Introduction

When dealing with chronic lameness cases, the two main sources of potential error (omission and misinterpretation) are related to the time you spend working up the case. For many lameness cases, it is virtually impossible to complete this in a routine consultation lasting 10–15 minutes. It may therefore be necessary to allocate some consultation space for extended consults for lameness cases.

It is important to adopt a standard protocol for handling lameness cases and to stick to it regardless of the pressures of time or any positive findings during the examination. More than one lesion may be present in the lame limb and you may not find the significant one first.

The amount and quality of information derived from an orthopedic examination varies greatly between clinicians. A thorough, methodical examination based on a sound understanding of normal anatomy and locomotion will maximize the yield from an orthopedic examination.

Lameness can result from abnormalities in any of the following systems:

 Skeletal system disease / abnormality - this is the most common cause of lameness, particularly disease of the joints

 Muscular abnormality (e.g., myopathies)

 Neurologic abnormality (e.g., disc disease)

 Systemic disease - many systemic diseases can directly or indirectly cause lameness. For this reason it is essential to examine the whole animal (i.e., complete physical examination) and not just perform an orthopaedic examination.

 Combination of the above

There are 4 Steps in the workup of a lameness case:

1.  History

2.  Observation of gait

3.  Physical examination

4.  Further diagnostics (as required to rule in / rule out your differential diagnoses)

A methodical and consistent approach to orthopaedic examination is essential to maximise success.

History

The history can be taken from the owner while the animal is allowed to walk around in the consulting room. This lets the animal become familiar and "more secure" in the strange surroundings and allows you to observe it during this time. Much useful information can be gleaned from passive observation.

Many conditions are more commonly seen in particular breeds or types of dog (e.g., German Shepherds with hip dysplasia, Rottweilers with cruciate disease). Familiarity with breed predispositions is helpful but should not be relied upon. Similarly some orthopedic conditions have a gender predisposition (e.g., male dogs and osteochondrosis, neutered female dogs and cruciate disease).

Which limb(s) does the owner think are lame? Remember that owners commonly identify the wrong limb as being lame, particularly in subtle forelimb lameness - do not rely on the owner to identify the lame limb.

 What is the duration and severity of the lameness?

 What was the nature of onset of the lameness - acute or gradual?

 Is the lameness progressive or static?

 Is it consistent or intermittent?

 Is it confined to one limb, multiple limbs, or is it shifting?

 Is it worse or better at certain times? (e.g., during exercise, after rest, in cold weather)

 Has there been any previous treatment and if so what response has there been to this treatment?

Important additional information can be gained from asking questions about the general health/condition of the patient (including previous injuries or illnesses), the housing environment, feeding, and exercise routine, and the intended function of the animal (e.g., racing versus pet)? This is a very important consideration given the irreversible nature of many joint diseases.

Observation: Assessment of Conformation, Stance and Gait

The first step that is often ignored by clinicians is careful examination of the animal's conformation and stance. This can often be very effectively achieved during the history taking. Standing with weight unevenly distributed (front/rear or left/right) or with one limb rotated abnormally can be important pointers to the source of the problem. Watching how a dog sits gives a good idea of stifle pain and range of motion. Identifying bowlegged vs knock-kneed vs straight leg conformation can point to the likely location of the primary problem.

Successful gait analysis is dependent on the clinician's knowledge of normal gait. Gait observation is ideally performed on non-slippery surface. Dogs will often not walk normally on the slippery floors of the average consulting room, particularly if very nervous. Cats are very difficult to observe as they will often not move at all in the consulting room and when they do will "protect" their gait through fear and often not show any lameness.

Observe the animal's gait at a walk and a trot in all directions (moving away, towards and across or around you is ideal). A running gait makes observation of lameness often very difficult. With some lameness problems that only become apparent after hard exercise schedule an appointment for when the owner completes their usual exercise routine.

Identify the lame limb(s). Unilateral forelimb lameness is the easiest to pick - remember the head "drops" on the non-lame (less lame?) limb. Actual lifting of the head as the lame limb strikes the ground is seen in more severe lameness. Bilateral forelimb lameness is probably the hardest lameness to pick. Remember that limping is to some degree a "luxury" that can only be afforded if one limb is less painful than the other. Bilateral forelimb lameness will typically be apparent as a shortened `"choppy" or "stilted" gait with shortened stride and limited elbow flexion; the whole limb looks to move almost as one relatively fixed bone. No head bob is apparent. Often in chronic bilateral forelimb lameness the changes in conformation and stance are overlooked - the hindlimbs are often positioned further cranially under the caudal abdomen and the head carriage is higher to shift load to the hindlimbs.

Subtle forelimb lameness can often be unmasked walking dogs down stairs. Similarly more subtle hindlimb lameness may become more apparent climbing stairs.

Unilateral pelvic limb lameness is typically manifest as a "raising" of the pelvis during the stride phase of the gait. Bilateral pelvic limb lameness varies depending on the joints involved. Bilateral hip lameness is usually manifest as a "waddling" or "oscillating" gait at a walk; this is usually a result of exaggerated thoracolumbar lateral flexion - the spine is bent laterally on the lame side to allow the foot to advance further with a limited range of motion of the hip. Bilateral stifle joint lameness typically displays a shortened "stilted" stride phase at a walk with elevation of the hindquarter and limited stifle flexion. At a trot and on stairs dogs with bilateral hindlimb lameness often display a bunny-hopping gait. In chronic bilateral lameness the dog's conformation and stance often change; muscle mass and "weight" increase in the thoracic limbs / chest relative to a loss of muscle / "weight" in the hindlimbs. The head is held lower and the forelimbs positioned more caudally beneath the thorax to "unload" the pelvic limbs.

Look for circumduction of a limb also; this is non-specific and reflects a compensatory mechanism for a reduced ability to flex a joint that can be due to either pain or a mechanical cause (e.g., arthrodesis). The more proximal the joint the more easily the animal can compensate for more minor limitations in flexion. Limitations in carpal flexion will often cause more obvious circumduction.

For subtle or intermittent lameness or lameness that is simply not apparent because a dog (or cat!) is very nervous ask the owners to record the lameness on video.

Physical Examination

There are four components to the physical examination in lameness cases:

1.  General physical examination: Is essential. This is particularly so in trauma cases where concurrent injuries (e.g., pneumothorax, urinary tract damage) are common.

2.  Neurologic examination: A limited or "functional" neurological examination should be a part of any orthopaedic examination. Testing of postural reactions (such as conscious proprioception) is simple and very sensitive and will determine whether a spinal neurological problem exists. If so, a complete neurological examination should be performed.

3.  Standing examination: For symmetry - this greatly facilitates the detection of subtle muscle wasting or joint abnormalities by comparing both sides simultaneously (provided the abnormality is unilateral). It also gives the dog the chance to become comfortable with your touch - remember that to perform a complete orthopaedic examination actually requires a lot of cooperation from our patients! Many clinicians bypass this stage, which is a mistake; it is much easier to appreciate muscle wasting, subtle joint changes and other symmetry changes in the standing exam than in the recumbent examination.

4.  Recumbent examination: Greater muscle relaxation when recumbent allows more detailed examination of the affected limb. Start your examination as far away from the likely source of lameness as possible, e.g., start with the contralateral normal limb. Start at the toes and work proximally. Palpate every structure as you move up. "Visualise" the underlying anatomy as you do so - "seeing" things in 3D as you feel them is very helpful. Palpate the soft tissue structures feeling for pain, fibrosis, crepitus, tumours etc. Firmly palpate the bone where it is superficial enough to do so (this is good for detecting bone tumours and panosteitis for example). Put each joint through a range of motion, feeling for the changes listed below under joint abnormalities.

What Should You Look For On Physical Examination?

 Consistent localisation of pain in joints, soft tissue structures or bone. Pain localisation is the best indication of the site of lameness. Pain is not always associated with lameness and may not be the cause of lameness although the vast majority of lameness cases have significant pain as a feature.

 Joint abnormalities: Joints are the most common site of lameness. It is essential that you become familiar with what normal joints look and feel like. This will make you much more sensitive in detecting joint abnormalities such as:

 Periarticular fibrosis: This is a sign of chronic joint pathology.

 Joint effusion: A sign of active joint disease.

 Decreased range of motion: Range of motion is most accurately assessed under general anaesthetic. Most clinicians have a good "feel" for normal range of motion in dogs. Remember that there is variation with age and between breeds. A normal adult dog should be able to touch its digital pads in the forelimb to the caudal surface of the antebrachium, its carpus to the shoulder and its hock to its tuber ischii.

 Crepitus: "Noise" within the joint that can be felt or occasionally heard. True crepitus is an important finding but must be interpreted with care. Clicking of joints is often normal and of no significance - in these cases there are no other pathologic characteristics (e.g., effusion, fibrosis, pain) on joint examination. A torn meniscus may give a marked "click" on manipulation of the stifle joint but soft tissue crepitus and osteophytes can also cause clicking. Crepitus can also be referred up or down the limb so accurate definition of its precise location is important. Remember also that suture material around mobile joints like the stifle joint can cause soft tissue crepitus that is not significant.

 Joint instability: Joints should be stressed to assess for instability - valgus / varus stress to assess collateral ligament integrity and pain. Dorsal and palmar / plantar stress for the joints of the manus and pes. Specific instability tests exist for several joints such as biceps stretch test and abduction test for the shoulder, Ortolani Sign and Barden's (hip lift) test for the coxofemoral joint, and the cranial drawer test and tibial compression test in cruciate rupture.

 Pain: The "gold standard" lameness localiser.

 Muscle fibrosis / muscle wasting / muscle pain / reduction in muscle extension (e.g., gracilis disease in German Shepherds).

 Regional lymph node enlargement.

Successful detection of the abnormal requires a sound familiarity with what is normal.

Repeating the physical 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 and arthrocentesis 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 localization is lost under heavy sedation.

Further Diagnostics

History, observation and physical examination generally allow localization 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 useful diagnostic aids in orthopedics include arthrocentesis (joint tap) and synovial fluid examination, arthroscopy, arthrotomy, CT scan, biopsy (of bone, muscle, joint capsule), hematology and biochemistry panel, MRI scan, scintigraphy.

Scintigraphy is rarely necessary but has potential as an aid to localizing lameness in the very difficult cases where the other diagnostic tests have not provided sufficient information. A study conducted by staff at the Glasgow Veterinary School used scintigraphy as an aid to diagnosis in 14 lame dogs, and found it helpful in 9 of those cases (Schwarz T, et al. J Small Anim Pract 2004;45:232–237). Although currently limited in availability to a small number of centers, this modality may play an increasing role in lameness diagnosis in the future.

Conclusion

A methodical, systematic approach to the chronic lameness case will build the clinician's knowledge base of normal structure and function, which then leads to confidence in detecting abnormalities. Localizing the primary lesion is the ultimate aim of lameness workup, so that further diagnostics and treatment can be properly focused, resulting in the best result for patient and owner.