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.

Isolated Scaphoid Dislocation: A Case Report and Review of the Literature

Background  Isolated scaphoid dislocation is an exceedingly rare event with only 55 cases described. Closed reduction followed by operative intervention with Kirschner's wires (K-wire) fixation and ligamentous reconstruction are the mainstays of treatment. Case Description  We describe a patient with a solitary scaphoid dislocation treated with initial closed reduction and urgent open reduction with K-wire stabilization and ligamentous repair. The patient was immobilized for 6 weeks and on 24-month follow-up, the patient was doing well with no limitations in his daily living, no pain, and acceptable range of motion. Literature Review  A literature review was performed on the 55 cases described in the English language. The majority of the patients were males, aged between 18 and 79 years, and presented with motor vehicle accidents as the most common mechanism. Historically, isolated scaphoid dislocations were treated with closed reduction. However, K-wire fixation and, now, K-wire fixation coupled with ligamentous injury repair remain the current treatments of choice. Avascular necrosis of the scaphoid remains a rare event with only one documented case. Overall, patients do well with only minor pain and limited wrist movements. Notably, only eight cases were associated with type-II lunates. Type-II lunates appear to be protective for carpal injury. Clinical Relevance  Although isolated scaphoid dislocations remain a rare event, understanding the anatomy and the current ability to restore carpal anatomy is important. Type-II lunates appear to confer protection from carpal injuries.

Lunate Reconstruction Using Osteochondral Vascularized Graft in Kienböck's Disease

There is a general consensus that the pathogenesis for Kienböck's disease remains uncertain, though it is probably related to nonphysiologic stress transmission across the lunate, acting in concert with one of several possible vascular abnormalities. Most surgical treatments focus on mechanical aspects rather than real physiopathology, but in the recent years several articles have shown the utility of vascularized grafts in the treatment of Kienböck's disease, especially in its early stages. The authors present a case of a successfully reconstruction of a IIIA stage Kienböck's disease with an osteochondral vascularized graft from medial femoral condyle.

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.

The effect of lunate morphology in Kienböck disease

PURPOSE

To determine if the absence (type I lunate) or presence (type II lunate) of a medial hamate facet on the lunate affects the radiographic characteristics of patients presenting with Kienböck disease.

METHODS

A retrospective review was performed on all patients evaluated at our institution from 2002 to 2010 with a diagnosis of Kienböck disease confirmed on plain radiographs in concert with magnetic resonance imaging (MRI) and/or bone scan. Study groups consisted of patients with type I versus type II lunates, as determined by radiographs, MRI, and/or computed tomography. Measured variables included the modified Lichtman stage on presentation, radioscaphoid angle, presence or absence of a coronal plane fracture of the lunate, modified carpal height, ulnar variance, and ulnar translocation of the carpus at the time of presentation.

RESULTS

A total of 106 wrists were examined, of which 75 were type I (71%) and 31 were type II (29%) lunates. At the time of presentation, there was significantly more advanced disease (stage IIIA or greater) in patients with type I (N = 64, 86%) compared with those with type II lunates (N = 19, 61%). Coronal fractures of the lunate were more prevalent in patients with type I (N = 58, 75%) compared with type II lunates (N = 18, 58%). In the absence of a coronal fracture, radioscaphoid angles were greater in patients with a type I (53°) versus a type II lunate (45°).

CONCLUSIONS

Lunate morphology may affect the severity of Kienböck disease at the time of initial presentation. Type II lunates appear to be protective against coronal fractures and scaphoid flexion deformities. This study provides further evidence that lunate morphology affects carpal pathology and may have implications for treatment options in Kienböck disease.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic III.

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.