Introduction

The past 25 years have been witness to a virtual explosion of interest and application of arthroscopy in the orthopedic surgeon’s armamentarium. Beginning as a diagnostic tool, largely for conditions in large joints such as the knee and shoulder, the arthroscope soon developed into a therapeutic tool for a procedure with well–documented advantages over open procedures. Next, intermediate–size joints (such as the wrist and elbow) became amenable to arthroscopic procedures—due in large part to the reduction in size of arthroscopic tools. This, too, followed the pattern of diagnostic procedures followed by therapeutic applications. With further reduction in the dimensions of arthroscopic equipment, we now have the capability to enter very small joints—such as the carpometacarpal and metacarpophalangeal joints of the hand.¹^–³ Although largely limited to diagnostic procedures, innovations are currently emerging in the use of the arthroscope for therapeutic intervention. Only time will tell if true advantages can be found in the application of arthroscopic technology to these small joints.

As a note of practicality, safety, and integrity, it must be emphasized that common sense must prevail with these techniques. Just because we have the capability to perform small–joint arthroscopy does not mean there is a universal indication that we must do so. In the large number of lectures and courses the author has participated in, and to each of the residents and fellows he has had the privilege to teach, he has stressed (1) how relatively seldom he actually employs arthroscopy in regard to these small joints and (2) the necessity of being convinced that there is a distinct advantage in performing arthroscopy over open procedures before considering using it.

These are decisions each surgeon must ask in an environment of personal honesty, resisting the urge to follow trends and to succumb to pressures from patients who have read about this procedure or the other on the Internet and want what is most modern. If a surgeon can get better results with an open procedure than with an arthroscopic procedure, they owe it to the patient to perform the procedure in the manner that gets the best results or to refer the patient to someone who is getting superior results with the other procedure.

First Carpometacarpal Joint

Arthroscopy of the first carpometacarpal (CMC) joint was developed and described nearly 10 years ago.^1,² The first CMC joint is particularly attractive as a joint available for arthroscopic evaluation because of its relative depth, highly curved articular surfaces, and the nearly circumferential nature of the stabilizing ligaments. Each of these factors makes complete viewing of the joint difficult with arthrotomy, unless highly destructive capsulotomies are carried out through these vital ligaments. As such, the use of the arthroscope was initially proposed for a diagnostic joint evaluation (if nothing more).

Early on it became quite clear, however, that the arthroscope could be a useful tool to help visualize the adequacy of reduction of fractures involving the articular surfaces of the trapezium or the base of the first metacarpal (such as with a Bennett’s fracture)—as well as for the debridement of an arthrotic joint. With miniaturization of thermocouple probes, a technique for an arthroscopically guided shrinkage of the joint capsule for the treatment of pain due to joint capsule laxity was developed—as well as arthroscopically guided arthroplasty for the treatment of end–stage arthrosis.

Indications

The principle indications for arthroscopy of the first CMC joint are, in general, the same as for other joints. These include the evaluation of a painful joint that is suspicious for arthrosis or ligament injury, the treatment of two–part fractures of the base of the first metacarpal, retrieval of floating loose bodies or foreign objects, and the irrigation of a septic joint. There has been a persistent interest in using the arthroscope as a means of performing a minimally invasive resection of arthritic joint surfaces and to facilitate the percutaneous interposition of tendon or other materials.²

Contraindications

The contraindications for arthroscopy of the first CMC joint are the same as for other joints, including poor soft–tissue coverage, active cellulites, and joint injury of such severity that it cannot be managed by percutaneous methods (such as a Rolando fracture).

Regional Anatomy

The skin overlying the first CMC joint is glabrous only on the palmar surface. Immediately deep to the skin and superficial to the deep fascia are numerous veins, including the principal tributaries forming the cephalic vein system. Within the periadventitial tissue of these tributaries are the major volar (S1) and major dorsal (S2) divisions of the superficial radial nerve, which are found just deep to the veins (Figure 27.1).

FIGURE 27.1 Drawing of the regional anatomy of the first carpometacarpal joint (mcI = first metacarpal, Tm = trapezium, Ra = radial artery, EPL = tendon of extensor pollicis longus, APL/EPB = tendons of abductor pollicis longus and extensor pollicis brevis, R and U = radial and ulnar arthroscopic portals, respectively).

Several muscles and tendons cross the joint, beginning anteriorly with the abductor pollicis brevis—which originates from the anterior surface of the trapezium (Figure 27.1). Just lateral to this is the tendon of abductor pollicis longus, inserting into the posterior base of the first metacarpal. The tendon of extensor pollicis brevis passes distally just posterior to the abductor pollicis longus. Just superficial to the posterior joint capsule of the first CMC joint is the deep division of the radial artery, crossing the first CMC joint deep to the extensor pollicis longus tendon before coursing anteriorly between the proximal metaphases of the first and second metacarpals. Between the proximal epiphyses of the first and second metacarpals is the intermetacarpal ligament, which is entirely extracapsular.

Joint Anatomy

The first CMC joint is a bi–sellar—a double saddle joint formed by the distal articular surface of the trapezium and the base of the first metacarpal. The articular surface along the major axis of the trapezium is concave in the medial–lateral direction and the articular surface along the minor axis is convex in the antero–posterior direction. The converse relationship is found with the base of the first metacarpal, where the articular surface is concave in the antero–posterior direction and convex in the medial–lateral direction. Although a joint capsule surrounds the entire joint, only 3/4 is reinforced by capsular ligaments.^4,⁵

The anterior edge of the first CMC joint is reinforced by the anterior oblique ligament (AOL) complex, which is composed of superficial and deep divisions (Figure 27.2). The superficial division (AOLs) spans nearly the entire anterior edge of the joint and attaches to the anterior surface of the trapezium just proximal to the articular surface and just distal to the articular surface of the base of the fist metacarpal. The deep division (AOLd) is a well–demarcated thickening of the superficial band found just medial to the midline of the superficial division.

FIGURE 27.2 Drawing of the anterior surface of the first carpometacarpal joint capsule (I = first metacarpal, II = second metacarpal, Tm = trapezium, S = scaphoid, APL = tendon of abductor pollicis longus, FCR = tendon of flexor carpi radialis, FR = flexor retinaculum, AOL = anterior oblique ligament, UCL = ulnar collateral ligament, IML = intermetacarpal ligament).

Often there is a distinct medial edge separating the AOLd from the AOLs. It is the deep division of the AOL that is often referred to as the “beak” ligament. The orientation of the fibers of the AOLs is slightly oblique, passing proximal to distal from lateral to medial. The fiber orientation of the AOLd is essentially proximal to distal. The extreme lateral (ulnar) surface of the joint is reinforced by the ulnar collateral ligament (UCL), which has fibers oriented in a proximal to distal direction (Figure 27.2). The lateral 30% of the posterior surface of the joint capsule is reinforced by the posterior oblique ligament (POL) (Figure 27.3). The fiber orientation of the POL is slightly oblique, passing from proximal and medial to distal and lateral.

FIGURE 27.3 Drawing of the posterior surface of the first carpometacarpal joint capsule (I = first metacarpal, II = second metacarpal, III = third metacarpal, Tm = trapezium, Td = trapezoid, C = capitate, ECRL = tendon of extensor carpi radialis longus, APL = tendon of abductor pollicis longus, IML = intermetacarpal ligament, POL = posterior oblique ligament, DRL = dorsoradial ligament).

The remaining posterior joint capsule is reinforced by the dorsoradial ligament (DRL) (Figure 27.3). The fiber orientation of the DRL is generally proximal to distal. The joint capsule immediately deep to the tendon of abductor pollicis longus is not reinforced by a ligament. Although there is a distinct border between the AOLs and AOLd, there are no reliable demarcations between the remaining ligaments.