Periarticular Distal Tibial Infected Nonunion, Ankle Salvage With Bone Transport

Abstract

This case outlines a staged approach to a patient status post open reduction, internal fixation (ORIF) of a tibial Pilon fracture with infection, bone loss and soft tissue compromise. The soft tissue management in this case dictates the approach and extent for reconstruction. Our plan involved careful exposure through compromised soft-tissue, removal of all nonviable tissue (bone and hardware) and stability (circular ring external fixation). The decision for ankle salvage versus arthrodesis is made based on the viability of the small tibial plafond segment and the condition of the tibio-talar joint. Residual limb length discrepancy was corrected through an integrated fixation method, lengthening with a Taylor-Spatial Frame (TSF) and then insertion of an intramedullary nail, as part of the second stage reconstruction.

1.Brief Clinical History:

This is a 42-year-old male who fell from a construction scaffold eight months prior to presentation in our clinic. The patient suffered a type IIIb Pilon fracture that was treated with external-fixation and a limited ORIF. Postoperatively, at the outside institution, the patient developed a wound infection with dehiscence that required repeat debridements. One-month post injury, the patient required an abdominal free-flap and hardware revision to provide adequate soft tissue coverage. A repeat ORIF was attempted at the time. This resulted in repeat wound infection and wound dehiscence. The patient presented to our clinic with active infection, wound breakdown and a vacuum-assisted closure (VAC) device on his leg.

2. Preoperative Clinical Photos and Radiographs:

• Figure 1: Clinical photo from the lateral side of the leg demonstrating poor soft tissue envelope and anteromedial free flap. Note equines position of the foot.
• Figure 2: Clinical photo from the medial side of the leg with evidence of cellulitis, and a dressing from the VAC assisting in wound closure.
• Figure 3: AP radiograph demonstrating LDTA of 79° (86-92) representing valgus deformity and metaphyseal nonunion with intact hardware on the tibia and fibula.
• Figure 4: Lateral radiograph demonstrating ADTA 85° (78-82) and a congruent articular reduction of the ankle joint. There is a very small segment of distal tibia.
• Figure 5: 51 inch standing erect leg radiograph demonstrating 23 mm limb length discrepancy, right short and a mechanical axis deviation of 7 mm lateral.

3. Preoperative Problem List:

1. Nonunion of a right type IIIb Pilon fracture
2. Post-traumatic bone loss right ankle
3. Rule out active infection
4. Limb length discrepancy, right short, 2.3 cm
5. 15 degree right external rotation deformity
6. 15 degree right ankle equines contracture
7. Retained hardware right ankle
8. Poor soft tissue envelope, wound dehiscence with VAC
9. Small periarticular fragment and valgus deformity of ankle

4. Treatment Strategy:

This complex reconstruction was divided into two stages. We also discussed with the patient a salvage option, which would have been ankle arthrodesis. Stage one’s goals were to perform a meticulous ankle debridement and obtain reliable deep tissue cultures and pathologic specimens. A TSF would provide the stability. Dead space management after debridement would be managed with rapid (2 mm per day) shortening of the articular block to the distal metaphysis. The TSF would also correct the rotational and equines deformity. Finally, residual limb length would be corrected with a proximal tibial and fibula osteotomy and application of TSF.  Lengthening would be performed using the Lengthening and then Nailing (LATN) technique.

5. Basic Principles:

Nonviable bone must be excised, potentially leaving a relatively small articular segment. If the tibial plafond is viable and good joint congruity exists, the ankle joint can be salvaged. 1.8 mm Olive wires are used to secure the segment and mechanical stability is augmented using a foot ring. The geometry of the bone resection is important. Flat cuts are mandatory. Soft tissue handling must be gentle and a plastic surgery colleague is invaluable in choosing skin incisions as well as re-elevating soft tissue flaps. Spanning the ankle provides improved stability to the distal segment and can be used to correct ankle contracture or manage drop-foot.

6. Images During Treatment:

• Figure 6: After an initial debridement and assessment of the level of bone resection is made, 1.8 mm smooth K-wires are used (black lines) as sagittal and coronal flat-cut guides.
• Figure 7: AP intraoperative X-ray confirming perpendicular flat cuts on proximal and distal tibial segments.
• Figure 8: Lateral intraoperative X-ray confirming perpendicular flat cuts on distal articular segment.
• Figure 9: AP post debridement bone cuts. Note the perpendicular flat cuts, which is requisite for stable docking of the distal tibial into the articular segment.
• Figure 10: Clinical photograph from the lateral side demonstrating the remaining bone defect .
• Figure 11: Intraoperative X-ray demonstrating TSF application across bone defect. Red arrows indicating 2 mm per day of defect closure. The ability to reduce the bone gap acutely is limited by wound closure and neurovascular structure kinking.
• Figure 12, 13: AP and lateral X-rays after application of TSF with two-level correction. This construct allowed for 5.5 cm lengthening at proximal tibia.
• Figure 14: Clinical photograph of patient wearing two-level TSF. Note the foot ring, which was added to increase the stability of the distal articular segment.

7. Technical Pearls:

1. Nonviable bone must be excised to ensure eradication of infection and allow for reliable bony union at docking site.
2. Obtaining five deep tissue cultures and one pathology sample allows for targeted antibiotic therapy.
3. Using K-wires ensures sound geometrical excision of bone and stable bone docking.
4. LATN allows for earlier removal of TSF.

8. Outcome clinical photos and radiographs:

• Figure 15: Final AP radiograph with healed lengthening at proximal tibia after LATN procedure.
• Figure 16: Final lateral radiograph, healed regenerate and docking site.
• Figure 17: Final postoperative standing 51-inch erect leg radiograph. Red lines illustrate the hip to ankle line and maintenance of the mechanical axis.
• Figure 18: Final standing clinical photograph.
• Figure 19: Final hind-foot clinical alignment illustrating a plantigrade foot with no residual limb length discrepancy.

9. Avoiding and Managing Problems:

1. Aggressive soft tissue coverage and eradication of infection through excision of all nonviable tissues should be the primary goal. Reconstruction with acute plus gradual shortening and a staged lengthening can concurrently manage the dead space and start the process of bony docking at the nonunion site.
2. A staged-approach is best. Repeating a new 51-inch hip to ankle x-ray after stage- one allows for modification, if necessary, of original planned lengthening. Correlate the clinical exam with blocks to equalize the limb lengths and the indirect limb measurement on radiographs.
3. Involve infectious diseases and plastic surgery early to ensure a focused treatment protocol.

10. References and Suggested Reading

1. Gardner MJ, Mehta S, Barei DP, Nork SE. Treatment protocol for open AO/OTA type C3 pilon fractures with segmental bone loss. J Orthop Trauma. 2008;22:451-457.
2. Kabata T, Tsuchiya H, Sakurakichi K, Yamashiro T, Watanabe K, Tomita K. Reconstruction with distraction osteogenesis for juxta-articular nonunions with bone loss. J Trauma. 2005;58:1213-1222.
3. Schottel PC, Muthusamy S, Rozbruch SR. Distal Tibial Periarticular Nonunions: Ankle Salvage with Bone Transport. J Orthop Trauma. 2013.
4. Rozbruch SR, Kleinman D, Fragomen AT, Ilizarov S. Limb lengthening and then insertion of an intramedullary nail: a case-matched comparison. Clin Orthop Relat Res. 2008;466:2923-2932.
5. Tellisi N, Fragomen AT, Ilizarov S, Rozbruch SR. Limb salvage reconstruction of the ankle with fusion and simultaneous tibial lengthening using the Ilizarov/Taylor spatial frame. HSS J. 2008;4:32-42.

Posted: 4/10/2014

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