Racing performance of Thoroughbred horses after arthroscopic surgery of the carpus NJ KANNEGIETER* and N RYAN'

SUMMARY: The case record, and subsequent racing performance, of 11 0 horses that had undergone arthroscopic surgery of the carpus, were reviewed. Of these, 87% resumed racing, with 43% able to win at least one race, after surgery. Horses with chip fractures from the distal radius had the best prognosis, while horses with sagittal fractures of the third carpal bone had the poorest. The performance of horses with bilateral lesions was similar to those with unilateral lesions. It was concluded that arthroscopic surgery was a suitable technique for the diagnosis and treatment of carpal lesions in the horse. Aust Vet J 68: 258 - 260

Introduction Recently, arthroscopic surgery has been used routinely to treat

lesionsin theequinecarpus (McIlwraith 1984, Hurtigetall985). Valdez (1982) and McIlwraith el af (1987) showed that 90% and 95%, respectively, of horses were able to resume racing.

This article evaluates the racing performance of Australasian Thoroughbred horses after arthroscopic surgery of the carpus. Other factors examined were the length of rest between surgery and resumption of training, and the severity and location of the lesion in relation to subsequent performance.

Materials and Methods The records of 110 horses that had arthroscopic surgery of one

or more carpal joints, over 3 yr, using a standard technique (McIlwraith ef a1 1987), by the same surgeon (NJK) at Massey University, New Zealand, and the University of Sydney, Australia, were reviewed. The location and seventy of all lesions seen during arthroscopy had been documented. Where more than one lesion was present, the horse was categorised according to the location of the most severe lesion. Articular cartilage damage was graded from 1 to 3. Grade 1 was a joint in which cartilage damage was confined to an area immediately adjacent to a chip fracture (within 2 to 3 mm) and no, or minimal, cartilage damage on the opposing articular surface was present. Grade 2 joints were those that had cartilage damage extending up to 3 to 8 mm from the fracture site, and obvious cartilage damage on the opposing articular surface (kissing lesion) was usually present. Grade 3 joints had articular cartilage damage greater than 8 mrn from the fracture line, and a severe kissing lesion was present.

Post-operatively all horses were confined to a stall for 4 to 6 wk. Pressure bandaging was applied for 10 to 14 d, with sutures being removed on the first bandage change, usually 4 to 8 d after surgery. Phenylbutazone (4.4 m a g ) was administered for 48 h in those horses that had severe !esions and that had required greater surgical manipulation during treatment. Procaine penicil- lin (15 m a g twice daily for 5 d) was administered only to those horses that had internal fixation. No other intra-articular medic- ation was used either during or immediately after surgery.

The length of rest recommended before resuming training varied from 6 wk to 12 mo, depending on the seventy of the lesion, the age and sex of horse, and anticipated racing program

Follow-up information was obtained by telephone from the owner or trainer. The minimum time from surgery to obtaining follow-up information was 6 mo. Information obtained included

the length of time between surgery and resuming training, the presence of lameness, in any limb, since surgery, whether any systemic or intra-articular medication had been used since surgery, and the subsequent racing performance of the horse, or reasons why the horse had not resumed racing. For comparison with other studies, the results were assesed in

terms of the proportion of horses able to resume racing, and those able to win races.

Results Racing Performance

The results of arthroscopic surgery are presented in Table 1. Horses that were unable to resume training for reasons other than lameness were excluded from the calculation of fiial percent- ages.

The distal radial carpal bone was the location of over 40% of all fractures. Of these horses, 90% resumed racing, and of these 40% were able to win subsequently. Kissing lesions on the opposing surfaceof the thirdcarpal bone were observed frequent- ly. Of the 4 horses that had not raced again because of lameness, two suffered from strained flexor tendons, one became lame in the other limb, and the other became lame in the same limb. Of the winners, one horse subsequently showed exercise induced pulmonary haemorrhage, while 2 became lame again in the same limb.

All 1 1 horses with chip fractures of the proximal aspect of the third carpal bone had resumed training. Of these, 3 were unable to race again because of recurrence of lameness in the limb that had been operated on. Eight horses raced again, although only 2 were able to win races. One of these 2 suffered a slab fracture of the third carpal bone, necessitating retirement from racing. All 5 horses that had internal fixation of slab fractures of the third carpal bone using arthroscopic visualisation were able to race again, with 3 winning, although one of these winners was still occasionally lame. Two horses withsagittal fractures were retired without returning to training, one because of severe degenerative joint disease, and one because of further chip fractures in the affected joints. Of the remaining 4 which raced, 2 won races, although one of these was occasionally lame in the limb that had been operated on. The overall success rate of horses with chip fractures and sagittal fractures of the third carpal bone was poor compared with other types of fractures. In contrast to this, the results after slab fracture repair were good, although only a small number of horses were treated.

Horses with chip fractures of the lateral aspect of the distal radius had the best subsequent performance of all the groups. All 9 horses in this group raced again, although one subsequently

* Department of Veterinary Clinical Sciences, University of Sydney, New South Wales. 2006 Department 'of Veterinary Clinical Sciences, Massey University, Palmerston North, New Zealand

strained a tendon. Of the 5 that wonraces, one later went iame in the other limb.

258 Australion Veterinary Journal. Vol68, No 8 , August 1991

TABLE 1 Relationship between site of lesion at arthroscopy and subsequent racing performance

Site of lesion'

Radial Third Slab C3 Sagit C3 Distal Bilat D iag Total carpal carpal radius Observation

Number of horses

Number spelling or in pre-training

Number not racing, reasons other than lameness

Total suitable for follow up

Did not race, because of lameness

Raced -number - Yo

Raced and won - number - %

48

3

1 1 0

6

1

7 1

9

0

22

2

8 0

1 1 1

7

3 0 0 0 0 1 0 4

42

4

1 1

3

5

0

6

2

9

0

19

1

8

3

100

13

38 90

8 73

5 100

4 67

9 100

18 95

5 63

87 87

2 33

5 56

1 1 58

3 38

43 43

17 40

2 18

3 60

~~ ~ ~

Radial carpal - Distal articular surface radial carpal bone Third carpal - Proximal articular surface third carpal bone Slab C3- Slab fractures of the third carpal bone Sagit C3 - Sagittal fractures of the third carpal bone

Distal radius - Lateral aspect distal radius Bilat - Bilateral chip fractures Diag - Diagnostic arthroscopy

Horses with bilateral lesions accounted for nearly 20% of cases. In all instances the lesions were located in similar positions in the left and right limbs. Two horses had distal radius chip fractures, and one had fractures of the proximal third carpal bone. All three of these horses were able to win following surgery.

The remaining 19 horses had fractures of the distal radial carpal bones. One of these was retired for breeding immediately after surgery, and one was unable to race because of further lameness. Of the remainder, 8 subsequently won races. One of these went lame again after winning.

There were 8 horses which underwent diagnostic arthroscopy. In 4 of these, radiographic evidence of degenerative joint disease was present, but no chip fractures, 3 were found to have intra- carpal ligament damage, and one was diagnosed as having acute synovitis. Three of the horses did not race again, 2 of these had ligament damage, while the third, a horse with degenerative joint disease, went lame again. Of the horses to race again, one strained a tendon in the opposing foreleg after two starts and was retired. This horse had been diagnosed as having ligament damage. Three horses in this group, including the horse with synovitis, were able to win races. One of the horses with degenerative joint disease was given intra-articular polysulphated glycosaminoglycans on two occasions.

Overallperformance - A total of 100 horses were evaluated for their racing performance after arthroscopic surgery. Of these 87% were able to race again with 43% able to win races after surgery. Lameness of varying types prevented 13% of horses racing again. Of the horses that resumedracing, 11 % had suffered further periods of lameness between the time of resuming and when follow-up information was obtained. This prevented some horses from continuing torace. A small proportion of horses (3%) were able to win races despite not being totally free of lameness.

Relationship Between Severity of Lesion and Racing Performance As there were only a small number of horses in some groups,

the figures were combined to enable a comparison of perfor- mance inrelation to the severity of lesion, irrespective of location of the fracture. The results are presented in Table 2. There was little difference in the overall performance of horses in each group.

Post-operative Rest Horses with fractures of the distal radius generally resumed

training earlier than horses with other types of fractures (Table 3). Sagittal fractures had the longest average convalescent time. The earliest a horse resumed training after surgery was 4 wk, and this was the horse with synovitis.

TABLE 2 Relationship between severity of lesion and racing performance

Severity of lesion'

Grade 1 and 2 Grade 2-3 and 3

Raced (number of 43 (84%) 1 7 (77%) horses and %)

Raced and won 22 (43%) 9 (41%) Did not racet 8 (16%) 5 (23%)

Discussion The racing performance of horses in this study is comparable

with other reports of treating carpal lesions by arthroscopic surgery. McIlwraith et a1 (1987) found that 95% of 445 horses, the majority of which were Quarter horses, were able to return to their intended athletic performance, with 68% competing at an equal or better level than before surgery. In an earlier study, Valdez (1982) reported that90%of 9 1 casesresumedracing, with 80% competing at the same level or higher. The present study included all lesions of the carpus that were examined arthroscopi- cally, which may have influenced the overall success rate.

The results after arthroscopy compare well with those after arthrotomy and conservative treatment. The success rate after arthrotomy varies from 68% (Gabel 1983) to 90% (Speirs er al

Total 51 22

Grading methods described in text includes horses that did not race for reasons other than lameness

Awlration VeterinaryJournaI, Vol68, No 8, August 1991 259

TABLE 3 Average rest period after arthroscopic surgery of the carpus

Site of lesion' Radial Third Slab C3 Sagit C3 Distal Bilat Diag All

Observation carpal carpal radius lesions

Average rest (mo) 5.7 6.7 7.5 9 4.9 6.5 4.6 6.4

Range (mo) 3-12 3-15 6-9 6-1 2 3-7 3-1 2 1-8 1-15

See footnote to Table 1

1986) of horses returning to racing. Results after conservative treatment range from 46% (Wybum and Goulden 1974) to 86% (Pendergast 1979) of horses racing again after the diagnosis of carpal chip fractures.

The effect of location of lesion on subsequent racing perfor- mance has been previously described (Lindsay and Homey 1981; Gabel 1983; Speirs et a1 1986; McIlwraith et a1 1987). Most authors agree that lesions in the radiocarpal joint have a better prognosis than those in the intercarpal joint. In addition, chip fractures of the distal articular surface of the radial carpal bone have been reported as having a better prognosis than those from the third carpal bone (McIlwraith el d 1987). The present series of cases agrees with this finding. In contrast, Spiers et af (1986) found that location of lesion had no effect on subsequent perfor- mance.

The results of treatment of slab fractures of the third carpal bone vary among reports. Lindsay and Homey (198 1) considered that after lag screw fixation via arthrotomy, the prognosis was poor. After using arthroscopic visualisation to assist placement of the screw, Richardson (1986) reported that 10 of 17 horses were able to race successfully. All horses in the present series were able to return to racing, which was considered an excellent result in view of the severity of the initial lesion.

The prognosis of sagittal fractures was found to be poor in this series. One of the main reasons for this is that there is often a considerable delay between fracture Occurrence and diagnosis, as has been previously described (Kannegieter and Burbidge 1988), resulting in severe lysis of bone and articular cartilage damage.

Of the horses in which diagnostic arthroscopy was performed, those with damage to the intra-carpal ligaments were considered to have the worst prognosis. This condition has been found only in a small number of cases to date, but may occur more frequently than is presently documented (Kannegieter 1990).

After racing succesfully, a small number of horses went lame again in the limb that had been operated on, while a smaller percentage were able to continue to win races despite being lame. A similar finding was reported by McIlwraith et ul(1987), where approximately 20% of the horses remained lame in the affected joint or suffered further chip fractures. This present report, and that of McIlwraith and co-workers both indicate that although many horses are able to return to racing and compete successful- ly, the incidence of subsequent lameness is high. The most likely reason is that chip fractures represent one complication of degenerative joint disease, that continues despite removal of the fracture. Chronic changes in the penarticular structures of the joint also may contribute to further problems.

There appeared to be no consistent relationship between the seventy of the lesion observed and the subsequent racing perfor- mance of individual horses. This suggests that factors other than the severity of articular cartilage damage present at the time of surgery influence the final outcome. This may include the con- formation and age of the horse, the extent of lysis of bone, the length of rest given, and the continuing presence of degradative enzyme products in the joint. This finding is in agreement with Speirs et ul(1986), but in contrast with the finding of McIlwraith

et d(1987), who found that horses with more severe lesions were less successful. However, in this latter report, there was no difference between horses with mild to moderate lesions, while horses having the most severe lesions had inferior performance. The differences between reports may reflect differences in grad- ing of lesions, and the numbers of horses in each group.

Horses with distal radial chip fractures, in addition to being the most successful, were also retumed to work earlier than horses with other lesions. The main reasons for this were the excellent appearance of the joints shortly after surgery, and the minimal degenerative articular cartilage damage adjacent to the chip and on the opposing surface. Horses with sagittal fractures required the longest rest period, primarily because of the severity of the fracture, but also because extensive degenerative joint disease often was present.

Although there is no definitive evidence that arthroscopic surgery results in superior long-term athletic performance com- pared to arthrotomy, the technique has advantages which should be of benefit to the horse. These include better visualisation and treatment of all lesions in the joint, less trauma during surgery and few post-operative complications.

References EvansCH.MazzochiRA,NelsmDDandRubashHE (1984)ArthririsRhem

Gabel AA (1983) Proc Srh Bain-Fallon Lectures Aust Equine Vet Assoc, p134 Hunig MB. Fretz PB, Doige CE and Naylor J (1985) Vet Surg 1463 Kannegieter NJ (1990) Proc 12th Bain-FaNon Lectwes Aust Equine Vet

Kannegieter NJ and Burbidge HM (1988)Aui Vet J 65402 Lindsay WA and Homey FD (1981) JAm Vet Med Assoc 179:682 Mcnwraith CW (1984) Equine Vet J 16 11 Mcnwraith CW, Yovich JV and Martin GS (1987) J Am Vet Med Assoc

NonieRD (1975)Proc21 AnnConvAmAssocEquinePracf p 191 Pendergast K (1979) A u t Vet Pract 9 179 Richardson DW (1986)JAm Vet Med Assoc 188288 Speirs VC. Anderson GA and Bourke JM (1986) Equine Ver J 18: 187 Valdez H (1982) Proc 28 Ann Conv Am Assoc Equine Pracf p 149 Wybum RS and Goulden BE (1974)NZ Ver J22:133

27200

Assoc, p175

191531

(Accepted for publication 29 April 1991)

African horse sickness and the Barcelona Olympics

Fifty six outbreaks of African horse sickness were reported in Spain during 1990, the last one on 29 October 1990. All occurred in the Malaga province in Andalucia (Vet Rec 128220,9 March 1991). The British Equine Veterinary Association has endorsed the

demand of the British Equestrian Federation that the equesman events of the 1992 Olympics should be taken away from Bar- celona because of the threat resulting from the outbreaks of African horse sickness in Spain.

260 AutralionVeteriMryJourMI, Vol68, No 8, August 1991