Spine Kyphosis influences the range of internal rotation after reverse shoulder arthroplasty
Global kyphosis of the spine influences the range of motion and deterioration of internal rotation after reverse total shoulder arthroplasty
Takayama and Ito
https://doi.org/10.1016/j.jse.2024.10.017(opens in a new tab)
Background
Reverse total shoulder arthroplasty (RTSA – reverse shoulder replacement surgery) is considered a promising surgical procedure, and several studies have reported its advantages in improving shoulder elevation. However, patients undergoing RTSA may still experience challenges related to rotational movements. While external rotation may be improved with lateralization, internal rotation may occasionally deteriorate after RTSA. We hypothesized that sagittal spinal alignment, especially in global kyphosis, is associated with the range of motion (ROM) and deterioration of internal rotation. Therefore, this study aimed to compare the clinical outcomes of patients with and without global kyphosis.
Methods
Global kyphosis occurs when the center of the C7 vertebral body plumb line is anterior to the femoral head (indicating a positive value for the distance between the C7 plumb line and the hip axis [C7-HA]). This study included 100 patients, comprising 65 and 35 patients without and with global kyphosis, respectively. Subsequently, ROM between the two groups were compared. To assess the degree of improvement, the difference between the preoperative and postoperative ROM in the two groups was also evaluated. The patients were also divided into groups showing deterioration and non-deterioration of internal rotation, and the factors affecting deterioration were investigated using logistic regression analysis.
Results
In comparison with the non-global kyphosis group, the global kyphosis group showed significantly inferior flexion (142° ± 20° vs. 119 ± 23°, P< 0.001), abduction (138° ± 21° vs. 114° ± 25°, P < 0.001), external rotation (33° ± 15° vs. 23° ± 15°, P < 0.001), and internal rotation (8 ± 3 L1 vs. 4 ± 2 L5, P< 0.001) and significantly inferior improvements in flexion (86° ± 26° vs. 65° ± 31°, P = 0.002), abduction (83° ± 29° vs. 63° ± 31°, P = 0.002), external rotation (6° ± 16° vs. -1° ± 13°, P = 0.009), and internal rotation (2 ± 3 vs. -2 ± 2, P < 0.001).
Thirty patients, including four and 26 without and with global kyphosis, respectively, showed deterioration in internal rotation. Logistic regression analysis showed that C7-HA was correlated with deterioration in internal rotation (odds ratio, 1.06; 95% confidence interval, 1.03–1.09; P < 0.001).
Conclusion
Global kyphosis (indicated by a positive value for C7-HA) negatively affects ROM and the degree of improvement and is correlated with the deterioration of internal rotation after reverse shoulder replacement(opens in a new tab). The sagittal spinal alignment should be considered when assessing the long-term prognosis of patients with RTSA.
My Opinion
Spinal deformity is automatically perceived by those surgeons who assess the shoulder by standing behind the patient, when considering a reverse shoulder replacement surgery. This position of testing allows for spine deformity and scapula motion evaluation. Both kyphosis and scoliosis of the spine affect how the shoulder works, and needs to be understood and explained to the patient.
