Migration and Spontaneous Extrusion of a Lumbar Spinal Fusion Rod From the Gluteal Region.

Instrumented fusion with rods and pedicle screws is often performed for the surgical treatment of adult spinal deformity (ASD). One of the complications of such long construct fusions is that of pseudoarthrosis, which can present with implant loosening, failure, and rod breakage. However, migration and spontaneous extrusion of the rod is relatively rare and has yet to be reported in the literature. We report a gentleman with previous long construct instrumented fusion done six years ago for ASD, who presented with gluteal pain. Radiographs revealed rod breakage and caudal migration towards the left gluteal region. He subsequently reported spontaneous extrusion of the broken rod through the gluteal skin, without the need for surgical removal. This case is reported for its rarity and to raise awareness about the rare occurrence of rod migration after breakage that can lead to potential complications if left unattended.

Pedicle Screw Designs in Spinal Surgery: Is There a Difference? A Biomechanical Study on Primary and Revision Pull-Out Strength.

STUDY DESIGN: An experimental laboratory-based biomechanical study. OBJECTIVE: The objective of this study was to evaluate, in a synthetic bone model, the difference in primary and revision pull-out strength using pedicle screws of different thread designs. SUMMARY OF BACKGROUND DATA: Over the past few decades, there has been a growing interest in optimizing the screw pull-out strength using various screw designs (single-thread, mixed-thread, dual-thread). Although primary pull-out strength has been studied previously, little is known about revision pull-out strength of different pedicle screws. METHODS: The pull-out strengths of three different pedicle screw designs (single-thread, mixed-thread, dual-thread) were tested in standardized polyurethane foam in three sequences. Sequence 1: A 6.5 mm screw was inserted into the foam block and the primary pull-out strength measured. Sequence 2: A 6.5 mm screw was inserted, removed, and then reinserted into the same foam block. The revision pull-out strength was then measured. Sequence 3: A 6.5 mm screw was inserted, removed and a 7.5-mm screw of the same thread design was reinserted. The revision pull-out strength was then measured. RESULTS: The primary pull-out strength was similar across screw designs, although dual-thread screws showed higher primary pull-out strength (2628.8 N) compared to single-thread screws (2184.4 N, P < 0.05). For revision pull-out strength, the mixed-thread screws had significant reduction in revision pull-out strength of 18.6% (1890.2 N, P = 0.0173). Revision with a larger diameter screw improved the pull-out strength back to baseline. Single and dual-thread screws showed no significant reduction in revision pull-out strength. CONCLUSION: The dual-threaded screws provided the strongest primary pull-out strength for spinal fixation. The mixed-thread screws, however, had the poorest revision pull-out strength, decreasing by 18.6% compared to other screw designs. In cases in which mixed-threaded screws have to be revised (at the index or revision surgery), surgeons should consider the use of larger diameter screws to improve the pull-out strength. LEVEL OF EVIDENCE: 5.

Megacolon as an atypical presentation of cervical myelopathy.

A 61-year-old gentleman was admitted with progressive symptoms of cervical myelopathy. An MRI performed showed severe compression from C3-6 with cord signal changes. He was offered surgical intervention but the operation had to be delayed because of worsening abdominal distension. X-rays performed showed a severely dilated colon measuring >12 cm. A CT did not show any obstructive cause. He was managed conservatively for more than 2 weeks but did not improve. As his symptoms continued to worsen, a decision was made to proceed with a C3-6 posterior decompression and fusion, despite the theoretical risk of bacterial translocation predisposing him to infection. Postoperatively, he improved significantly. Interestingly, his abdominal distention had also improved and a repeat X-ray showed complete resolution of the megacolon. In conclusion, this case highlights that long standing cervical cord compression may be a cause for an "atonic" megacolon. Once all causes of intestinal obstruction are excluded, surgical decompression of the cervical stenosis should proceed, and need not be delayed for the megacolon resolve spontaneously.

Infection rates in Singaporeans with and without complicated diabetes after ankle fracture surgery.

PURPOSE: To compare infection rates in Singaporeans with and without complicated diabetes after ankle fracture surgery. METHODS: Medical records of 18 men and 27 women aged 38 to 84 (mean, 62) years with complicated (n=12) or uncomplicated (n=33) diabetes who underwent internal fixation for closed ankle fractures were reviewed. Complicated diabetes was defined as having end organ dysfunction. The control of diabetes was categorised as good (n=19), fair (n=10), and poor (n=16), based on HbA1c level within 4 months before or after surgery. Patients were followed up at weeks 2, 6, 12, and 24, with bone union as the end point. RESULTS: The mean follow-up period was 9 (range, 4-12) months. 2 (6%) of 33 patients with uncomplicated diabetes and 6 (50%) of 12 patients with complicated diabetes developed superficial or deep infection. No patient died or underwent amputation secondary to infection. In multivariable logistic regression analysis after adjusting for co-morbidities, only complicated diabetes was a risk factor for postoperative infection (odds ratio=11.85, p=0.01). The odds of postoperative infection was 11.85 times higher in patients with complicated diabetes than with uncomplicated diabetes. CONCLUSION: In patients with complicated diabetes, careful patient selection, peri-operative precaution, and closer monitoring are recommended if surgery is necessary.