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Physical Therapy Darryl L. Millis, MS, DVM, Dipl ACVS Professor of Orthopedic Surgery University of Tennessee College of Veterinary Medicine Physical Rehabilitation Techniques and Practices Much attention has been directed to the preoperative and operative management of surgical patients, but very little attention has been focused on the postoperative rehabilitation of veterinary patients. Physical therapy in human patients is common and well accepted. Until recently, there has been little study of physical therapy of animals. Advances in the management of people receiving physical therapy have allowed us to adapt some of the techniques and procedures to small animals. Although there are many potential situations in which physical therapy may be used in animals, this discussion will primarily concentrate on orthopedic and neurologic patients. ESTABLISHING A PHYSICAL REHABILITATION TEAM Veterinary technicians and veterinarians receive virtually no training in physical therapy techniques. Similarly, physical therapists do not receive training in veterinary medicine. Therefore, it is important to develop collaborative working relationships to advance the care of postoperative veterinary patients. The AVMA House of Delegates passed guidelines for alternative and complementary veterinary medicine in 1996 which state that veterinary physical therapy should be performed by the veterinarian, a licensed veterinary technician, or a licensed physical therapist educated in animal anatomy and physiology under the supervision of a veterinarian. Collaborative efforts are also supported by the American Physical Therapy Association. Therefore, although postoperative rehabilitation of veterinary patients is supported by both professions, clearly there is the need for collaborative relationships to provide the best therapeutic plan possible. It is beneficial to locate a physical therapist who has an interest in working with animals to instruct veterinarians and veterinary technicians on the proper use of therapeutic modalities. CONSIDERATIONS IN THE PHYSICAL REHABILITATION PATIENT Factors affecting the type of physical therapy include the age and physical condition of the patient, the nature of the surgical condition, concurrent injuries, owner compliance, and the training and expertise of the rehabilitation team. Whenever possible, preemptive pain management should be instituted to allow physical therapy to be administered to a patient that is as comfortable and pain free as possible. Butorphanol and morphine are commonly used in our hospital to provide immediate postoperative analgesia, and carprofen or etodolac may be administered for chronic use. Massage Massage is the gentle manipulation of superficial and deep soft tissues, followed by later vigorous cross fiber massage of deep tissues. Massage prevents adhesions of muscles, tendons, and ligaments; reduces muscle spasm, edema, and joint stiffness; and improves soft tissue relaxation, muscle flexibility, venous and lymphatic flow, and local blood flow. In addition, dogs seem to enjoy massage and become more relaxed for the remainder of the therapy session. Owners who perform massage during home care programs also feel very favorable about the process. Frictional massage is performed by using small, deep strokes with the tip of one finger, sometimes reinforced by a second finger. The massage is performed in the direction of tissues or in circular strokes, moving skin and underlying tissue together to loosen tissue. Transverse friction massage is performed perpendicular to tissues, such a tendon sheath. Effleurage is massage performed with strokes parallel to the muscle fibers and heavier toward the heart. Petrissage is stroking muscles with a kneading or rolling motion either toward the heart or transversely to muscles. Hand massage is performed by using one hand to massage and the other to support the area. Strokes may be linear, circular, or applying direct compression, while directing strokes toward the heart for venous return. Stretching and Range of Motion Exercises In the acute injury phase and immediately following surgical procedures, full pain-free use of the joints may be limited. Local edema and joint effusion may limit joint motion mechanically. Joint pain and reflex inhibition may also limit motion. It is very important to reestablish full range of motion (ROM) as soon as possible. Animals may have permanent loss of motion in as little as two weeks after some surgical procedures, which ultimately limits an animal's functional ability in the future. Proper technique is vital in performing stretching and ROM. It is essential to maintain comfort of animal. Over-aggressive ROM exercises will result in pain, reflex inhibition, delayed use of limb, more fibrosis of the joint, and possibly a stiffer joint. The key is to stretch and realign soft tissues and collagen, not to rip and tear tissues. Begin by flexing the joint until the first indication of discomfort, and hold for a 10 count while continuing to stretch. Then extend the joint until the first indication of discomfort, and hold for a 10 count while stretching. Repeat for 10 to 30 repetitions, 3 to 6 times daily. Do all joints in the affected limb. Do not try to regain complete ROM all at once; it may take several days to weeks. ROM therapy is especially important for any joint surgery and in young dogs, especially CCLR stabilization, elbow fractures, and fracture of the distal femoral physis. Cryotherapy Cryotherapy, or the application of cold is important following acute injuries or in the immediate postoperative period. Cryotherapy decreases blood flow, and reduces pain, swelling, inflammation, hemorrhage, and metabolic activity. In general, cryotherapy in applied for the first 72-96 hours, for 15-20 minutes, every 4-6 hours following injury or surgery. Cryotherapy is also beneficial for up to 2-4 weeks following therapy sessions. A light pressure wrap between sessions may help limit edema. Although cryotherapy is beneficial for acute soft tissue injuries, fractures, and joint surgeries, it is also sometimes beneficial for chronic conditions because it reduces pain and edema, and it may reduce collagenolysis, synovial inflammation, and joint destruction. Ice packs, commercial cold water circulating units, or commercial cold packs may be used. Crushed ice may be placed in a sealable plastic bag wrapped in a towel. The cold will transfer better if the towel is moistened with cold water. Alternatively, commercially available ice bags or ice packs may be used. We frequently use an inflatable cryotherapy human ankle boot. By inflating the boot using an air pump, compression is applied to the area which also helps to treat swelling. Heat After 72-96 hours, heat applied to the area may be beneficial prior to the therapy session. Heat increases blood flow, tissue extensibility, and general relaxation, while it decreases pain, muscle spasms, and joint stiffness. Superficial heat penetrates 1-2 cm and may be applied using commercial hot/cold packs, warm moistened towels, or towels or packs which have been heated in a microwave so that they are warm (but not hot) to touch. Circulating warm water blankets may be used for large areas or for long-term heating, but electric heating units should not be used. Apply moist or dry heat for 10 min prior to a session. Be cautious in applying heat to areas with reduced sensation, or in animals that cannot move away. Heat application may increase swelling/edema if used too early. Although warm packs/towels are effective for superficial heating, there are situations where deeper heating is desired. In these cases, therapeutic ultrasound is useful in heating deeper tissues. Ultrasound penetrates up to 5 cm, and heats tissues to 40-450 C. The continuous mode is used for heating. Therapeutic ultrasound typically uses 1 or 3.3 MHz transducers with 1, 2 or 4 cm transducer head sizes. 3.3 MHz transducers are effective for heating more superficial tissues, while 1 MHz is used for deeper tissues. In addition to the benefits of heating tissues, ultrasound may also increase collagen deposition, wound closure, and wound breaking strength. Therapeutic Ultrasound Ultrasound (US) is a commonly used modality in physical therapy, and has been shown to be effective for many purposes including increasing collagen extensibility, increasing blood flow, increasing range of motion (ROM), decreasing pain and muscle spasm, accelerating wound healing, and enhancing transdermal administration of medication (phonophoresis). Therapeutic ultrasound is produced by applying an electrical current to a crystal, causing it to vibrate at its resonant frequency. These oscillations of the crystal cause pressure waves to be emitted, which are subsequently absorbed by the tissues. The two most commonly used US frequencies are 1.0 MHz and 3.3 MHz. The 1.0 MHz US penetrates more deeply and is used for heating tissues from 2.0-5.0 cm in depth. The 3.0 MHz US is used to heat tissues from the skin to a depth of 3.0 cm. Precautions/Contraindications to US There are certain conditions in which US should not be used, or should be used with caution. -Directly over the heart or in animals with pacemakers -Over areas where thrombophlebitis is present (or any risk of embolus) -Over infected areas or neoplasms -Over the carotid sinus -Over a pregnant uterus -Over the epipyseal area of growing bones -Over the spinal cord post-laminectomy -Over analgesic areas -Myositis ossificans -Plastic and metal implants Thermal Effects of US 1. Increased metabolic rate of tissues 2. Increased blood flow 3. Increased extensibility of collagenous tissue (tendon, scars, contracted joint capsule) leading to decreased joint stiffness 4. Decreased pain and spasm Non-thermal/Mechanical Effects of US 1. Increased cell diffusion and membrane permeability 2. Increased calcium ion transport 3. Facilitates the inflammatory process (release of histamine) 4. Increased glycosaminoglycan synthesis 5. Increased fibroblast proliferation 6. Increased intracellular calcium 7. Increased collagen content Intensity Rate at which energy is delivered per unit area, typically expressed in Watts/cm2 (Watts/area of the transducer head). The higher the intensity, the greater the heating effect. An intensity of 1.0-2.0 W/cm2 is generally used for areas with a large amount of soft tissue such as the caudal thigh muscles or the lumbar muscles of medium and large breed dogs. 0.5-1.0 W/cm2 should be used for areas like the carpus where there is relatively little soft tissue and underlying bone close to the US field. As bone reflects US waves, excess heating can place if the intensity is too high. To ensure that the intensity is accurate, US machines should be calibrated on a yearly basis. Continuous Versus Pulsed Ultrasound Although both continuous and pulsed US produce thermal and nonthermal effects, pulsed US produces predominantly non-thermal effects, as the average energy is much lower. In continuous the heating effect is much greater. When maximal thermal effects of US are desired, the continuous mode should be used. When the healing effects of US are desired with a minimal thermal effect, pulsed US should be utilized. Coupling Agents The purpose of coupling agents is to eliminate any air between the skin and the US transducer, thereby maximizing the transmission of US into the body. Cameron showed that water-soluble gels transmit the maximal amount of US. Caution should be used when performing US through media not prepared for its transmission. Ashton, et al, showed that little heating occurs when US is performed through media not made for US transmission such as Flex-all. Water may also be used as a coupling agent, and is recommended when performing US over irregular surfaces such as the interphalangeal joints. In this circumstance the dog can simply stand in water or have the limb placed in a basin of water for the US treatment. No additional precautions are need for underwater US treatment, however the intensity should be increased by 0.5 W/cm2 as water is not as effective as a coupling media as gel is. The US transducer should be held 1-2.0 cm away from the body part during underwater US. Animal Reaction/Safety Precautions should be taken to avoid injury to the handler and animal. A muzzle should be applied and the animal placed in lateral recumbency if possible during the initial treatment. In some cases, tranquilization may be necessary if the animal is anxious. We recommend that treatment only be given under the supervision of trained personnel. Unless US is properly used, it has the potential to cause tissue damage such as dermal necrosis or overheating of the deeper tissues leading to inflammation. Pain experienced during US is usually observed by a withdrawal of the limb or other signs such as whimpering which are most likely caused by overheating. US should be discontinued immediately if these responses are noticed, and the parameters adjusted before continuing treatment. Preparation of Treatment Area The hair over the area in which US will be appliedmust be closely clipped for adequate transmission. Steiss & Adams demonstrated a significant reduction in the thermal effect when coat hair was not first clipped. The skin should be cleaned with alcohol prior to treatment to remove any dirt or oils from the skin. After preparing the skin, gel is applied, and the treatment performed. Treatment Time/frequency Treatment time depends on the size of the area to be treated, and the size of the transducer head. Estimate how many transducer heads will fit into the treatment area. For each two heads, five minutes of US is applied. For larger areas, it is advantageous to use larger US transducers to save time. Treatment can be applied daily as long as it appears to be of benefit, with a maximum of 10 treatments recommended before taking a week off. Treatment will still be of benefit if given less frequently than daily and 2-3 times/week is commonly utilized for frequency of treatment. Rate and Pattern of Movement The US head should be slowly moved at a rate of approximately 4cm/sec. This allows effective heating without damaging the tissue from overheating. The angle of the US beam needs to be less than 15o to the surface for effective transmission. The US head can either be moved in a overlapping circular pattern (Fig 1), or in longitudinal stokes (Fig 2). Holding the transducer head in one spot for too long is a common cause of pain due to overheating of the tissues. Uses -Decrease Pain -Decrease Spasm -Increased Extensibility of collagen -Increase ROM/decrease stiffness -Increased Blood flow/Metabolic rate of tissues -Fracture Healing -Calcific Tendonitis -Improve Function THERAPEUTIC EXERCISES AND PROTOCOL DEVELOPMENT
Therapeutic Exercises The goals of therapeutic exercises are to improve active pain-free range of motion, improve use of limb, reduce lameness, improve muscle mass and muscle strength, improve daily function, and help prevent further injury. Common activities include standing exercises, slow walks, stair climbing, treadmill activity, wheelbarrowing (for forelimb activity), and dancing (for rear limb activity). Other activities include jogging, sit-to-stand exercises, pulling or carrying weights, walking and trotting across cavaletti rails, playing ball, taping a bottle or syringe cap to the bottom of the good foot, slinging the contralateral good limb, and using balance balls or Physiorolls. Standing Exercises Standing exercises are performed for animals with bilateral pelvic and neurologic injuries. Place the dog with all four feet squarely underneath, then support the affected body part with a towel or Walkabout sling to support the body and let the animal try to support weight. When the dog slowly collapses, pull it back up, then repeat the exercise. Start with 10-15 repetitions bid-tid, and gradually increase to 5 minutes per session. Slow Walks Slow walks are perhaps the most important exercise in the early post-op period. The walks must be at a speed to encourage weight-bearing; if the dog is walked too fast, they will carry the limb. Behavior modification is important. The dog should be praised when touching the limb down, and not praised when the leg is held up. Walks up and down inclines and hills will help to strengthen muscles with relatively low-impact activity. Stair Climbing Climbing stairs is useful to improve power in the rear limb extensors. Stair climbing may start if the repair is stable and the dog is consistently using the limb at a walk with progressively decreasing lameness. The dog must begin slowly climbing stairs to encourage proper use of the rear limbs, as opposed to simply carrying the limb while climbing stairs. Begin with 5-7 steps, and gradually increase to 2-4 flights of stairs sid-tid. Treadmill Activity Treadmill activity is very useful in rehabilitation. Most dogs trained to a leash readily take to treadmill walking. A variety of treadmills are available for dog use, including commercial canine treadmills. A harness is useful to help support the dog in case it stumbles or falls. Side fences placed alongside the treadmill are useful if a dog tends to step off to the side. Other useful features include a variable speed control, timer, and the ability to change the incline of the surface. Treadmills are very useful for patterning gait, encouraging early use of a limb when the foot is carried near the ground. It is important the treadmill does not face toward the wall; it should face toward a hallway or the middle of a room to encourage unimpeded walking. One person standing in front of the dog with words of encouragement or treats, and one person straddling the dog behind are helpful in the early training stages to keep the dog walking straight. Although the ground moving underneath the dog often encourages a nonweight-bearing dog to begin using limb, a person can stand beside a dog and manually advance a foot during the normal gait sequence to encourage gait reeducation. A syringe cap placed on the bottom of the good foot often encourages weight bearing. A sling may be used to support a paraparetic animal. The treadmill may be angled up or down to reduce or increase the stress placed on the forelimbs or rearlimbs. Treadmills help reduce the stress and pain of limb movement in some conditions, such as extension of the hips or knees. Extension of these joints is passive because the treadmill pulls the limb into an extended position. Dancing and Wheelbarrowing Dancing is a technique to increase weightbearing and stress on the rear limbs. Muzzle dogs prior to exercise. The forelimbs are lifted off the ground. Dogs with normal proprioception will naturally move the rear limbs as the animal "dances" backward. Dogs will also dance forward, but some dogs may simply try to put the forelimbs down. In this situation, get behind the dog, place your arms under the axillary region to support the dog, and walk forward. Dogs may also dance up and down inclines. Wheelbarrowing is a technique to increase weightbearing and stress on the forelimbs. It is recommended to muzzle the dog. The rear limbs are lifted off the ground and the dog is moved forward. Dogs with normal proprioception will move the forelimbs so they do not fall. Some dogs may require sling support if they are weak. Dogs may be wheelbarrowed up and down inclines for greater muscle strengthening. Jogging Jogging may be initiated in cases with stable repairs when the dog is walking on the limb with minimal pain. Begin slowly with 0.5-3 minutes bid-tid, and work up to 20 minutes bid-qid. Be certain lameness is not worse after jogging. Sit-to-Stand Exercises Sit-to-stand exercises help strengthen hip and stifle extensors. Some training will be necessary, and low calorie treats may be offered as a training aid. It is important to correctly perform these exercises. Attention should be paid to sitting and standing straight, with no leaning to one side, and both rear limbs should be flexed so that the dog sits squarely on its haunches. It may be easier to back the dog into a corner, with the affected limb next to a wall so that the dog cannot slide the limb out while rising or sitting. Start with 5-10 reps sid-bid, and work up to 15 reps tid-qid. Cavaletti Rails Cavaletti rails are poles which are spaced apart on the ground at a low height. They are useful to help dogs lengthen their stride, flex their joints, and regain appropriate proprioception. Begin with walking and progress to trotting. The rails may be raised to encourage greater active flexion and extension of joints, and the distance between the rails may be altered to encourage dogs to negotiate different situations. Pulling/Carrying Weight A variety of harnesses are available for dogs to attach to carts or sleds for pulling weight. The harness should be well padded and comfortable. Pulling a cart with a large wheel diameter will be easier than pulling a sled which slides along the ground. The position of the head and neck are important in determining whether a dog pulls the weight forward with the forelimbs or the hind limbs. If the dog carries its head and neck low to the ground, it is likely pulling with the forelimbs. A dog with the head and neck held high will shift some of the weight caudally and will tend to use the hind limbs to drive the body. Dogs may also perform chronic "weight lifting" by wearing a canine backpack filled with weights. Weights may be loaded unequally or equally on both sides. Controlled Ball Playing Ball playing is a fun and effective form of therapeutic exercise. It also has the potential to cause damage to surgical repairs. Controlled activity is the key. The degree of activity depends on the surgical procedure performed, the condition of the tissues, and the stage of tissue healing. Ball playing should begin on a relatively short leash to avoid explosive activity in the early post-operative period. As the patient progresses, the dog graduates to ball playing in an enclosed area, such as a run. As the animal nears full return to function, off-leash activity may be performed in a field free of irregular surfaces. Methods to Encourage Weightbearing A syringe cap or coin may be placed on the bottom of the contralateral foot and held in place with adhesive tape to encourage weightbearing on the affected limb. In many instances, weightbearing continues on the affected limb even after the item is removed from the good foot. Some dogs will build up a tolerance to the item; therefore, continuous application is not recommended. In some particularly difficult cases, a sling may be placed on the contralateral limb to coerce the animal to bear weight on the affected limb. Aquatic Therapy Water has useful features for rehabilitation, including thermal effects, buoyancy, increased hydrostatic pressure, cohesion, and turbulence. The benefits of aquatic exercise are many. Heart rate and oxygen consumption are greater when doing exercises in water. Patients with poor balance can stand because buoyancy will help keep patients from falling. Patients unable to bear full weight on joints can walk, and patients with weak muscles can move body parts. There are many indications for aquatic therapy. Contraindications include cardiac or respiratory dysfunctions, decreased thermal sensation, severe peripheral vascular disease, danger of hemorrhage, infections, incontinence, and diarrhea. Aquatic exercise should be initiated only after incisions are sealed and there is no drainage. Activity must be supervised at all times. Also, some dogs and most cats may thrash and hurt themselves. If possible, training should begin in water prior to surgery. Warm water (85-90 F) should generally be used. Dogs may be lowered into a pool or tub using a Hoyer-type lift. In the early phases of rehabilitation, the therapist should provide support to the patient or canine life preservers may be applied. Many patients will be in poor cardiovascular condition, and 2-3 minutes of aquatic therapy may tire some patients. Over the course of 10-14 days, therapy may increase to 10-15 minutes per session. Water wings or styrofoam balls attached to a limb may increase resistance and work that the limb must perform during aquatic therapy. Whirlpools, swimming pools, bathtubs, sinks, lakes and streams, and underwater treadmills may be used for aquatic therapy. Whirlpool tanks are stainless steel, plastic, or fiberglass tanks with an agitator. They must be thoroughly cleaned between patients. Large, deep tanks allow swimming by all but the largest dogs. Hubbard tanks are large keyhole-shaped tanks that allow a larger area for walking or swimming, but require a larger volume of water. Therapeutic pools and swimming pools are larger and suitable for all size dogs. There must be a mechanism to get the dog into the pool, such as a ramp, lift, etc. Some dogs, especially early in the rehabilitation period, may use either the front or rear limbs to swim and only float the injured limb. Pools should be equipped with a chlorinator, heater, and heater heavy-duty filters. Underwater treadmills are a relatively recent addition to aquatic therapy. Depending on the water height, patients may walk partially submerged or may swim. Principles of Protocol Development Preoperative Period Postoperative rehabilitation for conditions, such as surgery for cranial cruciate ligament rupture, actually begins prior to surgery. Factors affecting the type of postoperative rehabilitation include the age and physical condition of the patient, the nature of the surgical condition, conquering injuries, owner compliance, and the training and expertise of the rehabilitation team. Whenever possible, preemptive pain management should be instituted to allow postoperative therapy to be administered to a patient that is as comfortable and pain free as possible. Butorphanol and morphine are commonly used in our hospital to provide analgesia. Other techniques include fentanyl patches, carprofen, and etodolac. Many human patients undergoing surgery for anterior cruciate ligament tears begin physical therapy days to weeks prior to surgery in an attempt to strengthen various muscle groups to allow the postoperative therapy to be more effective. Although this is difficult and veterinary patients, some modalities, including range of motion exercises and neuromuscular electrical stimulation, may be instituted prior to surgery in some cases. Immediate Postoperative Period The goals in the early postoperative period should be to decrease inflammation, increased mobility, and prepare the animal for more active use of the limb. Activities which significantly increase pain and discomfort should be avoided because this will actually slow down the return to function. The judicious use of anti-inflammatory and analgesic medications 30-60 minutes prior to the first few sessions will allow the animal to be more comfortable, enhance the recovery period, and allow the animal to increase functional use of the limb. Immediately following surgery, cryotherapy in the form of ice packs wrapped in towels are applied to the surgical site. Commercially available ice packs and cold water circulating devices are also available. The application of cold decreases local blood flow to the area by causing vasoconstriction of the superficial vessels. This reduces the effects of inflammation and hemorrhage, and decreases metabolic rate. The treatment should last for approximately 15 to 20 minutes. Following that, a light pressure bandage may be applied to limit edema and swelling. Cryotherapy should be continued for the next 72 hours, for 15 to 20 minutes three to six times daily. For the next one to three days after surgery, the emphasis should be on limiting inflammation and edema to the surgical site. This is accomplished through continued application of cold, administration of anti-inflammatory medications, judicious use of gentle massage therapy, and range of motion exercises. We generally give anti-inflammatory medications, such as carprofen or etodolac, 30 to 60 minutes prior to instituting therapy. Massage therapy should include gentle manipulation of soft tissues superficially and more deeply. It is important to encourage gentle gliding of the skin over underlying tissues to minimize adhesion formation. Vigorous cross fiber frictional massage may be used in the deeper tissues to help prevent adhesions of muscles, tendons, or ligaments. The beneficial effects of massage include relaxation of soft tissues, decreased muscle spasm, increased muscle flexibility, improved venous and lymphatic flow with reduction of edema, and increased local blood flow to the area. Massage is an excellent way to increase blood flow to muscles to help warmup the area before activity and to decrease stiffness after activity. Range of motion exercises must be performed properly to be effective. To achieve the desired effect, it is important to manipulate the joints to maintain comfort of the animal. Under no circumstances should the animal experience undue pain or discomfort by forcibly flexing or extending joints because this will result in reflex inhibition, delayed active use of the limb, fibrosis of tissues, and ultimately, decreased use of the limb. Each joint in the affected limb should be placed through its comfortable range of motion. To achieve this, the joints should be slowly flexed to the point where the animal first begins to experience mild discomfort. This position should be held for a 10 count to allow stretching of tissues. Following flexion, the joint should be slowly extended to the point where the animal first begins to experience mild discomfort. This position should be held for 10 count. This process should be repeated 15 to 20 times, three to six times daily. The goal of range of motion exercises should be to stretch and realign soft tissues and immature collagen, rather than tearing and destroying soft tissues. Following range of motion exercises, additional massage may be beneficial. Finally, cryotherapy should be performed to help limit swelling. After three days, application of heat to the area may be beneficial prior to instituting massage and range of motion. Superficial heating typically heats the skin and subcutaneous tissues to a depth of 1 to 2 cm. Commercially available hot packs, circulating warm water heating blankets, or towels moistened with warm water (so they are comfortable to your touch) may be applied to the affected area for 10 minutes prior to instituting therapy. Do not use electric heating pads. Local application of heat increases blood flow to the area, decreases pain and muscle spasms, and causes general relaxation. Heat also promotes tissue extensibility of joint capsules, tendons, and scar tissue, while decreasing joint stiffness. Heat should not be applied in swelling or edema are present. Therefore, heat is generally not applied for the first 72 hours because it may actually increase edema formation. Therapeutic ultrasound may be used if deeper heating is desired. Ultrasound is capable of heating tissues 5 centimeters deep to temperatures of 40-45 C. Thermal effects are created by the tissues oscillating at high frequencies and producing heat. Non-thermal effects include increased cell membrane permeability, calcium transport across the cell membrane, removal of proteins and blood cells from the interstitial spaces, nutrient exchange, and phagocytic activity of macrophages. The most common therapeutic ultrasound frequencies in the United States are 1 and 3 MHz, and usually possess different size transducers. Most ultrasound units have two modes, continuous and pulsed. Both thermal and non-thermal effects are produced when the continuous mode is used, but thermal effects are reduced in the pulsed mode. Early Postoperative Period As edema and inflammation begin to subside, the animal is more tolerant to surgical site manipulation, and pain begins to resolve, additional activities may be added to the rehabilitation protocol. These activities include therapeutic exercises, such as standing exercises (for patients with neurologic or pelvic injuries), wheelbarrowing (to encourage active use of forelimbs), dancing (to encourage active use of rear limbs), walks at a slow speed to encourage weightbearing, walking up and down inclines, and treadmill walking. The use of treadmill activity has been very beneficial to our patients and most dogs adapt to it quite readily. Other methods to encourage active use of a limb include playing ball, sit-to-stand exercises (for rear limbs), and taping a bottle or syringe cap to the bottom of the contralateral normal foot. It is important when recommending any type of therapy to muzzle the animal to prevent injury to the handler. Following suture removal and complete sealing of the incision, swimming may be added. For small dogs, a bathtub may be sufficient. If a whirlpool is available, it may also be used for medium to large dogs. Alternatively, a swimming pool, pond, or lake may be used to allow the animal to swim. Some dogs to not tolerate swimming and there is some risk in damaging the surgical repair if the animal thrashes excessively. However, swimming is an excellent means of improving muscle strength and joint mobility in a nonweightbearing environment. If the animal is unwilling to bear weight and actively use the lamb, electrotherapy may be instituted. Neuromuscular electrical stimulation has a wide variety of benefits including increasing muscle strength and joint range of motion, decreasing edema and pain, promoting wound healing, and restoring function. Pulsed alternating current, low frequency units are the most widely used neuromuscular electrical simulators for therapeutic applications. Early use of neuromuscular electrostimulation may attenuate muscle atrophy following surgical procedures. In humans following surgery for anterior cruciate ligament tears, there is a 20-25 % loss of strength of the quadriceps muscles within four weeks. We found that there is significant muscle atrophy in the first two weeks following cruciate transection and repair in dogs. The combination of neuromuscular electrical stimulation, range of motion exercises, and early use of the limb results in attenuation of muscle atrophy in the affected limbs following surgery for cranial cruciate ligament rupture in dogs Chronic Management of the Postoperative Patient In the weeks to months following surgery, the goal should be to restore the animal to full, active use of the limb. Strategies should be designed to encourage increased weightbearing of the limb and increasing muscle mass. Anti-inflammatory medications given prior to activity may help limit pain following exercise. However, prior to significantly increasing activity level (step-up activity), medication should be stopped for one to two days to be certain that the animal is not experiencing additional pain and discomfort as a result of stepping up the level of activity. Additionally, it is extremely important to maintain a consistent level of activity on a daily basis. More harm may come to the animal by over doing activity one or two days a week with relatively no activity during the rest of the week. Weight management should also be a goal in the chronic postoperative period. ASSESSING THE REHABILITATION PATIENT
Assessing the outcome of treatments, including physical rehabilitation, is essential to determine how an animal is progressing and to determine the effectiveness of treatment protocols. Review of outcome data and evaluation of protocols are necessary so that changes may be initiated to improve outcomes. Assessments should consist of objective data whenever possible because owners and veterinarians often believe a patient is doing better than what the data suggest. In addition, documentation of progress is important to provide incentive for owners to continue rehabilitation and to justify continued treatment. Several measurements are important for assessing outcomes, including return to function, the ability to perform functional activities of daily living, gait analysis, joint function, body composition, muscle mass and strength, and impressions of owners and veterinarians. Return to Function There are many possible outcome measures in assessing canine patients. The easiest and perhaps the most valuable outcome measure is the patients return to function. Different patients and owners may have various expectations for return to function. For some have, it may be very important for them to return to vigorous work, such as a working police dog or a racing animal. For others, return to function may mean return to life as a house pet or other less vigorous activities. For some patients, return to function is not a realistic goal. For example, the dachshund with loss of the pain sensation to its fore limbs or an animal with a serious vertebral body fracture may have little if any chance of returning to normal function. In cases such as these, return of functional activities of daily living are more realistic goals. Parameters which may be assessed to determine the degree of treatment success include gait evaluation, joint function, body composition, muscle mass and function, and the impressions of the owners and veterinarians. Range of Motion (ROM)/Joint Function ROM should be documented at each visit using a goniometer and standardized test positions. The maximum comfortable ROM should be measured for each affected joint and compared to the joint of the contralateral limb, or to the expected normal ROM if there is no unaffected side. In measuring maximal comfortable ROM, the joint is moved passively though the ROM to the point in which the dog starts to show signs of discomfort such as turning the head or attempting to withdraw the limb. Using maximal comfortable ROM over full passive ROM also eliminates the need for sedation and potential conditioning by the dog (i.e., withdrawal of the limb in anticipation of pain as soon as ROM begins). The quality of movement including the synergy of the movement, presence or absence of joint crepitus, and pain during motion should be assessed and documented for later comparison. Limb Circumference There is significant correlation of thigh circumference measurements with muscle mass, validating the use of thigh circumference measurements as a clinical tool to assess muscle mass. We have also found thigh circumference measurements to be adequately sensitive in documenting muscle atrophy and hypertrophy. We currently measure thigh circumference by first measuring the distance from the greater trochanter to the distal lateral fabella. Girth measurements are then obtained at 70% of the measured thigh length. We have measured thigh circumference before and after clipping hair, and have found an average difference of 3-4 mm when performing measurements on clipped vs. unclipped short-haired dogs. Dogs with longer hair will likely have more significant differences, and this needs to be accounted for. Sedation resulted in a slight decrease in circumference compared to a fully aroused state although the differences were not significant. Measurements taken with the stifle in full flexion and in a functional standing position are greater than measurements taken with the stifle in full extension. Follow up measurements should be taken in the same position for the most accurate results. With a brief training session, we have demonstrated high inter-tester reliability of measurements with the agreement between testers within 3.5% of each other. Functional Activities of Daily Living This category is more applicable to humans receiving physical therapy, but may be applied to dogs with the idea that the patient should regain the ability to do things for themselves with minimal assistance. For a paraplegic dog, this may mean that the patient is able to get up to go outside and eliminate. For an older arthritic patient, this may mean that the patient has the ability to climb a few stairs to get in and out of the house. For others with specific duties or tasks to perform, this may mean the ability to perform those expected tasks on a daily basis. Gait Assessment There are qualitative and quantitative methods of evaluating the dogs gait. Qualitative assessment of gait may include observations and assessment note the flight of limbs during gait. The length of stride, presence or absence of circumduction, flexion or decreased motion of joints, and other factors may be assessed. In general, therapy patients are evaluated at the walk, trot, pace, or faster gaits. For patients in the early postoperative period or those with serious disabilities, it may be possible to assess the patient only at a walk. The trot is the most commonly used gait to evaluate the therapy patient. It is important to differentiate the trot from the pace. Approximately five percent of dogs will have the pace as their natural intermediate gait. More commonly, dogs which pays to sell to limit the degree of flexion and extension of joints. Many owners and veterinarians report that the dog trots very stiffly. In fact, the dog may not be trotting but only pacing. Because the pace is a lateral two beat gait, the dog is able to roll its body from left to right and right to left with minimal need to flex joints. It is difficult to evaluate dogs at faster gaits, but one effective method of gait assessment in a racing animal is the time to complete the race. Weight-Bearing at a Stance Evaluation of a dog's stance gives information regarding willingness to place complete weight on an affected limb. Many dogs may have no visible or only very mild lameness at a walk or trot, but will not bear equal weight on the limbs when standing. Weight-bearing at a stance may be assessed by observing the placement of a foot in relation to the contralateral front or rear foot. In severe cases, the dog may hold the foot completely or partially off the ground. More commonly, the dog places a moderate amount of weight on the foot, but not complete weight. The toes may point out and when the limb is gently pushed forward, it may be moved more easily than the contralateral limb when it is gently pushed. Alternatively, the evaluator may place both hands under the fore or rear feet with the palm facing the pads, and the relative amount of weight-bearing may be assessed. Weight-bearing at a stance may be incorporated into global lameness scores. An inexpensive method of acquiring more quantitative information regarding weight-bearing at a stance is to have a dogs stand with each limb on common household scales. It is important to be certain that the dog is standing squarely in a standard position. Dogs should also undergo a period of acclimation to the scales so that data collection is valid. Scales should periodically be calibrated to standard weights to be certain that accurate weights are recorded. Lameness Scores Lameness scores are a semi quantitative method of gait assessment and may be the only means of comparing an animals improvement during the course of treatment. It is important to have separate lameness scores for the walk and the trot. Some animals will appear to be relatively sound at a walk, but may have mild to moderate lameness at a trot. Scoring systems which combine features of both the walk and the trot may be confusing to a person performing the evaluation. In addition, it is beneficial to have separate lameness scores for animals which are just beginning a postoperative therapy program as compared to those who have been in a rehabilitation program for some time, or those that are being treated for chronic conditions. During the early postoperative period, it is expected that in animal will be quite lame. However, it is important that the animal begin to use the limb consistently with nearly every stride. With more conditions, it is expected that in animal will use the limb consistently trained each stride, but it is more important to quantify the degree of lameness that the animal has to assess the outcome of treatments. Kinetic (Forceplate) Analysis of Gait Kinetic evaluation of gait involves the measurement of ground reaction forces with a force plate or platform. It is an objective, repeatable measure of weight-bearing on limbs when proper technique is used for data collection. Lameness may be compared over a period of time without relying on memory of previous assessments because data may be stored on a computer. Although measurement of ground reaction forces is a reliable and well-accepted method of determining the degree of weight-bearing on the limbs, it is an artificial situation and some dogs may display different clinical signs in a home environment. Force platform systems are available at many veterinary colleges and some private practices. It is important that appropriate software for quadruped animals be used. The force plate is either mounted on a platform or embedded in the floor so that it is even with the surface. A runway of adequate length is essential. Most systems have timer lights that are triggered as the handler and dog approach and cross the force plate to allow the calculation of mean velocity and acceleration. Control of velocity and acceleration within appropriate parameters is essential for repeatable data collection, because these greatly affect the force placed on each limb. The force plate is connected to a computer which calculates ground reaction forces. The most useful forces measured are the peak vertical force (ZPeak) and vertical impulse (ZImpulse). Other forces that may be useful are the peak braking (YA Peak) and propulsion (YB Peak) forces and braking (YA Impulse) and propulsion (YB Impulse) impulses. Medial-lateral forces (XPeak) and impulse (Ximpulse) are likely too small and variable to be clinically useful. Forces may be measured during stance, walking, or trotting. In general, dogs bear 30% of their body weight on each front limb and 20% on each rear limb while in a standing position with the limbs placed squarely under the body. Walking at a velocity of 0.7-1.0 m/sec results in forces equivalent to 60% of body weight on each forelimb and 40% on each rear limb in a medium to large dog. Increasing the velocity to a trot of 1.7-2.0 m/sec results in weightbearing of 100-120% of body weight on each forelimb and 65-70% of body weight on each rearlimb in a similar-sized dog. Reduced weightbearing on an individual limb may result in mild weight shifts to the other limbs. Pain Assessment Assessment of pain and discomfort are important in the physical rehabilitation of animals. Excessive discomfort may prevent or slow progress during treatment, but objective measurement of pain is difficult in animals because they do not verbalize the level of pain that they may be experiencing. Therefore, pain assessment scores are generally used to evaluate behaviors which are believed to be associated with pain and discomfort. In addition, ordinal or visual analog scales are sometimes used in which owners are asked how painful they believe their pet is. Some physiologic parameters, such as heart rate, respiratory rate, and blood pressure, have been used to evaluate pain in the acute post-operative period, but these are generally not as useful for assessing pain in chronic conditions. Painful behavior in dogs may be indicated by whining, crying, or other forms of vocalizing when the animal moves or the affected body part is manipulated. Holding an affected limb in a tightly flexed or guarded position is frequently noticed after surgery. Animals may be particularly resentful to palpation and manipulation of the area. Painful behavior may also be exemplified by laying quietly in the back of a run or in the corner of a room with little desire to rise and move about. This may be a protective mechanism to avoid further injury and pain from moving about. The degree of pain in these patients is frequently underestimated because of their quiet nature. Impressions of Owners and Veterinarians Dogs and cats have different personalities and may respond very differently to various therapies. It is important for individuals who best know the patient to evaluate their progress. For example, owners are often very aware of subtle changes in their pet's behavior. Although it is somewhat difficult to quantify these changes, these subjective findings often provide the therapist with important information regarding patient progress. If possible, the changes should be as objective as possible, such as recording the amount of time a pet spends playing rather than resting, measuring the distance that an animal is able to walk before needing to rest, or evaluating the length of time a neurologic patient is able to stand unassisted. Owners should keep a log of daily activities to further define the progress of the patient at home. This may also provide incentive for owners to continue a home rehabilitation program if they can see the progress that is made from week to week and month to month. Poor compliance is a common reason for failure of a patient to progress. Regularly checking the log gives the veterinarian and owner an opportunity to evaluate the patient's progress, as well as make alterations to the rehabilitation program that account for an owner's ability to provide continued home care. In addition, videotaping the patient's activity on a regular schedule will allow comparisons to be made over relatively long periods of time. |
