Return of shoulder girdle function after anterior versus posterior adolescent idiopathic scoliosis surgery

Multicenter, prospective, cohort study.

To compare minimum 2-year postoperative shoulder function after 3 different surgical approaches for the treatment of primary thoracic curves in patients with adolescent idiopathic scoliosis (AIS).

Thoracic spinal instrumentation and fusion can be performed via posterior (PSF), open anterior (OASF), or thoracoscopic anterior (TASF) techniques. Although the morbidity of these 3 surgical approaches is beginning to be understood, no reports have been published comparing 2-year postoperative shoulder strength and range of motion.

AIS patients who underwent selective fusion of primary thoracic curves were studied. Right-sided shoulder strength (flexion, abduction) and range of motion (flexion, extension, abduction) measurements were collected prospectively at selected intervals. An arbitrary threshold (80% of preoperative value) was defined as postoperative return of normal shoulder function. Univariate analysis of variance (P < 0.05) was used to compare differences in shoulder function for the 3 approaches at each postoperative time-point.

Ninety-two patients with minimum 2-year postoperative shoulder function data were included in this study (24 PSF, 32 OASF, and 36 TASF). On average, patients who had an OASF failed to reach the 80% threshold for right shoulder forward flexion and abduction strength until 1-year and 6-months after surgery, respectively; whereas patients that had a TASF or PSF returned to normal shoulder strength by the 3-month follow-up visit. With regards to ROM, patients in all 3 groups surpassed the 80% preoperative threshold for right shoulder active forward flexion and extension by the 6-week visit, with no clinically significant differences between the groups. However, for active abduction range of motion, patients that had an OASF required 3-months to regain 80% of their preoperative motion, compared to 6-weeks for patients in both the TASF and PSF groups.

Approach-related differences in shoulder morbidity do exist in the treatment of primary thoracic curves in AIS. Specifically, OASF imparts a significantly greater magnitude and duration of postoperative shoulder dysfunction than do the TASF or PSF approaches. Nonetheless, these negative effects are transient as shoulder function in those patients treated via an open thoracotomy normalized by the 1-year postoperative time-point at the latest. Accordingly, viewed in isolation, shoulder morbidity should not deter surgeons from using an open anterior approach in the surgical treatment of AIS.