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Congenital anomaly of the thumb: Aplasia of the flexor pollicis longus
Congenital anomaly of the thumb: Aplasia of the flexor pollicis longus A five-year-old boy, with congenital aplasia of the flexor pollicis longus, without other associated anomalies is reported. A two-stage procedure was done using a silicone rubber rod and pulley reconstruction, followed by transfer of the flexor digitorum superficiaJis tendon from the ring finger to the distal phalanx of the thumb. This resulted in 0/55° active flexion at the interphalangeal joint. (J HAND SURG 1987;12A:108-9.)
Mark R. DeHaan, M.D., Leslie B. Wong, M.D., and David P. Petersen, M.D., Grand Rapids, Mich.
Congenital inability to flex the interphalangeal (IP) joint of the thumb may be due to one of several causes, including congenital absence of the flexor pollicis longus (FPL), anomalous insertion of FPL, congenital tenovaginitis of the flexor tendon sheath, partial anterior interosseous nerve paralysis, traumatic rupture of FPL, or anomalous bands connecting tendons. The absence of FPL has been commonly described in association with other anomalies of the hand. However, aplasia ofFPL, without other associated anomalies of the hand, particularly losses of median nerve innervated structures, is rare. Only four cases that describe this problem are reported in the literature.
Case report A 5-year-old right handed boy was first observed by his parents to be unable to flex his right thumb at the IP joint. The patient had some difficulty with writing and drawing, but performed most tasks with his right hand, without noticeable difficulty. The family history was negative for congenital anomalies. When seen, the patient's right thumb appeared to be slightly smaller in diameter than the left but was of equal
From the Department of Plastic and Reconstructive Surgery, Division of Hand Surgery, Butterworth Hospital, Grand Rapids, Mich. Received for publication July 15, 1985; accepted in revised form April 17, 1986. This article was accepted for publication before July I, 1986. No conflict-of-interest statement was requested from the authors . Reprint requests; Mark R. DeHaan, M.D., Butterworth Hospital, Surgical Education Department, 100 Michigan, N.E., Grand Rap-
ids, MI 49503.
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THE JOURNAL OF HAND SURGERY
length. There were no flexion creases at the IP joint. The IP joint remained in an extended posture at all times. There was no active flexion of the IP joint. Passive range of motion (ROM) of the IP joint was 0/45°. The thenar and forearm muscles were normal in size and function. Key pinch was two pounds on the right side compared with five pounds on the left side. No flexor tendon was palpable over the proximal phalanx. The range of motion (ROM) of all digits and sensibility were normal. X-ray examination showed no skeletal deficiencies.
Surgical findings and reconstruction The thumb was initially explored from the base of the distal phalanx to the distal half of the thenar eminence. There was no evidence of a flexor tendon sheath. The FPL tendon was absent, except for a vestigial tendinous band, which measured 2.0 mm in diameter. This tendinous tissue was attached to the soft tissue and periosteum of the proximal phalanx and inserted into the base of the distal phalanx (Fig. I). Proximally this tissue was bound tightly by a transverse band at the metacarpophalangeal (MP) level and then appeared to fuse with a small anomalous muscle palmar and ulnar to the other thenar muscles. A firststage reconstructive procedure was performed using a No. 3 silicone rubber rod inserted from the proximal end of the distal phalanx into the palm. A strip of extensor retinaculum was used to reconstruct a pulley at the MP joint level. Two months later, the silicone rod was removed. Transfer of the flexor digitorum superficialis (FDS) tendon from the ring finger to the tendinous tissue at the base of the distal phalanx of the thumb was performed. After the transfer, the IP joint of the thumb assumed a posture of 20° flexion, with the wrist in a neutral position.
Vol. 12A, No.1 January 1987
Fig. 1. Vestigial tendinous band proximally attached to anomolous muscle located palmar and ulnar to thenar muscles. Traction did not flex the IP joint.
Results Three weeks after ROM exercises were initiated there was full extension and 0/55° active flexion. Key pinch strength had improved to four pounds on the right side, compared with five pounds on the left and two pounds preoperatively. At 21 months, active ROM was 0/55°, and key pinch strength was 7.5 pounds compared with 7.5 pounds on the left. The patient could perform nail to nail, pulp to pulp, and key pinch (Fig. 2). Discussion The absence of the flexor pollicis longus, which is associated with aplasia of the thenar muscles, was first described by Fromont in 1895 . 1 Since this original observation, the absence of the FPL has commonly been associated with other anomalies of the thumb and thenar muscles. 2-4 Uchida,5 in a recently published report , has proposed a classification of congenital anomalies of the FPL. Absence of the FPL, without any abnormality of the thenar muscles and osseous structures of the thumb, is one of the rarest groups. Only four cases have been previously reported. 50S In these cases, active ROM was restored to the IP joint of the thumb by the transfer of the FDS tendon of the ring finger either as a one- or
Congenital anomaly of thumb
~
109
. .
is 0/55° at the IP joint. Pinch strength is 7.5 pounds .
two-stage procedure. In our case, the two-stage procedure, using a silicone rubber rod and pulley reconstruction, followed by transfer of the FDS tendon of the ring finger yielded an excellent functional result. REFERENCES I. Fromont: Anomalies musculaires multiples de la main, absence due flechisseur prope du pounce . Absence des muscles de le'minence thenar. Lobricaux Supple'mentaris. Bul Soc Anat Paris 70:395-401 , 1895 2. Strauch B, Spinner M: Congenital anomaly of the thumb: Absent intrinsics and flexor pollicis longus. J Bone Joint Surg [Am] 58:115-8, 1976 3. Tsuchida Y, Kasai S, Kojima T: Congenital absence of flexor pollicis longus and flexor pollicis brevis: A case report. Hand 8:294-7, 1976 4 . Paradini AG, Jr: Radial dysplasia. Clin Orthop 57: 15377 , 1968 5. Uchida M, Kojima T, Sakurai N: Congenital absence of flexor pollicis longus without hypoplasia of thenar muscles . Plast Reconstr Surg 75:413-6 . 1985 6. Miura T: Congenital absence of the flexor pollicis longus : A case report. Hand 9:272-4 . 1977 7. Armino JA: Congenital anomaly of the thumb: Absent flexor pollicis longus tendon . J HAND SURG 4:487-8. 1979 8. Koster G: Isolated aplasia of the flexor pollicis longus: A case report. J HAND SURG 9A:870-1, 1984
Mark R. DeHaan, M.D., Leslie B. Wong, M.D., and David P. Petersen, M.D., Grand Rapids, Mich.
Congenital inability to flex the interphalangeal (IP) joint of the thumb may be due to one of several causes, including congenital absence of the flexor pollicis longus (FPL), anomalous insertion of FPL, congenital tenovaginitis of the flexor tendon sheath, partial anterior interosseous nerve paralysis, traumatic rupture of FPL, or anomalous bands connecting tendons. The absence of FPL has been commonly described in association with other anomalies of the hand. However, aplasia ofFPL, without other associated anomalies of the hand, particularly losses of median nerve innervated structures, is rare. Only four cases that describe this problem are reported in the literature.
Case report A 5-year-old right handed boy was first observed by his parents to be unable to flex his right thumb at the IP joint. The patient had some difficulty with writing and drawing, but performed most tasks with his right hand, without noticeable difficulty. The family history was negative for congenital anomalies. When seen, the patient's right thumb appeared to be slightly smaller in diameter than the left but was of equal
From the Department of Plastic and Reconstructive Surgery, Division of Hand Surgery, Butterworth Hospital, Grand Rapids, Mich. Received for publication July 15, 1985; accepted in revised form April 17, 1986. This article was accepted for publication before July I, 1986. No conflict-of-interest statement was requested from the authors . Reprint requests; Mark R. DeHaan, M.D., Butterworth Hospital, Surgical Education Department, 100 Michigan, N.E., Grand Rap-
ids, MI 49503.
108
THE JOURNAL OF HAND SURGERY
length. There were no flexion creases at the IP joint. The IP joint remained in an extended posture at all times. There was no active flexion of the IP joint. Passive range of motion (ROM) of the IP joint was 0/45°. The thenar and forearm muscles were normal in size and function. Key pinch was two pounds on the right side compared with five pounds on the left side. No flexor tendon was palpable over the proximal phalanx. The range of motion (ROM) of all digits and sensibility were normal. X-ray examination showed no skeletal deficiencies.
Surgical findings and reconstruction The thumb was initially explored from the base of the distal phalanx to the distal half of the thenar eminence. There was no evidence of a flexor tendon sheath. The FPL tendon was absent, except for a vestigial tendinous band, which measured 2.0 mm in diameter. This tendinous tissue was attached to the soft tissue and periosteum of the proximal phalanx and inserted into the base of the distal phalanx (Fig. I). Proximally this tissue was bound tightly by a transverse band at the metacarpophalangeal (MP) level and then appeared to fuse with a small anomalous muscle palmar and ulnar to the other thenar muscles. A firststage reconstructive procedure was performed using a No. 3 silicone rubber rod inserted from the proximal end of the distal phalanx into the palm. A strip of extensor retinaculum was used to reconstruct a pulley at the MP joint level. Two months later, the silicone rod was removed. Transfer of the flexor digitorum superficialis (FDS) tendon from the ring finger to the tendinous tissue at the base of the distal phalanx of the thumb was performed. After the transfer, the IP joint of the thumb assumed a posture of 20° flexion, with the wrist in a neutral position.
Vol. 12A, No.1 January 1987
Fig. 1. Vestigial tendinous band proximally attached to anomolous muscle located palmar and ulnar to thenar muscles. Traction did not flex the IP joint.
Results Three weeks after ROM exercises were initiated there was full extension and 0/55° active flexion. Key pinch strength had improved to four pounds on the right side, compared with five pounds on the left and two pounds preoperatively. At 21 months, active ROM was 0/55°, and key pinch strength was 7.5 pounds compared with 7.5 pounds on the left. The patient could perform nail to nail, pulp to pulp, and key pinch (Fig. 2). Discussion The absence of the flexor pollicis longus, which is associated with aplasia of the thenar muscles, was first described by Fromont in 1895 . 1 Since this original observation, the absence of the FPL has commonly been associated with other anomalies of the thumb and thenar muscles. 2-4 Uchida,5 in a recently published report , has proposed a classification of congenital anomalies of the FPL. Absence of the FPL, without any abnormality of the thenar muscles and osseous structures of the thumb, is one of the rarest groups. Only four cases have been previously reported. 50S In these cases, active ROM was restored to the IP joint of the thumb by the transfer of the FDS tendon of the ring finger either as a one- or
Congenital anomaly of thumb
~
109
. .
is 0/55° at the IP joint. Pinch strength is 7.5 pounds .
two-stage procedure. In our case, the two-stage procedure, using a silicone rubber rod and pulley reconstruction, followed by transfer of the FDS tendon of the ring finger yielded an excellent functional result. REFERENCES I. Fromont: Anomalies musculaires multiples de la main, absence due flechisseur prope du pounce . Absence des muscles de le'minence thenar. Lobricaux Supple'mentaris. Bul Soc Anat Paris 70:395-401 , 1895 2. Strauch B, Spinner M: Congenital anomaly of the thumb: Absent intrinsics and flexor pollicis longus. J Bone Joint Surg [Am] 58:115-8, 1976 3. Tsuchida Y, Kasai S, Kojima T: Congenital absence of flexor pollicis longus and flexor pollicis brevis: A case report. Hand 8:294-7, 1976 4 . Paradini AG, Jr: Radial dysplasia. Clin Orthop 57: 15377 , 1968 5. Uchida M, Kojima T, Sakurai N: Congenital absence of flexor pollicis longus without hypoplasia of thenar muscles . Plast Reconstr Surg 75:413-6 . 1985 6. Miura T: Congenital absence of the flexor pollicis longus : A case report. Hand 9:272-4 . 1977 7. Armino JA: Congenital anomaly of the thumb: Absent flexor pollicis longus tendon . J HAND SURG 4:487-8. 1979 8. Koster G: Isolated aplasia of the flexor pollicis longus: A case report. J HAND SURG 9A:870-1, 1984