Hip-spine relations and sagittal balance clinical consequences

Junctional spinal disorders in operated adult spinal deformities: present understanding and future perspectives

INTRODUCTION

Junctional spinal disorders have become one of the greatest challenges in spinal deformity surgery. They can occur at any age but are mostly seen in adult deformity surgery and are most often observed as the patient gets older.

DEFINITIONS

Different forms can be individualized according to their types and location: one can observe simple segmental degeneration above or below instrumentation with or without spinal stenosis. Or the situation may be more complex with proximal junctional kyphosis, distal junctional kyphosis and intercalary junctional kyphosis where the junctional kyphosis occurs between two instrumented segments of the spine. Junctional scoliosis may also be observed as a new curve that did not exist after the index surgery.

PATHOPHYSIOLOGY

Many different factors have been described being associated or the cause of junctional problems: old age, increased BMI, osteoporosis, etc. The role of pre-existing and postoperative sagittal imbalance plays a definitive role in their pathogenesis. As well the weakened posterior elements and or fatty degeneration of the posterior muscles are key factors in the occurrence of these problems. Multiple different radiologic parameters to describe and achieve perfect sagittal balance have been described knowing that the pelvic incidence of the patients is the key element that governs lumbar lordosis of the patient and hence the sagittal balance. Away from the spine one has to integrate the issues of the knees and the hips in the presentation of these junctional problems whether they are the cause or one of the consequences of the sagittal malalignment. Likewise the non-instrumented part of the spine (thoracic and or cervical spine) will also play a role in the pathogenesis or prevention of these junctional problems if they are stiff and or autofused along with their respective deformity.

TREATMENT

To prevent the occurrence of such junctional problems some basic surgical rules must be observed, but still lots remain unknown such as how much restoration of lordosis is really necessary, how to create a smoother transition between the instrumented and non-instrumented spine, which metal and where to use it, which implants to use as our widely used pedicle screw system may be one of the causes of these problems. Clinically these junctional problems can be asymptomatic and require only observation, or require revision surgery. Revision will require in most cases decompression of the neural elements, extension of the instrumentation and spinal osteotomies.

CONCLUSION

Definitively the issue of junctional spinal disorder after deformity surgery will require further extensive research to minimize this problem especially in our aging population.

Does standing affect acetabular component inclination and version after THA?

BACKGROUND

Avoiding complications after hip arthroplasty with hard-on-hard bearings, especially metal-on-metal, correlates with the position of the acetabular component. Supine imaging with conventional radiography has traditionally been utilized to assess component inclination (abduction), as well as anteversion, after THA and surface replacement arthroplasty (SRA). However, most adverse events with hard bearings (excessive wear and squeaking) have occurred with loading. Standing imaging, therefore, should provide more appropriate measurements.

QUESTIONS/PURPOSES

We determined whether standing changed standard measurements of acetabular component position using a novel biplanar imaging system compared to traditional supine imaging.

METHODS

We performed simultaneous biplanar standing imaging of the lower extremity with a novel imaging system using low radiation collimated beam on 46 patients who underwent THA (23) or SRA (23). Patients who had previously undergone THA had standard CT scans performed. For patients who underwent SRA, we compared acetabular inclination in the supine versus double-limb and single-limb standing.

RESULTS

Standing anteversion differed from supine anteversion by greater than 5° for 12 of 23 patients who underwent THA (range, 5°-16°). For patients who underwent SRA, 13 of 23 patients exhibited a difference of greater than 3° in inclination between supine and double-limb standing images, and six of 23 patients exhibited a difference of greater than 3° in inclination between supine and single-limb standing images.

CONCLUSIONS

Standing changed the acetabular inclination and version in a substantial percentage of patients undergoing hip arthroplasty.

A systematic review of the clinical effectiveness of EOS 2D/3D X-ray imaging system

PURPOSE

To evaluate the available evidence for the clinical effectiveness of the EOS(®) 2D/3D X-ray imaging system for the evaluation and monitoring of scoliosis and other relevant orthopaedic conditions.

METHODS

A systematic review of studies of EOS(®), compared with standard X-ray film, computed radiography or digital radiography, of patients with orthopaedic conditions was undertaken. Ten electronic databases were searched. The quality of the included studies was assessed and a narrative synthesis undertaken.

RESULTS

Three small, limited quality studies, primarily of children with scoliosis, were identified. No patient health outcomes were reported. Spinal image quality was comparable or better overall with EOS(®). Radiation dose was considerably lower with EOS(®) than X-ray film or computed radiography; the mean entrance surface dose was over five times lower with EOS(®) for the posteroanterior spine radiograph and over six times lower for the lateral spine radiograph.

CONCLUSIONS

The available clinical evidence for EOS(®) is limited to establishing its basic technical ability. The technical advancements associated with EOS(®) (the ability to generate a full body scan and to construct a three-dimensional model from synchronously acquired lateral and posteroanterior images) have not been evaluated in terms of their ability to improve patient outcomes. Whilst radiation dose is a concern for orthopaedic patients who require repeated imaging, it is difficult to quantify the reductions in radiation dose seen with EOS(®) in terms of patient health benefits. Clinical studies that investigate the impact of EOS(®) on patient management are required.

Pelvic tilt and trunk inclination: new predictive factors in curve progression during the Milwaukee bracing for adolescent idiopathic scoliosis

INTRODUCTION

Previous studies had shown that sagittal spinal and pelvic morphology may be associated with the development and progression of adolescent idiopathic scoliosis, but the predictive value of initial spinal and pelvic morphology on the curve progression during brace treatment is unknown. The objective of this study was to evaluate the relation between initial spinopelvic morphology and the risk of curve progression of adolescent idiopathic scoliosis with the Milwaukee brace.

MATERIALS AND METHODS

From 2002 to 2007, adolescent idiopathic scoliosis (single thoracic curve with apex at or above T8) was treated with the Milwaukee brace in 60 girls. Initial standing, full-length lateral radiographs were made and seven sagittal radiographic parameters of spinal and pelvic alignment were measured. Patients were followed until skeletal maturity or progression of Cobb angle >45°. The progression of curve was defined as an increase of Cobb angle ≥6° at final follow-up or progression to surgery during brace treatment.

RESULTS

The 45 patients (75.0 %) who had successful control of curve progression were initially significantly more skeletally mature (higher mean Risser sign) than the 15 patients (25.0 %) who had curve progression. The initial mean Cobb angle was similar between the stable and progressed groups. The mean pelvic tilt, T1-spinopelvic inclination and T9-spinopelvic inclination angles were significantly greater in the stable group than in the progressed group and these three angles were independent predictors for curve progression during brace treatment. There were no significant differences between the stable and progressed groups in initial mean pelvic incidence, sacral slope, thoracic kyphosis or lumbar lordosis angles. Pre-bracing pelvic tilt ≤-0.5° was strongly predictive and T1-spinopelvic inclination ≤3.5° was moderately predictive of curve progression during the Milwaukee brace treatment.

CONCLUSIONS

Initial pelvic tilt and spinopelvic inclination angles may predict the curve progression and treatment outcome of adolescent idiopathic scoliosis with the Milwaukee brace.