What should be included in a follow-up CT report for a patient with a Limb Reconstruction System (LRS) in situ after undergoing tibial osteotomy and limb reconstruction/lengthening surgery?

Follow-Up CT Report Components for Tibial Osteotomy with LRS in Situ

A follow-up CT report for a patient with a Limb Reconstruction System (LRS) after tibial osteotomy and limb reconstruction/lengthening should document hardware position, bone regenerate quality at the distraction site, union status at the osteotomy/docking site, alignment measurements, and any complications including infection or hardware failure.

Essential Imaging Protocol

• CT with metal artifact reduction techniques is the preferred modality for detailed assessment of bone and hardware relationships when radiographs are insufficient 1
• CT provides superior visualization of changes in surrounding bone not apparent on plain radiographs and can detect radiographically occult pathology 1, 2
• Standard radiographs may be adequate for routine follow-up but CT is indicated when complications are suspected or for precise anatomical assessment 1

Critical Report Elements

Hardware Assessment

• Document pin/screw position and stability within the bone, noting any loosening, migration, or breakage 1
• Assess for periprosthetic lucency around pins/screws, which may indicate loosening or infection 1
• Evaluate rail rod integrity and clamp positioning 3, 4
• Note any hardware failure or mechanical complications 1

Bone Regenerate Quality (Distraction Site)

• Characterize the regenerate bone formation at the corticotomy/distraction site, describing density, consolidation pattern, and cortical continuity 3, 5, 6
• Document the length of regenerate bone achieved and compare to surgical goals 3, 5
• Assess for premature consolidation or poor regenerate formation that may require adjustment of distraction protocol 3, 7

Union Status (Osteotomy/Docking Site)

• Evaluate bony union at the osteotomy or docking site, noting presence of bridging callus, cortical continuity, and trabecular crossing 3, 5, 6
• Document any persistent gap, nonunion, or delayed union 5, 6
• Assess for signs of infection at the fracture/osteotomy site including bone destruction, periosteal reaction, or sequestrum formation 1

Alignment and Length Measurements

• Measure and report coronal and sagittal plane alignment of the tibia, noting any varus/valgus or anterior/posterior angulation 1
• Document rotational alignment when clinically relevant 1
• Calculate total limb length achieved and compare to contralateral limb or preoperative measurements 3, 5, 7
• Assess mechanical axis alignment when full-length imaging is available 1

Complications Surveillance

• Screen for pin tract infection by evaluating for periosteal reaction, cortical erosion, or soft tissue inflammatory changes around pin sites 3, 5, 4
• Assess for osteomyelitis with findings of bone destruction, sequestrum, involucrum, or sinus tract formation 1
• Evaluate for fracture through pin sites or regenerate bone 2, 3
• Document any joint subluxation or dislocation, particularly at the ankle if fibular osteotomy was performed 7
• Assess for heterotopic ossification or soft tissue calcification 1

Soft Tissue Assessment

• Evaluate soft tissue envelope for fluid collections, abscesses, or hematomas using CT with IV contrast when infection is suspected 1
• Document muscle atrophy or edema patterns 1
• Assess for nerve or vascular impingement by hardware 1

Common Pitfalls to Avoid

• Do not overlook subtle periprosthetic lucency around pins, as this may be the earliest sign of loosening or infection before clinical symptoms develop 1
• Avoid reporting only on hardware position without assessing bone quality, as regenerate consolidation and union status are the primary determinants of treatment success 3, 5, 6
• Do not fail to compare with prior imaging to detect interval changes in alignment, regenerate maturation, or development of complications 1
• Avoid inadequate assessment of the tibiofibular syndesmosis if fibular procedures were performed, as instability can lead to ankle malalignment 7

Timing Considerations

• Serial imaging is essential to monitor for fragment migration, development of complications, or changes in surrounding bone 2
• The average treatment duration with LRS is 8-10 months, with union typically occurring at 8-12 months depending on the amount of lengthening 3, 5, 6, 4
• More frequent imaging may be warranted if complications develop or if the distraction protocol requires adjustment 3, 7