Reverse Perilunate Injuries-The "Extended Scaphoid" Sign

Background  Reverse perilunate injuries (REPLI) are rare variants of the classic radial-sided perilunate injuries (PLI) whose mechanism was described by Mayfield in 1980. Classic radial-sided nontranscaphoid dorsal PLI invariably display a flexed, foreshortened position of the scaphoid on their initial posteroanterior (PA) and lateral radiographs. We observed that some dorsal perilunate dislocations displayed an extended position of the scaphoid on their initial radiographs. Our hypothesis is that this extended position of the scaphoid was associated with a REPLI pattern. Methods  The PA and lateral initial emergency radiographs of our specialized wrist surgery series of 114 dorsal pure ligamentous PLI (within a 186 cases series of PLI treated between 2004 and 2020) were reviewed as well as the available figures of the current REPLI literature. Results  A total of seven cases of cases within our dorsal PLI series displayed an extended position of the scaphoid on their initial PA and lateral radiographs, while 107 cases displayed a flexed, foreshortened position. The PA and lateral radiographs available in the REPLI literature displayed an extended position of the scaphoid, a lunotriquetral dissociation, and a dorsal dislocation of the capitate with respect to the lunate. Discussion  This study confirms our hypothesis. By contrast to the dorsal classic radial-sided pure ligamentous PLI pattern of scaphoid displacement (scaphoid flexed and foreshortened with scapholunate gap), the dorsal REPLI pattern displays an extended position of the scaphoid with scapholunate step-off and overlap rather than a gap. The combination of a lunotriquetral dissociation with a dorsal dislocation of the capitate from the lunate yet an extended position of the scaphoid with almost normal radioscaphoid relationships should raise a high suspicion for REPLI.

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.

Osteoarthritis of the Wrist: Pathology, Radiology, and Treatment

Osteoarthritis (OA) is a degenerative disease that can manifest in any synovial joint under certain conditions. It leads to destruction of articular cartilage and adjacent bone, as well as formation of osteophytes at the edges of afflicted joint surfaces. Regarding the wrist, typical degenerative arthritis affects particular joints at a specific patient age, due to asymmetric load distribution and repetitive microtrauma. However, in the presence of instability or systemic diseases, early-onset degeneration can also impair the range of motion and grip strength in younger patients. Although advanced stages of OA display characteristic signs in radiography, the detection of early manifestations frequently requires computed tomography or magnetic resonance imaging (in some cases with additional arthrography). If a wrist becomes unstable, timely diagnosis and precise treatment are essential to prevent rapid disease progression. Therefore, close collaboration between radiologists and hand surgeons is obligatory to preserve the carpal function of patients.

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.

Arthroscopic dorsal capsulodesis for isolated lunotriquetral interosseous ligament injuries

We assessed the outcomes of isolated lunotriquetral ligament injuries in ten patients who underwent arthroscopic dorsal capsulodesis. Data from patient records, radiologic images and arthroscopic video records were evaluated. The patients were evaluated for ulnar-sided wrist pain with history and physical examination. Preoperative radiographs and MRIs for pain aetiology were assessed. The patients underwent arthroscopic dorsal capsulodesis and were evaluated 29 months (range 19-45) after surgery. Nine patients returned to their original jobs. In one patient pain was aggravated with heavy activities. Mean scapholunate angle was 44°. There were significant improvements postoperatively in pinch and grip strength and MAYO wrist, patient-reported wrist evaluation and pain scores. The wrist flexion-extension and the radial ulnar deviation were significantly improved compared with the contralateral hand. We conclude that arthroscopic dorsal capsulodesis offers effective management for isolated lunotriquetral interosseous ligament injuries.Level of evidence: IV.

Imaging of Carpal Instabilities

Background The term “carpal instability” describes different debilitating wrist conditions, in which the carpus is unable to maintain its physiological range of motion and load transfer. Depending on the cause and location of the dysfunction, four groups can be defined: dissociative, non-dissociative, complex, and adaptive carpal instability. As the most common form by far, dissociative carpal instability can further be categorized as dorsal or palmar intercalated segment instability, contingent on the afflicted interosseous ligament.

Method This review article outlines the different entities of carpal instability, their pathophysiology, and their clinical presentation. It further discusses the diagnostic significance of different imaging methods as well as the established treatment options for each form of instability in context with the current literature.

Results and Conclusion Early detection and treatment of carpal instability are essential for preventing carpal osteoarthritis. Traumatic lesions of the scapholunate interosseous ligament are the most frequent cause of instability. They can occur in an isolated fashion or in context with other carpal injuries. While stress imaging and fluoroscopy facilitate the differentiation between dynamic and static forms of carpal instability, only MRI and CT/MR arthrography can directly reveal the extent of ligament discontinuity.

Key Points:

Citation Format

[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.

A biomechanical model of the wrist joint for patient-specific model guided surgical therapy: Part 2

An enhanced musculoskeletal biomechanical model of the wrist joint is presented in this article. The computational model is based on the multi-body simulation software AnyBody. Multi body dynamic musculoskeletal models capable of predicting muscle forces and joint contact pressures simultaneously would be valuable for studying clinical issues related to wrist joint degeneration and restoration. In this study, the simulation model of the wrist joint was used for investigating deeper the biomechanical function of the wrist joint. In representative physiological scenarios, the joint behavior and muscle forces were computed. Furthermore, the load transmission of the proximal wrist joint was investigated. The model was able to calculate the parameters of interest that are not easily obtainable experimentally, such as muscle forces and proximal wrist joint forces. In the case of muscle force investigation, the computational model was able to accurately predict the computational outcome for flexion and extension motion. In the case of force distribution of the proximal wrist joint, the model was able to predict accurately the computational outcome for an axial load of 140 N. The presented model and approach of using a multi-body simulation model are anticipated to have value as a predictive clinical tool including effect of injuries or anatomical variations and initial outcome of surgical procedures for patient-specific planning and custom implant design. Therefore, patient-specific multi-body simulation models are potentially valuable tools for surgeons in pre- and intraoperative planning of implant placement and orientation.

The role of arthroscopy in carpal instability

Carpal instability is predominantly caused by trauma and presents as a painful wrist with signs and symptoms of weakness, clicking, clunking and a sense of giving way. Wrist arthroscopy is widely regarded as the 'gold standard' in diagnosing and understanding carpal instability. This article is based on an extensive literature search to evaluate the evidence behind the use of wrist arthroscopy in the assessment and management of these patients. There is convincing evidence supporting the role of arthroscopy in diagnosis and assessment of factors involved in the development of carpal instability, but weak evidence for the effectiveness of arthroscopic techniques in the actual treatment of this condition. The article reviews mechanisms behind, and the role for arthroscopy in the management of scapholunate, lunotriquetral, midcarpal and radiocarpal instability. It also presents how the author incorporates the 'evidence-base' into an 'experience-based' clinical practice.

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.

Midcarpal instability: a radiological perspective

Midcarpal instability (MCI) is the result of complex abnormal carpal motion at the midcarpal joint of the wrist. It is a form of non-dissociative carpal instability (CIND) and can be caused by various combinations of extrinsic ligament injuries that then result in one of several subtypes of MCI. The complex patterns of injury and the kinematics are further complicated by competing theories, terminology and classifications of MCI. Palmar, dorsal, ulna midcarpal instability, and capitolunate or chronic capitolunate instability are all descriptions of types of MCI with often overlapping features. Palmar midcarpal instability (PMCI) is the most commonly reported type of MCI. It has been described as resulting from deficiencies in the ulna limb of the palmar arcuate ligament (triquetrohamate-capitate) or the dorsal radiotriquetral ligaments, or both. Unstable carpal articulations can be treated with limited carpal arthrodesis or the ligamentous defects can be treated with capsulorrhaphy or ligament reconstruction. Conventional radiographic abnormalities are usually limited to volar intercalated segment instability (VISI) patterns of carpal alignment and are not specific. For many years stress view radiographs and videofluoroscopy have been the methods of choice for demonstrating carpal instability and abnormal carpal kinematics respectively. Dynamic US can be also used to demonstrate midcarpal dyskinesia including the characteristic triquetral "catch-up" clunk. Tears of the extrinsic ligaments can be demonstrated with MR arthrography, and probably with CT arthrography, but intact yet redundant ligaments are more difficult to identify. The exact role of these investigations in the diagnosis, categorisation and management of midcarpal instability has yet to be determined.

The non-dissociative clunking wrist: a personal view

Clunking of the wrist is often the result of a combined radiocarpal and midcarpal ligament insufficiency, coupled with inadequate neuromuscular coordination. When symptomatic, these wrists may benefit from splinting, isometric exercising of specific muscles and advice on activity modification. Failing this, different surgical strategies have been proposed, depending on the location of dysfunction. When the clunking derives from an isolated injury of one joint, reconstruction of its inadequate ligaments may be an effective solution. However, soft tissue procedures tend to fail when clunking results from multilevel instability. In these cases, partial carpal arthrodesis is an alternative. Although effective in eliminating the clunking, midcarpal fusion is associated with alteration of the so-called "dart-throwing" motion, the most common rotation in daily activities, and hence is not recommended. Radiolunate fusion, by contrast, appears to be a less morbid alternative, with the benefit of eliminating the painful clunking while preserving a good range of dart-throwing motion.

Association between lunate morphology and carpal collapse patterns in scaphoid nonunions

PURPOSE

Type I lunates have a single distal facet for articulation with the capitate; type II lunates have an additional (medial) hamate facet on the distal articular surface. We retrospectively reviewed a series of patients with scaphoid nonunions to determine if there was an association between lunate morphology and the degree of carpal instability observed. Association between lunate morphology and the location of the scaphoid fracture (proximal or waist) was also investigated.

METHODS

Radiographs were evaluated for 45 patients with established scaphoid nonunions. Lunate morphology, scaphoid fracture location, and radiolunate angle were determined.

RESULTS

Type I lunates were present in 21 patients. Of these, 15 were found to have a dorsal intercalated segment instability pattern (radiolunate angle greater than 15 degrees ). By contrast, only 4 of the patients with type II lunates exhibited this pattern of instability. No significant association was found between lunate morphology and the scaphoid fracture location.

CONCLUSIONS

Type II lunate morphology is associated with significantly decreased incidence of dorsal intercalated segment instability (DISI) deformity in cases of established scaphoid nonunion (p = .0002). Lunate morphology, however, was not significantly associated with the location of the scaphoid fracture in these cases (p = .19).

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.

Dynamic radial translation instability of the carpus

We report a case of a dynamic radial translation instability of the carpus, secondary to avulsion of the ulnocarpal ligaments and attenuation of the short radiolunate ligament. In addition, there was a peripheral detachment of the distal radioulnar ligaments causing distal radioulnar instability. Reattachment of the avulsed ligaments combined with a Sauvé-Kapandji procedure resulted in an excellent function, which was maintained 10 years after surgery.

Perilunate injuries: diagnosis and treatment

Perilunate injuries are severe disruptions of the carpus, which present a formidable challenge to the treating physician. Accurate recognition of the pattern of injury is not always straightforward. The injury can propagate through ligaments and/or bone, creating multiple variations of a basic injury pattern. Posteroanterior and lateral radiographs will depict a perilunate injury, but additional views may be necessary to appreciate subtle carpal fractures. Once the diagnosis has been established, early intervention is necessary for optimal results. An initial closed reduction with sedation and traction is performed to restore overall carpal alignment. However, subsequent closed or open reduction is necessary to restore anatomic alignment of all injured structures. The outcome of perilunate injuries correlates with the adequacy of reduction. Complications such as chondrolysis, carpal instability, and traumatic arthritis can occur despite satisfactory treatment.

Imaging of the hand and wrist

This article reviews many of the most commonly used modalities for imaging the hand and wrist. Particular attention is paid to proper radiographic positioning, with emphasis on the four-view wrist series. Standard wrist measurements are detailed, and wrist arthrography is also discussed. Techniques for cross-sectional imaging, computed tomography, and MR imaging are reviewed, and several examples are presented as to where MR imaging is diagnostically valuable.

Analysis of carpal instability: II. Clinical applications

An analytic scheme for carpal instability patterns has been described to help standardize reporting of these conditions. Six categories to be recognized in each case are chronicity, constancy, etiology, location, direction, and pattern. Examples are presented to illustrate the use of this scheme.

Analysis of carpal instability: I. Description of the scheme

There is a lack of a generally agreed analysis of carpal instability that can assist in the diagnosis, give guidelines for treatment, and ensure unity when reporting results of treatment. Based on the literature and using six categories describing chronicity, constancy, etiology, location, direction, and pattern of the instability, we present a proposal for a standardized analysis. Using this analysis, an instability should be presented with information in all six categories. The analysis may be expanded and developed according to future needs.

[Radio-carpal and medio-carpal arthroscopy in instability of the wrist]

Forty-one arthroscopies were performed on previously asymptomatic wrists following trauma. In about 25% of the wrists there was only one specific ligamentous lesion. In 75% however a combination of 2 or several distinct lesions was observed. These lesions, localised on the ulnar aspect of the mid-carpal joint, are more complex than those on the radio-carpal joint on the radial aspect of the carpus. These observations would tend to confirm our present day knowledge of wrist biomechanics but disagree with the currently proposed concepts of instability by several American authors. "Instability" seems to be inadequate to define complex lesions, more adequate would be the simple description of a "dysfunctional state" of the wrist complex. This statement must be related to the position of the carpal bones, which do not show any significant change despite the tears shown. The arthroscopy appears to range first in a series of diagnostic tools. However it concerns mainly the ligamentous layers facing the interior of the joint while lacking information about time elapsed since the actual trauma. We therefore state that arthroscopy may decrease but not exclude diagnostic failures. Type and risk of therapeutic decisions are also appreciated with increased accuracy. No doubt there still remain discrepancies when clinical, arthrographic and arthroscopic examination are compared, which indicates the complementary nature of the technics of investigation, especially in the light of the current state of the biomechanic sciences of the wrist.