Surgical Strategy to Decrease the Revision Rate of Fassier-Duval Nailing in the Lower Limbs of Osteogenesis Imperfecta

Corrosion of a Fassier-Duval Telescopic Nail Causing Pain and Osteolysis: A Case Report

CASE

A 15-year-old girl known with osteogenesis imperfecta presented with left femoral pain. She had been treated with multiple Fassier-Duval intramedullary nails, which were still in situ. Radiographic imaging demonstrated focal osteolysis and periosteal reaction at the telescopic junction of the rod in the distal femur. She underwent implant removal. Intraoperative sampling demonstrating acute sterile inflammation and presence of brownish colored particles consistent with metal debris and osteolysis. Explant analysis confirmed corrosion of the stainless-steel telescopic nail as the underlying cause.

CONCLUSION

Osteolysis and periosteal reaction because of corrosion should be considered in conjunction with other more common causes of pain, such as fracture or infection, in patients treated with telescopic intramedullary nails.

Development and validation of a specialized system for self-tapping medical bone screw testing

A specialized system for accurate self-tapping medical bone screw testing is developed, fully meeting the requirements of ASTM F543-A4 (YY/T 1505-2016). The onset of self-tap is identified automatically according to a change in the slope of the torque curve. Precise load control is applied to determine the self-tapping force accurately. A simple mechanical platform is embedded to ensure the automatic axial alignment of a tested screw with the pilot hole in a test block. In addition, comparative experiments are conducted on different self-tapping screws to verify the system's effectiveness. By the automatic identification and alignment method, both torque curves and axial force curves for each screw exhibit significant consistency. The self-tapping time point derived from the torque curve agrees well with the turning point of the axial displacement curve. The determined self-tapping forces' mean values and standard deviations are both small, which are proved to be effective and accurate in the insertion tests. This work contributes to improving the standard test method for accurate determination of the self-tapping performance of medical bone screws.

The Fate of the Bent Rod in Children With Osteogenesis Imperfecta

BACKGROUND

Osteogenesis imperfecta (OI) is a genetic disorder characterized by brittle bones and long bone deformity. Realignment and intramedullary rodding with telescopic rods are indicated for progressive deformity and can help prevent fractures. Rod bending is a reported complication of telescopic rods and a common indication for revision; however, the fate of bent lower extremity telescopic rods in the setting of OI has not been reported.

METHODS

Patients with OI at a single institution who underwent lower extremity telescopic rod placement with at least 1-year follow-up were identified. Bent rods were identified, and for these bone segments, we collected the location and angle of bend, subsequent telescoping, refracture, increasing angulation of bend, and date of revision.

RESULTS

One hundred sixty-eight telescopic rods in 43 patients were identified. Forty-six rods (27.4%) bent during follow-up, with an average angulation of 7.3 (range: 1 to 24) degrees. In patients with severe OI, 15.7% of rods bent compared with 35.7% in nonsevere OI ( P =0.003). The proportion of bent rods was different between independent and nonindependent ambulators (34.1% and 20.5%; P =0.035). Twenty-seven bent rods (58.7%) were revised, with 12 rods (26.0%) revised early (within 90 d). The angulation of rods that were revised early was significantly higher than rods not (14.6 and 4.3 degrees, P <0.001). Of the 34 bent rods not revised early, the average time to revision or final follow-up was 29.1 months. Twenty-five rods (73.5%) continued to telescope, 14 (41.2%) increased in angulation (average 3.2 degrees), and 10 bones (29.4%) refractured. None of the refractures required immediate rod revision. Two bones had multiple refractures.

CONCLUSIONS

Bending is a common complication of telescopic rods in the lower extremities of patients with OI. It is more common in independent ambulators and patients with nonsevere OI, possibly because of the increased demand placed on the rods. Rods with a small bend and maintained fixation can telescope and need not be an indication for immediate revision.

LEVEL OF EVIDENCE

Level III-Retrospective review.

A Fracture From a Physical Exam: A Case Report of Osteogenesis Imperfecta and the Use of Fassier-Duval Rods

Osteogenesis Imperfecta (OI) is a rare hereditary disorder that leads to fragile bone mineralization and is most often due to a genetic defect in type I collagen, the primary collagen subtype that comprises bone. Patients with OI suffer from a significant burden of fractures and bony deformities. It has been recognized in countries throughout the world and has a variable age and severity of presentation depending on the subtype of OI. Recognition of this disorder requires a high index of suspicion on the part of the clinician, as it can easily be mistaken for non-accidental trauma in children. The current approach to care for patients with this disorder comprises surgical care with intramedullary rod fixation, cyclic bisphosphonate therapy, and rehabilitation to maximize the patient's quality of life and function. This case report demonstrates the importance of considering OI in the differential diagnosis of a child presenting with recurrent fractures so that appropriate testing and treatment interventions can be implemented. The case presented here is that of a male patient with osteogenesis imperfecta who suffered from recurrent long bone fractures, including his femurs bilaterally. His index fracture occurred after a visit to the pediatric ER for an unrelated issue, where his mother claimed that the boy demonstrated pain in his affected leg shortly after the visit. There was a delay in his diagnosis, and the patient suffered multiple fractures before undergoing the insertion of Fassier-Duval rods bilaterally into his femurs to prevent further injury.