Medical Studies

The Influence of Head Size and Sex on the Outcome of Birmingham Hip Resurfacing

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 The Journal of Bone and Joint Surgery (American). 2010
Callum W. McBryde, MD, FRCS(Tr&Orth)1, Kanthan Theivendran, MRCS1, Andrew M.C. Thomas, FRCS1, Ronan B.C. Treacy, FRCS(Tr&Orth)1 and Paul B. Pynsent, PhD1

1 Research and Teaching Centre, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. E-mail address for C.W. McBryde: cwmcbryde@hotmail.com

Investigation performed at the Royal Orthopaedic Hospital, Birmingham, United Kingdom

Background Hip resurfacing has gained popularity for the treatment of youngand active patients who have arthritis. Recent literature has demonstrated an increased rate of revision among female patients as compared with male patients who have undergone hip resurfacing. The aim of the present study was to identify any differences in survival or functional outcome between male and female patients with osteoarthritis who were managed with metal-on-metal hip resurfacing.

Methods A prospective collection of data on all patients undergoing Birmingham Hip Resurfacing at a single institution was commenced in July 1997. On the basis of the inclusion and exclusion criteria,1826 patients (2123 hips, including 799 hips in female patients and 1324 hips in male patients) with a diagnosis of osteoarthritis who had undergone the procedure between July 1997 and December2008 were identified. The variables of age, sex, preoperative Oxford Hip Score, component size used, surgical approach, lead surgeon, and surgeon experience were analyzed. A multivariate Cox proportional hazard survival model was used to identify which variables were most influential for determining revision.

Results The mean duration of follow-up was 3.46 years (range, 0.03 to10.9 years). The five-year cumulative survival rate for the655 hips that were followed for a minimum of five years was 97.5% (95% confidence interval, 96.3% to 98.3%). There were forty-eight revisions. Revision was significantly associated with female sex (hazard rate, 2.03 [95% confidence interval,1.15 to 3.58]; p = 0.014) and decreasing femoral component size hazard rate per 4-mm decrease in size, 4.68 [95% confidence interval, 4.36 to 5.05]; p < 0.001). Revision was not associated with age (p = 0.88), surgeon (p = 0.41), surgeon experience (p = 0.30), or surgical approach (p = 0.21). A multivariate analysis including the covariates of sex, age, surgeon, surgeon experience, surgical approach, and femoral component size demonstrated that sex was no longer significantly associated with revision when femoral component size was included in the model (p = 0.37).Femoral component size alone was the best predictor of revision when all covariates were analyzed (hazard rate per 4-mm decrease in size, 4.87 [95% confidence interval, 4.37 to 5.42]; p <0.001).

Conclusions The present study demonstrates that although female patients initially may appear to have a greater risk of revision, this increased risk is related to differences in the femoral component size and thus is only indirectly related to sex. Patient selection for hip resurfacing is best made on the basis of femoral head size rather than sex.

Surgery hits hip pocket

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By Sue Dunlevy From: The Daily Telegraph January 04, 2010

ONE in every 12 hip and knee replacements need corrective operations and new surgical techniques are more susceptible to problems, according to Australia's largest health insurer. Medibank Private has reviewed its data on the 3990 hip replacements and 4860 knee replacements it paid for in 2008 and found "on average surgeons perform revisions on 8.3 per cent of their total procedures"...

...The National Joint Replacement Registry, which is studying the reliability of hip and knee replacements, has found newer joint replacements that are cementless or hybrid are more likely to need further surgery than the older cemented replacements...

...And research found the more reliable cement joint replacements are used in just 23 per cent of hip replacement operations...

...The latest report from the National Joint Replacement Registry found that three types of hip replacements - the ASR, Durom and Recap hip replacements - had more than twice the risk of revision of other resurfacing prostheses. Hip replacements with smaller femoral head sizes are also more likely to be revised.

The Allegretto knee, one of the most common knee-replacements used in Australia, has a 10 per cent revision rate at 2.5 years, which is considerably greater than other similar prostheses.

 

Hip Resurfacing is Viable Alternative to Hip Replacement

Patients who had hip resurfacing surgery, such as the Birmingham Hip Resurfacing technique, reported a better quality of life, less pain and greater satisfaction a year after surgery than those who had a total hip replacement.

PRLog (Press Release) - Jul 31, 2009 - Oceanside, NY – Patients who had hip resurfacing surgery, such as the Birmingham Hip Resurfacing technique, reported a better quality of life, less pain and greater satisfaction a year after surgery than those who had a total hip replacement, according to a study presented at the American Academy of Orthopedic Surgeons (AAOS) 2009 Annual Meeting.

The study was based on data on the outcomes of 214 total hip replacement patients and 132 hip resurfacing patients that was recorded in a joint registry maintained at a single surgeon’s practice from 2003-2006. Orthopedic surgeon Dr. Elizabeth Anne Lingard of Freeman Hospital in Newcastle Upon Tyne, England, was the study’s lead researcher.

Each patient enrolled in the study completed a questionnaire preoperatively and one year after surgery. The questionnaire included the Western Ontario and MacMaster Universities Osteoarthritis Index (referred to as WOMAC, it is a 24-item questionnaire that is completed by the patient and focuses on joint pain, stiffness and loss of function related to osteoarthritis of the knee and hip) and the SF-36, a self-report questionnaire completed by the patient that measures health-related quality of life (and generates 8 subscales: physical functioning, role limitations due to physical problems, bodily pain, general health perceptions, vitality, social functioning, role-limitations due to emotional problems, and mental health; and 2 summary scores: physical component and mental component). The patients also completed a questionnaire regarding satisfaction with their procedures and outcomes one year after surgery.

The study showed that one year after surgery both groups of patients experienced significant improvements in WOMAC and SF-36. Hip-resurfacing patients, however, posted significantly higher WOMAC scores for decreased pain symptoms. When asked about patient satisfaction with the surgery, a greater number of hip-resurfacing patients said they were satisfied with their ability to perform functional activities after surgery.

"The (Birmingham) hip resurfacing technique allows me to preserve more of the patient’s natural bone structures and stability," said Bradley Gerber, MD, Chief of Joint Replacement Surgery at South Nassau Communities Hospital. "I see hip resurfacing as the ideal solution for many of my younger, active patients who suffer from hip pain. As my patients are getting younger and younger, and are staying physically active much later in life, I've needed an alternative to total hip replacement that accommodates their age and lifestyle. Hip resurfacing is that alternative."

Dr. Gerber was among the first surgeons in the U.S. to perform the Birmingham Hip Resurfacing (BHR) technique. Rather than replacing the entire hip joint, as in a total hip replacement, hip resurfacing simply shaves off the damaged cartilage and bone and a metal cap is placed onto the head of the leg bone (femur).

Total hip replacement involves the removal of the entire femoral head and neck, replacing it with a metal ball, while the BHR leaves the head and neck untouched. It is the neck length and angle that determines the natural length of a patient’s leg after surgery. Since it is not removed and replaced with an artificial device during the resurfacing procedure, there is a greater likelihood of maintaining accurate leg length.

In addition, traditional hip replacements use a plastic socket compared to the BHR implant (which is a metal socket). A plastic socket wears down over time, and may need to be replaced surgically. In fact, it is a leading cause of follow-up surgeries.

The BHR is intended for patients suffering from hip pain due to osteoarthritis, hip dysplasia (a congenital disease that, in its more severe form, can eventually cause crippling damage and painful arthritis of the joints) or avascular necrosis (a disease resulting from the temporary or permanent loss of the blood supply to the bones, often leading to collapse of the joint surface), and for whom total hip replacement may not be appropriate due to an increased level of physical activity. For these reasons, Dr. Gerber feels the BHR is ideal for patients under age 60 who live non-sedentary lifestyles.

While the BHR implant closely matches the size of a patient’s natural femoral head (hip ball), it is substantially larger than the femoral head of a traditional total hip replacement implant. This increased size translates to greater stability in the new joint, and it decreases the risk of dislocation of the implant after surgery, which is a leading cause of implant failure after total hip replacement.

In addition to the BHR, orthopedic surgeons at South Nassau’s Long Island Joint Replacement Institute specialize in custom-fitted total joint replacement as well as minimally invasive joint replacement surgery, such as the Uni-Knee® partial knee replacement and Image-Guided Knee Replacement technique. Minimally invasive joint replacement reduces trauma to surrounding tissue, blood loss during surgery, post-operative pain, and recovery time, leading to a speedier rehabilitation and return to daily activities. According to Dr. Gerber, the average length of stay of patients treated by the institute is less than 3 days, which is well below the national average.

The Joint Replacement Institute combines image-guided medical technology with minimally invasive knee replacement instrumentation. Image-guided surgical technology is used to determine the precise alignment of the replacement parts; improves the surgeon’s view of and feel for the surgical field and reduces the size of the incisions to perform a replacement.

Other procedures offered by the Institute’s physicians include reconstruction of foot and ankle injuries, pediatric orthopedics, hand and upper extremities, and meniscus cartilage transplantation and Carticel Therapy to correct recurring knee cartilage injuries.
For more information about the Long Island Joint Replacement Institute or to schedule a consultation, call 1-877-SouthNassau.  www.southnassau.org.

"The results also confirm clinical ion level measurements that steep cup angles can substantially increases wear"

Presented at the 2nd Annual Total Hip Resurfacing Arthroplasty Course in LA Oct. 2008

By: John Fisher
Co-Authors: Ian Leslie, Sophie Williams, Eileen Ingham, Graham Isaac
Institute of Medical and Biological Engineering
University of Leeds

Background: There are considerable variations in metal ion levels and metallic wear rates in patients with metal on metal resurfacing. In this in vitro study the effect of design variables of head diameter and bearing clearance and patient variables of cup and head position on metal ion levels and wear rates are were investigated. Methods: Hip joint simulator studies were carried out on size 39mm and size 55mm metal on metal resurfacing with the same design. Size 55mm diameter bearings with 110 micrometer diametrical clearance were compared to size 54mm diameter with larger >250 micrometer diametrical clearance. The wear rates of size 39mm bearings with a standard cup position of 45 degrees, were compared to a steep cup position of 60 degrees and to a steep cup position combined with micro separation associated with head offset deficiency.

Results: Initial bedding in wear rates and ion levels were higher with size 39mm bearings compared to size 55mm, but in long term after 15 million cycles there was no difference in the steady state wear rates. Bearings with the larger diametrical clearance had higher initial wear and steady state wear rates at five million cycles. Cup position and head position resulted in much greater increases in wear. For the 39 mm bearings, a 60 degree cup position resulted in a 9 fold increase in wear. A steep cup and microseparation resulted in a 17 fold increase in wear after two million cycles and a 39 fold increase in wear compared to the long term steady state wear rate.

Conclusions: The study confirmed clinical ion level studies of increased wear with larger clearance bearings. The results also confirm clinical ion level measurements that steep cup angles can substantially increases wear. The study also indicates that offset deficiency and microseparation may be responsible for extremely high wear rates and ion levels found in some retrievals and some patients. Further work is needed to investigate effect of different head sizes with steep cups and microseparation and the effect of version.

"The results also confirm clinical ion level measurements that steep cup angles can substantially increases wear"

Presented at the 2nd Annual Total Hip Resurfacing Arthroplasty Course in LA Oct. 2008

By: John Fisher
Co-Authors: Ian Leslie, Sophie Williams, Eileen Ingham, Graham Isaac
Institute of Medical and Biological Engineering
University of Leeds

Background: There are considerable variations in metal ion levels and metallic wear rates in patients with metal on metal resurfacing. In this in vitro study the effect of design variables of head diameter and bearing clearance and patient variables of cup and head position on metal ion levels and wear rates are were investigated. Methods: Hip joint simulator studies were carried out on size 39mm and size 55mm metal on metal resurfacing with the same design. Size 55mm diameter bearings with 110 micrometer diametrical clearance were compared to size 54mm diameter with larger >250 micrometer diametrical clearance. The wear rates of size 39mm bearings with a standard cup position of 45 degrees, were compared to a steep cup position of 60 degrees and to a steep cup position combined with micro separation associated with head offset deficiency.

Results: Initial bedding in wear rates and ion levels were higher with size 39mm bearings compared to size 55mm, but in long term after 15 million cycles there was no difference in the steady state wear rates. Bearings with the larger diametrical clearance had higher initial wear and steady state wear rates at five million cycles. Cup position and head position resulted in much greater increases in wear. For the 39 mm bearings, a 60 degree cup position resulted in a 9 fold increase in wear. A steep cup and microseparation resulted in a 17 fold increase in wear after two million cycles and a 39 fold increase in wear compared to the long term steady state wear rate.

Conclusions: The study confirmed clinical ion level studies of increased wear with larger clearance bearings. The results also confirm clinical ion level measurements that steep cup angles can substantially increases wear. The study also indicates that offset deficiency and microseparation may be responsible for extremely high wear rates and ion levels found in some retrievals and some patients. Further work is needed to investigate effect of different head sizes with steep cups and microseparation and the effect of version.

Outcome of hip resurfacing may be dependent on experience

Link http://www.orthosupersite.com/view.asp?rID=37423

By Gina Brockenbrough
February 27, 2009

LAS VEGAS — A new study links outcomes of hip resurfacing to the hospital volume of resurfacing cases and, thereby, the surgeon’s experience.

To evaluate the impact of operative volume on hip resurfacing outcomes, Andrew J. Shimmin, MBBS, FAOrthA, and colleagues used the Australian Joint Registry to identify nearly 9,000 hip resurfacings performed at 196 hospitals between September 1999 and December 2006...

..They found that 74% of hospitals performed fewer than 30 procedures during the 7-year study period, while 64% of hip resurfacings were performed at 16 "high-volume" hospitals, or those that performed more than 100 cases. Overall, the researchers found that 3.1% of resurfacings were revised...

...They then compared the cumulative rate of revision at 4 years among the hospital groups. At 4 years, the investigators discovered a 6% revision rate for centers performing fewer than 25 cases, a 5.6% rate for those performing 25-49 cases, a 4.7% rate for hospitals doing 50-99 cases, and a 2.7% revision rate for those performing more than 100 cases.

After adjusting for patient age and gender, the investigators discovered that the risk for revision was 66% greater in hospitals performing the least amount of cases.

"In this study, hospital volume is primarily a reflection of the operative experience of the individual surgeons," Shimmin said at the American Academy of Orthopaedic Surgeons 76th Annual Meeting, here.

"The outcome of hip resurfacing is strongly dependent on the experience of the surgeon and hospital performing the procedure. Even when adjusted for patients’ age and sex, the risk of revision at low-volume centers was 66% greater than at a higher volume center. This supports the need for increased training of surgeons before undertaking hip resurfacing," he said.

Reference:

Shimmin AJ. The effect of operative volume on the outcome of hip resurfacing. Paper #316. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-28, 2009. Las Vegas.

Computer-Assisted Vs Conventional Mechanical Jig Technique in Hip Resurfacing Arthroplasty

Link  http://www.arthroplastyjournal.org/article/PIIS0883540307007292/abstract?rss=yes

Volume 24, Issue 3, Pages 341-350 (April 2009)

Jose Rafael E. Resubal, MD, FPOA, David A.F. Morgan, B.Sc(Med), FRACS, FAOA

Received 16 June 2007; accepted 17 December 2007. published online 15 February 2008.

Abstract
To compare the effectiveness of computer-assisted surgery (CAS) and mechanical jig technique in hip resurfacing arthroplasty, we reviewed 176 hip resurfacing arthroplasty performed in 158 patients. The initial 131 hips were resurfaced using the conventional mechanical jig technique, and the remaining 45 hips with the CAS technique. The demographic data of the patients were similar for both techniques. Follow-up radiographs taken 2 months after the surgery showed patients in the CAS technique having a significantly better alignment of the femoral component on the frontal and sagittal planes. There was no difference in the risk of implant notching on the femoral neck for both techniques. The implant sizes were similar for both techniques; thus, the amount of bone stock preserved was not technique specific.

Reprint requests: Jose Rafael E. Resubal, MD, FPOA, Suite 1, Level 8, Arnold Janssen Centre, Brisbane Private Hospital, 259 Wickham Terrace, Brisbane, Queensland 4000, Australia.