The diagnosis and treatment of scapholunate instability

Dynamic assessment of scapholunate ligament status by real-time magnetic resonance imaging: an exploratory clinical study

OBJECTIVE

Clinical-standard MRI is the imaging modality of choice for the wrist, yet limited to static evaluation, thereby potentially missing dynamic instability patterns. We aimed to investigate the clinical benefit of (dynamic) real-time MRI, complemented by automatic analysis, in patients with complete or partial scapholunate ligament (SLL) tears.

MATERIAL AND METHODS

Both wrists of ten patients with unilateral SLL tears (six partial, four complete tears) as diagnosed by clinical-standard MRI were imaged during continuous active radioulnar motion using a 1.5-T MRI scanner in combination with a custom-made motion device. Following automatic segmentation of the wrist, the scapholunate and lunotriquetral joint widths were analyzed across the entire range of motion (ROM). Mixed-effects model analysis of variance (ANOVA) followed by Tukey's posthoc test and two-way ANOVA were used for statistical analysis.

RESULTS

With the increasing extent of SLL tear, the scapholunate joint widths in injured wrists were significantly larger over the entire ROM compared to those of the contralateral healthy wrists (p<0.001). Differences between partial and complete tears were most pronounced at 5°-15° ulnar abduction (p<0.001). Motion patterns and trajectories were altered. Complete SLL deficiency resulted in complex alterations of the lunotriquetral joint widths.

CONCLUSION

Real-time MRI may improve the functional diagnosis of SLL insufficiency and aid therapeutic decision-making by revealing dynamic forms of dissociative instability within the proximal carpus. Static MRI best differentiates SLL-injured wrists at 5°-15° of ulnar abduction.

Arthroscopic Scapholunate Synthetic Ligamentoplasty

The scapholunate ligament is made of 3 portions: proximal, volar, and dorsal. The latter is the major stabilizer of the scapholunar pair, and its lesion is bound to cause a destabilization of the carpus, as well as scapholunar diastasis, dorsal intercalated segment instability, then eventually SLAC (i.e., scapholunate advanced collapse) wrist. The healing process of this ligament, either spontaneous or after primary repair with direct suture, is rarely observed and a significant number of patients are diagnosed only at a late stage, thus making an illusion of a maintained stability of the carpus first range. Management then consists of ligamentoplasty. Several open techniques are described to restore stability, but at the cost of a frequent and significant tightening of the wrist. We will introduce here an arthroscopic ligamentoplasty technique completed by a posterior capsulodesis.

Deep Learning-Based Post-Processing of Real-Time MRI to Assess and Quantify Dynamic Wrist Movement in Health and Disease

While morphologic magnetic resonance imaging (MRI) is the imaging modality of choice for the evaluation of ligamentous wrist injuries, it is merely static and incapable of diagnosing dynamic wrist instability. Based on real-time MRI and algorithm-based image post-processing in terms of convolutional neural networks (CNNs), this study aims to develop and validate an automatic technique to quantify wrist movement. A total of 56 bilateral wrists (28 healthy volunteers) were imaged during continuous and alternating maximum ulnar and radial abduction. Following CNN-based automatic segmentations of carpal bone contours, scapholunate and lunotriquetral gap widths were quantified based on dedicated algorithms and as a function of wrist position. Automatic segmentations were in excellent agreement with manual reference segmentations performed by two radiologists as indicated by Dice similarity coefficients of 0.96 ± 0.02 and consistent and unskewed Bland–Altman plots. Clinical applicability of the framework was assessed in a patient with diagnosed scapholunate ligament injury. Considerable increases in scapholunate gap widths across the range-of-motion were found. In conclusion, the combination of real-time wrist MRI and the present framework provides a powerful diagnostic tool for dynamic assessment of wrist function and, if confirmed in clinical trials, dynamic carpal instability that may elude static assessment using clinical-standard imaging modalities.

Evaluation of Dorsal Subluxation of the Scaphoid in Patients With Scapholunate Ligament Tears: A 4D CT Study

OBJECTIVE. The purpose of this study was to evaluate the variation of the posterior radioscaphoid (RS) angle in patients with and without scapholunate ligament (SLL) tears during wrist radioulnar deviation. SUBJECTS AND METHODS. Seventy-three patients with clinically suspected scapholunate instability were prospectively evaluated with 4D CT and CT arthrography from February 2015 to April 2018. The posterior RS angle is formed between the articular surface of the scaphoid fossa of the radius and the most posterior point of the scaphoid in the sagittal plane. Two independent radiologists calculated this angle during radioulnar deviation. Posterior RS angles were correlated with the SLL status and the presence of a scapholunate diastasis on conventional stress radiographs. RESULTS. Readers 1 and 2 found mean posterior RS angles of 99° and 98°, respectively, in patients without and 107° and 111°, respectively, in patients with a scapholunate diastasis. The posterior RS angle amplitude varied 7.6-9.3° in the subgroups studied. The reproducibility of posterior RS angle measurement was considered good (intraclass correlation coefficient, 0.73). Mean posterior RS angles increased 6-10% and 12-14% when patients with an intact SLL were compared with those with partial tears and full tears, respectively (p < 0.001). These values also increased 8-13% when patients with diastasis were compared with those without (p < 0.0001). A dynamic acquisition was not necessary to assess this angle, with neutral posterior RS angles yielding a sensitivity of 64% and 72% and specificity of 79% and 94% for the diagnosis of SLL tears by readers 1 and 2, respectively. CONCLUSION. Posterior RS angle tended to increase with the severity of SLL tears and with the presence of scapholunate instability and yielded high sensitivity and specificity for the detection of SLL tears.

Surgical Techniques for the Treatment of Acute Carpal Ligament Injuries in the Athlete

The treatment of athletes with carpal ligament injuries provides many challenges. Our initial goals remain to make a timely and accurate diagnosis, provide treatment options, and create an environment for shared decision making. To optimize outcomes and facilitate return to play, early surgical intervention may be warranted. This article reviews common carpal ligament injury patterns in the athlete with a focus on both classic and newer surgical techniques.

Dorsal Scaphoid Subluxation on Sagittal Magnetic Resonance Imaging as a Marker for Scapholunate Ligament Tear

PURPOSE

To evaluate the diagnostic utility of scaphoid dorsal subluxation on magnetic resonance imaging (MRI) as a predictor of scapholunate interosseous ligament (SLIL) tears and compare this with radiographic findings.

METHODS

Thirty-six MRIs were retrospectively reviewed: 18 with known operative findings of complete Geissler IV SLIL tears that were surgically repaired, and 18 MRIs performed for ulnar-sided wrist pain but no SLIL tear. Dorsal subluxation of the scaphoid was measured on the sagittal MRI cut, which demonstrated the maximum subluxation. Independent samples t tests were used to compare radiographic measurements of scapholunate (SL) gap, SL angle, and capitolunate/third metacarpal-lunate angles between the SLIL tear and the control groups and to compare radiographic measurements between wrists that had dorsal subluxation of the scaphoid and wrists that did not have dorsal subluxation. Interrater reliability of subluxation measurements on lateral radiographs and on MRI were calculated using kappa coefficients.

RESULTS

Thirteen of 18 wrists with complete SLIL tears had greater than 10% dorsal subluxation of the scaphoid relative to the scaphoid facet. Average subluxation in this group was 34%. Four of 18 wrists with known SLIL tears had no subluxation. No wrists without SLIL tears (control group) had dorsal subluxation. The SL angle, capitolunate/third metacarpal-lunate angle and SL gap were greater in wrists that had dorsal subluxation of the scaphoid on MRI. Interrater reliability of measurements of dorsal subluxation of the scaphoid was superior on MRI than on lateral x-ray.

CONCLUSIONS

An MRI demonstration of dorsal subluxation of the scaphoid, of as little as 10%, as a predictor of SLIL tear had a sensitivity of 72% and a specificity of 100%. The high positive predictive value indicates that the presence of dorsal subluxation accurately predicts SLIL tear.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Optimal detection of scapholunate ligament tears with MRI

Background Scapholunate interosseous ligament (SLIL) injuries can often be difficult to detect using magnetic resonance imaging (MRI), especially with older 1.0 and 1.5 Tesla magnets. Wrist arthroscopy is the gold standard for diagnosis of SLIL injuries, but is an invasive procedure with associated risks. Purpose To assess whether SLIL injuries can be more accurately detected using axial MRI sequences instead of coronal sequences. Material and Methods An institutional review board approved retrospective analysis of arthroscopic wrist surgeries performed at our institution. Patients that had a preoperative MRI performed at our university center using a 1.5 Tesla scanner with a dedicated wrist coil were included in the study. Three fellowship-trained musculoskeletal radiologists reviewed the axial sequences and coronal sequences independently. The accuracy of the coronal and axial sequences was compared with the arthroscopic/surgical findings. Result Twenty-six patients met the inclusion criteria. The sensitivity for SLIL tears was 79% and 65% for the axial and coronal sequences, respectively. The specificity was 82% for the axial and 69% for the coronal sequences, respectively. The positive and negative predictive values for the axial sequences were 76% and 84% respectively, compared to 68% and 71% for the coronal sequences, a statistically significant difference. Conclusion SLIL tears are more readily detectable on axial MRI sequences than coronal. Clinically, patients with radial-sided wrist pain and suspicion for SLIL tears should have the axial sequences scrutinized carefully. An otherwise normal study with the axial sequence being degraded by motion or other MRI artifacts might need repeat imaging.

The Role of Dynamic (4D) CT in the Detection of Scapholunate Ligament Injury

Background Scapholunate (SL) interosseus ligament injuries detected at an early stage could allow the surgeon to prevent progression through the spectrum of injury that leads to instability, and eventually osteoarthritis. We contend that early instability following injury can be detected by visualizing the relative motions and distances between the involved carpal bones (scaphoid and lunate) during wrist movement in vivo. The purpose of this study is to demonstrate the utility of dynamic CT (i.e., 4DCT) in diagnosing SL interosseus ligament injuries in two patients with clinical suspicion of SL interosseus ligament injury during flexion-extension (FE), radial-ulnar (RU) deviation, and dart thrower's (DT) motions. Case Description 4DCT images obtained from two individual cases were analyzed to assess the proximity between the scaphoid and lunate during wrist motion using standard image processing techniques. Proximity maps representing the distances between the scaphoid and lunate bones during each phase of wrist motion were determined. These maps provide insight into the severity of diastasis (large separation) and location of diastasis at the SL joint. The patients' proximity maps indicated dorsal diastasis and subtle uniform diastasis. Literature Review Complex musculoskeletal abnormalities, such as wrist joint instabilities, elude diagnosis during 2D fluoroscopy due to the 3D geometry of the anatomy and the inherent 3D nature of the bony kinematics. Even the most recent advances with MR arthrography lack good correlation with wrist arthroscopy. Wrist arthroscopy remains the gold standard for diagnosis to assess for intercarpal laxity. However, arthroscopy is an invasive procedure subjecting patients to the risk of infection, nerve injury, pain, and stiffness. Clinical Relevance 4DCT allows noninvasive characterization of where ligament injuries likely occur; this may allow for a more selective surgical treatment directed at the specific location of the tear.

Advanced imaging of the scapholunate ligamentous complex

The scapholunate joint is one of the most involved in wrist injuries. Its stability depends on primary and secondary stabilisers forming together the scapholunate complex. This ligamentous complex is often evaluated by wrist arthroscopy. To avoid surgery as diagnostic procedure, optimization of MR imaging parameters as use of three-dimensional (3D) sequences with very thin slices and high spatial resolution, is needed to detect lesions of the intrinsic and extrinsic ligaments of the scapholunate complex. The paper reviews the literature on imaging of radial-sided carpal ligaments with advanced computed tomographic arthrography (CTA) and magnetic resonance arthrography (MRA) to evaluate the scapholunate complex. Anatomy and pathology of the ligamentous complex are described and illustrated with CTA, MRA and corresponding arthroscopy. Sprains, mid-substance tears, avulsions and fibrous infiltrations of carpal ligaments could be identified on CTA and MRA images using 3D fat-saturated PD and 3D DESS (dual echo with steady-state precession) sequences with 0.5-mm-thick slices. Imaging signs of scapholunate complex pathology include: discontinuity, nonvisualization, changes in signal intensity, contrast extravasation (MRA), contour irregularity and waviness and periligamentous infiltration by edema, granulation tissue or fibrosis. Based on this preliminary experience, we believe that 3 T MRA using 3D sequences with 0.5-mm-thick slices and multiplanar reconstructions is capable to evaluate the scapholunate complex and could help to reduce the number of diagnostic arthroscopies.

Management of complications of ligament injuries of the wrist

Despite advances in understanding the anatomy and biomechanics of wrist motion, intrinsic carpal ligament injuries are difficult to diagnose and treat. Even when an accurate diagnosis is made, there is no consensus on the most appropriate and reliable treatment. Injury predisposes to a progressive decline in wrist function and a predictable pattern of degenerative arthritis. To prevent inadequate outcomes, many treatment options exist, all having inherent benefits and complications. This article reviews the complications of intrinsic carpal ligament injuries and complications of their treatment. Methods to prevent and principles to manage the complications are discussed.

Reproducibility of radiographic classification of scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) wrist

The aim of this study was to measure inter- and intra-observer agreement on the radiographic classification of scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) wrist. Radiographs of 41 patients with SLAC wrist and 47 patients with SNAC wrist were graded on two separate occasions by four orthopaedic consultants specializing in hand and wrist surgery. Inter-observer agreement was evaluated using the multi-rater kappa value. Landis and Koch criteria were used to assess the level of agreement. Intra-observer agreement was tested by re-grading the radiographs after an interval of 2 to 4 weeks and calculating the weighted kappa value. For SLAC wrist, the inter-observer agreement was moderate (kappa value = 0.59) and intra-observer agreement substantial (kappa value = 0.65). For SNAC wrist, the inter-observer agreement was slight (kappa value = 0.20) and intra-observer agreement was fair (kappa value = 0.29). Radiographic classification of SLAC wrist has moderate reliability and reproducibility, whereas classification of SNAC wrist has limited reliability.

Prediction of ligament length and carpal diastasis during wrist flexion-extension and after simulated scapholunate instability

PURPOSE

To determine the role of the carpal ligaments during wrist flexion-extension and to understand whether maintaining integrity of only the dorsal scapholunate ligament (SLL) is adequate for maintaining stability of the scapholunate joint.

METHODS

This study combined motion analysis and manual digitization of ligament attachment regions to generate predictions of carpal ligament length and implied strain during wrist motion and length changes after simulated ligamentous injury.

RESULTS

We modeled 13 ligaments and 22 ligament segments (subportions). We measured ligament length change with respect to wrist angle. A total of 11 segments had minimum stretch or elongation from neutral wrist position over the entire wrist range of motion for any ligament cut condition. The remaining 11 segments had more than 10% stretch in some portion of flexion-extension. In general, ligaments had increased stretch during wrist flexion and after cutting the entire SLL and the dorsal intercarpal ligaments off the scaphoid.

CONCLUSIONS

Disruption of the membranous and palmar portions of the SLL and the dorsal intercarpal ligament off the scaphoid did not result in the development of an increased 3-dimensional scapholunate gap, as measured by differences in ligament length calculations between the scaphoid and lunate. This may indicate a predynamic instability condition (before clinical signs and x-ray findings) that is stabilized by the dorsal SLL, preventing the increase in the 3-dimensional scapholunate gap. This may also support surgical treatment recommendations, which suggest that repair of the dorsal component only of the SLL will be effective. Disruption of the dorsal intercarpal ligament off the scaphoid or lunate did not result in further significant changes. Therefore, the dorsal SLL has an important role in preventing scapholunate ligament instability.

CLINICAL RELEVANCE

These results provide insight into the abnormal kinematics as various ligaments are compromised.

Arthroscopic ligamentoplasty (bone-tendon-tenodesis). A new surgical technique for scapholunate instability: preliminary cadaver study

We present an anatomical study and description of a new surgical technique for arthroscopic treatment of scapholunate ligament injuries. Five cadaver specimens were used to perform the technique. After arthroscopic surgery, anatomic dissection was performed to measure the distances to critical wrist structures such as the posterior interosseous nerve and the radial artery, and the size and position of the plasty. This arthroscopic technique offers three advantages: soft tissue damage is reduced (avoiding an extensive approach and injury to the secondary stabilizers and reducing scar tissue); injury to the posterior interosseous nerve is avoided (maintaining wrist proprioception and the role of the dynamic stabilizers); and a biotenodesis is made that ensures proper placement, tension and functionality of the flexor carpi radialis ligament reconstruction.

Comparison of radiographic stress views for scapholunate dynamic instability in a cadaver model

PURPOSE

Many different stress views for the diagnosis of scapholunate (SL) instability have been described in the literature. The purpose of this study is to compare these stress views and determine which view has the greatest utility for demonstrating SL gap radiographically.

METHODS

We performed a literature search for articles describing SL radiographic stress views. We created SL instability in 9 cadaveric wrists by ligamentous sectioning and imaged each specimen using all radiographic views found in the literature. These included the "clenched pencil" view, clenched fist views in varying positions, and traction views. Scapholunate gaps were measured using digital calipers.

RESULTS

We found 8 different SL radiographic stress views specifically described in the literature. In order to further characterize the best stress views, we studied additional parameters, including varied ulnar deviation and degree of obliquity. The clenched pencil view resulted in the most consistent views with the widest SL gaps. With clenched fist views, SL gap trended to a peak at 30° of ulnar deviation.

CONCLUSIONS

The clenched pencil view was the best stress view to demonstrate dynamic SL instability. It also allows for a contralateral comparison on 1 radiograph. We recommend this view when evaluating for SL pathology.

CLINICAL RELEVANCE

This assessment of relative diagnostic utility might assist clinicians in the creation and use of protocols for the diagnosis of dynamic SL instability.

Modified carpal stretch test as a screening test for detection of scapholunate interosseous ligament injuries associated with distal radial fractures

BACKGROUND

Intra-articular distal radial fractures are frequently accompanied by a scapholunate interosseous ligament injury, which may adversely affect the outcomes. Arthroscopy may not be appropriate as a first-line evaluation method to diagnose these injuries because of time, expense, and availability issues. The purpose of this study was to evaluate the effectiveness of the modified carpal stretch test for screening for scapholunate interosseous ligament injuries in patients with an intra-articular distal radial fracture.

METHODS

The carpal stretch test is a radiographic evaluation in which disruption of the smooth arc of the proximal carpal row joint line indicates a lack of integrity of the scapholunate interosseous ligament. We modified the original carpal stretch test and prospectively performed the modified test on forty-eight patients with a total of forty-nine unstable intra-articular distal radial fractures. With the patient under anesthesia, the injured wrist was evaluated with the modified carpal stretch test with fluoroscopy. The wrist was then examined arthroscopically to classify the scapholunate interosseous ligament injury. Three observers independently determined whether there was disruption of the proximal carpal row joint line (Gilula's arc II), used as an indicator of a grade-III or IV scapholunate interosseous ligament tear, on fluoroscopic images. The fluoroscopic results were compared with the arthroscopic findings.

RESULTS

The average sensitivity of the modified carpal stretch test was 78%, the average specificity was 72%, the average positive predictive value was 60%, the average negative predictive value was 87%, and the average accuracy was 74%. The intraclass correlation coefficient (ICC) for interobserver agreement was 0.73, and the ICCs for intraobserver agreement were 0.86, 0.68, and 0.84 for the three observers.

CONCLUSIONS

The modified carpal stretch test was useful to rule out grade-III or IV scapholunate interosseous ligament tears associated with intra-articular distal radial fractures, but it was not as useful to confirm the presence of a tear. This test may reduce the necessity for arthroscopic assessment to identify scapholunate interosseous ligament injuries following distal radial fractures and may improve the rates of detection of important carpal ligament injuries accompanying intra-articular distal radial fractures.

[Carpal instability]

Carpal instability can be understood as a disturbed anatomical alignment between bones articulating in the carpus. This disturbed balance occurs either only dynamically (with movement) under the effect of physiological force or even statically at rest. The most common cause of carpal instability is wrist trauma with rupture of the stabilizing ligaments and adaptive misalignment following fractures of the radius or carpus. Carpal collapse plays a special role in this mechanism due to non-healed fracture of the scaphoid bone. In addition degenerative inflammatory alterations, such as chondrocalcinosis or gout, more rarely aseptic bone necrosis of the lunate or scaphoid bones or misalignment due to deposition (Madelung deformity) can lead to wrist instability. Under increased pressure the misaligned joint surfaces lead to bone arrosion with secondary arthritis of the wrist. In order to arrest or slow down this irreversible process, diagnosis must occur as early as possible. Many surgical methods have been thought out to regain stability ranging from direct reconstruction of the damaged ligaments, through ligament replacement to partial stiffening of the wrist joint.

Treatment of acute scapholunate ligament injuries with bone anchor

Scapholunate instability is the most common form of carpal instability. Repair or reconstruction of the scapholunate interosseus ligament is advocated to reduce symptoms, stabilize the scapholunate joint and avoid the progression of carpal degeneration. Aim of this study is to evaluate the results (clinical and radiographic) obtained in 18 patients treated in our department for acute lesions SLIL from 2003 to 2008. Patients were 16 males and 2 females with an average age at the time of the trauma of 33.8 years old (min 17 and max 68 years). The diagnosis of scapholunate dissociation relies on a through history and physical examination and imaging studies. Early surgical repair of the torn schapolunate ligament was performed in all the patients. The method used for the treatment of these lesions was open reduction and direct ligament reinsertion through a minianchor MITEK. In our surgical experience in 3 cases we have found a combination between an isolated scaphoid fractures and a scapholunate ligament rupture without carpal dislocation. We reviewed all patients treated with an average follow-up of 32 months (range 9-68 months). The review was carried out both clinically and radiographically (static and dynamic). We achieved 13 excellent results (Mayo score average 94,77), 3 good results (Mayo score average 84), 1 sufficient results (Wrist score 72) and 1 bad result (Wrist score 35). From the radiographic evaluation we found a loss of reduction in the two cases identified clinically as sufficient and bad. One patient after an optimal ligament healing, underwent to a recurrence of the lesion SLIL 2 years from surgery. Open reduction and direct bony fixation of the torn scapholunate ligament using a suture anchor is generally successful in restoring scapholunate stability and has produced good functional mid-term results. At an average follow up of 32 months excellent or good functional outcomes were reported in 88% of the patients despite a large number of cases with a high energy trauma and other associated injury. The association between an isolated scaphoid fracture and a SLIL lesion is rare but not impossible in presence of a scapholunate instability we recommend the immediate reconstruction of the torn ligament.

Identifying scapholunate ligamentous injury

The first purpose of this study was to develop a noninvasive clinical tool that could predict whether the scapholunate interosseous ligament and other secondary stabilizing ligaments are injured in the presence of suspected scapholunate instability. The second purpose of this study was to determine which of those ligaments or ligament groups have been injured. Kinematic and three-dimensional (3D) meaurements from 62 cadaver wrists moved in a wrist joint motion simulator were used to develop various neural network predictive models. One group of models was based on angular changes in scaphoid and lunate motion before and after ligament sectioning (representing scapholunate instability). A second group of models was based on changes in the minimum distance between the scaphoid and lunate as well as other 3D gap measurements. The models, based on the scaphoid and lunate angular data, could predict with a 93% accuracy rate whether the wrist ligaments were intact. These models could also predict whether it was the dorsal ligaments or the volar ligaments that were sectioned 84% of the time. The models worked best using data with the wrist in 10 to 30 degrees of wrist flexion. The viability of a CT-based predictive model has been demonstrated by obtaining high prediction rates, sensitivity, specificity, and kappa statistic values.