A Novel Method to Fix Type C 3 Distal Femur Fractures with Bone Defect Loss Using “ Harms Cage ”

A case of compound C3 distal femur fracture with 12 cm bone defect. After thorough debridement, the Harms cage was used to reconstruct the medial column and the fracture was fixed with the locking distal femur plate laterally. The Harms cage prevents the cantilever effect and eliminates the need for medial plating. This avoids another medial incision and preserves medial biology. At 18 months’ follow-up, plain radiographs demonstrated full reconstruction of the medial column with good range of motion at the knee joint. This technique avoids the need of dual plating in these fractures with good results.


Introduction
Distal femoral fractures are usually caused by a high energy trauma.They are complicated by a high rate of systemic and local injuries to cartilage, ligaments and skin.Hence, they are difficult fractures to treat [1].
These fractures show a bimodal pattern with a marked variation in the number of fractures in relation to gender and age.A larger prevalence of fractures is observed either in young men (about 20 years old, traffic or sport) and in old women (about 70, fall at home, osteoporosis) [2].
Based on the common principles of the AO classification, type A fractures include extra-articular fractures and type B fractures are partial articular fractures, meaning parts of the articular surface remains in contact with the diaphysis of the femur Type C fractures include complete articular fractures with both condyles being detached from the diaphysis.The fracture types are further subdi-vided describing the degree of comminution and other characteristics.Further subdivision of type B fractures includes Bl (sagittal, lateral condyle), B2 (sagittal, medial condyle) and B3 (frontal, Hoffa type).Fracture type C is divided in C1 (articular simple, metaphyseal simple), C2 (articular simple, metaphyseal multifragmentary) and C3 (multifragmentary) [3] [4] (Figure 1).
Strict adherence to basic principles and techniques is required to prevent unsatisfactory results.
ORIF of these difficult fractures is justified only if: 1) The joint surfaces can be restored anatomically.
2) Fixation is sufficiently rigid that external immobilization is not required.
3) Rigidity of fixation is sufficient to allow early and active motion of the knee joint.
4) The skin and soft tissues are satisfactory for surgery.
There is no single surgical implant that can be used for all distal femoral fractures.
Implant selection is determined by fracture pattern, patient age, bone density, and other injuries that the patient may have sustained.Rewarding results may be obtained with operative fracture intervention when appropriate patient and implant selection are made and the surgeon demonstrates meticulous skill and sound judgment [5].
A number of fixation devices such as blade plate, dynamic condylar screw, locking plates to more recently LISS, MIPPO and Distal femoral nails have been made available [6] [7] [8] [9].
For Distal femur type C3 fractures with severe comminution and bone defects it is recommended to do a dual plate fixation with bone grafting to achieve adequate stability [9] [10].
We present a novel method to fix type C3 distal femur fractures using a Harms cage with distal femur locking plates.

Case
A 21 year old male presented to us after a vehicular accident with a type C3 compound right distal femur fracture with bone defect of about 12 cm.Patient also had ipsilateral tibia shaft fracture.(Figure 2) There was no neuro vascular deficit.All blood investigations were normal.The tibia shaft fracture was treated with closed intra medullary interlocking nail immediately.Thorough debridement of the distal femur wound was done and surgery was carried out once the wound was clean.

Procedure
For the distal femur fracture the lateral approach was used and the fracture site was exposed.Hematoma was drained and the condylar fragments were reduced and fixed with cancellous screws and kirshner wires.Once the articular reduction was achieved we proceeded to build up the medial column.A Harms cage was taken of the size of the defect, in this case 12 cm and filled up with iliac bone grafts.The cage was inserted through the fracture site and punched all the way medially so that it filled up the medium column defect .Then the lateral column was anatomically reduced with the condyles and distal femur locking plate was applied (Figure 3).Patient was given an above knee cast and was kept nil weight bearing for 8 weeks.Physiotherapy was started at post op day 3. Patient was discharged at day 15 after stitch removal and AK cast reapplication.ROM exercises for the knee began at 6 weeks.Patient was allowed gradual weight bearing at 10 weeks.Patient was asked to follow up monthly and X-rays were taken.Soft callus formation started appearing at 5 weeks (Figure 4) and by 3months distinct hard callus formation with reconstruction of the medial column was seen in both AP and Lateral views (Figure 5) Good bone union was achieved by 6 months.By 18 months complete bony union with bony remodeling was visible on x-rays.(Figure 6) Patient had full extension and knee flexion up to 110 degrees and complete return of all his activities (Figure 7 and Figure 8).

Discussion
The Harms cage has been used in orthopaedic trauma to fill in segmental diaphysial bone defects with success.[11]- [19] In the spine, the Harms cage is used as a mechanical strut anteriorly to prevent kyphosis due to the cantilever effect.
We have extrapolated both these facts to the femur where the Harms cage acts as mechanical strut and reconstructs the medial column of the femur.
It prevents the cantilever effect and prevents the failure or breakage of the lateral implant.

Advantages of This Method
1) Reconstruction of the medial column in a single incision.
3) No risk of damage to the medial neurovascular bundle.4) Decreased chances of infection as lesser soft tissue handling.5) Preserves Biology medially.

Figure 2 .
Figure 2. 21-year old male with compound C3 fracture of the right distal femur with 12 cm bone defect with ipsilateral shaft tibia fracture.

Figure 3 .
Figure 3. Immediate post-operative x-ray of the lateral view showing anatomically well reduced fracture fixed with the locking plate laterally and Harms cage with bone.

Figure 4 .
Figure 4. 1 month Post-operative Anteroposterior (AP) and Lateral views showing soft callus formation along the harms cage.

Figure 5 .
Figure 5. 3 month follow up of the patient showing distinct hard callus formation with reconstruction of the medial column in both AP and lateral views.

Figure 6 .
Figure 6.Complete bony union seen at 18 months in both AP and Lateral views with remodeling the fracture site.

Figure 7 .
Figure 7. Clinical Photograph of the patient at 18 months standing.

Figure 8 .
Figure 8. Clinical Photograph of the patient at 18 months cross-legged sitting on the floor.