Bone transport in acute trauma

Mini-symposium : bone defects

(ii) Bone Transport in Acute Trauma

L. J. Prokuski,

J. L. Marsh

Introduction The management of segmental deficiency of bone in the acutely traumatized patient requires careful consideration of all treatment alternatives. Traditional options include amputation and prosthetic reconstruction. as well as skeletal stabilization and flap coverage of soft tissue defects, followed by vascularized or non-vascularized bone grafting. An exciting new technique for reconstruction of acute skeletal defects is bone transport. Although bone transport offers reconstructive options not previously possible, the procedure is complex and time consuming, and patient selection is important. Indications for Limb Salvage When an acute extremity injury is severe enough to be associated with segmental deficiency of bone, amputation is always a treatment alternative. The decision between limb salvage or amputation must be made after careful consideration of the characteristics of both the injury and the patient. A failed limb salvage, or a salvaged useless limb, can be devastating to the patient functionally, psychologically. and economically.‘.‘~” Injury characteristics that favor amputation over limb reconstruction include : pasterior tibia1 nerve injury in an adult, ipsilateral foot trauma, crush injury, vascular disruption with prolonged ischemia, severe contamination. and multisystem trauma.’ Patient characteristics that favor amputation are: advanced age, medical problems such as diabetes mellitus or peripheral vascular disease, cigarette smoking. and patients unwilling or L. J. Prokuski MD, J. L. Marsh MD, Department of Orthopacdx Surgery. University of Iowa Hospitals and Clinics. 200 Hawkins Drive. Iowa City, IA 52141. USA. Correspondence to JLM.

unable to assist in the reconstructive process (i.e. pin care or compliance with a distraction schedule). These factors are guidelines, and the presence of an individual characteristic that favors amputation should not be considered a contraindication to limb salvage if the patient and the medical team feel salvage is a reasonable option. Several scoring systems have been devised to assist in predicting successful limb salvage and to prevent prolonged attempts with unfavorable outcomes in patients with a high likelihood of failure. While a numerical score predicting successful iimb salvage to assist the physician with this decision making would be welcome, these scores often do not function well in clinical practice. Recent criticism of these scores cite the following problems: lack of applicability in a prospective manner; most are based on small patient groups. and there is validation of the scores in the same sample from which it was developed, yielding inflated estimates of accuracy; there is also the absence of long-term functional outcome data to validate the scoring criteria. Bonanni retrospectively scored 58 lower limb salvage attempts using the Mangled Extremity Syndrome Index, the Mangled Extremity Severity Score, the Predictive Salvage Index and the Limb Salvage Index, and he found no predictive utility in any of the four indices.’ Treatment Alternatives All treatment methods for traumatic loss of bone or bone loss resulting from debridement of a contaminated fracture require skeletal stabilization. Recently, both reamed” and unreamed” nails have been recommended for even severe open fractures; however, when open wounds are associated with contamination and bone loss, external fixation is most commonly indicated. Ring or monolateral fixators

.___ may be utilized. Monolateral fixators have the advantage of relative simplicity, better soft tissue access and more rapid application, all of which are considerable advantages in the acute trauma setting. Adequate stability must be provided, which requires knowledge of individual frame characteristics. Two additional procedures are required : soft tissue coverage of exposed bone, and either bone grafting or exchange nailing to stimulate healing. Soft tissue coverage requires free tissue transfer in most cases with segmental bone deficiency. The bony defect can be reconstructed by direct cancellous grafting after soft tissue coverage. This programme has been described for a series of 8 patients with bone loss secondary to open tibia1 fractures and included external fixation, with an antibiotic bead spacer in the defect to preserve length, free tissue transfer for soft tissue coverage, and later cancellous bone grafting. Two to four iliac crests were harvested per patient. All patients healed in an average of 9 months.’ Others have successfully treated patients with bone defects averaging 9 cm with staged vascularized muscle lransplantation and bone grafting.” Free vascularized libula transfers can be used to treat segmental defects In the lower extremity due to trauma and in a group <>,f12 patients 70% healed in an average of 6 months, .md an additional 15% healed after a second operation.!’ These techniques have several disadvantages. Long treatment times are standard. Extended periods of immobilization are required to protect the initial repair. and complications such as non-union or stress fracture are not infrequent. Multiple operations are needed on non-injured body parts, such as iliac crests or muscle donor sites. Microvascular techniques are necessary to perform free soft tissue or osseous transfers. Bone transport is an alternative technique used to treat segmental deficiencies of bone in acute trauma. The use of the Ilizarov technique has been described to treat 9 patients with an average bone loss of 6.4 cm. Treatment time averaged 7.6 months, and all healed.“’ We have utilized a monolateral limb reconstruction system (Orthofix SLR) to treat segmental deficiency in ‘icute trauma since 1989.” Bone transport for reconstruction of a severely Injured limb with bone and soft tissue loss has several advantages. There is less donor site morbidity. because bone and soft tissue repair is performed largely at the site of injury. This may be important in the multiply Injured patient. Secondly, soft tissue coverage can often be obtained by judicious early shortening of the limb combined with local soft tissue transfers, decreasing the need for free muscle transfers from distant sites. The soft tissue envelope gradually contracts and heals by secondary intention or with split-thickness skin grafts. Bone reconstruction is ‘lccomplished by distraction osteogenesis. which fills the defect and restores length. The regenerated bone IS wide. m’hich reduces the problem of late stress ___

BONE TR.\NSPORT

IN ACUTE

TRAL’M4

__

_.

15.;

Fig. l-The effect of skeletal shortening on soft tissue defects. (A) In an open fracture with exposed bone and a transverse11 orlented soft tissue defect. acute shortening achieves bon! contact and soft tissue coverage. Distraction osteogenesla performed at a distant site restores limb length. (B) Skeletal shortening to achieve contact of a similar skeletal defect with a longitudinally oriented wound results in incomplete wound closure with residual exposed bone. Shortening is less of an aid in the management ol’ the soft tissue injury with this type 01’ wound

154 CURRENT

ORTHOPAEDICS-MINI-SYMPOSIUM:

Fig. t-For

BONE

DEFECTS

legend see facing page.

BONE TRANSPORT

fractures. Finally. evact limb length can be restored if the patient and surgeon feel this is important. Using bone transport for treating acute injuries with bone loss also has disadvantages. Patient compliance is an absolute recluirement for successful treatment. OptimalI!. pre-operative counseling prepares the patient to tolerate. operate, and maintain the apparatus. The acutely traumatized patient does not have the opportunity to participate in preoperative counseling. and this decreases compliance and patient acceptance of the process. Treatment times for reconstruction of acute traumatic injuries by hone transport, as with other treatment methods for skeletal defects. arc long. C’omplications requiring additional operations are frequent. Late angulation through docking site5 and distraction sites are common and require I:ealignment and repeat external fixation or internal fixation. Patients should expect at least one additional surgical procedure after the initial !*ame application. All of these factors must be considered before using

IN .ACI Tf- fKAl

hl.i

155

bone transport to treat an acute traumatic injure associated with severe bone loss. In an :ippropriately selected patient. bone transport offers advantages over conventional techniques and may he the safest \\a\ to restore Iargc sections 01‘ cortical honr

Indications for Bone Transport in Acute Trauma Bone lranspnri shall never be considered t(>r the treatment of 211 aciite closed fracture. even Ii auliminution i\ were. It i\ indicated for segmental loss of hOlltZ Aild ;t\ seaI fractures of the io\j,cr extremity associated \\;ith high-energq open hounds and hone loss. either through the \vound or after debridcment of contaminated devascularized section5 ot‘ bone. 1s the classic indication. Thl\ most common Indicatioli occurs in se\eri’ open tibia1 fracture\. The r,lnge of bone loss required to ccbnsider hone tr;msport 1s generally ?--I 2 cm. Larger del>cts in ;tcute trauma arc not compatible \vith limb ,;il\;ige.

IllB tlbul ftacture utrh a 7 cm bone dcficirnc\i and ‘i 15 . 31 IID ,cI~’i!,\uc included Irrigation and debrldrmrnt and e;trrnal fixation ;I[ an I\LI:\I& institution. Th!s radiograph WB\ taken on admission to our institution 3 da)\ later. (B) .Al‘ter repeated debridemrnt. the v\trrn;ll ~~x;ttot was changed to a monolateral hmb reconstruction sytem allowin@ hone tranrpcjrt. Co\eragr of the bone aa$ performed \\~th Ir~c,~l muscle tranbfers and a split thickness skin graft. The lateral X-ray demonstrater ;Iccurntr :Ilignment and that an outeotomy u .IL performed in the proximal diaphysis. An osteotomy 2 cm more proximal would current11 he preferred. (Cl Bone tranrp. The time spent in csternal iiutli,n I\:,\ 7 monthz. Fig. 2-(AI

I‘hlr J-l-year-old

man suffered

an open grade

defect.The bone was only partlaIty exposed. Initial treatment

1%

CURRENT

ORTHOPAEDICS~MINI-SYMPOSIUM

: BONE DEFECTS

while smaller bone defects heal more quickly with cancellous grafting to the defect. Early aggressive infection may be an indication for bone transport if segmental resection of bone is required. Bone transport or acute shortening followed by distraction at another level aid the management of the soft tissue injury while avoiding free tissue transfer that would otherwise be required. In some cases, acute shortening may close a small bony defect and soft tissue defect simultaneously. In these cases bone transport may be indicated even though the bony defect is smaller than 3 cm. Several words of caution are important prior to widespread adoption of acute shortening to avoid soft tissue coverage. The technique of shortening to obtain soft tissue coverage is most efficacious for transverse wounds. Longitudinal wounds do not close well even with substantial shortening (Fig. 1). In acute trauma the fibula should not be sacrificed to shorten a tibia1 defect because it provides limb stability and decreases the forces on the external fixation frame. The amount of shortening that is well tolerated without distal venous congestion and edema is limited. For this reason free tissue transfers are more appropriate if shortening of greater than 5-7 cm is required to obtain soft tissue coverage. Finally, healthy bone should not be excised simply to permit shortening to obtain soft tissue coverage because free tissue transfer is successful in experienced hands in a high percentage of cases and restoration of lost bone stock even by distraction osteogenesis is a long, difficult process. Bone Transport for Acute Injuries with Bone Loss: Technique (Fig. 2) Wound debridement is performed as an emergency, and limb stabilization is achieved with provisional external fixation. For bone transport, as with any method of management of severe open fractures, excellent debridement is critical for successful management and repeat debridement is always indicated. A temporary fixator stabilizes the fracture to facilitate soft tissue care and patient mobilization. It is not necessary for any of the screws or wires from the temporary fixator to be incorporated in the bone transport fixator; therefore, rapid application can be performed in the most efficacious location and may include spanning a joint. The application of the bone transport frame and corticotomy can then be accomplished on an elective basis in conjunction with a debridement after extensive preoperative planning. At this time the decision as to whether to pursue limb salvage may also become clearer. The choice of frame type for bone transport varies with the injury and the experience of the surgeon. Our preference is for a monolateral frame. Access to soft tissues is better, application is straightforward and patients may have more tolerance for the less bulky frame. A small wire ring fixator or a hybrid frame has advantages, when a bone deficit is close to a joint. The

small juxta-articular section of bone is more reliably stabilized with tensioned wires than large screws. Trans-articular stabilization across the knee or ankle may be necessary in certain traumatic injuries, and the flexibility of a circular frame permits these elaborate constructs. The technique of application of an external fixation frame for bone transport can be complex. Preoperative planning is essential for optimal results. The location of the anticipated corticotomy and of screws or wires should be planned in advance. For large defects (greater than 6 cm) two corticotomy sites might be planned. Consideration needs to be given to the soft tissue injury and the anticipated effect of acute shortening. The ideal method for preparation of bone ends on either side of the gap is unknown. Oblique and cornminuted sections of bone, if viable, may be left in place or further shortened and squared off. The advantages of square ends are better stability after contact is achieved and less likelihood of developing bony obstructions to transport. Despite these advantages, it is our preference to save as much viable bone as possible. Once the frame is applied, we recommend some closure of the bone gap. This has the advantage of earlier contact across the defect, which encourages healing and decreases the need for late docking site bone grafting. In addition, limb shortening allows closure of soft tissue defects by local muscles or by split-thickness skin grafting. In unusual cases with transverse wounds, primary closure can be obtained. Distraction is begun 7-14 days postoperatively, depending on the location of the corticotomy, soft tissue conditions, and the age and osteogenic potential of the patient. Transport of the central section of bone is continued until the gap is closed and contact between the fragments on either side is achieved. Distraction may then continue to correct any leg length discrepancy. In cases where the defect is initially closed by shortening the limb, the entire distraction phase is performed to regain leg length. After the completion of distraction osteogenesis. the frame is locked and the regenerate allowed to consolidate. During this period progressive weight-bearing is encouraged to stimulate callus maturation. Roentgenograms are obtained weekly during the distraction phase, then every 24 weeks during the maturation of the regenerating segment. External fixation is continued until there is radiographic consolidation at the distraction and the docking sites. For tibias, bracing after fixator removal provides further protection. Methods Available to Decrease Treatment Time Since prolonged treatment time with cumbersome external fixation continues to be one of the drawbacks of bone transport, any method that can potentially decrease the time of treatment without increasing complications is welcome. Two methods are currently in use. Preliminary limb shortening to obtain early

contact across the gap speeds healing at this site and decreases the incidence of non-union. It also allows distraction to be terminated prior to full restoration of length in patients who are non-compliant or intolerant of the technique. Secondly, where a substantial amount of bone transport has occurred ( > 2 cm), aggressive treatment to stimulate osteogenesis at the docking site is required. Cancellous bone grafting just prior to the time of contact has been utilized most commonly Bone marrow injection or local decortications without grafting are alternative procedures for stimulating earl) union at this level. Bone transport o\‘t‘r a non-reamed intramedullarq nail has been reported as a method to decrease the time in an external fixator frame.” When contact ;tcross the gap has been obtained and length restored, (he fixator is removed and replaced with locking screws. This method has been described for four patients with grade II to IIIB open tibia1 fractures and an average defect of 9 cm: all healed with an average treatment time of 31 days/cm of regenerate. This represents d significant decrease in the time of external tixation. This advantage must be weighed against the risk of simultaneous external fixation and intramedullary implants. Finall!. other experimental methods to speed heating may have application to distraction osteogenesis in general and bone transport specifically. These include electrical stimulation, ultrasound and bone growth stimulating factors such as demineralized bone matrix ;md bone morphogenic protein. and osteoblastic cell cultures. While these methods are still experimental. they offer the possibility ofspeeding the process of distraction osteogenesis and therefore decreasing the o\,er;ill treatment time. These exciting

prospects could further expand the indications bone transport in the field of acute traumatology.

for

References

Book review The Practice of Shoulder Surgery

Edited by Ian G. Kelly. Oxford. I W.?

Butterworth-Heinemann

Ltd.

_____

ISBN

0

7506 1383 I

35Xpages

Price

f75.00

rhere IS a rapidly expanding interest in shoulder surgery world wide, and there arc now UK and European groups. in addition to I he North American\. with particular interest in this complex Joint. and this book is a welcome addition to the library OF knowledge on the subject. It is a moderate sized work of some 358 pages, but the text is extensively aupportcd by 390 illustrations as line drawings. X-rays and photographs. and some tables. ‘The editor has managed to bring together the Ih authors. who are almost exclusively drawn from the UK. to produce a universally well written 30 chapters. from anatomy and biomechanics. to sports Injuries. and rehabihtation. The chapters individually are authoritative and well supported with up-to-date references. Mr Kelly himself. in his chapter on Clinical Examination of the Shoulder. cmphaslses the need for an international

standard for the assessment of shoulder function. which would be useful in comparison of results following injury or surgery. A useful patient’s self-assessment pro-forma is included next to the surgeon’s/therapist’s clinical assessment in the chapter on Rehabilitation, and I’m sure this is the direction that we, as shoulder surgeons, should be going. The chapter on arthroscopic surgery of the shoulder is inevitably brief. and could not possibly cover this particular aspect of shoulder surgery in great detail, but did lack some necessary illustrative material for the visual topic it aimed to cover. The only other omission in the book as a whole was the acromioclavicular joint. which was only briefly mentioned in the chapters on Impingement Syndromes., and Arthritis and surprisingly only mentioned in reference to the rare condition of Clavicular Osteolvsis in the chapter on Sporting Injuries,. Overall. this book can be recommended to the tramee and resident who require concise yet fairly comprehensive knowledge of the shoulder joint complex. and will sit well with other orthopaedic texts in libraries around the world. MI(WAfI F WALSH