Functional ligamentous anatomy of the trapezium and trapeziometacarpal joint (gross and arthroscopic).

A detailed description of the ligamentous anatomy of the thumb basal joint is presented from a gross, arthroscopic, and functional point of view. All 16 ligaments that stabilize the trapezium and trapeziometacarpal (TM) joint are discussed in association with their presumed functional relevance regarding trapezial and trapeziometacarpal joint stability. Geometric and mathematical models are introduced to help describe and support anatomic observations with regard to ligament function. The dorsoradial ligament appears to be an important stabilizer of the TM joint against dorsally directed forces. The trapeziotrapezoid, trapezio-II metacarpal, and trapezio-III metacarpal ligaments appear to function as tension bands to help support the trapezium against cantilever bending forces imparted onto the trapezium by the thumb metacarpal.

A conceptual model for describing decision-making situations in integrated natural resource planning and modeling projects.

A conceptual model is developed herein for the purpose of stimulating discussions within groups planning and carrying out integrated natural resource projects. We first describe four basic components of integrated planning and modeling efforts: people, databases, technology, and organizational commitment. Second, we provide one view of the relationship between the size of the project's decision-making body and the timing of decisions during a project's life cycle. Finally, these two discussions are combined into a conceptual model describing the dynamic nature of decision-making within integrated projects. The abstractions and generalizations described here are not unique to private industry or governmental organizations and should provide the basis for a discussion of decision-making issues among interdisciplinary professionals embarking on large-scale or complex modeling efforts.

Trapezial tilt: a radiographic correlation with advanced trapeziometacarpal joint arthritis.

Trapeziometacarpal (TMC) joint arthritis is a common and debilitating condition of the hand. We defined a radiographic measure of trapezial inclination (trapezial tilt) and found a positive correlation between an increased trapezial tilt and severity of TMC joint arthritis. Radiographs (Robert's views) were obtained from 50 pairs of normal hands to evaluate the trapezial tilt to assess radial inclination of the trapezium with respect to the second metacarpal. The trapezial tilt was also measured in 65 hands from 43 patients with various stages of TMC joint arthritis and compared with the normal value. The trapezial tilt for hands without arthritis was 42 degrees +/- 4 degrees, Eaton stages I and II was 42 degrees +/- 4 degrees, and Eaton stages III and IV was 50 degrees +/- 4 degrees. Trapezial tilt angles from the Eaton III and IV group were significantly greater than those of the normal and Eaton I and II groups. Advanced TMC joint arthritis (Eaton III and IV) is associated with an increased trapezial tilt. Mild TMC joint arthritis with an increased trapezial tilt may be treated surgically. We speculate that a trapezio-trapezoid and trapezio-II metacarpal arthrodesis, or an opening wedge osteotomy of the trapezium might arrest the progression of TMC joint arthritis by resetting the slope of the trapezium and decreasing the shear stress within the TMC joint.

Material properties of the trapezial and trapeziometacarpal ligaments.

Destabilization of the trapezium from its normal orientation with respect to the trapezoid, second metacarpal, and thumb metacarpal leads to incongruity at the trapeziometacarpal (TMC) joint. Abnormal shear forces may eventually result in TMC joint arthritis. By determining the relative stiffness and strength of the ligaments that stabilize this joint, one may infer their role in providing stability to the TMC joint. This study addresses the material properties of the ligaments stabilizing the trapezium and TMC joint to better understand the mechanics and kinematics of this joint. Fresh-frozen cadaveric hands (10 males and 10 females) were used to obtain bone-ligament-bone complexes from the dorsal and volar trapeziotrapezoid ligaments, dorsal and volar trapezio-second metacarpal ligaments, anterior oblique ligament, dorsoradial ligament, and trapezio-third metacarpal (T-III MC) ligament. The following material properties were derived from our data: ultimate load, ultimate stress (normalized failure load), ultimate strain (percent elongation), stiffness, toughness (energy to failure), and hysteresis. The dorsoradial ligament demonstrated the greatest ultimate load and toughness (energy to failure). The T-III MC ligament demonstrated the greatest ultimate stress (normalized failure load) and stiffness. The anterior oblique ligament demonstrated the least stiffness and the greatest hysteresis. The material properties of capsuloligamentous structures may be a good indicator of their importance to joint stability. Using these criteria we conclude that the T-III MC and dorsoradial ligaments are important stabilizers of the trapezium and TMC joint, respectively. These two ligaments were found to be the strongest, stiffest, and toughest ligaments, while the anterior oblique ligament was relatively weak and compliant. The dorsal trapezio-second metacarpal, volar trapezio-second metacarpal, and T-III MC ligaments were all relatively strong and are anatomically aligned to function as tension bands to restrain the trapezium against cantilever bending forces applied to it by the thumb during key or tip pinch.

Flexor tendon-tendon sheath interaction after tendon grafting: a biomechanical study in a human model in vitro.

A human cadaver tendon sheath model was used to study the differences in excursion resistance of tendons that might be considered as sources of clinical tendon grafts. The flexor digitorum profundus and superficialis tendons, the extensor indicis proprius tendon used in its normal proximal-distal orientation, the extensor indicis proprius tendon used in a reversed distal-proximal orientation, and the palmaris longus tendon were studied in 7 fingers. The intrasynovial tendons (the flexor digitorum profundus and superficialis tendons and the reversed extensor indicis proprius tendon) produced less excursion resistance (p < .05) than the extrasynovial tendons (the normally oriented extensor indicis proprius tendon and the palmaris longus tendon). In contrast to studies measuring resistance against a single pulley, resistance within a complete tendon sheath may be affected by contact with other structures, particularly in joint extension.

An anatomic study of the stabilizing ligaments of the trapezium and trapeziometacarpal joint.

We provide a detailed and comprehensive anatomic description of the ligaments stabilizing the trapezium and trapeziometacarpal joint. Sixteen ligaments were identified. Fourteen ligaments inserted onto the trapezium and 2 others attached independently to the thumb metacarpal. The ligaments inserting onto the trapezium were the superficial anterior oblique, deep anterior oblique (beak ligament), dorsoradial, posterior oblique, ulnar collateral, dorsal trapezio-trapezoid, volar trapezio-trapezoid, dorsal trapezio-second metacarpal, volar trapezio-second metacarpal, trapezio-third metacarpal, volar scaphotrapezial, radial scaphotrapezial, transverse carpal, and trapezio-capitate ligaments. The remaining 2 ligaments attach onto the thumb metacarpal and are the proper intermetacarpal and the dorsal intermetacarpal. The dorsoradial and deep anterior oblique ligaments play a substantial role in stabilizing the trapeziometacarpal joint, and the deep anterior oblique ligament may function as a pivot for the first metacarpal during palmar abduction to allow rotation (pronation). The dorsal trapezio-second metacarpal, volar trapezio-second metacarpal, and trapezio-third metacarpal ligaments function as tension bands and are required to prevent instability from cantilever bending forces on the trapezium.

Flexor tendon-pulley interaction after pulley reconstruction: a biomechanical study in a human model in vitro.

Ten cadaver digits were used to evaluate excursion resistance between a tendon and pulley after completing 4 methods of pulley reconstruction (Bunnell's, Kleinert's, Lister's, and Karev's techniques). Five tissues (palmaris longus tendon, extensor digitorum tendon, flexor digitorum superficialis tendon, extensor retinaculum, and volar plate) were used to reconstruct the A2 pulley. Intrasynovial tissue sources (extensor retinaculum, volar plate, and flexor digitorum superficialis tendon) produced less excursion resistance than extrasynovial tissue sources (extensor digitorum tendon and palmaris longus tendon). The models using the extensor retinaculum and volar plate as reconstructive materials produced less excursion resistance than the normal A2 pulley, whereas the models using the palmaris longus tendon produced the highest excursion resistance. Bunnell's technique of pulley reconstruction produced less excursion resistance than Kleinert's technique with all 3 tissues tested. The results of the in vitro study of excursion resistance between the tendon and reconstructed pulley demonstrated that Lister's technique of pulley reconstruction using the extensor retinaculum produced the least resistance to tendon gliding.

Excursion properties of tendon graft sources: interaction between tendon and A2 pulley.

We measured excursion resistance of 4 different tendons (flexor digitorum superficialis, the portion of the extensor indicis proprius tendon beneath the extensor retinaculum, the portion of the extensor indicis proprius tendon distal to the extensor retinaculum, and palmaris longus) beneath the A2 pulley. Intrasynovial tendons (i.e., flexor digitorum superficialis and the portion of the extensor indicis proprius beneath the extensor retinaculum) produced less excursion resistance than extrasynovial tendons (i.e., the portion of the extensor indicis proprius distal to the extensor retinaculum and palmaris longus). The excursion resistance of the intrasynovial portion of the extensor indicis proprius tendon was significantly lower than that of the extrasynovial portion of the same tendon. Intrasynovial tendons may be preferred to extrasynovial tendons when choosing a tendon graft source and graft gliding under a pulley is a consideration.

Forest Planning in an Oregon Case Study: Defining the Problem and Attempting to Meet Goals with a Spatial-Analysis Technique

Five major management goals were identified for the upper Grande Ronde River Basin on the Wallowa-Whitman National Forest in northeastern Oregon: to produce high-quality fish habitat, to maintain elk habitat, to restore and maintain forest conditions within the natural range of viability, and to contribute to community economic stability. From the broad goals, specific goals for stream temperature, habitat effectiveness index (HEI), habitat corridors, maintenance of land in late or old seral stages, and a nondeclining even flow of timber were selected. A case study was undertaken in a small watershed that is under typical societal constraints to determine whether one decision-support tool, SNAP II+, could evaluate the selected goals in a single planning exercise. Three riparian management strategies and two forest road scenarios were used. The exclusion of harvest and road-building from riparian zones in order to increase habitat protection decreased harvest levels and net present value but maintained preactivity stream temperatures. Other resources were generally maintained within prescribed management levels. Although the technique has limitations (e.g., it does not account for riparian zones in calculations of forage and cover for HEI, and it can use the maximum but not minimum acreage goal for some resources), it shows promise for evaluating management tradeoffs in watershed analysis.

Arthroscopic anatomy of the wrist.

A good working knowledge of the intra-articular anatomy of the wrist is essential to perform arthroscopy. The authors present a detailed description of all pertinent structures that may be seen during a radiocarpal and midcarpal arthroscopic examination.

Reexamination of hip biomechanics during unilateral stance.

The Koch model, as initially proposed, is an incomplete representation of hip biomechanics during the unilateral support phase of midstance. The model proposed by this study includes the iliotibial band as a tension band lateral to the femoral shaft. During the unilateral support phase of gait, the iliotibial band creates compression loading laterally and medially throughout the femur distal to the greater trochanteric apophysis. Bench testing of cadaveric femora with and without protheses demonstrated the necessity of a total hip replacement femoral component to engage the proximal lateral femoral cortex as an additional area of support against subsidence. This model, byproviding a more complete and accurate depiction of hip biomechanics, creates a more valid basis for analysis of hip function.

New dorsal capsulotomy for the surgical exposure of the wrist.

A reliable, safe approach to the wrist through fiber-splitting dorsal capsulotomies has been developed. The dorsal wrist capsule is exposed by subperiosteally elevating the fourth and fifth extensor compartments ulnarly and translocating the extensor pollicis longus tendon with the radial wrist extensor tendons radially. The midcarpal joint and the radial half of the radiocarpal joint are exposed by longitudinally splitting the dorsal radiocarpal and dorsal intercarpal ligaments, with the apex at the triquetrum. The flap created is elevated radially, detaching the dorsal capsule from the radius to the level of the styloid process. For exposure of the ulnocarpal joint, the dorsal radiocarpal ligament is split longitudinally, and the capsule is incised along the extensor carpi ulnaris tendon subsheath proximally to the level of the triangular fibrocartilage, with the apex at the triquetrum. The flap created is elevated proximally. Exposure of the wrist is excellent, stability of the carpal bones is maintained, and closure is simplified using this approach.