The difference in multifidus muscle morphology and motor control in non-specific low back pain with clinical lumbar instability and healthy subjects: A case-control study.

BACKGROUND: Low back pain (LBP) with clinical lumbar instability (CLI) is considered a subgroup of back pain. Poor core stability function and/or lack of motor controls are thought to play a role in inappropriate inter-segmental movements and pain. There is no study investigating the changes in the lumbar multifidus muscle (LMM) morphology and motor control in this subgroup of patients. OBJECTIVE: To assess motor control components and morphological changes of LMM in the patients suffering from chronic nonspecific low back pain (CNSLBP) with CLI. DESIGN: Observational case-control study. METHODS: Thirty-two patients suffering from (CNSLBP) with CLI and 32 healthy individuals were included. The muscle force element of lumbar motor control was assessed by using (the active straight-leg raise test, leg lowering test, and Trendelenburg test). Ultrasonography was used to assess changes in the LMM morphology. RESULTS: There was a significant decrease in motor control (p = 0.0001), an increase in LMM fatty infiltration (p = 0.002), and a decrease in the thickness of LMM in patients suffering from CNSLBP during contraction (p = 0.006), during rest (p = 0.018). The cross-section area of the LMM showed no statistically significant differences during rest on the right and left sides (p = 0.827, 0.220 respectively) and contraction (p = 0.160, 0.278 respectively) between patients and healthy subjects. CONCLUSION: Motor control and the morphology of LMM in patients with CNSLBP with CLI may provide insight into the mechanisms of underlying pain and their effect on muscle function and structure.

Impact of different CRPS phenotypes and diagnostic criteria on quantitative sensory testing outcomes: systematic review and meta-analysis.

OBJECTIVES: This review and meta-analysis evaluated the impact of diagnostic criteria and clinical phenotypes on quantitative sensory testing (QST) outcomes in patients with complex regional pain syndrome (CRPS). METHODS: Eight databases were searched based on a previously published protocol. Forty studies comparing QST outcomes between CRPS-I vs II, warm vs cold CRPS, upper vs lower limb CRPS, males vs females, or using Budapest vs older IASP criteria were included. RESULTS: Studies investigating QST differences between CRPS-I vs II (n = 4), between males vs females (n = 2), and between upper and lower limb CRPS (n = 2) showed no significant differences. Four studies compared QST outcomes in warm vs cold CRPS, showing heat hyperalgesia in warm CRPS, with thermal and mechanical sensory loss in cold CRPS. Although CRPS diagnosed using the Budapest criteria (24 studies) vs 1994 IASP criteria (13 studies) showed similar sensory profiles, there was significant heterogeneity and low quality of evidence in the latter. CONCLUSIONS: Based on the findings of this review, classifying CRPS according to presence or absence of nerve lesion into CRPS-I and II, location (upper or lower limb) or according to sex might not be clinically relevant as all appear to have comparable sensory profiles that might suggest similar underlying mechanisms. In contrast, warm vs cold phenotypes exhibited clear differences in their associated QST sensory profiles. To the extent that differences in underlying mechanisms might lead to differential treatment responsiveness, it appears unlikely that CRPS-I vs II, CRPS location, or patient sex would prove useful in guiding clinical management.

Pain mechanisms in complex regional pain syndrome: a systematic review and meta-analysis of quantitative sensory testing outcomes.

BACKGROUND: Complex regional pain syndrome (CRPS) is a chronic condition following inciting events such as fractures or surgeries with sensorimotor and autonomic manifestations and poor prognosis. This review aimed to provide conclusive evidence about the sensory phenotype of CRPS based on quantitative sensory testing (QST) to understand the underlying pain mechanisms and guide treatment strategies. DATABASES: Eight databases were searched based on a previously published protocol. Forty studies comparing QST outcomes (thermal, mechanical, vibration, and electric detection thresholds, thermal, mechanical, pressure, and electric pain thresholds, wind-up ratio, mechanical pain sensitivity, allodynia, flare area, area after pinprick hyperalgesia, pleasantness after C-tactile stimulation, and pain ratings) in chronic CRPS (adults and children) versus healthy controls were included. RESULTS: From 37 studies (14 of low quality, 22 of fair quality, and 1 of good quality), adults with CRPS showed: (i) significant loss of thermal, mechanical, and vibration sensations, significant gain of thermal and mechanical pain thresholds, significant elevation of pain ratings, and no difference in wind-up ratio; (ii) significant reduction of pleasantness levels and increased area of pinprick hyperalgesia, in the affected limb. From three fair-quality studies, adolescents and children with CRPS showed loss of cold detection with cold hyperalgesia in the affected limb. There was moderate to substantial overall heterogeneity. CONCLUSION: Diffuse thermal and mechanical hypoesthesia with primary and secondary hyperalgesia, enhanced pain facilitation evidenced by increased area of pinprick hyperalgesia, and elevated pain ratings are dominant in adults with CRPS. Adolescents and children with CRPS showed less severe sensory abnormalities.

The relationship between ankle dorsiflexion range of motion, frontal plane projection angle, and patellofemoral pain syndrome.

BACKGROUND: Ankle range of motion abnormalities have been often linked with alteration in knee kinematics leading to the development of patellofemoral pain syndrome (PFPS). Literature exploring the relationship between ankle dorsiflexion range of motion (DF ROM) and knee kinematics during functional tasks is scanty. This study aims to assess the relation between ankle DF ROM and frontal plane projection angle (FPPA), one of the knee kinematic variables, in individuals with and without PFPS during a step-down test. METHODS: This is a case-control study in which seventy PFPS patients and other 70 asymptomatic control subjects had their ankle DF ROM measured using an inclinometer with the knee flexed and extended. Their FPPA angles were measured using Kinovea software while doing the step-down test. RESULTS: When the two groups were compared, ankle DF ROM measured with the knee flexed was higher in the control group (33.15 ± 4.96) than in the PFPS group (30.20 ± 6.93) (p = 0.03). In both the PFPS group and the control group, the correlation between FPPA and ankle DF ROM with the knee flexed was statistically insignificant (p = 0.075 and 0.323 respectively). CONCLUSION: Decreased ankle DF ROM can be one of the contributing factors to the development of PFPS in the context of greater dynamic knee valgus.