Use of Physical Therapy in a Dog with Bilateral Severe Plantigrade Stance
A 3.5 yr old spayed female Staffordshire terrier weighing 25.5 kg was presented with a 7 wk history of bilateral plantigrade stance in the pelvic limbs directly following an ovariohysterectomy procedure. Upon presentation, the dog had bilateral atrophy of the distal pelvic limb muscles, enlarged popliteal lymph nodes, and ulcerative wounds on the dorsa of her rear paws. Orthopedic examination revealed intact calcaneal tendons bilaterally and neurologic examination localized the lesion to the distal sciatic nerve. A diagnosis of compressive and stretch neuropathy was made affecting the distal sciatic nerve branches. Physical therapy modalities included neuromuscular electrical stimulation, ultrasound, and low-level laser therapy. Other therapeutic modalities included the use of orthotics and progressive wound care. The dog had increased muscle mass, return of segmental reflexes, return of nociception, and the ability to walk on pelvic limbs with higher carriage of the hock 15 mo following presentation. The use of custom orthotics greatly increased the quality of life and other physical therapy modalities may have improved the prognosis in this dog with severe bilateral plantigrade stance due to neuropathy.
Introduction
Plantigrade stance is usually seen either due to trauma to the calcaneal tendon/pelvis or iatrogenic damage directly to the sciatic nerve during surgery. Those cases have a poor prognosis without intervention to repair the cause. In the case described herein, physical therapy (PT) modalities and custom orthotics were used to minimize further complications during a dog's recovery and to potentially benefit nerve regeneration. There was an overall improvement of this dog's long-term prognosis following her initial neurologic exam that was possibly due to the applied PT modalities, such as neuromuscular electrical stimulation (NMES), low-level laser therapy (LLLT), ultrasound (US), and custom orthotics.
Case Report
A 3.5 yr old female spayed Staffordshire terrier weighing 25.5 kg was presented to the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California, Davis with a 7 wk history of progressive weakness and bilateral plantigrade stance of the pelvic limbs immediately following a routine ovariohysterectomy. The dog had no previous history of trauma or other orthopedic or neurologic conditions as a cause for the plantigrade stance, weakness, and ataxia.
Her initial physical examination revealed bilateral severe muscle atrophy of the muscles of the caudal thigh and distal to the stifle, bilateral severe plantigrade stance, ulcerations on the dorsa of the rear paws, and enlarged popliteal lymph nodes (Figure 1). The patient had been prescribed cephalexin (20 mg/kg q 12 hr) and prednisone (1 mg/kg q 12 hr) on three separate occasions during the 7 wk prior to presentation with no improvement of clinical signs.
Citation: Journal of the American Animal Hospital Association 51, 1; 10.5326/JAAHA-MS-5978
An orthopedic examination revealed intact calcaneal tendons bilaterally. A neurologic examination revealed a decreased gastrocnemius reflex, absent flexor reflex, absent postural reactions, and absent nociception in both distal pelvic limbs. The damage was localized to the distal sciatic nerve bilaterally. Due to the history of recent ovariohysterectomy, it was assumed that the legs were tied down to the operative table and a compressive neuropathy and the stretch/traction of the nerves was considered as the cause of the presentation. Further diagnostics and imaging were declined by the owner due to financial constraints.
The following week, the dog was evaluated by Jacqueline Woelz at the William R. Pritchard Veterinary Medical Teaching Hospital Rehabilitation Services at University of California, Davis for orthotic fittings and therapy with PT modalities. The dog began weekly to bimonthly PT modalities applied at the William R. Pritchard Veterinary Medical Teaching Hospital Rehabilitation Services at University of California, Davis including LLLTa, NMESb, and US therapyc. Home rehabilitation involved use of support boots, carts, and orthotics as described below due to the clients' inability to perform an aggressive PT regimen at home. The goal of PT was to stimulate and promote healing and to use supportive devices for return to normal function for the dog.
LLLT was used on the wound beds in a 1 cm2 footprint, and a wavelength of 904 nm was used to administer 2 Joules/cm2/point to enhance healing through acceleration of collagen synthesis and promotion of granulation tissue.1 LLLT was used along the length of the distal sciatic nerve and the distal left pelvic limb at 2 Joules/cm2/point, which has been previously shown to enhance nerve regeneration, preserve muscle tissue, and reduce inflammation.2
NMES was initially applied bilaterally with surface electrodes to stimulate the caudal thigh muscles and was moved distally over the tibial muscles in subsequent visits. Muscle recruitment improvement was set for a duration of 200 ms with 10 sec on and 50 sec off with a 2 sec ramp time over a period of 15 min. NMES has been shown to stimulate sensory nerves to exert trophic effects on dennervated muscle and promote speed and accuracy of motor axonal regeneration.3,4
US was used at 3 MHz in a 20% duty cycle and 0.5 watt/cm2 for 6 min over the cranial tibialis and gastrocnemius muscles in an attempt to help decrease healing time by increasing the quantity of regenerating nerve fibers and facilitate regeneration by increasing myelination.5 Multiple orthotic support and assist devices were usedd,eand custom orthotics until a support device was found that the dog could wear comfortably throughout the day without adverse effects.
Three months after initial presentation, the dog was wearing custom designed and fitted orthoticsf for 8–10 hr/day (Figure 2). Her wounds on the dorsal aspects of both pes were healed, her muscle tone and mass were increased, and she had good sensation in both hindpaws. She was able to walk over obstacles, including 10 cm high poles with 50% accuracy.
Citation: Journal of the American Animal Hospital Association 51, 1; 10.5326/JAAHA-MS-5978
Five months following presentation, a follow-up neurological evaluation showed improved sensation to both pelvic limbs and increased muscle mass and tone to the semimembranosus, semitendinosus, gastrocnemius, and cranial tibial muscles in both limbs. The left hindpaw still knuckled when walking, and there were postural deficits of the left pelvic limb compared to the right. The dog was able to wear the custom orthotics for up to 12 hr/day without loss of skin integrity.
Fifteen months following presentation, another serial neurological and orthopedic evaluation was performed. The dog had no apparent pain on spinal palpation, increased development of the cranial tibial muscle, and moderate development of her gastrocnemius muscle. The hocks were held about 2–3 cm above the ground when standing and walking without the use of orthotic devices (Figure 3). Postural deficits were still noted, with the left pelvic limb still worse than the right. The right pelvic limb had decreased gastrocnemius, flexor, and extensor thrust reflexes in comparison to the left. She had superficial pain perception present in both pelvic limbs when stimulated on the medial aspects of her pelvic paws.
Citation: Journal of the American Animal Hospital Association 51, 1; 10.5326/JAAHA-MS-5978
Overall, the dog had increased return to function and sensation of both pelvic limbs following her treatment with combination PT modalities. The wounds on the dorsum of her paws were completely healed. There was return of tibial nerve sensation and slight development of the cranial tibial muscle that was greater in the left compared to the right. The dog could hold her hocks up when standing and had an improved ability to correct the right foot placement during an unassisted gait. The withdrawal reflex was intact, greater on the left than right, with slight hock flexion observed.
Discussion
Plantigrade stance in dogs is a characteristic clinical sign that presents with rupture or avulsion of the calcaneal tendon or distal sciatic nerve injury. With rupture or avulsion of the calcaneal tendon, there is partial weight bearing, extension of the stifle, flexion of the digits, and an associated incidence of trauma.6,7
The human literature reports cases of spontaneous calcaneal tendon rupture associated with steroid administration.8,9,10,11 The three courses of corticosteroids during the 7 wk prior to presentation may have compromised the gastrocnemius tendon further by possibly allowing it to stretch and may have attributed to the slower return to function. It is important to rule out an orthopedic cause to plantigrade stance by palpating an intact gastrocnemius tendon or confirming with radiographs and/or US that the gastrocnemius tendon is intact. In the case described herein, there was a palpably intact gastrocnemius tendon; however, that was not confirmed with either radiographs or US.13 There was no evidence of a bulge within the area that could be associated with a previously avulsed tendon that had healed.
Most sciatic nerve injuries are attributed due to either trauma or iatrogenic causes from surgical procedures.14,15 Clinical signs with sciatic nerve injury include knuckling of the digits, sensory analgesia of the lower pelvic limb and decreased or absent gastrocnemius and cranial tibial tendon reflexes.15 In the current case, there was no evidence that the surgical procedure itself had any direct effect on the injury. However, due to the history, presentation, and progressive return to function, it could be speculated that either compressive or stretching nerve injury occurred while positioning the dog for her procedure, which would lead to ischemia and mechanical deformation of the nerve at the compression site as well as proximal and distal to the site of compression.11 Due to the lack of further diagnostics to localize the affected nerves and monitor improvement, the dog's documented recovery was reliant on serial neurologic examination and progression of return to function throughout the 15 mo of follow up.
Wall et al. (1992) showed that 6% strain for 1 hr results in significant loss of nerve function but would lead to recovery of 90% of the prestretch value. With 12% stretch over 1 hr, only 40% recovery was possible after 1 hr of recover time.12 That allows speculation that there was a component of stretch and compression to the nerve that allowed function of the legs with progressive degeneration following the ovariohysterectomy. The inability to confirm stretch or compression neuropathy as a definite cause in this patient's diagnosis only allows speculation that PT assisted in the improvement of return to function.
The amount and type of axonal damage could also help determine the prognosis of the patient. Categories of peripheral nerve damage are neuropraxia, axonotmesis, and neurotmesis, from best prognosis to worst prognosis.15 Neuropraxia is the transient physiological conduction block of nerve transmission that typically resolves spontaneously in 3–6 wk. Axonotmesis is the disruption of axons but maintenance of intact endoneurial tubules where recovery can occur but takes >6 wk. Neurotmesis is the severance and complete separation of the nerve where recovery is not likely to recur without surgical correction or aggressive supportive care and therapy. Because the patient described in this case showed some clinical signs of progression and return to function after a few months, the study authors suspect that either severe axonotmesis or some amount of neurotmesis had occurred to her distal sciatic nerve and nerve branches following a compression and stretching injury leading to ischemia of the nerve.
Lack of movement and anatomical position of the limbs are essential to assist in appropriate regeneration of nerve axons and to decrease interference of fibrosis that would axonal sprouting.11,16 Early mobilization showed decreased revascularization and increased scar tissue formation of a nerve repair site compared to immobilization of the limb with the repaired nerve. Lee et al. (1999) recommends immobilization of transected and repaired nerves for at least 6 wk to promote revascularization and axonal regeneration.17 The custom designed orthotics were fabricated to maintain a normal weight-bearing stance without increased range of motion of the hock. This allowed application of those principles, even though it may have not been a transected nerve, possibly allowing appropriate regeneration of the axons to the neuromuscular nerve plates.
The asymmetric nature of the dog's recovery in her pelvic limbs was speculated to be a result of both a previous spinal trauma (which was exacerbated by her current neuropathy) as well as an increased injury to the distal right sciatic nerve in comparison to the left. That may explain the upper motor neuron deficits in her left pelvic limb and her weaker reflexes in her right pelvic limb. Because those findings could not be definitively diagnosed without further tests or imaging, the therapy was not altered to address any additional complications and were aimed at improving quality of life.
LLLT, NMES, and therapeutic US was used at each PT session as described above because there have been previous reports of positive nerve regeneration experiments in rat models.2–5 Those reports discuss the benefits of each modality used in nerve regeneration with surgically transected nerves in the immediate perioperative period. However, there has been no evaluation of the standards that would allow for nerve regeneration in companion animal patients. Future studies in the role of those modalities in canine and feline patients would help understand the benefits of such therapies on nerve regeneration and wound management. The appropriate doses and time of use of each modality have not been defined and would be an area of interest for future evaluation to determine if there are true benefits for those techniques.
PT modalities are an emerging area for therapy in orthopedic and neurologic cases. Therapeutic US, NMES, LLLT, and custom orthotics are some of the modalities used in the patient described in this report and other patients to help with tissue healing and return to neuromuscular function. The progressive improvement in this dog's neurologic status over 15 mo illustrated how PT did not hinder improvement, may have aided in return to function, and improved quality of life.
Conclusion
Plantigrade stance is usually seen due to either trauma to the calcaneal tendon or rarely iatrogenic damage directly to the sciatic nerve during surgery but was not the cause of this patient's presentation. PT modalities and custom orthotics were used as an aid with the hope to progressively promote regeneration of the distal sciatic nerve axons and allow adequate return to function of both pelvic limbs. There was an overall reversal of her initial prognosis following her initial neurologic exam and may be due to the improvement seen with NMES, LLLT, therapeutic US, and custom orthotics. Those therapies did not preclude the patient from return to neurologic function following severe peripheral nerve injury secondary to either traction or compression. Future studies in the role of those modalities in canine and feline patients would help understand the benefits of those therapies on nerve regeneration and wound management.
Photograph showing the plantigrade stance and wounds on the pes.
Photograph of the custom orthotics allowing appropriate ambulation, angulation of the distal pelvic limbs, and recruitment of atrophied muscles.
Photograph taken 15 mo following presentation showing that hock carriage is 2–3 cm above the ground; however, postural deficits are still present in the left pelvic limb.
Contributor Notes
