Hip Resurfacing

Hip resurfacing is a recent technology which is being used in young patients who needs a hip replacement. In a conventional total hip replacement the ball of the hip joint is cut along with the neck of the femur and is replaced by a metal implant. In hip resurfacing the ball of the hip joint is preserved to a large extent and is only reshaped to fit a metal cap. The femoral neck is not cut.

The main potential advantage in hip resurfacing is that there is preservation of bone stock for further revision surgery. Another potential advantage is that once the soft tissues have healed there is very less chance of hip dislocation because of the large size of the ball (compared to conventional total hip replacement) and they can lead an active lifestyle with very little restriction.

---

---

However, hip resurfacing has its own special issues compared to a conventional total hip replacements including that it is technically more difficult procedure, higher early failure rate and increased metal ion levels in the blood. Special complications include fracture of the femoral neck, femoral neck thinning, avascular necrosis of the resurfaced femoral head (due to decreased blood supply), increased risk of heterotopic ossification (new bone formation in the muscle) and metal ion related problems.

Computer guided hip resurfacing: Studies have shown that correct placement of the femoral component is important decrease the risk of femoral neck fractures following hip resurfacing.  The accuracy of placement can be improved by using computer guidance.  Mr. Ganapathi’s has published a study comparing the difference between the preoperative planned position and postoperative position. The study showed that computer navigation had a significantly lower error compared to manual placement. Mr. Ganapathi  uses computer navigation routinely when doing hip resurfacing.

In addition, options are now available to use the large metal on metal bearings in a conventional type total hip replacements (which will provide the same stability but with lesser risk of early complications like femoral neck fractures (large head diameter total hip replacements).

---

Large Diameter Head & Hip Replacement

---

Metal ion issues: More recently a study from Oxford1 has reported cases of excessive fluid collection around the resurfaced hip with damage to the surrounding tissues in some patients (so called “pseudotumours”. The reasons are not entirely clear at this stage and may be related to allergic reaction or excessive metal ion/particles. Many factors have been associated with this including females, smaller components and placement of the components as well as the implant design and materials.

However, many centres have reported excellent results in men with larger components and there is also conflicting evidence regarding the influence of the gender. For example in the Australian national joint registry, the is higher failure in females. There are other studies  suggesting the component size is more important than the gender. 3,6

---

Australian Joint Registry report (2009) showing higher failure rate in females
but good result in men

---

Very recently MHRA issued an alert on metal on metal bearings with advice about regularly following up patients and monitoring the outcome.

In light of the above factors, although hip resurfacing was used very frequently in young adults few years ago, more recently the patient selection has become more important. It is also important to understand that all type of hip replacements have some advantages and disadvantages and selecting the type of hip replacements essentially depends on the balance between potential advantages and disadvantages. It is important that a decision about hip resurfacing is made on an individual basis after discussing the benefits and risks with the patient.

To maintain the advantage of the large diameter bearing (better range of movement and better stability) while minimising the potential adverse effects of metal ions, implant companies are adopting various strategies. They include surface modification of the metal surface (which has been shown to have low metal ion levels in recent studies) and using ceramics as large diameter bearing option. Mr.Ganapathi would be happy to discuss with you regarding these newer developments and would be able to offer those options if appropriate.

Scientific Literature

The following are some relevant selected scientific references:

1. Risk factors for inflammatory pseudotumour formation following hip resurfacing.

J Bone Joint Surg Br. 2009 Dec;91(12):1566-74.

Glyn-Jones S, Pandit H, Kwon YM, Doll H, Gill HS, Murray DW.

Department of Orthopaedics, Nuffield Orthopaedic Centre, University of Oxford, Oxford, England.

Abstract: Metal-on-metal hip resurfacing is commonly performed for osteoarthritis in young active patients. We have observed cystic or solid masses, which we have called inflammatory pseudotumours, arising around these devices. They may cause soft-tissue destruction with severe symptoms and a poor outcome after revision surgery. The aim of this study was to determine the incidence of and risk factors for pseudotumours that are serious enough to require revision surgery. Since 1999, 1419 metal-on-metal hip resurfacings have been implanted by our group in 1224 patients; 1.8% of the patients had a revision for pseudotumour. In this series the Kaplan-Meier cumulative revision rate for pseudotumour increased progressively with time. At eight years, in all patients, it was 4% (95% confidence interval (CI) 2.2 to 5.8). Factors significantly associated with an increase in revision rate were female gender (p < 0.001), age under 40 (p = 0.003), small components (p = 0.003), and dysplasia (p = 0.019), whereas implant type was not (p = 0.156). These factors were inter-related, however, and on fitting a Cox proportional hazard model only gender (p = 0.002) and age (p = 0.024) had a significant independent influence on revision rate; size nearly reached significance (p = 0.08). Subdividing the cohort according to significant factors, we found that the revision rate for pseudotumours in men was 0.5% (95% CI 0 to 1.1) at eight years whereas in women over 40 years old it was 6% (95% CI 2.3 to 10.1) at eight years and in women under 40 years it was 13.1% at six years (95% CI 0 to 27) (p < 0.001). We recommend that resurfacings are undertaken with caution in women, particularly those under 40 years of age but they remain a good option in young men. Further work is required to understand the aetiology of pseudotumours so that this complication can be avoided.

2. Canadian academic experience with metal-on-metal hip resurfacing.

Bull NYU Hosp Jt Dis. 2009;67(2):128-31.

O’Neill M, Beaule PE, Bin Nasser A, Garbuz D, Lavigne M, Duncan C, Kim PR, Schemitsch E.

Abstract: The current depth and breadth of experience in hip resurfacing in Canadian academic centers is not well known. This study endeavors to increase awareness of the prevalence of programs and current experience in a select number of representative teaching centers by examining the learning curve of high-volume surgeons. A questionnaire was sent to all academic centers in Canada to identify the volume of hip resurfacing, surgical approach, and type of prosthesis. In addition, five surgeons, not fellowship-trained in hip resurfacing, were selected for a detailed review of their first 50 cases, including survey of patient demographics, surgical approach, radiographic evaluation, complications, and revision. Eleven of 14 academic centers are currently performing hip resurfacing. All of these centers had performed more than 50 cases, with 10 of 11 of them having more than one surgeon performing the procedure. The posterior approach was found to be the most commonly utilized in surgeries. The overall revision rate was 3.2% at a mean time of 2 years, with femoral neck fracture (1.6%) being the most common cause for failure. The failure rate was comparable to other centers of expertise and lower than previously published multicenter trials. All surgeons reviewed were in specialized arthroplasty practices, which may contribute to the relatively low complication rates reported.

3. Sex as a Patient Selection Criterion for Metal-on-Metal Hip Resurfacing Arthroplasty.

J Arthroplasty. 2010 May 7. [Epub ahead of print]

Amstutz HC, Wisk LE, Le Duff MJ.

Joint Replacement Institute at St. Vincent Medical Center, Los Angeles, California.

Abstract: Short-term to midterm results of hip resurfacing arthroplasty suggest various contraindications, in particular the female sex. This study evaluates survivorship and clinical outcomes of a large patient cohort to determine whether sex itself has a detrimental effect on the results of hip resurfacing. We compared the clinical and survivorship results of men and women from a series of 1107 resurfaced hips in 923 patients (681 males and 242 females). Women saw greater positive changes in walking, function, and the mental component of the Short Form-12. There was no difference in complication rates between men and women. Although the revision rate was higher in the women’s group, the effect of sex disappeared when adjusted for component size and surgical technique. These data suggest that there is no appreciable effect of sex on implant survivorship and that women may be excellent candidates for resurfacing with proper surgical technique. This is a level III, retrospective comparative study.

4. Eleven years of experience with metal-on-metal hybrid hip resurfacing: a review of 1000 conserve plus.

J Arthroplasty. 2008 Sep;23(6 Suppl 1):36-43.

Amstutz HC, Le Duff MJ.

Joint Replacement Institute at St Vincent Medical Center, Los Angeles, California 90057, USA.

Abstract: Hip resurfacing is currently the fastest growing hip procedure worldwide. We reviewed 1000 hips in 838 patients who received a Conserve Plus (Wright Medical Technology, Inc., Arlington, Tenn) resurfacing at a single institution. The mean age of the patients was 50.0 years with 74.7% male. The hips were resurfaced irrespective of femoral defect size or etiology. The mean follow-up was 5.6 years (range, 1.1-11.0 years). All clinical scores improved significantly (P < .05). There was no acetabular component loosening. Ten were converted to total hip arthroplasty for femoral neck fracture, 20 for femoral loosening, 2 for sepsis, and 1 for recurrent subluxations. The 5-year survivorship was 95.2% with no failures in hips implanted since 2002. Short-term failures can be prevented. First-generation surgical technique and a low body mass index were the most important risk factors for the procedure. Improvements in bone preparation significantly increased prosthetic survival in hips with risk factors for failure.

5. Birmingham hip resurfacing: Five to eight year results.

Int Orthop. 2010 Jun 19. [Epub ahead of print]

Reito A, Puolakka T, Pajamäki J.

Abstract: Hip resurfacings have been performed in our hospital since May 2001, and in this retrospective study, we analysed the clinical and radiological outcome of the first 144 prostheses (126 patients). One hundred and seven patients have visited our hospital for regular follow-up examination; 16 are not in regular follow-up and were sent a Harris Hip Score (HHS) questionnaire. Three patients live abroad. Mean follow-up was six years. One patient was lost during follow-up. Four prostheses have been revised. The six year cumulative survival rate was 96.7%. Two female patients required revision for aseptic lymphocyte-dominated vascular associated lesions (ALVAL) and two male patients due for femoral head necrosis. Both reoperated female patients had cup inclination >60 degrees . Mean HHS in the follow-up was 95.3, and mean patient satisfaction 2.53 on a scale 0-3. Neck thinning >10% was seen in seven hips and impingement in 12 hips.

6. The influence of head size and sex on the outcome of Birmingham hip resurfacing.

J Bone Joint Surg Am. 2010 Jan;92(1):105-12.

McBryde CW, Theivendran K, Thomas AM, Treacy RB, Pynsent PB.

Abstract: BACKGROUND: Hip resurfacing has gained popularity for the treatment of young and 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 December 2008 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 to 10.9 years). The five-year cumulative survival rate for the 655 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.

7. Birmingham hip arthroplasty: five to eight years of prospective multicenter results.

J Arthroplasty. 2009 Oct;24(7):1044-50.

Khan M, Kuiper JH, Edwards D, Robinson E, Richardson JB.

Abstract: Pioneering centers report excellent results of Birmingham resurfacing arthroplasty. Results from pioneering surgeons are not usually reproduced when implants are used at other centers. We therefore studied patients’ satisfaction, postoperative hip function, and survival of Birmingham hip resurfacing in a group, operated by nonpioneering surgeons. The median first year postoperative Harris hip score was 95, and this score was sustained for a period of 8 years. The cumulative survival at 8 years was 95.7%. Most of the failures were in the first year; commonest cause of the first year failures was fracture of femoral neck. This complication is not seen as a substantial problem in the pioneering surgeons’ studies. We therefore conclude that this complication is not related to the prosthesis and that its occurrence can be reduced.

8. Birmingham hip resurfacing arthroplasty. A minimum follow-up of five years.

J Bone Joint Surg Br. 2005 Feb;87(2):167-70.

Treacy RB, McBryde CW, Pynsent PB.

Royal Orthopaedic Hospital, Birmingham, England.

Abstract: We report the survival at five years of 144 consecutive metal-on-metal resurfacings of the hip implanted between August 1997 and May 1998. Failure was defined as revision of either the acetabular or femoral component for any reason during the study period. The survival at the end of five years was 98% overall and 99% for aseptic revisions only. The mean age of the patients at implantation was 52.1 years. Three femoral components failed during the first two years, two were infected and one fractured. A single stage revision was carried out in each case. No other revisions were performed or are impending. No patients were lost to follow-up. Four died from unrelated causes during the study period. This study confirms that hip resurfacing using a metal-on-metal bearing of known provenance can provide a solution in the medium term for the younger more active adult who requires surgical intervention for hip disease.

9. What is the Midterm Survivorship and Function After Hip Resurfacing?

Clin Orthop Relat Res. 2010 Jun 24. [Epub ahead of print]

Rahman L, Muirhead-Allwood SK, Alkinj M.

The London Hip Unit, 30 Devonshire Street, London, W1G 6PU, UK

Abstract: BACKGROUND: Hip resurfacing arthroplasty is a common procedure that improves functional scores and has a reported survivorship between 95% and 98% at 5 years. However, most studies are reported from the pioneering rather than independent centers or have relatively small patient numbers or less than five years followup. Various factors have been implicated in early failure. QUESTIONS/PURPOSES: Our purposes were to determine: (1) the midterm survival of the BHR; (2) the function in patients treated with hip resurfacing; and (3) whether age, gender, BMI, or size of components related to failure. METHODS: We reviewed the first 302 patients (329 hips) on whom we performed resurfacing arthroplasty. We assessed the survivorship, change in functional hip scores (HHS, OHS, WOMAC, UCLA), and analyzed potential risk factors (age, gender, BMI, component size) for failure. The mean age at the time of surgery was 56.0 years (range, 28.2-75.5 years). The minimum followup was 5 years (mean, 6.6 years; range, 5-9.2 years). RESULTS: Kaplan-Meier analysis showed survival of 96.5% (95% CI, 94.7-98.4) at 9 years taking revision for any cause as the endpoint. All functional hip scores (HHS, OHS, WOMAC, UCLA) improved. Survivorship was higher in men compared with women. The component sizes and body mass index were smaller in the revised group compared with the nonrevised group. CONCLUSIONS: Medium-term survivorship and functional scores of hip resurfacing are comparable to those from the pioneering center. Hip resurfacing remains a good alternative to THA, particularly in the younger male population with relatively large femoral head sizes