Faculty Bibliography

STUDY DESIGN/METHODS:Retrospective cohort study. OBJECTIVE:The purpose of this study is to determine the utility of advanced imaging to confirm the placement of robotic pedicle screws. SUMMARY OF BACKGROUND DATA/BACKGROUND:With increasing robotic adoption, certain institutions and surgeons have developed protocols for obtaining 3D intraoperative imaging after robotic pedicle screw placement to ensure proper hardware placement. No studies have assessed the utility of these protocols relative to the potential risks of increased radiation exposure and operative time. The purpose of this study is to determine if we should be obtaining advanced imaging to confirm the placement of robotic pedicle screws. METHODS:This is a single institution retrospective cohort study of patients from May 2022 to July 2023 who underwent lumbar spinal fusion by a high-volume orthopedic spine surgeon at a level 1 metropolitan hospital. All cases used combined robotics and navigation systems for pedicle screw placement and intraoperative 3D imaging for evaluation of screw position. Pedicle screw accuracy was assessed using the Gertzbein and Robbins system (GRS). Acceptable pedicle screw position was defined as GRS A or B. RESULTS:Seventy patients with 354 robotically placed pedicle screws were assessed with intraoperative 3D fluoroscopy. All pedicle screws were placed in either a GRS type A or type B position. Three hundred forty-seven were placed in a GRS A classification (99.2%, 351/354), and 3 were placed in a GRS B classification (0.08% 3/354). No patients had screw-related complications. The average radiation dosage of 3D imaging was 289.7±164.6 mGy. CONCLUSION/CONCLUSIONS:The robotic system places pedicle screws accurately without 3D intraoperative imaging. Given the increased radiation and operative time associated with 3D imaging protocols 3D imaging scans should only be obtained in cases with heightened clinical concern. LEVEL OF EVIDENCE/METHODS:Level IV.

Pars injuries are common causes of low back pain in adolescent athletes. Workup traditionally has included lumbar radiographs with oblique views and single-photon emission computed tomography (SPECT). However, recent literature has demonstrated the accuracy of MRI as a diagnostic modality. Acute injuries may be amenable to bracing with the goal of a healed lesion. Most cases of spondylolysis will result in asymptomatic non-union, though pars repair is an option for symptomatic pars defects without spondylolisthesis.

The anterior cruciate ligament (ACL) functions as a mechanical stabilizer in the tibiofemoral joint, and is the most commonly injured knee ligament. To improve the clinical outcome of tendon grafts used for ACL reconstructions, our long-term goal is to promote graft-bone integration via the regeneration of the native ligament-bone interface. An understanding of strain distribution at this interface is crucial for functional scaffold design and clinical evaluation. Experimental determination, however, has been difficult due to the small length scale of the insertion sites. This study utilizes ultrasound elastography to characterize the response of the ACL and ACL-bone interface under tension. Specifically, bovine tibiofemoral joints were mounted on a material testing system and loaded in tension while radiofrequency (RF) data were acquired at 5 MHz. Axial strain elastograms between RF frames and a reference frame were generated using crosscorrelation and recorrelation techniques. Elastographic analyses revealed that when the joint was loaded in tension, complex strains with both compressive and tensile components occurred at the tibial insertion, with higher strains found at the insertion sites. In addition, the displacement was greatest at the ACL proper and decreased in value gradually from ligament to bone, likely a reflection of the matrix organization at the ligament-bone interface. Our results indicate that elastography is a novel method that can be readily used to characterize the mechanical properties of the ACL and its insertions into bone

Severe arthrosis and deformity of the ankle and subtalar joints are debilitating problems that can be difficult to treat. We retrospectively reviewed and functionally assessed 15 patients who had undergone tibiotalocalcaneal fusion with a retrograde intramedullary nail. The procedure had been a salvage procedure for severe arthrosis and deformity of the ankle and subtalar joints. Minimum follow-up was 2 years. Solid fusion was achieved in 14 of 15 patients. Mean time to union was 16.5 weeks. Ankle-Hindfoot Scale scores showed excellent pain relief at union. Subjective gait disturbances were common postoperatively, though patient satisfaction and the return-to-work rate were high (93% and 80%, respectively). The 12 complications included nonunion, malunion, skin problems, plantar pain, infection, and painful hardware. We advocate using a retrograde nail as a salvage technique in complex posttraumatic or postsurgical settings