Proximal Tibial Bone Defect Treated with Intentional Deformity and Bone Transport

Abstract

Septic nonunion of the tibia presents a challenge for limb reconstruction. Proximal bone defects are uncommon and require distal osteoplasty surgery. This case will present two challenges: the management of a bone and soft tissue defect of the proximal tibia without tissue transfer and the challenges of a distal tibial lengthening. The decision between classic bone transport and shortening-lengthening transport will also be addressed.

Brief Clinical History

This is a 55 year old male whose leg was crushed in an earthquake related building collapse. This occurred in an underdeveloped nation where he was treated with an IM nail and local wound care. He presented one year after the injury with an open wound, purulence, and an infected nonunion of the tibia.

Problem List

1. Septic nonunion of the tibia and fibula
2. Contaminated retained hardware
3. Soft tissue defect
4. Necrotic tibia bone with impending bone defect

Treatment Strategy

Eradication of infection was achieved with wound excision, removal of all poorly vascularized bone, hardware removal, culture specific antibiotics, stability and wound closure. The external fixator was used with pin fixation maintained outside the zone of infection. The rings were manipulated to allow for a tension free wound closure with no regard for the position of the bone ends. A fibular resection was performed to allow for shortening of the defect site independently from the future lengthening site. This also assisted with wound closure.

Basic Principles

Five deep soft tissue cultures were sent for aerobic, anaerobic, fungal, and mycobacterial investigation. Intravenous antibiotics were started empirically and were altered based on sensitivities. The challenged soft tissue was allowed to heal for two weeks before gradually correcting the proximal deformity and shortening the bone defect site. The use of external fixation was critical for its ability to gradually move bone and stretch soft tissues. The lengthening osteotomy was delayed to prevent contamination of the osteotomy site and to minimize stress on the soft tissues. The patient was encouraged to stretch the gastrocnemius and soleus muscles to prevent contracture during distal tibial lengthening. Acute closure of a contaminated wound is possible after a thorough debridement of all tissues.

Technical Pearls

The wires and pins need to be outside the zone of infection and dissection whenever possible to prevent pin infection leading to deep wound infection. Distal tibial lengthenings are less osteogenic than proximal lengthenings and need to proceed at a slower rate. In this case the bone was distracted at 0.5mm/day.

The decision to resect the fibula was made in part to allow for early docking and provide an extended time for healing at the nonunion site. This way the nonunion site would be healed around the same time as the lengthening site minimizing the time in the frame. One needs to estimate the time for healing at the lengthening site and the docking site independently and then use a technique to ensure the fastest healing at both sites. I recommend 50% weight bearing until the bone defect has docked and then advancement to full weight bearing.

Avoiding and Managing Problems

Distal tibial lengthening causes equinus ankle contractures. Calf muscle stretching needs to be performed by patients immediately post op 3-5 times per day. A neutral foot splint is also helpful to keep the ankle in a plantargrade position. A gastro soleus recession may be needed in the future. A foot ring can be used but needs to include ankle distraction to avoid compression of the articular cartilage.

Bone healing may be accelerated by partial weight bearing, Vitamin D and Calcium, a high protein diet, and external bone stimulation. Slow distraction of the osteotomy will make better regenerate bone. Delayed union of the regenerate can be treated with slowing or cessation of the distraction or, if distraction is complete, a percutaneous injection of bone marrow aspirate concentrate.

Cross References

References suggested reading

1. Rozbruch SR, Segal K, Ilizarov S, Fragomen AT, Ilizarov G. Does the Taylor Spatial Frame accurately correct tibial deformities? Clin Orthop Relat Res. 2010 May;468(5):1352-61. Epub 2009 Nov 13.
2. Rozbruch SR, Pugsley J, Fragomen A, Ilizarov S. “Repair of tibial nonunions and bone defects with the Taylor Spatial Frame”. J Orthop Trauma 2008, 22(2):88-95
3. Nho SJ, Helfet DL, Rozbruch SR. Temporary intentional leg shortening and deformation to facilitate wound closure using the Ilizarov/Taylor spatial frame. J Orthop Trauma. 2006 Jul;20(6):419-24
4. Gulsen M, Ozkan C. Angular shortening and delayed gradual distraction for the treatment of asymmetrical bone and soft tissue defects of the tibia: a case series.
5. Beltran MJ, Ochoa LM, Graves RM, Hsu JR. Composite bone and soft tissue loss treated with distraction histiogenesis. J Surg Orthop Adv. 2010 19(1):23-8

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