Focal Fibrocartilaginous Dysplasia (BFibrous

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Ulna. 70. Ulnar varus radial head dislocation. Surgery when first seen. (1) Curettage;. (2) osteotomy ..... cases of peroneal nerve palsy1,6 and 2 cases of valgus.

ORIGINAL ARTICLE

Focal Fibrocartilaginous Dysplasia (BFibrous Periosteal Inclusion^) An Additional Series of Eleven Cases and Literature Review Jean-Luc Jouve, MD,þ Remi Kohler, MD,Þ Scott J. Mubarak, MD,* Scott C. Nelson, MD,* Bruno Dohin, MD,Þ and Gerard Bollini, MDþ Abstract: Focal fibrocartilaginous dysplasia (FFCD) is a benign condition first described in 1985 as a cause of tibia vara. We are reporting on 11 cases. The lesions involved proximal tibia (9 cases), distal femur (1 case), and distal ulna (1 case). We believe that this entity represents a bony anchor preventing natural sliding of the periosteum during growth (an Bepiphysiodesis-like^ effect). For the tibia, we believe this is the pes anserinus. We are suggesting that this entity be called a Bfibrous periostal inclusion.^ Treatment indications result from this concept: (1) for tibial lesions with a metaphyseal-diaphyseal angle less than 20 degrees observation for 6 to 12 months; (2) if the deformity improves, the tether likely broke spontaneously, and no treatment is required; and (3) curettage early if the deformity worsens. This will be followed by rapid correction into physiological valgus (tibia) and prevent the need for osteotomy. Early curettage for other less common locations is recommended. Key Words: focal fibrocartilaginous dysplasia, curettage (J Pediatr Orthop 2007;27:75Y84)

F

ocal fibrocartilaginous dysplasia (FFCD) is a benign condition first described in 1985 by Bell et al4 as a cause of tibia vara. The authors postulated that a failure in differentiation of the pes anserinus areaVpersisting as a fibrocartilaginous focusVwas a cause of growth disturbance of the proximal tibia, resulting in a varus deformity. Literature review performed through the last 20 years collected 73 cases, most of them on the proximal tibial (43 cases), although other localizations are not so rare (distal femur, 15 cases; ulna, 10 cases; and others, 5 cases). The purpose of this study is to report an additional series of 11 cases and to discuss the mechanism of deformity and treatment decision making. We suggest calling this lesion Bfibrous periostal inclusion,^ a kind of anchor preventing natural sliding of the periosteum during growth (an Bepiphysiodesis-like^ effect). Treatment indications resulting

From the *Children’s Hospital San Diego, San Diego, CA; †Service d’orthope´die pe´diatrique, Hoˆpital Edouard Herriot-Pavillon Tbis, France; and ‡Service de chirurgie orthope´dique, Hoˆpital Timone, France. None of the authors received financial support for this study. Reprints: Scott J. Mubarak, MD, 3030 Children’s Way, Suite 410, San Diego, CA 92123. E-mail: [email protected] Copyright * 2007 by Lippincott Williams & Wilkins

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from this concept include the following: after observation (6 to 12 months), curettage should be considered early if the deformity persists or worsens, thus preventing osteotomy. In other cases, when the tether breaks spontaneously, no treatment is required.

METHODS During 1992 to 2005, we observed 11 cases of FFCD collected in 3 pediatric orthopaedic institutions [San Diego, Calif (USA), Marseille (France), and Lyon (France)] (Table 1). The locations involved were proximal tibia (9 cases), distal femur (1 case), and distal ulna (1 case). The diagnostic criteria were unilateral angular deformity in a long bone associated with the typical lucent bony defect with surrounding sclerosis at the concavity of the deformity with a cortical defect. There were 9 boys and 2 girls. The age at diagnosis ranged from 12 to 70 months (average, 23 months). Levine and Drennan metaphyseal-diaphyseal angle was used to evaluate and follow the tibial deformities.18 Additionally, we collected and analyzed 73 cases from the literature.

CASES REPORTS The parents of the following patients were informed that data concerning these cases would be submitted for publication, and their consent was obtained.

Case 1 A 22-month-old boy presented with a left unilateral bowleg. Originally, both legs were bowed, but the right side corrected in the normal physiological fashion. The child was otherwise healthy. He began walking at age 10.5 months. In the left medial proximal tibial metaphysis, x-rays revealed a lytic lesion with surrounding sclerosis. The metaphyseal-diaphyseal angle measured 22 degrees varus. The patient returned 5 months later showing no resolution of his deformity. At age 27 months, metaphyseal-diaphyseal angle measured 28 degrees varus. The child was taken to the operating room for curettage of the lesion. The pathology was consistent with the diagnosis of FFCD. Over the next 8 months, the varus deformity of the tibia corrected to 6 degrees of valgus, and his legs became symmetric (Fig. 1).

Case 2 A 27-month-old boy presented with bilateral bowlegs. Other than having mild internal tibial torsion bilaterally, this child was normal. He began walking at age 10 months. The left

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TABLE 1. Our Series (Cases 1Y2, San Diego; Cases 3Y6, Marseille; Cases 7Y11, Lyon) Short-Term Evolution

First Seen Case no.

Sex

Localization

Age (mo)

1

M

Tibia

22

2

M

Tibia

27

3

F

Tibia

12

4

M

Tibia

11

5

M

Tibia

15

6

M

Tibia

12

7

M

Tibia

15

8

F

Femur

40

9

M

Ulna

70

10

M

Tibia

17

11

M

Tibia

12

Angulation 22 degrees (Levine/ Drennan angle) 15 degrees (Levine/ Drennan angle) 14 degrees (Levine/ Drennan angle) 20 degrees (Levine/ Drennan angle) 11 degrees (Levine/ Drennan angle) 12 degrees (Levine/ Drennan angle) 28 degrees (Levine/ Drennan angle) 15 degrees (femorotibial angle) Ulnar varus radial head dislocation 14 degrees (Levine/ Drennan angle) 14 degrees (Levine/ Drennan angle)

metaphyseal-diaphyseal angle measured 15 degrees varus and was slightly more severe than the right. This patient was prescribed a Dennis-Brown bar with 45-degree external rotation to wear at night and during nap time. Four months later, he returned showing improvement bilaterally. His left side remained more severe than the right with genu varum of 13 degrees (femoral-tibial angle). He was also noted to have a small radiolucent lesion in the left proximal medial tibia. Computed tomographic (CT) scan confirmed the typical appearance of FFCD. At 36 months of age, the lesion seems to be filling in with an improvement to 10-degree metaphyseal-diaphyseal angle in his right and left lower extremity.

Last Follow-up

Age (mo)

Angulation (degrees)

27

28

Curettage

58

Symmetrical

36

10

No

36

3 degrees varus

36

30

Osteotomy

49

Symmetrical

24

18

No

47

Symmetrical

24

13

No

57

Symmetrical

18

14

No

68

Symmetrical

Curettage

96

Symmetrical

Curettage

120

Symmetrical

Surgery when first seen Surgery when first seen Surgery when first seen 25

0

22

20

Treatment

Age (mo)

Angulation

(1) Curettage; (2) osteotomy (9 mo later) No

96

Symmetrical radial head reduction

37

Symmetrical

Curettage

28

Symmetrical

Case 3 A 12-month-old girl presented unilateral left varus deformity. Radiographic examination demonstrated typical radiolucency of the proximal tibia and a metaphyseal diaphyseal angle measured 14 degrees. She was treated with nocturnal bracing, and at the age of 3 years old, presented worsening deformity with 30-degree metaphyseal diaphyseal angle. The treating surgeon elected to perform a valgus osteotomy of the proximal tibia combined with fibular osteotomy. Acute correction was obtained, and 1-year follow-up shows a normal tibiofemoral axis bilaterally. The pathology showed the typical fibrocartilaginous tissue at the pes anserinus insertion.

FIGURE 1. A, Proximal tibia (varus deformity) in a 22-month-old boy. B and C, Therapeutic drug monitoring and MRI assessing pathological inclusion in the cortical bone. Arrows indicate pes connection into proximal tibia (fibrous periosteal inclusion). D, A simple curettage is performed at the age of 27 months with early healing at 8-month follow-up.

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Focal Fibrocartilaginous Dysplasia

Case 4

Case 8

An 11-month-old boy presented with an idiopathic 20-degree (metaphyseal/diaphyseal angle) varus deformity of the right lower extremity. His x-ray showed a lucency surrounded by a dense layer of bone in the medial proximal tibia. He was observed, and at 1- and 2-year follow-up visits, he was noted to have an 18-degree deformity. At the age of 3 years, the deformity had improved to 8 degrees of varus, and by the age of 4 years, it had resolved.

A girl aged 3 years 4 months was seen with asymmetric genu valgum and a lateral metaphyseal radiolucency in the distal left femur typical of FFCD. The lesion underwent curettage, and during follow-up visits at 5 and 9 years, the patient was noted to have a normal lower extremity mechanical axis bilaterally (Fig. 2).

Case 5 A 15-month-old boy presented with an asymmetric tibia vara measuring 11 degrees on the affected right lower extremity (metaphyseal/diaphyseal angle). The child was observed with a follow-up visit at the age of 24 months, noting 13 degrees of deformity. This deformity resolved by age 3 years 5 months, and his alignment remained within normal limits at his latest follow-up at age 4 years 9 months.

Case 6 A 1-year-old boy presented with a varus asymmetry of the left tibia measuring 12 degrees (metaphyseal-diaphyseal angle). Radiographs confirmed the typical appearance of FFCD, and the child was observed. Follow-up at the age of 18 months and 29 months showed a stable deformity at 14 and 13 degrees, respectively. At the age of 5 years 6 months, the deformity resolved clinically and radiographically.

Case 7 A 15-month-old boy presented with an asymmetric varus deformity of the right proximal tibia with the typical radiographic features of FFCD. At 18 months, curettage was performed, and the diagnosis was confirmed. A 5-degree correction occurred within the first 3 postoperative months, and at 1 year postoperation, the deformity had almost corrected, and at 8 years, the lower extremity alignment was normal.

Case 9 A boy aged 5 years and 10 months was seen with asymmetric deformity of the right forearm. Radiographs confirm shortening and varus deviation of the ulna associated with proximal radial dislocation. In the medial proximal ulna, x-ray showed a lucency surrounded by a dense layer of bone. Magnetic resonance imaging (MRI) confirmed the diagnosis. Curettage was performed at the age of 6 years 8 months. The pathology showed fibrous aspect of the periosteum invaginated in the cortical bone. At 9 months’ follow-up, ulnar deformity and radial head dislocation remained. Ulnar osteotomy with lengthening was decided at the age of 7 years 5 months, with a satisfactory result (Fig. 3).

Case 10 A 17-month-old boy presented with an idiopathic asymmetric varus deformity of the right limb. A 14-degree (metaphysealdiaphyseal angle) varus deformity was observed on the x-ray with a lucency surrounded by a dense layer of bone in the medial proximal tibia. He was observed, and at follow-up visits at 8 months, he was noted to have no residual angulation with the metaphyseal diaphyseal angle. By the age of 5 years, the deformity had resolved.

Case 11 A 12-month-old boy presented with a right unilateral bowleg. In the right medial proximal tibial metaphysis, x-rays revealed a lytic lesion with surrounding sclerosis. The metaphyseal-diaphyseal angle measured 14 degrees varus. The patient returned 10 months later

FIGURE 2. A, Distal femur localization (valgus deformity) in a 3-year-old boy. Treatment with curettage. B, Improvement at 5 years old. C, Complete healing at 9 years old. * 2007 Lippincott Williams & Wilkins

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FIGURE 3. A, Ulnar localization with radial head dislocation in a boy aged 5 years 10 months. B, Operative view demonstrating fibrous band introduced in the cortical ulna. C, Histological aspect demonstrating fibrous tissue invaginated in the notch of the cortical bone. D, At 9 months’ follow-up, the ulnar deformity and radial head dislocation have been corrected with ulnar lengthening. E, Result at age 7 years 5 months.

with no resolution of his deformity. At age 22 months, the metaphyseal-diaphyseal angle measured 20 degrees. The child was taken to the operating room for curettage of the lesion. The pathology was consistent with the diagnosis of FFCD. Over the next 6 months, the varus deformity of the tibia corrected.

RESULTS All the 11 cases in this series presented with correction at last follow-up. No complication was observed with the treatment. Considering the 9 tibial localizations, 5 cases received no treatment, 3 cases were treated with simple curettage, and in 1 case (case 3), osteotomy was necessary (observed from 14 to 30 degrees Levine/Drennan angle and then osteotomy). All patients had normal physiological angulation at follow-up. The limb length discrepancy was minor. The femur case resolved with curettage (2 years follow-up). No osteotomy was performed. The ulnar case associated with radial head dislocation was initially treated with curettage at 6 years of age. Ulnar deviation and radial head dislocation remained. A second-stage surgery with ulnar lengthening and correction of the deviation was necessary, with a good result.

DISCUSSION There has been 73 cases of FFCD so far reported in the literature (Table 2). Forty-three of these lesions were located in the proximal medial tibia, causing a varus deformity in 41 cases, a valgus in 2 cases.26,28 The remaining cases were located in a variety of sites, including the distal femur (15 cases) with varus or valgus deformity,1Y3,5,7,16,20,26,27,30 and distal ulna (10 cases).7,14,19,29 There have been an increasing

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number of cases reported recently (28 cases during the 5 last years). This curious lesion is now probably better recognized, which is particularly evident for ulnar lesions. Although most of the lesions at these various sites have histological and radiographic similarities to the medial proximal tibial lesions, the natural history and treatments may vary especially for ulnar lesions. Thus, we have chosen to focus only on the lesions located in the proximal medial tibia and the femur. This disorder is usually noticed by the parents shortly after the onset of ambulation.15 Hence, most patients present between the ages of 12 and 24 months. Some lesions will initially progress; however, resolution and correction typically begins around the age of 24 months as noted in the cases reported in the literature.6,17 The histopathology and clinical course of the disease process are not uniform, resulting in various degrees of deformity and time needed for resolution. Radiographically, these lesions are characterized by a well-defined lucent defect; there is sclerosis along the lateral border of the lesion, and superior-medially, there is an absent bone margin10,25 (Fig. 1). In the tibia, the deformity is located in the proximal metaphysis. Varus deformity is usual, but 2 valgus cases have been reported. With the goal to differentiate physiological bowing and FFCD, we measured the metaphyseal-diaphyseal angle. This angle, described by Levine and Drennan,18 is created by the intersection of a line through the transverse plane of the proximal tibial metaphysic with a line perpendicular to the long axis of the tibial diaphysis. It is the authors’ opinion that the Levine and Drennan angle is well suited for FFCD tibial lesions because it measures very closely to the pathological deformity. * 2007 Lippincott Williams & Wilkins

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Focal Fibrocartilaginous Dysplasia

TABLE 2. Literature Review (1985Y2005), 73 Cases Authors (Ref. no.)

No. Cases

Age at Diagnosis (mo)

Sex

Bell et al4

3

9

M

15

M

27

F

15

F

24

M

17

M

28

F

16

F

1

22

M

4

30

Bradish et al6

Husien and Kale11 Beaty and Barret3

Herman et al10

Olney et al24

Kariya et al13

Zayer31

LandreauJolivet et al17

5

3

3

2

2

4

Localization

Deformity

Treatment

ResultY Complications

R

Varus

Osteotomy

24

Normal

R

Varus

Osteotomy

24

Normal

R

Varus

Observation

V

Resolved

L

Varus

Osteotomy

28

?

R

Varus

Observation

V

Normal

R

Varus

Observation

V

Normal

L

Varus

Observation

V

R

Varus

Osteotomy

25

R

Varus

R

Valgus

Night splint (1 year) Osteotomy

V

M

Proximal tibia Distal femur

Complete healing Valgus deformity + peroneal palsy Normal

13

F

Distal femur

R

Varus

Osteotomy

?

9

M

Distal femur

R

Valgus

Osteotomy

?

42

M

Distal femur

L

Varus

18

F

R

Varus

24 69 V

25

F

R

Varus

Osteotomy

26

Normal

16

F

L

Varus

Night splint

V

?

18

F

L

Varus

Osteotomy

30

Normal

5

M

R

Varus

Osteotomy

6

Normal

6

M

L

Varus

Osteotomy

23

Normal

5

F

R

Varus

Observation

V

Normal

12

F

L

Varus

Observation

V

12

F

R

Varus

Observation

V

Complete healing Normal

12

F

R

Varus

Observation

V

Normal

10

M

R

Varus

Night splint

V

Normal

11

M

R

Varus

Osteotomy

36

Normal

11

M

?

Varus

Observation

V

Normal

13

F

Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Distal femur

Osteotomy Curettage Night splint

Complete healing Complete healing Persistence raccourcissement V V Normal

?

Varus

Osteotomy

?

Normal

R

Varus

Observation

?

Normal

R

Varus

Osteotomy + curettage

V

Cockshott et al8

1

24

F

Vallcanera et al30

1

13

M

Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia Proximal tibia

Side

Age at Operation (mo)

54

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TABLE 2. (continued) Literature Review (1985Y2005), 73 Cases Authors (Ref. no.) Marchiodi et al21 Meyer et al22

Lincoln and Birch19

Albinana et al1

No. Cases

Age at Diagnosis (mo)

Sex

1

24

F

2

7

M

12

M

22

M

24

M

24

M

15

M

13

M

18

M

16

F

2

5

Localization

Side

Deformity

Age at Operation (mo)

Treatment

Proximal tibia Proximal tibia Proximal tibia Proximal humerus Ulna

R

Varus

Osteotomy

?

Normal

R

Varus

Osteotomy

26

Normal

L

Varus

Osteotomy

14

Normal

R

Varus

Osteotomy

72

Acceptable

L

Varus

Observation

?

Proximal tibia Proximal tibia Proximal tibia Proximal tibia Distal femur

L

Varus

Night splint

?

Healing but slight inequality Normal

L

Varus

Osteotomy

?

L

Varus

Night splint

?

L

Varus

Osteotomy

?

L

Varus

?

Complete healing

R R

Valgus ?

Periosteal medial release 3 Osteotomies Curettage ?

44 ?

L L R

Varus Varus Varus

Osteotomy Osteotomy Osteotomy

? ? 20

Normal Complete healing Normal Normal Normal

L

Varus

Osteotomy

39

L

Varus

Osteotomy

33

L

Varus

Observation

V

Complete healing Valgus deformity Normal

R

Varus

33

Normal

25

Normal

V

Correction Correction Complete healing Normal

Amillo et al2 Nakase et al23

1 1

12 ?

M F

Macnicol20

2

Choi et al7

8

24 14 18

M M F

18

M

16

F

17

M

17

M

Distal femur Proximal tibia Distal femur Distal femur Proximal tibia Proximal tibia Proximal tibia Proximal tibia Distal femur

15

F

Distal femur

L

Valgus

20

M

L

Varus

25 20

M M

R L

Incurve Varus

Observation Curettage

V V

17

M

Proximal tibia Ulna Proximal tibia Proximal tibia Proximal tibia Tibia

Osteotomy + Ilizarov Osteotomy + Ilizarov Observation

L

Varus

Observation

V

L

Valgus

Observation

V

R

Vara

Observation

V

L

Varus

Curettage

L

Valgus

Curettage

Short time observation V

L

Varus

Curettage

V

L

Valgus

Curettage

27

Khanna et al15

2

Santos et al28

1

22

M

Postovsky et al25 Poul and Straka26

1

24

F

3

17

?

18

M

11

M

Proximal tibia Proximal tibia Distal femur

20

F

Distal femur

Ruchelsman et al27

80

1

ResultY Complications

NormalVperoneal palsy Complete healing Normal

Complete healing None reported Complete healing Complete healing 10-mm shortening Healing

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Focal Fibrocartilaginous Dysplasia

TABLE 2. (continued) Literature Review (1985Y2005), 73 Cases Authors (Ref. no.) Smith et al29

Kazuki et al14

Berson et al5

No. Cases

Age at Diagnosis (mo)

Sex

7

43

M

Ulna

L

18

M

Ulna

R

57

M

Ulna

L

43

F

Radius

L

birth

M

Radius

V

birth

M?

Phalanx

V

1

?

Phalanx

V

60

F

Ulna

L

36

M

Ulna

L

60

F

Ulna

L

24

F

Ulna

L

84

M

Ulna

R

15

M

Femur

L

Forearm bowing Radial dislocation Forearm bowing Radial dislocation Forearm bowing Radial dislocation Forearm bowing Radial dislocation Varus

16

F

Femur

R

Varus

5

2

Localization

Side

Deformity Ulnar deviation Radial head subluxated Ulnar deviation Radial head subluxated Ulna bowing, progressive Radial dislocation Radial deviation

Treatment

Age at Operation (mo)

ResultY Complications

Biopsy

43

Normal except 15-degree loss of pronation

Observation

V

Normal

Ulna lengthening

105

Partial correction

Observation

V

Ulna deviation

Observation

V

Lateral deviation Lateral deviation Forearm bowing Radial dislocation

Osteotomy

24

Osteotomy

V

Normal function, length discrepancy No change at 15 mo old Recurrence of the deviation Lost FU

Ulnar lengthening Radius and ulna osteotomies 1-Bone forearm

60

Remained

36

Correction, limitation of rotation

1-Bone forearm

60

Correction, limitation of rotation

Ulnar lengthening

96

Corrected

Ulnar lengthening

84

Corrected

Curettage and osteotomy Curettage and osteotomy

45

11 degrees varus

29

Corrected

F indicates female; L, left; M, male; R, right.

With these classic findings, further imaging is not indicated,22 and biopsy is not necessarily required. However, in cases with atypical presentation, CT or MRI may be used to confirm diagnosis. These studies can be helpful in identifying the presence of dense fibroconnective tissue that is seen on MRI.22 On CT scan, this tissue is noted to be indistinguishable from overlying muscle and tendon. Histological findings include various combinations of dense fibrous tissue with or without cartilaginous tissue. There is variation in cellularity, with hypocellular areas being mainly composed of dense fibrous tissue. Prominent osteoclastic and osteoblastic activity surrounding some lesions

supports evidence for active remodeling in and around the lesions. This typical histology is demonstrated in case 8 (Fig. 3). Grossly, firm fibrous tissue has been noted to be tightly adhered to the overlying thickened periosteum in the notch of the cortex.7 The etiology of these lesions remains unknown. It was postulated that this may have been caused by trauma at delivery or other unknown trauma, and subsequent regeneration caused the characteristic defect distal to the physis.3,23,31 Nakase et al23 reported a florid periosteal reaction in the proximal tibia of a 2-month-old infant that resolved and later presented with the classic findings and appearance of FFCD.

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Focal fibrocartilaginous dysplasia is characterized by abnormal development of fibrocartilage at the site of tendon insertion.1,4,13,28 This involves the pes anserinus for lesions located in the medial proximal tibia. The angular deformity is not located in the growth plate in any case. The concept of a Bfibrous tether^ or Bmesenchymal anlage^ has also been proposed.1,3,4,15,20,21 It is interesting to note that this lesion has the potential to spontaneously correct even with varus deformities beyond 30 degrees.31

Treatment Modalities Tibial Lesions Considering tibial locations methods previously reported in the literature include observation (with or without bracing; 21 cases), biopsy/curettage (3 cases), Bhemicircumferential periosteal release with partial osteotomy^ (1 case), and corrective osteotomy (18 cases), an initial period of observation to document progression or resolution of the deformity seems warranted in nearly all cases.1,7,24 Choi et al7 reports that approximately 45% of lesions reported in the literature have proven the ability to correct spontaneously. It is likely that far more would correct spontaneously had they been given the chancel;1,4,6,7,11,17 however, the other 55% of lesions were treated with proximal tibial osteotomy or biopsy due to parental or physician concerns. When a varus deformity develops that is too severe to be acceptable cosmetically and biomechanically, then an operative approach may be indicated. This is especially true when a lesion fails to show improvement by the age of 2 years. Even when spontaneous improvement does occur, it may take months or years to resolve. Although Choi et al7 quotes a median time to resolution at 57 months, it is impossible to tell from the literature how long it actually takes for a lesion to resolve because this type of calculation is based on time to most recent follow-up, which in 1 case was greater than 30 years

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(Table 1).31 In addition, there is no objective criterion by which resolution is achieved. In this study, we observed 4 patients that had less than 20 degrees of varus that resolved without surgery in about 2 years. A corrective osteotomy of the proximal tibia and fibula has been a popular treatment modality (18 of 43 proximal tibial cases reported). Although usually successful, this treatment has had some serious complications, including 2 cases of peroneal nerve palsy1,6 and 2 cases of valgus overcorrection.6,7 There have also been 4 cases reported in the literature that underwent biopsy without osteotomy. These all went on to resolve without further treatment.6,31 Although it is impossible to tell from these studies exactly what the Bbiopsy^ procedure involved (needle biopsy versus open treatment with or without curettage) was, it is evident that further treatment was not needed in these cases. Curettage has been previously reported in only 4 cases, which were published in the literature.15,23,26 All cases showed a rapid improvement (Table 2). We are reporting an additional 3 cases that underwent simple curettage and consequently resolved in less than a year; this correction of nearly 30 degrees in 1 year (92 degrees/month) is rather spectacular for a lesion treated by just a curettage. Curettage is a minimally invasive procedure that has a low complication rate and seems to be very effective at stimulating correction of the deformity. It should be considered when the Levine and Drennan angle worsens after a 6-month observation and is around 20 degrees. The tibial lesion in this series that underwent osteotomy was observed from 14 to 30 degrees (1Y3 years). Perhaps earlier intervention with curettage at age 2 and 20 degrees would have averted the osteotomy. We believe that curettage removes the fibrous tether and, simultaneously, physeal growth is stimulated. Furthermore, while treating the disorder, it provides a histopathologic diagnosis, which may place the parents and the surgeon at ease when treating this rare entity.

FIGURE 4. Favorable evolution with spontaneous rupture of the fibrous tether.

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Femoral Lesions The treatment of femoral lesions is similar to the tibia. The femoral cases previously reported in the literature include curettage or Bposteromedial release^ (3 cases) and corrective osteotomy (12 cases). Amillo et al2 presented in 1998 a case with femoral valgus treated by 2 percutaneous osteotomies. The deformity recurred until the third-stage surgery, associating both resection of fibrous band and osteotomy. These authors postulated that simple curettage can correct the deformity as was proposed earlier. Kohler16 performed curettage in 1 case with correction. Albinana et al1 presented similar results with simple periosteal resection, and Ruchelsman et al27 and Poul and Straka,26 with fibrous resection. Considering the femoral locations, no spontaneous correction is described in the literature. It is the authors’ opinion that in case of femoral lesions, MRI is indicated to visualize the fibrous band. Excision of the tether, periosteum, and curettage is necessary in all cases. This should be sufficient to avoid osteotomy. However, considering the small numbers reported, no angle value can be suggested as to when osteotomy is necessary.

Upper Extremity Lesions Fifteen cases have been reported, with 10 cases involving the ulna7,14,19,29 and the rest the humerus. The treatment in ulnar locations included simple observation (2 cases), biopsy (1 case), osteotomies with ulnar lengthening (3 cases), and 1 bone forearm reconstruction (2 cases). The problem in ulnar localization is the risk for radial head dislocation. The authors’ opinion is that very closely, short observation is necessary with lesions of the ulna. Special attention is needed concerning the radial head, and MRI is indicated to be sure of early diagnosis. In case of progression, curettage associated with band resection and ulnar osteotomy is indicated. Additional ulnar lengthening is indicated in case of radial head subluxation/dislocation

Mechanism Although the etiology of FFCD remains unclear, we believe that FFCD can be considered as an abnormal anchorage of a tendon or a pathological fibrous band in the metaphyseal bone that we call Bfibrous periosteal inclusion.^ The consequence is a disturbance of the natural sliding of the periosteum along the diaphyseal bone during growth, inducing an epiphysiodesis-like effect with similar consequences. If we consider tendons with metaphyseal insertions, a relative migration of this insertion is necessary along the cortical bone to maintain their anatomical situation during growth.9 In most cases, this abnormal fixation is due to the inclusion of the pes anserinus in the medial part of the metaphysis. The effects are similar as observed in an epiphysiodesis and the evolution comparable (Fig. 4): If the inclusion is not too large, a spontaneous rupture of the fibrotic band occurs, and the remaining growth allows correction of the deviation.

Focal Fibrocartilaginous Dysplasia

If the inclusion is too large or strong, the combined effect of the fixed periosteum and the tension of the pes anserinus increases the deviation and shortening. In other localizations, fibrous tethered bands have been described by authors with similar effects on the distal femur, humerus, and ulna. In our experience, spontaneous improvementVif it occursVis established very early. After diagnosis in a child less than 2 years, a 6-month follow-up is indicated to determine the behavior of the deformity. In case of spontaneous improvement or stabilization, the deformity should resolve without any treatment. If the child is around 2, and the Levine/Drennan angle is more than 20 degrees, curettage should be considered. Treatment by curettage will accelerate the correction and will give histological confirmation of the diagnosis. This treatment method avoids osteotomies and their related complications while allowing the parents and treating surgeon to proceed with confidence. REFERENCES 1. Albinana J, Cuervo M, Certucha A, et al. Five additional cases of local fibrocartilaginous dysplasia. J Pediatr Orthop. 1997;6B:52Y55. 2. Amillo S, Mora G, Leniz P. Progressive genu valgum secondary to a fibrous tether at the distal aspect of the femur. J Bone Joint Surg. 1998;80A:424Y427. 3. Beaty JH, Barret IR. Unilateral angular deformity of the distal end of the femur secondary to a focal fibrous tether. J Bone Joint Surg. 1989;71A: 440Y445. 4. Bell SN, Campbell PE, Cole WG, et al. Tibia vara caused by focal fibrocartilaginous dysplasia. J Bone Joint Surg. 1985;67B: 780Y784. 5. Berson L, Dormans J, Drummond D, et al. Fibrous lesion of the distal femur associated with angular deformity. J Pediatr Orthop. 1999; 19:527Y530. 6. Bradish CF, Davies SJ, Malone M. Tibia vara due to focal fibrocartilaginous dysplasia. J Bone Joint Surg. 1988;70B:106Y108. 7. Choi IH, Chong JK, Cho TJ, et al. Focal fibrocartilaginous dysplasia of long bones: report of eight additional cases and literature review. J Pediatr Orthop. 2000;20:421Y427. 8. Cockshott WP, Martin R, Friedman L, et al. Focal fibrocartilaginous dysplasia and tibia vara: a case report. Skeletal Radiol. 1994;23: 333Y335. 9. Do¨rfl J. Migration of tendinous insertions. I. Cause and mechanism. J Anat. 1980;131:179Y195. 10. Herman TE, Siegel MJ, McAlister WH. Focal fibrocartilaginous dysplasia associated with tibia vara. Radiology. 1990;177:767Y768. 11. Husien AM, Kale VR. Case report: tibia vara caused by focal fibrocartilaginous dysplasia. Clin Radiol. 1989;40:104Y105. 12. Jouve JL, Debelenet H, Petit P, et al. Focal fibrocartilaginous dysplasia and tibia vara: a report of 2 cases: review of literature. Rev Chir Orthop. 1997;84:473Y476. 13. Kariya Y, Taniguchi K, Yagisawa H, et al. Case report: focal fibrocartilaginous dysplasia: consideration of the healing process. J Pediatr Orthop. 1991;11:545Y547. 14. Kazuki K, Hiroshima K, Kawahara K. Ulnar focal cortical indentation. A previously unrecognized form of ulnar dysplasia. J Bone Joint Surg. 2005;87B:540Y543. 15. Khanna G, Sundaram M, El-Khoury GY, et al. Focal fibrocartilaginous dysplasia: curettage as an alternative to conservative management or more radical surgery. Skeletal Radiol. 2001;30:411Y418. 16. Kohler R. Letter to the editor. J Bone Joint Surg. 1999;81A: 1319Y1348. 17. Landreau-Jolivet I, Pilliard D, Taussig G. Unilateral tibia vara in young children caused by focal fibrocartilaginous dysplasia. Rev Chir Orthop. 1992;78:411Y414.

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18. Levine AM, Drennan JC. Physiological bowing and tibia vara. J Bone Joint Surg. 1982;64A:1158Y1163. 19. Lincoln TL, Birch JG. Focal fibrocartilaginous dysplasia in the upper extremity. J Pediatr Orthop. 1997;17:528Y532. 20. Macnicol M. Focal fibrocartilaginous dysplasia of the femur. J Pediatr Orthop. 1999;8B:61Y63. 21. Marchiodi L, Stilli S, Di Gennaro G. Tibia vara caused by focal fibrocartilaginous dysplasia. Chir Organi Mov. 1995;80:453Y456. 22. Meyer JS, Davidson RS, Hubbard AM, et al. MRI of focal fibrocartilaginous dysplasia. J Pediatr Orthop. 1995;15: 304Y306. 23. Nakase T, Yasui N, Araki N, et al. Florid periosteal reaction and focal fibrocartilaginous dysplasia. Skeletal Radiol. 1998;27: 646Y649. 24. Olney BW, Cole WG, Menelaus MB. Three additional cases of focal fibrocartilaginous dysplasia causing tibia vara. J Pediatr Orthop. 1990;10:405Y407. 25. Postovsky S, Militianu D, Bialik V, et al. Concomitant focal fibrocartilaginous dysplasia of the tibia and eosinophilic

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granuloma of the jaw in a child. J Pediatr Orthop. 2002;11B: 172Y175. Poul J, Straka M. Periostal tethering of growth plates in long bones (focal fibrocartilaginous dysplasia). Acta Chir Orthop Traumatol Cechoslov. 2003;7:182Y186. Ruchelsman DE, Madan SS, Feldman DS. Genu valgum secondary to focal fibrocartilaginous dysplasia of the distal femur. J Pediatr Orthop. 2004;24:408Y413. Santos M, Valente E, Almada A, et al. Tibia valga due to focal fibrocartilaginous dysplasia: case report. J Pediatr Orthop. 2002;11B:167Y171. Smith NC, Carter PR, Ezaki M. Focal fibrocartilaginous dysplasia in the upper limb; seven additional cases. J Pediatr Orthop. 2004;24: 700Y705. Vallcanera CA, Sanguesa NC, Martinez FM, et al. Varus deformity of the distal and of the femur secondary to a focal fibrous lesion. Pediatr Radiol. 1994;24:74Y75. Zayer M. Tibia vara in focal fibrocartilaginous dysplasia. Acta Orthop Scand. 1992;63:353Y355.

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