The Effect of Povidone-Iodine Irrigation on the Efficacy of Antibiotic Cement In Vitro

Povidone-iodine is a common antiseptic demonstrating success in reducing infection rates in primary arthroplasty; however, recent data suggest that its use in revision arthroplasty may increase infection rates. This study evaluated the effect of povidone-iodine solution on antibiotic cement and investigated the connection between povidone-iodine and increased infection rates in revision arthroplasty. Sixty antibiotic cement samples (ACSs) were formed using gentamicin-impregnated cement. The ACSs were divided into three groups: group A (n=20) was subject to a 3-minute povidone-iodine soak followed by a saline rinse; group B (n=20) underwent a 3-minute saline soak; and group C (n=20) underwent only a saline rinse. The antimicrobial activity of the samples was tested using a Kirby-Bauer-like assay using Staphylococcus epidermidis. The zone of inhibition (ZOI) was measured every 24 hours for 7 days. All groups possessed the greatest antimicrobial activity at 24 hours. Group C displayed a mass-corrected ZOI of 395.2 mm/g, which was statistically greater than the group B ZOI (313.2 mm/g, P<.05) but not the group A ZOI (346.5 mm/g, P>.05). All groups demonstrated a decrease in antimicrobial activity at 48 through 96 hours, with no significant difference at any time point. Prolonged soaking of antibiotic cement in a povidone-iodine or saline solution results in elution of the antibiotic into the irrigation solution, blunting initial antibiotic concentration. When using antibiotic cement, antiseptic soaks or irrigation should be focused prior to cementation. [Orthopedics. 2024;47(1):10-14.].

Advances in Virtual Cutting Guide and Stereotactic Navigation for Complex Tumor Resections of the Sacrum and Pelvis: Case Series with Short-Term Follow-Up

Primary malignancies of the sacrum and pelvis are aggressive in nature, and achieving negative margins is essential for preventing recurrence and improving survival after en bloc resections. However, these are particularly challenging interventions due to the complex anatomy and proximity to vital structures. Using virtual cutting guides to perform navigated osteotomies may be a reliable method for safely obtaining negative margins in complex tumor resections of the sacrum and pelvis. This study details the technique and presents short-term outcomes. Patients who underwent an en bloc tumor resection of the sacrum and/or pelvis using virtual cutting guides with a minimum follow-up of two years were retrospectively analyzed and included in this study. Preoperative computer-assisted design (CAD) was used to design osteotomies in each case. Segmentation, delineating the tumor from normal tissue, was performed by the senior author using preoperative CT scans and MRI. Working with a team of biomedical engineers, virtual surgical planning was performed to create osteotomy lines on the preoperative CT and overlaid onto the intraoperative CT. The pre-planned osteotomy lines were visualized as "virtual cutting guides" providing real-time stereotactic navigation. A precision ultrasound-powered cutting tool was then integrated into the navigation system and used to perform the osteotomies in each case. Six patients (mean age 52.2 ± 17.7 years, 2 males, 4 females) were included in this study. Negative margins were achieved in all patients with no intraoperative complications. Mean follow-up was 38.0 ± 6.5 months (range, 24.8-42.2). Mean operative time was 1229 min (range, 522-2063). Mean length of stay (LOS) was 18.7 ± 14.5 days. There were no cases of 30-day readmissions, 30-day reoperations, or 2-year mortality. One patient was complicated by flap necrosis, which was successfully treated with irrigation and debridement and primary closure. One patient had local tumor recurrence at final follow-up and two patients are currently undergoing treatment for metastatic disease. Using virtual cutting guides to perform navigated osteotomies is a safe technique that can facilitate complex tumor resections of the sacrum and pelvis.

Utility of Repeat MRI in Patients With Degenerative Cervical Disease

Existing guidelines regarding indications for initial cervical spine magnetic resonance imaging (MRI) do not indicate when to perform repeat MRI in patients with previously documented degenerative disease. This study evaluates the efficacy of repeat MRI in patients with previously diagnosed degenerative cervical disease. Between 2013 and 2018, 153 patients (102 women, 51 men; mean age, 55 years; range, 19-81 years) without a history of trauma or surgery underwent cervical spine MRI 2 or more times at our institution indicated for symptoms of neck pain with or without radiculopathy. The MRI reports of repeat studies were reviewed and compared with index studies for notable changes. Notable radiographic changes were defined as any progression of the existing degenerative disease. Fifty-three of 153 (35%) patients demonstrated progression on repeat MRI. Forty-nine of the 53 patients demonstrating progression had new or worsening symptoms prior to their follow-up study (P=.03). Twenty-nine of 35 (83%) patients with new or worsening radiculopathy progressed on MRI (P<.01). Nine of 10 (90%) patients with new upper motor neuron findings demonstrated progression (P=.01). Axial neck pain alone was not statistically linked to MRI progression (P=.1). Twenty-five (16.3%) patients underwent operative management for their disease. Only 12 (48.0%) of the surgical patients presented MRI progression (P=.1). In the absence of new or worsening degenerative cervical symptoms, additional MRI studies are unlikely to reveal any radiographic progression or change clinical management from nonoperative to operative. [Orthopedics. 2023;46(2):98-102.].

Spontaneous Extensor Pollicis Longus Rupture Associated With an Extensor Digitorum Brevis Manus

A 64-year-old left-handed man with no history of rheumatoid arthritis or distal radius fracture presented with spontaneous loss of thumb interphalangeal joint extension. Intraoperatively, the patient was found to have a variant extensor indicis proprius with extensor digitorum brevis manus. Prior extensor digitorum communis ruptures have been reported in the literature secondary to the distal extensor digitorum brevis manus muscle belly, but there are no prior reports of extensor pollicis longus rupture. This case demonstrates a unique etiology of extensor pollicis longus rupture and highlights the alteration in the surgical plan required secondary to the absence of an extensor indicis proprius tendon.

Relationship to drill bit diameter and residual fracture resistance of the distal tibia

BACKGROUND

The etiology of bone refractures after screw removal can be attributed to residual drill hole defects. This biomechanical study compared the torsional strength of bones containing various sized cortical drill defects in a tibia model.

METHODS

Bicortical drill hole defects of 3 mm, 4 mm, and 5 mm diameters were tested in 26 composite tibias versus intact controls without a drill defect. Each tibia was secured in alignment with the rotational axis of a materials testing system and the proximal end rotated internally at a rate of 1 deg./s until mechanical failure.

FINDINGS

All defect test groups were significantly lower (P < 0.01) in torque-to-failure than the intact group (82.80 ± 3.70 Nm). The 4 mm drill hole group was characterized by a significantly lower (P = 0.021) torque-to-failure (51.00 ± 3.27 Nm) when compared to the 3 mm drill hole (59.00 ± 5.48 Nm) group, but not different than the 5 mm hole group (55.71 ± 5.71 Nm). All bones failed through spiral fractures, bones with defects also exhibited posterior butterfly fragments.

INTERPRETATION

All the tested drill hole sizes in this study significantly reduced the torque-to-failure from intact by a range of 28.4% to 38.4%, in agreement with previous similar studies. The 5 mm drill hole represented a 22.7% diameter defect, the 4 mm drill hole a 18.2% diameter defect, and the 3 mm drill hole a 13.6% diameter defect. Clinicians should be cognizant of this diminution of long bone strength after a residual bone defect in their creation and management of patient rehabilitation programs.

Extraction of a Bent Tibial Nail After Refracture: A Case Report

CASE

A 65-year-old man previously treated by intramedullary nailing for a left tibial shaft fracture presented 6 years later with an open refracture of his left tibia after a motorcycle accident. Treatment required extraction of the bent nail before revision nailing.

CONCLUSIONS

Extraction of deformed intramedullary devices is a skill that will continue to be demanded of orthopaedic surgeons. In this case, standard extraction though the entry point proved successful. Standard extraction offers the safest form of removal and should be contemplated before considering more morbid methods of extraction while examining the fracture's morphology and the device's deformity.