Disorders of the inert structures

Published on 10/03/2015 by admin

Filed under Orthopaedics

Last modified 10/03/2015

Print this page

This article have been viewed 2575 times

Disorders of the inert structures

Chapter contents

Capsular pattern

The capsular pattern at the hip joint is gross limitation of medial rotation, abduction and flexion, less limitation of extension, and little or no limitation of adduction and lateral rotation (Fig. 47.1). In advanced arthritis, abduction and internal rotation are impossible and associated with obvious limitation of flexion and extension.

Fig 47.1 The capsular pattern at the hip joint.

A capsular pattern in the hip joint of a child or adolescent always implies a serious problem. The slightest limitation of movement should be reason enough to put the child on bed rest and start diagnostic procedures to detect the cause. Weight bearing is prohibited until the reason for the capsulitis is discovered (see online chapter Hip disorders in children).

If a capsular pattern is present at the hip and resisted movements do not hurt, the conditions discussed in this section should be considered.

Monoarticular arthritis in middle-aged people

This condition was described by Cyriax ⁵ (his p. 386). For no special reason, a middle-aged patient experiences aching at the anterior aspect of the thigh during exertion. Clinical examination of the hip shows only a slight capsular pattern, with some limitation of internal rotation and flexion. There is pain at the end of range and the end-feel is elastic. The radiograph reveals nothing but a normal hip joint. The condition continues unchanged for months. Intra-articular injection with triamcinolone seems to be ineffective, but the lesion responds very well to stretching of the capsule, which relieves the pain quickly and permanently (see p. 633–634 for technique).

Osteoarthrosis

Aetiology

It is widely accepted that the most likely causative factor in the development of arthrosis of the hip is the incapacity of (parts of) the hip to withstand mechanical stresses. In the literature, a distinction is made between primary and secondary arthrosis.⁶

Secondary arthrosis originates from a pre-existing anomaly at the hip, such as Perthes’ disease, acetabular dysplasia and epiphysial dysplasia. Rapidly developing osteoarthrosis most often results from aseptic necrosis.

When the osteoarthrosis results from an undetermined abnormality of the cartilage or the subchondral bone, the condition is called idiopathic or primary. Primary osteoarthrosis is extremely rare – in more than 90% of cases, previous abnormalities in the hip joint can be demonstrated.7–9

Initiation and progression of osteoarthrosis at the hip seem to be caused by continuous interaction between such factors as deterioration of articular cartilage, changes in the subchondral bone, stiffening of the capsule, dysfunction in the neuromuscular system and chemical changes in the composition of the synovial fluid.

Cartilage fibrillation

Articular cartilage is a viscoelastic substance. It deforms slightly under load. The main purposes of the tissue are (a) to transmit joint forces to underlying bone structures, (b) to minimize the frictional drag of joint motion and (c) to maximize the contact area of the joint under load.

Strain may induce loss of proteoglycan molecules in the collagen network.¹⁰ This results in an increase in hydration and loss of tensile strength, and initiates the fibrillation of the cartilage.^11,12

Subchondral bone

The health of articular cartilage depends largely on the mechanical qualities of its bony subchondral bed: the greater the discontinuity in elasticity between cartilage and subchondral bone, the more shear stress will occur.¹³ The presence of stiffened subchondral bone thus increases the likelihood of the progression of cartilage lesions.¹⁴

Capsule of the joint

Inflammation of the synovial membrane can also be responsible for the degeneration of cartilage: connective tissue activating peptides and catabolites are set free during inflammatory reactions and have a negative influence on cartilage and subchondral bone.15,16

In addition, rigidity of the capsule, so often seen in the early stages of arthrosis,¹⁷ plays a role in its progression: because of the loss of laxity, the normal gliding movement of the cartilage surfaces is altered, which imposes a change in load distribution and thus increases stresses on particular areas of the joint.

Synovial fluid

The composition of the synovial fluid may enhance the development of osteoarthrosis: a decrease in viscoelastic quality provokes more friction between the joint surface. It is well to remember that immobilization also decreases synovial fluid hyaluronan levels and may thus contribute to the progression of osteoarthrosis.¹⁸

Muscular dysfunction

Muscular dysfunction and disturbed neuromuscular balance are quite common in osteoarthrosis of the hip. They cause the joint to work under abnormal conditions and may play a role in the development or continuation of hip osteoarthrosis.¹⁹ A pattern of tightness and overactivity of the psoas, adductors, tensor fasciae latae and rectus femoris is typical in arthrosis of the hip joint, whereas the gluteals show a tendency towards weakness and inhibition.^20,21

The continuous interaction between the changing structures of the joint imposes a physiological imbalance, which starts the process of degeneration. Vigorous and persistent attempts to repair the degenerative changes aggravate the already disordered joint function and set up a vicious circle. Hypervascularity, weakening of the subchondral bone, fatigue fractures, localized zones of collapse, flattening of the femoral head and formation of osteophytes then become inevitable (Fig. 47.3). This whole process can lead to rapid destruction of the joint; however, this is not always the case and spontaneous clinical and radiological improvements can occur.²²

Fig 47.3 The aetiology of osteoarthrosis.

Conclusion: osteoarthrosis is a ‘joint failure’, similar to ‘heart failure’. The aetiology is multiple but each of the components of the joint (cartilage, subchondral bone, synovial fluid and joint capsule) plays a role in the pathogenesis.

Symptoms and signs

Although the diagnosis of advanced arthrosis of the hip is easy, it may be difficult to diagnose the early stages. Also, there is sometimes a striking lack of correspondence between the clinical picture and the radiographic appearance.

Symptoms

The pain is located in part of the L3 dermatome: the groin, the anterior aspect of the thigh, the knee and the leg as far as the ankle joint. It is important not to forget that a separate part of the dermatome is located in the region of the sacroiliac joint, so patients with arthrosis of the hip may also present with unilateral pain in the lower back.

In the early stage, pain is only present during and after exercise but later it becomes continuous and can even disturb sleep. It is suggested that pain at night in coxarthrosis is associated with an increase in intracapsular pressure and subsequent joint contracture.²³ If the patient mentions twinges during normal walking, the disorder is considered to be complicated by impacted loose bodies (see later).

Signs

The examination often reveals a capsular pattern, with internal rotation the most limited and some limitation of flexion, extension and abduction, but this is certainly not always so. Many cases of hip osteoarthrosis present with other movement restriction patterns: for example, gross limitation of both internal and external rotation.²⁴ As a rule, there is considerable difference between the clinical signs of an early osteoarthrosis and those found in advanced cases.

In the early stage, there is merely a capsular stiffening, without much erosion of cartilage or osteophyte formation. The clinical findings are therefore a capsular pattern with a less elastic end-feel. Most commonly, internal rotation is found to be the most painful and limited, followed by limitation of flexion, abduction and extension.

In advanced instances, gross limitation is found, with loss of all rotational movement. In extreme cases, a ‘hinge joint’ develops, allowing only flexion and extension in an oblique plane: the femur moves laterally when flexion is forced. The end-feel is hard and marked coarse crepitus can be palpated. Muscle tightness can sometimes be detected by performing muscle length test procedures such as those described by Janda and Lewit.25–27

Radiography

‘Osteoarthrosis of the hip’ must be a clinical diagnosis and it is unwise to rely entirely on the radiograph for estimation of functional incapacity and for deciding on optimal treatment. First, there is a considerable lack of correspondence between the degree of pain, the mobility of the joint and the radiograph appearances.²⁸ Second, the patient may suffer from other lesions at or around the arthrotic hip. These lesions – loose body, psoas or gluteal bursitis (see pp. 642–647) – are not radiographically visible. If a radiological examination is performed without a full history and proper clinical examination of the hip, such conditions will be missed and the painless arthrosis will be blamed for the pain.

The radiological changes in hip osteoarthrosis are: presence of subchondral sclerosis in femoral head and acetabulum, joint space narrowing, femoral head deformity, marginal osteophytes, cystic changes in the femoral head and the acetabulum, and migration of the femoral head. The severity of the radiological changes is classified into four grades (Kellgren 1–4). Classically, there are three radiographic types of arthrosis of the hip, according to the direction of migration of the femoral head.

• Most osteoarthrotic hips show superolateral migration of the femoral head with localized erosion of cartilage at the lateral border of the labrum and a widening of the inferomedial part of the joint.²⁹ Cameron and MacNab suggest that this is the form of osteoarthrosis that is primarily related to capsular restrictions and responds well to capsular stretching.³⁰

• A medial–axial migration occurs in about 10–15% of cases. This presentation is usually associated with gross osteophytosis at the lower border of the femur and labrum.

• Another 10–15% of cases are non-migratory hip osteoarthrosis, associated with superior or concentric loss of cartilage space and concentric formation of osteophytes (Fig. 47.4).

Fig 47.4 Migration of the femoral head: (a) superolateral migration; (b) non-migratory hip osteoarthrosis; (c) medial–axial migration.

Treatment

Early treatment of osteoarthrosis is vital. There is evidence that reduced motion of the hip (from capsular tightening and muscular imbalance) further increases the degenerative process in cartilage and subchondral bone. Several studies have demonstrated the beneficial effect of exercise on pain and disability.³¹ The treatment of choice is therefore early stretching of the joint (grade B mobilizations). Treatment with injections has only a limited indication. In later stages or in quickly developing osteoarthrosis, conservative treatment is useless and surgery is indicated (Box 47.1).

Box 47.1 Treatment of osteoarthrosis of the hip

Early and/or slowly developing osteoarthrosis

Capsular pattern, ligamentous end-feel and absence of coarse crepitus

• Capsular stretching – angular mobilizations

• In flexion

• In extension

• In medial rotation

• Traction (manual or mechanical)

• In maximally loose-packed positions

• In other positions

• Muscular re-education

• Stretching of shortened muscles

• Activation of inhibited muscles

• Gait control

• (Intra-articular injections)

Advanced and/or quickly developing osteoarthrosis

Non-capsular pattern, hard end-feel and coarse crepitus

• Surgery

• (Intra-articular injections may give temporary relief)

Capsular stretching

It is generally believed that early stretching of a tight capsule may prevent joint damage or at least slow further progression.³² Therefore, stretching is the treatment of choice in the early stage of the disease. The decision to use it depends largely on the clinical findings: early arthrosis with a slight capsular end-feel usually responds quite well to such treatment. Stretching is of no use in advanced arthrosis with gross limitation of movement, a hard end-feel and coarse crepitus because these are the clinical indications of gross cartilaginous destruction and formation of large osteophytes.

It is vital to start stretching treatment as early as possible. A stiff and inflamed capsule is one of the reasons for disturbed load distribution, responsible for further progression of degeneration. Furthermore, overuse at a stiffened capsule provokes consecutive strains, resulting in traumatic inflammation and pain.

Treatment is given 2–3 times a week, for 10–20 sessions. The joint is mobilized in three directions – flexion, extension and internal rotation – for 5–10 minutes each. The patient may experience slight aching for 1 or 2 hours after the forcing. This is an important criterion to the therapist, who must adjust the vigour of the treatment according to the length of time that the increased pain lasts. Slight after-pain for 1–2 hours is acceptable. If the patient suffers from increasing pain over 1 or 2 days, it is clear that the joint has been forced too much. If neither after-pain nor improvement follows, greater stress, more persistently applied, is used during the next visit.

The result that can be expected is not a marked increase in range but merely a decrease in pain. It is remarkable that pain at night, even of many months’ standing, can often be abolished by a few sessions of capsular stretching. Used at an early stage, years of relief can often be obtained, although it may be necessary to repeat the mobilizations once or twice a year to keep the capsule as mobile as possible.

Technique: forced flexion

The patient adopts a half-lying position on the couch. The therapist stands on the affected side, level with the patient’s knee. The hip is flexed as far as is comfortably possible. One hand rests on the anterior aspect of the knee, while the other presses the opposite thigh down towards the couch. With steadily increasing pressure applied to the knee, the thigh is forced towards flexion (Fig. 47.5). This position is maintained for as long as the patient can bear it: e.g. 1 minute. The pressure is then slowly released to give the patient a break and the same procedure is repeated.

Fig 47.5 Forced flexion of the right hip.

Technique: forced extension – 1

The patient lies prone on a high couch. The therapist stands level with the thighs. To prevent stress on the lumbar spine, it is vital to keep the patient’s pelvis on the couch when extension of the hip is forced. Therefore, with one hand, the therapist presses on the lower part of the buttock, which will obstruct movements at the lower back and the sacroiliac joint. With the other hand, the therapist grasps the thigh from the medial side, just above the patella. Both arms are kept rigid. Bending the body sideways, the therapist then pulls the patient’s thigh upwards, while the patient’s pelvis is pushed forcefully downwards (Fig. 47.6).

Fig 47.6 Forced extension of the right hip – 1.

Technique: forced extension – 2

Some elderly people have difficulty lying on their stomach for any length of time and an alternative method can be used. The patient lies flat on the back, with the head supported with a cushion. The painless hip is now forced as far into flexion as possible, which tilts the pelvis and makes the other thigh lift off the couch. Sufficient extension can now be forced when sustained downward pressure is applied just above the patella (Fig. 47.7).

Fig 47.7 Forced extension of the right hip – 2.

Technique: forced medial rotation

The patient adopts a prone-lying position on a high couch. The knee at the affected side is bent at a right angle. The therapist stands on the affected side and level with the pelvis. The ipsilateral hand is pressed on to the ilium. The other hand is placed at the medial malleolus and forces the hip into medial rotation. The pelvis rotates and moves the iliac crest backwards on the opposite side. Pressure applied on the pelvic region now forces the iliac crest downwards again. When the thigh on the affected side is held firmly in the rotated position, this downward pressure will considerably increase the outward stress on the affected hip (Fig. 47.8).

Fig 47.8 Forced medial rotation of the right hip.

Traction

Traction (either manual or mechanical) is an alternative technique to stretch the joint capsule.33–35

Practitioner’s checklist

• The ratio of pain to end-feel will indicate the degree of applied force (see general principles of treatment, p. 93). Movements should be performed to the point of discomfort but not of pain. In suitable cases, the force can be gradually increased during the session. A whole session takes about 20–30 minutes, with pauses after every 30 seconds–1 minute.

• Slight passive oscillatory movements can be added: type I and II mechanoreceptors come into play and suppress a painful reaction from the nociceptors (see p. 92). To prevent adaptation of the mechanoreceptors, oscillations should be constantly changed in rhythm, amplitude and direction.

• Although osteoarthrosis and osteoporosis do not seem to appear simultaneously, the former protecting from the latter and vice versa,36,37 forcing medial rotation should always be carried out with caution in elderly people, for fear of fracturing the neck of the femur.

Manual traction (distraction) can be given in two different ways: with an extended knee, in which case the traction is performed via the ankle; or with the leg flexed to more than 90°. Traction is then carried out via the proximal part of the upper leg. Because of the direction of the hemispherical acetabulum, in either case the femoral head moves inferiorly, anteriorly and laterally. Depending on the position of the joint, some parts of the capsule are stretched more intensively.

Traction I

The patient lies supine near the edge of the couch. To prevent the pelvis being pulled down or sideways, or lifted off the couch, two bands are used for fixation: one at the groin, and the other transverse over the pelvis just beneath the anterior superior iliac spines.

The therapist grasps the patient’s ankle. According to the direction of the acetabulum – inferiorly, laterally and anteriorly and in agreement with the maximally loose-packed position of the joint capsule – the leg should be brought into a position of about 30° of flexion, 30° of abduction and slight lateral rotation.

Traction is performed by leaning backwards with straight arms (Fig. 47.9). Once the therapist feels the patient relaxing the muscles, a jerk can be tried by pulling the arms towards the body. At this point, slight separation of the femoral head from the acetabulum can be felt.

Fig 47.9 Manual traction.

Traction II

The therapist sits or stands at the level of the pelvis. The leg should be flexed to at least 90° and slightly laterally rotated. Both hands take hold of the upper part of leg (Fig. 47.10a). Traction is performed in the direction of the acetabulum: inferiorly, laterally and anteriorly.

Fig 47.10 Mechanical traction.

Use of a band makes it possible to lessen the effort of the therapist a great deal. Both hands then hold the leg in position at the knee (Fig. 47.10b). Traction is achieved by leaning backwards.

Traction II is not suitable for manipulating the joint.

It must be noted that distraction of the hip joint can only be effective if the pelvis is completely immobilized; otherwise, the lumbar spine will compensate for the movement. To this end, two fixation belts are used. One should resist the movement of the pelvis caudally, while the other resists anterior and lateral displacement.

Muscular re-education

In order to correct the pattern of muscular dysfunction and a disturbed neuromuscular balance, selective activation of inhibited, weak muscles and stretching of tight, shortened muscles is advocated by several authors.38–41 The second measure is of even greater importance because tight, hyperactive muscles interfere with the activation of inhibited muscles. These muscles (usually psoas, tensor fasciae latae and rectus femoris) are stretched slowly without straining the joint.

Activation of inhibited muscles is achieved by exercises with low loads to prevent overflow into other muscles. It is also advisable to perform exercises as closely as possible to their functional manner. For this purpose, closed kinetic chain exercises are advocated because the weight-bearing component effectively stimulates mechanoreceptors around the joint, so improving muscular contractions.⁴²

Hip extensors can be activated lying supine, the lower leg over the edge of the couch, the hip extended and the knee in 90° of flexion. Pushing the foot on the floor facilitates both the gluteus maximus and the posterior part of the gluteus medius.

Activation of the hip abductors is performed first sitting near to the edge and at the corner of the couch, one leg extended and in contact with the floor. Supporting him- or herself on this leg, the patient activates the hip abductors. Standing with the feet about 25 cm apart and resisting pressure against the pelvis from the contralateral side is another effective exercise to activate the ipsilateral hip abductors. This can also be achieved if the patient is asked to lower and raise the contralateral pelvis. Placing the hands on a chair at each side of the body for support reduces the load.

In order to reduce the harmful effect of a limp, a walking stick in the contralateral hand may be necessary at first. It decreases the contraction of the ipsilateral hip abductors and thereby reduces compressive forces on the joint.

Finally, it is necessary to be aware of any harmful effect produced by the trunk or lower limb that might influence the development and continuation of the hip joint problems, i.e. stiffness of the lumbar spine, leg-length differences, or dysfunction at the knee or the talocrural or subtalar joint.

Intra-articular injections

If the patient suffers from a subacute exacerbation because of traumatic arthritis superimposed on a stiffened arthrotic capsule, one intra-articular injection with 50 mg of triamcinolone will relieve the traumatic inflammation and the pain but increased mobility will not follow. To avoid arthropathy, this injection should not be repeated.⁴³

Also, intra-articular injections with hyaluronic acid seem to be a safe and effective method of treatment for patients with advanced hip arthrosis and may lead to a significant reduction in pain scores, disability scores and analgesic use.44–46

Surgery

A McMurray intertrochanteric osteotomy is indicated in a painful hip that has good mobility. It has the advantage of diminishing pain while maintaining a useful range of motion in the ‘natural hip’.

Total hip replacement is indicated in advanced osteoarthrosis. It is one of the most commonly performed operations in the United States, with over 280 000 procedures reported annually.⁴⁷ The benefits of total hip replacement in terms of reduced pain and improved function and quality of life for patients with advanced coxarthrosis have been well documented in the literature.⁴⁸ The prosthesis is made up of two parts: an acetabular component made of a metal shell with a plastic inner socket (the socket portion) that replaces the acetabulum, and a femoral component made of metal (the stem portion) that replaces the femoral head.

There are two major types of artificial hip replacement: cemented and uncemented. Cemented total hip replacement uses cement to secure an implant to the bone, while with cementless technology the bone heals directly to the prosthesis. The choice is usually made based on age, body weight and lifestyle. Patients with poor bone quality or with less active lifestyles are candidates for cemented total hip replacement.

The life expectancy of the prosthesis is between 15 and 20 years.⁴⁹ Aseptic loosening with or without osteolysis is the major problem and accounts for 71% of the revisions, but the incidence had decreased three times during the past 15 years to less than 3% at 10 years in Sweden.⁵⁰ However, long-term durability of the acetabular components remains a major concern.⁵¹

Concerns regarding high rates of failure among young, active patients and a desire to preserve bone for future revision operations led to the development of hip resurfacing arthroplasty. This differs from total hip replacement in that the femoral head is resurfaced rather than resected, thereby preserving femoral bone stock, which could theoretically decrease morbidity and improve patient outcomes associated with future revision operations.52,53

Non-capsular pattern

A non-capsular pattern on clinical examination of the hip indicates the possibility of lesions of the joint itself or disorders of nearby tissues such as the buttock and the groin. The straight leg raising test and resisted movements help to differentiate the two possibilities.

Serious lesions in the buttock are characterized by an interesting pattern of physical signs, called the ‘buttock sign’, summarized in Box 47.2. Non-capsular lesions of the hip itself comprise loose bodies, bursitis and aseptic necrosis of the femoral head.

Disorders with a positive ‘buttock sign’

This clinical syndrome, described by Cyriax ⁵ (his p. 375), always indicates a major lesion in the buttock.

The buttock sign is characterized by more limitation and/or pain on passive hip flexion with a flexed knee than with an extended knee (i.e. straight leg raising; Fig. 47.11). The other passive movements at the hip joint are limited in a non-capsular way. This strange pattern immediately draws attention to the gluteal region. If the hip joint itself were affected, straight leg raising would not be limited, except in those gross articular patterns in which flexion cannot reach 90°. If the nerve roots, the sciatic nerve or the hamstrings were affected, hip flexion with a flexed knee would not be painful or limited because it does not stretch these structures. The fact that both movements are limited and painful implicates other structures in the gluteal region.

Fig 47.11 The buttock sign: passive hip flexion is more limited and/or painful than straight leg raising.

Checking for the buttock sign is very important in pain syndromes at the gluteal region. Because there will probably be nothing characteristic about the pain, only a comparison between the results of the straight leg raising test and passive hip flexion can detect serious disorders in the buttock.54–56 When this typical combination of signs emerges, a very careful examination of passive and resisted movements must follow. Passive movements disclose a non-capsular pattern, almost always with a full range of medial rotation. The end-feel of the limited movements is ‘empty’: as a consequence of the increasing pain, the examiner has to stop the movement, even though it is felt that the end of range has not been reached. Some resisted movements are painful and weak as well because they increase the tension on the affected tissues. As a rule, resisted extension and internal rotation are the most painful. Palpation may disclose a painful swelling.

To refine the diagnosis, the general temperature must be noted, a rectal examination performed and radiographs and/or bone scans done.

Septic bursitis

This is by far the commonest cause of a positive ‘buttock sign’. The condition usually occurs after direct inoculation during an intramuscular injection, although haematogenous dissemination is also possible, especially in the elderly.

History

The history is often rather trivial, with increasing gluteal pain spreading down the back of the thigh to the knee and calf. During the first few hours or days, the pain eases at rest and increases during movement. Coughing does not hurt. The features do not draw immediate attention to the buttock but rather suggest a nuclear disc lesion.

Clinical examination

The patient’s gait is hobbling, as if the weight can hardly be borne on the affected leg.⁵⁷ This major disability contrasts markedly with the minor degree of discomfort and is the first warning for the examiner.

Examination of the lumbar spine shows limitation of flexion, sometimes with a list towards the pain. This is logical since the pain increases when tension on the affected tissues increases during forward flexion of the spine. The other lumbar movements are of full range and painless, while straight leg raising is painful and somewhat limited.

These clinical examination findings correspond perfectly with the classic findings of a disc protrusion, so the diagnosis will be missed if the examination is not properly performed. When passive flexion at the hip joint is tested, the buttock sign will be apparent at once.

The local temperature is raised and palpation reveals a tender area just above and behind the greater trochanter. In advanced cases, an abscess may have formed, revealed by a swollen, tense and fluctuating area in the buttock.

Treatment

Treatment consists of ice packs, bed rest and antibiotic therapy. If there is an abscess, the lesion must be drained.

Sometimes the buttock sign and the localized and fluctuating swelling result from an acute haemorrhage after trauma: for example, a fall on the buttocks. Here the history of trauma is informative and the temperature is normal. Aspiration usually leads to complete cure.

Ischiorectal abscess

Occasionally, an anorectal abscess points towards the ischiorectal fossa instead of to the rectal region – an ischiorectal abscess.⁵⁸

Usually, the patient complains of gluteal pain, rather than of local rectal pain, and nothing in the history suggests an infection of rectal origin; the pain is related to movement and posture and not to function of the bowel.

Sitting is impossible. The patient limps badly and even putting the foot to the ground causes considerable pain.⁵⁹ The hip is held constantly in slight flexion but further flexion is prevented by increasing pain, as is straight leg raising, indicating the buttock sign. Apart from fever, other toxic symptoms may be present. The abscess may be felt during bidigital rectal examination with the index finger in the rectum and the thumb external.

The treatment is surgical and consists of prompt incision and adequate drainage.⁶⁰