Portion Of Ligament Research Articles

Long-term Results of Percutaneous Lumbar Decompression for LSS

The aim of this report was to evaluate the long-term effectiveness and safety of mild lumbar decompression for the treatment of neurogenic claudication associated with lumbar spinal stenosis. This technique uses a percutaneous dorsal approach to remove small portions of ligament and lamina, thereby restoring space and decompressing the spinal canal. Two-year data are reported for 45 patients treated with mild decompression at 11 US sites. Outcome measures included the Visual Analog Scale (VAS), Oswestry Disability Index, and Zurich Claudication Questionnaire. Safety was monitored throughout the procedural and follow-up period for all patients. Interim data are included for these patients at 1 week, 6 months, and 1-year follow-up. Seventy-one percent of patients reported improvement in VAS at the end of the reporting period. At 2 years, patients demonstrated a statistically significant reduction of pain as measured by VAS, and improvement in physical function and mobility was significant as measured by Zurich Claudication Questionnaire and Oswestry Disability Index. Tukey honestly significant different test found significant improvement in all outcome measures from baseline to each follow-up interval. Further, major improvement occurred by 1-week follow-up and showed no difference between each subsequent follow-up, signifying considerable stability and durability of the initial result over time. No major device or intraprocedural adverse events were reported. In this report of 2-year follow-up on 45 patients treated with mild percutaneous lumbar decompression, patients experienced statistically significant pain relief and improved functionality.

The EWAS Classification of Scapholunate Tears: An Anatomical Arthroscopic Study.

Treatment of scapho-lunate (SL) injuries is still a challenge for the surgeon, especially in chronic cases. The aim of the study isto experimentally cut, specific portions of scapholunate ligament and extrinsic ligaments and check their corresponding arthroscopic finding in order to understand the pathogenesis and develop a new classification system which is an evolution of the present arthroscopic classifications. Materials and Methods Thirteen cadaver wrists were studied under arthroscopy. Different portions of the scapho-lunate ligament were subsequently sectioned. In group A the sectioning sequence was: anterior SLIOL, RSC, LRL, SLIOL's proximal and posterior, DIC, DRC ligament and ST ligaments (8 cases). In group B it was: SLIOL's posterior and proximal, DIC, SLIOL's anterior, LRL, RSCL, DRC, ST ligaments (5 cases). The anatomo-pathological findings after each sectioning were correlated to the classification system proposed (Table 1). Results In group A, stage 3A was obtained when SL ligament's volar and intermediate portion and/ or SC/LRL ligaments were sectioned. A stage 3C was obtained when section of posterior SLIOL was sectioned as well. A stage IV when the DIC was also sectioned. In group B a stage 3B was obtained by cutting intermediate, posterior portion of the SLIOL ligament and DIC. A stage 3C was obtained when the anterior part of the SLIOL was also sectioned. In all cases, sectioning of the SLIOL lead to a stage 3C only if associated with sectioning of at least one of the extrinsic stabilizers (DIC or SC/LRL). Sectioning of DIC and SC ligament, in addition to SLIOL led to an arthroscopic stage IV. When ST, DRC and TH ligaments were also sectioned significant radiological signs appeared (stage V). Conclusions This study helps us to understand the anatomo-pathological scapho-lunate lesions in their different stages of partial lesions. Commonly called scapho-lunate lesions are complex, involving also extrinsic ligaments.

MRI features most often associated with surgically proven tears of the spring ligament complex

The authors aim to present the common MRI appearances of surgically proven spring ligament tears as minimal radiological literature exists regarding injury to this increasingly important structure. Our retrospective review identified a treatment group comprising 13 cases of surgically proven spring ligament injury and a 96-patient comparison group. All patients underwent standard musculoskeletal MRI sequences of the foot and ankle. Images were reviewed by a registrar-grade orthopedic surgeon and a consultant musculoskeletal radiologist for abnormalities of the spring ligament complex. MRI findings in relation to surgically proven injury of the superior-medial portion of the spring ligament included proximal thickening >5 mm in 92 % and distal thinning <2 mm in 85 % of proven injures to the spring ligament complex. Common abnormalities of the medio-plantar portion comprised ligament thickening >7 mm in 31 % and intra-substance signal heterogenicity demonstrated in 38 % of cases. The complex orientation of the medio-plantar ligament makes its evaluation unreliable due to the difficulty obtaining diagnostic quality imaging and our inability to correlate MRI findings in this portion of the ligament with surgically proven injury. However, MRI abnormalities of the superior-medial ligament are consistent, reproducible, and correlate with surgical pathology. As our incomplete understanding of the flexible flatfoot deformity evolves, our ability to recognize injury to the spring ligament may encourage novel surgical treatments looking to incorporate its repair or reconstruction into deformity correction.

Predictors of Distal Radioulnar Joint Instability in Distal Radius Fractures

A tear of the triangular fibrocartilage complex (TFCC) is the most frequent soft tissue injury associated with fractures of the distal radius, and repair of the deep ligamentous portion of the TFCC is considered when the tear contributes to instability of the distal radioulnar joint (DRUJ). The purpose of this prospective cohort study was to identify predictors of DRUJ instability accompanying unstable distal radius fractures. Between 2002 and 2007, we prospectively treated 163 consecutive patients with unstable distal radius fractures with the volar locking plating system. Complete radioulnar ligament tears representing DRUJ instability were present in 11 of 163 distal radius fractures. We tested univariate associations between DRUJ instability and potential predictors and conducted multivariate analysis to establish independent predictors of instability. We applied receiver operating characteristics curves within the significant risk factors to determine threshold values. In univariate analyses, only the radial and sagittal translation ratios of the fracture site were significant predictors of DRUJ instability. Multivariate logistic regression analysis confirmed that the radial translation ratio, which corresponds to a normalized DRUJ gap, was a significant risk factor. According to the receiver operating characteristics curve for the radial translation ratio, the area under the curve was 0.89. A cutoff value of 15% for the radial translation ratio showed the highest diagnostic accuracy rate. A radiographic finding of a normalized DRUJ gap on posteroanterior views was the most important predictor to identify DRUJ instability accompanying unstable distal radius fractures. The relative risk of instability increases by 50% when the ratio of DRUJ widening increases by 1%.

Study of length changes in the collateral ligament during movement of the metacarpophalangeal joint

Objective To investigate changes in collateral ligament length during flexion and extension of the metacarpophalangeal joint (MCJ) of the four fingers. Methods Spiral CT scans of the MCJ of the index, middle, ring and little fingers were obtained from 6 volunteers. Images from the mid-metacarpal to midproximal phalanx were acquired while the MCJ moved from 0° of flexion to 90° of flexion with 30° inerements.Changes in length of the collateral ligament of MCJ of each individual finger during MCJ movement were analyzed by software processing after three-dimensional image reconstruction of bone structures were obtained. Results During flexion of the MCJ the dorsal bundle of the ulnar and radial collateral ligaments lengthened, while the volar bundle shortened. The length of the middle bundle did not change significantly. Conclusion During MCJ flexion and extension, the collateral ligaments are in a state of tension. However tension in different portions of the ligament varies. There are two main relative movements during MCJ flexion: lengthening of the dorsal bundle of the collateral ligament results in increased tension and shortening of the volar bundle results in decreased tension. The middle bundle always maintains proper tension, restricting and regulating the movement of the joint. Key words: Metacarpophalangeal joint; Collateral ligaments; Movement; Length changes; In vivo study

Changes in Shape and Length of the Collateral and Accessory Collateral Ligaments of the Metacarpophalangeal Joint During Flexion

Although the collateral and accessory collateral ligaments of the metacarpophalangeal joint contribute to the stability of this joint, the functional role of the various portions of these ligaments during flexion is unclear. We investigated changes in the three-dimensional shape and length of the collateral and accessory collateral ligaments during flexion to determine how each portion stabilized the metacarpophalangeal joint. Twelve fingers from three embalmed cadavers were examined. The origin and the insertion point of the dorsal, middle, and volar portions of the radial and the ulnar collateral ligament and of the radial and the ulnar accessory collateral ligament were precisely identified. Microcomputed tomograms were obtained at 10° intervals during passive flexion from 0° to 80°. We created three-dimensional models of the metacarpal, the proximal phalange, and the paths of the twelve ligament portions. Finally, we calculated the change in the shape and length of the path of each ligament portion during flexion. The region of contact between each collateral ligament and the lateral edge of the metacarpal gradually lengthened during flexion of the joint, and the ligament gradually stretched to pass around the convex radial or ulnar surface of the metacarpal head. In contrast, each accessory collateral ligament curved around the volar tubercle of the metacarpal head at all flexion angles. The length of the volar portion of each collateral ligament and the length of the dorsal and middle portions of each accessory collateral ligament underwent little change during flexion. However, the lengths of the dorsal and middle portions of each collateral ligament increased significantly during flexion, and the length of the volar portion of each accessory collateral ligament decreased significantly. The collateral and accessory collateral ligaments can each be functionally divided into three portions-dorsal, middle, and volar. The volar portion of each collateral ligament and the dorsal and middle portions of each accessory collateral ligament are nearly isometric, the dorsal and middle portions of each collateral ligament become taut only in flexion, and the volar portion of each accessory collateral ligament becomes taut only in extension.

Collateral ligament length change patterns after joint line elevation may not explain midflexion instability following TKA

Midflexion instability (MFI) after TKA is a phenomenon often described as varus–valgus instability between 30° and 45° knee flexion. The exact mechanisms causing MFI remain unclear, but elevation of the joint line (JLE) may be one possible cause. In an in silico approach using 4 subject specific musculoskeletal models, the length change patterns of the collateral ligaments during knee flexion (relative to the extended knee) were calculated for the anatomically reconstructed joints as well as for JLEs of 5 and 10 mm. Analysis of the distance between the ligaments’ attachment sites (DA) in midflexion revealed a relative decrease in DA magnitude after JLE for both collateral ligaments in comparison to the anatomically reconstructed knee. This finding suggests that JLE could contribute to MFI. However, the anterior ligament regions also experienced a DA increase (MCL) or only a slight DA decrease (LCL) for each JLE simulated. From this perspective, the anterior ligament portions are unlikely to slacken in midflexion and JLE is unlikely to contribute greatly to MFI. In conclusion, our findings did not support the idea that JLE is a major contributor to midflexion instability for this particular ultra-congruent implant design.

Biomechanical properties of the scapholunate ligament and the importance of its portions in the capitate intrusion injury

BackgroundRepair of the dorsal component of the scapholunate ligament alone is the usual surgical treatment for scapholunate injuries. Recent literature has suggested that additionally repairing the palmar component of the scapholunate ligament leads to improved and lasting clinical outcomes. The aim of this study was to determine the biomechanical properties of both portions of scapholunate ligaments derived from the same wrist and compare them with the whole scapholunate ligament. The goal was to further elucidate the importance of the palmar portion of the scapholunate ligament from a biomechanical perspective. MethodsScapholunate ligaments and their components were harvested from the same fresh frozen cadaveric wrists. Force at failure and stiffness were measured. FindingsThe mean maximum loads to failure for the entire scapholunate ligament, dοrsal and palmar portions were found to be 147 (SD 54)N, 83 (SD 18)N and 86 (SD 16)N respectively. No statistical difference was found between the mean maximum load and stiffness for palmar and dorsal components (P=0.05). Mean maximum load and stiffness, of the intermediate portion, were 36 (SD 15)N and 25 (SD 23)N/mm. InterpretationOur biomechanical findings on the dorsal and palmar portions of the scapholunate ligament suggest that each portion contributes approximately 50% to the whole ligament tensile force. These results appear to agree with other reports about the stabilizing role of the palmar portion of the scapholunate ligament and suggest that the palmar portion of the ligament should be considered for surgical repair.

Morphological and Functional Characteristics of Three-Dimensional Engineered Bone-Ligament-Bone Constructs Following Implantation

The incidence of ligament injury has recently been estimated at 400,000/year. The preferred treatment is reconstruction using an allograft, but outcomes are limited by donor availability, biomechanical incompatibility, and immune rejection. The creation of an engineered ligament in vitro solely from patient bone marrow stromal cells (has the potential to greatly enhance outcomes in knee reconstructions. Our laboratory has developed a scaffoldless method to engineer three-dimensional (3D) ligament and bone constructs from rat bone marrow stem cells in vitro. Coculture of these two engineered constructs results in a 3D bone-ligament-bone (BLB) construct with viable entheses, which was successfully used for medial collateral ligament (MCL) replacement in a rat model. 1 month and 2 month implantations were applied to the engineered BLBs. Implantation of 3D BLBs in a MCL replacement application demonstrated that our in vitro engineered tissues grew and remodeled quickly in vivo to an advanced phenotype and partially restored function of the knee. The explanted 3D BLB ligament region stained positively for type I collagen and elastin and was well vascularized after 1 and 2 months in vivo. Tangent moduli of the ligament portion of the 3D BLB 1 month explants increased by a factor of 2.4 over in vitro controls, to a value equivalent to those observed in 14-day-old neonatal rat MCLs. The 3D BLB 1 month explants also exhibited a functionally graded response that closely matched native MCL inhomogeneity, indicating the constructs functionally adapted in vivo.

Three-dimensional knee model: Constrained by isometric ligament bundles and experimentally obtained tibio-femoral contacts

The purpose of this study is to investigate the effect of anterior portion of anterior cruciate ligament, posterior cruciate ligament, anterior and deep portions of medial collateral ligament and the tibio-femoral articular contacts on passive knee motion. A well-accepted reference model for a normal tibio-femoral joint is reconstructed from the literature. The proposed three-dimensional dynamic tibio-femoral model includes the isometric fascicles, ligament bundles and irregularly shaped medial-lateral contact surfaces. With the approach we aim to analyze bone shape and ligament related abnormalities of knee kinematics. The rotations, translations and the contact forces during passive knee flexion were compared against a reference model and the results were found in close accordance. This study demonstrated that isometric ligament bundles play an important role in understanding the femur shape from contact points on tibia. Femoral condyles are not necessarily spherical. The surgical treatments should consider both ligament bundle lengths and contact surface geometries to achieve a problem free knee kinematics after a knee surgery.

A Quantitative Study of the Microstructure and Biochemistry of the Medial Meniscal Horn Attachments

Little quantitative data is available on the structure of meniscal attachments. Therefore, as an aid to designing meniscal replacements as well as a possible explanation for mechanical behavior, this study was designed to further the knowledge of the microstructure and biochemistry of native meniscal attachments. Bovine medial meniscal attachments (the external ligamentous portion as well as the transition zones at the bony insertion) were removed and prepared for microstructural evaluation. After embedding in paraffin, the samples were sliced on a microtome and stained for quantitative analysis. The anterior and posterior insertion sites are known to contain three zones: subchondral bone, calcified fibrocartilage, and uncalcified fibrocartilage. Additionally, others have shown that the anterior insertion site contains a ligamentous zone. The insertion zones were further divided into proximal, middle, and distal zones. The posterior attachment's insertion site had a significantly greater thickness of interdigitations, subchondral bone, uncalcified fibrocartilage, and calcified fibrocartilage zone thickness compared to the anterior attachment insertion. The anterior attachment's insertion had the greatest GAG fraction in each zone when compared to the posterior attachment's insertion. GAG fraction decreased from the meniscus to the subchondral bone. Both GAG fraction and normalized thickness varied within a given zone, decreasing from the distal to proximal regions in both the anterior and posterior attachments' insertion zones. Crimp frequency of the collagen fibrils in the external ligamentous portion of the tissue was homogeneous along the length. The findings from this study agree with previously published material property data on the medial meniscal attachments, and could be used in the future to design methods of attachment for tissue engineered replacement menisci.

Optimal Intervertebral Sealant Properties for the Lumbar Spinal Disc: A Finite-Element Study

Background In the lumbar spinal column, an annular disruption may be sealed after annulotomy to prevent further prolapse and instability. We investigated the biomechanical effects of various material properties of an injectable sealant Methods We used a 3-dimensional, nonlinear, osteoligamentous, experimentally validated finite-element model of the L3−L5 spine segment to study annulotomies of varying sizes and locations in the L3−L4 annulus followed by replacement with isotropic sealants (plugs) with a Young's modulus of 0.4, 2.0, 4.0, 6.0, and 40.0 MPa. Annulotomies in the region of the posterior longitudinal ligament were studied with and without the ligament in place. Intact, destabilized, and repaired models were subjected to 400 N compression and 12.7 Nm moment in all loading modes to compute plug forces, plug stresses, motion characteristics, and annulus bulge. Results Changes in sealant stiffness minimally affected the overall motion characteristics of the segment. Increases in shear stress and von Mises stress were proportional to the stiffness of the sealant. The von Mises stress was inversely proportional to plug size. Removal of portions of the posterior longitudinal ligament did not significantly alter motion between spinal segments or stress in the annulus fibrosus. Removal of portions of the ligament increased the disc bulge when plugs were less stiff. Intradiscal pressure decreased when an annulotomy was created. The sealant generally restored nucleus pressure to a degree proportionate to sealant stiffness. Conclusions Minimizing sealant stresses as well as expulsion and separation forces should lead to a minimal Young's modulus. Sealant materials with a Young's modulus close to 6 MPa are most appropriate. The allowable variation in material properties is reduced with increased annulotomy size. Removal of posterior longitudinal ligament only allows increased sealant bulge when the sealant's modulus of elasticity is very low. This removal does not affect spinal unit biomechanics or annulus stress in annulotomy or annulotomy with sealant repair.

Endoscopic Resection of Dorsal Spinous Processes and Interspinous Ligament in Ten Horses

To describe endoscopic surgical subtotal resection of the dorsal spinous processes (DSP) and interspinous ligament in horses. Descriptive clinical study. Adult horses (n=10) with back pain and impinging dorsal spinous processes Diseased portions of DSP and interspinous ligament were resected by endoscopic surgery, using Destandau Endospine to create a surgical space and provide triangulation for the endoscope, suction cannula, and surgical instruments. Medical records of 10 horses with pain attributable to DSP pathology treated by endoscopic resection of DSP were reviewed to determine intra- and postoperative complications and outcome. Affected portions of DSP were successfully resected with minimal hemorrhage. Limited periosteal reaction was noticed after 3 months in 2 horses. Nine horses had no complications and returned to full work within 8 weeks; 1 developed a subcutaneous abscess, which was successfully managed, and returned to work after 3 months. Surgical resection improved presenting clinical signs and owner's complaint although 2 horses did not return to previous performance levels. Resection of DSP and interspinous ligament can be successfully performed endoscopically in horses. Hemorrhage was minimal but reduced visibility. Complications were minimal and most horses returned to work by 8 weeks. Endoscopic resection of DSP is a safe and reliable surgical procedure in horses.

Optimal intervertebral sealant properties for the lumbar spinal disc: a finite-element study.

BackgroundIn the lumbar spinal column, an annular disruption may be sealed after annulotomy to prevent further prolapse and instability. We investigated the biomechanical effects of various material properties of an injectable sealantMethodsWe used a 3-dimensional, nonlinear, osteoligamentous, experimentally validated finite-element model of the L3–L5 spine segment to study annulotomies of varying sizes and locations in the L3–L4 annulus followed by replacement with isotropic sealants (plugs) with a Young's modulus of 0.4, 2.0, 4.0, 6.0, and 40.0 MPa. Annulotomies in the region of the posterior longitudinal ligament were studied with and without the ligament in place. Intact, destabilized, and repaired models were subjected to 400 N compression and 12.7 Nm moment in all loading modes to compute plug forces, plug stresses, motion characteristics, and annulus bulge.ResultsChanges in sealant stiffness minimally affected the overall motion characteristics of the segment. Increases in shear stress and von Mises stress were proportional to the stiffness of the sealant. The von Mises stress was inversely proportional to plug size. Removal of portions of the posterior longitudinal ligament did not significantly alter motion between spinal segments or stress in the annulus fibrosus. Removal of portions of the ligament increased the disc bulge when plugs were less stiff. Intradiscal pressure decreased when an annulotomy was created. The sealant generally restored nucleus pressure to a degree proportionate to sealant stiffness.ConclusionsMinimizing sealant stresses as well as expulsion and separation forces should lead to a minimal Young's modulus. Sealant materials with a Young's modulus close to 6 MPa are most appropriate. The allowable variation in material properties is reduced with increased annulotomy size. Removal of posterior longitudinal ligament only allows increased sealant bulge when the sealant's modulus of elasticity is very low. This removal does not affect spinal unit biomechanics or annulus stress in annulotomy or annulotomy with sealant repair.

Posterolateral Corner Reconstruction of the Knee: Surgical Technique Utilizing a Bifid Achilles Tendon Allograft and a Double Femoral Tunnel

Reconstruction of the posterolateral corner of the knee has received increased attention in the recent literature. Basic science studies have helped us determine the 3 critical structures of the posterolateral corner: the lateral collateral ligament (LCL), the popliteus tendon, and the popliteofibular ligament. We have developed an anatomic posterolateral corner reconstruction that most closely resembles these 3 key structures and is based on the work of previous authors. Our technique is performed using a single Achilles allograft. The bone plug is secured in a femoral tunnel at the anatomic attachment of the popliteus tendon with an interference screw. The Achilles tendon is then split approximately 1 to 2 cm distal to the bone plug into 2 segments: (1) the popliteofibular ligament portion that is passed through a fibular tunnel starting at the anatomic attachment of popliteofibular ligament and fixed with a biointerference screw and (2) the static portion of the popliteus tendon securing this through a tibial tunnel passed from posterior to anterior right at the musculotendinous junction of the popliteus. The anterior limb of the Achilles tendon exiting the fibula is then brought back around, secured to the fibular attachment of the LCL with a suture anchor, and is then passed through a separate femoral tunnel placed at the anatomic attachment of the LCL.

Transarticular invasion of bone tumours across the sacroiliac joint

The purpose of this study was to evaluate the pattern of tumour spread across the SI articulation, correlating with cadaveric anatomic observations, in order to better understand the local spread of tumour and to assist in the assessment of local staging. Twenty-four consecutive patients (14 male, 10 female; age range 22-89 years, mean 52 years) with primary bone tumours of the iliac bone or sacrum abutting the SI joint, in whom surgical resection of the SI joint was performed, were studied following institutional ethics approval. In all patients, preoperative magnetic resonance (MR) imaging studies of the pelvis and SI joint were reviewed for imaging evidence of transarticular extension across the SI joint. Gross pathologic and histologic assessment of possible transarticular SI joint tumour extension was performed in all patients. Nine cadaveric pelvic specimens without pelvic neoplastic disease (4 male, 5 female; age range 20-84 years, mean 59 years, median 58 years) were anatomically dissected and the articular anatomy of the SI joint examined macroscopically. Twelve of the twenty-four patients demonstrated imaging and histological evidence of transarticular SI joint invasion. Eight tumours infiltrated only the interosseous ligamentous aspect of the SI joint. In the remaining four cases, extensive tumour infiltrated both the cartilaginous and ligamentous aspects of the joint. No case showed tumour involvement isolated to the cartilaginous aspect of the joint. Among the cadaveric specimens studied, degenerative changes were found involving the majority of cases (6/9), with cartilage thinning and fibrillation and antero-superior marginal osteophytes seen involving the cartilaginous portion of the SI joint articulation. Four of the nine specimens demonstrated central ossification bridging the iliac and sacral aspects of the ligamentous (interosseous) SI joint. Tumour invasion across the SI articulation favours its interosseous ligamentous portion. Factors influencing transarticular tumour extension and its preferential course across the interosseous component of the articulation have been discussed. It is particularly important to assess the interosseous ligamentous portion of the SI articulation when locally staging primary pelvic bone tumours subjacent to the SI articulation, as this will have a significant impact on planning surgical management.

Deformation and fracture behavior of notched and unnotched unidirectional C/C-Mg composite with Young's modulus 520 GPa and tensile strength 1 GPa

Experimental study on tensile fracture behavior of the newly developed C/C-Mg composite, prepared by infiltration of Mg into the pores in the C/C composite heat-treated at 3000°C, was carried out. The volume fraction of the filled Mg was 9–10%. The composite had a specific density 2.1, Young's modulus 520 GPa and Poisson's ratio 0.26. The average tensile strength measured for the specimen with a nominal width 8 mm, gage length 40 mm and thickness 1 mm was 1 GPa. The Young's modulus was improved from 450 to 520 GPa and the strength from 0.9 to 1.0 GPa by Mg-infiltration. The specific Young's modulus and specific strength based on the average measured values were 2.5 × 107 m and 5 × 104 m, respectively, showing high potential as light-weight, stiff and strong structural material. The strength distribution of the composite was described by the two-parameter Weibull distribution function with a shape parameter 7.6 and scale parameter 1060 MPa. Prior to the overall fracture of the composite, the longitudinal cracking arose at the notch tip, due to which the notch tip was blunted and the ligament portion behaved like an unnotched specimen. As a result, the notched strength could be described by the net stress criterion. The apparent critical energy release rate at formation of the longitudinal crack was around 70–90 J/m2.

Histological anatomy of the triangular fibrocartilage complex of the human wrist

The triangular fibrocartilage complex (TFCC) was studied in serial histological sections of the human wrist to reveal its three-dimensional fine structure. The TFCC consisted of a fibrocartilaginous disc proper and other fibrous components. Three-dimensionally, the distal portion of the TFCC had a hammock-like contour that partially surrounded the carpus; while the proximal ligamentous portion corresponding to the radioulnar ligament connected the radius to the ulna. The radioulnar ligament originated at the ulna from both the fovea and the basistyloid. The fibres first gathered and then bifurcated palmarly and dorsally, enclosing and partially coalescing with the proximal side of the disc before inserting around the distal rim of the sigmoid notch of the radius. The meniscus homologue, which corresponded to the ulnar internal wall of the wrist joint, was derived from a loose synovial fold adapting to the stresses from radioulnar deviation. The distal side of the disc consisted of a dense population of chondrocytes in a collagen matrix, while the proximal side was rather rich in fibres directed radioulnarly. Inside the TFCC were loose connective tissues. The histological arrangement of the TFCC is compatible with its function of supporting the carpus, stabilizing the joints and allowing smooth motion of the wrist.

A histological and electron-microscopic study of the architecture and ultrastructure of human periodontal tissues

The structure of periodontal tissues is still far less understood than their clinical relevance would demand. Here the periodontal ligament and radicular cementum in healthy human teeth were studied by light microscopy, transmission and scanning electron microscopy. These observations showed that the extracellular matrix of periodontal ligament is composed of a loose plexus of wavy collagen fibrils immersed in a highly hydrated interfibrillar matrix. Only close to their cemental insertion do these fibrils gather in thick, parallel fascicles (Sharpey’s fibres). As these cross the mineralization front, they become infiltrated by the mineral phase and continue directly with the cementum matrix. Sharpey’s fibres, “extrinsic” and “intrinsic” fibres all appear to be the same fibres, which bend and branch repeatedly during their course within the thickness of the cementum. Because of its physical continuity with the cementum, a limited portion of the periodontal ligament approximately corresponding to the length of Sharpey’s fibres remains unaffected by enzymatic digestion of the interfibrillar matrix while the rest of the ligament is completely dissolved. The findings here indicate that the periodontal ligament and dental cementum join by a continuity rather than a contiguity of structures; that the collagen–mineral relation in cementum has distinctive features in comparison to other hard tissues; that extrinsic and intrinsic fibres of cementum and the adjoining portion of periodontal ligament form a structural, mechanical and metabolic unit distinct from the central, more metabolically active portion of the periodontal ligament.

MR imaging findings in spring ligament insufficiency.

Spring ligament insufficiency is associated with chronic posterior tibial tendon dysfunction, and may constitute an indication for surgical repair or reconstruction. This study examines the accuracy of MRI for the diagnosis of insufficiency of the spring ligament. Two experienced musculoskeletal radiologists independently scored the MRI findings in 13 cases of surgically proven spring ligament insufficiency and in 18 control subjects, using a standardized scoring system. Insufficiency of the spring ligament was associated with increased signal heterogeneity on short TE spin echo images, and an increase in the thickness of the medial portion of the ligament. The sensitivity of MRI for the diagnosis of spring ligament insufficiency was 54-77%, while the specificity was 100%. MRI assessment of the plantar portion of the spring ligament was unreliable (kappa=0.33), but the assessment of global ligament integrity was substantially reproducible (kappa=0.76). The medial portion of the spring ligament can be reliably assessed on routine MRI. The findings of spring ligament insufficiency on MRI are only moderately sensitive but highly specific.