Chapter 22 Arthroscopic Scaphotrapeziotrapezoidal Interposition Arthroplasty



10.1055/b-0035-121132

Chapter 22 Arthroscopic Scaphotrapeziotrapezoidal Interposition Arthroplasty



Introduction


Isolated osteoarthritis of the scaphotrapeziotrapezoidal (STT) joint is rare, but very painful. As a general rule, conservative treatment is used. If this fails, STT fusion is traditionally the next treatment option, but the repercussions for joint mobility are problematic. Isolated resection of the distal tubercle of the scaphoid is another option1; however, secondary collapse can lead to pain recurrence. Interposition arthroplasty avoids this pitfall. Arthroscopic surgery gives the surgeon a better view of the STT joint, which makes it easier to resect the distal tubercle, and postoperative recovery is faster.



Operative Technique



Patient Preparation and Positioning


The procedure is performed under regional anesthesia. The patient’s arm is secured to the table. Upward traction can be placed either on the long fingers or on the thumb alone. If traction is placed on the thumb, only 2 to 3 kg of counterweight is needed and if traction is placed on the long fingers, 5 to 6 kg of counterweight is needed.



Midcarpal Joint Debridement


This procedure requires only a midcarpal joint approach. The ulnar midcarpal (MCU) portal is the most straightforward entrance to the joint. A shaver is introduced through the radial midcarpal (MCR) portal to debride the joint. The scope and shaver positions are then reversed to finish the midcarpal joint debridement.



Scaphotrapeziotrapezoid Joint Exploration


The STT joint can be easily examined with the scope in the MCR portal. From the midcarpal joint, the medial and distal faces of the scaphoid are followed while the scope passes between the scaphoid and the capitate ( Fig. 22.1 ). When the scope reaches the STT joint, the view may be hindered by widespread synovitis. The joint must first be cleaned out through the 1–2 or STT portal. A needle is inserted between the first and second compartments, ~1.5 cm below the trapeziometacarpal joint. Because this joint is straight, the natural angulation of the carpal bones is not a factor as it is when the positions of other portals are determined. The scope is held stationary and used to find the needle tip inside the joint ( Fig. 22.2 ).


A small horizontal incision is made. Mosquito forceps are used to pass through the capsule, and the shaver is inserted into the joint. Synovectomy is performed until the entire joint is completely debrided; any small cartilage fragments are also removed ( Fig. 22.3 ).



Distal Resection of the Scaphoid


A bur is introduced into the 1–2 portal. The tubercle on the distal pole is resected under visual control, starting at its dorsal section and gradually proceeding toward its volar section ( Fig. 22.4a, b ). The resection must be uniform. It is also important to ensure that no bone lip remains, especially on the medial portion against the capitate ( Fig. 22.5 ). When the resection is properly carried out, the scope (2–3 mm), which is still in the MCR portal, can easily be moved into the STT joint. Nevertheless, it is easier to directly inspect the quality of the resection through the 1–2 portal ( Fig. 22.6 ).

Fig. 22.1 Arthroscopic view of the scope moving from the radial midcarpal (MCR) portal into the scaphotrapeziotrapezoidal (STT) joint while passing between the scaphoid on the left and the lateral side of the capitate on the right.
Fig. 22.2 Intraoperative view of the needle in the 1–2 portal being located with the scope‘s transillumination feature.
Fig. 22.3 Arthroscopic view of the scaphotrapeziotrapezoidal (STT) joint after the inflamed synovial tissue has been excised by the shaver; the cartilage on the scaphoid‘s distal facet on the bottom is gone, as is the cartilage on the proximal facets of the trapezoid and trapezium.
Fig. 22.4a, b Drawing (a) and arthroscopic view (b) of the initial burring of the scaphoid’s distal facet.

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Jun 13, 2020 | Posted by in ORTHOPEDIC | Comments Off on Chapter 22 Arthroscopic Scaphotrapeziotrapezoidal Interposition Arthroplasty

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