Distraction osteogenesis at the site of neutral wedge ostectomy for angular limb deformity in the hind limb in 2 young dogs

Our objective was to report the use of distraction osteogenesis at the site of angular limb deformity correction using external skeletal fixation for treatment of 1 femoral and 1 tibial angular limb deformity in 2 large-breed puppies. Medical records were reviewed from 2 dogs (a 7-month-old intact male golden retriever and a 4-month-old intact female German shepherd mixed breed) diagnosed with angular limb deformities and truncation of a pelvic limb. Surgical treatment consisted of neutral wedge ostectomy and distraction osteogenesis at the site of bone deformity with an external skeletal fixator (ESF). The surgical technique and postoperative period of distraction osteogenesis were reviewed along with postoperative complications and clinical outcomes after complete bone healing was evident radiographically. Both dogs had adequate bone formation during distraction osteogenesis and the ESFs remained intact and structurally stable. At ESF removal, femoral length had increased 2.6 cm for Dog 1 and tibial length increased 3.88 cm for Dog 2, distal femoral valgus improved 16.3 degrees for Dog 1, and tibial procurvatum improved 19.5 degrees and distal tibial valgus improved 6.2 degrees for Dog 2. At the last follow-up examinations, 5 mo (Dog 1) and 3 mo (Dog 2) postoperatively, both dogs were ambulating without any visible lameness. Key clinical message: Acute angular correction and subsequent distraction osteogenesis at the site of bone deformity and corrective ostectomy using an ESF enabled successful treatment of femoral (Dog 1) and tibial (Dog 2) truncation and angulation in 2 large-breed puppies. Optimal deformity correction and lengthening were achieved through distraction osteogenesis at the site of neutral wedge ostectomy, minimizing soft tissue dissection and risk for potential complications that can occur with bifocal deformity correction (i.e., correction of the deformity at 1 osteotomy/ostectomy and correction of bone length at another, remote osteotomy).

Locking compression plate osteosynthesis of complicated mandibular fractures in six horses

Complicated mandibular fractures were recognised in one foal, one pony and four horses. The foal was two months old while the adult animals ranged in age from 12 to 24 years. Three horses had a unilateral horizontal ramus fracture. Two fractures were open and one was closed. Comminution was present in one of these patients while the other two horses had marked displacement of the fragments. Two suffered from comminuted fractures of the horizontal and vertical ramus of the mandible. One of these patients had open and infected fractures. One foal had a bilateral horizontal ramus fracture with marked periosteal 'new bone' formation and malalignement which required corrective osteotomy. Each horse underwent locking compression plate (LCP) osteosynthesis consisting of open fracture reduction and application of one to three 4.5/5.0 mm LCP at the ventral, lateral or caudal aspect of the mandible under fluoroscopic control. Two 3.5 mm LCP were used in the foal. Plate fixation was supported by application of a cerclage wire construct between the incisor and premolar teeth in most patients. Complete fracture healing, with an excellent functional and cosmetic outcome, was achieved in all of the patients. Complications encountered included seroma formation, screw and wire breakage, as well as implant and apical tooth root infections. The LCP was removed after fracture healing had occurred in four patients.

Unifocal internal and external bone lengthening with circular external skeletal fixator in 5 dogs

The purpose of this study was to investigate the effectiveness of treatment of long bone defects and extremity shortness in 5 dogs using circular external skeletal fixator. In one case a bone necrosis and osteomyelitis shortened radius by 7.0 cm; however in others extremity shortening between 3.0 and 6.0 cm affected radius-ulna or tibia. 2 or 3 rings of 80.0-100.0 mm diameters, and 3 rods were used as a circular external skeletal fixator. The distractions at the rate of 0.5 mm X 2 times/day were performed following a latent period of 3 days after the corticotomy. Unifocal internal lengthening for case 1 and unifocal external lengthening for the others were performed. Distraction was performed between 30 and 70 days (mean 50 days). It was noted that the circular external skeletal fixator was well-tolerated in all cases. The first usages of limbs in all cases were on postoperative day between 8 and 43 (mean 22 days). The radiographic follow-up examinations revealed a complete consolidation on postoperative day between 35 and 75 (mean 55.6 days). The fixators were removed on the postoperative day between 45 and 85 (mean 65 days). The treatment was successful in restoring the appropriate length of the limbs. After removing the fixator, functional and cosmetic results were graded as excellent in 3 cases, good in one case and fair in one case.

Limb lengthening in three dogs using distraction rates without a latency period. Radius/ulna, tibia, femur

OBJECTIVE

To report three clinical cases suffering from limb shortening secondary to monostotic physeal closure, in which distraction osteogenesis had been performed without a latency period and with high distraction rates.

METHODS

Three dogs had limb lengthening performed, using an Ilizarov ring fixator in two dogs and a linear dynamic fixator in the other dog. Bone lengthening achieved for a radius/ulna was 27 mm at 2 mm per day , a tibia was 78 mm at 3 mm per day, and a femur of 45 mm was 3 mm per day .

RESULTS

Complications related to pin loosening occurred in each case, thus requiring surgical corrective procedures, but these did not affect the final outcome. Lateral bowing of the bar and bone and some musculo-cutendinous contracture occurred in the femur. Fixation frames were on for 12 weeks in Case 1, eight weeks in Case 2 and nine weeks in Case 3. All three of the cases had a good functional outcome.

DISCUSSION

The faster rates of lengthening were not associated with any long-term deleterious soft tissue complications, but they were associated with pin loosening and bending of the bar. In each case there was excellent osteogenesis.

CONCLUSIONS

From the results achieved in these three cases it can be concluded that a latency period prior to distraction osteogenesis may not be necessary. Also, distraction rates up to 3 mm per day can be used to shorten the time needed to achieve lengthening; however further studies are needed to investigate the high level of complications.

Transverse ulnar bone transport osteogenesis: a new technique for limb salvage for the treatment of distal radial osteosarcoma in dogs

OBJECTIVE

To develop instrumentation and a technique for transverse ulnar bone transport osteogenesis in dogs.

STUDY DESIGN

Cadaveric study and in vivo validation (1 dog).

SAMPLE POPULATION

Paired cadaveric antebrachii (n=10 dogs) and 1 live dog.

METHODS

Circular fixator constructs were applied and fitted with reeling or linear motors designed to transport an ulnar segment transversely into a defect created by excising the distal 50% of the ipsilateral radius. A longitudinal osteotomy of the adjacent ulna was created and the segment was transported across the radial defect. Pre- and post-distraction CT scans were used to compare the efficacy of each construct. The procedure was performed unilaterally in a live dog using the reeling motor (RM) construct.

RESULTS

Both constructs effectively transported the ulnar segment into the defect. Subjectively, the RMs were easier to apply and operate. No significant differences were observed in the objective measures of efficacy between the 2 construct types. The live dog produced viable regenerate bone after transverse ulnar bone transport.

CONCLUSIONS

Transverse ulnar bone transport should be considered a potential method for limb salvage in dogs with osteosarcoma (OSA) of the distal radius. The RMs were effective and clinically applicable.

CLINICAL RELEVANCE

Transverse ulnar bone transport osteogenesis affords the benefits of longitudinal radial bone transport osteogenesis, allowing resolution of large longitudinal radial defects in a substantially less time as a result of shortening the transport distance. This would be beneficial when treating conditions such as OSA where minimizing convalescence and maximizing quality of life is a priority.

Intramedullary pinning of metacarpal and metatarsal fractures in cats using a simple distraction technique

OBJECTIVE

To describe a simple technique of intramedullary (IM) pinning for open reduction and internal fixation of metacarpal and metatarsal fractures in cats and evaluate outcome.

STUDY DESIGN

Retrospective study.

ANIMALS

Cats (n=17).

METHODS

Medical records of cats with metacarpal and metatarsal fractures treated by a specific IM pinning method with Kirschner wires were reviewed. Types of fractures and number of pins used were recorded. Pre- and postoperative radiographs were evaluated. Outcome was assessed based on clinical examination, evaluation of radiographs, and owner questionnaire.

RESULTS

Seventeen questionnaires were evaluated. Thirteen cats had a final recheck and radiographic assessment. Eight cats were lost to follow-up. Sixteen owners (94%) reported no obvious change in their cat's gait after treatment. One owner reported excellent function in her cat despite a slightly abnormal gait because of bent implants.

CONCLUSIONS

IM pinning after distraction of bone fragments is a reliable technique for treatment of metacarpal and metatarsal fractures in cats. Complications associated with fracture healing may or may not be associated with lameness.

CLINICAL RELEVANCE

IM pinning used in conjunction with appropriate bandaging for 4 weeks yields excellent functional outcome for treatment of metacarpal and metatarsal fractures in cats. Metacarpo- and metatarsophalangeal joint damage is prevented using this technique.

Evaluation of delayed-image bone scintigraphy to assess bone formation after distraction osteogenesis in dogs

OBJECTIVE

To quantitatively assess distraction-induced bone formation in a crural lengthening model in dogs by use of delayed-image bone scintigraphy.

ANIMALS

12 mature Labrador Retrievers.

PROCEDURE

Dogs were randomly allocated to 1 of 3 groups. A circular external skeletal fixation system was mounted on the right crus of each dog. Osteotomy of the distal portion of the tibia and fibula was performed in groups 1 and 2 and was followed by a lengthening procedure of 10 mm in the first group only. The third group served as sham-operated controls. Delayed-image bone scintigraphy with technetium-99m hydroxy methylene diphosphonate was performed 2, 4, and 6 weeks after surgery. Delayed-image-to-region-of-interest, delayed-image-to-crural, and delayed-image-to-femoral scintigraphic activity ratios were calculated. New bone formation was quantified by use of densitometric image analysis, and values for the scintigraphic ratios were compared.

RESULTS

In the distraction and osteotomy groups, delayed-image-to-region-of-interest and delayed-image-to-crural ratios increased significantly. Although densitometric image analysis revealed increased bone formation after distraction, the region-of-interest ratios and crural ratios were similar in both groups. All dogs had increased delayed-image-to-femoral ratios.

CONCLUSIONS AND CLINICAL RELEVANCE

Delayed-image bone scintigraphy ratios were not effective at differentiating between the amounts of distraction-induced bone and osteotomy-induced bone. Metabolic bone activity in the adjacent femur was increased as a consequence of circular external skeletal fixator placement. Delayed-image bone scintigraphy was not adequately sensitive to quantitatively monitor bone formation but may be useful as an early predictor of bone healing.

The efficacy of the bone markers osteocalcin and the carboxyterminal cross-linked telopeptide of type-I collagen in evaluating osteogenesis in a canine crural lengthening model

The aim of the present study was to determine the efficacy of the bone markers osteocalcin (OC) and carboxyterminal cross-linked telopeptide of type-I collagen (ICTP) in evaluating new bone formation in the dog, using commercially available immunoassay kits. Dogs were randomly divided into three groups and a circular external skeletal fixation system (CESF) was mounted on the tibia. In the first group a distraction osteogenesis procedure of the crus was performed. The second group received an osteotomy without crural lengthening, whereas the third group served as a sham-operated control. Bone formation was assessed using densitometric image analysis of crural radiographs. Despite significant differences in the amount of newly formed bone, this finding was not reflected in the plasma levels of OC and ICTP. In conclusion, OC and ICTP were not efficacious as markers of bone formation and resorption during osteogenesis in this canine model.

Treatment of segmental tibial defects using acute bone shortening followed by gradual lengthening with circular external fixator

The aim of this study was to clinically and radiographically evaluate acute bone shortening followed by gradual lengthening in the treatment of large segmental tibia defects induced in seven clinically normal dogs. A circular external fixator was assembled with one proximal 5/8-circle ring, one middle ring and one distal ring connected with three rods. Thirty per cent of the tibia and fibula were removed in the middle and distal parts of the diaphyses, between the middle and distal rings. Acute bone shortening with compression of proximal and distal segments was performed. A subperiosteal osteotomy was performed between the half-ring and middle ring. Bone distraction started 7 days after surgery; after lengthening, the apparatus was left in place for 14 weeks for consolidation of regenerated bone. The frame was removed at the end of this period, and the dogs observed for four more weeks. Functional results were considered excellent in two, good in three and fair in the other two dogs. Bone regeneration within the distraction gap was obtained 14 weeks after neutral fixation period. We concluded that acute bone shortening followed by gradual lengthening by Ilizarov method can be used to treat extensive tibial defects in dogs, although it presents limb temporary abnormal limb shape and unequal length as early disadvantages.

Treating pedal shortening in a dog by metatarsal distraction osteogenesis

A five-month-old, male German shepherd dog was presented with a left hindlimb deformity. Wearing a cast for a prolonged period to treat left metatarsal fractures at eight weeks of age had resulted in physeal closure of the calcaneus, metatarsals and phalanges. Hyperextension of the phalanges and ulceration of the plantar skin proximal to the main tarsal pad were seen. The left foot was 40 mm shorter than the right. At seven months of age, a modified circular external skeletal fixator (CESF) was used to perform distraction osteogenesis of the metatarsal bones for 28 days. The CESF apparatus was removed after eight weeks when there was radiographic consolidation of regenerate bone. At follow-up evaluations four and 12 months after surgery, the phalangeal hyperextension and plantar skin ulceration had resolved. No lameness was detected.

Use of the Ilizarov method of distraction osteogenesis for the treatment of radial hemimelia in a dog

A 6-month-old female crossbred dog with unilateral radial hemimelia was treated with a circular external fixator. During the first surgery, the dog underwent transverse osteotomy through the distal ulnar physis and rotation of the distal ulnar fragment (epiphysis) together with the forepaw in a lateral direction to achieve contact with the end of the proximal ulnar segment (shaft of the ulna); a circular external fixator was then applied. After removal of the fixator, a cast was applied. The initial intent was to preserve mobility of the ulnocarpal joint; however, the joint fused naturally. A second surgery was performed to lengthen the ulna by use of distraction osteogenesis. An Ilizarov external fixator was used, and the ulna was lengthened 25 mm. During the third surgery, osteotomy of the distal portion of the ulna was performed to treat residual deviation of the forepaw. The surgical treatment resulted in satisfactory use of the limb and a better quality of life.

Longitudinal Bone Transport for Treatment of Primary Bone Tumors in Dogs: Technique Description and Outcome in 9 Dogs

OBJECTIVE

To describe a surgical technique for bone transport osteogenesis (BTO) limb salvage and report outcome in 9 dogs with primary bone tumors.

ANIMALS

Nine dogs with spontaneously occurring primary bone tumors.

RESULTS

BTO surgery was performed as a primary means of limb salvage in 7 dogs and as a salvage procedure after catastrophic allograft infection and failure in 2 dogs. Mean defect size was 9.5 cm with a mean of 123 days distraction until docking. Mean time from surgery to fixator removal was 205 days. Minimum follow-up was 9 months. There were 2 histologically confirmed local recurrences where although limb function was excellent, eventually resulted in limb amputation. Limb function was good to excellent in all but 2 dogs; 1 was chronically non-weight bearing before BTO surgery because of complications associated with an allograft limb salvage that had been performed previously on the same limb. The cause of lameness in the other dog was undetermined.

CONCLUSIONS

BTO limb salvage can be successful in dogs with primary bone tumors. Whereas allograft limb salvage may be simpler from an initial management perspective, BTO has some unique advantages when compared with the allograft technique.

CLINICAL RELEVANCE

BTO has an emerging role in limb salvage surgery for dogs with primary bone tumors. BTO provides excellent long-term outcomes in some dogs with primary bone tumors and will likely become increasingly more attractive as technique modifications allow the duration of the treatment to be shortened.

Use of distraction osteogenesis for the correction of deviated nasal septum and premaxilla in a horse

A 13-month-old female Andalusian was evaluated because of a congenital left deviation of the maxilla and nasal septum, which had resulted in a gross malocclusion of the maxillary incisor teeth. Surgical correction of a deviated nasal septum and premaxilla in a horse was first reported in 1978 and involved a pre-maxilla osteotomy and use of an autogenous rib graft, with a nasal septum osteotomy performed in a second surgery; to the authors' knowledge, no alternative surgical treatments have since been described. In this horse, a new surgical treatment by distraction osteogenesis without nasal septum osteotomy was attempted. After the procedure, the premaxilla and nasal septum deviations were corrected; however, an overjet lesion (rostral projection of maxillary arcade over the mandibular arcade) was evident, for which the owners declined treatment. Compared with previously recommended procedures, distraction osteogenesis appears to be a less invasive treatment for congenital facial deformities and may be considered an option in the treatment of congenital deviation of the nasal septum and premaxilla (wry nose), head scoliosis, brachygnathism, and prognathism in horses.

The effects of osteoporosis on distraction osteogenesis: an experimental study in an ovariectomised rabbit model

The effects of oestrogen deficiency-associated osteoporosis on callus distraction were investigated in rabbits. Twenty-four female New Zealand rabbits 5 to 6 months old were used. Ovariectomy was performed on 12 rabbits, which composed the osteoporotic model group. Six weeks later, osteotomy was carried out and Ilizarov external fixators were applied to the right proximal tibial metaphyses in both the osteoporotic model group and the control group. Beginning one week postosteotomy, the metaphyses were distracted 0.35 mm twice daily for 3 weeks, and the average length increase obtained for both groups was 17.2 mm (minimum: 16.8, maximum: 19 mm). Following a postdistraction waiting period of 6 weeks for newbone formation, the subjects were sacrified and specimens were examined histopathologically. Radiography was carried out at one-week intervals during the distraction period and at 2-week intervals during the waiting period, and scintigraphy was performed at the end of each period. On histopathologic examination, a significant difference in callus remodeling was observed between the control and osteoporotic model groups. On radiologic evaluation it was observed that, while both groups had inadequate callus tissue at the end of the waiting period, callus formation and remodeling occurred later in the model group than in the control group, and the new bone was more osteoporotic. Osteoporosis associated with estrogen deficiency adversely affects the outcome of callus distraction. Nonetheless, radiographic findings in rabbits indicate that the effects may not be so great as to preclude clinical procedures. It was concluded that these results should be supported with clinical studies.

Distraction osteogenesis for treatment of premature physeal closure and shortening of the third and fourth metatarsals of a dog

A 4-month-old Siberian husky was presented for a history of lameness of the left hind limb. Physical and radiographic examination revealed a 1-cm shortening of metatarsals III and IV, with subsequent hyperextension of the digits on the left hind paw. A circular external skeletal fixator was used to accomplish distraction osteogenesis in both metatarsals over a period of 15 days. Treatment was successful in restoring appropriate length of the metatarsals and in resolution of the lameness. At 6 and 12 months after surgery, the owner reported that the dog was ambulating normally and had no complications related to the surgery.

Effect of cisplatin on bone transport osteogenesis in dogs

OBJECTIVE

To document effects of cisplatin on regenerate bone formation during the distraction and consolidation phases of bone transport osteogenesis.

ANIMALS

10 skeletally mature hounds.

PROCEDURES

Bone transport osteogenesis was performed to reconstruct a 3-cm defect in the radius of each dog. Five dogs were randomly selected to receive cisplatin (70 mg/m2, IV, q 21 d for 4 cycles), and 5 were administered saline (0.9% NaCl) solution. Bone mineral density was measured by use of dual-energy x-ray absorptiometry (DEXA) on days 24, 55, and 90 after surgery. Dogs were euthanatized 90 days after surgery. Histomorphometry was performed on nondecalcified sections of regenerate bone. Bone mineral density and histomorphometric indices of newly formed bone were compared between groups.

RESULTS

Densitometric differences in regenerate bone mineral density were not detected between groups at any time period. Cisplatin-treated dogs had decreased mineralized bone volume, decreased percentage of woven bone volume, decreased percentage of osteoblast-covered bone, increased porosity, and increased percentage of osteoblast-covered surfaces, compared with values for control dogs. Lamellar bone volume and osteoid volume did not differ significantly between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Regenerate bone will form and remodel during administration of cisplatin. Results of histomorphometric analysis suggest that bone formation and resorption may be uncoupled in cisplatin-treated regenerate bone as a result of increased osteoclast activity or delayed secondary bone formation during remodeling. These histomorphometric differences were modest in magnitude and did not result in clinically observable complications or decreased bone mineral density as measured by use of DEXA.

Distraction osteogenesis to treat premature distal radial growth plate closure in a dog

A 4-month-old Labrador was presented for forelimb lameness and elbow pain. Radiography revealed asymmetric premature closure of the distal radial physis resulting in humeroradial and humero-ulnar subluxation. A four-ring circular external fixator applied to the antebrachium was used to perform distraction osteogenesis. After a 4 day latency period, varying rates of linear distraction were used to lengthen the radius by 50% of its original length, which is significantly longer than has been previously reported. By 69 days after performing the radial osteotomy, the distraction callus had achieved clinical union and the fixator was removed. One year postoperatively, mild lameness was present after exercise and minimal elbow osteo-arthritis was evident radiographically. Complications observed included pin tract drainage, transient carpal contracture and radio-ulnar synostosis.

Distraction osteogenesis

Distraction osteogenesis and the use of circular external skeletal fixation has increased the capacity of veterinary surgeons to manage difficult orthopedic conditions including limb-length discrepancies, angular deformity, distal and severely comminuted fractures, and bone defects. This article discusses the historical developments of the Ilizarov method of distraction osteogenesis in veterinary surgery, circular external skeletal instrumentation, and the biological principles. There is also discussion of use of this method for correction of angular deformity and bone transport and complications associated with this technique.