Shoulder terminal sensory articular nerve radiofrequency ablation for non-surgical refractory shoulder pain due to rotator cuff pathology and osteoarthritis: A technical note.

BACKGROUND: Given the high prevalence of chronic shoulder pain and encouraging early results of terminal sensory articular branch (TSAB) radiofrequency ablation to treat shoulder pain, research is warranted to refine the procedural technique based on updated neuroanatomical knowledge with the goal of further improving patient outcomes. OBJECTIVE: We describe an updated radiofrequency ablation protocol that accounts for varied locations of the TSABs of suprascapular, axillary, subscapular and lateral pectoral nerves within individual patients. DESIGN: Technical note. METHODS: Cadaveric studies delineating the sensory innervation of the shoulder joint were reviewed, and a more comprehensive radiofrequency ablation (RFA) protocol is proposed relative to historical descriptions. CONCLUSIONS: Based on neuroanatomical dissections of the shoulder joint, the proposed RFA protocol will provide a safe means of more complete sensory denervation and potentially improve clinical outcomes compared to historical descriptions, which must be confirmed in prospective studies.

The effectiveness of intradiscal corticosteroid injection for the treatment of chronic discovertebral low back pain: a systematic review.

OBJECTIVE: Determine the effectiveness of intradiscal corticosteroid injection (IDCI) for the treatment of discovertebral low back pain. DESIGN: Systematic review. POPULATION: Adults with chronic low back pain attributed to disc or vertebral end plate pain, as evidenced by positive provocation discography or Modic 1 or 2 changes on magnetic resonance imaging. INTERVENTION: Fluoroscopically guided or computed tomography-guided IDCI. COMPARISON: Sham/placebo procedure including intradiscal saline, anesthetic, discography alone, or other active treatment. OUTCOMES: Reduction in chronic low back pain reported on a visual analog scale or numeric rating scale and reduction in disability reported by a validated scale such as the Oswestry Disability Index. METHODS: Four reviewers independently assessed articles published before January 31, 2023, in Medline, Embase, CENTRAL, and CINAHL. The quality of evidence was evaluated with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework. The risk of bias in randomized trials was evaluated with the Cochrane Risk of Bias tool (version 2). RESULTS: Of the 7806 unique records screened, 6 randomized controlled trials featuring 603 total participants ultimately met the inclusion criteria. In multiple randomized controlled trials, IDCI was found to reduce pain and disability for 1-6 months in those with Modic 1 and 2 changes but not in those selected by provocation discography. CONCLUSION: According to GRADE, there is low-quality evidence that IDCI reduces pain and disability for up to 6 months in individuals with chronic discovertebral low back pain as evidenced by Modic 1 and 2 changes but not in individuals selected by provocation discography. STUDY REGISTRATION: PROSPERO (CRD42021287421).

A pragmatic randomized prospective trial of cooled radiofrequency ablation of the medial branch nerves versus facet joint injection of corticosteroid for the treatment of lumbar facet syndrome: 12 month outcomes.

BACKGROUND: Lumbar medial branch radiofrequency ablation (LRFA) and intraarticular facet steroid injections (FJI) are commonly performed for recalcitrant facet joint-mediated pain. However, no study has compared clinical outcomes of the two treatments in patients selected using dual medial branch blocks (MBBs) with an 80% relief threshold. OBJECTIVE: Compare the effectiveness of cooled LRFA (C-LRFA) to FIJ as assessed by pain and functional improvements. DESIGN: Prospective randomized comparative trial. METHODS: Patients with dual MBB-confirmed facet joint-mediated pain were randomized to receive C-LRFA or FIJ. Outcomes were assessed at 1, 3, 6, and 12 months. The primary outcome was ≥50% improvement in numerical pain rating scale (NPRS) score at 3 months. Secondary outcomes included ≥30% Oswestry Disability Index (ODI) improvement and Patient Global Impression of Chance (PGIC) ≥6 points, among others. Data were analyzed using contingency tables and mixed-effects logistic regression models. RESULTS: Of 1128 patients screened, 32 met eligibility criteria, were randomized, and received their allocated study treatment. In total, 20 (62.5%) and 12 (37.5%) participants received C-LRFA and FIJ, respectively. In the C-LRFA group, 70% (95% CI 48-85), 55% (95% CI 34-74), and 45% (95% CI 26-66) of participants met the NPRS responder definition, compared to 25% (95%CI 9-53), 25% (95% CI 9-53), and 17% (95% CI 5-45) in the FJI group at 3, 6, and 12 months, respectively (P = .014 at 3 months). The PGIC responder proportion was higher in the C-LRFA compared to FJI group at 3 and 6 months (P < .05). CONCLUSIONS: C-LRFA demonstrated superior success rates compared to FJI across pain and functional outcome domains. TRIAL REGISTRATION DETAILS: ClinicalTrials.gov (NCT03614793); August 3, 2018.

Great power comes at a high (locomotor) cost: the role of muscle fascicle length in the power versus economy performance trade-off.

Muscle design constraints preclude simultaneous specialization of the vertebrate locomotor system for explosive and economical force generation. The resulting performance trade-off between power and economy has been attributed primarily to individual differences in muscle fiber type composition. While certainly crucial for performance specialization, fiber type likely interacts with muscle architectural parameters, such as fascicle length, to produce this trade-off. Longer fascicles composed of more serial sarcomeres can achieve faster shortening velocities, allowing for greater power production. Long fascicles likely reduce economy, however, because more energy-consuming contractile units are activated for a given force production. We hypothesized that longer fascicles are associated with both increased power production and locomotor cost. In 11 power-trained and 13 endurance-trained recreational athletes, we measured (1) muscle fascicle length via ultrasound in the gastrocnemius lateralis, gastrocnemius medialis and vastus lateralis, (2) maximal power during cycling and countermovement jumps, and (3) running cost of transport. We estimated muscle fiber type non-invasively based on the pedaling rate at which maximal cycling power occurred. As predicted, longer gastrocnemius muscle fascicles were correlated with greater lower-body power production and cost of transport. Multiple regression analyses revealed that variability in maximal power was explained by fiber type (46% for cycling, 24% for jumping) and average fascicle length (20% for cycling, 13% for jumping), while average fascicle length accounted for 15% of the variation in cost of transport. These results suggest that, at least for certain muscles, fascicle length plays an important role in the power versus economy performance trade-off.

Musculoskeletal mass and shape are correlated with competitive ability in male house mice (Mus musculus).

Intense physical competition between males for mating opportunities is widespread among mammals. In such agonistic encounters, males with combinations of morphological, physiological and behavioral characters that allow them to dominate an opponent have greater fitness. However, the specific physical traits associated with competitive ability are poorly understood. Larger body size is often correlated with fitness in mammals. Interestingly, fitness is maximized at intermediate body masses in male house mice (Mus musculus), a species with a polygynous mating system in which males compete physically for access to reproductive resources. Here, we used competition trials in semi-natural, mixed-sex population enclosures to directly measure competitive ability in male house mice based on control of a preferred nesting site. We tested the hypothesis that the musculoskeletal systems of male mice demonstrating high competitive ability are more specialized for competition by comparing the masses of 10 major muscle groups and eight bones as well as a set of 12 skeletal shape indices associated with anatomical specialization for fighting performance in a set of nine winners and 20 losers. Winning males possessed several traits hypothesized to enhance performance in male-male contests: relatively greater mass in several muscle groups and bones of the forelimb and hindlimb and larger scapular surface area. Unexpectedly, no measurements of the head and neck differed significantly between winners and losers. These results identify musculoskeletal traits associated with competitive ability in male house mice and suggest that our current understanding of mammalian fighting performance is incomplete and more nuanced than previously considered.