(52,77) Smoking is associated with increased risk of non-union, infection, and delay in healing. A meta-analysis by Schenker et al suggested an increase in time for bone healing in smokers. Various studies suggest smoking as an important risk for non-union. However, studies suggesting the risk of developing hypertrophic non-union in smoker are lacking.
6(35%) out 11 patients were a smoker in our study.Fibular bone cuff resection was done in all patient with hypertrophic non-union of the tibia. The fibula was united in all tibia non-union which may suggest fibular union itself a risk factor for failure of the union in hypertrophic non-union of the tibia.
3 patients had infected non-union. Distraction with Ilizarov also aids in the treatment of infection by increasing vascularity and regenerative process as the stated law of tension stress by Ilizarov GA and famous statement that ” infection is burned out in the fire of regeneration”. 2 out 3 infected non-union healed within 3 months of distraction in the present study. The infection resolved in 5 out of 6 patients in the study by Catagni et al. and in 2 patients in the study by Kocaoglu et al. Maini et al treated 6 patients with infected stiff non-union with deformity with Ilizarov and compression-distraction.(49) The ability of hypertrophic non-union to produce regenerate also allows correcting angular, rotational and translational deformity by simultaneous distraction. The ability to form new bone on distraction also allows correcting limb length discrepancy reducing difficulty associated with a short limb.
6 patients had deformity less than 70 angulation, 3 had a deformity of 70 to 150 in any plane, 8 had deformity more than 150 before treatment. The deformity was corrected to less than 70 in 13 patients after treatment. The median limb length discrepancy was 15 mm ranging 4 to 66 mm with average of 19.8 mm before treatment. Kocauglu et al reported average LLD of 22.5 mm.
After treatment Limb length was equalized to within 1 cm in 15 patients. 2 patients had persistent LLD of more than 2.5 cm out of which distraction was stopped early in one patient due to pain and early consolidation whereas regenerate fracture occurred in another patient. Limb length was equalized within 1 cm in 86% in the study by Catagni et al and in all patients in the study by Kocauglu et al.The various other modalities have focussed on stability by compression or absolute immobility like compression plating. Modalities for compression requires the opening of the non-union site which affects the soft tissue and vascularity, more blood loss, delay in weight bearing.
Ilizarov is a percutaneous method of circular external fixation with minimal blood loss.Ilizarov fixation allows mechanical stability required for consolidation while allowing mobility and weight bearing. Full weight bearing was allowed after completion of distraction after final tightening of nuts and hinge. Full function of the extremities can be encouraged by early weight bearing which may improve functional status early.Iwakura et al concluded that nonunion tissue contains mesenchymal progenitor cells which has the ability to form bone and cartilage and can be stimulated to form bone maintaining vascularity and stability.(42)The non-union site was not exposed in most of the patient. The non-union site was minimally exposed in some patients to remove the previous implant, debride infected tissue with minimal soft tissue dissection supporting procedure to be lesser invasive. Bone graft was not applied to any patients in the study.
The morbidity associated with bone grafting is also eliminated as our treatment modality utilizes non-union tissue as the source of new bone which supports the potential of hypertrophic non-union tissue to form new bone and heal.The torsional and shear forces are eliminated by application of Ilizarov fixator and distraction at the non-union site which aids in the new bone formation and healing. The study supports the theory of stimulation of non-union tissue leading to the metaplastic conversion of fibrocartilage tissue into the bone by gradual distraction and microenvironment stabilization as described by Ilizarov G. A by producing controlled tension stress.ADL improved in most of the patient at 8 months of distraction, 11 patient could perform ADL without difficulty and 3 patient with minimal difficulty.
3 patient could perform most of their ADL with some difficulty. Improvement in ADL further is expected on longer follow up as all patient had improvement in ADL during treatment and assessment was done at 8 month which is early compared to other similar studies.There was a significant improvement in pain score after treatment at 8 months (p< 0.001) analyzed by Wilcoxon signed-rank test. The stiffness of knee and ankle was a frequent problem, the range of motion of adjacent joint was restricted more than 150 in 8 months which was probably due to inadequate physiotherapy, patients compliance. The outcome assessment was done early at 8 months in our study compared to other studies which had longer follow up.15 out 17 patients achieved non-union within 8 months.
All patient achieved union by 9 months with a mean of 6.38 ±1.69 months. Average time spent in Ilizarov fixator was 7.20±1.82 months with a range of 4 to 10.5 months.The bone outcome was excellent in 11 patients, good in 2 patients, fair in 2 patients, poor in 2 patient at 8 months of distraction.
The function outcome was excellent in 5, good in 6, fair in 5 and poor in 1 month at 8 months of distraction based on ASAMI evaluation. In a study by Catagni et al outcome of treatment with distraction with Ilizarov on stiff nonunion were excellent in 14, good in 4 and fair in 3 patients.There is a paucity of a study assessing bone and functional outcomes of distraction osteogenesis in hypertrophic nonunion and early outcomes.