Biomechanical reconstruction of the hip: a randomised study comparing total hip resurfacing and total hip arthroplasty

Conversion of hip resurfacing to total hip arthroplasty: is the outcome closer to primary or revision total hip arthroplasty?

BACKGROUND

Along with the advent of newer bearings, hip resurfacing (HR) is gaining renewed interest as a bone sparing alternative to conventional total hip arthroplasty (THA) in young patients. However, the outcome of conversion of failed HR to THA (HRc) remains sparsely described. This study aimed to compare the outcomes and complication rates of HRc to those of primary (pTHA) and revision THA (rTHA) to find out to which group HRc is most comparable.

HYPOTHESIS

The study hypothesis was that the outcomes and complications rates of HRc were closer to those of pTHA than rTHA.

MATERIALS AND METHODS

Between 2001 and 2011, a continuous series of 207 HR were prospectively included in our institutional registry and retrospectively analyzed. Out of them, 17 HR (8%) were converted to THA. Propensity scores were used to match patients in the HRc group to the pTHA and the rTHA groups using a greedy 1:3 matching procedure (51 pTHA and 51 rTHA). Clinical and radiographic outcomes, perioperative data and complications were analyzed and compared between the three groups.

RESULTS

No significant difference between HRc and pTHA was observed in terms of clinical and functional outcomes, duration of surgery, acetabular component diameter and length of hospital stay (p = 0.13 to 0.94). Perioperative blood loss was significantly lower for pTHA than for HRc (p = 0.01). HRc demonstrated significantly higher HHS and HOOS scores than for rTHA at one year (p = 0.03 and p < 0.01, respectively). Duration of surgery was significantly lower in HRc compared to rTHA (p = 0.02) while length of hospital stay was similar (p = 0.84). Complication rate was significantly higher in the rTHA group, compared to HRc and pTHA groups (37.3 vs. 29.4 vs. 11.8%, p = 0.01).

CONCLUSION

This study demonstrated that the clinical and functional outcomes of HRc were closer to those of pTHA than those of rTHA, though complication rate was higher than for pTHA.

LEVEL OF EVIDENCE

III; Retrospective comparative study.

15-year survivorship of a unique dual-modular femoral stem in primary hip arthroplasty

BACKGROUND

Hip offset, version, and length are interdependent femoral variables which determine stability and leg length. Balancing these competing variables remains a core challenge in hip arthroplasty. The potential benefits of modular femoral stems have been overshadowed by higher rates of failure. The objective of this study was to assess the survivorship of a unique dual-modular femoral stem at an average 15-year follow-up period.

METHODS

The records of all patients with osteoarthritis who underwent primary total hip arthroplasty with this device between 2004-2009 were reviewed. There were no exclusions for BMI or other factors. We examined the data with Kaplan-Meier survival analysis. The primary endpoint for survival was mechanical failure of the modular neck-body junction.

RESULTS

The survivorship of this device in 172 subjects was 100% with none experiencing mechanical failure of the modular junction at an average of 15 years. 60 patients died of causes unrelated to their THA and 9 patients were lost to follow-up. There were three early (≤ 12 months) dislocations (1.7%), and seven total dislocations (4.1%). 16 patients underwent reoperations during the follow-up period, none for any complication of the modular junction. Radiographic results showed well-fixed femoral stems in all cases. There were no leg length discrepancies of greater than 10 mm, and 85% were within 5 mm.

CONCLUSION

There were no mechanical failures of the modular junction in any of the subjects over the average 15-year period, demonstrating that this dual-modular design is not associated with increased failure rates. We achieved a 1.7% early dislocation rate and a 4.1% total dislocation rate without any clinically significant leg length discrepancies.

Comparison of iliopsoas tendonitis after hip resurfacing arthroplasty and total hip arthroplasty: A case-controlled investigation using a validated simulation

Iliopsoas tendonitis, typically caused by impingement with the acetabular cup, occurs in up to 18% of patients after total hip arthroplasty (THA) and up to 30% of patients after hip resurfacing arthroplasty (HRA). We have developed a simulation for detecting iliopsoas impingement and validated it in a previous study of THA patients. However, due to the difference in incidence between HRA and THA, this study had two aims. First, to validate the simulation in a cohort of HRA patients and, second, to comparethe results of the HRA and THA patients to understand any differences in their etiology. We conducted a retrospective search in an experienced surgeon's database for HRA patients with iliopsoas tendonitisand control patients without iliopsoas tendonitis, resulting in two cohorts of 12 patients. Using CT scans, 3D models of the each patient's prosthetic and bony anatomy were generated, landmarked, and simulated. Regarding validation of the simulation for HRA patients, impingement significantly predicted the probability of iliopsoas tendonitis in logistic regression models and the simulation had a sensitivity of 83%, specificity of 100%, and an AUC ROC curve of 0.95. Unexpectedly, the HRA cohort exhibited less impingement than the THA cohort. Our novel simulation has now been demonstrated to detect iliopsoas impingement and differentiate between the symptomatic and asymptomatic cohorts in investigations of THA and HRA patients. This tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis.

Long-Term Outcomes of Birmingham Hip Resurfacing Arthroplasty: A Systematic Review of Independent Series with At Least 10 Years of Follow-up

Background

Hip resurfacing arthroplasty (HRA) provides an attractive alternative to total hip arthroplasty (THA) for the management of osteoarthritis in younger, more active patients; however, concerns persist over complications specific to HRA. The aims of this systematic review were to assess the documented long-term survival rates of the metal-on-metal BIRMINGHAM HIP Resurfacing System at a follow-up of at least 10 years and to analyze the functional outcomes and cause of failures.

Methods

A systematic review was undertaken of all published cohort studies available in the MEDLINE, Cochrane, Embase, and PubMed research databases up to December 2021, as recommended by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data extraction was focused on survival rates, causes of failure, and functional outcomes. Survival estimates at 10 years were pooled in a meta-analysis, with each series weighted by its variance. Causes of failure were presented as a percentage of the pooled revisions.

Results

A total of 11 studies were identified, encompassing 3,129 cases. Across the 9 studies that had reported a mean follow-up, the mean follow-up was 11.7 years (range, 9.55 to 13.7 years). We found a pooled 10-year survival rate of 95.5% (95% confidence interval, 93.4% to 97.1%). There were 149 revisions among the studies (range, 4 to 38 revisions per study), a rate of 4.8% of the total procedures performed. The 2 main causes of revision were aseptic loosening (20.1% of revisions) and adverse reactions to metal debris (20.1%). There were no revisions for dislocation. Of the studies that reported preoperative functional scores, all reported significant improvement in mean scores postoperatively except for 1 study in which the mean Tegner activity score did not significantly improve.

Conclusions

When performed for appropriate indications, patients undergoing an HRA with use of the BIRMINGHAM HIP Resurfacing System can expect good implant survivorship at 10 years with acceptable functional results and low rates of dislocation and infection. This systematic review, however, confirms concerns regarding adverse reactions to metal debris as a leading cause of revision.

Level of Evidence

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Do hip resurfacing and short hip stem arthroplasties differ from conventional hip stem replacement regarding impingement-free range of motion?

Total hip joint replacement (THR) is clinically well-established. In this context, the resulting range of motion (ROM) is crucial for patient satisfaction when performing joint movements. However, the ROM for THR with different bone preserving strategies (short hip stem and hip resurfacing) raises the question of whether the ROM is comparable with conventional hip stems. Therefore, this computer-based study aimed to investigate the ROM and type of impingement for different implant systems. An established framework with computer-aided design 3D models based on magnetic resonance imaging data of 19 patients with hip osteoarthritis was used to analyse the ROM for three different implant systems (conventional hip stem vs. short hip stem vs. hip resurfacing) during typical joint movements. Our results revealed that all three designs led to mean maximum flexion higher than 110°. However, hip resurfacing showed less ROM (-5% against conventional and -6% against short hip stem). No significant differences were observed between the conventional and short hip stem during maximum flexion and internal rotation. Contrarily, a significant difference was detected between the conventional hip stem and hip resurfacing during internal rotation (p = 0.003). The ROM of the hip resurfacing was lower than the conventional and short hip stem during all three movements. Furthermore, hip resurfacing shifted the impingement type to implant-to-bone impingement compared with the other implant designs. The calculated ROMs of the implant systems achieved physiological levels during maximum flexion and internal rotation. However, bone impingement was more likely during internal rotation with increasing bone preservation. Despite the larger head diameter of hip resurfacing, the ROM examined was substantially lower than that of conventional and short hip stem.

Resurfacing Hip Arthroplasty Is a Safe and Effective Alternative to Total Hip Arthroplasty in Young Patients: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis of randomized controlled trials (RCTs) aimed at comparing resurfacing hip arthroplasty (RHA) and total hip arthroplasty (THA) in terms of rate of complications, revisions, functional outcomes, blood loss, operative time and metal ions levels. The search was conducted on three databases (PubMed, Cochrane and Web of Science) updated until 13 October 2022. The inclusion criteria were RCTs) written in the English language, with no time limitation, comparing RHA and THA. Among the retrieved 4748 articles, 18 RCTs were eligible for a total of 776 patients (mean age 53.1 ± 5.0). A meta-analysis was performed. RHA reported significantly lower blood loss compared to THA (p < 0.001) but with longer operative time (p < 0.001). No statistically significant difference was found between RHA and THA in terms of complications (12.08% and 16.24%, respectively) and revisions (6.32% and 6.14%, respectively). Both RHA and THA provide excellent clinical results in a population of young and active patients. Functional outcomes were not significantly different between the groups. Moreover, no significant difference in metal ion levels was found. These findings provide evidence concerning the safety and clinical effectiveness of RHA. Because of its bone-preserving properties, the lack of drawbacks and good outcomes, RHA appears to be a valid alternative to THA in young and active patients.

Hip resurfacing for small-sized osteonecrosis: 73 cases at a median 8years' follow-up

INTRODUCTION

Total hip resurfacing arthroplasty (THRA) is an alternative to conventional total hip replacement (THR) in young patients with osteonecrosis of the femoral head. Series have been small, without criteria regarding extent of necrosis, thus vitiating results. We therefore conducted a retrospective assessment of THRA for small necrosis, to determine (1) implant survival, (2) functional scores, and (3) systemic chromium, cobalt and titanium ion concentrations.

HYPOTHESIS

The study hypothesis was that the revision rate is low, meeting the National Institute for Health and Care Excellence (NICE) criterion of<0.5% revision per year.

MATERIAL AND METHOD

A single-center single-surgeon retrospective study included 62 patients, for 73 RTHAs, with a mean age of 45.6years (range: 23-68years) presenting Ficat stage 3 or 4 osteonecrosis of the femoral head with<330° total Kerboul angle (frontal+lateral angles) on simple preoperative X-ray. Study data comprised implant survival and preoperative and last follow-up functional scores (Postel-Merle-d'Aubigné, Oxford-12, Harris, and Devane) and titanium, chromium and cobalt blood concentrations. Necrosis size was assessed on preoperative Kerboul angle.

RESULTS

At a median 8years' follow-up (IQR: 5.9-9.3years), implant survival was 98.6% (95% CI: 97.22-99.98%). Only 1 implant was exchanged, for femoral loosening. Three other patients underwent revision surgery: 2 cases of lavage for infection, and 1 muscle hernia repair. Postel-Merle-d'Aubigné, Oxford-12 and Harris functional scores and Devane activity scores were significantly improved at follow-up, by a median +5 (IQR: 5 to 7), -26 (IQR: -29 to -23), +55 (IQR: 49 to 61) and +1 (IQR: 1 to 2), respectively (all p<0.001). Ion concentrations at last follow-up for titanium, chromium and cobalt were respectively 4.0μg/L (range: 3.6-4.1), 1.1μg/L (range: 0.8-1.9) and 1.1μg/L (range: 0.6-1.8).

CONCLUSION

THRA is a useful option in the long-term for young patients with osteonecrosis with Kerboul angle<330°.

LEVEL OF EVIDENCE

IV, retrospective study.

Personalized Hip Joint Replacement with Large Diameter Head: Current Concepts

Hip arthroplasty is a common procedure in elective orthopaedic surgery that has excellent outcomes. Hip replacement surgery aims to create a “forgotten” joint, i.e., a pain-free joint akin to a native articulation. To achieve such goals, hip arthroplasty must be personalised. This is achieved by restoring: the centre of rotation of the native hip; leg length equality; femoral offset; femoral orientation; soft tissue tension; joint stability with an unrestricted hip range of motion; and having appropriate stress transfer to the bone. In addition, the whole pathway should provide an uneventful and swift postoperative recovery and lifetime implant survivorship with unrestricted activities. At our institution, the preferred option is a personalized total hip arthroplasty (THA) with a large diameter head (LDH) using either monobloc or dual-mobility configuration for the acetabular component. LDH THA offers an impingement-free range of motion and a reduced risk of dislocation. The larger head-neck offset allows for a supraphysiologic range of motion (ROM). This can compensate for a patient’s abnormal spinopelvic mobility and surgical imprecision. Additionally, LDH bearing with a small clearance exerts a high suction force, which provides greater hip micro-stability. With appropriate biomechanical reconstruction, LDH THA can restore normal gait parameters. This results in unrestricted activities and higher patient satisfaction scores. We use LDH ceramic on ceramic for our patients with a life expectancy of more than 20 years and use LDH dual mobility bearings for all others.

Balance Remains Impaired after Hip Arthroplasty: A Systematic Review and Best Evidence Synthesis

Background: Hip arthroplasty (HA) is the most common intervention for joint replacement, but there is no consensus in the literature on the real influence of this procedure on balance, or on what factors in the pre-operative, surgical, and post-operative stages may affect it. Purpose: To synthesize the evidence on how Hip Arthroplasty (HA) affects balance, identifying pre-operative, surgical, and postoperative risk factors that may impair balance in HA patients, with the aim to improve patients’ management strategies. Methods: A literature search was performed on PubMed, PeDRO, and Cochrane Collaboration on 25 May 2021. Inclusion criteria: clinical report of any level of evidence; written in English; with no time limitation; about balance changes in hip osteoarthritis (OA) patients undergoing HA and related factors. Results: 27 papers (391 patients) were included. Overall, the evidence suggested that balance is impaired immediately after surgery and, 4–12 months after surgery, it becomes better than preoperatively, although without reaching the level of healthy subjects. A strong level of evidence was found for hip resurfacing resulting in better balance restoration than total HA (THA), and for strength and ROM exercises after surgery positively influencing balance. Conclusion: Both the surgical technique and the post-operative protocols are key factors influencing balance; thus, they should be carefully evaluated when managing hip OA in patients undergoing HA. Moreover, balance at 4–12 months after surgery is better than preoperatively, although without reaching the level of the healthy population. Attention should be paid in the early post-operative phase, when balance may be impaired in patients undergoing HA.

Surfing After Hip Resurfacing Surgery

OBJECTIVE

There is no information about surfing after hip resurfacing arthroplasty (HRA). We did a retrospective study aiming to evaluate the safety and feasibility to resume surfing-an extreme sport with high-impact physical activity-after HRA.

DESIGN

Retrospective case series.

SETTING

Specialist Orthopaedic Group, Mater Hospital Sydney, NSW, Australia.

PATIENTS

We evaluated 45 patients who practiced surfing before the onset of pain and hip surgery. Complete clinical and radiographical follow-up and a completed questionnaire were available for 37 (82%) patients.

INTERVENTIONS

Hip resurfacing arthroplasty.

MAIN OUTCOME MEASURES

Postel-Merle d'Aubigne score, the Oxford hip score, the Harris hip score, and the University of California at Los Angeles activity score. Radiographical evaluation at 6 weeks, 3, and 12 months after surgery and yearly thereafter. Return to surf rates using a specific questionnaire. Complications and failures during follow-up.

RESULTS

All clinical scores improved significantly after HRA. Eight of 37 (22%) patients stopped surfing after their HRA. More than 80% of patients commenced surfing within the first 6 months after surgery. During surfing, 21 patients (72%) were completely pain free.

CONCLUSION

No literature exists regarding the return to a high-impact sport as surfing after HRA. Most of our patients (71%) were able to return at least to their preoperative level of surfing after surgery. No complications related to this sport activity were observed during short-term follow-up. We believe that surfing is compatible with HRA, but long-term studies are necessary to assess the influence of this extreme sport on loosening and revision rates.

Restoration of Hip Biomechanics after a Hemiarthroplasty for a Femoral Neck Fracture—Who Does It Better?

Introduction: The restoration of the preoperative biomechanics of the hip, in particular leg length and femoral offset, are critical in restoring normal function and diminishing the risk of dislocation following hip arthroplasty. This study compares the consistency of arthroplasty and non-arthroplasty orthopedic surgeons in restoring the normal biomechanics of the hip when performing a hemiarthroplasty for the treatment of a femoral neck fracture. Methods: We retrospectively reviewed the preoperative and postoperative digital radiographs of 175 hips that had a modular hemiarthroplasty for the treatment of a displaced femoral neck fracture at a Level 1 academic hospital. Fifty-two hips were treated by one of the three fellowship-trained arthroplasty surgeons (Group A), and 123 were treated by one of the nine non-arthroplasty fellowship-trained orthopedic surgeons (Group B). Results: Patients in Group A were more likely to have their femoral offset restored to normal than patients in Group B, both with respect to under correcting the offset (p = 0.031) and overcorrecting the offset (p = 0.010). Overall, there was no difference in restoration of leg lengths between the two groups (p = 0.869). Conclusions: Following a hemiarthroplasty for a displaced femoral neck fracture, the normal biomechanics of the hip are more likely to be restored by an arthroplasty-trained surgeon than by a non-arthroplasty-trained surgeon. Identifying the inconsistency of non-arthroplasty surgeons and, to a lesser degree, arthroplasty surgeons in restoring hip biomechanics is important for sensitizing surgeons to rectify this in the future with appropriate templating and femoral implant selection.

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.

What is the Level of Evidence Substantiating Commercial Payers' Coverage Policies for Total Joint Arthroplasty?

BACKGROUND

The prevalence of total joint arthroplasty (TJA) in the United States has drawn the attention of health care stakeholders. The payers have also used a variety of strategies to regulate the medical necessity of these procedures. The purpose of this study was to examine the level of evidence of the coverage policies being used by commercial payers in the United States.

METHODS

The references of the coverage policies of four commercial insurance companies were reviewed for type of document, level of evidence, applicability to a TJA population, and success of nonoperative treatment in patients with severe degenerative joint disease.

RESULTS

282 documents were reviewed. 45.8% were primary journal articles, 14.2% were level I or II, 41.2% were applicable to patients who were candidates for TJA, and 9.9% discussed the success of nonoperative treatment in patients who would be candidates for TJA.

CONCLUSION

Most of the references cited by commercial payers are of a lower level of scientific evidence and not applicable to patients considered to be candidates for TJA. This is relatively uniform across the reviewed payers. The dearth of high-quality literature cited by commercial payers reflects the lack of evidence and difficulty in conducting high level studies on the outcomes of nonoperative versus operative treatment for patients with severe, symptomatic osteoarthritis. Patients, surgeons, and payers would all benefit from such studies and we encourage professional societies to strive toward that end through multicenter collaboration.

Instability After Total Hip Arthroplasty and the Role of Advanced and Robotic Technology

Instability remains the leading cause of reoperation following total hip arthroplasty (THA). In this article, the risk factors for instability after THA are reviewed, including patient-related characteristics, surgical techniques, positioning of implants, and the role of advanced technology and robotics as a platform that may reduce the incidence of instability.

Optimizing the Femoral Offset for Restoring Physiological Hip Muscle Function in Patients With Total Hip Arthroplasty

Objective

Femoral offset (FO) restoration is significantly correlated with functional recovery following total hip arthroplasty (THA). Accurately assessing the effects of FO changes on hip muscles following THA would help improve function and optimize functional outcomes. The present study aimed to (1) identify the impact of FO side difference on the hip muscle moment arms following unilateral THA during gait and (2) propose the optimal FO for a physiological hip muscle function.

Methods

In vivo hip kinematics from eighteen unilateral THA patients during gait were measured with a dual-fluoroscopic imaging system. The moment arms of thirteen hip muscles were calculated using CT-based 3D musculoskeletal models with the hip muscles’ lines of actions. The correlation coefficient (R) between FO and hip muscle moment arm changes compared with the non-implanted hip was calculated. We considered that the FO reconstruction was satisfactory when the abductor moment arms increased, while the extensor, adductor, and flexor moment arms decreased less than 5%.

Results

A decreased FO following THA was significantly correlated with a decrease of the abductor and external rotator moment arms during the whole gait (R > 0.5) and a decrease of extensor moment arms during the stance phase (R > 0.4). An increased FO following THA was significantly associated with shorter flexor moment arms throughout the gait (R < −0.5) and shorter adductor moment arms in the stance phase (R < −0.4). An increase in FO of 2.3–2.9 mm resulted in increased abductor moment arms while maintaining the maximum decrease of the hip muscles at less than 5.0%.

Conclusion

An increase of 2–3 mm in FO could improve the abductor and external rotator function following a THA. Accurate surgical planning with optimal FO reconstruction is essential to restoring normal hip muscle function in THA patients.

A Comparative Cohort Study With a 20-Year Age Gap: Hip Resurfacing in Patients Aged ≤35 Years and Patients Aged ≥55 Years

Background

This single-center retrospective cohort study aimed to evaluate and compare implant survival and patient-reported outcome measures in 2 distinct age groups separated by 20 years who underwent hip resurfacing arthroplasty (HRA).

Methods

Between 2005 and 2014, 2042 HRAs were performed by a single-surgeon, and 75 and 377 hips from patients aged ≤35 years and ≥55 years, respectively, were included in this study. Implant survival was determined for all available hips. Clinical features and patient-reported outcome measures were collected.

Results

Seven hips were revised, 4 for aseptic loosening of one or both components, one for infection, one for accelerated wear and metallosis, and one for femoral neck fracture. There was no difference in all-cause 10-year revision, with 97.1% (95% confidence interval 80.9 to 99.6) and 99.6% (95% confidence interval: 97 to 99.9) survivorship in younger and older patients, respectively (P = .246). Preoperatively, younger patients were less active than older patients on the Lower Extremity Activity Scale (LEAS) or University of California, Los Angeles, activity scale, but at follow-up, younger patients outpaced older ones.

Conclusion

Original to our study was the isolation and comparison of 2 distinct age groups. With excellent results in disparate age groups, HRA can be applied to a broad patient demographic and is suitable for those patients who want to achieve a high activity level as defined by Lower Extremity Activity Scale or University of California, Los Angeles, scores.

Return to work after hip resurfacing

INTRODUCTION

Hip arthroplasty is being performed in ever-younger patients, for whom return to work is a major issue. Type of job, type of implant and comorbidities all affect outcome. Heavy manual work is harder to resume after hip replacement, and reclassification or cessation of activity may ensue. This, however, is little dealt with in the literature, although its consequences are both psychologically and financially critical. The aim of the present study was to perform a retrospective analysis of return to work after hip resurfacing (HR).

MATERIAL

A retrospective study included patients undergoing Birmingham Hip Resurfacing with at least 6 months' follow-up. Occupational status was assessed, preoperatively and at follow up, as not working, in work or retired, type of work as sedentary, manual, or strenuous, and time to return to work was noted. Clinical assessment, preoperatively and at follow-up, used Postel Merle d'Aubigné, Harris, Devane, UCLA and Oxford scores.

RESULTS

One hundred and seventeen patients were included (114 male, 3 female) for 121 HRs. Mean age was 52.9 years (range, 29-66 years). Mean follow-up was 14.3 months (range, 6-20 months), with no loss to follow-up. Crutches were abandoned in week 3 on average (range, 1-7 weeks). Four patients had no occupation; analysis focused on the other 113. At follow-up, only one patient had not resumed work, and was reclassified. The other 112 (99.1% of those in work) returned to their previous job at a mean 9.4 weeks (range, 1-22 weeks). Nine patients required therapeutic part-time work for a mean 5.3 weeks (range, 3-8 weeks). Time to return to work was significantly shorter for "sedentary" workers than "physical" (manual/strenuous) workers: 6.4 weeks (range, 1-9 weeks) versus 13.5 weeks (range, 2-22 weeks).

DISCUSSION&CONCLUSION

Return to work was feasible for almost all these young patients after HR. Sedentary work was resumed very quickly (<7 weeks), while strenuous work required 3 months' sick leave.

LEVEL OF EVIDENCE

IV.

High-level judo practice after hip resurfacing

BACKGROUND AND HYPOTHESIS

The ability to participate in sports after hip arthroplasty is increasingly being requested by patients. The possibilities of participating in sports such as judo after hip arthroplasty have not been explored sufficiently even though these sports are associated with a high risk of loosening, dislocation or revision. The aim of this study was to evaluate the return to judo after hip resurfacing arthroplasty (HRA) in terms of time and level of practice in an expert population and to determine the surgical complication rate.

MATERIALS AND METHODS

This was a retrospective observational study of all licensed judo practitioners at an expert level (≥black belt 3rd Dan) who underwent HRA. Patients filled out a sport-specific questionnaire that captured their level of judo practice (international, national, regional, recreational), type of practice (teaching, technical recreational, competitive recreational), dan grade, weekly volume of practice and time elapsed after surgery before resuming judo. The features of the return to judo were analyzed (technical, ground, combat).

RESULTS

Sixty-seven HRA were implanted in 60 patients: 11 were international judokas, 3 were national, 8 were regional and 38 were recreational. The case series consisted of 18 patients who were 3rd Dan, 18 were 4th Dan, 7 were 5th Dan, 5 were 6th Dan and 12 were 7th Dan. The average follow-up was 65.3 months (range 9.9-11.9). All the clinical scores pointed to clinically and statistically significant improvement. Of the 60 patients, 53 had resumed judo at the final assessment (90%) after a mean of 4 months (2-7) for technical judo, 6 months (3-10) for ground judo and 7 months (3-12) for combat judo. Of those who did not resume their judo practice, 3 patients voluntarily changed sports, 2 had psychological apprehension and 2 had residual groin pain. The weekly volume of practice preoperatively was 0.9hours (0-5) and postoperatively it reached 5hours (2-18) (P<0.001).

CONCLUSION

HRA in a population of high-level judokas allows for return to sport practice without short-term complications such as fracture, dislocation or loosening.

LEVEL OF EVIDENCE

III.

Hip Resurfacing Compared with 28-mm Metal-on-Metal Total Hip Replacement: A Randomized Study with 15 Years of Follow-up

BACKGROUND

Bone stock conservation, hip anatomy preservation, and greater stability are among the promoted advantages of hip resurfacing (HR). However, the disappointing failure of some implants nearly led to its abandonment. The aim of this study was to compare clinical scores and revision and complication rates after HR with those after total hip arthroplasty (THA).

METHODS

Two hundred and three hips were randomized to 28-mm metal-on-metal (MoM) THA (99 hips) or to HR (104 hips). Main outcome measures compared between groups were the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, the revision rate, and the complication rates. The radiographic findings were also assessed.

RESULTS

After a mean follow-up of 15 years (range, 14 to 16 years), 9 (4.4%) of the 203 patients were lost to follow-up and 15 (7.4%) had died. The Kaplan-Meier survivorship, with revision for any reason as the end point, was 89.2% (95% confidence interval [CI], 82.3% to 96.1%) for HR and 94.2% (95% CI, 89.3% to 99.1%) for THA (p = 0.292). The reasons for revision included infection (3 patients), recurrent dislocation (1 patient), and adverse reaction to metal debris (ARMD) (1 patient) in the THA group and ARMD (2 patients) and femoral head loosening (7 patients) in the HR group. With aseptic revision as the end point, the Kaplan-Meier survivorship was significantly higher in the THA group (97.4% versus 89.2%; p = 0.033). No dislocation occurred in the HR group compared with 4 in the THA group (p = 0.058). Both groups achieved a similar mean WOMAC score (10.7 in the HR group and 8.8 in the THA group; p = 0.749), Forgotten Joint Score (87.1 and 85.3, respectively; p = 0.410), University of California Los Angeles (UCLA) activity score (6.3 and 6.4, respectively; p = 0.189), and overall joint perception (p = 0.251).

CONCLUSIONS

The specific HR and MoM 28-mm THA implants used in this study showed good long-term survival and function. The overall rates of complications and revisions were similar in both groups but were of different types. As it provides better femoral bone preservation and biomechanical reconstruction, HR may continue to have a role in selected patients when performed by experienced surgeons and using validated implants.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Hip Arthroplasty Instability After Implantation of a Spinal Cord Stimulator

A 46-year-old man with a left hip resurfacing that had been stable for over 5 years sustained a hip dislocation immediately after the implantation of a spinal cord stimulator (SCS). He continued to experience multiple episodes of instability after this initial event, requiring several revision hip arthroplasty surgeries with variable degrees of constraint. It was not until after SCS removal and prolonged hip spica casting that the patient returned to pain-free, independent ambulation. SCS implantation may affect spino-pelvic stability and alter the biomechanics of the hip after hip arthroplasty procedures. We present the unique case of a patient with a well-fixed hip resurfacing with no previous episodes of instability who experienced dislocation immediately after SCS implantation.

Return to sports after hip resurfacing versus total hip arthroplasty: a mid-term case control study

BACKGROUND

Hip resurfacing (HR) is an alternative to conventional total hip arthroplasty (THA) for the treatment of osteoarthritis (OA) in very active, young male patients. However, there is no study in the literature that has proven its benefits for high-impact sport over standard primary THA. The aim of the current study was to investigate the return to sport and function level of male patients after THA vs. HR.

MATERIALS AND METHODS

This prospective study is based on a telephone questionnaire for general health and sports activities. 40 HRs were matched with 40 THAs based on preoperative University of California Arthroplasty Score (UCLA), BMI, age at time of surgery and age at follow-up. The mean follow-up period was 56 months (range 24-87 months).

RESULTS

HR patients showed a significantly higher High-activity arthroplasty score (HAAS) (14.9 vs. 12.9, p < 0.001) and Lower extremity activity scale (LEAS) (15.9 vs. 14.1, p < 0.001) and reached significantly higher values in the Hip cycle score (HCS) (44.7 vs. 35.7 p = 0.037) and Impact score (IS) (40.9 vs. 29.6, p < 0.002) than THA patients. No significant differences were found in the HOOS function section (91.4 vs. 90.3, p = 0.803) and the Pain numeric rating scale (NRS)-11 (0.6 vs. 0.9 p = 0.169). Patients with HR had a slightly higher Harris hip score (HHS) (97.8 vs. 95.6, p = 0.015) CONCLUSION: The current study suggests that young male patients are able to engage in higher activity levels after HR compared to standard THA.

Sex-specific risk factors determine the survivorship of female and male patients after metal-on-metal hip resurfacing

BACKGROUND

The need for revision surgery after hip resurfacing arthroplasty (HRA) is more prevalent for women than for men. However, there is a paucity of information to explain this observation. We aimed (1) to determine sex-specific risk factors leading to revision surgery; and (2) to correlate these risk factors to the dominant modes of failure of HRA.

METHODS

1101 patients (1375 consecutive hips) including 292 women (355 hips) and 809 men (1020 hips) with a mean age of 51.3 years were included regardless of bone quality. The contact patch to rim distance was computed.

RESULTS

A contact patch to rim (CPR) distance of ⩽7 mm, an aetiology of developmental dysplasia, a postoperative abduction-adduction arc of ⩾95°, and a metaphyseal stem left uncemented were risk factors associated with revision surgery for female patients, while a CPR distance of ⩽10 mm, a component size of ⩽46 mm, an age at surgery of ⩽55 years, and an early femoral preparation technique were risk factors for male patients. Hips with no risk factors from the female group had a survivorship of 98.7% at 15 years, matching or exceeding the results of all male subgroups. However the risk factors in the female group increased the risk of revision much more than in the male group.

CONCLUSIONS

In the absence of risk factors, the survivorship of HRA in female patients is equal to that of males. Many female patients can safely benefit from HRA by excluding severe dysplasia and optimising surgical technique.

Accuracy of leg length and femoral offset restoration after total hip arthroplasty with the utilisation of an intraoperative calibration gauge

BACKGROUND

Offset and leg length (LL) restoration are critical for the achievement of a stable, well-functioning hip following total hip arthroplasty (THA). Several techniques are described in the literature, including a hip calibration gauge. We question whether meticulous preoperative planning of a specific surgical technique in combination with the utilisation of a calibration gauge can provide an accurate offset and LL restoration.

METHODS

Retrospective review of 101 unilateral THAs via a posterior approach by a single surgeon. Preoperative radiographic LL and offset were radiographically calculated. Intraoperatively prior to hip dislocation a calibration gauge was used to measure LL and offset with a pin inserted into the iliac crest acting as a static referencing point. All had pelvis x-ray performed 6 weeks postoperatively. A literature review was conducted to establish average postoperative LL/offset values for statistical comparison.

RESULTS

The average absolute postoperative leg-length discrepancy (LLD) was 2.51 mm compared to preoperatively 3.54 mm (p = 0.018). A total of 93.1% and 100% had LLD of ⩽5 mm and ⩽10 mm, respectively. The mean postoperative offset difference was 2.39 mm. The investigated LLD and offset results were comparable with literature data of studies utilising an intraoperative measuring device. LLD was significantly decreased when compared to a free-hand technique (LLD 4.42 mm, p < 0.001).

CONCLUSION

The technique utilising preoperative templating, intraoperative offset verification together with the use of hip calibration gauge yielded accurate LLD and offset restoration as in the literature. Precise offset restoration, which often is a neglected issue, can lead to better abductor vector restoration, hip function and less pain.

Hip resurfacing generates a more physiological gait than total hip replacement: A case-control study

BACKGROUND

Restoration of the constitutional joint anatomy after hip replacement favours physiological peri-articular soft-tissue tension and kinematics, and is likely to be functionally beneficial. Hip resurfacing (HR) and conventional total hip replacement (THR) are two different options for replacing degenerated hips, and are likely to result in different anatomical reconstruction. We initiated this study to investigate the differences in gait performance between these two prosthetic options, and aimed to answer the following questions: (1) does HR result in better restoration of the frontal hip anatomical parameters, (2) and generate a more physiological gait compared to THR? (3) Does the quality of the anatomical restoration after THR influence gait performance?

HYPOTHESES

Our hypothesis was that a better anatomical restoration using HR versus THR would produce more physiological (symmetric) gait.

METHODS

We retrospectively reviewed 52 patients who had unilateral primary osteoarthritis successfully treated by replacement (40 THRs and 12 HRs). Hip anatomical parameters were measured on standing pelvic radiographs on both the prosthetic and the contralateral healthy hips. Patients undertook gait assessment under both normal and stress conditions at a mean follow-up of 14 months (7 to 16 months). Gait performances were compared between HR and THR, and the relationship between gait performances and quality of frontal anatomical restoration (estimated on radiograph) were assessed.

RESULTS

Compared to the native contralateral side, the HR procedure tended to decrease all independent anatomical radiographic parameters with the exception of the vertical centre of rotation offset, whilst the THR procedure tended to increase them; the difference between HR and THR was only statistically significant for femoral offset and global horizontal offset (increased after THR while reduced after HR). Only 50% of THR and 25% of HR procedures closely anatomically (±15%) recreated both global horizontal offset and global vertical offset. Under normal conditions (normal walking speed and flat ramp), the gait was fairly symmetric for both the HR and the THR patients with a symmetry index of 0.62% and 3.14% respectively. At high walking speed (stress conditions), the symmetry index degraded for both groups, but the gait remained more symmetric in the HR group (2.09%), compared to the THR group (5.74%); nevertheless, the difference remained not statistically significant (p=0.159). We were unable to detect any significant relationship between gait performances and radiographically measured hip frontal anatomical parameters.

DISCUSSION/CONCLUSIONS

HR procedure is more consistent than conventional THR in generating a more physiological gait under stress conditions. Radiographic estimation of the quality of the frontal anatomical hip restoration is of poor value to predict gait performances of THR patients.

LEVEL OF EVIDENCE

III - retrospective case-control study with prospective data collection.

Periprosthetic hip infection treated with two-stage stage-one Select Spacer- complication rate and restoration of anatomy

Two-stage revision with 'StageOne™ Select Hip Cement Spacer' is used as treatment of periprosthetic hip joint infection. The aim is to evaluate complications and restoration the joint with the StageOne Select Spacer. From 2013 to 2018 twenty-nine StageOne Select Spacers was inserted. Data was obtained through medical records and radiographs. 3.5% dislocated the spacer, 6.9% sustained a femoral fracture, 6.9% got reinfected and 6.9% failed to control the infection. Leg length discrepancy was 1.5 mm (-4,25-5.25) and offset discrepancy was 4 mm (-0.5-9). The spacer shows promising results with a low reinfection and dislocation rate and allowance of restoration of the joint.

Pre-operative templating in THA. Part I: a classification of architectural hip deformities

INTRODUCTION

While numerous classifications of hip arthritis have been proposed, none considered the magnitude and direction of femoral head translation relative to the native acetabulum. A more precise classification of architectural hip deformities is necessary to improve preoperative templating and anticipate surgical challenges of total hip arthroplasty (THA). The purpose of the present study was to introduce a classification system to distinguish different types of architectural hip deformities, based on femoral head translation patterns, and to evaluate its repeatability using plain radiographs (qualitative) and Computed Tomography (CT) measurements (quantitative).

MATERIALS AND METHODS

We studied pre-operative frontal and lateral hip radiographs and CT scans of 191 hips (184 patients) that received primary THA. The distance between the femoral head center (FC) and the acetabular center (AC) was measured, as well as femoral offset, acetabular offset, head center height, acetabular floor distance and femoral neck angle. The hips were classified qualitatively using frontal plain radiographs, and then quantitatively using CT scans (with an arbitrary threshold of 3 mm as Centered, Medialized, Lateralized, Proximalized or Proximo-lateralized. The agreement between qualitative and quantitative classification methods was compared for applying the same classification.

RESULTS

Qualitative classification identified 120 centered (63%), 8 medialized (4%), 49 lateralized (26%), 3 proximalized (2%), and 11 proximo-lateralized (6%) hips, while quantitative classification identified 116 centered (61%), 8 medialized (4%), 51 lateralized (27%), 5 proximalized (3%), and 11 proximo-lateralized (6%) hips. The agreement between the two methods was excellent (0.94; CI 0.90-0.98). Medialization reached 9.7 mm, while lateralization reached 10.9 mm, and proximalization reached 8.5 mm. Proximalized and proximo-lateralized hips had more valgus necks, while medialized hips had more varus necks (p = 0.003).

CONCLUSIONS

The classification system enabled repeatable distinction of 5 types of architectural hip deformities. The excellent agreement between quantitative and qualitative methods suggests that plain radiographs are sufficient to classify architectural hip deformities.

Preliminary report of clinical experience with metal-on-highly-crosslinked-polyethylene hip resurfacing

Objectives

Modern metal-on-metal (MoM) hip resurfacing arthroplasty (HRA), while achieving good results with well-orientated, well-designed components in ideal patients, is contraindicated in women, men with head size under 50 mm, or metal hypersensitivity. These patients currently have no access to the benefits of HRA. Highly crosslinked polyethylene (XLPE) has demonstrated clinical success in total hip arthroplasty (THA) and, when used in HRA, potentially reduces metal ion-related sequelae. We report the early performance of HRA using a direct-to-bone cementless mono-bloc XLPE component coupled with a cobalt-chrome femoral head, in the patient group for whom HRA is currently contraindicated.

Methods

This is a cross-sectional, observational assessment of 88 consecutive metal-on-XLPE HRAs performed in 84 patients between 2015 and 2018 in three centres (three surgeons, including the designer surgeon). Mean follow-up is 1.6 years (0.7 to 3.9). Mean age at operation was 56 years (sd 11; 21 to 82), and 73% of implantations were in female patients. All patients were individually counselled, and a detailed informed consent was obtained prior to operation. Primary resurfacing was carried out in 85 hips, and three cases involved revision of previous MoM HRA. Clinical, radiological, and Oxford Hip Score (OHS) assessments were studied, along with implant survival.

Results

There was no loss to follow-up and no actual or impending revision or reoperation. Median OHS increased from 24 (interquartile range (IQR) 20 to 28) preoperatively to 48 (IQR 46 to 48) at the latest follow-up (48 being the best possible score). Radiographs showed one patient had a head-neck junction lucency. No other radiolucency, osteolysis, component migration, or femoral neck thinning was noted.

Conclusion

The results in this small consecutive cohort suggest that metal-on-monobloc-XLPE HRA is successful in the short term and merits further investigation as a conservative alternative to the current accepted standard of stemmed THA. However, we would stress that survival data with longer-term follow-up are needed prior to widespread adoption.

Cite this article: R. B. C. Treacy, J. P. Holland, J. Daniel, H. Ziaee, D. J. W. McMinn. Preliminary report of clinical experience with metal-on-highly-crosslinked-polyethylene hip resurfacing. Bone Joint Res 2019;8:443–450. DOI: 10.1302/2046-3758.810.BJR-2019-0060.R1

Clinical efficacy of orthopilot navigation system versus conventional manual of total hip arthroplasty: A systematic review and meta-analysis

BACKGROUND

To compare the clinical efficacy between Orthopilot navigation system and conventional manual surgery in total hip arthroplasty (THA).

METHODS

Electronic databases were searched to identify randomized controlled trials (RCTs) investigating Orthopilot navigation system versus conventional manual in patients undergoing THA. Outcome measurements include anteversion angle, inclination angle, preoperative leg length discrepancy, postoperative leg length discrepancy and femoral offset. Statistical software Stata 12.0 was used for data-analysis.

RESULTS

A total of 5 studies were finally included in this meta-analysis. The results showed that the conventional manual group have a less anteversion angle than that in Orthopilot navigation system group (weighted mean difference (WMD) = 4.67, 95% confidence interval (CI) = 3.53, 5.82, P = .000). And pooled analysis showed that the inclination angle in Orthopilot navigation group was less than that in conventional manual group (WMD = -4.19, 95% CI = -8.00, -0.37, P = .031). There was no significant difference between the preoperative leg length discrepancy and postoperative leg length discrepancy (P > .05). Orthopilot navigation system compared with conventional manual procedure was associated with decreased of femoral offset by 2.76 (WMD = -2.76, 95%CI = -3.90, -1.62, P = .000).

CONCLUSION

Both Orthopilot navigation system and conventional THA result in significant improvements in patient function with similar overall complication rates and have their own edges in cup position.

Dislocation of large-diameter head metal-on-metal total hip arthroplasty and hip resurfacing arthroplasty

INTRODUCTION

Dislocation of large-diameter head (LDH) metal-on-metal (MoM) total hip arthroplasty (THA) or hip resurfacing arthroplasty (HRA) is a rare complication. This study aimed to determine the incidence and risk factors for dislocation of LDH MoM THAs and HRAs.

METHODS

This retrospective analysis considered 4038 cementless LDH MoM THAs and HRAs, 3207 THAs in 2912 patients and 831 HRAs in 757 patients. The end of follow-up was revision due to dislocation. Incidence of dislocation was evaluated from this study population of 4038, and study groups were formed. The study was designed as a case-control study, and a threefold stratified randomised control group was formed. Demographic data were collected and radiological analyses were performed in the study groups.

RESULTS

There were 26/3207 (0.8%) early dislocations in the THA group, and 6/831 (0.7%) in the HRA group ( p = 0.9). Most LDH THA dislocations occurred in a group with head size ⩽ 38 mm (18/26) ( p < 0.001). In dislocated hips, there were more dysplastic acetabula and post-traumatic hips than in the control group ( p = 0.036). In the dislocation group, the mean acetabulum component anteversion angle was 19.6° (standard deviation [SD] 13.4°) and in the control group it was 23.2° (SD 10.4°) ( p = 0.006); 7/32 (21.8%) of dislocated THAs needed revision surgery, and mean time to revision from the index surgery was 1.2 (SD 2.6) years.

DISCUSSION

Dislocations occurred more often in THAs of head size ⩽ 38 mm and with a smaller anteversion angle of the acetabulum component. Hip dysplasia and post-traumatic osteoarthritis were more common in patients with dislocation.

Is there evidence to support an indication for surface replacement arthroplasty?: a systematic review

AIMS

Surface replacement arthroplasty (SRA), compared with traditional total hip arthroplasty (THA), is more expensive and carries unique concern related to metal ions production and hypersensitivity. Additionally, SRA is a more demanding procedure with a decreased margin for error compared with THA. To justify its use, SRA must demonstrate comparable component survival and some clinical advantages. We therefore performed a systematic literature review to investigate the differences in complication rates, patient-reported outcomes, stress shielding, and hip biomechanics between SRA and THA.

MATERIALS AND METHODS

A systematic review of the literature was completed using MEDLINE and EMBASE search engines. Inclusion criteria were level I to level III articles that reported clinical outcomes following primary SRA compared with THA. An initial search yielded 2503 potential articles for inclusion. Exclusion criteria included review articles, level IV or level V evidence, less than one year's follow-up, and previously reported data. In total, 27 articles with 4182 patients were available to analyze.

RESULTS

Fracture and infection rates were similar between SRA and THA, while dislocation rates were lower in SRA compared with THA. SRA demonstrated equivalent patient-reported outcome scores with greater activity scores and a return to high-level activities compared with THA. SRA more reliably restored native hip joint biomechanics and decreased stress shielding of the proximal femur compared with THA.

CONCLUSION

In young active men with osteoarthritis, there is evidence that SRA offers some potential advantages over THA, including: improved return to high level activities and sport, restoration of native hip biomechanics, and decreased proximal femoral stress shielding. Continued long-term follow up is required to assess ultimate survivorship of SRA.

Clinical efficacy of OrthoPilot navigation system versus conventional manual total hip arthroplasty: A systematic review and meta-analysis

Objective

This study was performed to compare the clinical efficacy between the OrthoPilot navigation system and conventional manual surgery in patients undergoing total hip arthroplasty.

Methods

The Embase, PubMed, CINAHL, and Cochrane databases were searched for clinical trials. The outcome measurements were the anteversion angle, inclination angle, and complications. Review Manager 5.3 statistical software was used for the data analysis.

Results

Significant differences were found in the femoral offset and overall complication rate between the conventional and navigation groups. Additionally, the conventional group had significantly less anteversion than the navigation group. However, the navigation group had significantly better inclination. The operation time was significantly shorter in the conventional than navigation group.

Conclusion

Both the OrthoPilot navigation system and conventional total hip arthroplasty result in significant improvements in patient function with similar overall complication rates and have their own advantages in achieving good cup position. The conventional procedure has a shorter operation time than does use of a navigation system.

The Utilization of Metal Augments Allows Better Biomechanical Reconstruction of the Hip in Revision Total Hip Arthroplasty With Severe Acetabular Defects: A Comparative Study

BACKGROUND

Reconstructing the normal hip biomechanics is important for a successful revision total hip arthroplasty (THA). Little is known about whether using metal augments in revision THA is biomechanically superior to traditional techniques.

METHODS

A retrospective review was conducted on 74 consecutive THAs revised using metal augments with a cementless hemispherical cup and 77 consecutive THAs revised using the jumbo cup, all with a minimum 2-year follow-up. Biomechanical parameters were measured before and immediately after the revision. Radiological and clinical outcomes at follow-ups were also evaluated.

RESULTS

The metal augment group had a reconstructed center of rotation (COR) that was 6.5 mm closer to the anatomic COR in height (P < .001), had 3.6 m smaller cup size (P < .001), and had 5.7 mm less head-cup difference (P < .001). Moreover, there was a reconstructed COR that was much closer to the anatomic COR (vertical distance: 1.8 vs 14.1 mm, P < .001; horizontal distance: -2.1 vs 7.9 mm, P = .013), had 4.1 mm greater femoral offset (P = .006), and had 8 mm less leg length discrepancy (P = .035) in the subgroup of Paprosky type III bone defects when compared to the jumbo cup group. All cup-augment constructs were radiologically stable with a higher mean postoperative Harris Hip Score (P = .012). One jumbo cup was radiologically unstable.

CONCLUSION

In revision THA, utilizing metal augments helps to restore the COR position more precisely, avoid using a larger cup, reduce head-cup difference, rebuild femoral offset, and decrease leg length discrepancy, particularly with Paprosky type III bone defects. Moreover, it provides satisfactory radiological and clinical outcomes in the short term.

A novel ceramic coating for reduced metal ion release in metal-on-metal hip surgery

An ovine total hip arthroplasty model was developed to evaluate metal ion release, wear, the biological response and adverse tissue reaction to metal-on-metal (MoM) bearing materials. The performance of an advanced superlattice ceramic coating (SLC) was evaluated as a bearing surface and experimental groups divided into; (1) MoM articulating surfaces coated with a SLC coating (SLC-MoM), (2) uncoated MoM surfaces (MoM), and (3) metal on polyethylene (MoP) surfaces. Implants remained in vivo for 13 months and blood chromium (Cr) and cobalt (Co) metal ion levels were measured pre and postoperatively. Synovial tissue was graded using an ALVAL scoring system. When compared with the MoM group, sheep with SLC-MoM implants showed significantly lower levels of chromium and cobalt metal ions within blood over the 13-month period. Evidence of gray tissue staining was observed in the synovium of implants in the MOM group. A significantly lower ALVAL score was measured in the SLC-MoM group (3.88) when compared with MoM components (6.67) (p = 0.010). ALVAL results showed no significant difference when SLC-MOM components were compared to MoP (5.25). This model was able to distinguish wear and the effect of released debris between different bearing combinations and demonstrated the effect of a SLC coating when applied onto the bearing surface. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1760-1771, 2019.

Metal on Metal Hip Resurfacing in Patients 45 Years of Age and Younger at Minimum 5-Year Follow-Up

BACKGROUND

Metal on metal hip resurfacing (MoM-HR) is an alternative to total hip arthroplasty in young and active patients. The purpose was to determine the survivorship of MoM-HR procedures performed in patients aged 45 years and younger assessing patient-reported outcome measures (PROMs) at minimum 5-year follow-up.

METHODS

All 217 patients equal to or younger than 45 years of age at the time of surgical intervention presenting to our center with MoM-HR between May 2002 and May 2011 were prospectively followed. Baseline demographic data, preoperative and postoperative radiographic measurements, and validated PROMs were obtained (Hip Disability and Osteoarthritis Outcome Score, Western Ontario and McMaster Universities Osteoarthritis Index, and University of California, Los Angeles Activity Score). Survivorship was calculated using Kaplan-Meier analysis, and risk factors for failure were identified using multivariate regression analysis.

RESULTS

The overall survivorship excluding septic failures was 94.6% and 93.8% at 5 and 10 years, respectively. Aseptic loosening of the acetabular component was the most common mode of failure (11/20 cases). Gender, head size, and acetabular abduction angle had no significant effect on survivorship. Significant improvements in PROMs were seen for Hip Disability and Osteoarthritis Outcome Score, Western Ontario and McMaster Universities Osteoarthritis Index, and University of California, Los Angeles Activity Scale (P < .001).

CONCLUSION

This study indicates that MoM-HR is a suitable option for young individuals, as demonstrated through improved functional scores and low revision rates. The survivorship of HR in the younger than 45 age-group was similar to that of total hip arthroplasty, as well as HR in older patients. Given the proposed benefits of HR, this procedure may be viewed as a viable option in patients aged younger than 45 years.

Comparison of revision risks and complication rates between total HIP replacement and HIP resurfacing within the similar age group

BACKGROUND AND PURPOSE

Currently it is not clear whether age is a factor affecting revisions in total hip replacement (THR) and hip resurfacing (HR). This study aimed to investigate which of THR or HR has a higher risk in terms of revision and complication within similar age groups.

METHODS

A systemic review was performed for published literature research databases and local data and compared the two procedures under the condition that both groups of patients were age matched. Meta-analysis techniques were used to analyse revision and complication rates. Twenty-seven literature studies were included along with local audit data. In total, 2520 HR procedures were compared with age-matched 2526 of THR procedures.

MAIN FINDINGS

It was found that revision risk of HR is significantly higher than THR (risk ratio 1.65, 95% CI 1.28-2.31, p < 0.0001), highlighting that HR has a slightly higher chance of reoperation when compared to THR within the similar age group population. In terms of complications, HR was found to have an advantage over THR (risk ratio 0.84, 95% CI 0.73-0.96, p < 0.01).

CONCLUSION

THR had a lower revision risk but a slightly higher complication risk than HR under the condition that the two surgical procedures were applied to similar age groups of patients. In other words, age has not played an important role in revision and complication. Survivorship cannot be measured as follow-up periods were different in the studies used.

Hip resurfacing before 50years of age: A prospective study of 979 hips with a mean follow-up of 5.1years

BACKGROUND

Hip resurfacing arthroplasty (HRA) is an alternative to total hip arthroplasty (THA) for the treatment of hip osteoarthritis in patients younger than 50 years. Data on revision rates after HRA are conflicting. The National Institute for Health and Care Excellence (NICE) recommends performing only those hip arthroplasty procedures associated with 10-year revision rates no greater than 5% (0.5% per year). Follow-up studies can rapidly determine whether this criterion is met. The uncertainties surrounding revision rates after HRA prompted us to design a study of prospectively enrolled patients aiming (1) to determine the revision rate after HRA performed before 50years of age and (2) to assess the functional, radiological, and biological outcomes of HRA.

HYPOTHESIS

The revision rate after HRA performed before 50years of age meets the NICE criterion.

MATERIAL AND METHODS

Consecutive patients undergoing HRA before 50years of age were enrolled prospectively. The same implant was used in all patients. Functional outcomes were assessed based on the Harris Hip Score (HHS), Postel-Merle d'Aubigné (PMA) score, 12-item Oxford Hip Score (OHS), and UCLA activity score. Radiographic outcomes were assessed, and blood levels of chromium and cobalt were assayed.

RESULTS

The study included 936 patients (979 HRAs) with a mean age of 42.7years (16.4-50.0years) at surgery and a mean follow-up of 5.1years (range: 3.1-9.0 years). All four mean functional scores were significantly improved at last follow-up vs. baseline: HHS, 95.9 (39.0-100) vs. 44.3 (18.0-83.0); PMA score, 17.6 (6.0-18.0) vs. 11.7 (3.0-16.0); OHS, 14.3 (12.0-37.0) vs. 40.6 (25.0-60.0); and UCLA activity score, 7.8 (2.0-10.0) vs. 5.6 (1.0-10.0) (p<0.0001). Mean cup inclination in the coronal plane was 42.1° (25.0°-68.0°). Mean blood cobalt level was significantly higher at last follow-up than at baseline (1.36μg/L [0.05-8.2μg/L] vs. 0.61μg/L [0.01-3.6]) (p<0.001). No patient experienced dislocation. Revision was required for 17 hips and involved changing the implant in 12 (1.2%). The 10-year survival rate with implant change, as the endpoint was 98.7% (95%CI, 97.6%-99.3%), indicating that the NICE criterion was easily met.

DISCUSSION

The NICE criterion allows the rapid identification of prostheses with insufficient survival. HRA is theoretically associated with a high risk of aseptic mechanical loosening, as it is performed in young patients who have a high level of physical activity. Nevertheless, our study showed that implant survival after HRA was better than required by the NICE criterion. Thus, HRA is a valid alterative to THA in patients younger than 50years.

LEVEL OF EVIDENCE

IV, prospective study with no control group.

Wear testing of a canine hip resurfacing implant that uses highly cross-linked polyethylene

Hip resurfacing offers advantages for young, active patients afflicted with hip osteoarthritis and may also be a beneficial treatment for adult canines. Conventional hip resurfacing uses metal-on-metal bearings to preserve bone stock, but it may be feasible to use metal-on-polyethylene bearings to reduce metal wear debris while still preserving bone. This study characterized the short-term wear behavior of a novel hip resurfacing implant for canines that uses a 1.5 mm thick liner of highly cross-linked polyethylene in the acetabular component. This implant was tested in an orbital bearing machine that simulated canine gait for 1.1 million cycles. Wear of the liner was evaluated using gravimetric analysis and by measuring wear depth with an optical scanner. The liners had a steady-state mass wear rate of 0.99 ± 0.17 mg per million cycles and an average wear depth in the central liner region of 0.028 mm. No liners, shells, or femoral heads had any catastrophic failure due to yielding or fracture. These results suggest that the thin liners will not prematurely crack after implantation in canines. This is the first hip resurfacing device developed for canines, and this study is the first to characterize the in vitro wear of highly cross-linked polyethylene liners in a hip resurfacing implant. The canine implant developed in this study may be an attractive treatment option for canines afflicted with hip osteoarthritis, and since canines are the preferred animal model for human hip replacement, this implant can support the development of metal-on-polyethylene hip resurfacing technology for human patients. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1196-1205, 2018.

Hip prostheses in young adults. Surface prostheses and short-stem prostheses

The poor results obtained in young patients when using a conventional prosthesis led to the resurgence of hip resurfacing to find less invasive implants for the bone. Young patients present a demand for additional activity, which makes them a serious challenge for the survival of implants. In addition, new information technologies contribute decisively to the preference for non-cemented prostheses. Maintaining quality of life, preserving the bone and soft tissues, as well as achieving a very stable implant, are the goals of every hip orthopaedic surgeon for these patients. The results in research point to the use of smaller prostheses, which use the metaphyseal zone more and less the diaphyseal zone, and hence the large number of the abovementioned short stem prostheses. Both models are principally indicated in the young adult. Their revision should be a more simple operation, but this is only true for hip resurfacing, not for short stems.

Choice of implant combinations in total hip replacement: systematic review and network meta-analysis

Objective To compare the survival of different implant combinations for primary total hip replacement (THR). Design Systematic review and network meta-analysis. Data sources Medline, Embase, The Cochrane Library, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, and the EU Clinical Trials Register.Review methods Published randomised controlled trials comparing different implant combinations. Implant combinations were defined by bearing surface materials (metal-on-polyethylene, ceramic-on-polyethylene, ceramic-on-ceramic, or metal-on-metal), head size (large ≥36 mm or small <36 mm), and fixation technique (cemented, uncemented, hybrid, or reverse hybrid). Our reference implant combination was metal-on-polyethylene (not highly cross linked), small head, and cemented. The primary outcome was revision surgery at 0-2 years and 2-10 years after primary THR. The secondary outcome was the Harris hip score reported by clinicians.Results 77 studies were included in the systematic review, and 15 studies (3177 hips) in the network meta-analysis for revision. There was no evidence that the risk of revision surgery was reduced by other implant combinations compared with the reference implant combination. Although estimates are imprecise, metal-on-metal, small head, cemented implants (hazard ratio 4.4, 95% credible interval 1.6 to 16.6) and resurfacing (12.1, 2.1 to 120.3) increase the risk of revision at 0-2 years after primary THR compared with the reference implant combination. Similar results were observed for the 2-10 years period. 31 studies (2888 patients) were included in the analysis of Harris hip score. No implant combination had a better score than the reference implant combination.Conclusions Newer implant combinations were not found to be better than the reference implant combination (metal-on-polyethylene (not highly cross linked), small head, cemented) in terms of risk of revision surgery or Harris hip score. Metal-on-metal, small head, cemented implants and resurfacing increased the risk of revision surgery compared with the reference implant combination. The results were consistent with observational evidence and were replicated in sensitivity analysis but were limited by poor reporting across studies.Systematic review registration PROSPERO CRD42015019435.

High-impact sport after hip resurfacing: The Ironman triathlon

BACKGROUND

Returning to high-impact sport is an increasingly frequent functional demand following hip replacement. The literature, however, is sparse on the subject and nonexistent regarding triathlon. We therefore conducted a retrospective study of hip resurfacing in triathlon players, to determine: (1) whether it is possible to return to this kind of sport; (2) if so, whether it is possible to return to the same level; and (3) how a resurfaced hip behaves under these conditions.

HYPOTHESIS

Hip resurfacing allows return to competition level in long-distance triathlon.

MATERIAL AND METHODS

A single-center single-operator retrospective study included patients undergoing hip resurfacing with the Conserve Plus implant inserted through a posterolateral approach, who had ceased long-distance triathlon practice due to osteoarthritis of the hip. Fifty-one of the 1688 patients undergoing resurfacing during the inclusion period were long-distance triathlon players.

RESULTS

The series comprised 48 patients: 51 implants; 43 male, 5 female; mean age, 44.8 years (range, 28.2-58.9 years). At a mean 4.7 years' follow-up (range, 2.2-7.6 years), all clinical scores showed significant improvement; Merle d'Aubigné and Harris scores rose respectively from 12.3 (5-16) and 42 (37-56) preoperatively to 17.5 (13-18) and 93.2 (73-100) (P<0.001). There were no cases of dislocation or implant revision. Forty-five patients returned to sport (94%). Rates of return to swimming, cycling and running were respectively 38/48 (79%), 41/48 (85%) and 33/48 (69%). Preoperatively, all patients had taken part in at least 1 competition: 29 with distance=70.3km and 19 with distance=140.6km. At follow-up, 28 patients had taken part in an Ironman competition: 21 with distance=70.3km and 7 with distance=140.6km. Mean competition performance did not differ between pre and postoperative periods.

DISCUSSION

Return-to-sport rates were good following hip resurfacing. Non-impact sports (swimming, cycling) predominated postoperatively, whereas the rate of impact sport (running) diminished. Return to competition-level sport (extreme triathlon) was possible for 28/48 patients (58%). Implant survival seemed unaffected by this high-impact sports activity at a mean 4.7 years' follow-up.

LEVEL OF EVIDENCE

IV, retrospective, non-controlled.

Is there a role for femoral offset restoration during total hip arthroplasty? A systematic review

Benefits of femoral offset restoration during total hip arthroplasty should be the reduction of bearing surfaces wear, implant loosening and dislocation rates. Modular neck stems ensure offset customization but fretting corrosion and catastrophic failures are well-documented complications. Since clinical evidences are needed to substantiate the effectiveness of femoral offset restoration and promote modular neck choice, we systematically reviewed the literature to ascertain whether femoral offset itself has a proven clinical influence: (1) on bearing surfaces wear, (2) implant loosening, (3) and dislocation rates. A systematic literature screening was conducted to find papers dealing with the influence of femoral offset on wear, dislocation and loosening, including articles with conventional radiographic femoral offset assessment and with comparative design. Observational studies, case reports, instructional course lectures, cadaveric and animal studies as well as biomechanical studies, letters to the editor, surgical techniques or technical notes were all excluded. No limits about publication date were supplied but only papers in English were taken into account. Data were extracted into an anonymous spreadsheet. Offset values, dislocation rates, wear rates, follow-up and surgical approaches were all detailed. Ten manuscripts were finally selected. A statistically significant correlation between femoral offset restoration and the reduction of conventional ultrahigh-molecular-weight polyethylene wear was found in two out of three papers investigating this issue, but no correlations were found between femoral offset and dislocation rates or implant loosening. Femoral offset modification influences ultrahigh-molecular-weight polyethylene liners wear, but no correlation was found with dislocation rates or implant loosening. Advantages on wear can be counterbalanced by the use of hard bearing surfaces or highly cross-linked polyethylene liners, besides the availability of larger femoral heads improving implant stability further reduces the importance of femoral offset restoration by means of modularity. We believe that efforts in restoring femoral offset during total hip arthroplasty do not translate into tangible clinical profits and consequently, we do not advise the routinely usage of modular neck stems in total hip arthroplasty.

LEVEL OF EVIDENCE

level III, systematic review of case-control studies.

Robotic-arm assisted total hip arthroplasty results in smaller acetabular cup size in relation to the femoral head size: a matched-pair controlled study

PURPOSE

To compare the acetabular component size relative to the patient's native femoral head size between conventional THA (CTHA) approach and robotic-arm assisted THA (RTHA) to infer which of these techniques preserved more acetabular bone.

METHODS

Patients were included if they had primary osteoarthritis (OA) and underwent total hip replacement between June 2008 and March 2014. Patients were excluded if they had missing or rotated postoperative anteroposterior radiographs. RTHA patients were matched to a control group of CTHA patients, in terms of preoperative native femoral head size, age, gender, body mass index (BMI) and approach. Acetabular cup size relative to femoral head size was used as a surrogate for amount of bone resected. We compared the groups according to 2 measures describing acetabular cup diameter (c) in relation to femoral head diameter (f): (i) c-f, the difference between cup diameter and femoral head diameter and (ii) (c-f)/f, the same difference as a fraction of femoral head diameter.

RESULTS

57 matched pairs were included in each group. There were no significant differences between groups for demographic measures, femoral head diameter, or acetabular cup diameter (p>0.05). However, measures (i) and (ii) did differ significantly between the groups, with lower values in the RTHA group (p<0.02).

CONCLUSIONS

Using acetabular cup size relative to femoral head size as an approximate surrogate measure of acetabular bone resection may suggest greater preservation of bone stock using RTHA compared to CTHA. Further studies are needed to validate the relationship between acetabular cup size and bone loss in THA.

Restoration of the centre of rotation in primary total hip arthroplasty: the influence of acetabular floor depth and reaming technique

AIMS

One goal of total hip arthroplasty is to restore normal hip anatomy. The aim of this study was to compare displacement of the centre of rotation (COR) using a standard reaming technique with a technique in which the acetabulum was reamed immediately peripherally and referenced off the rim.

PATIENTS AND METHODS

In the first cohort the acetabulum was reamed to the floor followed by sequentially larger reamers. In the second cohort the acetabulum was only reamed peripherally, starting with a reamer the same size as the native femoral head. Anteroposterior pelvic radiographs were analysed for acetabular floor depth and vertical and horizontal position of the COR.

RESULTS

Horizontally, the mean medial displacement of the COR was 0.8 mm (standard deviation (sd) 1.4) in the peripheral remaing group and 5.0 mm (sd 3.30) in the standard reaming group (p < 0.001). Vertically, the mean superior displacement of the COR was 0.7 mm (sd 1.3) in the peripheral reaming group and 3.7 mm (sd 2.6) in the standard reaming group (p < 0.001). In the standard reaming group, there was a strong correlation between the pre-operative acetabular floor depth and displacement of the COR (p < 0.001).

CONCLUSION

Reaming the acetabulum to the floor can lead to significant displacement of the COR medially and superiorly. This displacement is related to the pre-operative acetabular floor depth and cannot always be compensated by using a high offset stem. Cite this article: Bone Joint J 2016;98-B:1597-603.

Hip Resurfacing: International Perspectives: Review Article

BACKGROUND

The hip resurfacing concept was developed for young and active patients, especially for femoral bone stock preservation. However, concerns about metal-on-metal bearings with adverse reactions to metal debris have led to a drop off in hip-resurfacing procedures.

QUESTIONS/PURPOSES

The goal of this review is to evaluate our current knowledge of survivorship of second-generation hip resurfacing devices and elaborate international perspectives for product improvement.

METHODS

A comprehensive literature search provided information on national joint arthroplasty registers worldwide with a minimum of 3000 reported hip resurfacings. It culminated in the analysis of six registers.

RESULTS

Long-term data showed that available hip resurfacing device survivorship ranged from 95 to 99.7% with 10 years of follow-up, in selected patient populations. The criteria for success were well known, male gender, good bone quality, head component size greater than 48 mm, and cup inclination less than 45°. On the other hand, the recent recall of some hip-resurfacing devices has resulted in huge medico-legal problems and has discredited all implants. It has brought about the recent evolution of hip resurfacing. Femoral fixation is now available for cemented and cementless surfaces. Bearings are still always metal-on-metal, but new types have come on board. Newer designs suggest that ceramic-on-ceramic, cross-linked polyethylene, and oxinium may be applied in this configuration.

CONCLUSIONS

In 2015, the evolution of hip resurfacing is ongoing in terms of implant design, alternative bearings, and implant fixation with hopes of improving survivorship.

Comparison of Cemented and Bone Ingrowth Fixation Methods in Hip Resurfacing for Osteonecrosis

BACKGROUND

The optimal surgical treatment for osteonecrosis of the femoral head has yet to be elucidated. To evaluate the role of femoral fixation techniques in hip resurfacing, we present a comparison of the results for 2 consecutive groups: group 1 (75 hips) received hybrid hip resurfacing implants with a cemented femoral component; group 2 (103 hips) received uncemented femoral components. Both groups received uncemented acetabular components.

METHODS

We retrospectively analyzed our clinical database to compare failures, reoperations, complications, clinical results, metal ion test results, and X-ray measurements. Using consecutive groups caused time interval bias, so we required all group 2 patients to be at least 2 years out from surgery; we compared results from 2 years and final follow-up.

RESULTS

Patient groups matched similarly in age, body mass index, and percent female. Despite similar demographics, the uncemented, group 2 cases showed a lower raw failure rate (0% vs 16%; P < .0001), a lower 2-year failure rate (0% vs 7%; P = .04), and a superior 8-year implant survivorship (100% vs 91%; log-rank P = .0028; Wilcoxon P = .0026). In cases that did not fail, patient clinical (P = .05), activity (P = .02), and pain scores (P = .03), as well as acetabular component position (P < .0001), all improved in group 2, suggesting advancements in surgical management. There were no cases of adverse wear-related failure in either group.

CONCLUSION

This study demonstrates a superior outcome for cases of osteonecrosis with uncemented hip resurfacings compared to cases employing hybrid devices.

Hip resurfacing and pseudotumour

Metal on metal hip resurfacing has been used widely over the last ten years but there has been recent concern about destructive soft tissue reactions, which have been called pseudotumours by some authors. This has generated considerable controversy. This review explains why pseudotumours occur after resurfacing and how they can be prevented. It also supports the continued use of resurfacing in appropriate patients by appropriately trained surgeons.

Gluteal tendon reconstruction in association with hip arthroplasty

We studied a prospective cohort of patients in whom gluteal tendon reconstruction was undertaken in association with hip arthroplasty. Over the course of 10 years, 24 patients had gluteal tendon reconstruction performed either at the time of hip arthroplasty or post-operatively, using the Ligament Augment and Reconstruction System (LARS), suture anchors, direct suture to bone, or a combination of these techniques. All patients were assessed clinically and by patient-centred outcome measures, including the hip disability and osteoarthritis score (HOOS). The mean post-operative HOOS was significantly better than pre-operative score (p < 0.05). The mean post operative score in the domains of symptoms, pain, activities of daily living (ADL), sports and quality of life (QoL) was 72 (SD 12.8), 73 (SD 15.9), 71 (SD 11.8), 54 (SD 22.6) and 57 (SD 21.76) respectively. There were two failures of gluteal tendon reconstruction which required revision using LARS. One patient died of an unrelated cause. Surgical intervention should be considered in gluteal tendinopathy at the time of hip arthroplasty or when symptoms occur following arthroplasty.