Wrist Arthroscopy – Anatomy, Indications, Contraindication

Wrist arthroscopy has steadily gained prominence as a diagnostic and therapeutic procedure for several wrist and carpal pathologies. Advances in wrist arthroscopy have widened its indications since it was first described in the late 1970s.

Aatomy and Physiology

The anatomy involved with wrist arthroscopy consists of the radiocarpal joint and the ulnocarpal joint. The carpus of the hand is made of 8 bones arranged in 2 rows, proximal and distal. The proximal row is the most involved in wrist arthroscopy and is made of the scaphoid, lunate, triquetrum, and pisiform, in a radial to ulnar direction, respectively. The ulnocarpal joint consists predominantly of the triangular fibrocartilage complex (TFCC). This TFCC consists of ligamentous and fibrocartilaginous structures that aid in the stabilization of the wrist joint.

The standard dorsal radiocarpal portals used in wrist arthroscopy are named and placed in relationship to the dorsal extensor compartments. There are 6 dorsal extensor compartments of the wrist. The first compartment is the most radial and contains extensor pollicis brevis (EPB) tendon and abductor pollicis longus (APL) tendon. The second dorsal compartment contains the extensor carpi radialis brevis (ECRB) tendon and extensor carpi radialis longus (ECRL) tendon. The third compartment courses around Lister’s tubercle on its ulnar side and contains the extensor pollicis longus (EPL) tendon. The fourth extensor compartment contains multiple slips of the extensor digitorum communis (EDC) tendons and the extensor indicis proprius (EIP) tendon. The fifth extensor compartment contains the extensor digiti minimi (EDM) tendon. Finally, the sixth extensor compart is the most ulnar compartment, containing the extensor carpi ulnaris (ECU) tendon.

Indications of Wrist Arthroscopy

Wrist arthroscopy may be implemented for multiple pathologies of the wrist, including diagnostic evaluation of the joint surfaces and ligaments, loose body removal, TFCC pathology, carpal instability, direct visualization of the distal radius, or scaphoid intraarticular fracture reduction, capsulectomy, ganglion excision, and radial styloidectomy.[rx] With advances in wrist arthroscopy, indications continue to grows

Contraindications of Wrist Arthroscopy

Absolute contraindications include active wrist infection for an elective procedure using intraarticular implants such as suture anchors or suture materials and capsular tears that could lead to excessive fluid extravasation. Relative contraindications include bleeding disorders.

Equipment

For wrist arthroscopy, smaller arthroscopic equipment is needed. A 30° arthroscope measuring 2.7 mm or less should be used for visualization. A 70° arthroscope may also be used. Wrist joint distraction is performed using a commercial traction device which is commonly available. It is recommended to use small joint graspers and shavers measuring 3.5 mm or less.[rx] An arthroscopic video monitor, effective light source, and recording equipment are needed.

Personnel

Wrist arthroscopy is to be performed in the operating room suite. As such, it is recommended that general operating room staff should be present, including but not limited to: A single surgeon trained in the procedure, a surgical technician, surgical assistant, circulating nurse, and anesthetist

Preparation

A complete physical exam of the upper extremity is a necessity for appropriate patient selection. Preoperative planning should take place, including preoperative wrist and hand radiographs. Advanced imaging in the form of magnetic resonance imaging (MRI) of the wrist and/or hand, may be useful for the diagnosis of soft tissue injuries treated using wrist arthroscopy.

Appropriate patient selection and screening are necessary. Patients should undergo standardized preoperative testing to ensure it is safe for them to undergo this surgical procedure and be optimized preoperatively.

Technique

Prior to transport to the operative suite, the anesthesia team may elect to perform a regional nerve block for perioperative pain control. General anesthesia is recommended for this type of procedure but can be performed under monitored anesthesia care (MAC).

Once the patient is transported to the operating room, they should be positioned supine with operative extremity on an arm table. For hemostasis, a tourniquet can be used and should be placed as proximal on the operative extremity as possible. The entire upper extremity is prepped and draped in a routine sterile fashion. The traction device with sterilized components can be attached to the operative extremity using finger traps. It is recommended that no more than 10 lbs. of traction used during the procedure.[rx]

To gain access to the wrist joint using dorsal portals, the surgeon should be facing the dorsum of the hand and seated at the patient’s head. For volar portals, the converse is true, and the surgeon should be seated in the axilla facing the volar wrist. The dorsal 3-4 portal is the standard viewing portal and is established first. This portal is between extensor compartments 3 and 4 and is found by palpating the concavity just distal to Lister’s tubercle. A 22-gauge needle is then inserted into this space between EPL and EPC. Using the needle ensures that it is in an intraarticular position. Distend the joint with 5 to 10 ml of normal saline. The needle is then pulled, and using an 11 blade scalpel, and a skin incision is made. Blunt dissection is achieved using a hemostat to avoid iatrogenic injury to sensory nerves and/or extensor tendons. An arthroscopic cannula with trocar is then bluntly punctured through the joint capsule at a 10-degree dorsal-distal to proximal-palmar angle, which accounts for the volar tilt of the distal radius. The blunt trocar is removed, and a 30° 2.7 mm arthroscope is then inserted into the cannula. These steps are repeated to establish the remaining portals.

Following the 3-4 portal, the surgeon may choose to establish an inflow/outflow fluid portal, which is most commonly the 6-U portal. The 6-U denotes placement on the ulnar side of the 6th extensor compartment containing the ECU. This can be done under direct intra-articular visualization with the arthroscope in the 3-4 portal and using an 18 gauge needle inserted just ulnar to the ECU at the level of the joint line.

The 4-5 portal is the next to be established and is generally used as the working portal, located between the 4th and 5th extensor compartment (EDC and EDM). This portal is made by palpating the EDC and rolling your finger to the ulnar border of the compartment. A 22 gauge needle is inserted into the joint under direct visualization in the same manner as the 3-4 portal. The 4-5 portal is approximately 1 cm more proximal than the 3-4 portal due to the decrease in radial height on the ulnar side of the wrist. This portal serves mainly as the working portal and allows visualization of the TFCC.

Establishing the 6-R portal is achieved by palpating the radial edge of the ECU tendon and inserting a 22 gauge needle intra-articularly. Care should be taken when making this portal as not to injure the dorsal sensory branch of the ulnar nerve, which is in close proximity to the 6-R and 6-U portals.[rx]

The 1-2 portal can be made by palpating the dorsum of the anatomic snuffbox and radial to the EPL tendon. It is recommended to place this portal no more than 4.5 mm dorsal to the APL and EPB to reduce the risk of injury to the superficial radial nerve and the radial artery.[rx]

The volar radial sided portal can be made using an inside out technique by placing a blunt trocar or switching stick through the 3-4 portal. The trocar is then gently passed through space between the volar radioscaphocapitate and long radiolunate ligaments until tenting of the skin occurs.[rx][rx] A skin incision is made over the tip of the trocar. This portal can be safely made without damaging the nearby radial artery and the superficial sensory branch of the radial nerve.[rx]

The volar ulnar portal is located ulnar to the flexor tendons of the digits [rx]. A 2 cm longitudinal incision is made at the level of the proximal wrist crease. Flexor tendons are retracted radially, and the flexor carpi ulnaris (FCU) and neurovascular bundle are retracted ulnarly. The radiocarpal joint is identified, and a 22 gauge needle is inserted through the capsule, ensuring appropriate placement.

Once relevant portals are established, the surgeon is then able to perform a various amount of procedures, including extensive debridement, ligament repair, and osseous procedures.

Complications

Wrist arthroscopy rarely results in complications. Thorough knowledge of wrist anatomy is necessary during the portal placement so as not to cause iatrogenic injury to local neurovascular and tendinous structures. Ahsan and colleagues performed a meta-analysis to quantify the overall complication rate of wrist arthroscopy and found it to be 4.8%.[rx] Some of the complications seen were those related to traction and arm position and injury to cutaneous nerves, vascular structures, flexor and extensor tendons, ligaments, and articular cartilage.

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