Injury factors, surgical timing important in treatment of knee dislocations

Bruce A. Levy

ORLANDO — In a presentation at the Arthroscopy Association of North America Annual Meeting, Bruce A. Levy, MD, noted the importance of recognizing whether a knee dislocation is a limb-threatening injury.

Perspective from Lars Engebretsen, MD, PhD

For patients who present with high-energy knee trauma, Levy recommends surgeons acquire an ankle brachial index.

“If the [ankle brachial index] ABI is greater than or equal to 0.9, the odds of having a major arterial lesion are zero — 100% negative predictive value,” Levy said in his presentation.

Patients with an ABI less than 0.9 should undergo CT angiogram, which Levy noted is fast, less invasive than conventional angiography, has one-fourth the radiation exposure and has high sensitivity.

Vascular lesions also affect outcomes of a dislocated knee, according to Levy. He cited results from a previously published study which showed patients with a vascular lesion that required a popliteal artery bypass graft experienced significantly lower functional outcomes than patients without a vascular lesion.

Levy also reviewed results on patients with vs. those without peroneal injury, which showed a higher restoration of normal anti-gravity dorsiflexion among patients with partial nerve palsy.

“No matter what we did to that nerve, only 38% [of patients] regained anti-gravity dorsiflexion if they had a complete peroneal nerve palsy,” Levy said.

Levy noted that optimal surgical timing for the dislocated knee is still unknown, with previous research showing an increase of arthrofibrosis with early surgery despite improvement in patient outcomes, as well as good outcomes with staged surgery. He said a new, multicenter randomized clinical trial to compare early vs. delayed surgery of the dislocated knee is underway.

“[There are] two arms in the trial: Patients are randomized to acute vs. delayed surgery and early vs. delayed rehab,” Levy said. “So, hopefully, this trial will shed some light on optimal patient outcomes.” – by Casey Tingle

Reference:

Levy BA. Dislocated knee: Current concepts. Presented at: Arthroscopy Association of North America Annual Meeting; May 2-4, 2019; Orlando.

Disclosure: Levy reports he receives IP royalties from Arthrex Inc.; is a paid consultant for Arthrex Inc. and Smith & Nephew; receives research support from Biomet, Smith & Nephew and Stryker; and is on the editorial or governing board of Clinical Orthopaedics and Related Research, Journal of Knee Surgery, Knee Surgery, Sports Traumatology, Arthroscopy and Orthopedics Today.

Perspective

Lars Engebretsen, MD, PhD

I have recently had Gilbert Moatshe, MD, PhD, reviewing our results on more than 300 knee dislocations from May 1996 through 2016. We certainly agree with Levy on the importance of early detection of vascular injuries and on the use of an ankle brachial index.

However, although vascular injuries complicate the overall treatments, our experience is that it does not lead to a reduction in the functional or patient-reported outcome measure results. Our patients with vascular injuries had identical functional and subjective results with the nonvascular injured knee dislocations.

As for the nerve injuries, in practicality the peroneal nerve, similar to Levy, our patients with a complete neural palsy did not regain their function. We have had good results in these patients with tibial tendon transfer 6 to 12 months after the knee dislocation. However, almost all with a partial nerve injury regained their function within 6 to 12 months.

We agree that the issue of nonoperative vs. a surgical approach is still not resolved. The old literature from open surgery and casting postoperatively reported on arthrofibrosis problems and suggested staged surgery as a solution. We have reported good functional and patient-reported results from acute surgery within the first 2 weeks.

Our experience has not been good when outside hospitals have performed surgery on, for example, only the ACL and left the rest of the ligaments to us. In Norway, staged surgery does not work well.

However, I do agree with Levy that the jury is still out on the nonoperative approach in a segment of this population. There are studies ongoing in Denmark and the U.S. which should give us needed information.

Reference:

Moatshe G, et al. Orthop J Sports Med. 2017;doi:10.1177/2325967117706521.

Molund M, et al. Clin Orthop Relat Res. 2014;doi:10.1007/s11999-014-3533-x.

Lars Engebretsen, MD, PhD

Professor in orthopedic surgery

University of Oslo

Oslo, Norway

Disclosures: Engebretsen reports he receives grants from Arthrex, Smith & Nephew, Thon Foundation, the International Olympic Committee and the Norwegian Department of Culture.