Intervention

For the 2005 playing season a final number of 59 players were randomly assigned in equal numbers to either a:

a. Control group. They received what was considered best medical and sports science management as directed by club medical staff including medication, manipulative physiotherapy, massage, strength and conditioning and rehabilitation exercises. There was no limitation in the number or type of treatments and no influence from the study authors. This was the usual care they would have been receiving if there had been no research project.

b. Intervention group. They received the same best management as the control group, but in addition pragmatic chiropractic treatment from a single experienced clinician. Features of the chiropractic management included:

• Treatment as determined appropriate on an individual patient/subject basis.

• One or more of joint manipulation (HVLA—high-velocity, low amplitude), joint mobilization (passive movement without thrust and within normal range of motion) and soft-tissue therapies.

• Directed to the spine, pelvis and extremity

• Minimum duration and frequency of treatment of 1 treatment per week for 6 weeks (Phase 1—the late pre-season period where pre-season matches were played) followed by one treatment per fortnight [two weeks] for 3 months—the remainder of the season (Phase 2).

• The average number of treatments was 17 per player. All players received manipulation and/or mobilization—92% received manipulation.

On the average treatment visit, manipulation and/or mobilization was directed at 4 of the 5 treatment areas—thoracic spine, knee, hip, lumbar spine and sacroiliac joint. However, overall the slight majority of treatments (53%) was soft-tissue techniques—principally to the gluteal region and lumbar spine, but also to the hip flexors, knee and posterior thigh.

Overall treatment was predominately directed at areas non-local to the hamstrings.

Outcome Measures

The primary outcome measure adopted was the one used in the AFL Injury Surveillance System, “currently considered the most reliable … method in team sports.” That is the number of games missed due to injury. The injuries monitored in this study were hamstring, other lower limb muscle and non-contact knee injuries. The definition of injury, again using the AFL method, was “any physical or medical condition that prevents a player from participating in a regular season (home and away) or finals match.”

Injury diagnoses were determined by club medical staff who were blinded to group allocation and therefore treatment being given. Staff used either clinical features of injury, advanced imaging or both at their discretion. The club medical and coaching staff independently determined this—there was no interference from the study authors.

Secondary outcome measures were the short form McGill Pain Questionnaire (MPQ-SF) for low back pain and the 39-item Health Status Questionnaire (SF-39). Players completed these prior to randomization into the trial and at the midpoint of the season—after 18 weeks of intervention and 12 home and away season matches.

Finally there was surveillance for adverse outcomes from the treatment being studied, mainly injury defined as “any undue pain, discomfort or disability arising during, immediately after or subsequent to chiropractic therapy that resulted in missed participation in a match or training session” or required additional medical care.