Interdisciplinary consensus statements on imaging of scapholunate joint instability

Gantry-free cone-beam CT arthrography for diagnosis of scapholunate ligament injuries: accelerating the preoperative work-up in acute wrist trauma

OBJECTIVE

Combining fluoroscopy and high-resolution cone-beam CT (CBCT) in a multipurpose scanner without a conventional gantry holds the potential for time-saving in musculoskeletal interventions. This study investigated the performance of gantry-free CBCT arthrography in patients with suspected scapholunate ligament (SLL) tears.

MATERIALS AND METHODS

Fifty-five patients (29 men, 46.0 ± 15.3 years) who underwent preoperative gantry-free CBCT arthrography between June 2021 and March 2024 were analyzed retrospectively. Three radiologists assessed CBCT arthrograms for tears of the palmar and dorsal SLL segments. Surgical reports served as the reference standard for calculating indicators of diagnostic accuracy. Interreader agreement was tested by computing Krippendorff α. Radiation dose and examination time were recorded.

RESULTS

Tears of the palmar and dorsal SLL segment were recorded in 25 (45%) and 6 patients (11%), respectively. CBCT arthrography facilitated good sensitivity (range for all readers: 84-92%) and excellent specificity (93-97%) in the assessment of the palmar SLL. For the dorsal SLL, sensitivity (83-100%) and specificity (96-98%) were even higher. Substantial agreement was determined for both the palmar (α = 0.83, 95% CI: 0.74-0.90) and dorsal SLL (0.84, 0.70-0.95). The mean volume CT dose index for CBCT arthrography was 3.2 ± 1.4 mGy. Not requiring patient repositioning, the median time between fluoroscopy-guided contrast injection and CBCT was 3:05 min (2:31-3:50 min).

CONCLUSION

Gantry-free CBCT arthrography allows for excellent accuracy in the preoperative diagnosis of SLL tears with low radiation dose. The ability to alternate between fluoroscopy and CBCT without repositioning facilitates a "one-stop-shop" approach with short examination time.

KEY POINTS

Question Performing fluoroscopy-guided arthrography and high-resolution cone-beam CT without patient repositioning appears advantageous for the preoperative work-up of distal radius fractures with concomitant scapholunate ligament injuries. Findings Gantry-free cone-beam CT arthrography allowed for short examination times and high diagnostic accuracy for either segment of the scapholunate ligament (89-98% versus surgery). Clinical relevance Preoperative assessment of scapholunate instability influences treatment since surgeons can reduce radius fractures and perform osteosynthesis via a dorsal portal to simultaneously stabilize the scapholunate compartment or use an additional dorsal access route for ligament suture and transfixation.

Dynamic CT features of scapholunate instability during the wrist extension to flexion-An in vivo study

Purpose

This biomechanical study aimed to assess the change in the radioscaphoid and the radiolunate angles during wrist extension to flexion in scapholunate instability compared to the healthy wrist.

Methods

Dynamic CT scans of 19 participants with no history of wrist pathology and 19 patients with scapholunate instability without degenerative changes were selected. Motion sequence studied was wrist extension to flexion. Image segmentation followed by 3D registration techniques were used to calculate the displacement field between scaphoid and lunate models in each time point. The radiocarpal angles and centroid positions were computed in the neutral wrist and throughout wrist motion. Comparisons were made between the normal and the scapholunate instability wrists.

Results

The scapholunate instability wrist had less range of extension to flexion compared to the normal wrist. The scapholunate instability scaphoid was flexed and internally rotated in the neutral wrist position and throughout the range of motion. The scapholunate instability scaphoid centroid remained radial and distal in the extended wrist. The scapholunate instability lunate was significantly extended from wrist 20° extension to 50° flexion. The scapholunate instability lunate centroid was more ulnar from 70° wrist extension to 50° flexion.

Conclusions

The scapholunate instability scaphoid demonstrated rotational abnormalities in two planes throughout the wrist motion and abnormal centroid positions in the extended wrist. The lunate extension in scapholunate instability was significant mostly during wrist flexion. Radioscaphoid instability appear to be the primary pathology in SLI and can be used to differentiate the SLI wrist from the normal throughout wrist extension to flexion. Lunate extension is not different between the normal and scapholunate instability in the extended wrist.

Level of evidence

Level III.

Overview for developing Delphi-based interdisciplinary consensus statements on imaging: pros and cons

This review paper offers a concise guide on how to execute Delphi-based interdisciplinary consensus statements on imaging. Fundamental to the Delphi methodology are several core principles. First, an initial key element is the selection of experts, known as panelists. Second is the principle of anonymity among participants, ensuring that no single individual or group applies excessive influence over others. Third, the methodology involves iterative rounds where statements are presented repeatedly, allowing for controlled feedback. Lastly, after each round, participants are given insight into the collective panel's previous responses. This knowledge enables them to potentially reconsider and adjust their positions in subsequent rounds, driving towards the group consensus. These principles emphasize the critical role of statistical group responses and the structured interaction inherent in the Delphi approach. Looking at the broader process, the development of Delphi-based interdisciplinary consensus statements on imaging unfolds through several stages. It begins with identifying the research field or the consensus statements in question. This is followed by undertaking comprehensive literature research. Subsequently, pertinent questions and their corresponding statements are crafted. The process then moves on to administering anonymous, iterative questionnaire rounds. Feedback, both on an individual and collective level, is provided between the rounds. The process culminates in the summarization and reporting of the finalized Delphi-based interdisciplinary consensus statements on imaging.

Catch the shift: Ultrasound diagnosis of scapholunate lesion during Watson test

Scapholunate ligament lesion is the most common ligament lesion in the wrist. We assessed the reliability of sonography in detecting it during Watson test. Twenty patients with scapholunate ligament lesion confirmed on MRI and intraoperatively were assessed preoperatively between July 2020 and April 2023. Sonography was performed on the scaphoid dorsal subluxation in wrist neutral and during Watson test and compared with the healthy contralateral side. Dorsal subluxation was measured by two independent investigators and intra- and inter-observer reliability were assessed. We found a significant difference between dorsal subluxation of the scaphoid in the healthy (0.89 mm, SD 0.67 mm) compared to the pathological side (1.67 mm, SD 0.95 mm). Reliability was very good and the standard error of measurement was less than 0.4 mm for all measurements. Sonography during Watson test demonstrated high reliability in diagnosing scapholunate lesions. LEVEL OF EVIDENCE: III.

Post-processing of quantitative 4D-CT for initial evaluation of scapholunate Instability: Assessment of simplified approaches to data analysis

OBJECTIVES

To evaluate the diagnostic performance of simplified post-processing approaches for quantitative wrist 4D-CT in the assessment of scapholunate instability (SLI).

METHODS

A prospective monocentric case-control study included 60 patients with suspected post-traumatic scapholunate ligament (SLL) tears and persistent pain. Of these, 40 patients exhibited SLL tears, subdivided into two groups of 20 each: one group with completely torn ligaments and the other with partially torn ligaments. The remaining 20 patients, whose SLLs were intact, served as controls. 4D-CT and CT arthrography were performed, and post-processed by two readers using three approaches: the standard method with full data assessment and dedicated software, partial data assessment with post-processing software (bone locking), and partial data assessment without post-processing software (no bone locking). The scapholunate gap (SLG) parameter was measured in millimeters to evaluate scapholunate diastasis during radioulnar deviation (RUD). The scapholunate ligament status on CT arthrography was considered the gold standard.

RESULTS

The SLG-derived parameters (range, mean, and maximal values) were significantly increased in patients with both intact and torn scapholunate ligaments across all post-processing approaches (P values ranging from 0.001 to 0.004). SLG range was the best parameter for diagnosing SLL tears, with ROC AUC values ranging from 0.7 to 0.88 across the three post-processing methods. The interobserver reproducibility was better with the alternative approaches (ICC values 0.93-0.96) compared to the standard approach (ICC values 0.65-0.72). Additionally, post-processing time was shorter with the alternative approaches, especially when specific software was not used (reduced from 10 to three minutes).

CONCLUSION

Simpler approaches to wrist 4D-CT data analysis yielded acceptable diagnostic performances and improved interobserver reproducibility compared to the standard approach.

Biomechanical evaluation of the wrist after scaphotrapeziotrapezoid arthrodesis

BACKGROUND

The main objective of the present study was to present the biomechanical properties of the wrist in patients who underwent scaphotrapeziotrapezoid arthrodesis when compared to a healthy control hand.

METHODS

The study group consisted of 29 consecutive patients who underwent a scaphotrapeziotrapezoid wrist arthrodesis at least 1 year before the research onset. Both hands of all patients were examined in 4 main categories.

RESULTS

Average score obtained in the VAS, before the surgery, without motion of the wrist was 5.21 (SD = 3.04), whereas with wrist motion, it was 8.10 (SD = 1.37). Nineteen (65.52%) patients exhibited weakened wrist muscle strength. After the surgery, only 5 (17.24%) patients declared pain in the wrist. Furthermore, the results obtained in the VAS statistically significant differed from the ones before (p < 0.05). Twenty-eight (96.55%) patients were able to resume their profession. Twenty-seven (93.10%) patients stated that they would opt for the operation again. The peak torque during the analysis of extension of the wrist in the isometric protocol was found to be 8.1 Nm (SD = 2.9), 7.9 Nm (SD = 2.3), and 7.9 Nm (SD = 2.5) in the operated hands and 10.9 Nm (SD = 3.2), 9.6 Nm (SD = 2.9), and 9.1 Nm (SD = 3.8) in non-operated hand for 30° extension, no-flexion, and 30° flexion positions, respectively (p < 0.05).

CONCLUSION

The current study is the first to present the biomechanical parameters of flexor and extensor muscles of the wrist and fingers in patients after the said procedure. Biomechanical assessments with additional isometric, isotonic, and isokinetic tests provide an opportunity to objectify treatment outcomes and guide appropriate rehabilitation by monitoring its effects.

LEVEL OF EVIDENCE

III.

Measurement of Scapholunate Joint Space Width on Real-Time MRI-A Feasibility Study

INTRODUCTION

The scapholunate interosseous ligament is pivotal for wrist stability, and its impairment can result in instability and joint degeneration. This study explores the application of real-time MRI for dynamic assessment of the scapholunate joint during wrist motion with the objective of determining its diagnostic value in efficacy in contrast to static imaging modalities.

MATERIALS AND METHODS

Ten healthy participants underwent real-time MRI scans during wrist ab/adduction and fist-clenching maneuvers. Measurements were obtained at proximal, medial, and distal landmarks on both dynamic and static images with statistical analyses conducted to evaluate the reliability of measurements at each landmark and the concordance between dynamic measurements and established static images. Additionally, inter- and intraobserver variabilities were evaluated.

RESULTS

Measurements of the medial landmarks demonstrated the closest agreement with static images and exhibited the least scatter. Distal landmark measurements showed a similar level of agreement but with increased scatter. Proximal landmark measurements displayed substantial deviation, which was accompanied by an even greater degree of scatter. Although no significant differences were observed between the ab/adduction and fist-clenching maneuvers, both inter- and intraobserver variabilities were significant across all measurements.

CONCLUSIONS

This study highlights the potential of real-time MRI in the dynamic assessment of the scapholunate joint particularly at the medial landmark. Despite promising results, challenges such as measurement variability need to be addressed. Standardization and integration with advanced image processing methods could significantly enhance the accuracy and reliability of real-time MRI, paving the way for its clinical implementation in dynamic wrist imaging studies.

Detection of scapholunate interosseous ligament injury using dynamic computed tomography-derived arthrokinematics: A prospective clinical trial

Scapholunate interosseous ligament injuries are a major cause of wrist instability and can be difficult to diagnose radiographically. To improve early diagnosis of scapholunate ligament injuries, we compared injury detection between bilateral routine clinical radiographs, static CT, and dynamic four-dimensional CT (4DCT) during wrist flexion-extension and radioulnar deviation. Participants with unilateral scapholunate ligament injuries were recruited to a prospective clinical trial investigating the diagnostic utility of 4DCT imaging for ligamentous wrist injury. Twenty-one participants underwent arthroscopic surgery to confirm scapholunate ligament injury. Arthrokinematics, defined as distributions of interosseous proximities across radioscaphoid and scapholunate articular surfaces at different positions within the motion cycle, were used as CT-derived biomarkers. Preoperative radiographs, static CT, and extrema of 4DCT were compared between uninjured and injured wrists using Wilcoxon signed rank or Kolmogorov-Smirnov tests. Median interosseous proximities at the scapholunate interval were significantly greater in the injured versus the uninjured wrists at static-neutral and maximum flexion, extension, radial deviation, and ulnar deviation. Mean cumulative distribution functions at the radioscaphoid joint were not significantly different between wrists but were significantly shifted at the scapholunate interval towards increased interosseous proximities in injured versus uninjured wrists in all positions. Median and cumulative distribution scapholunate proximities from static-neutral and 4DCT-derived extrema reflect injury status.

ACR Appropriateness Criteria® Chronic Hand and Wrist Pain: 2023 Update

Chronic hand and wrist pain is a common presenting complaint. The intricate anatomy results in a variety of pain generators-multiple bones, articular cartilage, intrinsic ligaments, triangular fibrocartilage complex, joint capsules and synovium, tendons and tendon sheaths, muscles, and nerves-in a compact space. The need for imaging and the choice of the appropriate imaging modality are best determined by the patient's presentation, physical examination, and the clinician's working differential diagnosis. Radiography is usually appropriate as the initial imaging study in the evaluation of chronic hand or wrist pain. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Arthroscopic management of scapholunate complex injuries associated with distal radius fractures

Scapholunate complex injuries are the most frequent lesions associated with distal radius fractures and the treatment algorithm according to the stage of the instability remains controversial. However, there is an admitted consensus around the necessary treatment of the associated high-grade instabilities. They occur frequently in young patients after high energy trauma, and not treated, they can lead to chronic wrist pain and eventually to scapholunate advanced collapse. The routine use of the arthroscopy provides an accurate intraoperative staging of the lesions and allows a tailored treatment depending on the severity of the scapholunate instability.

Hand and wrist - what the hand surgeon wants to know from the radiologist

Hand surgeons, as unique specialists, appreciate the complexity of the anatomy of the hand. A hand is not merely a group of anatomic structures but a separate organ that works by feeling, sending information to the brain, and enabling a variety of movements, from precise skills to firm tasks. Acute and chronic problems interfere with complicated hand function and potentially influence work or daily life activities for a long time. Thus, the surgeon's role is to propose appropriate treatment with predictable results. This paper attempts to specify the preoperative considerations and their influence on the choice of surgical procedure and the assessment of results potentially influencing further treatment. We have divided the manuscript by anatomical structures, which is a natural surgical assessment and planning approach. The most common problems were highlighted to introduce the method of decision-making and surgical solutions.

[Distal radius fracture-tactic and approach]

OBJECTIVE

The aim of surgical treatment is fracture healing with restored alignment, rotation, and joint surface. Stable fixation allows for functional postoperative aftercare.

INDICATIONS

Displaced intra- and extra-articular fractures which either could not be adequately reduced or in which a secondary displacement is to expected due to instability criteria. The following factors are considered instability criteria: age > 60 years, female, initial dorsal displacement > 20°, dorsal comminution, radial shortening > 5 mm, palmar displacement.

CONTRAINDICATIONS

The only absolute contraindication is if the patient is deemed unfit for surgery due to concerns regarding anesthesia. Old age is a relative contraindication, as it is currently debated whether older patients benefit from the operation.

SURGICAL TECHNIQUE

The surgical technique is guided by the fracture pattern. Palmar plating is most commonly performed. If the joint surface needs to be visualized, a dorsal approach (in combination with another approach or alone) or arthroscopically assisted fixation should be chosen.

POSTOPERATIVE MANAGEMENT

In general, a functional postoperative regime can be carried out after plate fixation with mobilization without weightbearing. Short-term splinting can provide pain relief. Concomitant ligamentous injuries and fixations, which are not stable enough for functional aftercare (such as k‑wires) require a longer period of immobilization.

RESULTS

Provided the fracture is reduced correctly, osteosynthesis improves functional outcome. The complication rate ranges between 9 and 15% with the most common complication being tendon irritation/rupture and plate removal. Whether surgical treatment holds the same benefits for patients > 65 years as for younger patients is currently under debate.

Scapholunate ligament injuries: an instructional review for the FRCS examination

An instructional review of the anatomy, investigation, and management of scapholunate ligament injuries. Aimed at the knowledge level required for the trauma and orthopaedic FRCS examination.

Use of Generalizability Theory Evaluating Comparative Reliability of the Scapholunate Interval Measurement With X-ray, CT, and US

RATIONALE AND OBJECTIVES

There is no universally accepted standard technique for measuring the scapholunate interval and no specific sources of measurement error have been identified. We aimed to establish a set of normal radiological criteria for the scapholunate interval that could be used in comparative studies of wrist pathology to determine interobserver reliability and to identify potential errors that might influence measurements.

MATERIALS AND METHODS

A total of 60 healthy volunteers participated in the study. Scapholunate interval was measured by three independent observers using X-ray, CT, and US in four positions, including neutral, fist, radial and ulnar deviation. Inter-observer reliability was tested using intraclass correlation coefficient. Generalizability theory was applied to evaluate specific sources of measurement error related to participant, observer, imaging modality and measurement position.

RESULTS

In neutral position, the scapholunate interval measured by X-ray, CT, and US was 3.1 mm, 3.5 mm and 3.5 mm respectively. The interval remained constant during fist and radial deviation but decreased during ulnar deviation. Correlation coefficients ranged from 0.874 to 0.907 for X-ray, 0.773-0.881 for CT and 0.964-0.979 for US. In the generalizability study, the participant x modality x position interaction accounted for the largest proportion of total variance (29%).

CONCLUSION

X-ray, CT, and US are reliable modalities for measuring the scapholunate interval, with US having the highest reliability. Participant and position factors may independently contribute to measurement error. Therefore, standardized measurement positions are recommended to obtain reliable measurement results.

Assessment of Scapholunate Instability on 4D CT Scans in Patients with Inconclusive Conventional Images

Background Initial imaging work-up using radiography and CT arthrography sometimes can be insufficient to identify a scapholunate (SL) instability (SLI) in patients suspected of having SL ligament tears. Purpose To determine the diagnostic performance of four-dimensional (4D) CT in the identification of SLI and apply the findings to patients suspected of having SLI and with inconclusive findings on radiographs and CT arthrograms. Materials and Methods This prospective single-center study enrolled participants suspected of having SLI (recent trauma, dorsal pain, positive Watson test results, decreased grip strength) between March 2015 and March 2020. Participants with wrist fractures, substantial joint stiffness, or history of wrist surgery were excluded. Each participant underwent radiography, CT arthrography, and 4D CT on the same day. Participants were divided into three groups: those with no SLI, those with SLI, and those with inconclusive results. SL gap and radioscaphoid and lunocapitate angle were measured using semiautomatic quantitative analysis of 4D CT images by two independent readers. Receiver operating characteristic curves were used to evaluate the diagnostic performance of 4D CT. Thresholds were determined with the Youden index and were applied to the inconclusive group. Results Of the 150 included participants (mean age, 41 years ± 14 [SD]; 102 male, 48 female), there were 63 with no SLI, 48 with SLI, and 39 with inconclusive results. The maximum value and range of SL gap measurements on 4D CT scans showed high sensitivity (83% [40 of 48] and 90% [43 of 48], respectively) and high specificity (95% [59 of 62] and 81% [50 of 62], respectively) in the identification of SLI. At least one of these parameters was abnormal on 4D CT scans in 17 of 39 (44%) participants in the inconclusive group, and 10 of 17 (59%) participants had confirmed SLI. In the 22 participants in the inconclusive group with no indication of SLI at 4D CT, follow-up showed no evidence of SLI in 10 (45%) and enabled confirmation of SLI via arthroscopy in three (14%). Conclusion Scapholunate gap measurements on kinematic 4D CT scans enabled correct identification of SLI in 59% of participants with inconclusive results on conventional images. ClinicalTrials.gov registration no. NCT02401568 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Demehri and Ibad in this issue.

Interdisciplinary consensus statements on imaging of DRUJ instability and TFCC injuries

OBJECTIVES

The purpose of this agreement was to establish evidence-based consensus statements on imaging of distal radioulnar joint (DRUJ) instability and triangular fibrocartilage complex (TFCC) injuries by an expert group using the Delphi technique.

METHODS

Nineteen hand surgeons developed a preliminary list of questions on DRUJ instability and TFCC injuries. Radiologists created statements based on the literature and the authors' clinical experience. Questions and statements were revised during three iterative Delphi rounds. Delphi panelists consisted of twenty-seven musculoskeletal radiologists. The panelists scored their degree of agreement to each statement on an 11-item numeric scale. Scores of "0," "5," and "10" reflected complete disagreement, indeterminate agreement, and complete agreement, respectively. Group consensus was defined as a score of "8" or higher for 80% or more of the panelists.

RESULTS

Three of fourteen statements achieved group consensus in the first Delphi round and ten statements achieved group consensus in the second Delphi round. The third and final Delphi round was limited to the one question that did not achieve group consensus in the previous rounds.

CONCLUSIONS

Delphi-based agreements suggest that CT with static axial slices in neutral rotation, pronation, and supination is the most useful and accurate imaging technique for the work-up of DRUJ instability. MRI is the most valuable technique in the diagnosis of TFCC lesions. The main indication for MR arthrography and CT arthrography are Palmer 1B foveal lesions of the TFCC.

CLINICAL RELEVANCE STATEMENT

MRI is the method of choice for assessing TFCC lesions, with higher accuracy for central than peripheral abnormalities. The main indication for MR arthrography is the evaluation of TFCC foveal insertion lesions and peripheral non-Palmer injuries.

KEY POINTS

• Conventional radiography should be the initial imaging technique in the assessment of DRUJ instability. CT with static axial slices in neutral rotation, pronation, and supination is the most accurate method for evaluating DRUJ instability. • MRI is the most useful technique in diagnosing soft-tissue injuries causing DRUJ instability, especially TFCC lesions. • The main indications for MR arthrography and CT arthrography are foveal lesions of the TFCC.

Evaluation of Scapholunate Injury and Repair with Dynamic (4D) CT: A Preliminary Report of Two Cases

Background  In predynamic or dynamic scapholunate (SL) instability, standard diagnostic imaging may not identify SL interosseous ligament (SLIL) injury, leading to delayed detection and intervention. This study describes the use of four-dimensional computed tomography (4DCT) in identifying early SLIL injury and following injured wrists to 1-year postoperatively. Description of Technique  4DCT acquires a series of three-dimensional volume data with high temporal resolution (66 ms). 4DCT-derived arthrokinematic data can be used as biomarkers of ligament integrity. Patients and Methods  This study presents the use of 4DCT in a two-participant case series to assess changes in arthrokinematics following unilateral SLIL injury preoperatively and 1-year postoperatively. Patients were treated with volar ligament repair with volar capsulodesis and arthroscopic dorsal capsulodesis. Arthrokinematics were compared between uninjured, preoperative injured, and postoperative injured (repaired) wrists. Results  4DCT detected changes in interosseous distances during flexion-extension and radioulnar deviation. Generally, radioscaphoid joint distances were greatest in the uninjured wrist during flexion-extension and radioulnar deviation, and SL interval distances were smallest in the uninjured wrist during flexion-extension and radioulnar deviation. Conclusion  4DCT provides insight into carpal arthrokinematics during motion. Distances between the radioscaphoid joint and SL interval can be displayed as proximity maps or as simplified descriptive statistics to facilitate comparisons between wrists and time points. These data offer insight into areas of concern for decreased interosseous distance and increased intercarpal diastasis. This method may allow surgeons to assess whether (1) injury can be visualized during motion, (2) surgery repaired the injury, and (3) surgery restored normal carpal motion. Level of Evidence  Level IV, Case series.

Current Concepts in Scapholunate Instability Without Arthritic Changes

Scapholunate instability (SLI) is the most common carpal instability described. SLI leads to a degenerative arthritic pattern known as scapholunate advanced collapse (SLAC). Diagnosis of SLI can be challenging in pre-dynamic and dynamic stages. CT arthrogram, MR arthrogram and dynamic fluoroscopy are helpful in diagnosis while arthroscopy remains the gold standard. SLI is a multi-ligament injury, which involves not only the scapholunate interosseous ligament (SLIL) but also the extrinsic carpal ligaments. Hence, it is better described as an injury compromising the 'dorsal scapholunate(dSLL) complex'. A repair can be attempted for acute SLI presenting within 6 weeks of injury. Reconstruction is the mainstay of treatment for chronic SLI without degenerative changes. Multiple repair techniques have been described which include capsulodesis and tenodesis procedures. The clinical outcomes of the techniques have improved over the years. However, a common problem of all these techniques is the lack of long-term data on the outcomes and deteriorating radiological parameters over time. SLI staging is an important factor to be considered in choosing the reconstruction techniques for a better outcome. Currently, there is a trend towards more biological and less invasive techniques. Regardless of the technique, it is important to preserve the nerve supply of the dorsal capsuloligamentous structures of the wrist. Arthroscopic techniques being minimally invasive have the advantage of less collateral damage to the capsuloligamentous structures. Rehabilitation involves a team approach where a protected dart thrower's motion is allowed after a period of immobilization. Strengthening SL-friendly muscles and inhibiting SL-unfriendly muscles is a key principle in rehabilitation.

Kinematic 4D CT case-control study of wrist in dart throwing motion "in vivo": comparison with other maneuvers

OBJECTIVES

To compare the diagnostic performance of scapholunate gap (SLG) measurements acquired with dart throwing (DT), radio-ulnar deviation (RUD), and clenching fist (CF) maneuvers on 4D CT for the identification of scapholunate instability.

METHODS

In this prospective study, 47 patients with suspected scapholunate interosseous ligament (SLIL) tears were evaluated from March 2015 to March 2020 with semiautomatic quantitative analysis on 4D CT. Five parameters (median, maximal value, range, and coefficient of variation) for SLG, lunocapitate angle (LCA), and radioscaphoid angle (RSA) obtained during DT maneuver were evaluated in patients with and without SLIL tears. CT arthrography was used as the gold standard for the SLIL status. The SLG values obtained were also compared with those obtained during CF and RUD maneuvers.

RESULTS

Significant differences in all SLG- and LCA-derived parameters are found between patients with and without SLIL tears with DT (p < 0.003). The best diagnostic performance for the diagnosis of SLIL tears was obtained with median and maximal SLG values (sensitivity and specificity of 86-89% and 95%) and with maximal and range LCA values (sensitivity and specificity of 86% and 74%). No significant differences were observed for RSA values (p > 0.275). The SLG range obtained with DT maneuver was the only dynamic parameter statistically different between patients with partial and complete torn SLIL (p = 0.037).

CONCLUSION

4D CT of the wrist during DT showed a similar performance than RUD and a better performance than CF for the differentiation between patients with and without SLIL tears.

KEY POINTS

• Four-dimensional computed tomography can dynamically assess scapholunate instability. • The best results for differentiating between patients with and without SLIL tears were obtained with SLG median and maximal values. • The dart throwing and radio-ulnar deviation maneuvers yielded the best results for the dynamic evaluation of scapholunate instability.