Changes in sagittal spinal alignment and pelvic parameters in patients undergoing a total hip arthroplasty

BACKGROUND: The relationship of the spine to the pelvis has been widely studied. However, the role of the hip joint in maintaining sagittal balance remains poorly understood. We aimed to examine if radiographic sagittal spine and pelvic parameters change after Total Hip Arthroplasty (THA), and to evaluate the postural effects on these parameters in standing, sitting, and supine positions. MATERIALS AND METHODS: 36-inch anteroposterior and lateral standing, sitting and supine radiographs in patients undergoing a unilateral THA pre and post THA were obtained. Standard pelvic and spinal alignment parameters were measured. RESULTS: There were 31 cases with complete radiographic information. Pre-THA SVA was 35.7mm, improving to 24.9mm post-THA. Lumbar lordosis was 50.6° standing and 33.8° sitting; maintained post-THA at 50.6° standing and 36.4°sitting. Pelvic incidence remained unchanged in all positions pre and post-THA (49.1° to 51.2°). Pre-THA sacral slope was 36.9° standing, 23.3° sitting and 40.9° supine. This was maintained post-THA (36.0° standing, 22.9°sitting and 39.7°supine). Pre-THA pelvic tilt was 14.5° standing, 27.8° sitting and 8.8° supine. This was maintained post-THA (15.3° standing, 28.2°sitting and 12.0°supine). Lumbar lordosis was significantly less, and pelvic tilt was significantly greater in sitting position than in standing and supine positions, representing the pelvis moves posteriorly as a patient goes to a seated position,CONCLUSION: This study establishes baseline values for the normal standing, sitting and supine sagittal spine and pelvic parameters patient’s undergoing THA. THA does not seem to lead to substantial changes in sagittal spine and pelvic radiographic parameters

Lumbar fusion outcomes in patients with rheumatoid arthritis

Although outcomes after cervical fusion in rheumatoid arthritis (RA) patients are widely published, outcomes of lumbar fusion in RA patients has not been reported. Ninteen patients with RA, identified using ICD-9 and CPT codes, who underwent instrumented posterolateral lumbar fusion were matched for age, gender, smoking status, date, and level of surgery to a contemporaneous non-RA group. Medical records and radiographs were reviewed by the primary author who had no role in the treatment of these patients. The average age was 64 years in the RA group and 65 years in the non-RA group. The male to female ratio was 2:17 and 1:18, respectively. There were three smokers and two diabetics in each group. An average of 1.5 levels was fused in each group. Average follow-up was 24 and 27 months, respectively. In the RA group, 15 patients were taking DMARDs with 7 of those also taking oral steroids; 4 patients were taking NSAIDs only. There were seven complications (37%) in the RA group versus four (21%) in the non-RA group; wound infections in three patients (16%) in the RA group versus one (5%) in the non-RA group; and non-union in two patients (11%) in the RA group versus three (16%) in the non-RA group. Clinical outcomes were similar between the two groups with 74% of patients achieving good to excellent results in the RA group compared to 63% in the non-RA group (p = 0.692). Surgeons and their RA patients who undergo an instrumented lumbar fusion can expect a slightly higher complication rate than patients without RA which may be related to osteopenia and immunosuppression

Intra- and inter-observer reliability of determining radiographic sagittal parameters of the spine and pelvis using a manual and a computer-assisted methods

Sagittal imbalance is a significant factor in determining clinical treatment outcomes in patients with deformity. Measurement of sagittal alignment using the traditional Cobb technique is frequently hampered by difficulty in visualizing landmarks. This report compares traditional manual measurement techniques to a computer-assisted sagittal plane measurement program which uses a radius arc methodology. The intra and inter-observer reliability of the computer program has been shown to be 0.92–0.99. Twenty-nine lateral 90 cm radiographs were measured by a computer program for an array of sagittal plane measurements. Ten experienced orthopedic spine surgeons manually measured the same parameters twice, at least 48 h apart, using a digital caliper and a standardized radiographic manual. Intraclass correlations were used to determine intra- and interobserver reliability between different manual measures and between manual measures and computer assisted-measures. The inter-observer reliability between manual measures was poor, ranging from −0.02 to 0.64 for the different sagittal measures. The intra-observer reliability in manual measures was better ranging from 0.40 to 0.93. Comparing manual to computer-assisted measures, the ICC ranged from 0.07 to 0.75. Surgeons agreed more often with each other than with the machine when measuring the lumbar curve, the thoracic curve, and the spino-sacral angle. The reliability of the computer program is significantly higher for all measures except for lumbar lordosis. A computer-assisted program produces a reliable measurement of the sagittal profile of the spine by eliminating the need for distinctly visible endplates. The use of a radial arc methodology allows for infinite data points to be used along the spine to determine sagittal measurements. The integration of this technique with digital radiography’s ability to adjust image contrast and brightness will enable the superior identification of key anatomical parameters normally not available for measurement on traditional radiographs, improving the consistency of sagittal measurement