Scapulohumeral arthrodesis in miniature horses

OBJECTIVES: To describe surgical arthrodesis of the scapulohumeral joint and to evaluate its efficacy in reducing morbidity associated with severe shoulder dysfunction in miniature horses. STUDY DESIGN: Retrospective study. ANIMALS: Four miniature horses. METHODS: Medical records and radiographs were reviewed for history, physical examination findings, lameness evaluation, radiographic evaluation, surgical techniques, postoperative complications, and outcome. A 10- or 11-hole, 4.5-mm narrow dynamic compression plate and 4.5-mm cortical screws were applied to the cranial surface of the scapula and cranial surface of the humerus after osteotomy of the intermediate tubercle. In most horses, 1 or 2 screws were inserted in lag fashion across the joint, through holes in the plate. RESULTS: Scapulohumeral osteoarthritis was diagnosed radiographically in 4 horses, and 3 horses had concurrent shoulder luxation or subluxation. All horses had grade 3 or 4 lameness before surgery, and most improved by 1 to 2 grades after surgery. Despite complications of implant failure (2 horses), infection (2 horses), scapular fracture (1 horse), and atrophy of the shoulder muscles (1 horse), functional arthrodesis reduced morbidity in all horses. CONCLUSIONS: Scapulohumeral arthrodesis facilitates early return to weight bearing in miniature horses with severe scapulohumeral joint osteoarthrosis. Despite functional gait abnormality, the horses ambulated quite well after surgery. CLINICAL RELEVANCE: Scapulohumeral arthrodesis should be considered for debilitating conditions of the shoulder joint in miniature horses, especially when the intended outcome is breeding or pasture soundness.     

The effects of lifetime food restriction on the development of osteoarthritis in the canine shoulder

Objective— To report effects of age and lifetime food restriction on development and progression of shoulder joint osteoarthritis (OA) in Labrador retriever dogs.
Study Design— Longitudinal life-span, cohort study.
Animals— Labrador retriever dogs (n=48).
Methods— Littermates were paired (gender, weight) to make 24 pairs of genetically similar dogs. Each diet-restricted (DR) pair-mate was fed daily 75% of the same diet consumed by its control-fed (CF) pair-mate for life. Shoulders were evaluated radiographically at years 6, 8, and end of life (EOL). At EOL shoulders were evaluated grossly and by histopathology for OA.
Results— Radiographic evidence of shoulder OA was identified in 78% of dogs. Severity of radiographic shoulder OA at 6 ( P <.03) and 8 years ( P <.02) was significantly lower among DR dogs compared with CF dogs. Pooled gross evaluation results revealed 40 of 46 dogs had cartilage erosion on the caudal aspect of the humeral head. By EOL, 91% of dogs had histopathologic changes consistent with OA.
Conclusion— There was a high overall prevalence of radiographic, gross, and histologic OA among dogs. Substantial disparity was found between radiographic evidence of OA (at EOL) and characteristic changes visible by gross and histologic examination.
Clinical Relevance— Radiographic evaluation correlates poorly with severity of shoulder joint pathology. The benefits of DR on shoulder OA are consistent with the demonstrated effect of DR in delaying species- and strain-specific diseases of aging.     

Role of the tendons of the biceps brachii and infraspinatus muscles and the medial glenohumeral ligament in the maintenance of passive shoulder joint stability in dogs

OBJECTIVE: To objectively evaluate the effect of transecting the tendon of the biceps brachii muscle (BBT), tendon of the infraspinatus muscle (IFS), or medial glenohumeral ligament (MGHL) on shoulder joint stability in canine cadavers. SAMPLE POPULATION: 81 forelimbs from mature dogs. PROCEDURE: Cadaver forelimbs were placed in a testing frame and axially preloaded with 4 kg of weight. Shoulder joint stability was tested in neutral joint position, flexion, and extension before and after transection of the BBT (n = 37), IFS (37), or MGHL (7). Humeral translation relative to the glenoid was induced by applying a 3-kg load in each of 3 directions (cranial, lateral, and medial) and quantitatively measured by use of an electromagnetic motion tracking system. Peak translational data were compared in each joint position before and after transection of the BBT, IFS, or MGHL. RESULTS: When tested in neutral position, the cranial, lateral, and medial translation of the humerus was significantly increased after BBT transection. In the flexed position, translation of the humerus in the cranial and lateral directions was significantly increased after BBT transection. In the extended position, the medial translation of the humerus was significantly increased after BBT transection. Complete medial luxation of all humeral heads occurred following transection of the MGHL. CONCLUSIONS AND CLINICAL RELEVANCE: The BBT contributes to passive shoulder joint stability in dogs, particularly in the neutral and flexed positions. It also provides medial stability during shoulder joint extension. Complete luxation of the joint occurs when the MGHL is transected.     

COMPUTED TOMOGRAPHY AND POSITIVE CONTRAST COMPUTED TOMOGRAPHIC ARTHROGRAPHY OF THE CANINE SHOULDER: NORMAL ANATOMY AND EFFECTS OF LIMB POSITION ON VISIBILITY OF SOFT TISSUE STRUCTURES

Soft tissue injuries of the shoulder are an important cause of forelimb lameness in dogs. The objectives of this canine cadaver study were to describe normal anatomy of shoulder soft tissue structures using computed tomography (CT) and computed tomographic arthrography (CTA) and to determine the effects of positioning on visualization of shoulder soft tissue structures. Thirteen forelimbs were removed from eight canine cadavers. Two forelimbs were used for contrast dose optimization. For the remaining 11 forelimbs, shoulder CT and CTA were performed using three defined joint angles (140°, 90°, and 70°). For three forelimbs, CT and CTA images were compared with frozen anatomic sections to describe normal anatomy. Ten forelimbs were used for analysis of positioning effects. Soft tissue structures evaluated were the joint capsule, cartilage, ligaments, tendons, and muscles. A visual assessment score was assigned to each structure using a consensus of two observers. The range and mode of scores were calculated and compared for each modality and limb position. The shoulder joint capsule and medial and lateral glenohumeral ligaments were completely visible with CTA. All tendons and muscles were visualized in all the examinations except for the teres minor muscle tendon and the coracobrachialis muscle, which were not visible on all scans. Positioning the limb in an extended position significantly improved visualization of most soft tissue shoulder structures. Shoulder cartilage was best seen with CTA and with neutral or flexed positioning of the shoulder. Findings indicated that both CT and CTA are feasible imaging techniques for visualization of soft tissue structures of the canine shoulder.     

Prospective evaluation of techniques for differentiating shoulder pathology as a source of forelimb lameness in medium and large breed dogs

Objective— To assess lameness evaluation, shoulder abduction angles, radiography, and ultrasonography for determining presence, location, and severity of forelimb pathology. Study Design— Prospective cohort study. Animals— Dogs ≥20 kg (n=30). Methods— Each dog was assigned lameness scores. Shoulder abduction angles were determined. Radiographs of shoulders and elbows were subjectively graded for pathology. One investigator unaware of dog history (lameness, radiographic findings) performed ultrasonographic assessment of shoulders with subjective grading of pathology. Another investigator unaware of dog history (lameness, radiographic, ultrasonographic findings) performed arthroscopic assessment of shoulders with subjective grading of pathology. Elbows were disarticulated and evaluated for gross pathology. Histologic pathology scoring of shoulder tissues was performed. Data were compared for differences among groups, sensitivities, specificities, positive and negative predictive values, and positive and negative likelihood ratios were calculated. Results— Twenty‐seven forelimbs were considered clinically normal, 26 had shoulder pathology, 5 had elbow pathology, and 2 had pathology of both the shoulder and elbow. Dogs with shoulder pathology were twice as likely to be lame compared with dogs with elbow pathology. Limbs with medial shoulder instability had significantly higher abduction angles than normal limbs and those with elbow pathology. Radiographs were clinically useful for diagnosing elbow, but not shoulder, pathology. Ultrasonography was clinically useful for diagnosing shoulder pathology other than instability. Abduction angles, ultrasonographic evaluation, and arthroscopic assessments had strong, significant correlations with reference standards. Conclusions— Clinically relevant diagnostic techniques yielded characteristic, repeatable differences in objective and subjective assessments for distinguishing presence, location, and severity of forelimb lameness in dogs. Clinical Relevance— The diagnostic approach to forelimb lameness in dogs should include shoulder pathology as a differential with multiple assessments used to determine the clinical cause of lameness.     

Evaluation of the passive function of the biceps brachii muscle-tendon unit in limitation of shoulder and elbow joint ranges of motion in horses

OBJECTIVE: To quantify the passive contribution of the biceps brachii muscle-tendon unit to the limits of elbow joint extension during shoulder joint flexion in horses. SAMPLE POPULATION: Normal right forelimb specimens from 6 Thoroughbred cadavers. PROCEDURE: Specimens included the scapula, humerus, radius-ulna, biceps brachii muscle-tendon unit, and stabilizers of the shoulder and elbow joints. Specimens were mounted to a rigid board by transfixation pins through the humerus and instrumented for mechanical manipulation of the limb and joint angle and load measurements. Flexion and extension limits of shoulder and elbow joint ranges of motion were measured in each joint separately, while the other joint was fixed. Measurements were made before and after transection of the biceps brachii muscle-tendon unit. RESULTS: The biceps brachii muscle-tendon unit limited elbow joint extension when the shoulder joint was fixed in flexion, limited shoulder joint flexion when the elbow joint was fixed in extension, and inhibited shoulder joint extension to a lesser degree when the elbow joint was fixed at midrange angles of 75 degrees to 90 degrees. CONCLUSIONS AND CLINICAL RELEVANCE: Clinical manipulation of the elbow joint into hyperextension during shoulder joint flexion is indicative of biceps brachii injury.     

A technique for internal fixation of scapulohumeral luxation using scapulohumeral tension sutures in three alpacas and one miniature steer

Objective— To report a technique for open reduction and internal fixation of scapulohumeral joint luxation in large animals, and outcome.
Study Design— Clinical case reports.
Animals— Mature alpacas (n=3) and immature miniature steer (1).
Methods— Shoulder joint luxation was diagnosed by physical examination and confirmed by radiography. Open reduction was performed with internal fixation using lateral tension band sutures.
Results— Animals maintained shoulder joint reduction and were sound with radiographically normal shoulder joints (n=2) and normal range of motion without appreciable gait abnormalities (4) at follow-up 8–36 months later.
Conclusions— In contrast to previous reports of open reduction with internal fixation of shoulder joint luxation in large animals, open reduction and use of lateral scapulohumeral tension sutures resulted in functionally normal shoulder joints.
Clinical Relevance— Stabilization of the shoulder joint with lateral scapulohumeral tension sutures after open reduction is effective, technically simple, and should be considered in large animal species weighing <100 kg.     

Neck and shoulder motion of the gallop stride

The motion patterns of the neck and shoulders during the gallop stride were documented using high-speed cinematography. The gallop stride characteristics of 4 Quarter Horse fillies, approximately 30 months of age, were used as a model. Horses were housed and fed together and received the same amount and type of limited training; and were all ridden with the same tack and by the same person. Both sides of each horse were filmed simultaneously (243 frames/sec) while galloping individually along a 1.5-m-wide track. Kinematic variables describing 29 strides (mean velocity 13.1 m/sec, stride frequency 2.6 strides/sec, stride length 5.1 m) included linear and temporal measurements of the maximum and minimum heights of the wing of the atlas, spine of the scapula, shoulder joint and elbow joint; maximum and minimum angles with respect to the horizon of the neck, shoulder and arm segments; and maximum and minimum relative angles between the neck and shoulder, and shoulder and arm segments. Differences (P<.05) between the leading and trailing sides of the body were identified for 12 of a total of 27 spatial measurements reported for the neck, shoulder and arm, including minimum height of the scapula spine, maximum height of the scapula spine and elbow joint, maximum absolute angle of the shoulder segment, and minimum angle between neck and shoulder segments. Of 18 temporal measurements reported involving the neck, shoulder and arm, 14 differed (P<.05) between leading and trailing sides. Kinematic events describing the motion of the leading and trailing shoulder and arm segments were ordered and tabulated in the temporal sequence of the normal gallop stride. Results indicated that the motion patterns of the shoulder and arm segments were highly specific to the leading and trailing sides of the body in the equine gallop stride. The work required for vertical displacement of the center of mass in galloping was estimated to be approximately 98,500 J/km or 23.5 kcal/km; equivalent to approximately 6 percent of the total energy expenditure for galloping 1 km.     

Evaluation of anticollagen type I antibody titers in synovial fluid of both stifle joints and the left shoulder joint of dogs with unilateral cranial cruciate disease

OBJECTIVE: To evaluate anticollagen type I antibodies in synovial fluid of the affected stifle joint, the contralateral stifle joint, and the left shoulder joint of dogs with unilateral cranial cruciate ligament (CrCL) rupture during an extended period of 12 to 18 months. ANIMALS: 13 client-owned dogs with CrCL rupture and 2 sham-operated dogs. PROCEDURES: All dogs were examined and arthrocentesis of all 3 joints was performed every 6 months after surgery. Synovial fluid samples were tested for anticollagen type I antibodies by use of an ELISA. RESULTS: Dogs with partial CrCL rupture had higher antibody titers than dogs with complete rupture. Six of 13 dogs ruptured the contralateral CrCL during the study, whereby higher antibody titers were found for the stifle joints than for the shoulder joint. Seronegative dogs or dogs with extremely low antibody titers and 2 dogs with high antibody titers did not sustain a CrCL rupture in the contralateral stifle joint. CONCLUSIONS AND CLINICAL RELEVANCE: In most dogs that had a CrCL rupture of the contralateral stifle joint, a distinct antibody titer gradient toward the stifle joints was detected, suggesting that there was a local inflammatory process in these joints. However, only a small number of sham-operated dogs were used to calculate the cutoff values used to determine the anticollagen type I antibody titers in these patients. Synovial fluid antibodies against collagen type I alone do not initiate CrCL rupture because not all dogs with high antibody titers sustained a CrCL rupture in the contralateral stifle joint.     

Diagnostic and Surgical Arthroscopy of the Equine Shoulder Joint

An arthroscopic technique for examination and surgical treatment of conditions of the shoulder joint was evaluated in eight normal horses and two horses with osteochondrosis lesions. A single arthroscope entry point caudal to the infraspinatus tendon allowed inspection of the cranial, lateral, and caudal surfaces of the shoulder joint. With the humeral head and glenoid cavity distracted by a curved forceps, the entire cartilage surface of the shoulder could be examined. The caudomedial portion of the humeral head was seen better with a 70 degree angled arthroscope. Instruments for intra-articular manipulation were introduced through a separate skin incision 2 to 4 cm caudal to the arthroscope entry point. Two horses with osteochondrosis lesions of the shoulder were examined arthroscopically and debrided with instrument triangulation. Five normal horses and both horses with osteochondrosis lesions were euthanized immediately after the procedure and a necropsy was performed. Minor iatrogenic damage to the cartilage surfaces and joint capsule resulted from the technique. Three horses recovered from anesthesia and were killed 3, 30, or 60 days after surgery. Subcutaneous fluid that accumulated during surgery had resorbed by 3 days and lameness was evident for 12 to 24 hours. Gross examination and histopathologic findings of specimens collected at 30 and 60 days showed several small nonhealing partial-thickness cartilage defects attributed to instrument insertion. Arthroscopy is a satisfactory method to examine the joint surfaces and to evaluate and treat osteochondrosis lesions of the shoulder joint in horses.     

Nutritional management of gastrointestinal disease

The gastrointestinal (GI) tract is primarily responsible for acquiring and digesting food, absorbing nutrients and water, and expelling wastes from the body as feces. A proper diet and normally functioning GI tract are integral for the delivery of nutrients, prevention of nutrient deficiencies and malnutrition, repair of damaged intestinal epithelium, restoration of normal luminal bacterial populations, promotion of normal GI motility, and maintenance of normal immune functions (eg, both tolerance and protection from pathogens). The amount of food, its form, the frequency of feeding, and the composition of diet each have important effects on GI function and may be used to help ameliorate signs of GI disease. Although both nutrients and nonnutritional components of a diet are important to GI health, they also may cause or influence the development of GI pathology (eg, antibiotic responsive diarrhea, inflammatory bowel disease, dietary intolerance, or sensitivity and/or allergy). The appropriate diet may have a profound effect on intestinal recovery and successful management of chronic or severe GI disease.     

Computed tomographic arthrography is a useful adjunct to survey computed tomography and arthroscopic evaluation of the canine shoulder joint

The aim of this retrospective, methods comparison study was to assess the diagnostic utility of computed tomographic arthrography in the assessment of various intraarticular shoulder pathologies in dogs in comparison with survey computed tomography (CT), using arthroscopic examination as the reference standard. Computed tomography, computed tomographic arthrography, and arthroscopic findings of 46 scapulohumeral joints of dogs with forelimb lameness were reviewed retrospectively. Predefined sites were assessed for the presence or absence of disease. If a lesion was present, a prespecified pathology was designated. Computed tomographic arthrography was found to be a safe technique which provided a superior diagnostic efficacy relative to survey CT for the assessment of the biceps tendon and biceps tendon sheath (sensitivity 71%, specificity 75%, positive likelihood ratio 2.9, negative likelihood ratio 0.38) and humeral head cartilage (sensitivity 65%, specificity 97%, positive likelihood ratio 19, negative likelihood ratio 0.37). Computed tomography and computed tomographic arthrography provided additional diagnostic information to arthroscopy in regard to osteophytosis, subchondral defects, and joint mice. Computed tomographic arthrography alone was of limited diagnostic value for assessment of the medial and lateral glenohumeral ligaments (sensitivity 13% and 0%, specificity 1% and 78%, positive likelihood ratios unmeasurable and 0, negative likelihood ratios 0.88 and 1.29, respectively) and the subscapularis tendon (sensitivity 14%, specificity 98%, positive likelihood ratio 5.7, negative likelihood ratio 0.88). Computed tomographic arthrography is therefore a useful adjunct to survey CT and arthroscopic evaluation of the canine shoulder joint, however, is not a replacement for these techniques.     

Does temporomandibular joint pathology affect performance in an equine athlete?

Temporomandibular joint (TMJ) pathology is a rarely reported cause of decreased performance among equine athletes or at least seldom recognised. This case report describes the work‐up of a high level dressage horse with decreased performance. Temporomandibular joint pathology was suspected based on computed tomography (CT) and the horse responded very well to joint treatment.     

Ultrasonography of the canine shoulder joint and its pathological changes

The objective of this study was to present and discuss the available data on canine shoulder joint ultrasonography. The paper presents the method of ultrasonographic examination of the shoulder joint area, describes the normal structure of the shoulder joint in dogs, and discusses the most frequently encountered shoulder joint pathologies.     

Diagnostic findings and prognosis following arthroscopic treatment of subtle osteochondral lesions in the shoulder joint of horses: 15 cases (1996-1999)

OBJECTIVE: To determine clinical, scintigraphic, radiographic, and arthroscopic findings and results of treatment in horses with lameness attributable to subtle osteochondral lesions of the shoulder joint. DESIGN: Retrospective study. ANIMALS: 15 horses. PROCEDURE: Medical records were reviewed, and results of physical examination, scintigraphy, radiography, arthroscopy, and treatment were recorded. RESULTS: Severity of lameness ranged from grade 1 to 4. Response to shoulder flexion or extension was variable. Twelve horses had a narrow upright foot. Intra-articular anesthesia of the shoulder joint localized the cause of the lameness to the shoulder joint in 9 of 10 horses. Scintigraphic abnormalities were detected in 4 of 6 horses. Radiographic lesions were subtle and included glenoid sclerosis, focal glenoid lysis, small glenoid cysts, and alterations in the humeral head contour. Arthroscopic evaluation confirmed clefts in the glenoid cartilage, glenoid cysts, a humeral head cyst, fibrillation of the humeral head cartilage, cartilage fragmentation, or a nondisplaced fracture of the humeral head. After treatment, 12 horses returned to their previous level of performance, 1 was sound for light riding, 1 remained lame, and 1 was euthanatized because of chronic lameness. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a combination of physical examination, scintigraphy, and radiography is necessary to diagnose subtle osteochondral lesions of the shoulder joint in horses. Arthroscopy can be used to confirm the diagnosis and treat cartilage and subchondral bone lesions. Young and middle-aged horses with subtle osteochondral lesions of the shoulder joints have a good prognosis for return to performance following arthroscopic treatment.     

Magnetic Resonance Imaging Findings in Dogs with Confirmed Shoulder Pathology

Objective— To evaluate the diagnostic potential of magnetic resonance imaging (MRI) compared with a reference standard, arthroscopic and/or open surgery, in dogs with soft tissue shoulder pathology. Study Design— Retrospective study. Animals— Dogs (n=21). Methods— Magnetic resonance (MR) images were retrospectively evaluated in 21 dogs that had surgically identified soft tissue shoulder pathology. The musculotendinous units of the biceps, infraspinatus, teres minor, supraspinatus, subscapularis, and the medial and lateral glenohumeral ligaments (MGHL and LGHL) were graded as either normal or abnormal. Abnormal structures were further classified as being either inflamed, partially torn, or fully torn. Impingement of the biceps tendon was also evaluated. Results were reported in terms of agreement and concordance between MRI findings and surgical findings. Agreement was defined as the percentage of times MRI findings concurred with surgical findings with respect to a structure being either normal or abnormal. Concordance was defined as the percentage of times MRI concurred with the exact surgically assessed pathology when abnormality was identified. Results— The findings were biceps tendon: 90% agreement with 100% concordance; subscapularis: 95% agreement with 62% concordance; MGHL: 84% agreement with 83% concordance; LGHL: 88% agreement with 100% concordance; infraspinatus: 100% both agreement and concordance; biceps tendon impingement: 90% agreement with 100% concordance. Conclusions— Soft tissue abnormalities of the canine shoulder were readily identified on preoperative MR images. Clinical Relevance— MRI shows great potential as a diagnostic tool in the evaluation of canine shoulder disease.     

Relationship of physical examination test of shoulder instability to arthroscopic findings in dogs

Objective— To determine the diagnostic validity of commonly used physical examination maneuvers for shoulder instability.
Study Design— Retrospective study.
Animals— Dogs (n=24) referred for shoulder arthroscopy.
Methods— Results of physical maneuvers and arthroscopic findings were recorded and sensitivity, specificity, positive likelihood ratios (LR+), and negative likelihood ratios (LR−) were calculated for each of 4 physical examination test findings for arthroscopic changes in the medial, lateral, cranial, or caudal compartments of the shoulder joint viewed in dorsal recumbency by lateral and craniomedial portals.
Results— Distribution of compartment changes was: medial (17 dogs), caudal (15), cranial (12), and lateral (5). The biceps test had a moderate effect (LR+=9) on post-test probability of cranial compartment changes and a small effect on post-test probability of lateral and caudal compartment changes (LR+=3 and 2.4, respectively). Hyperabduction had a minimal effect and mediolateral instability test had a small effect (LR+=1.64 and 2.68, respectively) on post-test probability of medial compartment changes. Craniocaudal instability test had little to no effect on post-test probability of changes in any compartment.
Conclusions— Physical examination tests evaluated were limited in their ability to predict the type of arthroscopic pathology in this study population.
Clinical Relevance — Clinicians should understand that a diagnostic test performs inconsistently based on prevalence of a condition in a given patient population. The use of likelihood ratios can assist clinicians in determining the probability of intraarticular changes from a group with a differing prevalence than the patient population presented.