Phalanx In Horses Research Articles

Experience in the treatment of horses with short incomplete sagittal fractures of the proximal phalanx

Sagittal fractures are the most common injury of the proximal phalanx in horses. Choosing the optimal treatment tactics allows you to eliminate the physiological consequences of injury. The aim of this work was to compare the effectiveness of traditional and surgical methods of treatment of horses with short incomplete sagittal fractures of the putus bone. Thus, the study included horses (n=20) with short incomplete sagittal fractures of the proximal phalanx, which were then divided into two groups. In the first group (n=10), treatment was based on the application of a plaster cast, changing every 14 days. Osteosynthesis by screw fixation was performed in the second experimental group (n=10). Clinical and radiological research methods were used in the work. Complete radiographic healing was confirmed in 100% of animals in the second group, where osteosynthesis was performed by screw fixation, they returned to full athletic load without complications. However, in the first group of horses to which a plaster cast was applied, only 72.7% of animals and 27.3% of horses completely recovered their athletic qualities due to the development of complications, in the form of osteoarthritis changes, were excluded from sports. The proposed method of treating fractures in horses of the second group using the screw fixation method increases the possibility of animals returning to their previous loads. The rehabilitation technique developed and implemented in the clinic expands the possibilities of use in practical veterinary medicine.

Ex vivo comparison of standing and recumbent repair of incomplete parasagittal fractures of the first phalanx in horses.

To assess suspensory ligament extensor branch location and fracture gap reduction with simulation of standing and recumbent cortical bone screw repair of experimental incomplete parasagittal proximal phalanx (P1) fractures. Controlled laboratory study. Twenty equine cadaver forelimbs. Simulated fractures were repaired twice in random order. A proximal cortical bone screw was placed in lag fashion with the limb unloaded (simulated recumbent repair) and loaded to 38% of body weight (range, 375-568 kg; simulated standing repair). Changes in fracture gap width were assessed on computed tomography (CT) images and with intraplanar force-sensitive resistors measuring voltage ratios (V△ ) between loaded recumbent (R-1) and standing repair simulations (R-2). Extensor branch borders were determined relative to implant position and sagittal P1 width on transverse CT images. P ≤ .05 was considered significant. Standing repair simulation-associated fracture gaps were not wider than in R-1 while controlling for confounding factors (loading weight, implant position, or animal age; P > .7, repeated-measures analysis of variance). Voltage ratio data associated with R-2 were not smaller than with R-1 (mean difference, 0.002 ± 0.052; one-sided Wilcoxon signed-rank test, P = .27). More of P1 width was approachable palmar to extensor branches when limbs were loaded (0.804 ± 0.314 cm) vs unloaded (0.651 ± 0.31 cm; paired Student's t test, P < .001). Simulated standing repair was not associated with inferior fracture reduction compared with loaded simulations of recumbent repairs. Limb loading affected extensor branch location relevant to implant positioning. Unloading during standing repair of incomplete parasagittal proximal P1 fractures may not be required to optimize fracture reduction.

Comparison of 3D‐assisted surgery and conservative methods for treatment of type III fractures of the distal phalanx in horses

SummaryThe aim of this retrospective study was to compare the outcome of conservative methods and 3D‐assisted surgery for treatment of type III fractures of the distal phalanx with regard to recovery time and the development of osteoarthritis (OA) in the distal interphalangeal joint (DIPJ). The medical records of all horses with type III fracture of the distal phalanx referred to the Equine Department, Vetsuisse Faculty, University of Zurich, between 1992 and 2016 were reviewed. The severity of lameness at initial examination, radiographic evaluation, treatment (conservative, group A; 3D‐assisted surgery, group B), complications, outcome and recovery time were determined. Follow‐up examinations included clinical and radiographic examinations. Of 33 horses, 15 received conservative treatment and 18 underwent surgery. Eleven of the 15 (73.3%) horses in group A returned to their intended use and four were subjected to euthanasia or remained chronically lame. The median recovery time was 240 days (95% CI, 180–374). Thirteen of 15 (86.7%) horses developed OA of the DIPJ within 5 months of the fracture. In group B, 16 of 17 (94.1%) horses returned to their intended use, one horse remained chronically lame, and one horse was subjected to euthanasia because of unrelated reasons. The median recovery time was 139 days (95% CI, 120–270), and seven horses (38.9%) developed OA of the DIPJ within 5 months of the fracture. Overall, the screws had to be removed in five fluoroscopic‐assisted surgery cases (three because of implant infection and two because of severe lameness), in one computer‐assisted surgery case due to severe lameness and in one computed tomography‐assisted surgery case because of implant infection. In conclusion, there was no significant difference in time for recovery of type III fractures of the distal phalanx between the two groups, but surgical treatment led to significantly fewer cases of OA in the DIPJ as determined by subjective radiographic evaluation (P = 0.015).

Long-term clinical and radiographic results after lag screw ostheosynthesis of short incomplete proximal sagittal fractures of the proximal phalanx in horses not used for racing.

To determine long term outcomes of nonracing equines athletes treated for short incomplete proximal sagittal fractures of the proximal phalanx (SIPSFP1) by lag screw fixation. Retrospective study. Thirty-one horses. Medical records from horses with an SIPSFP1 (2008-2014) were reviewed. Long-term (≥12 months) outcomes were assessed with telephone interviews and clinical and radiographic examinations. Warmblood was the predominant breed in cases included in the study. Among horses with long-term interview information, 27 of 31 returned to previous athletic activity level. In total, 15 horses with 19 fractures had clinical and radiographic assessment after a minimum of 12 months. Among those, nine of 15 horses were sound at the trot, and six of 15 were mildly lame. Complete radiographic healing was confirmed in six limbs, and the facture line was evident in 13. The position of the proximal screw was not associated with radiographic fracture healing or return to soundness. Most horses treated for SIPSFP1 with lag screw fixation returned to previous activity levels, although radiographic fracture healing remained incomplete 12 months or more after surgery. Lag screw fixation is a valid treatment for horses not used for racing that are experiencing an SIPSFP1 and results in a high rate of return to intended use, although complete radiographic fracture healing cannot be expected.

A detailed radiographic description of the nutrient foramen of the dorsal cortex of the proximal phalanx in horses

SummaryThe purpose of this study was to provide a detailed radiographic description of the nutrient foramen (NF) of the dorsal cortex of the proximal phalanx (Pl) which may aid the veterinary practitioner in identification of the NF and subsequently prevents misinterpretation of this radiographic finding. Medical records of 190 horses (116 Standardbreds, 64 Warmbloods and 10 Friesians) presented for standard radiographic screening were retrospectively reviewed. All four lateromedial radiographs of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints were evaluated for presence, localisation and trajectory of a dorsal NF by a registered radiologist and a surgical resident. In 27.5% (209/760) radiographs, a full‐cortex NF was identified. The Standardbred‐group represented the majority with 30% (138/464) diagnosed NF, followed by the Warmblood‐group with 26% (66/256) NF and the Friesian‐group with 13% (5/40) NF. Most NF had a unilateral distribution (62%). Fifty per cent of the NF entered the dorsal cortex at 47.4–59.2% of the total dorsal length of Pl. Four different trajectory types were noted; a sigmoid‐shaped course (44%), a straight course (33%), a palmar/plantar‐curved course (14%) and a dorsal‐curved course (9%). The consistent entrance location of the NF into the dorsal cortex and medullary cavity, together with its typical trajectory aids the veterinary practitioner in distinguishing an NF from a pathologic fissure or fracture. Comparison with radiographs of the contralateral limb is unreliable as most NF are identified unilaterally.

In vitro comparison of linear vs triangular screw configuration to stabilize complete uniarticular parasagittal fractures of the proximal phalanx in horses.

To assess fracture gap reduction and stability of linear vs triangular 4.5-mm lag screw repair of experimental, uniarticular, and complete forelimb proximal phalanx (P1) fractures. Experimental. Fourteen equine cadaver limbs/horses. Simulated fractures were repaired with 2 lag screws under 4-Nm insertion torque (linear repair). Computed tomography (CT) imaging was performed with the leg unloaded and loaded to forces generated while walking. The fracture repair was revised to include 3 lag screws placed with the same insertion torque (triangular repair) prior to CT. The width of the fracture gap was assessed qualitatively by 2 observers and graded on the basis of gap measurements relative to the average voxel size at dorsal, mid, and palmar P1 sites. Interobserver agreement was assessed with Cohen's κ. The effect of repair type, loading condition, and measurement site on fracture gap grades was evaluated by using Kendall's τ-b correlation coefficients and paired nonparametric tests. Significance was set at P ≤ .05. Agreement between loading and fracture gap widening was fair in triangular (κ = 0.53) and excellent in linear (κ = 0.81) repairs. Loading resulted in fracture gap distraction in linear repairs (Plinear = .008). Triangular repairs reduced fractures better irrespective of loading (Punloaded = .003; Ploaded < .001). The type of repair was not correlated with fracture gap grades at unloaded mid and loaded dorsal P1 sites. Repair of uniarticular complete parasagittal fractures with a triangular screw configuration improved in vitro fracture gap reduction and stability. Triangular lag screw repair likely improves biomechanical conditions during postoperative weight bearing.

Comparison of the VetGate and SurgiGATE 1.0 computer assisted surgery systems for insertion of cortex screws&#x0D;across the distal phalanx in horses – an in vitro study

The In vitro experimental study on five cadaveric equine limb pairs (n=10) was conducted to evaluate the functionality and precision of the VetGate Computer Assisted Surgery (CAS) system during insertion of two 4.5mm cortex screws across virtual midsagittal fractures of the distal phalanx (P3) in the horse and to compare the results with those achieved with the SurgiGate 1.0 CAS-System in a similar study. In each specimen wo 4.5mm cortex screws were inserted computer assisted in lag fashion facilitated by the VetGate CASSystem. In none of the specimens did screw penetration of the articular- or solar surface or the semilunar canal, occur. The difference between optimal and actual screw length is significantly better in this study compared to a similar study conducted with the SurgiGATE 1.0 CAS-System. The results achieved with the VetGate CAS-System are even more precise than with the SurgiGATE 1.0 CAS-System (p<0.001). The VetGate CAS-System allows exact screw placement at delicate locations.

Does subchondral bone of the equine proximal phalanx adapt to race training?

Sagittal fractures of the first phalanx are a common, potentially catastrophic injury in racehorses. These fractures are often linked to an acute, one time, biomechanical event; however, recent evidence implies that chronic exposure to stress can lead to the accumulation of bony changes that affect the structural integrity of the bone and increase the likelihood of fracture. The aim of the study was to compare variations of two common metrics of bone adaptation - subchondral bone density and thickness across the proximal articular surface of the first phalanx in Thoroughbred horses that (1) raced but never experienced a first phalanx fracture (Raced Control); (2) raced and had experienced fracture of the contralateral first phalanx (Contralateral to Fracture); (3) had never raced or experienced a first phalanx fracture (Unraced Control). A total of 22 first phalangeal bones were sampled post-mortem and imaged using micro-computed tomography calibrated for mineral density measures. Measurements of volumetric subchondral bone mineral density and thickness were taken from images at five sites from medial to lateral, in three coronal planes (25, 50 and 75% dorsal-palmar). At each of the 15 sites, measurements were repeated and averaged across 10 adjacent micro-computed tomography slices of bone, spanning 0.75mm. The magnitude and variance of these measurements were compared between sites and between cohorts with non-parametric statistical tests. Across the proximal osteochondral surface of the first phalanx, the pattern of subchondral bone volumetric bone mineral density and thickness varied with each coronal section studied. The subchondral bone thickness was greater for the central and dorsal coronal sections, compared with the palmar section. For the race-fit groups (Raced Control and Contralateral to Fracture), the highest volumetric bone mineral density was in the central sagittal groove. The volumetric bone mineral density was significantly greater in the sagittal groove in the central coronal section in the raced than the unraced group. The Contralateral to Fracture group demonstrated significantly greater variance of volumetric bone mineral density compared with the Raced Control and Unraced Control (P<0.0001), with no difference in variance noted between the Raced Control and Unraced Control groups. There was a small (R rank=0.3) but significant correlation between subchondral bone volumetric bone mineral density and thickness in the Contralateral to Fracture group (P=0.005). The findings demonstrate that differences exist in subchondral bone volumetric bone mineral density and thickness across the proximal osteochondral surface of the equine first phalanx in horses with different training histories. The findings also demonstrate that the subchondral bone of the sagittal groove of the equine first phalanx adapts to race-training in the race-fit groups (Raced Control and Contralateral to Fracture) with an increase in volumetric bone mineral density relative to unraced controls. Within the race-trained groups, the Contralateral to Fracture bones had a greater variance of volumetric bone mineral density, suggesting that stress-induced bone adaptation had become more erratic, potentially contributing to the aetiology of sagittal fractures of the first phalanx in the Thoroughbred racehorse.

Clinical features, diagnosis and management of fractures of the distal phalanx in horses

Fractures of the distal phalanx are not an uncommon cause of lameness and occur in horses of all ages, breeds and disciplines. Many fractures present with severe lameness and obvious localising clinical signs but others present a diagnostic challenge. The prognosis for these fractures is also highly variable, depending on their configuration.

Using magnetic resonance imaging to diagnose non‐displaced fractures of the second phalanx in horses

Two horses presented with a history of severe lameness that was localised to the area around the second phalanx (P2) of one forelimb. Radiographs of the second phalanx of both horses were unremarkable, apart from some smooth periosteal new bone production on the dorsum of P2. Magnetic resonance imaging revealed a non‐displaced fracture of P2 in both horses. One horse was euthanased because of a poor prognosis for racing, but the second horse was treated conservatively and salvaged for breeding. Magnetic resonance imaging is a newer imaging modality in horses and may be useful in diagnosing cases of obscure lameness.

In this issue – November 2010

Management and preventive health care in aged horses · Echocardiographs in healthy Thoroughbred foals · Surgical stapling technique for caecal impaction in horses · MRI of the second phalanx in horses · Radiotransmitters in snakes · Nasotracheal intubation of a kangaroo · Avian tracheal resection and anastomosis · Nasal bot fly in a cat · First report of Cryptosporidium andersoni in Australian cattle

Medullary Plasma Pharmacokinetics of Vancomycin After Intravenous and Intraosseous Perfusion of the Proximal Phalanx in Horses

To study the pharmacokinetics of vancomycin in plasma obtained from the medullary sinusoids of the proximal phalanx (P1) after intravenous (IV) and intraosseous (IO) regional limb perfusion (RLP). Experimental study. Twelve horses. IV and IO RLP were performed in 2 groups (n = 6) of horses. Vancomycin hydrochloride (300 mg in 60 mL 0.9% NaCl) was randomly infused in 1 front limb, with the contralateral limb as control (60 mL 0.9% NaCl). A hole was drilled in the lateral cortex of P1, and blood samples from the medullary sinusoids of P1 were collected before infusion, and 15, 30, 45, 65, and 90 minutes after beginning infusion. Samples were centrifuged and plasma vancomycin concentrations determined. Vancomycin concentrations were compared over time and between routes using a 2-way repeated measures ANOVA. Pharmacokinetic variables were compared with a Kolmogorov-Smirnov test. Significance was set at P<.05. No vancomycin-induced clinical side effects such as lameness or swelling were observed. Both techniques, IV and IO, produced high vancomycin concentrations in the sinusoidal plasma of the P1, which remained above the minimum inhibitory concentration value for methicillin-resistant Staphylococcus aureus (MRSA) during the 90 minutes study. Concentrations and pharmacokinetic variables were not significantly different comparing both routes. IV and IO routes produced similar antimicrobial perfusion of the medullary cavity of P1. Either IV or IO routes for perfusion are likely to be equally selected when planning RLP with vancomycin.

Conservative treatment of intra-articular distal phalanx fractures in horses not used for racing

To determine the success rate and whether specific patient and treatment factors influenced the outcome after conservative treatment with a bar shoe with quarter clips of intra-articular fractures of the distal phalanx in horses not used for racing. Retrospective study. Thirty-two client-owned horses. Hospital records of horses that had been treated conservatively for intra-articular fractures of the distal phalanx at Skara Equine Hospital or Halland Animal Hospital in Sweden between 1995 and 2001 were reviewed. Racehorses in active training and horses affected with other musculoskeletal diseases were excluded from the study. Follow-up was performed by questionnaire and telephone inquires to the owners 1 to 7 years after injury. Twenty-two horses (69%) returned to their previous or expected level of use and did not wear their bar shoe when they were put back into training. There was no statistically significant correlation between outcome and patient or treatment variables, or bony union of the fracture. Conservative treatment of intra-articular fractures of the distal phalanx carries a fair prognosis for return to previous or expected level of use in horses not used for racing. Radiographic evidence of fracture healing and age of the patient do not seem to influence the prognosis. Horses not used for racing do not need to be shod with a bar shoe with quarter clips for the rest of their athletic career.

Management of comminuted fractures of the proximal phalanx in horses: 64 cases (1983-2001).

To report the outcome of surgical treatment of comminuted fractures of the proximal phalanx in horses. Retrospective study. 64 horses. Medical records and radiographs were reviewed to obtain information regarding signalment, fracture classification, and treatment. Follow-up information was obtained by telephone conversation or evaluation of production records. Thirty-eight horses had moderately comminuted fractures of the proximal phalanx. Two horses were euthanatized immediately. Fractures of the proximal phalanx in 36 horses were repaired with open reduction and internal fixation with a successful outcome in 33 (92%) horses. Reconstruction of the fracture was performed in most horses by use of a long curved incision, transection of the collateral ligament of the metacarpophalangeal or metatarsophalangeal joint, and open exposure of the proximal articular surface of the proximal phalanx. Twenty-six horses had severely comminuted fractures of the proximal phalanx. Six horses were euthanatized immediately. One horse was euthanatized after 9 days of treatment with a cast alone. Severely comminuted fractures of the proximal phalanx in 13 horses were treated with an external skeletal fixation device, and fractures healed in 8 of those horses. Six horses with severely comminuted fractures of the proximal phalanx were treated with transfixation pins incorporated into a fiberglass cast, and fractures healed in 4 horses. Moderately comminuted fractures of the proximal phalanx can be successfully repaired; however, fractures that are too severe to permit accurate reconstruction of the fragments remain difficult to treat and horses have only a fair prognosis for survival.

New approach for quantitative assessment of articular cartilage degeneration in horses with osteoarthritis.

To evaluate a modified digital imaging technique for quantitative assessment of the grade of osteoarthritis across the proximal articular surface of the first phalanx in horses. 6 metacarpophalangeal (fet-lock) joint specimens from 6 horses with various stages of osteoarthritis. First phalanx specimens, together with 4 gray scale reference calibration targets, were positioned in a bath with the proximal articular cartilage surface submerged in saline (0.9% NaCl) solution. Digital images were obtained from the articular surface before and after staining with Indian ink. Computer-controlled gray level analysis of the nonstained and Indian ink-stained cartilage surfaces and gray scale reference calibration targets was performed by use of the mean pixel value (based on 255-gray scale). An increase in the mean pixel value after staining was used to calculate the cartilage degeneration index (CDI). The CDI of the proximal articular cartilage surface of the first phalanx specimens ranged from 9.2 +/- 5.7 (early stage osteoarthritis) to 41.5 +/- 3.6% (late stage osteoarthritis). The effect of repeating the measurement 6 times in nonstained (including repositioning) and stained specimens (including repositioning and restaining) was not significant. Up to 10 measurements of nonstained specimens could be made without refreshing the bath solution. In stained specimens, mean gray level increased significantly after the sixth measurement. The modified digital imaging technique allowed quantitative assessment of cartilage degeneration across the articular cartilage surface. The CDI is the first quantitative measure for osteoarthritis-induced cartilage degeneration over an entire joint surface in horses.

Double-plate fixation of comminuted fractures of the second phalanx in horses: 10 cases (1985-1993)

Objective— To determine the technique used, and the outcome for, double-plate fixation of comminuted fractures of the second phalanx of horses Design— Retrospective analysis of medical records. Animals— l0 horses with comminuted fractures of the second phalanx that were treated by use of double-plate fixation. Procedure— Two 4- to 6-hole dynamic compression plates were abaxially placed to achieve arthrodesis of the proximal interphalangeal joint and fixation of the fracture of the second phalanx. Results— Arthrodesis and fracture healing were detected in all horses. Clinical Implications— Horses with comminuted fractures of the second phalanx that are treated with double-plate fixation have an excellent prognosis for survival and use as broodstock, and have an increased potential for return to useful function.

Histologie appearance of axial osteochondral fragments from the proximoplantar/proximopalmar aspect of the proximal phalanx in horses

Summary Osteochondral fragments from the axial proximoplantar/proximopalmar region of the proximal phalanx were removed from 38 joints in 30 horses. Ninety-three percent of the horses were Standardbreds, and 28 of the 30 had a low-grade lameness. All but 1 of the horses had hind limb involvement. A total of 43 fragments were removed. Most (71%) of the fragments involved the medial aspect of the joint and had to be dissected from a covering of synovial tissue. Histologically, the circumference of most fragments consisted of a transition zone at the attachment of the joint capsule, a region of nonarticular, non-weight-bearing cartilage, a region where organized, dense connective tissue, presumably remnants of the short sesamoidean ligament were attached, and a region consisting of irregular truncated bony surfaces covered by mature fibrous tissue, which appeared to be the result of healing of a chronic fracture. There were several areas of degenerate hyaline cartilage, but no areas of normal hyaline cartilage or areas containing retained cartilage cores or other evidence of delayed endochondral ossification. Immunohistochemical staining of 4 segments from 1 horse revealed sensory substance P immunoreactive nerves in the fibrous tissue surrounding the bony fragments and within the central cancellous spaces. The histologic appearance suggests that these osteochondral fragments may be a result of fracture, rather than a manifestation of osteochondrosis.

Fractures of the distal phalanx in horses.

Nineteen cases of fracture of the distal phalanx in horses are reviewed. This represented 1.1% of the total number of horses seen at Murdoch University Veterinary Hospital (MUVH) over a 32-month period. All horses were managed conservatively. Eight horses made a complete recovery. Three are being trained again and are not lame. Four horses made a limited recovery. Two horses are still resting and one horse was killed humanely when it still showed lameness after 2 years. One horse was killed humanely after the fracture was first diagnosed.