•Introduction•Introduction•It should be the surgeon’s to re-establish joint integrity in such

manner, to allow optimal function after healing of an injury. Unfortunately, in many instances this is not attainable and

degenerative changes limit the horse’s use as an athlete or pleasure horse. In selected joint disorders, arthrodesis is an alternate

approach to gaining a useful horse despite sacrificing one joint (Auer, 1992).

•Arthrodesis is a type of ankylosis involving surgical fixation of a joint by procedures designed to promote fusion of the joint surfaces

through promotion of the proliferation of bone cells (Auer, 1992).•The development of osteoarthritis in high load-low motion joints

such as the equine proximal inter-phalangeal joint is felt to be the result of repeated trauma to the periarticular soft tissues. A currently recommended treatment for this disease is arthrodesis of such joint

• Surgical methods of arthrodesis as a treatment for osteoarthritis or traumatic

injury include curettage of articular cartilage of the joint or drilling of

subchondral bone incombination with AO/ASIF cortical lag screw fixation or T-

plate placement followed by cast immobilization

•Introduction•In most cases arthrodesis is carried out to

salvage valuable breeding stock. There are certain joints that can be fused without

undully compromising the animal performance (Auer, 1992). Such horses

can return to comfort and some to atheletic soundness after arthrodesis of

the proximal inter phalangeal joint

•Anatomy of proximal interphalangeal (pastern)joint-:•The pastern (proximal interphalangeal or suffergino-corneal) joint is

a saddle shaped joint. The distal articular surface of the first phalanx has a shallow sagittal groove separating into medial and lateral surfaces, both are slightly convex .The corresponding articular

surface on the second phalanx forms a low ridge and two concave surfaces (Nilsson, 1973; Adams, 1974 and Getty, 1975).

•Owen (1980); Horne and Lundvall (1981) and McIlwraith (1982) mentioned that, the articular cartilage of pastern joint is consists of

hyaline type, the matrix of which is a complex of collagenous fibrills and highly hydrated ground substance containing

mucopolysaccharides and glycoprotein. The collagen fibrils provide tensile strength to the articular cartilage .

•History of Arthrodesis-:

•Adams (1970) was the first to describe arthrodesis of the proximal inter tarsal,

distal intertarsal and tarsometatarsal joints as a treatment for spavin but the technique has remained contraversial among equine

orthopedic surgeons.

Osteoarthritis of the distal tarsal joints or bone spavin is the most frequent cause of lameness associated with the tarsus A curative treatment that reverses the degenerative changes and returns the horse to soundness currently does not exit. The trasometatarsal (TMT) and distal intertarsal (DIT) joints of some horses with sever osteoarthritis will fuse without treatment resulting in a return to soundness but spontaneous ankylosis is an inconsistent and lengthy

phenomenon

•Surgical techniques of arthrodesis involve removing varying amounts of articular cartilage using a drill bit

(Adams, 1970; Edwards, 1982; Ali, 1984; Wyn-Jones & May, 1986 and McIlwraith & Turner, 1987) and /or

internal fixation (Mackay and Liddell, 1972; Wynn- Jones & May 1986; Archer et al., 1989 and Abd El-

Aal, 1998) was conducted. Nevertheless, surgical arthrodesis is a major procedure that requires general

anaesthesia, is relatively expensive and has a convalescence period of up to 12 months (Sonnichsen

& Svastoga, 1985 and McIlwraith & Turner, 1987). More recently, chemical arthrodesis of the distal hock

joints in the horse using intra-articular sodium monoiodoacetate has been attempted .

SMIA is reported to produce a reliable, diffuse and sever insult to the articular cartilage after intra-articular injection. SMIA is a potent inhibitors of glycolysis- dependent chondrocytes and had been used extensivly to produce experimental model of osteoarthritis which will ultimately result in ankylosis (Williams and Brandt, 1982 and Yovich et al., 1987). A further possible mechanism by which SMIA may enhance arthrodesis is that results in reduced cartilage chondrone formation (Bohanon et al., 1991). Chondrones are thought to delay the ankylosing process by forming persistent cartilage bridges between the joint surfaces (Auer, 1999). Therefore reduced chondrone formation may lead to potentially more effective arthrodesis.

•Sodium monoiodoacetate (SMIA) is a chemical compound, when injected intra-

articularly, causes a rapid decrease in chondrocyte intracellular adenosine

triphosphate concentration resulting in inhibition of glycolysis, chondrocyte death, partially necrosis, joint collapse and fusion

•Martin et al., (1984) said that, arthrodesis are performed in low motion joints

especially pastern joint for a return to performance in situations where treatment

of the arthritis is not successful or in which, treatment has gradually become overpowered by the progression of the

degeneration.

•Moore and Withrow (1981) and Newton and Nunamaker (1984) stated that,

arthrodesis is an elective surgical procedure to eliminate motion in a joint by

providing a bony fusion to relieve pain, provide stability, over coming postural

deformity resulting from neurologic deficit and to control advancing disease.

•Schneider, Carinine and Guffy (1978); Trotter, McIlwraith, Norrdin and Turner (1982); Ellis and Greenwood (1985) and

Adams, Honnas and Ford (1995) mentioned that, arthrodesis of the proximal

interphalangeal joint (PIPJ) is used in treating degenerative joint disease (DJD),

luxations, subluxations and fracture of proximal and middle phalanges

•the proximal interphalangeal joint is a common site for DJD (high ring bone). It

can occur as a sequela to a severe sprain of the pastern or a deep wire cut in the

pastern region

•Raker (1962); Schneider et al., (1978); Auer, Fackelman and Gingerich (1980) and

McIlwraith (1982) defined osteoarthritis or degenerative joint disease as a disease of

diarthrodial joints comprising destruction of articular cartilage to varying degrees,

accompanied by subchondral bone sclerosis and marginal osteophyte formation. Synovitis and

joint effusion often are associated with the disease. They added that, the disease is

characterized by pain and dysfunction of the affected joints

•Trotter et al., (1982); Ellis et al.,(1985) and Pool (1996) reported that the

development of osteoarthritis in high-load low motion joints such as the equine PIPJ is felt to be the result of repeated trauma

to the periarticular soft tissues. A currently recommended treatment for this disease is

arthrodesis of such joint.

•Olds (1975); Moore et al., (1981) and Newton et al., (1984) mentioned that

septic arthritis, degenerative joint diseases and rheumatoid arthritis may result in joint

instability, pain or both often when medical or conservative surgical means prove unsuccessful, arthrodesis is the only

solution.

•Vansalis (1972); Adams (1974); Johnson (1974); Olds (1975); Schneider et al.,(1978);

Fessler and Amstutz (1988); and Auer (1991) mentioned that the non-surgical treatment for osteoarthritis especially the articuler type has

been unsuccessful but ankylosis relieves pain by preventing joint movement. McIlwraith and

Bramlage (1996) added that arthrodesis performed in acute joint disruptions noted with

fractures of the proximal and middle phalanges.

•Early et al., (1966); Olds (1975); Wind(1975); Dee, Dee and Early (1984) and Steenhaut,

Verschooten and DeMoor (1985) mentioned that, orthopedic indications for an arthrodesis

include chronic instability or subluxation not amenable to reconstructive procedure, painful arthritis not responsive to medical therapy and

certain fractures of the middle phalanx that don’t involve the distal inter-phalangeal joint.

•Arnolds (1985) reported that the most common indications for arthrodesis in veterinary medicine divided into traumatic, developmental and congenital. He added

that traumatic injuries to joint consists of both fractures and ligamentous disruptions with or without dislocation,

in which a primary repair lead to chronic instability or DJD and pain. Newton and Nunamaker (1985)

mentioned that, the major developmental diseases can be included under the heading arthritis that further

subdivided into idiopathic or secondary DJD, septic arthritis and immune mediated arthritis. The same

authors added congenital diseases as congenital elbow luxations and stifle deformities that are not amenable to

primary reconstruction.

•Olds et al., (1975); Johnson and Bellenger (1980) reported that arthodesis

indicated for the treatment of sever ligament sprains, sever joint trauma and

intra-articular fractures

•Proximal inter-phalangeal joint athrodesis has been indicated in osteochondritis dessicans (OCD) Trotter et

al., (1982) subchondral cystic lesions (Steenhaut et al.,1985) phalangeal deviations in foals (Schneider,

Guffy and Leipold 1987) and flexural deformities (White hair, Adams and Toombs 1992). Yovich,

Stashak and Sullins (1986); Bukowiecki and Bramlage (1989) and Caron, Fretz and Bailey (1990)

mentioned that lameness caused by DJD of pastern joint and comminuted middle phalangeal fracture has been treated successfully in horses by surgical arthrodesis.

•Adams (1974) and Fessler and Amastutz (1988) stated that most non

surgical treatment of osteoarthritis especially the articular type have been

unsuccessful but ankylosis relieves pain by preventing joint movement.

•Raker, Raker and Wheat (1966); Adams (1974); Whittick (1974); Olds (1975); DeAngelis (1975); Moore et al., (1981) and Newton

et al., (1984) said that prior to the development of prosthetic joints for human beings, arthrodesis was a common surgical procedure for

osteoarthritic joints in various parts of the body. The surgical principle that are necessary to achieve arthrodesis of joints include

the removal of all articular cartilage and sub-chondral bone until bleeding subchondral cancellous bone is reached. They added that the sub chondral cancellous surfaces are approximated and bound

by rigid internal implants. Autogenous cancellous bone graft is desirable in any defect between the two opposing bones which

serves as a scaffold for in growth of new vessels from each of the opposing bones.

•Adams (1970); Bramlage (1982) and Turner (1984) said that the articular cartilage of opposing bones should be removed for

achievement of an effective arthrodesis in the shortest time. If the bone ends are sclerotic as a result of a diseased process they must

be removed to achieve formation of new tissue in the defect and good ankylosis. While, Auer (1999) suggested that the cartilage was not removed from the proximal interphalangeal joint (PIPJ)

during the experimental procedure. It has been proposed that removal of cartilage will alter the radii of the opposing bones. He added that the distal end of the proximal phalanx will be reduced

and the proximal end of the middle phalanx will be decreased following curettage of articular cartilage. Although cartilage removal

is strongly recommended for arthrodesis to progress rapidly in the clinical cases.

•Whittick (1974); Olds (1975); DeAngelis (1975) and Auer (1992) observed that any defect not filled with

cancellous bone would first filled with fibrous connective tissue, then changed into osteoblastic tissue, thus

delaying complete ankylosis and external support is required until radiographic evidence of early fusion is

seen.Review of Literature•

Rick, Herthel and Boles (1986) reported that the use of an autogenous cancellous bone graft can substantially

reduced the time of osseous union following arthrodesis. However the presence of cancellous bone between the

proximal and the middle phalanges can adversely affect the degree of contact between the subchondral plates.

•Adams (1974) used a joint drilling procedure, removing as much of the articular cartilage then packing the joint with cancellous bone harvested from a different sites. Other techniques of arthrodesis

employ a more radical approach to the joint utilizing a variably shaped skin incision and a transection of the dorsal joint capsule of

the pastern joint and curettage of articular cartilage followed by support of the joint in a fiber glass cast (Turner and Gabel 1975; Turner 1984 and Stashak 1987). Alternatively, the method of lag

screw fixation either in criss-crossing or paralled procedure as described by Schneider et al., (1978) can be used. Surgical

techniques of arthrodesis involves removing varying amount of the articular cartilage using a drill bit (Adams 1970; Edwards 1982;

Wyn-Jones and May 1986, and McIlwraith & Turner 1987) and /or internal fixation (Mackay & Liddell 1972 and Archer,

Schneider, Lindsay and Wilson 1989).

•Surgical arthrodesis has an over all success rate of about 80% (Auer, 1992).

The current recommended surgical arthrodesis technique which involves

placement of three drill holes across each joint of distal tarsal joint, is associated with minimal post-operative complications and pain (McIlwraith and Turner 1987). The same authors preferred this technique in

the PIPJ

•Different methods of arthrodesis of the PIPJ have been described and include curettage of articular cartilage

(Adams 1974; Gabel and Bukowiecki 1983 and Boran, White and Allen 1987) insertion of lag screws

either by paralled or criss-crossing procedure (Schneider et al., 1978; Genetzky, Schneider, Butler

and Guffy 1981; Grant 1982; Gabel et al., 1983 and Yovich et al., 1986), application of a dynamic

compression plate (DCP) or specially designated T-plate (Fackelman and Nunamaker 1982; Bramlage 1985

and Boran et al., 1987), sliding grafting technique (Fackelman Nunamaker 1982) and combinations of the

above methods. All techniques are completed after removing articular cartilage and all involve the use of

post- operative cast.

•Baumberger and Lakatos (1977); Steenhaut et al., (1985) and Auer (1992) mentioned that

surgical methods of pastern arthrodesis as a treatment for osteoarthritis or traumatic injury include curettage of the articular cartilage or

drilling of the subchondral bone in combination with cortical screw fixation with lag effect or T-

plate placement followed by immobilization. They added that, immobilization with out

complete curettage of cartilage lead to ankylosis without osseus union

•Several methods of internal fixation have provided successful fusion of the PIPJ. after exposure of joint surfaces and curettage of the articular cartilage, two

screws in a cruciate orientation inserted with lag effect (Schneider et al.,1978 and Genetzky et al., 1981),

three screws placed with lag effect in parallel orientation (Colahan, Wheat and Meagher 1981; Martin et al.,

1984, Steenhaut et al.,1985; Caron, Fretz, Bailey and Barber 1990 and Schneider, Bramlage and Hardy

1993), a single T-plate (Steenhaut et al., 1985; Rick et al., 1986 and Auer,1992) and one or two dynamic

compression plate (DCPs) placed across the dorsal aspect of the joint (Auer, 1992; Crabill, Watkins and

Schneider 1995 and McIlwraith et al., 1996).

•Arthrodesis of the PIPJ was recommended as the best method of treatment of

comminuted fractures of the middle phalanx by application of a T-plate (Boran

et al., 1987), a narrow dynamic compression plate (Doran et al., 1987),

use of a broad dynamic compression plate (BukoWiecki and Bramlage 1989) or two

narrow dynamic compression plate

•Adams (1974) mentioned that fusion of the PIPJ in horse was done by drilling from the lateral

aspect of the joint and packing it with a cancellous bone graft while, Johnson (1974)

used the electrically stimulating fragmented ends after arthrodesis of the PIPJ. to decrease the

necessary for ankylosis and minimize extraarticular bony proliferation. The later author utilized electrical currents to create an electrical

effect to hasten bony union between the proximal and middle phalanges .

•Other technique aimed compression of the pastern joint with cortical screws were investigated by Vansalis (1972), Schnieder et al.,

(1978) and Mansmann et al., (1982) they stated that the technique of arthrodesis is begin by exposure of the PIPJ from its dorsal

aspect to ensure more thorough removal of the articular cartilage. The common (or long) digital extensor tendon was severed by an

inverted V-shape (Schneider et al., 1978) or by a Z-plasty (Mansmann et al., 1982), the joint capsule is transversely incised

by sharp dissection. The collateral ligaments were severed to allow exposure of the joint. Following arthrotomy a periosteal elevator is used to pry the joint surface apart for optimal exposure of hyaline

cartilage. A curette or drill is used to remove as much cartilage from the bone end as possible. AO/ASIF cortical lag screws were placed

in the joint to achieve greater stability and shorten the period of healing.

•One of the most description of pastern arthrodesis utilizing a dorsal approach to the joint. Curettage of articular cartilage and the

compression of the joint surfaces by cortical screws through the proximal into the middle phalanx using the lag principle (Schneider et al., 1978 and Genetzky et al., 1981). They found that placement

of three cortical screws crossing the pastern joint nearly parallel to the long axis of the phalanges creates a stronger union during the

first 120 post operative days than the diagonal insertion of two screws criss-crossing the joint. While, the latter author found that

the criss-cross procedure would be useful for arthordesis of the PIPJ after the transverse fracture of the second phalanx than the parallel procedure because the criss-cross screws penetrate the

second phalanx dorsal to the area of the fracture

•Maclellan (2001) concluded that an arthrodesis technique using two 5.5mm AO/ASIF cortical lag screws in parallel

procedure results in favorable outcome in fore and hind limb PIPJ. The technique

has another advantage of decreased surgical and coaptation time.

•Carnine and Guffy (1978) showed that method of lag screw fixation is preferred than the curettage of the joint

cartilage followed by support of the joint in a fiberglass cast as a techniques for arthrodesis of PIPJ. The

convalescent time and cost of hospitalization can be reduced because the cast can be removed earlier, since

the joint is inherently more stable owing to the lag screws. They added that the cast left on for an average

of 23 days, after that time, it was removed for radiographic evaluation of the joint, then a cast was

reapplied, if it was felt that the arthrodesis needed further support.

•Fackelmann and Nunamaker (1982) described other surgical procedure leading

to fusion of the PIPJ using plates and screws. The joint was fixed by T-plate

contoured to confirm to the anterior surface of the first and second phalanges.

The operated limb was placed in a cast from the carpus or tarsus to the hoof. The

horse was rested for a total of 12 weeks.

•Watt, Edward, Markel and Wilson (2001) compared the biomechanical characteristics and mode of failure of two different

screws techniques (3 parallel 4.5mm cortical screws and 2 parallel 5.5mm cortical screws in lag fashion) in equine PIPJ arthrodesis.

They observed that 3 parallel 4.5mm cortical screws placed in lag fashion have been an accepted standard for PIPJ arthrodesis in the

horse.Two 5.5 mm screws have been shown here to be biomechanically similar to three 4.5mm screws. They believed that,

it is surgically simpler to implant two 5.5mm screws than three 4.5mm screws. The same authors in (2002) compare the

biomechanical characteristics and mode of failure of two different dynamic compression plates (two 7 holes 3.5mm broad DCPs and

two 5 holes4.5mm narrow DCPs) techniques for PIPJ arthrodesis in horses. They advised that the latter technique is more preferable

than the former one

•Sodium monoiodoacetate ( MIA ) is a chemical compound which, when injected intra-articularly causes

a rapid decrease in chondrocyte and intracellular adenosine triphosphate concentrations resulting in

inhibition of glycolysis and chondrocyte death (Sorimarchi & Nishimura, 1983; Berding &

Mikhailov, 1983; Saito & Yamaguchi, 1985 and Tread Well & Mankin, 1986). MIA has been used

experimentally as a glycolysis blocking agent to create arthritis in rats (Kalbhen 1981), guinea pigs (Williams &

Brandt, 1982), chicken (Stick, Slocumbe and Personnett 1984) and horses (Buchmann & Kalbhen

1985 and Yovich, Trotter, McIlwraith and Norrdin 1987) .

•Review of Literature•Bohanon, Schneider and Weisbrade (1991)

and Bohanon (1995) reported a process of arthrodesis of distal tarsal joints by intra-articular

injection of MIA which compared favorably with surgical one this technique has been suggested

as a simple, cheap and easier than the latter one.

•Penraat, Allen, Fretz and Bailey (2000) reported that chemical arthrodesis can not be

advocated in clinical cases because of high complication rate and lack of bony fusion.

•Experimental arthrodesis in horses using MIA has been investigated by Bohanon et al., (1991) who found that a

series of three injections of 120 mg of MIA into the pastern joint with 10 days intervals would produce an

average 80.5% joint fusion in 3 month with unfused areas of the joint showing potential for fusion. The same

author in addition to Bohanon (1995) found that the second and third injections of MIA revealed difficulties

not encountered on the first injection. Although the needle was inserted to its maximum depth, high

pressure was required to inject into the intra-articular space. A soft tissue swelling from pervious injections

increased the distance from the skin to the intra-articular space.

•Recently, chemical arthrodesis of the PIPJ through intra-articular injection of 120mg of MIA has been introduced as a treatment for DJD. Pronounced

synovitis after injection by 12 to 24 hours which is managed with sedation and analgesia with detomidine and phenylbutazone before injections

(Schneider, 1997).•Penraat et al., (2000) studied the use of MIA for arthodesis of the PIPJ and

the effect of exercise on the degree of fusion in eight horses. Animals received three injections with 10 days intervals of MIA (6% ,60 mg /ml) at a

dose of 120 mg into the right or left fore PIPJ, perioperatively, the horse received phenylbutazone and low volar never blocks to relive pain. Horses were randomly divided into non-exercised and exercised groups. Exercise

consisted of 20 minutes of trotting 3 days per week for 13 weeks. The horses were killed at 24 weeks, slab sections of the joint were evaluated

grossly and radiographically for bony fusion. They found that three horses were excluded from the study after developing soft tissue necrosis around

the injection site, septic arthritis and necrotic tendonitis. The remaining horses developed a grade 1 to 4 lameness with minimum to sever swelling

in the pastern region. All 5 horses showed radiographic evidence of bony fusion.

•Review of Literature

•Williams & Brant (1984); Yovich et al., (1987); Bohanon et al., (1991) and Bohanon (1995) mentioned that MIA blocks a specific enzyme pathway in chondrocyte metabolism, resulting in

chondrocyte death, cartilage necrosis, joint collapse and fusion of it.

Prognosis & complications of pastern joint arthrodesis-:

••Martin et al., (1984) and Caron et al., (1990)

reported that the success of arthrodesis of the proximal interphalangeal joint was 46% in fore limbs and 83% in hind limbs using a technique involving a three screws in converging pattern.

While Schneider et al., (1993) reported that the success of arthrodesis was 67% in the fore limbs

and 86% in hind limbs. Rick et al., & Yovich et al., (1986) described a successful cases of

bilateral arthrodesis in the fore and hind limbs.

•Schneider et al., (1978) and Genetzky et al., (1981) compared transarticular screws

techniques using three paralled 4.5mm screws or two cruciate 4.5mm screws, result of comparison revealed that, the paralled

procedure created a functional soundness and a superior union between the first and second

phalanges during the first 120 days post-operatively. It was easier than the diagonal

insertion of the two screw crossing the joint, produced better alignment and was less prone to

error in screws placement.

•Review of Literature•Doran et al., (1987); Bukowieki et al., (1989); Caron et al., (1990)

and Crabill (1995) mentioned that the prognosis for horses having arthrodesis to intra-articular fractures or active sepsis has not been

reported in large numbers of cases, however, the prognosis for treatment of fractures that involve only the PIPJ has been assumed

to be similar to that for DJD .••Genetzky et al., (1981) and Martin et al., (1984) mentioned that

the complications following PIPJ arthrodesis in horses include radiographic evidence of navicular disease, degenerative disease

involving the distal inter phalangeal joint and toe-elevation at the beginning of the weight bearing. Other complications related to open

reduction and internal fixation include infection, and implant associated lameness .

•Nixon et al., (1984) reported that implant associated lameness is likely to occur if a screw penetrates distally

on the palmar or plantar cortex of the middle phalanx and encroaches on the navicular bone articulation,

furthermore, even a properly positioned screw that is too long can cause persistent irritation to the soft tissue

structures and result in lameness. Toe-elevation occur due to damage to the deep flexor tendon. The same

authors in addition to Bramlage (1992) reported other complications of PIPJ arthrodesis as low true ring bone,

screw breakage, excessive formation of callus and fracture of the small shelf created on the distal end of the

proximal phalanx. All which produced continued lameness.

•Review of Literature•Bramlage (1992) said that, the most significant

complications associated with arthrodesis was laminitis in the opposing limb which is influenced by the lack of comfortable weight bearing in the

injured limb. Martin et al., (1984) added that lameness associated with excessive periarticular

exostosis and increased period in cast were other complications of pastern joint arthrodesis

in horses.