Spine Fixation Hardware: An Update

Development and validation of deep learning models for identifying the brand of pedicle screws on plain spine radiographs

Background

In spinal revision surgery, previous pedicle screws (PS) may need to be replaced with new implants. Failure to accurately identify the brand of PS-based instrumentation preoperatively may increase the risk of perioperative complications. This study aimed to develop and validate an optimal deep learning (DL) model to identify the brand of PS-based instrumentation on plain radiographs of spine (PRS) using anteroposterior (AP) and lateral images.

Methods

A total of 529 patients who received PS-based instrumentation from seven manufacturers were enrolled in this retrospective study. The postoperative PRS were gathered as ground truths. The training, validation, and testing datasets contained 338, 85, and 106 patients, respectively. YOLOv5 was used to crop out the screws' trajectory, and the EfficientNet-b0 model was used to develop single models (AP, Lateral, Merge, and Concatenated) based on the different PRS images. The ensemble models were different combinations of the single models. Primary outcomes were the models' performance in accuracy, sensitivity, precision, F1-score, kappa value, and area under the curve (AUC). Secondary outcomes were the relative performance of models versus human readers and external validation of the DL models.

Results

The Lateral model had the most stable performance among single models. The discriminative performance was improved by the ensemble method. The AP + Lateral ensemble model had the most stable performance, with an accuracy of 0.9434, F1 score of 0.9388, and AUC of 0.9834. The performance of the ensemble models was comparable to that of experienced orthopedic surgeons and superior to that of inexperienced orthopedic surgeons. External validation revealed that the Lat + Concat ensemble model had the best accuracy (0.9412).

Conclusion

The DL models demonstrated stable performance in identifying the brand of PS-based instrumentation based on AP and/or lateral images of PRS, which may assist orthopedic spine surgeons in preoperative revision planning in clinical practice.

Targeted Delivery of Abaloparatide to Spinal Fusion Site Accelerates Fusion Process in Rats

Spinal fusions are performed to treat congenital skeletal malformations, spondylosis, degenerative disk diseases, and other pathologies of the vertebrae that can be resolved by reducing motion between neighboring vertebrae. Unfortunately, up to 100,000 fusion procedures fail per year in the United States, suggesting that efforts to develop new approaches to improve spinal fusions are justified. We have explored whether the use of an osteotropic oligopeptide to target an attached bone anabolic agent to the fusion site might be exploited to both accelerate the mineralization process and improve the overall success rate of spinal fusions. The data presented below demonstrate that subcutaneous administration of a modified abaloparatide conjugated to 20 mer of D-glutamic acid not only localizes at the spinal fusion site but also outperforms the standard of care (topically applied BMP2) in both speed of mineralization (p < 0.05) and overall fusion success rate (p < 0.05) in a posterior lateral spinal fusion model in male and female rats, with no accompanying ectopic mineralization. Because the bone-localizing conjugate can be administered ad libitum post-surgery, and since the procedure appears to improve on standard of care, we conclude that administration of a bone-homing anabolic agent for improvement of spinal fusion surgeries warrants further exploration.

Therapeutics for enhancement of spinal fusion: A mini review

Objective

With the advances in biological technologies over the past 20 years, a number of new therapies to promote bone healing have been introduced. Particularly in the spinal surgery field, more unprecedented biological therapeutics become available to enhance spinal fusion success rate along with advanced instrumentation approaches. Yet surgeons may not have been well informed about their safety and efficacy profiles in order to improve clinical practices. Therefore there is a need to summarize the evidence and bring the latest progress to surgeons for better clinical services for patients.

Methods

We comprehensively reviewed the literatures in regard to the biological therapeutics for enhancement of spinal fusion published in the last two decades.

Results

Autograft bone is still the gold standard for bone grafting in spinal fusion surgery due to its good osteoconductive, osteoinductive, and osteogenic abilities. Accumulating evidence suggests that adding rhBMPs in combination with autograft effectively promotes the fusion rate and improves surgical outcomes. However, the stimulating effect on spinal fusion of other growth factors, including PDGF, VEGF, TGF-beta, and FGF, is not convincing, while Nell-1 and activin A exhibited preliminary efficacy. In terms of systemic therapeutic approaches, the osteoporosis drug Teriparatide has played a positive role in promoting bone healing after spinal surgery, while new medications such as denosumab and sclerostin antibodies still need further validation. Currently, other treatment, such as controlled-release formulations and carriers, are being studied for better releasing profile and the administration convenience of the active ingredients.

Conclusion

As the world's population continues to grow older, the number of spinal fusion cases grows substantially due to increased surgical needs for spinal degenerative disease (SDD). Critical advancements in biological therapeutics that promote spinal fusion have brought better clinical outcomes to patients lately. With the accumulation of higher-level evidence, the safety and efficacy of present and emerging products are becoming more evident. These emerging therapeutics will shift the landscape of perioperative therapy for the enhancement of spinal fusion.