Introduction The gold standard for selecting patients for lumbar radiofrequency ablation (RFA) is medial branch block (MBB). An ideal lumbar MBB would anesthetize the targeted medial branch, with minimal to no spread to surrounding structures. Injectate spread can be affected by numerous factors, including injection volume, and location. Optimizing these factors is important to improve specificity and minimize the number of false positive responders. Capture of unintended structures is relevant as it may impact specificity of the MBB and warrants further investigation. Therefore, the objective of the current study was to perform fluoroscopic guided lumbar MBBs in cadaveric specimens and conduct meticulous dissection to assess dye spread and nerve capture rates. Materials and methods Fluoroscopy-guided contrast and dye injection (n = 20) was performed targeting lumbar MB (L1-L5). Following dye injection (0.25 mL), each specimen was meticulously dissected to expose the course of the lumbar dorsal rami branches relative to dye spread. Photographs were taken to document the extent of dye spread and structures that were stained. The capture rate was quantified and reported as a percentage. Results A total of 20 fluoroscopy-guided lumbar MBB were performed. Location of contrast flow on fluoroscopy was consistent with the location of dye spread observed in dissected specimens. Dissection post injection consistently found injectate staining all branches of the lumbar dorsal ramus. Injectate was found to spread anteriorly to the lateral aspect of the vertebral body. Conclusion Fluoroscopy guided lumbar MBB using contrast and dye were performed in anatomical specimens to assess spread and nerve capture rates. Lumbar MBB at small volumes stained all branches of the lumbar dorsal ramus suggesting it is non-selective. Further anatomical and clinical research is required.

The function of the anconeus has been previously described for the muscle as a whole. No studies were found that explored the functional neuromuscular partitioning based on 3D muscle architecture and innervation patterns, which is paramount to understanding changes in pathological muscle. The purpose of this study was to investigate 3D muscle morphology and intramuscular innervation of the anconeus, quantify architectural parameters, and propose functional implications of the findings. The fiber bundles, aponeuroses, and intramuscular innervation of the anconeus (n = 8 embalmed specimens, mean age 81 ± 12 years) were serially dissected, digitized, and modeled in 3D. Muscle morphology and intramuscular innervation patterns were determined and architectural parameters computed. The 3D models and data were used to assess muscular partitioning and propose functional implications of the findings. The anconeus was found to be morphologically partitioned into three parts, proximal, distal, and deep, based on fiber bundle orientation, attachment sites, and architectural parameters. The nerve to anconeus supplied the proximal part and underlying deep part. The nerve bifurcated to supply the distal part via medial and lateral branches or superficial and deep branches. In conclusion, the proximal part could act as an abductor of the ulna, the distal part as an initial elbow extensor, and deep part as a stabilizer and tensor of the elbow joint capsule. The in-depth 3D mapping of the anconeus will enable the development of in vivo ultrasound protocols to provide further insight into the in vivo functions of the three parts of the anconeus.

ObjectiveThe study’s primary objective was to compare the effectiveness of intra-articular platelet-rich plasma injections versus corticosteroid injections for the treatment of cervical facetogenic pain. Secondary aims were to compare self-rated disability, pain self-efficacy, and the safety of the procedure between groups.MethodsA single-site randomized double-blind controlled trial with 40 participants assigned to receive either leucocyte-poor, low-concentrate platelet-rich plasma injections or corticosteroid injection without local anesthetic into the cervical facet joint under fluoroscopy. Outcomes were collected via telephone at 1, 3, and 6 months to determine treatment effectiveness.ResultsLow-concentrate platelet-rich plasma and corticosteroid injections had similar effects on cervical facetogenic pain intensity over a 6-month period post injection as demonstrated by a non-significant group-by-time interaction for Numeric Rating Scale scores (p>0.05). However, both groups showed a statistically significant decrease in cervical facetogenic pain intensity 1 month post treatment compared with baseline (p=0.02), while the platelet-rich plasma group also demonstrated a clinically significant decrease in pain intensity at the same time point. There was a significant interaction at 1 month post intervention for pain self-efficacy (p=0.04), with the platelet-rich plasma injection group showing a larger increase in pain self-efficacy compared with the corticosteroid injection group. No significant interaction was observed for self-rated disability; however, significant reductions were shown at 3 and 6 months post treatment compared with baseline in both groups (p<0.01). No significant differences between groups were reported for adverse events; however, those receiving platelet-rich plasma injection reported significantly less procedural pain (p=0.02).ConclusionBoth platelet-rich plasma and corticosteroid injections induced similar improvements in cervical facetogenic pain intensity (1 month post) and self-rated disability (3 and 6 months post). Pain self-efficacy demonstrated a significant interaction with platelet-rich plasma injection showing greater improvement 1 month post. Additionally, both treatments exhibited a similar low prevalence of adverse events; however, those receiving platelet-rich plasma injection reported less procedural pain.

Introduction Variability in lumbar vertebral anatomy and clinical outcomes necessitate a more patient-specific approach to perform lumbar medial branch radiofrequency neurotomy (LMBRFN). To identify patient-specific fluoroscopic biomarkers, a comprehensive understanding of 3D bony anatomy and its fluoroscopic appearance is required. The objective of this first-of-its-kind pilot morphometric study was to use 3D modeling technology to evaluate these correlations and identify fluoroscopic biomarkers that may distinguish optimal parallel cannula placement for LMBRFN. Methods The lumbar vertebrae and sacra (n = 60) were photographed, reconstructed in 3D and imaged with fluoroscopy. Individual 3D model of the lumbar vertebra and sacrum were imported into Blender3D and custom code was used to simulate fluoroscopic imaging for correlational morphometric analysis with photos and radiographs. Virtual cannulae were placed parallel to the lateral necks of the superior articular processes of each 3D model to determine the cannula angle classification and identify the fluoroscopic biomarker. Results A total of 85 out of 118 simulated cannula placements (72.0%) were classified as parasagittal (<15-deg) and 33 (28.0%) were traditional (>15-deg). Qualitative analysis of the parasagittal vs traditional vertebrae found a potential differentiating fluoroscopic biomarker based on morphometric parameters. In the 85 cases of simulated cannula placement with parasagittal trajectory, 70 (82.0%) had this fluoroscopic biomarker. For the 33 cases with traditional cannula trajectory, only 10 (30.0%) had the fluoroscopic biomarker. Conclusions This morphometric analysis study demonstrates that 3D modelling with fluoroscopic imaging analysis is feasible to identify fluoroscopic biomarkers. Future clinical and morphometric studies are needed to develop robust fluoroscopic biomarkers to advance interventional pain medicine towards a personalized medicine paradigm based on a patient's specific anatomy.

BACKGROUND:Changes in architectural parameters, including alterations in contractile and connective tissue elements, can impact the plantarflexion function of the soleus muscle in gait. To date, no architectural data or quantified observations of volumetric neonatal soleus fibre bundles could be found in the literature. The purpose of this study was therefore to document the musculoaponeurotic and musculotendinous structures of the neonatal soleus muscle by employing a serial digitization-dissection and three-dimensional modelling protocol. METHODS:Both the left and right soleus of four neonatal anatomical donors were serially dissected, each muscle fibre was digitized (MicroScribe® Digitizer), and the whole volume of fibre bundles modelled in Autodesk Maya®. RESULTS:Connective tissue footprint similarities and apparent differences in architectural parameters between adult and neonatal soleus muscles, and their individual structural partitions (marginal, posterior, and anterior) were noted. Whole muscle architectural parameters for the neonatal soleus suggest that the anterior partition contributes more during force-generation, while the posterior partition has relatively greater force-generating capacity. CONCLUSIONS:This study provides the first three-dimensional, whole-volume characterization of the neonatal soleus muscle, demonstrating that its marginal, posterior, and anterior partitions are structurally and architecturally distinct at birth. These findings establish a normative baseline for neonatal soleus architecture and indicate that regional specialization for force generation and excursion is intrinsically present prior to gait, forming the foundation for subsequent postnatal functional adaptation.

Introduction Persistent pain following total knee arthroplasty (TKA) is a challenging condition to manage. Conceivably, persistent pain may be mediated by residual innervation to the subchondral bone. In the previous anatomical literature, targeting the middle two quadrants of the lateral and medial aspects of the distal femur was suggested to optimize capture of subchondral bone innervation. In this case report, we describe a modified injection protocol at the level of the epicondyle that provided pain relief for a patient with persistent post-TKA pain after failing to respond to genicular nerve diagnostic blocks at the classical target sites. Case report An 84-year-old female had right TKA in 2023 for severe osteoarthritis. The patient had right genicular nerve diagnostic blocks at the classical target sites for consideration of possible radiofrequency ablation (RFA). A 1 mL volume of contrast was injected at each location, followed by 1 mL of 0.5 % bupivacaine. The patient reported no relief from these diagnostic blocks. The patient subsequently had repeated diagnostic blocks, using a modified protocol, where two injections were performed at each of the superomedial, superolateral, and inferomedial quadrant of the knee. Following the second procedure, the patient reported 100 % pain relief for 5 hours. The patient has been scheduled for an RFA procedure. Conclusion In the current case report, a modified genicular nerve diagnostic block protocol provided pain relief for a post-TKA patient after failure of a classical injection technique. This suggests that a modified injection protocol may be necessary to select post-TKA patients for joint denervation. Future anatomical and clinical research is required.

Introduction:Recent anatomical studies have identified the sub-mammillary fossa as a potential target site to extend the length and more reliably capture the medial branch during lumbar facet joint denervation. Although a clinical case series was published describing positive outcomes targeting the sub-mammillary fossa, the ideal location for radiofrequency cannula placement has not been assessed. Further anatomical investigation of this novel technique is warranted to refine fluoroscopic landmarks for optimal placement. Methods:Twelve cannulae were placed under fluoroscopic guidance targeting the L3, L4, & L5 medial branches in 2 embalmed cadaveric specimens. Dissection, digitization, and high-fidelity 3D modelling methodology was used to identify fluoroscopic landmarks. Lesion simulation was performed on 3D models to analyze nerve capture. Results:In 5 of 12 placements (41.7 %), the medial branch capture rate was classified as "complete," as the simulated lesion overlapped with the medial branch trunk or all of its distal branches. In 4 of 12 placements (33.3 %), the nerve capture rate was "partial" with at least one distal branch found beyond the boundary of the simulated lesion. In the remaining 3 placements (25.0 %), the capture rate was classified as "none," as the medial branch trunk and all distal branches transited beyond the simulated lesion boundary. Refined fluoroscopic landmarks proposed were the lateral boundary of mammillary process (AP view); the mamillo-accessory notch/inferior boundary of facet joint line (oblique view); and the inferior aspect of the mammillary process (lateral view). Conclusions:This anatomy optimization study used dissection, imaging correlation, and high-fidelity modelling to assess cannula placement for capture of the medial branch at the sub-mammillary fossa for lumbar facet joint denervation. Based on the present analysis, refined fluoroscopic landmarks were proposed for further investigation.

Background Sensory afferents supplying subchondral bone could mediate pain from the knee joint. Intrinsic innervation originates externally and follows blood vessels through nutrient foramina. Therefore, targeting the intrinsic innervation of subchondral bone can be achieved by capturing extrinsic innervation prior to their entry into the nutrient foramina. Understanding of extrinsic innervation of the knee joint as well as the distribution of the epiphyseal nutrient foramina are important. Currently, the distribution of nutrient foramina has not been analyzed. The objective of this osteological study was to quantify the distribution of nutrient foramina in the distal femur to inform knee joint denervation strategies. Methods A convenience sample of 19 bony femurs was used in this study. The distal end of each specimen was photographed to obtain standardized lateral, medial, and anterior views. The location of nutrient foramina was documented. Each photograph was imported into ImageJ and the distribution of nutrient foramina was quantified. Results Location of epiphyseal nutrient foramina was variable on distal femur. Laterally, distribution of nutrient foramina showed percentages of 11.5 %, 44.7 %, 36.5 %, and 7.3 % in the first, second, third, and fourth quadrants, respectively. Distribution on the medial distal femur showed percentages of 12.4 %, 40.4 %, 35.5 %, and 11.5 % in the first, second, third, and fourth quadrants, respectively. Anteriorly, distribution showed a difference between the medial and lateral halves with percentages of 71.1 % and 28.9 %, respectively. Conclusions Epiphyseal nutrient foramina are important conduits that enable extrinsic innervation to enter and supply the subchondral bone. The location and distribution of the nutrient foramina of the distal femur reported in this study can be used to optimize nerve blocks and denervation techniques to manage chronic knee joint pain from osteoarthritis.

Background: Radiofrequency ablation is a common non-opioid treatment to manage chronic knee pain. The inferior medial genicular nerve is conventionally targeted. It has been suggested that the infrapatellar branch (saphenous nerve) should also be targeted. There is controversy regarding the contribution of the infrapatellar branch to the innervation of the knee joint capsule. Objective: (1) Identify the frequency of the branching pattern(s) of the infrapatellar branch in three-dimensional (3D); (2) Assess spatial relationships of branches of infrapatellar branch to the inferior medial genicular nerve; (3) Determine if capturing infrapatellar branch could result in additional benefit to the existing protocol. Design: Anatomical study. Methods: The infrapatellar branch and inferior medial genicular nerve were serially dissected, digitized, and modelled in 3D in 7 specimens (mean age 91.3 +/- 6.5; 2F/5M) and their relationship documented. The spatial relationship of the nerves was used to assess the anatomical efficacy of including the infrapatellar branch in the protocol. Results: The infrapatellar branch is most frequently a cutaneous nerve. This nerve was variable and found to be unbranched or have 2-3 branches and in all specimens was located superficial to the branches of inferior medial genicular nerve. When the infrapatellar branch (1) coursed more distally, the strip lesion would not capture the infrapatellar branch but would capture inferior medial genicular nerve consistently; (2) overlapped with the inferior medial genicular nerve, the strip lesion would capture both nerves. Conclusions: Proposed protocol targeting the infrapatellar branch is likely to capture the inferior medial genicular consistently regardless of the anatomical variation of the infrapatellar branch.

BACKGROUND:Image-guided radiofrequency ablation of the superior and inferior medial genicular nerves is used to treat medial knee pain. The infrapatellar branch (saphenous nerve) has been suggested as an additional nerve target. No studies have assessed nerve capture rates of the techniques. OBJECTIVE:To simulate four radiofrequency ablation techniques (cooled/long-axis/conventional bipolar strip lesion/dual-tined techniques) to (1) visualize the lesions in 3D relative to the treatment line and compare their extent; (2) determine and compare capture rates of the infrapatellar branch and inferior medial genicular nerve; and (3) assess which technique(s) would be most effective. DESIGN:Anatomical simulation study. METHODS:3D models were reconstructed, based on previously collected data of the dissection/digitization of 7 specimens. Four techniques were simulated with lesion sizes obtained from previously published data or manufacturer's specifications. Capture rates of the infrapatellar branch and inferior medial genicular nerve were compared and the extent of the lesion relative to the treatment line was visualized. RESULTS:The cooled monopolar technique resulted in over 50% capture rate of the superior infrapatellar branch and anterior branch of inferior medial genicular nerve. This was followed by the dual-tined monopolar technique, capturing 42.9% of superior infrapatellar branch and 57.1% of anterior branch of inferior medial genicular nerve. The simulated lesions did not always encompass the treatment line inferiorly, sparing the inferior infrapatellar branch. All techniques resulted in complete sparing of the infrapatellar branch in some specimens. CONCLUSIONS:High-fidelity lesion simulation of radiofrequency ablation techniques provides a robust anatomical foundation to inform image-guided interventions for medial knee pain.

ObjectiveLumbar medial branch denervation is commonly used to treat chronic facetogenic low back pain. Controversy exists regarding risk to adjacent neural structures. The objectives of this cadaveric study were to: (1) dissect, digitize, and model in 3D the branches of the first (L1) to fifth (L5) lumbar dorsal rami located near the junction of the transverse process and lateral neck of the superior articular process; and (2) quantify the minimal distance between the lateral/intermediate and medial branches at the anterior quarter and midpoint of the lateral neck of the superior articular process.DesignEighteen formalin-embalmed specimens were dissected, digitized and modeled in 3D. The high-fidelity 3D models were used to compare branching patterns and quantify the mean minimal distance between the lateral/intermediate and medial branches of the lumbar dorsal ramus at the anterior quarter and midpoint of the lateral neck of the superior articular process. A Two-way ANOVA was performed to determine if difference of mean distances was significant.ResultsThere was variability in the branching pattern of the lumbar dorsal rami. In 46 cases (51.1%) the lumbar dorsal ramus divided into 2 branches, in 41 cases (45.6%) into 3, and in 3 cases (3.3%) 4. The mean minimal distance between the lateral/intermediate and medial branches was significantly greater at the midpoint (3.2 ± 2.5 mm) than the anterior quarter (1.2 ± 1.8 mm) of the lateral neck of superior articular process.ConclusionMinimal distance measurements between the branches of the lumbar dorsal rami at the anterior quarter and midpoint of the lateral neck of the superior articular process were computed. When placing the distal end of the needle tip at the anterior quarter of the lateral neck of the superior articular process, the smaller mean minimal distance between the branches suggests there is a greater risk for inadvertent denervation of the lateral/intermediate branches. Further anatomical and clinical investigations are required.

OBJECTIVES:The medial sural artery (MSA) perforator flap is a versatile free flap. However, the cutaneous perforators are not well characterized. The objectives of this pilot anatomical study were to: (1) visualize in three-dimensions, as in-situ, the origin, course, and distribution of the cutaneous perforators, (2) characterize the number and frequency of the perforators, and (3) quantify mean pedicle length. METHODS:Thirteen cadaveric specimens were dissected, digitized, and modeled in 3D. Three-dimensional models and dissection photographs were used to determine the origin, course, number, distribution, and pedicle length of MSA perforators. RESULTS:The most common pattern consisted of three perforators (39% of specimens). The maximum number of perforators identified was four (23%). The majority of specimens (92%) had a cutaneous perforator originating from the lateral branch of the MSA and coursed most frequently in the second (43%) and third (37%) quartiles of the length of the tibia. Mean pedicle length was 19.1 ± 6.9 cm. Perforators originating from the medial branch of the MSA were significantly (p < 0.05) shorter than those from the lateral branch and were found to course only in the first quartile. CONCLUSION:The 3D models constructed in this study provide a comprehensive overview of the location and course of the perforators, enabling measurement of parameters in 3D-space. Anatomical characterization of the MSA perforator flap using 3D analysis can assist reconstructive surgeons in understanding the relevant anatomy and optimizing the surgical technique for flap harvest. LEVEL OF EVIDENCE:N/A Laryngoscope, 134:4298-4303, 2024.

Radiofrequency denervation of lumbar medial branches is a viable treatment option to manage chronic facetogenic low back pain. Traditionally, lumbar medial branch denervation involves placement of the electrode's active tip at a 20-degree angulation away from the parasagittal plane. However, more recent anatomical studies have provided evidence supporting the feasibility of an alternative parasagittal approach targeting the posterior half of the lateral neck of the superior articular process to capture the lumbar medial branches. Currently, there is a lack of clinical data on the effectiveness of the alternative parasagittal needle placement technique. Therefore, in this brief technical report, the parasagittal needle placement technique and the pain relief outcomes in four consecutive patients following treatment with the parasagittal approach are described.

Background Lumbar medial branch (MB) radiofrequency ablation is a common intervention to treat facetogenic low back pain. The consensus among spine pain interventionalists is that capturing a greater length of the MB correlates with a longer duration of pain relief. Therefore, there has been interest in defining optimal needle angles to achieve parallel cannula placement. Presently, there is inconsistency regarding the optimal caudal needle angles. Objectives The objectives of this study were to: 1) use a dissection-based 3D modelling methodology to quantify optimal caudal needle angles from cadaveric models; and 2) compare optimal cadaver-derived caudal needle angles with real-world patient-derived needle angles. Methods Eighteen formalin embalmed lumbosacral spine specimens were dissected, digitized, and modelled in 3D. Virtual needles were simulated and placed parallel with the L1-L5 MBs. Cadaver-derived caudal needle angles were measured from the high-fidelity 3D models with optimally placed virtual needles. Lateral fluoroscopic images of patients (n = 200) that received lumbar MB denervation were reviewed to measure patient-derived caudal needle angles (L3-L5 MB levels). Descriptive statistics were used to analyze the cadaver (L1-L5 MB levels) and patient-derived (L3-L5 MB levels) caudal needle angles. The cadaver and patient-derived mean caudal needle angles for L3-L5 MB levels were compared. Results There was variability in the cadaver-derived mean caudal needle angles. The lowest mean caudal needle angle was the L1 MB level measured at 41.57 ± 8.56° (range: 27.14° - 53.96°). The highest was the L5 MB level with a mean caudal needle angle of 60.79 ± 8.55° (range: 46.97° - 79.74°). A total of 123 patients were included and 369 caudal needle angles (L3-L5 MB levels) were measured and analyzed. There was variability in the patient-derived mean caudal needle angles. The patient-derived mean caudal needle angles were 29.18 ± 8.77° (range: 11.80° - 61.31°), 33.34 ± 7.23° (range: 16.40° - 54.15°), and 49.08 ± 8.87° (range: 26.45° - 76.95°) for the L3, L4, and L5 MB levels, respectively. There was a significant difference in mean caudal needle angle between cadaver and patient-derived needle angles at the L3, L4, and L5 MB levels. Conclusions Analysis of cadaver-derived needle angles versus patient-derived data suggests optimization of lumbar MB denervation requires greater caudal angulation to achieve parallel needle placement. Further research is required to assess the clinical implications.

INTRODUCTION:Osteoarthritis (OA) of the thumb carpometacarpal (CMC) joint is a common disorder that negatively impacts hand function. Denervation of the thumb CMC joint has emerged as a viable treatment option. However, the innervation pattern of the thumb CMC joint is controversial. Therefore, the objective of this study was to identify the articular branches supplying the thumb CMC joint and to document their relationship to anatomical landmarks to provide the foundation for image-guided diagnostic block and denervation procedures. METHODS:In 10 formalin-embalmed upper limb specimens articular branches supplying the thumb CMC joint were dissected from their origin to termination. A frequency map documenting the number of articular branches was generated. The frequency map enabled visualization and comparison of the relative area of innervation of the thumb CMC joint by each articular branch. RESULTS:The thumb CMC joint received innervation from six nerves. These were the deep branch of ulnar nerve (DBUN), dorsal articular nerve (DAN) of the first interosseus space, thenar branch of median nerve (TBMN), palmar cutaneous branch of median nerve (PCBMN), lateral antebrachial cutaneous nerve (LACN) and superficial branch of the radial nerve (SBRN) and/or their branches. Each nerve was found to innervate different aspects of the joint. The DBUN and DAN were found to innervate the posteromedial aspect of the thumb CMC joint, the TBMN and PCBMN anterior/anteromedial aspects, LACN posterolateral/lateral/anterior aspects and SBRN posterolateral/anterolateral aspects. CONCLUSIONS:The thumb CMC joint was innervated by articular branches originating from the SBRN, DAN, LACN, PCBMN, TBMN and DBUN. The documented anatomical relationships provide the foundation to inform selective diagnostic block and denervation of the thumb CMC joint. Further investigations are needed to assess the clinical implications of the current study.