CHAPTER 10 Musculoskeletal assessment
A thorough musculoskeletal assessment of the whole limb is an essential component of evaluation of a patient’s specific and often localised lower limb complaint. Apparent localised foot and ankle problems may have a genesis in proximal regions or, conversely, have secondary untoward effects on other structures. Such an assessment involves both static and dynamic assessment of musculoskeletal function.
Movement of the lower limb involves interaction between the musculoskeletal and nervous systems. The function of both systems can be compromised by vascular pathology. This chapter concentrates on the orthopaedic assessment of the musculoskeletal system. The assessment of the vascular system is covered in Chapter 6 and the neurological basis of movement and assessment of the nervous system are covered in Chapter 7. As the healthcare practitioner becomes competent, experienced and confident, essential components of these three systems will be evaluated seamlessly during the patient evaluation. Although reference is made to the weightbearing examination during this chapter, this subject, including gait analysis, is covered in greater detail in section 10B (functional assessment).
Qualitative, semiquantitative and quantitative measurement techniques are used. The practitioner should be aware of the likely errors that can ensue from such measurements and take these into consideration when interpreting and analysing data from the assessment (see Ch. 4).
Figure 10A.1 Cardinal planes of the body: sagittal, frontal and transverse. Sagittal divides the body into right and left halves, frontal divides the body into front and back, and transverse divides the body into upper and lower sections. The diagram shows midplanes but the terms refer to any plane parallel to the appropriate midplane.
Universal use of these terms of reference is important when communicating with colleagues as one can be safe in the knowledge that they will understand the nature of the pathological process being described.
• Anterior (to the front of) and posterior (to the rear of) describe positions in the frontal plane, e.g. the patella, or knee cap, lies anterior to the main weightbearing part of the knee joint (tibio-femoral).
• Distal (away from the centre) and proximal (towards the centre) describe positions in the transverse plane, e.g. the interphalangeal joints of the foot (IPJs) lie distal to the metatarsophalangeal joints (MTPJs) of the foot.
• Medial (towards the midline of the body) and lateral (away from the midline of the body) describe positions in the sagittal plane, e.g. the navicular lies on the medial side of the foot and the cuboid on the lateral side.
Motion in the sagittal plane produces extension and flexion. The terms used to describe sagittal plane motion in the foot are slightly different from those used to describe such motion at the hip and knee (extension and flexion).
At the ankle (Fig. 10A.2), the midtarsal joints (MTJs), the MTPJs and the IPJs, sagittal plane motion is termed dorsiflexion and plantarflexion. Dorsiflexion denotes a raising of the whole or part of the foot towards the leg, whereas plantarflexion denotes the movement of the dorsal aspect of the foot away from the leg.
Motion in the frontal plane produces abduction and adduction of the thigh and leg and inversion and eversion of the foot. This is because the foot lies at right angles to the leg, so the terms used to describe movements of the foot differ from those used for the leg and thigh.
Abduction is when the distal segment moves away from the midline of the body and adduction when it moves towards the midline. For example, in order to do the ‘splits’, gymnasts must abduct their legs. Inversion of the foot is when the plantar aspect of the foot is tilted so as to move towards the midline of the body. Eversion is when the plantar aspect of the foot is tilted so as to face away from the midline of the body (Fig. 10A.3).
Internal rotation occurs when the anterior surface of the distal segment rotates medially in relation to the proximal segment and external rotation when the opposite occurs – the anterior surface of the distal segment moves laterally in relation to the proximal segment (Fig. 10A.4).
Figure 10A.4 Relationship between transverse plane motion in the leg and transverse plane motion in the foot. A The feet are mildly abducted; this is the normal standing position B The legs are externally (laterally) rotated, which results in abduction of the feet (C). D The legs are internally rotated (medially), which results in the adduction of the feet (E).
In the foot, the use of the terms adduction and abduction depends upon the site of the reference point: the midline of the body or the midline of the foot. Functionally, the midline of the body is usually used as the reference point:
The mid-axial line of the forefoot is different from that of the hand. For the latter, the middle finger is taken as the mid-axial point. Muscles which abduct (dorsal interossei) and adduct (palmar interossei) the fingers take the middle finger as their reference point. Conversely in the foot the longitudinal axis has shifted pre-axially and the second toe becomes the reference point for the mid-axial line for the actions of the dorsal and plantar interossei. The adductor hallucis is inserted into the lateral side of the proximal phalanx of the hallux and is so termed because it brings about adduction of the hallux – movement of the hallux towards the midline of the foot.
It is important that a distinction is made between joint motion and position; a joint may be moving in the opposite direction to the position it occupies at any one moment. For example, at heel-strike the foot is slightly supinated (position) but as soon as the heel contacts the ground pronation (motion) occurs at the subtalar joint (STJ) in order to absorb shock from ground contact.
• Sagittal plane – equinus is when the foot or part of the foot is plantarflexed, e.g. ankle equinus, and extensus is when the foot or part of the foot is dorsiflexed, e.g. hallux extensus. Calcaneus is used to describe the calcaneus when it is in fixed dorsiflexion, e.g. talipes calcaneovalgus.
Figure 10A.5 Frontal plane deformity of the legs. A Genu valgum (knock knees): the knees are close together and the medial malleoli are far apart. B Genu varum (bow legs): the knees are far apart and the medial malleoli are close together.
To reinforce the importance of understanding these terms, Figure 10A.6 illustrates the three planes of a knee as seen on a plain radiograph and Figure 10A.7 illustrates the three planes of the ankle and hindfoot as seen on magnetic resonance imaging (MRI).
Figure 10A.6 Plain X-ray views of a knee joint: A anteroposterior or frontal (coronal) view; B lateral or sagittal view; C and skyline (axial) or transverse view, demonstrating patello-femoral position.
Normal lower limb function should be free of pain and energy efficient. The main purpose of the orthopaedic assessment is to identify whether the system is functioning within the boundaries of ‘normality’. Normal function can be affected by many factors (Box 10A.1). It should be remembered that orthopaedic lower limb problems are not always isolated in origin. They may result from referred pain from a proximal source or can be part of a systemic disorder, e.g. a neuromuscular disease. It is therefore important that the lower limbs are not examined in isolation and that observation and examination of other parts of the body are undertaken where indicated.
Box 10A.1 Factors that can affect normal function
When undertaking an assessment of the lower limb it is essential that the system is observed weightbearing (dynamic and static) and non-weightbearing. Differences between the two states can help to determine whether compensation has occurred. For example, non-weightbearing assessment may identify the presence of a forefoot varus; observation of the patient’s gait may show this problem has been fully compensated through abnormal positioning of the STJ. Conversely, information from the non-weightbearing assessment may explain the cause of a gait abnormality, e.g. a patient may have a bouncy gait due to an early heel lift; non-weightbearing assessment of the ankle joint may reveal that the cause is an ankle equinus secondary to a short gastrocnemius muscle.
The sequence of assessment of the above varies among practitioners. There is no one correct sequence; practitioners should adopt the sequence and approach they feel most comfortable with. However, it is essential that a systematic approach is adopted to ensure vital pieces of data are not omitted. For complete assessment, the examination should involve the following three important sections:
For successful assessment, it is important that the patient is at ease and cooperates with and has confidence in the practitioner. The practitioner should always be sensitive to the patient’s needs and explain what they are about to do and why, before undertaking the assessment. Qualitative and quantitative measurement should be undertaken where necessary, but the data must be meaningful and reproducible if they are to be of any use in assessing improvement or deterioration. Various measuring devices may be used; their use will be discussed in the appropriate sections.
• It is valuable to obtain an overview of both limbs, particularly if the onset of the problem is insidious, the pain is diffuse and nonspecific or if during testing a number of joints seem to be implicated.
• Where only one limb is affected, it is often helpful to start with the unaffected limb first, then repeat the test on the affected limb. Compare ranges of motion, end feel (the sensation the examiner feels when they push the joint being examined to the end of its range of motion) and muscular strength.
Not all the tests will be required during every lower-limb assessment. The selection of tests used will depend on the findings as the examination proceeds, and should be influenced by the preceding clinical history and observations. However, it is necessary to be thorough enough to rule out alternative pathologies. The exclusion of alternative aetiologies may require the assessment of additional systems, e.g. the cardiovascular system. Referred pain associated with local nerve entrapment or radicular patterns of pain in which spinal nerves or nerve roots are irritated need to be considered.
Remember that a problem that affects one part of the system can lead to problems elsewhere in the system. The lower limb functions as one mechanical unit and as a result a problem in one part may have to be compensated for in another part of the system. Compensation is a change in the structure, position or function of one part in an attempt to adjust to an abnormal structure, position or function in another part. For example, scoliosis of the spine may lead to an apparent leg-length discrepancy, which will affect foot function. Conversely, a problem affecting the foot, e.g. an uncompensated rearfoot varus, may lead to discomfort/pain at the knee.
The assessment process starts at the time of introduction. Observation of a patient’s demeanour, facial expression, seated posture and how they get up from a chair provides valuable clinical information. In addition, the way in which the patient walks into the clinic, together with use of walking aids, provides more information about mobility and how this might be influencing lower limb/foot function. After history taking, the patient will have to undress appropriately. Observation of the ease with which this is achieved gives an insight into the way a patient copes with certain activities of daily living.
Observation of each lower-limb joint before the examination will establish the presence of any clinical features synonymous with pathology, e.g. oedema, contusion, erythema, local muscle wasting, alteration in shape or the presence of scars. Symmetry of contralateral parts, abnormal posture/evidence of limb shortening and abnormal joint movement during gait are additional clinical clues to underlying pathology.
Palpation of the limb segment or joint for clinical features such as raised/lowered skin temperature, swelling/effusion, tenderness, pain or abnormal lumps/nodules also provides information to help establish a diagnosis.
Features of an inflamed joint are redness (rubor), heat (calor), pain (dolor), swelling (tumour) and loss of function. Inflammation of a joint may be due to a range of factors, e.g. trauma, arthritis and infection. Examination of the joint, information from the medical and social history and results of radiological and laboratory investigations will enable a diagnosis to be made. If a patient complains of a painful joint, the characteristic features of the pain should be recorded.
ROM is the amount of motion at a joint and is usually measured in degrees. The ROM at a joint can be compared with the expected ROM for that joint, e.g. if only 20° of motion occurs at the first MTPJ when the expected norm is 70° (28% of the normal ROM) it can be concluded that the ability of this joint to carry out normal function is impaired (hallux limitus). Often a guesstimate of the amount of joint motion is made from observation. Protractors, tractographs and goniometers can be used to quantify joint motion (Fig. 10A.8).
A joint may show normal ROM but the direction of the motion may be abnormal. It is, therefore, important to note the direction as well as the range. For example, the total ROM of transverse plane rotation at the hip is 90°; 45° internal rotation and 45° external rotation. If the ROM is 90° but there is 70° of external rotation and 20° of internal rotation then the ROM would be normal but the direction of the motion would be abnormal. Normal joint motion should occur without crepitus, pain or resistance (quality of motion). The ROM and direction of motion of a joint, e.g. hip, should be the same for both limbs (symmetry of motion). The presence of asymmetry of motion should always be noted.
Joint motion can be affected by the ligaments around the joint. It is important as part of joint assessment to identify any dysfunction of the ligaments, e.g. ligament tear or rupture. Finally, joints should be assessed as to whether they are subluxated or dislocated. Dislocation occurs where there is no contact between articulating surfaces of the joint and subluxation where there is only partial contact.
The range of active and passive movement of each respective lower limb joint should be examined, documented, and compared with the contralateral side. It is useful to assess whether passive movement of the joint provokes any pain or guarding (sometimes seen in hallux limitus). In addition, it is valuable to document the response to resisted testing (strong/weak/painless/painful) and stability of the joint. This will determine the integrity of the articulating surfaces and ligaments. Provoking crepitus on joint movement is an indication of joint damage.
All muscles should show tone. Asking the patient to undertake isometric contraction of a muscle is a useful means of identifying tonal quality. Tone can also be assessed by the examiner holding the limb and placing it through a range of movement. Involuntary resistance is indicative of increased tone.
Muscle bulk should be observed and comparisons made between the limbs. Atrophy of muscle results in a loss of muscle bulk and may be due to a number of factors, e.g. lack of use, lower motor neurone lesion. Hypertrophy of muscles that show normal tone and symmetrical distribution is considered normal and is usually due to exercise. Unilateral atrophy/hypertrophy can be assessed by observation and recorded by measuring the girth of both limbs with a tape measure.
It may be necessary to carry out specific tests to confirm a diagnosis or to differentiate between similar conditions. Some clinical examination techniques have been developed to test a particular aspect of joint function, e.g. Lachman’s test to assess sagittal plane stability of the knee in an anterior direction and thereby the integrity of the anterior cruciate ligament. The section on non-weightbearing examination discusses the specific tests used to assess each of the lower limb joints and their associated structures.
Usually the information obtained from a detailed history and assessment is sufficient to arrive at a diagnosis. Occasionally, specialist investigations may be necessary to confirm the diagnosis or to consider other options. A number of possibilities are available including: specialist imaging techniques and haematological, biochemical and nerve conduction studies and electromyography (EMG). In addition, histological examination of specimens, video/treadmill gait analysis or computerised analysis/forceplate analysis may be indicated.
The prime purpose of the non-weightbearing examination is assessment of the joints and muscles of the lower limb and other important soft-tissue structures. A flat couch is required for the patient to lie on. Patients should feel comfortable and relaxed and should not be wearing restrictive clothing. Non-weightbearing examination involves an assessment of the following:
The hip joint is regarded as a stable ball and socket synovial joint. It has sufficient mobility to allow economic gait and stance while being more restricted than its counterpart in the upper limb, the shoulder joint (glenohumeral joint), which tolerates greater potential instability in exchange for increased motion. The hip joint’s stability is provided by:
Hip joint pain (coxodynia) is usually felt as an anterior groin pain sometimes radiating down the front of the thigh as far as the knee. In children, significant hip pathology may present as knee pain due to the shared nerve supply (femoral and obturator nerves).
A frequent diagnostic problem is distinguishing hip from spinal problems, and they often co-exist in elderly people. Low back pain radiating into the buttock, and posterior and lateral aspects of the thigh is more likely to have a spinal origin. Similarly proximal pain which radiates below the knee into the calf and foot is unlikely to emanate from the hip joint. A history of altered sensation or weakness in the limb is more likely to be neurological in origin. With concomitant spine and hip pathology, an intra-articular injection into the hip joint of local anaesthetic (with or without steroid in arthritic conditions) under aseptic conditions and image intensifier control can help distinguish the contribution of the hip from that of the spine.
Not every patient who presents to a podiatry clinic needs to have their hips examined. However, the hip should be examined if the patient complains of discomfort or pain in the area and/or gait analysis reveals an abnormality which affects normal pelvic and lower limb mobility and mechanics, e.g. weakness or limb discrepancy. The hip should be examined with the patient:
• The examination couch should ideally not be placed against a wall. The examiner should be free to examine the patient from both sides and be allowed unencumbered assessment of parameters such as hip abduction.
• The patient should be adequately exposed. Ideally, they should be undressed down to shorts or suitable underwear. Both the hip and spinal areas should be exposed to assess linked mobility and posture.
This test is performed with the patient standing. The patient can be assessed from the front or behind – the latter is usually more reliable. The patient is initially asked to single leg stance on the unaffected limb. Normally the contralateral buttock is elevated and pelvis tilted towards the standing side. This moves the centre of gravity of the body closer to the centre of the standing hip joint. The pelvic tilt is produced by the hip abductors (principally gluteus medius and minimus).
The patient is asked to elevate the contralateral pelvis for 30 seconds, and then they are asked to repeat the test on the affected limb. If the contralateral hemi-pelvis cannot be elevated and held for 30 seconds the patient is said to be Trendelenburg positive. Often the patient will tilt their trunk excessively, bringing the centre of gravity close to or even lateral to the centre of the standing hip joint. A positive Trendelenburg test indicates one or more of the following problems:
Ideally the patient should be able to lie fully flat on the examination couch. The examiner should be able to observe the pelvis and limb position and gain access to the lumbar spine area to assess changes in lumbar position. Usually, the examination is commenced with the patient lying supine. Check that the patient’s iliac crests on either side of the pelvis are level and that the lower limbs are placed in identical position. Begin the supine examination with an assessment of limb-length inequality (see end of section 10A).
Ask the patient to point and demonstrate the sight of any pain. The centre of the hip joint is deep to the femoral pulse, which can usually be easily palpated. However, the hip is a far deeper joint than the knee and, subsequently, it is more difficult to palpate and has fewer landmarks. However, a systematic examination around the hip joint should include palpation of:
Check for evidence of previous scarring from surgery or trauma. Look for healed sinuses which may be evidence of old, deep infection. Look for evidence of wasting of the thigh musculature – indicative of disuse of the joint.
Before commencing formal passive hip movements, it is wise to ask the patient to move each limb actively in turn. This allows a rapid, albeit global, assessment of the amount of pain-free movement that is likely to be available in each limb. Similarly, gently rotating the extended limb internally and externally will indicate the degree of ‘irritability’ of the joint. Pain from this gentle manoeuvre is unlikely to elicit pain from any pathology except an intra-articular problem.
To ensure normal forward progression during gait, sagittal plane motion at the hip is essential. There should be approximately 120–140° of flexion and 5–20° of extension, although not all of this is necessary for gait.
Extension of the hip is assessed by placing one of the examiner’s hands under the lumbar spine. At rest the curvature of the lower spine (lumbar lordosis) should be felt. With the hand staying in this position, ask the patient to flex the healthy hip and knee. As the hip progressively flexes, the lumbar curvature should progressively flatten until the lordosis is obliterated.
If during the process of flexing the healthy hip, the damaged hip begins to lift from the couch, the patient is said to exhibit a loss of extension or fixed flexion deformity (FFD), which can be measured in relationship to the horizontal. Many patients when standing and walking attempt to ‘mask’ moderate degrees of fixed flexion deformities by increasing their lumbar lordosis.
The test can be undertaken ‘in reverse’ by asking the patient to flex both hips and during this manoeuvre confirm that the lumbar curve has been obliterated. Then, in turn, ask the patient to hold one leg in position with their hands while gradually extending the other hip. In health, a person should be able to place the leg on the couch without increasing the lumbar lordosis as a compensatory mechanism.
If the hip displays no evidence of an FFD, more subtle changes of hip extension may be detected by placing the patient prone. With the pelvis stabilised by the examiner’s hand, each limb in turn is lifted from the couch and any difference noted. Normal extension is up to 10–20°.
The good hip is flexed to allow lumber spine flattening. The comfortable flexion angle is noted and the patient asked to steady the limb with their own hands. The affected hip is then flexed while checking that the pelvis and lumber spine remain static. A comparison is made between the flexion in both hips.
This should be assessed with the patient lying flat and supine, with room to assess both limbs. An exaggerated impression of available hip abduction may be gained if the pelvis is not stabilised by the examiner placing their hand on the contralateral iliac crest as the limb is moved. Then the limb is moved outwards and the arc of movement from the midline noted. If possible, when dealing with unilateral pathology, start with the normal side. Usually, enough abduction is available in the healthy hip to allow the leg to hang dependent over the couch with the knee flexed. This allows further stabilisation of the pelvis and allows comparison with the contralateral side. Normal hip abduction is at least 40°.
Tightness of the adductors on attempted abduction is common in osteoarthritis and other common hip pathologies. In cerebral palsy, it can lead to a scissors-type gait when one or both legs have a tendency to cross over during gait.
Internal and external hip rotation can be assessed in several different ways. The recorded measurement might be slightly different according to the method employed. It is important that the way the assessment was conducted is recorded in the notes. Essentially there are three methods:
With the patient supine, rotation can be assessed with the hips and knees extended, i.e. the legs straight. Observe the patient from the foot of the bed and assess rotation in each limb simultaneously. Hold each heel in the palm of your hands and first externally rotate and then internally rotate each limb. In this position, rotation is derived from the hip, unless there is any knee instability. It is useful to observe the movement of the patellae as a gauge of the amount of rotation from the hip. The alternative method with the patient supine is to flex to 90° the hip and knee joints. This may be difficult if hip flexion is painful and restricted. The hip is moved both internally and externally and the angle is measured by comparing the position of the shin with respect to the midline.
With the patient prone, rotation can be assessed by flexing the knees to 90°. The legs can be simultaneously rotated outwards to assess and compare internal rotation. External rotation can be assessed with one limb extended and the other leg moved towards the midline. Alternatively, external rotation can be compared by crossing the legs. For all these manoeuvres it is important that rotation is not exaggerated by the pelvis lifting alternatively off each side.
In health, 45° of comfortable internal and external rotation is possible. In certain conditions, e.g. unilateral excessive femoral anteversion, the total rotational arc may be the same in both hips, but with a skew in one rotational direction in one hip compared to the other. Females tend to show more internal rotation than males (Svenningsen et al 1990). The range of transverse plane motion at the hip decreases with age and most hip pathologies.
Femoral anteversion is the angle that the femoral neck makes with the shaft of the femur. It varies with age, and there is a difference between the sexes. In males, the neck lies more in line with the femoral shaft than in females – 140° compared with 120° of anteversion. In children, the angle is similar to that in the adult female. It is important for podiatrists to be aware of this because excessive femoral anteversion is one of the most important causes of ‘intoeing’ – especially in the child (along with tibial internal torsion and persistent metatarsus adductus).
The most accurate clinical evaluation of femoral anteversion is with the patient lying prone and the knee flexed. With the contralateral limb extended, rotate the leg from side to side. Feel the greater trochanter laterally as the hip rotates. When the trochanter is truly facing lateral, the angle between the shin position and the vertical represents the anteversion angle of the femoral neck. On occasions, computed tomography (CT), which can measure this angle more accurately, is required.
Ask the patient to walk up and down the examination area. Make sure that there are no obstructions and the patient can perform at least four to five stride lengths. With regard to hip pathology, the four most common reasons why a patient has a limp are:
Patients often display one or more of these problems. A thorough examination of the patient on the examination couch will have flagged up likely gait problems, e.g. limb shortening and significant hip pain on motion.
Conventional radiographic views of the hip joint includes an AP view of the pelvis (Fig. 10.9) and a lateral view of one or both hip joints. The advantage of the pelvic AP view is that the hips can be compared and any other pathology within the bony pelvis can be noted, e.g. Paget’s disease. Other views can be requested under specific circumstances but are beyond the scope of this discussion.
MRI can be used to look for subtle pathology within the hip joint, e.g. labral cartilage tears. Additionally, it allows visualization of the extra-articular soft tissues and may detect conditions that cause hip/groin pain, e.g. bursitis. MRI can also show subtle osseous lesions, for instance early avascular necrosis.
CT can be useful for looking at bone and joint structure and disease. Modern CT scanners with the ability to collect increasingly smaller, thin slices of information, are capable of detecting ever more subtle lesions. In addition, the ability to reformat the information into a three-dimensional image has helped our understanding of musculoskeletal pathology and planning of corrective procedures.
Scanning with isotopes such as technetium-99m is a useful way of determining the presence or absence of pathology in the region of the hip joint. It is helpful in distinguishing the location of discomfort, e.g. hip joint pathology versus spine. It is sensitive for identifying areas of inflammation and abnormal pathology while not being particularly specific about the cause. It is particularly useful in assessing whether an established hip replacement is beginning to loosen and causing symptoms.