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Split flexor pollicus longus tendon transfer for stabilization of the thumb interphalangeal joint: A cadaveric and clinical study
Split Flexor Pollicus Longus Tendon Transfer for Stabilization of the Thumb Interphalangeal Joint: A Cadaveric and Clinical Study Ann Van Heest, MD, Daniel Hanson, MD, Jen Lee, MD, Fred Wentdorf, MS, James House, MD, Minneapolis, MN The split flexor pollicus longus (FPL) tendon transfer is a surgical technique using the radial half of the FPL tendon rerouted dorsally and inserted into the extensor pollicis longus tendon for correction of Froment’s sign. A cadaveric model was designed to investigate the effects of the split FPL tendon transfer on pinch strength. Pinch strength was compared for extrinsic thumb flexion (1) without the split FPL and (2) with the split FPL, tensioned at 3 different positions (0° flexion, 30° flexion, and 60° flexion). We report the clinical results of key pinch strength using split FPL tendon transfer as part of thumb reconstruction for 12 thumbs in 10 patients at an average follow-up time of 2 years. The cadaveric study showed no significant difference in pinch force between specimens with or without split FPL transfer or when comparing tensioning at 0° versus 30° versus 60°. Froment’s sign was reproduced in all cadavers with pinch activation without split FPL transfer and was eliminated in all specimens after the split FPL transfer. In the clinical portion of this study 12 transfers in 10 patients had an average follow-up pinch strength of 33.7 N (range, 18 – 80 N) and no evidence of Froment’s sign. We conclude that the split FPL tendon transfer is an effective method for correction of Froment’s sign due to intrinsic paralysis of the thumb. (J Hand Surg 1999;24A:1303–1310. Copyright © 1999 by the American Society for Surgery of the Hand.) Key words: Intrinsic tendon transfer, intrinsic paralysis, Froment’s sign, thumb paralysis.
Control of the intercalated bony segments of the thumbs requires balance of the intrinsic and extrinsic muscle forces to provide proper positioning for effective pinch function. To achieve normal pinch function 9 muscles must effectively and appropriately position the 3 joints of the thumb: the carpo-
From the Department of Orthopaedic Surgery, and the Biomechanics Laboratory, University of Minnesota, Minneapolis, MN. Received for publication December 4, 1998; accepted in revised form May 27, 1999. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Ann Van Heest, MD, Department of Orthopaedic Surgery, University of Minnesota, 420 Delaware St SE, Box 492, Minneapolis, MN 55455. Copyright © 1999 by the American Society for Surgery of the Hand 0363-5023/99/24A06-0014$3.00/0
metacarpal joint, the metacarpophalangeal joint, and the interphalangeal (IP) joint. The normal muscle forces controlling these intercalated joints includes 4 extrinsic muscles (flexor pollicis longus [FPL], extensor pollicis longus, abductor pollicis longus, and extensor pollicis brevis) and 5 intrinsic muscles (abductor pollicis brevis, opponens pollicis, adductor pollicis, flexor pollicis brevis, and first dorsal interosseous). The presence of extrinsic motor forces, with loss of appropriate intrinsic balancing forces, can lead to intercalated collapse with IP joint flexion (Froment’s sign) and secondary metacarpophalangeal joint hyperextension (Jeanne’s sign), as shown in Figure 1. Hyperflexion of the IP joint directs external forces to the tip of the thumb, causing loss of use of the wider surface area at the pulp of the thumb (ie, loss of pulp pinch).1 The Journal of Hand Surgery 1303
1304 Van Heest et al / Split FPL Transfer for Froment’s Sign
Figure 1. Loss of adductor muscle stabilization of the thumb proximal phalanx is seen in intrinsic paralysis and leads to hyperflexion of the IP joint (Froment’s sign). With Froment’s sign, the wide surface area of the pulp is not used for key pinch positioning and external forces are concentrated into the small surface area of the tip of the digit.
As described by Mohammed et al,2 the FPL can be split to provide an IP joint tenodesis for patients with intact extrinsic thumb flexion, loss of appropriate intrinsic thumb balance, and resultant positive Froment’s sign. We have termed this procedure the split FPL tendon transfer. Use of the split FPL transfer corrects Froment’s sign and re-establishes pulp pinch positioning. An advantage of split FPL transfer compared with IP joint arthrodesis3,4 is that mobility of the thumb is maintained. The purpose of this study was 2-fold. First, a cadaveric model was designed to investigate the effects of the split FPL tendon transfer on pinch strength. Pinch strength was compared for extrinsic thumb flexion (1) without the split FPL and (2) with the split FPL, tensioned at 3 different positions (0° flexion, 30° flexion, and 60° flexion). Second, this study presents the clinical results of key pinch strength using split FPL tendon transfer in the hand reconstruction for 12 thumbs in 10 patients.
Materials and Methods Cadaveric Study Seven above-elbow fresh-frozen cadavers were used in this study. After thawing, passive range of motion of the thumb was verified to be within normal limits. The limb was then dissected to identify the origin of the FPL. The tendon was dissected off its musculotendinous junction; a locking suture was placed to allow attachment to a handle-mounted forced transducer. The wrist was stabilized in neutral position by 2 Steinmann pins through the second and third web spaces into the radius. The specimen was then placed on a custom-built mounting frame and secured to the frame with an additional Steinmann pin through the midshaft of the radius and the ulna,
holding the forearm in neutral rotation, and the elbow in 90° flexion. Carpometacarpal joint arthrodesis was then simulated with 2 percutaneous pins as previously described for a 1-stage key pinch.5 A second force transducer was placed under the pulp of the thumb. The amount of force necessary to load the FPL tendon to produce 22 N of pinch strength was measured over 5 trials and averaged for the 22-N FPL loading force. A second set of trials were then performed producing 31 N of pinch strength and the average was recorded as the 31-N FPL loading force. A range of 22 to 31 N of pinch force was chosen as these are average pinch forces following reconstruction in the paralytic thumb.2,5,6 The specimen remained in the mounting frame and the split FPL tendon transfer was performed using the technique described below. The transfer was first tensioned so that with FPL activation, the IP joint had 0° flexion. Five repeat trials, first using the 22-N FPL loading force and then the 31-N FPL loading force, were conducted; the resultant pinch strengths were measured and averaged. The split FPL transfer was then retensioned with 30° IP joint flexion. Five repeat trials, first using the 22-N FPL loading force and then the 31-N FPL loading force, were conducted; the resultant pinch forces were recorded and averaged. The split FPL transfer was then retensioned with 60° IP joint flexion. Five repeat trials, first using the 22-N FPL loading force and then the 31-N of FPL loading force, were conducted; the resultant pinch forces were recorded and averaged. The average pinch force generated for 22 and 31 N FPL loading was then compared for (1) without split FPL transfer and (2) with split FPL at 0°, 30°, and 60° of tensioning. Student’s t-test was used for statistical comparison. All measurements were made in pounds with subsequent conversion to newtons (1 lb of force equals 0.2248 N).
Clinical Portion A retrospective chart review was completed for 10 patients who had undergone 12 split FPL tendon transfers as part of their thumb reconstruction. Charts were reviewed for demographics, type of hand reconstruction, and final pinch strength. Eight patients were successfully contacted and re-examined (average follow-up period, 29 months). Two patients were not available for re-examination and data were derived from the charts (average follow-up period, 24 months; range, 6 –36 months). As shown in Table 1, 10 patients underwent thumb intrinsic reconstruction due to spinal cord injury in 8
The Journal of Hand Surgery / Vol. 24A No. 6 November 1999 1305
Table 1. Clinical Demographics Pinch Strength (N)
Patient No.
Age at Time of Surgery (y)
Side
1
32
L
2
32
2
Before Reconstruction
At Follow-Up Examination
Brachial plexopathy
0
40
R
Tetraplegia (OCU 5)
0
18
35
L
Tetraplegia (OCU 4)
0
27
3
19
R
Tetraplegia (OCU 5)
0
31
4
20
R
3
NA
FDS opposition transfer
5
26
L
NA
NA
CMC joint arthrodesis FPL/EPL tenodesis BR to FDS transfer
6
32
R
Congenital absence of intrinsics Congenital spinal cord injury (OCU 2) Tetraplegia (OCU 6)
0
36
7
20
R
Tetraplegia (OCU 5)
0
22
8
29
L
Tetraplegia (OCU 3)
0
31
8
30
R
Tetraplegia (OCU 3)
0
18
9
34
R
Tetraplegia (OCU 6)
0
80
10
26
R
Tetraplegia (OCU 1)
0
NA
ECRL to FDP transfer BR to FPL transfer ECRI to FDS adductor opposition transfer5 EDQ to EPL transfer Lasso digits 2–5 EDC tenodesis Intrinsic tenodesis8 EPL tenodesis CMC joint arthrodesis BR to FPL transfer CMC joint arthrodesis EPL tenodesis EDC tenodesis EPL tenodesis CMC joint arthrodesis Intrinsic tenodesis8 BR to FPL transfer ECRL to FDP transfer CMC joint arthrodesis EPL tenodesis Split FPL transfer BR to ECRB transfer and FPL CMC joint arthrodesis Lasso digits 2–5 Split FPL transfer
Diagnosis (OCU Level)
First Procedure BR to FPL transfer ECRL to FDP 2–5 CMC joint arthrodesis Split FPL transfer EDC tenodesis EPL tenodesis
EPL tenodesis BR to FPL transfer CMC joint arthrodesis BR to EDC transfer EPL and APL tenodesis Split FPL transfer
Second Procedure
ECRL to FDP transfer Pronator teres to FPL transfer BR to FDS adductor opposition transfer5 Split FPL Split FPL transfer MCP joint capsulodesis ECRL to FDP transfer ECRI to FPL transfer Pronator teres to FDS adductor opposition transfer5 Lasso digits 3,4 CMC joint Eaton-Littler stabilization10 Split FPL transfer Split FPL transfer
Split FPL transfer EPL and APL tenodesis
BR to FPL transfer ECRL to FPL transfer Split FPL transfer Split FPL transfer Index Stiles-Bunnel transfer BR to FDP transfer ECRI to FPL transfer Split FPL transfer
OCU, International Spinal Cord Injury Ocula-Cutaneous Level; NA, not available; BR, brachioradialis; ECRL, extensor carpi radialis longus; FDP, flexor digitorim profundus; CMC, carpometacarpal; EDC, extensor digitorim comminus; EPL, extensor pollicis longus; APL, abductor pollicis longus; FDS, flexor digitorim superficialis; ECRI, extensor carpi radialis intermedius (accessory muscle); EDQ, extensor digiti quinti; Lasso, Zancolli FDS lasso9; ECRB, extensor carpi radialis brevis; MCP, metacarpophalangeal.
1306 Van Heest et al / Split FPL Transfer for Froment’s Sign
Figure 2. Surgical technique. (A) Through a zig-zag palmar incision, the radial half of the FPL tendon is detached from its insertion on the distal phalanx. The radial one half is tagged, split longitudinally and delivered through a window in the flexor sheath proximal to the oblique pulley. (B) The radial half of the FPL tendon is passed deep to the neurovascular bundle into a dorsal wound over the proximal phalanx. (Figure continues)
patients, brachial plexopathy in 1, and congenital intrinsic absence in 1. The patients included 8 males and 2 females undergoing surgery at an average age of 29 years. Concomitant and subsequent hand reconstructive procedures are outlined in Table 1. The FPL transfer was performed concomitantly as part of
the original thumb reconstruction in 7 cases and as a secondary procedure in 5 cases. In the tetraplegic hand reconstruction, the split FPL was most commonly combined with the flexor phase.6 The indication for the procedure was diminished thumb pinch with IP joint hyperflexion.
The Journal of Hand Surgery / Vol. 24A No. 6 November 1999 1307
Figure 2. (Continued) (C) The radial half of the FPL tendon is then woven and sutured into the EPL with tensioning appropriate for pulp placement in key pinch position. (D) Schematic drawing for use of the split FPL transfer in the one-stage key pinch reconstruction. EPL, extensor pollicis longus; CMC, carpometacarpal. (Reprinted with permission.7)
Surgical Technique As previously reported,7 through a zig-zag palmar incision, the radial half of the FPL tendon is detached from its insertion on the distal phalanx. The radial half of the tendon is split longitudinally and brought out through a window in the flexor sheath just proximal to the oblique pulley (Fig. 2A). The tendon is passed into a longitudinal incision over the dorsum of the proximal phalanx, deep to the neurovascular bundles. The radial half of the FPL tendon is then passed into the extensor pollicis longus tendon (Fig. 2B). The end of the FPL tendon is passed a second time, and a provisional suture is placed. Tension is
then adjusted so that the thumb pulp can be brought into an effective key pinch position onto the radial side of the index finger over the middle phalanx segment. The end of the split FPL tendon is then sutured at that tension into the extensor pollicis longus tendon (Fig. 2C). The radial half of the FPL tendon can then function as an intrinsic linking the FPL to the extensor mechanism (Fig. 2D).
Results Cadaveric Results This study showed that the pinch generated with the 22-N loading force averaged 22.9 N (range,
1308 Van Heest et al / Split FPL Transfer for Froment’s Sign
Figure 3. (A) Cadaveric specimen with Froment’s sign after FPL activation, shown in the custom-built mounting frame. (B) Cadaveric specimens after split FPL transfer, eliminating Froment’s sign and restoring pulp pinch.
21.9 –24.6 N) without the split FPL transfer and 22.3 N (range, 20.1–23.3 N) with the split FPL transfer. No statistically significant difference was noted between the 2 groups (p 5 .31). The pinch force generated with the 31 N activation force averaged 32.2 N (range, 30.9 –35.3 N) without the split FPL transfer and 31.0 N (range, 28.6 –33.3 N) with the split FPL transfer. No statistically significant difference was noted between the 2 groups (p 5 .06). For both the 22-N FPL activation force and the 31-N FPL activation force, no significant difference in pinch strength was noted between specimens with or without split FPL transfer. Adding the split FPL transfer did not affect pinch
Figure 4. Cadaveric key pinch strength comparing tensioning of the split FPL at 0° (solid bars), 30° (open bars), and 60° (shaded bars) IP joint flexion.
The Journal of Hand Surgery / Vol. 24A No. 6 November 1999 1309
Figure 5. Patient 3. A Brown-Sequard injury pattern preserved normal contralateral motor function. The split FPL transfer as part of reconstruction of the right hand allowed effective pulp pinch for holding the guitar pick and an effective return to guitar playing after surgery.
strength but did improve thumb positioning in all specimens. Froment’s sign was present in all specimens with pinch activation without split FPL transfer (Fig. 3A) and was eliminated in all specimens with the split FPL transfer (Fig. 3B). Jeanne’s sign was not present in the cadaveric specimens. As shown in Figure 4, no significant difference in pinch force was generated with the split FPL transfer comparing tensioning at 0° versus 30° versus 60°. Pulp pinch was preserved at all 3 settings.
Clinical Results Twelve transfers in 10 patients show an average of 33.7 N for postoperative pinch strength (range, 18 – 80 N ), as shown in Table 1. All patients demonstrated an effective pulp pinch with no evidence of Froment’s sign. The split FPL transfer limited IP joint flexion to between 15° and 30° in all patients. All patients had full IP joint extension. No complications were reported. No subsequent thumb rebalancing surgical procedures were necessary. All patients were satisfied with improved thumb position and function (Fig. 5).
Discussion Options for stabilization of the thumb IP joint in intrinsic imbalance posturing includes IP joint ar-
throdesis or nonarthrodesis procedures (pinning, tenodesis). Interphalangeal joint fusion3,4 has a risk of nonunion or repeat surgery, requires the use of internal fixation, and has resultant loss of flexibility. Nonarthrodesis procedures include the split FPL tendon transfer described here. The results of cadaveric and clinical portions of this study confirm previous clinical reports2 that the split FPL transfer can effectively correct Froment’s posture. The effect of this procedure on Jeanne’s sign was not documented. The clinical portion of this study confirms pinch strengths similar to those previously reported for thumb reconstructions in patients with intrinsic loss.5 The tendon transfer procedure offers the advantage of a relatively simple procedure that can be safely tensioned from 0° to 60°, adjusting to the most functional position and maintaining the supple nature of the thumb.
References 1. Brand PW, Hollister A. Clinical mechanics of the hand. 2nd ed. St Louis: Mosby Year Book, 1993:60 –91. 2. Mohammed KD, Rothwell AG, Sinclair SW, Willems SM, Bean AR. Upper-limb surgery for tetraplegia. J Bone Joint Surg 1992;74B:873– 879. 3. Moberg E. Surgical treatment for absent single-hand grip and elbow extension in quadriplegia: principles and pre-
1310 Van Heest et al / Split FPL Transfer for Froment’s Sign
4.
5.
6.
7.
liminary experience. J Bone Joint Surg 1975;57A:196 – 206. Hiersche DL, Waters RL. Interphalangeal fixation of the thumb in Moberg’s key grip procedure. J Hand Surg 1985; 10A:30 –32. House JH, Comadoll J, Dahl AL. One-stage key pinch and release with thumb carpal-metacarpal fusion in tetraplegia. J Hand Surg 1992;17A:530 –538. House JH, Shannon MA. Restoration of strong grasp and lateral pinch in tetraplegia: a comparison of two methods of thumb control in each patient. J Hand Surg 1985;10A: 21–29. House JH, Walsh TE. Two-stage reconstruction of the
tetraplegic hand. In: Strickland JW, ed. Master techniques in orthopedic surgery, The Hand. Philadelphia: LippincottRaven, 1998:229 –277. 8. McCarthy CK, House JH, Van Heest A, Kawiecki JA, Dahl A, Hanson D. Intrinsic balancing in reconstruction of the tetraplegic hand. J Hand Surg 1997;22A:596 – 604. 9. Zancolli E. Structural and dynamic bases of hand surgery. 2nd ed. Philadelphia: JB Lippincott, 1979:105–135. 10. Eaton RG, Lane LB, Littler JW, Keyser JJ. Ligament reconstruction for the painful thumb carpometacarpal joint: a long-term assessment. J Hand Surg 1984;9A: 692– 699.
Control of the intercalated bony segments of the thumbs requires balance of the intrinsic and extrinsic muscle forces to provide proper positioning for effective pinch function. To achieve normal pinch function 9 muscles must effectively and appropriately position the 3 joints of the thumb: the carpo-
From the Department of Orthopaedic Surgery, and the Biomechanics Laboratory, University of Minnesota, Minneapolis, MN. Received for publication December 4, 1998; accepted in revised form May 27, 1999. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Ann Van Heest, MD, Department of Orthopaedic Surgery, University of Minnesota, 420 Delaware St SE, Box 492, Minneapolis, MN 55455. Copyright © 1999 by the American Society for Surgery of the Hand 0363-5023/99/24A06-0014$3.00/0
metacarpal joint, the metacarpophalangeal joint, and the interphalangeal (IP) joint. The normal muscle forces controlling these intercalated joints includes 4 extrinsic muscles (flexor pollicis longus [FPL], extensor pollicis longus, abductor pollicis longus, and extensor pollicis brevis) and 5 intrinsic muscles (abductor pollicis brevis, opponens pollicis, adductor pollicis, flexor pollicis brevis, and first dorsal interosseous). The presence of extrinsic motor forces, with loss of appropriate intrinsic balancing forces, can lead to intercalated collapse with IP joint flexion (Froment’s sign) and secondary metacarpophalangeal joint hyperextension (Jeanne’s sign), as shown in Figure 1. Hyperflexion of the IP joint directs external forces to the tip of the thumb, causing loss of use of the wider surface area at the pulp of the thumb (ie, loss of pulp pinch).1 The Journal of Hand Surgery 1303
1304 Van Heest et al / Split FPL Transfer for Froment’s Sign
Figure 1. Loss of adductor muscle stabilization of the thumb proximal phalanx is seen in intrinsic paralysis and leads to hyperflexion of the IP joint (Froment’s sign). With Froment’s sign, the wide surface area of the pulp is not used for key pinch positioning and external forces are concentrated into the small surface area of the tip of the digit.
As described by Mohammed et al,2 the FPL can be split to provide an IP joint tenodesis for patients with intact extrinsic thumb flexion, loss of appropriate intrinsic thumb balance, and resultant positive Froment’s sign. We have termed this procedure the split FPL tendon transfer. Use of the split FPL transfer corrects Froment’s sign and re-establishes pulp pinch positioning. An advantage of split FPL transfer compared with IP joint arthrodesis3,4 is that mobility of the thumb is maintained. The purpose of this study was 2-fold. First, a cadaveric model was designed to investigate the effects of the split FPL tendon transfer on pinch strength. Pinch strength was compared for extrinsic thumb flexion (1) without the split FPL and (2) with the split FPL, tensioned at 3 different positions (0° flexion, 30° flexion, and 60° flexion). Second, this study presents the clinical results of key pinch strength using split FPL tendon transfer in the hand reconstruction for 12 thumbs in 10 patients.
Materials and Methods Cadaveric Study Seven above-elbow fresh-frozen cadavers were used in this study. After thawing, passive range of motion of the thumb was verified to be within normal limits. The limb was then dissected to identify the origin of the FPL. The tendon was dissected off its musculotendinous junction; a locking suture was placed to allow attachment to a handle-mounted forced transducer. The wrist was stabilized in neutral position by 2 Steinmann pins through the second and third web spaces into the radius. The specimen was then placed on a custom-built mounting frame and secured to the frame with an additional Steinmann pin through the midshaft of the radius and the ulna,
holding the forearm in neutral rotation, and the elbow in 90° flexion. Carpometacarpal joint arthrodesis was then simulated with 2 percutaneous pins as previously described for a 1-stage key pinch.5 A second force transducer was placed under the pulp of the thumb. The amount of force necessary to load the FPL tendon to produce 22 N of pinch strength was measured over 5 trials and averaged for the 22-N FPL loading force. A second set of trials were then performed producing 31 N of pinch strength and the average was recorded as the 31-N FPL loading force. A range of 22 to 31 N of pinch force was chosen as these are average pinch forces following reconstruction in the paralytic thumb.2,5,6 The specimen remained in the mounting frame and the split FPL tendon transfer was performed using the technique described below. The transfer was first tensioned so that with FPL activation, the IP joint had 0° flexion. Five repeat trials, first using the 22-N FPL loading force and then the 31-N FPL loading force, were conducted; the resultant pinch strengths were measured and averaged. The split FPL transfer was then retensioned with 30° IP joint flexion. Five repeat trials, first using the 22-N FPL loading force and then the 31-N FPL loading force, were conducted; the resultant pinch forces were recorded and averaged. The split FPL transfer was then retensioned with 60° IP joint flexion. Five repeat trials, first using the 22-N FPL loading force and then the 31-N of FPL loading force, were conducted; the resultant pinch forces were recorded and averaged. The average pinch force generated for 22 and 31 N FPL loading was then compared for (1) without split FPL transfer and (2) with split FPL at 0°, 30°, and 60° of tensioning. Student’s t-test was used for statistical comparison. All measurements were made in pounds with subsequent conversion to newtons (1 lb of force equals 0.2248 N).
Clinical Portion A retrospective chart review was completed for 10 patients who had undergone 12 split FPL tendon transfers as part of their thumb reconstruction. Charts were reviewed for demographics, type of hand reconstruction, and final pinch strength. Eight patients were successfully contacted and re-examined (average follow-up period, 29 months). Two patients were not available for re-examination and data were derived from the charts (average follow-up period, 24 months; range, 6 –36 months). As shown in Table 1, 10 patients underwent thumb intrinsic reconstruction due to spinal cord injury in 8
The Journal of Hand Surgery / Vol. 24A No. 6 November 1999 1305
Table 1. Clinical Demographics Pinch Strength (N)
Patient No.
Age at Time of Surgery (y)
Side
1
32
L
2
32
2
Before Reconstruction
At Follow-Up Examination
Brachial plexopathy
0
40
R
Tetraplegia (OCU 5)
0
18
35
L
Tetraplegia (OCU 4)
0
27
3
19
R
Tetraplegia (OCU 5)
0
31
4
20
R
3
NA
FDS opposition transfer
5
26
L
NA
NA
CMC joint arthrodesis FPL/EPL tenodesis BR to FDS transfer
6
32
R
Congenital absence of intrinsics Congenital spinal cord injury (OCU 2) Tetraplegia (OCU 6)
0
36
7
20
R
Tetraplegia (OCU 5)
0
22
8
29
L
Tetraplegia (OCU 3)
0
31
8
30
R
Tetraplegia (OCU 3)
0
18
9
34
R
Tetraplegia (OCU 6)
0
80
10
26
R
Tetraplegia (OCU 1)
0
NA
ECRL to FDP transfer BR to FPL transfer ECRI to FDS adductor opposition transfer5 EDQ to EPL transfer Lasso digits 2–5 EDC tenodesis Intrinsic tenodesis8 EPL tenodesis CMC joint arthrodesis BR to FPL transfer CMC joint arthrodesis EPL tenodesis EDC tenodesis EPL tenodesis CMC joint arthrodesis Intrinsic tenodesis8 BR to FPL transfer ECRL to FDP transfer CMC joint arthrodesis EPL tenodesis Split FPL transfer BR to ECRB transfer and FPL CMC joint arthrodesis Lasso digits 2–5 Split FPL transfer
Diagnosis (OCU Level)
First Procedure BR to FPL transfer ECRL to FDP 2–5 CMC joint arthrodesis Split FPL transfer EDC tenodesis EPL tenodesis
EPL tenodesis BR to FPL transfer CMC joint arthrodesis BR to EDC transfer EPL and APL tenodesis Split FPL transfer
Second Procedure
ECRL to FDP transfer Pronator teres to FPL transfer BR to FDS adductor opposition transfer5 Split FPL Split FPL transfer MCP joint capsulodesis ECRL to FDP transfer ECRI to FPL transfer Pronator teres to FDS adductor opposition transfer5 Lasso digits 3,4 CMC joint Eaton-Littler stabilization10 Split FPL transfer Split FPL transfer
Split FPL transfer EPL and APL tenodesis
BR to FPL transfer ECRL to FPL transfer Split FPL transfer Split FPL transfer Index Stiles-Bunnel transfer BR to FDP transfer ECRI to FPL transfer Split FPL transfer
OCU, International Spinal Cord Injury Ocula-Cutaneous Level; NA, not available; BR, brachioradialis; ECRL, extensor carpi radialis longus; FDP, flexor digitorim profundus; CMC, carpometacarpal; EDC, extensor digitorim comminus; EPL, extensor pollicis longus; APL, abductor pollicis longus; FDS, flexor digitorim superficialis; ECRI, extensor carpi radialis intermedius (accessory muscle); EDQ, extensor digiti quinti; Lasso, Zancolli FDS lasso9; ECRB, extensor carpi radialis brevis; MCP, metacarpophalangeal.
1306 Van Heest et al / Split FPL Transfer for Froment’s Sign
Figure 2. Surgical technique. (A) Through a zig-zag palmar incision, the radial half of the FPL tendon is detached from its insertion on the distal phalanx. The radial one half is tagged, split longitudinally and delivered through a window in the flexor sheath proximal to the oblique pulley. (B) The radial half of the FPL tendon is passed deep to the neurovascular bundle into a dorsal wound over the proximal phalanx. (Figure continues)
patients, brachial plexopathy in 1, and congenital intrinsic absence in 1. The patients included 8 males and 2 females undergoing surgery at an average age of 29 years. Concomitant and subsequent hand reconstructive procedures are outlined in Table 1. The FPL transfer was performed concomitantly as part of
the original thumb reconstruction in 7 cases and as a secondary procedure in 5 cases. In the tetraplegic hand reconstruction, the split FPL was most commonly combined with the flexor phase.6 The indication for the procedure was diminished thumb pinch with IP joint hyperflexion.
The Journal of Hand Surgery / Vol. 24A No. 6 November 1999 1307
Figure 2. (Continued) (C) The radial half of the FPL tendon is then woven and sutured into the EPL with tensioning appropriate for pulp placement in key pinch position. (D) Schematic drawing for use of the split FPL transfer in the one-stage key pinch reconstruction. EPL, extensor pollicis longus; CMC, carpometacarpal. (Reprinted with permission.7)
Surgical Technique As previously reported,7 through a zig-zag palmar incision, the radial half of the FPL tendon is detached from its insertion on the distal phalanx. The radial half of the tendon is split longitudinally and brought out through a window in the flexor sheath just proximal to the oblique pulley (Fig. 2A). The tendon is passed into a longitudinal incision over the dorsum of the proximal phalanx, deep to the neurovascular bundles. The radial half of the FPL tendon is then passed into the extensor pollicis longus tendon (Fig. 2B). The end of the FPL tendon is passed a second time, and a provisional suture is placed. Tension is
then adjusted so that the thumb pulp can be brought into an effective key pinch position onto the radial side of the index finger over the middle phalanx segment. The end of the split FPL tendon is then sutured at that tension into the extensor pollicis longus tendon (Fig. 2C). The radial half of the FPL tendon can then function as an intrinsic linking the FPL to the extensor mechanism (Fig. 2D).
Results Cadaveric Results This study showed that the pinch generated with the 22-N loading force averaged 22.9 N (range,
1308 Van Heest et al / Split FPL Transfer for Froment’s Sign
Figure 3. (A) Cadaveric specimen with Froment’s sign after FPL activation, shown in the custom-built mounting frame. (B) Cadaveric specimens after split FPL transfer, eliminating Froment’s sign and restoring pulp pinch.
21.9 –24.6 N) without the split FPL transfer and 22.3 N (range, 20.1–23.3 N) with the split FPL transfer. No statistically significant difference was noted between the 2 groups (p 5 .31). The pinch force generated with the 31 N activation force averaged 32.2 N (range, 30.9 –35.3 N) without the split FPL transfer and 31.0 N (range, 28.6 –33.3 N) with the split FPL transfer. No statistically significant difference was noted between the 2 groups (p 5 .06). For both the 22-N FPL activation force and the 31-N FPL activation force, no significant difference in pinch strength was noted between specimens with or without split FPL transfer. Adding the split FPL transfer did not affect pinch
Figure 4. Cadaveric key pinch strength comparing tensioning of the split FPL at 0° (solid bars), 30° (open bars), and 60° (shaded bars) IP joint flexion.
The Journal of Hand Surgery / Vol. 24A No. 6 November 1999 1309
Figure 5. Patient 3. A Brown-Sequard injury pattern preserved normal contralateral motor function. The split FPL transfer as part of reconstruction of the right hand allowed effective pulp pinch for holding the guitar pick and an effective return to guitar playing after surgery.
strength but did improve thumb positioning in all specimens. Froment’s sign was present in all specimens with pinch activation without split FPL transfer (Fig. 3A) and was eliminated in all specimens with the split FPL transfer (Fig. 3B). Jeanne’s sign was not present in the cadaveric specimens. As shown in Figure 4, no significant difference in pinch force was generated with the split FPL transfer comparing tensioning at 0° versus 30° versus 60°. Pulp pinch was preserved at all 3 settings.
Clinical Results Twelve transfers in 10 patients show an average of 33.7 N for postoperative pinch strength (range, 18 – 80 N ), as shown in Table 1. All patients demonstrated an effective pulp pinch with no evidence of Froment’s sign. The split FPL transfer limited IP joint flexion to between 15° and 30° in all patients. All patients had full IP joint extension. No complications were reported. No subsequent thumb rebalancing surgical procedures were necessary. All patients were satisfied with improved thumb position and function (Fig. 5).
Discussion Options for stabilization of the thumb IP joint in intrinsic imbalance posturing includes IP joint ar-
throdesis or nonarthrodesis procedures (pinning, tenodesis). Interphalangeal joint fusion3,4 has a risk of nonunion or repeat surgery, requires the use of internal fixation, and has resultant loss of flexibility. Nonarthrodesis procedures include the split FPL tendon transfer described here. The results of cadaveric and clinical portions of this study confirm previous clinical reports2 that the split FPL transfer can effectively correct Froment’s posture. The effect of this procedure on Jeanne’s sign was not documented. The clinical portion of this study confirms pinch strengths similar to those previously reported for thumb reconstructions in patients with intrinsic loss.5 The tendon transfer procedure offers the advantage of a relatively simple procedure that can be safely tensioned from 0° to 60°, adjusting to the most functional position and maintaining the supple nature of the thumb.
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