The Biomechanical and Histological Processes of Rerouting Biceps to Treat Chronic Irreparable Rotator Cuff Tears in a Rabbit Model

Background: Recently, the biceps was rerouted into a newly fabricated bicipital groove for in situ superior capsular reconstruction (SCR), resulting in promising time-zero cadaveric and clinical outcomes. However, no studies have determined the in vivo biomechanical and histological processes after the biceps is transposed to a nonanatomic position. Purpose: To explore the in vivo biomechanical and histological processes of the rerouting biceps tendon to treat chronic irreparable rotator cuff tears (IRCTs) in a rabbit model. Study Design: Controlled laboratory study. Methods: A total of 94 skeletally mature male rabbits were used to create a chronic IRCT model in the supraspinatus tendon. Then, the biceps rerouting procedures were performed in rabbits with chronic IRCT. Eighteen rabbits were sacrificed at 1, 3, 6, 9, and 12 weeks postoperatively for biomechanical testing, micro—computed tomography scanning, and histological analysis. The biomechanical and histological changes of intra- and extra-articular portions of the rerouting biceps were evaluated at each time point, with the contralateral native superior capsule (NSC) and the native biceps (NB) as controls, respectively. The morphology and bone formation of the fabricated bicipital grooves were evaluated, with native grooves as controls. Results: The intra-articular rerouting biceps tendon was progressively remodeled over time, displaying denser fibers and more mature collagen than those of the NSC, with gradual improvements in the tendon-to-bone healing interface from 6 to 12 weeks. Consequently, the failure load and stiffness of the intra-articular rerouting biceps portion increased with time and were significantly higher than those of the NSC from 9 weeks. Similarly, the extra-articular portion of the rerouting biceps progressively healed into a new bicipital groove, as demonstrated by a smaller tendon-to-bone interface from 6 to 12 weeks, resulting in greater failure load and stiffness at 9 and 12 weeks than those of the NB attachment. The newly fabricated bicipital groove showed similar morphology to that of the native groove with sufficient trabecular bone formed underneath. Conclusion: The rerouting biceps could progressively remodel and heal into the newly fabricated bicipital groove over time, resulting in greater biomechanical performances in intra- and extra-articular portions than the NSC and the NB attachment. Clinical Relevance: The biceps rerouting technique may be a feasible procedure to perform in situ SCR to treat IRCT in the future clinical practice; however, more clinical evidence is required.

Biceps Augmentation Outperforms Tear Completion Repair or In Situ Repair for Bursal-Sided Partial-Thickness Rotator Cuff Tears in a Rabbit Model

Background: There is an ongoing debate on the treatment of bursal-sided partial-thickness rotator cuff tears (PTRCTs), including ideal repair techniques. Augmentation using a collagen patch has been introduced as a new surgical approach to treat PTRCTs, while the effect of autogenous biceps augmentation (BA) has not been investigated. Purpose: To analyze the effects of BA on bursal-sided PTRCTs and compare its histological and biomechanical results with those of tear completion followed by repair and in situ repair (ISR). Study Design: Controlled laboratory study. Methods: Unilateral chronic PTRCTs were created in 96 mature New Zealand White rabbits, which were randomly divided into 4 groups: no repair, tear completion repair (TCR), ISR, and BA. A new bicipital groove was fabricated in BA for the biceps tendon that was transferred to augment the bursal-sided PTRCT repair. In each group, we sacrificed 6 rabbits for biomechanical testing of the whole tendon-to-bone complex (WTBC) and 6 for histological evaluation of bursal- and articular-sided layers at 6 and 12 weeks postoperatively. Healing responses between the biceps and new bicipital groove in the BA group were determined using histological analysis, and final groove morphologies were evaluated using micro–computed tomography. Results: The remaining tendon and enthesis in bursal-sided PTRCTs progressively degenerated over time. WTBCs of ISR exhibited a larger failure load than those of TCR, although better healing properties in the bursal-sided repaired site were achieved using TCR based on histological scores and superior articular-sided histological scores were observed using ISR. However, WTBCs of BA displayed the best biomechanical results and superior histological scores for bursal- and articular-sided regions. The new bicipital groove in BA remodeled over time and formed similar morphologies to a native groove, which provided a mature bone bed for transferred biceps tendon healing to augment bursal-sided PTRCTs. Conclusion: BA achieved better biomechanical and histological results for repairing bursal-sided PTRCTs as compared with TCR and ISR. When compared with that of TCR, the WTBC of ISR exhibited a higher failure load, showing histological superiority in the articular-sided repair and inferiority in the bursal-sided repair. Clinical Relevance: BA may be an approach to improve bursal-sided PTRCT repair in humans, which warrants further clinical investigation.

The Relevant Anatomy of the Biceps Tendon When Performing Tenodesis in Filipino Cadaveric Specimens

Background: Biceps tenodesis is a technique frequently performed in shoulder surgeries. Various techniques have been described, but there is no consensus on which technique restores the length-tension relationship. Restoration of the physiologic length-tension relationship has been correlated to better functional outcomes, such as decreased incidence of residual pain or weakness of the biceps. The objective of this study was to measure the anatomic relationship of the origin of the biceps tendon with its zones in the upper extremity. This would provide an anatomic guide or an acceptable placement of the tenodesis to reestablish good biceps tension during surgery. Methods: The study used nine adult cadavers (five males, four females) from the [withheld for blinded review]. Nine shoulder specimens were dissected and markers were placed at five points along each biceps tendon: (1) Labral origin (LO) (2) Superior bicipital groove (SBG) (3) Superior border of the pectoralis tendon (SBPMT) (4) Musculotendinous junction (MTJ) and (5) Inferior border of the pectoralis tendon (IBPMT). Using the origin of the tendon as the initial point of reference, measurements were made to the four subsequent sites. The humeral length was recorded by measuring the distance between the greater tuberosity and the lateral epicondyle as well as the tendon diameter at the articular surface. Results: The intraclass correlation coefficient was excellent across all measures. A total of nine cadavers were included. Mean age of patients was 66.33 years old, ranging from 52-82 years old. These were composed of five male and four female cadavers. The mean tendon length was 24.83mm ± 4.32 from the origin to the superior border of the bicipital groove, 73.50mm ± 6.96 to the Superior Border Pectoralis Major Tendon, 100.89mm ± 6.88 to the Musculotendinous Junction, and 111.11mm ± 7.45 to the Inferior Border Pectoralis Major Tendon. The mean tendon diameter at the articular origin was 6.44mm ± 1.76. Conclusion: This study provided measurement guidelines that could restore the natural length-tension relationship during biceps tenodesis using the interference screw technique in Filipinos. A simple method of restoring a normal length-tension relationship is by doing tenodesis close to the articular origin and creating a bone socket of approximately 25mm in depth, using the superior border of the bicipital groove as a landmark.

The Loop Tenodesis Procedure—From Biomechanics to First Clinical Results

(1) Introduction: Several surgical therapy options for the treatment of pathologies of the long biceps tendon (LHB) have been established. However, tenotomy, as well as established tenodesis techniques, has disadvantages, such as cosmetic deformities, functional impairments and residual shoulder pain. This study presents the first clinical and structural results of the recently introduced loop tenodesis procedure for the LHB, developed to overcome these issues. (2) Methods: 37 patients (11 women, 26 men, mean age 52 years), who underwent loop tenodesis of the LHB were examined six months after surgery. For the clinical evaluation the Constant score, as well as the LHB score, were used, complemented by elbow flexion and supination strength measurements. The integrity of the tenodesis construct was evaluated indirectly by sonographic detection of the LHB in the bicipital groove. (3) Results: Both, the overall Constant score as well as the LHB score showed significant improvements six months postoperatively, as compared to the preoperative value. Fourteen patients (38%) presented an examiner-dependent upper arm deformity, although only five patients (13%) reported subjective cosmetic deformities. Both, flexion and supination strength were preserved compared to the preoperative level. In 35 patients (95%), the tenodesis in the bicipital groove was proofed sonographically. (4) Conclusion: The loop tenodesis of the LHB provides good-to-excellent overall clinical results after a short-term follow-up of six month. The incidence of cosmetic deformities was inferior compared to conventional therapy options (tenotomy and anchor tenodesis).

Measurements of Tendon Movement Within the Bicipital Groove After Suprapectoral Intra-articular Biceps Tenodesis in a Cadaveric Model

Background: Lesions of the long head of the biceps can be successfully treated with biceps tenotomy or tenodesis when surgical management is elected. The advantage of a tenodesis is that it prevents the potential development of a cosmetic deformity or cramping muscle pain. Proponents of a subpectoral tenodesis believe that “groove pain” may remain a problem after suprapectoral tenodesis as a result of persistent motion of the tendon within the bicipital groove. Purpose/Hypothesis: To evaluate the motion of the biceps tendon within the bicipital groove before and after a suprapectoral intra-articular tenodesis. The hypothesis was that there would be minimal to no motion of the biceps tendon within the bicipital groove after tenodesis. Study Design: Controlled laboratory study. Methods: Six fresh-frozen cadaveric arms were dissected to expose the long head of the biceps tendon as well as the bicipital groove. Inclinometers and fiducials (optical markers) were used to measure the motions of the scapula, forearm, and biceps tendon through a full range of shoulder and elbow motions. A suprapectoral biceps tenodesis was then performed, and the motions were repeated. The motion of the biceps tendon was quantified as a function of scapular or forearm motion in each plane, both before and after the tenodesis. Results: There was minimal motion of the native biceps tendon during elbow flexion and extension but significant motion during all planes of scapular motion before tenodesis, with the most motion occurring during shoulder flexion-extension (20.73 ± 8.21 mm). The motion of the biceps tendon after tenodesis was significantly reduced during every plane of scapular motion compared with the native state ( P < .01 in all planes of motion), with a maximum motion of only 1.57 mm. Conclusion: There was a statistically significant reduction in motion of the biceps tendon in all planes of scapular motion after the intra-articular biceps tenodesis. The motion of the biceps tendon within the bicipital groove was essentially eliminated after the suprapectoral biceps tenodesis. Clinical Relevance: This arthroscopic suprapectoral tenodesis technique can significantly reduce motion of the biceps tendon within the groove in this cadaveric study, possibly reducing the likelihood of groove pain in the clinical setting.

Definition, classification and morphometry of entrance of the bicipital groove and its associations with lesions of adjacent structures

Background The definition of the entrance of the bicipital groove (EBG) is still unclear, and the relationships between the EBG and lesions of the long head of the biceps brachii tendon (LBT) and biceps pulley complex (BPC) have long been controversial. The purpose of this anatomic and imaging study was to define the EBG and to examine morphological parameters, classifications, and their relationships with lesions of the LBT and BPC. Methods One hundred thirteen unpaired intact dry humeri, 34 cadaveric shoulder specimens and 278 shoulder images were collected, measured, and classified based on morphological characteristics. Soft tissue and bony landmarks of the EBG were classified into different types. The relationships between the types and lesions of the LBT and BPC were analyzed through an anatomic and imaging study. Results Type II, type A and type i of the EBG and type b of the adjacent articular surface accounted for most of the dry humeri, cadavers, and images. Based on the EBG classification in the superoinferior image view, all of the subluxations and dislocations were classified as type B (61/120, 50.83%; χ2 = 16.55, P < 0.001), and most LBT and BPC lesions were type B (65/117, 55.56%; χ2 = 26.05, P < 0.001). LBTs were injured in (χ2=, P < 0.001) 83.56% of type B, 100% of type C, and 95.83% of type iii EBGs (χ2 = 135.69, 31.89, all P < 0.001). Similarly, BPCs were injured in 89.04% of type B and 93.10% of type C EBGs (χ2 = 153.14, P < 0.001), while BPCs were injured in 95.8% of type iii EBGs (χ2 = 33.79, P < 0.001). Conclusions The EBG is an anatomical concept worthy of clinical attention. Anatomical variations in the EBG correlated with lesions of the LBT and BPC. LBT and BPC lesions correlated with type B and C EBGs by imaging analysis.