Surgical Repair of Coxofemoral Joint Luxation in a Wild Black-Crowned Night Heron (Nycticorax nycticorax)

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pISSN 1598-298X

J Vet Clin 30(1) :49-₅₂ (2013)

49

Surgical Repair of Coxofemoral Joint Luxation in a Wild Black-Crowned Night Heron ( Nycticorax nycticorax)

Eun-Ju Kim*, Jong-Hyun Lee*, Min-Su Kim, Ki-Chang Lee, Nam-Soo Kim, Gee-Wook Shin and Hae-Beom Lee¹ College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Korea

*Chonbuk Wildlife Rescue and Conservation Center, Chonbuk National University, jeonju 561-756, Korea (Accepted: January 21, 2013)

Abstract : A wild black-crowned night heron (Nycticorax nycticorax) with dehydration and a non-weight bearing lameness of the left leg was rescued. On physical examination, the left knee was displaced laterally at almost a 90^o angle with firm swelling and crepitus in the area of the coxofemoral joint. Radiographs confirmed cranio-dorsal coxofemoral luxation. A closed reduction attempt failed. The coxofemoral joint luxation was reduced surgically by placement of the femoral neck next to the pelvis with a suture. Ten days after surgery, radiographs and computed tomography showed the femoral neck and head were positioned well within the acetabulum. At 20 days, the bird was using the affected limb normally, and could hunt and forage for food in a rehabilitation housing unit with a small pond. The bird was successfully released into the wild. The placement of the femoral neck adjacent to the pelvis with a suture can be successfully performed for cases of avian coxofemoral joint luxation. Furthermore, this procedure can provide sufficient stabilization of the coxofemoral joint and acceptable limb function.

Key words : Avian, black-crowned night heron, coxofemoral joint luxation, open reduction.

Introduction

Avian coxofemoral joint luxation is an infrequent injury due to the unique structure of the coxofemoral joint, which differs from that of dogs and cats (4,6,7). The avian femoral head is seated deeply on the acetabulum and attached to the acetabular cavity with a strong round ligament. The avian femoral neck articulates with the dorsal rim of the acetabulum, which is called the antitrochanter, whereas the femoral head of dogs and cats only articulates at the acetabulum. This joint structure stabilizes the coxofemoral joint more than that in dogs and cats (5,6).

Avian coxofemoral joint luxation usually is craniodorsal with the knee displaced laterally almost at a 90^o angle. This prevents foot of the luxated limb from being placed on the ground. The quality of life for birds with a luxated joint is impacted significantly in both the short and long term (1).

Because of this, reduction of the luxation and stabilization of the joint is needed.

Treatment options for the reduction of an avian coxofemoral joint luxation include closed reduction and open reduction.

Closed reduction including the application of a sling or coap- tation splinting may be successful in the acute phase. Open reduction includes suturing the joint capsule and placement of the trochanter next to the pelvis with a suture. Open reduction has been recommended for chronic joint luxation or after

failure of a closed reduction attempt. If reduction of the coxofemoral joint fails, then excision arthroplasty can be used as a salvage procedure (1,5,6).

Anecdotal reports suggest that avian coxofemoral luxation is difficult to repair and most cases require excision arthroplasty. In addition, the overall incidence of coxofemoral luxation is low in wild birds. Therefore, few cases addressing the treatment of coxofemoral joint luxation have been reported in the literature, especially those involving open reduction.

The purpose of this report is to describe the surgical technique used for an open reduction in which the femoral neck was placed adjacent to the pelvis with a suture and the outcome in a black-crowed night heron with coxofemoral joint luxation.

Case

A free-living, 600 g juvenile black-crowned night heron (Nycticorax nycticorax) was rescued with non-weight-bearing lameness of the left leg and brought to the Chonbuk Wildlife Rescue and Conservation Center at Chonbuk Na- tional University. The bird was bright, alert, and responsive.

The bird’s general health status was a body condition score 2/5 with mild dehydration. On physical examination, the left knee was found to be displaced laterally at nearly a 90^o angle. Mild swelling and crepitus was noted at the area of the left coxofemoral joint. Blood was collected from the medial metatarsal vein for a complete blood count and clinical chemistry profile under manual restraint. The blood test results

1Corresponding author.

E-mail: seatiger76@chonbuk.ac.kr

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50 Eun-Ju Kim, Jong-Hyun Lee, Min-Su Kim, Ki-Chang Lee, Nam-Soo Kim, Gee-Wook Shin and Hae-Beom Lee

were within normal limits. Radiologic examination revealed craniodorsal luxation of the left coxofemoral joint (Fig 1) and a closed reduction failed at that time.

An open reduction was performed two days later. Preoper- atively, warm Lactated Ringer’s solution (10 ml/kg subcuta- neously; Hartmann's Sol; Daihan Pharm. Co., Ltd. Seoul, Korea), Butorphanol tatrate (1 mg/kg intramuscularly; Buto- phan; Myungmoon Pharm. Co., Ltd. Seoul, Korea) and enrofloxacin (10 mg/kg intramuscularly; Baytril 50, Bayer Animal Health, Seoul, Korea) were administrated 20 minutes prior to anesthesia. The bird was anesthetized using a face mask isoflurane (Ifran Solution, Hana Pharm. Co., Ltd. Kyonggi-Do, Korea; inspired concentration of 5% in oxygen) and then intubated. The anesthesia was maintained with 2-3% isoflurane in 100% oxygen. The bird was placed on an operating table in a right lateral recumbency with the affected limb sus- pended. The lateral aspect of the left pelvic limb was plucked of feathers from the dorsal midline to the stifle joint. After the surgical region was prepared for aseptic surgery, a standard lateral approach to the avian coxofemoral joint was used. The round ligament of the femoral head and joint capsule was torn. Tissue debris and blood clots were removed from the acetabulum using a moistened cotton swab. The cartilage of the femoral head and acetabulum appeared normal. The avulsed joint capsule from the cranial dorsal acetabulum aspect did not seem to permit adequate closure. Therefore,

stabilization of the femoral head and neck to the pelvis with a suture was utilized to achieve greater joint stability. As the knee rotated laterally, a 3-0 nylon suture (Blue nylon, Ailee co., Ltd. Busan, Korea) was passed from the lateral aspect to the medial aspect of the femoral head and neck and then through the dorsal rim of the acetabulum using a regular cutting needle (Fig 2). The femoral head was reduced on the acetabulum. The 3-0 nylon suture was tightened and tied with surgeon’s knots. The joint stabilization was sufficient.

The joint capsule was closed with an extracapsular technique, but adequate closure of the joint capsule was impossi- ble. The iliotibialis and iliofibularis muscles were apposed using 4-0 absorbable polydioxanone suture (Ethicon, Inc., Somerville, New Jersey, USA) in a simple continuous pattern, and the skin was closed with a 4-0 polydioxanone suture in a Ford interlocking pattern.

After surgery, meloxicam (4 mg/kg orally, q 12h; Meta- cam, Boehringer Ingelheim Vetmedica, Seoul, Korea) and enrofloxacin (15 mg/kg orally, q 12h; Baytril flavorur Tab- lets, Bayer HealthCare, Seoul, Korea) were administered for one week. An Ehmer sling was applied for three days and then the bird was confined to a small cage with floor perches for one week. The bird used the leg immediately after removal of the Ehmer sling. Ten days after surgery, the bird appeared to use the limb normally. At that time, the bird was anesthetized using isoflurane and oxygen to obtain radiographs. The femoral head and neck were positioned within the acetabulum on postoperative radiographs and computed tomography (Fig 3). On palpation, a smooth gliding motion in a cranial Fig 1. Ventrodorsal radiograph showing luxation of the left cox-

ofemoral joints.

Fig 2. Illustration of the placement of the femoral neck adjacent to the pelvis with a suture. A 3-0 nylon suture with a regular cutting needle was passed from the lateral aspect to medial aspect of the femoral head and neck (A), and then though the dorsal rim of the acetabulum (B). The 3-0 nylon suture was tightened and tied with surgeon’s knots (C).

Fig 3. Ventrodorsal radiograph (A) and computed tomography (B) image of the coxofemoral joint ten days after surgery. The femoral neck and head were positioned within the acetabulum.

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Surgical Repair of Coxofemoral Joint Luxation in a Wild Black-Crowned Night Heron (Nycticorax nycticorax) 51

caudal direction was observed. The range of motion of the affected coxofemoral joint was approximately 20% decreased compared to that of the contralateral limb. The bird was moved to a rehabilitation housing unit with a small pond for one week. The bird used the limb normally and was able to successfully catch Chinese weatherfish from the pond and eat them. At 20 days after admission, the bird was successfully released in the area where it had been found.

Discussion

Birds are bipedal animals that bear all of their weight on their pelvic limbs, whereas quadrupeds such as dogs and cats bear less than half of their weight on their pelvic limbs. Avian coxofemoral joint luxation makes it difficult to place the foot of a luxated limb on the ground, and thus places results in more weight being borne on the foot of the unaffected limb, which can lead to bumblefoot. Severe bumblefoot in wild birds can decrease their likelihood of survival. Therefore, the goals of coxofemoral joint luxation treatment in wild birds are joint reduction and stabilization. Open joint reduction methods have been introduced for treating avian coxofemoral joint luxation.

However, the results of these methods are reported rarely in literature, which may be due to the low incidence of avian coxofemoral joint luxation and the difficulty of the proce- dures (3,7).

Excision arthroplasty to manage avian coxofemoral joint luxation has been described as a salvage procedure. The functional outcome was acceptable in that the affected limb could be used for support, climbing, and walking without pain (1,5,6). However, there was a change in limb movement on the affected limb. Although excision arthroplasty may not significantly affect survival in wild birds after release, the ideal treatment for coxofemoral joint luxation will enable the bird to be 100% healed before being released into the wild.

Open reduction has been recommended for chronic joint luxation or after the failure of a closed reduction. In dogs and cats, the success rate after open reduction is significantly greater than after closed reduction because open reduction can achieve more joint stability than closed reduction (5,6). The methods for open reduction in birds are limited in comparison to those for dogs and cats. Toggle rod stabilization, in which suture material is placed through the femoral head and neck to a toggle pin behind the acetabulum, and transarticu- lar pining, which involves insertion of a pin through the femoral head and neck into the medial wall of the acetabulum, are not recommended in birds because the kidney is located within the pelvis directly adjacent to the acetabulum (2,3,6).

For this reason, suture of the joint capsule and stabilization of the trochanter to the pelvis with a suture is recommended.

These methods are used alone or in combination. In this case, the avulsed joint capsule from the aspect of the cranial dorsal acetabulum did not seem to permit adequate closure.

Therefore, suture of the joint capsule did not help stabilize the joint sufficiently. Stabilization of the femoral neck to the

pelvis with a suture was utilized to achieve more joint stability. After placement of the suture from the femoral neck to the pelvis, secure fixation of the femoral head in the acetabulum was observed. When suture material is placed through the femoral neck and pelvis in dogs and cats, a figure eight pattern between the femoral neck and the pelvis is recommended because it creates a web over the joint and prevents reluxation. In this case, however, a figure eight pattern between the pelvis and the femoral neck was not used. The femoral neck articulates with the dorsal rim of the acetabulum in birds, whereas the femoral head of dogs and cats only articulates at the acetabulum. This joint structure in birds may pose a high risk of damage to the articular cartilage of the joint by the suture material when figure eight pattern between the pelvis and the femoral neck is performed. However, more research is needed to determine whether this high risk of damage applies to birds. Although a figure eight pattern was not used in this case, the joint stability was sufficient to prevent reluxation of the joint. In addition, an Ehmer sling was applied for three days after surgery to further stabilize the joint.

This case study is limited by the short follow-up period, as affected animals should be monitored for a long-term period in order to definitively determine the treatment results. How- ever, it is very difficult to follow wildlife for a long period after treatment because they are usually released back into wild. To overcome this problem, a satellite tracking system can be used for monitoring wildlife, this technique is often impractical due to the high cost. In this case, the range of motion of the affected coxofemoral joint was approximately 20% decreased in comparison to the contralateral limb due to fibrosis of the affected joint. However, an abnormal gait was not observed and the bird used the limb almost normally. To evaluate the functional of the affected limb before release into wild, the bird was placed in a rehabilitation housing unit with a small pond. The bird was able to hunt and forage for food in the small pond using the affected limb.

In summary, placement of the femoral neck adjacent to the pelvis with a suture can be used to successfully treat avian coxofemoral joint luxation. Placement of the femoral neck adjacent to the pelvis with a suture can provide sufficient stabilization of the coxofemoral joint in addition to acceptable limb function.

Reference

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3. Coles BH. Essential of avian medicine and surgery, 3rd ed.

London: Blackwell. 2007; 180.

4. Duff SR. Hip instability in young adult, broiler fowls. J Comp Pathol 1985; 95: 373-382.

5. Fossum TW, Hedlund CS, Hulse DA, Johnson AL, Seim HB,

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52 Eun-Ju Kim, Jong-Hyun Lee, Min-Su Kim, Ki-Chang Lee, Nam-Soo Kim, Gee-Wook Shin and Hae-Beom Lee

Willard MD, Carroll GL. Diseases of the Joints. In: Small animal surgery, 3rd ed. Missouri: Mosby. 2007; 1143-1315.

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Wingers. 1994; 1137-1169.

야생 검은댕기해오라기에서 대퇴관절 탈골의 수술적 교정

김은주*·이종현*·김민수·이기창·김남수·신기욱·이해범¹

전북대학교 수의과대학, *전라북도 야생동물구조관리센터

요 약 : 왼쪽 뒷다리의 파행을 보이는 야생 검은댕기해오라기가 내원하였다. 신체검사에서 왼쪽 뒷다리가 외측으로 90^o

돌아가 있었으며 대퇴관절부위의 부종이 관찰되었다. 혈액검사와 더불어 영상학적 검사가 진행되었다. 골반 방사선 사 진상 왼쪽 대퇴관절의 앞쪽 등쪽 방향 탈골이 확인되었다. 비흡수성 봉합사를 이용하여 탈골을 고정한 후 관절낭 성형 술을 이용한 수술적 방법으로 교정하였다. 수술 10일 후 거의 정상에 가까운 보행을 보였으며, 수술 20일 후 자연으로 복귀되었다. 본 보고는 야생조류에서 대퇴골 탈골의 영상 진단 과정과 수술적 교정방법에 대해 소개하였다.

주요어 : 조류, 검은댕기해오라기, 대퇴관절 탈구, 수술적 교정