The detailed anatomy of the palmar cutaneous nerves and its clinical implications

[Distal radius fracture-tactic and approach]

OBJECTIVE

The aim of surgical treatment is fracture healing with restored alignment, rotation, and joint surface. Stable fixation allows for functional postoperative aftercare.

INDICATIONS

Displaced intra- and extra-articular fractures which either could not be adequately reduced or in which a secondary displacement is to expected due to instability criteria. The following factors are considered instability criteria: age > 60 years, female, initial dorsal displacement > 20°, dorsal comminution, radial shortening > 5 mm, palmar displacement.

CONTRAINDICATIONS

The only absolute contraindication is if the patient is deemed unfit for surgery due to concerns regarding anesthesia. Old age is a relative contraindication, as it is currently debated whether older patients benefit from the operation.

SURGICAL TECHNIQUE

The surgical technique is guided by the fracture pattern. Palmar plating is most commonly performed. If the joint surface needs to be visualized, a dorsal approach (in combination with another approach or alone) or arthroscopically assisted fixation should be chosen.

POSTOPERATIVE MANAGEMENT

In general, a functional postoperative regime can be carried out after plate fixation with mobilization without weightbearing. Short-term splinting can provide pain relief. Concomitant ligamentous injuries and fixations, which are not stable enough for functional aftercare (such as k‑wires) require a longer period of immobilization.

RESULTS

Provided the fracture is reduced correctly, osteosynthesis improves functional outcome. The complication rate ranges between 9 and 15% with the most common complication being tendon irritation/rupture and plate removal. Whether surgical treatment holds the same benefits for patients > 65 years as for younger patients is currently under debate.

The Cutaneous Branches of the Median and Ulnar Nerves in the Palm

PURPOSE

The dermatomal distributions of the ulnar and median nerves on the palmar skin of the hand have been studied thoroughly. However, the anatomic course of the median and ulnar cutaneous nerve branches and how they supply the skin of the palm is not well understood.

METHODS

The cutaneous branches of the median and ulnar nerves were dissected bilaterally in 9 fresh cadavers injected arterially with green latex.

RESULTS

We observed 3 groups of cutaneous nerve branches in the palm of the hand: a proximal row group consisting of long branches that originated proximal to the superficial palmar arch and reached the distal palm, first web space, or hypothenar region; a distal row group consisting of branches originating between the superficial palmar arch and the transverse fibers of the palmar aponeurosis (these nerves had a longitudinal trajectory and were shorter than the branches originating proximal to the palmar arch); and a metacarpophalangeal group, composed of short perpendicular branches originating on the palmar surface of the proper palmar digital nerves at the web space. The radial and ulnar borders of the hand distal to the palmar arch were innervated by short transverse branches arising from the proper digital nerves of the index and little finger. Nerve branches did not perforate the palmar aponeurosis in 16 of 18 cases.

CONCLUSIONS

The palm of the hand was consistently innervated by 20-35 mm long cutaneous branches originating proximal to the palmar arch and shorter branches originating distal to the palmar arch. These distal branches were either perpendicular or parallel to the proper palmar digital nerves.

CLINICAL RELEVANCE

Transfer of long proximal row branches may present an opportunity to restore sensibility in nerve injuries.

Anatomical considerations of US-guided carpal tunnel release in daily clinical practice

Carpal tunnel syndrome is the most frequent compression neuropathy with an incidence of one to three subjects per thousand. As specific anatomical variations might lead to unintended damage during surgical interventions, we present a review to elucidate the anatomical variability of the carpal tunnel region with important considerations for daily clinical practice: several variants of the median nerve branches in and around the transverse carpal ligament are typical and must - similarly to the variant courses of the median artery, which may be found eccentric ulnar to the median nerve - be taken into account in any interventional therapy at the carpal tunnel. Unintended interference in these structures might lead to heavy arterial bleeding and, in consequence, even underperfusion of segments of the median nerve or, if neural structures such as variant nerve branches are impaired or even cut, severe pain-syndromes with a profound impact on the quality of life. This knowledge is thus crucial for outcome- and safety-optimization of different surgical procedures at the volar aspect of the wrist and surgical therapy of the carpal tunnel syndrome e.g., US-guided carpal tunnel release, as injury might result in dysfunction and/or pain on wrist motion or direct impact in the region concerned. For most variations, anatomical and surgical descriptions vary, as official classifications are still lacking.

Density mapping of nerve endings in the skin of the palm and flexor retinaculum of the hand. Application to open carpal tunnel release

In order to re-evaluate the safest area to incise skin and the flexor retinaculum (FR) when performing a carpal tunnel release (CTR), we carried out a mapping study of the nerve endings in the skin and FR on cadaver specimens, which, unlike previous studies for the first time, includes histomorphometry and image digital analysis. After dividing the skin and FR into 20 and 12 sections, respectively, we carried out a histomorphological analysis of nerve endings. The analysis was performed by two neutral observers on 4-μm histological sections stained with hematoxylin-eosin (H-E), and Klüver-Barrera with picrosirius red (KB + PR) methods. A semi-automatic image digital analysis was also used to estimate the percentage of area occupied per nerve. We observed a lower quantity of nerve endings in the skin of the palm of the hand in line with the ulnar aspect of the 4th finger. The ulnar aspect of the FR was the most densely innervated. However, there are no statistically significant differences between sections in the percentage of area occupied per nerve both in the skin and in the FR. We concluded that there is not a safe area to incise when performing carpal tunnel surgery, but taking into account the quantity of nerve endings present in skin and FR, we recommend an incision on the axis of the ulnar aspect of 4th finger when incising skin and on the middle third of the FR for CTR.

[Differential therapeutic Approaches in Treatment of Carpal Tunnel Syndrome]

Carpal tunnel syndrome (CTS) is one of the most common compression neuropathies. The therapeutic concept should be tailored to each patient individually, with initial non-surgical treatment being the standard of care for early CTS. Primary surgical intervention should be considered in more advanced diseases stages, in case of concomitant pathologies (including space-occupying lesions, complex regional pain syndrome or diabetic neuropathy), if non-surgical strategies have failed or in pregnancy-related CTS. This work aims to discuss common surgical approaches, their clinical application as well as benefits and disadvantages in a pragmatic style. Further, we highlight surgical strategies to address recurrent CTS following failed primary surgery. In view of the recently updated S3 guidelines "Diagnosis and Therapy of Carpal Tunnel Syndrome", this topic is timely and relevant for hand and nerve surgeons.

Preservation of terminal branches of the palmar cutaneous branch of the median nerve in open carpal tunnel release

PURPOSE

Post-operative pain in the palm and scar area is the most common complication after carpal tunnel release and injury to the terminal branches of the palmar cutaneous nerve is generally considered one of the causes for this complication. The Authors performed an intraoperative study preserving the terminal branches of the palmar cutaneous branch of the median nerve and verifying the frequency, location and direction of the branches that cross an interthenar incision.

METHOD AND MATERIAL

Eighty-five consecutive patients (57 F - 28 M, mean age 66 y) underwent carpal tunnel release between February and June 2021. The cutaneous branches crossing the incision were identified and preserved by careful dissection. Subsequently they were counted and classified by their direction and distance from the proximal border of the transverse carpal ligament.

RESULTS

Sensory branches were found in 40 % of cases (34/85) and their origin was observed at an average of 1.05 cm (0-1.8 cm) distal from the proximal border of the carpal tunnel. A total of 44 branches were observed of which 23 branches crossed the incision with a transverse course and 21 with an oblique, generally proximal-distal radio-ulnar course. The subcutaneous layer overlying the distal third of the transverse carpal ligament was found to be devoid of sensory branches, therefore it can be considered a relatively safe area.

CONCLUSION

Isolation and protection of palmar sensory branches is important for improving carpal tunnel release results. This goal can be more easily achieved by locating the skin incision on the distal third of the transverse carpal ligament, where the sensory branches have a lower frequency, possibly associated with a second proximal incision (biportal technique) to better visualize the proximal portion of the ligament and antebrachial fascia.

Comparison of the Therapeutic Effect of the Mini-Open Incision and Conventional Open Neurolysis of the Median Nerve for Carpal Tunnel Syndrome

OBJECTIVE

The aim of this study was to compare the therapeutic effects of the mini-open incision and conventional open surgery for carpal tunnel syndrome (CTS).

METHODS

The clinical data of 52 patients with CTS treated at the First Affiliated Hospital of the University of Science and Technology of China from October 2020 to February 2022 were retrospectively analyzed. The patients were divided into the conventional open surgery group (28 cases) and the mini-open incision group (24 cases) according to different surgical incisions applied. The incision length, operation time, time until postoperative return to work, and complications were observed in the two groups. The Visual Analog Scale (VAS) for pain at one day, one month, and three months after surgery and the Boston Carpal Tunnel Questionnaire scores before, at one month, and at three months after surgery were compared between the two groups.

RESULTS

The incision length, operation time, and time until return to work in the mini-open incision group were all shorter than those in the conventional open surgery group (2.58 ± 0.35 vs. 7.32 ± 0.61 cm, 18.67 ± 2.62 vs. 29.46 ± 3.42 min, and 5.33 ± 1.40 vs. 13.86 ± 2.70 d, respectively), and differences were statistically significant (P < 0.05 in all). The VAS scores in the mini-open incision group were lower than those in the conventional open surgery group at one day and one month after surgery, while the difference in the VAS scores at three months after surgery was not statistically significant between the two groups. There was no statistically significant difference in neurological recovery between the two groups at postoperative follow-ups (P > 0.05). The incidences of postoperative scar hyperplasia and scar pain were higher in the conventional open surgery group than those in the mini-open incision group, and differences were statistically significant (P < 0.05 in both).

CONCLUSION

Mini-open incision surgery for CTS was a safe and reliable procedure with a precise therapeutic effect, minimal surgical trauma, and high postoperative comfort for patients and could achieve enhanced recovery. Trial Registration. This trial is registered with ChiCTR2200064631.

Modified Carpal Tunnel Release: A New Approach to Minimizing Pillar Pain

INTRODUCTION

Pillar pain is a frequent postoperative complication of carpal tunnel release (CTR). The precise definition of pillar pain is lacking, but most authors describe it as diffuse aching pain and tenderness in the thenar and hypothenar area. The etiology of pillar pain is unclear. However, the most prevalent theory is the neurogenic theory, which attributes the pain to the damage of small nerve branches of palmar cutaneous branches of median nerve after surgical incision, with resulting entrapment of the nerves in the scar tissue at the incision site. We postulated that a main source of pillar pain is sensory neuromas along the incision site.In this article, we describe a simple modification of the standard CTR technique with intent to decrease neuroma formation and thus minimizing pillar pain.

MATERIALS AND METHODS

This is a retrospective study comparing the incidence and duration of pillar pain between patients who underwent standard CTR (SCTR, n = 53) versus the minimizing pillar pain CTR technique (n = 55). Based on duration of pillar pain, the groups were placed into 3 subgroups (<3, 3-6, and >6 months). Presence and duration of pillar pain in each group were recorded along with return to work (RTW), complications, and patient satisfaction.

RESULTS

The SCTR group had a total of 17 patients with pillar pain (32.1%), 5 of which resolved within 3 months, 7 within 3 to 6 months, and 5 in more than 6 months. The group that underwent the minimizing pillar pain technique had a total of 4 patients with pillar pain (7.2%). Three resolved within 3 months, 1 resolved within 3 to 6 months, and there were no patients with pillar pain lasting more than 6 months. Average RTW time for minimization of pillar pain CTR (MPPCTR) was 34.9 days. Average RTW time for SCTR was 54.8 days. Satisfaction was higher among patients who underwent surgery with MPPCTR.

CONCLUSIONS

Based on these results, we concluded that MPPCTR compared with SCTR had equal complication rate, however, significantly lower incidence and duration of pillar pain, higher rate of satisfaction, and earlier RTW.

Innervation of the wrist joint: Literature review and clinical implications

The aim of this study was to review the literature on the innervation of the wrist with an emphasis on pathological and therapeutic aspects. The nerves involved in wrist innervation and their mechanoreceptor endings are described. The literature over the past 30 years includes several topics that are still subjects of discussion and debate and require further research.

Anomalous Courses of the Palmar Cutaneous Branch of the Median Nerve in Relation to the Flexor Carpi Radialis Tendon for ORIF of Distal Radius Fractures

Background: The purpose of this study was to prospectively document the incidence of variations in the course of palmar cutaneous branch of the median nerve (PCBMN) that may increase the risk of injury to the nerve during the flexor carpi radialis (FCR) approach. We hypothesize that the incidence of anomalous branching of the PCBMN around the FCR sheath will be approximately 5%. Methods: All cases that met inclusion criteria between November 2013 and March 2018 were included. The operating surgeon made the final decision for operative intervention using the FCR approach. Each surgeon performed the standard FCR approach to the distal radius. The branching location from the median nerve, the relationship to the FCR sheath, and the course of the PCBMN were recorded. Results: In total, 101 distal radius fractures were included. The average branching point of PCBMN was 5.2 cm from the distal wrist crease (range = 3.3-9.0). There were 26 anomalous branching patterns of PCBMN. Nineteen (18.8%) crossed volar, dorsal, or ran within the FCR sheath. Six PCBMN were found within the FCR sheath, 1 penetrated the FCR sheath, 6 crossed volar to the FCR sheath, and 6 were dorsal to the FCR tendon sheath. When comparing the branching patterns of the PCBMN from the median nerve, 4 branched from the volar aspect, 2 branched from the dorsal aspect, and 1 branched from the ulnar aspect of the median nerve. Conclusions: Variation in the course of the PCBMN relative to the FCR sheath is more than previously thought and can be expected in approximately 18.8% of patients.

Anatomy of the palmar cutaneous branch of the median nerve: A review

The palmar cutaneous branch of the median nerve (PCBm) supplies afferent innervation to the volar aspect of the hand. It consistently originates from the radial side of the median nerve, travels in relation to the tendons of the palmaris longus and flexor carpi radialis muscles, and courses superficially through fascial planes to reach the surface of the palm. Because it is at risk of injury in numerous operations, this review serves to provide a summary of anatomical findings regarding the PCBm across various studies to aid orthopedists and other clinicians in anticipating the location of the nerve during surgical procedures.

Ultrasound determination of presence, length and diameter of the palmaris longus tendon

Inadvertent median nerve harvest is a devastating complication of palmaris longus harvest. Accurate assessment of palmaris longus presence and dimensions preoperatively would minimize this risk and assure safe harvest. We hypothesized that ultrasound would accurately predict palmaris longus presence, length and diameter. Seventeen cadaveric forearms were studied using a LOGIQ-E9 ultrasound. Two radiologists assessed palmaris longus presence and dimensions. Each wrist was explored, and the tendon was harvested and measured. Inter-rater reliability and agreement between measurements was assessed. The palmaris longus was present in 13 of 17 forearms. Both radiologists correctly identified the tendon and its absence (sensitivity and specificity, 100%). Ultrasound assessment of palmaris longus dimensions significantly correlated with surgical measurements. Intraclass correlation coefficient between radiologists was 0.97. We conclude that ultrasound can determine palmaris longus presence and dimensions with excellent accuracy and inter-observer reliability. Ultrasound is useful for preoperative evaluation of the palmaris longus and its use will increase patient safety.

A review of main anatomical and sonographic features of subcutaneous nerve injuries related to orthopedic surgery

Lesion to subcutaneous nerves is a well-known risk of orthopedic surgery and a significant cause of postoperative pain and dissatisfaction in patients. High-resolution ultrasound can be used to visualize the vast majority of small subcutaneous nerves of the upper and lower limbs. Ultrasound detects nerve abnormalities such as focal hypoechoic thickening, stump neuroma, and scar encasement, and provides information not only about the peripheral nerve itself but also about its relationship to adjacent anatomical structures. The purpose of this review is to provide an overview of the anatomy of the main subcutaneous nerves damaged during orthopedic surgery, recall at-risk procedures, and offer useful anatomic landmarks to help the sonographer identify and follow the nerves when an iatrogenic lesion is suspected.

The Palmar Cutaneous Branch Mimicking the Recurrent Motor Branch of the Median Nerve

We report an unusual anatomical variant of the palmar cutaneous branch (PCB) of the median nerve in a 46-year-old man presenting with recurrent carpal tunnel syndrome. At surgery, after neurolysis, the PCB was visualized arising at the level of the proximal margin of the transverse carpal ligament, mimicking the appearance of the recurrent motor branch. To date, there has been no description of this branch arising at this level. We aim to remind surgeons of this variation and highlight the importance of maintaining vigilance to avoid iatrogenic nerve injury.

Iatrogenic Injuries of the Palmar Branch of the Median Nerve Following Volar Plate Fixation of the Distal Radius

Background: Our aims were to identify iatrogenous injuries to the palmar branch of the median nerve sustained during volar plate fixation of the distal radius, make the clinician aware of this relatively uncommon complication of distal radius fixation, to emphasise common threads in symptomatology and to propose an algorithm for evaluation and management.

Methods: Retrospectively interrogating our database over a 5 year period, the case records, neurophysiology records, operative records, therapy records were reviewed. The data was analysed with regard to the grade of surgeon performing the procedure, the site of injury, complexity of the fracture, delay to surgery, implant choice and outcome of the treatment. Variations in nerve anatomy were documented during revision surgery and common themes in symptomatology and clinical presentation were identified.

Results: Seven patients with an iatrogenic injury involving the palmar branch of the median nerve associated with volar plate fixation of the distal radius were assessed. The male: female ratio was 1:6 and the mean age of patients was 47.8 years (33-74 years). The initial operative fixation was undertaken by a consultant orthopaedic surgeon at a mean of 7.8 (1-17) days from injury. The mean time from fracture fixation surgery to referral to the peripheral nerve injury service was 8.9 (2-36) months. Six patients presented with pain on attempted wrist extension. Five patients had parasthesia, hyperaesthesia or dysaesthesia in the distribution of the PCBMN. Anaesthesia or hypoaesthesia was present in three patients. Two patients presented with symptoms of complex regional pain syndrome (CRPS) Type 2.

Conclusions: Revising relevant anatomy and possible variations as well as careful placements of retractors in the region of the median nerve could bring down these injuries. We propose an algorithm for their management.

A comprehensive review of motor innervation of the hand: variations and clinical significance

PURPOSE

The objective of the present review is to assemble the recognized anatomical variations, classifications, and clinical evidence with regard to innervation of the hand and discuss the clinical significance of these variations.

METHODS

The material for this review was obtained by exploring PubMed and Google Scholar (search terms: hand innervation, variations of ulnar nerve, variations of median nerve, variations of radial nerve) as well as from standard anatomy texts. This initial search returned approximately 300 articles, which was reduced by abstract or title review. Reviewing the reference lists of significant papers uncovered further studies missed in the initial search. A few standard anatomy texts were also consulted for normal anatomy.

RESULTS

The median and ulnar nerves frequently display a number of significant deviations from the traditionally taught branching patterns. The traditionally taught innervation of the hand is also found to be highly variable. This is especially evident with regard to the motor innervation of thenar muscles. These variations may be explained by the often under-recognized anastomoses that exist in the hand, such as the motor Riche-Cannieu Anastomosis. Some of these variations are associated significant clinical consequences.

CONCLUSIONS

The median and ulnar nerves display many anatomical variations, often with significant clinical implications. Awareness about these variations is clinically important when interpreting clinical examination findings, electrophysiological and radiological investigation as well as during management of patients in terms of surgical and anesthetic procedures.

A comparison of minimally invasive approach vs conventional approach for volar plating of distal radial fractures

Background

The aim of this study was to introduce and to evaluate the functional results of volar plating of distal radial fractures through a longitudinal minimally invasive approach.

Methods

From January 2010 to January 2013, 157 patients with distal radial fractures were randomly allocated to group A (n = 83; 49 men, 34 women; mean age: 42 (18–67)) and B (n = 74; 46 men, 28 women; mean age: 41 (22–65)), including type A2, A3, B3, C1, and C2 fractures, based on AO Foundation and Orthopaedic Trauma Association Classification. Patients in group A were treated through a 1.5- to 2-cm longitudinal incision, and patients in group B were treated through the conventional flexor carpi radialis approach. All fractures were treated with a locking volar plate. The functional results were compared with range of motion, grip and pronation strengths for each fracture type.

Results

After a follow-up of 2 years, similar measurements were noted on range of motion and grip strength in both groups. Regarding pronation strength, group A was superior to group B (p < 0.05).

Conclusions

Minimally invasive volar plating of distal radial fractures is a safe and reliable technique, resulting in better pronation function and appearance.

Level of Evidence

Level I, Therapeutic study

Anatomic considerations when performing the modified Henry approach for exposure of distal radius fractures

BACKGROUND

Identify the proximity of anatomic structures during the modified Henry approach (MHA).

METHODS

Distances between median nerve (MN), palmar cutaneous branch (PCB), radial artery (RA) and the flexor carpi radialis (FCR) were measured at the wrist crease (WC), 5 and 10 cm proximal in 16 fresh frozen cadavers. The FPL origin and innervation was measured.

RESULTS

Most at risk was the MN proximally and the PCB distally while the RA was safe. Innervation occurred at the proximal third of the FPL's origin along the ulnar aspect.

CONCLUSION

The MHA is safe when understanding the proximity of structures.

Incidence of an Anomalous Course of the Palmar Cutaneous Branch of the Median Nerve During Volar Plate Fixation of Distal Radius Fractures

PURPOSE

Volar plating of distal radius fractures using an approach through the flexor carpi radialis (FCR) sheath is commonplace. The palmar cutaneous branch of the median nerve (PCB) is considered to run in a position adjacent to, but outside, the ulnar FCR sheath. Anatomic studies have not identified anatomic abnormalities relevant to volar plating. The purpose of this study was to determine the frequency of anomalous PCB branches entering the FCR sheath during volar plating.

METHODS

This observational study involved 10 attending hand surgeons during a 7-month period (July 2015-January 2016). Surgeons assessed, documented, and reported any PCB anomalies that were encountered during volar plating through a trans-FCR approach.

RESULTS

There were 182 volar plates applied that made up the study group. There were 10 cases (5.5%) of anomalous PCBs entering the FCR sheath. In 4 cases, the PCB pierced the radial FCR sheath proximally, crossed beneath the tendon, and traveled distally on the ulnar side. In 4 other cases, the PCB entered the FCR sheath proximally on the ulnar or central aspect of the sheath and remained within the sheath, staying along the ulnar or dorsal side of the tendon. In 1 case, the PCB pierced the ulnar distal aspect of the sheath and split into 2 branches. In 1 case, the PCB ran within the sheath along the radial aspect of the FCR.

CONCLUSIONS

Anomalies in the course of the PCB are more common than often considered. These variants are at risk during volar surgical approaches to the wrist that proceed through the FCR sheath.

CLINICAL RELEVANCE

Although dissecting along the radial side of the FCR sheath may protect the PCB in most cases, care must be taken to identify anomalous branches (if present) and protect them during surgery.

Selection of tendon grafts for distal radioulnar ligament reconstruction and report of a modified technique

PURPOSE

To investigate the graft length necessary to complete a distal radioulnar ligament reconstruction and assess the suitability of several tendon graft sources.

METHODS

We measured the graft length needed to complete the distal radioulnar ligament reconstruction in 7 fresh-frozen cadaver specimens. The pure tendon lengths of 7 tendon graft sources were measured: palmaris longus, extensor indicis proprius, slips of extensor digiti minimi and abductor pollicis longus, and portions of flexor carpi ulnaris, flexor carpi radialis, and extensor carpi ulnaris. A modified technique that allows for a shorter length of graft is also described, and the suitability of each graft source for this technique was assessed.

RESULTS

The mean graft lengths needed to complete the original and modified reconstructions were 138 mm and 89 mm, respectively. The average length of the tendon graft when measured as pure tendon was: palmaris longus (127 mm), slip of extensor digiti minimi (112 mm), extensor indicis proprius (100 mm), partial flexor carpi radialis (87 mm), slip of abductor pollicis longus (69 mm), partial flexor carpi ulnaris (67 mm), and partial extensor carpi ulnaris (67 mm). The palmaris longus was too short for the original technique in the majority of specimens but was sufficient to complete the modified technique in every specimen that had a palmaris longus. Six specimens also had an extensor indicis proprius of suitable length for the modified technique.

CONCLUSIONS

The length of donor graft required for the modified reconstruction was significantly less than that needed for the original reconstruction. Three specimens had no donor tendons sufficiently long to complete the original technique if a pure tendon graft were used, whereas the modified technique could be completed in all specimens.

CLINICAL RELEVANCE

Many tendon graft sources in the upper extremity are of insufficient length to complete the distal radioulnar ligament reconstruction as described. A modified technique using suture anchors may be a useful alternative in such cases.

Volar wrist ganglion excision through the flexor carpi radialis sheath

Volar wrist ganglions are much less frequent than their dorsal counterparts but provide much more surgical trepidation due to their proximity to the radial artery. With the majority arising from the radiocarpal joint, we have found that entering the flexor carpi radialis sheath and accessing the ganglion through the floor of the sheath allows for a relatively safe excision of these benign hand tumors.

The cadaveric anatomy of the distal radius: implications for the use of volar plates

INTRODUCTION

Fractures of the distal radius are common upper limb injuries, representing a substantial proportion of the trauma workload in orthopaedic units. With ever increasing advancements in implant technology, operative intervention is becoming more frequent. As growing numbers of surgeons are performing operative fixation of distal radial fractures, an accurate understanding of the relevant surgical anatomy is paramount. The flexor carpi radialis (FCR) tendon forms the cornerstone of the Henry approach to the volar cortex of the distal radius. A number of key neurovascular structures around the wrist are potentially at risk during this approach, especially when the FCR is mobilised and placed under retractors.

METHODS

In order to clarify the safe margins of the FCR approach, ten fresh frozen human cadaver limbs were dissected. The location of the radial artery, the median nerve, the palmar cutaneous branch of the median nerve and the superficial branch nerve were measured with respect to the FCR tendon. Measurements were taken on a centre-to-centre basis in the coronal plane at the watershed level. In addition, the distances between the tendons of brachioradialis, abductor pollicis longus and flexor pollicis longus, and the radial artery and median nerve were measured to create a complete picture of the anatomy of the FCR approach to the distal radius.

RESULTS

The structure most at risk was the palmar cutaneous branch of the median nerve. It was located on average 3.4mm from the FCR tendon. The radial artery and the main trunk of the median nerve were located 7.8mm and 8.9mm from the tendon. The superficial branch of the radial nerve was 24.4mm from the FCR tendon and 11.1mm from the brachioradialis tendon.

CONCLUSIONS

Operative intervention is not without complication. We believe a more accurate understanding of the surgical anatomy is key to the prevention of neurovascular damage arising from the surgical management of distal radial fractures.

Surgical exposures of the radius and ulna

The forearm contains many muscles, nerves, and vascular structures that change position on forearm rotation. Exposure of the radial shaft is best achieved with the Henry (volar) or Thompson (dorsal) approach. The volar flexor carpi radialis approaches are used increasingly for exposure of the distal radius. Although the dorsal approach is a safe utilitarian option with many applications, its use for managing fracture of the distal radius has waned. Potential complications associated with radial exposure include injury to the superficial branch of the radial nerve, the lateral antebrachial cutaneous nerve, and the cephalic vein. Dorsal and ulnar proximal radial exposures are associated with increased risk of injury to the posterior interosseous nerve. With surgical exposure of the ulna, care is required to avoid injuring the dorsal cutaneous branch of the ulnar nerve.

Definition of a safe-zone in open carpal tunnel surgery: a cadaver study

Carpal tunnel decompression is one of the most common surgical procedures in hand surgery. Cutaneous innervation of the palm by median and ulnar nerves was evaluated to find a suitable incision preserving cutaneous nerves. A morphometric study was designed to define the safe-zone for mini-open carpal tunnel release. Sixteen fresh-frozen (8 right, 8 left) and 14 formalin-fixed (8 right, 6 left) cadaveric hands were dissected. Anatomy of the palmar cutaneous branch of the median and the ulnar nerve, motor branch of the median nerve, superficial palmar arch were evaluated relative to the surgical incision. We also identified the motor branch of the median nerve. Detailed measurements of the whole palmar region are reported in this study. The motor branch of the median nerve was extraligamentous as 60%, subligamentous as 34%, transligamentous as 6%. The palmar cutaneous branches of the median and the ulnar nerves in the palmar region were classified as Type A (34%), Type B (13%), Type C (13%), Type D (none), Type E (40%) according to forms of palmar cutaneous innervation originating from the ulnar and median nerves. Injury to the palmar cutaneous branch of the median nerve (PCBMN) is the most common complication of the carpal tunnel surgery. Various techniques were described to decrease post-operative morbidity. Based on these anatomic findings mini incision between the superficial palmar arch and the most distal part of the PCBMN in the palmar region is the safe-zone for carpal tunnel surgery.

Sonographically guided carpal tunnel injections: the ulnar approach

OBJECTIVE

The purpose of this report is to describe a new sonographically guided technique for carpal tunnel injections using an ulnar approach.

METHODS

Previously published sonographically guided techniques for carpal tunnel injections were reviewed. Described approaches were noted to be technically challenging because of the need to perform long-axis imaging of the carpal tunnel, short-axis (out-of-plane) imaging of the needle, or both.

RESULTS

We developed and herein describe the ulnar approach for sonographically guided carpal tunnel injections. Advantages of this approach include transverse imaging of the carpal tunnel, long-axis (in-plane) imaging of the needle, and versatility in targeting structures within the carpal tunnel.

CONCLUSIONS

Clinicians should consider the ulnar-sided approach when performing sonographically guided carpal tunnel injections.

Anomalous palmar cutaneous branch of the median nerve in the distal forearm: case report

Variations exist in the anatomy of the palmar cutaneous branch of the median nerve about the wrist. We report an anatomic variation in the course of the palmar cutaneous branch of the median nerve identified in a 17-year-old girl undergoing surgery for a scaphoid nonunion. Instead of coursing ulnar to the flexor carpi radialis tendon, deep to the antebrachial fascia between the tendons of the flexor carpi radialis and palmaris longus, the palmar cutaneous branch of the median nerve was noted to cross volar to the distal aspect of the flexor carpi radialis to lie on its radial aspect. Knowledge of the anatomic variant described in this report should encourage surgeons to dissect carefully as they expose the flexor carpi radialis during the exposure of the distal radius or scaphoid.

High-resolution sonography of the palmar cutaneous branch of the median nerve

OBJECTIVE

The aim of this study was to describe the potential value of high-resolution sonography for evaluation of the palmar cutaneous branch of the median nerve (MN).

SUBJECTS AND METHODS

The volar wrists of 12 healthy volunteers and 22 consecutive patients with sensory deficit in the palmar triangle and thenar eminence suggesting neuropathy of the palmar cutaneous branch of the MN were examined with high-frequency sonography. Nine patients underwent carpal tunnel release, five had a history of penetrating trauma, six had symptoms suggesting concurrent carpal tunnel syndrome, one received surgery for palmaris tendon transfer, and one underwent resection of a ventral carpal ganglion cyst. Correlative 1.5-T MRI was performed in six patients.

RESULTS

In 83% of the healthy volunteers, 17-5-MHz sonography was able to identify the palmar cutaneous branch of the MN from its origin down to slightly distal to the wrist crease. In the patient group, sonography allowed detection of nerve abnormalities in 55% of the cases. Focal hypoechoic swelling of the nerve at the fascial crossing was observed in patients who had either concurrent carpal tunnel syndrome (four cases) or previous carpal tunnel release (three cases). Sonography performed after a penetrating trauma revealed nerve encasement by scar tissue (two cases) or complete transection of the nerve ending in a terminal neuroma (one case). Nerve transection secondary to resection of a ventral carpal ganglion cyst (one case) or to carpal tunnel release (one case) was also observed.

CONCLUSION

Sonography can identify the palmar cutaneous branch of the MN and characterize its abnormalities, providing unique information about this small nerve branch.

Ulnar nerve palsy after open carpal tunnel decompression: Case report and review of the literature

Open carpal tunnel release is the commonest surgical treatment of median nerve compression at the wrist. Although successful in most cases, there are well described complications. We report a case of laceration of the deep motor branch of the ulnar nerve at the level of the hook of hamate following a complicated carpal tunnel decompression. Good surgical technique and knowledge of wrist anatomy are essential for performing this apparently simple procedure safely.

Standard open decompression in carpal tunnel syndrome compared with a modified open technique preserving the superficial skin nerves: a prospective randomized study

PURPOSE

A common surgical treatment for carpal tunnel syndrome is open carpal tunnel decompression. This involves skin incision followed by sharp dissection straight down through fat and palmar fascia to the transverse carpal ligament, which is then divided. The incidence of scar discomfort ranges from 19% to 61%, and its cause is not fully understood. We conducted a prospective randomized controlled trial to investigate whether preservation of superficial nerve branches crossing the incision site reduces the incidence and severity of postoperative scar pain after open carpal tunnel release.

METHODS

Forty-two patients with bilateral idiopathic carpal tunnel syndrome (84 hands) were included in the study. The patients were randomized to determine which hand was to have carpal tunnel decompression using a technique that would try to preserve the superficial nerve branches. The other hand had open carpal tunnel decompression without any attempt to preserve the superficial nerve branches. An assessment of each hand in each patient was performed immediately before surgery and at 6 weeks, 3 months, and 6 months after surgery. This assessment was performed with a questionnaire based on the Patient Evaluation Measure.

RESULTS

We found no evidence of a difference in scar pain between the 2 methods at 6 weeks, 3 months, and 6 months. There was a significant difference in the length of surgery between the 2 groups.

CONCLUSIONS

Scar pain scores in this series of open carpal tunnel decompressions were similar, whether or not an attempt was made to identify and preserve superficial nerve branches crossing the wound.

Surgical approaches to the carpus

The increasing numbers of wrist disorders amenable to surgical treatment have resulted in a myriad of described exposures of the wrist. The purpose of this article is to provide an updated review of the commonly used exposures to the carpus and the distal radioulnar joint in a hand surgery practice.

Étude anatomique de l’innervation de l’articulation trapézo-métacarpienne

PURPOSE OF THE STUDY

When the radiological signs are minimal in patients with a painful carpal syndrome involving the trapeziometacarpal joint (TMCJ), selective articular denervation can be proposed as an alternative after failure of conservative treatment. Results have been variable, sometimes disappointing, suggesting the anatomic basis of denervation should be revisited. The purpose of this work was to study the nerve supply to the TMCJ in order to acquire the indispensable elements necessary for performing effective selective articular denervation.

MATERIAL AND METHODS

This anatomical study was performed by dissection under magnification (4.5-x350) of 15 upper limb cadaver specimens. The median nerve, its thenar and volar cutaneous branches and the terminal sensorial branches of the radial nerve were dissected. Articular branches to the TMCJ were carefully identified. Histological samples were taken to verify the neurological nature of the elements dissected.

RESULTS

All TMCJs dissected exhibited radial and median nerve supply. Branches of the median nerve predominated in number and caliber. The volar cutaneous branch gave rise to articular branches in eleven dissections and the thenar branch gave rise to articular branches via a retrograde arciform trajectory between the short abductor and the opponens digiti pollicis in thirteen. For five dissections, the TMCJ branches arose directly from the median nerve within the carpal tunnel. At histological analysis the dissected elements were identified as nerves.

DISCUSSION

There have been few anatomic studies concerning the nerve supply of the TMCJ. Unlike the findings reported by Cozzi in 1960, we did not find the dorsal sensorial branch of the radial nerve to play an exclusive or preponderant role in the innervation of the TMCJ. The median nerve supply to the TMCJ appeared to be more significant, particularly for the volar cutaneous and especially thenar branches.

CONCLUSION

Total and definitive selective denervation of the TMCJ appears to be a most difficult procedure which would require a very wide access and extensive dissection, including the thenar branch which would raise the risk of significant complications.

Relationships of the palmar cutaneous branch of the median nerve: a morphometric study

Treatment of carpal tunnel syndrome consists in decompression of the median nerve by section of the flexor retinaculum. Usually, this surgery improves the disease with disappearance of the symptoms. However, some painful sequelae may remain such as painful discharges, paresthesiae or permanent anesthesia of the base of the thumb or of the scar related to an injury of the palmar cutaneous branch of the median nerve (PCBm). This study was performed to define the accurate emergence and the anatomic characteristics of this nerve in relation to stable landmarks. Moreover, it assessed the importance of the visual identification of the branch during section of the flexor retinaculum. Thirty-five hands were dissected under macroscopic examination and under magnification of the thinnest branches. Measurements were performed with a caliper and the forearm in supination. Determination of the bistyloid line showed variability in the location of the distal wrist crease. Thus, it could not be used as a landmark to locate the PCBm. The palmar cutaneous branch is the distal collateral branch of the median nerve in the forearm. It emerges on its radial side, on average 44.3 mm before the bistyloid line. It courses in line with the third finger and perforates the antebrachial aponeurosis about 5.7 mm from the bistyloid line. This emergence can be located in the palm, where it can be injured if the incision is performed in line with the third finger. The PCBm usually ends in the palm by division into two or three branches. The lateral branch supplies the skin of the thenar eminence while the medial, usually shorter branch supplies the midline part of the palm. This study has shown the importance of performing the cutaneous incision in line with the fourth finger to avoid injury to the PCBm.

Nerve fibre composition of the palmar cutaneous branch of the median nerve and clinical implications

Fifteen fresh human cadaver hands were dissected, using x2.8 loupe magnification, to study the subcutaneous innervation at the site of the incision (in the line with the radial border of the ring finger) for standard open carpal tunnel decompression. Subcutaneous nerve branches were detected and traced proximally to determine their origin. Morphometric analysis of nerve cross sections from the site of the incision and from the main nerve trunk proximal to cutaneous arborisation was performed using light and transmission electron microscopy and a computer-based image analysis system. At the site of the incision, the ulnar sub-branch (US) of the palmar cutaneous branch of the median nerve (PCBMN), which innervates the skin over the hypothenar eminence, was found in 10 of 15 cases. Branches from the ulnar side were not detected. The main trunk of PCBMN consisted on average of 1000 (SD 229) myelinated axons arranged in 1-4 fascicles. In the US of the PCBMN there were on average 620 (SD 220) myelinated axons, 80% of them smaller than 40 microm(2) i.e. thin myelinated axons, and on average 2037 (SD 1106) unmyelinated axons, arranged in 1-3 fascicles. The ratio of the number of myelinated axons in the US and the main trunk of the PCBMN was on average 63% (SD 19%). Frequency distribution of cross-sectional areas of myelinated axons shows no significant difference between the US and the main nerve trunk of the PCBMN. The importance of incision trauma to subcutaneous innervation of palmar triangle is emphasised and possible mechanisms of scar discomfort are discussed.

Surgical technique to reduce scar discomfort after carpal tunnel surgery

A total of 379 patients (416 hands) with clinically diagnosed and electromyographically confirmed carpal tunnel syndrome were enrolled in a prospective study to determine the influence of a modified open decompression technique on postoperative scar discomfort. The new technique used in 184 patients (200 hands) is presented. Special attention was focused on identification and preservation of macroscopically detectable subcutaneous nerves. After using this method, which permits complete visualization of the entire transverse carpal ligament, the incidence of postoperative scar discomfort was 2.5%. This was significantly lower compared with the group of 195 patients (216 hands) treated by standard open decompression technique, without preservation of subcutaneous nerves. Primary results regarding relieving symptoms were comparable in both groups. Five anatomic variations of subcutaneous innervation, at the site of the incision in the line with the radial border of the ring finger, are described. The etiology of scar discomfort is discussed.

The nerve supply of the trapeziometacarpal joint

Ten forearm and hand specimens from fresh cadavers were dissected and examined under magnification for articular branches to the trapeziometacarpal joint arising from the thenar and palmar cutaneous branches of the median nerve, the superficial branch of the radial nerve and the lateral cutaneous nerve of forearm. In all but one specimen the thenar branch of the median nerve sent an articular branch to the trapeziometacarpal joint. Multiple branches from the palmar cutaneous branch of the median nerve, the superficial branch of the radial nerve and the lateral cutaneous nerve of forearm were also found. All these branches need to be divided during a "complete" denervation of the trapeziometacarpal joint.