Soft tissue injury

When injury or trauma occurs producing forces necessary to damage soft tissues it is important to consider what happens to these tissues at a cellular level. The secondary injury model described by Merrick (2002) considers there to be two stages following tissue injury, namely the primary and secondary injury response:

General physiotherapy aims of early phase management (phases 1 and 2)

The aims are:

The PRICE principles

PRICE is a mnemonic for the principal interventions commonly used in the immediate early stages following tissue injury. PRICE stands for :

These interventions together are applied in principle to address the seven aims of early phase tissue injury and healing management. These interventions are discussed below. The reader is also referred to the guidelines written in conjunction with the Association of Chartered Physiotherapists in Sports Medicine (ACPSM), on the immediate management of soft tissue injury using the PRICE principles (Bleakley et al. 2010).

First-line management

Increasingly in modern physiotherapy practice the physiotherapist will be the first line of medical assessment, management and advice. This may occur, for example, in the sporting environment, in private practice or via direct access services. These roles require the physiotherapist to have excellent assessment skills and experience, and the understanding of differential diagnoses and indications for onward referral. Several guidelines are in place to aid clinicians in managing and diagnosing injuries, and using investigations such as radiology. Physiotherapists should be aware of these guidelines and implement them appropriately in order to promote best practice. For example, physiotherapists working in these settings should be familiar with the Ottawa guidelines for ankle injuries (Bachmann et al. 2003), which guide clinicians on when to X-ray the ankle to rule out fracture.

Applying the PRICE principles in practice

Having discussed the elements of the PRICE principles it is evident that there are sometimes conflicting demands and that it is often not possible or, indeed, appropriate to employ all five principles simultaneously. As discussed previously, the research evidence underpinning these interventions is insufficient and much of everyday practice is based upon historical approaches and consensus opinion (Bleakley et al. 2010). It is therefore important to consider this and the physiological processes occurring in the tissues when rationalising a treatment plan for an individual patient. It is also important to make realistic and reasoned treatment decisions considering all bio-psychosocial factors. This can be illustrated through the use of the case studies in this chapter.

Severity of injury and progression through the healing continuum

The speed of progress and recovery of those who have sustained soft tissue injury will vary depending on a large number of factors. These include the type, severity and location of injury, the individual’s tissue type and response to injury, and many extrinsic factors, such as their exposure to appropriate treatment and advice in the immediate stages, and any other psychosocial factors. For example, a minimal grade I ligament injury effectively managed in the early stages may move very quickly through the continuum of tissue injury to repair and remodelling within a few weeks, whereas major tissue injury induced through trauma or surgery may require a much longer process. Those individuals not having sought, or followed, advice and treatment in the early stages are more likely to develop problems such as chronic swelling, loss of range of movement and function in injured and adjacent structures, and may even have compromised the formation of appropriate new tissue.

In view of this it is desirable that individuals seek early advice from an appropriately trained professional and that they fully understand the advice and treatment approaches taken. Often, many of the treatment modalities discussed so far can be implemented by a patient independently at home and the frequency and accuracy by which they do this will have a large impact on their recovery and progress. It should, therefore, be ensured that physiotherapy intervention is focussed on establishing that the patient fully understands the advice and treatment approaches that will be implemented at home, especially if the frequency of physiotherapy contact will be limited. If the patient does not fully understand the advice given and instructions regarding their activities at home then any benefit gained from a physiotherapy treatment session will be undermined by the patient’s behaviour in the intervening period.

When deciding how long to continue to apply these principles consideration of the severity and size of the injured area is required. Despite common descriptions of grades of muscle and ligament injury being used, it is impossible to determine this accurately without radiological investigation such as ultrasound imaging. This is an area of increasing research; however, its clinical relevance in the management of muscle injuries is still under debate. Without the aid of valid and reliable imaging it would seem sensible to use the patient’s level of pain and possible gentle palpation to indicate the size of injury as indicators of when to progress rehabilitation.

As discussed earlier, it is often suggested to consider beginning early movement of the injured part at around 72 hours post-injury as initial pain is reducing, and progressing to gradually achieve full range of movement of the affected tissues before moving on to increase normal muscle power, strength, timing and proprioceptive control in light of the patient’s individual needs and abilities. In the early stages, acute pain is often a sign of further tissue injury and bleeding; thus, activity and movement of the injured area should be discouraged. However, as the continuum progresses, pain is often secondary to problems such as joint stiffness and lack of strength and control, and needs to be respected but not seen as a barrier to progressing rehabilitation. This will be discussed in detail in the following sections.

Pathophysiology

Cellular processes during this stage include:

As the initial processes of inflammation begin to lessen, the inflammatory exudate begins to be absorbed. This leads to a decrease in swelling. Pain is reduced as a result. An increase in swelling during this stage is usually indicative of a more severe injury. Alternatively, this may be a result of inappropriate early management, for example a patient who has sustained a severe second-degree sprain of the lateral ligament complex at the ankle joint returns to full weight-bearing activity before the injured tissue strength has developed to a point where it is capable of withstanding the forces that walking demands of it. Tissue proliferation begins to occur as early as 24 hours after trauma. This proliferation begins the stage of fibrous repair, which usually involves the production of scar (collagen) material. The nature of the tissue, which is produced in the proliferation phase, is dependent on which elements of the tissues are damaged initially. If the cellular framework (satellite cells) is not damaged then regeneration of these cells may be possible. If the cellular framework (satellite cells) is destroyed then the tissue is replaced by scar tissue. In addition, if the cells damaged have no capacity to regenerate because they are deemed to be permanent cells, for example nerve cell bodies and cardiac muscle, then scarring definitely occurs. Scar tissue is a non-differentiated form of fibrous tissue that may develop some properties of the original tissue but will not function in the same way as the normal tissue would. By 2–3 weeks after the injury the majority of the scar tissue is in place. After this time, the rate of proliferation diminishes but may continue for several months following the injury. There is no hard and fast rule about exactly when this occurs, as the timeframe will vary in accordance with the factors that influence repair identified at the beginning of this section, for example it will occur earlier in vascular tissues.

Around 3–4 days following trauma the process of cell death will be complete and this means that the physiotherapist can assess the injury more objectively. At this stage the risk of aggravating/increasing the trauma or identifying false-positive findings because the patient’s pain is masking the real symptoms is reduced. It is at this point that the physiotherapist can begin to use therapeutic techniques that promote an increase in circulation and tissue temperature without fear of inducing further tissue damage or further bleeding.

Physiotherapy in the tissue proliferation stage (1–10+ days post-injury)

In this tissue proliferation stage physiotherapeutic treatment approaches are aimed at the achievement of the goals as identified above by influencing the pathophysiological processes involved in this stage of healing and repair. While approaches to physiotherapy to address the first four aims have largely been covered in the earlier parts of this chapter when considering the management of the bleeding and inflammation stages of the healing and repair continuum these are still worthy of a mention here. In order to reduce pain the injury may require a degree of ongoing protection, such as limiting movement to that which is pain free. However, the degree of protection will slowly be reduced throughout this stage.

Use of cryotherapy at this stage

Cryotherapy can continue to be utilised if the area injured continues to have an elevated temperature. However, it is likely that this will probably only be required at this stage in more severe injuries. Often at this stage the physiotherapist might choose to apply cryotherapy at the conclusion of a treatment session. The clinical reasoning underpinning this is that during this stage the potential to cause minor bleeding and inflammation as a result of treatment is high owing to the frail and vulnerable nature of the newly developing tissue. Cryotherapy applied at the end of treatment can potentially minimise the risk of this occurring.

Prescribing activity and exercise in the proliferative stage

During this proliferative stage the main input by the physiotherapist is to encourage a graded return to exercise and activity. This is achieved through the prescription of a specific exercise programme tailored to each individual patient’s needs. This type of approach that involves active involvement of the patient is valuable as it promotes patient empowerment and prevents the patient from taking a passive approach to treatment.

The aims of increasing range of movement, maintaining/increasing muscle strength/timing/control, preventing soft tissue adaptation in non-injured tissues and improving function are all best achieved through application of graded exercise and activity. Inevitably, function will be improved to some extent by activity to increase range, increase muscle strength and prevent soft tissue adaptation. However, it is important that functional activities that are specifically pertinent to the individual are targeted specifically within an individual’s treatment programme as early as possible, for example increasing ankle range of movement is unlikely to produce a direct improvement in walking performance without a specific rehabilitation activity aimed at improving walking. The primary emphasis of activity and exercise in this proliferative phase is to increase range of joint movement.

Grading the level of activity

Ensuring that any activity undertaken by the patient early in the proliferative stage is completed within pain-free limits provides a mechanism to protect newly developing tissues and prevent further secondary damage to those tissues initially traumatised at the time of the injury. It is sensible throughout this proliferative stage of healing and repair to use the patient pain report during activity as an indicator of appropriate levels of activity and exercise. As a rule, any activity or exercise prescribed in the proliferative phase that provokes pain, which could be classified with a high SIN (pain severity, irritability and nature) factor should be avoided.

From around the second day post-injury, fibroblasts are increasingly prevalent around the site of the trauma. These are the precursors to the formation of new fibrous tissue that will enable the healing process. In the proliferative phase, it is inappropriate to do aggressive activities or exercises of the areas directly affected by the trauma, as this will only serve to further damage the newly developing tissue. The use of gentle, active movements controlled by the patient within the pain-free range is appropriate at this stage – they will stimulate fibroblast activity and promote the production of collagen tissue. This is an example of the plasticity described earlier in the chapter.

Beyond the fourth day post-injury, proliferation of new, developed collagen tissue begins to accelerate thereby strengthening the healing of the injured tissue. As a result of this, increasingly greater ranges of pain-free movement can be expected. The physiotherapist needs to encourage their patients to practise these movements frequently throughout the day. Taking the movements to their pain-free limit will begin to progressively load the newly developing tissues and will facilitate an inbuilt progression of activity because as the pain eases progressively more range of movement will be achievable. This will promote the further formation and alignment of collagen and hence promote repair and the development of a functional scar (Watson 2004). However, care must continue to be taken, as during this phase any excessive loading still has the potential to damage the newly-formed tissue thereby provoking further injury and delaying the repair process.

Range of movement exercises will contribute to the maintenance of muscle strength and promote tissue-loading, but during this stage it is normal practice to limit the amount of overt strengthening/timing/control exercise recommended to the patient until full, non-weight-bearing pain-free active and passive ranges of movement are achieved. The use of isometric contractions involving structures not directly affected by the injury can be commenced early in the process.

Other available physiotherapeutic techniques suitable at this stage include reciprocal inhibition. This can be useful to increase range of movement and increase tissue length (Waddington 1976). Reciprocal inhibition is the physiological phenomena which occurs when a skeletal muscle (antagonist) contracts and the opposing muscle (antagonist) relaxes. These techniques can be useful when trying to encourage elongation of the musculotendinous apparatus. Their main use is when muscle tension or muscle spasm is identified as the reason for limited range of motion.

Very gentle passive static stretching of affected tissues can begin at this stage as long as precautions are taken not to be over zealous. Again, the patient’s pain report is the main indicator of the amount of stretch that it is safe to apply. Ballistic stretching would not be advocated at this stage, as the potential to overstretch the newly forming tissues and reinjure while performing this technique is high.

As the tissues continue to proliferate, more fibrous tissue is laid down and the healing tissues begin to get stronger. During this time corresponding increases in the forces applied to the tissues can be made by increasing the force of stretch applied, increasing the range of movement produced and increasing the number of repetitions of any activity.

As a progressively greater load is applied to newly forming fibrous tissue it begins to remodel in response to the increasing forces applied. In addition, it is proposed that the haphazard arrangement of collagen laid down in the early healing stages begins to take on a more organised pattern as load is applied to it. The collagen fibres begin to align themselves along the lines of the stress. It is important, therefore, that the stresses applied to newly forming tissue are directed along the functional lines of stress normally required by that tissue. This requires the physiotherapist to apply their anatomical knowledge in an effective way.

From about the sixth day post-injury onwards there are increasing amounts of fibrous tissue laid down and, correspondingly, increasing levels of activity can be promoted. Tissues should be stressed progressively. It is considered to be both safe and advantageous to warm-up the affected tissues prior to activity – this has the effect of reducing the amount of load required to stress the tissues (compared with cold tissue) and therefore the tissue can be stressed more safely.

Electrotherapy in tissue healing and repair

The use of electrotherapy in the healing and repair processes has long been discussed and, again, there is varied evidence to support or discount the use of modalities such as ultrasound (US), pulsed electromagnetic energy and laser therapy in facilitating these processes. Electrotherapy as a topic is very large and this chapter does not claim to fully address all the literature and physiology surrounding it. The reader is referred to the electrotherapy chapter and other texts and literature for further information and discussion of these topics.

The most common electrotherapy modalities that appear to have the potential to have a direct action on the tissue repair process are US, pulsed shortwave diathermy (PSWD) and laser therapy. There is substantial evidence to support the notion that these modalities all have the capacity to influence the normal physiological processes of tissue repair, particularly the early inflammatory stage; however, clinical trials that demonstrate their efficacy in the clinical situation are lacking.

Watson (2006) describes a simple model of electrotherapy (Figure 12.3). This model summarises that the machine-generated energy in one form or another is delivered to the tissue. This energy is then absorbed by the tissue (to varying degrees depending on type), which then results in a change in one or more physiological events. It is the result of the energy being absorbed by the tissues resulting in a physiological shift, which is referred to as the therapeutic effect.

Figure 12.3 A simple model of electrotherapy.

Reproduced from Watson (2006) with permission.

Pathophysiology

Key processes involved in the phase of tissue remodelling are:

You must remember that the different phases of the healing and repair process do not occur in perfect sequence. The phase of tissue remodelling and soft tissue contraction overlaps significantly with the earlier proliferation phase (see Figure 12.2). Remember that the peak of fibrous tissue repair occurs 2–3 weeks after the injury and the whole healing process is a dynamic one as older fibrous tissue is removed and new scar tissue is laid down. The continued application of physical stress to the developing tissues is one of the most significant factors influencing this phase of the repair process. The newly laid down fibrous tissue becomes ‘more organised’, being arranged less randomly and beginning to orientate itself along the lines of stress, thus enabling them to function more normally. This is the beginning of the remodelling phase which can continue for months and, possibly, for more than a year. It is clear, therefore, that this process continues long after the noticeable healing process and definitely beyond the time in which the patient would be in direct contact with the physiotherapist within the active rehabilitation process. This means that it is important that therapy, usually in the form of activity and exercise, continues long after an individual has been discharged from the ongoing care of the physiotherapist. Some evidence shows that even at this stage remodelling is still ongoing and tissues have not returned to their full functional capacity. Research in anterior cruciate ligament repair in monkeys indicated that the repaired anterior cruciate ligament reached 56%, 76% and 96% of its normal tensile strength 6 weeks, 12 weeks and 24 weeks after repair respectively. While this extent of remodelling may be acceptable in some members of the population it may not be so in others.

A key feature of the remodelling phase is soft tissue contraction. This is a process by which the newly formed tissues begin to physically shorten. This process has the potential for the healing tissues to begin to restrict and limit mobility and range of movement in the affected tissue. This process of soft tissue contraction begins to occur around the third week post-injury and continues long into the remodelling phase. As this process continues long after a patient would normally be discharged by the therapist, it is a key influence on the nature of the ongoing prescription of activity and exercise given to patients following discharge.

This phase of remodelling process takes place following the proliferative phase and is referred to as the chronic stage in some texts. Within this chapter, this phase is seen as a natural progression following the proliferative stage in an uncomplicated process of proliferation and remodelling.

General physiotherapy aims in the remodelling stage (phase 4)

The aims of physiotherapy in the remodelling stage may include any, or all, of the following:

• promoting collagen growth and fibre/tissue realignment;

• increasing the range of movement:

 active;

 passive;

 accessory;

• increasing muscle strength/control/timing;

• preventing soft tissue adaptation in injured and non-injured tissues;

• maximising function.

Physiotherapy in the remodelling phase (Phase 4)

These aims can be related to the ongoing pathophysiological processes involved. Fibroblastic activity increases and new collagen fibres continue to be laid down. This process peaks around 2–3 weeks post-injury, continues through to 4–6 weeks following injury and is clearly extended beyond this timeframe in more severe injuries. Ongoing attention to progressive activities started in days 3–10 post-injury is required. The purpose of the physiotherapeutic treatment is to promote movement and mobility of the injured structures/tissues.

Preventing tissue contraction and adhesion formation

Beginning around the third week post-injury the healing scar tissue begins to undergo a process known as soft tissue contraction. This means that the physical length of the tissue actually begins to get shorter. Consider this in the case of a hamstring injury as described above. At the same time that you are working with the patient therapeutically to lengthen the hamstrings the remodelling tissue begins to cause the healing scar tissues to shorten. This is a process that can go on for a considerable period of time after the injury. At this stage, it is normal for the patient to experience some discomfort during end-range stretching activity.

Contractures can sometimes become permanent. In these cases it becomes impossible to stretch the scar tissue. This is known as fixed contracture. Fixed contractures develop when the normal connective tissues (which are elastic) are replaced by fibrous tissue (which is inelastic). This means that the tissue will not stretch and this prevents normal movement. Contractures can occur in any tissue. The key to preventing the development of fixed contractures lies in ongoing therapeutic exercise and activity aimed at ensuring that as the scar tissue forms it remains a mobile, functionally-able structure. At the end of the remodelling stage the injured soft tissue will be repaired by scar tissue. The desired outcome is that this final scar is able to be a functional replacement for the tissues initially injured.

A potential problem during the remodelling phase is the formation of soft tissue adhesions. This is where newly forming fibrous tissue has been produced between adjacent layers of tissue such that these layers become bound together. These adhesions, when formed, can severely limit movement and soft tissue function. Normal movement requires that adjacent layers of tissue are able to move independently, for example a tendon moves over a bony surface or beneath a fascial band such as retinacula while the bone/retinacula stays still. As the formation of fibrous tissue during the proliferation phase is completely random, the potential for the development of adhesions is real. Movement in the early stages of healing and repair helps to ensure that the newly forming tissues do not create these adhesions. In some healing processes, where long periods of immobility are part of the patient management, their formation is probably inevitable. Soft tissue adhesions are normally easily palpable – tissues feel thickened and immobile to soft tissue palpation and mobilisation.

Passive and accessory mobilisation techniques

Other techniques aimed at restoring full working/functional length in tissues include passive and accessory movement techniques. The application of these demands the use of an in-depth knowledge of human anatomy. This means that the physiotherapist can select the appropriate techniques to attempt to influence a specific structure.

Activity and exercise continue to play a key part in the physiotherapy management. A shift towards an activity and exercise programme placing more emphasis on improving muscle strength/timing/control is normally seen at this stage. It is important to consider all the ways in which the tissues in question are loaded during normal functional activity. This enables the physiotherapy programme to be tailored appropriately to an individual’s need.

Muscle tissue will need to be able to withstand load from active and passive forces, from concentric, eccentric and isometric contractions at varying points within its range. It may need to work in an open-chain or closed-chain environment; it may need to function as an agonist, antagonist, synergist or fixator; it may need to generate strength, power or endurance. All of these factors must be considered when developing patient-specific exercise and activity programmes in the remodelling phase. Only when all of these things are considered and incorporated effectively into an exercise and activity programme is the potential for rehabilitation of individuals back to their full and maximum functional capacity realised.

The context of an individual’s normal functional activity is paramount to effective physiotherapy practice, whether it be playing a 90-minute game of football in the premiership or getting into and out of a car. The key skill that the physiotherapist utilises here is that of movement analysis. By analysing the demands of the activities that an individual aspires to be involved in, the physiotherapist is able to plan rehabilitation to meet individuals’ needs with the aim of maximising each individual’s capacity. Too often, in the author’s opinion, the lowest common denominator of functional ability is accepted. This becomes the norm and physiotherapeutic intervention fails to enable individuals to achieve their full potential.

Tissue remodelling is a prolonged process which is especially pertinent in young patients who are remodelling and growing at the same time. In this client group, remodelling periods are often prolonged beyond the normal periods for adult members of the population.