If you can get it sort of balanced once you have inserted your implants - which is not that unlikely - then I would go for an LPS design, otherwise constrained. For extensive bone loss, which can not be corrected with your cuts, you will have to use wedges combined with intramedullary rods.

If you can obtain a well balanced knee with a single PS prosthesis it would be the best choice. If the LCL is really uncompetent, this laxity after a release of the MCL and the flexion deformity would be controlled with a LCCK prosthesis to preserve a joint line in its height. In this case tibial and femoral intramedullaries rods could be used.

Metallic wedges or bone grafting would be used to reconstruc the tibial bone defect.

Thanks Dr Alfred and Dr Gilles!

In our hospital we try to fix normal condylar PS prosthesis with additional bone grafting as necessary. If there is a large bone deficit - sometimes additional tibial (or femoral) stem is required. Always proper knee balancing is a priority. If severe medial release is not sufficient in some cases we can implant a semi- constrained or hinged prosthesis but the decision is always intraoperative.

Right, I agree with you. In this case I have to anticipate the bad situation with a persistent laxity. I do this surgical procedure with a constrained knee prosthesis ready to be used. But always when I can do it I perform a PS prosthesis of course

I manage these types of cases with a meticulous medial subperiosteal tibial release, routine cruciate sacrifice, and MCL pie-crusting to achieve a balanced knee. Usually this can be managed with a standard PS implant, however, I always have a revision option available in the OR for a constrained post. I use the Stryker Triathalon TKA system and their constrained post allows 7 degrees of rotational motion, which is more than in other designs. Note that this case can be managed with implants from any manufacturer. The real key is the handling of the soft tissues in a careful, attentive, step-wise fashion during the case. I reserve stems for osteoporotic bone or if I do choose the use of constrained implants. Good luck and Best Regards. LR

Sometimes it is difficult to decide what to do in these cases. Of course you need more soft tissue release so it will be difficult to get a proper gap balance. Previous deformity implies LCL laxity and flexion deformity needs hard posterior release so after osteotomies it is not so easy to achieve a balanced knee. You should recruit as much options as you can during surgery. A constrained implant with the aid of wedges or graft could be a good option, but I will be ready to a hinged prosthesis in case of well established varus and flexion deformity

Good luck and success in your performance. Regards. AS

Thanks Dr Silvestre!

Regards

Dear Dr Gupta Sir

I would not, in a varus OA, consider a constrained implant. that is really an extreme situation. I would actually do the femur first as I do always, and then do limited tibial cuts as required by the implant. At this stage also i would not release the MCL beyond needed for exposure. The build up medially and lateral translation of the tibial component with an occasional need for downsizing the tibia would usually take care of the situation. It is rather imperative than in an attempt to balance to the loose LCL, one does not overrelease the MCL and land up with a constrained implant. Yes I do like a stem in larger defects and my balancing with MCL release comes a bit later and is very guarded. I agree a lot with Dr Rubins suggestions

I can not exactly agree with dr Poduval. The tibial component has to be positioned to cover the whole tibial plateau. Any medial - lateral translation of a tibial component or even downsizing is not a good option for may interfere with an implant survival. Both components have to positioned in one line, to restore alignment of the extremity and make mechanical axis to pass through the center of the knee (or slightly medial). Any downsizing of a tibial component will interfere with proper mechanical support to this component. I can't agree also that overrelease of MCL is possible. The constrained implant is required usually because of underrelease of MCL that results in imbalance knee.

What is worth undrelining- the initial distal femoral and proximal tibial cuts are to be made very conservative in such a varus knee. I personally ones landed with a poly insert of 18mm because of excessive initial cuts. So first very conservative cuts have to be performed - then the knee should be balanced - and the final additional proximal and distal cuts are then to be performed.

What 's about "the extremely stretched out lateral collateral ligament " ? It is the point which could not be forgotten; it s why I keep a constraint prosthesis in my mind . A periperical ligamentary insufficiency could not solved with an adapted release !

We use RT plus modular or monoblock knee prosthesis (S & N).

The algorithm would depend on the age and demands of the patient. The danger of trying to 'balance' a stretched out LCL is to over-stuff the knee and produce significant stiffness. In my experience I have seen surgeons 'balance' the capsule when they think they are balancing the ligaments. I would therefore caution against this and advise using a rotating hinge type device in cases where balance cannot be easily achieved and the patient is elderly or relatively low demand

Initially there is no clear cut in the question of the severity of bone deformity. This to be clarified. Taking in consideration the gradual bone loss the suggestion can be as; the old teaching of soft tissue balance and reconstruction of the bone losses (contained or uncontained) with bone graft of blocks or lately sleeves is there. The use of blocks or sleeves resulting to stems. As the anticipated releases will involve all ligaments but the lateral collateral a posterior stabilising component will perform better. The extreme releases for balancing need to be controlled and be supported according to the bone loss and the limb lengthening. In case of anticipation of soft tissue inbalance due to extreme bone loss and the releases, rotating linked prostheses need to be considered. So please clarify the deformity and take the options available to you; this may be an algorithm, as the joint is a combination of bones and soft tissues and the solution has to touch both.

In my humble experience, soft tissue balance is the key for implant choice. Severe valgus or varus deformity leads me to use a PS implant once osteotomies, soft tissue relase and gap measurements have been done . If previuos subluxation or unacceptable instability appears when preparing femur and tibia, rods (specially in tibial component) provide good feelings at the end of the procedure. I reserve constrained prosthesis for severe joint destruction (revisions, tumors, etc and very poor bone quality)

This is a great question. I encounter this situation commonly in my uninsured patients that have gone a long time without care.

Many of these knees can be balanced with an implant that does not have varus/valgus constraint but certainly it would be reasonable to have semi constrained implants available as back up. I'll with a standard distal femur cut (the thickness of the implant) regardless of the presence of a flexion contracture. I template the angle of my distal femoral cut and in a situation like this if the templated angle is between 2 degrees I pick the lower number or even a degree less cheating the femur in 0.5-1.5 degrees of varus from the mechanical axis. This will make the knee easier to balance and in my opinion will likely not affect the durability of the knee replacement. The tibia however should be cut perpendicular to its axis. At this point you have to decide how much lateral bone your willing to take and/or how much medial bone you will leave un resurfaced to accomplish this task. With the system I use, downsizing a single size does not require a big lateral shift so I have no problem doing this. Releasing and excising the uncovered medial bone will also greatly facilitate balancing the knee. From the lateral side I don't want to take more than 12mm after which the lateral laxity seems to markedly worsen. If a tibial downsize, slight lateral shift, and a 12mm cut from the lateral side will not give a flat tibia perpendicular to its axis then I will use a 5mm medial block augment along with a short/stubby cemented stem. At this point I'll check the alignment of my tibial cut but I'm not going to try to completely balance the extension space. Given the fexion contracture I'm pretty sure that removal of posterior femoral osteohytes and release of the capsule from the posterior femur will be required so I'll do this before any further releases from the tibia. For the femoral cuts I am a believer in posterior referencing for sizing because I want to maintain native femoral offset. For femoral rotation, I'll use anatomic landmarks for multiple reasons (that is another discussion). At this point I'll use spacer blocks or laminar spreaders to balance the knee. Given the flexion contracture and severe varus most of the release with be posterior. The sequence I will use is first the posterior oblique ligament then semimenbranosous. If I'm still too tight medial in extension a gentle fractional lengthening of the MCL will almost always get me there. I'll use an 18 gauge needle to slowly pie crust the MCL while applying gentle traction and valgus. What I'm looking for in a perfect world is 1mm of opening medial and 2mm of opening lateral. Depending on the patient, Ill accept a little more lateral opening. What I wont accept is a completely incompetent lateral side, more than 2mm of opening on the medial side, or a medial side that is so tight that it is springing open the lateral side. In these rare situations, rather than risk making the medial side completely incompetent, I'm going with short cemented stems, and a semi constrained poly with a thickness that will allow for full extension and no springing open of the lateral side.