5,557

Congenital Aplasia of the Patella

Nikolaos K. Sferopoulos

Nikolaos K. Sferopoulos, Department of Pediatric Orthopaedics, “G. Gennimatas” Hospital, Thessaloniki, Greece

Conflict-of-interest statement: The author(s) declare(s) that there is no conflict of interest regarding the publication of this paper.

Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http: //creativecommons.org/licenses/by-nc/4.0/

Correspondence to: Nikolaos K. Sferopoulos, P. Papageorgiou 3, 546 35, Thessaloniki, Greece.
Email: sferopoulos@in.gr, sferopoulos@yahoo.com
Telephone: +302310963270

Received: April 9, 2018
Revised: May 12, 2018
Accepted: May 14, 2018
Published online: May 28, 2018

ABSTRACT

Congenital absence or marked reduction of the patella may exist in association with other congenital anomalies, most likely the nail-patella syndrome and the ischiopatellar dysplasia or as an isolated entity described in only a few families to date. It may also appear in other orthopaedic malformations, such as the congenital dislocation of the knee. A careful physical examination is essential in the diagnosis of the syndrome, which is mainly clinical. The purpose of this review is to present a range of the clinical syndromes that may be associated with aplasia of the patella, in both children and adults, and to review the related literature.

Key words: Congenital patella aplasia; Nail-patella syndrome; Isolated familial patella aplasia; Patellar aplasia; Congenital dislocation of the knee

© 2018 The Author(s). Published by ACT Publishing Group Ltd. All rights reserved.

Sferopoulos NK. Congenital Aplasia of the Patella. International Journal of Radiology 2018; 5(1): 172-176 Available from: URL: http://www.ghrnet.org/index.php/ijr/article/view/2317

EDITORIAL

Congenital aplasia of the patella is an extremely rare disorder, characterized by congenital absence or marked reduction of the patella. The prevalence rate of patellar aplasia in the newborn child is not readily diagnosed because the patella is completely cartilaginous at birth and starts its ossification process between the third and the sixth year. Aplasia of the patella has been documented in the papers of Little and Mayer since 1897. Congenital absence of the patella is usually observed bilaterally and is usually associated with other malformations, although it may occasionally present as an isolated lesion. Congenital anomalies characterized by patellar aplasia belong to a clinically diverse and genetically heterogeneous group of disorders. The most common syndromes associated with congenital patellar aplasia is the nail-patella syndrome (NPS), also known as hereditary onychoosteodysplasia (HOOD syndrome), as Fong disease or as Turner-Kieser syndrome, and the ischiopatellar dysplasia (IPD), also known as the ‘small patella’ syndrome (SPS)[1-9].

Patients with NPS also present with ungula (nail) dysplasia from birth, elbow dysplasia, exostoses of the ilia (iliac horns), swan-neck deformity and absent skin creases on the dorsal aspect of the distal interphalangeal joints of the fingers, tingling, numbness, and in some cases renal insufficiency. The disease is transmitted as a simple autosomal dominant gene resulting from symmetrical mesodermal and ectodermal abnormalities. There is a definite linkage between the locus of the nail-patella gene and the ABO blood groups. LMX1B (LIM homeobox transcription factor 1 beta) is a unique mesenchymal determinant of dorsal patterning during vertebrate limb development, so mutations in the LMX1B gene on chromosome 9q34 result in skeletal dysplasia affecting the dorsal tissues, especially the nails and patellae. Most patients function without difficulty, while some individuals may have flexion contractures and recurrent knee dislocations. Diagnostic radiographic findings include absent or severely hypoplastic patellae (with a tendency to recurrent dislocation), hypoplasia of the radial head or capitellum (leading to subluxation/dislocation), bilateral posterior iliac horns and protuberant anterior iliac spines (Figure 1). The bilateral posterior iliac horns, due to exostoses arising from the posterior aspect of the iliac bones, are present in as many as 80% of patients; this finding is considered pathognomonic for the syndrome. The horns may be capped by an epiphysis. Iliac horns were initially described by Edward Everett Fong, an American radiologist in 1912. Various other skeletal anomalies, including pes equinovarus, dislocated hips, and contractures of major joints have been described in NPS but do not contribute to the diagnosis. Other features include: scoliosis, genu valgum deformity, flared iliac crests, prominent tibial tuberosities, clinodactyly, short 5th metacarpals, open angle glaucoma and renal osteodystrophy[10-35].

Ischiopubic hypoplasia is a rare constituent of congenital syndromes. Ischiopubic hypoplasia is associated, in most cases, with other malformations such as anomalies of the hips, including CDH, of the feet, including talipes equinovarus and scoliosis. Congenital anomalies of the pelvic bones and hips associated with aplasia of the patellae are diagnosed as IPD or as the SPS[36-39]. They are also known as coxopodopatellar syndrome or Scott-Taor syndrome (Figure 2). It is a rare autosomal dominant disorder, characterized by aplasia of the patellae and various anomalies of the pelvis and feet. The syndrome was first described by Scott and Taor in 1979 in a large family with bilateral small or absent patellae accompanied by anomalies of the pelvic girdle and upper femora, in most of the affected subjects. Other major signs were a wide gap between the first and second toes, short fourth and fifth rays of the feet, and pes planus. Various other skeletal anomalies have been reported, such as elongated femoral necks, flattened and widened proximal femoral epiphyses, hypoplasia of the lesser trochanter and tarsal anomalies[40-50].

Other congenital anomalies associated with patellar aplasia include the Meier-Gorlin syndrome[51,52], the Rapadilino syndrome[53], the genitopatellar syndrome[54], aniridia[55], and trisomy 8q syndrome determined on chromosome analysis[56]. Patellar aplasia may be also occasionally associated with various orthopaedic malformations, but the most common one is congenital dislocation of the knee (Figures 3 and 4)[57-61].

Isolated familial patella aplasia or congenital patellar syndrome is a rare autosomal dominant disorder in which congenital aplasia of the patellae is the only clinical and radiographic finding. Congenital absence or marked reduction of the patellar bone (Patellar Aplasia-Hypoplasia-PTLAH) has been described in only a few families to date. It may cause no major dysfunction, and surgical or major treatment is not always required. Whenever the absence of the patella is associated with atrophy of the quadriceps mechanism, patients suffer from weakness of knee extension and may develop progressive flexion deformity of the knee. A locus for PTLAH has been identified on chromosome 17q21-22[62-71].

Differential diagnosis of patients with aplasia of the patellae requires careful clinical and radiographic evaluation, and primarily involves the NPS, IPD and the isolated familial PTLAH. In NPS, patellar aplasia is associated with nail anomalies since birth, deformation or luxation of the head of the radius resulting in impaired mobility of the elbow, iliac horns and, frequently, nephropathy. Radiological examination of the pelvis and feet should be performed in all patients with aplasia of the patellae in order to differentiate SPS from PTLAH, and to further evaluate the diagnostic value of pelvic and feet anomalies in SPS. Pelvic anomalies, including anomalies of the ischiopubic joint or infra-acetabular notches have never been mentioned in PTLAH. Linkage studies excluded allelism of IPD with NPS, while allelism between IPD and PTLAH cannot be excluded so far[72].

Figure 1 A 57-year-old man with a diagnosed nail-patella syndrome. The nails are markedly ridged, abnormally structured and almost completely absent in the thumbs. The skin shows a loss of creases on the dorsal aspect of the distal interphalangeal joints of the fingers. Radiographs showed complete absence of the patella on the right and a hypoplastic patella on the left knee. Elbow radiographs indicated hypoplasia of the radial head and capitellum. Anteroposterior radiograph and computed tomography of the pelvis demonstrated protuberant anterior iliac spines and a bilateral bony exostosis or posterior iliac horn, which is pathognomonic of NPS.

Figure 2 An 8-year-old boy with bilateral congenital absence of the patella. Ischiopubic hypoplasia and scoliosis were also evident in the patient leading to the diagnosis of a sporadic case of IPD or SPS.

Figure 3 Typical clinical appearance and radiographic features of congenital dislocation of the knee in a 4-day-old girl.

Figure 4 A 5-year-old girl with congenital dislocation of the right knee (bottom). The range of joint motion of the left knee (top) was normal. Posterior slope of the right tibial surface was evident on the lateral views. There is aplasia of the right patella, while the left one seems to be hypoplastic. However, further follow-up is required to secure the diagnosis of the congenital patellar anomalies.

REFERENCES

1. Little EM. Congenital absence or delayed development of the patella. Lancet 1897; 2: 781-4.

2. Mayer HN. Congenital absence or delayed development of the patella. Lancet 1897; 2: 1384-5.

3. Kutz ER. Congenital absence of the patellae. J Pediatr 1949; 34: 760-2. [PMID: 18130187].

4. Bell J. Congenital absence of both patellae. J Bone Joint Surg 1955; 37B: 352.

5. Riccardi VM, Atkins L, Holmes LB. Absent patellae, mild mental retardation, skeletal and genitourinary anomalies, and C group autosomal mosaicism. J Pediatr 1970; 77(4): 664-72. [PMID: 5454713].

6. Spranger J, Benirschke K, Hall JG, Lenz W, Lowry RB, Opitz JM, Pinsky L, Schwarzacher HG, Smith DW. Errors of morphogenesis: concepts and terms. Recommendations of an international working group. J Pediatr 1982; 100(1): 160-5. [PMID: 7057306].

7. Miller TT, Shapiro MA, Schultz E, Crider R, Paley D. Sonography of patellar abnormalities in children. AJR Am J Roentgenol 1998; 171(3): 739-42. [PMID: 9725307]; [DOI: 10.2214/ajr.171.3.9725307].

8. Fulkerson JP, Buuck DA, Post WR, Farr J, Dye SF. Disorders of the patellofemoral joint. 4th ed, Lippincott Williams & Wilkins, 2004.

9. Bongers EM, van Kampen A, van Bokhoven H, Knoers NV. Human syndromes with congenital patellar anomalies and the underlying gene defects. Clin Genet 2005; 68(4): 302-19. [PMID: 16143015]; [DOI: 10.1111/j.1399-0004.2005.00508.x].

10. Maini PS, Mittal RL. Hereditary onycho-osteo-arthrodysplasia. J Bone Joint Surg Am 1966; 48(5): 924-30. [PMID: 5942808].

11. Palacios E. Hereditary osteo-onycho-dysplasia. The nail-patella syndrome. Am J Roentgenol Radium Ther Nucl Med 1967; 101(4): 842-50. [PMID: 6073380].

12. Beals RK, Eckhardt AL. Hereditary onycho-osteodysplasia (Nail-Patella syndrome). A report of nine kindreds. J Bone Joint Surg Am 1969; 51(3): 505-16. [PMID: 5778286].

13. Geens S. Heredity osteo-onycho-dysplasia (Nail-Patella syndrome). Report of an affected family and two severely disabled sporadic cases. Acta Orthop Belg 1970; 36(2): 229-54. [PMID: 4915921].

14. Alain JL, Rigault P. Hereditary onycho-arthro-dysplasia. Rev Chir Orthop Reparatrice Appar Mot 1972; 58(6): 623-8. [PMID: 4267337].

15. Yakish SD, Fu FH. Long-term follow-up of the treatment of a family with nail-patella syndrome. J Pediatr Orthop 1983; 3(3): 360-3. [PMID: 6874935].

16. Banskota AK, Mayo-Smith W, Rajbhandari S, Rosenthal DI. Case report 548: Nail-patella syndrome(hereditary onycho-osteodysplasia) with congenital absence of the fibulae. Skeletal Radiol 1989; 18(4): 318-21. [PMID: 2675322].

17. Stellamor K, Anzböck W. Hereditary onycho-osteo-arthrodysplasia (nail-patella syndrome) with progressive renal failure. Rontgenblatter 1989; 42(10): 437-40. [PMID: 2682986].

18. Letts M. Hereditary onycho-osteodysplasia (nail-patella syndrome). A three-generation familial study. Orthop Rev 1991; 20(3): 267-72. [PMID: 2023790].

19. Trinn C, Szöke B, Magyarlaki T, Turi S, Ormos J, Nagy J. Nail-patella syndrome: clinico-pathologic characteristics. Orv Hetil 1996; 137(41): 2253-6. [PMID: 8992423].

20. Wildfeuer T, Albrecht G. Nail-patella syndrome. Hautarzt 1996; 47(11): 860-2. [PMID: 9036142].

21. Höger PH, Henschel MG. Skeletal anomalies in nail-patella syndrome. Case report and overview. Hautarzt 1997; 48(8): 581-5. [PMID: 9378640].

22. Dreyer SD, Morello R, German MS, Zabel B, Winterpacht A, Lunstrum GP, Horton WA, Oberg KC, Lee B. LMX1B transactivation and expression in nail-patella syndrome. Hum Mol Genet 2000; 9(7): 1067-74. [PMID: 10767331].

23. Kolhe N, Stoves J, Will EJ, Hartley B. Nail-patella syndrome--renal and musculo-skeletal features. Nephrol Dial Transplant 2002; 17(1): 169-[PMID: 11773489].

24. Bongers EM, Gubler MC, Knoers NV. Nail-patella syndrome. Overview on clinical and molecular findings. Pediatr Nephrol 2002; 17(9): 703-12. [PMID: 12215822]; [DOI: 10.1007/s00467-002-0911-5].

25. Beguiristáin JL, de Rada PD, Barriga A. Nail-patella syndrome: long term evolution. J Pediatr Orthop B 2003; 12(1): 13-6. [PMID: 12488765]; [DOI: 10.1097/01.bpb.0000043727.21564.e9].

26. Sweeney E, Fryer A, Mountford R, Green A, McIntosh I. Nail patella syndrome: a review of the phenotype aided by developmental biology. J Med Genet 2003; 40(3): 153-62. [PMID: 12624132]; [PMCID: PMC1735400].

27. Dunston JA, Reimschisel T, Ding YQ, Sweeney E, Johnson RL, Chen ZF, McIntosh I. A neurological phenotype in nail patella syndrome (NPS) patients illuminated by studies of murine Lmx1b expression. Eur J Hum Genet 2005; 13(3): 330-5. [PMID: 15562281]; [DOI: 10.1038/sj.ejhg.5201332].

28. Bongers EM, Huysmans FT, Levtchenko E, de Rooy JW, Blickman JG, Admiraal RJ, Huygen PL, Cruysberg JR, Toolens PA, Prins JB, Krabbe PF, Borm GF, Schoots J, van Bokhoven H, van Remortele AM, Hoefsloot LH, van Kampen A, Knoers NV. Genotype-phenotype studies in nail-patella syndrome show that LMX1B mutation location is involved in the risk of developing nephropathy. Eur J Hum Genet 2005; 13(8): 935-46. [PMID: 15928687]; [DOI: 10.1038/sj.ejhg.5201446].

29. Bongers EM, de Wijs IJ, Marcelis C, Hoefsloot LH, Knoers NV. Identification of entire LMX1B gene deletions in nail patella syndrome: evidence for haploinsufficiency as the main pathogenic mechanism underlying dominant inheritance in man. Eur J Hum Genet 2008; 16(10): 1240-4. [PMID: 18414507]; [DOI: 10.1038/ejhg.2008.83].

30. Granata A, Nori G, Ravazzolo R, Marini M, Castellino S, Sicurezza E, Fiore CE, Mignani R. Nail-patella syndrome and renal involvement. Description of three cases and literature review. Clin Nephrol 2008; 69(5): 377-82. [PMID: 18538102].

31. Mankin HJ, Jupiter J, Trahan CA. Hand and foot abnormalities associated with genetic diseases. Hand (N Y) 2011; 6(1): 18-26. [PMID: 22379434]; [PMCID: PMC3041879]; [DOI: 10.1007/s11552-010-9302-8].

32. Tong SY, Luk HM, Tong TM, Lo IF. The nail points to the diagnosis. Fong disease or hereditary osteo-onychodysplasia. Hong Kong Med J 2015; 21(6): 573.e3-5. [PMID: 26634378]; [DOI: 10.12809/hkmj154728].

33. Tigchelaar S, Rooy Jd, Hannink G, Koëter S, van Kampen A, Bongers E. Radiological characteristics of the knee joint in nail patella syndrome. Bone Joint J 2016; 98B(4): 483-9. [PMID: 27037430]; [DOI: 10.1302/0301-620X.98B4.37025].

34. Harita Y, Kitanaka S, Isojima T, Ashida A, Hattori M. Spectrum of LMX1B mutations: from nail-patella syndrome to isolated nephropathy. Pediatr Nephrol 2016 Jul 23. [PMID: 27450397]; [DOI: 10.1007/s00467-016-3462-x].

35. Witzgall R. Nail-patella syndrome. Pflugers Arch 2017; 469(7-8): 927-36. [PMID: 28681095]; [DOI: 10.1007/s00424-017-2013-z].

36. Sferopoulos NK, Tsitouridis I. Ischiopubic hypoplasia: a rare constituent of congenital syndromes. Acta Orthop Belg 2003; 69(1): 29-34. [PMID: 12666288].

37. Sarban S, Ozturk A, Isikan UE. Aplasia of the pubic bone in conjunction with hip dislocation. J Pediatr Orthop B 2005; 14(4): 266-8. [PMID: 15931030].

38. Saber A. Isolated loss of inferior pubic ramus: a case report. J Med Case Rep 2008; 2: 202. [PMID: 18549487]; [PMCID: PMC2438370]; [DOI: 10.1186/1752-1947-2-202].

39. Bashyal RK, Malchau H, Nimkin K. The association of a dysmorphic pelvis, absence of pubic rami, hip dysplasia, and genitourinary anomalies. Birth Defects Res A Clin Mol Teratol 2012; 94(1): 57-60. [PMID: 22183795]; [DOI: 10.1002/bdra.22873].

40. Scott JE, Taor WS. The “small patella” syndrome. J Bone Joint Surg 1979; 61-B: 172-5. [PMID: 438269].

41. Vanĕk J. Ischiopatellar dysplasia (Scott and Taor’s syndrome of the small patella). Rofo 1981; 135(3): 354-6. [PMID: 6212344].

42. Burckhardt A. The small patella syndrome. A combination of knee and pelvic dysplasia. Z Orthop Ihre Grenzgeb 1988; 126(1): 22-9. [PMID: 3381566]; [DOI: 10.1055/s-2008-1044862].

43. Tachdjian MO. Pediatric Orthopedics W.B. Saunders, Philadelphia, 1990; 1879-1881.

44. Kozlowski K, Nelson J. Small patella syndrome. Am J Med Genet 1995; 57(4): 558-61. [PMID: 7573128]; [DOI: 10.1002/ajmg.1320570408].

45. Dellestable F, Péré P, Blum A, Régent D, Gaucher A. The ‘small-patella’ syndrome. Hereditary osteodysplasia of the knee, pelvis and foot. J Bone Joint Surg Br 1996; 78(1): 63-5. [PMID: 8898129].

46. Azouz E. M, Kozlowski K. Small patella syndrome: A bone dysplasia to recognize and differentiate from the nail-patella syndrome. Pediatr Radiol 1997; 27: 432-5. [PMID: 9133358]; [DOI: 10.1007/s002470050163].

47. Habboub HK, Thneibat WA. Ischio-pubic-patellar hypoplasia: Is it a new syndrome ? Pediatr. Radiol 1997; 27: 430-1. [PMID: 9133357]; [DOI: 10.1007/s002470050162].

48. Poznanski AK. Editorial comments on the ischio-pubic-patellar syndrome. Pediatr Radiol 1997; 27: 428-9. [PMID: 9133356]; [DOI: 10.1007/s002470050161].

49. Offiah AC, Mansour S, McDowall S, Tolmie J, Sim P, Hall CM. Surviving campomelic dysplasia has the radiological features of the previously reported ischio-pubic-patella syndrome. J Med Genet 2002; 39(9): e50. [PMID: 12205120]; [PMCID: PMC1735222].

50. Bongers EM, Duijf PH, van Beersum SE, Schoots J, Van Kampen A, Burckhardt A, Hamel BC, Losan F, Hoefsloot LH, Yntema HG, Knoers NV, van Bokhoven H. Mutations in the human TBX4 gene cause small patella syndrome. Am J Hum Genet 2004; 74(6): 1239-48. [PMID: 15106123]; [PMCID: PMC1182087]; [DOI: 10.1086/421331].

51. Bongers EM, Opitz JM, Fryer A, Sarda P, Hennekam RC, Hall BD, Superneau DW, Harbison M, Poss A, van Bokhoven H, Hamel BC, Knoers NV. Meier-Gorlin syndrome: report of eight additional cases and review. Am J Med Genet 2001; 102(2): 115-24. [PMID: 11477602].

52. de Munnik SA, Hoefsloot EH, Roukema J, Schoots J, Knoers NV, Brunner HG, Jackson AP, Bongers EM. Meier-Gorlin syndrome. Orphanet J Rare Dis 2015; 10: 114. [PMID: 26381604]; [PMCID: PMC4574002]; [DOI: 10.1186/s13023-015-0322-x].

53. Vargas FR, de Almeida JC, Llerena Júnior JC, Reis DF. RAPADILINO syndrome. Am J Med Genet 1992; 44(6): 716-9. [PMID: 1481838]; [DOI: 10.1002/ajmg.1320440604].

54. Bergmann C, Spranger S, Javaher P, Ptok M. Genitopatellar syndrome, sensorineural hearing loss, and cleft palate. Oral Maxillofac Surg 2011; 15(2): 103-6. [PMID: 20182757]; [DOI: 10.1007/s10006-009-0202-4].

55. Mirkinson AE, Mirkinson NK. A familial syndrome of aniridia and absence of the patella. Birth Defects Orig Artic Ser 1975; 11(5): 129-31. [PMID: 1218204].

56. Arslan H, Kapukaya A, Kayikçi C, Demircan A. Congenital patellar aplasia in conjunction with trisomy 8. A case report. Acta Orthop Belg 2004; 70(4): 373-6. [PMID: 15481426].

57. Katz MP, Grogono BJ, Soper KC. The etiology and treatment of congenital dislocation of the knee. J Bone Joint Surg Br 1967; 49: 112-20. [PMID: 6019376].

58. Goeminne L, Dujardin L. Congenital coxa vara, patella aplasia and tarsal synostosis: a new inherited syndrome. Acta Genet Med Gemellol (Roma) 1970; 19(4): 534-45. [PMID: 5512529].

59. Jacobsen K, Vopalecky F. Congenital dislocation of the knee. Acta Orthop Scand 1985; 56: 1-7. [PMID: 3984696].

60. Johnson E, Audell R, Oppenheim WL. Congenital dislocation of the knee. J Pediatr Orthop 1987; 7: 194-200. [PMID: 3558805].

61. Roth S, Sestan B, Gruber B, Ledić D, Ostojić Z, Rakovac I. Bilateral congenital dislocation of the knee with ipsilateral developmental dysplasia of the hip-report of three patients. Coll Antropol 2010; 34 Suppl 1: 299-305. [PMID: 20402338].

62. Rubin G. Congenital absence of patellae and other patellar anomalies in three members of the same family. JAMA 1915; 64: 2062.

63. Bernhang AM, Levine SA. Familial absence of the patella. J Bone Joint Surg 1973; 55A: 1088‑90. [PMID: 4760095].

64. Braun, HS. Familial aplasia or hypoplasia of the patella. Clin. Genet 1978; 13: 350-2. [PMID: 657574].

65. Mangino M, Sanchez O, Torrente I, De Luca A, Capon F, Novelli G, Dallapiccola B. Localization of a gene for familial patella aplasia-hypoplasia (PTLAH) to chromosome 17q21-22.Am J Hum Genet 1999; 65(2): 441-7. [PMID: 10417287]; [PMCID: PMC1377943]; [DOI: 10.1086/302505].

66. Bongers EM, van Bokhoven H, Knoers NV, Hamel BC, Woods CG. Evidence for genetic heterogeneity in familial isolated patella aplasia-hypoplasia. Am J Med Genet 2002; 108(1): 78-9. [PMID: 11857555].

67. Varghese RA, Joseph B. Congenital aplasia of the patella and the distal third of the quadriceps mechanism. J Pediatr Orthop B 2007; 16(5): 323-6. [PMID: 17762670]; [DOI: 10.1097/01.bpb.0000243828.22552.74].

68. Jerome JT, Varghese M, Sankaran B. Congenital patellar syndrome. Rom J Morphol Embryol 2009; 50(2): 291-3. [PMID: 19434325].

69. Oner M, Halici M, Guney A. Congenital total absence of the quadriceps muscle and patella: a case report with computed tomography scan and three-dimensional reconstructions. J Pediatr Orthop B 2013; 22(4): 322-4. [PMID: 22146563]; [DOI: 10.1097/BPB.0b013e32834dfe12].

70. Gunay C, Atalar H. An unusual case of neglected bilateral isolated aplasia of the patella in a 21-yearold patient: A case report. Formosan Journal of Musculoskeletal Disorders 2013; 4: 18-21.

71. Duygun F, Sertkaya O, Aldemir C, Doğan A. Isolated unilateral absent patella and contralateral small patella. BMJ Case Rep 2013. [PMID: 24001732]; [PMCID: PMC3794225]; [DOI: 10.1136/bcr-2013-200353].

72. Bongers EM, Van Bokhoven H, Van Thienen MN, Kooyman MA, Van Beersum SE, Boetes C, Knoers NV, Hamel BC. The small patella syndrome: description of five cases from three families and examination of possible allelism with familial patella aplasia-hypoplasia and nail-patella syndrome. J Med Genet 2001; 38(3): 209-14. [PMID: 11303519]; [PMCID: PMC1734819].

Peer Reviewer: Abdulrasool Alaee

Refbacks

  • There are currently no refbacks.


Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.