Hand surface landmarks and measurements in the treatment of trigger thumb

Surgical Treatment for Trigger Thumb Using a Radial Approach

The anatomy of the thumb flexor pulley system and surrounding structures differs from the fingers. The hand's positioning during trigger thumb release is troublesome. Iatrogenic radial digital nerve injuries of the thumb following opened or percutaneous A1 pulley release have been reported. We present the radial approach using a transverse incision for surgical release of the trigger thumb. This surgical approach aimed to restore a familiar surgical hand position, prevent radial digital nerve injury and bowstringing of the flexor pollicis longus, and decrease postoperative pain to facilitate recovery of hand function.

Projection of the A1-Pulley of the Thumb onto Superficial Anatomical Landmarks: An Anatomical Study and a Useful Guide to Surgeons

BACKGROUND

The aim of our study was to project the A1-pulley of the thumb onto the total thumb length to enable its complete division with and without direct sight.

MATERIALS AND METHODS

The study involved 50 hands from adult human cadavers. The proximal and distal borders of the A1-pulley were measured with reference to the first metacarpophalangeal joint (MCPJ). The length of the thumb was defined as the interval between the first carpometacarpal joint (CMCJ) and the apex of the thumb. The length of the pulley is calculated proportionally with reference to the line between the first CMCJ and apex of the thumb.

RESULTS

Approximated by computing 95% confidence intervals, the pulley can be expected to lie in an area between 34.0% (proximal border) and 57.8% (distal border) alongside this line.

CONCLUSION

Percutaneous and minimally-invasive division of the A1-pulley needs to be performed between 34.0 and 57.8% of the length between the first CMCJ and apex of the thumb.

A New Surface Landmark for Thumb Digital Nerve Bifurcation: A Cadaveric Study

PURPOSE

The radial and ulnar thumb digital nerves are critical for tactile sensation and dexterity in the hand. This cadaveric study sought to validate a surface landmark for the bifurcation of the thumb radial digital nerve (RDN) and ulnar digital nerve (UDN).

METHODS

We used 24 fresh-frozen cadaveric specimens for dissections. With the thumb placed in the plane of the palm and fully radially abducted, the index finger metacarpophalangeal joint was flexed to 90°. Then, while keeping the distal interphalangeal joint straight, the proximal interphalangeal joint was flexed until the fingertip contacted the thenar eminence to identify the point of bifurcation. We made a U-shaped incision and identified the bifurcation of the thumb RDN and UDN. The point of bifurcation was measured from the ulnar- and proximal-most aspects of the incision.

RESULTS

The bifurcation of the thumb RDN and UDN was consistently identified within the U in 22 of 24 specimens (92%). In 16 specimens, the index RDN was also identified either trifurcating with the thumb RDN and UDN or branching from a common digital nerve of index RDN and thumb UDN. Most bifurcation points were found directly along the ulnar and proximal edge of the incision. Two specimens contained a bifurcation point 2 mm ulnar to the ulnar limb of the U.

CONCLUSIONS

The bifurcation U is a consistent landmark for the thumb RDN and UDN point of bifurcation. The variable branching patterns in this region confirms the importance of thorough clinical examination with penetrating injuries to the thenar eminence.

CLINICAL RELEVANCE

This surface anatomic landmark for the thumb RDN and UDN bifurcation may aid in preventing iatrogenic injuries during elective procedures and identifying at-risk structures during penetrating injuries to the palm.

Does Bowstringing Affect Hand Function in Patients Treated With A1 Pulley Release for Trigger Fingers?: Comparison Between Percutaneous Versus Open Technique

We aimed to inspect bowstringing after percutaneous and open release of the A1 pulley for trigger digits and its influence on hand function. Sixty-two patients with a resistant trigger digit were randomized to undergo either open release or percutaneous release of the A1 pulley. We quantified bowstringing of the digit using ultrasonography preoperatively and at 12 and 24 weeks after surgery. Pain on a visual analog scale; Disabilities of the Arm, Shoulder, and Hand questionnaire; pinch power; and grip strength were assessed. Bowstringing was significantly increased at 12 weeks after surgery in both groups, and the mean value of the open release group was significantly greater than that of the percutaneous group (2.30 ± 0.58 mm vs 1.46 ± 0.51 mm, respectively; P = 0.035). However, the bowstringing was decreased at 24 weeks without showing significant difference between the 2 groups. The clinical outcomes of each cohort improved significantly, with no difference between the groups at final follow-up. No association was found between bowstringing and any clinical outcome measure. Bowstringing occurred by A1 pulley release with either the percutaneous or open technique does not affect clinical hand function in patients with trigger fingers.

Topographic anatomical landmarks for pulley system of the thumb

PURPOSE

Knowledge of anatomical landmark to pulley system of the thumb is essential in successful treatment of trigger thumb release either by percutaneous or by minimally invasive technique. Though surgical release of trigger thumb is done commonly, there is paucity of data in the literature regarding its surface landmarks. The purpose of this study is to identify palmar surface anatomical landmarks to the pulley system of the thumb.

METHODS

Dissection was performed on 55 fresh frozen adult cadaveric thumbs. The palmar thumb creases were given names as the proximal-proximal crease (PPC) present at the metacarpophalangeal joint, the distal-proximal crease (DPC) over the middle of the proximal phalanx and the distal crease (DC) at interphalangeal joint. The distance between the proximal edges of each pulley to the three thumb creases and longitudinal length of A1, A2, oblique and Av pulley was measured using digital vernier caliper and was expressed in mean and standard deviation.

RESULTS

The proximal edge of A1 pulley was 1.98 ± 1.61 mm proximal to the PPC. The mean longitudinal length of the A1 pulley was measured to be 5.06 ± 0.87 mm, so the distal edge of the A1 pulley was calculated to lie 3.08 mm distal to PPC. The proximal edge of Av and oblique pulley was situated 7.78 ± 2.5 and 15.72 ± 3.22 mm distal to PPC, respectively. The proximal edge of A2 pulley was very nearer and 2.88 ± 1.79 mm proximal to DC.

CONCLUSION

The knowledge of anatomical skin surface landmarks is helpful in the percutaneous release or minimally invasive procedure. The PPC serves as a definite landmark for A1, Av and oblique pulley whereas it is the DC for A2 pulley.

Flexor Tenosynovitis

For patients with suspected flexor tenosynovitis, the mainstay of diagnosis is a thorough history and physical examination. The examination is guided by evaluating the patient for Kanavel's four cardinal signs. Empiric antibiotics should be started immediately on diagnosis covering skin flora and gram-negative bacteria. Typically, surgery is required. Appropriate exposure is required for adequate treatment and incisions should be tailored to preserve areas of skin compromised from draining sinuses and abscess pressure. Diabetes mellitus and peripheral vascular disease place patients at higher risk of poor outcomes including stiffness and amputation; early administration of antibiotics is the intervention that correlates most closely with good outcomes.

Pediatric Trigger Digits

Pediatric trigger thumb presents not at birth but early in childhood. Most evidence suggests that it is caused by a developmental size mismatch between the flexor pollicis longus tendon and its sheath. Patients generally present with the thumb interphalangeal joint locked in flexion. Surgical reviews report near universally excellent outcomes after open release of the A1 pulley. However, recent reports indicate that there may be a role for nonsurgical treatment for families that are willing to wait several years for possible spontaneous resolution of the deformity. Triggering in digits other than the thumb in children is generally associated with an underlying diagnosis including anatomic abnormalities of the tendons, and metabolic, inflammatory, and infectious etiologies. Although some have advocated nonsurgical treatment, surgery is often necessary to address the underlying anatomic etiology. More extensive surgery beyond simple A1 pulley release is often required, including release of the A3 pulley and resection of a slip of the flexor digitorum superficialis tendon.