Wrist Arthroscopy: A Masterclass in Dorsal, Midcarpal, and Volar Portal Techniques

Alright, fellows, gather 'round. Welcome to the operating theater. Today, we're delving into the intricate world of wrist arthroscopy. This isn't just about poking holes in a joint; it's about a deep understanding of three-dimensional anatomy, precise instrument handling, and the ability to diagnose and treat pathology that often eludes open approaches. Wrist arthroscopy has evolved significantly, moving from a purely diagnostic tool to a powerful therapeutic modality for a wide array of conditions, from ligamentous injuries to complex fractures and degenerative changes. Our goal today is to master the art of portal placement – dorsal, midcarpal, and volar – understanding the rationale, the risks, and the unparalleled insights each offers.

Indications for Wrist Arthroscopy

First, let's review our indications. When do we bring a patient to the OR for this procedure?

• Persistent Wrist Pain: The primary indication is persistent wrist pain that has failed an appropriate trial of conservative management. This includes nonsteroidal anti-inflammatories, activity modification, and cortisone injections. If their pain remains undiagnosed or refractory, arthroscopy provides an unparalleled diagnostic and often therapeutic opportunity.
• Diagnostic Technique: It serves as a superior diagnostic technique for conditions like scapholunate (SLIL) and lunotriquetral (LTIL) instability, where subtle findings might be missed on standard imaging.
• Adjuvant Procedure: We frequently use it as an adjuvant procedure for acute fractures, such as distal radius or scaphoid fractures, allowing for direct visualization of articular reduction and assessment of associated soft tissue injuries.
• Staging Degenerative Disorders: For conditions like scapholunate advanced collapse (SLAC), scaphoid nonunion advanced collapse (SNAC), or Kienböck disease, arthroscopy allows for precise staging of cartilage damage and guides our treatment decisions.
• Therapeutic Interventions: Beyond diagnosis, it's indicated for various therapeutic procedures, including:
  • Ganglion resection (both dorsal and volar)
  • Release of wrist contractures
  • Arthroscopic synovectomy
  • Radial styloidectomy
  • Proximal pole of hamate resection
  • Dorsal radiocarpal ligament repair
  • Evaluation and treatment of carpal instability (scapholunate, lunotriquetral, midcarpal)
  • Triangular fibrocartilage complex (TFCC) repair or debridement
  • Management of chondral lesions and loose bodies.

Contraindications to Wrist Arthroscopy

While powerful, wrist arthroscopy is not without its contraindications. Always consider these carefully:

• Marked Swelling: Significant wrist swelling can distort topographic anatomy, making accurate portal placement hazardous and increasing the risk of neurovascular injury.
• Large Capsular Tears: Pre-existing large capsular tears can lead to excessive extravasation of irrigation fluid into the surrounding soft tissues, obscuring visualization and potentially causing compartment syndrome.
• Neurovascular Compromise: Any pre-existing neurovascular compromise is a relative contraindication, as the procedure could exacerbate the condition.
• Bleeding Disorders: Uncontrolled bleeding disorders significantly increase the risk of hematoma formation and poor visualization.
• Active Infection: An active local or systemic infection is an absolute contraindication, as it risks spreading the infection into the joint.
• Unfamiliarity with Regional Anatomy: This is a crucial relative contraindication. If you are not intimately familiar with the complex neurovascular and tendinous anatomy of the wrist, particularly the volar aspect, do not proceed.

Preoperative Planning and Patient Positioning

Before we even consider making an incision, meticulous preoperative planning and patient positioning are paramount for a successful and safe wrist arthroscopy.

Preoperative Planning

1. Imaging Review: Thoroughly review all available imaging – plain radiographs, CT scans, and MRI. Understand the suspected pathology, identify any osteophytes, loose bodies, or anatomical variations.
2. Templating: Mentally template your portal placements. Consider the specific pathology you're targeting and which portals will offer the best visualization and access for instrumentation.
3. Fluoroscopy Setup: Plan your fluoroscopy setup. We'll need a C-arm that can easily be brought in and out without contaminating the field. Ensure it's draped and tested before draping the patient.
4. Instrument Tray: Confirm all necessary arthroscopic instruments are available: various sizes of arthroscopes (2.7mm and 1.9mm are standard), blunt and sharp trocars, cannulas, probes, shavers, graspers, and specific repair tools if a repair is anticipated.

Patient Positioning and Setup

1. Anesthesia: General anesthesia or regional block (e.g., supraclavicular or axillary block) is acceptable. For longer cases, general anesthesia with a regional block for postoperative pain control is often preferred.
2. Patient Position: The patient is positioned supine on the operating table.
3. Arm Positioning: The affected arm is placed on a specialized hand table or a padded arm board. The elbow should be flexed to 90 degrees, and the arm abducted to allow comfortable access for the surgeon.
4. Traction Tower: A traction tower is essential for distracting the radiocarpal and midcarpal joints, creating space for the arthroscope and instruments.
   • Attachment: The traction tower is typically clamped to the operating table.
   • Fingertrap Application: Sterile finger traps are applied to the index and middle fingers (or middle and ring fingers, depending on desired distraction vector) of the affected hand.
   • Weight: We typically apply 10-15 pounds of traction. The goal is sufficient distraction to allow joint entry without excessive force that could cause neuropraxia. Always ensure the traction is pulling in line with the forearm.
5. Tourniquet: A pneumatic tourniquet is applied to the upper arm. This provides a bloodless field, crucial for clear arthroscopic visualization. We will inflate it after exsanguination.
6. Exsanguination: The limb is exsanguinated using an Esmarch bandage from distal to proximal.
7. Sterile Preparation and Draping: The entire hand, wrist, and forearm are prepped with an antiseptic solution (e.g., chlorhexidine or povidone-iodine) and then draped in a sterile fashion, ensuring the traction tower and C-arm are also draped appropriately.

Surgical Anatomy: A Portal-by-Portal Masterclass

Now, let's talk anatomy. Precision in portal placement is paramount. We must be intimately familiar with the superficial landmarks, the underlying tendinous intervals, and, critically, the neurovascular structures at risk.

Dorsal Radiocarpal Portals

These are our workhorse portals, offering excellent views of the radiocarpal joint due to the relative paucity of major neurovascular structures dorsally.

1. The 3-4 Portal

• Location: This portal lies in the interval between the third and fourth dorsal extensor compartments, approximately 1 cm distal to Lister's tubercle.
• Anatomy:
  • Third Compartment: Contains the extensor pollicis longus (EPL) tendon.
  • Fourth Compartment: Houses the extensor digitorum communis (EDC) tendons.
  • Lister's Tubercle: A prominent bony landmark on the dorsal aspect of the distal radius, serving as a key reference point for many dorsal portals.
• Neurovascular Risks: Generally considered a safe portal. The main risk is injury to minor branches of the dorsal cutaneous branch of the ulnar nerve or superficial radial nerve, though these are typically more radially or ulnarly located. Careful blunt dissection minimizes this risk.
• Function: This is a primary viewing portal for the radial aspect of the radiocarpal joint and often serves as an initial entry point for establishing fluid inflow. It's also excellent for instrumentation.

2. The 4-5 Portal

• Location: Situated between the fourth and fifth dorsal extensor compartments.
• Anatomy:
  • Fourth Compartment: Extensor digitorum communis (EDC) tendons.
  • Fifth Compartment: Contains the extensor digiti minimi (EDM) tendon.
• Neurovascular Risks: Similar to the 3-4 portal, generally safe, but transverse branches of the dorsal cutaneous branch of the ulnar nerve can be in proximity. Again, blunt dissection is key.
• Function: A crucial viewing portal for the ulnocarpal joint and for introducing instruments to address ulnar-sided pathology, particularly TFCC tears.

3. The 6R Portal (Radial to ECU)

• Location: On the radial side of the extensor carpi ulnaris (ECU) tendon.
• Anatomy: The ECU tendon lies within the sixth dorsal extensor compartment. Identifying the ECU is critical.
• Neurovascular Risks: Generally safe, but care must be taken to avoid the dorsal cutaneous branch of the ulnar nerve, which can course near this area.
• Function: Primarily used for instrumentation, especially when working on the ulnocarpal joint or TFCC. It allows for triangulation with the 4-5 portal.

4. The 6U Portal (Ulnar to ECU)

• Location: On the ulnar side of the extensor carpi ulnaris (ECU) tendon.
• Anatomy: Again, the ECU tendon is the key landmark.
• Neurovascular Risks: The dorsal cutaneous branch of the ulnar nerve is at increased risk here. Be mindful of its course.
• Function: Typically used as an outflow portal for irrigation fluid, but can also be used for visualization or instrumentation in specific cases.

5. The 1-2 Portal

• Location: This portal lies between the first and second dorsal extensor compartments.
• Anatomy:
  • First Compartment: Contains the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons.
  • Second Compartment: Contains the extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB) tendons.
• Neurovascular Risks: The superficial radial nerve (SRN) is highly vulnerable in this region. Its branches can be quite variable. Meticulous blunt dissection and careful palpation of the tendons are crucial.
• Function: Used less frequently than 3-4 or 4-5, but provides an excellent view for radial styloidectomy, visualizing the radioscaphoid joint, and addressing specific pathologies on the radial side.

Dorsal Distal Radioulnar Joint (DRUJ) Portals

These portals offer direct access to the DRUJ for assessing its articular cartilage and ligaments.

1. The Dorsal Radioulnar Joint Portal (Proximal and Distal)

• Location: Lies between the ECU and the EDM tendons. There can be a proximal (PDRUJ) and a distal (DDRUJ) portal.
• Anatomy: The interval between the fifth (EDM) and sixth (ECU) extensor compartments.
• Neurovascular Risks: Transverse branches of the dorsal cutaneous branch of the ulnar nerve are the only sensory nerves in proximity, typically at a mean of 17.5 mm distally (range 10–20 mm) from the portal. Careful dissection is still advised.
• Function: Used in concert with the volar distal radioulnar portal to fully assess the articular cartilage of the ulnar head and sigmoid notch, and for instrumentation within the DRUJ.

Dorsal Midcarpal Portals

Midcarpal arthroscopy is essential for diagnosing instability and assessing carpal kinematics.

1. The Midcarpal Radial Portal (MCR)

• Location: Approximately 1 cm distal to the 3-4 portal. It is bounded radially by the ECRB tendon and ulnarly by the EDC tendons.
• Anatomy: This portal enters the midcarpal joint, providing a view of the scaphoid, lunate, capitate, and hamate articulations.
• Neurovascular Risks: Generally safe, but the superficial radial nerve branches can be in the vicinity more radially.
• Function: A primary viewing portal for midcarpal arthroscopy, allowing triangulation with the midcarpal ulnar portal for instrumentation. Essential for probing the SLIL and LTIL joint spaces for instability and assessing chondral lesions.

2. The Midcarpal Ulnar Portal (MCU)

• Location: Similarly located 1 to 2 cm distal to the 4-5 portal. It is bounded by the EDC and the EDM tendons.
• Anatomy: Enters the midcarpal joint, providing views of the lunotriquetral articulation, hamate, and capitate.
• Neurovascular Risks: The dorsal cutaneous branch of the ulnar nerve is at risk here.
• Function: Complements the midcarpal radial portal for triangulation, allowing instrumentation for débridement, loose body removal, or chondroplasty.

3. The Triquetrohamate Portal (T-H)

• Location: Enters the midcarpal joint at the level of the triquetrohamate joint, ulnar to the ECU tendon. Its entry site is both ulnar and distal to the midcarpal ulnar portal.
• Anatomy: Directly accesses the articulation between the triquetrum and hamate.
• Neurovascular Risks: Branches of the dorsal cutaneous branch of the ulnar nerve are most at risk here.
• Function: A special-use portal for specific pathology localized to the triquetrohamate joint.

Volar Radiocarpal Portals

Volar portals offer unique perspectives, particularly for volar ligamentous pathology and fracture reduction, but they demand extreme caution due to critical neurovascular structures.

1. The Volar Radial Portal (VR)

• Location: Accessed through the floor of the flexor carpi radialis (FCR) tendon sheath, at the level of the proximal wrist crease.
• Anatomy: The FCR tendon is our primary landmark. Anatomic studies have revealed a safe zone free of neurovascular structures, equal to the width of the FCR tendon plus at least 3 mm in all directions. Medial to the FCR, the median nerve and radial artery are at high risk. Laterally, the superficial radial artery branch is a concern.
• Neurovascular Risks: HIGH. The radial artery and median nerve are medial to the FCR. The superficial radial nerve is radial to the FCR. Meticulous, sharp and blunt dissection directly through the FCR tendon sheath is critical.
• Function: Indicated for evaluating the dorsal radiocarpal ligament (DRCL) and the palmar portion of the scapholunate interosseous ligament (SLIL). It provides a clear view of dorsal rim fragments for arthroscopic reduction of intra-articular distal radius fractures.

2. The Volar Ulnar Portal (VU)

• Location: Located underneath the ulnar border of the flexor tendons (specifically the flexor carpi ulnaris, FCU, and flexor digitorum sublimis, FDS) at the level of the proximal wrist crease.
• Anatomy: The interval between the FCU and FDS tendons.
• Neurovascular Risks: HIGH. The ulnar nerve and ulnar artery are immediately radial to the FCU tendon. The palmar cutaneous branch of the ulnar nerve is also vulnerable. Extreme caution and meticulous blunt dissection are mandatory.
• Function: Indicated for visualizing and débriding palmar tears of the lunotriquetral ligament (LTIL). It aids in the repair or débridement of dorsally located TFCC tears, especially when triangulation from dorsal portals is difficult. It also assesses the dorsal radioulnar ligament, the ECU subsheath, and the radial TFCC attachment.

Volar Midcarpal Portals

These are less commonly used but offer unique insights into midcarpal pathology.

1. The Volar Radial Midcarpal Portal

• Location: Uses the same skin incision as the volar radial radiocarpal portal, but the capsular entry point is about 1 cm distal.
• Anatomy: Enters the midcarpal joint, providing a volar perspective of the scaphoid, lunate, capitate, and hamate.
• Neurovascular Risks: Similar to the volar radial portal, the radial artery and median nerve are significant concerns.
• Function: Occasionally used as an accessory portal for visualizing the pal

Additional Intraoperative Imaging & Surgical Steps

REFERENCES

1. Berger RA. Arthroscopic anatomy of the wrist and distal radioulnar joint. Hand Clin 1999;15:393–413.

2. Geissler WB, Freeland AE, Savoie FH, et al. Intracarpal soft-tissue lesions associated with an intra-articular fracture of the distal end of the radius. J Bone Joint Surg Am 1996;78A:357–365.

3. Slutsky DJ. Distal radioulnar joint arthroscopy and the volar ulnar portal. Tech Hand Up Extrem Surg 2007;11:38–44.

4. Slutsky DJ. Arthroscopy portals: volar and dorsal. In Budoff J, Slade JF, Trumble TE, eds. Master’s Techniques in Wrist and Elbow Arthroscopy. Chicago: American Society for Surgery of the Hand, 2006.

5. Slutsky DJ. Clinical applications of volar portals in wrist arthroscopy. Tech Hand Up Extrem Surg 2004;8:229–238.

6. Slutsky DJ. Management of dorsoradiocarpal ligament repairs. J Am Soc Surg Hand 2005;5:167–174.

7. Slutsky DJ. Volar portals in wrist arthroscopy. J Am Soc Surg Hand 2002;2:225–232.

8. Slutsky DJ. Wrist arthroscopy portals. In Slutsky DJ, Nagel DJ, eds. Techniques in Hand and Wrist Arthroscopy. Philadelphia: Elsevier, 2007.

9. Slutsky DJ. Wrist arthroscopy through a volar radial portal. Arthroscopy 2002;18:624–630.

10. Steinberg BD, Plancher KD, Idler RS. Percutaneous Kirschner wire fixation through the snuff box: an anatomic study. J Hand Surg Am 1995;20A:57–62.

11. Viegas SF. Midcarpal arthroscopy: anatomy and portals. Hand Clin 1994;10:577–587.

12. Most of the complications related to use of the dorsal portals are related to injury to the sensory branches of the superficial radial nerve and the dorsal cutaneous branch of the ulnar nerve.

13. The palmar cutaneous branch of the ulnar nerve is at risk with the volar radial portal, although the interposed flexor carpi radialis tendon mitigates this risk.

14. There is no true internervous plane when using the volar ulnar portal; hence, sensory branches of the palmar cutaneous branches of the ulnar nerve or nerve of Henle are always at risk. Thus, proper wound spread technique is paramount.

15. The ulnar neurovascular bundle is also potentially at risk with overzealous retraction or poor portal placement.

16. Venous bleeding, loss of wrist motion (especially forearm supination), complications related to fluid extravasation, and infection are general risks attendant to any arthroscopic procedure.

17. These can be minimized by fastidious surgical technique, aggressive rehabilitation as necessary, and diligent followup in the early postoperative period.