Arthroscopically assisted arthrodesis of the distal interphalangeal joint with transarticular screws inserted through a dorsal hoof wall approach in a horse

Evita Busschers Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348-1692.

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Dean W. Richardson Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348-1692.

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Abstract

Case Description—A 16-year-old Thoroughbred gelding was examined because of chronic right forelimb lameness.

Clinical Findings—On radiographs of the right front foot, the distal interphalangeal (DIP) joint space was narrow, and osteophytes and periarticular bony proliferation indicative of severe osteoarthritis were seen. Arthrodesis of the right DIP joint was recommended to improve the horse's comfort on the limb.

Treatment and Outcome—The horse was anesthetized, and palmar and dorsal arthroscopic approaches were used to remove as much of the articular cartilage as was accessible. Holes were then drilled through the dorsal aspect of the hoof wall, and 3 transarticular, 5.5-mm cortical screws were placed in lag fashion through these holes across the distal phalanx and into the middle phalanx. Defects in the hoof wall were filled with gentamicin-impregnated polymethyl methacrylate plugs and sealed with cyanoacrylate. Eight months after surgery, fusion of the DIP joint was evident radiographically and the horse was sound at a walk.

Clinical Relevance—Transarticular placement of cortical screws through a dorsal hoof wall approach combined with arthroscopically guided cartilage removal can result in fusion of the DIP joint in horses.

Abstract

Case Description—A 16-year-old Thoroughbred gelding was examined because of chronic right forelimb lameness.

Clinical Findings—On radiographs of the right front foot, the distal interphalangeal (DIP) joint space was narrow, and osteophytes and periarticular bony proliferation indicative of severe osteoarthritis were seen. Arthrodesis of the right DIP joint was recommended to improve the horse's comfort on the limb.

Treatment and Outcome—The horse was anesthetized, and palmar and dorsal arthroscopic approaches were used to remove as much of the articular cartilage as was accessible. Holes were then drilled through the dorsal aspect of the hoof wall, and 3 transarticular, 5.5-mm cortical screws were placed in lag fashion through these holes across the distal phalanx and into the middle phalanx. Defects in the hoof wall were filled with gentamicin-impregnated polymethyl methacrylate plugs and sealed with cyanoacrylate. Eight months after surgery, fusion of the DIP joint was evident radiographically and the horse was sound at a walk.

Clinical Relevance—Transarticular placement of cortical screws through a dorsal hoof wall approach combined with arthroscopically guided cartilage removal can result in fusion of the DIP joint in horses.

A16-year-old 602-kg (1,324-lb) Thoroughbred gelding was brought to the George D. Widener hospital for evaluation of grade 3/5 right forelimb lameness. The horse had performed well as a show horse, but had received numerous intra-articular corticosteroid injections in both DIP joints during its career. The lameness was exacerbated when the horse was circled in either direction, but a more severe increase in lameness was noticed when the horse was trotted in a circle with the right forelimb on the inside of the circle. Prominent effusion of the right DIP joint was not evident. Intraarticular administration of 10 mL of 2% mepivacaine in the right DIP joint resulted in marked improvement in the severity of lameness. On radiographs of the right front foot, the width of the DIP joint space appeared severely decreased, and osteophyte formation and periarticular bony proliferation were evident.

Severity of the lameness worsened over the subsequent 7 weeks to the point that the horse became reluctant to put full weight on the limb (ie, grade 4/5 lameness) even while receiving a high dosage of phenylbutazone. During a re-examination, effusion of the DIP joint was now evident, and there was nearly complete loss of the joint space on radiographs (Figure 1). Because of the marked decrease in comfort and worsening of the radiographic appearance, arthrodesis of the right DIP joint was recommended, with the goal of achieving pasture soundness.

The horse was anesthestized and positioned in left lateral recumbency, and gentamicin sulfate (6.6 mg/kg [3 mg/lb], IV) and cefazolin (20 mg/kg [9.1 mg/lb], IV) were administered. The hair was clipped from the fet-lock region distally, and the right front digit, including the hoof, was prepared for aseptic surgery. The hoof was covered with an iodine-impregnated adhesive plastic drape,a and a pneumatic tourniquet was applied proximal to the metacarpophalangeal joint.

Figure 1
Figure 1

Lateral radiographic view of the right front foot of a horse examined because of right forelimb lameness. Notice the severely decreased width of the distal interphalangeal (DIP) joint space, osteophyte formation, and periarticular bony proliferation.

Citation: Journal of the American Veterinary Medical Association 228, 6; 10.2460/javma.228.6.909

A 20-gauge needle was inserted in the DIP joint 2 cm lateral to the midline and 3 cm proximal to the coronary band. The needle was directed distally and axially until the joint was entered. A balanced electrolyte solution was injected through the needle to distend the joint. A skin incision was made over the lateral aspect of the palmaroproximal pouch of the joint, proximal to the distal sesamoid bone, axial to the ungual cartilage, palmar to the neurovascular bundle, and abaxial to the deep digital flexor tendon and digital tendon sheath at the level of the proximal edge of the ungual cartilage, as described.1 A sharp trocar was used to introduce an arthroscope sleeve into the joint, and a conical obturator was used to advance the sleeve in the joint.

The obturator was removed, and an arthroscope was inserted in the joint. Minimal intact cartilage was seen on the palmaroproximal portion of the distal articular surface of the middle phalanx and the proximodorsal articular surface of the navicular bone. Instrument portals were created on the medial and lateral aspects of the palmaroproximal pouch by use of the same landmarks as described for the arthroscope portal, and a 5.5-mm full radius resectorb was used to remove synovium to improve visibility in the joint. A 5.5-mm spherical burrb was then used to expose fresh subchondral bone. Cartilage remaining on the dorsal articular surface of the navicular bone was partially debrided with an angled curette; for this procedure, the curette was used as a lever arm to create space between the distal aspect of the middle phalanx and the navicular bone.

The dorsal aspect of the DIP joint was examined arthroscopically through a portal created 2 cm lateral to the dorsal midline at the most proximal aspect of the distended joint capsule. An instrument portal was created medial to the dorsal midline and distal to the arthroscope portal, as described,c and the resector was again used to improve visibility of the joint surfaces. No cartilage was initially visible on the distal articular surface of the middle phalanx or the proximal articular surface of the distal phalanx. A 5.5-mm spherical burr was used to expose fresh subchondral bone on both articular surfaces.

The palmar aspect of the DIP joint could be partially visualized by manipulation of the arthroscope sleeve between the middle and distal phalanges (Figure 2). A narrow rim of intact cartilage was visible on the palmar aspect of the distal phalanx, but it was not possible to reach this location for complete debridement. Articular cartilage was removed from approximately 80% of the joint surface.

A 9.5-mm drill bit was used under fluoroscopic guidance to create holes through the dorsal aspect of the hoof wall. A total of 4 holes were created in the dorsal aspect of the hoof wall, but the first hole was found to be located too far proximal and was not used. The 3 more distal holes were located in the dorsomedial, dorsal middle, and dorsolateral aspects of the hoof wall. A 5.5-mm drill bit was inserted through each of these 3 holes and used to create glide holes in the distal phalanx. An effort was made to begin the glide holes approximately a third of the distance between the proximal and distal aspects of the distal phalanx and to aim toward the center of the distal articular surface of the middle phalanx. Glide holes were created in a dorsodistal-palmaroproximal direction under fluoroscopic guidance, and the dorsal aspect of the DIP joint was examined arthroscopically to observe the entrance of the drill bit into the joint. This assured the accuracy of the glide holes' depth and location.

Figure 2
Figure 2

Arthroscopic view of the right DIP joint in the horse in Figure 1; the arthroscope was inserted through a dorsal portal. Minimal cartilage is present at the most palmar aspect of the joint. MP = Middle phalanx. DP = Distal phalanx. AC = Articular cartilage.

Citation: Journal of the American Veterinary Medical Association 228, 6; 10.2460/javma.228.6.909

Figure 3
Figure 3

Photograph of the right front hoof of the horse in Figure 1 after placement of 3 screws in a dorsodistal-palmaro-proximal direction through the distal phalanx and into the middle phalanx for arthrodesis of the DIP joint. Defects in the hoof wall were filled with gentamicin-impregnated polymethyl methacrylate plugs sealed with cyanoacrylate. The most proximal defect was found to be located too far proximal and was not used for screw placement.

Citation: Journal of the American Veterinary Medical Association 228, 6; 10.2460/javma.228.6.909

Figure 4
Figure 4

Lateral radiographic view of the right front foot of the horse in Figure 1 obtained immediately after placement of 3 transarticular, 5.5-mm cortical screws in a dorsodistal-palmaro-proximal direction for arthrodesis of the DIP joint.

Citation: Journal of the American Veterinary Medical Association 228, 6; 10.2460/javma.228.6.909

Figure 5
Figure 5

Lateral (A) radiographic view of the right front foot of the horse in Figure 1 obtained 5 months after arthrodesis of the DIP joint and lateral (B) and dorsopalmar (C) radiographic views obtained 8 months after surgery. Five months after surgery, fusion of the dorsal aspect of the joint was evident, but the joint space on the palmar aspect of the joint was still visible radiographically. Eight months after surgery, there was radiographic evidence of fusion of both the dorsal and palmar aspects of the joint.

Citation: Journal of the American Veterinary Medical Association 228, 6; 10.2460/javma.228.6.909

Following creation of each glide hole, the 5.5-mm bit was removed, and a 3-mm K-wire was placed through a drill guide inserted in the glide hole. The drill guide was removed, and a 4.0/5.5 centering sleeve was placed over the K-wire. The K-wire was removed, and a 4.0-mm drill bit was used to create a hole through the middle phalanx. Threads were hand tapped in the holes in the middle phalanx, and a 5.5-mm cortical screwd was placed through each hole and firmly tightened.

An autogenous cancellous bone graft (approx 4 mL) obtained from the right tuber coxae was placed in the DIP joint through the dorsal and palmar arthroscopic portals with thumb forceps and rongeurs. The arthroscopic portals were closed with 2-0 polyglecaprone 25 in a simple interrupted pattern. The hoof wall defects were filled with polymethyl methacrylatee impregnated with gentamicin sulfate (1 g), and the edges were sealed with cyanoacrylatef (Figure 3).

Intravenous regional perfusion of the distal portion of the limb was performed with amikacin sulfate (2 g) diluted in 60 mL of sterile saline (0.9% NaCl) solution. Twenty minutes after the amikacin solution was administered, the tourniquet was released. A fiber-glass cast that enclosed the hoof and extended to the proximal aspect of the metacarpal region was applied. The horse was placed on a thick mat for recovery; no complications were encountered during anesthetic recovery. The overall surgery time was 2 hours; the pneumatic tourniquet was maintained for 2 hours and 25 minutes. Gentamicin (6.6 mg/kg, IV, q 24 h) and cefazolin (20 mg/kg, IV, q 6 h) were administered for 72 hours after surgery, and phenylbutazone (2.2 mg/kg [1 mg/lb], IV or PO, q 12 h) was administered during the remainder of the hospitalization period. Postoperative radiography revealed correct placement of the screws (Figure 4).

After surgery, the horse was bearing full weight on the right forelimb, with only mild lameness evident while in the stall. The horse was discharged from the hospital 5 days after surgery, and the owner was instructed to confine the horse to a stall and continue phenylbutazone administration. Fifteen days after surgery, the horse was re-examined and the cast was changed. Before the new cast was applied, fresh cyanoacrylate was applied to the edges of the polymethyl methacrylate plugs in the hoof wall. On radiographs obtained at this time, progression of proliferative bone formation on the dorsal aspect of the DIP joint was seen; proliferative changes on the palmar aspect of the joint were less prominent.

Twenty-one days after surgery, the horse was returned to the hospital because of owner concerns about the horse's comfort level. Although the severity of the horse's lameness seemed unchanged, the cast was changed so that the limb could be evaluated for complications. After 2 months, the cast was removed and a shoe with a 4-cm heel extension and a heavily padded bandage that included the extended-heel shoe were applied. At this time, a change in foot conformation was noticed, along with a steeper angle of the dorsal hoof wall and heels.

During the subsequent 3 months, the heel extension was shortened approximately 1 cm every month. Shoeing was discontinued 5 months after surgery. The horse had intermittent mild right forelimb lameness during this time, and phenylbutazone was administered as needed. On radiographs obtained 5 months after surgery, fusion of the dorsal aspect of the joint was evident (Figure 5), although a portion of the joint space on the palmar aspect of the joint was still visible radiographically. Eight months after surgery, there was radiographic evidence of fusion of both the dorsal and palmar aspects of the joint and the horse was sound at a walk and when turned out in a paddock. The plugs in the hoof wall remained intact and moved distally as expected with hoof wall growth.

Discussion

In horses with septic arthritis of the DIP joint, ankylosis has been described to sometimes result in minimal residual lameness.2,3 Ankylosis can be facilitated by surgical debridement of the cartilage, intra-articular application of autogenous cancellous bone graft, and application of a half-limb or transfixation cast.2-4 It appears that septic joints have a better chance of undergoing fusion following use of these techniques than do joints with severe osteoarthritis.

Various methods for arthrodesis of the DIP joint have been described.5,6 However, horses in which these methods were used all remained lame at a walk or sustained other complications, such as infection. Schneider et al6 described use of combined dorsal and palmar approaches, with a dorsal approach used to remove articular cartilage from the middle and distal phalanges and a palmar approach through the digital flexor tendon sheath used to place transarticular screws from the palmar aspect of the middle phalanx into the distal phalanx. Advantages of the dorsal hoof wall approach described in the present report were that, by contrast, there was minimal soft tissue damage and the transarticular screws were positioned such that there was a short glide hole in the distal phalanx and a long threaded hole in the middle phalanx, allowing for greater purchase of the screws. With the combined dorsal and palmar approaches, use of a transfixation cast after surgery was recommended to afford an adequate level of comfort.g This was not necessary in the horse described in the present report, and a simple half-limb cast was used.

Neither the method described in the present report nor the method described by Schneider et al6 provides complete access to the palmar aspect of the joint. Because it was not possible to completely debride cartilage on the palmar aspect of the DIP joint in the horse described in the present report, fusion of only the dorsal aspect of the joint was seen initially. However, the entire joint, including the palmar aspect, appeared fused on radiographs obtained 8 months after surgery. Previous reports2,6 have suggested that only partial fusion of the DIP joint can result in residual lameness. In the horse described in the present report, the radiographic appearance of complete fusion of the joint was associated with an increase in the comfort level of the horse, supporting the suggestion that movement between the distal aspect of the second phalanx and the navicular bone may result in some degree of lameness. Fusion of the palmar aspect of the DIP joint might be facilitated by incorporating the navicular bone in the arthrodesis. It is possible that an additional screw placed through the dorsal hoof wall and distal phalanx could engage the navicular bone.

Potential major complications associated with the method described in the present report, as with any internal fixation method, are implant failure and infection. In a previous report5 in which arthrodesis of the DIP joint was performed through a dorsal hoof wall approach, infection was a problem. However, this method involved creating a flap of the dorsal hoof wall and incising the coronary band. The infection that occurred several months after surgery was believed to have originated from deep cracks that extended from the incisions in the coronary band. With the method described in the present report, drill holes in the dorsal hoof wall used to provide access to the distal phalanx did not result in permanent damage of the hoof wall, reducing the long-term risk for infection. The combination of inserting gentamicin-impregnated polymethyl methacrylate plugs in the dorsal hoof wall defects and coating of the edges of the defects with cyanoacrylate was expected to provide a sufficient seal to prevent infection, and infection was not encountered in the horse described in the present report or in any of several other horses in which this technique was used for lag screw fixation of distal phalangeal fractures by the senior author.

A particular advantage of the technique described in the present report was that through a combination of arthroscopy and fluoroscopy, the surgeon could be confident that the glide hole was correctly positioned in the distal phalanx. Although the technique could have been done without the use of fluoroscopic imaging, fluoroscopy subjectively made the surgery much easier. Results for this horse suggest that this procedure should be considered for horses with irreversible damage of the DIP joint and can result in pasture soundness.

DIP

Distal interphalangeal

a.

Ioban 2, 3M Health Care, Saint Paul, Minn.

b.

CONMED, Linvatec, Utica, NY.

c.

Richardson DWR. Arthroscopy of the distal interphalangeal joint (abstr), in Proceedings. Annu Symp Am Coll Vet Surg 2004;78–79.

d.

Synthes, Paoli, Pa.

e.

Surgical Simplex P, Stryker Howmedia Osteonics, Mahwah, NJ.

f.

Nexaband liquid topical tissue adhesive, Closure Medical Corp, Raleigh, NC.

g.

Schneider RK. Arthrodesis of the distal interphalangeal joint of the horse (abstr), in Proceedings. Annu Symp Am Coll Vet Surg 2004;82–85.

  • 1

    Vacek JR, Welch RD, Honnas CM. Arthroscopic approach and intra-articular anatomy of the palmaroproximal or plantaroproximal aspect of distal interphalangeal joints. Vet Surg 1992; 21: 257260.

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  • 2

    Honnas CM, Schumacher J, Kuesis BS. Ankylosis of the distal interphalangeal joint in a horse after septic arthritis and septic navicular bursitis. J Am Vet Med Assoc 1992; 200: 964968.

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  • 3

    Honnas CM, Welch RD, Ford TS, et al. Septic arthritis of the distal interphalangeal joint in 12 horses. Vet Surg 1992; 21: 261268.

  • 4

    Lescun TB, Morisset SM, Fugaro MN, et al. Facilitated ankylosis of the distal interphalangeal joint in a foal. Aust Vet J 2004; 82: 282285.

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  • 5

    Honnas CM, Vacek JR, Schumacher J. Arthrodesis of the distal interphalangeal joint in a horse using stainless steel baskets and transarticular 4.5 mm cortical screws. Vet Comp Orthop Traumatol 1995; 8: 4651.

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  • 6

    Schneider RK, Bramlage LR, Hardy J. Arthrodesis of the distal interphalangeal joint in two horses using three parallel 5.5 mm cortical screws. Vet Surg 1993; 22: 122128.

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