Femoral neck fracture after Birmingham Hip Resurfacing Arthroplasty: prevalence, time to fracture, and outcome after revision

Towards the First Generation of Biomimetic Fixation for Resurfacing Arthroplasty Endoprostheses

This paper presents advances in designs of resurfacing arthroplasty endoprostheses that occurred through their historical generations. The critical characteristics of contemporary generation hip resurfacing arthroplasty endoprostheses are given and the failures resulting from the specific generation cemented and short stem fixation of the femoral component are reviewed. On the background of these failures, the critical need arises for an alternative approach to the fixation of components of resurfacing arthroplasty leading towards the first generation of biomimetic fixation for resurfacing arthroplasty endoprostheses. The state of the art of the completed bioengineering research on the first biomimetic fixation for resurfacing arthroplasty endoprostheses is presented. This new design type of completely cementless and stemless resurfacing arthroplasty endoprostheses of the hip joint (and other joints), where endoprosthesis components are embedded in the surrounding bone via the prototype biomimetic multi-spiked connecting scaffold (MSC-Scaffold), initiates the first at all generations of biomimetic endoprostheses of diarthrodial joints.

Hip Resurfacing vs Total Hip Arthroplasty in Patients Younger than 35 Years: A Comparison of Revision Rates and Patient-Reported Outcomes

Background

Hip resurfacing arthroplasty (HRA) and total hip arthroplasty (THA) are two treatment options for end-stage degenerative hip conditions. The objective of this single-center retrospective cohort study was to compare implant survival and patient-reported outcomes (PROs) in young patients (≤35 years) who underwent HRA or THA.

Methods

All patients aged 35 years or younger who underwent HRA or THA with a single high-volume arthroplasty surgeon between 2004 and 2015 were reviewed. The sample included 33 THAs (26 patients) and 76 HRAs (65 patients). Five-year implant survival and minimum 2-year PROs were compared between patient cohorts.

Results

Three patients in the THA group (9%) were revised within 5 years for instability (n = 1), squeaking (n = 1), or squeaking with a ceramic liner fracture (n = 1). No patients who underwent HRA were revised. The University of California, Los Angeles, activity score, modified Harris Hip score, and Hip Dysfunction and Osteoarthritis Outcome Scores for Joint Replacement increased by 74%, 64%, and 49%, respectively, among all patients. Compared to the HRA cohort, patients who underwent THA had lower preoperative and postoperative University of California, Los Angeles, activity, modified Harris Hip score, and Hip Dysfunction and Osteoarthritis Outcome Scores for Joint Replacement scores, yet there were no differences in the absolute improvements in any of the three measures between the two groups.

Conclusions

Excellent functional outcomes were seen in young patients undergoing either HRA or THA. Although young patients undergoing THA started at lower preoperative baseline and postoperative PROs than patients undergoing HRA, both groups improved by an equal amount after surgery, suggesting that both HRA and THA afford a similar degree of potential improvement in a young population.

The Effect of Travel Distance on Outcomes for Hip Resurfacing Arthroplasty at a High-Volume Center

Background

Patients are increasingly traveling greater distances to receive care at high-volume centers. The effect of travel distance on patient-reported outcomes after hip resurfacing arthroplasty has not been described.

Methods

Patients undergoing HRA by a single surgeon from January 2007 to April 2018 with minimum 2-year follow-up were reviewed retrospectively. Five hundred ninety-nine patients were identified and divided into 2 cohorts: home-to-hospital distance >100 miles and ≤100 miles from our institution. Preoperative and 2-year postoperative patient-reported outcome measures (PROMs) were assessed, including the modified Harris Hip Score and Hip disability and Osteoarthritis Outcome Score. The minimal clinically important difference (MCID) for each PROM was calculated using the distribution-based method. Chi-square tests were used for univariate comparison. Poisson regressions controlling for demographic variables were performed to determine the effect of travel distance on whether patients achieved the MCID. Multivariate linear regressions were used to determine association between distance and improvement in PROMs.

Results

A total of 599 patients met criteria for inclusion. There were 113 (18.9%) with a home-to-hospital distance >100 miles and 486 (81.1%) with distance ≤100 miles. Age was the only demographic factor different between these groups (mean: 1.1-year difference, P < .001). There were no significant differences in reaching the MCID on any PROM between these groups. Multivariate linear regressions revealed no associations between travel distance and improvement in PROMs.

Conclusions

Travel distance to a high-volume center did not affect 2-year patient-reported outcomes or rate of achieving the MCID in patients undergoing hip resurfacing arthroplasty.

BIOMECHANICAL STUDY ON MECHANISMS OF FEMORAL NECK FRACTURE AFTER HIP RESURFACING ARTHROPLASTY

Hip resurfacing arthroplasty (HRA) is a long-established procedure. It is a minimally invasive surgery where the surgical wound is relatively small to facilitate a shorter recovery period. HRA remained a popular option among the patients allowing better range of motion of the joint compared to that of total hip arthroplasty (THA). Although HRA is associated with the above advantages, complications involving femoral neck fractures after surgery still occur. Therefore, the present study attempts to assess the impact of stress under various alignment conditions and different scenarios in surgical errors upon the femoral neck in hip resurfacing prostheses (HRP) that may be encountered during the procedure using finite element analysis (FEA) technique. The results showed that anteversion implantation errors on femoral components should be avoided, and that the main reason that causes femoral neck fracture is related to the stress shielding effect generated internally in the femoral neck. Methods to prevent the incidence of such events are a major obstacle to be solved in the future.

10-year results of the Birmingham Hip Resurfacing: a non-designer case series

INTRODUCTION

Recent controversies surrounding metal-on-metal (MoM) hip resurfacing has led to a substantial decline in its use. Despite this, there is good evidence to support the use of specific implants in select patients.

PATIENTS AND METHODS

A retrospective analysis of Birmingham Hip Resurfacing (BHR) patients with a minimum of 10 years follow-up was performed. Functional scoring was performed with the Oxford Hip Score (OHS) and failure was defined as revision for any cause. 111 patients underwent 121 BHR procedures. All patients had a minimum follow-up of 10 years. 70 patients (63%) were male. Mean patient age at surgery was 52.5 years (male 53.9 years, female 48.8 years).

RESULTS

Overall survival at 10 years was 91% (97% male, 80% female). There was a statistically significant improvement in OHS postoperatively which remains at 10-year follow-up (p = <0.05). There was no significant difference in scores between the male and female groups. Revisions were most often in patients with smaller component sizes but this was not found to be statistically significant.

CONCLUSIONS

Our results reflect that of the wider literature in that good outcomes can be obtained with this implant in a select group of patients and results are comparable to that of conventional hip arthroplasty in patients of a similar age.

Poor Survivorship and Frequent Complications at a Median of 10 Years After Metal-on-Metal Hip Resurfacing Revision

BACKGROUND

High short-term failure rates have been reported for several metal-on-metal hip resurfacing (MoMHR) designs. Early observations suggested that MoMHRs revised to total hip arthroplasties (THAs) for pseudotumor had more major complications and inferior patient-reported outcomes compared with other revision indications. However, little is known about implant survivorship and patient-reported outcomes at more than 5 years after MoMHR revision.

QUESTIONS/PURPOSES

(1) What are the implant survivorship, proportion of complications and abnormal radiological findings, and patient-reported outcomes at a median of 10 years after MoMHR revision surgery? (2) Are survivorship, complications, and patient-reported outcomes influenced by revision indication? (3) Do any other factors predict survivorship, complications, and patient-reported outcomes?

METHODS

Between 1999 and 2008, 53 MoMHR revision procedures in 51 patients (mean age, 55 years; 62% female) were performed at one center and were all included in this retrospective study. Two patients (4%) were lost to followup and two patients (4%) died before a minimum followup of 7 years (median, 10.3 years; range 7-15 years). Revision indications included pseudotumor (n = 16), femoral neck fracture (n = 21), and other causes (n = 16). In most cases (62%, n = 33) both components were revised to a non-MoM bearing THA with the remainder (38%, n = 20: fracture, loosening, or head collapse) undergoing femoral-only revision to a large-diameter MoM THA. Postrevision complications, rerevision, Oxford Hip Score (OHS), and UCLA score were determined using both a longitudinally maintained institutional database and postal questionnaire. Implant survivorship was assessed using the Kaplan-Meier method (endpoint was rerevision surgery). Radiographs at latest followup were systematically assessed for any signs of failure (loosening, migration, osteolysis) by one observer blinded to all clinical information and not involved in the revision procedures.

RESULTS

Overall, 45% (24 of 53) experienced complications and 38% (20 of 53) underwent rerevision. Ten-year survival free from rerevision for revised MoMHRs was 63% (95% confidence interval [CI], 48%-74%). Revision indications were not associated with differences in the frequency of complications or repeat revisions. With the numbers available, 10-year survival free from rerevision for pseudotumor revisions (56%; 95% CI, 30%-76%) was not different from the fracture (68%; 95% CI, 42%-85%; p = 0.359) and other groups (63%; 95% CI, 35%-81%; p = 0.478). Pseudotumor revisions had inferior OHSs (median, 21; range, 2-46; p = 0.007) and UCLA scores (median, 2; range, 2-7; p = 0.0184) compared with fracture and other revisions. Ten-year survival free from rerevision after femoral-only revision using another large-diameter MoM bearing was lower (p = 0.0498) compared with all component revisions using non-MoM bearings. After controlling for potential confounding variables such as age, sex, and revision indication, we found femoral-only revision as the only factor predicting rerevision (hazard ratio, 5.7; 95% CI, 1.1-29; p = 0.040).

CONCLUSIONS

Poor implant survivorship and frequent complications were observed at a median of 10 years after MoMHR revision. However, patients undergoing femoral-only revisions with large-diameter MoM bearings had the worst survivorship, whereas patients revised for pseudotumor had the most inferior patient-reported outcomes. Our findings suggest these two patient subgroups require regular surveillance after MoMHR revision.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses-Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation

We present here—designed, manufactured, and tested by our research team—the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold) interfacing the components of resurfacing arthroplasty (RA) endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like) coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine) and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP) activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the enhancement of the osteoinduction/osteointegration potential by the Ca-P surface modification of the Ti-alloy MSC-Scaffold prototype. Planned further research on the prototype of this biomimetic MSC-Scaffold for a new generation of RA endoprostheses is also given.

Current indications for hip resurfacing arthroplasty in 2016

Hip resurfacing arthroplasty (HRA) is an alternative to conventional, stemmed total hip arthroplasty (THA). The best reported results are young, active patients with good bone stock and a diagnosis of osteoarthritis. Since the 1990s, metal-on-metal (MoM) HRA has achieved excellent outcomes when used in the appropriate patient population. Concerns regarding the metal-on-metal bearing surface including adverse local tissue reaction (ALTR) to metal debris have recently lead to a decline in the use of this construct. The current paper aims to provide an updated review on HRA, including a critical review of the most recent literature on HRA.

Revision of metal-on-metal hip replacements and resurfacings for adverse reaction to metal debris: a systematic review of outcomes

PURPOSE

This systematic review assessed evidence on outcomes following revision of MoM hip resurfacings (HRs) and total hip replacements (THRs) for adverse reaction to metal debris (ARMD).

METHODS

Four electronic databases were searched between January 2009 and July 2013 to identify studies reporting clinical outcomes following revision of MoM HRs and THRs for ARMD. Only studies reporting cohorts with more than 10 metal-on-metal (MoM) hips revised for ARMD were included. Outcomes of interest following ARMD revision were: (1) complication rates; (2) re-revision rates; (3) surgical intervention other than re-revision; (4) functional outcome.

RESULTS

Of 148 unique studies identified, six studies were eligible for inclusion containing 216 MoM hips (197 HRs and 19 THRs) revised for ARMD. Mean follow-up time from ARMD revision ranged between 21-61 months. Complication rates were 4%-50% for HR and 68% for THR. Re-revision rates were 3%-38% for HR and 21% for THR. Dislocation (n = 14), ARMD recurrence (n = 11), and acetabular loosening (n = 9) were the three commonest complications and indications for re-revision. All six studies reported between one and three cases of ARMD recurrence during follow-up. One study specifically reported on performing procedures other than re-revision with 26% requiring closed reductions for dislocated THRs. Functional outcomes following ARMD revision were good or satisfactory in all but two studies.

CONCLUSIONS

Limited evidence exists regarding outcomes following revision of MoM hips for ARMD, especially for THRs. This should be addressed in future studies and may be important when counselling asymptomatic individuals in whom revision is considered for raised blood metal ions.

Survivorship and clinical outcome of Birmingham hip resurfacing: a minimum ten years' follow-up

INTRODUCTION

Resurfacing as a percentage of total hip arthroplasty rose from 5.6 % in 2001 to 8.9 % in 2005 in Australia. During the same period the resurfacing to conventional prosthesis rose from 19.6 % to 29 % in the younger age group (less than 55 years). Long term (more than ten years) functional results of BHR are sparingly documented. Among the literatures available, the patient selection criteria vary from osteoarthritis, avascular necrosis, and dysplastic hip to slipped capital femoral epiphysis. The objective of the current study is to evaluate long term survivorship and functional outcome of Birmingham hip resurfacing surgery in osteoarthritic hip patients performed by a single surgeon.

PATIENTS AND METHODS

In this retrospective clinical study, all patients who underwent hip resurfacing for osteoarthritis of hip between 1999 and 2004 are included. All surgeries were performed by single surgeon (SJM) and in all patients Smith & Nephew system (Midland Medical Technologies, Birmingham, United Kingdom)) was used. Revision surgery is considered the end point of survivorship. Means, standard deviations, and confidence interval were calculated for all continuous measures. Survival analysis was performed with the Kaplan-Meier method and 95 % confidence intervals were calculated.

RESULT

The result is based on 222 patients (244 hips). This included 153 males and 69 females. Our mean follow up was 12.05 years and overall survival was 93.7 %. In terms of gender, survival in males was 95.43 % while in females it was 89.86 %. Failure was seen in 14 patients (16 hips), which included seven female (10.14 %) and seven male (4.57 %) patients. Failure of femoral components due to aseptic loosening and varus collapse was seen in eight patients after a mean 9.6 years. Metal allergy was seen in three patients (five hips), all of them were female of which two had bilateral resurfacing. Other complications included femoral neck stress fractures in two patients and acetabular component loosening in one patient. We observed that the failure rate is higher if the BHR femoral component size is 46 or less (ten out of 16 hips revised).

CONCLUSION

If patient selection is judiciously done and surgical technique is meticulously followed, hip resurfacing offers acceptable survivorship, satisfactory range of motion and enables patients to resume high demand activities including sports. Future improvements in the bearing surfaces, and possibly in the design, might alleviate concerns posed by high serum metal level and provide options that continue to benefit younger patients in future.

Predictors of time to revision and clinical outcomes following revision of metal-on-metal hip replacements for adverse reaction to metal debris

We undertook a retrospective cohort study to determine clinical outcomes following the revision of metal-on-metal (MoM) hip replacements for adverse reaction to metal debris (ARMD), and to identify predictors of time to revision and outcomes following revision. Between 1998 and 2012 a total of 64 MoM hips (mean age at revision of 57.8 years; 46 (72%) female; 46 (72%) hip resurfacings and 18 (28%) total hip replacements) were revised for ARMD at one specialist centre. At a mean follow-up of 4.5 years (1.0 to 14.6) from revision for ARMD there were 13 hips (20.3%) with post-operative complications and eight (12.5%) requiring re-revision. The Kaplan-Meier five-year survival rate for ARMD revision was 87.9% (95% confidence interval 78.9 to 98.0; 19 hips at risk). Excluding re-revisions, the median absolute Oxford hip score (OHS) following ARMD revision using the percentage method (0% best outcome and 100% worst outcome) was 18.8% (interquartile range (IQR) 7.8% to 48.3%), which is equivalent to 39/48 (IQR 24.8/48 to 44.3/48) when using the modified OHS. Histopathological response did not affect time to revision for ARMD (p = 0.334) or the subsequent risk of re-revision (p = 0.879). Similarly, the presence or absence of a contralateral MoM hip bearing did not affect time to revision for ARMD (p = 0.066) or the subsequent risk of re-revision (p = 0.178). Patients revised to MoM bearings had higher rates of re-revision (five of 16 MoM hips re-revised; p = 0.046), but those not requiring re-revision had good functional results (median absolute OHS 14.6% or 41.0/48). Short-term morbidity following revision for ARMD was comparable with previous reports. Caution should be exercised when choosing bearing surfaces for ARMD revisions.