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Bone resorption of the proximal phalanx after tendon pulley reconstruction
Bone Resorption of the Proximal Phalanx After Tendon Pulley Reconstruction Gau-Tyan Lin, MD, Kaohsiung, Taiwan, ROC A 35-year-old male worker sustained a degloving injury of the left hand. An abdominal flap was used for skin coverage. Tenolysis and reconstruction of the A2 pulley was done using a procedure based on the 3-loop technique, which was modified by putting the tendon loop under the extensor apparatus and periosteum. X-ray revealed hourglass-shaped bone resorption around the proximal phalanx, just under the reconstructed pulley. Diaphyseal narrowing remained present in follow-up x-rays obtained 9 and 10 years later. The remodeling of the resorption was poor. Too much pressure may have caused this bone resorption from the shortened pulley and the circulatory deprivation may have been caused by the dissected periosteum and blocking by the surrounding tendon loop. The degloving injury, which also deprived the digits of a blood supply, may have been an additional underlying risk factor. We recommend that future comparative studies of pulley reconstruction take into account mechanical effectiveness as well as force distribution. (J Hand Surg 1999;24A:1323–1326. Copyright © 1999 by the American Society for Surgery of the Hand.) Key words: Bone resorption, pulley, pulley reconstruction, fingers, tendons.
The pulley is an important component of the flexor system of the hand because it prevents bowstringing of the flexor tendon and, with minimal tendon excursion, provides maximum joint motion.1,2 Many surgical techniques used in pulley reconstruction have been described and tested.3–12 In all these reports, with the exception of tendon or pulley rupture, few complications have been mentioned. Two cases of proximal phalangeal fracture after A2 pulley reconstruction have been reported. One of these 2 cases had a previous fracture;13 the other case, occurring in a 9-year-old boy, had no previous From the Department of Orthopedics, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC. Received for publication January 12, 1999; accepted in revised form April 8, 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: Gau-Tyan Lin, MD, Department of Orthopedics, Kaohsiung Medical University, 100 Shi-Chang 1st Rd, Kaohsiung, Taiwan, ROC. Copyright © 1999 by the American Society for Surgery of the Hand 0363-5023/99/24A06-0001$3.00/0
fracture.14 We report an adult case of marked bone resorption without previous fracture after A2 pulley reconstruction.
Case Report A 35-year-old male worker sustained a degloving injury of the left hand. After debridement and amputation of the distal phalanx of the index, middle, and ring fingers, an abdominal flap was used for skin coverage of the middle and ring fingers. The flexor digitorum profundus tendons were cut and retracted into the palm; the flexor digitorum superficialis tendons were intact. The proximal interphalangeal (PIP) joints of the index, middle, and ring fingers were intact, but intramedullary pinning was performed to keep the fingers in an extended position during the pedicle flapping period. The fixation pins were removed after division of the pedicle flap. Because the middle and ring finger flap was bulky, defatting and tenolysis were performed 2 months and 5 months later. The A2 pulleys were opened for tenolysis. Tenolysis was repeated 13 months after the The Journal of Hand Surgery 1323
1324 Gau-Tyan Lin / Bone Resorption After Pulley Reconstruction
injury because the flexor digitorum superficialis tendon had adhered to the surrounding tissue and because the A2 pulley of the middle finger was found to be damaged by repeat surgeries and fibrotic scarring. Reconstruction of the A2 pulley was performed using a procedure based on the 3-loop technique, which was modified by putting the tendon loop under the extensor apparatus and periosteum.10,15 The resulting length of the reconstructed A2 pulley was approximately 47% of the original A2 pulley.
Twenty-seven months after the injury a neurovascular island flap from the index finger was taken and used for sensory reconstruction of the middle finger. The joint motion of the PIP joint improved after tenolysis and pulley reconstruction, but at a follow-up examination 6 years later, the PIP joint motion was found to have gradually reduced, eventually leading to ankylosis. No x-rays were obtained because all previous surgical procedures involved soft tissue reconstruction. Eight years 3 months after the injury, however, an x-ray was obtained to study the
Figure 1. An x-ray obtained 7 years after pulley reconstruction showing hourglass narrowing at the level of the grafted tendon loop.
The Journal of Hand Surgery / Vol. 24A No. 6 November 1999 1325
Figure 2. The stress concentration at the tendon loop reconstructed pulley.
stiffness of the PIP joint, revealing hourglass-shaped bone resorption around the proximal phalanx, just under the reconstructed pulley (Fig. 1). Diaphyseal narrowing remained present in follow-up x-rays obtained 9 and 10 years subsequent to the pulley reconstruction. The remodeling of the resorption was poor.
Discussion Of the procedures used for pulley reconstruction, the around-the-bone techniques used by Bunnell,16 Lister,8 Wray and Weeks,4 Widstrom et al,12 Okutsu et al,10 and Strickland11 may involve some bone resorption. Because pulley reconstruction is a soft tissue procedure and x-ray examination is not usually included as part of the routine examination, however, few reports have mentioned this complication. In one previous report, an x-ray was used to evaluate a fracture of the proximal phalanx.13,14 Even in our case, x-rays were not obtained to check the pulley reconstruction but rather to examine the joint stiffness. Sanger et al13 reported a case of bone resorption in which an A2 pulley reconstruction was performed that encircled a previously fractured, multiply operated proximal phalanx. The bone resorption occurred directly under the pulley, causing the bone to fracture. These investigators postulated that both the
cumulative effect of the multiple procedures on the blood supply to the bone and the abnormal levels of pressure led to resorption of bone and the subsequent fracture. Conolly and Leicester14 reported a case of bone resorption in a fracture occurring in the proximal phalanx of a child following pulley reconstruction. These investigators stated that this complication was probably the result of the inability of the tendon graft to grow and the tightness of the tendon loop. In our case, although there was no growth problem, bone resorption did occur. The original degloving injury in our case deprived the digits of their neurovascular supply, which may have played an important role in the bone resorption, poor remodeling, and destruction of the articular cartilage, resulting in ankylosis of the PIP joint. In a biomechanical study, Lin et al15 reported that only a triple loop around the bone reconstruction could withstand as much load as a normal pulley could withstand before failure. In fact, while no reconstruction can completely restore a normal tendon excursion–joint motion relationship, reconstruction of the A2 and A4 pulleys can restore a closerto-normal relationship than other reconstructions. The A2 pulley is the longest pulley attached to the diaphysis of the proximal phalanx, and the tendon– pulley reaction force is normally distributed along its
1326 Gau-Tyan Lin / Bone Resorption After Pulley Reconstruction
whole length. In tendon loop reconstruction, the resulting length of a reconstructed pulley cannot be compared with the length of a normal pulley. Even using the 3-loop technique in A2 pulley reconstruction, the length is shorter than the normal A2 pulley length.10 The resulting length in our case was approximately 47%. Thus, stress was concentrated at a relatively small area (Fig. 2). The stress added pressure to the bone, causing pressure erosion of the bone, which is a well-documented phenomenon.17 The relatively high pressure often compresses the bone, resulting in bone resorption. Because of this pressure-related bone resorption, future comparative studies of pulley reconstruction should take into account mechanical effectiveness as well as force distribution. Bone resorption caused by the grafted tendon was observed in this study, but the mechanism remains unclear. The physical effects, biological influences, and changes of local growth factors need further investigation.
References 1. Peterson WW, Manske PR, Bollinger BA, Lesker PA, McCarthy JA. Effect of pulley excision on flexor tendon biomechanics. J Orthop Res 1986;4:96 –101. 2. Lin G-T, Amadio PC, An K-N, Cooney WP. Functional anatomy of the human digital flexor pulley system. J Hand Surg 1989;14:949 –956. 3. Cleveland M. Restoration of the digital portion of a flexor tendon and sheath in the hand. J Bone Joint Surg 1933;15: 762–765. 4. Wray RC Jr, Weeks PM. Reconstruction of digital pulleys. Plast Reconstr Surg 1974;53:534 –536.
5. Doyle JR, Blythe W. The finger flexor tendon sheath and pulleys: anatomy and reconstruction. In: American Academy of Orthopaedic Surgeons. Symposium on tendon surgery in the hand. St Louis: CV Mosby, 1975:81– 87. 6. Michon J, Merle M. Confection d’une poulie artificielle pour fle´chisseur. Ann Chir 1977;31:358. 7. Kleinert HE, Bennett JB. Digital pulley reconstruction employing the always present rim of the previous pulley. J Hand Surg 1978;3:297–298. 8. Lister GD. Reconstruction of pulleys employing extensor retinaculum. J Hand Surg 1979;4:461– 464. 9. Karev A. The “belt loop” technique for the reconstruction of pulleys in the first stage of flexor tendon grafting. J Hand Surg 1984;9A:923–924. 10. Okutsu I, Ninomiya S, Hiraki S, Inanami H, Kuroshima N. Three-loop technique for A2 pulley reconstruction. J Hand Surg 1987;12A:790 –794. 11. Strickland JW. Flexor tendon injuries. Part 4. Staged flexor tendon reconstruction and restoration of the flexor pulley. Orthop Rev 1987;16:78 –90. 12. Widstrom CJ, Johnson G, Doyle JR, Manske PR, Inhofe P. A mechanical study of six digital pulley reconstruction techniques: part I. Mechanical effectiveness. J Hand Surg 1989;14A:821– 825. 13. Sanger JR, Buebendorf ND, Matloub HS, Yousif NJ. Proximal phalangeal fracture after tendon pulley reconstruction. J Hand Surg 1990;15A:976 –979. 14. Conolly WB, Leicester AW. Fracture of the proximal phalanx: an unusual complication of pulley reconstruction in a child. J Hand Surg 1992;17B:420 – 421. 15. Lin G-T, Amadio PC, An K-N, Cooney WP, Chao EYS. Biomechanical analysis of finger flexor pulley reconstruction. J Hand Surg 1989;14B:278 –282. 16. Boyes JH. Bunnell’s surgery of the hand. 5th ed. Philadelphia: JB Lippincott, 1970:403– 404. 17. Monsees B, Murphy WA. Pressure erosions: a pattern of bone resorption in rheumatoid arthritis. Arthritis Rheum 1985;28:820 – 824.
The pulley is an important component of the flexor system of the hand because it prevents bowstringing of the flexor tendon and, with minimal tendon excursion, provides maximum joint motion.1,2 Many surgical techniques used in pulley reconstruction have been described and tested.3–12 In all these reports, with the exception of tendon or pulley rupture, few complications have been mentioned. Two cases of proximal phalangeal fracture after A2 pulley reconstruction have been reported. One of these 2 cases had a previous fracture;13 the other case, occurring in a 9-year-old boy, had no previous From the Department of Orthopedics, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC. Received for publication January 12, 1999; accepted in revised form April 8, 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: Gau-Tyan Lin, MD, Department of Orthopedics, Kaohsiung Medical University, 100 Shi-Chang 1st Rd, Kaohsiung, Taiwan, ROC. Copyright © 1999 by the American Society for Surgery of the Hand 0363-5023/99/24A06-0001$3.00/0
fracture.14 We report an adult case of marked bone resorption without previous fracture after A2 pulley reconstruction.
Case Report A 35-year-old male worker sustained a degloving injury of the left hand. After debridement and amputation of the distal phalanx of the index, middle, and ring fingers, an abdominal flap was used for skin coverage of the middle and ring fingers. The flexor digitorum profundus tendons were cut and retracted into the palm; the flexor digitorum superficialis tendons were intact. The proximal interphalangeal (PIP) joints of the index, middle, and ring fingers were intact, but intramedullary pinning was performed to keep the fingers in an extended position during the pedicle flapping period. The fixation pins were removed after division of the pedicle flap. Because the middle and ring finger flap was bulky, defatting and tenolysis were performed 2 months and 5 months later. The A2 pulleys were opened for tenolysis. Tenolysis was repeated 13 months after the The Journal of Hand Surgery 1323
1324 Gau-Tyan Lin / Bone Resorption After Pulley Reconstruction
injury because the flexor digitorum superficialis tendon had adhered to the surrounding tissue and because the A2 pulley of the middle finger was found to be damaged by repeat surgeries and fibrotic scarring. Reconstruction of the A2 pulley was performed using a procedure based on the 3-loop technique, which was modified by putting the tendon loop under the extensor apparatus and periosteum.10,15 The resulting length of the reconstructed A2 pulley was approximately 47% of the original A2 pulley.
Twenty-seven months after the injury a neurovascular island flap from the index finger was taken and used for sensory reconstruction of the middle finger. The joint motion of the PIP joint improved after tenolysis and pulley reconstruction, but at a follow-up examination 6 years later, the PIP joint motion was found to have gradually reduced, eventually leading to ankylosis. No x-rays were obtained because all previous surgical procedures involved soft tissue reconstruction. Eight years 3 months after the injury, however, an x-ray was obtained to study the
Figure 1. An x-ray obtained 7 years after pulley reconstruction showing hourglass narrowing at the level of the grafted tendon loop.
The Journal of Hand Surgery / Vol. 24A No. 6 November 1999 1325
Figure 2. The stress concentration at the tendon loop reconstructed pulley.
stiffness of the PIP joint, revealing hourglass-shaped bone resorption around the proximal phalanx, just under the reconstructed pulley (Fig. 1). Diaphyseal narrowing remained present in follow-up x-rays obtained 9 and 10 years subsequent to the pulley reconstruction. The remodeling of the resorption was poor.
Discussion Of the procedures used for pulley reconstruction, the around-the-bone techniques used by Bunnell,16 Lister,8 Wray and Weeks,4 Widstrom et al,12 Okutsu et al,10 and Strickland11 may involve some bone resorption. Because pulley reconstruction is a soft tissue procedure and x-ray examination is not usually included as part of the routine examination, however, few reports have mentioned this complication. In one previous report, an x-ray was used to evaluate a fracture of the proximal phalanx.13,14 Even in our case, x-rays were not obtained to check the pulley reconstruction but rather to examine the joint stiffness. Sanger et al13 reported a case of bone resorption in which an A2 pulley reconstruction was performed that encircled a previously fractured, multiply operated proximal phalanx. The bone resorption occurred directly under the pulley, causing the bone to fracture. These investigators postulated that both the
cumulative effect of the multiple procedures on the blood supply to the bone and the abnormal levels of pressure led to resorption of bone and the subsequent fracture. Conolly and Leicester14 reported a case of bone resorption in a fracture occurring in the proximal phalanx of a child following pulley reconstruction. These investigators stated that this complication was probably the result of the inability of the tendon graft to grow and the tightness of the tendon loop. In our case, although there was no growth problem, bone resorption did occur. The original degloving injury in our case deprived the digits of their neurovascular supply, which may have played an important role in the bone resorption, poor remodeling, and destruction of the articular cartilage, resulting in ankylosis of the PIP joint. In a biomechanical study, Lin et al15 reported that only a triple loop around the bone reconstruction could withstand as much load as a normal pulley could withstand before failure. In fact, while no reconstruction can completely restore a normal tendon excursion–joint motion relationship, reconstruction of the A2 and A4 pulleys can restore a closerto-normal relationship than other reconstructions. The A2 pulley is the longest pulley attached to the diaphysis of the proximal phalanx, and the tendon– pulley reaction force is normally distributed along its
1326 Gau-Tyan Lin / Bone Resorption After Pulley Reconstruction
whole length. In tendon loop reconstruction, the resulting length of a reconstructed pulley cannot be compared with the length of a normal pulley. Even using the 3-loop technique in A2 pulley reconstruction, the length is shorter than the normal A2 pulley length.10 The resulting length in our case was approximately 47%. Thus, stress was concentrated at a relatively small area (Fig. 2). The stress added pressure to the bone, causing pressure erosion of the bone, which is a well-documented phenomenon.17 The relatively high pressure often compresses the bone, resulting in bone resorption. Because of this pressure-related bone resorption, future comparative studies of pulley reconstruction should take into account mechanical effectiveness as well as force distribution. Bone resorption caused by the grafted tendon was observed in this study, but the mechanism remains unclear. The physical effects, biological influences, and changes of local growth factors need further investigation.
References 1. Peterson WW, Manske PR, Bollinger BA, Lesker PA, McCarthy JA. Effect of pulley excision on flexor tendon biomechanics. J Orthop Res 1986;4:96 –101. 2. Lin G-T, Amadio PC, An K-N, Cooney WP. Functional anatomy of the human digital flexor pulley system. J Hand Surg 1989;14:949 –956. 3. Cleveland M. Restoration of the digital portion of a flexor tendon and sheath in the hand. J Bone Joint Surg 1933;15: 762–765. 4. Wray RC Jr, Weeks PM. Reconstruction of digital pulleys. Plast Reconstr Surg 1974;53:534 –536.
5. Doyle JR, Blythe W. The finger flexor tendon sheath and pulleys: anatomy and reconstruction. In: American Academy of Orthopaedic Surgeons. Symposium on tendon surgery in the hand. St Louis: CV Mosby, 1975:81– 87. 6. Michon J, Merle M. Confection d’une poulie artificielle pour fle´chisseur. Ann Chir 1977;31:358. 7. Kleinert HE, Bennett JB. Digital pulley reconstruction employing the always present rim of the previous pulley. J Hand Surg 1978;3:297–298. 8. Lister GD. Reconstruction of pulleys employing extensor retinaculum. J Hand Surg 1979;4:461– 464. 9. Karev A. The “belt loop” technique for the reconstruction of pulleys in the first stage of flexor tendon grafting. J Hand Surg 1984;9A:923–924. 10. Okutsu I, Ninomiya S, Hiraki S, Inanami H, Kuroshima N. Three-loop technique for A2 pulley reconstruction. J Hand Surg 1987;12A:790 –794. 11. Strickland JW. Flexor tendon injuries. Part 4. Staged flexor tendon reconstruction and restoration of the flexor pulley. Orthop Rev 1987;16:78 –90. 12. Widstrom CJ, Johnson G, Doyle JR, Manske PR, Inhofe P. A mechanical study of six digital pulley reconstruction techniques: part I. Mechanical effectiveness. J Hand Surg 1989;14A:821– 825. 13. Sanger JR, Buebendorf ND, Matloub HS, Yousif NJ. Proximal phalangeal fracture after tendon pulley reconstruction. J Hand Surg 1990;15A:976 –979. 14. Conolly WB, Leicester AW. Fracture of the proximal phalanx: an unusual complication of pulley reconstruction in a child. J Hand Surg 1992;17B:420 – 421. 15. Lin G-T, Amadio PC, An K-N, Cooney WP, Chao EYS. Biomechanical analysis of finger flexor pulley reconstruction. J Hand Surg 1989;14B:278 –282. 16. Boyes JH. Bunnell’s surgery of the hand. 5th ed. Philadelphia: JB Lippincott, 1970:403– 404. 17. Monsees B, Murphy WA. Pressure erosions: a pattern of bone resorption in rheumatoid arthritis. Arthritis Rheum 1985;28:820 – 824.