Extrinsic and Intrinsic Ligaments of the Wrist

Carpal stability depends on the integrity of both intra-articular and intracapsular carpal ligaments. In this review, the role of the radial-sided and ulnar-sided extrinsic and intrinsic ligaments is described, as well as their advanced imaging using magnetic resonance arthrography (MRA) and contrast-enhanced magnetic resonance imaging (MRI) with three-dimensional (3D) scapholunate complex sequences and thin slices. In the last decade, the new concept of a so-called “scapholunate complex” has emerged among hand surgeons, just as the triangular ligament became known as the triangular fibrocartilage complex (TFCC).The scapholunate ligament complex comprises the intrinsic scapholunate (SL), the extrinsic palmar radiocarpal: radioscaphocapitate (RSC), long radiolunate (LRL), short radiolunate (SRL) ligaments, the extrinsic dorsal radiocarpal (DRC) ligament, the dorsal intercarpal (DIC) ligament, as well as the dorsal capsular scapholunate septum (DCSS), a more recently described anatomical structure, and the intrinsic palmar midcarpal scaphotrapeziotrapezoid (STT) ligament complex. The scapholunate (SL) ligament complex is one of the most involved in wrist injuries. Its stability depends on primary (SL ligament) and secondary (RSC, DRC, DIC, STT ligaments) stabilizers.The gold standard for carpal ligament assessment is still diagnostic arthroscopy for many hand surgeons. To avoid surgery as a diagnostic procedure, advanced MRI is needed to detect associated lesions (sprains, midsubstance tears, avulsions and chronic fibrous infiltrations) of the extrinsic, midcarpal and intrinsic wrist ligaments, which are demonstrated in this article using 3D and two-dimensional sequences with thin slices (0.4 and 2 mm thick, respectively).

Wrist and Hand

The wrist and hand have complex anatomy with small bones and supporting soft tissue structures, which limits the diagnostic yield for radiologic assessment. Knowledge of anatomy and different clinical entities is key to the radiologic diagnosis. Some of the essential anatomic and clinical topics in radiologic interpretation include knowledge of the topographic tendon anatomy of wrist and hand, the intrinsic and extrinsic carpal ligaments, the thumb ligaments, thumb carpometacarpal ligaments, the triangular fibrocartilage complex, the extensor mechanism, and the flexor tendons and pulleys. In this chapter, common traumatic injuries affecting the wrist and hand are reviewed.

Using an Office-Based, Dedicated Extremity MRI Scanner for Depicting Important Structures in Common Wrist Pathologies: A Pilot Comparison with a Conventional MRI Scanner

Background Compared with the conventional magnetic resonance imaging (MRI), dedicated MRI scanners are more accessible. Images of a dedicated 1.0-T MRI specifically developed for the hand and wrist were compared with images of a conventional 1.5-T MRI. Methods Paired images of the right wrist were randomized and separately graded by two experienced radiologists for the quality of anatomical details, including the triangular fibrocartilage complex, carpal ligaments, intercarpal cartilage, median and ulnar nerves, overall image quality, and artifacts. Interrater reliability was measured with the percentage of exact agreement and agreement within a range of ± 1 score point. Participant experience of undergoing the examination in both MRI scanners was evaluated using a questionnaire. Results The overall image quality of all sequences was considered to be moderate to high. In 25 of 38 paired images, no statistically significant difference was found between the MRI scanners. Ten scores were found to be in favor of the dedicated extremity MRI. Within a range of ± 1 score point, the extremity MRI and the conventional MRI demonstrated an interrater agreement of 67 to 100% and 70 to 100%, respectively. Among the respondents of the questionnaire, the extremity MRI scored better for participant satisfaction when compared with the conventional MRI. Conclusions In healthy volunteers, the dedicated extremity MRI generally is similar or superior to the conventional MRI in the depiction of anatomical structures of the wrists, image quality, and artifacts, and significantly scored better on participant satisfaction. Future clinical studies should focus on defining the diagnostic value of the extremity MRI in wrist pathologies.

Demystifying Palmar Midcarpal Instability

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

Results of Arthroscopically Assisted Volar and Dorsal Scapholunate Ligament Reconstruction Using Flexor Carpi Radialis: Modified Arthroscopic Corella Technique

Purpose: We evaluated results of arthroscopically assisted volar and dorsal scapholunate(SL) ligament reconstruction using flexor carpi radialis(FCR). Methods: We reviewed 31 cases who had been operated from August 2015 to June 2018. Two cases were excluded and 4 cases lost contact. Twenty five wrists were included. The average follow-up duration was 25.3months. Diagnostic arthroscopy was performed to evaluate EWAS stage of SL instability and the reparability of SL ligament. The SL reconstruction was performed for the cases which showed EWAS stage IIIC, IV having gap over 3mm and irreparable SL ligament. The interval between the diagnosis and operation was 5.9 days in average. We modified the arthroscopic Corella technique by repairing the graft tendon to FCR. Results: All SL joints were stabilized to EWAS stage I arthroscopically after reconstruction. DASH score changed from 32.7 to 9.7. Grip power changed from 74.1% to 93.3%. Modified Mayo Wrist score was 83.8. Preoperative SL angle was 53.8。, postoperative 49.6。 and the last was 51.2。. The improvement between preoperative and last follow-up SL angle was statistically significant(p<0.05). The SL angle from operation to last follow-up has increased by 1.67。(39.8%, p<0.01). Twelve cases showed SL gap over 2mm in clenched fist view before operation, but no case at follow-up. Conclusions: Volar and dorsal SL reconstruction using FCR should provide more stability and strength than only dorsal SL reconstruction. Arthroscopic technique has the merit that it causes minimal damage to extrinsic carpal ligaments and posterior interosseous nerve and can provide rapid recovery.

Avulsion of the Accessory-Carpal Ligaments and Sagittal Fracture of the Ulnar Carpal Bone in a Foal

A 45-day-old foal presented for weight bearing lameness. Radiography revealed an abnormal radiolucent line associated with the proximal ulnar carpal bone and a separate curvilinear mineral opacity palmaromedial to the distal radial epiphysis. Computed tomography illustrated a sagittal, biarticular, non-displaced fracture of the ulnar carpal bone with small separate fragments associated with the accessory-ulnar and accessory-radial carpal ligaments. The foal was treated conservatively with rest and adjunct intra-articular hyaluronic acid. The lameness resolved within 90 days. Full range of motion of the carpus returned within 120 days following an active rehabilitation protocol. This report details avulsion of the accessory-carpal ligaments and sagittal fracture of the ulnar carpal bone secondary to presumed hyperextension injury.

Bone and joint injuries of the wrist and forearm

The forearm is a complex quadrilateral structure linked by the proximal and distal radioulnar joints, ligaments, which include the interosseous membrane and triangular cartilage, and several obliquely orientated muscles. A displaced fracture or ligament rupture within this forearm is likely to involve other structures. Treatment requires anatomic recovery of stable function. The ulnar corner can sustain fractures or ligament ruptures which affect stable, pain-free, congruous forearm rotation. The distal radius may fracture after high- or low-energy trauma; anatomic reduction may not be essential in all; inaccuracy may lead to loss of rotation and ulnocarpal abutment but long-term arthritis is unusual. Children’s fractures are managed with consideration of remodeling potential. The scaphoid is vulnerable to non-union; plaster immobilization, early percutaneous fixation, and later bone-grafting all have roles. Salvage for osteoarthritic non-union may reduce pain but compromises function. Rupture of the carpal ligaments may cause substantial disruption and require complex reconstruction.

The Optimal Location to Measure Scapholunate Diastasis on Screening Radiographs

Background: Lack of a universally accepted location and normal value limits the utility of measuring scapholunate diastasis. The primary purpose of this study was to define the optimal location to measure the scapholunate gap throughout sequential ligament transections. Secondary purposes were to compare plain radiographs with fluoroscopy and to evaluate interrater reliability in measuring scapholunate diastasis. Methods: Five cadaver forearms were imaged with intact carpal ligaments and after sequentially transecting the scapholunate, radioscaphocapitate, and scaphotrapezium-trapezoid ligaments. Plain radiographs and static fluoroscopic images were obtained with wrists in neutral and 30° ulnar deviation for each stage. Multiple reviewers performed measurements of the scapholunate interval at 3 separate locations. Mean distances were calculated and pairwise comparisons between groups were made. Intraclass correlation was calculated to determine interrater reliability. Results: Overall, measurements made in the middle of the scapholunate joint had the smallest margins of error for all imaging modalities, ligament disruptions, and wrist positions. For normal wrists, the mean scapholunate measurements were all less than 2.0 mm at the middle of the joint, regardless of imaging modality or wrist position. Fluoroscopy detected significance between more stages of instability than plain radiographs at the middle of the joint. Conclusions: Measurements in the middle of the scapholunate joint in neutral and 30° of ulnar deviation under fluoroscopic imaging best capture all stages of ligamentous disruptions. Measurements less than 2.0 mm at the middle of the scapholunate interval may be considered within normal range.