The hamatolunate facet: characterization and association with cartilage lesions--magnetic resonance arthrography and anatomic correlation in cadaveric wrists

Lunate morphology: association with the severity of scapholunate ligament injuries and carpal instability patterns

Type II lunate has been associated with a lower incidence of dorsal intercalated segment instability (DISI) in the case of scapholunate dissociation. We aimed to evaluate the frequency of different lunate types and their influence on the prevalence and severity of scapholunate ligament (SLIL) injuries and the development of DISI. The surgical records of 414 arthroscopies were reviewed retrospectively. Lunate types were diagnosed based on radiograms and MRI examinations. The Type II lunate had a facet between hamate and lunate; in the Type I lunate, this facet is lacking. We additionally included the assessment of the capitate-triquetrum distance (CTD), which defines Type I, Intermediate, and Type II lunates. We adopted the DISI when the scapholunate angle was more than 80° and/or the radiolunate angle less than -15°. Fisher's exact test was applied to compare the distribution frequency of SLIL lesions and DISI deformity of patients with different lunate types. To quantify the inter- and the intra-rater reliability of lunate type assessment Cohen's kappa was calculated and, for CTD measurements, a Bland-Altman plot was created. Up to 77.1% patients had Type II lunates. Regarding MRI and CTD classification in patients with Type I lunates, Grade 4 SLIL injuries were more common than in those with Intermediate and Type II (p < 0.05). In the case of Grade 4 SLIL lesions, DISI was more common in patients with Type I lunates (p < 0.05). There were, however, only 25 patients with Type I lunates, and Grade 4 SLIL lesions according to MRI, and 6 according to CTD measurement.

An Evidence-Based Review of Overuse Wrist Injuries in Athletes

Overuse wrist injuries are a common problem in athletes and can be related to tendinopathies or osteoarticular pathology. Fortunately, athletes rarely miss time from their sport due to these conditions because many can be treated nonoperatively. For refractory cases, there often is a curative surgical procedure that can be done during the off-season.

Radiographic/MR Imaging Correlation of the Wrist

In this review article, the authors discuss the imaging features of the most common pathologic conditions of the wrist by putting the emphasis on radiographic and MR imaging correlations. A topographic approach based on the 3 functional columns of the wrist (radial, central, and ulnar) serves as a framework. The pathologic conditions are classified, based on the structures involved, as fractures, ligament injuries, arthropathies, bone abnormalities, and tendinopathies. The authors describe and evaluate classic radiographic signs and explain how they correlate with MR imaging. The advantages and limitations of each technique are thoroughly discussed as well as other imaging modalities.

Functional and Surgical Anatomy of the Upper Limb: What the Radiologist Needs to Know

The anatomy of the upper limb is complex and allows for exceptional functionality. The movements of the joints of the shoulder, elbow, and wrist represent a complex dynamic interaction of muscles, ligaments, and bony articulations. A solid understanding and of the characteristics and reciprocal actions of the anatomic elements of the joints of the upper limb helps explain the mechanisms and patterns of injury. This article focuses on the anatomy and functionality of the shoulder, elbow, and wrist, with emphasis on the stabilizing mechanisms, to set the foundation for understanding the occurrence of pathologic conditions.

Radiographic prediction of lunate morphology in Asians using plain radiographic and capitate-triquetrum distance analyses: reliability and compatibility with magnetic resonance arthrography (MRA) findings

Background

The purpose of this study was to examine the reliability of plain radiographic methods of determining the lunate type and its compatibility with magnetic resonance arthrography (MRA) findings.

Methods

Plain radiographs of a total of 150 wrists were reviewed by three observers. Lunate types were evaluated using both conventional posteroanterior (PA) radiographic analysis and the capitate-triquetrum distance (CTD) analysis. Cohen kappa and Fleiss kappa statistics were used to estimate intra- and inter-observer reliabilities. Compatibility with the MRA findings, as assessed by each observer, was investigated.

Results

The overall intra-observer reliability was 0.517 for the analysis and 0.589 for the CTD analysis. The overall inter-observer agreement was 0.448 for the PA radiographic analysis and 0.581 for the CTD analysis. The PA radiographic analysis and MRA findings for the detection of medial lunate facets were compatible in 119 of the 150 patients (79.3%). Twenty-eight (90.3%) of the 31 incompatible wrists had a medial facet on MRA (Type II), which was not detected in the PA radiographic analysis. In the CTD analysis, the results for 27 of 29 Type II lunates (93.1%) and 39 of 45 Type I lunates (86.7%) were compatible with the MRA.

Conclusions

This study suggests that predicting the lunate type by plain radiographs alone is insufficient, as both radiographic analyses showed moderate intra- and inter-observer reliabilities. Although both radiographic analyses showed good compatibility with the MRA for Type II lunates, clinicians should be alert to undetected medial facets in Type I lunates on PA radiographic analysis.

Three-dimensional kinematics of the lunate, hamate, capitate and triquetrum with type 1 or 2 lunate morphology

The purpose of this study was to investigate the differences in three-dimensional carpal kinematics between type 1 and 2 lunates. We studied 15 instances of wrist flexion to extension (nine type 1, six type 2), 13 of radial to ulnar deviation (seven type 1, six type 2), and 12 of dart-throwing motion (six each of type 1 and 2) in 25 normal participants based on imaging with computerized tomography. Mean proximal translation of the distal articular midpoint of the triquetrum relative to type 2 lunates during wrist radioulnar deviation was 2.9 mm (standard deviation (SD) 0.7), which was significantly greater than for type 1 lunates, 1.6 mm (SD 0.6). The hamate contacted the lunate in ulnar deviation and ulnar flexion of wrists with type 2 lunates but not with type 1. We conclude that the four-corner kinematics of the wrist joint are different between type 1 and 2 lunates.

Lunate morphology as a risk factor of idiopathic ulnar impaction syndrome

AIMS

Positive ulnar variance is an established risk factor for idiopathic ulnar impaction syndrome (UIS). However, not all patients with positive ulnar variance develop symptomatic UIS and other factors, including the morphology of the lunate, may be involved. The aim of this study was to clarify the relationship between lunate morphology and idiopathic UIS.

PATIENTS AND METHODS

A cohort of 95 patients with idiopathic UIS (UIS group) was compared with 95 asymptomatic controls with positive ulnar variance. The shape of the lunate was measured using the capitate-triquetrum distance (CTD), ulnar coverage ratio (UCR), radiolunate distance and radiolunate angle. The association of radiographic parameters and lunate types with the development of UIS was investigated in univariable and multivariable analyses. Receiver operating characteristic curves were used to estimate a cutoff for any statistically significant variables.

RESULTS

The proportion of type II lunates, which have a medial hamate facet, were significantly higher in the UIS group than in the control group in the univariable analysis (p = 0.001). CTD (odds ratio (OR) 1.52; 95% confidence interval (CI) 1.11 to 2.06; p = 0.008) and UCR (OR 44.78; 95% CI 5.35 to 374.90; p = 0.002) showed a positive association with UIS in the multivariable analysis. Estimated cutoff values were 2.5 mm for the CTD (area under the curve (AUC) = 0.65) and 0.4 for the UCR (AUC = 0.64).

CONCLUSION

The proportion of type II lunates was greater in the UIS group than in the control group. A large UCR, which represents the broad base of the lunate, was positively associated with the development of idiopathic UIS. Cite this article: Bone Joint J 2017;99-B:1508-14.

MRI and Arthroscopic Correlation of the Wrist

Since its introduction in 1979, the practice of and indications for wrist arthroscopy in the diagnosis and treatment of pathologic conditions in the wrist continues to grow. Magnetic resonance imaging (MRI) is another commonly used tool to noninvasively examine the anatomy and pathology of the wrist joint. Here, we review the normal wrist anatomy as seen arthroscopically and through MRI. We then examine the various common pathologic entities and define both the arthroscopic findings and correlated MRI findings in each of these states.

Clinical outcomes of proximal row carpectomy by preoperative midcarpal joint morphological classification: Viegas type I versus type II

The midcarpal joint can be classified into two anatomical types - Viegas type I and Viegas type II - based on the absence or presence of a medial facet for the hamate on the lunate (lunohamate facet). Type I is associated with a round capitate shape, which theoretically allows better congruence with the lunate fossa of the distal radius following proximal row carpectomy (PRC). This morphological feature has never been considered as a predictive factor of clinical outcome for this surgical procedure. This study aimed to compare the clinical and radiological outcomes of the two Viegas types following PRC. A retrospective single-center study was carried out on patients who underwent PRC for wrist osteoarthritis. Minimum follow-up was 2 years. Lunate type was determined based on preoperative CT arthrography. The clinical evaluation included range of motion (ROM) and strength as well as the functional DASH, Mayo Wrist scores and a VAS for pain. The outcome of radiocapitate osteoarthritis was assessed on plain radiographs. Forty patients were reviewed with a mean follow-up of 57 months. Twenty-one Viegas type I and 19 Viegas type II were identified on preoperative CT arthrography. The etiologies included 23 SLAC wrists (12 Viegas type I, 11 type II), 8 SNAC wrists (4 Viegas type I, 4 type II), 6 cases of Kienböck's disease (3 type IIIa, 3 type IIIb with 3 Viegas type I and 3 type II), 1 Preiser's disease and 2 cases of transscaphoid perilunate dislocation of the carpus. Patients with a Viegas type I lunate had significantly greater flexion-extension ROM: 83.5° vs. 71° (P=0.04) and radial deviation: 12° vs. 7° (P=0.013) than those with Viegas type II. However, three cases of complex regional pain syndrome (CRPS) were reported in the Viegas type II group vs. zero in the Viegas type I group. There were no differences between the two groups in terms of strength, functional scores or VAS pain. The outcome of radiocapitate osteoarthritis was similar in both groups. Considering the number of CRPS cases in the Viegas type II group and similar functional results in both groups, the worse outcomes of the Viegas type II patients in terms of ROM cannot be considered as clinically relevant. This comparative study does not provide a reasonable basis for concluding that Viegas type I patients are better candidates for PRC than Viegas type II patients.

Imaging of Sports-related Hand and Wrist Injuries: Sports Imaging Series

Hand and wrist injuries are common occurrences in amateur and professional sports and many of them are sport-specific. These can be divided into two categories: traumatic injuries and overuse injuries. The aim of this article is to review the most common hand and wrist sports-related lesions. Acute wrist injuries are predominantly bone fractures, such as those of the scaphoid, hamate hook, and ulnar styloid. Ligament lesions are more challenging for radiologists and may lead to carpal instability if undiagnosed. Overuse wrist injuries are mainly represented by tendinous disorders, with De Quervain syndrome and extensor carpi ulnaris tendon disorders being the most common among them; however, there are other possible disorders such as impaction syndromes, stress fractures, and neurovascular lesions. Finally, finger lesions, including closed-tendon injuries (mallet and boutonniere injuries, jersey finger, and boxer's knuckle), flexor pulley injuries, and skier's thumb, should also be detected. (©) RSNA, 2016 Online supplemental material is available for this article.

The Role of Lunate Morphology on Scapholunate Instability and Fracture Location in Patients Treated for Scaphoid Nonunion

BACKGROUND

To determine the association between lunate morphology and the scapholunate instability using radiographic images, and investigate the association between lunate morphology and scaphoid fracture location.

METHODS

Between January 2003 and December 2011, we retrospectively evaluated the plain radiographs and computed tomography (CT) images of 70 patients who underwent surgical intervention for a scaphoid nonunion, in order to determine the association between lunate type (I or II) and scapholunate instability or scaphoid fracture location. We determined the scaphoid fracture location using the fragment ratio and measured the radiolunate angle and capitate-triquetrum (C-T) distance.

RESULTS

A type II lunate was present in 68.6% (48 of 70 cases). Mean fragment ratio of fracture location was 50.6% in the type II lunate group and 56.2% in the type I lunate group (p = 0.032). Sixteen of the 70 patients had dorsal intercalated segmental instability (DISI) deformities. Nine of 22 cases showed DISI deformity in type I lunate and 7 of 48 cases showed DISI deformity in type II lunate (p = 0.029). However, there were no significant differences between the presence of DISI deformity and fracture location (p = 0.15). Morphologic comparisons by both plain radiography and CT indicated a mean C-T distance in the type I lunate group (22 cases) of 2.3 mm and 5.0 mm in the type II lunate group (48 cases). The C-T distances were significantly correlated with lunate morphology (p = 0.001).

CONCLUSIONS

A type II lunate was associated with low incidence of DISI deformity and proximal location of fracture in patients presenting with a scaphoid nonunion.

Avaliação artroscópica e macroscópica da faceta medial do semilunar

OBJETIVO: avaliar a correlação entre a presença de uma faceta medial do semilunar e a incidência de lesões ligamentares e artrose do pólo proximal do hamato. MÉTODOS: Avaliação artroscópica e dissecação dos punhos foram efetuados em cadáveres. RESULTADOS: Houve uma correlação clara, estatisticamente significativa entre artrose do pólo proximal do hamato e a presença da faceta medial do semilunar. CONCLUSÃO: Artrose do pólo proximal do hamato está correlacionada com a presença do tipo II semilunar. Nível de Evidência III, Estudo de pacientes nãoconsecutivos; sem padrão de referência "ouro" aplicado uniformemente

Role of imaging in spine, hand, and wrist osteoarthritis

Osteoarthritis (OA) of the wrist is mainly secondary to traumatic ligamentous or bone injuries. Involvement of the radiocarpal joint occurs early on in the disease, whereas the mediocarpal joint is involved at a later stage. Metabolic diseases may also involve the wrist and affect specific joints such as the scapho-trapezio-trapezoid joint. Although OA of the wrist is routinely diagnosed on plain films, a thorough assessment of cartilage injuries on computed tomographic arthrography, magnetic resonance imaging (MRI), or MR arthrography remains necessary before any surgical procedure. OA of the fingers is frequently encountered in postmenopausal women. Distal interphalangeal joints and trapezio-metacarpal joint are the most frequently involved joints. Whereas the clinical diagnosis of OA of the wrist and hand is straightforward, the therapeutic management of symptomatic forms remains unclear, with no clear guidelines. OA of the spine is related to degenerative changes of the spine involving the disc space, vertebral endplates, the facet joints, or the supportive and surrounding soft tissues. The sequelae of disc degeneration are among the leading causes of functional incapacity in both sexes, and are a common source of chronic disability in the working years. Disc degeneration involves structural disruption and cell-mediated changes in composition. Radiography remains usually the first-line imaging method. MRI is ideally suited for delineating the presence, extent, and complications of degenerative spinal disease. Other imaging modalities such as computed tomography, dynamic radiography, myelography, and discography may provide complementary information in selected cases, especially before an imaging-guided percutaneous treatment or spinal surgery. The presence of degenerative changes on imaging examinations is by no means an indicator of symptoms, and there is a high prevalence of lesions in asymptomatic individuals. This article focuses on imaging of OA of the wrist and hand, as well as lumbar spine OA, with an emphasis on current MRI grading systems available for the assessment of discovertebral lesions.

Ulnar-sided wrist pain. Part I: anatomy and physical examination

Ulnar-sided wrist pain is a common complaint, and it presents a diagnostic challenge for hand surgeons and radiologists. The complex anatomy of this region, combined with the small size of structures and subtle imaging findings, compound this problem. A thorough understanding of ulnar-sided wrist anatomy and a systematic clinical examination of this region are essential in arriving at an accurate diagnosis. In part I of this review, ulnar-sided wrist anatomy and clinical examination are discussed for a more comprehensive understanding of ulnar-sided wrist pain.

Imaging recognition of morphological variants at the midcarpal joint

PURPOSE

To compare the imaging methods for identifying the various morphological variations of the articular surfaces at the midcarpal joint.

METHODS

Thirteen cadaveric wrists were examined by plain neutral anteroposterior radiographs; 2-dimensional computed tomography (CT); 3-dimensional CT reconstruction, and 3-tesla magnetic resonance imaging (MRI). Carpal measurements were performed, and the parameters that defined the scaphoid, lunate, hamate, and capitate morphological types were investigated, with dissection being used as the definitive measure of morphology. The dissection findings were compared to the results of each imaging technique to determine the accuracy of morphological determination from each technique.

RESULTS

Lunate type was the most accurately identified morphological variant amongst all imaging techniques. Lunate type was most accurately determined from coronal MRI. A lunate with a small, cartilaginous ulnar facet (intermediate type) could be differentiated only by coronal MRI and dissection. Scaphoid type could not be determined accurately using any of the imaging modalities described. Capitate type was most accurately determined from coronal MRI. However, flat and spherical-type capitates could not be routinely differentiated from V-shaped capitates. Hamate type was most accurately determined from 3-dimensional CT reconstruction.

CONCLUSIONS

Accurate identification of carpal bone morphology is required to improve our understanding of carpal mechanics and pathology. Not all morphological features can be identified radiographically. Direct visualization is required to differentiate types of scaphoid, and to differentiate V-type capitates. MRI provides the most accurate identification of lunate type, and 3-dimensional CT provides the best method of differentiating hamate types.

Anthropometric characteristics of wrists joint surfaces depending on lunate types

It is well known that the lunate presents with two main types: lunate type I has one facet of its distal surface only for capitates, whereas lunate type II has two facets of the same surface for capitate and for hamate. Our previous anthropometric studies showed that the lunate type II wrists are of greater size than the lunate type I wrists. The aim of the present study was to determine whether the lunate types and the presence or absence of hamato-lunate joint correlate with anthropometric characteristics of the joint surfaces of other wrists. Sixteen sets of macerated wrists with the lunate type I and 21 with the lunate type II were studied. Two-thousand-four-hundred-and-forty-eight anthropometric measurements were done (for 68 anthropometric indicators) and 864 anthropometric indices were calculated (for 24 anthropometric indices) separately for the wrist joint surfaces. The absolute value of the anthropometric indicators of the joint surfaces of the separated wrists were greater in the wrists with the lunate type II, except for the indicators "Greatest length of the dorsal joint surface of pisiform", "Width of the proximal joint surface, measured in the middle" and "Greatest width of the proximal joint surface" for the trapezoid and "Greatest height of the ulnar joint surface" for the capitate. The enlargement of the joint surfaces for the scaphoid was mainly in proximo-distal direction. The enlargement for the triquetrum and pisiform was mainly in radio-ulnar direction. The enlargement for trapezium, trapezoid and capitate was mainly in dorso-volar direction (except for the ulnar joint surface of capitate). The enlargement for hamate was mainly in radio-ulnar and dorso-volar directions (except for the joint surfaces for capitate and triquetrum). The calculated indices illustrate the quantitative proportions of the variations mentioned above. The anthropometric differences are a good reason to make a clear distinction between both types of wrist joint complexes-with or without a hamato-lunate joint.

MR imaging of cartilage in cadaveric wrists: comparison between imaging at 1.5 and 3.0 T and gross pathologic inspection

PURPOSE

To evaluate prospectively the diagnostic accuracy of magnetic resonance (MR) imaging in the identification of cartilage abnormalities at 3.0 and 1.5 T in cadaveric wrists, with gross pathologic findings as the standard of reference.

MATERIALS AND METHODS

The study was approved by the hospital review board, and informed consent for scientific use of body parts had been provided by the subjects. Ten cadaveric wrists from nine subjects were evaluated (seven left wrists, three right; five women, four men; age range, 46-99 years; mean age, 80 years). All wrists were examined with MR imaging in a 1.5-T unit and a 3.0-T unit, with the same imaging protocol used with both systems. Imaging protocol included intermediate-weighted fast spin-echo sequences and three-dimensional gradient-recalled-echo sequences. Cartilage surfaces of the proximal and distal carpal row, including the scaphotrapeziotrapezoidal joint, were analyzed in blinded fashion by two musculoskeletal radiologists working independently and then in consensus. Open inspection of the wrists was used as the standard of reference. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. The McNemar test was used to assess differences in diagnostic assessment. Weighted kappa values were calculated for interobserver agreement.

RESULTS

One hundred seventy cartilage surfaces were graded. The sensitivity and specificity for cartilage lesions were 43%-52% and 82%-89%, respectively, at 1.5 T and 48%-52% and 82% at 3.0 T. Differences in assessment did not reach statistical significance (P > .99). Highest sensitivities were found in the proximal carpal row (67%-71%); lowest sensitivities were found in the distal carpal row (14%-24%). Interobserver agreement was higher for imaging at 3.0 T (kappa = 0.634) than at 1.5 T (kappa = 0.267).

CONCLUSION

The performance of MR imaging for the detection of articular cartilage abnormalities in the wrist depends on anatomic location. Interobserver agreement is higher for imaging at 3.0 than at 1.5 T, but diagnostic performances were not significantly different (P > .99) at either field strength.

Técnica e indicaciones de la resonancia magnética artrografía. Extremidad superior (I)

Magnetic resonance (MR) is the most effective imaging technique in the diagnosis of articular pathology. MR arthrography (MRA), with intra-articular injection of diluted gadolinium or physiological saline solution has become more common in recent years. The intra-articular fluid facilitates the detection of articular pathology by delineating the articular structures, separating adjacent anatomic structures, and filling potential spaces that originate in or communicate with the joint. MRA provides additional information about the integrity of the articular structures, especially cartilage, fibrocartilage, and ligaments. MRA has proven especially useful in the shoulder, where most of the studies have been centered. The detection of subtle lesions of the capsule/labrum complex is fundamental for presurgical evaluation. MRA can be used to complement conventional MR imaging in some cases and in others it is the initial technique of choice. Indirect MRA with intravenous gadolinium administration is based on the enhancement of articular fluid caused by diffusion from the synovial space to the articular space. This technique offers better results in articulations with less capacity for distension, such as the wrist, ankle, hand, and foot. This first part of two-part article reviews the current role of MRA in the upper limb. Special emphasis is placed on the shoulder joint, where its usefulness has been most clearly established. The usefulness of this technique in other joints is also described, reviewing the most important anatomic aspects, techniques and applications.

Role of MR imaging in chronic wrist pain

Magnetic resonance (MR) imaging for chronic wrist pain is challenging. Correct assessment of the triangular fibrocartilage, hyaline cartilage, ligaments, and tendons has become mandatory for comprehensive decision making in wrist surgery. The MR technique, potential and limits of MR imaging in patients with chronic wrist pain will be discussed. MR arthrography with injection of gadolinium-containing contrast material into the distal radioulnar joint is suggested for evaluation of the triangular fibrocartilage. The clinically meaningful ulnar-sided peripheral tears are otherwise hard to diagnose. The diagnostic performance of MR imaging for interosseous ligament tears varies considerably. The sensitivity for scapholunate ligament tears is consistently better than for lunotriquetral ligament tears. Gadolinium-enhanced MR imaging is considered to be the best technique for detecting established avascularity of bone, but the assessment of the MR results remains challenging. Most cases of ulnar impaction syndrome have characteristic focal signal intensity changes in the ulnar aspect of the lunate. Avascular necrosis of the lunate (Kienböck's disease) is characterized by signal changes starting in the proximal radial aspect of the lunate. MR imaging is extremely sensitive for occult fractures. Questions arise if occult posttraumatic bone lesions seen on MR images only necessarily require the same treatment as fractures evident on plain films or computed tomography (CT) images. MR imaging and ultrasound are equally effective for detecting occult carpal ganglia. Carpe bossu (carpal boss) is a bony protuberance of a carpometacarpal joint II and III which may be associated with pain.

Imaging of Ulnar-Sided Wrist Pain

Ulnar-sided wrist pain has long been a diagnostic problem, partly because of the complex anatomy and many possible causes of pain in this region. This article discusses anatomy, pathophysiology, and imaging appearance of the more common causes, including tears of the triangular fibrocartilage complex, disorders of the distal radioulnar joint, tears of the lunotriquetral ligament, disorders of the extensor carpi ulnaris tendon, disorders of the pisotriquetral joint, the impingement and impaction syndromes, and ulnar wrist masses. Along with clinical history and physical examination, imaging is important in evaluation of ulnar-sided wrist pain. Conventional radiographs, conventional arthrography, CT, MRI, and MR arthrography are useful modalities that are often used in concert to help guide diagnosis and treatment.

Variants, pitfalls and asymptomatic findings in wrist and hand imaging

Anatomic variants of the bones, ligaments, tendons and muscles are frequent findings in imaging of the wrist and hand. Many findings especially changes in the triangular fibrocartilage (TFC) and the interosseous ligaments are asymptomatic, their incidence is increasing with age, and they are frequently found bilaterally. Abnormalities such as increased signal within tendons are common in asymptomatic subjects. They may be explained by normal physiology, anatomical variability, MR artifacts or true abnormalities without clinical importance. Although it is not always possible to differentiate variants and artifacts from clinically relevant findings it is important to know their potential etiology and clinical importance and not to over report them as abnormality requiring additional imaging or treatment.

The hamate facet of the lunate: a radiographic study in an Arab population from Bahrain

Based on the presence of a facet for the hamate two types of lunate bone have been described in the wrist; type I is without a facet for the hamate while type II bears a facet on the medial surface for articulation with the proximal pole of the hamate. Compared to type I lunates, type II lunates have been shown to have different kinematics, are more prone to clinically relevant degenerative changes in the hamato-lunate joint and may cause ulnar-sided wrist pain. The incidence of type II lunates seems to vary in different populations. Postero-anterior (PA) view of plain radiographs of the hand was studied in Arab subjects from Bahrain (n=381; 307 males and 74 females) to determine the incidence of type I and type II lunates. The mean age of the subjects was 31.1 years, the range being 18-80 years. In the population studied, only 148 (38.8%) of the 381 wrists showed type II lunate; 121 (31.7%) were found in males and 27 (7.1%) in females. There was no significant difference in the mean age of subjects with type I or type II lunates (P=0.16). There was no correlation between side and gender with the presence or absence of a hamate facet on the lunate. The incidence of type II lunate was much lower than reports in the literature of populations from the Western world, which could be attributed to a genetic variation in the Arab population in Bahrain. These data indicate that osteoarthritis of the hamate or lunate is less likely to be a cause of ulnar-sided wrist pain in Bahraini Arabs.

Wrist MR Arthrography: How, Why, When

MR imaging of the wrist frequently represents a diagnostic challenge for radiologists because of the complex anatomy of this joint, small size of its components, and little known pathologic conditions. MR arthrography combines the advantages of conventional MR imaging and arthrography by improving the visualization of small intra-articular abnormalities. This article reviews the current role of MR arthrography in the evaluation of wrist joint disorders considering the relevant aspects of anatomy, techniques, and applications.