Abstract
AbstractBackgroundReverse shoulder arthroplasty (RSA) is a valuable solution for patients with shoulder pain or injury primarily due to a rotator cuff tear or secondary to traumatic events. Nevertheless, several complications are known to appear, with the most frequent being scapular notching (SN) on the inferior and posterior scapular neck. Controversial data exist about the clinical relevance of SN. Since further consequences are still not clearly understood, we aimed to provide more clarity on which factors, especially external rotation (ER), contribute to the appearance and progress of notching.MethodsConstant Score (CS), Subjective Shoulder Value (SSV), flexion, abduction, and ER were evaluated retrospectively in 153 shoulders of 147 patients (mean age 79±7.7 years; 62% women) who underwent RSA between 2005 and 2010. Anteroposterior radiographs were evaluated before and 1, 2, 3, and 5 years after RSA for SN according to the Sirveaux classification. The evaluation was performed by two independent surgeons. Spearman’s coefficient andt-test were used.ResultsCS, SSV, flexion, and abduction increased significantly 1 year after RSA compared to before (allp < 0.0001). No improvement was shown for ER between the same timepoints. Between 2 and 5 years of follow-up, only flexion decreased by 5°(p = 0.02) while CS, SSV, abduction, and ER remained constant. After RSA, notching increases over time. There was no association between SN and CS, SSV, flexion, abduction or ER at any of the measured timepoints. Higher flexion correlated with higher abduction after RSA at every follow-up (1 yearr = 0.88, 2 yearsr = 0.89, 3 yearsr = 0.86, 5 yearsr = 0.86). The interrater correlation test showed a strong correlation (r = 0.7).ConclusionWe verified the functional benefits of RSA for patients. Additionally, our findings show that despite radiographic progression of notching and unchanged limited ER, the postoperative improvements in CS, SSV, flexion, and abduction are preserved over 5 years.
Highlights
With the Grammont type of reverse prosthesis that was introduced in the late 1980s, a new biomechanical concept was established by lowering and medializing the center of rotation [6, 17]
110 patients were diagnosed with cuff tear arthropathy, four with osteoarthritis and 39 with cuff deficiency or posttraumatic injury
Three patients had surgery due to an emergency, all others were planned in advance for Reverse shoulder arthroplasty (RSA)
Summary
With the Grammont type of reverse prosthesis that was introduced in the late 1980s, a new biomechanical concept was established by lowering and medializing the center of rotation [6, 17]. Several authors have reported that clinically internal and external rotation (ER) do not necessarily improve after RSA despite preservation of the infraspinatus and subscapularis muscle tendon unit [6, 9]. Explanations for this are that the ROM is restrained as a consequence of the limited lateral offset of the prosthesis and that the lever arm of the remaining rotator cuff is reduced by medializing and lowering the center of rotation. Our findings show that despite radiographic progression of notching and unchanged limited ER, the postoperative improvements in CS, SSV, flexion, and abduction are preserved over 5 years
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