Capsuloligamentous restraints to dorsal and palmar carpal translation

Radiocarpal fracture-dislocation: Review of the literature, new classification and decision algorithm

BACKGROUND

Radiocarpal fractures and dislocations are rarely described in the literature. However, the consequences at the functional level are severe, with the loss of almost half of the articular amplitude. The most widespread classification is that of Dumontier, which divides the injury into two categories according to the presence or absence of a fracture. Currently, no classification considers fracture-dislocations in a global and multi-tissue manner; therefore, no therapeutic strategy has been reported.

METHODS

We conducted an exhaustive bibliographic search for cohort or case report articles concerning radiocarpal fracture-dislocations published between 1990 and the present. Only descriptions of the injury were identified (noting the type of fracture, direction of displacement and carpal injuries).

RESULTS

In all, data were collected from 14 retrospective series and 16 case reports involving 218 patients. Thirty-five and 183 cases involved anterior and posterior displacement, respectively. A fracture of the distal radius was found in 183 cases and 35 cases had a dislocation only, with no significant fracture. Among the posterior displacements, 44 isolated styloid fractures, 62 styloid and posterior marginal fractures, 29 bimarginal fractures (large anterior fragment and small posterior fragment) and 31 fractures of all the fragments described by Medoff with impaction of the central pavement were found. Anterior displacement fractures were found in 17 cases (styloid and/or anterior marginal fracture). We were able to group the different traumatic clinical forms according to a six-category classification.

DISCUSSION

A review of the literature highlighted three major components in the management of radiocarpal fracture-dislocations: the bone component, the ligament component and the associated intracarpal lesions. These three components were included in our classification and allowed us to accurately describe all types of radiocarpal fracture-dislocations published in the literature. Authors currently agree on management of the bone component but disagree on that of the ligament component. Particular attention should be paid to intracarpal lesions, which lead to poor outcomes if ignored. Based on our biographical research, we propose a management plan for these complex injuries.

LEVEL OF EVIDENCE

VI.

How Close Are the Volar Wrist Ligaments to the Distal Edge of the Pronator Quadratus? An Anatomical Study

Background: This cadaveric study defines the interval distance between the proximal insertion of the volar wrist ligaments and the distal edge of the pronator quadratus on the distal radius. It is important to be aware of this distance during surgical dissection for placement of volar locking plates for wrist fractures. Disruption of the volar wrist ligament insertion may have adverse biomechanical consequences such as carpal instability, which can lead to pain and eventually wrist arthritis. Methods: Thirteen cadaveric wrists were dissected using the trans-flexor carpi radialis volar approach to identify relevant anatomy. The distance between the distal border of the pronator quadratus and the most proximal insertion of the volar wrist ligaments was measured. Results: The average distance between the pronator quadratus and the proximal insertion of the volar wrist ligaments was 5 mm, with a standard deviation of 2 mm. Conclusions: The volar wrist ligaments insert quite near the distal end of the pronator quadratus. Surgeons should be cognizant of the proximity of the volar wrist ligaments and be judicious with subperiosteal stripping of the distal fragment during volar plating procedures.

Three-dimensional geometric morphometric analysis of the distal radius insertion sites of the palmar radiocarpal ligaments in hominoid primates

OBJECTIVES

To identify anatomic differences in the insertion sites of the palmar radiocarpal ligaments in different species of hominoid primates that may be related to their different types of locomotion.

MATERIALS AND METHODS

We have used three-dimensional geometric morphometrics (3D GM) to analyze the distal radius ligament insertion sites in 31 Homo sapiens, 25 Pan troglodytes, 31 Gorilla gorilla, and 15 Pongo pygmaeus. We have also dissected the radioscaphocapitate (RSC), long radiolunate (LRL) and short radiolunate (SRL) ligaments in six H. sapiens and five P. troglodytes to obtain quantitative values that were then compared with the results of the 3D GM analysis.

RESULTS

H. sapiens had a relatively larger insertion site of the RSC + LRL ligament than the other hominoid primates. P. pygmaeus and P. troglodytes had a relatively large SRL ligament insertion site with a palmar orientation. In G. gorilla, the two ligament insertion sites were relatively smaller and the SRL insertion site had an ulnopalmar orientation.

DISCUSSION

The morphological differences observed can be related to the types of locomotion used by the different species and to quantitative data obtained from the dissection of ligaments in H. sapiens and P. troglodytes. 3D GM analysis of ligament insertion sites can help in interpreting the types of locomotion used by extinct hominoid primates through the analysis of preserved fossilized fragments of the distal radius.

Dorsal Radiocarpal Joint Fracture-Dislocation: A Case Report

CASE

A 19-year-old right-hand-dominant man sustained a right dorsal radiocarpal dislocation. He presented with instability secondary to displacement of the volar ligamentous structures and an avulsed fragment of the distal aspect of the radius within the radiocarpal articulation. The patient was treated with open reduction and internal fixation, as well as a capsuloligamentous repair. At the 18-month follow-up, he had no pain and excellent functional recovery.

CONCLUSION

Our experience emphasizes the importance of looking critically at the radiographs when there is an irreducible radiocarpal fracture-dislocation. A volar distal radial fragment and attached ligamentous structures can be the main blocks to closed reduction.

The Pronator Quadratus and Distal Anterior Interosseous Nerve: A Cadaveric Study

Background The pronator quadratus (PQ) muscle is an important and commonly encountered structure in surgery of the wrist. A thorough understanding of the anatomy of the PQ and the anterior interosseous nerve (AIN), which innervates the PQ, is important, particularly during distal radius fracture osteosynthesis and distal AIN transfer to deep branch of the ulnar nerve. Furthermore, there is a paucity of literature regarding sex differences in the morphology of these structures. We describe the morphology of the PQ and AIN and compare PQ and AIN findings in male and female specimens. Methods Twenty-five cadaveric upper extremities underwent loupe-aided dissection of the volar forearm with identification of the AIN and PQ. A digital photograph taken perpendicular to the volar surface of the forearm was used to measure the PQ and assess AIN morphology using ImageJ (National Institutes of Health; Bethesda, MD). Comparisons between male and female specimens were performed. Results Of the 25 specimens, 84% appeared as a single trapezoidal muscle bundle, with the remaining 16% demonstrating a double-bundle morphology. The PQ was a mean 3.8 ± 0.5 cm in radial-ulnar width and 4.6 ± 0.7 cm in proximal-distal length with a mean thickness, area, and volume of 0.6 ± 0.2 cm, 18.2 ± 4.8 cm(2), and 10.5 ± 3.7 cm(3), respectively. The PQ branch of the AIN was a mean 3.8 ± 1.1 cm long and had a mean diameter of 1.4 ± 0.2 mm. Male specimens demonstrated significantly greater radial-ulnar width (p = 0.005), area (p = 0.006), and volume (p = 0.033) of the PQ, as well as a greater distance from the radial styloid to the distal arborization of the AIN (p = 0.005) compared with female specimens. Conclusions The current study informs hand surgeons of the morphologic variability and sexual dimorphism of the PQ and AIN and may help guide operative planning.

Carpal Ligament Anatomy and Biomechanics

A fundamental understanding of the ligamentous anatomy of the wrist is critical for any physician attempting to treat carpal instability. The anatomy of the wrist is complex, not only because of the number of named structures and their geometry but also because of the inconsistencies in describing these ligaments. The complex anatomy of the wrist is described through a review of the carpal ligaments and their effect on normal carpal motion. Mastery of this topic facilitates the physician's understanding of the patterns of instability that are seen clinically.

Carpal instability of the wrist

The scaphoid is stabilized by the scapholunate ligament (directly) and lunotriquetral ligament (indirectly). Disruption of either of these ligaments leads to a pattern of instability that, left untreated, leads to altered mechanics of the wrist and ultimately debilitating arthritis and collapse. Although arthroscopy remains the gold standard for diagnosis of these injuries, plain films and advanced imaging are useful adjuncts. In the acute setting, conservative treatment may be attempted, but recalcitrant cases require surgical stabilization. Salvage procedures are also available for those patients who fail initial stabilization or present with late degeneration.

Volar ligament repair for radiocarpal fracture-dislocation

Radiocarpal fracture-dislocations are uncommon injuries, comprising a spectrum of trauma to the capsuloligamentous complex and osseous structures of the radiocarpal joint along with the adjacent structures. Management guidelines are derived from limited case series and expert opinions. An understanding of the relevant anatomy suggests that restoration of an anatomically reduced joint in conjunction with repair or reconstruction of the osseous and soft tissue structures optimizes outcome. Special consideration should be given to repair of the radial styloid, intercarpal ligaments, and radiocarpal capsuloligamentous complex. The authors report 2 patients with radiocarpal fracture-dislocations in which reduction and stabilization of the carpus was achieved using suture anchor fixation of the volar extrinsic radiocarpal ligaments.

Wrist anatomy and biomechanics

Anatomic and biomechanical research of the wrist has yielded a substantial amount of information that improves our basic knowledge of carpal morphology and function of the wrist and provides information to better assess and improve treatment(s) for various problems of the wrist joint. A precise knowledge of the anatomy and biomechanics of the wrist is useful not only for diagnosis of traumatic ligamentous injuries or degenerative change of the wrist joint but also for treatment for wrist dysfunction.

Carpal tunnel syndrome caused by volar dislocation of the lunate in a patient with rheumatoid arthritis

We report a case of carpal tunnel syndrome caused by volar dislocation of the lunate in a patient with rheumatoid arthritis. A 74-year-old woman complained of numbness in her fingers. Carpal tunnel syndrome was diagnosed, and carpal tunnel release was performed. However, the symptoms recurred. Three-dimensional computed tomography and magnetic resonance imaging revealed volar dislocation of the lunate and synovitis around the distal radioulnar joint, respectively. Resection of the lunate and the Sauvé-Kapandji procedure were effective.