Comparative Efficacy of Limited Contact–Dynamic Compression Plate and Dynamic Compression Plate for Repair of Diaphyseal Femoral Fracture in Dogs

Farah Ijaz^*, Shahla Gull Buk, Muhmmad Arif Khan, Syed Saleem Ahmad, Bilal Haider

*Corresponding author:drfarah14@gmail.com

ARTICLE CITATION: Ijaz F, Bukhari SG, Khan MA, Ahmad SS, Haider B (2014). Comparative efficacy of limited contact–dynamic compression plate and dynamic compression plate for repair of diaphyseal femoral fracture in dogs. Adv. Anim. Vet. Sci. 2 (5): 296–301.
Received: 2013–11–29, Revised: 2014–05–13, Accepted: 2014–05–20
The electronic version of this article is the complete one and can be found online at ( http://dx.doi.org/10.14737/journal.aavs/2014/2.5.296.301 ) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

ABSTRACT

LC–DCP is claimed to be a better implant as compared with the conventional DCP, with respect to low–bone–surface–contact, decreased incidence of porosity, increased and better vascularity of bone tissue, and earlier healing time. In the present study the experimental study was performed on 8– adult dogs divided into 2–groups, A and B. In Groups A and B, DCP and LC–DCP implants were used, respectively. The efficacy of the two plate systems was assessed on the basis of physiological parameters, radio–graphic evaluation. Each dog was radio graphed with medio–lateral projection (ACOMA, JAPAN, Df–50). The radiographs were obtained at an interval of 2 weeks to examine the progress of callus formation with respect to each plate fixation system. Group A showed not good callus formation as some have large callus. Group B dogs showed ideal fixation of implant with accurate Small callus formation. From all this results of this study clearly proved that LC–DCP is better implant than DCP in terms of above parameters for repair of femoral fracture especially in dogs.

INTRODUCTION

The femur is the longest bone in the mammalian skeleton. Femoral shaft fractures can result from high energy as well as low–energy trauma and 30% of patients have multiple injuries in these cases (please give reference to support your statement). Chances of femoral fracture in dogs below 1 year of age are 51.78% and below 2 years of age are 69%. Overall chances of fracture are 29.94% in dogs and most of them are long oblique femoral shaft (73.21%) and supra–condylar fracture (19.64%) (Tercavlioglu, 2009). Fractures can be treated by means of various kinds of external and internal fixation devices. Internal fixation devices include intramedullary pins, elastic stable intramedullary nails (ESIN), bone plates, orthopedic wires, and screws (Roe, 2003). The primary bone plate system is the Dynamic Compression Plate (DCP), in which the holes are designed in such a way that they cause compression of the fracture fragments (Roe, 2003). Their superiority over other implants lies in their characteristics that they can effectively neutralize compression, shearing, rotational and bending forces on the bone (Stiffler, 2004). However despite some advantages, the Dynamic Compression Plates also have some disadvantages such as weakening, osteoporosis and necrosis of the underneath bone. Chances of infection after DCP are generally greater as compared to that after the LC–DCP implants (Perren, 1988). Advantages of LC–DCP over DCP are that it has been designed in such a way that stress is not concentrated at the screw holes. The solid portion of the plate is scalloped at the top and bottom which reduces the area of contact with the bone and hence exerts comparatively less effects on the blood supply (Roe, 2003). The additional benefits of these newer implants are that their torsion and bending properties are comparable with the DCP in the fixation of simple transverse diaphyseal fractures (Miclau et al., 1995).

The present study was designed to evaluate the t two plate fixation systems i.e. DCP plates and LC–DCP plates, in terms of appropriate fracture reduction, implant position, early fracture healing, lesser infection rates, early callus formation and better vascularization of the bone.

MATERIALS AND METHODS

The trial was performed on 8 dogs of local breed of either sex. The dogs were divided into 2 groups, A and B comprising four dogs each. The animals of group A were designated as A1, A2, A3 and A4 and that of group B as B1, B2, B3 and B4.

In group 1, DCP was applied while in group 2, LC–DCP was applied to fix experimentally created long oblique femoral fractures.

Pre–operative dog preparation for surgery: All the dogs were examined for their health status through complete physical examination. All the dogs were kept in kennels of Surgery Section (CMS) of University of Veterinary and Animal Sciences, Lahore. Luke worm water and antibacterial soap Dettol (Lever Broth; Pakistan) were used for bathing. Rabicin vaccine (Rhone Meriux) was administered to all the dogs as a prophylactic measure. Ectoparasites were controlled by using Trichorophan (Seguvon; Symons Pharmaceuticals Pakistan). Fenbendazole was used for control of round worms (Zental suspension; Smith Kline Becham) at the dose rate of 6mg/kg body weight (Green, 2006). The whole limb from the point of hip to the pastern joint was shaved one day before surgery.

In addition to the general surgical instruments, the following special orthopedic instruments were prepared by autoclaving.

1. Periosteal elevator.

2. Lowman’s bone clamp.

3. Bone plates of 2 sizes as follow

1. Dynamic Compression Plate (DCP) 3.5mm broad

2. Limited contact–Dynamic compression plate (LC–DCP) 3.5mm broad.

4. A hand bone drill machine with a set of drill bits of different sizes.

5. Bone saw.

6. Plate screws as with specific size 3.5 mm.

7. Bone hammer.

8. Depth gauge for 3.5 mm plate

9. Bone chisel.

10. A Cerclage wire of 20 gauges.

11. Lag screws of 30 mm, 32mm, and 34mm length.

12. Screw driver according to the top of the screw (hexagonal).

13. Bone tap.

14. Wire cutter

15. Wire twister

Anesthetic consideration: The following protocol was followed:

1. Pre anesthetic medication: Xylazine–HCl at the dose rate of 0.4mg/kg along with atropine sulphate at the 0.02mg/kg body weight before general anesthesia.

2. Anesthetic medication: Animals were anesthetized with Ketamine–HCl at the doze rate 5mg/kg body in combination with Xylaze, in a ratio of 2:1 was given as a general anesthetic before start of surgery. Half of doze was given at once and the remaining half given in small doses with checking of reflexes after small interval of time as per requirement.

Surgical Protocols
For complete aseptic surgery, sterilized surgical gowns and sterilized disposable surgical gloves, caps, masks were worn before the surgical operation and hands of the surgeon, assistant surgeon and assistants were scrubbed properly with six minutes scrubbing protocol before touching to the sterilized surgical dress (Slatter 2003).

First of all, the operative site was clipped and shaved off at lateral side from point of hip to pastern joint and from medial side also. After clipping and shaving, soap was used to clean surgical site. The dog was moved to the operation theatre and restrained in left lateral recumbence on table. Scrubbing was done in linear fashion from centre towards periphery of complete hind limb to avoid infection by povidone surgical scrub (Pyodine surgical, Brooks). Scrubbing was done to make area free from microbes. Sterile surgical drapes were placed around surgical area and around the lower portion of the limb. The first drape was placed in such a fashion that the central opening area covered the limb and whole body of the animal. Then four drapes fashion was secured to patient skin by towel clamp as the patient’s hind quarter is covered. (Slatter 2003)

All surgical instruments including drapes, scissors, forceps, needle holders, scalpel handles, trays and bowels were sterilized in autoclave before surgery are arranged on the sterilized table after scrubbing of my hands.

Surgical Technique
For the surgery, the animal was placed in lateral recumbence with the limb to be operated on top. The femur was exposed through a cranio–lateral approach (Slatter 2003). Then afterwards, a long oblique fracture was induced using a heck saw. After adequate reduction, the respective bone plates were applied in each group using standard procedures (slatter 2003).

Observations
The operated animals were kept under observation in animal house facility for the experimental period of three months and the efficacy of the internal implants were evaluated on the basis of the following parameters:

Clinical Evaluation
It included evaluation through the following parameters.

1. Gait and lameness analysis.

2. Presence of pain.

3. Wound healing.

Radiographic Findings
The animals were restrained in lateral recumbence and radiographs of the femora were obtained through a medial–lateral projection. The radiographs were obtained at an interval of 15–days to examine the progress of callus formation with respect to each plate fixation system. The radiographs also made it convenient to visualize the implant position and ascertain proper reduction of the fracture.

REUSLT

In this experimental study my project DCP had been compared with LC–DCP in presence control by keeping physical findings and Radiographic findings.

Experimental Parameters
The effectiveness of the technique was evaluated through following parameters.

1. Physical findings

2. Radiographic findings

3. Physical Findings

1. Gait and lameness analysis

2. Presence of pain

3. Wound healing

Gait and Lameness Analysis
Animals of each group were tested at various intervals for lameness, according to the grades.

Group A (DCP)

At Walk
During the healing period, the gait was evaluated on the basis of the degree of lameness. This was checked at an interval of 2 weeks after the surgery till three months post–operatively. The dogs showed different degrees of lameness at different periods.

In the beginning lameness was quite pronounced in all the experimental animals; Dog A1 showed three– legged lameness but with the passage of time it showed improvement and at the end of 12 weeks, no signs of lameness were present. Dog A2 and A4 showed marked lameness even after 2^nd week post–operatively, however, at later stages only mild lameness ensued. Dog A3 was weak, lethargic and completely unwilling to stand up post–operatively. At two weeks after the surgery, it developed severe osteomyelitis and signs of 2^nd degree lameness. Finally, after the 3rd week it expired.

Further results of lameness are evaluated in Table 2.

At Trot
Animals in group A were also evaluated for lameness at trot, at four weeks postoperatively. The results were not much different from those at walk. Dog A4 showed marked lameness at 2^nd week which improved with the passage of time till at 12th week it finally resolved with good recovery and showed no signs of lameness.

Assumption
–union and dog A3 expired in 3rd week

Group B (LC–DCP)

At Walk
In group B (LC–DCP), during the healing period after the surgical procedure, the gait was evaluated for signs of lameness at walk. This was checked at an interval of 2 weeks after surgery till the end of the experimental period. The results of the LC–DCP were quite promising in all dogs.

Dogs B1, B2 and B4 showed ideal weight–bearing from the very next day after surgery, owing to ideal fixation of the implant. However, dog B3 showed three–legged lameness at 2^nd week. Radiographs were suggestive of plate displacement. The plate was removed; however, the dog expired at 2^nd week post–operatively due to osteomyelitis and a generalized febrile skin disease.

Further results of lameness are evaluated in Table 3

At Trot
Animals in group B were also evaluated for lameness at trot. This was begun at four weeks post–operatively as in group A. The results were not much different from walk. Dogs B1, B2 and B4 showed good recovery with time, however, Dog B3 showed three–legged lameness at 2^nd week due to implant loosening, and later expired at 2^nd week post–operatively.

Assumption
From above table it is assumed that lameness is absent in 75% of animals. While in 25% it is sever. This was expired later on due to osteomyelitis.

Pain Grading
All the dogs showed normal routine without the exhibition of any sever pain signs except dog A1 and A3 in group A (DCP) and B3 in group B (LC–DCP), which showed severe pain on 2^nd day postoperatively; however, after the injection of Dicloran®(Diclofenac sodium) BD, the pain was alleviated the very next day. Response to pain was recorded according to the following scale:–

Assumption
From table it is assumed that sever pain in 50 % animals and Moderate in 50% at start. Later on controlled but A1 had pain throughout research trial.

Assumption
From table it is assumed that 75 % have moderate and just 25% sever signs of pain.