Can the caudal extent of fusion in the surgical treatment of scoliosis in Duchenne muscular dystrophy be stopped at lumbar 5?

Abstract

Instrumentation and fusion to the sacrum/pelvis has been a mainstay in the surgical treatment of scoliosis in Duchenne muscular dystrophy (DMD) and is recommended to correct pelvic obliquity. The caudal extent of instrumentation and fusion in the surgical treatment of scoliosis in DMD has remained a matter of considerable debate, and there have been few studies on the use of segmental pedicle screw instrumentation for this pathology. From 2004 to 2007, a total of 28 patients with DMD underwent segmental pedicle screw instrumentation and fusion only to L5. Assessment was performed clinically and with radiologic measurements. All patients had a curve with the apex at L2 or higher preoperatively. Preoperative coronal curve averaged 74°, with a postoperative mean of 14°, and 17°at the last follow-up. The pelvic obliquity improved from 17°pre-operatively to 6°postoperatively, and 6°at the last follow-up. Good sagittal plane alignment was recreated after surgery and maintained long term. In 23 patients with a preoperative L5 tilt of less than 15°, the pelvic obliquity was effectively corrected to less than 10°and maintained by adequately addressing spinal deformity, while five patients with a preoperative L5 tilt of more than 15°had a postoperative pelvic obliquity of more than 15°. Segmental pedicle screw instrumentation and fusion to L5 was effective and safe in patients with DMD scoliosis with a minimal L5 tilt (\15°) and a curve with the apex at L2 or higher, both initially and long term, obviating the need for fixation to the sacrum/pelvis. Segmental pedicle screw instrumentation and fusion to L5 was safe and effective in patients with DMD scoliosis with stable L5/ S1 articulation as evidenced by a minimal L5 tilt of less than 15°, even though pelvic obliquity was significant. There was no major complication. With rigid segmental pedicle screw instrumentation, the caudal extent of fusion in the treatment of DMD scoliosis should be determined by the degree of L5 tilt. This method in appropriate patients can be a viable alternative to instrumentation and fusion to the sacrum/pelvis in the surgical treatment of DMD scoliosis.

Posterior spinal fusion to sacrum in non-ambulatory hypotonic neuromuscular patients: Sacral rod/bone graft onlay method

“…Many recommend fusion to the pelvis in all non-ambulatory patients having spinal fusion [ 6 , 15 , 17 , 18 , 29 ], while those fusing only to L 5 recommend doing so in those with early or milder deformities such as scoliosis <40°, pelvic obliquity <10° (or 15°) and the apex of the curve at L 1 (or L 2 ) and above [ 21 , 25 , 27 , 30 , 34 ]. Alman and Kim [ 27 ] fused 38 DMD patients to L 5 but noted subsequent increase of pelvic obliquity in all of at least 10°, while none of 10 fused to the pelvis showed any increase.…”

“…Alman and Kim [ 27 ] fused 38 DMD patients to L 5 but noted subsequent increase of pelvic obliquity in all of at least 10°, while none of 10 fused to the pelvis showed any increase. Takaso et al [ 34 ] fused 28 patients with DMD to L 5 only in those with the scoliosis apex at L 2 or higher and preferably with a minimal L 5 tilt <15°. They decreased the pre-operative mean 74° curves to 14° post-operatively and 17° at latest follow-up, with pelvic obliquity at 17° pre-operatively and 6° post-operatively and at latest follow-up.…”

“…Several studies have assessed the complex anatomy of the pelvis [1,5,16] and the biomechanical aspects of fusion to the sacrum [1,5,8,16,23,24]. In some neuromuscular patients, particularly with Duchenne muscular dystrophy (DMD), many surgeons have extended the fusion only to L 5 in those with relatively mild deformity, bypassing pelvic concerns [25][26][27][28][29][30][31][32][33][34][35][36].…”

Early limited instrumentation of scoliosis in Duchenne muscular dystrophy: is a single-rod construct sufficient?

“…instrumentation for 20 patients with a correction from 44° to10° [13]. Takaso et al 3 demonstrated pedicle screw instrumentation for 28 patients from T3 to L5, with a 4 correction from 74° to 17° [19]. Patients with a pre-operative Cobb of greater than 40° 5 in this achieved a 44% deformity correction to 22.4°, indicating the ability for a 6 single-rod technique to partially correct and most importantly, stabilize more severe 7 curves.…”

“…Radiographic evaluation of this 17 patient demonstrated evidence of loosening of the iliac crest screw but without 18 pullout. Takaso et al recommended fixation to L5 in patients with an apex at or 19 higher than L2 [19]. Proximal deformity correction causing pelvic obliquity 20 correction without pelvic instrumentation has been demonstrated previously [25].…”