Introduction:
Defects in long bones pose a great challenge to orthopaedic surgeon. These can arise in long bones due to malignancy, high energy trauma and atrophic non-unions. If untreated these can lead to unacceptable shortening and may render extremity unfit for use. Historically, because of the problems involved in initial limb salvage and the subsequent difficulty of reconstructing large skeletal defects, many fractures with significant bone loss were treated by primary amputation. Modern techniques of fracture stabilization and soft-tissue reconstruction mean that many more severely injured limbs with bone defects can now be salvaged in the acute phase of treatment. Similarly, with advances in imaging modalities and effective chemotherapy, limb- saving surgery has become a standard in treating malignant and benign bone tumors, instead of a primary amputation. The resultant bone gaps are usually massive and difficult to treat. Bone gaps also result following atrophic non- unions. They are characterized by poor blood supply in the ends of the fracture fragments due to which they are atrophic and lack osteogenic potential. Amongst various methods available to bridge such bone gaps, namely, allografts, limb- lengthening procedures and vascularized and non – vascularized autologous bone grafts, we have evaluated the role of non- vascularized fibular auto- graft in the present study.
Methods
Twenty five patients with bone gap were treated with non- vascularized fibular strut grafts from June 2010 to September 2012. Thirteen cases were of gap non- union. (Figure 1a, 1b)
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Figure 1a. X-Ray of a 50 years old lady with atrophic nonunion of ulna with a failed implant.
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Figure 1b. Implant removal, resection of non- union, fibular strut grafting and fixation with rush nail. Union at both graft host junctions at 18 weeks post- operative |
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Figure 2a. Radiological and Clinical pictures of 12 years old child with osteochondroma involving proximal humerus. |
Figure 2b. Tumour was resected completely and a single fibular strut measuring 8 cm was inserted. Graft incorporated at 12 weeks post- operative. |
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Figure 3a. 44 years old patient, X-Ray showing distal femur fracture with bone loss |
Figure 3b. Fibula strut grafting with locking compression plate fixation done.Graft incorporated at 16 weeks post- operative. |
Nine cases were post bone tumor resection (Figure- 2a, 2b) and 3 cases were post traumatic bone loss (Figure 3a, 3b)
Data was collected prospectively and analysis was done using proportions and chi- square test. Statistical package SPSS Version 17.0 was used to do analysis. P<0.05 was considered as statistically significant. Written informed consent was obtained from every patient. Ethical committee clearance was obtained prior to commencement of the study. Following parameters were assessed: patient demographics, cause of bone defect, size of bone defect, quality of the bone and soft tissue envelope. One or more fibular struts were placed either intra or extra medullary in a vascular recipient host bed and augmented with the help of autogenous cancellous bone grafts and internal or external fixation devices, where required. In case of Cystic Lesions, the defect was filled with fibular struts and cancellous bone graft after curettage and appropriate fixation method was used where ever required. Primary cancellous bone grafting was done in 15 out of 25 cases (60%). Plate fixation was used in 13 cases, intramedullary nailing was used in 6 cases, rail fixator was used in 3 cases, screw fixation alone was used for one case whereas no fixation devices were used in 2 cases. Fibula was harvested using postero-lateral approach of Henry leaving at least 7 cm of distal fibula. While harvesting proximal fibula, for reconstruction of distal radius, common peroneal nerve was carefully dissected and isolated. Resection arthrodesis of knee joint was done in two cases of distal femur GCT using a long intramedullary nail spanning entire femur and tibia, with fibular struts and cancellous graft filling the bone defect. Mobilization was started immediately after surgery unless it was contra-indicated. All patients were followed up for an average period of 1.5 years (1 – 2 years). At each follow- up visit, patients were thoroughly examined for donor and recipient site complications. X-rays were taken to assess union at each graft host junction. Functional assessment was done using MSTS Score.[1] Weight bearing was allowed only after radiological union.
Results
Out of 25 patients, 17 were Males (68%) and 8 were Females (32%) with mean age of patients being 39 years (SD 13.59). Most frequently involved bone was Femur (n=11) followed by Radius (n=6), Tibia (n=3), Humerus (n=3) and ulna (n=2). Mean size of bone gap in this study was 5.19 cm (3cm- 9cm). There were a total of 71 graft host junctions in 25 cases treated. Each graft host junction was evaluated for signs of union. Out of 71 Graft-Host junctions, 68 united in a mean period of 13 weeks (8 – 20 weeks), whereas three went for non- union. A statistically significant correlation was found between method of fixation and mean time to union (p= 0.037). Time taken was minimum when plate fixation was used (Mean 11.73 weeks),whereas it was maximum when an external fixator was used (Mean 16.66 weeks). No statistical significance was found between Mean time to union and size of bone gap, use of primary cancellous bone grafting, cause of bone gap and age & sex of the patient (p>0.05).(Table- 1)
| Table1: Factors influencing average time to union and their statistical significance. |
| Mode of Fixation |
Average Time for Union (in wks.) |
p-value |
Nail |
14.6 |
0.037
Significant |
Plate |
12.79 |
External Fixator |
16.6 |
Screw |
13 |
Primary Cancellous Bone
Grafting done |
Average Time for Union (in wks.) |
p-value |
Yes |
13.01 |
0.973
Not Significant |
No |
15.4 |
Size of Bone Gap (in cms.) |
Average Time for Union (in wks.) |
p-value |
</= 7 |
14.05 |
0.340
Not Significant |
> 7 |
15.81 |
Cause of bone gap |
Average Time for Union (in wks.) |
p-value |
Post- Resection |
12.07 |
0.734
Not Significant |
Post- Traumatic |
12.60 |
Non- Union |
12.87 |
Age (in yrs.) |
Average Time for Union (in wks.) |
p-value |
<20 |
10.75 |
0.268
Not Significant |
21-40 |
13.27 |
>40 |
12.45 |
Sex |
Average Time for Union (in wks.) |
p-value |
Female |
12.0 |
0.463
Not Significant |
Male |
12.74 |
Functional outcome was assessed by Musculoskeletal Tumour Society (MSTS) Score in which results were expressed as proportion of the expected normal function. Average MSTS score was 76.63% in this study. Sex of the patient had a statistically significant relationship with MSTS Score (p=0.013), with females having better functional outcome (MSTS Score 84.37%) as compared to males (MSTS Score 72.64%). Method of fixation was also found to be statistically significant with MSTS Score (p=0.042). Highest MSTS scores were found when plate fixation was used (MSTS Score 79.25%). MSTS Score with External Fixator and intra medullary nailing were 75% and 70% respectively. Poor MSTS Scores were obtained when Screw fixation alone was used (MSTS Score 55%). Presence or absence of any complications (recipient and/or donor site) also significantly affected MSTS Score (p = 0.003). Mean MSTS Score was 82.14% when there were no complications, whereas it was 70.0% in presence of associated recipient and/or donor site complications. (Table- 2)
| Table 2: Factors influencing MSTS Score (Functional Outcome) and their statistical significance. |
| Size of Bone Gap (in cms.) |
Average MSTS Score (%) |
p-value |
</= 7 |
80.76 |
0.368
Not Significant |
> 7 |
72.5 |
Age (in yrs.) |
Average MSTS Score (%) |
p-value |
< 20 |
86.66 |
0.157
Not Significant |
20- 40 |
73.33 |
> 40 |
76.15 |
Sex |
Average MSTS Score (%) |
p-value |
Female |
84.37 |
0.013
Significant |
Male |
72.64 |
Method of Fixation |
Average MSTS Score (%) |
p-value |
Plate |
79.23 |
0.042
Significant |
Screw |
55 |
External Fixator |
75 |
I/M Nail |
70 |
Complications |
Average MSTS Score (%) |
p-value |
Absent |
82.14 |
0.003
Significant |
Present |
70.00 |
At the donor site, haematoma formation was the most common complication (n=2), others were superficial wound infection (n=1) and common peroneal nerve palsy (n=1). Haematoma required surgical drainage. Superficial wound infection was managed with antibiotics and daily dressings, wound healed in two weeks. Common peroneal nerve palsy occurred while harvesting proximal fibula. It was a neuropraxia and recovered completely in 6 weeks duration. Stiffness of the adjacent joints (n=4) was the most common complication at recipient site which was attributed to prolonged period of immobilization. Satisfactory function was regained by aggressive physiotherapy. Non- union was the second most common complication, seen in 3 out of 71 graft host junctions studied, and it required secondary cancellous bone grafting. Graft fracture was seen in one case of tibia shaft non- union which was treated with a single strut of intramedullary fibula and a single screw was used for fixation. It was managed conservatively with above knee cast. Superficial wound infection (n=2) and haematoma (n=1) were managed in a similar way as mentioned in donor site complications. (Table- 3)
| Table 3: Complications |
| Donor Site Complications |
Frequency |
Haematoma |
2 |
Superficial Wound
Infection |
2 |
Recipient Site Complications |
Frequency |
Haematoma |
1 |
Superficial Wound
Infection |
2 |
Joint Stiffness |
4 |
Non- Union |
3 |
Graft Fracture |
1 |
Shortening |
2 |
Discussion:
Bone gap is a challenging problem and the different methods available to treat it are autografts, allografts and bone lengthening procedures. Allografts are expensive, and require bone banks. Also, there is risk of disease transmission and immunogenic reactions. Moreover, allografts are poorly taken up as compared to autografts. Bone Lengthening Procedures require special surgical skills and instrumentation. It has associated risk of pin tract infection and poor patient compliance. Autologus grafts are shown to incorporate very well. They can be augmented with routine fixation methods thus requiring no special surgical skills. Fibula is the most suitable bone to transfer for a large defect in a tubular bone because of its established length, geometrical shape and strength and low donor site morbidity.[2,3] In addition to its strength, both fibulas can be used when required.[4]
Proximal fibula can also be used for reconstruction of defects in distal radius as an osteochondral graft. It provides considerable amounts of wrist motion and forearm rotation when compared with graft from ilium, tibia or wrist prosthesis.[5] At the forearm, fibular grafts allow the use of a segment of diaphyseal bone which is structurally similar to the radius and ulna and of sufficient length to reconstruct most skeletal defects affecting these bones.
Several studies have shown that vascularized grafts are significantly stronger than conventional non-vascularized grafts[6], but it is technically difficult and occasionally impossible to perform.[7] While a high incidence of stress fractures has been reported with non-vascularized grafts[8], they have also been shown to occur with free vascularized grafts.[9] In our study, there was one instance of fracture of the graft. Appropriate internal fixation device and protected weight bearing can prevent incidence of stress fractures. In animal experiments, Dell et al[10] and Brown [11] found no substantial difference between non-vascularised and vascularized grafts in the time to consolidation or in the incidence of union. Vascularised grafts were transiently stronger than conventional grafts in the first six months, but there was no difference thereafter. Enneking et al[12] found primary union in 63% of the long bone reconstructions within the first 12 months, Yadav et al [13] found union after 8 to 10 months in 60% and AH Krieg et al[14] got primary union in 89% in mean period of 24 weeks. We achieved primary union in 95.77% of the reconstructions in a mean period of 13 weeks (8- 20 weeks). Enneking et al[12] did not found any correlation between the length of the non-vascularised fibular graft and the rate of healing. Similar results were observed in our study as well.
Addition of cancellous bone grafting also did not affect average time taken for union. The complication rate at the donor site in our series was 16% and for vascularised grafts has been reported to vary between 7% and 35%.[15-19] It appears to be higher than for non-vascularised grafts whose complication rate has been reported to vary between 4% and 12%.[12,13,20] Problems in the ankle after harvesting a fibular graft have been reported to range between 10% and 40%.[16,21] We did not have any case of ankle instability after resection of fibula. Clinical studies have suggested that the distal 6 cm of fibula should be preserved to maintain lateral stability of the ankle.[22,23]
Conclusion:
Non-vascularised fibular strut grafting is an effective, simple and less demanding technique in bridging large bone gaps. It may take longer duration to achieve union, but if used in selected patients with good vascular bed and soft tissue coverage, can yield comparable results to vascularized fibular grafts in terms of overall union. It is associated with less donor site morbidity as compared to vascularised fibular grafting. However, a larger comparative clinical study is required so as to make it statistically more significant.
Conflicts of Interest:
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
References
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