Long-term adjacent segment degeneration at average 21-year follow-up of posterior instrumented fusion for adolescent idiopathic scoliosis.

INTRODUCTION: Posterior instrumented fusion for progressive adolescent idiopathic scoliosis (AIS) is generally considered to have good outcomes, but very long-term reviews are rare. Data on adjacent segment degeneration (ASD) following posterior instrumented thoracic fusion for AIS are lacking. The primary aim was to assess the incidence of ASD and to correlate this with radiographic measures and patient-reported outcome measures (PROMs). The secondary aim was to assess maintenance of curve correction at very long-term follow-up. METHODS: This single-surgeon consecutive case series of 47 AIS patients was identified from a prospectively collated dataset. As the primary outcome, ASD was assessed radiographically using the Mimura grading system. Pulmonary function tests and PROMs were assessed along with secondary radiographic outcome measures. RESULTS: Radiographic follow-up was achieved in 77% (36/47) of patients at an average of 21 years (range, 16.5-26.5 years) after surgery. Radiographic evidence of ASD was seen in 64%. PROMs showed a mean Oswestry disability index of 12.1% with an overall Scoliosis Research Society 22 score averaging at 3.7 out of 5. The Coronal Cobb Angle was corrected from an average of 57° preoperatively to 19° immediately postoperatively, deteriorating to 22° at final review, maintaining a 61% curve correction. CONCLUSIONS: Radiographic evidence of ASD was found in 64% of the cohort. The patient-reported outcome measures were good, with few limitations to activities.

Intraoperative contamination and space suits: a potential mechanism.

The body exhaust suit (BES) of Charnley creates 'negative pressure' inside the gown using intake/outtake tubing. Modern 'space suit' (SS) systems incorporate helmet-based intake fans, which use the hood material as a filter and create 'positive pressure' inside the gown. While early studies of BES demonstrate a clear reduction in infection rates following arthroplasty, recent clinical data on SS use has paradoxically reported a marked increase. We hypothesized that the positive pressure inside the gown could carry air and particles via the unsealed area around the surgeon's cuff into the operative field. We performed 12 simulated operations with the surgeons hands covered in fluorescent 0.5 micron powder that approximates the size of shedded skin squames. Photographs under UV light and air particle counts were used to compare potential contamination rates between SS and conventional gowns using a standardised scoring system. The highest powder migration was seen in the SS group with a score of 15.3 out of 28. No powder migration was seen in the standard gown group (p = 0.028). This study provides a plausible explanation for the increase in infection rates seen with SS use. We recommend SS be considered for personal protection only and supplemented with sealant tape around the inner glove.

An in vivo kinematic study of the reverse shoulder joint replacement.

As of now few studies have investigated the kinematics of the reverse shoulder arthroplasty (RSA) in patients and none on how this may be affected by glenosphere shape or size. There have been a few biomechanical studies evaluating the RSA. These studies have modelled and estimated that a large amount of movement is available at the glenohumeral articulation, when using a standard glenosphere, with even more movement using an eccentric or large glenosphere. However, the in vivo kinematics of the RSA has not been determined. Therefore, we conducted a study to assess the in vivo kinematics of the RSA and to observe what affect the glenosphere type would have. Areas of specific interest were the maximal abduction, the ratio of glenohumeral to scapulothoracic motion, and an observation of what occurs during notching. We obtained 18 patients who had high functioning reverse shoulder replacements, with surgery greater than a year ago. We assessed the kinematics, first with fluoroscopy, where we obtained 5 images at various levels of abduction. Then, at the same sitting, electromagnetic sensors were placed on the lateral epicondyle, acromion and base of the scapular spine. These sensors were attached to the Polhemus 3space tracking system that allowed us to measure the movement of the humerus and the movement of scapula during cycles of abduction. Our results demonstrated that the RSA is able to reproduce kinematics similar to the quoted physiological kinematics. Eccentric glenospheres had higher abduction and are less likely to experience superior impingement of the humerus on the under surface of the acromion or develop the more severe stages of notching. The range of movement in our study was highest in the 36-mm eccentric glenospheres and lowest in the 44-mm concentric glenospheres. Notching, although not associated with a poor outcome score or a lower range of movement was more prevalent in patients whose first phase of movement, consisted mainly of scapulothoracic motion.