Getting Hip to New Techniques
Getting Hip to New Techniques
Tennessee-based Wright Medical Group, Inc. is a global orthopaedic medical device company specializing in the design, manufacturing and marketing of reconstructive joint devices and biologics.

Among the company's specialty lines, the CONSERVE® family of hip implants is designed to preserve as much bone as possible and lends itself to new minimally invasive approaches to hip resurfacing and total replacement.

For total replacement, one of the innovations is the development of BFH™ (Big Femoral Head) technology that mimics the body's natural head with a large diameter implant that reduces the chance of dislocation.

Dr. William Kurtz, an orthopaedic surgeon affiliated with Tennessee Orthopaedic Alliance who practices at Baptist Hospital, has recently returned to Nashville after completing a one-year fellowship in adult reconstructive joint surgery in Boston. While in Massachusetts, he worked with Dr. Stephen Murphy who has created a new surgical approach to total hip arthroplasty. Murphy, who is developing the instrumentation and procedure with Wright Medical, uses a superior approach rather than the traditional anterior or posterior approach that requires the surgeon to dislocate the hip.

Kurtz, who performed more than 50 of these procedures in Boston and will bring the technique to Nashville, says superior capsulotomy works with the big femoral head or with traditional components and can be performed on a wide array of patients, including those who are overweight.

For the most part, "all comers" are welcome, according to Kurtz, with the exception of the patient who needs to have his or her leg intentionally lengthened, such as those with dysplasia. In cases where the surgeon wants to intentionally lengthen more than 1-2 cm, this procedure is not optimal because the preservation of the soft tissue makes it impossible to lengthen much more than 15 mm, Kurtz explains.

"It's truly a minimally invasive technique because it is a small incision, but the most important part of it is that the soft tissue dissection near the hip joint is as atraumatic as possible," says Kurtz. "You don't cut through the deep muscles, and you don't violate tissues that are important to the stability of the hip socket."

With an anterior or posterior approach, surgeons have to dislocate the leg by twisting and rotating it about 90 degrees from its normal position.

With the superior approach, Kurtz says, "The hip is laid in a normal position … like you were going to bed. The leg is never contorted into an abnormal position."

When opting for this approach, surgeons should be aware that the implant components must be put together inside the hip joint, and the surgery dictates the use of a modular femoral stem.

Typically the superior approach takes no more than 15-20 minutes longer than a traditional hip replacement. Kurtz says the extra time is warranted because the technique enables a surgeon to preserve the soft tissue structures.

In addition to less postoperative discomfort, Kurtz says there is observational evidence that points to recovery times being better in comparison with traditional hip replacement.

Wright is also rolling out another minimally invasive hip replacement technique developed by Dr. Brad Penenberg in Beverly Hills known as PATH™ (Percutaneously Assisted Total Hip). Like the Murphy method, PATH™ is truly a minimally invasive technique with an emphasis on preserving soft tissue underneath the incision.

Patrick Fisher, Wright Medical's hip product manager, notes, "We used to cut four or five tendons, as an example, and now we only release one tendon. It's a return to activity quicker because of the soft tissue sparing." He adds that with fewer tendons and muscles being cut and stretched, there is also less blood loss.

Prior to these new MIS techniques, a surgeon had to excise the capsule. Today's surgeries leave the capsule intact with just a small incision where the hip components are built within. This also preserves the natural synovial fluid, which improves lubrication on the new hip bearings.

Gary Henley, president and CEO of Wright Medical Group, notes that the final refinements to the instrument sets for the PATH™ procedure have recently been completed and national physician training is underway.

In concert with the newer techniques is the improvement of the components. The big femoral head, for example, is a 50 mm head compared with the 28 mm heads that have been the standard.

"It really replicates the person's anatomy," Fisher says of the larger heads.

Today, the heads can articulate directly onto the socket whereas before they had to articulate on a plastic liner. Because the plastic liner has to be built to last, it must be very thick. Therefore, it takes up a lot of available space so the head has to be smaller to accommodate the liner requirements. Now Wright has a metal-on-metal option that has allowed for the much larger head.

Fisher says the dislocation rate in a traditional hip replacement using the 28 mm head is in the range of 2-3 percent. With the BFH™ technology, that rate of dislocation has dropped to 0.5 percent.

"The PATH™ technology coupled with the BFH™ technology has the potential to revolutionize a surgeon's practice and their patient's outcomes," Fisher says.

Henley adds that the longer wear on these stronger, newer components expands the indications for hip surgery offering relief to younger patients.

Certainly, one patient that has seen a dramatic life change is tennis great Jimmy Connors.

"His story is quite compelling," says Henley. "We all have the vision of Jimmy Connors as a warrior on the court … and deservedly so. But, he had come down with this horrible, chronic hip pain but was afraid to have surgery."

The pain had gotten so bad that he had difficulty walking even short distances, let alone getting on the courts. After his damaged hip joint was replaced using the PATH™ method with Wright's CONSERVE┬« product line including the metal-on-metal BFH™, Connors was back on the courts in six weeks. He's once again active in the tennis world as Andy Roddick's new coach.

Connors has now partnered with Wright to help the company in its efforts to educate the public about recent advances for the treatment of chronic hip pain.

October 2006