“There is a great track record on constraint for intraoperative MCL injury. The bonuses: no need for sutures or staples, no need for a hinged knee brace, full weight bearing, early ROM, and an excellent long term survival!” argues Paul Lachiewicz. But Josh Jacobs counters, “CCKs in primary TKR are not very conservative…you’re resecting a lot of bone. And there are issues of wear and ease of removal.”
This week’s Orthopaedic Crossfire® debate was part of the 31st Annual CCJR – Winter meeting, which took place in Orlando this past December. This week’s topic is “Intraoperative MCL Injury Requires Constrained Components.” For the proposition is Paul F. Lachiewicz, M.D. of Duke University Medical Center. Joshua J. Jacobs, M.D. of Rush University Medical Center is in opposition. Moderating is Steven J. MacDonald, M.D., F.R.C.S.(C) from the University of Western Ontario.
Dr. Lachiewicz: “In the past, people have had a bad taste in their mouths from the so-called constrained prostheses because these did have high rates of complications and loosening. But the modern constrained condylar prosthesis has almost 30 years of a track record.”
“It’s unusual to have to do this in a primary total knee arthroplasty. It’s generally indicated for a fixed valgus deformity, usually in an elderly patient. I’ll concentrate today on the incompetent medial collateral ligament (MCL). One example, done by one of my former partners, involved a valgus knee where the MCL was ‘slightly weakened’ intraoperatively. Five months postoperatively I saw this patient with an embarrassing instability.”
“Beware of patients who have a staple or a screw at the medial epicondyle. In one example, a surgeon removed a stone staple from the medial epicondyle. The MCL was thought to be fine, but two weeks postop the knee was unstable. Also, beware of patients with heterotopic bone at the medial joint line. Once that bone comes out to mobilize the knee there is no adequate MCL.”
“What happens if there is an ‘inadvertent’ division of the MCL? This occurs anywhere from less than 1% to almost 3%. If I determine that the MCL is shot, then I will use an intercondylar cutting guide for the femoral component.”
“Postop rehab is easy, with routine pain management, no knee immobilizer, no brace, full weight bearing, early range of motion (ROM)…I even use a continuous passive motion machine in the hospital.”
“We’ve published two series on this. The first was with the older version (TCP III, I-B II). We had 44 knees, and a 10-year survival rate of 96%. The main problem with this knee was that the patellofemoral mechanics were not optimal; we had to do a lot of retinacular releases. We had no post breakages—even at 10 years. We did have three revisions.”
“In our most recent series (February 1999-present) we used a stem with the tibial component. On the femur I used a .145 mm stem. There were 27 knees with a mean follow-up of five years; we did have two that were an actual disruption of the MCL. We tried to balance all of these knees. I don’t routinely go to a CCK (constrained condylar knee); we do routinely use stems. There were no mechanical complications, no loosening, and no post breakage. We did see two patients with stress fractures of the patella.”
“Maynard et al. (Journal of Arthroplasty, 2014) involved 132 primary CCKs…a lot! This is because their indications were very broad: >5mm of mid-flexion laxity, no aseptic loosening at seven years…but they did have some patellar complications.”
“The advantages of CCK for intraoperative MCL injury are that there is no need for sutures or staples, no need for a hinged knee brace, you don’t have to manipulate these patients, full weight bearing, early ROM, and an excellent long term survival.”
Dr. Jacobs: “From the article by Galante et al. (Clinical Orthopaedics and Related Research, 1991), we know that coronal balance is critical to total knee arthroplasty (TKA). The general consensus is that an injured MCL with coronal imbalance should be addressed.”
“We have published on this (Leopold et al. The Journal of Bone and Joint Surgery, 2001). We had 16 cruciate retaining (CR) TKA with intraoperative MCL injuries. It involved a primary repair and six weeks in a hinged knee brace; there was no increased constraint. We had excellent results, with a mean Hospital for Special Surgery (HSS) Knee Score of 93 and no instability at a mean of 45 months.”
“We took this further, looking at a larger cohort (including varus and valgus knees) and had a longer follow-up. It was a retrospective review of intraoperative MCL injuries during primary TKA from 1991-2009. We either repaired it end to end for mid-substance lacerations or with a suture anchor/screw washer for avulsions. We exposed the ligament, used running, locking, non-absorbable braided sutures for end to end repair of mid-substance lacerations. For avulsions, two sutures were used in a running/locking fashion distal to proximal, then proximal to distal tied over a screw washer or to a suture anchor.”
“We placed the sutures into the ligament prior to cementing, and the sutures were tensioned with the knee in mid-flexion with a final polyethylene spacer in place. The patient was placed in an unlocked knee hinged brace for six weeks. During rehab we ordered unrestricted, full weight bearing, along with free ROM in the hinged knee brace. The brace was discontinued at six weeks.”
“We looked at HSS Knee Scores, radiographic reviews, subjective complaints of instability, and the physical exam. And of our nearly 4, 000 consecutive primary TKAs, there were 48 intraoperative injuries (split between lacerations and avulsions). We lost 3 patients, leaving us with 45 and a mean follow-up of 89 months; 35 were cruciate retaining, 10 were posterior stabilized. They were mostly varus knees.”
“There were no subjective complaints of instability in any of these patients. There was no instability on the physical exam in full extension or in 30 degrees of flexion; there was no need for functional bracing. And their HSS Knee Scores increased 46.8 points after repair. Finally, there was no radiographic evidence of instability and ROM was respectable. Four knees did require manipulation under anesthesia, and three knees required revision; there was no hardware migration or breakage.”
“The paper by Lotke did have suboptimal results with repair, but our results suggest that primary repair works…whether it’s a varus or a valgus knee…whether it’s a laceration or avulsion. However, stiffness was a real problem, so it made us wonder whether the brace was really necessary. We can get away with this because of the important role of the posterior cruciate ligament (PCL) in secondary valgus stabilization (as reported by one of the investigators in Leo Whiteside’s lab). And after MCL release, valgus laxity was statistically greater in patients that had a PCL sacrifice or a PS prosthesis.”
“There are problems with increased constraint, including increased stress at implant interfaces and increased stress and poly wear of the tibial post; it’s certainly less conservative. These are all of the reasons we don’t use these implants routinely for primary TKA. And, you may be in a situation where you rupture an MCL intraoperatively and semiconstrained implants may not be available.”
“To cave a bit to Paul’s argument, we still think you should use caution when using a PS because of the important secondary stabilizing effect of the PCL.”
Moderator MacDonald: “Paul, what do you do to minimize injury to the MCL in the first place…so that you’re not in this situation?”
Dr. Lachiewicz: “In the severe varus knee you must be certain that you’re not stripping all the way down. You do a minimal release at the start, put the spacer block in (or trial component). During the cuts you need a retractor, a Hohmann under the MCL…don’t cut it. But there is going to be the rare case where it will be disrupted.”
Moderator MacDonald: “Josh, same question.”
Dr. Jacobs: “Often, you don’t realize that it’s happened until you’re putting in your spacer or trials. I agree…you do a bit of a medial release initially, then make sure that at all times the MCL is protected with a retractor (and that they aren’t retracting too forcefully).”
Moderator MacDonald: “So you can either repair it or constrain with polyethylene. Paul, do you ever repair it?”
Dr. Lachiewicz: “I did once, and I put multiple sutures and took it through a stress and the sutures just ripped through. I think the fears that these things are going to loosen have not been borne out. We have 15 year data on people who were 50 when we put them in…they do well.”
Moderator MacDonald: “Josh, what do you do?”
Dr. Jacobs: “We have on occasion used a CCK when the MCL was totally irreparable. Back to the other point, though, we don’t use these CCKs in primary TKA because they’re not very conservative…you’re resecting a lot of bone. If you have to go back and remove it for infection it is not easy and you sacrifice even more bone. Furthermore, there is the issue of tibial post wear, which isn’t an issue with CR and not as much of an issue with PS. Even though your survivorship is high in terms of aseptic loosening, what about wear and ease of removal? These create issues that are best avoided.”
Moderator MacDonald: “So if you’re going to use the constraint for MCL rupture do you always need to stem it—even if you have good quality bone?”
Dr. Lachiewicz: “Tom Sculco had a paper with the HSS version of the CCK where the initial results (without a stem on the femur) looked good, but the follow-up has revealed femoral component loosening. I don’t usually cement the femoral stem; I put a stubby stem extension, something you can remove without much difficulty if you have an infection.”
Moderator MacDonald: “Thank you, gentlemen.”
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