12 Ruptured Flexor Pollicis Longus Tendon
12.1 Patient History Leading to the Specific Problem
A 49-year-old man presented with missing active flexion of the interphalangeal joint of the left thumb. Three months ago, the patient sustained a palmar cutting injury at the distal proximal phalanx with a hunting knife. A repair of the flexor pollicis longus tendon in T1 zone (Verdan) was performed in an outside department for hand surgery. The patient reported that after splinting for 6 weeks there was no return of active movement of the interphalangeal joint.
12.2 Anatomic Description of the Patient’s Current Status
The flexor pollicis longus tendon not only provides active flexion of the interphalangeal joint of the thumb but also stabilizes the joint together with the antagonistic extensor pollicis longus tendon (▶Fig. 12.1). After chronic rupture, drag of the extensor pollicis tendon outweighs and hyperextension of the joint, often together with painful osteoarthritis in the long term, may result. A feeling of instability of the thumb is common. Furthermore, active flexion of the interphalangeal joint of the thumb is essential for a precise pinch grip. Hence, tendon repair should be preferred instead of arthrodesis or tenodesis of the interphalangeal joint.
In patients with chronic rupture or re-rupture, the proximal part of the tendon retracts and extensive scaring of the tendon stump, slide bearing, and tendon pulleys occurs (▶Fig. 12.2). As a result, simple secondary suture of the tendon is only possible in very rare cases after a few weeks.
Fig. 12.1 Anatomy example. (Reproduced from Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy. General Anatomy and Musculoskeletal System. Illustrations by Voll M and Wesker K. 2nd ed. New York: Thieme Medical Publishers; 2016)
Fig. 12.2 The proximal stump of flexor pollicis longus tendon (white arrow) was retracted up to the carpal tunnel and flipped over. There was extensive scaring. The tendon pulleys were lost.
12.3 Recommended Solution to the Problem
A secondary suture of the shortened and adhered tendon stumps may not be possible after a couple of weeks, but there are several therapeutic options. First, the slide bearing of the tendon must be inspected. If it is destructed, the best option is to insert a silicon rod first that is sutured to the distal stump and lays loose in the carpal tunnel with its rounded end. After 8 weeks of passive motion under the guidance of a physical therapist, a neoformation of the tendon channel can be seen. This should provide adequate tendon gliding, and tendon grafting can be performed. In the presented case, there was a sufficient tendon route for a single-stage procedure. Established techniques for the replacement of the flexor pollicis longus tendon are the transfer of the flexor digitorum superficialis tendon of the ring finger or the interposition of the palmaris longus tendon if there is no atrophy of the muscle motor. Of course, the availability of the palmaris longus tendon has to be checked preoperatively. In the presented case, the use of a functional tendon was rejected by the patient; therefore, the interposition technique was used.
Force transmission of the flexor tendons requires intact tendon pulleys. In several positions, they are indispensable. For sufficient active flexion of the thumb, the Y pulley or the A1 and the A2 pulleys in combination are necessary. In the presented case, a pulley in the Y position was reconstructed. In two-stage cases, the pulley reconstruction should always be performed in the first stage.
Secondary flexor tendon reconstruction is challenging and comes along with a protracted subsequent treatment. Physiotherapy and occupational therapy are necessary for several months. Some patients withdraw these expenses. Arthrodesis of the interphalangeal joint of the thumb and tenodesis of the distal tendon stump connecting it to the distal tendon pulley are alternative options that can be considered in low-demand patients.
12.3.1 Recommended Solution to the Problem
• Inspection of the tendon route with decision for single- or two-stage tendon reconstruction.
• Interposition of the palmaris longus tendon between proximal and distal tendon stumps.
• Reconstruction of a flexor tendon pulley.
12.4 Technique
Operation is performed under regional or general anesthesia with use of a tourniquet with 300 mm HG in a bloodless field. The use of magnifying loupes is mandatory.
A Bruner-type incision is performed; an arteriolysis and a neurolysis of both neurovascular bundles follow. The tendon stumps are identified and tenolysed, and the vital ends are resected sparely. It is usually required to open the carpal tunnel to find the proximal tendon stump. In these cases, a neurolysis of the median nerve is part of the operation. Parts of the flexor retinaculum or of the palmar aponeurosis can be used for reconstruction of a tendon pulley as well as the palmaris longus tendon. The palmaris longus tendon is harvested through an extra incision just proximal of the distal wrist crease using a tendon stripper. It is of utmost importance to distinguish the tendon from the median nerve first. The graft is interposed in the Pulvertaft technique using resorbable sutures. In the presented case, PDS 3–0 (Ethicon, Somerville, New Jersey, United States) was used. Care should be taken that the reconstructed tendon has the appropriate extend of pretension. The thumb should be just a little bit more in flexion compared to its neutral position. It has to be ensured that the interphalangeal joint can be extended fully in the neutral position of the wrist (▶Fig. 12.3).
A diversity of techniques is described for tendon pulley reconstruction. In this case, a strip of the palmar aponeurosis was sutured to remaining parts of the Y pulley with PDS 3–0 sutures. Postoperatively, a dorsal forearm splint is used in mild flexion of the wrist and the thumb. Dynamic treatment starts on the second postoperative day. Additionally, a protection of the reconstructed flexor pulley using a Velcro textile ring is necessary. Full load is not allowed for 12 weeks postoperatively.
12.4.1 Steps for the Procedure
1. Bruner-type incision.
2. Arteriolysis and neurolysis of both neurovascular bundles.
3. Identification and debridement of both tendon stumps.
