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Surgeon finds hinged knees an alternative to TKA for OA patients
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ORLANDO, Fla. — In specific circumstances, hinged knee arthroplasty can be a valuable tool for orthopedic surgeons and a viable option for patients with osteoarthritis.
“There are still primary indications for a hinged knee,” Thorsten A. Gehrke, MD, of HELIOS ENDO Klinik Hamburg, said. “In my daily practice, I would say 3% to 5% of my knee implantations are hinged knees in the primary situation.”
He presented potential indications for rotating-hinged or pure-hinged implants in primary total knee arthroplasty (TKA) at the Current Concepts in Joint Replacement Winter Meeting, here.
While most TKA cases can be handled using primary non-hinged implants, stability issues can remain, especially in older patients. Some solutions to these issues can result in longer operating times and more complications, according to Gehrke.
This radiograph shows severe valgus arthritis in a 70-year-old woman.
The patient demonstrated typical lateral patellar tracking and subluxation of the patella.
Images: Gherke TA
He cited several situations that call for a hinged knee. In addition to cases of instability, a hinged knee prosthesis is indicated when there is bone loss, stiffness, new bone formation, post-traumatic deformity or complete dislocation of a knee that is devoid of stabilizing structures.
“In those severe cases, we use pure hinged knees and not rotating hinged knees” if there is extensive valgus deformity or an absent extensor mechanism, he said.
Surgeons confirmed on this long leg axis image that the patient’s knee was in severe valgus.
The surgical result after implanting the Link Endo-Model hinged knee [Waldemar Link; Hamburg] is shown.
A patient’s age also can be an indicator that a hinge knee may be appropriate procedure, according to Gehrke.
He said the literature on hinged knees is somewhat inconclusive.
“We did our own study with over 230 cases in the primary situation. We had, after 13 years, a 90% survival [rate],” he said.
Gehrke said that there is a sound strategy for the revision procedure.
“Since long, cemented stems are usually combined with a hinge implant, the metaphyseal and parts of the diaphyseal region have been in cement contact. Therefore, we strongly recommend not to simply re-cement the next prosthesis. Due to the missing cancellous bone, those implants will fail early,” he told Orthopedics Today.
Instead, impaction grafting is a reliable alternative, he noted.
Lateral views show the implantation
of a hinged model knee.
“We use an impaction grafting technique utilizing allograft cancellous bone chips, creating an Exeter-type filling of the diaphyseal canal with the new bone,” Gehrke said. “Combined impaction grafting, and often the use of tantalum cones for the metaphyseal region, allow for a proper cementing [technique] with rotational stability of the new implant. Since the collateral ligaments have been cut during the primary implantation of a hinged knee (in most cases), conversion to an implant with less constraint becomes usually impossible,” he said.
Patients with this type of implant can fully weight-bear immediately postoperatively, Gehrke said.
“There are literally no limitations to this implant and patients with severe deformities usually report relatively fast pain relief after the operation, since no ligament balancing or restrictions of the collaterals might cause any additional pain,” he said.
In severe valgus knees of older patients, a hinged knee should be the primary indication, Gehrke said.
“It allows for a quick recovery without ligamental restrictions during and after the operation. If possible, due to the rest-rotational movement, a rotational hinged implant should be the implant of first choice, if an indication for a hinged is considered in primary or revision cases,” he said. – by Christian Ingram
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Disclosure: Gehrke receives consulting and designing fees from Biomet, Waldemar Link GmbH and Zimmer, and is a member of the advisory board for CD-Diagnostics.