A comprehensive review of the normal, abnormal, and post-operative MRI appearance of the proximal biceps brachii

Radiological changes in anterior arm muscles after biceps long head tenotomy

BackgroundAlthough a decrease in pain may be observed after tenotomy, conditions such as muscle cramp, limited elbow flexion, cosmetic deformity (Popeye sign), decreased elbow flexion-supination strength, and persistent pain are also seen, and the exact cause is not fully known.PurposeTo evaluate the changes in the short head of the biceps brachii (SHB) tendon thickness and coracobrachialis muscle after tenotomy.Material and MethodsIn this original article, magnetic resonance imaging (MRI) was performed preoperatively and 6 months postoperatively on 77 patients who underwent biceps brachii long head tenotomy during shoulder arthroscopy and who met the inclusion criteria. Changes in the thickness of the SHB and the coracobrachialis muscle were evaluated. The location where the long head of the biceps brachii (LHB) terminated after tenotomy was also investigated.ResultsIn the 6th postoperative month, we observed a significant increase in both the thickness of the SHB footprint and 2 cm distal to the tendon's origin. In addition, the LHB, which underwent tenotomy, was distracted on average 24.2 mm distally. However, no changes were observed in the thickness of the coracobrachialis muscle during the same period.ConclusionIn this study, we demonstrated prospectively increased thickness of the SHB tendon and no increase in thickness in the coracobrachialis muscle on postoperative MRI.

Increased Load to Failure in Biceps Tenodesis With All-Suture Suture Anchor Compared With Interference Screw: A Cadaveric Biomechanical Study

PURPOSE

To compare the biomechanical characteristics of a single radially expanding all-suture anchor with an interference screw for open subpectoral long head of biceps tendon (LHBT) tenodesis.

METHODS

Eighteen fresh-frozen matched-pair human cadaveric humeri were used for this biomechanical study. The matched pair humeri were randomly assigned into 2 experimental biceps tenodesis groups: conventional interference screw (CIS) or all-suture suture anchor (ASSA). Open subpectoral LHBT tenodesis was then performed and biomechanical testing was performed using a servohydraulic test frame. A preload of 5 N was applied for 2 minutes before cyclic loading. Displacement was recorded at cycle 300 (D300) and cycle 500 (D500) and at ultimate failure. Data recorded included displacement, load to failure, displacement at failure. Paired t test was used for analysis.

RESULTS

Decreased displacement was observed for the CIS group at D300 (1.67 ± 0.57 mm vs 3.35 ± 2.24 mm; P = .04), D500 (2.00 ± 0.76 mm vs 3.87 ± 2.20 mm; P = .04), and at failure (5.17 ± 3.05 mm vs 10.76 ± 2.66 mm; P < .001). Load to failure was lower in CIS specimens (170 ± 24.5 N vs 217.8 ± 51.54 N; P = .02). Failure in each case was tendon pullout for all CIS specimens; in ASSA 6 specimens failed as the suture pulled through the tendon, 2 specimens failed by suture breakage. No difference in stiffness was observed between the 2 groups (CIS = 98.33 ± 22.98 N/m vs ASSA = 75.94 ± 44.83 N/m; P = .20).

CONCLUSIONS

Our study found that open subpectoral biceps tenodesis performed with an ASSA construct results in increased load to failure as compared with CIS. However, the CIS did demonstrate decreased displacement as compared to ASSA in this cadaveric biomechanical study.

CLINICAL RELEVANCE

ASSA and CIS at time zero provide fixation as indicated by the provider intraoperatively for LHBT tenodesis. ASSA, however, does remove less cortical bone than does CIS and therefore produces a smaller stress riser in the proximal humerus. Further testing as to the integrity of ASSA is warranted to determine the integrity of the tenodesis with cyclical loading.