Quantitative assessment of motion smoothness after rotator cuff surgery using HTC VIVE and its correlation with clinical function

At 3 months post-rotator cuff repair, the shoulder joint functional score frequently diverges from patients’ subjective perceptions of their motor quality. Previous literature has indicated that these score values do not necessarily reflect motor quality. Smoothness is the most widely used metric in motion quality research; however, there are currently no relevant datasets to support it. In the present study, we utilized the HTC VIVE system to acquire shoulder joint motion data, calculated motion fluency, and investigated its clinical application value during this postoperative phase. Thirty healthy adults (control group) and 10 patients at 3 months after rotator cuff repair (patient group) were enrolled. Shoulder motion data across five planes (flexion, abduction, extension, internal, and external rotation) were collected via the HTC VIVE system and quantified by log dimensionless jerk (LDLJ) to establish healthy reference intervals. Correlations between movement smoothness and ASES scores were analyzed, and the proportion of patients with smoothness in the reference range was compared between the high- and low-function recovery groups. Flexion and abduction smoothness exhibited a highly significant positive correlation with the ASES score. At 3 months post-rotator cuff repair, shoulder movement smoothness recovery showed pronounced heterogeneity across planes. Flexion and abduction movement smoothness recovered consistently and effectively discriminated between high- and low-function recovery groups. Extension movement smoothness remained mostly within the normal range even in the low-function recovery group. Internal and external rotation movement smoothness were generally delayed in both recovery groups, with external rotation exhibiting the most pronounced delay. Flexion movement smoothness showed optimal predictive efficacy for the high-function recovery group (AUC = 0.96). At 3 months post-rotator cuff repair, flexion and abduction movement smoothness correlate significantly with the ASES score, with flexion movement smoothness showing the best predictive efficacy for high functional recovery. Individual mismatches between patients’ movement quality and their high- or low-function recovery group status may be associated with factors including delayed recovery in rotational planes and scapulothoracic compensatory movement. However, these preliminary conclusions are limited by sample size and require further validation in larger multicenter studies.