In one of my recent surgeries on an obese female, the extension and flexion gaps (after the releases) were just sufficient enough for the largest insert (17.5) I had available. I was wondering what the options to tackle this situation would be if the gap was bigger.
Depends how much is the gap. Depending upon the size, options can be thick cement mantel or bone grafts. It is always better for preop assessment and come with all possible sizes
Dear Ravi
I agree with Ajai and the most important is to make a good preoperative planning
Dear Dr.Gupta,I would try to use the Maquelet’s technique, first fill the gap with a plaque and then fill it with polymetacrylate cement.After few week, redo the surgery, cutting the induced membrane rich in stem cells and well vascularized that has formed around the cement and fill the gap inside the membrane with bone graft and then sew the induced membrane and close the wound. In about 3weeks the bone should be consolidated
If tibia is bone grafted should the IM rod and uncemented component be done because cement mantle over the graft won't provide fixation of tibial component to tibia
Well, actually what I proposed is a two step surgery, first the extremity of the gap should be stabilized by means of a plaque and screws over the non-fractured bone extremity or by using an ilizarov externally, or you can try to stabilize the structure running a wire between the two sewered extremity and then fill the gap and stabilize further with the use of cement, and, may be a cast after the surgery, once the induced membrane has formed over the cement(it takes about 3 weeks), cut the membrane maintaining its integrity, break the cement with pliers and completely remove it, then fill the gap inside the induced membrane with bone fragment, stitch the membrane and then close the whole wound.In another 3 weeks the bone fragment should be consolidated and all the other fixation equipment could be removed. If you mix bone and cement I do not think you will get any fixation. It is more labor intensive but it allows for a much quicker filling and consolidation of the gap
Thats extremely interesting Dr Zangani, could you refer me to a source where I can read it in more detail.
Dear Dr. Poduval, here are some review papers about the tecnique:
J Child Orthop. 2013 Dec;7(6):477-85. doi: 10.1007/s11832-013-0535-2. Epub 2013 Oct 8.
Induced membrane technique for the treatment of congenital pseudarthrosis of the tibia: preliminary results of five cases.
J Bone Joint Surg Am. 2013 Apr 3;95(7):597-604. doi: 10.2106/JBJS.L.00310.
The mechanism of action of induced membranes in bone repair.
Orthop Traumatol Surg Res. 2012 Feb;98(1):97-102. doi: 10.1016/j.otsr.2011.11.001. Epub 2012 Jan 12.
Treatment of posttraumatic bone defects by the induced membrane technique.
Injury. 2011 Jun;42(6):591-8. doi: 10.1016/j.injury.2011.03.036. Epub 2011 May 4.
Masquelet technique for the treatment of bone defects: tips-tricks and future directions.
Take a look of this
http://www.orthobullets.com/recon/5016/sagittal-plane-gap-balancing
this seem to be the problem i have too faced especially in obese patients in early cases. economics also is a concern so in 2 cases i have used an extension rod with the tibial plate and raised the tibia with screws support in the intact tibial cut area as additional support ( like steel rods in cement column of buildings) and filled the rest of the area with cement.
as the tibia is mostly in compression mode and cement is good in compression i thought of this. agreed the preoperative planning has to be better and now i take more conservative cuts in both the femur and the tibia and revise if needed after trial so that the implant sizes are adequate.
interesting answer dr Danilo Zangani
As I assume you are in the trial stage of the operation take an interop xray with trials in place. Your joint line is at the incorrect level tibia to low and or too much of the distal femur and undersized. With the xray you can replan and adjust by grafting of add augments to revision components on the femur. These are
In principle for the primary case you don't have such problems. The previous answer is correct to look at https://www.researchgate.net/go.Deref.html?url=http%3A%2F%2Fwww.orthobullets.com%2Frecon%2F5016%2Fsagittal-plane-gap-balancing.
But for this special situation a revision prosthesis is necessary .
I agree with Cristea that this should not be a problem. I think this might be due to a wrong exposure. For instance, in obese patients with valgus knee and anteromedial approach, you will have to release the laterale side for balancing the knee while the medial structures are less sufficient because of the valgus deformity and the approach. You will end up with a wide gap in extension and flexion although the tibial cut might be normal. I strongly advise to open from lateral with a tuberosity osteotomy and lateral release. But if the medial structures are still to lax, you will need more contraint by using a hinge (RHK) or semiconstrained like a condylar constrained CCK.
In my opinion such situation is usually due to the excessive initial cuts that were performed in severely valgus or varus knee. Generally one should avoid such situation and in difficult cases (obese patients, severe malalignment) the distal femoral and proximal tibial cuts have to be performed very carefuly. Its better to make several cuts than to face with such a problem of excessive flexion and extension gaps. In my practice I once faced with such a problem (my fault of excessive initial cuts) and had to put bone grafts to the tibia (tibial component with a longer stem) and distal augments to femoral component.
Always make initial cuts step by step in difficult knees.
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