COMPARTMENT SYNDROME IN A LABRADOR RETRIEVER

JAMIE WILLIAMS, MS, DVM, MICHAEL Q. BAILEY, DVM, ERIC R. SCHERTEL, DVM, PHD, AMY VALENTINE, MS, DVM

Compartment syndrome is an elevation of interstitial pressure in a closed osseofascial compartment that results in microvascular compromise. This report documents a clinical syndrome in the crus of a fourteen-month-old intact male Labrador Retriever which was consistent with trauma-induced com- partment syndrome. A six month history of recurring trauma or complications resulted in the need for referral. Survey radiography and ultrasonography aided in the diagnosis, but the definitive answer was provided by femoral angiography. The patient was successfully treated and was discharged with normal limb function. One year later, there were no complications observed. Compartment syndrome is not uncommon in humans, and is routinely considered in certain blunt and most penetrating trau- mas. However, few reports of this complication in animals are found. Veterinary Radiology & Ultra- sound, Vol. 33, No. 6, 1992, p p 244-248.

Key words: compartment syndrome, compartmental hematoma, angiography of the proximal rear limb.

Case History Report

FOURTEEN-MONTH-OLD intact male Labrador Re- A triever was referred to The Ohio State University Vet- erinary Teaching Hospital (OSU-VTH) for a two week du- ration of swelling of the left thigh with lameness, anorexia and weight loss. Medical history included a dog-bite punc- ture wound to be proximal left rear leg four months previ- ously. This was treated by the referring veterinarian, and the condition resolved in about 1.5 weeks. Two months after the original incident, the dog was again presented to the referring veterinarian for unknown trauma to the same leg, resulting in a deep puncture with severe hemorrhage. No fracture or foreign bodies were observed on radio- graphic examination. The wound was treated and appeared to resolve.

Six weeks later (two weeks before presentation to OSU- VTH), the patient was swimming and exited the water non- weight bearing on the left rear leg. Within 48 hours, severe swelling of the thigh was noted. The dog was confined to a cage and treated with antibiotics and corticosteroids for seven days, with no resolution of the swelling.

From the Department of Veterinary Clinical Sciences, College of Vet- erinary Medicine, The Ohio State University, 601 Vernon L. Tharp St. , Columbus, OH 43210-1089.

Correspondence and reprints: Dr. Jamie Williams, Department of Vet- erinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon L. Tharp St., Columbus, OH 43210-1089.

Received May 8, 1992; accepted for publication September 10, 1992. FIG. 1. Ventrodorsal survey radiograph. Note the severe difference in

soft tissue thickness of the rear limbs.

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VOL. 34, No. 4

FIG. 2. a. Sonographic image of vascular struc- ture (arrow) deep to layered architecture (open ar- row). b. Sonographic image of second anechoic structure (arrow).

COMPARTMENT SYNDROME

The dog was referred to OSU-VTH with a two week duration of lameness, swelling of the left rear thigh, an- orexia and weight-loss. Severe, firm swelling of the cau- domedial aspect of the left thigh was identified on initial physical examination. No neurologic deficits were present. Temperature and pulses of the distal limb were within nor- mal limits, and a palpable thrill was detected in the femoral artery of the affected leg. A continuous bruit was not aus- cultated in the region.

Fine needle aspiration of the swollen area revealed dis- torted red blood cells with a few squamous cells (contam- inant). A hemogram indicated a regenerative anemia and

245

(4

neutrophilia with a left shift. The serum profile, coagulation screen* and buccal bleeding time were within normal range.

The soft tissues of the left femoral region were 3 4 times the thickness of the right femoral area on initial survey radiographs (Fig. 1). Multifocal mineralized opacities in the soft tissues were evident, with a singular opacity caudome- dial to the stifle joint. No obvious osseous involvement was noted. Differential diagnoses for the increases soft tissue thickness included trauma, infection, hemorrhage, and neo- plasia.

*Tested for PT, PTT, and Fibrin Degradation Products.

246 WILLIAMS ET AL 1993

FIG. 3. Contrast extravasation (arrow) seen on the craniocaudal angio- gram, exposed during injection.

Prominence of the fascial planes was noted on ultra- sonographic examination of the swollen left thigh, indicat- ing possible hemorrhage or edema within the muscle. A vascular structure with concentric alternating echoic and anechoic walls was identified at the mid-proximal thigh. Layering was noted immediately superficial to the vessel; presumed to be a clot. A second anechoic area was noted immediately caudal to the femur, just proximal to the stifle (Figs. 2a & b). It appeared to pulsate in response to adjacent vascular structures, was round on both views and collapsed easily; differentials included aneurysmal or pseudoaneurys- ma1 structure.

On day two, the distal limb was cool and pulses were absent. The palpable thrill in the femoral artery persisted. Angiography of the proximal left femoral artery was per- formed via retrograde carotid catheterization utilizing a 90 cm multipurpose catheter with end and side holes.? Ten ml of positive contrast medium3 was hand-injected and radio-

graphs were made. A focal area of contrast extravasation was identified proximal to the origin of the gastrocnemius muscle on the medial aspect of the limb (Figs. 3, 4 and 5) . This extravasation was believed to be from the femoral artery between the middle and distal caudal femoral artery branches. The large soft tissue swelling on the caudomedial aspect of the femur was thought to be a pseudoaneurysm. Cause of the extravasation could not be ascertained, but the mineral opacities within the soft tissues on the survey ra- diographs may have been associated with a foreign body.

Surgical exploration of the femoral artery from the me- dial aspect of the thigh was performed immediately follow- ing the angiogram. A large fluid-filled capsule containing a hematoma was found deep to the femoral artery. A 2 cm longitudinal tear of the lateral aspect of the femoral artery was identified just distal to the saphenous branch. The ves- sel was bleeding into a compartment formed by the fascial planes of the semimembranosus and semitendinosus mus- cles. The femoral artery was ligated proximal and distal to the tear after confirming good collateral blood supply distal to the ligation. The compartment containing the hematoma was entered from the site of the vessel tear and a separate incision on the caudal aspect of the thigh. The clot was removed and the wound drained with penrose tubing. The incision on the medial aspect of the thigh was closed pri- marily. Pulses were present in the distal limb post- operatively. The patient was discharged thirteen days later, with reduction in swelling and normal limb function. No complications were reported on the one year post-operative follow-up.

Discussion The cause of the swelling in this patient was arterial

extravasation, which resulted in a pseudo- (false) aneurysm of the femoral artery. This eventually progressed to com- partment syndrome. True aneurysms, unlike pseudoaneu- rysms, arise from a weakening in the media of the arterial wall, with an intact, but stretched intima and adventitia. The dilation may be saccular or fusiform.’ Pseudoaneu- rysms are caused by rupture of a true aneurysm or by pen- etrating trauma to an artery, with the resulting hemorrhage confined to the periarterial structures such that blood flow is maintained. True aneurysms are differentiated from false aneurysms only by histology.

Most traumatic aneurysms in the extremities are false, usually caused by penetrating trauma. Pseudoaneurysms are initiated by full-thickness tear or laceration of an artery, which leaks blood forming a pulsatile, perivascular he- m a t ~ m a . ~ ’ ~ The size of the resulting hematoma is limited by clotting and tamponade from the surrounding soft tissues. Eventually, the hematoma is surrounded by fibrous tissue

tDucor Angiographic Catheter, Cordis Corp., Miami, FL. $Angio-Conray, Mallinckrodt, Inc., S t . Louis, MO.

VOL. 34, No. 4 COMPARTMENT SYNDROME 247

(B)

FIG. 4. a. Lateral angiogram (arterial phase), exposed during injection. The arrow indicates the pooling of the extravascular contrast. b. Close-up view of extravascular contrast pooling.

and then liquifies, becoming a mature pseudoanuerysm that can enlarge due to continued inflow from the laceration. Arterial flow distal to the pseudoaneurysm usually is main- tained.’

Compartment syndrome has been defined as an elevation of the interstitial pressure in a closed osseofascial compart- ment that results in microvascular compromise.u As the duration and magnitude of the interstitial pressure increase,

FIG. 5 . a. Extravascular extravasation and retention of contrast seen on this lateral angiogram (venous phase) exposed post-injection. b. Close-up view of contrast retention.

248 WILLIAMS ET AL 1993

myoneural function is impaired and necrosis of the soft tissues eventually develops. Predisposing risk factors for the development of compartment syndrome include vascu- lar injury and trauma to a closed area, with or without

Although more commonly reported in the distal extremities, there have been occasional reports involving the The infrequent occurrence in the thigh may be due to the larger volume of the compartments of the thigh, requiring a massive increase in compartmental con- tent to cause pathologic increase in interstitial pressure.436 In acute compartment syndrome, pulses distal to the lesion are p r e ~ e n t , ~ however, with duration, diminution or absence of pulses has been r e p ~ r t e d . ~ Tense swelling of the involved

area is the hallmark of compartment ~yndrome.~’ Increased tissue pressure will eventually lead to venous outflow ob- struction from the compartment, promoting further swelling and increased tissue pressure.537 Recommended treatment in humans is fa~ciotomy.~’

Compartment syndrome may occur in combination with pseudo-aneurysm in human patients. 8 2 9 One affected hu- man patient experienced a clinical course nearly identical to the dog described in this report.’ The trauma to the thigh was blunt, but the onset, recurrence and outcome were very similar. The affected artery was embolized rather than ligated, resulting in a similar non-complicated recov- ery.’

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