Modified Extensor Indicis Proprius Opponensplasty.

Extensor indicis proprius (EIP) opponensplasty is one of the commonly used techniques to restore thumb abduction and opposition in patients with thenar muscle dysfunction from various causes of median nerve palsy. However, its subcutaneous route around the distal ulna may not represent a straight line of pull, and part of the extensor hood sometimes has to be harvested along with the EIP tendon to gain adequate length to reach the insertion. The purpose of the study is to present the alternative method of EIP opponensplasty and report the clinical outcomes. The modified EIP opponensplasty was performed on 16 patients with severe carpal tunnel syndrome. At the final follow-up examination, all patients were able to regain their desired level of activities. The Kapandji score, abduction angle, and the disabilities of the arm, shoulder, and hand score improved in all patients. There were no complications related to harvesting the EIP tendon. Two patients developed finger stiffness, which improved after rehabilitation. This technique is safe and effective for restoring thumb function and can solve the insufficient tendon length problem of the original EIP opponensplasty.

Posterior Deltoid Function After Transfer of Branch to the Long Head Triceps Brachii of the Radial Nerve to the Anterior Branch of the Axillary Nerve.

PURPOSE: The aim of this study was to evaluate the function of the posterior part of the deltoid after nerve transfer of the long head triceps branch of the radial nerve to the anterior branch of the axillary nerve in patients with an upper brachial plexus injury or isolated axillary nerve injury. METHODS: We retrospectively reviewed 26 patients diagnosed with an upper brachial plexus injury or isolated axillary nerve injury who underwent nerve transfer of the long head triceps muscle branch of the radial nerve to the anterior branch of the axillary nerve in our institute between 2012 and 2017. Data on age, sex, the mechanism of injury, the pattern of injury, and operative treatment were collected from medical records. Preoperative and postoperative clinical examinations, including motor powers of shoulder abduction and extension according to Medical Research Council grading, were evaluated. At a minimum of 2 years after the operation, we evaluated the recovery of the posterior deltoid function using the swallow-tail test. RESULTS: Twenty-two patients (84.6%) had recovery of posterior deltoid function confirmed by the swallow-tail test. There were 23 patients (88.5%) who achieved at least Medical Research Council grade 4 of shoulder abduction. CONCLUSIONS: Nerve transfer from the branch to the long head triceps to the anterior branch of the axillary nerve is an effective technique for restoring deltoid function in an upper brachial plexus injury or isolated axillary nerve injury. This technique can provide shoulder abduction and shoulder extension, which are the functions of the posterior deltoid muscle. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

The Intercostal Nerves Transfer to the Radial Nerve Branch to the Long Head Triceps Muscle: Influencing Factor and Outcome of 55 Cases.

PURPOSE: The objective of this study was to report the functional outcomes and factors affecting the result of intercostal nerves transfer to the radial nerve branch to the long head triceps muscle for restoration of elbow extension in patients with total brachial plexus palsy or C5 to C7 palsy with the loss of triceps muscle function. METHODS: Fifty-five patients with total brachial plexus palsy or C5 to C7 palsy with no triceps muscle function had a reconstruction of elbow extension by transferring the third to fifth intercostal nerves to the radial nerve branch to the long head triceps muscle. The functional outcomes determined by the Medical Research Council grading were evaluated. Factors influencing the outcomes were determined using logistic regression analysis. RESULTS: At the follow-up of at least 2 years, 36 patients (65%) had antigravity motor function (Medical Research Council grade, ≥3). Multivariable logistic regression analysis showed that the body mass index, time to surgery, and injury of the dominant limb were associated with the outcome. CONCLUSIONS: The third to fifth intercostal nerves transfer to the radial nerve branch to the long head triceps muscle is an effective procedure to restore elbow extension. We would recommend using 3 intercostal nerves without grafts; in cases of nerve root avulsion in which there is no chance of spontaneous recovery, early surgery should be considered. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Dorsoradial Ligament Reconstruction in Trapeziometacarpal Joint Arthritis.

BACKGROUND: The main purpose of the study is to present the alternative novel surgical technique in treating patients with trapeziometacarpal (TMC) joint arthritis using dorsoradial ligament (DRL) reconstruction technique and report the clinical outcomes. METHODS: Patients who were diagnosed with TMC joint arthritis and underwent DRL reconstruction were evaluated. Visual analog pain score; Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score; grip, tip pinch, tripod pinch, and key pinch strengths along with range of motion of the thumb; and Kapandji score were recorded in the preoperative period and at follow-up. Stress examination was also performed under a fluoroscope. RESULTS: Eleven patients were included in the study. Median follow-up time was 13 months. At follow-up, postoperative visual analog scale and QuickDASH score improved in all patients. Grip, tip pinch, tripod pinch, and key pinch strengths also improved. The range of motion and Kapandji score were slightly improved compared with the preoperative period except for the thumb metacarpophalangeal flexion. Two patients had numbness at the thumb and spontaneously recovered after 3 months. CONCLUSIONS: According to recent evidence which proposed the importance of DRL in TMC joint stability, our DRL reconstruction technique may be an alternative treatment in treating patients presented with TMC joint arthritis. Further study with a longer follow-up period is needed.

Outcomes of Spinal Accessory Nerve and Intercostal Nerve Transfers for Shoulder Stabilisation and Elbow Extension in Patients with C5,6,7 Root Avulsion Injury.

Background: Upper arm type brachial plexus palsy results in decreased shoulder and elbow function. Reanimation of shoulder and elbow function is beneficial in these patients. The aim of this study is to report the results of restoring the shoulder abduction and elbow extension in patients with C5,6,7 root avulsion injury by simultaneous transfer of the spinal accessory nerve for the supraspinatus muscle combined with the transferring of the sixth and seventh intercostal nerves for the serratus anterior muscle along with the third to fifth intercostal nerves to the triceps muscle. Methods: All patients who underwent the above set of nerve transfers and had at least 2 years of follow-up were included in the study. The outcome measures included the Medical Research Council (MRC) grading of motor strength of shoulder abduction and elbow extension and range of motion of shoulder abduction and shoulder external rotation. Results: The study included 10 patients with an average age of 27. The mean time from injury to surgery was 6 months and the mean follow-up period was 35 months. M4 grade shoulder abduction was restored in five patients, M3 grade in three patients and M2 grade in two. M4 grade elbow extension was achieved in four patients, M3 grade in four patients and M2 grade in two patients. The average arc of shoulder abduction and external rotation was 71° and -21°, respectively. Conclusions: The spinal accessory nerve and the sixth and seventh intercostal nerves transfer to the supraspinatus muscle and serratus anterior muscle with the third to fifth intercostal nerves transfer to the triceps muscle provided satisfactory results for both shoulder abduction and elbow extension in C5,6,7 root avulsion injury. Level of Evidence: Level IV (Therapeutic).

Anatomy of Distal Articular Surface of Hamate Bone, A Cadaveric Study.

Background: Hemi-hamate arthroplasty is one of the treatment options for dorsal proximal interphalangeal joint fracture dislocation. Many studies reported favorable outcomes. However, some long term studies demonstrated the degenerative change of PIP joint. The articular mismatch of the hemi-hamate autograft might play an important role of this complication. Methods: We studied the anatomy of distal articular surface of the hamate bone in embalmed hamate bones. The anatomy of distal articular surface and dimensions of the hamate bone were measured and recorded. Results: Seventy hamate bones were dissected out from embalmed cadavers and included in this study. The mean angle of the 4th metacarpal articulation was 85.54 degrees (SD = 3.53) and mean angle of the 5th metacarpal articulation was 95.51 degrees (SD = 3.57). The inter-articular ridge was approximately 5 degrees radial inclination. Conclusions: The inter-articular ridge of distal articular surface was approximately 5 degrees radial inclination. In order to minimize the graft mismatch, we recommend making the bone cut with the saw blade tilted to radial side 5 degrees to achieve better alignment of inter-articular ridge of the graft.

Surgical anatomy of the dorsal cutaneous branch of the ulnar nerve and its clinical significance in surgery at the ulnar side of the wrist.

The dorsal cutaneous branch of the ulnar nerve can be easily injured during surgery at the ulnar side of the wrist. We sought to identify the surgical anatomy, the pathway around the ulnar styloid process and the safe zone of the dorsal cutaneous branch of the ulnar nerve. In 44 forearm dissections, we found that the dorsal cutaneous branch of the ulnar nerve originated at a median distance of 6.8 cm proximal to the tip of the ulnar styloid. We classified the crossing pattern of the dorsal cutaneous branch of the ulnar nerve at a vertical axis into three types. The most common type featured the dorsal cutaneous branch of the ulnar nerve crossing the vertical axis at a median distance of 10.0 mm distal to the tip of the ulnar styloid. In 14% of specimens, the dorsal cutaneous branch of the ulnar nerve crossed the vertical axis at the level of the tip of the ulnar styloid. By mapping the course of the nerve using a Cartesian coordinate system, it was found that the areas located proximal and palmar to the tip of the ulnar styloid had a very high density of dorsal cutaneous branches of the ulnar nerve. We were unable to establish a safe zone. We recommend identifying the dorsal cutaneous branch of the ulnar nerve in every patient undergoing surgery at the ulnar side of the wrist.

Simultaneous Phrenic and Intercostal Nerves Transfer for Elbow Flexion and Extension in Total Brachial Plexus Root Avulsion Injury.

BACKGROUND: To report the results of restoring the elbow flexion and extension in patients with total brachial root avulsion injuries by simultaneous transfer of the phrenic nerve to the nerve to the biceps and three intercostal nerves to the nerve of the long head of the triceps. METHODS: Ten patients with total brachial root avulsion injuries underwent the spinal accessory nerve transfer to the suprascapular nerve for shoulder reconstruction. Simultaneous transfer of the phrenic nerve to the nerve to the biceps via the sural nerve graft and three intercostal nerves to the nerve of the long head of the triceps was done for restoration of the elbow flexion and extension. Trunk flexion exercise program was used for all patients postoperatively. The mean follow up period was 36 months. RESULTS: For elbow flexion, there were two M4, seven M3, and one M1. For elbow extension, there were three M4, four M3, two M2, and one M1. No patient demonstrated a respiratory problem clinically postoperatively. The average FVC% decreased to 61% of the predicted value at 24 months after surgery. CONCLUSIONS: The simultaneous nerve transfer using the phrenic nerve to the nerve to the biceps and 3 intercostal nerves to the nerve of the long head of the triceps with postoperative trunk flexion exercise provide a comparable result for restoration of elbow function in total brachial plexus root avulsion injury. The patients who appear to have a respiratory problem and are unable to comply with the post-operative respiratory muscles training should be contraindicated for this simultaneous transfer.

Painful Snapping of Thumb Caused by Osteochondroma of Trapezium.

Osteochondroma is the most common benign bone tumor. Lesions occurring at the carpal bones are extremely rare. There are very few cases of osteochondroma at the trapezium had been reported in the English literature. We reported a 47-year-old patient with an osteochondroma of the left trapezium presented with painful snapping of abductor pollicis longus tendon.

Nerve Transfers to Restore Shoulder Function.

The restoration of shoulder function after brachial plexus injury represents a significant challenge facing the peripheral nerve surgeons. This is owing to a combination of the complex biomechanics of the shoulder girdle, the multitude of muscles and nerves that could be potentially injured, and a limited number of donor options. In general, nerve transfer is favored over tendon transfer, because the biomechanics of the musculotendinous units are not altered. This article summarizes the surgical techniques and clinical results of nerve transfers for restoration of shoulder function.

Polyester tape scapulopexy for chronic upper extremity brachial plexus injury.

PURPOSE: To report the results of scapular stabilization for winging in patients with chronic upper brachial plexus injury. METHODS: Eight patients, mean age 36 years, who had a winged scapula after successful restoration of major shoulder function by nerve transfer underwent scapular stabilization to the ribcage using polyester tape. The follow-up period ranged from 24 to 40 months (mean, 38 mo). Data collection included radiographic analysis, active range of motion measurement, University of California Los Angeles shoulder score, and visual analog scale pain score. RESULTS: All patients had clinical improvement with resolution of scapular winging. Five patients had no winging and 3 had mild winging after the surgery. Mean active forward flexion increased from 101° preoperatively to 127° postoperatively. Mean active shoulder abduction increased from 91° preoperatively to 121° postoperatively. Mean University of California Los Angeles shoulder score improved from 17 to 27 and mean visual analog scale pain score improved from 6.1 to 0.7. In addition, mean lateral deviated angle increased from 4° from neutral preoperatively to 9° at the last follow-up. All patients reported satisfaction with postoperative appearance. CONCLUSIONS: Outcomes of polyester tape scapulopexy in the short to intermediate term were favorable in terms of improved appearance, upper extremity function, and pain reduction in patients with winged scapula resulting from chronic upper brachial plexus injury, and with successful restoration of shoulder motion by previous nerve transfers. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Surgical anatomy of the axillary nerve branches to the deltoid muscle.

Variations in the innervation of the posterior deltoid muscle by the anterior branch of the axillary nerve have been reported. The objective of this study is to clarify the anatomy of the axillary nerve branches to the deltoid muscle. One hundred and twenty-nine arms (68 right and 61 left) from 88 embalmed cadavers (83 male and 46 female) were included in the study. The anterior and posterior branches of the axillary nerve were identified and their lengths were measured from the point of emergence from the axillary nerve to their terminations in the deltoid muscle. In all cases, the axillary nerves split into two branches (anterior and posterior) within the quadrangular space and none split within the deltoid muscle. In all specimens, the anterior and middle parts of the deltoid muscle received their nerve supplies from the anterior branch of the axillary nerve. The posterior part of the deltoid muscle was supplied only by the anterior branch of the axillary nerve in 2.3% of the specimens, from the posterior branch in 8.5%, and from both branches in 89.1%. There were two sub-branches of the anterior branch in 4.7% of the specimens. The anterior branch of the axillary nerve supplied not only the anterior and middle parts of the deltoid muscle but also the posterior part in most cases (91.5%).

Proximal ulnar stump stability after using the pronator quadratus muscle transfer combined with the Suavé-Kapandji procedure in rheumatoid wrist.

The pronator quadratus muscle transfer combined with the Sauvé-Kapandji procedure was used to treat the distal radioulnar joint disorder in ten rheumatoid wrists for prevention against instability of the proximal ulnar stump. All patients were female with a mean age of 46.6 years. The mean follow-up time was 24.2 months. Postoperatively, supination increased in all patients with a mean of 50 degrees. Pain decreased significantly and none complained of prominence of the proximal ulnar stump in normal pronated position and during a tight grip. The wrist radiographs of both coronal and sagittal planes in normal and stress fisting views were used to evaluate the postoperative static and physiologic loaded stability of the proximal ulnar stump. It had shown this procedure provided good static proximal ulnar stump stability in both coronal and sagittal planes. However, in physiologic loaded condition, it was able to provide stability only in the sagittal plane.

Surgical anatomy of the radial nerve branches to triceps muscle.

The objectives of the study are to demonstrate the innervation patterns of the triceps muscles and the most suitable branch of the radial nerve for nerve transfer to restore the motor function of the deltoid muscle in patients with complete C5-C6 root injury. Seventy-nine arms (40 left arms and 39 right arms) from 46 embalmed cadavers (24 male and 22 female) were included in the study. The nerves to the triceps were dissected from the triceps muscles (long head, lateral head, and medial head). The lengths of the branches were measured from the main trunk. The distance from the inferior margin of the teres major muscle to the origin of the nerve to the long head, lateral head, and medial head of the triceps were recorded as well. The first branch was the nerve to the long head of the triceps in 79 arms (100%). The second branch was the nerve to the upper medial head in 30 arms (38%), nerve to the medial head in 8 arms (10.1%), nerve to the upper lateral head in 35 arms (44.3%) and nerve to the lateral head in 6 arms (7.6%). The patterns of branches to the triceps were classified according to our dissections. The nerve to the long head of the triceps was constant as the first branch of the nerve to the triceps branch of the radial nerve in the vicinity of the inferior margin of the teres major muscle.

Simultaneous intercostal nerve transfers to deltoid and triceps muscle through the posterior approach.

PURPOSE: This study reports the results of restoring the deltoid and triceps functions in patients with C5, C6, and C7 root avulsion injuries by simultaneously transferring 4 intercostal nerves to the anterior axillary nerve and the nerve to the long head of the triceps through the posterior approach. METHODS: Nine patients with C5, C6, and C7 root avulsion injuries underwent spinal accessory nerve transfer to the suprascapular nerve combined with transfer of the third and fourth intercostal nerves to the anterior axillary nerve for shoulder reconstruction. Simultaneous transfer of the fifth and sixth intercostal nerves to the radial nerve branch of the triceps was done to restore elbow extension. RESULTS: For shoulder function, 8 patients had M4 recovery and 1 patient had M2 recovery. Average shoulder abduction and external rotation were 69° and 42°, respectively. For elbow extension, 3 patients achieved M3 recovery, 5 patients had M2 recovery, and 1 patient had M1 recovery. CONCLUSIONS: Reconstruction of 2 muscles with intercostal nerves is possible when both muscles act synergistically, such as shoulder abduction and elbow extension. Two intercostal nerves are adequate to transfer for deltoid reconstruction but not enough for elbow extension against gravity. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Bilateral congenital hypoplasia of the extensor tendons of the hand: a case report.

Congenital hypoplasia of the extensor tendons, which is defined as a congenital anomaly of the hand involving the extensor mechanism, is a rare condition and there are few previous reports in literature. We reported a case of bilateral congenital hypoplasia of the extensor tendons in a 12-year-old boy who presented with inability to extend his middle and ring fingers treated by the flexor carpi radialis tendon transfers.

Nerve transfer for wrist extension using nerve to flexor digitorum superficialis in cervical 5, 6, and 7 root avulsions: anatomic study and report of two cases.

PURPOSE: To evaluate the feasibility of restoring wrist extension in patients with complete cervical root 5 (C5), 6, and 7 avulsion injuries by transferring the most proximal branch of the median nerve that innervates flexor digitorum superficialis (FDS) muscle (proximal FDS branch) to the branch of the radial nerve that innervates extensor carpi radialis brevis (ECRB) muscle (ECRB branch) in an anatomic study and 2 case reports. METHODS: The study was performed on 10 fresh cadavers. The nerve branches of the median nerve and the radial nerve were measured for length, diameter, and sites of origin of their nerve branches. The nerve branches of the median nerve, the posterior interosseous nerve, and the ECRB branch of the radial nerve were processed for histomorphometric evaluation. Using image analysis software, we took all histomorphometric measurements of the nerve sections. Based on this anatomical study, the proximal FDS branch was transferred directly to the ECRB branch without nerve graft in 2 patients. RESULTS: The average distance from the origin of nerve branches to the interepicondylar line was 3.5 and 2.3 cm, respectively, for the proximal FDS and ECRB branches. The average length of the proximal FDS branch and ECRB branch was 2.8 and 3.3 cm, respectively. The average number of myelinated nerve fibers of the proximal FDS branch and ECRB branch was 983 and 2,797, respectively. At 2 years' follow-up, preliminary clinical results demonstrated that wrist extension had gained strength against resistance (grade M4). The arc of motion for wrist extension was 30 degrees in the first patient and 70 degrees in the second one. Useful functional recovery was achieved and classified as good result in both cases. CONCLUSIONS: The anatomic study and 2 reported results supports our hypothesis that transfer of the proximal FDS branch of median nerve to the ECRB branch of radial nerve could be an alternative method for reconstructiing wrist extension in C5, 6, and 7 avulsion injuries.

Nerve transfer to serratus anterior muscle using the thoracodorsal nerve for winged scapula in C5 and C6 brachial plexus root avulsions.

PURPOSE: To report the results of nerve transfer to the serratus anterior muscle using the thoracodorsal nerve for winged scapula in C5 and C6 brachial plexus avulsion. METHODS: Five patients with a mean age of 27 years with loss of shoulder abduction due to upper brachial plexus injuries and with winged scapula had nerve transfer using 1 branch (1 medial and 4 lateral) of the thoracodorsal nerve to the long thoracic nerve. The spinal accessory nerve and the nerve to the long head of the triceps were used simultaneously for nerve transfer to the suprascapular nerve and the axillary nerve, respectively. The follow-up period ranged from 24 to 33 months (mean, 28 months). RESULTS: All patients recovered serratus anterior muscle function. Two patients had no winged scapula, whereas 3 patients had mild winged scapula after the surgery at the last follow-up evaluation. The result was excellent for 2 patients, good for 2 patients, and fair for 1 patient. The mean arcs of motion of shoulder abduction and external rotation were 134 degrees and 124 degrees , respectively. No notable weakness of shoulder adduction was observed. CONCLUSIONS: Use of the branch of the thoracodorsal nerve ensured adequate return function of the serratus anterior muscle by decreasing or correcting winged scapula in upper brachial plexus injury. We recommend nerve transfer for winged scapula for achieving optimum shoulder function. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Restoration of winged scapula in upper arm type brachial plexus injury: anatomic feasibility.

BACKGROUND: The patients who have C5-C6 root avulsion in brachial plexus injury, suffered from loss of elbow flexion, shoulder abduction and winged scapula. The purpose of study is to provide anatomic feasibility of thoracodorsal nerve (medial and lateral branches) and long thoracic nerve for restoration of the shoulder function caused by winged scapula. MATERIAL AND METHOD: To study the length of thoracodorsal nerve and long thoracic nerve from the apex of the posterior axillary line to the insertion of the latissimus dorsi muscle and the serratus anterior muscle respectively, 10 fresh cadavers were dissected. The distance between the thoracodorsal nerve and long thoracic nerve, and the numbers of fascicles and axon were measured by histomorphometry. We transferred the lateral branch of the thoracodorsal nerve to the long thoracic nerve in order to restore the serratus anterior muscle function. RESULTS: The mean length of the thoracodorsal nerve from apex of posterior axillary line to bifurcation before separation to medial and lateral branches was 31.5 mm. The average length of the thoracodorsal nerve and long thoracic nerve from bifurcation to the insertion of the latissimus dorsi muscle and the serratus anterior muscle were 10.3, 82.2, and 99.5 mm, respectively. The distance between the lateral branch of the thoracodorsal nerve and long thoracic nerve was 33.4 mm. The mean number of myelinated nerve fiber of the thoracodorsal nerve medial and lateral branches and long thoracic nerve were 973.8, 1843.3 and 1135.3 axons, respectively. CONCLUSION: The anatomic study of the thoracodorsal nerve and long thoracic nerve showed that the lateral branch of the thoracodorsal nerve is proper in the length and numbers of axon to transfer to the long thoracic nerve for restoration of shoulder function caused by the winged scapula.

Nerve transfer to deltoid muscle using the intercostal nerves through the posterior approach: an anatomic study and two case reports.

PURPOSE: To evaluate the feasibility of restoring the deltoid function in patients with C5 through C7 root avulsion injuries by transferring 2 intercostal nerves to the anterior branch of the axillary nerve through a posterior approach. The preliminary results of the clinical application of this procedure also are reported. METHODS: The study was performed on 10 fresh cadavers. The lengths of the third, fourth, and fifth intercostal nerves from the costochondral junction to the midaxillary line were recorded. The distance from the pivot point at the midaxillary line to the anterior branch of the axillary nerve was recorded as the tunnel length. All histomorphometric measurements of the axon number were recorded. Based on the anatomic study, the fourth and fifth intercostal nerves were transferred directly to the anterior branch of the axillary nerve in 2 patients. RESULTS: The average distances from the costochondral junction of the third, fourth, and fifth intercostal nerves to the pivot points were 12, 15, and 16 cm, respectively. The average tunnel distances of the third, fourth, and fifth intercostal nerves were 11, 13, and 15 cm, respectively. The average numbers of myelinated nerve fibers of the third, fourth, and fifth intercostal nerves were 742, 830, and 1,353, respectively. At the 2-year follow-up evaluation the preliminary clinical results showed that the deltoid recovered against resistance (M4). The range of motion for shoulder abduction and external rotation were both 95 degrees in the first case and 105 degrees and 95 degrees , respectively, in the second case. Useful functional recovery was achieved and classified as a good result in both patients. CONCLUSIONS: This anatomic study with 2 case reports supports the idea that transfer of 2 intercostal nerves to the anterior branch of the axillary nerve through the posterior approach could be an alternative method for reconstruction of the deltoid muscle in C5 through C7 root avulsion injuries. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.