Table 2 Summary of included studies regarding kyphosis surgery in MPS I patients

Abelin Genevois, JIMD, 2014 [17]

Case series

N = 13

Hurler

Treated between 2003 and 2010

Median age: 8 (range 3.5–15)

Deformity progression and disruption spinal balance

Single- stage circumferential arthrodesis.

Combined anterior and posterior approach (n = 12/13)

Not reported (NR)

Two levels above and 2 levels below the apex (n = 12)

Median 60° (range 30°-90°) / Median 13° (range − 14°-52°)

Significant loss of correction (n = 2) ➔ revision surgery (consecutively to a previous posterior-only fusion)

Mild adjacent segment spondylolisthesis at the upper level in 50%.

Multi-modal EP or at least SSEP

Postoperatively a spine cast for 3 months, in addition full time bracing for 3 months

Median 2.2 (range 0.8–8.7)

Roberts et al., Bone Joint J, 2016 [52]

Case series

N = 7

Hurler

Treated between 2001 and 2013

Median 4.1 (range 2.8–16.8)

The presence of severe, progressive thoracolumbar kyphosis > 40°

Circumferential arthrodesis (n = 3)

Circumferential arthrodesis with posterior instrumentation (n = 4)

T12 (n = 2)

L1 (n = 2)

L2 (n = 1)

L1-L2 (n = 2)

T10-L3 (n = 3)

T10-L4 (n = 2)

T10-L5

T11-L4

Median 78° (range 56°- 110°)/ median 35° (range 0°-65°)

Deep wound infection (n = 1), stable proximal junctional kyphosis(n = 1)

SSEP and MEP

No brace

Median 5.8 (range 3.5–9.3)

Yasin et al., Spine, 2014 [49]

Case series

N = 7

Hurler

Anterior fusion using vascularized rib: mean 3 (range 2.4–3.8; n = 5)

Combined anterior and posterior instrumented fusion: 8 (n = 1)

VEPTR: 4 (n = 1)

NR

Anterior fusion using vascularized rib (n = 5), combined anterior and posterior instrumented fusion (n = 1), VEPTR (n = 1)

NR

NR

Anterior fusion: mean 60° (n = 5)/NR

Combined fusion: 84° /at FU 35°

VEPTR: 87°/ 35°

Anterior only: kyphotic deformity adjacent to the operated segment (n = 5)

NR

Postoperatively: braced until satisfactory healing of the graft on plain radiographs

NR

Tandon et al., J Bone Joint Surg, 1996 [30]

Case series

N = 3

Hurler

2.8

3.5

10.3

NR

Posterior spinal fusion (n = 3)

L2 (n = 2)

NR

80°/NR

56°/NR

40°/NR

At age 12y symptomatic cord compression at T10-T11 (n = 1)

NR

NR

NR

Garrido et al., Eur Spine J, 2014 [53]

Case series

N = 3

Hurler

2.4

2.9

3

NR

Anterior and posterior spinal arthrodesis with segmental pedicle screw instrumentation

L1 (n = 2), Th12(n = 1)

T10-L3

70°/NR

65°/NR

63°/NR

Left lower lobe collapse after extubation (n = 1)

Wound infection (n = 1)

SSEP

Postoperatively: Moulded Thoracolumbar Sacral Orthosis for 3 months

NR

Vellodi et al., Archives of Disease in childhood, 1997 [54]

Case series

N = 7

Hurler

Average age of 7.6 (3.8–10.3) (n = 6)

Prophylactic posterior spinal fusion (n = 6)

Thoracolumbar decompression and fusion for cord compression (n = 1)

NR

NR

NR

NR

NR

NR

NR

Field et al., J Bone Joint Surg, 1994 [6]

Case series

N = 6

Hurler

Average age of 7.6 (3.8 to 10.3)

NR

Posterior spinal fusion (n = 6)

L1 or L2

NR

NR

NR

NR

NR

NR

Polgreen et al., Bone Marrow Transplantation, 2009 [55]

Case series

N = 5

Hurler

Reported in one patient: 5

NR

Spinal fusion (n = 2), anterioposterior spinal fusion (n = 1), posterior spinal fusion (n = 2), anterior spinal fusion (n = 1)

NR

T9 – L3

T10-L2

T11 - L3

T7 -L3

1 not reported

NR

NR

NR

Adjacent kyphosis to operated segment T1-T8

NR

Schmidt et al., Orphanet Journal of Rare diseases, 2016 [33]

Case series

N = 2

Hurler

7.8

14.3

Symptoms, not further specified (n = 1)

Posterior fusion (n = 2)

NR

NR

90°/ NR

(n = 1)

NR

NR

No

NR

Hopwood et al., JIMD, 1993 [56]

Case series

N = 2

Hurler

7

10.3

NR

Posterior spinal fusion (n = 1)

Posterior spinal fusion using the patient’s own left anterior iliac spine plus donor bone. (n = 1)

NR

NR

NR

NR

NR

NR

NR

Malm et al., Acta Paediatrica, 2008 [57]

Case series

N = 2

Hurler

NR

NR

Spinal fusion

Dorsal spinal fusion and ventral spinal fusion

NR

Spinal fusion: T8 and L4

Dorsal spinal fusion: T10 to L4 and ventral spi- nal fusion: T12 - L3

NR

NR

NR

NR

NR

Souillet et al., Bone marrow transplantation, 2003 [58]

Case series

N = 2

Hurler

11.2 and 12.2

3.4

NR

Posterior spinal fusion and anterior spinal fusion (n = 1)

Posterior spinal fusion (n = 1)

NR

NR

NR

NR

NR

No

NR

Stoop et al., JIMD reports, 2012 [45]

Case series

N = 1

Hurler

Treated between 2003 and 2011

NR

NR

Short segment posterior fusion after pedicle subtraction osteotomy of L1

NR

Th12 to L3

80°/ 12°

Kyphosis superior to the spondylodesis; 64°➔ revision of the spondylodesis at the level of T11-L4 and superior extension with a growing rod system; 14°

NR

No.

NR

Yasuda et al., MGM reports, 2015 [59]

Case report

N = 1

Hurler

13

NR

Arthrodesis. Thoracolumbar spinal fusion surgery, dual fusion rods with pedicle screws extended from T5- L3 with overlying graft material

L2

T5-L3

NR

NR

NR

NR

NR

Bekmez et al., J Pediatr Orthop,2016 [43]

Case report

N = 1

Hurler

Treated between 2008 and 2011

8

Deformity progression of > 10 °/ 12 months and disruption of the sagittal balance despite brace treatment

Posterior only

L1

T10- L3

52°/ 15°

Distal junctional Kyphosis of 18 °

SSEP and MEP

Postoperatively, thoracolumbar sacral orthosis, for 4 months.

5.1

Makler et al., Surg Neurol Int, 2017 [60]

Case report

N = 1

Hurler

6

NR

Anterior release and posterior spinal fusion

L1

NR

Complete resolution of gibbus deformity

Preoperative work up revealed a Chiari I malformation and a syringomelia

NR

NR

NR

Dalvie et al., Spine,2001 [44]

Case report

N = 1

Hurler

5

NR

Anterior instrumented correction and fusion

NR

T11-L2

59°/18°

NR

NR

NR

0.4

Pauchard et al., JIMD reports, 2014 [61]

Case report

N = 1

4

NR

Two-stage surgical correction was planned, with initial posterior instrumentation of T12-L2, followed by anterior graft. After first surgery a complication ➔leading to removal of the hardware.

T12

T12-L2

90°/NA

Asymmetric paraplegia with partial sensory loss

SSEP and MEP

NR

NR