Child Christopher, Scheibel Markus, Wehrli Martina, de Jong Marije, Brune Daniela, Endell David, Audigé Laurent
Shoulder and Elbow Surgery, Schulthess Clinic, Zurich, Switzerland.
Department of Shoulder and Elbow Surgery, Center for Musculoskeletal Surgery, Charité-Universitaetsmedizin Berlin, Berlin, Germany.
JSES Int. 2023 Jul 17;7(6):2349-2355. doi: 10.1016/j.jseint.2023.06.017. eCollection 2023 Nov.
Shoulder strength is an essential assessment to monitor the outcome of treatment interventions. Isometric strength assessment in the Constant Score (CS) was initially measured with a cable tensiometer or spring balance (SB). Some authors have questioned the validity of this strength assessment and the resulting CS. The purpose of this study was to investigate the concordance of strength measurements using an unsecured SB vs. isometric dynamometer and outline the impact of these methods on the CS.
In the context of routine clinical examination as well as participation in a Swiss national cohort study, shoulder strength was measured to calculate baseline (before surgery) and 6-month postoperative CS in adult rotator cuff tear patients who had undergone primary arthroscopic rotator cuff repair. Measurements of each of the operated and contralateral shoulders were made per patient routinely using an unsecured SB and study-specific using an isometric dynamometer in patients with the shoulder at 90° abduction in the scapular plane. Absolute and change values of strength and CS data were presented in scatter plots and assessed using concordance correlation coefficients (CCCs) and Bland-Altman plots.
Between June 2020 and October 2021, baseline strength measurements from the operated shoulder of 78 patients ranged from 0.0 to 13.6 kg with a CCC of 0.64 ( < .001) and a mean difference of 0.81 kg between the SB and dynamometer methods. There were 89 measurements of the contralateral healthy shoulder that ranged from 3.6 to 15.6 kg; CCC and mean strength difference were 0.76 ( < .001) and 0.70 kg, respectively. At 6 months postsurgery, strength measurements of the operated shoulder ranged from 1.4 to 12.0 kg with a CCC of 0.66 ( < .001) and mean strength difference of 0.9 kg (n = 68). Respective 6-month measurements of the contralateral side (n = 52) ranged from 2.0 to 15.9 kg with a CCC of 0.73 ( < .001) and mean strength difference of 0.03 kg.
Absolute and change values in shoulder strength assessments using an unsecured SB and isometric dynamometer are fairly concordant with mean differences of less than 1 kg between methods. With the variability of strength differences among patients, interpretation of these values for individual patients may be challenging. Nonetheless, unsecured SB and dynamometer methods share only slight and clinically unimportant differences that can provide similar group mean values for use in research along with the calculation of the CS.
肩部力量是监测治疗干预效果的重要评估指标。Constant评分（CS）中的等长力量评估最初是用缆线张力计或弹簧秤（SB）进行测量的。一些作者对这种力量评估方法以及由此得出的CS的有效性提出了质疑。本研究的目的是调查使用无固定弹簧秤与等长测力计进行力量测量的一致性，并概述这些方法对CS的影响。
在常规临床检查以及参与一项瑞士国家队列研究的背景下，对接受初次关节镜下肩袖修补术的成年肩袖撕裂患者测量肩部力量，以计算基线（手术前）和术后6个月的CS。每位患者的患侧和对侧肩部测量均常规使用无固定弹簧秤，对于肩部处于肩胛平面外展90°的患者，采用特定研究的等长测力计进行测量。力量和CS数据的绝对值及变化值以散点图呈现，并使用一致性相关系数（CCC）和Bland-Altman图进行评估。
在2020年6月至2021年10月期间，78例患者患侧肩部的基线力量测量值范围为0.0至13.6千克，CCC为0.64（<0.001），弹簧秤和测力计方法之间的平均差异为0.81千克。对侧健康肩部进行了89次测量，范围为3.6至15.6千克；CCC和平均力量差异分别为0.76（<0.001）和0.70千克。术后6个月，患侧肩部的力量测量值范围为1.4至12.0千克，CCC为0.66（<0.001），平均力量差异为0.9千克（n = 68）。对侧相应的6个月测量值（n = 52）范围为2.0至15.9千克，CCC为0.73（<0.001），平均力量差异为0.03千克。
使用无固定弹簧秤和等长测力计进行肩部力量评估时，绝对值和变化值相当一致，方法之间的平均差异小于1千克。鉴于患者之间力量差异的变异性，对个体患者这些值的解读可能具有挑战性。尽管如此，无固定弹簧秤和测力计方法之间的差异很小且在临床上不重要，可为研究提供相似的组均值，并用于CS的计算。
