Severe cervical spinal cord injuries related to rugby union and league football in New South Wales, 1984-1996

Abstract

Introduction

We report the findings of a survey of rugby union- and league-related cervical spinal cord injuries in New South Wales (NSW) for the period 1984 to 1996.

Methods

Additional information about the circumstances of the injuries, including eyewitness reports of the events leading to them, was obtained from the NSW Sporting Injuries Committee -- a statutory authority which administers an insurance scheme for people permanently injured while playing sports. We also estimated the number of participants in rugby union and league football in NSW per year in the review period, based on the Committee's data⁵ plus surveys of NSW schoolboy football participants.⁶ As some of these data were incomplete and there was some duplication, these estimates are broad approximations only.

Statistical analysis

The number of cervical spinal cord injury cases is small, so any statistical analysis necessarily lacks power. To develop valid conclusions from this study, we analysed cases of cervical spinal cord injuries according to:

• total number of admissions to the two spinal units;
• permanent neurological deficits (ie, complete tetraplegia); and
• trends during the review period.

When there are large numbers of participants and the risk of cervical spinal cord injury to any particular player is very low over a short time period -- and the injury is permanent and will not allow a return to the game -- the number of injuries in each year is assumed to follow a Poisson distribution.

In the absence of data on hours of playing football or training for football, we assumed that the total number of hours devoted to the game for each code and grade did not vary from year to year.

The null hypothesis for each test we performed was that there was no change in aggregated risk of cervical spinal injury against the alternative that the risk had decreased. All tests were based on the null-hypothesis assumption that the best estimate of annual rate of injuries was the average rate of injuries. We then fitted a simple linear regression, of time, to a probability transformation of the injury data. The number of injuries for each year was converted to the probability of observing, at most, that number of injuries in a particular year. These values were then converted to their corresponding standard normal score. The tests were based only on the regression slopes, which were tested to see if they were negative. The critical level of significance for these tests was 0.1.

All calculations were performed using Microsoft Excel. The function POISSON was used to calculate the cumulative probabilities; the function NORMINV was used to calculate the standard normal scores; the function LINEST was used to calculate the slope and its standard error; and the function TDIST (one-tailed 11 degrees of freedom) was used to obtain the significance of the results. The Random Number Generator was used in a small simulation study to confirm the size of the testing procedure.  

Results

The age range of the injured players from both codes was 15-37 years (median, 22 years); all were male.

The number of patients admitted per year to the spinal units because of cervical spinal cord injuries varied widely: from one to nine per year for league and one to eight per year for union. The number of players who had permanent tetraplegia varied from none to five per year for league and none to six for union (Table 1).

Incidence and trends

There were about 106 000 participants in rugby league and about 31 000 in rugby union in NSW during each year of the review.^5,6 Trends in rates of admissions and incidence of permanent neurological deficits per 10 000 participants are shown in Table 2.

Using the data shown in Table 1, there was no decline in the number (and hence the rate) of admissions for union (P = 0.21) or league (P = 0.33) players. There was a small but significant decline for union in the number and hence the incidence (P = 0.06) of players with permanent neurological deficits, but no significant decline for league (P = 0.16).

Type of play associated with severe cervical spinal cord injuries

Although detailed self-reports and eyewitness accounts of the events surrounding the injuries were available for 43 of the 49 patients with complete tetraplegia, no consistent patterns of play or events could be identified other than that the injury occurred in scrum-like plays (scrums, mauls and rucks; n = 23) or tackles (n = 26). Repeatedly, eyewitnesses observed that a player was found paralysed on the ground, without an obvious causal explanation, while the general play moved on. This lack of a specific, out-of-the-ordinary event was supported by two video recordings of cervical spinal cord injuries that occurred during scrums.

The injuries were most common in scrum-like plays in union and in tackles in league. The most common level of spinal cord damage was C4-5 (Table 3).

Discussion

While any fall in the number and incidence of permanent neurological deficits among union players is pleasing and may well be a consequence of rule changes and safety measures,⁷ the unchanged rate of admissions to spinal units suggests that such improvements may not be sustained.

In those players admitted to spinal units who do not experience permanent neurological deficits, the injuries can be regarded as "near misses" (ie, possible damage to the vertebral column without spinal cord injury).⁷ While evacuation procedures for suspected cervical and other spinal cord injuries may vary, such "near misses" included in the admission rates offer a useful indicator of the risks of such injuries associated with rugby union and league football.⁸

Our observation that cervical spinal cord injuries are more common in scrum-like plays in union and tackles in league is similar to recent findings in New Zealand.⁷ However, there is insufficient information in this review and in the New Zealand⁷ and other reviews⁹ of rugby football-associated spinal cord injury upon which to base sound recommendations for detailed changes to the rules or other safety measures. These reviews confirm the obvious -- that both rugby union and league are inherently dangerous games.

There appear to be several options:

• Maintain the status quo and accept that each year several union and league players in NSW (and elsewhere) will suffer cervical spinal cord injuries which will leave them permanently paralysed below the neck;
• For rugby union, change the rules so as to substantially reduce the number of scrum-like plays and change the organisation of the scrum;
• For rugby league, introduce changes to the rules aimed at substantially altering the nature of the tackle.

Acknowledgement

References

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