Ultrasound Evaluation of the Scapholunate Ligament: Technique and Classification

Abstract

Objective

The objective of this study is to describe a systematized ultrasound evaluation technique of the scapholunate ligament (SLL) and to classify the different findings according to their severity in order to facilitate early diagnosis of this type of injuries.

Materials and Methods

We conducted a retrospective study of 13 patients evaluated in our clinics for wrist pain between February and August 2024, to whom we performed an ultrasound examination of the scapholunate ligament (SLL) and a subsequent arthroscopic study. We grouped the ultrasound images following the classification proposed by Kashiyama et al., modifying it to include new subgroups and taking into account the results of dynamic tests.

Results

Type A patients presented a normal ultrasound examination without pathology, where the SLL was visualized as a well-defined continuous hyperechoic line. Subtype B1 patients showed a preserved SLL with superficial inflammatory accumulations at the ligament and negative dynamic tests. In subtype B2 patients, the SLL was bulging and poorly defined with positive dynamic tests. 80% presented Geissler grade 2 injuries in arthroscopy. In Type C patients, it was not possible to delineate the SLL, but the opening of the scapholunate space was observed with radiocubital tilt movements and a positive Watson test was presented. 100% presented injuries, Geissler grade 3 and 4 in arthroscopy.

Conclusions

Ultrasound allows for the diagnosis of SLL injuries and their classification according to severity. Additionally, it enables dynamic studies, comparisons with the healthy contralateral wrist, and optimization of the therapeutic management of these patients.

 

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Keywords

classification - ligament - ultrasound - scapholunate

Introduction

The scapholunate ligament (SLL) is one of the most important primary stabilizers of the wrist,[1] and its injury produces an overload in the rest of the osteoligamentous structures of the carpus that results in a premature degeneration of the wrist and carpal joint if not treated correctly.[2]

Plain wrist radiography has very low sensitivity for the early diagnosis of SLL lesions.[1] It allows for the observation of secondary changes in the carpal bones, which occur in the more advanced stages of scapholunate instability.[3]

Nuclear magnetic resonance allows precise visualization of SLL lesions, but the disadvantage is its high cost and excessive waiting time in our setting, which often delays early treatment, which is so important for these lesions.[4]

For its part, ultrasound allows for dynamic studies of SLL in a non-invasive, non-ionizing, low-cost manner and with minimal waiting times.[5] [6]

Currently, there is no standardized ultrasound method for assessing SLL lesions. Published ultrasound studies only provide descriptive studies of SLL, ignoring dynamic ultrasound tests that assess SLL competence. The simplicity, ease of execution, and availability of ultrasound are the reasons why we want to present a systematic ultrasound method for assessing SLL that can be useful in routine clinical practice. The objective of this study is to describe an ultrasound technique for assessing SLL that combines SLL ultrasound images with dynamic tests. We also propose a classification of the findings according to the degree of SLL lesions in order to facilitate early treatment of these types of lesions.

 

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Materials and Methods

We conducted a retrospective study of patients clinically evaluated in the Plastic Surgery Department of the University Hospital of Burgos for wrist pain, without an associated distal radius fracture, between February 2024 and August 2024. We included all patients who met the following criteria: wrist pain, a recorded ultrasound study of the scapholunate ligament, and subsequent arthroscopic evaluation. For each patient, we recorded the age, sex, affected hand, ultrasound classification, and arthroscopic classification.

The ultrasound and arthroscopic studies were all performed by the first author of the article, a plastic surgeon specializing in hand and wrist surgery. We used ultrasound equipment with a 12 MHz linear array transducer. To study the SLL, we positioned the patient's forearm on a table, in a prone position with the wrist flexed at 45°. We use Lister's tubercle as a dorsal reference point and then move the transducer distally over the radiocarpal joint until we visualize the morphology of the scaphoid and lunate bones ([Fig. 1]). The dorsal surface of the lunate has a characteristic hump that allows it to be identified and differentiated from the scaphoid ([Fig. 2]). Once the transducer was positioned over the scapholunate interval, we tilted it as perpendicular as possible to the SLL to better visualize the hyperechoic fibrillar pattern of this ligament and avoid anisotropy. To check for dynamic scapholunate instability, we performed the Watson test with ultrasound visualization and the stress test, which consists of performing radial and ulnar tilt movements with a closed fist. If dynamic instability is present, dorsal displacement of the scaphoid can be observed with the Watson maneuver and an increase in the scapholunate space with the stress maneuver. We grouped the descriptive ultrasound images of the SLL obtained following the ultrasound classification proposed by Kashiyama et al.,[7] modifying it to include new subgroups and the results of dynamic tests:

Fig. 1 The patient's forearm rests on a table in a pronated position, with the wrist flexed at 45° and supported on a towel. Once the Lister's tubercle is identified (indicated by the black arrow), the transducer is moved distally until the scapholunate ligament is visualized. To correctly visualize its hyperechoic fibrillar pattern, the probe must be tilted until it is positioned perpendicular to the ligament.

Fig. 2 The dorsal surface of the lunate has a characteristic hump that allows it to be identified and differentiated from the scaphoid. The dorsal surface of the SLL (indicated by the red arrow) appears as a continuous, well-defined hyperechoic line between the scaphoid and lunate.

• Type A (Normal): The dorsal surface of the SLL appears as a well-defined hyperechoic continuous line between the scaphoid and the lunate. The hyperechoic transverse fibers that make up the ligament can be observed if the transducer is tilted 90° with respect to it ([Fig. 2]). The dorsal capsule and the extensor tendons of the different compartments can also be identified. Both bones are aligned. The dynamic Watson and stress tests are negative ([Video 1]).

• Type B: This group consists of a set of different ultrasound images. For ease of understanding, we have organized the images into two subtypes.

  • − Subtype B1: SLL appears well-defined with preserved fibrillar structure. ([Fig. 3]) There are hypoechoic inflammatory accumulations superficial to the ligament, representing interstitial edema. Watson's dynamic stress test and stress test are negative. ([Video 2]).

  • − Subtype B2: There is a loss of the fibrillar structure of the SLL, which appears bulging and poorly defined. In an acute episode, we also observe inflammatory changes and even partial detachment of the same ([Fig. 4]). The scaphoid is correctly aligned with the lunate at rest. The Watson test allows for the visualization of small, painful dorsal displacements of the scaphoid without any opening of the scapholunate space with dynamic stress testing ([Video 3]).

• Type C: There is a loss of the ligament's fibrillar pattern to a point where it cannot be precisely defined. Complete detachment of the SLL is also observed ([Fig. 5]). In the resting position, the scaphoid is seen displaced dorsally relative to the lunate. The ultrasound Watson test shows dorsal subluxation of the scaphoid and its posterior reduction. The dynamic stress test is positive, revealing an opening of the scapholunate space with radioulnar tilt movements. ([Video 4])

Video 1 Ultrasound evaluation of a 42-year-old patient presenting with ulnar-sided pain in the left wrist. The SLL appears normal, with no associated edema. Stress tests and the Watson maneuver are negative. Type A.

Video 2 Ultrasound evaluation of a 32-year-old professional dancer presenting with scapholunate pain after falling on her left wrist in hyperextension. Edema (indicated by arrow) is observed superficially to the ligament, which shows preserved morphology. Stress tests are negative. Subtype B1.

Video 3 Ultrasound evaluation of 35-year-old patient reporting episodes of scapholunate pain in the left wrist during bench press exercises at the gym (forced wrist hyperextension against resistance). A partial avulsion of the ligament is observed (indicated by arrow) without associated edema (chronic stage). Dorsal displacement of the scaphoid is observed with the Watson maneuver. At rest, the scaphoid is correctly positioned. Subtype B2.

Video 4 Ultrasound evaluation of a 55-year-old carpenter presenting with scapholunate pain in the right wrist after falling from scaffolding. During the dynamic stress test, scapholunate instability is observed, with widening of the scapholunate space. At rest, the scaphoid is dorsally displaced. Positive Watson test. Type C.

Fig. 3 Representative illustration of the ultrasound image obtained in patients with Subtype B1 lesion. The morphology of the SLL is preserved. There are superficial hypoechoic inflammatory accumulations over the ligament representing interstitial edema (red arrow).

Fig. 4 Representative illustration of the ultrasound image obtained in patients with Subtype B2 lesion. A partial avulsion of the SLL (indicated by the red arrow) can be seen, which may appear bulging and poorly defined.

Fig. 5 Representative illustration of the ultrasound image obtained in patients with Type C lesion. A complete detachment of the SLL is observed, with widening of the scapholunate space.

Arthroscopic evaluation was performed according to the classification proposed by Geissler[8]: grade 0 was normal; grade 1 was attenuation or hemorrhage of the scapholunate ligament seen from the radiocarpal space; grade 2 was an incongruity less than the width of the palpable hook between the scaphoid and lunate; grade 3 was an incongruity that allowed passage of the palpable hook; and grade 4 was a separation between the bones greater than the width of the hook, allowing passage of a 2.7 mm arthroscope.

Statistical data were collected in an Excel spreadsheet version 18.0 (Microsoft 365) and subsequently analyzed using SPPS version 28.0 (IBM Corp., Armonk, NY). We studied the degree of agreement observed between the ultrasound study and arthroscopy by calculating the Kappa coefficient. A P value of less than 0.05 was considered statistically significant.

 

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Results

A total of 13 patients were included. 61% were men. The wrist examined was the right one in 8 patients and the left one in 5. The mean age was 45 years (range 28–63). According to the modified Kashiyama ultrasonographic classification, there were 3 patients with type A (23%), 2 with type B1 (15%), 5 with type B2 (39%), and 3 with type C (23%). Based on the arthroscopic Geissler classification, there were 3 patients with grade 0 (23%), 2 patients with grade 1 (15.4%), 4 patients with grade 2 (30.8%), 3 patients with grade 3 (23%), and 1 patient with grade 4 (7.7%) ([Table 1]). The Kappa coefficient (95% CI) was 0.587 (0.267; 0.908) with a p-value <0.001.

Table 1 Relationship between ultrasound and arthroscopic classification. The data reflects the number of patients

		ULTRASOUND CLASSIFICATION
		A	B1	B2	C
ARTHROSCOPIC CLASSIFICATION	0	2	1
	1	1	1
	2			4
	3			1	2
	4				1

 

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Discussion

The diagnosis of SLL lesions is not standardized in clinical practice, and different clinical and radiological methods exist. Magnetic resonance imaging has a sensitivity of 90% in the diagnosis of complete SLL lesions. It has the disadvantage of not being as accurate in partial lesions, its high cost, and its excessive waiting time, which precludes early treatment of SLL lesions in the acute phase, where direct ligament repair is still possible.[9] [10]

Arthroscopy is the best diagnostic tool available, but it is still a surgical procedure. Patients are increasingly reluctant to undergo surgery for purely diagnostic purposes, which carries inherent, albeit minimal, risks, such as infection or risks associated with anesthesia.[11]

Ultrasound allows for the diagnosis of SLL lesions, the evaluation of their competence through dynamic studies, and comparisons of the injured hand with the contralateral healthy hand. Its low cost, ease of implementation, and availability are the reasons why we have described a systematic ultrasound method for assessing SLL so that it can be useful in routine clinical practice.

The main studies conducted on the sensitivity of ultrasound as a diagnostic test for SLL lesions show mixed results. Dao et al.[12] described an ultrasound sensitivity of 46.2% and a specificity of 100% in 14 patients with dynamic instability of the scapholunate ligament using 5-10 MHz transducers and comparing the results with arthroscopy. In another study, Taljanovic et al.[13] described 100% sensitivity and 92% specificity in SLL lesions using higher frequency transducers (9 to 12 MHz) and using MRI as the reference diagnostic technique. The differences obtained in the results show that the use of higher frequency transducers, typically 12 MHz or higher, increases the sensitivity of ultrasound as a diagnostic test in SLL lesions and that wrist arthroscopy remains the gold standard for the diagnosis of this type of lesion.

Comparing ultrasound studies with arthroscopic findings, Takahiro Kashiyama et al.[7] proposed the first validated ultrasound classification of SLL lesions. They grouped patients into three categories: type A, in which the sonographic appearance of the SLL is normal; type B, in which there is bulging of the SLL; and type C, in which there is loss of ligament morphology. They concluded that 87% of patients grouped in type A had Geissler grade 0-1 SLL lesions, and 78% of type C patients had Geissler grade 3-4 lesions. Group B presents more heterogeneous lesions, from normal arthroscopic examinations (29% present Geissler grade 0-1 lesions) to complete SLL lesions (71% of type B patients present Geissler grade 2-3 lesions). The lower sensitivity reported in type B patients may be due to the fact that patients with different ultrasound findings have been grouped together in the same group and that dynamic tests for assessing SLL have not been taken into account. An adaptation of this classification is of interest. Recently, Huber et al.[14] have described the use of the Watson test in the diagnosis of SLL lesions under ultrasound guidance.

In our article, we aim to more precisely describe the ultrasound findings in type B patients and classify them into two subtypes based on dynamic SLL testing. In subtype B1, the SLL is preserved, and the inflammatory changes are superficial to it. The Watson dynamic stress test and the stress test are negative. This new subtype probably corresponds to 29% of patients with Geissler grade 0-1 lesions described by Kashiyama et al. in type B. In our study, the two patients with subtype B1 lesions presented Geissler grade 0 and 1 lesions, respectively. In subtype B2, the inflammatory changes affect the SLL, and there is a loss of its fibrillar ultrasound pattern. The Watson test allows visualization of small, painful dorsal displacements of the scaphoid, with a negative dynamic stress test. This second subtype probably corresponds to 71% of patients with Geissler grade 2-3 lesions, also described by Kashiyama et al in type B. In our study, ultrasound had a sensitivity of 100% and specificity of 100% for the assumption that type B2 lesions correspond to Geissler grade 2 and 3 lesions. We consider it of interest to make this differentiation into two new subtypes since subtype B1 patients have a better prognosis and benefit from conservative treatment.

Our study has several limitations. First, the small sample size makes generalization of the findings impossible. The degree of agreement observed between ultrasound and arthroscopy is moderate, probably due to the small number of patients included in each group. Second, it should be mentioned that the Kashiyama classification has been described in cases of distal radius fractures, in which associated inflammation and hematoma could contribute to increasing the sensitivity of ultrasound.

Our ultrasound findings are consistent with other published studies.[15] [16] [17] [18] In addition to providing the B1 and B2 subclassification to the classification of Kashiyama et al, we believe that future research should take into account that in all studies only the dorsal portion of the SLL is evaluated and, although it is the most important in scapholunate stability, injuries to the volar part of the ligament can also cause pain and require treatment,[19] [20] as we have explained in [video 2]. The ultrasound technique described in this study does not detail the assessment of the volar component of SLL, as we believe its visualization is not always possible given its greater depth. It should also be noted that a single injury to the scapholunate ligament is not sufficient to produce scapholunate dysfunction, as an associated injury to the secondary stabilizing ligaments, such as the scaphotrapezial, scaphocapitate, and radiocarpal ligaments, or the dorsal intercarpal ligament, is necessary. Their involvement will determine the final degree of scapholunate dysfunction.

Finally, it should be noted that the ultrasound study of SLL is an operator-dependent technique that requires a learning curve.

This work provides a novel approach to the ultrasound study of SLL by describing a standardized ultrasound technique combining descriptive images of SLL with dynamic testing, supported by videos and illustrations of the different types of SLL lesions. We propose a modification to the Kashiyama ultrasound classification to make it more easily adaptable to the range of SLL lesions observed in daily clinical practice. We also present several clinical cases with their corresponding arthroscopic examination to facilitate understanding of the ultrasound study of SLL.

 

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Conclusion

This study describes the ultrasound technique for assessing the scapholunate ligament and classifies the findings according to the severity of the injury. In our opinion, incorporating this type of study into routine practice allows for early identification of these types of injuries and optimized therapeutic management of these patients.

 

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Conflicto de Intereses

Los autores declaran no tener ningún conflicto de interés.

• Bibliografía

• 1 Corella F, Ocampos M, Del Cerro-Gutiérrez M. Diagnóstico y tratamiento artroscópico de la inestabilidad escafolunar. Rev Esp Artrosc Cir Articul 2014; 21 (01) 51-62
• 2 Mathoulin CL, Dauphin N, Wahegaonkar AL. Arthroscopic dorsal capsuloligamentous repair in chronic scapholunate ligament tears. Hand Clin 2011; 27 (04) 563-572 , xi
• 3 Kitay A, Wolfe SW. Scapholunate instability: current concepts in diagnosis and management. J Hand Surg Am 2012; 37 (10) 2175-2196
• 4 Shahabpour M, De Maeseneer M, Pouders C. et al. MR imaging of normal extrinsic wrist ligaments using thin slices with clinical and surgical correlation. Eur J Radiol 2011; 77 (02) 196-201
• 5 Díaz HFS, Fernández FD, Horcajadas ÁB, Martínez MV, Yubero MEC. Usefulness of the Ultrasound in Hand Surgery: Part I. Rev Iberoam Cir Mano 2021; 49 (02) e128-e139
• 6 Falsetti P, Conticini E, Baldi C. et al. Ultrasound evaluation of the scapholunate ligament and scapholunate joint space in patients with wrist complaints in a rheumatologic setting. J Ultrason 2021; 21 (85) e105-e111
• 7 Kashiyama T, Miura T, Sugawara R, Uehara K. Ultrasonographic Classification of Scapholunate Interosseous Ligament Injury Associated With Distal Radius Fracture. J Hand Surg Am 2020; 45 (12) 1182.e1-1182.e5
• 8 Geissler WB, Haley T. Arthroscopic management of scapholunate instability. Atlas Hand Clin 2001; 6: 253-274
• 9 Scheck RJ, Kubitzek C, Hierner R. et al. The scapholunate interosseous ligament in MR arthrography of the wrist: correlation with non-enhanced MRI and wrist arthroscopy. Skeletal Radiol 1997; 26 (05) 263-271
• 10 De Santis S, Cozzolino R, Luchetti R, Cazzoletti L. Comparison between MRI and arthroscopy of the wrist for the assessment of posttraumatic lesions of intrinsic ligaments and the triangular fibrocartilage complex. J Wrist Surg 2021; 11 (01) 28-34
• 11 Leclercq C, Mathoulin C. Members of EWAS. Complications of wrist arthroscopy: a multicenter study based on 10107 arthroscopies. J Wrist Surg 2016; 5 (04) 320-326
• 12 Dao KD, Solomon DJ, Shin AY, Puckett ML. The efficacy of ultrasound in the evaluation of dynamic scapholunate ligamentous instability. J Bone Joint Surg Am 2004; 86 (07) 1473-1478
• 13 Taljanovic MS, Sheppard JE, Jones MD, Switlick DN, Hunter TB, Rogers LF. Sonography and sonoarthrography of the scapholunate and lunotriquetral ligaments and triangular fibrocartilage disk: initial experience and correlation with arthrography and magnetic resonance arthrography. J Ultrasound Med 2008; 27 (02) 179-191
• 14 Huber N, Götschi T, Schweizer A, Reissner L. Catch the shift: Ultrasound diagnosis of scapholunate lesion during Watson test. Hand Surg Rehabil 2024; 43 (05) 101756
• 15 Kendi ATK, Güdemez E. Sonographic evaluation of scapholunate ligament: value of tissue harmonic imaging. J Clin Ultrasound 2006; 34 (03) 109-112
• 16 Griffith JF, Chan DP, Ho PC, Zhao L, Hung LK, Metreweli C. Sonography of the normal scapholunate ligament and scapholunate joint space. J Clin Ultrasound 2001; 29 (04) 223-229
• 17 Manske MC, Huang JI. The Quantitative Anatomy of the Dorsal Scapholunate Interosseous Ligament. Hand (N Y) 2019; 14 (01) 80-85
• 18 Rodriguez RM, Ernat JJ. Ultrasonography for Dorsal-Sided Wrist Pain in a Combat Environment: Technique, Pearls, and a Case Report of Dynamic Evaluation of the Scapholunate Ligament. Mil Med 2020; 185 (1-2): e306-e311
• 19 Corella F, Del Cerro M, Ocampos M, Simon de Blas C, Larrainzar-Garijo R. Arthroscopic Scapholunate Ligament Reconstruction, Volar and Dorsal Reconstruction. Hand Clin 2017; 33 (04) 687-707
• 20 Del Piñal F. Arthroscopic volar capsuloligamentous repair. J Wrist Surg 2013; 2 (02) 126-128

Publication History

Received: 03 September 2024

Accepted: 24 March 2025

Article published online:
21 July 2025