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The deep palmar spaces of the hand include the midpalmar space, the hypothenar space, the thenar space, space of Parona, and the interdigital web spaces. There are various communications between different spaces. These communications are of clinical importance in explaining the spread of inflammatory, infectious, and even neoplasic processes that involve this region. Surgical incision and drainage of all potentially communicating spaces and compartments is mandatory in deep hand infections. The purpose of this technical note is to describe the minimally invasive approach of endoscopic drainage and debridement of the flexor pollicis longus tendon sheath, radial bursa, and thenar space.
The anatomy of the hand is complex, containing deep spaces, bursae, and tendon sheaths that can harbor infection. The deep palmar spaces of the hand include the midpalmar space, the hypothenar space, the thenar space, space of Parona, and the interdigital web spaces. The midpalmar and thenar spaces are separated by the oblique (vertical midpalmar) septum, which extends from the palmar aspect of the third metacarpal shaft obliquely and radially toward the palmar aponeurosis. The deep midpalmar space communicates with the space of Parona through the carpal tunnel.1 In the normal hand, all of these spaces are potential rather than actual spaces.2 The radial and ulnar bursae are synovium-lined structures localized in the palmocarpal area.3 Communication of the bursae occurs in 50% to 85% of the population.3 Such communication usually occurs through an intermediate bursa between the deepest layer of the ulnar bursa and radial bursa, behind the flexor digitorum profundus tendon of the index finger.3 The radial bursa surrounds the flexor pollicis longus (FPL) tendon and always communicates with the FPL tendon sheath.2, 3 The ulnar bursa surrounds the superficial and deep flexor tendons and communicates with the flexor tendon sheath of the little finger in about 50% to 80% of wrists.2, 3 These communications are of clinical importance in explaining the spread of inflammatory, infectious, and even neoplasic processes that involve this region.3
Hand infections may range from simple cellulitis to deep space abscess, and even to suppurative flexor tenosynovitis.2 The accurate differentiation of these clinical entities is of paramount importance to healing and recovery of function.2 Ultrasonographic study is a useful diagnostic tool. This aids preoperative planning as it determines the extent of the infection and involvement of the potential spaces.2, 4 Deep space hand infections can be caused primarily by direct inoculation of the tendon sheath/bursa or secondarily either through hematogenous spread, the lymphatics, or through pus spreading from adjacent fascial spaces.5, 6, 7 Apart from antibiotic coverage and immobilization with hand elevation, the surgical incision and drainage of all potentially communicating spaces and compartments is mandatory, along with intraoperative irrigation and, sometimes, continuous postoperative irrigation.5 Postoperative early mobilization is mandatory to avoid stiffness.6 Drainage can be performed through a wide or limited approach. Wide incisions allow excellent exposure and debridement. However, a wide approach has the potential complications of flap necrosis and exposure of the tendons or neurovascular structures.6 Another popular treatment method is limited incisions at the proximal and distal ends of the flexor sheath, catheter insertion into one end, and either continuous or intermittent through-and-through irrigation. Extravasation is common with this technique, probably because of sheath erosions or inaccurate catheter placement resulting in digital swelling and stiffness.6 Surgeons advocating the limited approach claim a better final range of motion, whereas others believe that a limited approach should be used in less severe cases.3 In this technical note, we describe the technique of FPL tendoscopy, which allow endoscopic approach to the FPL tendon sheath, the radial bursa, and the thenar space. It is indicated for deep infection or inflammatory disease involving the FPL tendon sheath, the radial bursa, or the thenar space.8 It is contraindicated for infection of the ulnar bursa or the flexor tendon sheaths of the index to little fingers (Table 1).
The patient is in supine position with an arm tourniquet (Zimmer, Warsaw, IN) to provide a bloodless operative field. The surface anatomy of the FPL tendon at the thumb, the flexor retinaculum of the wrist, and the flexor carpi radialis (FCR) tendon just proximal to the flexor retinaculum are marked (Fig 1). A 2.7-mm 30° arthroscope (Henke-Sass Wolf, Tuttlingen, Germany) is used for this procedure. Fluid inflow is by gravity and no arthro-pump is used.
The phalangeal portal is located close to the phalangeal insertion of the FPL tendon and just proximal to the volar interphalangeal crease of the thumb. A 5-mm longitudinal skin incision is made at this point. The subcutaneous tissue is bluntly dissected down to the flexor tendon sheath by means of a hemostat. The tendon sheath is incised to expose the FPL tendon. The wrist portal is located at the ulnar side of the FCR tendon and 1 cm proximal to the proximal edge of the flexor retinaculum. A 1-cm longitudinal skin incision is made at this point. The subcutaneous tissue is bluntly dissected down to the deep fascia. The deep fascia is incised open to expose the FCR tendon. The FCR tendon is retracted radially to expose the FPL tendon and the radial bursa, which are deep and ulnar to the FCR tendon. It is important to notice that the median nerve is at the ulnar side of the incision. Excessive ulnar retraction of the wound should be avoided.
A 2.7-mm Wissinger rod (Richard Wolf, Knittlingen, Germany) is inserted into the FPL tendon sheath via the phalangeal portal. An arthroscopic cannula (Henke-Sass Wolf) is inserted along the rod. The rod is removed and the arthroscope is inserted into the cannula (Fig 2). The rod usually penetrates the tendon sheath and reaches the thenar muscles. The first structures that are viewed through the arthroscope are the thenar muscles. When the arthroscope is retrieved backward, it will go back to the tendon sheath and the FPL can be examined. It is difficult if not impossible to advance the arthroscope proximally along the tendon sheath because of the turn of the FPL tendon at the proximal palm (Fig 3).
A 2.7-mm Wissinger rod (Richard Wolf) is inserted into the radial bursa at the wrist portal and is advanced distally. An arthroscopic cannula (Henke-Sass Wolf) is inserted along the rod. The rod is removed and the arthroscope is inserted into the cannula (Fig 4). The rod usually penetrates the tendon sheath and reaches the thenar space. The first structure in view is the thenar space. While the arthroscope is retrieved backward, it will go back to the tendon sheath and the FPL can be examined (Fig 5). It is difficult if not impossible to advance the arthroscope distally along the tendon sheath because of the turn of the FPL tendon at the proximal palm.
By passive adduction and flexion of the thumb, the proximal phalanx of the thumb, first metacarpal, and radius is in a straight line. However, the phalangeal and wrist portals are still not coaxial in this thumb position (Fig 6). The arthroscope or the arthroscopic shaver cannot overcome the turn of the FPL tendon sheath at the proximal palm when it passes through either the phalangeal or the wrist portal. The instruments via the portals will go to different tissue planes at the proximal palm. The solution is to create a thenar portal over the thenar muscle. The FPL tendon is not palpable at the thenar muscle. The thenar portal should be created by an inside-out method. When the arthroscope via the phalangeal portal reaches the turn of the FHL tendon sheath, the arthroscope is removed, leaving the cannula in situ. The Wissinger rod is inserted into the cannula and the cannula is removed. The rod passes through the thenar muscle and the skin over the tip of the rod is incised to create the thenar portal. This portal can be used as the working portal for the distal portion of the FHL tendon sheath. It is also the viewing portal for the FHL tendon sheath of the proximal palm. The phalangeal and thenar portals are coaxial.
The finger web portal at the second finger web will be the working portal for the thenar space and the radial bursa at the wrist. This is created by an inside-out technique through the wrist portal. The arthroscope is advanced via the thenar space toward the second finger web. The arthroscope is removed leaving the cannula in situ. The Wissinger rod is inserted into the cannula, and the cannula is removed. The rod enters the second finger web and a 5-mm incision is made at the tip of the rod to create the finger web portal (Fig 7). The wrist and finger web portals are coaxial (Video 1, Table 2).
FPL tendoscopy is a minimally invasive approach to the FPL tendon sheath, the radial bursa, and the thenar space. It allows continuous postoperative irrigation with catheters through the portals. If the midpalmar space is infected and distended, it can be approached via the wrist portal. The instrument can reach the midpalmar space via the space of Parona, which is deep to the FPL tendon. The median nerve will not be injured as the path is deep to the flexor tendon and the medial nerve.
The thenar portal is created by the Wissinger rod technique as it is difficult to palpate the FPL tendon within the thenar muscles. Care should be taken not to injure the branch of the median nerve, which supplies the thenar muscles as it passes across the radial bursa, approximately 1 cm distal to the transverse ligament of the wrist.5 Similarly, the interdigital nerve may be injured during establishment of the finger web portal.
The advantages of this technique include small incisions, good cosmetic result, less scar contracture, less stiffness as early mobilization is allowed, and endoscopic debridement of the deep spaces of the radial side of the hand and wrist. The potential risks of this approach include injury to the median nerve and its branches, injury to the interdigital nerve, and spread of infection (Table 3). This is a technically demanding procedure and should be reserved for the experienced hand and wrist arthroscopist.
The author reports that he has no conflicts of interest in the authorship and publication of this article.
Flexor pollicis longus (FPL) tendoscopy of the left hand. The patient is in supine position. The distal portion of the FPL tendon can be examined via the phalangeal portal. The first structure in view is the thenar muscle, and the tendon sheath can be examined by retrieval of the arthroscope. The proximal part of the FPL tendon can be examined via the wrist portal. The first structure in view is the thenar space. The tendon can be examined by retrieval of the arthroscope. The wrist and phalangeal portals are not coaxial and instruments via these 2 portals enter different tissue planes. The finger web and thenar portals can be created inside out via the wrist and phalangeal portals, respectively. The finger web portal is the working portals of the thenar space and is the proximal portion of the radial bursa. The thenar portal is the working portal of the FPL tendon sheath and the distal portion of the radial bursa.