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New minimally invasive hip resurfacing technique shows some hopeful results
Surgeon describes the new technique for the first time and introduces the necessary instrumentation.
GLASGOW, SCOTLAND – A surgeon is seeing promising results with a new, minimally invasive gluteus maximus splitting posterior approach for metal-on-metal hip resurfacing.
Gursharan S. Chana, FRCS(Ed), of the Royal Orthopaedic Hospital in Birmingham, England, described the procedure, which allows an average 7-cm incision, at the British Orthopaedic Association Annual Congress.
Chana developed the minimally invasive hip resurfacing procedure and instrumentation after 8 years of performing a posterior hip resurfacing approach.
“There are a number of patients who will get hypertrophic bone formation [with conventional approaches], and it can be quite debilitating,” Chana said.
Chana said he and other surgeons are already seeing patients mobilize earlier with this new technique, and he has gotten “excellent” clinical results in 136 patients who underwent the procedure, he said.
With this new metal-on-metal hip resurfacing technique, surgeons do not have to release the gluteus maximus insertion to the femur, and they do not need intraoperative fluoroscopy, Chana said.
However, the technique requires some new instrumentation. Chana assisted in developing some of the tools, including the Chana Femoral Neck Targeting Device [Orthoserve Ltd.] and Targeting Caliper. These devices allow surgeons to accurately place a guide wire in the center of the femoral neck in both anteroposterior and lateral planes. The femoral head can be prepared using the guide wire for accurate placement.
Chana also uses the Chana EZ Clean Reamer Handle [Precimed], an acetabular pusher/impactor for accurate acetabular component placement, and a minimally invasive retractor system.
Surgical procedure
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For the procedure, Chana said he uses a spinal block or general anesthetic with a femoral nerve block. Patients are placed in the true lateral position. To plan the incision, he marks the tip of the greater trochanter and draws a 5-cm line distal from the tip along the mid-femoral shaft. A right angle line is drawn posteriorly at the distal point of this line. An 11-cm line is drawn 45° from the intersection of the previous two lines. He begins the incision along the 11-cm line starting posteriorly and extending anteriorly, depending on the desired length of the incision.
Chana said he then splits the gluteus maximus fibers to expose the fatty tissue of the external rotators and releases the short external rotators. The size of the incision essentially depends on the patient’s body mass index (BMI).
“In a female [patient] with a BMI of 30 or less, you’ll get an incision of 6 cm,” Chana said. “In a big, [muscular] man, it takes about a 9-cm incision.”
Next he performs capsulotomy – “a superior, posterior and inferior release. I will not touch the anterior capsule,” Chana said.
He dislocates the femoral head and prepares it for resurfacing using the targeting caliper and the Chana Targeting Device. He prepares the femoral head down to the chamfer stage and displaces it in a pocket deep to the abductors to expose the acetabulum.
After preparing the acetabulum, Chana said he inserts the acetabular component using the special impactors. He completes the femoral head preparation, cements the femoral head component and relocates it.
“The important thing is … we can have a circumferential view of the acetabulum, and the reamer handle will allow preparation for reaming in an accurate full position and angular position,” he said.
After repairing the external rotators, Chana usually performs closure of the gluteus maximus fascia and the subcutaneous layer.
Clinical results
Chana presented 136 cases of patients who underwent this new procedure from December 2001 to February 2006. All were sent a postal questionnaire and 91 responded (70%).
The responders included 47 men and 32 women and included 12 bilateral cases. The patients were an average age of 56 years (range, 30 years to 78 years) and had an average BMI of 32 (range, 17.5 to 41.7).
He reviewed all patients at an average of 26 months (range, 6 months to 54 months). The average incision size was 7 cm (range, 6 cm to 10 cm). Patients lost an average of 245 mL (range, 100 mL to 800 mL) of blood, Chana said.
Among the responses, patients had a median Oxford Hip Score of 9.38%. Chana said he found two fractured femoral necks at 6 weeks, resulting in a 97.8% success rate at the 26-month average follow-up.
Of the two fractures, one occurred in a patient who returned to work and was walking without assistance at 2 weeks, which may have been too soon, Chana said. The other fracture occurred in a woman with osteoporosis and a slightly higher BMI. He revised both fractures through the same original incision.
He did not find any infections, nerve palsy, dislocation or hypertrophic bone formation in any of the 136 cases.
The potential of the technique
He believes the future of this type of surgery lies with systems such as the MIHR Minimally Invasive Hip Resurfacing system [Comis Orthopaedics], which is specifically designed for minimally invasive surgery.
The system uses an Electronic Neck Targeting Assistant System, which can locate the center of the femoral neck from AP and lateral views in 6 seconds, according to Chana.
“Clearly, this system is much better than what we’re used to, and has more control,” he said.
Chana said he has already trained 10 surgeons in this new technique.
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Images: Chana GS |
For more information:
- Chana G. Minimally invasive hip resurfacing. #FP141. Presented at the British Orthopaedic Association Annual Congress. Sept. 27-29, 2006. Glasgow, Scotland.
- Gursharan S. Chana, FRCS(Ed), is an orthopedic surgeon at the Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham, B31 2AP, England. He can be contacted at +44 0121 685 4181, fax: +44 0121 323 4314, or chanchana50@hotmail.com.
- Chana patented the Chana Femoral Neck Targeting Device and Targeting Calliper, the Chana EZ Clean Reamer Handle, the MIHR Minimally Invasive Hip Resurfacing system and the Electronic Targeting Neck System. He also owns and provides funding for the company Orthoserve. He receives royalties from Precimed to globally manufacture the Chana EZ Clean Reamer Handle.