Exercise therapy after ultrasound-guided corticosteroid injections in patients with subacromial pain syndrome: a randomized controlled trial.

BACKGROUND: Subacromial pain syndrome (SAPS) accounts for around 50 % of all cases of shoulder pain. The most commonly used treatments are glucocorticosteroid (steroid) injections and exercise therapy; however, despite treatment SAPS patients often experience relapse of their symptoms. Therefore the clinical effect of combining steroid and exercise therapy is highly relevant to clarify. The aim of this randomized controlled trial was to investigate if exercise therapy added to steroid injection in patients with SAPS will improve the effect of the injection therapy on shoulder pain. METHODS: In this two-arm randomized trial running over 26 weeks, patients with unilateral shoulder pain (> 4 weeks) and thickened subacromial bursa (> 2 mm on US) were included. At baseline all participants received two steroid injections into the painful shoulder with an interval of one week. Subsequently they were randomized (1:1) to either 10 weeks exercise of the involved shoulder (intervention group) or exercise of the uninvolved shoulder (control group). The patients were re-examined after the exercise program (at week 13) and again at week 26. The primary outcome assessed after 26 weeks was change in shoulder pain analyzed using the intention-to-treat principle (non-responder imputation). RESULTS: Ninety-nine SAPS patients (58 female) participated (49 intervention/50 control). At both follow up visits (week 13 and 26) no statistically significant between-group differences in pain changes on a visual analog scale (mm) were seen (13 weeks: pain at rest 1.7 (95 % CI -3.6 to 7.0; P = 0.53); pain in activity 2.2 (95 % CI -6.5 to 10.9; P = 0.61), 26 weeks: rest 5.6 (95 % CI -0.9 to 12.1; P = 0.09); activity 2.2 (95 % CI -6.8 to 11.2; P = 0.62). The reduction in pain was most evident in the control group at all four pain measurements. The only difference between groups was seen by US examination at week 13, where fewer participants with impingement were observed in the intervention group compared with the controls (9 vs. 19 participants; P = 0.03). CONCLUSION: Exercise therapy in the painful shoulder in SAPS patients did not improve the effectiveness of steroid injections for shoulder pain in patients with unilateral SAPS and enlarged subacromial bursa on US examination. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT01506804 ). Registration date 5 May 2011.

The dynamics of the pain system is intact in patients with knee osteoarthritis: An exploratory experimental study.

Background and aims Despite the high prevalence of knee osteoarthritis (OA) it remains one of the most frequent knee disorders without a cure. Pain and disability are prominent clinical features of knee OA. Knee OA pain is typically localized but can also be referred to the thigh or lower leg. Widespread hyperalgesia has been found in knee OA patients. In addition, patients with hyperalgesia in the OA knee joint show increased pain summation scores upon repetitive stimulation of the OA knee suggesting the involvement of facilitated central mechanisms in knee OA. The dynamics of the pain system (i.e., the adaptive responses to pain) has been widely studied, but mainly from experiments on healthy subjects, whereas less is known about the dynamics of the pain system in chronic pain patients, where the pain system has been activated for a long time. The aim of this study was to assess the dynamics of the nociceptive system quantitatively in knee osteoarthritis (OA) patients before and after induction of experimental knee pain. Methods Ten knee osteoarthritis (OA) patients participated in this randomized crossover trial. Each subject was tested on two days separated by 1 week. The most affected knee was exposed to experimental pain or control, in a randomized sequence, by injection of hypertonic saline into the infrapatellar fat pad and a control injection of isotonic saline. Pain areas were assessed by drawings on anatomical maps. Pressure pain thresholds (PPT) at the knee, thigh, lower leg, and arm were assessed before, during, and after the experimental pain and control conditions. Likewise, temporal summation of pressure pain on the knee, thigh and lower leg muscles was assessed. Results Experimental knee pain decreased the PPTs at the knee (P <0.01) and facilitated the temporal summation on the knee and adjacent muscles (P < 0.05). No significant difference was found at the control site (the contralateral arm) (P =0.77). Further, the experimental knee pain revealed overall higher VAS scores (facilitated temporal summation of pain) at the knee (P < 0.003) and adjacent muscles (P < 0.0001) compared with the control condition. The experimental knee pain areas were larger compared with the OA knee pain areas before the injection. Conclusions Acute experimental knee pain induced in patients with knee OA caused hyperalgesia and facilitated temporal summation of pain at the knee and surrounding muscles, illustrating that the pain system in individuals with knee OA can be affected even after many years of nociceptive input. This study indicates that the adaptability in the pain system is intact in patients with knee OA, which opens for opportunities to prevent development of centralized pain syndromes.

Altered visual and feet proprioceptive feedbacks during quiet standing increase postural sway in patients with severe knee osteoarthritis.

OBJECTIVE: The objective was to investigate how postural control in knee osteoarthritis (KOA) patients, with different structural severities and pain levels, is reorganized under different sensory conditions. METHODS: Forty-two obese patients (BMI range from 30.1 to 48.7 kg*m(-2), age range from 50 to 74 years) with KOA were evaluated. One minute of quiet standing was assessed on a force platform during 4 different sensory conditions, applied 3 times at random: Eyes open (EO) and eyes closed (EC) standing on firm and soft (foam) surfaces (EO-soft and EC-soft). Centre of pressure (Cop) standard deviation, speed, range and Cop mean position in both directions (anterior-posterior and medial-lateral) were extracted from the force platform data. Structural disease severity was assessed from semiflexed standing radiographs and graded by the Kellgren and Lawrence (KL) score. Pain intensity immediately before the measurements was assessed by numeric rating scale (range: 0-10). RESULTS: The patients were divided into "less severe" (KL 1 and 2, n = 24) and "severe" (KL>2, n = 18) group. The CoP range in the medial-lateral direction was larger in the severe group when compared with the less severe group during EC-soft condition (P<0.01). Positive correlation between pain intensity and postural sway (range in medial-lateral direction) was found during EC condition, indicating that the higher the pain intensity, the less effective is the postural control applied to restore an equilibrium position while standing without visual information. CONCLUSION: THE RESULTS SUPPORT THAT: (i) the postural reorganization under manipulation of the different sensory information is worse in obese KOA patients with severe degeneration and/or high pain intensity when compared with less impaired patients, and (ii) higher pain intensity is related to worse body balance in obese KOA patients.

Experimental knee pain reduces muscle strength.

UNLABELLED: Pain is the principal symptom in knee pathologies and reduced muscle strength is a common observation among knee patients. However, the relationship between knee joint pain and muscle strength remains to be clarified. This study aimed at investigating the changes in knee muscle strength following experimental knee pain in healthy volunteers, and if these changes were associated with the pain intensities. In a crossover study, 18 healthy subjects were tested on 2 different days. Using an isokinetic dynamometer, maximal muscle strength in knee extension and flexion was measured at angular velocities 0, 60, 120, and 180 degrees/second, before, during, and after experimental pain induced by injections of hypertonic saline into the infrapatellar fat pad. On a separate day, isotonic saline injections were used as control condition. The pain intensity was assessed on a 0- to 100-mm visual analogue scale. Knee pain reduced the muscle strength by 5 to 15% compared to the control conditions (P < .001) in both knee extension and flexion at all angular velocities. The reduction in muscle strength was positively correlated to the pain intensity. Experimental knee pain significantly reduced knee extension and flexion muscle strength indicating a generalized muscle inhibition augmented by higher pain intensities. PERSPECTIVE: This study showed that knee joint pain has a significant impact on muscle function. The findings provide evidence of a direct inhibition of muscle function by joint pain, implying that rehabilitative strengthening exercises may be antagonized by joint pain.