Imaging recognition of morphological variants at the midcarpal joint

Relationship Between Carpal Bone Morphology and Distal Radius Fracture Pattern

Abstract Background: In this study, we examined whether carpal bones (lunate, hamate, capitate) morphologies and fourth metecarp-capitate articulation have an effect on the distal radius fracture pattern. Methods: 206 patients who applied to the emergency department with distal radius fracture between 2016-2020 were included in the study. Preoperative and pre-reduction x-ray films of the patients were examined. Lunate, hamate, capitate morphologies and 4.metacarp articulation analyzed and classified. Distal radius fracture types were classified according to AO and Fernandez. The relationship between carpal bone morphology and distal radius fracture type was analyzed. Results: This study consisted of 101 men and 103 women. AO fracture types and carpal bone morphologies (lunate joint type according to Viegas, lunate type according to Zapico, capitate morphology, hamate morphology and capitate-4 metacarpal joint morphology) did not differ significantly (p > 0.05). Fernandez fracture types and carpal bone morphologies (lunate joint type according to Viegas, lunate type according to Zapico, capitate morphology, hamatum morphology and capitate-4.metacarp joint morphology) were compared, there was no significant difference (p > 0.05). Conclusion: As a result, no clear relationship could be demonstrated between carpal bone morphology and distal radius fracture pattern.

Is DISI Deformity Related to Presence of a Medial Lunate Facet in Patients with Scapholunate Dissociation?

Background  Lunate morphology has been suggested to influence carpal kinematics. Purpose  We investigate a possible relation between presence of a medial lunate facet and dorsal intercalated segment instability (DISI) of the wrist in patients with a scapholunate (SL) dissociation. Methods  We retrospectively reviewed patients diagnosed with SL dissociation between 2000 and 2017. Lunate morphology was categorized based on radiographs and magnetic resonance imaging (MRI), as type I or II according to Viegas and Galley. DISI was defined as radiolunate angle > 15 degrees and SL instability as SL angle > 60 degrees. SL distance > 3 mm was considered as widening and carpal height ratio < 0.5 was considered as carpal collapse. We used descriptive statistics to report on SL instability and DISI in patients with Viegas type I and type II lunates. We calculated kappa to determine agreement between radiographs and MRI and to determine inter- and intraobserver agreement. Results  Of 119 patient files, 79 wrists met the inclusion criteria of which 25 were type I lunates and 54 type II. Similar spreading of the data of both groups was found regarding DISI, SL instability, and SL widening based on radiographic classification of the lunate, even after adding MRI findings. In the presence of carpal collapse, capitate-to-triquetrum distance was higher. We found a substantial inter- and intraobserver agreement for lunate classification. Conclusion  Our results suggest a similar prevalence of DISI deformity or enlarged SL angle in patients with type I or II lunate in presence of SL dissociation. The Viegas classification is a reliable and reproducible classification system. Level of evidence  This is a Level III, cross-sectional study design.

Association of Lunate Morphology With Progression to Scaphoid Fracture Nonunion

Background: The purpose of our study was to review a series of patients with scaphoid fractures to determine whether there was an association between lunate morphology and progression to delayed union or nonunion when treated operatively or nonoperatively. Secondary aims included evaluation of the relationship between lunate morphology and scaphoid fracture location. Methods: A retrospective review of all patients with a diagnosis of scaphoid fracture was performed at our institution between 2014 and 2017. Medical records and radiographs were evaluated to determine lunate morphology, scaphoid fracture location, treatment, and time to union. Differences between groups were determined using χ² analysis with significance set at P <.05. Multiple logistic regression analyses were used to evaluate scaphoid union in the setting of lunate morphology when controlling for confounders. Results: A total of 169 patients were included; 45.0% (n = 76) of patients had type I lunate morphology, and 55.0% (n = 93) had type II. In all, 64.5% (n = 49) of patients with type I lunate and 68.8% (n = 64) with type II lunate had a fracture at the scaphoid waist. Among all patients with a scaphoid fracture, type II lunates were more likely than type I lunates to progress to nonunion when treated both operatively and nonoperatively (18.3% vs 4.0%, P = .0042). Lunate facet size was not shown to be a significant risk factor for nonunion among patients with a type II lunate (P = .4221). Conclusions: Patients with a scaphoid fracture and type II lunate morphology were more likely to progress to nonunion than patients with a type I lunate.

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.

Demystifying Palmar Midcarpal Instability

Palmar midcarpal instability is an uncommon condition diagnosed clinically with a painful pathognomonic clunk on terminal ulnar deviation of the wrist. Various causes have been described, but congenital laxity of the carpal ligaments is thought to be a key contributor. Treatment commences with conservative measures. This includes proprioceptive training based on more recent concepts on the sensorimotor function of the wrist. When these measures plateau, surgery is considered. The lack of high-level evidence and consensus on its cause continue to hamper our understanding and knowledge of this condition. The purpose of this review is to examine the current evidence to conceptualize this mysterious, yet infrequent phenomenon, and to provide an algorithm on its management.

Dynamic MRI of the wrist in less than 20 seconds: normal midcarpal motion and reader reliability

OBJECTIVE

To describe the normal motion pattern at the midcarpal compartment during active radial-ulnar deviation of the wrist using dynamic MRI, and to determine the observer performance for measurements obtained in asymptomatic volunteers.

METHODS

Dynamic MRI of 35 wrists in 19 asymptomatic volunteers (age mean 30.4 years, SD 8.6) was performed during active radial-ulnar deviation using a fast gradient-echo pulse sequence with 315 ms temporal resolution (acquisition time, 19 s). Two independent readers measured the transverse translation of the trapezium at the scaphotrapezium joint (STJ) and the capitate-to-triquetrum distance (CTD). Relationships between these measurements and laterality, sex, lunate type, and wrist kinematic pattern were evaluated.

RESULTS

At the STJ, the trapezium moved most in radial deviation, with an overall translation of 2.3 mm between ulnar and radial deviation. Mean CTD measurements were the greatest in ulnar deviation and varied 2.4 mm between ulnar and radial deviation. Mean CTD was greater in men than women in the neutral position (p = 0.019), and in wrists with type II lunate morphology during radial and ulnar deviation (p = 0.001, p = 0.014). There were no significant differences in trapezium translation or CTD with wrist laterality and kinematic pattern. Intraobserver and interobserver correlation coefficients were 0.97 and 0.87 for trapezium translation and 0.84 and 0.67 for CTD.

CONCLUSION

This study is the first to demonstrate the performance of dynamic MRI to quantify STJ motion and CTD. Dynamic MRI with a short acquisition time may be used as a tool to supplement static MRI in evaluation of the midcarpal compartment.

Analysis of Radiographic Relationship between Distal Radius, Ulna, and Lunate

Background  Wrist anatomy variability is associated with differing susceptibility to pathology. For example, a flat radial inclination is associated with Kienbock's disease. Lunate facet inclination (LFI) also exhibits variability. Its relationship with other wrist features is poorly documented. Purposes  We tested the hypothesis that high LFI is associated with increased uncovering of the lunate, negative ulnar variance (UV), and type 2 lunates to balance forces across wrists. Methods  In total, 50 bilateral and 100 unilateral wrist posteroanterior radiographs were reviewed. Lunate type, lunate uncovering index (LUI), lunate tilting angle (LTA), UV, and sigmoid notch angle (SNA) were measured, and correlation with LFI was assessed on 150 right wrist radiographs followed by an assessment of differences based on lunate morphology. Symmetry of 50 bilateral wrists was assessed. Results  There was no correlation of LFI with lunate morphology, LUI, and LTA. There was a low correlation of LFI with SNA and UV. There was an inverse relationship between UV and SNA. Wrists with type 2 lunates had more oblique sigmoid notches and higher LTA in comparison to wrists with type 1 lunates. Side-to-side comparison revealed strong correlation except for LUI, which exhibited moderate correlation. Conclusions There is no correlation between LFI, LUI, and lunate morphology. Type 2 lunates are associated with higher LTA and more oblique SNA. Wrists were symmetrical. Clinical Relevance  Factors other than lunate morphology are essential in balancing forces across wrists. A better understanding of soft tissue and other factors will improve the understanding of wrist biomechanics and pathology. Contralateral wrist radiographs can guide reconstructive surgery.

Capitate and Lunate Morphology in Normal Wrist Radiographs-A Pilot Study

BACKGROUND

Morphology may provide the basis for the understanding of wrist mechanics.

METHODS

We used classification systems based on cadaver dissection of lunate and capitate types to evaluate a normal database of 70 wrist radiographs in 35 subjects looking for associations between bone shapes. Kappa statistics and a log-linear mixed -effects model with a random intercept were used.

RESULTS

There were 39 type-1, 31 type- 2 lunates, 50 spherical, 10 flat and 10 V-shaped capitates. There was a significant difference in lunate and capitate shape between the hands of the same individual p <0.001. This may be due to different loads on the dominant vs. nondominant hands in the same individual.

CONCLUSION

Further study to better understand the development of radiographic parameters of the midcarpal joint may aid in our understanding of the morphology and mechanics of the wrist.

Association of Lunate Morphology With Carpal Instability in Scapholunate Ligament Injury

BACKGROUND

We examined the relationship between lunate morphology (type 1 without a medial facet; type II with a medial facet) and dorsal intercalated segmental instability (DISI) in patients with scapholunate ligament injuries. We tested the primary null hypothesis that there is no relationship between lunate morphology and development of DISI. Secondary analysis compared the agreement of classifying lunate morphology based on the presence of a medial lunate facet, capitate-to-triquetrum (CT) distance, and magnetic resonance imaging (MRI).

METHODS

We performed a retrospective chart review of patients with known scapholunate ligament injuries from 2001 to 2016. Posterior-anterior radiographs and MRI, when available, were evaluated. CT distances were measured as a secondary classification method. DISI and scapholunate instability were determined as radiolunate angle >15° and scapholunate angle >60°, respectively. Differences between groups were determined using chi-square analysis with significance set at P < .05. Agreement between plain radiographs, MRI, and CT distance was calculated using the kappa statistic.

RESULTS

Our search found 58 of 417 patients who met inclusion criteria; 41 of 58 had type II and 17 of 58 had type I lunates. There was no significant difference between groups in regard to DISI or scapholunate instability. Subanalysis using MRI alone or correcting any discrepancy between plain film and MRI classification, using MRI as the standard, found no difference between groups in regard to DISI or scapholunate instability.

CONCLUSIONS

In patients with scapholunate ligament injuries, there are no differences in the development of DISI or scapholunate instability between patients with type I and type II lunates.

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.

Evaluation of midcarpal capitate contact mechanics in normal, injured and post-operative wrists

BACKGROUND

Scapholunate ligament injury is a commonly occurring carpal ligament injury. Pathology associated with scapholunate ligament injury depends on several factors such as the time after injury, type of injury (instability) and the development of osteoarthritis. The aim of this study was to investigate and compare contact mechanics in the lunocapitate and scaphocapitate joints in the normal, injured (scapholunate dissociation) and repaired (postoperative) wrist.

METHODS

Four human subjects with scapholunate ligament dissociation participated in this study. MR images of normal (contralateral), injured and postoperative wrists were obtained during relaxed condition and during active light grasp. Relaxed MR images were used to construct model geometry (bones with cartilage) for the capitate, lunate and scaphoid. Kinematic transformations were obtained by using image registration between the unloaded and functionally loaded image sets. Joint surface contact mechanics were then calculated.

FINDINGS

All contact measures (contact force, pressure, mean pressure and area) tended to increase with injury in both articulations. A significantly higher contact area was found in the injured scaphocapitate joint compared to normal. A significant increase in peak pressure was observed in the postoperative state compared to normal.

INTERPRETATION

Injury to the scapholunate ligament increased contact measures, suggesting a risk for onset of osteoarthritis in both the scaphocapitate and lunocapitate joints. Surgical repair appeared to restore most measures of contact mechanics to near normal values, more so for the lunocapitate joint when compared to scaphocapitate joint. The elevated postoperative peak pressures indicate the difficulty to fully restore joint mechanics.

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.

Common radiographic imaging modalities fail to accurately predict capitate morphology

BACKGROUND

There are three morphologies of the capitate based on its lunate and scaphoid articulations: flat, spherical, and V-shaped. Following a proximal row carpectomy (PRC), the capitate articulates with the lunate facet of the radius, altering contact biomechanics at the radiocarpal joint. Therefore, capitate morphology may influence contact pressures at the capitolunate articulation and influence clinical outcomes after PRC. However, it remains unclear which diagnostic imaging technique most reliably distinguishes between capitate morphologies.

METHODS

We evaluated the ability of plain radiographs, two-dimensional computed tomography (2D-CT), three-dimensional (3D)-CT reconstruction, and magnetic resonance imaging (MRI) to predict capitate type in 47 fresh frozen cadaver wrists. Two attending hand surgeons and one hand surgery fellow characterized capitate type based on each imaging modality. True capitate type was determined after gross dissection. We determined the reliability of each modality to predict capitate morphology.

RESULTS

We found all four imaging modalities to have a low sensitivity and specificity for predicting capitate morphology. Plain radiographs, 2D-CT, 3D-CT, and MRI had sensitivities/specificities of 0.46/0.57, 0.54/0.72, 0.54/0.52, and 0.56/0.65, respectively. All modalities had high negative predictive values for detecting the more rare V-shaped capitate subtype (range 91-94 %). Inter-rater reliability was poor for all modalities.

CONCLUSION

These data suggest that plain radiographs, CT, 3D-CT, and MRI are not helpful in preoperative determination of true capitate morphology. Plain radiographs are as effective as more cost-intensive modalities in ruling out V-shaped capitates.

The effect of lunate morphology on the 3-dimensional kinematics of the carpus

PURPOSE

To assess carpal kinematics in various ranges of motion in 3 dimensions with respect to lunate morphology.

METHODS

Eight cadaveric wrists (4 type I lunates, 4 type II lunates) were mounted into a customized platform that allowed controlled motion with 6 degrees of freedom. The wrists were moved through flexion-extension (15°-15°) and radioulnar deviation (RUD; 20°-20°). The relative motion of the radius, carpus, and third metacarpal were recorded using optical motion capture methods.

RESULTS

Clear patterns of carpal motion were identified. Significantly greater motion occurred at the radiocarpal joint during flexion-extension of type I wrist than a type II wrist. The relative contributions of the midcarpal and radiocarpal articulations to movement of the wrist differed between the radial, the central, and the ulnar columns. During wrist flexion and extension, these contributions were determined by the lunate morphology, whereas during RUD, they were determined by the direction of wrist motion. The midcarpal articulations were relatively restricted during flexion and extension of a type II wrist. However, during RUD, the midcarpal joint of the central column became the dominant articulation.

CONCLUSIONS

This study describes the effect of lunate morphology on 3-dimensional carpal kinematics during wrist flexion and extension. Despite the limited size of the motion arcs tested, the results represent an advance on the current understanding of this topic.

CLINICAL RELEVANCE

Differences in carpal kinematics may explain the effect of lunate morphology on pathological changes within the carpus. Differences in carpal kinematics due to lunate morphology may have implications for the management of certain wrist conditions.

An association between lunate morphology and scaphoid-trapezium-trapezoid arthritis

The purpose of this study was to determine if an association exists between scaphoid-trapezium-trapezoid arthritis and lunate morphology. Plain neutral posteroanterior radiographs were evaluated for 48 patients with STT arthritis and 96 patients from a control group. Lunate type was determined using capitate-triquetrum (C-T) distance. A type I lunate was defined as a C-T distance < or =2 mm. A type II lunate was defined as a C-T distance > or =4 mm. Lunate type was recorded and compared between those with STT arthritis and a control group. The groups were similar with regard to age, gender and handedness. Type II lunates were found in 83% of cases with STT arthritis and in 64% of controls. STT OA was associated with type II lunate wrists (P = 0.02; OR = 0.35; CI: 0.15-0.82). We postulate that variations in scaphoid motion secondary to lunate morphology may contribute to the development of STT OA.