DIAGNOSIS AND REHABILITATION By Caryl Becker, MCSP

A study by Hollenberg (1) showed that in up to 47% of adolescents with lower back pain, a pars interarticularis fracture was reported. In another study by Gregory et al (2) it was reported that the incidence of injuries in young fast bowlers was 0.165/1000 balls bowled, in comparison with 0.066/1000 in spin bowlers. In the fast bowling group, 17.6% of these were lower back injuries.

A much earlier study in 1976 by Wiltse (3) showed that 6% of the general population had pars interarticularis defects irrespec- tive of whether they played sport or not. It was suggested that the cause of these could be considered to be a fatigue frac- ture due to repetitive load and stress rather than a single traumatic event. It would seem from the above that young fast bowlers who repetitively put their lower backs under pressure during the bowling action are more at risk of this overuse type injury than most.

DIAGNOSIS A stress fracture of the lower back affects the pars interarticu- laris, which is to be found between the inferior and superi- or process of the neural arch at the junction between the lami- nae and pedicles. Spondylolysis is a separation in the neural arch and is considered to be complete if it passes right through the pars and incomplete if the fracture appears on one side of the cortex and not the other (4).

LUMBAR SPONDYLOLYSIS

Lumbar spondylolysis, or stress fractures of the lower back have been reported in a number of different sports including gymnastics, golf, tennis, football and cricket. All of these are known as one-sided sports and involve a combination of rotation and lateral flexion of the lower back. This article focuses on the profile of this injury in young fast bowlers.

Hollenberg et al (1) proposed that lumbar spondylolysis resulted from repetitive trauma with the beginning being a radi- ographically occult stress-related injury to the pars without cortical interruption.

Over time and with repetitive trauma this injury can progress to a complete spondy- lolysis visible on plain radiographs. The diagnosis however tends to be made fol- lowing an MRI scan or a bone isotope scan as young fast bowlers tend to expe- rience symptoms before plain radiographs indicate the fracture (these symptoms are outlined in more detail on page 8).

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Figure 1: Diagram showing the pars interarticularis on a lumbar vertebra

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POSSIBLE CAUSES Two papers written in the 90s support a multifactorial aetiology concept. Bell (5) suggested that the cause of the injuries in cricketers was a combination of incorrect technique, poor preparation, overuse and

clinical features. Stretch (6) goes further and suggests that the predisposing fac- tors causing spondylolysis were are a com- bination of inadequate physical and phys- iological factors, postural defects, high physical demands, biomechanical aspects of the bowling technique, escalation in training frequency and duration of bowl- ing spells in both matches and training.

Only by examining and understanding the biomechanics of the bowling action can a practitioner start to see and understand why the lower back is at such risk. It is only when this is understood that treat- ment can be effective.

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