Injury of the dorsal sensory branch of the ulnar nerve as a complication of arthroscopic repair of the triangular fibrocartilage

Description of Specific Portals for Extensor Carpi Ulnaris Tenoscopy: Anatomical Safety Study

PURPOSE

The objective of this study was to describe potential working portals positioned directly over the extensor carpi ulnaris (ECU) tendon and assess their safety in relation to the dorsal branch of the ulnar nerve (DBUN).

METHODS

A descriptive anatomical study was conducted on 15 fresh human cadaver upper limbs. Five distinct portals over the ECU were examined, and the shortest distances from these portals to the DBUN were measured. Additionally, three distances from two portals and the ulnar styloid to the point where the DBUN crosses the ECU tendon were assessed.

RESULTS

The measurements of the distance to the DBUN from the portal at the level of the ulnocarpal joint (UCJ) from the proximal ECU (PECU) portal and from the portals located two and three centimeters proximal to the PECU indicate that no distances fell within the high-risk category (less than 3.5 mm). Measuring from the portal at the level of the UCJ to the DBUN, only one specimen fell within the medium-risk range (3.5-4.5 mm). However, in the rest of the previously described portals, all measurements corresponded to a low-risk range (more than 4.5 mm). The measurements from the distal ECU (DECU) portal to the DBUN revealed that 4 of 15 specimens had a distance less than 3.5 mm (high-risk range), whereas 2 of 15 fell within the medium-risk range.

CONCLUSIONS

Proximal portals are safer and present a lower risk of nerve injury. Three distinct zones have been defined along the ECU based on their safety characteristics. The "green zone" is the safest area, situated 1 cm proximal to the 6R portal. The "yellow zone" encompasses the area extending from 1 cm proximal to 0.5 cm distal to the 6R portal. Finally, the "red zone" is located 0.5 cm distal to the 6R portal.

CLINICAL RELEVANCE

For arthroscopic procedures involving the ECU, additional portals may be necessary. This anatomical study may be valuable in developing and implementing surgical techniques tailored for ECU pathology.

Computer assisted surgical anatomy mapping (CASAM) of the distal Posterior Interosseous Nerve (PIN) and its relation to the wrist arthroscopy portals: A cadaver study

Introduction

The distal Posterior Interosseous Nerve (PIN) plays an important part in the sensory innervation of the wrist joint. Introduction of the arthroscopy portals during wrist arthroscopy might injure the PIN. The anatomic variation in the trajectory of the PIN and the proximity to the dorsal arthroscopy portals have not yet been fully explored.

Materials and methods

Computer assisted surgical anatomy mapping (CASAM) is a technique to digitally compute and merge photographic images using anatomic landmarks and visualize variation in anatomy. A standard wrist arthroscopy procedure was carried out on eight cadaver forearms. CASAM was used to map the trajectory of the distal PIN and measure the distance to bony landmarks and the nearest wrist arthroscopy portals. Descriptive statistics were provided for anatomical measurements.

Results

CASAM illustrated great variation in the PIN trajectories between the specimens. The mean distance from the PIN to Lister's tubercle was 9 ​mm (range 3-14, SD 3.9), the distance to the ulnar styloid was 27 ​mm (range 23-32, SD 3.3). None of the nerves showed signs of iatrogenic injury from placement of the arthroscopy portals. The 3-4 portal and the 6R portal were closest to the PIN with a respective mean distance of 9 ​mm (range 4-15, SD 3.8) and 19 ​mm (range 13-22, SD 3.2).

Conclusion

CASAM demonstrated the importance of understanding nerve anatomy variations and offered insight into which arthroscopy portals are most likely to damage the distal PIN. However, we conclude that the overall risk of PIN injury from wrist arthroscopy is low due to the proximity to the portals.

Arthroscopic dual-bone tunnel repair for palmer type IB injuries of the triangular fibrocartilage complex

BACKGROUND

Triangular fibrocartilage complex (TFCC) injuries, especially Palmer type IB, pose surgical management challenges due to associated distal radial ulnar joint (DRUJ) instability. Traditional surgeries entail risks of complications. Arthroscopic repair presents advantages but lacks consensus on optimal techniques. To evaluate arthroscopic dual-bone tunnel repair in patients with Palmer type IB TFCC injuries of the wrist.

METHODS

In this retrospective case series, grip strength ratio, joint range of motion, pain visual analogue scale (VAS), modified Mayo wrist score, and Disabilities of the Arm, Shoulder, and Hand (DASH) scores were assessed before and 12 months after surgery.

RESULTS

The cohort consisted of 45 patients. At 12 months, the grip strength ratio improved from 0.71 ± 0.08 to 0.93 ± 0.05 (P < 0.001), and wrist joint rotation increased from 126.78 ± 13.28° to 145.76 ± 8.52° (P < 0.001). VAS (1.60 ± 0.58 vs. 6.33 ± 0.91, P < 0.001), DASH (12.96 ± 3.18 vs. 46.87 ± 6.62, P < 0.001), and modified Mayo wrist (88.11 ± 4.43 vs. 63.78 ± 7.99, P < 0.001) scores all improved after surgery. The overall complication rate was 4.44%.

CONCLUSION

Arthroscopic dual-bone tunnel repair appears to be an effective intervention for alleviating wrist pain, restoring stability, and enhancing joint function in patients with TFCC Palmer type IB injuries.

Safe zones in dorsal portals for wrist arthroscopy: a cadaveric study

The standard dorsal portals are the most commonly used in wrist arthroscopy. This cadaveric study aims to determine safe zones, by quantitatively describing the neurovascular relationships of the dorsal wrist arthroscopy portals: 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar. The neurovascular structures of twenty-one fresh frozen human cadaveric upper limbs were exposed, while the aforementioned portals were established with needles through portal sites. The minimum distance between portals and: dorsal carpal branch of radial artery, superficial branch of radial nerve, posterior interosseous nerve and dorsal branch of ulnar nerve, were measured accordingly with a digital caliper, followed by statistical analysis of the data. The median and interquartile range for each portal to structures at risk were determined and a safe zone around each portal was established. Free of any neurovascular structure safe zones surrounding 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals were found at 0.46mm, 2.33mm, 10.73mm, 11.01mm, 10.38mm, 5.95mm and 0.64mm respectively. Results of statistical analysis from comparisons between 1-2, 3-4 and midcarpal radial portals, indicated that 1-2 was the least safe. The same analysis among 3-4, midcarpal radial, midcarpal ulnar and 4-5 portals indicated that midcarpal portals were safer, while 3-4 was the least safe. Results among midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals indicated that 6-radial and specifically 6-ulnar were the least safe. This study provides a safe approach to the dorsal aspect of the wrist, enhancing established measurements and further examining safety of the posterior interosseous nerve.

Complications after arthroscopic triangular fibrocartilage complex (TFCC) surgery

Wrist arthroscopy is a valuable and widely utilized tool in the treatment of triangular fibrocartilage complex (TFCC) injuries. These procedures include synovectomy alone, peri-capsular or transosseous repair, and arthroscopic-assisted reconstruction, and each are associated with specific complications. This review describes the types of complications and their rates in different types of arthroscopic TFCC surgery reported in the literature and in our centre. Across the spectrum of arthroscopic TFCC surgery, complication rates and the learning curve increase with surgical complexity. Relevant anatomy, prevention and management of complications including nerve injury and irritation, extensor tendon injury and tendinitis, fracture, stiffness, and persistence of symptoms or instability are discussed. Vigilance to anatomical details and careful dissection can help to reduce complications that may result in disturbing pain and functional loss.

The Risk of Injury in Wrist Arthroscopy Portals: A Cadaveric Study

During wrist arthroscopy, the wrist joint can be visualized from almost every perspective through a combination of standard dorsal and volar arthroscopic portals. This cadaveric study aims to compare all wrist portals described in terms of their safety in order to rank them according to the distance from the nearest structure at risk for arthroscopic wrist procedures. Twenty-nine cadaveric formalin-embellished upper limbs were examined. Needles were inserted at dorsal and volar portal sites to perform the measurements. During the subsequent dissection, distances were measured as the shortest possible distance from the nearest structure at risk for each portal. Safe zones were determined for all portals, and the safety classification of arthroscopic wrist portals was proposed, ranking them from the safest to the most perilous. Applying the proposed safety classification to arthroscopic practice, wrist arthroscopy can be performed with a lower risk of iatrogenic complications arising from the implementation of the wrist portals.

Subcutaneous Dorsomedial Triangle of Forearm: Surgical Anatomy and Clinical Implication

Background The purpose of the study was to provide a practical landmark for localizing the dorsal branch of the ulnar artery and nerve, to approach for microsurgical flaps, for harvesting nerve grafts and also to avoid these nerves during insertion of wrist arthroscopy portals. Material and methods Forty adult cadaveric upper limbs (20 right and 20 left) were dissected for localizing the dorsal branches of the ulnar artery and nerve. The ramification patterns of the nerve were mapped. The wrist arthroscopy portals are located radial and ulnar to the tendon of extensor carpi ulnaris at the level of the wrist joint, and their designated names are '6R & 6U', respectively. The distance of branches of the nerve from the 6U and 6R portals for wrist arthroscopy was recorded. Results The present study has delineated a subcutaneous dorsomedial triangular area in the distal forearm. The construction of this triangle uses palpable landmarks, i.e. pisiform bone, styloid process and subcutaneous border of the ulna. The measure of the sides of the triangle uses proportion rather than absolute measurements and hence is person specific. The dorsal branches of the ulnar nerve and artery are consistently given off in the triangle's upper third and middle third, respectively. Four branching patterns have been mapped, with one dominant pattern in 67.5% of limbs. In three-fourths of cases, one branch of the dorsal branch of the ulnar nerve consistently overlies the 6U portal and hence runs a higher risk of injury. Conclusion The study suggests more practical, accurate, reliable and consistent surface landmarks for the localization of the dorsal branch of the ulnar artery and nerve for reconstructive microsurgery for distal hand defects.

Causes of Dorsal Cutaneous Branch of the Ulnar Nerve Neuropathy Among Patients Undergoing Electrodiagnostic Studies: A Series of 14 Patients

BACKGROUND

Isolated neuropathy of the dorsal cutaneous branch of the ulnar nerve (DCBUN) is rare and most cases are secondary to trauma, often iatrogenic. The topography of sensory abnormalities and abnormal electrodiagnostic (EDX) findings are crucial in confirming DCBUN neuropathy.  Materials and methods: This is a retrospective study of patients with isolated involvement of the DCBUN from among patients referred for EDX studies for upper extremity symptoms. All patients underwent a focused neurological examination followed by EDX studies. Ultrasound (US) studies were performed in two patients.  Results: Of the 14 patients with DCBUN neuropathy, decreased pinprick sensation in the distribution of the DCBUN was noted in 11 (78%) patients. DCBUN sensory nerve action potential (SNAP) was not recordable in 13 (92%) patients. In one patient who had a recordable SNAP, the latency was prolonged, and the amplitude was decreased. Four (28%) patients had incidental EDX abnormalities suggestive of entrapment of the median nerve at the carpal tunnel. The most common cause of DCBUN neuropathy was trauma in 13 (92%) patients, of which eight were iatrogenic. No specific etiology was detected in one patient (7%). Of the two patients who underwent US studies, one had increased cross-sectional area (CSA) at the wrist with prominent fascicles and hyperechoic scar tissue, while the CSA was normal in the other patient.

CONCLUSIONS

Although rare, DCBUN neuropathy can be readily confirmed by typical clinical features and EDX findings. Surgeons should be aware of the anatomy and clinical features of DCBUN neuropathy and avoid injuring the nerve during surgical procedures at the wrist and forearm.

Arthroscopic Excision of Hamate Osteoid Osteoma

Osteoid osteoma is considered the most common benign bone forming tumor accounting for 12% of all benign bone tumors. The carpus is a rare site for this tumor but quite a few cases were reported before. The lesion can be subperiosteal, cortical or medullary. Computed tomography scan is the gold standard diagnostic study, whereas magnetic resonance imaging can result in delaying the diagnosis as reported in the literature. Open excision with or without grafting was the technique of choice in most reviewed cases in the literature. In this paper we will illustrate a minimally invasive technique using wrist arthroscopy for an osteoid osteoma of hamate proximal pole. This minimally invasive arthroscopic technique provides a rapid recovery for patients with lesions that are accessible to wrist arthroscopy.

Designing a 20 mm incision to protect the dorsal branch of the ulnar nerve during arthroscopic repair of triangular fibrocartilage complex injuries: Cadaver study and preliminary clinical results

The ulnar-sided approach for arthroscopic peripheral triangular fibrocartilage complex (TFCC) repair may be associated with injury to the dorsal branch of the ulnar nerve (DBUN). The goal of this study was to develop a small incision to help minimize DBUN injury. Ten cadaveric upper limbs were used to measure the anatomic parameters of the DBUN. Based on these measured anatomical relationships, a 20 mm longitudinal incision with the ulnar styloid process as the midpoint was designed to explore and protect the DBUN. Three additional cadaveric upper limbs were used to test the feasibility of this method. Then this method was applied in 15 patients with TFCC injury (IB type). In 10 cadavers, the DBUN was located volar to the ulnar styloid process. The mean linear distance between the DBUN and the ulnar styloid process was 8.04 mm (range: 7.02-8.82mm) in the transverse-volar direction and 13.78 mm (range: 11.06-16.02mm) in the longitudinal-distal volar direction. In three additional cadavers, the DBUN was successfully explored and retracted with this incision, creating a safer space for passing sutures and tying knots. This modified method was used successfully in 15 patients, and the DBUN was protected during surgery. There were no complications, and most importantly, no injuries to the DBUN at the 6-month follow-up visit. Therefore, we recommend that a 20 mm longitudinal incision with the ulnar styloid process as the midpoint be made prior to passing sutures during the arthroscopic repair of TFCC tears to avoid injuring the various branches of the DBUN.

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.

Complications of Wrist and Hand Arthroscopy

Arthroscopy of the wrist continues to evolve and advance as a valuable clinical technique in hand surgery. This article aims to address safety of wrist arthroscopy and provide an overview of the known iatrogenic complications. Ultimately, the likelihood of associated injuries during wrist arthroscopy is dependent on the surgeon's ability and understanding of the equipment. Case volume and duration of experience directly correlate with mitigating iatrogenic injury and optimizing patient outcomes.

Results of Arthroscopic Repair of Peripheral Triangular Fibrocartilage Complex Tear With Exploration of Dorsal Sensory Branch of Ulnar Nerve

Background:

Ulnar-sided approach in arthroscopic triangular fibrocartilage complex (TFCC) repair may jeopardize treatment success by exposing the dorsal sensory branch of ulnar nerve (DSBUN) in risk of injury. We aim to conduct a follow-up assessment of arthroscopic outside-in TFCC repair and efficacy of sensory nerve exploration.

Methods:

We conducted a retrospective chart review of 58 patients (59 wrists) who received arthroscopic repair of the peripheral attachment of the TFCC. Ulnar-sided skin incision and exploration of DSBUN were performed before arthroscopy setting. Arthroscopic outside-in repair through pullout suture ligation was performed. Functional survey at 6 months and 1 year postoperatively was based on Mayo Modified Wrist Score (MMWS), and compared to the preoperative assessment. A p-value of less than 0.05 was considered significant as calculated using paired t-test.

Results:

Postoperative MMWS averaged 74.32±11.50 at 6 months, and 84.41±9.52 at one year; both showed significant difference as compared to preoperative status. Significant improvement was noted in all 4 individual items except motion retrieval between 6 months and 1 year. Totally, 45 (76%) cases achieved good or excellent results at one year; however, less patients resumed pre-injury activity level when treatment delay was more than 6 months than those treated earlier (41% vs. 57%). Complication included 6 transient paresthesia; 1 anchor migration and 1 distal radioulnar arthrosis. No more nerve complication was found after modification of perineural dissection.

Conclusion:

Arthroscopy is effective in obtaining both correct diagnosis and treatment of peripheral TFCC tear. Modified perineural dissection can minimize sensory nerve complications.

Management of painful scar-tethered cutaneous nerves of the upper limb

We report the results of treatment by division and proximal relocation of 44 painful, scar-tethered cutaneous nerves of the upper limb in 22 patients. In all patients, neuropathic pain had developed either following surgery or trauma, but without apparent direct nerve injury. The mean duration of pain symptoms prior to relocation was 17 (range 7-44) months. Adequate treatment involved relocation of 35 nerves at a first operation for each of the 22 patients, with six patients requiring further surgery to relocate 9 nerves. At a minimum follow-up of 6 months, nerve relocation resulted in complete resolution of all forms of pain at the primary site in 21/22 (95%) patients and no pain or hypersensitivity at the final relocation site in 19 of the 22 patients (86%).

Can the Diagnostics of Triangular Fibrocartilage Complex Lesions Be Improved by MRI-Based Soft-Tissue Reconstruction? An Imaging-Based Workup and Case Presentation

Introduction. The triangular fibrocartilage complex (TFCC) provides both mobility and stability of the radiocarpal joint. TFCC lesions are difficult to diagnose due to the complex anatomy. The standard treatment for TFCC lesions is arthroscopy, posing surgery-related risks onto the patients. This feasibility study aimed at developing a workup for soft-tissue reconstruction using clinical imaging, to verify these results in retrospective patient data. Methods. Microcomputed tomography (μ-CT), 3 T magnetic resonance imaging (MRI), and plastination were used to visualize the TFCC in cadaveric specimens applying segmentation-based 3D reconstruction. This approach further trialed the MRI dataset of a patient with minor radiological TFCC alterations but persistent pain. Results. TFCC reconstruction was impossible using μ-CT only but feasible using MRI, resulting in an appreciation of its substructures, as seen in the plastinates. Applying this approach allowed for visualizing a Palmer 2C lesion in a patient, confirming ex postum the arthroscopy findings, being markedly different from MRI (Palmer 1B). Discussion. This preliminary study showed that image-based TFCC reconstruction may help to identify pathologies invisible in standard MRI. The combined approach of μ-CT, MRI, and plastination allowed for a three-dimensional appreciation of the TFCC. Image quality and time expenditure limit the approach's usefulness as a diagnostic tool.

Proximity of the Triangular Fibrocartilage Complex to Key Surrounding Structures and Safety Assessment of an Arthroscopic Repair Technique: A Cadaveric Study

PURPOSE

To quantify the distance of the dorsal ulnar sensory branch, floor of the extensor carpi ulnaris (ECU) subsheath, and ulnar neurovascular bundles from the triangular fibrocartilage complex (TFCC), and secondarily to assess the safety of an all-inside arthroscopic repair of the TFCC with a commonly used meniscal repair device with respect to the aforementioned structures.

METHODS

A custom K-wire with 1-mm gradation was used to determine the distance of at-risk structures from the periphery of the TFCC in 13 above-elbow human cadaver specimens. An all-inside repair of the TFCC at the location of a Palmer 1B tear was then performed using a commonly employed meniscal repair device. The distance from the deployed devices to the structure in closest proximity was then measured using digital calipers.

RESULTS

The mean distance from the deployed device to the nearest structure of concern for iatrogenic injury was 9.4 mm (range, 5-15 mm). The closest structure to iatrogenic injury was usually, but not always, the dorsal ulnar sensory nerve in 9 of 13 wrists (69.2%) at 9.3 mm (range, 5-15 mm); on 3 occasions it was instead the ulnar nerve (23.1%) at 9.5 mm (range, 9-10 mm), and on 1 occasion 6 mm from the flexor digitorum profundus to the little finger (7.7%). Forearm rotation had no significant effect on measured distances (ulnar nerve: P = .98; dorsal sensory: P = .89; ECU: P = .90). The largest influence of forearm rotation was a 0.4-mm difference between pronation and supination with respect to the distance of the TFCC periphery on the ECU subsheath.

CONCLUSIONS

An all-inside arthroscopic TFCC repair using a commonly used meniscal repair device appears safe with respect to nearby neurovascular structures and tendons under typical arthroscopic conditions.

CLINICAL RELEVANCE

An all-inside arthroscopic TFCC repair using a commonly employed meniscal repair device appears safe in terms of proximity to important structures although further clinical investigation is warranted.

Safety of dorsal wrist arthroscopy portals: A magnetic resonance study

In wrist arthroscopy, the standard dorsal portals are the most commonly used. However, their placement can be associated with injuries to the neurovascular structures of the radiocarpal joint. The present study assessed and compared the distance of commonly used dorsal portals to radial and ulnar neurovascular structures. Forty patients (20 males, 20 females) were evaluated with T1-weighted spin-echo (SE) magnetic resonance (MR) sequences. We measured the distance between 1-2 and 3-4 portals and radial vascular bundle and the nearest branch of the superficial branch of radial nerve (SBRN). We also measured the distance between 4 and 5, 6/U and 6/R and ulnar vascular bundle and the nearest branch of the dorsal ulnar nerve (DUN). The median age of patients was 39 years (95% IC 36.97-43.32 years). The 3-4 portal was farther away from the vascular structure than the 1-2 portal (P < 0.0001), 4-5 portal (P = 0.008), 6/R (P < 0.0001), and 6/U portals (P < 0.0001). Moreover, the 3-4 portal was farther away from the nerve branch than the 1-2 portal (P < 0.0001), 4-5 portal (P < 0.0001), 6/R (P < 0.0001), and 6/U portals (P < 0.0001). No statistical significant differences were found between the two genders. The 3-4 and 4-5 portals are the farthest away from the neurovascular structures, and likely reduce the risk to damage these structures. On the other hand, the 1-2 and 6/U portals likely increase the risk of neurovascular damage, because of their proximity to neurovascular structures.

LEVEL OF EVIDENCE

Diagnostic study; Level III.

Complications of Wrist Arthroscopy: A Multicenter Study Based on 10,107 Arthroscopies

Background Wrist arthroscopy is now a routine procedure, regarded as safe. Complications are reported in the literature as being rare and mostly minor. Purpose The two goals of this study were to evaluate the incidence and nature of complications based on a very large multicenter retrospective study, and to investigate about a potential learning curve. Methods The authors sent a detailed questionnaire to all members of the European Wrist Arthroscopy Society (EWAS), inquiring about the number and types of complications encountered during their practice of wrist arthroscopy, and about their experience with the technique. Results A total of 36 series comprising 10,107 wrist arthroscopies were included in the study. There were 605 complications (5.98% of the cases), of which 5.07% were listed as serious and 0.91% as minor. The most frequent ones were failure to achieve the procedure (1.16%), and nerve lesions (1.17%). Cartilage lesions and complex regional pain syndrome each occurred in 0.50% cases. Other complications (wrist stiffness, loose bodies, hematomas, tendon lacerations) were less frequent. Breaking down of the data according to each surgeon's experience of the technique showed a significant relationship with the rate of complications, the threshold for a lower complication rate being approximately 25 arthroscopies a year and/or greater than 5 years of experience. Conclusion Although the global incidence of complications was in keeping with the literature, the incidence of serious complications was much higher than previously reported. There is a significant learning curve with the technique of wrist arthroscopy, both in terms of volume and experience.

Assessment of the structures at risk during wrist arthroscopy: a cadaveric study and systematic review

We assessed the proximity of neurological structures to arthroscopic portals in a cadaveric study and through a systematic review. Arthroscopy was performed on ten cadaveric wrists. Subsequently the specimens were dissected to isolate the superficial branch of the radial nerve, the dorsal branch of the ulnar nerve, the posterior interosseous nerve and the extensor tendons. We measured the distances from the nerves to common portals. For the systematic review Pubmed and EMBASE were searched on the 31 May 2014 for cadaveric studies reporting the proximity of neurological structures to any arthroscopic wrist portal. In the cadaveric study, partial injuries were seen to six extensor tendons and one posterior interosseous nerve; it was assumed this was due to creation of the portals. Seven published studies were included in the systematic review. The dorsal sensory branch of the ulnar nerve was found to be at risk by performing the 6 Ulnar, 6 Radial and ulnar midcarpal portals, the sensory branch of the radial nerve by the 1-2 and 3-4 portals and the posterior interosseous nerve by the 3-4 and 4-5 portals.

LEVEL OF EVIDENCE

V.

The Anatomical Relationship Between the Dorsal Cutaneous Branch of the Ulnar Nerve and the Ulnar Styloid Process with Variations in Forearm Position

BACKGROUND

There are significant variations in the anatomy of the dorsal cutaneous branch of the ulnar nerve (DCBUN). The DCBUN is at risk for iatrogenic injury during surgeries around the ulnar side of the wrist. The purpose of this study was to demonstrate the relationship between the ulnar styloid process and the DCBUN and to confirm the DCBUN's change in location with different forearm positions.

METHODS

We examined 9 fresh frozen cadaveric limbs to establish the course of this nerve. The DCBUN was dissected and traced around the ulnar border of the wrist. The distance from the tip of the ulnar styloid process to the origin of the DCBUN was measured. The distances from the ulnar styloid process to the DCBUN were measured in supination, pronation, and in a neutral position of the forearm.

RESULTS

The DCBUN originated on average 4.92 cm proximal to the ulnar styloid process. In all cases, the DCBUN crossed the ulnar distal to ulnar styloid process and it moved more closely to the ulnar styloid process with a forearm position change from supination to pronation.

CONCLUSIONS

We recommend making a skin incision on the ulnar side around the styloid process with the forearm in supination or neutral position was another method to avoid injury of DCBUN.

Risk of Injury to the Dorsal Sensory Branch of the Ulnar Nerve With Percutaneous Pinning of Ulnar-Sided Structures

PURPOSE

To assess the risk of injury to the dorsal sensory branch of the ulnar nerve (DSBUN) with percutaneous pinning of commonly stabilized ulnar-sided structures.

METHODS

Eleven fresh-frozen cadaveric upper extremities were assessed. Percutaneous pinning of the fifth metacarpal base and neck, lunotriquetral joint, ulnar styloid, and distal radioulnar joint (DRUJ) with 1.4-mm Kirschner wires was performed under fluoroscopic guidance. Each specimen was then carefully dissected and the distance from each pin to the DSBUN was measured using a digital caliper. Direct injury to the DSBUN and pins found immediately adjacent to the nerve were recorded.

RESULTS

Mean distance from the pin to the DSBUN at the fifth metacarpal neck was 5.0 ± 1.5 mm; fifth metacarpal base, 2.3 ± 2.2 mm; lunotriquetral joint, 1.8 ± 1.6 mm; ulnar styloid, 0.8 ± 1.1 mm; and DRUJ, 3.1 ± 0.9 mm. Two of 11 ulnar styloid pins and 1 of 11 lunotriquetral pin directly penetrated the DSBUN, whereas 4 of 11 ulnar styloid pins, 3 of 11 fifth metacarpal base pins, and 2 of 11 lunotriquetral pins were directly adjacent to the DSBUN. There was an increased overall risk of DSBUN injury (risk of direct injury and risk of adjacent pin) with pinning of the ulnar styloid compared with fifth metacarpal neck and DRUJ pinning.

CONCLUSIONS

The current study demonstrates the risk of iatrogenic injury to the DSBUN with percutaneous pinning of the ulnar styloid, lunotriquetral joint, and fifth metacarpal base.

CLINICAL RELEVANCE

We recommend identifying and protecting the nerve to mitigate the risk of iatrogenic injury when performing ulnar-sided pinning of structures from the ulnar styloid to the fifth metacarpal base.

Anatomical relationships and branching patterns of the dorsal cutaneous branch of the ulnar nerve

PURPOSE

To describe the variable branching patterns of the dorsal cutaneous branch of the ulnar nerve (DCBUN) relative to identifiable anatomical landmarks on the ulnar side of the wrist.

METHODS

We dissected the ulnar nerve in 28 unmatched fresh-frozen cadavers to identify the DCBUN and its branches from its origin to the level of the metacarpophalangeal joints. The number and location of branches of the DCBUN were recorded relative to the distal ulnar articular surface. Relationships to the subcutaneous border of the ulna, the pisotriquetral joint, and the extensor carpi ulnaris tendon were defined in the pronated wrist.

RESULTS

On average, 2 branches of the DCBUN were present at the level of the distal ulnar articular surface (range, 1-4). On average, 2.2 branches were present 2 cm distal to the ulnar articular surface (range, 1-4). At least 1 longitudinal branch crossed dorsal to the extensor carpi ulnaris tendon prior to its insertion at the base of the fifth metacarpal in 23 of 28 specimens (82%). In 27 of 28 specimens (96%), all longitudinal branches of the DCBUN coursed between the dorsal-volar midpoint of the subcutaneous border of the ulna and the pisotriquetral joint. In 20 of 28 specimens (71%), a transverse branch of the DCBUN to the distal radioulnar joint was present.

CONCLUSIONS

During exposure of the dorsal and ulnar areas of the wrist, identification and protection of just a single branch of the DCBUN are unlikely to ensure safe dissection because multiple branches normally are present. The 6U, 6R, and ulnar midcarpal arthroscopy portals may place these branches at risk. In the pronated forearm, the area between the DCBUN and the pisotriquetral joint contained all longitudinal branches of the DCBUN in 96% of specimens.

CLINICAL RELEVANCE

During surgery involving the dorsal and ulnar areas of the wrist, multiple longitudinal branches and a transverse branch of the DCBUN are normally present and must be respected.

Anatomical study of the dorsal cutaneous branch of the ulnar nerve using ultrasound

OBJECTIVES

To determine whether ultrasound allows precise assessment of the course and relations of the dorsal cutaneous branch of the ulnar nerve (DCBUN).

METHODS

This work, initially undertaken in cadavers, was followed by high-resolution ultrasound study in 20 healthy adult volunteers (40 nerves) by two musculoskeletal radiologists in consensus. Location and course of the DCBUN and its relations to adjacent anatomical structures were analysed.

RESULTS

The DCBUN was consistently identified along its entire course by ultrasound. Mean cross-sectional area of the nerve was 1.6 mm(2) (range 1.1-2.2). The level at which the DCBUN branches from the ulnar nerve was located a mean of 57 mm (range 40-80) proximal to the ulnar styloid process and 11 mm (range 7-15) radial to the medial border of the ulna. The DCBUN then crossed the medial border of the ulna a mean of 14 mm (range 6-25) proximal to the ulnar styloid process.

CONCLUSION

The DCBUN is clearly depicted by ultrasound. Precise mapping of its anatomical course could have significant clinical applications, such as preventing injury during surgery of the ulnar side of the wrist or helping in the diagnosis of chronic pain of the ulnar side of the hand.

KEY POINTS

• The dorsal cutaneous branch of the ulnar nerve (DCBUN) is often injured. • The DCBUN originates from the ulnar nerve in the distal third of the forearm. • It can be clearly depicted by ultrasound. • The level at which the DCBUN crosses the ulna is variable. • Precise mapping of its anatomical course could have significant clinical applications.

Complications of wrist arthroscopy

PURPOSE

The purpose of this systematic review was to address the incidence of complications associated with wrist arthroscopy. Given the paucity of information published on this topic, an all-inclusive review of published wrist arthroscopy complications was sought.

METHODS

Two independent reviewers performed a literature search using PubMed, Google Scholar, EBSCO, and Academic Megasearch using the terms "wrist arthroscopy complications," "complications of wrist arthroscopy," "wrist arthroscopy injury," and "wrist arthroscopy." Inclusion criteria were (1) Levels I to V evidence, (2) "complication" defined as an adverse outcome directly related to the operative procedure, and (3) explicit description of operative complications in the study.

RESULTS

Eleven multiple-patient studies addressing complications of wrist arthroscopy from 1994 to 2010 were identified, with 42 complications reported from 895 wrist arthroscopy procedures, a 4.7% complication rate. Four case reports were also found, identifying injury to the dorsal sensory branch of the ulnar nerve, injury to the posterior interosseous nerve, and extensor tendon sheath fistula formation.

CONCLUSIONS

This systematic review suggests that the previously documented rate of wrist arthroscopy complications may be underestimating the true incidence. The report of various complications provides insight to surgeons for improving future surgical techniques.

LEVEL OF EVIDENCE

Level IV, systematic review of Levels I-V studies.

The surgical management of painful nerves of the upper limb: a unit perspective

Some patients develop excessive peripheral nerve pain beyond that normally experienced after injury or surgery. Managing this pain can be a difficult and frustrating experience for both the surgeon and patient concerned. We present a system for the classification, assessment and treatment of painful neuromas of the upper limb.

Accidental section of the ulnar nerve in the wrist during arthroscopy

Arthroscopy of the wrist is a frequently performed procedure. Its role in diagnosis and treatment is significant. The complications of arthroscopy are well known and are described in the literature. We describe a case of accidental section of the ulnar nerve during repair of the triangular fibrocartilage complex during arthroscopy. The nerve section was caused by the trocar used for drainage in the 6U portal. We propose to establish the injury mechanism and describe a safe procedure for this examination.

The dorsal cutaneous branch of the ulnar nerve: an anatomical study

There are significant variations in the anatomy of the dorsal cutaneous branch of the ulnar nerve. The dorsal cutaneous branch is at a risk of injury during a therapy for the ulnar side of the wrist. The purpose of this study is to measure the variations of the dorsal cutaneous branch. We studied 30 embalmed cadaver specimens. In its course, two division patterns of the dorsal cutaneous branch were identified, namely proximal and distal types. The proximal type went around the ulna proximal to the ulnar styloid process, and directed toward the ulnodorsal aspect. The distal type went around to the ulnodorsal aspect, distal to the styloid process. The proximal type was found in 21 of 30 cadavers, and the distal type was found in nine of 30 cadavers.

Safety analysis of all-inside arthroscopic repair of peripheral triangular fibrocartilage complex

PURPOSE

The purpose of this study was to determine whether an all-inside peripheral triangular fibrocartilage complex (TFCC) repair using the FasT-Fix device (Smith & Nephew Endoscopy, Andover, MA) is safe by measuring the proximity of the anchors to ulnar-sided anatomic structures.

METHODS

Eleven fresh-frozen cadaveric wrists were thawed and placed in traction. Under direct arthroscopic visualization, an all-inside arthroscopic peripheral TFCC repair was completed by placing a single FasT-Fix device in a vertical mattress fashion. The wrists were then dissected to visualize the 2 anchors. The distance between these anchors and the flexor carpi ulnaris (FCU), extensor carpi ulnaris (ECU), and dorsal branch of the ulnar sensory nerve (DBUN) were measured with digital calipers and recorded.

RESULTS

The peripheral anchor averaged 4.2 mm (range, 0 to 14 mm) from the ECU tendon, 3.8 mm (range, 0 to 9 mm) from the DBUN, and 8.3 mm (range, 1 to 15 mm) from the FCU tendon. The central anchor averaged 9.6 mm (range, 2 to 15 mm) from the ECU tendon, 6.8 mm (range, 1 to 13 mm) from the DBUN, and 7.6 mm (range, 1 to 13 mm) from the FCU tendon.

CONCLUSIONS

This study exposes some safety concerns with the all-inside peripheral TFCC repair using the FasT-Fix device, which was found to reside in close proximity to the ECU, FCU, and DBUN. In multiple wrists the anchors were noted to underlie the anatomic structure that we measured, making it possible to pierce these structures with the needle before deployment of the anchor.

CLINICAL RELEVANCE

Though technically feasible, all-inside arthroscopic repair of the peripheral TFCC risks injury to the ulnar-sided anatomy.

The anatomy of the dorsal cutaneous branch of the ulnar nerve

We investigated the anatomy of the dorsal cutaneous branch of the ulnar nerve in 32 upper limbs in cadavers. The dorsal cutaneous branch of the ulnar nerve originated on average 5.1 cm proximal to the ulnar styloid process and 1.9 cm palmar and radial to the subcutaneous border of the ulna. It crossed the subcutaneous border 0.2 cm proximal to the ulnar styloid process. In all cases it displaced further away in full pronation. We recommend cautious dissection when approaching within 2.5 cm of the ulnar styloid process. We also recommend making the initial incision in full pronation and just along the dorsal aspect of the subcutaneous border of the ulna.

A technique for arthroscopic all-inside suturing in the wrist

A technique for arthroscopic all-inside suturing in the wrist is presented. The procedure allows placement of the knot inside the joint without additional incisions. We have applied it in cases of dorsal, foveal and coronal tears of the triangular fibrocartilage. No special instrument is required apart from a Tuohy needle.

Anatomic relation of dorsal wrist arthroscopy portals and superficial nerves: a cadaveric study

PURPOSE

The aim of this cadaveric study was to assess and compare the distance of commonly used dorsal wrist portals to the dorsal ulnar and radial superficial nerves and their branches.

METHODS

Twenty embalmed cadaveric upper limbs were dissected, exposing the nerves and tendons, and wrist arthroscopy portal sites were marked with pins. The horizontal distance between the portals and closest nerve branch was measured with a digital caliper. Statistical analysis of the data was performed with SPSS software for Windows (version 11.5; SPSS, Chicago, IL) by use of Friedman tests and Wilcoxon signed rank tests.

RESULTS

The median distance of the nearest nerve branch to portal 1-2 was 1.82 mm; portal 3-4, 4.85 mm; portal 4-5, 16.13 mm; portal 6U, 2.47 mm; and midcarpal radial portal (MCP), 6.65 mm. The 4-5 portal was safer than the 1-2 portal (P < .0001), 3-4 portal (P = .015), MCP (P = .001), and 6U portal (P < .0001). The MCP was safer than the 1-2 portal (P = .01), 3-4 portal (P = .019), and 6U portal (P = .003).

CONCLUSIONS

The 4-5 portal is further away from a nerve branch than any other portal, followed by the MCP.

CLINICAL RELEVANCE

The results of this study may be of use in the planning of wrist arthroscopy.