Other neuromuscular diseases

The Growing Spine: Management of Spinal Disorders in Young Children

Volumn , Issue , 2010, Pages 281-298

  Yaszay, Burt ^a  

^a RADY CHILDREN'S HOSPITAL   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 79959795739     PISSN: None     EISSN: None     Source Type: Book    
DOI: 10.1007/978-3-540-85207-0_22     Document Type: Chapter

References (144)

1. Allen BL Jr, Ferguson RL (1984) The Galveston technique of pelvic fixation with L-rod instrumentation of The spine. Spine 9:388-394
2. Alman BA, Kim HK (1999) Pelvic obliquity after fusion of The spine in Duchenne muscular dystrophy. J Bone Joint Surg Br 81:821-824
3. Alman BA, Raza SN, Biggar WD (2004) Steroid treatment and The development of scoliosis in males with duchenne muscular dystrophy. J Bone Joint Surg Am 86-A:519-524
4. Alper G, Narayanan V (2003) Friedreich's ataxia. Pediatr Neurol 28:335-341
5. Angelini C (2007) The role of corticosteroids in muscular dystrophy: A critical appraisal. Muscle Nerve 36:424-435
6. Aprin H, Bowen JR, MacEwen GD et al (1982) Spine fusion in patients with spinal muscular atrophy. J Bone Joint Surg Am 64:1179-1187
7. Arkader A, Hosalkar H, Dormans JP (2005) Scoliosis correction in an adolescent with a rigid spine syndrome: Case report. Spine 30:E623-E628
8. Aronsson DD, Stokes IA, Ronchetti PJ et al (1994) Comparison of curve shape between children with cerebral palsy, Friedreich's ataxia, and adolescent idiopathic scoliosis. Dev Med Child Neurol 36:412-418
9. Banker BQ (1985) Neuropathologic aspects of arthrogryposis multiplex congenita. Clin Orthop Relat Res 30-43
10. Barnes MJ (2001) Other neuromuscular deformities. In: Weinstein SL (ed) The pediatric spine principles and practice, 2nd edn. Lippincott Williams & Wilkins, Philadelphia
11. Bassett GS, tolo VT (1990) The incidence and natural history of scoliosis in Rett syndrome. Dev Med Child Neurol 32:963-966
12. Beauchamp M, Labelle H, Duhaime M et al (1995) Natural history of muscle weakness in Friedreich's Ataxia and its relation to loss of ambulation. Clin Orthop Relat Res 270-275
13. Bentley G, Haddad F, Bull tM et al (2001) The treatment of scoliosis in muscular dystrophy using modifi ed Luque and Harrington-Luque instrumentation. J Bone Joint Surg Br 83:22-28
14. Bernstein RM (2002) Arthrogryposis and amyoplasia. J Am Acad Orthop Surg 10:417-424
15. Bonnett C, Brown JC, Perry J et al (1975) Evolution of treatment of paralytic scoliosis at Rancho Los Amigos Hospital. J Bone Joint Surg Am 57:206-215
16. Bowen JR, Lipton GE (2001) Spinal muscular atrophy. In: Weinstein SL (ed) The pediatric spine principles and practice, 2nd edn. Lippincott Williams & Wilkins, Philadelphia
17. Bridwell KH, Baldus C, Iffrig tM et al (1999) Process measures and patient/parent evaluation of surgical management of spinal deformities in patients with progressive fl accid neuromuscular scoliosis (Duchenne's muscular dystrophy and spinal muscular atrophy). Spine 24:1300-1309
18. Brook PD, Kennedy JD, Stern LM et al (1996) Spinal fusion in Duchenne's muscular dystrophy. J Pediatr Orthop 16:324-331
19. Brown JC, Zeller JL, Swank SM et al (1989) Surgical and functional results of spine fusion in spinal muscular atrophy. Spine 14:763-770
20. Bunch WH (1975) The Milwaukee brace in paralytic scoliosis. Clin Orthop Relat Res 63-68
21. Burke SW, Jameson VP, Roberts JM et al (1986) Birth fractures in spinal muscular atrophy. J Pediatr Orthop 6:34-36
22. Byers RK, Banker BQ (1961) Infantile muscular atrophy. Arch Neurol 5:140-164
23. Cady RB, Bobechko WP (1984) Incidence, natural history, and treatment of scoliosis in Friedreich's ataxia. J Pediatr Orthop 4:673-676
24. Cahill PJ, Rinella AS, Bielski RJ (2007) Orthopaedic complications of myotubular myopathy. J Pediatr Orthop 27:98-103
25. Cervellati S, Bettini N, Moscato M et al (2004) Surgical treatment of spinal deformities in Duchenne muscular dystrophy: A long term follow-up study. Eur Spine J 13:441-448
26. Chen P, Shen Y (2001) Poliomyelitis scoliosis. In: Weinstein SL (ed) The pediatric spine principles and practice, 2nd edn. Lippincott Williams & Wilkins, Philadelphia
27. Cheuk DK, Wong V, Wraige E et al (2007) Surgery for scoliosis in Duchenne muscular dystrophy. Cochrane Database Syst Rev CD005375
28. Cole JW, Murray DJ, Snider RJ et al (2003) Aprotinin reduces blood loss during spinal surgery in children. Spine 28:2482-2485
29. Daher YH, Lonstein JE, Winter RB et al (1985) Spinal deformities in patients with arthrogryposis. A review oft patients. Spine 10:609-613
30. Daher YH, Lonstein JE, Winter RB et al (1985) Spinal deformities in patients with Friedreich ataxia: A review of J Pediatr Orthop 5:553-557
31. Dewald RL, Ray RD (1970) Skeletal traction for The treatment of severe scoliosis. The University of Illinois halohoop apparatus. J Bone Joint Surg Am 52:233-238
32. Drachman DB, toyka KV, Myer E (1974) Prednisone in Duchenne muscular dystrophy. Lancet 2:1409-1412
33. Dubousset J, Herring JA, Shuffl ebarger H (1989) The crankshaft phenomenon. J Pediatr Orthop 9:541-550
34. Eberle CF (1982) Pelvic obliquity and The unstable hip after poliomyelitis. J Bone Joint Surg Br 64:300-304
35. Eberle CF (1988) Failure of fixation after segmental spinal instrumentation without arthrodesis in The management of paralytic scoliosis. J Bone Joint Surg Am 70:696-703
36. Evans GA, Drennan JC, Russman BS (1981) Functional classifi cation and orthopaedic management of spinal muscular atrophy. J Bone Joint Surg Br 63B:516-522
37. Finsterer J (2006) Cardiopulmonary support in duchenne muscular dystrophy. Lung 184:205-215
38. Flanigan KM, Kerr L, Bromberg MB et al (2000) Congenital muscular dystrophy with rigid spine syndrome: A clinical, pathological, radiological, and genetic study. Ann Neurol 47:152-161
39. Florentino-Pineda I, thompson GH, Poe-Kochert C et al (2004) The effect of amicar on perioperative blood loss in idiopathic scoliosis: The results of a prospective, randomized double-blind study. Spine 29:233-238
40. Fujak A, Ingenhorst A, Heuser K et al (2005) treatment of scoliosis in intermediate spinal muscular atrophy (SMA type II) in childhood. Ortop traumatol Rehabil 7:175-179
41. Gaine WJ, Lim J, Stephenson W et al (2004) Progression of scoliosis after spinal fusion in Duchenne's muscular dystrophy. J Bone Joint Surg Br 86:550-555
42. Galasko CS, Delaney C, Morris P (1992) Spinal stabilisation in Duchenne muscular dystrophy. J Bone Joint Surg Br 74:210-214
43. Gamble JG, Rinsky LA, Lee JH (1988) Orthopaedic aspects of central core disease. J Bone Joint Surg Am 70:1061-1066
44. Gibson DA, Wilkins KE (1975) The management of spinal deformities in Duchenne muscular dystrophy. A new concept of spinal bracing. Clin Orthop Relat Res 41-51
45. Gilchrist JM (2002) Overview of neuromuscular disorders affecting respiratory function. Semin Respir Crit Care Med23:191-200
46. Granata C, Merlini L, Magni E et al (1989) Spinal muscular atrophy: Natural history and orthopaedic treatment of scoliosis. Spine 14:760-762
47. Granata C, Merlini L, Cervellati S et al (1996) Long-term results of spine surgery in Duchenne muscular dystrophy. Neuromuscul Disord 6:61-68
48. Gui L, Savini R, Vicenzi G et al (1976) Surgical treatment of poliomyelitic scoliosis. Ital J Orthop traumatol 2: 191-205
49. Guidera KJ, Borrelli J Jr, Raney E et al (1991) Orthopaedic manifestations of Rett syndrome. J Pediatr Orthop 11:204-208
50. Hahn GV, Mubarak SJ (2001) Muscular dystrophy. In: Weinstein SL (ed) The pediatric spine principles and practice, 2nd edn. Lippincott Williams & Wilkins, Philadelphia
51. Hall JG, Reed SD, Driscoll EP (1983) Part I. Amyoplasia: A common, sporadic condition with congenital contractures. Am J Med Genet 15:571-590
52. Hall JG (1997) Arthrogryposis multiplex congenita: Etiology, genetics, classifi cation, diagnostic approach, and general aspects. J Pediatr Orthop B 6:159-166
53. Hapke EJ, Meek JC, Jacobs J (1972) Pulmonary function in progressive muscular dystrophy. Chest 61:41-47
54. Harding AE (1981) Friedreich's ataxia: A clinical and genetic study of 90 families with an analysis of early diagnostic criteria and intrafamilial clustering of clinical features. Brain 104:589-620
55. Harper CM, Ambler G, Edge G (2004) The prognostic value of pre-operative predicted forced vital capacity in corrective spinal surgery for Duchenne's muscular dystrophy. Anaesthesia 59:1160-1162
56. Harrington PR (1973) The history and development of Harrington instrumentation. Clin Orthop Relat Res 110-112
57. Harrison DJ, Webb PJ (1990) Scoliosis in The Rett syndrome: Natural history and treatment. Brain Dev 12:154-156
58. Heiman-Patterson tD, Natter HM, Rosenberg HR et al (1986) Malignant hyperthermia susceptibility in X-linked muscle dystrophies. Pediatr Neurol 2:356-358
59. Heller KD, Wirtz DC, Siebert CH et al (2001) Spinal stabilization in Duchenne muscular dystrophy: Principles of treatment and record of 31 operative treated cases. J Pediatr Orthop B 10:18-24
60. Herron LD, Westin GW, Dawson EG (1978) Scoliosis in arthrogryposis multiplex congenita. J Bone Joint Surg Am 60:293-299
61. Hsu JD (1983) The natural history of spine curvature progression in The nonambulatory Duchenne muscular dystrophy patient. Spine 8:771-775
62. Iannaccone ST (1998) Spinal muscular atrophy. Semin Neurol 18:19-26
63. Inkley SR, Oldenburg FC, Vignos PJ Jr (1974) Pulmonary function in Duchenne muscular dystrophy related to stage of disease. Am J Med 56:297-306
64. Karol LA (2007) Scoliosis in patients with Duchenne muscular dystrophy. J Bone Joint Surg Am 89 Suppl 1:155-162
65. Kennedy JD, Staples AJ, Brook PD et al (1995) Effect of spinal surgery on lung function in Duchenne muscular dystrophy. thorax 50:1173-1178
66. Keret D, Bassett GS, Bunnell WP et al (1988) Scoliosis in Rett syndrome. J Pediatr Orthop 8:138-142
67. Khoshhal K, Mukhtar I, Clark P et al (2003) Effi cacy of aprotinin in reducing blood loss in spinal fusion for idiopathic scoliosis. J Pediatr Orthop 23:661-664
68. Kinali M, Main M, Eliahoo J et al (2007) Predictive factors for The development of scoliosis in Duchenne muscular dystrophy. Eur J Paediatr Neurol 11:160-166
69. Kunkel LM, Hejtmancik JF, Caskey CT et al (1986) Analysis of deletions in DNA from patients with Becker and Duchenne muscular dystrophy. Nature 322:73-77
70. Kurz LT, Mubarak SJ, Schultz P et al (1983) Correlation of scoliosis and pulmonary function in Duchenne muscular dystrophy. J Pediatr Orthop 3:347-353
71. Labelle H (2001) Spinal deformities in Friedreich's ataxia. In: Weinstein SL (ed) The pediatric spine principles and practice, 2nd edn. Lippincott Williams & Wilkins, Philadelphia
72. Labelle H, tohme S, Duhaime M et al (1986) Natural history of scoliosis in Friedreich's ataxia. J Bone Joint Surg Am 68:564-572
73. Lee DY, Choi IH, Chung CY et al (1997) Fixed pelvic obliquity after poliomyelitis: Classifi cation and management. J Bone Joint Surg Br 79:190-196
74. Lefebvre S, Burglen L, Reboullet S et al (1995) Identifi cation and characterization of a spinal muscular atrophy-determining gene. Cell 80:155-165
75. Lefebvre S, Burlet P, Liu Q et al (1997) Correlation between severity and SMN protein level in spinal muscular atrophy. Nat Genet 16:265-269
76. Leong JC, Wilding K, Mok CK et al (1981) Surgical treatment of scoliosis following poliomyelitis. A review of one hundred and ten cases. J Bone Joint Surg Am 63:726-740
77. Letts M, Rathbone D, Yamashita t et al (1992) Soft Boston orthosis in management of neuromuscular scoliosis: A preliminary report. J Pediatr Orthop 12:470-474
78. Lidstrom J, Stokland E, Hagberg B (1994) Scoliosis in Rett syndrome. Clinical and biological aspects. Spine 19: 1632-1635
79. Lin MC, Liaw MY, Chen WJ et al (2001) Pulmonary function and spinal characteristics: Their relationships in persons with idiopathic and postpoliomyelitic scoliosis. Arch Phys Med Rehabil 82:335-341
80. Linson M, Bresnan M, Eraklis A et al (1981) Acute gastric volvulus following Harrington rod instrumentation in a patient with Werdnig-Hoffman disease. Spine 6:522-523
81. Loder RT, Lee CL, Richards BS (1989) Orthopaedic aspects of Rett syndrome: A multicenter review. J Pediatr Orthop 9:557-562
82. Luque ER (1982) Segmental spinal instrumentation for correction of scoliosis. Clin Orthop Relat Res 192-198
83. Luque ER (1982) The anatomic basis and development of segmental spinal instrumentation. Spine 7:256-259
84. Manzur AY, Kuntzer t, Pike M et al (2004) Glucocorticoid corticosteroids for Duchenne muscular dystrophy. Cochrane Database Syst Rev CD003725
85. Marchesi D, Arlet V, Stricker U et al (1997) Modifi cation of The original Luque technique in The treatment of Duchenne's neuromuscular scoliosis. J Pediatr Orthop 17:743-749
86. Marsh A, Edge G, Lehovsky J (2003) Spinal fusion in patients with Duchenne's muscular dystrophy and a low forced vital capacity. Eur Spine J 12:507-512
87. Martinez BA, Lake BD (1987) Childhood nemaline myopathy: A review of clinical presentation in relation to prognosis. Dev Med Child Neurol 29:815-820
88. Mayer PJ, Dove J, Ditmanson M et al (1981) Postpoliomyelitis paralytic scoliosis. A review of curve patterns and results of surgical treatments in 118 consecutive patients. Spine 6:573-582
89. McCarthy RE, Bruffett WL, McCullough FL (1999) S rod fixation to The sacrum in patients with neuromuscular spinal deformities. Clin Orthop Relat Res 26-31
90. Merlini L, Granata C, Bonfi glioli S et al (1989) Scoliosis in spinal muscular atrophy: Natural history and management. Dev Med Child Neurol 31:501-508
91. Mertz KD, Jost B, Glatzel M et al (2005) Progressive scoliosis in central core disease. Eur Spine J 14:900-905
92. Miles JM, Gilbert-Barness E (1993) Pathological cases of The month. type 1 spinal muscular atrophy (Werdnig-Hoffman disease). Am J Dis Child 147:907-908
93. Miller F, Moseley CF, Koreska J et al (1988) Pulmonary function and scoliosis in Duchenne dystrophy. J Pediatr Orthop 8:133-137
94. Miller RG, Chalmers AC, Dao H et al (1991) The effect of spine fusion on respiratory function in Duchenne muscular dystrophy. Neurology 41:38-40
95. Mubarak SJ, Morin WD, Leach J (1993) Spinal fusion in Duchenne muscular dystrophy-fixation and fusion to The sacropelvis? J Pediatr Orthop 13:752-757
96. Nash CL Jr (1980) Current concepts review: Scoliosis bracing
97. Newton PO, Faro F, Wenger D et al (2006) Neuromuscular scoliosis. In: Herkowitz HN, Garfi n SR, Eismont FJ, Bell GR, Balderston RA (eds) The spine, 5th edn. Saunders Elsevier, Philadelphia
98. Noordeen MH, Haddad FS, Muntoni F et al (1999) Blood loss in Duchenne muscular dystrophy: Vascular smooth muscle dysfunction? J Pediatr Orthop B 8:212-215
99. O'Brien JP, Yau AC, Hodgson AR (1973) Halo pelvic traction: A technic for severe spinal deformities. Clin Orthop Relat Res 179-190
100. O'Brien JP, Dwyer AP, Hodgson AR (1975) Paralytic pelvic obliquity. Its prognosis and management and The development of a technique for full correction of The deformity. J Bone Joint Surg Am 57:626-631
101. O'Brien JP, Yau AC, Gertzbein S et al (1975) Combined staged anterior and posterior correction and fusion of The spine in scoliosis following poliomyelitis. Clin Orthop Relat Res 81-89
102. Oda t, Shimizu N, Yonenobu K et al (1993) Longitudinal study of spinal deformity in Duchenne muscular dystrophy. J Pediatr Orthop 13:478-488
103. Pavon SJ, Manning C (1970) Posterior spinal fusion for scoliosis due to anterior poliomyelitis. J Bone Joint Surg Br 52:420-431
104. Pearn J (1980) Classifi cation of spinal muscular atrophies. Lancet 1:919-922
105. Peelle MW, Lenke LG, Bridwell KH et al (2006) Comparison of pelvic fixation techniques in neuromuscular spinal deformity correction: Galveston rod versus iliac and lumbosacral screws. Spine 31:2392-2398; discussion 2399
106. Phillips DP, Roye DP Jr, Farcy JP et al (1990) Surgical treatment of scoliosis in a spinal muscular atrophy population. Spine 15:942-945
107. Piasecki JO, Mahinpour S, Levine DB (1986) Long-term follow-up of spinal fusion in spinal muscular atrophy. Clin Orthop Relat Res 44-54
108. Ramirez N, Richards BS, Warren PD et al (1997) Complications after posterior spinal fusion in Duchenne's muscular dystrophy. J Pediatr Orthop 17:109-114
109. Reid JM, Appleton PJ (1999) A case of ventricular fibrillation in The prone position during back stabilisation surgery in a boy with Duchenne's muscular dystrophy. Anaesthesia 54:364-367
110. Riddick MF, Winter RB, Lutter LD (1982) Spinal deformities in patients with spinal muscle atrophy: A review of 36 patients. Spine 7:476-483
111. Rideau Y, Glorion B, Delaubier A et al (1984) The treatment of scoliosis in Duchenne muscular dystrophy. Muscle Nerve 7:281-286
112. Roaf R (1956) Paralytic scoliosis. J Bone Joint Surg Br 38-B:640-659
113. Robinson D, Galasko CS, Delaney C et al (1995) Scoliosis and lung function in spinal muscular atrophy. Eur Spine J 4:268-273
114. Russman BS, Melchreit R, Drennan JC (1983) Spinal muscular atrophy: The natural course of disease. Muscle Nerve 6:179-181
115. Russman BS, Iannacone ST, Buncher CR et al (1992) Spinal muscular atrophy: New thoughts on The pathogenesis and classifi cation schema. J Child Neurol 7:347-353
116. Russman BS, Buncher CR, White M et al (1996) Function changes in spinal muscular atrophy II and III. The DCN/SMA Group. Neurology 47:973-976
117. Sabin AB (1985) Oral poliovirus vaccine: History of its development and use and current challenge to eliminate poliomyelitis from The world. J Infect Dis 151:420-436
118. Salk D (1980) Eradication of poliomyelitis in The United States. III. Poliovaccines-practical considerations. Rev Infect Dis 2:258-273
119. Sarwark J, Sarwahi V (2007) New strategies and decision making in The management of neuromuscular scoliosis. Orthop Clin North Am 38:485-496
120. Sarwark JF, MacEwen GD, Scott CI Jr (1990) Amyoplasia (a common form of arthrogryposis). J Bone Joint Surg Am 72:465-469
121. Schwentker EP, Gibson DA (1976) The orthopaedic aspects of spinal muscular atrophy. J Bone Joint Surg Am 58:32-38
122. Seeger BR, Sutherland AD, Clark MS (1984) Orthotic management of scoliosis in Duchenne muscular dystrophy. Arch Phys Med Rehabil 65:83-86
123. Sengupta DK, Mehdian SH, McConnell JR et al (2002) Pelvic or lumbar fixation for The surgical management of scoliosis in duchenne muscular dystrophy. Spine 27: 2072-2079
124. Shapiro F, Bresnan MJ (1982) Orthopaedic management of childhood neuromuscular disease. Part I: Spinal muscular atrophy. J Bone Joint Surg Am 64:785-789
125. Shapiro F, Sethna N, Colan S et al (1992) Spinal fusion in Duchenne muscular dystrophy: A multidisciplinary approach. Muscle Nerve 15:604-614
126. Shapiro F, Specht L (1993) The diagnosis and orthopaedic treatment of inherited muscular diseases of childhood. J Bone Joint Surg Am 75:439-454
127. Shapiro F, Specht L (1993) The diagnosis and orthopaedic treatment of childhood spinal muscular atrophy, peripheral neuropathy, Friedreich ataxia, and arthrogryposis. J Bone Joint Surg Am 75:1699-1714
128. Shapiro F, Sethna N (2004) Blood loss in pediatric spine surgery. Eur Spine J 13(Suppl 1):S6-17
129. Shapiro F, Zurakowski D, Sethna NF (2007) tranexamic acid diminishes intraoperative blood loss and transfusion in spinal fusions for duchenne muscular dystrophy scoliosis. Spine 32:2278-2283
130. Smith AD, Koreska J, Moseley CF (1989) Progression of scoliosis in Duchenne muscular dystrophy. J Bone Joint Surg Am 71:1066-1074
131. Smucker JD, Miller F (2001) Crankshaft effect after posterior spinal fusion and unit rod instrumentation in children with cerebral palsy. J Pediatr Orthop 21:108-112
132. Sucato DJ (2007) Spine deformity in spinal muscular atrophy. J Bone Joint Surg Am 89(Suppl 1):148-154
133. Suk SI, Kim JH, Cho KJ et al (2007) Is anterior release necessary in severe scoliosis treated by posterior segmental pedicle screw fixation? Eur Spine J 16:1359-1365
134. Sussman M (2002) Duchenne muscular dystrophy
135. Sussman MD (1984) Advantage of early spinal stabilization and fusion in patients with Duchenne muscular dystrophy. J Pediatr Orthop 4:532-537
136. turturro F, Rocca B, Gumina S et al (2005) Impaired primary hemostasis with normal platelet function in Duchenne muscular dystrophy during highly-invasive spinal surgery. Neuromuscul Disord 15:532-540
137. Velasco MV, Colin AA, Zurakowski D et al (2007) Posterior spinal fusion for scoliosis in duchenne muscular dystrophy diminishes The rate of respiratory decline. Spine 32:459-465
138. Vezain M, Saugier-Veber P, Melki J et al (2007) A sensitive assay for measuring SMN mRNA levels in peripheral blood and in muscle samples of patients affected with spinal muscular atrophy. Eur J Hum Genet 15:1054-1062
139. Wedel DJ (1992) Malignant hyperthermia and neuromuscular disease. Neuromuscul Disord 2:157-164
140. Werner AY, Zumeta GR, Newman RW et al (1951) Comparison of vital capacity in normal and poliomyelitic subjects. J Bone Joint Surg Am 33-A:628-632
141. Wilkins KE, Gibson DA (1976) The patterns of spinal deformity in Duchenne muscular dystrophy. J Bone Joint Surg Am 58:24-32
142. Yamashita t, Kanaya K, Yokogushi K et al (2001) Correlation between progression of spinal deformity and pulmonary function in Duchenne muscular dystrophy. J Pediatr Orthop 21:113-116
143. Yilmaz O, Karaduman A, topaloglu H (2004) Prednisolone therapy in Duchenne muscular dystrophy prolongs ambulation and prevents scoliosis. Eur J Neurol 11:541-544
144. Yingsakmongkol W, Kumar SJ (2000) Scoliosis in arthrogryposis multiplex congenita: Results after nonsurgical and surgical treatment. J Pediatr Orthop 20:656-661