Ch 54 radius and ulna Flashcards

Question

What can done to aid in stability of a proximal dynamic ulnar osteotomy/ostectomy? (2) | to prevent bending moment

Answer 1

Oblique cut (proximocaudal to craniodistal) IM pin (in immature) | revision sx: graft + plate

Answer 2

ostectomy of the distal part of the ulnar diaphysis or removal of the distal physis itself - interosseous ligament to help stabilize - unknown is the comparative efficacy of low versus high dynamic ulnar ostectomies in the skeletally immature dog in reestablishing humeroulnar congruence - in vitro: distal to the interosseous ligament did not allow adequate movement of the ulna in one study

Answer 3

- Ostectomy gap greater than 1.5x diameter of the bone (Key’s hypothesis) - Removal of all periosteum in the vicinity - Insertion of free fat graft into ostectomy

Answer 4

Physeal growth is slowed by excessive compression and is accelerated by distraction

Answer 5

(1) asymmetric premature closure of the proximal or distal physis of the radius or both (2) premature closure of the distal physis of the ulna with continued radial development (3) a combination of the two - decisions regarding timing and the type of correction to be completed - skeletally immature risk: correction before development ceases is that the angulation can return - delay surgery until mature risk: angulation will negatively affect biomechanical loads at joints, creating stress + OA - success rate of ulnar ostectomy as the sole treatment for premature ulna closure of juvenile dogs is relatively unknown - reestablishing normal antebrachial bone and joint alignment, or resolution of lameness, not prospectively studied - PUO utility as the sole corrective procedure limited to mild radial changes - >> radial corrective measures are often necessary - likely that distal radial physis also damaged, resulting in more complex deformity

Answer 6

Radial valgus greater than 25 degrees **If varus, recurvatum or internal torsion are present then radial corrective measures will be necessary**

Answer 7

presurgical planning called the center of rotation of angulation (CORA) method goal of this technique is to determine the apex of the deformity or deformities (also referred to as CORAs) using the radial anatomic or mechanical axis in conjunction with the joint orientation angles 1. normal contralateral antebrachium agles used or mean joint orientation angles (bilateral dz) 2. frontal plane joint orientation lines 3. frontal plane radial anatomic axes 4. Determine where the anatomic axes intersect within the cortical confines of the bone > CORA 5. repreat in sagital 6. If angulation in both orthogonal planes, then an oblique plane deformity is present radioulnar angular limb deformities frequently include torsion

Answer 8

- torsion in excess of 15 degrees results in radiographic miscalculation greater than 5 degrees in the frontal plane - surgical planning based on orthogonal radiographs alone appears unreliable when severe torsion is present - require additional diagnostics such as CT +/- stereolithographic modeling (perform a rehearsal surgery)

Answer 9

1. Radiographs of the elbow are prioritized. > “straight elbow” radiograph, which will allow determination of elbow joint orientation lines and the anatomic axis of the proximal portion of the radius. 2. Radiographs of the carpus are prioritized. > “straight carpus” view that can be assessed for the joint orientation line and the distal radial anatomic axis.

Answer 10

- premature closure of the distal physis of the ulna and possible associated premature closure of the lateral aspect of the distal radial physis - valgus, procurvatum, and torsion of the radius. - gross appearance of cranial bowing of the antebrachium, valgus deviation and external rotation of the distal limb - CORA may occur anywhere > most frequently localized on/proximal to, the distal physis - radial deformities in distal diaphysis or metaphysis can occur congenitally and may result in lateral deviation and luxation of the radial head - deformities occur secondary to malunion

Answer 11

- two CORAs within the cortical confines of the radius .1.Partially compensated - planes of the proximal and distal CORAs occur in opposite directions - result of the Hueter-Volkmann law - proximal CORA with varus deviation, partially compensated by a distal CORA with valgus deviation - many chondrodystrophic dogs naturally possess biapical, partially compensated .2. Noncompensated - planes of the two CORAs exist in the same direction, thus magnifying the overall deviation of the deformity in one direction

Answer 12

possess more than two CORAs

Answer 13

**integrity of the carpus** - should be assessed through palpation or stress radiography (laxity) - may result from severe radioulnar angulation due to substantial stretching of the joint capsule and collateral ligaments on the convex side of the deformation - often laxity subsides once the limb is straightened and biomechanical loads across the carpus are normalized - persistent laxity following surgery could negatively affect the long-term function and require additional surgery (imbrication, pancarpal arthrodesis) **uniapical** - single corrective osteotomy or ostectomy on the transverse bisecting line of the CORA. - closing wedge - cylindrical (incapable of achieving accurate correction of torsional deformities) - dome osteotomies (diminished accuracy in correcting sagittal plane, less bone apposition) - ESF with opening wedge osteotomy **Biapical** - may require correction of both CORAs, challenging + invasive due to small size of bone - ulna typically requires a releasing osteotomy at the level of each radial osteotomy (torsion may prevent fixation of ulna) - Gradual with bi-hinged circular ESF - bone plates and screw | care: avoid radial nerve, runs deep to supinator muscle

Answer 14

- internal fixation with bone plates - linear external skeletal fixators - circular external skeletal fixators - hybrid linear-circular external skeletal fixator constructs each offers advantages and disadvantages: PLATE - less intensive post-op - no postoperative modification possible ESF - accuracy of correction and the adaptability, - opening wedge osteotomy has the advantage of preserving some limb length - disadvantage that fixation must be applied in buttress fashion - hinged circular ESF used, the angulation correction axis is determined by the axis of the hinges of the fixation frame - complications: wire breakage, skin irritation, osteomyelitis, and radial re-fracture

Answer 15

Paley’s second rule

Answer 16

- if hinged ring fixator > opening osteotomy may be placed on the CORA - insufficient bone or using a bone plate, then Paley's second rule can be employed > osteotomy proximal to the CORA. - result in a translational deformity - use cylindrical or true dome osteotomy blade

Answer 17

poorly understood etiopathogenesis open or closed reduction Open > acute correction and thus require the release of soft tissues constraining the radial head, can result in an unstable joint - TA-ESF humeroradial distraction - closing or opening wedge osteotomy positioned on the defined CORA. - The radial head is moved by placing the olive wire, reduced over a period of 7 to 10 days - radial head is maintained > pin through the radial head into the ulna - concurrent dynamic ulnar osteotomy will help to prevent humeroulnar subluxation - young: articular cartilage of the radial head is able to remodel in response to the forces - mature: reduction of the head may result in more severe incongruity between the radial head and the capitulum of the humerus, may be limited to salage tx only (amp, arthrodesis, Cx, head ostectomy) - Regardless of technique, early postoperative physical therapy is advocated

Answer 18

- Conservative managment - Open surgical reducation and fixation (50% retained reduction of between 50-80%, 50% reluxated) - Radial head ostectomy (in young dog regrowth become exuberant, humeroulnar articulation in the adult dog) - Arthrodesis

Answer 19

ESF - monitoring of the pin–soft tissue interface (irritation or drainage) - pin failure or underlying osteomyelitis, which may require pin replacement or antimicrobial therapy, respectively. - frequent radiographic examination: presence of regenerative bone in the osteotomy gap, to allow appropriate modifications in distraction speed. internal fixation - rigid caudal splint or a bivalved cast - 4-6 weeks - destabilized over time as radiographs indicate increased healing.

Answer 20

- severity of elbow osteoarthritis and more severe functional impairments were significant prognostic indicators - dogs with biapical deformities are more likely to possess joint pathology affecting the elbow, carpus, or both joints at the time of presentation - chondrodystrophic dog more likely to be severely afffected - discussed with the owners before surgery because osteoarthritic changes may mitigate postoperative results

Answer 21

- Salter-Harris fracture of proximal or distal radial physes or the distal physis of the ulna proximal radius - challenging because of the small size of the epiphysis, the complexity of surrounding soft tissue, and the constraints of the elbow joint - ORIF, craniolateral approach - epiphysis is cross-pinned to the metaphysis with Kirschner wires distal physis of the radius - usually accompanied by a fracture of distal ulna - fluoroscopically guided closed reduction - Kirschner wires crossed, starting at the radial and ulnar styloid processes and directed proximally - caudal splint for 1 to 2 weeks to gain additional stability (protect against the force generated by the long lever arm) - removal of the implants in 4 to 6 weeks - possibility of **premature closing** of the radial or ulnar physes, may result in 3 issues: .1. radial shortening, .2. elbow joint incongruity .3. antebrachial angulation greenstick, or incomplete, fractures - nondisplaced nature, successfully achieved with external coaptation - immobilize both carpus and elbow

Answer 22

fracture of the proximal radius, concurrent fracture of the ulna or dislocation of the elbow joint occurs frequently. - lateral approach - Identification of the radial nerve as it passes beneath the supinator - identification of small articular fragments may require arthroscopic assistance. - comminuted radial head and neck (with no load sharing) > internal fixation + circular external skeletal fixator - radial head does not possess enough bone for implant > used proximal ulna. Radial head attached to the ulna through soft tissues (annular ligament, cranial crura of the collateral ligaments, and joint capsule)

Answer 23

T-plate CESF Proximal ulna stabilised to distal radius with ESF (type Ib or type II)

Answer 24

External Coaptation - Indications: isolated fracture of the radial or ulnar and stable fractures involving both radius and ulna. - young, medium-sized or larger dogs - unlikely to result in satisfactory healing of unstable fractures - regular reexamination at 1- to 2-week intervals + replacement (can increase $$$) - skin irritation, bandage sores, and ulcers - dealyed, malunion or nonunion internal fixation - open reduction (anatom. recon.) or via minimally invasive - indication: small- or toy-breed dog - plate on cranial surface - medial plate: ease of application and less interference with the tendons - polytrauma, large- or giant-breed, ulna can be simultaneously repaired - locking plates allow MIO: without complete disruption of the fracture hematoma or devascularization of bone fragments, plate is applied in distal-to-proximal fashion - postoperative rigid external coaptation is advocated > depends on age, fracture configuration, and degree of load sharing ESF - especially for comminuted and open # - advantage of being easily removable - positively threaded pins, more secure clamps, and stronger connecting rods, have obviated the need for more complex frame configurations + reduced complications associated with their use. - type Ia, Ib, and II frames - type Ib corridors minimize pin-associated morbidity + utilizes a larger bone surface area compared to type II - staged disassembly of this construct can be completed - circular: minimize interference with the motion of the elbow joint, “stretch” and “horseshoe” rings - prognosis for healing and good use of the limb was excellent, despite 100% of cases had some degree of drainage

Answer 25

divided into articular and nonarticular fractures. - T-plate if sufficient bone is available or Circular ESF for the juxta-articular fracture (opposing olive wires are based on the ring) - cephalic vein and the tendon of the abductor pollicis longus muscle may be sacrificed fracture of the radial styloid process - avulsion injury at the site where the medial collateral ligament is attached - Kirschner wires and a tension band or a screw in lag fashion - salvage > pancarpal arthrodesis.

Answer 26

Studies toy vs large breed: - toy-breed antebrachii are more susceptible to fracture when loaded because of morphologic differences in the bone - small-breed dogs possess decreased vascular density > can result in a delayed healing - small cross-sectional area cause trick apposition - tx should focus on: rigid stabilization and optimizing apposition while preserving the surrounding blood supply Tx - ESF with acrylic connecting bars (predrill/low speed to avoid necrosis) - ORIF interrupting the overlying soft tissues, but ensure rigid stabilization, excellent apposition, interfragmentary compression, and access to apply a bone graft - supportive soft-padded bandage or caudal splint for 3 to 4 weeks

Answer 27

Coaptation **83%** Bone plate - Successful **70 - 85%** - Complications **54%** (skin irritation, cold conduction, synostosis, angulation, osteopenia, plate failure, and screw loosening)

Answer 28

Staged screw removal once clinical union is evident - Start with screws closest to the fracture on each side - Waiting 3-4 weeks after removal prior to removing the next set (allows holes to fill in)

Answer 29

Nonarticular ulnar fractures proximal to the elbow joint are usually avulsion fractures of the olecranon - pull of the triceps brachii muscle group, tensile forces must be counteracted - caudal or lateral approach > lateral has less pressure when lying sternally; thus, incision dehiscence may be avoided - two Kirschner wires and a tension band along the caudal aspect - retrograde fashion reduces the risk inadvertently directed into the trochlear notch - fixation strength increases with increasing implant diameter, and wire diameter is more critical than pin diameter articular # - minimize changes associated with secondary osteoarthritis - bone plate and screws along the caudal or lateral cortex of the bone - caudal: biomechnically because tension surface, disadvantage soft tissue coverage is sparse, may become irritated - comminuted fractures of the proximal part of the ulna may require interfragmentary compression techniques - Nonreducible fractures > ESF, severe osteoarthritis and loss ROM are certain sequelae.

Answer 30

Type I: Cranial luxation of the radial head with cranioproximal angulation of ulnar fracture Type II: Caudal luxations of the radius and caudal angulation of ulnar fracture Type III: Lateral luxation of the radius Type IV: Fracture of the proximal part of the radius and the ulna diaphysis with cranial luxation of the radial head - annular ligament is still intact, closed reduction of the radial head + IM pin (and cast) - fractures of the ulna distal to the coronoid processes, the radioulnar joint is also luxated, thus necessarily disrupting the annular ligament - If the radioulnar joint is no longer intact, will have to stabilise once radial head is reduced (screw from caudal to cranial) + plate for ulna - radioulnar screws are subject to tremendous shear forces, To eliminate the effect on limiting radioulnar motion and prevent screw failure, screws may be removed 4 to 6 weeks following repair. | ulna is most frequently fractured just distal to the coronoid processes

Answer 31

Most fractures of the distal part of the ulna are associated with fracture of the radius; epair of the radius, stabilization of the ulna is not necessary. - large dogs, or in situations in which bilateral thoracic limb injuries are present, additional support may be required - bone plate to the lateral surface of the ulna - normograde IM pin ulnar styloid process - proximal attachment of the lateral collateral ligament of the antebrachiocarpal joint and thus provides stability to the joint, must be repaired - Kirschner wire and a figure of eight tension band

Answer 32

cats: 16.7%, dogs - 17.9% delayed union - 3.4% non-union

Answer 33

17% of all radial and ulnar fracture repairs combined with external coaptation were associated with soft tissue injuries which represented 69% of all confirmed complications (De Arburn Parent et al. 2017).

Answer 34

Ex vivo biomechanical study. simulated radioulnar synostosis in cats Induced radioulnar synostosis decreases antebrachial rotation by more than two-thirds, Implants fixating the radius to the ulna should be avoided in cats, regardless where they are located along the radial diaphysis. could lead to impairment of forelimb function and lameness if possible, reconstruction of the annular ligament would be preferable dogs prevalence of 11%, cats 12%, for radioulnar synostosis reported after radioulnar fractures

Answer 35

retrospectively, 6 referral clinics, Dual bone fixation was used in 13/49 (26.5%) cases, with only 1/13 (7.7%) having major complications. By comparison, 4/36 (11.1%) of single plated fractures had major complications. Single bone fixation was 14.25 times more likely to have a successful outcome compared with dual bone fixation no significant difference in the rate of minor and major complications between the SBF and DBF groups increase in stiffness with DBF clinical decision bias where DBF may be used in more complex fractures (36%) of the SBF cases had either an intact radius or ulna majority located in the distal diaphysis incidence of major complications in cases requiring revision surgery or even limb amputation was 10.2% cats having almost double the range of supination. Comminution of the fracture and concurrent orthopaedic issues did not significantly affect the outcome

Answer 36

Results indicated that use of CADS to assess the 3-D orientation of the proximal, diaphyseal, and distal segments of normal and abnormal canine radii yielded highly repeatable and reliable measurements

Answer 37

In the cat, there appears to be a less extensive interosseous component of the distal radioulnar ligament compared with the dog These anatomical differences may account for increased rotation of the feline antebrachium and have clinical implications, particularly with regard to the management of antebrachiocarpal joint injuries

Answer 38

medical records, Fifteen limbs that underwent initial fracture repair and five that underwent revision surgery met the inclusion criteria. using non-locking cuttable plates long plate working length resulted in minimal compression of the periosteal blood vessels close cancellous bone grafting applied in all cases Synostosis + Re-fracture after cranial plate removal was observed in one case each radial and ulnar radiographic union was achievedafter a mean of 6.1 ± 1.5 and 5.7 ± 1.7 weeks, > open reduction with OP to the fracture region did not adversely influence radial and ulnar fracture removed the cranial plate after radial or ulnar bone union became evident destabilisation by removal of the OP cranial plate may be beneficial, leading to increased loading of the bone which could accelerate healing (Claes et al. 2011)

Answer 39

226 cases. implant-induced osteoporosis assessed by ratio of pixel values (PVR) - significant decrease in PVR from 1-12m post-plate fixation - persistent in dogs ≥6m age, improved/corrected in dogs <6m age - PVR not affected by screw removal - destabilisation with plate removal → increased PVR after 3m - may be more affected by age at time of injury than fixation method - possibly related to plate contact (?) - screw removal had no effect on PVR osteoporosis > major cause of refractures after implant removal. Biphasic> 8 to12 weeks due to impaired periosteal blood flow caused by plate compression on the bone and at 24 to 36 weeks due to reduced mechanical stress on the bone. According toWolff’s law, reduction in bone mineral density can occur due to reduced mechanical stress (stress shielding)

Answer 40

olecranon fracture treated by tension band wire or plate osteosyntehsis - complications: overall 52%, 36.5% major, 29.2% minor - TBW 72% complications, plate 27% - implant failure only seen with TBW – proposed due to inappropriate selection - excellent long-term outcome regardless of technique

Answer 41

Prospective, randomized, controlled clinical trial 25 dogs Power Doppler ultrasonographic, computed tomographic (CT), and radiographic examinations Pressure-sensitive walkway gait analysis Radiographic healing occurred earlier in bones treated with OG (median, 9 weeks) than in those treated with BG (12 weeks). bones retained more vessels and greater signal intensity when treated with OG compared with treatment with BG in dogs perceived to be at risk for such complications OG did not result in major complications but led to limb swelling and erythema in 64% of dogs Conclusion: Omental grafting was not associated with major complications, and it accelerated bone healing and return to weight bearing in dogs. the effect of OG to improve healing and function postoperatively compared to no augmentation remains unknown.

Answer 42

stress changes in the radii beneath the locking plates (LP) 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 In contrast to the conventional plate technique, the LP technique is engineered for relative stability and secondary bone healing

Answer 43

Case report. Animals: An 8-month-old female spayed Border Collie In dogs with radial shortening and elbow incongruity, use of an ipsilateral proximal ulnar autograft with rigid internal fixation can be an effective treatment for radial lengthening to improve elbow congruity and resolve lameness.