Chronic Quadriceps Contracture in an Adult Cat

Winner, Cases/Abstracts
Ashley Nichols, Ross

Cloe is my three-year-old, spayed, Domestic Short Hair, feline that was adopted in 2010 at the age of one. When Cloe was adopted from the shelter, she displayed a hind limb deformity. The right hind limb deformity resulted in a permanent extension of the right hind limb (Figure 1). It was suggested by the shelter that the “cat was abused or hit by a car prior to arrival.” Subsequently, I have not seen nor taken any radiographs of the right hind limb. Since 2010, there have been no clinically observable changes in the condition of the right hind limb and Cloe has been up to date on all medications, and vaccines. On December 17^th, 2012, Dr Paula A. Schuerer DVM saw Cloe as a new patient. She was seen for a physical exam and baseline radiographs.

Physical Examination

Cloe’s weight, 9 lbs, and body condition score (3.5/5) put her in the overweight category.  Nevertheless, with exception to abnormalities being in the muscular skeletal system, the rest of physical exam findings were within normal limits. Examination of Cloe’s movement demonstrated an abnormal gait. Yet, she had no difficulty in moving around the exam room, including an attempt to jump off the exam table. When in a sitting position, it was observed that Cloe’s right hind limb was in a fixed position and abnormally protruded from the body.

Examination results show most of the muscular skeletal system were within normal limits, the exception being the right hind limb. Palpation of the right rear limb did not elicit a painful response. However, Cloe did display signs of agitation when touched proximally and distally on both hind limbs. The right quadriceps femoris muscle group, were in a “fixed” and tense state; they were unable to be manually manipulated into any other state. Palpation of this muscle group has an overall feeling of a thick tendon rather than a muscle.

Full examination of the right stifle joint was difficult, as Cloe was not cooperating and the patella was not in its normal location.  Dr. Schuerer was unable to manually change the “fixed” position of the right hind limb at the point of the stifle joint. The abnormal location of the right patella and fixed position of the right stifle joint appears to be the only abnormality in comparison with the left stifle joint. The other joints of the right hind limb were normal upon examination and comparison to the left hind limb. 

Diagnostic Imaging and Analysis

Click to enlarge

Click to enlargeAt the time of the appointment, a radiographic series was taken of the right hind limb. The first radiograph is a lateromedial (lateral) view of the right hind limb.  Abnormalities are seen in the femur, in the location of both of the seasmoids of the gastrocnemius muscle, and in the location of the patella. The second radiograph is a craniocaudal (Cr/Ca) view of the right hind limb. The abnormalities seen in the lateral view are more apparent in the Cr/Ca view.  The increased opacity seen in the body of the femur, in both views, is evidence of a healed fracture. Both views also confirm the abnormal location of the patella. From the Cr/Ca view the right patella, normally superimposed above the interconylar fossa of the femur, is now located on the lateral aspect of the medial epicondyle of the femur. The most surprising abnormality is the torsion of the distal portion of the right femur and the right femoral condyles. This is the likely cause of the abnormal location of the right sesamoids of the gastrocnemius muscle; and may be the cause for the abnormal position of the right patella.

Discussion and Diagnosis

Cloe’s radiographs are supportive of a torsional malunion fracture of the right femur (Thrall 298). Malunion fractures result from poor stabilization of the bone and often lead to dysfunction of nearby muscles and joints. The dislocation and torsion of the distal right femur with the angle of the femoral fracture line, supports the speculation that traumatic injury caused the fracture (Thrall chapter 16).

Dr. Schuerer DVM diagnosed Cloe with a quadriceps contracture, due to a malunion fracture of the right femur. In cats, quadriceps contractures are uncommon conditions, and are often the result of mid-diaphyseal fractures of the femur.  They result in degenerative conditions of the limb, characterized by stifle hyperextension (Liptak 44 and Moore 74). Even without a muscle biopsy, one can conclude from the time frame provided in the history, that irreversible muscle fibrosis has already occurred. This muscle fibrosis, abnormal position of the distal femur, and other stifle joint abnormalities are the likely causes of the clinical presentation of “fixed” right hind limb extension.

Treatment and Prognosis

Successful treatment for quadriceps contracture requires early intervention, before “irreversible muscle fibrosis (Moore 74).” However, due to the chronic nature of Cloe’s injury, surgical outlook is poor. It is unlikely that Cloe will ever regain normal use of the right hind limb. The current treatment plan is designed to maintain the health of both of her coxofemoral joints. The current recommendation is a weight management plan with oral supplementation of glucosamine and chondroitin. However, currently oral supplementation is inconsistent due to the personality of the patient.

In the future, I would like to periodically take radiographic series of both hind limbs. In order to continue to assess, compare, and monitor any joint changes in the right stifle joint and both coxofemoral joints. Cloe’s current quality of life is good. If her coxofemoral joints remain in a good state, then her future health prognosis is good.  

This case reinforces the importance of physical exams in veterinary medicine. While the radiographs were important in supporting the final diagnosis, radiographs are insufficient when dealing with soft tissue injuries. Therefore, the key to a diagnosis may lie in our ability to physically assess our patients with our own two hands, rather than an array of diagnostic tests.

References

Liptak, J. M., and D. J. Simpson. "Successful Management of Quadriceps Contracture in a Cat Using a Dynamic Flexion Apparatus." Veterinary and Comparative Orthopaedics and Traumatology (2000): 44-48. Print.

"Merck Veterinary Manual." Merck Veterinary Manual. Merck & Co., Inc., n.d. Web. 17 Jan. 2013.

Moores, Andy. "Muscle and Tendon Disorders in Small Animals 2. Conditions Affecting the Hindlimb and Digital Flexor Tendons." In Practice 34 (2012): 74-77. Print.

Thrall, Donald E. Textbook of Veterinary Diagnostic Radiology. St. Louis, MO: Saunders Elsevier, 2007. Print.