Shin, Alexander Y.

Case: An upper trunk brachial plexus injury patient underwent ulnar motor fascicular to biceps motor nerve transfer. At 6 months postoperative, the patient had trace biceps firing but was diagnosed with an unrecognized rupture of the distal biceps tendon, requiring reconstruction. Another patient with C5-T1 injury was noted to have distal biceps tendon rupture at the time of gracilis muscle transfer. Both patients had gravity-assisted elbow flexion at 1-year follow-up. Conclusion: Biceps rupture is an uncommon concomitant injury with brachial plexus trauma and challenging to diagnose in the context of a paretic limb. Thorough history and intraoperative biceps tendon palpation will ensure these injuries are identified.

Background: Secondary shoulder deformities are the most frequent sequelae of upper trunk-type brachial plexus birth injury (BPBI). Coracoid process dysplasia was recently described as being associated with glenoid retroversion and was recognized to block successful humeral head relocation. There are little to no reports on coracoid process deformity causing anterior shoulder pain. Our hypothesis is that coracoid process impingement causes anterior shoulder pain in BPBI, which is relieved by coracoid excision. This study presents the short-term results of this new technique in BPBI patients. Methods: A retrospective review identified BPBI patients who underwent coracoid excision from 2000 to 2022. Indications for this procedure include BPBI patients with anterior shoulder pain limiting the range of motion, localized tenderness over a prominent coracoid process, a dysplastic coracoid process seen on imaging, and persistent pain despite activity modification, medication, and therapy. Patient characteristics, preoperative shoulder pain score, range of motion, degree of glenohumeral subluxation, patient-reported outcomes measurement information system (PROMIS) scores for pain interference, and physical and upper extremity function were collected from chart review. Postoperative pain scores, range of motion, and PROMIS scores were collected at an average of 1 year after excision. Results: Five upper trunk BPBI patients, ages 10 to 25 years old, with anterior shoulder pain underwent coracoid excision. All had statistically significant pain relief from 6.5–8.5/10 before to 0–3/10 after the procedure. Forward flexion and external rotation improved by an average of 18 degrees. The pain interference score decreased by 25%. There was a 33% improvement in physical function scores and a 31% increase in upper extremity function scores. No complications or recurrence were observed at 7.5 months to 1 year and 7 months after surgery. Conclusions: Coracoid excision is a simple procedure that can relieve localized shoulder pain caused by coracoid impingement in adolescent/adult BPBI. Continued follow-up of all patients will be undertaken to determine long-term recurrence rates and complications. Level of Evidence: Level IV.

Segmental bone loss reconstruction using frozen bone allografts has a great advantage over amputation. Unfortunately, frozen allografts are avascular, and their use often results in infection, non-union, or fracture. We have attempted to overcome these complications by revascularizing the bone using gene therapy. Segmental tibial bone transplants were performed in 16 Yucatan minipigs. An arteriovenous (AV) bundle was placed intramedullary inside the allografts, which were transfected with growth factors vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) in 8 out of the 16 pigs. Survival time was set at 20 weeks. Bone remodeling and biomechanical properties were tested using histology, compression testing, bone mineralization, and gait analysis. In the growth factor group, five out of eight pigs developed cutaneous vascular tumors, causing excessive bleeding, which led to the exclusion of one pig. Bone remodeling was significantly more present in the VEGF group compared to the control group. This correlated with the amount of pressure the pig allowed on the operated leg for 10 weeks, which was also significantly more (p = 0.029) than the control. Both bone mineralization (p = 0.156) of the area inside the cortex and the amount of stress the allograft could endure before breaking (p = 0.078) seemed to be no different for the VEGF group compared to its healthy contralateral side, which was the control group. We have shown that growth factor-induced frozen allograft bone revascularization using an intramedullary AV bundle results in significantly more bone remodeling and better biomechanical bone properties. However, we encountered benign vascular cutaneous tumors in five out of eight pigs, making the clinical application of this technique impossible at this time.

AbstractThe sliding filament theory explains skeletal muscle fibre force change as a function of length based on the overlap of actin and myosin filaments. Although this length‐tension (LT) relationship has been well investigated in animal models, it is not known whether this microscopic sarcomere LT property can be scaled up five orders of magnitude to explain the LT behaviour of a long human muscle such as the gracilis. The goal of this study is to validate the sarcomere LT curve in humans based on human filament length combined with in vivo experimental data. Intraoperative measurements of maximal tetanic force and muscle‐tendon unit length at four different joint configurations (JC) were obtained from 19 patients undergoing free functioning muscle transfer surgery. With physiologically measured fibre length and estimated sarcomere shortening resulting from tendon compliance, we show that 79.7% variance in isometric force data is explained by a simple human sarcomere LT model. This study demonstrates that the human whole muscle LT relationship can be modelled by the sliding filament theory given patient‐specific fibre length, filament length, tendon compliance and sarcomere shortening. imageKey points Whole human gracilis muscle isometric length‐tension relationships were measured in the operating room. Grouped whole muscle raw length‐tension curves showed no obvious form. The width of each experimental length‐tension curve was highly variable across subjects and used to predict fibre length (serial sarcomere number). After whole muscle length‐tension curves were normalized to each patient's serial sarcomere number, the whole human muscle length‐tension curve was well predicted by the sliding filament theory.

The gracilis free functioning muscle transfer is an established procedure for reconstructing elbow, wrist, and hand function in adult traumatic brachial plexus injury patients. Elbow flexion or distal wrist or hand function can be compromised by gracilis bowstringing in up to 17.8% of patients. Two techniques for pulley reconstruction to correct bowstringing and improve the function of the gracilis transfer are described.

We aimed to describe outcomes, including shoulder motion, deltoid strength and Disabilities of Arm, Shoulder and Hand scores, in 19 patients with terrible triad shoulder injuries (anterior shoulder dislocation, rotator cuff tear or greater tuberosity fracture, and axillary nerve injury) who required axillary nerve reconstruction. The type of nerve surgery (grafting vs. nerve transfer), demographic factors and injury characteristics were not significantly associated with outcomes. The mean postoperative abduction and Disabilities of Arm, Shoulder and Hand score were 95° and 28, respectively. Patients with rotator cuff tears had a higher Disabilities of Arm, Shoulder and Hand score (more disability) than those with isolated greater tuberosity fractures. We conclude that spontaneous recovery of the axillary nerve may not occur in patients with a terrible triad injury. Functional outcomes after axillary nerve repair are poor with respect to motion, strength and patient-reported outcomes compared with reported results for axillary nerve reconstruction in the absence of rotator cuff injury. Level of evidence: IV

OBJECTIVE Triceps motor branch transfer to the anterior division of the axillary nerve (AXN) was originally described for patients with a loss of deltoid function secondary to upper trunk (UT) brachial plexus injuries but has evolved to restore deltoid function in isolated peripheral AXN injuries. The purpose of this study was to compare functional outcomes in patients who had undergone this procedure in the setting of UT brachial plexus injury versus peripheral AXN injury. METHODS The records of patients who had undergone triceps branch to anterior division of the AXN transfer at a single academic institution between 2001 and 2023 were retrospectively reviewed. Patients were included in the study if they had either a UT or an AXN injury and were excluded if their follow-up was less than 2 years. Pre- and postoperative outcomes, including modified British Medical Research Council grade and range of motion, were compared between the two groups. RESULTS Forty-two patients met the criteria for inclusion. Thirty cases were classified as UT injury and 12 cases as AXN injury. The mean postoperative abduction strength was significantly higher in the AXN injury group (3.2 ± 1.5 vs 1.9 ± 1.2, p = 0.007), as was the postoperative change in abduction strength (2.8 ± 1.7 vs 1.6 ± 1.4, p = 0.01). The mean postoperative forward flexion (136° ± 57° vs 79° ± 54°, p = 0.005) and abduction (129° ± 64° vs 59° ± 47°, p = 0.004) were significantly better in the AXN group, although postoperative changes in flexion and abduction were not different between the groups. Triceps strength preoperatively was similar to that postoperatively in both groups. CONCLUSIONS Patients with an AXN injury, compared to those with a UT injury, had better postoperative abduction strength and shoulder range of motion after triceps branch transfer to the anterior division of the AXN. Triceps strength was not significantly changed after the procedure in the two groups. The study findings suggest that the outcomes of triceps branch transfer to the anterior division of the AXN are different based on the location and type of injury, providing insight into prognosis while counseling patients.