A kinematic study of luno-triquetral dissociations

Outcomes Following Surgical Interventions for Isolated Lunotriquetral Interosseous Ligament Injuries: A Systematic Review

Ulnar-sided wrist pain can be attributed to various bony and ligamentous structures. The purpose of this review is to compare outcomes following surgical interventions for isolated lunotriquetral (LT) interosseous ligament injuries in adults. We assessed 202 procedures from 9 retrospective case series studies of low to moderate quality based on the Structured Effectiveness Quality Evaluation Scale. The comparative outcomes (ie, range of motion, pain, strength, quality of life, complications, return to work, and patient satisfaction) were aggregated and categorized under arthrodesis, capsulodesis, ligament repairs and reconstruction, and ulna shortening osteotomy procedures. Although the comparison of outcomes was largely inconclusive due to the heterogeneity and the omission of preoperative characteristic data, we did observe higher complications and reoperation rates post LT arthrodesis. It is recommended that all outcomes be standardized and presented uniformly with best practices developed to better characterize the injury's severity and integrity in future studies.

Carpal dislocations

Carpal dislocations result from sequential disruption of the complex relationship between the bones and ligaments of the wrist. Injuries to the carpus occur via predictable mechanisms, an understanding of which is critical to identify and treat these frequently missed patterns of injury and to avoid the sequela of chronic instability. Lunate dislocations are by far the most common, but isolated dislocation of other carpal bones can also occur. Open reduction and internal fixation still remains the gold standard for treatment regardless of the debate around the specific approaches. These high-energy injuries are associated with significant long-term morbidity even when identified promptly and appropriately treated. This review will focus on the evaluation and management of common forms of carpal dislocations.

Augmented reality-based surgical guidance for wrist arthroscopy with bone-shift compensation

BACKGROUND AND OBJECTIVES

Intraoperative joint condition is different from preoperative CT/MR due to the motion applied during surgery, inducing an inaccurate approach to surgical targets. This study aims to provide real-time augmented reality (AR)-based surgical guidance for wrist arthroscopy based on a bone-shift model through an in vivo computed tomography (CT) study.

METHODS

To accurately visualize concealed wrist bones on the intra-articular arthroscopic image, we propose a surgical guidance system with a novel bone-shift compensation method using noninvasive fiducial markers. First, to measure the effect of traction during surgery, two noninvasive fiducial markers were attached before surgery. In addition, two virtual link models connecting the wrist bones were implemented. When wrist traction occurs during the operation, the movement of the fiducial marker is measured, and bone-shift compensation is applied to move the virtual links in the direction of the traction. The proposed bone-shift compensation method was verified with the in vivo CT data of 10 participants. Finally, to introduce AR, camera calibration for the arthroscope parameters was performed, and a patient-specific template was used for registration between the patient and the wrist bone model. As a result, a virtual bone model with three-dimensional information could be accurately projected on a two-dimensional arthroscopic image plane.

RESULTS

The proposed method was possible to estimate the position of wrist bone in the traction state with an accuracy of 1.4 mm margin. After bone-shift compensation was applied, the target point error was reduced by 33.6% in lunate, 63.3% in capitate, 55.0% in scaphoid, and 74.8% in trapezoid than those in preoperative wrist CT. In addition, a phantom experiment was introduced simulating the real surgical environment. AR display allowed to expand the field of view (FOV) of the arthroscope and helped in visualizing the anatomical structures around the bones.

CONCLUSIONS

This study demonstrated the successful handling of AR error caused by wrist traction using the proposed method. In addition, the method allowed accurate AR visualization of the concealed bones and expansion of the limited FOV of the arthroscope. The proposed bone-shift compensation can also be applied to other joints, such as the knees or shoulders, by representing their bone movements using corresponding virtual links. In addition, the movement of the joint skin during surgery can be measured using noninvasive fiducial markers in the same manner as that used for the wrist joint.

The Dorsal Ligament Complex: A Cadaveric, Histology, and Imaging Study

PURPOSE

The distinction between the dorsal intercarpal (DIC) and dorsal scaphotriquetral (DST) ligaments is imprecise and unclear in the literature. The purpose of our cadaveric study was to define the origins, insertions, and anatomic relationships of the dorsal wrist ligaments and relate these anatomic findings to magnetic resonance imaging (MRI) scans and histology.

METHODS

The study included 17 unmatched fresh-frozen cadaveric specimens (7 male and 10 female), with a mean age of 67.1 years (range, 48-86 years). Wrists with arthritis or carpal malalignment were excluded. Ligaments were dissected and insertion sites were recorded in the radioulnar (width) and proximodistal (length) dimensions, centered at the midpoints of the insertion. Three cadaveric specimens underwent a histologic analysis to demonstrate ligament composition and insertion sites. Three additional cadavers underwent MRI, from which 3-dimensional models were built to model ligament topography.

RESULTS

The conjoined triquetral insertion of the DIC, DST, and dorsal radiocarpal (DRC) measured 88.5 ± 6.4 mm². In each specimen, there were 2 distinct deep and superficial components of intercarpal fibers. The deep component inserted on the lunate with an area of 59.0 ± 5.0 mm². The deep and superficial components diverged as they coursed radially. The superficial component proceeded to the scaphoid ridge, trapezium, and trapezoid, whereas the deep component inserted on the proximal row. The deep fibers blended distally from their lunate insertion with the DST, forming a robust, 2.9 ± 0.8-mm wide extension over the dorsal capitate. The DRC inserted on the lunate, proximal to the DIC and DST insertions, with an area of 23.9 ± 5.4 mm².

CONCLUSIONS

The dorsal ligament complex forms a firm link across the proximal carpal row and the DST provides extension of the proximal row over the capitate.

CLINICAL RELEVANCE

This information can guide surgeons while performing a dorsal approach to the wrist and repairing traumatic ligament disruption.

LT Ligament Tears

Lunotriquetral (LT) ligament injuries are uncommon, however, should be considered in patients with ulnar-sided wrist pain. LT injuries are often associated with other injuries but can occur in isolation. Understanding the anatomy and pathomechanics will aid in making the diagnosis. Similar to other injuries, a thorough history and focused physical examination is critical. Radiographs may show normal findings; however, advanced imaging can support the diagnosis. Arthroscopy remains the gold standard for diagnosis. Most patients do well with conservative management; however, injury acuity and severity will direct surgical management. Anatomy, pathophysiology, and treatment options are discussed.

Carpal Instability: II. Imaging

Beyond clinical examination, the various forms of carpal instability are assessed with radiologic methods and arthroscopy. For this purpose, the imaging demand for spatial and contrast resolution is particularly high because of the small ligamentous structures involved. The entities of carpal instability are classified into degrees of severity. Early (dynamic) forms of instability can either be indirectly detected with X-ray stress views and cineradiography or by direct visualization of ruptured ligaments in high-resolution magnetic resonance (MR) imaging and MR or computed tomography (CT) arthrography, with the latter the standard of reference in imaging. Advanced (static) forms of carpal instability are sufficiently well detected on radiographs; visualization of early carpal osteoarthritis is superior on CT. To prevent disability of the hand, the radiologist has to provide an early and precise diagnosis. This case-based review highlights the imaging procedures suitable for detection and classification of carpal instability.

Carpal Instability: I. Pathoanatomy

The pathoanatomy of carpal instability is multifactorial and usually complex. A thorough medical history and clinical examination are essential, as well as profound knowledge of the specific instability patterns. The stability of the wrist is ensured by the carpal joint surfaces, by intact intra-articular (particularly the scapholunate interosseous ligament) and intracapsular ligaments, and by crossing extensor and flexor tendons, the latter making the proximal carpal row an "intercalated segment." An important classification feature is the distinction between dissociative and nondissociative forms of carpal instability. Among others, scapholunate dissociation, lunotriquetral dissociation, midcarpal instability, and ulnar translocation are the most common entities. Early forms of instability are considered dynamic. In the natural course, static instability of the wrist and osteoarthritis will develop. This review focuses on the pathoanatomical fundamentals of the various forms of carpal instability.

MRI of the Wrist Ligaments

Technological advances in magnetic resonance imaging (MRI) have improved radiologists' ability to evaluate wrist ligaments. MRI interpretation often guides clinical management. This article aims to review the normal and pathologic appearance of intrinsic and extrinsic wrist ligaments with a focus on MRI. Variant anatomy, imaging pearls, and clinical significance are also discussed. Special attention is paid to key wrist ligaments that play a role in carpal stability.

Narrative Review of Ligamentous Wrist Injuries

Ligamentous wrist injuries are common occurrences that require complex anatomical mastery and extensive understanding of diagnostic and treatment modalities. The purpose of this educational review article is to delve into the most clinically relevant wrist ligaments in an organized manner to provide the reader with an overview of relevant anatomy, function, clinical examination findings, imaging modalities, and options for management. Emphasis is placed on elucidating reported diagnostic accuracies and treatment outcomes to encourage evidence-based practice.

Dorsal Bone–Ligament–Bone Reconstruction of Chronic Lunotriquetral Instability: Biomechanical Testing

Purpose

Lunotriquetral (LT) instability is uncommon and few biomechanical analyses of the condition exist. For chronic LT instabilities, arthrodesis has long been the treatment of choice but has a high risk for nonunion. The aim of this study was to evaluate an alternative treatment option using a bone–ligament–bone graft in a cadaver model and compare it with a conventional arthrodesis.

Methods

We used 10 cadaveric forearms with different loading positions. We employed computed tomography scans to evaluate the LT joint. Scans were performed with the joint intact after we sectioned the dorsal LT ligament and the palmar LT ligament. The joints were then reconstructed using a bone–ligament–bone graft from the capitate–hamate joint as well as with a compression screw simulating arthrodesis. The joints were then rescanned and 3-dimensional analysis was performed using specialized 3-dimensional software.

Results

Sectioning the dorsal part of LT ligament had little effect on kinematics; however, additional division of the palmar LT ligament resulted in increased mobility. Restoration of physiological kinematics could be partially achieved after bone–ligament–bone reconstruction. Arthrodesis showed increased intercarpal motion in the adjacent scapholunate and lunocapitate joints compared with the bone–ligament–bone reconstruction.

Conclusions

The bone–ligament–bone reconstruction displayed physiologic carpal kinematics in the adjacent joints compared with arthrodesis. It provided enough stability but still some mobility in the LT joint to be able to use it as a treatment modality for chronic LT instability without the risk for nonunion. Decreased intercarpal motion was not statistically significant although there appeared to be a trend toward it.

Type of study/level of evidence

Therapeutic IV.

Anatomy and injuries of the pediatric wrist: beyond the basics

Ligamentous injuries of the pediatric wrist, once thought to be relatively uncommon, are increasingly recognized in the context of acute high-energy mechanism trauma and chronic axial loading, including those encountered in both recreational and high-performance competitive sports. Recent advances in MR-based techniques for imaging the pediatric wrist allow for sensitive identification of these often radiographically occult injuries. Detailed knowledge of the intrinsic and supportive extrinsic ligamentous complexes, as well as normal developmental anatomy and congenital variation, are essential to accurately diagnose injuries to these structures. Early identification of ligamentous injury of the pediatric wrist is essential within the conservative treatment culture of modern pediatric orthopedics because treatment of these lesions often necessitates surgery, and outcomes often depend on early and sometimes aggressive intervention. In this article, we review MR arthrogram technique and pediatric wrist anatomy, and correlate appearances on MR and selected ligamentous pathologies of the pediatric wrist.

Association of lunate morphology, sex, and lunotriquetral interosseous ligament injury with radiologic measurement of the capitate-triquetrum joint

OBJECTIVE

Radiologic presentation of carpal instability at the radial side of the carpus, e.g. scapholunate diastasis following scapholunate interosseous ligament injury, has been studied extensively. By comparison, presentation at the ulnar-sided carpus has not. The purpose of this study was to assess the effects of lunate morphology, sex, and lunotriquetral interosseous ligament (LTIL) status on the radiologic measurement of the capitate-triquetrum joint (C-T distance). Further, we sought to evaluate the diagnostic accuracy of C-T distance for assessing LTIL injuries.

MATERIALS AND METHODS

We retrospectively identified 223 wrists with wrist radiographs and MR arthrograms with contrast injection. Data collected included sex, lunate morphology and LTIL status from MR arthrography, and C-T distance from radiography. The effects of lunate morphology, sex, and LTIL injury status on C-T distance were evaluated using generalized linear models. Diagnostic performance of C-T distance was assessed by the area under receiver-operator characteristic curve (AUROC).

RESULTS AND CONCLUSION

Lunate morphology, sex, and LTIL injury status all had significant effects on C-T distance; wrists with type II lunates, men, and wrists with LTIL injuries had greater C-T distances than wrists with type I lunates, women, and wrists without LTIL injuries, respectively (p < 0.01). The diagnostic value of the C-T distance for identifying patients with full-thickness LTIL tears was sufficient for women with type I (AUROC = 0.67) and type II lunates (0.60) and good for men with type I (0.72) and type II lunates (0.77). The demonstrated influence of LTIL status on C-T distance supports the use of C-T distance as a tool in assessing for full-thickness LTIL tears.

[Ligament injuries of the wrist]

The distal radioulnar joint, the triangular fibrocartilage complex (TFCC) and the wrist are stabilized by many ligaments allowing not only a wide range of motion but also providing sufficient stability. The complex arrangement of carpal ligaments and prosupination around the forearm joint enables multiaxial motion patterns. In the wrist, intra-articular ligaments can be differentiated from extra-articular capsular ligaments as well as intrinsic and extrinsic ligament courses. Imaging is essential for classification of dynamic and static instability patterns. This review article illustrates the ligamentous anatomy of the wrist, the symptoms of carpal instability as well as the diagnostic capability of projection radiography, cinematography, computed tomography (CT) arthrography, magnetic resonance imaging (MRI) and MR arthrography.

Inestabilidad lunopiramidal

Históricamente, la inestabilidad en el lado radial de la muñeca ha recibido mucha más atención que la inestabilidad en el lado ulnar, a pesar de ser una patología relativamente frecuente. Como consecuencia de ello, suele darse un retraso en el diagnóstico correcto y el tratamiento apropiado. Las lesiones del ligamento lunopiramidal pueden ser parciales o completas, y estas últimas pueden estar asociadas a lesión de los estabilizadores secundarios. Cuando se lesionan estos estabilizadores es cuando se produce una inestabilidad estática del carpo conocida como Volar Intercalated Segmentary Instability (VISI). Entre los test clínicos más utilizados para detectar una inestabilidad del ligamento lunopiramidal están el Ballottement test, descrito por Reagan, y el Shear test, descrito por Kleinman, aunque ambos poseen una sensibilidad y una especificidad bajas. Para el diagnóstico de estas lesiones se emplean técnicas como la radiografía simple (que suele ser normal si no hay una inestabilidad estática del carpo), la artrografía y la RMN, entre otras, aunque el gold standard lo constituye la artroscopia de muñeca. No existe un consenso en cuanto al tipo de tratamiento óptimo, ya que la mayoría de los estudios publicados son retrospectivos de nivel iv sin medidas objetivas estandarizadas mediante instrumentos validados. Además, en su mayoría describen los resultados del tratamiento tardío, ya que no se suelen diagnosticar en la fase aguda. Dentro de los tratamientos descritos se encuentran el tratamiento artroscópico (desbridamiento/termocoagulación asociados o no a estabilización con agujas de Kirscher), la reparación abierta, la reconstrucción del ligamento y la artrodesis del ligamento lunopiramidal.

Understanding carpal instability: a radiographic perspective

The wrist is disposed to a variety of instability patterns owing to its complex anatomical and biomechanical properties. Various classification schemes have been proposed to describe the different patterns of carpal instability, of which the Mayo classification is the most commonly used. Understanding the concepts and pertinent terminology of this classification scheme is important for the correct interpretation of images and optimal communication with referring physicians. Standard wrist radiographs are the first line of imaging in carpal instability. Additional information may be obtained with the use of stress radiographs and other imaging modalities.

Subject-Specific Carpal Ligament Elongation in Extreme Positions, Grip, and the Dart Thrower's Motion

This study examined whether the radiocarpal and dorsal capsular ligaments limit end-range wrist motion or remain strained during midrange wrist motion. Fibers of these ligaments were modeled in the wrists of 12 subjects over multiple wrist positions that reflect high demand tasks and the dart thrower's motion. We found that many of the volar and dorsal ligaments were within 5% of their maximum length throughout the range of wrist motion. Our finding of wrist ligament recruitment during midrange and end-range wrist motion helps to explain the complex but remarkably similar intersubject patterns of carpal motion.

Functional kinematics of the wrist

The purpose of this article is to review past and present concepts concerning functional kinematics of the healthy and injured wrist. To provide a context for students of the wrist, we describe the progression of techniques for measuring carpal kinematics over the past century and discuss how this has influenced today's understanding of functional kinematics. Next, we provide an overview of recent developments and highlight the clinical relevance of these findings. We use these findings and recent evidence that supports the importance of coupled motion in early rehabilitation of radiocarpal injuries to develop the argument that coupled motion during functional activities is a clinically relevant outcome; therefore, clinicians should develop a framework for its dynamic assessment. This should enable a tailored and individualized approach to the treatment of carpal injuries.

Diagnosis and Treatment of Acute Lunotriquetral Ligament Injuries

Isolated acute lunotriquetral (LT) injuries are an uncommon diagnosis in hand surgery. Diagnosis is aided by a high index of suspicion when pain is localized over the LT joint. Standard radiographs show typically normal findings, leading to advanced diagnostic investigations, including MRI and wrist arthroscopy. Standard treatment options for acute LT injuries include immobilization, arthroscopy, and direct open LT repair.

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.

Physical Examination of the Wrist: Useful Provocative Maneuvers

Chronic wrist pain resulting from partial interosseous ligament injury remains a diagnostic dilemma for many hand and orthopedic surgeons. Overuse of costly diagnostic studies including magnetic resonance imaging, computed tomography scans, and bone scans can be further frustrating to the clinician because of their inconsistent specificity and reliability in these cases. Physical diagnosis is an effective (and underused) means of establishing a working diagnosis of partial ligament injury to the wrist. Carefully performed provocative maneuvers can be used by the clinician to reproduce the precise character of a patient's problem, reliably establish a working diagnosis, and initiate a plan of treatment. Using precise physical examination techniques, the examiner introduces energy into the wrist in a manner that puts load on specific support ligaments of the carpus, leading to an accurate diagnosis. This article provides a broad spectrum of physical diagnostic tools to help the surgeon develop a working diagnosis of partial wrist ligament injuries in the face of chronic wrist pain and normal x-rays.

Role of the extensor carpi ulnaris in the stabilization of the lunotriquetral joint. An experimental study

STUDY DESIGN

Experimental laboratory-based research in biomechanics.

INTRODUCTION

The mechanisms by which some lunotriquetral (LTq) ligament disruptions remain stable are not known.

PURPOSE OF THE STUDY

To investigate the contribution of muscles in preventing carpal destabilization when the LTq ligaments are torn.

METHODS

Ten fresh cadaver wrists, set vertical in a jig, were isometrically loaded through five wrist motor tendons. Changes in carpal alignment secondary to the application of loads were monitored by a Fastrak™ electromagnetic motion tracking device, before and after sectioning the LTq ligaments.

RESULTS

After LTq ligaments sectioning, wrist loading forced the triquetrum into flexion (5.4° average) and supination (2.9 ). The only muscle capable of extending and pronating the collapsed triquetrum was the extensor carpi ulnaris (ECU).

CONCLUSIONS

Inadequate ECU muscle function is an important destabilizing factor in LTq deficient wrists. Dynamic LTq instabilities may benefit from proprioceptionally training the ECU muscle, while avoiding carpal supination torques.

Fracture-dislocations of the carpus: perilunate injury

The progressive perilunar instability model described by Mayfield is still used to predict the pattern of injury. Diagnosis of injury and clinical and radiographic findings depend on the pattern of injury. Open procedures are preferred for anatomic reduction after initial closed reduction is performed for acute injuries. A dorsal, volar, or combined dorsal/volar approach may be necessary and is often decided by surgeon preference. Loss of motion and diminished grip strength are common consequences despite appropriate treatment. Successful outcomes depend on time to treatment, open or closed nature of injury, extent of chondral damage, residual instability, and fracture union.

Immunohistochemical composition of the human lunotriquetral interosseous ligament

PURPOSE

The human lunotriquetral ligament (LTL) is a functionally important intrinsic hand ligament, which is assumedly subjected to insertion angle changes at the entheses during movement. To clarify whether the current model of the ligament's mechanical environment is reflected in its structural composition, we determined the regional distribution of extracellular matrix-related antigens.

METHODS

The extracellular matrix was immunohistochemically investigated in 12 LTLs from both wrists of 6 human donors (Mean age: 60 y).

RESULTS

The dorsal, proximal, and volar portions of the ligament immunolabeled for type I, III collagen and versican. Both entheses labeled strongly for type II collagen, aggrecan, and link protein and were distinctly cartilaginous. The ligament midsubstance was positive for collagen II in 30%, for aggrecan in 40%, and for keratocan and lumican in 100% of specimens. In contrast, keratocan and lumican were absent from the fibrocartilaginous entheses and the articular cartilage. Ligament insertion at a carpal bone occurs either directly through fibrocartilage or indirectly through a bilayered configuration of fibrocartilage and hyaline-like cartilage. The hyaline-like cartilage is continuous with the neighboring articular cartilage.

CONCLUSIONS

The LTL has an extracellular matrix comparable with that of ligaments experiencing a combination of tensile and shear/compressive load at the attachment sites. All regions of the LTL exhibit fibrocartilaginous entheses; purely fibrous attachment sites are rare. The ligament midsubstance shows a more fibrous phenotype than the entheses and expresses keratocan and lumican, which previously have not been recorded in any human hand ligament.

The mechanism of ulnar-sided perilunate instability of the wrist: a cadaveric study and 6 clinical cases

PURPOSE

To define the mechanism of ulnar-sided perilunate instability using a cadaveric model and correlate these biomechanical findings with 6 clinical cases.

METHODS

We mounted 16 fresh-frozen human cadaver arms and loaded them to failure in extension and radial deviation, recreating our understanding of the injury mechanism leading to ulnar-sided perilunate instability of the wrist. After testing, we examined the wrists clinically and radiographically. We identified, examined, and treated 6 patients with ulnar-sided perilunate instability over a period of 5 years. Based on these data, we propose a 3-stage mechanism for ulnar-sided perilunate instability of the wrist.

RESULTS

In 13 of 16 specimens, we observed failure of ulnotriquetral, ulnolunate, and ulnocapitate ligaments as well as the dorsal scaphotriquetral and dorsal radiotriquetral ligaments. In 11 of these 13, the lunotriquetral interosseous ligament was disrupted, and in 2 of the 11, a dorsal perilunate dislocation occurred. After comparing these laboratory findings with clinical findings in 6 patients with ulnar-sided perilunate instability, we propose the following 3-stage mechanism for ulnar-sided perilunate instability: stage 1, disruption of the lunotriquetral interosseous ligament; stage 2, stage 1 plus disruption of the ulnolunate, ulnotriquetral, and ulnocapitate ligaments as well as the dorsal scaphotriquetral and radiotriquetral ligaments; and stage 3, stage 2 with progression of the injury through the midcarpal joint plus disruption of the scapholunate and radioscapholunate ligaments, potentially resulting in a dorsal perilunate dislocation.

CONCLUSIONS

We describe a 3-stage mechanism of ulnar-sided perilunate ligamentous wrist injury that can lead to dorsal perilunate dislocation. We recommend considering ulnar-sided perilunate instability of the wrist in patients with ulnar wrist pain after a fall on the outstretched wrist.

CLINICAL RELEVANCE

Ulnar-sided wrist injury can lead to subtle forms of perilunate instability.

Scaphoid and lunate movement in different ranges of carpal radioulnar deviation

PURPOSE

We aimed to investigate scaphoid and lunate movement in radial deviation and in slight and moderate ulnar deviation ranges in vivo.

METHODS

We obtained computed tomography scans of the right wrists from 20° radial deviation to 40° ulnar deviation in 20° increments in 6 volunteers. The 3-dimensional bony structures of the wrist, including the distal radius and ulna, were reconstructed with customized software. The changes in position of the scaphoid and lunate along flexion-extension motion (FEM), radioulnar deviation (RUD), and supination-pronation axes in 3 parts--radial deviation and slight and moderate ulnar deviation--of the carpal RUD were calculated and analyzed.

RESULTS

During carpal RUD, scaphoid and lunate motion along 3 axes--FEM, RUD, and supination-pronation--were the greatest in the middle third of the measured RUD (from neutral position to 20° ulnar deviation) and the smallest in radial deviation. Scaphoid motion along the FEM, RUD, and supination-pronation axes in the middle third was about half that in the entire motion range. In the middle motion range, lunate movement along the FEM and RUD axes was also the greatest.

CONCLUSIONS

During carpal RUD, the greatest scaphoid and lunate movement occurs in the middle of the arc--slight ulnar deviation--which the wrist frequently adopts to accomplish major hand actions. At radial deviation, scaphoid and lunate motion is the smallest.

Dorsal radiocarpal ligament capsulodesis for chronic dynamic lunotriquetral instability

PURPOSE

Chronic lunotriquetral (LT) instability (persisting >3 months after injury) can be treated with a variety of surgical methods (LT fusion, ligament repair or reconstruction, or arthroscopic debridement), with varying degrees of success. We retrospectively evaluated the results of dorsal capsulodesis using the dorsal radiocarpal ligament in an attempt to reinforce the dorsal LT interosseous ligament in patients with chronic dynamic LT instability.

METHODS

A total of 11 patients (mean age, 37 years) with persistent posttraumatic wrist pain and weakness were diagnosed with dynamic LT instability (positive LT ballotment test, disruption of Gilula's lines or volar intercalated segment instability deformity on stress radiography, arthroscopic findings of Geissler grade 3, or 4 LT tears). They were treated consecutively with dorsal capsulodesis. We used subjective and functional outcome measures to evaluate the results.

RESULTS

The mean follow-up period was 31 months (range, 12-65 months). The postoperative visual analog pain score and Mayo wrist score were significantly improved compared with their preoperative values. The average grip strength increased by 5 kg, and the average range of wrist flexion was reduced by 3 degrees .

CONCLUSIONS

In this small series, in the short term, dorsal radiocarpal ligament capsulodesis reduced pain and instability and improved function in patients with chronic dynamic LT instability.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Apparent visi deformity: periscaphoid perilunate dissociation - a case report

We report a case of carpal instability complex, which presented apparent volar intercalated segmental instability (VISI) caused by acute injury. Proper diagnosis and treatment by ligament repair and Kirschner wire fixation yielded good clinical results.

Incidence of dorsal radiocarpal ligament tears in the presence of other intercarpal derangements

PURPOSE

The aim of this study was to examine the incidence of dorsal radiocarpal ligament (DRCL) tears in patients who underwent wrist arthroscopy for chronic pain.

METHODS

A chart review was performed of 64 patients who underwent diagnostic wrist arthroscopy for wrist pain. Interosseous ligament instability/tears were graded according to the Geissler classification. Tears of the triangular fibrocartilage complex (TFCC) and other intracarpal pathology were documented. Any DRCL tears were noted.

RESULTS

The average duration of wrist pain before arthroscopy was 20 months. There were 35 of 64 patients with DRCL tears. The average duration of wrist pain before treatment was 20 months (range, 4 to 60 months). There were 5 patients who had an isolated DRCL tear. Thirteen patients in this series had a scapholunate interosseous ligament (SLIL) derangement; 7 of 13 also had a DRCL tear. Seven patients had a lunotriquetral interosseous ligament (LTIL) derangement; 2 of 7 also had a DRCL tear. Two patients had a capitohamate ligament tear; 1 of these patients also had a DRCL tear. There were 7 patients with a solitary TFCC tear; 6 of 7 were in association with a DRCL tear. One patient had a chronic ulnar styloid nonunion and a DRCL tear. Two or more lesions were present in 23 patients; DRCL tears were present in 12 of 23 patients. Three patients had generalized arthrofibrosis; 1 had a volar ganglion and 2 had a normal examination. None of these were associated with DRCL tears.

CONCLUSIONS

DRCL tears are commonly seen with injuries to the SLIL, the LTIL, and the TFCC. Isolated DRCL tears should be treated with an arthroscopic repair. DRCL repairs in the presence of other intracarpal pathologies requires further study.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

The incidence of dorsal radiocarpal ligament tears in patients having diagnostic wrist arthroscopy for wrist pain

PURPOSE

The goal of this study was to examine the incidence of dorsal radiocarpal ligament (DRCL) tears in patients having diagnostic arthroscopy for chronic wrist pain.

METHODS

A chart review was performed of 64 patients who had diagnostic wrist arthroscopy for chronic wrist pain that was refractory to conservative measures. For each case, interosseous ligament instability/tears were graded according to the Geissler classification. Tears of the triangular fibrocartilage complex and the presence or absence of a DRCL tear were noted.

RESULTS

There were 35 of 64 wrists (in 64 patients) with DRCL tears. The average duration of wrist pain prior to treatment was 20 months. Only 10 patients could recall a specific injury. Five patients had an isolated DRCL tear. A scapholunate interosseous ligament injury was identified in 13 patients, of whom 7 had a concomitant DRCL tear. A lunotriquetral interosseous ligament injury was present in 7 patients, of whom 2 had a concomitant DRCL tear. Two patients had a capitohamate ligament tear: 1 of these patients had a DRCL tear. There were 7 patients with a solitary triangular fibrocartilage complex tear: 6 of 7 were in association with a DRCL tear. One patient had a chronic ulnar styloid nonunion and a DRCL tear. Two or more lesions were present in 23 patients; DRCL tears were present in 12.

CONCLUSIONS

DRCL tears are commonly seen with injuries to the primary wrist stabilizers. Recognition of this condition and further research into treatment methods are needed.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.

Management of wrist injuries

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand the anatomy and the biomechanical properties of the wrist. 2. Understand the standard examination process for wrist injuries. 3. Accurately diagnose common wrist conditions. 4. Establish a management plan for wrist problems.

BACKGROUND

Although common, wrist injuries and conditions are difficult to treat if the physician is unfamiliar with their management.

METHODS

Wrist anatomy and kinematics are discussed. Physical and radiographic examinations that are mandatory for diagnosing wrist conditions are presented. Common wrist injuries are reviewed.

RESULTS

Understanding the anatomy and kinematics of the wrist is important in diagnosing and treating wrist conditions and in predicting outcomes after treatment. Physical examination of the wrist requires an understanding of the surface anatomy and a number of specific maneuvers. Physicians should also be familiar with other diagnostic tests, which include radiography, arthrography, computed tomography, magnetic resonance imaging, and arthroscopy.

CONCLUSIONS

Physicians who treat wrist injuries should be able to establish an adequate management plan for common wrist injuries and conditions and be able to predict outcomes based on these treatment plans.

Distal radioulnar joint arthroscopy and the volar ulnar portal

Pain on the ulnar side of the wrist remains poorly understood. As attention has shifted toward the myriad causes of ulnar-sided wrist pain, the utility of viewing the wrist from a volar ulnar (VU) perspective has emerged. Lunotriquetral ligament tears have been implicated in the pathogenesis of volar intercalated segmental instabilities. They often originate in the palmar subregion, which is most important for maintaining stability. These tears are difficult to visualize through the 4, 5, or 6R portals. They are well seen through a VU portal, and the direct line of sight facilitates debridement. The VU portal has potential use in the arthroscopic diagnosis and treatment of patients with injuries to the ulnar sling mechanism. It aids in triangular fibrocartilage repairs especially those involving the dorsal aspect between the ulnar styloid and the radial insertion, because the proximity of the 4, 5, and 6R portals makes triangulation of the instruments difficult. Although arthroscopy of the dorsal aspect of the distal radioulnar joint has been well described, it has largely remained a curiosity, with few clinical indications. Recent biomechanical studies have highlighted the importance of the deep attachment of the triangular fibrocartilage complex in maintaining distal radioulnar joint stability. The volar distal radioulnar portal is useful for assessing the foveal attachment. It may be used where there is the suspicion of a peripheral triangular fibrocartilage detachment due to a loss of its normal tension despite the lack of a visible tear during radiocarpal arthroscopy. The judicious use of these portals deserves consideration for inclusion as part of a thorough arthroscopic examination of selected patients with ulnar-sided wrist pain.

Carpal kinematics after proximal row carpectomy

PURPOSE

Proximal row carpectomy (PRC) is a clinically useful motion-sparing procedure for the treatment of certain degenerative conditions of the wrist. Clinical outcome studies after PRC have shown that wrist flexion-extension averages approximately 60% of that of the contralateral wrist. The purpose of this study was to determine how the kinematics of the wrist are altered after PRC.

METHODS

Eight fresh-frozen cadaver forearms were scanned with computed tomography before and after PRC. Forearms were scanned in 5 different wrist positions (neutral, extension, flexion, radial deviations, and ulnar deviation). Wrists were positioned dynamically and then held statically in a custom fixture through forces applied to the 4 wrist flexor/extensor tendon groups. Three-dimensional computer models of the radius, lunate, and capitate were generated from the computed tomographic images, and the kinematics of the capitate and lunate were calculated relative to the neutral position. For the intact wrist, the motion of the capitate was calculated relative to both the lunate (midcarpal motion) and the radius (overall wrist motion) and the motion of the lunate was calculated relative to the radius (radiocarpal motion). After PRC, only the movement of the capitate relative to the radius was calculated, which represents radiocapitate and overall wrist motion. All motions were plotted in 3 dimensions for purposes of qualitative visualization.

RESULTS

After PRC, the capitate articulated with the lunate fossa of the radius for all positions in all samples. Overall wrist motion decreased 28%, 30%, 40%, and 12% in flexion, extension, radial deviation, and ulnar deviation, respectively. Motion at the radiocarpal joint after PRC, however, was greater compared with motion at the radiocarpal and midcarpal joints of the intact wrist during flexion and extension. This was not the case in radial deviation because of impingement of the trapezoid on the radial styloid. In radial and ulnar deviation, motion of the capitate head changed from predominantly rotational in the intact wrist (midcarpal joint) to a combination of rotation and translation after PRC (radiocarpal joint).

CONCLUSIONS

Removal of the proximal carpal row decreased normal wrist flexion and extension. Although ulnar deviation was preserved, radial deviation was limited by impingement of the trapezoid on the radial styloid. Radiocapitate range of motion after PRC was greater than capitolunate range of motion in the intact wrists. Compared with previously published requirements, wrist range of motion observed after PRC was sufficient for activities of daily living.

Carpal osteoarthrosis

Despite improved understanding of carpal mechanics, increased awareness of intercarpal ligament injuries, and improved techniques for treating carpal instability, post-traumatic intercarpal osteoarthrosis remains a common problem. Osteoarthritis of the carpal bones, including scapholunate advance collapse wrist, scaphotrapeziotrapezoid arthritis, lunotriquetral arthritis, triquetrohamate arthritis, and pisotriquetral arthritis, follows specific unique patterns, but in each, the final common pathway leads to degenerative change. Injury or deformity leads to instability and altered kinematics, producing abnormal joint contact pressures. Cartilage injury and eventual degeneration of the join follow. The etiology, prevalence, and current evaluation and treatment of these conditions are of importance to hand surgeons.

Kinematics of the midcarpal and radiocarpal joint in flexion and extension: an in vitro study

PURPOSE

To apply carpal kinematic analysis using noninvasive medical imaging to investigate the midcarpal and radiocarpal contributions to wrist flexion and extension in a quasidynamic in vitro model.

METHODS

Eight fresh-frozen cadaver wrists were scanned with computed tomography in neutral, full flexion, and full extension. Body-mass-based local coordinate systems were used to track motion of the capitate, lunate, and scaphoid with the radius as a fixed reference. Helical axis motion parameters and Euler angles were calculated for flexion and extension.

RESULTS

Minimal out-of-plane carpal motion was noted with the exception of small amounts of ulnar deviation and supination in flexion. Overall wrist flexion was 68 degrees +/- 12 degrees and extension was 50 degrees +/- 12 degrees. In flexion, 75% of wrist motion occurred at the radioscaphoid joint, and 50% occurred at the radiolunate joint. In extension, 92% of wrist motion occurred at the radioscaphoid joint, and 52% occurred at the radiolunate joint. Midcarpal flexion/extension between the capitate and scaphoid was 0 degrees +/- 5 degrees in extension and 10 degrees +/- 13 degrees in flexion. Midcarpal flexion/extension between the capitate and lunate was larger, with 15 degrees +/- 11 degrees in extension and 22 degrees +/- 19 degrees in flexion.

CONCLUSIONS

The capitate and scaphoid tend to move together. This results in greater flexion/extension for the scaphoid than the lunate at the radiocarpal joint. The lunate has greater midcarpal motion between it and the capitate than the scaphoid does with the capitate. The engagement between the scaphoid and capitate is particularly evident during wrist extension. Out-of-plane motion was primarily ulnar deviation at the radiocarpal joint during flexion. These results are clinically useful in understanding the consequences of isolated fusions in the treatment of wrist instability.

Funktionelle Anatomie und Biomechanik des Karpus

The wrist is an exceedingly complex structure composed of several joints and a dedicated ligamentous system. Its functional principles allow a wide range of carpal motion and make the wrist remarkably resistant to external stress forces:The proximal carpal row serves as an intercalated link interposed between the static elements of both the forearm and the distal carpal row. Like a flexible place-holder, the proximal row synchronously adapts to the spatial and temporal requirements of the wrist. There are synergistic movement patterns including simultaneous flexion of the proximal row as the wrist is deviated radially and simultaneous extension during ulnar deviation. Together with pronosupination of the radioulnar joints, the combined radial/ulnar inclination and flexion/extension enable spherical, out-of-plane movements of the hand. Carpal function is best explained by the "model of a ring under tension."This review addresses the anatomy and the biomechanics of the wrist and illustrates systematic image analysis by using carpal lines and angles as well as indices of carpal height.

Clinical applications of volar portals in wrist arthroscopy

Volar portals for wrist arthroscopy have certain advantages over the standard dorsal portals for visualizing dorsal capsular structures as well as the palmar aspects of the carpal ligaments. The volar radial portal is relatively easy to use and is an ideal portal for evaluation of the dorsal radiocarpal ligament and the palmar aspect of the scapholunate interosseous ligament. The volar midcarpal portal may be considered as an occasional accessory portal for visualizing the palmar aspects of the capitate and hamate in cases of avascular necrosis or osteochondral fractures. The volar ulnar portal is especially useful for the viewing and debridement of palmar tears of the lunotriquetral ligament.

Carpal instability

This review addresses the pathoanatomical basics as well as the clinical and radiological presentation of instability patterns of the wrist. Carpal instability mostly follows an injury; however, other diseases, like CPPD arthropathy, can be associated. Instability occurs either if the carpus is unable to sustain physiologic loads ("dyskinetics") or suffers from abnormal motion of its bones during movement ("dyskinematics"). In the classification of carpal instability, dissociative subcategories (located within proximal carpal row) are differentiated from non-dissociative subcategories (present between the carpal rows) and combined patterns. It is essential to note that the unstable wrist initially does not cause relevant signs in standard radiograms, therefore being "occult" for the radiologic assessment. This paper emphasizes the high utility of kinematographic studies, contrast-enhanced magnetic resonance imaging (MRI) and MR arthrography for detecting these predynamic and dynamic instability stages. Later in the natural history of carpal instability, static malalignment of the wrist and osteoarthritis will develop, both being associated with significant morbidity and disability. To prevent individual and socio-economic implications, the hand surgeon or orthopedist, as well as the radiologist, is challenged for early and precise diagnosis.

Arthroscopic dorsal radiocarpal ligament repair

PURPOSE

The goal of this study was to determine if arthroscopic repair of a dorsal radiocarpal ligament (DRCL) tear is effective in ameliorating wrist pain.

TYPE OF STUDY

Retrospective study.

METHODS

A chart review was performed of 53 patients (56 wrists) who underwent wrist arthroscopy with use of a volar radial portal. There were 21 patients with DRCL tears. Mean follow-up was 16 months. Thirteen patients underwent arthroscopic DRCL repair and/or thermal shrinkage (5 repairs, 6 repair plus shrinkage, and 2 shrinkage). Lunotriquetral tears were treated with debridement and pinning. Triangular fibrocartilage (TFC) tears were debrided or repaired. Scapholunate ligament tears/instability were treated with capsulodesis.

RESULTS

The 4 patients who underwent repair of an isolated DRCL tear had excellent results with no or mild pain. All returned to their previous occupation. Dorsal capsulodesis was performed in 7 patients with 4 fair/poor results. Nine DRCL repairs/shrinkage were in association with other procedures for ulnar-sided pathology with 6 fair/poor results.

CONCLUSIONS

Tears of the DRCL are more common than previously suspected. They are best seen through a volar radial portal and are amenable to arthroscopic repair. DRCL tears appear to be part of a spectrum of radial and ulnar-sided carpal instability as evidenced by the frequent association with scapholunate ligament tears/instability or ulnar-sided pathology. Isolated DRCL tears can be solely responsible for wrist pain. Good results are obtained with arthroscopic repair of isolated DRCL tears. The presence of a DRCL tear when seen in combination with a scapholunate, lunotriquetral, or TFC tear connotes a greater degree and/or duration of carpal instability, and portends a poorer prognosis following treatment. Recognition of this condition and further research into treatment methods is needed.

LEVEL OF EVIDENCE

Level IV.

Tenodesis of the extensor carpi ulnaris for chronic, post-traumatic lunotriquetral instability

We describe a technique of soft-tissue reconstruction which is effective for the treatment of chronic lunotriquetral instability. Part of extensor carpi ulnaris is harvested with its distal attachment preserved. It is passed through two drill holes in the triquetrum and sutured to itself. This stabilises the ulnar side of the wrist.

We have reviewed 46 patients who underwent this procedure for post-traumatic lunotriquetral instability with clinical signs suggestive of ulnar-sided carpal instability. Standard radiographs were normal. All patients had pre-operative arthroscopy of the wrist at which dynamic lunotriquetral instability was demonstrated. A clinical rating system for the wrist by the Mayo clinic was used to measure the outcome. In 19 patients the result was excellent, in ten good, in 11 satisfactory and in six poor. On questioning, 40 (87%) patients said that surgery had substantially improved the condition and that they would recommend the operation. However, six (13%) were unhappy with the outcome and would not undergo the procedure again for a similar problem. There were six complications, five of which related to pisotriquetral problems. The mean follow-up was 39.1 months (6 to 100). We believe that tenodesis of extensor carpi ulnaris is a very satisfactory procedure for isolated, chronic post-traumatic lunotriquetral instability in selected patients. In those with associated pathology, the symptoms were improved, but the results were less predictable.

The effect of ulnar shortening on lunate and triquetrum motion--a cadaveric study

BACKGROUND

Ulnar shortening osteotomy is a widely used procedure for a number of pathologic conditions. However, there is little biomechanical data on its effect on the surrounding soft tissue structures. Therefore, the objective of this study was to determine the effects of progressive ulnar shortening on the distal radioulnar joint and the proximal carpal bones.

METHODS

The kinematics and strain between the ulnar styloid, lunate, and triquetrum were evaluated with varying supination and pronation forces. Six fresh-frozen cadaveric upper extremity specimens were tested after progressive ulnar shortening using a custom jig. Biomechanical measurements including strain and translation were made by evaluating the change in position of the digitizing markers on the carpal bones, radius and ulna.

FINDINGS

There were significant changes in marker positions with respect to intact specimens for each amount of shortening at the ulnar styloid (P<0.001), the lunate (P<0.001), and triquetrum (P<0.001). With progressive ulnar shortening, the strain data demonstrated that there was no significant change in lunato-triquetral strain, but demonstrated a significant increase in both ulno-triquetral and ulno-lunato strain (P<0.04).

INTERPRETATION

Progressive ulnar shortening increases ulno-triquetral and ulno-lunato strains with an ensuing reduction in motion between the carpal bones.

The role of the dorsal intercarpal ligament in dynamic and static scapholunate instability

PURPOSE

Scapholunate instability (SLI) is the most common carpal instability. Recent studies have suggested that the dorsal intercarpal (DIC) and the dorsal radiocarpal ligaments play an important role in stabilization of the scaphoid and lunate. Differences between dynamic SLI and static SLI with a dorsal intercalated segment instability (DISI) are clearly described in the clinical literature; however, there has never been a clear explanation of the anatomic differences. This study describes the role of the DIC in the development of dynamic and static SLI with DISI in a cadaver model.

METHODS

Five fresh cadavers were studied radiographically and by 3-dimensional digitization. Six increasing stages of instability were developed by sectioning progressively the following structures: the dorsal capsule, the palmar and proximal (membranous) portion of the scapholunate interosseous ligament, the DIC from its insertion on the scaphoid and trapezium, the dorsal scapholunate interosseous ligament from the scaphoid, the DIC ligament from its attachment on the lunate, and the lunotriquetral interosseous ligament.

RESULTS

The scaphoid position and the scapholunate gap changed significantly after sectioning the entire scapholunate interosseous ligament and DIC from the scaphoid when a 5-kg load was applied. The lunate position was unchanged in both the loaded and the unloaded conditions. After detaching the DIC from the lunate, both the scaphoid and lunate moved and the scapholunate gap increased significantly in both loaded and unloaded conditions and showed a DISI deformity.

CONCLUSIONS

This study describes an anatomic difference between dynamic and static scapholunate instability. Complete disruption of the scapholunate ligament did not result in the development of a static collapse of the lunate. The DIC had an important role in stabilizing the scaphoid and lunate and preventing DISI deformity. This study suggests that in the clinical setting the DIC ligament should be assessed intraoperatively and consideration should be given to repair and/or reconstruction of the DIC ligament attachments to both the scaphoid and the lunate.

The use of a volar ulnar portal in wrist arthroscopy

PURPOSE

The purpose of this study was to quantitatively describe the neurovascular relationships of a volar ulnar (VU) wrist arthroscopy portal. A second purpose was to evaluate whether the use of a VU portal identified additional pathology of the lunotriquetral ligament and ulnar sling mechanism that was not seen through the dorsal portals.

TYPE OF STUDY

This study was an anatomic study and retrospective chart review.

METHODS

Cadaver dissections established the neurovascular anatomy of the VU portal. Measurements were taken from the portal to the ulnar nerve and artery, the palmar cutaneous branch of the ulnar nerve, and the pronator quadratus. A dorsal capsulotomy was performed to assess the ligamentous interval. A chart review was performed of 23 patients in whom a volar ulnar portal was used. Intraoperative pathology that was identified through the VU portal but was not visible through a dorsal portal was recorded. Postoperative neurovascular complications were noted.

RESULTS

The portal was generally > 5 mm radial to the ulnar neurovascular bundle, but no true internervous plane was seen. Tears of the palmar aspect of the lunotriquetral ligament were seen in 7 patients. One patient had a triangular fibrocartilage tear that extended into the dorsal radioulnar ligament.

CONCLUSIONS

This study provides a safe, standardized approach to the volar ulnar aspects of the radiocarpal joint, which is useful for evaluation of the ulnar sling mechanism and the dorsal radioulnar ligament. The VU portal aids in the diagnosis and debridement of tears involving the palmar aspect of the lunotriquetral ligament. The VU portal should be considered for inclusion in the arthroscopic examination of any patient with ulnar sided wrist pain.

LEVEL OF EVIDENCE

Level IV.

Capsuloligamentous restraints to dorsal and palmar carpal translation

PURPOSE

The purpose of this study was to determine biomechanically the relative contributions of the dorsal and palmar capsuloligamentous structures to dorsal and palmar carpal stability.

METHODS

Seven fresh-frozen cadaver specimens were tested using a testing machine (MTS, Eden Prairie, MN) with low loads applied perpendicular to the axis of the radial diaphysis. We determined the loads required to achieve dorsal and palmar translation of the carpus on the radius as palmar and dorsal ligaments and capsule were sectioned sequentially. The relative contributions of the dorsal and palmar capsuloligamentous structures to dorsal and palmar stability were determined.

RESULTS

The palmar structures provided a statistically significantly greater restraint (61%) to dorsal translation of the carpus than did the dorsal structures (2%). The palmar structures also provided a statistically greater restraint (48%) to palmar translation of the carpus than did the dorsal structures (6%).

CONCLUSIONS

The palmar capsuloligamentous structures provided greater restraint to both dorsal and palmar translation of the carpus. We suggest that surgeons consider repair or reconstruction of traumatic injuries to these structures.