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Isolated closed rupture of the bony insertion of the flexor digitorum superficialis tendon: An unusual case
Isolated Closed Rupture of the Bony Insertion of the Flexor Digitorum Superficialis Tendon: An Unusual Case Stephen P. Ferraro, Jr, MD, Robert R. Schenck, MD, Chicago, IL We describe a case of isolated rupture of the flexor digitorum superficialis tendon due to middle phalangeal cortical bone avulsion with a 4-month delay in treatment. X-ray examination revealed an area of calcification in the flexor tendon sheath proximal to the proximal interphalangeal joint. Excision of the bone fragment and surrounding scar tissue corrected nearly all the 60 ~ extension lag at the proximal interphalangeal joint, which was the most notable functional loss. (J Hand Surg 1998;23A:837-839. Copyright 9 1998 by the American Society for Surgery of the Hand.)
Rupture of the flexor tendons, especially in the ring finger, has been well-documented. 1"2 The majority of injuries involve the profundus tendon at its insertion and, less frequently, both superficialis and profundus tendons. 3'4 A review of the literature identified 17 cases of isolated avulsion of the flexor digitorum superficialis primarily involving the dominant ring finger, t'5'6 These ruptures occurred through the tendon insertional fibers or through the tendon, either in its passage through the wrist or, more rarely, at the musculotendinous origin. We report a case of isolated rupture of the flexor digitorum superficialis tendon due to middle phalangeal cortical bone avulsion.
Case Report A 21-year-old right-handed man was involved in an altercation 4 months before presentation. He iniFrom the Departments of Plastic and Orthopaedic Surgery, RushPresbyterian-StLuke's Medical Center, ChicagoIL. Received for publicationJuly 2, 1997; acceptedin April 14, 1998. No benefitsin any formhave been receivedor will be receivedfrom a commercialparty relateddirectlyor indirectlyto the subject of this article. Reprint requests: RobertR. Schenck, MD, ProfessionalBldg, Suite 263, 1725 W HarrisonSt, Chicago, IL 60612. Copyright9 1998by the AmericanSocietyfor Surgeryof the Hand 0363-5023/98/23A05-001553.00/0
tially complained of pain and swelling along the middle phalangeal aspect of the right ring finger. He could not recall the exact mechanism of injury, but did report that grasping and pulling were involved. He sought treatment and was diagnosed with a sprain of the proximal interphalangesl (PIP) joint. The finger was splinted for a short time. The patient did not seek further treatment until he presented to our office 4 months later. Initial x-ray films were not available. Physical examination revealed painless active and passive motion at the PIP joint from 60 ~ to 90 ~ but absence of flexor superficialis function when the other digits were held in extension. The distal interphalangeal joint had normal active and passive range of motion. A solid end point was reached at the limit of extension of PIP motion, without tenderness or instability. Sensation was intact. An x-ray film revealed a 2 X 6 m m oblong area of calcification on the volar aspect of the proximal phalanx with an irregular area of the middle phalangeal volar surface (Fig. 1). Surgical exploration through a palmar incision revealed attenuation of th A2 pulley with slight bowstringing of the flexor tendons. Deeper exposure was gained through opening the flexor tendon sheath between the A2 and A4 pulleys. The area of calcification noted on the x-ray film proved to be a piece of The Journal of Hand Surgery 837
838
Ferraro and Schenck / Flexor Superficialis Tendon Insertion Rupture
Figure 1. Lateral radiograph of the middle finger demonstrating calcification in the flexor sheath.
avulsed cortex at the site of insertion of the flexor superficialis tendon, with scar extending across the PIP joint to the middle phalanx. The bone fragment was even larger than the x-ray film indicated. The fragment measured 3 X 8 x 6 mm, much too large to have simply been calcification from a segment of avulsed periosteum. In fact, the bone fragment had displaced the flexor profundus tendon anteriorly, and with its attached tendon caused a mechanical block to the final 10~ of PIP joint flexion. Both the bone fragment and the surrounding scar tissue in the area of the volar capsule created a 60 ~ extension lag at the same joint. The bone fragment and scar tissue were excised, and the flexor superficialis tendon was allowed to retract into the palm. Capsulotomy and collateral ligament release were necessary to regain full extension. A dynamic extension splint was applied on the first postoperative day. This included an extension block of 15 ~ at the PIP joint to prevent hyperextension following the soft tissue release. The patient was examined regularly and dynamic splinting was continued for 4 weeks, followed by buddy taping. At the final follow-up examination at 3 months, active and passive rage of motion at the PIP joint measured 5 ~ in extension to 100 ~ in flexion, with no evidence of bowstringing.
Discussion The biomechanics of flexor tendon rupture have been examined by Lanzetta and Conolly, 7 leading to conclusions explaining the reason for the ring finger flexor profundus tendon being so commonly involved, particularly the strong intertendinous connections of the middle and little finger profundus tendons converging on the profundus tendon of the ring finger. In 1993, Brand and Hollister 8 described the lever arm and pathomechanics of flexor tendon ruptures, and some of these same forces also may be active on the flexor superficialis tendon as well. To our knowledge, this current case report is the first description of an isolated rupture of a flexor digitorum superficialis tendon due to bone avulsion. The treatment concepts are no different from those used when a bone fracture fragment is not involved. Delay in definitive treatment led to excessive scar tissue formation and flexion contracture at the PIP joint, which also can occur in avulsions without bone involvement. Removal of the offending tendon and attached bone fragment would have restored full flexion function of the digit and prevented secondary contracture, which caused the extension lag of the PIP joint. Indeed, it was the 60 ~ loss of extension and
The Journal of Hand Surgery / Vol. 23A No. 5 September 1998 not the loss o f flexion that caused the real functional deficit in this patient. Ideally, this injury could have been initially better treated b y reattachment o f the superficialis tendon with or without excision o f the b o n y fragment, or by excision o f the b o n y f r a g m e n t together with excision o f a portion o f the distal superficialis tendon if surgical reattachment was not feasible.
References 1. Boyes JH, Wilson JN, Smith JW. Flexor tendon ruptures in the forearm and hand. J Bone Joint Surg 1960;42A:637-646. 2. Carroll RE, Match RM. Avulsion of the flexor profundus insertion. J Trauma 1970; 10:1109-1118.
839
3. Cheung KMC, Chow SP. Closed avulsion of both flexor tendons of the ring finger. J Hand Surg 1995;20B:78-79. 4. Backe H, Posner M. Simultaneous rupture of both flexor tendons in a finger. J Hand Surg 1994;19A:246-248. 5. Gibson C, Manske P. Isolated avulsion of a flexor digitorum superficialis tendon insertion. J Hand Surg 1987;12A:601602. 6. Stern J, Mitra A, Spears J. Isolated avulsion of the flexor digitorum superficialis tendon. J Hand Surg 1995;20A:642644. 7. Lanzetta M, Conolly B. Biomechanical explanationof a simultaneous closed rupture of both flexor tendons in the same digit. Aust N Z J Surg 1996;66:191-194. 8. Brand PW, Hollister A. Clinical mechanics of the hand. St. Louis: Mosby, 1993;21-22, 317-322.
Rupture of the flexor tendons, especially in the ring finger, has been well-documented. 1"2 The majority of injuries involve the profundus tendon at its insertion and, less frequently, both superficialis and profundus tendons. 3'4 A review of the literature identified 17 cases of isolated avulsion of the flexor digitorum superficialis primarily involving the dominant ring finger, t'5'6 These ruptures occurred through the tendon insertional fibers or through the tendon, either in its passage through the wrist or, more rarely, at the musculotendinous origin. We report a case of isolated rupture of the flexor digitorum superficialis tendon due to middle phalangeal cortical bone avulsion.
Case Report A 21-year-old right-handed man was involved in an altercation 4 months before presentation. He iniFrom the Departments of Plastic and Orthopaedic Surgery, RushPresbyterian-StLuke's Medical Center, ChicagoIL. Received for publicationJuly 2, 1997; acceptedin April 14, 1998. No benefitsin any formhave been receivedor will be receivedfrom a commercialparty relateddirectlyor indirectlyto the subject of this article. Reprint requests: RobertR. Schenck, MD, ProfessionalBldg, Suite 263, 1725 W HarrisonSt, Chicago, IL 60612. Copyright9 1998by the AmericanSocietyfor Surgeryof the Hand 0363-5023/98/23A05-001553.00/0
tially complained of pain and swelling along the middle phalangeal aspect of the right ring finger. He could not recall the exact mechanism of injury, but did report that grasping and pulling were involved. He sought treatment and was diagnosed with a sprain of the proximal interphalangesl (PIP) joint. The finger was splinted for a short time. The patient did not seek further treatment until he presented to our office 4 months later. Initial x-ray films were not available. Physical examination revealed painless active and passive motion at the PIP joint from 60 ~ to 90 ~ but absence of flexor superficialis function when the other digits were held in extension. The distal interphalangeal joint had normal active and passive range of motion. A solid end point was reached at the limit of extension of PIP motion, without tenderness or instability. Sensation was intact. An x-ray film revealed a 2 X 6 m m oblong area of calcification on the volar aspect of the proximal phalanx with an irregular area of the middle phalangeal volar surface (Fig. 1). Surgical exploration through a palmar incision revealed attenuation of th A2 pulley with slight bowstringing of the flexor tendons. Deeper exposure was gained through opening the flexor tendon sheath between the A2 and A4 pulleys. The area of calcification noted on the x-ray film proved to be a piece of The Journal of Hand Surgery 837
838
Ferraro and Schenck / Flexor Superficialis Tendon Insertion Rupture
Figure 1. Lateral radiograph of the middle finger demonstrating calcification in the flexor sheath.
avulsed cortex at the site of insertion of the flexor superficialis tendon, with scar extending across the PIP joint to the middle phalanx. The bone fragment was even larger than the x-ray film indicated. The fragment measured 3 X 8 x 6 mm, much too large to have simply been calcification from a segment of avulsed periosteum. In fact, the bone fragment had displaced the flexor profundus tendon anteriorly, and with its attached tendon caused a mechanical block to the final 10~ of PIP joint flexion. Both the bone fragment and the surrounding scar tissue in the area of the volar capsule created a 60 ~ extension lag at the same joint. The bone fragment and scar tissue were excised, and the flexor superficialis tendon was allowed to retract into the palm. Capsulotomy and collateral ligament release were necessary to regain full extension. A dynamic extension splint was applied on the first postoperative day. This included an extension block of 15 ~ at the PIP joint to prevent hyperextension following the soft tissue release. The patient was examined regularly and dynamic splinting was continued for 4 weeks, followed by buddy taping. At the final follow-up examination at 3 months, active and passive rage of motion at the PIP joint measured 5 ~ in extension to 100 ~ in flexion, with no evidence of bowstringing.
Discussion The biomechanics of flexor tendon rupture have been examined by Lanzetta and Conolly, 7 leading to conclusions explaining the reason for the ring finger flexor profundus tendon being so commonly involved, particularly the strong intertendinous connections of the middle and little finger profundus tendons converging on the profundus tendon of the ring finger. In 1993, Brand and Hollister 8 described the lever arm and pathomechanics of flexor tendon ruptures, and some of these same forces also may be active on the flexor superficialis tendon as well. To our knowledge, this current case report is the first description of an isolated rupture of a flexor digitorum superficialis tendon due to bone avulsion. The treatment concepts are no different from those used when a bone fracture fragment is not involved. Delay in definitive treatment led to excessive scar tissue formation and flexion contracture at the PIP joint, which also can occur in avulsions without bone involvement. Removal of the offending tendon and attached bone fragment would have restored full flexion function of the digit and prevented secondary contracture, which caused the extension lag of the PIP joint. Indeed, it was the 60 ~ loss of extension and
The Journal of Hand Surgery / Vol. 23A No. 5 September 1998 not the loss o f flexion that caused the real functional deficit in this patient. Ideally, this injury could have been initially better treated b y reattachment o f the superficialis tendon with or without excision o f the b o n y fragment, or by excision o f the b o n y f r a g m e n t together with excision o f a portion o f the distal superficialis tendon if surgical reattachment was not feasible.
References 1. Boyes JH, Wilson JN, Smith JW. Flexor tendon ruptures in the forearm and hand. J Bone Joint Surg 1960;42A:637-646. 2. Carroll RE, Match RM. Avulsion of the flexor profundus insertion. J Trauma 1970; 10:1109-1118.
839
3. Cheung KMC, Chow SP. Closed avulsion of both flexor tendons of the ring finger. J Hand Surg 1995;20B:78-79. 4. Backe H, Posner M. Simultaneous rupture of both flexor tendons in a finger. J Hand Surg 1994;19A:246-248. 5. Gibson C, Manske P. Isolated avulsion of a flexor digitorum superficialis tendon insertion. J Hand Surg 1987;12A:601602. 6. Stern J, Mitra A, Spears J. Isolated avulsion of the flexor digitorum superficialis tendon. J Hand Surg 1995;20A:642644. 7. Lanzetta M, Conolly B. Biomechanical explanationof a simultaneous closed rupture of both flexor tendons in the same digit. Aust N Z J Surg 1996;66:191-194. 8. Brand PW, Hollister A. Clinical mechanics of the hand. St. Louis: Mosby, 1993;21-22, 317-322.