Learning Objectives

At the end of this session, which will focus on canine lameness, you will be able to:

• Recognise a shift in stance and how this identifies the site of lameness
• Identify a positive sit test and how this helps localise disease
• Identify elbow effusion and elbow pain as indicators of elbow dysplasia
• Palpate medial buttress and stifle joint effusion as indicators of cruciate disease
• Perform an Ortolani test for identifying hip laxity as an indicator of hip dysplasia
• Identify typical signs of panosteitis on orthopaedic examination
• Perform a test for biceps tendon laxity

An orthopedic examination, like a neurological examination, is a detailed systems examination that is performed in addition to a general physical examination. So you will need to allow additional time if you are going to perform a complete orthopedic examination.

The amount and quality of information derived from an orthopedic examination varies from clinician to clinician.

Much of an orthopedic exam relies on subjective assessment of the dog compared to a normal dog of that breed or type or compared to the joint/segment/limb on the contralateral side. Where possible try and rely on objective changes - for example where a joint is clearly enlarged and unstable in comparison to the contralateral joint. Unfortunately, identification of clearly objective abnormalities is not always possible - early disease with subtle changes and bilateral disease are examples.

To improve identification of subjective or subtle abnormalities requires a thorough, methodical examination based on a sound understanding of normal anatomy, stance and movement. Using a consistent method of performing orthopaedic examination will improve your ability to detect subtle changes.

Signs of an orthopedic problem may include some or all of the following:

• Stiffness on rising after rest
• Change in exercise capacity or exercise behaviour
• Change in stance (altered distribution of weight)
• Lameness/change in gait
• Pain - pain is the most common cause of lameness. Lameness can also result less commonly from mechanical causes (such as patella luxation), neurologic disease, vascular disease, and systemic disease.
• Change in normal shape
• Asymmetry - for example, joint enlargement or muscle wasting. Reduction in muscle mass is typically seen in chronic lameness.
• Change in normal alignment
• Change in stability or range of motion

It is important to recognise that quadrupeds are very good at “masking” lameness or not showing obvious limping until their pain is quite marked. This has both evolutionary and practical benefits. Close observation of how an animal stands, moves, and gets up and down from a recumbent position will often indicate lameness in earlier or less severe cases.

What is lameness? Lameness is an abnormal gait or stance resulting from some abnormality in the locomotor system.

What are you trying to achieve in an orthopedic examination?

1.  Localize the limb(s) affected - Is the animal lame and if so in which limb(s)?

2.  Localize the site(s) of the lameness - Where is the source of the lameness?

3.  Identify the cause(s) of the lameness - This usually involves radiography, advanced imaging or other diagnostics.

4.  Determine the appropriate treatment and prognosis.

Some definitions that are useful when talking about lameness:

• Stride - The full cycle of limb advancement
• Contact phase - The part of the stride when the foot is in contact with the ground
• Swing phase - The part of the stride when the foot is in the air and not in contact with the ground

There are 4 steps in an orthopedic examination:

• History
• Observation of stance and observation of gait
• Standing symmetrical examination followed by recumbent examination
• Further diagnostics - as indicated

1. History

The history should be taken from the owner while the dog is allowed to stand or walk around in the consulting room or outside rather than placing the dog on the examination table. Having the dog walk or stand lets them become familiar and “more trusting” in unusual surroundings and allows you to observe them during this time.

In many cases simply by the way they stand or in some cases sit you will be able to identify the lame limb(s).

2. Observation of Stance and Observation of Gait

Observation of stance: Simpler than gait observation. Observing an animal stand often is sufficient to identify lameness and, in many instances, gives more useful information than gait exam.

Quadrupeds have the ability to shift their centre of mass both to one side, as with humans, and also cranially or caudally. This re-distribution of their mass reduces the load going through the lame/sore limb(s) thereby reducing the pain and very often minimises the observable lameness.

Visual observation of canine lameness is relatively insensitive. In one study 75% of dogs with no observable lameness were actually lame when measured objectively on a force plate¹. In other words, even in dogs with significant unilateral lameness (and remember that bilateral lameness is even more difficult to detect than unilateral lameness) only 25% showed apparent lameness on visual examination of their gait.

However, even though quadrupeds shift their centre of mass to minimise observable lameness, this shift is usually readily apparent provided that you are familiar with normal stance of dogs - and that you actively look for this change.

To expend the least amount of energy when standing a normal dog will stand with the foot directly beneath the dependent joint - the shoulder or hip joint. When dogs have a unilateral limb lameness they bend their spine laterally towards the lame side and bring their sound leg closer to the midline. The lame leg is laterally abducted. This creates a “tripod” stance where the lame limb is used for balance but is not taking full weight.

In some cases when you look at their feet you will see that in the sound limb that is taking most of the load the metacarpal/metatarsal pad is fully compressed and the nail tips consequently sit up off the ground. On the contralateral lame limb the pad is not fully compressed and so the nails are usually in contact with the ground.

When dogs have a bilateral forelimb lameness they often shift their mass more to the pelvic limbs by bringing the feet of the pelvic limbs cranially. If you look at them stand from the side you will see that their feet are cranial to a line drawn perpendicularly from the hip to the ground.

When dogs have a bilateral hindlimb lameness they often shift their mass more to the thoracic limbs by bringing their elbows caudally so they are positioned more caudally underneath their thorax than normal. If you look at them stand from the side you will often see that the feet of the thoracic limbs are caudal to a line drawn perpendicularly from the shoulder to the ground. They will often also lower their head to further shift their weight from the hindlimbs.

Not that too many dogs do “handstands” but if you think of the action they would need to make if they were going to perform a handstand this will explain the way they change their stance in bilateral hindlimb lameness.

Observation of gait: What sort of gait abnormalities could you observe? This depends on whether the cause of the lameness is unilateral or bilateral.

If lameness is unilateral, or if one leg is significantly worse than the other, then these gait changes are typically observed:

• The classic “head-bobbing” lameness. Remember the head drops on the good limb not on the lame limb. “Down on the sound” is the phrase that is often used. This not infrequently is misinterpreted by owners and they may wrongly advise you that they think the dog is lame on what is actually the sound limb. The classic head-bobbing lameness is most obvious in unilateral forelimb lameness. Landing more heavily on the sound limb is also seen in the hind limbs though is less obvious than in the forelimbs.
• Shortened contact length and duration in the affected limb and increased contact length and duration on the sound limb. The animal wants to spend as little time with the sore leg bearing weight as possible. The contact phase is shorter in the lame leg and longer in the sound leg. The swing phase is quicker in the sound leg as the dog is “rushing” the good leg through to take weight to minimise the time that the sore leg needs to bear weight. This faster swing phase in the sound leg is often misinterpreted as indicating this is the lame leg.
• Circumduction - the animal with a painful joint or a decreased range of motion in a joint will often circumduct the limb in preference to flexing the joint.

Bilateral lameness, particularly when it is symmetric, is particularly hard to detect. Beware the bilaterally lame animal as these commonly go undetected as the gait abnormalities are more subtle. In these cases, the dog has “lost the luxury of limping” as the limb on one side is just as sore as the other. Their main compensation in these cases is to walk with their centre of mass set in the position described above under changes in stance.

Typically dogs with bilateral joint-related lameness will walk with a “stiff” or “stilted” gait as they limit the range of motion of their painful joint.

What about grading the severity of the lameness?

This is subjective and varies with the individual doing the grading. There are a number of “systems” for grading lameness, including a descriptive scale, a scale of 1 to 10, a scale of 1 to 5, etc., but none is widely accepted. None have been validated for repeatability. The key is to be consistent with whatever system you choose and ideally use the one simple system throughout all clinicians in your hospital.

3. Standing Symmetrical Examination Followed by Recumbent Examination

Standing Symmetric Examination

The aim of this part of the exam is to compare each side simultaneously for evidence of difference in size, either muscle wasting or joint/segment/limb enlargement. Also, to palpate the musculature of the spine. This is most easily done standing behind and over the dog.

The forelimbs are easier to detect relative muscle wasting than the hindlimbs by comparing the prominence of the spine of the scapula. In the hindlimbs muscle wasting is identified by symmetric palpation of the main muscle masses and is more affected by the amount of load the dog is taking on the limb at the time.

Relative hindlimb muscle mass is most reliably compared visually when the dog is anesthetised in dorsal recumbency during the subsequent diagnostic investigation. Relative joint enlargement, which can be from a variety of causes most commonly effusion and periarticular fibrosis, can be palpated in the elbow and stifle and joints distal to these. It is uncommon to be able to palpate joint enlargement in the shoulder or hip joints.

Conscious proprioception should be assessed as part of the standing symmetry exam. The spine should be assessed by gentle palpation of the epaxial muscles and vertebrae for pain and assessment of free range of motion of the cervical and lumbosacral spine.

Recumbent Examination

This obviously relies on having a cooperative dog. Most dogs will allow a calm recumbent exam. Owners are most often not useful in helping quietly restrain the dog.

Start at the foot pads and work proximally. Palpate every structure progressively as you move up. Think of the underlying anatomy as you do so.

Palpate each joint and assess whether it is enlarged, either through effusion or periarticular fibrosis, has normal stability and a normal range of motion, whether there is crepitus or palpable osteophytes present and in particular whether there is consistent localisation of pain.

Localising a focus of pain is of course challenging. It is subjective and relies on a cooperative and trusting patient. However consistent localisation of a focus of pain is one of the most useful findings on orthopaedic exam to identify the site of the problem.

If you have identified possible limitations in joint range of motion during the recumbent exam you should confirm this if the dog is having further diagnostics performed under sedation or general anaesthesia by repeating the recumbent examination. This is very useful as it allows easy immediate comparison of range of motion and stability of joints although of course removes identification of pain as a localising factor.

Palpate the soft tissue structures. Palpate the muscle groups for defects, abnormal texture, masses and pain. Palpate and stress accessible tendons and ligaments. Be familiar with the location of regional lymph nodes and assess for evidence of enlargement.

Firmly palpate the bone where it is superficial enough to do so. It is abnormal for bone to be painful on palpation.

Repeating the orthopedic examination while the animal is under general anesthesia is often very beneficial, as it allows more detailed examination, particularly of joint structures, than is often possible while the animal is conscious. This is usually done if further diagnostics such as radiography are to be performed. In animals with a poor temperament examination under sedation or anesthesia may be the only way to perform a physical examination. It is important to remember that reliable pain localisation is lost under heavy sedation or general anesthesia.

4. Further Diagnostics

History, observation and physical examination generally allow localisation of the site of the lameness. In some cases it may also determine the cause of the problem and the appropriate treatment and prognosis. More usually however further diagnostics, most commonly radiographic examination of the affected area, are necessary before an accurate diagnosis and appropriate treatment may be determined.

Other diagnostic aids commonly used in orthopedics include arthrocentesis (joint tap and synovial fluid examination), arthroscopy, arthrotomy, biopsy (of bone, muscle, joint capsule), haematology and biochemistry panel.

References

1.  Evans R, Horstman C and Conzemius M. Accuracy and optimization of force platform gait analysis in Labradors with cranial cruciate disease evaluated at a walking gait. Veterinary Surgery 34: 445–449, 2005

2.  Arthurs G. Orthopaedic examination of the dog 1. Thoracic Limb. In Practice 33: 126–133, 2011

3.  Arthurs G. Orthopaedic examination of the dog 2. Pelvic Limb. In Practice 33: 172–179, 2011