Topographical Anatomy of the Distal Ulna Attachment of the Radioulnar Ligament

Qualitative and Quantitative Anatomy of the Deep Radioulnar Ligaments' Insertion on Ulna: Cadaveric, Histologic, and MRI Study

PURPOSE

To qualitatively and quantitatively analyze the anatomic features of the insertion of deep radioulnar ligaments (RULs) and provide an anatomic basis for further studies.

METHODS

The anatomic features of deep RUL insertion were observed macroscopically in 26 cadaveric wrists, after which the size of the deep RUL footprint and distance from the center of the footprint to the ulnar-sided margin of articular cartilage of the ulnar head were each measured. Five specimens were analyzed histologically to examine the attachment of the RUL on the ulna. In addition, we evaluated 21 asymptomatic wrists from healthy volunteers using 3.0 T magnetic resonance imaging.

RESULTS

The insertion of the deep RUL was located mainly on the radial aspect of the ulnar fovea from the foveal center to the articular cartilage. The footprint of the deep RUL appeared in 3 different shapes. The maximal width, length, and area of the footprint of the deep RUL were 3.7 (95% confidence interval [CI], 3.3-4.0) mm, 8.4 (95% CI, 7.9-8.9) mm, and 26.3 (95% CI, 23.4-29.1) mm2, respectively. Histologic analyses showed the attachment of the deep RUL on the radial wall of the fovea exhibited a direct insertion with typical 4-layer structures. The deep RUL fibers formed an acute angle with the distal component of the triangular fibrocartilage complex.

CONCLUSIONS

The deep RUL was inserted on the radial side of the ulnar fovea and not the foveal center; it had direct insertion on the radial wall continuous with articular cartilage, and the fibers in the direct insertion formed an acute angle with the distal component of the triangular fibrocartilage complex.

CLINICAL RELEVANCE

Understanding the quantitative anatomy of the deep RUL insertion may help guide surgeons to perform an anatomic foveal repair of the triangular fibrocartilage complex in its native footprint.

Current concepts and new trends in management of isolated triangular fibrocartilage complex injuries

The triangular fibrocartilaginous complex is made of multiple components, of which the palmar and dorsal radioulnar ligaments play an important role in distal radioulnar joint stability. The ulnar wrist ligaments may be injured during forearm and wrist trauma. There are several aspects of triangular fibrocartilaginous complex management that are still open to debate. The aim of the present study was to review the current concepts and discuss emerging trends to better elucidate and treat this important ligament complex.Level of evidence: V.

An All-Arthroscopic Technique of Repairing Foveal Tears of the Triangular Fibrocartilage Complex Using a Bone Anchor-Repair Made Simple

Traumatic foveal tears of the triangular fibrocartilage complex lead to ulnar-sided wrist pain and instability, resulting in painful motion and loss of grip strength with a severe impact on the overall function of the upper limb. Surgical repair is nothing new and has traversed through the realm of open repair to arthroscopic assisted to all arthroscopic repair techniques over the many decades, with arthroscopic repairs showing better visualization, lesser trauma, and equally favorable patient outcomes. Techniques had varied from using trans osseous tunnels to bone anchors, with or without the usage of special jigs. Here, we describe a simple and fast 3 portal arthroscopic technique of repairing the torn foveal insertion of the triangular fibrocartilage complex using a bone anchor inserted under arthroscopic and fluoroscopic guidance into the fovea. Both the dorsal and volar limbs of the triangular fibrocartilage complex are repaired arthroscopically, resulting in a strong anatomic repair resulting in a stable and pain-free wrist.

Effectiveness of suture anchor and transosseous suture technique in arthroscopic foveal repair of the triangular fibrocartilage complex: a systematic review

BACKGROUND

Currently, there were two major surgical methods for arthroscopic triangular fibrocartilage complex (TFCC) foveal repair: suture anchor (SA) and transosseous suture (TOS). The purpose of this systematic review is to examine the relevant outcome improvement and safety of SA and TOS technique.

METHODS

Literature review of electronic databases for studies investigating the effects of SA and TOS in patients undergoing arthroscopic TFCC foveal repair was performed. We compared the pre-operative and postoperative functional outcomes, clinical outcomes [pain, range of motion (ROM) and grip strength], and complications of two methods. Minimal clinically important difference (MCID) was used to determine clinically meaningful improvement.

RESULTS

There were 1263 distinct studies identified, with 26 (904 patients) meeting the inclusion criteria. The mean age of participants ranged from 21.4 to 41 years, and the mean follow-up time ranged from 6 to 106 months. Both SA and TOS groups reported significant improvement in the modified mayo wrist score, the disabilities of the arm, shoulder, and hand (DASH) score, quick DASH score, patient-reported wrist evaluation (PRWE) score, and the visual analog scale (VAS) score. According to MCID, all the studies from both groups reporting DASH, quick DASH, PRWE and VAS score achieved clinically meaningful improvement. (MCID: 10 for DASH, 14 for quick DASH, 14 for PRWE and 1.6-18 for VAS). The ROM changes in both groups varied from improvement to deterioration. Grip strength improved in both SA and TOS group. Most complications were self-limited. The reoperation rates in SA and TOS ranged from 0 to 20% and 0 to 27.3%, respectively.

CONCLUSIONS

Both SA and TOS technique for arthroscopic TFCC foveal repair could achieve improvement in postoperative functional outcomes, pain, and grip strength with low reoperation rate. However, the ROM improvement was still inconclusive.

LEVEL OF EVIDENCE IV

Systematic review of level III and IV studies.

Foveal Triangular Fibrocartilage Complex Tears: Recognition of a Combined Tear Pattern

PURPOSE

Triangular fibrocartilage complex (TFCC) injuries are categorized most commonly by the Palmer and the Atzei and Luchetti classifications. Combined tears are reported less frequently, and the classification of these tears is unclear. In this study, we present a series of patients with combined central disc and foveal TFCC tears that do not fit into either of these classifications.

METHODS

Seventeen patients from 2 institutions presented with a combined central and foveal TFCC tear, confirmed by wrist arthroscopy between September 2017 and December 2020. Patient demographics, injury mechanism, associated injuries, clinical findings, magnetic resonance imaging results, surgeon description of tears, and treatment rendered were evaluated.

RESULTS

Patients were predominantly female (76%). Mean age was 40 years with a bimodal age distribution (7/17 patients <35 and 10/17 >45 years). Eleven patients (65%) sustained the injury from a fall. All had some degree of distal radioulnar joint (DRUJ) instability on clinical examination and almost half (8/17) had a history of a distal radius or ulnar styloid fracture during the initial injury. The foveal tear was confirmed by direct visual assessment and a positive hook test result; a suction test result commonly was positive as well. All patients underwent debridement of the central tear, and 16 of 17 underwent foveal TFCC repair with 1 having an irreparable tear.

CONCLUSIONS

We present a series of patients with combined central disc and foveal TFCC tears, a pattern that does not fit current classification schemes. All patients exhibited some degree of instability of the DRUJ and almost half had a history of distal radius or ulnar styloid fracture. Identification of a central tear of the TFCC, together with even subtle DRUJ instability, should lead to consideration of a coexistent foveal tear.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.

Advances in the Repair of Palmer type IB TFCC Injuries With Wrist Arthroscopy

The triangular fibrocartilage complex (TFCC) is essential for maintaining wrist stability. Injury-caused pain is the primary cause of ulnar wrist pain. The TFCC injury refractory to conservative treatment requires further surgical treatment, and because Palmer type IB tears belong to peripheral injuries due to their proximity to the blood supply area, arthroscopic suture repair has become the preferred surgical method for TFCC injury repair, exhibiting strong healing ability. This study reviewed the anatomy of TFCC, injury classification, and advances in arthroscopic suturing for treating Palmer type IB.

Relevant landmarks to navigate the suture locations for the arthroscopic triangular fibrocartilage complex foveal reattachment

INTRODUCTION

Key step of arthroscopic triangular fibrocartilage complex (TFCC) foveal reattachment is to suture dorsal and palmar deep components of radioulnar ligaments (RULs) to the fovea of ulnar head to ensure distal radioulnar joint stability. However, the deep components are covered and cannot be identified arthroscopically from standard radiocarpal joint view. Suturing sites described in previous studies have not been proved gasping of the deep components. The purpose of this study was to investigate our TFCC suture locations using relevant landmarks on securing the RULs' deep components for arthroscopic TFCC foveal reattachment.

MATERIALS AND METHODS

Wrist arthroscopy and horizontal mattress suture was performed in 20 fresh-frozen cadaver wrists. Based on close proximity of the ulnocarpal ligaments to the palmar RUL and fovea, palmar suture location was designated at the junction between ulnolunate, ulnotriquetral ligaments and palmar border of TFCC disc, whereas dorsal suture location was at dorsal border of TFCC disc, opposite the palmar location, at same distance between prestyloid recess and palmar location. The radiocarpal and ulnocarpal joint was subsequently opened to evaluate grasping of RULs' deep components and evaluate the relevant landmarks.

RESULTS

Thirty-nine of 40 (97%) RULs' deep components were successfully grasped by the sutures. With 0.98-0.99 interobserver agreement for the measurements, mean distance between sigmoid notch to suture and suture to ulnar capsule were 5.6 ± 1.1 and 4.0 ± 0.9 mm, respectively. Whereas, the dissecting point of deep component from the superficial component of the RULs was detected immediately radial to the midpoint between the sigmoid notch and the ulnar capsule (4.5 ± 0.9 mm from sigmoid notch).

CONCLUSIONS

We determined the relevant anatomical landmarks to navigate the TFCC suture locations, which reliably secure the deep components of the radioulnar ligaments for the arthroscopic TFCC foveal reattachment.

Clinical Outcomes of Arthroscopic One-Tunnel Triangular Fibrocartilage Complex Transosseous Suture Repair Are Not Diminished in Cases of Ulnar Styloid Process Fracture Nonunion

PURPOSE

To determine whether clinical outcomes of arthroscopic one-tunnel wrist triangular fibrocartilage complex (TFCC) transosseous suture repair are not diminished in cases of ulnar styloid process fracture nonunion (USPFN).

METHODS

Patients who underwent arthroscopic 1-tunnel transosseous suture repair of Palmer 1B foveal TFCC tear (with/without superficial fiber tear; Atzei class 2 or 3 TFCC tear) from 2015 to 2020 were retrospectively reviewed. Group I was the TFCC foveal tear repair group with USPFN. Group II was the TFCC foveal tear repair group without USPFN. In group I, no additional treatment for USPFN was made. Functional preoperative and postoperative outcomes were compared by Modified Mayo Wrist Score (MMWS); Quick Disabilities of the Arm, Shoulder, and Hand (Quick-DASH) score; grip strength; pain visual analog scale (VAS); and distal radioulnar joint (DRUJ) stability. Wrist posteroanterior, lateral, and both oblique views of the wrist were used to assess the ulnar styloid process before and after operation.

RESULTS

This study consisted of 66 patients: group I (n = 22) and group II (n = 44). No differences were found between the 2 groups preoperatively in MMWS, Quick-DASH, grip strength, and VAS (MMWS: P = .94, Quick-DASH: P = .23, grip strength: P = .69, VAS: P = .45). No differences were found between the 2 groups with respect to outcome measures postoperatively in MMWS, Quick-DASH, grip strength, and VAS (MMWS: P = .59, Quick DASH: P = .82, grip strength: P = .15, VAS: P = .84). All of the enrolled patients achieved restored function with negative ballottement test and maintained DRUJ stability on follow-up. Of the 22 USPFN cases in group I, 11 (50%) showed spontaneous union after transosseous TFCC foveal repair without any additional USPFN treatment. The proportion of patients achieving a minimal clinically important difference for the Quick-DASH was similar between the 2 groups.

CONCLUSIONS

Although this current study has insufficient statistical power, the available data suggest that patients with TFCC foveal tear combined with USPFNs treated with arthroscopic transosseous repair surgery could experience similar functional improvement compared with those with TFCC foveal tear without USPFNs. The presence of USPFN accompanied by Palmer 1B type TFCC foveal tear may not affect the clinical results, including MMWS, Quick-DASH, grip strength, VAS, and DRUJ stability of patients who undergo arthroscopic 1-tunnel transosseous suture repair.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Residual stability of the distal radioulnar joint following ulnar styloid fracture: influence of the remnant distal radioulnar ligaments

Clinical studies suggest that even untreated basal ulnar styloid fractures may not affect patient outcomes. This may be due to the remaining parts of the distal radioulnar ligament still attached providing sufficient residual stability of the distal radioulnar joint. We tested this hypothesis in a biomechanical cadaveric model. Dorsopalmar translation of the distal radioulnar joint and forearm rotation were measured. Seventeen specimens were tested after a simulated ulnar styloid fracture including the fovea, followed by transection of the remaining palmar (n = 9) or dorsal (n = 8) portions of the distal radioulnar ligament and finally with all remnants transected. Rotation and translation both increased significantly after the final transection compared with the foveal fracture. The increase in translation was larger after transection of the dorsal remnants. We conclude that in an ulnar styloid fracture including the fovea, some ligament components are still attached to the ulnar head, giving residual stability to the distal radioulnar joint.

Editorial Commentary: Arthroscopic Capsular Repair of Wrist Triangular Fibrocartilage Complex Tears: Beware That Apparent Isolated Atzei Class 1 (Isolated Distal Component) Tears May Include a Proximal Component

Accumulating knowledge about the anatomy of the triangular fibrocartilage complex (TFCC) and its function has revealed that the foveal insertion of the TFCC plays a key role in distal radioulnar joint stability rather than the superficial fibers that insert into the ulnar styloid. Recently, the interest in torn peripheral TFCC repair has been shifting from capsular repair for Atzei class 1 to foveal repair for Atzei class 2 or 3. Most acute Atzei class 1 tears spontaneously heal without surgical repair; in contrast, in cases of sustained pain and distal radioulnar joint instability even after successful Atzei class 1 repair, the unrecognized proximal component TFCC tear concomitant with a distal component TFCC tear may exist and appropriate treatment for the proximal component TFCC tear should be combined. Although overall successful results have been reported using various repair techniques, the most important consideration is re-establishing biologic regeneration potential at the insertion site of torn TFCC.

Arthroscopic transosseous foveal footprint repair of the triangular fibrocartilage complex

Foveal disruption of the triangular fibrocartilage complex contributes to the instability of distal radioulnar joint. We have developed an arthroscopic transosseous foveal footprint repair technique, which maximizes the contact between the disrupted triangular fibrocartilage complex and its foveal footprint for better healing by using four sutures in a divergent configuration through a 1.6-mm bone tunnel. Twelve patients with triangular fibrocartilage complex foveal injuries who had undergone this repair technique were reviewed with a mean follow-up of 53 months. All patients achieved significant improvement in the modified Mayo wrist score and the Disabilities of the Arm, Shoulder and Hand score. All patients had stable distal radioulnar joints with comparable ranges of motion and grip strengths between the operated and contralateral wrists. There was no significant difference in functional score in those who were treated more than 6 months after injury.Level of evidence: IV.

The Triangular Fibrocartilage Complex In The Human Wrist: A Scoping Review Towards Uniform And Clinically Relevant Terminology

The aim of this scoping review was to assess the composition, terminology, and anatomy of the triangular fibrocartilage complex (TFCC) of the wrist and propose unambiguous terminology regarding the individual components. The review was conducted according to the methodological framework by Arksey and O'Malley (International Journal of Social Research Methodology, 2005, 8, 19–32). Electronic databases were searched from inception until September 1, 2021 for original anatomical studies, using MeSH terms and keywords on terminology and anatomy of TFCC components. Studies using gross dissections or macro‐ or microscopic histology were included. Animal studies, fetal studies and studies with unknown disease status, were excluded. A total of 24 studies were included. The articular disc, the radioulnar ligaments, the meniscus homologue and the extensor carpi ulnaris tendon (sub)sheath were unanimously classified as TFCC components. One study did not include the ulnolunate and ulnotriquetral ligaments and only one study did include the ligamentum subcruentum. The largest disagreement existed regarding the inclusion of the ulnar collateral ligament. Terminological ambiguity was seen in “triangular fibrocartilage,” “triangular ligament,” “igamentum subcruentum,” and the “proximal and distal lamina.” Anatomical ambiguity existed especially regarding the radioulnar ligaments, the ulnar attachments of the TFCC and the ulnar collateral ligament. Definitions of the individual TFCC components are redundant, ambiguous, and ill‐defined and therefore subject to different interpretations. In order to preclude confusion, consensus regarding terminology is recommended. We proposed a concise definition of the healthy TFCC that can be used as a starting point for future studies and current clinical practice.

Is the Fovea Ulnaris Truly Isometric during Forearm Rotation?—An In Vivo Retrospective Analysis Using Superimpositions of Three-Dimensional Reconstructions

The fovea ulnaris is considered to be the center of rotation on the ulnar head during forearm rotation. The purpose of this study was to investigate whether the fovea ulnaris is truly isometric during forearm rotation in vivo. The three-dimensional reconstruction models of 21 wrist computed tomography images taken in supination and pronation were investigated. The models were superimposed so that the two ulnar heads were in the same position. Numerous points were set on the surface of the ulnar head with a mean distance of 0.2 mm between the nearest two points. Then, the models were superimposed with respect to the radius, and the distance between the same points on the ulnar head in pronation and supination (DFR) was measured. The rotation center was defined as the point with the shortest DFR. The isometric point was defined as a rotation center with a DFR of less than 0.2 mm. An isometric point was found in three cases and not in 18 cases. The distance the rotation center moved during forearm rotation (DFR of the rotation center) ranged from 0.1 mm to 2.4 mm. The position of the rotation center in the radioulnar direction was significantly correlated with the translation of the ulnar head and the amount of forearm rotation. The rotation center was located more ulnarly when the translation of the ulnar head or the amount of forearm rotation was greater. The isometricity of the foveal insertion of the TFCC during forearm rotation may not be consistent in vivo. The center of rotation on the ulnar head during forearm rotation appears to shift ulnarly with increasing translation of the ulnar head or forearm rotation.

The rein-type arthroscopic capsular suture for triangular fibrocartilage complex foveal tears: midterm results for 90 patients

We describe an arthroscopic rein-type capsular suture that approximates the triangular fibrocartilage complex to the anatomical footprint, and report the results at a minimum 12 month follow-up. The procedure involves two 3-0 polydioxanone horizontal mattress sutures inserted 1.5 cm proximal to the 6-R and 6-U portals to obtain purchase on the dorsal and anterior radioulnar ligaments, respectively. The two sutures work as a rein to approximate the triangular fibrocartilage complex to the fovea. Ninety patients with Type IB triangular fibrocartilage complex injuries were included retrospectively. The 12-month postoperative Modified Mayo Wrist scores, Disabilities of Arm, Shoulder and Hand scores and visual analogue scale for pain showed significant improvements on preoperative values. Postoperative range of wrist motion, grip strength and ultrasound assessment of the distal radioulnar joint stability were comparable with the normal wrist. The patients had high satisfaction scores for surgery. There were minor complications of knot irritation. No revision surgery for distal radioulnar joint instability was required. It is an effective and technically simple procedure that provides a foveal footprint contact for the triangular fibrocartilage complex.Level of evidence: IV.

[Anatomical repair of Atzei-EWAS type 2 triangular fibrocartilage complex injury under wrist arthroscopy]

Objective

To explore the effectiveness of anatomical repair of Atzei-EWAS type 2 triangular fibrocartilage complex (TFCC) injury under wrist arthroscopy.

Methods

Between March 2018 and March 2020, 16 patients with Atzei-EWAS type 2 TFCC injury were admitted, and the TFCCs were anatomically repaired with a three-dimensional suture with a thread anchor under wrist arthroscopy. There were 10 males and 6 females with an average of 40.2 years (range, 22-54 years). The disease duration ranged from 2 to 9 months (mean, 6.4 months). Preoperative grip strength of the affected limb was (20.06±3.38) kg, wrist range of motion in flexion and extension was (117.19±7.74)°, radial-ulnar deviation was (31.25±5.32)°, forearm rotation range of motion was (137.19±14.83)°, visual analogue scale (VAS) score was 5.6±1.2. At last follow-up, the effectiveness was evaluated by the grip strength of the affected limb, the range of motion of the wrist joint, the VAS score, and the modified Mayo wrist score.

Results

All incisions healed by first intention. One case had paralysis of the dorsal branch of the ulnar nerve after operation, and no other complications occurred in other cases. All patients were followed up 12-18 months (mean, 14.5 months). The distal radioulnar joint stability of all patients recovered. At last follow-up, the grip strength of the affected limb was (24.88±3.26) kg, the range of motion in flexion and extension was (146.59±6.49)°, radial-ulnar deviation was (39.38±6.55)°, and forearm rotation range of motion was (152.50±11.55)°, which were significantly higher than those before operation ( P<0.05); the VAS score was 0.9±0.8, which was significantly lower than that before operation ( t=21.029, P=0.000). The modified Mayo wrist score was rated as excellent in 10 cases, good in 5 cases, and fair in 1 case. The excellent and good rate was 93.8%. MRI results showed that TFCC healed in all cases.

Conclusion

For Atzei-EWAS type 2 TFCC injury, anatomical repair under wrist arthroscopy can restore the anatomical structure of TFCC, effectively relieve wrist pain, improve function, and obtain good effectiveness.

The Critical Size of Ulnar Styloid Fragment for the DRUJ Stability

Background  Ulnar styloid fractures can be associated with clinically significant instability of the distal radioulnar joint (DRUJ). However, the exact fragment size that results in DRUJ instability is unknown. Purpose  The objective of this study was to determine the critical size of an ulnar styloid fracture that would result in a significant increase in DRUJ translation and forearm rotation. Methods  Eight cadaveric specimens were used to investigate the effects of three different ulnar styloid fracture sizes on DRUJ instability: tip fracture, base fracture, and a fracture including the fovea. Forearm rotation and dorsopalmar DRUJ translation were measured after each sequential increase in fracture size. Results  Relative to the uninjured state, a significant increase in forearm rotation and dorsopalmar translation was found for all three fractures. However, the fovea fracture showed a statistically significant increase in forearm rotation compared with all other fracture types and a statistically significant increase in total dorsopalmar translation compared with the tip fracture. Conclusion  In this study, ulnar styloid fractures involving the fovea resulted in significantly greater DRUJ instability comparted to tip and base fractures alone. This study provides important biomechanical data regarding the critical size of ulnar styloid fractures that result in DRUJ instability and may aid in the surgical decision-making algorithm in these patients.

Morphology of the Ulnar Insertion of the Triangular Fibrocartilage Complex and Related Osseous Landmarks

PURPOSE

In triangular fibrocartilage complex (TFCC) injuries, a foveal tear of the radioulnar ligament often requires surgery. Previous studies have suggested that surgeons should attach the TFCC to the center of the fovea. The TFCC and its insertion points are small structures, and few studies have reported details of the foveal insertion. This study aimed to clarify the morphology of the ulnar insertion of the TFCC and related osseous landmarks with 3-dimensional imaging.

METHODS

This study used 26 formalin-fixed cadavers. At the ulna, the TFCC was inserted from the fovea to the middle part of the ulnar styloid. After gross observation of the TFCC, the ulnar insertion was outlined using a 1.0-mm drill. We then created 3-dimensional images of the ulna using computed tomography and marked (with software) an outline of the foveal insertion of the TFCC. We measured the area and the long and short diameters of the TFCC insertion.

RESULTS

The area of the TFCC insertion was 34 mm² and positively correlated with the height of the ulnar styloid and the area of the ulnar head. The TFCC's highest point was 58% of the ulnar styloid height. The center of the TFCC insertion was 1.3 mm ulnar and 0.6 mm dorsal from the lowest point of the ulnar surface.

CONCLUSIONS

The center of the TFCC insertion was slightly ulnar of the lowest point of the ulnar surface. This study revealed the center, the area, and the osseous relation of the ulnar insertion of the TFCC.

CLINICAL RELEVANCE

When surgeons repair a TFCC foveal tear, they can find the anatomical center of the ulnar insertion efficiently and easily based on its osseous relationship.

In Vivo Mechanical Function of the Distal Radial Ulnar Ligaments During Rotation of the Wrist

PURPOSE

The purpose of this study was to investigate changes in length of the volar and dorsal radioulnar ligaments (VRULs and DRULs), and the distal radioulnar joint (DRUJ) space during unweighted and weighted rotation of the wrist using magnetic resonance imaging and biplanar fluoroscopy.

METHODS

Fourteen wrists in 7 normal adult volunteers were imaged to define the 3-dimensional geometry of the DRUJ and the insertion sites of the superficial and deep bundles of the VRULs and DRULs. Subjects were imaged at 10 positions of forearm rotation ranging from full pronation to full supination, with or without a 5-pound weight. Lengths of the superficial and deep VRUL and DRUL bundles and DRUJ space were measured (in millimeters) at each position to evaluate ligament function and DRUJ stability.

RESULTS

In the unweighted and weighted trials, maximal elongation of both deep and superficial VRUL bundles occurred in supination and maximal lengths of the deep and superficial DRUL bundles occurred in pronation. Maximum DRUJ space occurred during pronation and a minimum occurred in 30° of supination. In weighted trials, there was a significant increase in deep and superficial VRUL bundle length at positions between 30° of pronation and 30° of supination; however, there was no effect of weight on DRULs length. In weighted trials, there was a significant increase in DRUJ space at positions between full pronation and 15° of supination.

CONCLUSIONS

This study demonstrates elongation of the VRULs in supination and the DRULs in pronation. There was no evidence of reciprocal loading of superficial/deep ligament bundles on either the dorsal or the volar aspects of the DRUJ. The effect of loading the wrist during rotation was apparent primarily in the VRULs, but not the DRULs. The DRUJ space was lowest at approximately 30° of supination.

CLINICAL RELEVANCE

These results add information to the literature regarding the complicated biomechanics of the triangular fibrocartilage complex and DRUJ. Future work should evaluate changes in biomechanics caused by triangular fibrocartilage complex tears to determine how tear severity and location relate to clinical symptoms.

Ulnar footprints of the distal radioulnar ligaments: a detailed topographical study in 21 cadaveric wrists

Understanding of the exact topography of the distal radioulnar ligaments insertions remains limited. An anatomical study was performed in 21 fresh frozen cadaveric wrists, where the superficial and deep ligaments were sequentially transected sharply at their ulnar insertions. The relationships between the distal radioulnar ligament footprints relative to the bony landmarks of the ulnar styloid were digitized. Our study demonstrated that in the coronal plane, the superficial distal radioulnar ligaments inserted at an average of 87% of the styloid height proximally to the styloid tip distally. The deep distal radioulnar ligaments inserted at an average of 81% of the styloid height distally to the fovea proximally. The superficial footprint had an area of 10.6 mm² on the ulnar styloid. The deep distal radioulnar ligaments attachment was asymmetric and generally had two separate footprints. This study adds important topographical knowledge about the footprint of the distal radioulnar ligaments and may contribute to understanding the consequences of ulnar styloid fractures and distal radioulnar ligaments lesions.

Arthroscopic Ligament-specific Repair for Triangular Fibrocartilage Complex Foveal Avulsion: A Novel Technique

The deep components of the triangular fibrocartilage complex (TFCC), which consist of the volar and dorsal radioulnar ligaments (RULs), are crucial for maintaining stability of the distal radioulnar joint. Avulsion of the volar and dorsal RULs from their foveal insertions must thus be diagnosed and treated correctly. We describe our arthroscopic technique for TFCC foveal repair (arthroscopic ligament-specific transosseous repair), in which we repair each of the dorsal and volar RUL to separate points on the fovea. With this "ligament-specific" repair we wish to restore the normal anatomy and physiology of the TFCC.

Arthroscopic-assisted 6U approach for foveal reattachment of triangular fibrocartilage complex with an anchor: Clinical and radiographic outcomes at 4 years' mean follow-up

The main objective of this study was to evaluate the long-term clinical and radiological outcomes of arthroscopic-assisted foveal repair of proximal triangular fibrocartilage complex (TFCC) tears with an anchor. The secondary objective was to look for ligament damage associated with TFCC tears. Twenty-four patients who underwent foveal repair of the TFCC were evaluated retrospectively: 16 stage 2 and 8 stage 3 in the Atzei-EWAS classification. The TFCC was repaired with an anchor using an expanded 6U approach. Systematic testing of intrinsic and extrinsic ligaments was performed. The assessment criteria were pain on a visual analog scale (VAS), wrist joint range of motion, grip strength and pronation-supination strength, and the QuickDASH and PRWE outcome scores. X-rays were also taken to assess anchor position and to look for distal radioulnar (DRU) joint damage. The average follow-up was 44 months. After the surgical repair, pain was reduced (7.36±1.3 preoperatively vs. 0.69±1.3 postoperatively; P<0.001), the QuickDASH score improved (52.1±16 vs. 21.7±7; P<0.001), the PRWE score improved (83.7±35 vs. 9.3±12; P<0.001) as did strength (35 vs. 43kg; P<0.001). The DRU joint stability was also significantly improved. The time away from work was 2.6 months. During the arthroscopy exploration, 25% of patients had an ulnotriquetral ligament lesion and 8% had an ulnolunar ligament lesion in combination with their TFCC tear. Fifteen anchors were positioned in the anatomical fovea (62%). No DRU joint damage was noted. Six patients had neurapraxia of the dorsal branch of the ulnar nerve, although it recovered spontaneously. One patient still had hypoesthesia of the ulnar side of the fifth finger at 48 months. Arthroscopic-assisted foveal repair of the TFCC yields good results in terms of pain, strength and DRU joint stability. In one-quarter of cases, TFCC foveal tears are associated with lesions of the ulnotriquetral ligament. There is no long-term degeneration of the DRU joint.

What Is the Normal Ulnar Bow in Adult Patients?

BACKGROUND

Rotation of the forearm is a result of the complex interaction among the radius, ulna, and interosseous membrane. Although the radius is recognized as curved, the ulna is generally thought of as a "straight bone." To better describe normal anatomy, which may lead to more successful anatomic fixation of forearm fractures, we aimed to apply a method of measuring the normal ulnar bow and determine the mean ulnar bow in adults.

QUESTIONS/PURPOSES

(1) To what degree is the ulna bowed in the coronal and sagittal planes in normal adult forearms? (2) To what degree is the radius bowed in the coronal plane in normal adult forearms?

METHODS

Radiographs of the forearms of adults taken during a 1-year period were initially obtained retrospectively. These radiographs were performed for various reasons, including forearm pain and routine radiographic follow-up. Radiographs were excluded if evidence of a fracture or post-fracture fixation was found, if a patient had missing AP or lateral images, or if a suboptimal technique was used. The coronal and sagittal bow of the ulna was measured with a method adapted from previous studies that assessed radial bow using AP and lateral radiographs, respectively. Similar measurements were made in the coronal plane for the radius. All measurements were performed independently by the four authors. There was excellent interobserver reliability for ulnar bow in the coronal and sagittal planes (interclass correlation coefficient = 0.96 and 0.97, respectively) and for radial bow in the coronal plane (interclass correlation coefficient = 0.90).

RESULTS

The mean maximal coronal ulnar bow was 7 ± 2 mm and was located at 75% of the ulnar length, measured proximally to distally. The location of coronal bow was consistently distal to the radial bow location. The mean maximal sagittal ulnar bow was 6 ± 3 mm and was located at 39% of the ulnar length. The mean maximal coronal bow of the radius was 14 ± 2.0 mm and was 59% of the total length of the radius from proximal to distal.

CONCLUSIONS

The ulna is not a "straight bone," as is commonly thought, but rather has a bow in both the coronal and sagittal planes.

CLINICAL RELEVANCE

Knowledge of the standard ulnar bow may be pivotal to prevent malunion of the ulna during surgery. Future research using these data in preoperative planning may lead to changes in plate contouring and clinical outcomes in forearm fracture management.

Ulnar Wrist Pain Revisited: Ultrasound Diagnosis and Guided Injection for Triangular Fibrocartilage Complex Injuries

The triangular fibrocartilage complex (TFCC) serves as the major stabilizer of the wrist. Its injuries can result from trauma or degeneration, both of which are strongly correlated with the loading stress on the ulnar shaft and carpal joints. The TFCC is made of the articular disc, meniscus homologue, ulnocarpal ligament, radioulnar ligament, ulnotriquetral ligament, ulnolunate ligament, and subsheath of the extensor carpi ulnaris tendon. Because of its complexity, it is challenging to confirm the exact component affected in TFCC injuries. The Palmer classification is widely used for investigation of TFCC lesions using magnetic resonance imaging. Recently, high-resolution ultrasound (US) has become more popular in diagnosing musculoskeletal disorders. However, the utility of US imaging in TFCC lesions is less common because its anatomy under US imaging is not described in the current literature. Accordingly, in this review, we aimed to propose a standard US scanning protocol for the TFCC, present relevant images for its pathologies, and illustrate appropriate US-guided injection techniques for their management.

Arthroscopic Diagnosis of the Triangular Fibrocartilage Complex Foveal Tear: A Cadaver Assessment

PURPOSE

To determine whether the arthroscopic hook and trampoline tests are accurate and reliable diagnostic tests for foveal triangular fibrocartilage complex (TFCC) detachment.

METHODS

Wrist arthroscopy was performed on 10 cadaveric upper extremities. Arthroscopic hook and trampoline tests were performed and videos recorded (baseline). The deep foveal TFCC insertion was then sharply detached. Arthroscopic hook and trampoline tests were repeated. Subsequently, the foveal detachment was repaired via an ulnar tunnel technique and the hook test was repeated for a third time. Videos were independently reviewed at 2 time points by 2 fellowship-trained hand surgeons and 1 hand surgery fellow in a randomized and blinded fashion. Hook and trampoline tests were graded as positive or negative. Proportions of categorical variables were compared via 2-tailed Fisher exact test. Inter- and intraobserver reliabilities were assessed via Cohen kappa coefficient.

RESULTS

The sensitivity and specificity of the hook test for foveal detachment diagnosis were 90% and 90%, respectively. There was 90% agreement among all 3 observers for the baseline and foveal detachment hook tests. Cohen kappa coefficients for the inter- and intraobserver reliabilities of the hook test were 0.87 and 0.81, respectively. Seventeen percent of trampoline tests were positive at baseline versus 43% after foveal detachment. The trampoline test had 45% agreement between the 3 observers. Cohen kappa coefficients for the inter- and intraobserver reliabilities of the trampoline test were 0.16 and 0.63, respectively. Following ulnar tunnel repair, 20% of hook tests were positive.

CONCLUSIONS

The hook test is highly sensitive, specific, and reliable for the diagnosis of isolated TFCC foveal detachment. The trampoline test has insufficient reliability to assess foveal detachment. A TFCC foveal repair using an ulnar tunnel technique returns the hook test to baseline.

CLINICAL RELEVANCE

The hook test is a sensitive, specific, and reliable test for the diagnosis of isolated TFCC foveal detachment.