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Surgeon finds hinged knees an alternative to TKA for patients with OA
The status of a patient's collateral ligaments and age can help determine whether a hinged knee implant is indicated.
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ORLANDO, Fla., USA — In specific circumstances, hinged knee arthroplasty can be a valuable tool for orthopaedic surgeons and a viable option for patients with osteoarthritis, according to a knee surgeon who recently discussed the role that hinges have in primary total knee arthroplasty.
“I think there are still primary indications for a hinged knee,” Thorsten A. Gehrke, MD, of HELIOS ENDO Klinik Hamburg, said at the Current Concepts in Joint Replacement Winter Meeting, here. “In my daily practice, I would say 3% to 5% of my knee implantations are hinged knees in the primary situation.”
Gehrke presented potential indications for rotating-hinged or pure-hinged implants in primary total knee arthroplasty (TKA).
When to use hinged knee implants
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: Gehrke TA
While the majority of 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 for the patient, according to Gehrke.
In his presentation, Gehrke 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.
A patient’s age also can be an indicator that a hinge knee may be an appropriate procedure, according to Gehrke.
Concerns noted
Gehrke said the literature surrounding hinged knees is somewhat inconclusive.
“We did our own study with over 230 cases in the primary situation. And we had, after 13 years, a 90% survival [rate],” he said.
Should revision surgery be required, which is often of concern to surgeons, Gehrke told Orthopaedics Today Europe that there is a sound strategy for the revision procedure.
The surgical result after implanting the Link Endo-Model hinged knee [Waldemar Link; Hamburg] is shown.
Lateral views show the implantation of a hinged model knee in this 70-year-old patient.
“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,” Gehrke told Orthopaedics Today Europe.
Instead, impaction grafting is a reliable alternative, he noted.
“We therefore recommend an impaction grafting technique utilizing allograft cancellous bone chips and 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, allows 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.
Advantages and limitations
Rehabilitation following hinged knee replacement is not critical. 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
- Reference:
- Gehrke TA. Paper #120; Presented at: Current Concepts in Joint Replacement Winter Meeting; Dec. 12-14, 2013; Orlando, Fla., USA
- For more information:
- Thorsten A Gehrke, MD, can be reached at Holstenstrasse 2, 22767 Hamburg, Germany; email: tagehrke@gmail.com.
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.