Elbow and Shoulder



Elbow and Shoulder


Brad B. Nelson and Laurie R. Goodrich



Anatomy


The elbow joint is composed of the articulation between the distal humerus and the proximal radius and ulna. The joint undergoes a large range of motion; however, due to the soft tissue attachments and bone articulation, joint movement is restricted to the sagittal plane.1,2 The humeral epicondyles articulate with the proximal aspect of the radius. Between the epicondyles is the olecranon fossa where the anconeal process from the olecranon interdigitates with the distal humerus. The olecranon tapers distally until it fuses (with maturity) with the caudal aspect of the radius. There is an intraosseus space that remains in the proximal portion of the antebrachium between the radius and ulna.1 The collateral ligaments are present medially and laterally to prevent movement in the frontal plane. The medial collateral ligament is divided into the long, superficial portion and short, deep portion. The medial collateral ligament is also covered by the transverse pectoral muscle making palpation of this ligament more difficult than the lateral collateral ligament.1 The muscles that aid in flexion of the joint consist of the biceps brachii and brachialis. The extensor muscles consist mostly of the triceps, but the tensor fasciae antebrachii and anconeus also have some importance for extending the elbow. The attachment of the triceps muscle group to the olecranon is the main source for extension of the elbow joint.1


Diagnosis of elbow disease is uncommon in the equine athlete, but can be due to developmental, traumatic, infectious, or non-septic inflammatory causes. Other causes of elbow lameness can be due to damage of the ligament and tendons in the region.3


The best approach to diagnosing elbow disease is with intra-articular blocks with 2% mepivicaine (See Chapter 13). The elbow joint can be anesthetized with the lateral, caudolateral, or caudal approaches. If the lateral approach is chosen and the needle inserted cranial to the lateral collateral ligament, verification of the needle within the joint should be confirmed as peri-articular deposition of the anesthetic has resulted in radial nerve paralysis.4 Treatment for radial nerve paralysis is described later in this chapter. The lameness rarely resolves completely following the block but can improve to greater than 80%.3 Flexion tests can be performed on the elbow by advancing the leg forward; this action simultaneously extends the shoulder joint.3,5 These flexion tests may be hard to interpret as some horses may resent this test and are negative for elbow disease.


Radiographic examination of the elbow can be performed easily and can help evaluate for osteoarthritis, fractures, or osteochondrosis. Ultrasound can be helpful in visualizing the collateral ligaments and other surrounding soft tissue structures. Arthroscopic approaches of the elbow joint are well described, but its clinical usefulness is limited. Stress fractures may be visible radiographically, but may require nuclear scintigraphy in certain cases.



Ulnar/olecranon fractures






Recognition




Physical examination

Clinical signs in horses with olecranon fractures may show a dropped elbow appearance, which is due to the lack of effective triceps function as this muscle attachment is to the fractured olecranon.6 This dropped elbow appearance occurs with displaced or unstable fractures. These horses may display swelling around or near the point of the elbow and may be sensitive to palpation in this area depending upon the degree and configuration of the fracture.3 Contrary to other horses with a dropped elbow appearance, such as those with complete humeral fractures or radial neuropathy, these horses may be able to bear weight on the limb (minimally displaced fractures). An open wound may also accompany these fractures, which may communicate with the elbow joint.



Special examination

Latero-medial and cranio-caudal radiographic projections are recommended to assess the fracture configuration and to determine if there is an articular component. Once the fracture is identified, it can be classified. There have been different grading schemes reported, but the authors use the one described below.7






Treatment and prognosis




Therapy

First aid to stabilize the fracture is indicated in cases where the horse is unable to bear weight on the limb. The leg should be bandaged and a full limb caudal splint from elbow to fetlock should be applied to lock the carpus in extension. Local wounds in open fractures should be clipped of hair and cleaned. Many of these horses become more comfortable with the splint applied. Displaced and articular fractures warrant internal fixation to restore the joint surface. Locking or Dynamic Compression Plates are typically used to repair these fractures.8–10 Articular fractures that are not displaced have the potential to be treated conservatively. Non-displaced and non-articular fractures are typically treated conservatively with rest, but should frequently be re-evaluated to ensure the fracture has not become displaced.







Radial fractures






Recognition



History and presenting complaint

Horses typically present following a history of direct trauma or acute, severe lameness. The severity of lameness will depend upon the degree of displacement of the fracture.3,5,15 Complete, displaced fractures will result in a non-weight bearing lameness. A wound over the radius may be present and is commonly on the medial aspect of the limb due to decreased soft tissue coverage in this area.



Physical examination

Clinical signs in horses with radial fractures will depend upon the degree of displacement and can range from a walking lameness to non-weight bearing. In horses with displaced fractures, attempts at weight bearing usually result in deviation of the limb and many will stand with their carpus and fetlock joints flexed and the toe dragging. Most horses will have significant swelling over the site of fracture. Affected horses may also have a visible deviation in the limb or palpable crepitance. Since there is minimal soft tissue covering over the radius many of these fractures have an associated wound medially. Non-displaced or minimally displaced fractures can be harder to diagnose as horses will be severely lame, but palpable swelling, crepitus, or a wound may not be present to point the examiner to the radius.15




Diagnostic confirmation

Standard latero-medial and cranio-caudal radiographic views are the minimum required to evaluate the fracture, but oblique views and stress views may provide valuable information. Stress fractures or incomplete radial fractures can be diagnosed with radiography or nuclear scintigraphy. Trauma to the radius can also result in sequestration or osteomyelitis, which can be suspected with radiography and/or scintigraphy.16 Computed tomography may be beneficial to fully characterize the fracture in foals with radial fractures, but the gantry size in most computed tomography scanners does not typically allow imaging of this area in the adult patient. Furthermore, since scanning requires general anesthesia substantial risk is encountered during anesthetic recovery unless the fracture is repaired with internal fixation. High-resolution ultrasound may be beneficial in locating breaks within the periosteum; however, the methods mentioned above are preferred.



Treatment and prognosis




Therapy

First aid therapy in displaced open fractures is to clip the open wound and thoroughly clean the area with dilute saline solution. Foreign material should be removed from the area and the leg should be bandaged to prevent further contamination. This is with a heavy bandage with a lateral splint that extends from the ground up to the withers and a caudal splint that extends from the ground to the olecranon.


In horses with non-displaced or incomplete fractures, conservative therapy is recommended. This entails strict stall confinement and cross-ties to prevent the horse from laying down. Horses that have incomplete fractures that are not cross tied have the potential of causing further displacement or propagation of the fracture due to the stresses placed on the limb when attempting to stand. This stall confinement is recommended for 3–4 months prior to attempting short handwalks with periodic radiographic assessment of fracture healing.3 In cases that are not amenable to conservative management (displaced fractures), internal fixation with bone plates is required. Involvement of the fracture line into the elbow joint or a wound communicating with the joint must be ruled out to treat the horse conservatively.16 Sequestration requires removal of the fragment. Osteomyelitis requires long-term antimicrobial therapy.





Septic elbow arthritis






Recognition








Treatment and prognosis




Therapy

Removal of inflammatory cells and fibrin can be accomplished with lavage of the elbow joint under general anesthesia. Through-and-through needle lavage can remove the source of infection and inflammatory mediators; however, advanced cases or those with gross contamination are better treated with arthroscopic lavage. Arthroscopic lavage not only provides a larger bore flush and facilitates removal of fibrin, but also provides a diagnostic view of the elbow joint. The horse should also be placed on systemic antibiotics and anti-inflammatory medications post-operatively.5,18






Osteoarthritis of the elbow joint






Recognition








Treatment and prognosis




Therapy

Therapies to treat osteoarthritis include: intra-articular corticosteroids, hyaluronan, polysulfated glycosaminoglycans or IRAP (see Chapter 23). Systemic joint therapies such as NSAIDs, hyaluronan, and polysulfated glycosaminoglycans can also be explored for treatment. Numerous oral supplements are available to reduce inflammation, but the authors typically only recommend those that have undergone testing such as glucosamine and chondroitin sulfate, specifically brands such as Cosequin® ASU (Nutramax® Laboratories, Inc Edgewood, MD, USA) as they have been tested for their contents and studied in clinical trials. Significant disease modifying effects have not been demonstrated in horses although anectodal evidence of efficacy abounds. Topical medications such as 1% diclofenac sodium (Surpass® Boehringer Ingelheim Vetmedica, Inc. St. Joseph, MO, USA) has proven to have disease modifying effects in carpal joints with osteoarthritis and as such are frequently recommended to treat other joints with osteoarthritis.19







Olecranon bursitis






Recognition








Treatment and prognosis




Therapy

If therapy is chosen, injections with corticosteroids, orgotein, dysprosium-165 or atropine have been reported.20,21 Similarly injection of iodine or Lugol’s solution has been reported to be successful.3,21 Regardless of the product injected, most are unrewarding and/or require multiple injections to treat the condition. If there is an open wound, lavage with curettage of the ‘bursal’ lining can resolve the bursitis. The bursa may be surgically resected if the above methods fail to resolve the condition.







Collateral ligament injury/luxation






Recognition





Special examination

Ultrasound is the diagnostic method of choice for collateral ligament injuries. Radiography can be beneficial in cases where the ligament is completely torn, there are avulsion fragments or secondary osteoarthritis within the elbow joint.22 Distraction views can be helpful in diagnosing the rupture (Fig. 18.5). Nuclear scintigraphy can be beneficial if ultrasound or radiographs fail to diagnose the condition due to the bone attachments of these ligaments to the lateral humeral epicondyle or the lateral radial tuberosity. Intra-articular analgesia may improve the lameness; however, if the tears are outside of the elbow joint, these may be negative.






Treatment and prognosis




Therapy

As there are no surgical procedures for treating these ligaments, healing is by second intention. Regenerative therapies such as bone marrow derived mesenchymal stem cells or platelet rich plasma may be beneficial in these cases.23–25 Recheck ultrasound and lameness examinations should be performed periodically. The horse should be kept under stall confinement for at least a few months depending upon the degree of damage and then can be gradually re-introduced to handwalking. The course of healing will depend upon the degree of damage, but can take upwards of six months to one year for complete healing. Rehabilitation depends on ultrasound appearance on recheck examinations.






Jun 18, 2016 | Posted by in EQUINE MEDICINE | Comments Off on Elbow and Shoulder
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