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Table 1 Study characteristics

From: Impact of audible pops associated with spinal manipulation on perceived pain: a systematic review

Study

Aim

Participants

Intervention

Presence of AP’S

Outcome measure

Conclusion

Bialosky et al. [20]

U.S.A

Prospective Cohort Secondary analysis

Assess the role of the AP in HVLA manipulation associated thermal pain sensitivity to both A-delta fiber mediated pain perception and temporal summation

n = 40

Males and females, pain free, aged 18–60

HVLA thrust technique on the sacroiliac joint two times on each side, regardless of whether an AP was perceived. The examiner noted if AP was perceived

AP present:

n = 18

AP absent:

n = 22

NPRS as a measure of expected and perceived pain and psychological questionnaires (PCS, FPQ-III and anxiety VAS). Immediate follow-up directly after intervention and after 4 min

Hypoalgesia is associated with HVLA manipulation and occurs independently of a perceived AP. Inhibition of lower extremity temporal summation may be larger when AP is perceived

Sillevis and Cleland [21]

U.S.A

RCT

secondary analysis

1. Determine if audible sounds during a thrust manipulation have an immediate effect on pain perception within a group of chronic neck pain patients. 2. Determine if there is a positive correlation between the presence of audible sounds and a change in autonomic function

n = 100

Males and females with chronic (present for at least 3 months) cervical pain aged 18–65

High-velocity anterior-to-posterior force to the upper thoracic spine targeting T3-T4 segment in supine position. Presence of audible sounds recorded by the researcher. Control: mobilization directed at T3-T4

n = 50 mobilization

n = 50 manipulation

of which

One pop:

n = 14

Multiple pops:

n = 18

No pop: n = 18

VAS used to assess pain and automated pupillometry used to capture pupil responsiveness measured in the form of pupil diameter. Follow-up directly after intervention and after 4 min

The presence of joint sounds does not influence the overall activity of the autonomic nervous system (P = .31, .44, .47, respectively) following a thrust manipulation or contribute to the reduction of pain (P > 0.05) in patients with chronic neck pain

Cleland et al. [22]

U.S.A

Prospective Cohort secondary analysis

Examine the relationship between the audible pop and patient-centered outcomes in a cohort of patients with neck pain treated with thoracic spine thrust manipulation

n = 72

Males and females with neck pain with or without unilateral upper extremity symptoms, and baseline NDI > 10% aged 18–60

3 different thrust manipulation techniques to the thoracic spine: distraction manipulation, upper and middle thoracic spine manipulation. The presence or absence of an AP was noted by the treating therapist. 3 thrusts were repeated if no AP was noted

 ≤ 3 pops:

n = 21

 > 3 pops:

n = 51

Change scores for pain and disability (NDI and NPRS) and cervical ROM. Additionally, GROC was completed. Follow-up 2–4 days after first session

No relationship between the number of audible pops and clinically meaningful improvements in pain (P = 0.41), disability (P = 0.66) or cervical ROM (P > 0.05) in patients with neck pain

Flynn et al. [23]

U.S.A

Prospective Cohort secondary analysis

Investigate whether the occurrence of a manipulative pop during sacroiliac region manipulation is related to the outcome of the intervention over a 4-week period

n = 70

Males and females with a primary complaint of low back pain with or without referral into the lower extremity and an ODQ score of > 30% aged 18–60

Total of 5 physical therapy sessions over 4 weeks. In the first two sessions pts received HVLA thrust manipulation on the sacroiliac region on the more symptomatic side, and ROM exercise. If cavitation heard onto ROM exercise. If no cavitation heard after additional attempt on opposite side with a maximum of two attempts per side, onto ROM exercise. Cavitation was noted by the patient or therapist

AP present:

n = 59

AP absent:

n = 11

NPRS to rate pain intensity, ODQ and measurement of lumbopelvic flexion ROM changes. Follow-up at 1 week, and 4 weeks after intervention

AP may not relate to improved outcomes from HVLA thrust manipulation for patients with non-radicular low back pain at either an immediate odds ratio: 1.1 (95% CI, 0.29–3.86) or longer-term odds ratio: 1.7 (95% CI, 0.41–7.1) follow-up

Flynn et al. [24]

U.S.A

Prospective Cohort

Investigate whether the occurrence of a manipulative pop during sacroiliac region manipulation is related to the outcome of the intervention

n = 71

Males and females with non-radicular low back pain aged 18–60

HVLA thrust technique on the sacroiliac joint, side determined by an algorithm. The therapist noted whether the therapist or patient heard an AP. If no AP, the manipulation was repeated. If no AP, the therapist manipulated the opposite site with a maximum of 2 attempts per side

AP present:

n = 50

AP absent:

n = 21

Changes in ROM, NPRS scores and modified ODQ scores. Reassessment 48 h after the manipulation

No relationship between AP during sacroiliac region manipulation and improvement in ROM (P = 0.74), pain (P = 0.23) or disability (0.49). Occurrence of AP did not improve odds of dramatic improvement

  1. AP Audible Pop, HVLA High-Velocity Low-Amplitude, NPRS Numeric Pain Rating Scale, PCS Pain Catastrophizing Scale, FPQ-III Fear of Pain Questionnaire III, VAS Visual Analog Scale, RCT Randomized Controlled Trial, NDI Neck Disability Index, ROM Range of Motion, GROC Global Rating of Change, ODQ Oswestry Disability Questionnaire.