Musculoskeletal injury

Chapter 5 Musculoskeletal injury

Injuries to musculoskeletal structures can be divided into two main groups; those due to acute injuries and those due to overuse injuries. Both injuries may have a brief history of onset as regards their symptoms and signs; however, an acute injury may not be attributable to a developing pathology and occurs out of the blue, such as a bone fracture or a tear within a muscle. Overuse injuries, however, may have a more gradual onset and a multifactorial cause, whether it be related to training load, biomechanics, previous injury or inadequate rehabilitation. This may predispose to an injury that may present over a chronic period of time or may be sub-clinical and then present with an acute onset. The following text will describe different types of acute and overuse injuries affecting the musculoskeletal system and summarise their symptoms, signs and treatment.


Injuries to bone

The bones provide a rigid structure to the skeleton and are a site of rigid attachment of muscles, tendons and ligaments. It also provides protection to vulnerable soft tissues within the skeleton. Activity increases the strength of bone and thickens the structure, whereas inactivity weakens them. Bones can adapt to stress applied to them as long as the stress is applied gradually. An acute stress or dramatic increase in the stress results in fracture. Bones are better at resisting compression rather than tension or torsion and that is why fractures mostly occur on torsional forces.

A fracture may occur either as a result of a direct blow as in trauma or as a result of indirect trauma such as a torsional injury. Fractures may be transverse, oblique, spiral or comminuted and a special group in adolescents exists as a form of avulsion, where a tendon or ligament that is stronger than the piece of bone to which it is attached pulls the fragment away from the bone. Fractures may result in distortion of the bone in terms of angulation, rotation and shortening and the aim of treatment is to return the fractured bones as precisely as possible to their correct position and reduce any malalignment. Some fractures are more common in certain sports, such as tibial fractures in soccer players, forearm fractures in gymnasts and clavicular fractures in horse riders.

Features of a fracture include swelling and progressive bruising in the injured area and tenderness and pain at the site of injury, aggravated by loading the limb and movement of the injured site, deformity and abnormal mobility of the limb and restriction of movement. Occasionally, these symptoms are lessened when there is a compression injury such as in the neck of the femur, where signs may be minimal.

Treatment includes: first aid measures, such as covering the open injury with a sterile compress and clean bandage; immobilising the limb by splinting or bracing; elevating the injured limb; and arranging further investigation and transport to hospital for imaging. It is important to confirm the presence of vascular or neurological impairment at an early stage to prevent any ischaemia or long-term nerve damage. The correction of malalignment or the relocation of a dislocated joint on site when there may be vascular or neurological deficit can be limb-saving. It is important to document exactly the sequence of events and to be sure of your actions for medico–legal reasons.

Non-displaced fractures can be treated by immobilisation in a cast, boot or brace with advice for the patient to be aware of increased pain, swelling and/or tingling distal to the calves that may be signs of compartment syndrome. Bracing will help the fracture heal but will result in stiffness of the joint above and below the brace, and, therefore, following removal of the brace active mobilisation needs to occur.

Displaced fractures need to be realigned either by manipulation or with fixation, and then immobilised.

Complications of fractures include infection, which is most likely to occur in open fractures, acute compartment syndrome where rapid swelling of the muscle compartment around the fracture causes a rise in pressure within the fascial sheath and ischaemia, not only of the muscle, but of the distal structures including the nerves and blood vessels. The patient complains of severe pain, usually at the fracture site or distal to the fracture site, which may be out of proportion to the degree of initial injury associated with pallor, paraesthesia and pulselessness and pain on passive stretching (all the ‘Ps’). This requires urgent recognition and decompression with fasciotomy as a medical emergency.

Other complications include injury to associated structures such as muscles, ligaments, tendons, nerves and blood vessels. Certain fractures have a close proximity to these structures, including distal humerus and the brachial artery and median nerve, distal radius and the median nerve and olecranon fractures and the ulna nerve. Specifically, neck of femur and scaphoid fractures may result in avascular necrosis due to their unique blood supply and the importance of this needs to be recognised. Further complications include deep vein thrombosis as a result of immobilisation of lower limb fractures and its subsequent pulmonary embolism, as well as fat embolisms of long bone fractures and pelvic fractures. Do not underestimate the degree of haemorrhage that may occur as a result of a fracture, mainly within the long bones but especially in the pelvis, and the shock and hypotension that can quickly ensue.

Other complications include delayed and non-union of fractures as well as mal-union. In adolescents, injury to the growth plate can be a complication as classified by the Salter–Harris classification where Grades 1 and 2 can be treated conservatively but Grades 3, 4 and 5 need special consideration and possibly orthopaedic surgical intervention. The risk of injury to the growth plate can result in asymmetrical growth and lead to malalignment and disproportionate growth within joints and long-term complications. Avulsion fractures are unique to the adolescent age group and do not need surgical correction unless there is a significant fragment or displacement. Most can be treated with conservative therapy.

image Articular cartilage injury

The articular cartilage is the smooth, shiny covering on the ends of the long bones that allows smooth movement of the joints by reducing friction and providing protection for the bones through shock absorption. The articular cartilage lacks any vascular, nerve or lymphatic supply and as a result has limited tissue repair capacity and is dependent on the exchange of synovial fluid for nutrients and oxygen. The cartilage is made up of chondrocytes which produce a matrix of collagen and proteoglycans which attract water into the cartilage providing 70% of its total volume. On weight-bearing, the water content is compressed back out into the joint hence the shock absorbance effect. The lack of nerve supply means that injuries to the articular cartilage may be pain free. Injuries may occur acutely due to trauma injuring the articular cartilage but also can occur slowly as a form of repetitive small injures causing ‘wear and tear’ injuries that may progress to osteoarthritis. Acute and minor injuries to the articular cartilage are more commonly diagnosed now due to the imaging techniques of MRI and increasing availability of arthroscopy. Asymptomatic lesions are increasingly being diagnosed in arthroscopy. The importance of diagnosing these lesions is primarily that they can progress to further damage of the joint and osteoarthritis. Injuries can occur by dislocation, contusion and compression of a joint and malalignment of a joint can be a contributing factor for repeated micro trauma.

There have been several grading classifications of articular cartilage injuries and these follow two formats.

The first classification is defined by the depth of the lesion, usually best seen on imaging, and is divided into:

Alternatively, grading can be made according to the arthroscopic appearance as follows:

The symptoms of articular cartilage injuries depend on the site, the most common lesion areas being the articular surfaces of the talus, femoral condyles, patella and capitellum of the humerus. The patient may present with a history of distortion or dislocation and there may be swelling or bleeding or an effusion of a joint. Pain is precipitated by movement of the joint and there may be a catching or locking feeling on joint movement. Crepitus may be heard or felt.

The physician needs to have a high index of suspicion for osteochondral lesions and progress to imaging with a view to arthroscopy. Acutely, the bleeding within the joint can be drained and cleaned out and removal or fixing of the osteochondral fragment can be beneficial. In chronic situations where this has occurred over a gradual period of time, MRI scans can give an idea of whether the fragment is stable or unstable. A stable lesion is one where there is Grade 1 or 2 classification with no evidence of any fluid-filled cleft beneath the fragment that may imply that it is going to become dislodged. A Grade 3 or 4 lesion would suggest instability and will need arthroscopy. A stable lesion will require 6 weeks of low-impact rest or non-weight-bearing rest with a range of movement exercises and strengthening exercises followed by a graded rehabilitation programme. Unstable lesions require arthroscopy where debridement of loose cartilage is followed by drilling, microfracturing or abrasion of the defect. The idea of this is to encourage trauma to the subchondral bone which bleeds into the defect creating a fibrous repair. If this is unsuccessful, then further tissue engineering with either autologous chondrocyte transplantation or perichondrial and periosteal grafting may be indicated. The recovery from this is slow, as there is a significant period of several months of non-weight-bearing; however, some grafting results have been promising.

Ligamentous injuries

Ligaments provide stability to a joint, together with the joint capsule. Both are made of connective tissue and the capsule is thickened at points of stress to form a ligament. Ligaments are not contractile tissue but provide an end-point to extreme range of motion. When a joint is moved beyond its normal range of movement or a load is applied to it that is excessive, then the ligament fails and tears rather than causing injury to the attached bone. Ligament injuries are graded one to three depending on the amount of fibres within the ligament that are damaged. The greater the number of fibres the higher the instability of the joint as a result.

The patient may sustain a valgus or varus injury to the joint associated with bruising, swelling and tenderness along the joint line. The ligament itself may be tender on palpation and most noticeable is the degree of instability or laxity of the joint on stress testing.

Management involves the RICE regime with support, possibly a brace. Grades 1 and 2 injuries involve conservative treatment including electrotherapeutic modalities, joint mobilisation and soft tissue massage to promote tissue healing, prevent joint stiffness and protect against further damage. Recovery can be anything from 10 days to 2 months, depending on the severity of the injury. Rehabilitation involving strength, stability and proprioception are vitally important. Grade 3 ruptures used to require surgical reconstruction as well as bracing; however, there is a movement towards bracing and conservative treatment, especially involving the medial collateral ligament of the knee. Some ligaments, however, are not amenable to primary surgical repair and require a graft, such as the ACL which can be grafted with hamstring, patella tendon or donor grafts.

Muscle injuries

Muscle injuries can exist in two forms, either as a strain or tear or as a contusion or haematoma. Tears occur when the muscle fibres fail to cope with the overstretching or eccentric overload put onto them. This occurs most commonly in the musculotendinous junction and usually occurs when there is changeover between the eccentric and concentric contraction of the muscle that occurs during explosive muscular effort. Tears more commonly affect a muscle that spans two joints, such as the hamstrings, the rectus femoris of the quadriceps and the gastrocnemius muscle. This is because the muscles cannot perform two functions at the same time that are governed by a sensitive neuromuscular system. Other factors that predispose to muscle strains include inadequate warm-up and preparation of the muscle, and previous injury to a muscle involving inadequate rehabilitation; however, even muscles that have been adequately rehabilitated are at more risk of injury as can be seen by recurrent hamstring injuries. Muscles that are fatigued, overused or have inadequate recovery, muscles that are excessively tight or have faulty biomechanics as well as those who have muscle imbalance and therefore are consequently overloaded, are at risk. Muscles that have inadequate neuromuscular input such as those with neurological or spinal dysfunction are also at risk.

imageLike ligaments, muscle strains and tears can be classified into three grades:

The patient may complain of a sharp or stabbing pain at the moment of injury that is reproduced on resisted contraction of the muscle. The severity of the injury can be diagnosed clinically as listed above but, often, imaging is required to be absolutely sure.

Management of the muscle strains requires first aid to minimise bleeding, swelling and inflammation and subsequent treatment promotes efficient scar formation through the use of strengthening exercises, soft tissue therapy and stretching. Adequate strengthening exercises as well as addressing biomechanical and postural defects are important to prevent recurrence.

image Muscle contusions and haematomas

A direct impact on a muscle causes a contusion resulting in injury, rupture and bleeding deep within the muscle fibres. Direct impacts are most common in collision sports and most commonly occur at the front of the thigh and the quadriceps muscle. They are otherwise known as ‘corks’ or ‘Charlie Horse’. During activity the blood supply to the muscles is vast and when a muscle is damaged a significant amount of bleeding occurs. A haematoma can develop between the muscle groups when a muscle fascia and its blood vessels are damaged. This is known as intermuscular haematoma. On these occasions, the bleeding that occurs disperses quickly within the fascial layers and typically bruising and swelling appear distally to the damaged area within 48 h of the injury, caused by gravity. There is no increased pressure within the muscle group and swelling is temporary and muscle function is rapidly restored. Conversely, if haematoma is confined within a muscle group, this is called an intramuscular haematoma. Swelling can occur within a muscle itself and is accompanied by tenderness, pain and impaired mobility. There is often less bruising and muscle function can be dramatically impaired. In an acute situation this can lead to acute compartment syndrome although this is rare.1

Management of a contusion involves minimising the bleeding and swelling and historically this has involved rest, icing, compression and elevation. Evidence suggests, however, that compression with the muscle on a stretch, such as keeping the knee flexed, may encourage the dispersal of the haematoma and a more rapid return to play.

The patient may complain of acute pain within a muscle group and the muscle itself may be totally dysfunctional requiring the player to come off the pitch. Quite rapidly there may be reduction in range of movement, and a reduction of knee flexion to less than 90° may imply an intramuscular haematoma. The importance of an intramuscular haematoma not only signifies a more prolonged recovery programme but these haematomas are at risk of complication in the form of myositis ossificans. This occurs when a haematoma calcifies and is most common following intramuscular haematomas. They are also more common when a haematoma is subjected to massage within the first 48–72 h of a muscular injury and therefore massage should not be used. Myositis ossificans should be suspected in a muscle contusion that does not resolve in a normal time frame. It may be diagnosed either by X-ray, which shows calcification, or at an earlier stage by ultrasound, which can also show organisation of the haematoma with calcification. Management of myositis ossificans is conservative and is felt to be due to the presence of osteoblasts and osteoclasts within the haematoma that try to form bone within the haematoma itself. Generally, the haematoma is more painful and enlarges and can cause nerve impingement on surrounding nerves. The management is conservative and avoidance of further trauma by offloading and protecting the area. Early surgical excision can be counterproductive in that this can reform and cause further problems. Treatment involving bisphosphonates has had limited success in some studies. Return to sport can occur when the area is no longer tender and the muscle has regained its full function. This can take up to 8 weeks.

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Jul 18, 2016 | Posted by in SPORT MEDICINE | Comments Off on Musculoskeletal injury

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