MLS Master Class - Veterinary Imaging Presented by CelticSMR Ltd Free Phone (UK): 0800 279 9050 International: +44 (0) 1646 603150 AUTHOR DETAILS Carl Gorman BVSc MRCVS PUBLISHER DETAILS Mike Howe B Vet Med MRCVS celticsmr.co.uk SPRAINS AND STRAINS Key words: Laser, sprain, strain, lameness, tendon INTRODUCTION Sprains and strains are common injuries in dogs, especially working or athletic dogs. They are less common in cats, but still occur. Specific diagnosis can be difficult as we have to rely on palpation and manipulation to identify affected tissues. Management of these injuries involves a range of advice and therapies. DEFINITION Both sprains and strains affect joints and soft tissues of the musculoskeletal system. The signs of both types of injury are very similar, and the terms are often used interchangeably. Often this is not important, but for some severe injuries it can be useful to differentiate between them. Both sprains and strains involve tearing of soft tissue associated with a joint. A sprain is an overstretching or tearing of ligaments. In humans, the ankle is the joint most often affected. A strain involves tearing and overstretching of muscle or tendon. For humans, hamstrings and back muscles are often affected. If a sprain or strain is so severe that it results in the total disruption of a ligament, tendon or muscle, that is a rupture. Ruptures almost always require surgery to allow healing, while most sprains and strains will heal with time, rest and therapy.
CLINICAL SIGNS Lameness is the principal clinical sign. This will often be an acute lameness which occurs at exercise. This may improve as the initial pain of the tearing injury subsides, but will become worse as the secondary inflammation and swelling develop. Both sprains and strains display similar clinical signs, and the terms are often confused or used interchangeably. Common clinical signs in joints affected by sprains and strains: Pain Swelling (Fig 1) (Fig 2) (Fig 3) Fig 1 A strained gastrocnemius tendon (Achilles). Note the swelling compared the normal tendon in the left leg (Fig 3). Fig 2 Close up of the swelling in the gastrocnemius tendon.
Fig 3 Normal gastrocnemius tendon. Limited flexibility Reduced range of motion (Where there is a rupture there will an abnormal, excessive range of movement) Additional signs of a sprain: Bruising Additional signs of a strain: Muscle spasm COMMON SITES FOR MUSCLE STRAINS The iliopsoas, gracilis, quadriceps and hamstrings are common sites for strains in dogs. In human sports medicine, it is estimated that 50 per cent of injuries are due to strains of muscles and tendons, and we can assume that dogs suffer similar levels of injury. These injuries are probably poorly or under diagnosed in veterinary medicine because they are not recognised. We have to rely on careful examination and identification of the affected muscle, without the input of the patient, unless we cause acute pain. (Fig 4)
Fig 4 Xray of a strained gastrocnemius. Note the swollen lower end of tendon where it inserts into the calcaneus. There is an enthesiophyte (calcification) in the tendon insertion, suggestion a more chronic strain injury at this site. COMMON SITES FOR SPRAINS All joints may be affected by sprains, but commonly the cruciate ligaments, medial collateral ligaments of the stifle, and ligaments of the digits and carpi are vulnerable. (Fig 5) Diagnosis of sprains is easier than strains, especially in distal limb joints, as pain and reduced range of movement can be demonstrated. Sprains of upper limb joints may be harder to detect. Early sprains of cruciate ligaments may be difficult to diagnose with confidence. Fig 5 The cranial cruciate ligament is a common site for a sprain.
CLASSIFICATION Sprains and strains may be graded according to their severity: Grade 1 (mild) Slight stretching and some damage to the fibres Grade 2 (moderate) be loose when manipulating it. Partial tearing of the fibres. Where this affects ligaments, the joint may be felt to Grade 3 (severe) Complete tearing of fibres. Also known as a rupture. If ligaments are affected the joint may be very loose, subluxate or luxate. (Fig 6) Where muscles or tendons are ruptured you may feel bunched tissue where the muscle has pulled and contracted from its insertion. Fig 6 dog's paw. A grade 3 strain (rupture) of the digital flexor tendons, resulting in hyperextension of this CAUSES OF SPRAINS AND STRAINS The cause of sprains and strains are stretching and tearing of muscle fibres, tendons and ligaments. This may be due to over-stretching, repetitive strain on the tissues or twisting. These injuries are often exercise induced. As a result, they are common in working dogs and sporting dogs, however even pets which habitually don't exercise much can suffer sprains and strains. There are a number of factors which can predispose to these injuries Predisposing factors 1) Fitness Unfit animals which undertake vigorous exercise are at risk. Muscles and joints may not have the flexibility or resilience to cope with the extra demands.
2) Weight Overweight pets are likely to be unfit, and will also put undue stress on their muscles and joints due to extra load. 3) Previous injuries Muscles, tendons and ligaments which have been damaged before will have healed but the tissue fibres in the repaired areas will be less flexible and usually less strong compared to the original tissue. These weak areas will be more prone to damage. The more recent an injury, the more likely that the healing area will be susceptible to further damage. 4) Other injuries When a limb is affected by a disorder, an animal will compensate by taking more weight on the remaining limbs. This will place extra stress on the soft tissue in those limbs and may make injuries more likely. Disorders of the back may similarly result in extra force being placed on certain limbs. 5) Anatomical anomalies Changes from the normal anatomy of a limb, which may be congenital or acquired, will put extra stress on soft tissues. The chronic nature of the abnormal forces will eventually result in injury. Examples of anatomical causes i. Stifle conformation may lead to anterior cruciate ligament injuries ii. Shallow patellar grooves can cause stretching and possibly rupture of the collateal patellar ligaments. iii. Bowing of long bones puts abnormal forces on muscles and tendons iv. Fractures which have not healed in perfect alignment will place abnormal forces on the muscles associated with that limb. 6) Other disease processes Some endocrine disorders may result in weaker muscles and tendons, making injuries more likely. Hyperadrenocorticism (Cushing's syndrome) is one example. One of the side effects of chronic corticosteroid overdose is muscle loss, and another is weight gain. Long term treatment with corticosteroids will have the same effect. Hypothyroidism will reduce fitness and muscle strength as well as cause weight gain, again making soft tissue injuries more likely.
TREATMENT The goals of treatment for sprains and strains are: Relief of pain Resolution of the acute changes in the damaged tissues Rehabilitation and strengthening of the repaired tissue Prevent secondary complications Return to normal use ANALGESIA These injuries are painful, as can be seen by the way an affected animal reduces its use of the affected limb, and resents palpation and manipulation of the affected area. There are several approaches which can be taken to deliver analgesia. Non-steroidal anti-inflammatories NSAIDs are the mainstay of analgesia in veterinary practice. They are effective pain relievers, familiar drugs and have anti-inflammatory effects which help to resolve the acute changes in sprain and strain injuries. Opiates Opiates are powerful analgesics, and are indicated if the pain from an injury is not controlled by NSAIDs. Ice Icing an injured joint will aid with analgesia and reduce swelling. It should be used during the first 72 hours after an injury - the acute phase. How well icing is tolerated will depend on the type of patient and its temperament. Ice packs or packs of frozen vegetables, wrapped in a teacloth or pillow case are suitable. Ice should be applied for 8 to 10 minutes if tolerated, and should be used every 2 to 3 hours, or after exercise. Heat Application of heat is useful after the acute phase, i.e. after the first 72 hours. Applying heat to an injured joint reduces pain and improves blood flow. Heat will also relax contracted tissues and increases the elasticity of connective tissue. Heat can be used before and after exercising a joint.
Support It may be appropriate to immobilise an injured joint or to apply pressure with a dressing to reduce further injury, relieve pain and control swelling. Bandaging will interfere with the application of other treatments, and so would normally be only used during the acute phase following an injury unless the joint was unstable. Surgery This is normally reserved for cases of Grade 3 injuries, where the structures have ruptured. Surgical repair may be necessary before any meaningful healing can take place. Ultrasound Ultrasound treatment is not widely available in small animal practice, but is often used in human physiotherapy. Ultrasound waves heat the target tissues gently, enabling chemical reactions, improving blood flow decreasing spasm and breaking down adhesions. Laser Therapeutic laser has multiple benefits in the management of sprains and strains. We have learned the mechanisms at work when tissues are stimulated by laser. In the short term, therapeutic laser will reduce swelling and relieve pain. (Fig 7) Fig 7 Laser therapy of the strained gastrocnemius seen in Fig 1. As recovery progresses, laser therapy will allow faster and stronger repair of the damaged soft tissues. Several studies in lab animals show that tendon repair is enhanced by laser therapy with stronger tissues once healing has completed. Blood supply to damaged tissue is improved, and the quality of repaired tissue is better. Treated tendons had more Type 1 collagen compared to Type 3. Type 1 collagen is stronger and more akin to the original tissue type. Normally when ligaments and tendons heal they form disorganised scar tissue at the site of injury. This is less flexible and more easily damaged than the original tendon. Where laser has been used, the healed fibres are more organised and more similar in structure to the original tissues.
Physical therapy Physiotherapy, including massage, controlled exercise and hydrotherapy, is increasingly recognised as an important part of the management of musculoskeletal injuries. In the acute phase massage of oedematous acutely inflamed joints will help to reduce swelling and improve comfort. As inflammatory processes settle down, range of motion exercises help to counteract contraction of ligaments and tendons and maintain a normally functioning joint. Controlled exercise and hydrotherapy restore muscle strength and function, while placing controlled stress on healing ligaments and tendons helps produce more organised and strong repair. This is important to restore full function after recovery. PRACTICAL LASER THERAPY Laser should be introduced as soon as practical following an injury. Acute phase This is characterised by swelling and marked pain. Laser energy levels should be reduced as overstimulation of tissues may cause more discomfort. Remember that it is possible to reduce intensity levels, e.g. to 50%. Suitable settings are: Acute inflammation Acute pain Oedema Treatment should be administered every 1 to 2 days until the swelling reduces and pain is controlled. Aim the probe over the injured tissue. Scanning mode is normally appropriate unless the affected area is small, e.g. a toe, in which case point mode can be used. Recovery phase Once the initial pain and swelling are controlled, the ongoing aims of treatment are to continue relieving pain and reducing inflammation, and to encourage healing and healthy repair. Suitable settings are Sprains and strains Chronic pain
Chronic inflammation Look for secondary problems in the muscles associated with injured joints. (Fig 8) Contracted muscles (taut, tense muscles) or trigger points may be identified. Treating these secondary problems will improve comfort. Use these settings: Muscle contracture Trigger point Fig 8 Laser therapy of the biceps tendon and muscle. Treatment should be administered twice weekly, possibly reducing to weekly in longer standing injuries such as cruciate ligament tears, iliopsoas strain, or shoulder injuries. Continue until good use of the leg is restored. (Fig 9) Fig 9 Laser therapy of a carpus sprain.