLUSIONS AND CLINICAL RELEVANCE: With the elbow joint in extension at an angle of 135 degrees, the AN is a primary rotational stabilizer in pronation, and the LCL is a primary stabilizer in supination. Disruption of the AN or LCL may affect rotary range of motion or compromise stability of the elbow joint in dogs.     

In vitro validation of a technique for assessment of canine and feline elbow joint collateral ligament integrity and description of a new method for collateral ligament prosthetic replacement

Objective— To assess the ability of an operator to differentiate intact from transected canine and feline elbow joint collateral ligaments (CL) using a reported manipulative test (Campbell's test) and to determine the potential for elbow joint luxation in canine and feline elbows with intact, transected, and surgically stabilized CL. Study Design— In vitro biomechanical study. Sample Population— Canine (n=6) and feline cadavers (n=3). Methods— Thoracic limb specimens were mounted on a custom‐built jig with the elbows and carpi fixed in 90° of flexion. Angles of pronation and supination were recorded after applying rotational forces to the manus. Attempts were made to manually luxate each elbow with intact CL. Constructs were re‐evaluated after sequential sectioning of the medial (MCL) and lateral (LCL) collateral ligaments and after insertion of a new CL prosthesis. Results— Mean (±SD) angles of rotation in dogs increased from 27.3±8° (range, 16.7–41.3°) in pronation to 58.9±9.2° (range, 38–88.3°) after sectioning the MCL and from 45.5±10.8° (range, 30.7–67.3°) in supination to 68.9±17.2° (range, 45–94°) after sectioning the LCL. Angles of pronation and supination were subject to significant interanimal variability, with a strong correlation between increasing animal weight and smaller angles of rotation. Elbow luxation in dogs was not possible unless at least the LCL was transected. In cats, mean angles of rotation increased from 49.8±14.9° (range, 30.7–70°) in pronation to 99.1±17.6° (range, 79–111.7°) after sectioning the MCL and from 128.7±18.8° (range, 108.3–151.7°) in supination to 166.7±13.1° (range, 157.3–181.7°) after sectioning the LCL. Luxation in cats was not possible unless both CL were cut. Use of the ligament prosthesis without primary CL repair reliably prevented reluxation in all canine and feline elbows. Conclusions— Campbell's test allowed reliable differentiation of intact, transected and surgically stabilized canine and feline elbow joint CL in a cadaveric model. Luxation could not be performed by application of rotational forces to specimens with intact CL. Clinical Relevance— Clinical examination findings, specifically Campbell's test, can be used to determine elbow CL integrity in dogs and cats. The contralateral elbow should be used as a control, because of interanimal variability in angles of rotation.     

The ligamentum olecrani of the Elbow Joint in Dogs and Cats

The olecranon ligament ( ligamentum olecrani ) is described as an elastic ligament of the elbow joint in carnivores that tenses the caudomedial part of the joint capsule. The aim of the study was to compare the course and the microscopic structure of the ligament in dogs and cats. The elbow regions of 25 dogs and 15 cats were dissected to examine the topography of the ligament in extension and flexion. Furthermore, the olecranon ligaments of five dogs and five cats were studied using routine histological methods. Additional sections were stained with Resorcin–Fuchsin and Orcein to detect elastic fibres. In both species the olecranon ligament originates at the lateral surface of the epicondylus medialis humeri and inserts at the cranial crest of the olecranon extending distally to the roof of the processus anconeus . Tension of the ligament only occurs when the elbow joint is flexed maximally. This tension is increased by a slight supination of the forearm, which takes place automatically in this joint position. In dogs the ligament is long (30–40 mm in medium sized breeds) and relatively slim (approx. 2–4 mm). In cats the ligament is short (10–12 mm) and relatively strong (5–8 mm). The histological examination of the olecranon ligament shows all signs of a tight collagenous ligament with a negligible amount of elastic fibres. The olecranon ligament helps to limit the maximal flexion of the elbow joint. In addition, it controls a slight lateral movement of the processus anconeus during the automatic supination of the antebrachial bones in extreme flexion of the elbow joint.     

Morphometric analysis of the intercarpal ligaments of the equine proximal carpal bones during simulated flexion and extension of cadaver limbs

Despite many reported cases of carpal lameness associated with intercarpal ligament injuries in horses, the morphometry, movement pattern and general intrinsic biomechanics of the carpus are largely unknown. Using osteoligamentous preparation of the carpus prepared from 14 equine cadaver forelimbs (aged 9.62 ± 4.25 years), locomotory simulations of flexion and extension movements of the carpal joint were carried out to observed carpal biomechanics and, thereafter, the limbs were further dissected to obtain morphometric measurements of the medial and lateral collateral ligaments (MLC and LCL); medial and lateral palmar intercarpal ligaments (MPICL and LPICL); intercarpal ligaments between radial (Cr) and intermediate (Ci) carpal bones (Cr-Ci ICL); and intercarpal ligaments between Ci and ulnar (Cu) carpal bones (Ci-Cu ICL). The Cr, Ci, Cu and Ca are held together by a series of intercarpal ligaments and move in unison lateropalmarly during flexion, and mediodorsally during extension with a distinguishable proximo-distal sliding movement (gliding) of Cr and Ci against each other during movement. The mean length of MCL (108.82 ± 9.64 mm) was significantly longer (p = 0.042) than LCL (104.43 ± 7.65 mm). The Cr-Ci ICL has a dorsopalmar depth of 37.58 ± 4.14 mm and a midpoint width of 12.05 ± 3.09 mm and its fibres ran diagonally from the medial side of the Ci in a proximo-palmar disto-dorsal direction (i.e. palmarodistally) to the lateral side of the Cr. The specialized movement of the Cr-Ci ICL, which appeared to be further facilitated by a longer MCL suggest a biomechanical function by which carpal damage may be minimized in the equine carpus.     

Evaluation of the Lateral Collateral Ligament After Fibular Head Transposition in Dogs

Cranial transposition of the fibular head stabilizes the stifle joint by displacing the distal attachment of the lateral collateral ligament (LCL). The forces applied to the LCL after displacement may cause ligamentous elongation. This investigation evaluated the morphological, histological, and biomechanical changes of the LCL after fibular head transposition (FHT) in dogs. Unilateral cranial cruciate ligament (CCL) excision and FHT were performed on 25 dogs. Cross-sectional area, length, histological, and structural properties of the LCL were evaluated 3 weeks, 4 months, and 10 months after surgery. Ligament length means were significantly increased at week 3, month 4, and month 10 compared with intraoperative length means. No significant changes in elongation were observed after week 3. Fibrovascular proliferation within the LCL increased the cross-sectional area and associated structural properties.     

Multiple ligamentous injuries of the canine stifle joint: a study of 12 cases

Multiple ligamentous injuries of the canine stifle are uncommon. In this study, they affected mainly adult, male, working or sporting dogs and occurred secondary to severe trauma, or where chronic joint infection had weakened the supporting structures. Rupture of the cranial cruciate, caudal cruciate and lateral collateral ligaments was the most common injury observed and this occurred after catching the limb in a fence or gate. Reconstruction of the collateral and cranial cruciate ligaments, and careful repair of damaged menisci and joint capsule, was an effective method of treatment for medium- and large-size dogs. Reconstruction of the caudal cruciate ligament and postoperative limb support was not found to be essential. All dogs with subluxated stifles had good to excellent limb function with minimal loss of mid-thigh circumference or stifle joint range of motion at follow-up. Less favourable results were achieved where there was stifle joint luxation with extensive disruption to secondary joint restraints.     

Evaluation of computed tomographic anatomy of the equine metacarpophalangeal joint

OBJECTIVE: To determine the detailed computed tomography (CT) anatomy of the metacarpophalangeal (MCP) joint in healthy horses. SAMPLE POPULATION: 10 cadaveric forelimbs from 10 adult horses without orthopedic disease. PROCEDURES: CT of the MCP joint was performed on 4 forelimbs. In 1 of the limbs, CT was also performed after intra-articular injection of 30 mL of contrast medium (40 mg of iodine/mL). Transverse slices 1-mm thick were obtained, and sagittal and dorsal planes were reformatted with a slice thickness of 2 mm. The CT images were matched with corresponding anatomic slices from 6 additional forelimbs. RESULTS: The third metacarpal bone, proximal sesamoid bones, and proximal phalanx could be clearly visualized. Common digital extensor tendon; accessory digital extensor tendon; lateral digital extensor tendon; superficial digital flexor tendon (including manica flexoria); deep digital flexor tendon; branches of the suspensory ligament (including its attachment); extensor branches of the suspensory ligament; collateral ligaments; straight, oblique, and cruciate distal sesamoidean ligaments; intersesamoidean ligament; annular ligament; and joint capsule could be seen. Collateral sesamoidean ligaments and short distal sesamoidean ligaments could be localized but not at all times clearly identified, whereas the metacarpointersesamoidean ligament could not be identified. The cartilage of the MCP joint could be assessed on the postcontrast sequence. CONCLUSIONS AND CLINICAL RELEVANCE: CT of the equine MCP joint can be of great value when results of radiography and ultrasonography are inconclusive. Images obtained in this study may serve as reference for CT of the equine MCP joint.     

The Intercarpal Ligaments of the Equine Midcarpal Joint, Part 2: The Role of the Palmar Intercarpal Ligaments in the Restraint of Dorsal Displacement of the Proximal Row of Carpal Bones

Objective— To determine the relative contributions of the palmar intercarpal ligaments in the midcarpal joint to the restraint of dorsal displacement of the proximal row of carpal bones.
Study Design— A biomechanical study of cadaver equine carpi.
Animals or Sample Population— Eight equine forelimbs from six thoroughbred horses.
Methods— With joints in full extension, the radius was dorsally displaced while midcarpal joint displacement was measured. The restraining force at a joint displacement of 1.5 mm was determined from the load-displacement curve. A ligament or pair of ligaments was then cut and the testing procedure repeated. Their contribution to restraining force was calculated as the percentage change in restraining force after the ligament was sectioned. Relative cross-sectional areas of the ligaments tested were measured at the level of the midcarpal joint.
Results— The collateral ligaments were the major contributors to the restraint of dorsal displacement ( P <.001). In all joints, the palmar intercarpal ligaments contributed a greater proportion than the palmar carpal ligament (PCL) ( P <.05). The mean percentage (±SEM) contributions to the restraint of dorsal displacement were 62.8 ± 3.4 for the collateral ligaments, 14.5 ±1.4 for the PCL, and 22.7 ± 2.2 for the palmar intercarpal ligaments. Mean cross-sectional area expressed as a percentage (±SEM) of the total ligamentous area were 9.0 ± 0.3 for the palmar intercarpal ligaments, 27.1 ± 3.0 for the PCL, and 63.8 ± 2.8 for the collateral ligaments.
Conclusions— Despite the small size of the palmar intercarpal ligaments, they play an important role in the restraint of dorsal displacement of the proximal row of carpal bones.
Clinical Relevance— Interpretation, as well as prevention and treatment of intercarpal ligament tearing requires an understanding of their function.     

Lateral ligamentous injury to the carpus of a racing greyhound

The lateral collateral ligament of the ulna and the dorsolateral ligaments of the radiocarpal joint of a racing Greyhound were ruptured, resulting in instability of the carpus when the joint was flexed. This report describes a technique for making a ligament prosthesis, using the ulnaris lateralis tendon. Although the dog did not return to racing, the carpus was stable enough for general activity.     

Replacement of the Collateral Ligaments of the Canine Tarsocrural Joint: A Proposed Technique

A technique for replacement of the medial and lateral collateral ligaments of the tarsocrural joint in dogs was developed based on studies of normal anatomy and function. The medial or lateral tarsocrural joint was made unstable by removal of the respective malleolus, ligaments, and joint capsule; the component parts of the collateral ligaments were replaced using suture material to function as ligament prostheses. The technique was found to be effective in maintaining near normal joint motion and adequate joint stability in cadavers immediately following surgery, and in dogs observed for up to 39 months postoperatively. No degenerative joint disease was noted upon gross or radiographic examination.     

Craniocervical junction in dogs revisited--new ligaments and confirmed presence of enthesis fibrocartilage

The study was performed to investigate and to describe features of gross and microscopic morphology of craniocervical junction (CCJ) in dogs. Seventy mature dogs (38 females, 32 males) of different body weight, representing small, medium and large breeds of dolicho-, mesati-, and brachycephalic morphotype were dissected. Morphological details were localised using an operating microscope with integrated video channel. Occurrence and distribution of fibrocartilage in the ligaments from 10 dogs was analysed histologically. Three new pairs of ligaments were described and named: dorsal ligaments of atlas, cranial internal collateral ligaments of atlas, and caudal internal collateral ligaments of atlas. Several new findings in the course of the known ligaments were found relating to breed and body weight. For the first time enthesis fibrocartilage was identified in ligaments of CCJ in dogs. Sesamoidal fibrocartilage was identified in the transversal ligament of atlas in large dogs. The findings are discussed for clinical importance.     

COMPUTED TOMOGRAPHIC ARTHROGRAPHY OF THE NORMAL CANINE STIFLE

Computed tomographic (CT) imaging of eight normal cadaveric canine stifles was performed before and after intra-articular administration of iodinated contrast medium. Transverse CT images were reconstructed in dorsal, parasagittal, and oblique planes. The following ligamentous structures were identified on transverse CT images in all stifles: cranial cruciate ligament, caudal cruciate ligament, medial meniscus, lateral meniscus, and the medial and lateral collateral ligaments. The following ligamentous structures were identified on transverse computed tomographic arthrography (CTA) images in all stifles: cranial cruciate ligament, caudal cruciate ligament, medial meniscus, lateral meniscus, meniscofemoral ligament, cranial meniscotibial ligaments, caudal meniscotibial ligaments, intermeniscal (transverse) ligament, and the medial and lateral collateral ligaments. The patellar tendon was identified on transverse and reconstructed dorsal and sagittal CT and CTA images in all stifles. Multiplanar reconstructions enabled further evaluation of the continuity of the cranial and caudal cruciate ligaments and menisci. The medial and lateral collateral ligaments were not clearly identified on CT or CTA multiplanar reconstructed images.     

Correlative biomechanical and histologic study of the cranial cruciate ligament in dogs

The mechanical properties of the cranial cruciate ligament were determined, using unilateral bone-ligament-bone preparations from 65 dogs of various ages and body sizes. Tensile loading of the cranial cruciate ligament from 1 of each pair of stifle joints demonstrated a decrease in material properties (modulus, maximum stress, strain energy) with aging. The decreases in maximum stress and strain energy with age were significantly less (P less than 0.05 and P less than 0.05, respectively) in the cranial cruciate ligament from dogs weighing less than 15 kg, compared with those weighing 15 kg or more. The cranial cruciate ligament and remaining femorotibial ligaments were collected from the opposite stifle joints and examined microscopically. By 5 years of age, the cranial cruciate ligaments of dogs weighing greater than 15 kg consistently had microscopic evidence of degenerative disease (loss of ligamentocytes, metaplasia of surviving ligamentocytes to chondrocytes, and failure to maintain collagen fibers and primary collagen bundles) which progressed in severity with age. The caudal cruciate ligaments were similarly affected, although the degenerative changes were rarely as severe as in the cranial cruciate ligament. The collateral ligaments underwent minimal degeneration. Sex differences had no bearing on degeneration. The cranial cruciate ligaments in dogs weighing less than 15 kg generally had less severe alterations than those in heavier dogs, and the onset of the degenerative process was delayed by several years. Cranial cruciate ligaments removed from dogs after ligament failure not only had degenerative disease, but also had undergone unsuccessful attempts at repair. In contrast, fibrous repair was rarely present in intact ligaments of asymptomatic dogs with degenerative disease of the cranial cruciate ligament.     

The jump behavior of the humeroradial and tarsocrural joints of the horse

Osteoligamentous preparations of the elbow and hock joints of the horse show “jump” behavior when flexed and extended. This behavior is not seen in undissected anatomical specimens or in the live horse. The hypothesis is that energy is stored in the collateral ligaments during the middle range of joint displacement and quickly released nearing full flexion or extension. This energy storage mechanism has the attribute of negative work. In the undissected specimen and the live horse energy is stored in muscles and tendons as well as in the collateral ligaments, and the obvious jump phenomenon is not observed although the principle of negative work still pertains.     

Ultrasonography of the Collateral Ligaments of the Distal Interphalangeal Joint in Horses: Technique and Reference Images

This study describes ultrasound (US) technique and reference images of the equine distal interphalangeal joint collateral ligaments (CLs), and evaluates the portion of the CLs assessable by US in a series of normal forelimbs. Transverse and longitudinal US images were obtained on five healthy horses and on 25 equine cadaver forelimbs. On six limbs, a needle was placed under US-guidance at the distal limit of visualization of each CL, and the portion of CL visible at US was evaluated on computed tomographic (CT) images. The normal CLs appear as oval structures located abaxial to the fossae of the middle phalanx in the transverse sections, obtained at the level of the coronary band. A centrodorsal hypoechoic image appears with increasing proximodistal probe inclination, demonstrating different fiber orientations within the ligament. Two main fascicles, a deep and a superficial, distally divergent, are visible on longitudinal images obtained in the central part of the ligament. The proportion of CL visible at US examination was more than 50% of the total ligament length in nine of the 12 CLs assessed by CT. Awareness of the estimated portion of distal interphalangeal joint CLs visible at US and detailed knowledge of the US technique and CLs morphology are essential to efficiently use US examination on clinical cases.     

FEASIBILITY FOR ULTRASOUND‐GUIDED INJECTION OF THE COLLATERAL LIGAMENTS OF THE DISTAL INTERPHALANGEAL JOINT IN HORSES

Desmitis of the collateral ligament of the distal interphalangeal joint is a cause of lameness in performance horses. The objective of this prospective, experimental, ex vivo feasibility study was to evaluate the success of ultrasound‐guided injection of the collateral ligaments of the distal interphalangeal joint in the equine forelimb. Seventy‐six ultrasound‐guided dye injections of the collateral ligament of the distal interphalangeal joint were performed on horses’ cadaver limbs. The hooves were sectioned transversely to verify the location of the dye relative to the collateral ligaments and surrounding structures. Evaluations of transverse sections were performed independently by two experienced observers. A scoring system was used to assess injection of the collateral ligament of the distal interphalangeal joint at the proximal, middle, and distal aspect over the length of the ligament. The collateral ligament was injected at any point in 97.4% of cases. The ligament was injected over the entire scored length in 43.2% of cases (32/74), over two scored length areas in 45.9% of cases (34/74), and in one area in 10.8% of cases (8/74). The distal interphalangeal joint and the common digital extensor tendon were also injected in 81.6% (62/76) and 43.4% (33/76) of the cases, respectively. Use of the ultrasound had a positive and negative predictive value of 98% and 9%, respectively. In this study, ultrasound guidance was useful for confirming injection of the collateral ligament of the distal interphalangeal joint but did not prevent injecting the distal interphalangeal joint and the common digital extensor tendon.     

Risk of intra‐articular injection with longitudinal ultrasound‐guided injection of collateral ligaments of the equine distal interphalangeal joint

Desmopathy of the collateral ligaments of the distal interphalangeal joint is a common cause of equine foot lameness and carries a poor prognosis with conservative management. Intralesional injections may improve healing, although accuracy of radiographically guided injections is significantly less than when guided by MRI, which requires special needles. Longitudinal ultrasound‐guided injection of the distal collateral ligament has not been evaluated objectively. In this prospective, anatomic study, seven equine cadaver limbs (14 collateral ligaments) were injected with methylene blue dye and radiographic contrast medium using ultrasound to guide the needle longitudinally into the collateral ligaments until contacting bone. The insertion site of the needle proximal to the coronary band was measured on the limb and the needles left in place for radiography and CT to evaluate the needle angulation, location of the contrast medium, and whether the contrast entered the distal interphalangeal joint. The limbs were frozen and sectioned with a band saw to identify the location of the dye. Fifty percentage of injections were in or around the collateral ligaments. However, the percentage of “successful” injections, defined as in the collateral ligament but not in the joint, was only 36%. All legs had dye and contrast in the joint after both ligaments had been injected. There were no significant differences between the needle angle and entry site for “successful” and “unsuccessful” injections. Findings from this study indicates that the success rate is low for injecting the distal portions of the distal interphalangeal joint collateral ligaments using ultrasound guidance alone.     

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.     

Elbow joint luxation in a 1-month-old foal

This paper reports on luxation of the elbow joint without concomitant fracture in a 1-month-old foal. Conservative treatment, with closed reduction and full-limb bandaging, including caudal and lateral splints, seemed successful initially, however, failed to provide enough stability and luxation recurred, and open reduction and surgical placement of prosthetic collateral ligaments was required. Luxation of the elbow joint should be considered when acute non-weight bearing forelimb lameness occurs associated with pain and swelling in the area of the elbow in young foals. Closed reduction failed to provide sufficient joint stability.