Distal Tibial Bone Defect Treated with Bone Transport Using Two Proximal Osteotomy Sites

Abstract

Large bone and soft tissue defects present a challenging problem for limb salvage surgeons. Bone transport is a powerful technique that restores normal autologous bone to the defect site but can be a long process. Using two osteotomy sites allows for more rapid recovery of length and is well tolerated. Bone transport can often be used to close soft tissue defects reducing the need for free tissue transfer.

Brief Clinical History:

This is a 41 year old, healthy male who suffered a severe tibial injury at sea. He presented two weeks after the injury. He had already been treated with wound debridement, an antibiotic spacer, and external fixation. Wound closure had not been possible.

Preoperative Problem List

1. Distal tibial bone defect
2. Distal medial leg soft tissue defect
3. Coronal intraarticular fracture

Treatment Strategy

The plastic surgery team was consulted, and a discussion of all options ensued. Options included bone transport and local grafting, free tissue and free fibula transport, and below knee amputation. The patient was included in the decision and bone transport was elected.

Basic Principles

The wound was debrided, spacer removed, articular surfaced fixed, external fixator applied, and a local soleus flap was mobilized and was covered was a split thickness skin graft. The grafts were allowed four weeks to heal, and then a two level tibial osteotomy was performed. The bone transport was started with the proximal site distracted at 0.75mm per day, the mid tibial osteotomy site distracted 0.5mm per day, and the defect site shortened at 1.25mm per day. 

Technical Pearls:

For two level osteotomies the rate of distraction cannot be 1mm per day at each site. This is too fast for the tissues to accommodate to the tension.  The rate at the middle site is typically 0.5mm/day and the proximal site can be 0.5-0.75mm/day. The compression at the defect site needs to proceed at the same rate as the total distraction. This is a true bone transport. For a shortening-lengthening type “transport” with a fibular defect, the defect can be compressed 2-3mm/day while the lengthening rate remains unaltered. At the end of transport and docking a long 51” radiograph needs to be taken to ensure equal leg lengths and a level pelvis. Persistent discrepancy can be treated with fibular osteotomy and continued distraction until equalization.

Avoiding and Managing Problems

Pin loosening is an infrequent problem with metaphyseal pins that have been in place for over 6 months. Serial radiographs are taken to observe bone healing but attention should also be given to pin fixation when analyzing those films. Loose pins should be removed in the office and replaced in the operating room.

Entrapment of overlying soft tissue at the docking site is common with long bone transports. This is managed with temporary cessation of the transport, skin elevation or transverse excision, acute docking that may require a fibular osteotomy, and/or bone grafting at the docking site.

Alignment of the lengthening and docking sites can be optimized with use of a six axis hexapod ringed external fixator. One must remember, however, that correction at one level of a stacked frame will introduce new deformity at the adjacent level. The new deformity of often not recognized.

Bone transport is a lengthy process, and patient expectations can be tricky to manage. The best policy is to explain to patients that bone transport is a limb salvage endeavor, multiple surgeries will be needed, obstacles will be encountered along the way, and pain medication will be needed for prolonged periods. As the surgeon it is important to remain positive and confident and to re-vitalize the patient during each office visit.

References

1. 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
2. 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.
3. Rozbruch SR, Weitzman AM, Watson T, Freudigman P, Katz HV, Ilizarov S.  Simultaneous treatment of tibial bone and soft tissue defects with the Ilizarov method. J Orthop Trauma. 2006 Mar;20(3):197-205
4. Sen C, Kocaoglu M, Eralp L, Gulsen M, Cinar M. Bifocal compression-distraction in the acute treatment of grade III open tibia fractures with bone and soft-tissue loss: a report of 24 cases. J Orthop Trauma. 2004 Mar;18(3):150-7

 

Authors