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

Current Concepts in the Orthopaedic Management of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD), a genetic condition marked by progressive muscle degeneration, presents notable orthopaedic challenges, especially scoliosis, which deteriorates patients' quality of life by affecting sitting balance and complicating cardiac and respiratory functions. Current orthopaedic management strategies emphasize early intervention with corticosteroids to delay disease progression and the use of surgical spinal fusion to address severe scoliosis, aiming to enhance sitting balance, alleviate discomfort, and potentially extend patient lifespan. Despite advancements, optimal management requires ongoing research to refine therapeutic approaches, ensuring improved outcomes for patients with DMD. This review synthesizes recent findings on surgical and nonsurgical interventions, underscoring the importance of a multidisciplinary approach tailored to the dynamic needs of patients with DMD.

Utilizing robotic-assisted navigation for pelvic instrumentation in pediatric patients with neuromuscular scoliosis: a technical note and case series

Pelvic fixation is commonly used in correcting pelvic obliquity in pediatric patients with neuromuscular scoliosis and in preserving stability in adult patients with lumbosacral spondylolisthesis or instances of traumatic or osteoporotic fracture. S2-alar-iliac screws are commonly used in this role and have been proposed to reduce implant prominence when compared to traditional pelvic fusion utilizing iliac screws. The aim of this technical note is to describe a technique for robotically navigated placement of S2-alar-iliac screws in pediatric patients with neuromuscular scoliosis, which (a) minimizes the significant exposure needed to identify a bony start point, (b) aids in instrumenting the irregular anatomy often found in patients with neuromuscular scoliosis, and (c) allows for greater precision than traditional open or fluoroscopic techniques. We present five cases that underwent posterior spinal fusion to the pelvis with this technique that demonstrate the safety and efficacy of this procedure.

Fusion to the sacrum or pelvis increases survival in patients with Duchenne muscular dystrophy

This commentary is on the original article by Arshad and Tsirikos on pages 187–194 of this issue.

Distal fusion level, complications, and reoperations in individuals with cerebral palsy undergoing surgery for scoliosis

PURPOSE

To compare radiological outcome, complications and reoperations in individuals with cerebral palsy and scoliosis fused to the fifth lumbar vertebra (L5), the sacrum, or the ilia.

METHODS

208 individuals were identified in the national quality registry Swespine. Lowest level of fusion was L5 in 58, the sacrum in 92, and the ilia in 58 individuals. A subanalysis on 58 matched pairs operated to L5 or the pelvis (sacrum = 42, ilia = 16) with similar pelvic obliquity (± 5°) was performed.

RESULTS

The median (interquartile range) follow-up for the last radiograph was 1.7 (1.7) years and for reoperations 6.0 (5.9) years. Preoperatively, median Cobb angle of the major curve was 65° (23°) in the L5 group, 68° (28°) in the sacrum group, and 78° (25°) in the ilia group (p = 0.006). Preoperative median pelvic obliquity according to Maloney was 16° (19°), 21° (13°), and 27° (28°), respectively (p = 0.004). Immediate postoperative Cobb angles were 28° (18°), 28° (16°), and 32° (25°), respectively (p = 0.11). Immediate postoperative pelvic obliquity was 7° (10°), 7° (8°), and 8° (10°), respectively (p = 0.28). The median change in pelvic obliquity from the first to the last postoperative radiograph was - 5° (7°), - 3° (6°), - 3° (6°), respectively (p = 0.55). 7 (12%), 11 (12%), and 7 (12%) patients required at least one reoperation (p = 1.0), respectively. In the matched analysis, no significant differences in the radiological outcomes were found (all p ≥  0.38).

CONCLUSIONS

Maintained curve and pelvic obliquity correction with no significant difference in complication and reoperation rates were found irrespective of distal fusion level.

The indication of fusion to the pelvis in neuromuscular scoliosis is based on the underlying disease rather than on pelvic obliquity

INTRODUCTION

The decision to instrument to L5 or ilium, in NMS, is usually based on radiologic factors, including pelvic obliquity (PO) > 15°, apex of curvature < L3, and Cobb angle > 60°. Since scoliosis in these patients is caused by a neurologic disease, we based our decision to stop at L5 on the presence of spasticity or flaccidity.

PATIENTS & METHODS

The senior author did 109 primary fusions in NMS. Of those with DMD or SMA only 16% were instrumented to the ilium. The main factor for our decision was the correction potential of the truncal shift and PO in the supine traction radiographs and the absence of severe spasticity.

RESULTS

The 57 patients with DMD/SMA had a mean preoperative curvature of 68°, PO of 17°, and truncal shift of 20°. 74% should have been instrumented to the pelvis, but only 16% were. Those instrumented shorter as the rule, were corrected from 74° to 26° and had a postoperative PO of 8°. There was no significant difference in postoperative correction and PO compared to those instrumented to L5 on standard protocol. Subsequent extension to the pelvis was needed in 1 CP patient. There were no significant changes after 2 years. Of the 20 patients instrumented to the pelvis 11 had cerebral palsy and a preop curvature of 89°, a PO of 21° and a truncal shift of 25°.

DISCUSSION

The decision on instrumentation length should take flexibility and disease into consideration. If the trunk is centred over the pelvis, deterioration will not occur in absence of spasticity.

Distal fusion in Duchenne scoliosis: the relevance of preoperative pelvic obliquity. A case series study

PURPOSE

The aim of this study was to determine clinical and radiographic outcomes for Duchenne Muscular Dystrophy (DMD) patients who underwent posterior spinal fusion from T2/3 to L5 (without pelvic fixation), at this single centre.

METHODS

From January 2012 to January 2020, 29 consecutive DMD scoliosis patients underwent posterior spinal fusion using pedicle screws from T2/3 to L5 in a single center with a minimum of 3 years follow-up (FU). Radiologic measurements and chart review were performed.

RESULTS

Twenty nine patients aged 14 ± 1.5 years were included. No patient was lost to FU. All patients had significant correction in Cobb angle, pelvic obliquity (PO) and lumbar lordosis (LL), without loss of correction at last FU. The mean values for preoperative, immediate postoperative and last FU were CA 62o, 15o and 17o, PO: 21o, 8o and 9o; and LL 10o, -41o and -41o respectively. Correction in CA was independent of any variable analysed including implant density, rod diameter, traction, or bone density. Regarding PO, it was inversely related to age and independent of all other variables. Factors associated with postoperative complications were age and respiratory function.

CONCLUSIONS

It appears from our results that pelvic fixation might not always be required in DMD scoliosis surgery, when using pedicle screws with lowest instrumented vertebra at L5. However, larger preoperative PO values can be related with residual PO. It seems that probably related to the underlying condition, early surgery may decrease incidence of complications.

LEVEL OF EVIDENCE

IV.

Posterior Spinal Fusion Surgery for Neuromuscular Disease Patients with Severe Scoliosis Whose Cobb Angle Was over 100 Degrees

Background and objectives: Patients with neuromuscular diseases usually have progressive neuromuscular scoliosis (NMS), requiring invasive surgery. Some patients present with severe scoliosis at the time of consultation and are difficult to treat. Posterior spinal fusion (PSF) surgery combined with anterior release and pre- or intraoperative traction would be effective for severe spinal deformities but would be invasive. This study aimed to evaluate the outcomes of PSF-only surgery for patients with severe NMS with a Cobb angle > 100°. Materials and Methods: Thirty NMS patients (13 boys and 17 girls; mean age 13.8 years) who underwent PSF-only surgery for scoliosis with a Cobb angle > 100° were included. We reviewed the lower instrumented vertebra (LIV), duration of surgery, blood loss, perioperative complications, preoperative clinical findings, and radiographic findings, including Cobb angle and pelvic obliquity (PO) in the sitting position pre- and postoperatively. The correction rate and correction loss of the Cobb angle and PO were also calculated. Results: The mean duration of surgery was 338 min, intraoperative blood loss was 1440 mL, preoperative %VC was 34.1%, FEV1.0 (%) was 91.5%, and EF was 66.1%. There were eight cases of perioperative complications. The Cobb angle and PO correction rates were 48.5% and 42.0%, respectively. We divided the patients into two groups: the L5 group, in which the LIV was L5, and the pelvis group, in which the LIV was the pelvis. The duration of surgery and PO correction rate in the pelvis group were significantly higher than those in the L5 group. Conclusions: Patients with severe NMS demonstrated severe preoperative restrictive ventilatory impairments. PSF surgery without anterior release or any intra-/preoperative traction showed satisfactory outcomes, including acceptable scoliosis correction and improved clinical findings, even in patients with extremely severe NMS. Instrumentation and fusion to the pelvis for severe scoliosis in patients with NMS showed good PO correction and low correction loss of Cobb angle and PO, but a longer duration of surgery.

When Should Instrumentation to the Pelvis be Considered in Minimally Ambulatory Adolescents With Neuromuscular Scoliosis?

INTRODUCTION

The goal of neuromuscular scoliosis (NMS) surgery is to improve sitting balance, facilitate daily care, and alleviate pain. In nonambulatory patients, where sitting balance is key, fusion to the pelvis is usually required. However, in minimally ambulatory patients, fusion to the pelvis remains controversial, and there is considerable practice variability in this patient population. The purpose of this study is to evaluate and summarize the available evidence regarding fusion constructs in minimally ambulatory patients with NMS and to provide expert opinion regarding when fusion to the pelvis should be considered.

METHODS

A search of the English literature was performed using PubMed to identify papers pertaining to patients with NMS treated with instrumented posterior spinal fusion. Papers published before 2000, case reports, and level V evidence were excluded.

RESULTS

The authors identified 8 studies for review. The majority included both nonambulatory and minimally ambulatory patients. Structured review of the literature demonstrated fusion to the pelvis may allow for greater curve and pelvic obliquity correction, but it is also associated with increased blood loss and operative time. There is no evidence that fusing to the pelvis decreases ambulatory status in minimally ambulatory patients.

CONCLUSIONS

In minimally ambulatory patients with NMS, fusion short of the pelvis may be considered in patients with adequate head control without the presence of hip subluxation or dislocation and when pelvic obliquity is <15 degrees. Fusion to the pelvis is recommended in patients who do not meet these criteria.

Hip Dislocation After Correction for Scoliosis in an Adolescent with Angelman Syndrome: A Case Report

CASE

Although scoliosis is common in Angelman syndrome (AS), there are no reports of hip dislocation as a complication of scoliosis surgery. We experienced a case of hip dislocation after posterior spinal instrumentation and fusion from T4 to L5 because of scoliosis progression in an adolescent girl with AS. Postoperatively, posterior dislocation of the left hip occurred; after closed reduction, instability remained. Thus, periacetabular osteotomy was performed (left hip), with good clinical outcomes.

CONCLUSION

Especially in cases of abnormal muscle tone, a loss of spinal flexibility because of extensive spinal fixation may result in secondary pathologies of the hip joint.

Limitations of posterior spinal fusion to L5 for flaccid neuromuscular scoliosis focusing on pelvic obliquity

STUDY DESIGN

Retrospective comparison based on the degree of pelvic obliquity (PO).

PURPOSE

To assess the controversial indications for and limitations of ending the instrumentation for posterior spinal fusion (PSF) at L5 in patients with flaccid neuromuscular scoliosis (fNMS).

METHODS

We reviewed the cases of 45 patients with progressive spinal deformity as a result of fNMS treated by PSF to L5 and followed for an average of 4 years postoperatively with adequate clinical and radiological data. Anterior-posterior and lateral whole spine radiographs were evaluated. We divided patients into two groups based on the degree of pelvic obliquity (PO) at the final follow-up. Radiographic data from the two groups were analyzed to identify the indications and limitations of this surgical method focusing on PO.

RESULTS

Preoperatively, there were significant differences between the two groups in Cobb angle, PO, thoracolumbar kyphosis, and lumbar lordosis (LL) while sitting; Cobb angle and LL while supine (Supine Cobb, and Supine LL); and major curve flexibility. Multivariate logistic regression analysis identified Supine Cobb and Supine LL as independent risk factors for residual PO at the final follow-up (Supine Cobb: odds ratio, 1.1; 95% confidence interval 1.0-1.2, Supine LL: odds ratio, 0.9; 95% confidence interval 0.8-1.0).

CONCLUSION

Patients with larger preoperative Cobb angle and smaller LL while supine may not achieve adequate spine and pelvic correction and this may lead to deterioration in the PO over time, even after spinal fusion ending at L5.

Surgical Correction of Scoliosis in Patients With Duchenne Muscular Dystrophy: 30-Year Experience

BACKGROUND

The natural history of scoliosis in Duchenne muscular dystrophy (DMD) is progressive and debilitating if neglected. The purpose of this study was to evaluate outcomes related to spinal deformity surgery in patients with DMD over a 30-year period.

METHODS

This was a single center retrospective study of all operatively treated scoliosis in DMD patients over 30 years. Minimum follow-up was 2 years. Owing to changes in instrumentation over time, patients were divided into 2 groups: Luque or pedicle screws (PS) constructs. Radiographic, perioperative variables, pulmonary function test (preoperatively and postoperatively), and complication data were evaluated.

RESULTS

There were 60 subjects (Luque: 47, PS: 13). The Luque group was on average 13 years old, 53 kg, and had 7 years of follow-up. Coronal Cobb was 31±12 degrees preoperatively, 16±11 degrees at first postoperatively, and 21±15 degrees at final follow-up (P≤0.001). Pelvic obliquity was 7±6 degrees preoperatively, 5±5 degrees at first postoperatively (P=0.43), and 5±4 degrees at final follow-up (P=0.77). The majority of this group was fused to L5 (45%) or the sacrum (49%). The PS group was on average 14 years old, 65 kg, and had 4 years of follow-up. Coronal Cobb was 43±19 degrees preoperatively, 12±9 degrees at first postoperatively (P≤0.001), and 12±8 degrees at final follow-up. Pelvic obliquity was 6±5 degrees preoperatively, 3±3 degrees at first postoperatively (P=0.06), and 2±2 degrees at final follow-up (P=0.053). The majority were fused to the pelvis (92%). Both groups' pulmonary function declined with time. Both groups had high complication rates (Luque 68%; PS group 54%). The Luque group had more implant-related complications (26%); the PS group had a higher rate of early postoperative infections (23%).

CONCLUSIONS

Over a 30-year period of operative treatment of scoliosis in DMD, both PS constructs and Luque instrumentation improved coronal Cobb. The PS group had improved and maintained pelvic obliquity. Both groups had high complication rates.

LEVEL OF EVIDENCE

Level IV-therapeutic.

Spinal correction in patients with Fukuyama congenital muscular dystrophy

BACKGROUND

Fukuyama congenital muscular dystrophy (FCMD) is one of the most common congenital progressive muscular dystrophies in Japan. Some patients develop a severe spinal deformity that leads to an unstable sitting position or pain. Since 2008, we have treated FCMD using posterior spinal fusion. This study reports the short-term clinical and radiographic results of posterior spinal correction and fusion in FCMD.

METHODS

We retrospectively reviewed 11 consecutive FCMD patients, average age 13 years old, treated with posterior spinal instrumentation and fusion between 2008 and 2015. All patients were non-ambulatory and complained about difficulty sitting and/or buttock pain. Posterior spinal correction was performed to halt progression of spinal deformity and improve their sitting balance. Assessment was performed clinically and with radiological measurements at a mean follow up period of 34.5 months. To evaluate functional status of patients after surgery objectively, a Muscular Dystrophy Spine Questionnaire (MDSQ) was obtained at the final follow up.

RESULTS

The mean height, weight and body mass index of the patients were 144.1 ± 11.8 cm, 26.5 ± 8.7 kg and 12.5 ± 2.6 kg/m². The average intensive care unit stay was 1.3 days. Five patients had complications related to surgery. The mean preoperative major Cobb angle and pelvic obliquity (PO) were 65.5 ± 41.7° and 31.4 ± 28.9°, respectively, were corrected to 34.4 ± 29.7° and 20.0 ± 18.7° just after the surgery, and were maintained at 35.1 ± 29.9° and 20.5 ± 21.1° at the final follow up. The average MDSQ score was 35.8 ± 13.2 at the final follow up.

CONCLUSION

Posterior spinal correction and fusion in FCMD achieved good radiographic results and clinical improvement with acceptable perioperative complications. FCMD patients are mentally impaired and physically small, so post-operative observation and close attention to perioperative complications are critical.

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

BACKGROUND CONTEXT

Correction of scoliotic deformity in Duchenne muscular dystrophy (DMD) is performed to maintain adequate seating posture and facilitate comfort. Delaying surgery can predispose to greater morbidity as DMD exhibits progressive cardiorespiratory compromise. Early limited instrumentation may provide a solution to optimize patients with this condition.

PURPOSE

The aim was to assess outcomes for a cohort of DMD patients who had posterior single-rod instrumentation and bilateral spinal fusion of their neuromuscular scoliotic deformity.

STUDY DESIGN

This was a retrospective cohort study.

PATIENT SAMPLE

Forty-one consecutive patients were included.

OUTCOME MEASURES

Perioperative morbidity, seating outcomes, pulmonary function, deformity correction, and instrumentation integrity were assessed.

METHODS

Clinical and radiographic review was performed.

RESULTS

No perioperative mortality or neurologic deterioration was encountered. Total surgical time was 96 minutes, mean total blood loss was 2.3l, mean intensive care unit stay was 41 hours, and overall length of stay was 11 days. Mean Cobb angle improved from 24.3° to 15.6°, pelvic obliquity improved from 7° preoperatively to 5° postoperatively. Three patients had failure of fixation at a mean of 3.5 years. Forced vital capacity was 60% preoperatively and 56% at 1 year, forced expiratory volume/1 second was 67% and 62% at 1 year postoperatively. Seating and posture was satisfactory in all these patients.

CONCLUSIONS

The authors advocate early operative intervention using a limited instrumentation technique in patients with DMD to maintain seating balance and minimize perioperative morbidity.

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

PURPOSE

A retrospective study involving 65 non-ambulatory patients with hypotonic neuromuscular scoliosis has assessed the effectiveness of a sacral rod/bone onlay technique for extending spinal fusion to the sacrum.

METHODS

To extend posterior spinal fusion to the sacrum, we used either 1 Harrington rod and 1 Luque L rod with sublaminar wires in 14 patients (Group 1) or two rods with sublaminar wires in 51 patients (Group 2) along with abundant autograft and allograft bone covering the ends of the rods.

RESULTS

Diagnoses were Duchenne muscular dystrophy 53, spinal muscular atrophy 4, myopathy 3, limb girdle muscular dystrophy 2, infantile FSH muscular dystrophy 1, cerebral palsy 1, and Friedreich ataxia 1. Mean age at surgery was 14.3 years (±2.2, range 10.9-25.2). Radiographic follow-up (2 years post-surgery or greater) was 6.4 years (±4.4, range 2-25.3). Using the onlay technique, all patients fused with no rod breakage or pseudarthrosis. For the entire series, the mean pre-operative scoliosis was 54.7° (±31.1, range 0°-120°) with post-operative correction to 21.8° (±21.7, range 0°-91°) and long-term follow-up 24° (±22.9, range 0°-94°). For pelvic obliquity, pre-operative deformity was 17.3° (±11.3, range 0°-51°) with post-operative correction to 8.9° (±7.8, range 0°-35°) and long-term follow-up 10.1° (±8.1, range 0°-27°). Five required revision at a mean of 3.3 years post-original surgery involving rod shortening at the distal end. One of these had associated infection.

CONCLUSION

Lumbosacral stability and long-term sitting comfort have been achieved in all patients. Problems can be minimized by positioning the rods firmly against the sacrum at the time of surgery with a relatively short extension beyond the L5-S1 junction. The procedure is valuable in hypotonic non-ambulatory neuromuscular patients whose immobility enhances the success rate for fusion due to diminished stress at the lumbosacral junction. It is particularly warranted for those with osteoporosis and a small, deformed pelvis. Considerable weight loss and lengthy rods not closely apposed to the sacrum at the time of surgery played a major role in patients needing revision.