How Does Resorption Differ Among Single-Level and Multilevel Lumbar Disc Herniations? A Prospective Multi-Imaging and Clinical Phenotype Study.

STUDY DESIGN: Prospective, case series. OBJECTIVE: To identify and characterize any differences in specific patient factors, MRI findings, features of spontaneous disc resorption, and outcomes between patients with single-level and multilevel LDH. BACKGROUND: Lumbar disc herniation (LDH) is one of the most common spinal pathologies worldwide. Though many cases of LDH resolve by spontaneous resorption, the mechanism underlying this "self-healing" phenomenon remains poorly understood, particularly in the context of multilevel herniations. METHODS: A one-year prospective study was conducted of patients presenting with acute symptomatic LDH between 2017 and 2019. Baseline demographics, herniation characteristics, and MRI phenotypes were recorded before treatment, which consisted of gabapentin, acupuncture, and the avoidance of inflammatory-modulating medications. MRIs were performed approximately every three months after the initial evaluation to determine any differences between patients with single-level and multilevel LDH. RESULTS: Ninety patients were included, 17 demonstrated multilevel LDH. Body mass index was higher among patients with multilevel LDH ( P <0.001). Patients with multilevel LDH were more likely to exhibit L3/L4 inferior endplate defects ( P =0.001), L4/L5 superior endplate defects ( P =0.012), and L4/L5 inferior endplate defects ( P =0.020) on MRI. No other differences in MRI phenotypes ( e.g. Modic changes, osteophytes, etc .) existed between groups. Resorption rate and time to resolution did not differ between those with single-level and multilevel LDH. CONCLUSIONS: Resorption rates were similar between single-level and multilevel LDH at various time points throughout one prospective assessment, providing insights that disc healing may have unique programmed signatures. Compared with those with single-level LDH, patients with multilevel herniations were more likely to have a higher BMI, lesser initial axial and sagittal disc measurements, and endplate defects at specific lumbar levels. In addition, our findings support the use of conservative management in patients with LDH, regardless of the number of levels affected. LEVEL OF EVIDENCE: Level 3.

CT Osteoabsorptiometry Assessment of Subchondral Bone Density Predicts Intervertebral Implant Subsidence in a Human ACDF Cadaver Model.

STUDY DESIGN: Cadaveric biomechanics study. OBJECTIVE: Subchondral bone mineral density (sBMD) reflects the long-term mineralization and distribution of stress on joints. The use of 3-dimensional (3-D) methods to evaluate sBMD, including computed tomography osteoabsorptiometry (CT-OAM), enables the assessment of density distribution with emphasis on subchondral bone. This study sought to measure the sBMD of cervical endplates using CT-OAM and correlate it to mechanical implant subsidence in a cadaveric model. METHODS: Fourteen fresh human cadaveric cervical spines were subjected to dynamic testing after single level discectomy and instrumentation using a PEEK interbody spacer. Specimens were imaged with CT 3 times: 1st) whole intact cervical spine, 2nd) after implantation, and 3 rd) after testing. These images were used to assess sBMD distributions using CT-OAM directly underneath the spacer. Subsidence was defined as the displacement of the device into the endplates. RESULTS: The observed "failure mode" was consistently recorded as subsidence, with a mean of 0.45 ± 0.36 mm and 0.40 ± 0.18 mm for the C4-5 and C6-7 levels, respectively. There were no differences by level. The experimental cyclic test showed that denser endplates experienced less deformation under the same load. CONCLUSIONS: This study achieved its stated aim of validating the use of CT-OAM as a method to analyze the sBMD of the cervical endplates. Studies such as this are providing new information on available technology such as CT-OAM, providing new tools for clinicians treating spinal conditions in need of augmentation and stabilization via interbody devices.

Initial Impact of the COVID-19 Pandemic on a US Orthopaedic Foot and Ankle Clinic.

Background: In the United States, the COVID-19 pandemic led to a nationwide quarantine that forced individuals to adjust their daily activities, potentially impacting the burden of foot and ankle disease. The purpose of this study was to compare diagnoses made in an orthopaedic foot and ankle clinic during the shelter-in-place period of the COVID-19 pandemic to diagnoses made during the same months of the previous year. Methods: A retrospective review of new patients presenting to the clinics of 4 fellowship-trained orthopaedic foot and ankle surgeons in a major United States city was performed. Patients in the COVID-19 group presented between March 22 and July 1, 2020, during the peak of the quarantine for this city. Patients in the control group presented during the same period of 2019. Final diagnosis, chronicity of symptoms (acute: ≤1 month), and mechanism of disease were compared between groups. Results: A total of 1409 new patient visits were reviewed with 449 visits in the COVID-19 group and 960 visits in the control group. The COVID-19 group had a significantly higher proportion of ankle fractures (8.7% vs 5.4%, P = .020) and stress fractures (4.2% vs 2.2%, P = .031), but a smaller proportion of Achilles tendon ruptures (0.7% vs 2.5%, P = .019). The COVID-19 group had a higher proportion of acute injuries (35.4% vs 23.5%, P < .001). Conclusion: There was a shift in prevalence of pathology seen in the foot and ankle clinic during the COVID-19 pandemic, which may reflect the adoption of different activities during the quarantine period and reluctance to present for evaluation of non-urgent injuries. Level of Evidence: Level III, retrospective cohort study.

Periprosthetic Tibial Plateau Fractures After Unicompartmental Knee Arthroplasty Are Successfully Treated With Open Reduction and Internal Fixation.

Periprosthetic tibial fractures after unicompartmental knee arthroplasty (UKA) are rare but devastating events. Given the relative infrequency of these injuries, treatment strategies are not well defined. The goal of this retrospective case series is to report the findings for a series of patients who underwent open reduction and internal fixation (ORIF) of periprosthetic fracture after UKA, including radiographic alignment, Knee Society Score (KSS), and failure rate. Patients were identified by the International Classification of Diseases code for periprosthetic tibial plateau fractures. Electronic medical records and radiographs were retrospectively reviewed. Fracture patterns and coronal and sagittal alignment of UKA components were measured on radiographs. Clinical outcomes, including range of motion assessment, visual analog scale pain score, and KSS, were collected at final follow-up. Eight patients satisfied the inclusion criteria for this study. Fractures occurred at a median of 14 days (range, 5-52 days) after UKA, and all showed a vertical shear pattern that exited at the meta-diaphyseal junction. Of the 8 fractures, 7 (87.5%) healed to radiographic and clinical union after the initial ORIF. One patient required reoperation for hardware failure. Mean visual analog scale pain score and KSS at final follow-up were 3 and 85±14, respectively. Periprosthetic tibial plateau fractures after UKA commonly occur as a vertical shear fracture exiting at the metadiaphyseal junction. The use of ORIF with a 3.5-mm plate in buttress mode is a reliable method for treatment of these fractures. Restoration of alignment and motion is achievable, but residual pain may affect patient-reported outcome scores. [Orthopedics. 2022;45(5):287-292.].