Morphology of the Radial Attachment of the Radioulnar Ligament and Surrounding Landmarks.

PURPOSE: The triangular fibrocartilage complex (TFCC) is composed of dorsal and palmar radioulnar ligaments (RULs). A common injury pattern of the RUL is the avulsion of the ulnar insertion, which can be treated by arthroscopic or open repair. Although the general method of TFCC reconstruction is a tendon graft with a bone tunnel, detailed information regarding the radial attachment of the RUL is unclear. This study aimed to clarify the morphology of the radial attachments of the palmar radioulnar ligament (PRUL), dorsal radioulnar ligament (DRUL), and short radiolunate ligament (SRL) using three-dimensional imaging. METHODS: A total of 29 upper limbs (16 formalin-fixed and 13 embalmed by Thiel's embalming method) of Japanese cadavers were used. After gross observation, we marked the attachments of the PRUL, DRUL, and SRL using 0.7-mm diameter pins. We created three-dimensional images of the radius, outlining the PRUL, DRUL, and SRL attachments. The software application calculated the centers of the PRUL and DRUL attachments. RESULTS: The PRUL attachment was horizontally shaped. The center of the PRUL was 1.5 mm proximal and 5.8 mm radial to the tip of the palmar pyramid formed by the palmar cortex and the radioulnar and radiocarpal joint surfaces. The DRUL attachment was vertically shaped. The center of the DRUL was 2.0 mm proximal and 1.7 mm radial from the tip of the dorsal pyramid formed by the dorsal cortex and the radioulnar and radiocarpal joint surfaces. The length of the SRL was 9.2 mm. The SRL and PRUL were strongly conjoined. CONCLUSIONS: The anatomical center on the RUL attachment of the radius can be determined from osseous landmarks. CLINICAL RELEVANCE: The findings of this study contribute to the understanding of RUL attachment to the distal radius and may assist surgeons in performing anatomical reconstruction of TFCC.

Load Distribution in Dorsally-Angulated Distal Radius Deformity Using Finite Element Analysis.

PURPOSE: The load axis of the carpals is located on the volar side of the normal distal radius. A volar lunate facet fracture (VLFF) is exposed to volar-shearing stress, which can cause volar displacement of the carpus. A previous biomechanical study reported that the load at the scaphoid fossa was located more dorsally and the pressure at the lunate fossa decreased in a dorsally-angulated model. However, the distal radius load distribution for various volar tilts remains unclear. We speculate that if the volar tilt decreases, the load distribution moves dorsally and decreases the stress on the VLFF. Therefore, we analyzed a dorsally-angulated distal radius model to evaluate changes in the load distribution using finite element analysis. METHODS: A 3-dimensional finite element wrist model was developed using computed tomography images. The ligaments were modeled as tension-only spring elements. We considered the intact wrist model for a volar tilt of 15° and created 5 additional models for volar tilts of 10°, 5°, 0°, -5°, and -10°. RESULTS: As the dorsal angulation increased, the stress distribution moved from volar to dorsal and from the lunate fossa toward the scaphoid fossa. The maximum stress on the volar lunate facet was reduced as volar tilt decreased. The maximum stress was higher on the lunate fossa for volar tilts from 15° to 5°. In contrast, the maximum stress was higher on the scaphoid fossa for volar tilts of ≤0°. CONCLUSIONS: Load transmission moved from volar to dorsal and from the lunate fossa to the scaphoid fossa when the volar tilt decreased. Therefore, a decrease in the volar tilt would reduce the load on the VLFF. CLINICAL RELEVANCE: This study provides surgeons accurate knowledge regarding load distribution of the distal radius for various volar tilts that could be helpful in treating patients with VLFFs.

Cytokine Inhibitors Upregulate Extracellular Matrix Anabolism of Human Intervertebral Discs under Alginate Beads and Alginate-Embedded Explant Cultures.

We investigated the effects of the cytokine inhibitors IL-1 receptor antagonist (IL-1Ra) and soluble tumor necrosis factor receptor-1 (sTNFR1) on the extracellular matrix metabolism of human intervertebral discs (IVDs) and the roles of IL-1ß and TNF in the homeostasis of IVD cells. The 1.2% alginate beads and the explants obtained from 35 human lumbar discs were treated with cytokine inhibitors. Extracellular matrix metabolism was evaluated by proteoglycan (PG) and collagen syntheses and IL-1ß, TNF, and IL-6 expressions after three days of culture in the presence or absence of IL-1Ra, sTNFR1, and cycloheximide. Simultaneous treatment with IL-1Ra and sTNFR1 stimulated PG and collagen syntheses in the NP and AF cells and explants. The IL-1ß concentration was significantly correlated to the relative increase in PG synthesis in AF explants after simultaneous cytokine inhibitor treatment. The relative increase in PG synthesis induced by simultaneous cytokine treatment was significantly higher in an advanced grade of MRI. Expressions of IL-1ß and TNF were upregulated by each cytokine inhibitor, and simultaneous treatment suppressed IL-1ß and TNF productions. In conclusion, IL-1Ra and sTNFR1 have the potential to increase PG and collagen synthesis in IVDs. IL-1ß and TNF have a feedback pathway to maintain optimal expression, resulting in the control of homeostasis in IVD explants.

Radiographic changes in the distal ulna in non-rheumatoid patients with extensor digitorum communis ruptures.

INTRODUCTION: Osteoarthritis of the distal radioulnar joint (DRUJ) is relatively common in elderly people. Extensor digitorum communis (EDC) ruptures occasionally and occurs with or without prior signs in these people. The purpose of this study was to clarify the radiographic changes in the distal ulna associated with EDC rupture. MATERIALS AND METHODS: We analyzed plain radiographs of 71 patients with non-rheumatoid arthritis and 40 controls. Radiographic changes in the distal ulna were categorized into normal, osteoarthritic-change (OA-change), and taper. We measured the ulnar variance (UV) and ulnar bowing angle in the posteroanterior radiographs and the dorsal bowing angle (DBA) and dorsal protrusion (DP) in the lateral radiographs. The shape of the sigmoid notch (SN) was categorized into flat, radial inclination, and dimple. The primary outcome was a comparison of radiographic parameters between the patient and the control groups. The secondary outcome was an analysis of the type of SN to investigate factors affecting ulnar deformation. RESULTS: The ratio of the radiographic change in the ulna, UV, DBA, and DP was significantly larger in the patient group than in the control group. Patients with the radial inclination type of SN showed a greater UV than those with the dimple type. CONCLUSIONS: Deformation of the distal ulna, a large UV, dorsal penetration, and dorsal bowing was related to EDC rupture. Regarding the large UV, the lunate shaved the upper half of the distal ulna, whereas the DRUJ shaved the lower half. These processes formed a tapered ulna head. A large UV and an inclination of the DRUJ played a role in ulnar head deformation.

Radiographic study of the distal ulna in rheumatoid arthritis with extensor digitorum communis ruptures.

OBJECTIVES: Extensor digitorum communis rupture of the wrist often occurs in patients with rheumatoid arthritis. Early operation is desirable for patients with a high risk of rupture; therefore, rheumatologists should diagnose it during daily examinations. This study aimed to clarify radiographic changes in the distal ulna and related factors associated with extensor digitorum communis rupture in patients with rheumatoid arthritis. METHODS: We analysed plain radiographs of 40 patients with rheumatoid arthritis associated with extensor digitorum communis rupture and 62 healthy controls. We investigated the deformation of the distal ulna, Larsen grades, and radiological parameters such as ulnar variance, ulnar bowing angle, dorsal protrusion, and dorsal bowing angle. RESULTS: The ratios of the ulna head deformation, Larsen grades, ulnar variance, dorsal protrusion, and dorsal bowing angle were significantly larger in the ruptured group than in the control group. Multiple logistic regression analysis revealed that dorsal protrusion and Larsen grades were significantly associated with extensor digitorum communis rupture. CONCLUSIONS: Deformity of the distal ulna is evident in patients with an extensor digitorum communis rupture. Ulnar head deformation, high Larsen grades, and large dorsal protrusion are potential risk factors for extensor digitorum communis rupture.

Morphology of the Ulnar Insertion of the Triangular Fibrocartilage Complex and Related Osseous Landmarks.

PURPOSE: In triangular fibrocartilage complex (TFCC) injuries, a foveal tear of the radioulnar ligament often requires surgery. Previous studies have suggested that surgeons should attach the TFCC to the center of the fovea. The TFCC and its insertion points are small structures, and few studies have reported details of the foveal insertion. This study aimed to clarify the morphology of the ulnar insertion of the TFCC and related osseous landmarks with 3-dimensional imaging. METHODS: This study used 26 formalin-fixed cadavers. At the ulna, the TFCC was inserted from the fovea to the middle part of the ulnar styloid. After gross observation of the TFCC, the ulnar insertion was outlined using a 1.0-mm drill. We then created 3-dimensional images of the ulna using computed tomography and marked (with software) an outline of the foveal insertion of the TFCC. We measured the area and the long and short diameters of the TFCC insertion. RESULTS: The area of the TFCC insertion was 34 mm2 and positively correlated with the height of the ulnar styloid and the area of the ulnar head. The TFCC's highest point was 58% of the ulnar styloid height. The center of the TFCC insertion was 1.3 mm ulnar and 0.6 mm dorsal from the lowest point of the ulnar surface. CONCLUSIONS: The center of the TFCC insertion was slightly ulnar of the lowest point of the ulnar surface. This study revealed the center, the area, and the osseous relation of the ulnar insertion of the TFCC. CLINICAL RELEVANCE: When surgeons repair a TFCC foveal tear, they can find the anatomical center of the ulnar insertion efficiently and easily based on its osseous relationship.

Three-dimensional computed tomography confirmed that the meniscal root attachments and meniscofemoral ligaments are morphologically consistent.

PURPOSE: To clarify the characteristic features of the meniscal root attachments, meniscofemoral ligaments (MFLs), and related osseous landmarks on three-dimensional images using computed tomography. METHODS: Twenty-eight non-paired, formalin-fixed human cadaveric knees were evaluated in this study. The meniscal root attachments were identified and marked. Three-dimensional images were obtained after applying a contrast agent to the entire meniscal surfaces and MFLs, then the morphology of the meniscal root attachments and MFLs, and their positional relationships with osseous landmarks, were analyzed. RESULTS: Parsons' knob divided the medial meniscal anterior root attachment and lateral meniscal anterior root attachment on the anterior portion of the tibial plateau. The medial meniscal posterior root attachment was near the medial intercondylar tubercle. The lateral meniscal posterior root attachment (LMPRA) was closer to the lateral intercondylar tubercle. Both root attachments were near the posterior intercondylar fossa. The positional relationships between the meniscal root attachments and related osseous landmarks were consistent in all specimens. The MFLs originated from the lateral meniscus posterior horn, and the anterior MFL was closer to the LMPRA than the posterior MFL. The posterior MFL originated at approximately the midpoint between the LMPRA and the most posterior margin of the lateral meniscus. CONCLUSION: This study showed that the relationships between the characteristic features of the meniscal root attachments, MFLs, and related osseous landmarks were consistent. The clinical relevance of this study is that it improved understanding of the anatomy of the meniscal root attachments and MFLs.

Hyperactivation of Nrf2 leads to hypoplasia of bone in vivo.

Keap1 is a negative regulator of Nrf2, a master transcription factor that regulates cytoprotection against oxidative and electrophilic stresses. Although several studies have suggested that the Keap1-Nrf2 system contributes to bone formation besides the maintenance of redox homeostasis, how Nrf2 hyperactivation by Keap1 deficiency affects the bone formation remains to be explored, as the Keap1-null mice are juvenile lethal. To overcome this problem, we used viable Keap1-deficient mice that we have generated by deleting the esophageal Nrf2 in Keap1-null mice (NEKO mice). We found that the NEKO mice exhibit small body size and low bone density. Although nephrogenic diabetes insipidus has been observed in both the NEKO mice and renal-specific Keap1-deficient mice, the skeletal phenotypes are not recapitulated in the renal-specific Keap1-deficient mice, suggesting that the skeletal phenotype by Nrf2 hyperactivation is not related to the renal phenotype. Experiments with primary culture cells derived from Keap1-null mice showed that differentiation of both osteoclasts and osteoblasts was attenuated, showing that impaired differentiation of osteoblasts rather than osteoclasts is responsible for bone hypoplasia caused by Nrf2 hyperactivation. Thus, we propose that the appropriate control of Nrf2 activity by Keap1 is essential for maintaining bone homeostasis.

Volar locking plates not touching the flexor pollicis longus tendon appear as prominences on radiographs: a cadaver study.

BACKGROUND: Plate protrusion is a risk factor for flexor pollicis longus (FPL) rupture following volar locking plate (VLP) surgery. However, plate prominence on follow-up radiographs is common. We hypothesised that a VLP that does not touch the FPL tendon can appear as a plate prominence projected over the volar ridge on lateral radiographs. MATERIALS AND METHODS: We studied six current designs of widely used plates in formalin-fixed cadavers. Each plate was placed in six cadavers. We analysed 36 different plate-cadaver combinations. The main aim of plate fixation was to position the plate in the most distal position without FPL tendon contact. Radiographs were obtained using fluoroscopy. We evaluated plate prominence from the volar ridge according to the Soong grading system. RESULTS: Soong grades 0 (plate did not extend beyond volar ridge), 1 (plate protruded beyond volar ridge) and 2 (plate directly on or located beyond the volar ridge) were observed in 23 (63.9%), 9 (25.0%) and 4 (11.1%) cadavers, respectively. VariAx, DVR and VALCP showed grade 1 prominence, whereas Acu-Loc2, HYBRIX and MODE showed grade 2 prominence. CONCLUSIONS: Implant protrusion was observed in 36% of plate-cadaver combinations, even if the plate did not touch the FPL. Estimating the risk of FPL rupture using lateral radiographs alone is likely insufficient. Our findings can be applied to accurately identify the presence of implant prominence following VLP surgery.

Importance of latissimus dorsi muscle preservation for shoulder function after scapulectomy.

BACKGROUND: Scapulectomy is an inevitable treatment for sarcomas of the scapula. This procedure is unavoidable because it reduces the local recurrence rate but can impair shoulder movements and affect the activities of daily living. This study investigated the factors influencing functional outcomes after scapulectomy. MATERIALS AND METHODS: The clinical results of 8 patients (5 males, 3 females) who were diagnosed with primary or metastatic sarcomas of the scapula were retrospectively reviewed. The mean age was 49 years (range, 11-86 years). We examined the correlation between the type of excision of the scapula (total, subtotal, or partial) and postoperative functional outcomes according to the Musculoskeletal Tumor Society (MSTS) score. In partial excision, the glenohumeral joint was preserved; in subtotal excision, the glenoid was completely resected and some bony components were preserved; and in total excision, the entire bony component of the scapula was resected. The average follow-up period was 55 months (range, 9-142 months). RESULTS: The partial, subtotal, and total excision groups had mean functional scores of 96.7%, 76.7%, and 62.2%, respectively. Although the mean functional scores were lower in patients who underwent total and subtotal excisions, 3 patients in whom the latissimus dorsi muscle was preserved had better function (mean MSTS score, 76.7%) than the 2 patients in whom it was not preserved (mean MSTS score, 55.0%). CONCLUSION: These results suggest that the latissimus dorsi muscle, along with the deltoid and pectoralis major muscles, is one of the stabilizers of the proximal humerus after scapulectomy.

Morphology of the Insertions of the Superficial Medial Collateral Ligament and Posterior Oblique Ligament Using 3-Dimensional Computed Tomography: A Cadaveric Study.

PURPOSE: To describe the insertions of the superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL) and their related osseous landmarks. METHODS: Insertions of the sMCL and POL were identified and marked in 22 unpaired human cadaveric knees. The surface area, location, positional relations, and morphology of the sMCL and POL insertions and related osseous structures were analyzed on 3-dimensional images. RESULTS: The femoral insertion of the POL was located 18.3 mm distal to the apex of the adductor tubercle (AT). The femoral insertion of the sMCL was located 21.1 mm distal to the AT and 9.2 mm anterior to the POL. The angle between the femoral axis and femoral insertion of the sMCL was 18.6°, and that between the femoral axis and the POL insertion was 5.1°. The anterior portions of the distal fibers of the POL were attached to the fascia cruris and semimembranosus tendon, whereas the posterior fibers were attached to the posteromedial side of the tibia directly. The tibial insertion of the POL was located just proximal and medial to the superior edge of the semimembranosus groove. The tibial insertion of the sMCL was attached firmly and widely to the tibial crest. The mean linear distances between the tibial insertion of the POL or sMCL and joint line were 5.8 and 49.6 mm, respectively. CONCLUSIONS: This study used 3-dimensional images to assess the insertions of the sMCL and POL and their related osseous landmarks. The AT was identified clearly as an osseous landmark of the femoral insertions of the sMCL and POL. The tibial crest and semimembranosus groove served as osseous landmarks of the tibial insertions of the sMCL and POL. CLINICAL RELEVANCE: By showing further details of the anatomy of the knee, the described findings can assist surgeons in anatomic reconstruction of the sMCL and POL.

Morphology of the fibular insertion of the posterolateral corner and biceps femoris tendon.

PURPOSE: To clarify the fibular head insertion of the fibular collateral ligament (FCL), popliteofibular ligament (PFL), and biceps femoris tendon and related osseous landmarks on three-dimensional (3-D) images. METHODS: Twenty-one non-paired, formalin-fixed human cadaveric knees were evaluated in this study. The fibular head insertions of the FCL, PFL and biceps femoris tendon were identified and marked. 3-D images were created, and the surface area, location, positional relationships, and morphology of the fibular insertions of the FCL, PFL, and biceps femoris tendon and related osseous structures were analysed. RESULTS: The fibular head had a unique pyramidal shape, and the relationships of the fibular insertion of the FCL, PFL, and biceps femoris tendon were consistent. The fibular head consists of three aspects: lateral aspect, posterior aspect, and proximal tibiofibular facet. The insertions of the FCL, PFL, and biceps femoris tendon were attached to the centre from the distal side of the lateral aspects of the fibular head, posterior aspect of the fibular styloid process, and lateral aspect surrounding the FCL, respectively. The mean surface areas of the FCL and PFL fibular insertions were 100.1 ± 29.5 and 18.5 ± 7.2 mm2, respectively. CONCLUSION: This study showed that the relationships between the characteristic features of the fibular head and insertions of the FCL, PFL, and biceps femoris tendon were consistent. The clinical relevance of this study is that it improves understanding of the anatomy of the insertions of the PLC and biceps femoris tendon.

Morphology of insertion sites on patellar side of medial patellofemoral ligament.

PURPOSE: The purpose of this study was to clarify the insertion sites on the patellar side of the medial patellofemoral ligament (MPFL). METHODS: A total of 35 nonpaired human cadaveric knees were used in this study. After identification of the MPFL, the insertion sites on the patellar side of the MPFL were marked. Three-dimensional images were created, and the location and morphology of these insertion sites were analysed. RESULTS: The morphology of the insertion sites on the patellar side of the MPFL was consistent. The proximal fibres of the MPFL were inserted to the deep fascia of the vastus medialis obliquus (VMO) and medial margin of the vastus intermedius (VI). The distal fibres of the MPFL were inserted to the medial margin of the patella directly. The insertion lengths of the VMO, VI, and patella were 26.7 ± 5.0, 28.5 ± 4.4, and 18.5 ± 4.4 mm, respectively. The rate of the vertical distance from the superior pole of the patella to the superior edge of the MPFL in relation to the total patellar height was 12 ± 4.4 %. At the distal edge, the rate was 58 ± 9.6 %. CONCLUSION: The insertion sites on the patellar side of the MPFL were consistent. The MPFL inserted into the VMO and VI was significantly longer than into the patella. The clinical relevance of this study is to improve understanding of the anatomy of the insertion sites on the patellar side of the MPFL and the pathophysiology of patellar dislocation.

Morphology of the femoral insertion of the lateral collateral ligament and popliteus tendon.

PURPOSE: To clarify the femoral insertion of the lateral collateral ligament (LCL) and popliteus tendon (PT) and related osseous landmarks on three-dimensional images. METHODS: Twenty-six non-paired, formalin-fixed human cadaveric knees were evaluated in this study. Femoral insertion of the LCL and PT was identified and marked. Three-dimensional images were created, and the surface area, location, positional relationships, and morphology of the femoral insertion of the LCL, PT, and related osseous structures were analysed. RESULTS: The mean surface areas of the LCL and PT femoral insertions were 55.8 ± 25.0 and 52.5 ± 24.2 mm(2), respectively. Variations in the positional relationships between the LCL and PT insertions (PT inserted parallel and posterior to the LCL insertion to the long axis of the femur) were observed. The lateral epicondyle and popliteal sulcus could be clearly identified as osseous landmarks on three-dimensional images in all knees. Most of the LCL was inserted postero-distal to the apex of the lateral epicondyle, and the PT was inserted at the anterior end of the popliteal sulcus in all knees. CONCLUSION: We observed variation in the positional relationship between the femoral insertion of the LCL and PT. However, the relationships between their insertions and osseous landmarks were consistent. The findings of this study contribute to the understanding of the PLC osseous anatomy and should assist surgeons in performing PLC surgery with a more anatomic perspective.

Glenohumeral arthrodesis for malignant tumor of the shoulder girdle.

BACKGROUND: Arthrodesis of the shoulder joint using a free vascularized fibular graft has been performed as a reconstruction method after resection of bone sarcoma in the shoulder girdle. Postoperative fractures occasionally occur as a complication of arthrodesis of the shoulder joint using single-bone fusion (the conventional method). We hypothesized that the clinical results of shoulder arthrodesis using a double-barrel vascularized fibula graft for the malignant tumor of the shoulder girdle would achieve superior results compared with the conventional single-bone fusion method. METHODS: The clinical results of 5 patients with a malignant bone and soft tissue tumor of the shoulder girdle were retrospectively reviewed. The factors evaluated were surgical margins, reconstruction procedures, postoperative complications, local recurrences, metastasis in lymph nodes or lung, or both, survival, and functional results assessed by the Musculoskeletal Tumor Society (MSTS) score. After surgical resection, arthrodesis of the shoulder joint was performed using a free vascularized fibula graft as a reconstructive procedure for the bone defect. Arthrodesis was by single-bone fusion in 3 of 5 patients, and a double-barrel vascularized fibula graft (dual-bone fusion) was used in 2 patients. RESULTS: The average MSTS scores were 58.3% in the group with single-bone fusion and 85.0% in the group with dual-bone fusion. CONCLUSION: The use of a double-barrel vascularized fibular graft may be useful in the reconstruction of large bone defects after wide excision of malignant tumors of the proximal humerus, with the advantage of avoiding postoperative fractures in shoulder arthrodesis.

Morphology of the popliteomeniscal fascicles around the popliteal hiatus on three-dimensional images reconstructed from 7 T magnetic resonance imaging: A cadaveric study.

BACKGROUND: This study aimed to clarify the characteristic features of the anteroinferior and posterosuperior popliteomeniscal fascicles (aiPMF and psPMF, respectively) and popliteal hiatus using three-dimensional (3D) reconstructions of 7 T magnetic resonance imaging (MRI) arthrography. METHODS: Six knees from human cadavers fixed using the Thiel embalming method were examined using 7 T MRI arthrography. 3D Images of the structures around the popliteal hiatus were reconstructed. Morphologies of the psPMF, aiPMF, and popliteal hiatus were investigated and their positional relationships analyzed. RESULTS: The PMFs attached to the periphery of the lateral meniscus (LM) to form the popliteal hiatus. Each coursed in an oblique direction. The mean length of the psPMF and aiPMF attachments to the LM were 6.8 and 21.6 mm, respectively; mean popliteal hiatus length was 12.8 mm. These lengths corresponded to 7.5%, 24.3%, and 14.5% of the total length of the LM, respectively. The aiPMF was thick near the lateral aspect of the articular capsule and became thinner towards the posteromedial aspect of the LM. The psPMF was thick near the posterior aspect of the articular capsule and became thinner towards the posterolateral aspect of the LM. CONCLUSION: Morphological properties of the aiPMF, psPMF, their attachments to the LM, and the popliteal hiatus were consistent across the cadaver specimens examined. Each PMF was thin near the popliteal hiatus and became thicker towards its attachment to the articular capsule. These findings may be useful for anatomical repair for the LM hypermobility.

Finite Element Modeling for Biomechanical Comparisons of Multilevel Transforaminal, Posterior, and Lateral Lumbar Approaches to Interbody Fusion Augmented with Posterior Instrumentation.

OBJECTIVE: Verifying the intervertebral stability of each intervertebral fusion procedure, including transforaminal, posterior, and lateral lumbar interbody fusion (TLIF, PLIF, and LLIF, respectively), and the ratio of stress on the rods and pedicle screws during initial fixation may help select a fixation procedure that reduces the risk of mechanical complications, including rod fracture and screw loosening. Thus, we aimed to assess whether these procedures could prevent mechanical complications. METHODS: Using the finite element method (FEM), we designed 4 surgical models constructed from L2-5 as follows: posterior lumbar fusion (PLF), TLIF, PLIF, and LLIF models. Bilateral rods and each pedicle screw stress were tracked and calculated as Von Mises stress (VMS) for comparison among the PLF and other 3 interbody fusion models during flexion, extension, and side-bending movements. RESULTS: The lowest rod VMS was LLIF, followed by PLIF, TLIF, and PLF in flexion and side bending movements. Compared with PLF, intervertebral fixation significantly reduced stress on the rods. No remarkable differences were observed in extension movements in each surgical procedure. A tendency for higher pedicle screw VMS was noted at the proximal and distal ends of the fixation ranges, including L2 and L5 screws for each procedure in all motions. Intervertebral fixation significantly reduced stress on the L2 and L5 screws, particularly in LLIF. CONCLUSIONS: Stress on the rods and pedicle screws in the LLIF model was the lowest compared with that induced by other intervertebral fusion procedures. Therefore, LLIF may reduce mechanical complications occurrence, including rod fracture and screw loosening.

Intervertebral disc and macrophage interaction induces mechanical hyperalgesia and cytokine production in a herniated disc model in rats.

OBJECTIVE: The expression of proinflammatory factors such as tumor necrosis factor α (TNFα), interleukin-6 (IL-6), IL-8, and prostaglandin E(2) (PGE(2) ) is significantly correlated with the symptoms of herniated disc disease. Among the different types of immune cells, macrophages are frequently noted in the herniated disc tissue. We undertook this study to clarify the interaction of the intervertebral disc (IVD) and macrophages with regard to the production of TNFα, IL-6, IL-8, and PGE(2) . METHODS: We developed 2 animal models to assess the interactions of IVDs with macrophages in terms of TNFα, IL-6, IL-8, and PGE(2) production and pain-related behavior. We also cocultured IVDs and macrophages to assess the role of TNFα in IL-6, IL-8, and PGE(2) production. RESULTS: IVD autografts induced TNFα, IL-6, IL-8, and cyclooxygenase 2 (COX-2) messenger RNA (mRNA) up-regulation; macrophage infiltration was seen shortly after the autograft was implanted. A significant decrease was noted in the mechanical threshold of the ipsilateral paw following the up-regulation of TNFα, IL-6, IL-8, and COX-2 mRNA. Only IVD and macrophage cocultures resulted in IL-8 and PGE(2) up-regulation. TNFα up-regulation was maximized before that of IL-6 and IL-8. TNFα neutralization attenuated production of IL-6 and PGE(2) , but not that of IL-8. Neutralization of TNFα and IL-8 significantly increased the paw withdrawal mechanical threshold in the IVD autograft and spinal nerve ligation model. CONCLUSION: IVD-macrophage interaction plays a major role in sciatica and in the production of TNFα, IL-6, IL-8, and PGE(2) . TNFα is required for IL-6 and PGE(2) production, but not for IL-8 production, during IVD-macrophage interaction. Neutralization of TNFα and IL-8 can be a valuable therapy for herniated disc disease.

C1 laminectomy for retro-odontoid pseudotumor without atlantoaxial subluxation: review of seven consecutive cases.

PURPOSE: A retro-odontoid pseudotumor is usually a reactive fibrocartilaginous mass associated with atlantoaxial subluxation (AAS). However, a retro-odontoid pseudotumor not associated with AAS, which undergoes spontaneous regression following C1 laminoplasty, has been reported. The purpose of this study was to report surgical outcomes of C1 laminectomy for retro-odontoid pseudotumor without AAS. MATERIALS AND METHODS: The cases of seven patients (mean age 75.6 ± 7.6 years-old) with retro-odontoid pseudotumor without AAS were reviewed. The mean follow up time was 52.3 ± 25.5 months. Each patient underwent a C1 laminectomy with an additional C3-6 expansion laminoplasty in three patients. The Japanese Orthopaedic Association score (JOA score) was used for neurological assessment. Pseudotumor size and additional AAS were analyzed using MRI and radiography. RESULTS: All patients exhibited neurological improvement following surgery, the JOA score improved from 7.2 ± 3.2 to 14.1 ± 2.6. The mean O-C2 and C2-7 angle decreased from -3.2 ± 2.1° to -3.9 ± 1.7°, showing a slight kyphotic change. Postoperative AAS was not observed. All pseudotumors spontaneously resolved, and recurrence and regrowth were not observed. Five patients had MRIs after gadolinium administration; four patients who showed enhancement of the pseudotumor had almost complete reduction within 1 year following surgery. DISCUSSION: Our study, assessing the outcome of C1 laminectomy for retro-odontoid pseudotumor, found neurological improvement in all cases. Since all pseudotumors were reduced and additional AAS was not observed, C1 laminectomy for retro-odontoid pseudotumor, in the absence of AAS, is recommended as a therapeutic strategy.

Intraosseous Schwannoma of the Distal Phalanx.

Intraosseous schwannomas are extremely rare and only a few cases involving the proximal phalanx and metacarpal of the hand have been reported. We report a patient with an intraosseous schwannoma of the distal phalanx. Radiographs showed lytic lesions in the bony cortex and enlarged soft shadows of the distal phalanx. The lesion was hyperintense to fat on T2-weighted magnetic resonance imaging (MRI) and strongly enhanced after gadolinium (Gd) administration. Surgical findings revealed that the tumour had developed from the palmar side of the distal phalanx and the medullary cavity was filled with a yellow tumour. The histological diagnosis was schwannoma. A definitive diagnosis of intraosseous schwannoma using radiography is difficult. In our case, a high signal was observed on Gd-enhanced MRI and histological findings showed areas with a high cellular area. Thus, Gd-enhanced MRI may help in the diagnosis of intraosseous schwannomas of the hand. Level of Evidence: Level V (Therapeutic).