Isotension Versus Low-Tension Fixation in Arthroscopic Biceps Tenodesis: A Comparative Study of Clinical Outcomes

Background: It remains uncertain whether anatomic or reduced tension provides superior clinical outcomes in tendon-to-bone fixation for long head of the biceps tendon (LHBT) tenodesis. Hypothesis/Purpose: The purpose was to compare clinical outcomes between isotension and low-tension fixation techniques for LHBT tenodesis. The authors hypothesized that isotension fixation would yield superior clinical outcomes compared to low-tension fixation. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective analysis was conducted on the data of patients who underwent arthroscopic LHBT tenodesis for either LHBT lesions or LHBT lesions combined with rotator cuff tears between May 2019 and June 2024 with ≥1 year of follow-up. Patients were divided into 2 groups based on different tension after tenodesis: isotension group (tenodesis in situ at the bicipital groove followed by resection of proximal tendon insertion) and low-tension group (resection of proximal tendon transection followed by tenodesis of the residual tendon stump in the bicipital groove). Shear wave elastography (SWE) was used to measure the elastic modulus of the LHBT preoperatively and postoperatively at 1 week to evaluate the effects of the 2 fixation methods on the tension of the LHBT. Functional outcome scores (including the American Shoulder and Elbow Surgeons [ASES] score, Constant-Murley score [CMS], visual analog scale [VAS] score, and long head of the biceps [LHB] score) were collected, and the minimal clinically important difference (MCID) for each functional score was calculated. Results: A total of 50 patients in the isotension group (mean follow-up, 26.5 ± 4.7 months) and 73 patients in the low-tension group (mean follow-up, 26.0 ± 6.4 months) were included in this study. SWE showed no preoperative to postoperative stiffness change in the isotension group (6.75 ± 1.07 m/s to 6.70 ± 1.01 m/s; P = .930) but reduced stiffness in the low-tension group (5.88 ± 1.30 m/s postoperatively vs 6.79 ± 1.35 m/s preoperatively; P = .001). Both groups achieved significant postoperative improvement compared with preoperative baseline ( P < .05). At the final follow-up, the isotension group demonstrated superior functional scores to the low-tension group regarding ASES score (93.2 ± 5.5 vs 87.7 ± 8.0; P = .001), CMS (94.2 ± 4.5 vs 91.2 ± 6.6; P = .003), and LHB score (97.6 ± 3.7 vs 91.4 ± 7.8; P = .001). However, VAS improvement showed no significant difference between the 2 groups ( P = .129). Regarding the LHB score subcategories, the isotension group showed significantly better results for elbow flexion strength than the low-tension group (19.3 ± 3.7 points vs 15.7 ± 7.8 points; P = .001). The percentage of patients reaching the MCID differed only in LHB score (86.0% for isotension vs 56.2% for low tension; P = .001), not in ASES score ( P = .238), CMS ( P = .706), or VAS score ( P = .783). The Popeye sign incidence was similar between to 2 groups (2.0% for isotension and 2.7% for low tension; P > .999). Conclusion: Both maintained physiological tension (isotension) and reduced tension (low tension) tenodesis achieved satisfactory outcomes. However, tenodesis maintaining physiological tension demonstrated superior biceps strength recovery and functional score (LHB score) compared to tenodesis with reduced tension.