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The evolution of bone plate design has been with a view to reducing the interface contact between the plate and the underlying bone thereby limiting the perfusion deficiency that develops. Little consequence, however, has been attributed to the drilling of holes in the steps prior to bone plate application; the work present herein attempts to define the vascular response of bone to the trauma of drilling holes. Anaesthetized sheep underwent the creation of drill holes in both tibiae and metatarsi. Animals were then heparinized and euthanatized. Utilizing femoral cannula, perfusion of the vasculature ensued; spalteholz (India ink), disulphine blue and radiocontrast material (barium sulfate). Decalcified histology was performed and correlated with the perfusion studies. Regions of perfusion deficiency were observed immediately adjacent to, and removed from, the drill hole site. Radiographic images showed substantial haematoma formation and vascular disruption in the vicinity of the drill hole site. Histologically, blood vessels immediately adjacent and distal to the drill hole site, contained a proteinaceous/cellular material occluding the vascular space. Our findings support the proposal of a short-term obstruction in cortical blood flow which may contribute to later adaptational osteopaenia following bone plate application. We have observed an acute vascular insufficiency in cortical bone directly related to the trauma of drilling screw holes.

The occurrence of primary endotracheal adenocarcinoma in two 12-year-old cats is reported. Dyspnoea was the most dominant clinical sign in both cases. The endotracheal masses were identified radiographically and removed via thoracotomy and tracheotomy in the first case and cervical tracheal resection and anastomosis in the second case. In both cases, the diagnosis of adenocarcinoma was confirmed histopathologically.

SummaryThe in vitro performances of four recognized fixation methods of femur neck fractures in the dog were evaluated. After a simulated basilar fracture, three multiple pin techniques and a lag screw method were applied to four groups of nine freshly dissected femurs. A standardized force was applied to all specimens as well as five intact femurs and the force-deformation curve and yield points were recorded. Radiographs were taken to determine the mode of failure. The results indicate that the lag screw and three-parallel-pin techniques were significantly stronger than the two-pin methods. The pin techniques failed by either bending and/or slippage, while the lag screw failed by bending and/or pulling in of the screw head into the lateral femoral cortex.An in vitro study, comparing the mechanical performances of four fixation techniques for femoral neck fracture fixation, is presented. The lag screw and three-pin techniques were stronger than the two double-pin techniques. Fixation failure occurred through bending or slippage of the pins, or through bending of the screws or pulling of the screw head into the lateral femoral cortex.

This article describes the different situations that result in interference with fracture healing and discusses the possible causes of such problems. Prevention and treatment of these states are reviewed.

Here’s a farmer that hanged himself on the expectation of plenty! - Shakespeare (1564–1616: Macbeth)

A system already described by Unger and others was used to classify long bone fractures in dogs. The present paper reports experiences using the fracture classification system regarding its ease of use and the ability to analyse the data generated. Three hundred and eighty-six canine long bone fractures were classified from radiographs. Results were assessed by reviewing the medical records or by sending questionnaires to referring veterinarians. There were a few inconsistencies, particularly in classifying proximal ulnar fractures, but the system was easy to use and data retrieval was readily accomplished. Data from the system were used to compare the results of repairs of diaphyseal fractures of the radius/ulna, femur and tibia/fibula. A chi square analysis was used to determine significant differences between the outcome scores of the three fracture types. Fractures of the femoral diaphysis had a statistically poorer outcome than did diaphyseal fractures of the radius/ulna or tibia/fibula.

Fractures of the scapula can be classified into four groups on the basis of the anatomic structures involved: 1. Fractures of the glenoid (articular surface) 2. Fractures of the neck 3. Fractures of the acromion 4. Fractures of the body and spine

The Assyrian came down like the wolf on the fold, And his cohorts were gleaming in purple and gold; And the sheen of their spears was like stars on the sea, When the blue wave rolls nightly on deep Galilee’.

Editorial: ‘All students of animal motion–sooner or later find their way back to the monumental photographic work of Eadweard Muybridge’ - Lewis S. Brown, 1955

Electrical resistance rosette strain gauges bonded directly to the surface of the midshaft of the normal canine tibia were utilized to study the effect of the AO external skeletal fixator on the magnitude and orientation of the peak strain values recorded during locomotion. The application of the fixator in a single lateral bar configuration resulted in a significant decrease in surface bone strain magnitude but in only minor changes in the orientation of those strains. However, in only one of three dogs tested did the addition of a second external connecting bar result in significant further decreases in bone strain.

Electrical resistance rosette strain gauges were bonded directly to the surface of the midshaft of the tibia in four dogs. In vivo strain recording were obtained using a telemetric system allowing the dog relatively free movement. During the stance phase of walking, the cranial surface was mainly in tension while the caudal surface was mainly in compression. The pattern of strain recorded is consistent with craniocaudal bending superimposed on external torsion at the stifle.

A compaiison is made between mongrels and miniature Poodles of the healing of experimentally produced fractures of the radius and ulna. Three different postoperative regimes were used in comparing the factors which predispose to nonunion. Resume. On compare la guerison d'une fracture experimentale du radius et cubitus entre un groupe de chiens croises et un groupe de caniches nains. Trois differentes methodes de soins postoperatoires ont ete instituees en comparant les facteurs predisposant a la non-union. Zusammenfassung. Die Heilung von experimentell erzeugten Frakturen von Radius und Ulna bei Bastardhunden und Zwergpudelm wurde verglichen. Zur vergleichenden Betrachtung von Faktoren die praedisponierend die Frakturvereinigung verhindern, kamen postoperativ drei verschiedene Behandlungsverfahren zur Anwendung.

SUMMARY The Prieur technique was employed to hook plates to fractures and corrective osteotomies. The technique permits rigid internal fixation when one component of the bone is particularly small.

Two types of total hip prostheses were implanted in three dogs that had been previously treated by excision arthroplasty, two for degenerative joint disease secondary to hip dysplasia and one for removal of a fractured femoral neck. Complications occurred in one case when the femoral shaft was split during the reaming process for implantation of the prosthesis and at three weeks after surgery when an oblique fracture of the distal femur occurred. Both complications were treated successfully. The time since surgery varied between eight and 18 months. All three dogs had excellent functional results evidenced by increased joint mobility and freedom from pain.

Twelve surface replacement arthroplasties were performed on the hips of ten mongrel dogs using scaled-down replicas of the Wagner prosthesis. The contralateral hips and two further animals served as nonoperated controls. Animals were killed 5 months postoperatively. Clinical, radiological, histological and fluorochrome-labelling studies were employed to assess the bony and soft tissue reaction to resurfacing arthroplasty. There was no clinical or radiographic evidence of prosthetic loosening. Histological examination disclosed a thick foreign body and chronic inflammatory membrane containing acrylic cement and polyethylene wear particles at the bone-cement interface of both components. Generally, the bone marrow and trabecula were viable. There was evidence of increased bony remodelling and new bone formation in the subchondral area. The similarity between the above findings and those of aseptic component loosening in man suggests a mechanism whereby wear debris initiate a biological foreign body reaction culminating in component loosening.

Strain gauge technology and telemetric transmission were utilized to investigate the dynamic strain patterns along the cortical surface of bone and the response to internal fixation, in vivo. Application of a tension band plate resulted in conversion of normal tensile strain into compressive strain which verified the tension band principle of internal fixation. Creation of a transverse osteotomy did not alter this response, provided that the fragments were rigidly fixed. The plate caused an appreciable decrease in normal surface strain measured from the lateral and medial cortices, illustrating the concept of stress protection.

Lack of mineralization of a fracture of a radius and ulna does not necessarily produce nonunion or pseudarthrosis. Hyaline cartilage may persist at the fracture site beyond 24 weeks. A fracture may be firm although radiographically there is no evidence that the site is mineralized, being bridged only by hyaline and fibrocartilage and not by bone. Resume. On a constate qu'un defaut de mineralisation lors d'une fracture du radius et cubitus ne produit pas necessairement une non-union ou une pseudo-arthrose et que le cartilage hyalin peut demeurer au site d'une fracture au-dela de 24 semaines. Par consequent, une fracture peut etre suffisamment solide, bien que radiographiquement le site n'est pas mine ralise, etant soudee par du cartilage hyalin et fibreux seulement et non pas du tissu osseux. Zusammenfassung. Fehlende Mineralisierung einer Fraktur von Radius und Ulna fuehrt nicht unbedingt zu mangelnder Vereinigung oder zu einer Pseudarthrose, und hyaliner Knorpel mag laenger als 24 Wochen im Frakturgebiet vorkommen. Die Fraktur kann stabil sein, wenn roentgenologisch das Frakturgebiet nicht mineralisiert ist, und lediglich durch hyalinen und fibroesen Knorpel—nicht durch Knochen—ueberbrueckt ist.

“Why is my pain perpetual and my wound incurable, which refuseth to heal?” Jeremiah XV. 18.

The distal femoral epiphyses of 142 marten (Martes americana) and 391 fisher (Martes pennanti), all trapped from November to February in the Algonquin region of Ontario, were radiographed to determine their state of fusion and the presence or absence of scar lines. These criteria indicated that on the average fusion occurred first in female marten, then in male marten, female fisher, and finally in male fisher. Thus the time of fusion in these mustelids was a function of size and possibly also of sex. Radiography of the femur of winter-trapped marten and fisher is not a good method of aging these species because the degree of fusion does not necessarily differentiate juveniles from adults.

In order to assess the response of bone to low-viscosity polymethylmethacrylate, CMW or Simplex acrylic cement was digitally packed while in a doughy state into drill holes in the proximal diaphysis in each of four long bones (humeri and tibiae) of mongrel dogs. Histological assessment was performed in areas of minimal load at the interface between the viscoelastic bone and the acrylic cement. Decalcified and undecalcified sections were evaluated and a remodeling or activity index calculated. Fluorescent labeling studies were performed in order to assess bone growth. Animals were killed at 2, 4 or 5 months. Histological analysis showed a thin connective-tissue membrane containing scattered giant cells and histiocytes at the bone-cement interface. Inflammation was not an important facet of this response. The marrow and trabecular bone were viable, except for scattered localized areas of marrow necrosis and fibrosis immediately adjacent to the cement. The bone adjacent to the cement showed a lower remodeling or activity index, fewer fluorescent bands, and smaller distances between successive bands, suggesting decreased bone formation and turnover. The etiology of these findings may include a vascular disturbance secondary to disruption of the cortical and marrow circulation, temperature effects during cement polymerization, and/or chemical effects from the acrylic monomer.

A new method for repair of femoral capital epiphyseal fractures in the immature dog is described. The technique employs two small AO/ASIF cortical screws inserted in lag fashion from the articular surface into the femoral neck. The screw heads are countersunk, so as not to project from the articular cartilage of the femoral epiphyseal fragment, While this is an early report it is hoped that it will prompt the use of the technique by others so that its long term assessment may be more rapidly determined than by one clinic working alone.

The use of the narrow lengthening plate (NLP) was evaluated in eleven fractures in ten dogs repaired in the Ontario Veterinary College, Veterinary Teaching Hospital. Dogs were evaluated radiographically and clinically. Of the eight dogs with adequate radiographic follow-up radiographic union was demonstrated in seven; one dog had a nonunion at 12 months. Good to excellent clinical results were achieved in eight of 10 dogs. The NLP in conjunction with cancellous bone grafting was considered a good technique for the treatment of comminuted diaphyseal frac-in mid- to large- sized dogs.

Movement between screw threads and bone inhibits bone formation, revascularization and remodeling of dead bone. Movement causes the screw to become enveloped by fibrous tissue in response to necrosis and resorption of adjacent dead cortical bone. This results in a radiologically discernible radiolucent "halo" about the screw, a certain sign of screw loosening.

A total hip surface replacement was successfully performed on eight adult dogs, using a porous-coated, cobalt-chromium- molybdenum alloy acetabular resurfacing component fixed to the acetabulum with 3.5 mm cortical screws. Functional, radiological, histological and fluorochrome labelling studies were used to assess tissue response to the implant. At four months after implantation, seven of the acetabular components were anchored with well organized fibrous tissue. Bone ingrowth had occurred in three components. Failures appeared to be due to technical difficulties encountered during the surgical procedure.