Effects of long-term plate fixation with different fixation modes on the radial cortical bone in dogs

A Retrospective Study of Risk Factors Associated with Refracture after Repair of Radial-Ulnar Fractures in Small-Breed Dogs

OBJECTIVE

 The aim of this study was to identify risk factors for refracture after radial union in small-breed dogs.

STUDY DESIGN

 In our retrospective study, medical records of radial-ulnar fracture cases in small dogs treated with plates and screws were reviewed. General information and postoperative course (days until confirmed radial fracture healing, with or without ulnar union, time to final follow-up, with or without plate removal and refracture) were recorded. The fracture line location, screw positions, radial thickness and width, and pixel values throughout the postoperative periods were obtained from the radiographs. The affected limbs were classified into non-plate removal (P) and plate removal (R) groups.

RESULTS

 Refracture occurred in 5 of the 141 limbs at the most distal screw in the P group and 5 of the 40 limbs at the same site as the initial fracture in the R group. Multivariate analysis indicated that refracture was linked to the amount of relative change with growth in the position of the most distal screw in the P group, with pixel value and radial thickness ratios at the same site as the initial fracture in the R group.

CONCLUSION

 Reducing the screw diameter relative to the radial width to the appropriate extent may be considered in cases where the screw positioned at the most distal end of the radius is expected to be relatively proximal as the distal radius grows; not removing the plate may be considered in cases with a decreased radial thickness or bone mineral density beneath the plate during plate removal.

Clinical and Radiographic Outcomes of 1.5-mm Locking Plate Fixation for 30 Radial and Ulnar Fractures in Dogs

OBJECTIVE

 This study aimed to report clinical and radiographic outcomes of dogs that underwent radial and ulnar fracture repair using 1.5-mm locking plate systems.

STUDY DESIGN

 Dogs that had radial and ulnar fractures repaired using 1.5-mm locking compression plate systems at four referral hospitals were retrospectively included. Signalment, body weight, fracture aetiology, fracture location and configuration, radius diameter, plate-bone ratio, repair method, clinical and radiographic outcomes, complications, and time to last follow-up were recorded.

RESULTS

 Thirty fractures in 28 dogs were included. Median body weight was 2.4 kg (range 1.3-5.5 kg). The mean length of the proximal segment relative to the total length of the radius was 67% (range 33-93%). The mean diameter of the radius at its isthmus was 4.9 mm (range 3.1-6.1 mm). The mean plate-bone ratio was 64% (range 48-89%). Radiographic union was documented in 29/30 fractures at a median of 8 weeks postoperatively. Of the cases with long-term follow-up available, 21/24 had a full function and 3/24 had an acceptable function. Five complications occurred, including infection (n = 2), screw migration (n = 1), bandage sores (n = 1), and peri-plate fracture (n = 1).

CONCLUSION

 In this population of miniature and toy-breed dogs, 1.5-mm locking plates provided effective fixation for radial and ulnar fractures. Despite complications in 5/30 fractures, radial union occurred in 29/30, and no dog had an unacceptable function at the last follow-up.

Expression patterns of inflammatory and oxidative stress-related genes in the uterine and ovarian tissues of dogs diagnosed with pyometra based on cervical patency status

This study aimed to investigate the expression patterns of genes associated with inflammation and oxidative stress in ovarian and uterine tissues of dogs with pyometra, categorized by cervical status (open cervix or closed cervix), which influences disease severity. The control group comprised healthy animals undergoing elective ovariohysterectomy. Tissue inflammatory gene expression and Malondialdehyde (MDA) levels were determined while microbial and histopathological examinations were conducted, along with immunohistochemical evaluations. In the closed-cervix group, uterine TNF and IL6 were upregulated approximately 10-fold while IL10 was upregulated nearly 5-fold. TNF expression differed remarkably between the pyometra groups. In the closed-cervix group, PTGS2 and HMOX1 were upregulated approximately 5-fold whereas NFE2L2 expression was downregulated. The closed-cervix group also had the highest uterine MDA levels. Regarding ovarian tissue, MDA levels were higher in the closed-cervix group than in the open-cervix group while IL10 expression was lower in the closed-cervix group than the open-cervix group. In the closed-cervix group, NFE2L2 was downregulated whereas HMOX1 was upregulated. Uterine TNF levels were positively correlated with IL6, IL10, PTGS2, and HMOX1, but negatively correlated with NFE2L2. IL6 was positively correlated with IL10, PTGS2, and HMOX1. NFE2L2 was negatively correlated with IL6 and HMOX1. IL10 was positively correlated with PTGS2 and HMOX1. MDA was positively correlated with TNF, IL6, IL10, PTGS2, NFE2L2, and HMOX1. TNF levels were positively correlated with ovarian PTGS2, and with IL6 and NFE2L2. MDA was positively correlated with PTGS2 and HMOX1. MDA could be an important biomarker for understanding the severity of pyometra. Moreover, TNF expression and its relationships with various studied parameters such as IL10 may contribute to treatment and prognostic biomarker studies in closed-cervix pyometra pathology.

Stress Changes in the Canine Radius after Locking Plate Fixation Using Finite Element Analysis

OBJECTIVE

 The aim of this study was to evaluate the stress changes in the radii beneath the locking plates (LP) of dogs implanted with LP using finite element analysis (FEA).

STUDY DESIGN

 The study included radii harvested from eight dogs. After computed tomography (CT) scans of the forelimb, the articular surface of the radius was fixed using resin. Material tests were conducted to identify the yield and fracture points and for verification with FEA. The CT data of the radius were imported into FEA software. The radii were classified into three groups based on the placement of the LP (nonplate placement, intact group; 1 mm above the radial surface, LP + 1 mm group; 3 mm above the radial surface, LP + 3 mm group). Equivalent, maximum, and minimum principal stresses and minimum principal strain were measured after FEA at the radial diaphysis beneath the plate.

RESULTS

 In shell elements, the LP + 1 mm and LP + 3 mm groups showed a significantly lower maximum principal stress compared with the intact group. In solid elements, the LP + 1 mm and LP + 3 mm groups showed a significantly higher equivalent stress and a significantly lower maximum principal stress compared with the intact group.

CONCLUSION

 When an axial load is applied to the radius, LP placement reduces the tension stress on the cortical bone of the radius beneath the plate, possibly related to implant-induced osteoporosis and bone formation in the cortical bone beneath the plate.

Indications for the removal of implants after fracture healing: A comparison between human and veterinary medicine

Indications for implant removal after fracture healing are still under debate in both human and veterinary medicine. Although hardware removal is a common procedure, it should not be undertaken lightly. Intra and post-operative complications are common and a thorough evaluation of the risks and benefits should be performed. This review aimed to collect and summarise published data on the indications for implant removal in small animals, compare the collected data with human and equine medicine, and investigate the existence of guidelines for this purpose. There is no international consensual agreement for implant removal after fracture healing, neither in small animals nor in human orthopaedics. Decision-making processes are still controversial in some scenarios, thus clear evidence-based protocols for implant removal are needed.

Design and topographic evaluation of a canine humeral anatomic plating system (CHAPS) for humeral condylar fracture repair in spaniels

OBJECTIVE

To design a precontoured plating system for humeral condylar fracture repair in spaniels with humeral intracondylar fissure (HIF) and quantify accuracy of fit of the system on 3D printed bone models.

STUDY DESIGN

Experimental on 3D printed models.

METHODS

The plating system was based on morphometric data obtained from CT. Plates were applied to models and impression material was measured under the plates at points of interest to define plate bone gap (PBG). Data on locking screw interference on plate application were also obtained.

RESULTS

Eleven elbows models were plated. Statistical analysis to assess for any difference in PBG measurements between left and right humuri revealed two loci (3 and 17) under the lateral plate and two loci (3 and 17) under the medial plate. On cumulate portion analysis, 67% of lateral plate loci and 80% of medial plate loci had a PBG of ≤2 mm respectively. An incidence of 2.1% (3/143) screw interference occurred.

CONCLUSION

Design of a contoured plating system for application to humeral models from spaniels with HIF and its application with objective measurement of PBG is described. The majority of the loci measured under both lateral and medial plates had a BPG of ≤2 mm and the incidence of locking screw interference on plate application was low.

CLINICAL SIGNIFICANCE

This novel system may have application for the stabilization of humeral condylar fractures in spaniels avoiding the need for plate contouring and minimizing the incidence of locking screw interference.

A Retrospective Study of Postoperative Development of Implant-Induced Osteoporosis in Radial-Ulnar Fractures in Toy Breed Dogs Treated with Plate Fixation

OBJECTIVE

 This study aimed to evaluate implant-induced osteoporosis (IIO) development in toy breed dogs treated using internal fixation with digital radiographs as the index of pixel values.

STUDY DESIGN

 There were 226 cases (236 limbs) of toy breed dogs with radial-ulnar fractures. Pixel values were measured on radiographs immediately, 2 weeks and 1 to 12 months after surgery. The ratio of pixel values (PVR) represented the bone mineral areal density based on the humeral condyle in the same image. The dogs were grouped based on the fixation methods, age and status of destabilization.

RESULTS

 There was a significant decrease in the PVR at 1 to 12 months postoperatively for all cases. There were not any significant differences in PVR of antebrachial fractures between those repaired with plates using locking head screws, cortex screws or a combination of locking and cortex screws. Implant-induced osteoporosis persisted at 1 to 12 months postoperatively in dogs aged ≧6 months, while the PVR increased after 3 months in dogs aged <6 months. Based on the destabilization method, there was a significant increase in the PVR at 3 months in the plate removal group.

CONCLUSION

 This study suggests that IIO occurs in small dogs treated with plates and screws. Moreover, patients aged < 6 months showed an early postoperative recovery of bone mineral areal density. Further, screw and plate removal could contribute to the recovery of bone mineral areal density.