Total Hip Resurfacing Arthroplasty Research Articles

Comparison of Acetabular Bone Resection, Offset, Leg Length and Post Operative Function Between Hip Resurfacing Arthroplasty and Total Hip Arthroplasty

Controversy exists regarding the amount of acetabular bone resection, biomechanics and function of patients receiving either total hip arthroplasty (THA) or hip resurfacing arthroplasty (HRA). A cohort of patients undergoing 36 mm ceramic-on-ceramic THA (89) or metal-on-metal HRA (86) were compared. No difference was observed when the ratio of native femoral head size was compared to the implanted acetabular component size (1.15±0.1 HRA c.f. 1.13±0.1 THA). No difference was observed in acetabular offset, vertical centre of rotation or function (OHS mean 47 in both groups) but leg length discrepancy (1.8 mm c.f. 5.5 mm) and femoral offset did differ (0.6 mm c.f. 4.1 mm). This demonstrates that 36 mm ceramic-on-ceramic THA is not associated with more bone resection than HRA and achieves equivalent function whilst avoiding the problems of metal-on-metal bearings.

The effect of total hip and hip resurfacing arthroplasty on vertical ground reaction force and impulse symmetry during a sit-to-stand task

BackgroundThe aim of this study was to determine the influence of total hip arthroplasty and hip resurfacing arthroplasty on limb loading symmetry before, and after, hip reconstruction surgery during a sit-to-stand task. MethodsFourteen patients were recruited that were about to receive either a total hip prosthesis (n=7) or a hip resurfacing prosthesis (n=7), as well as matched controls. Patients performed a sit-to-stand movement before, 3months after, and 12months after surgery. Peak vertical ground reaction force and impulse were measured for each leg, from which ground reaction force and impulse symmetry ratios were calculated. FindingsBefore surgery, hip resurfacing patients showed a small asymmetry which was not different to normal for ground reaction force (0.88(0.28) vs. 1.00(0.11); p=0.311) or impulse (0.87(0.29) vs. 0.99(0.09); p=0.324) symmetry ratios. Total hip patients offloaded their affected hip by 30% in terms of impulse symmetry ratio (0.71(0.36) vs. 0.99(0.23); p=0.018). At 3months following surgery asymmetries were seen that were different to normal in both hip resurfacing patients for ground reaction force (0.77(0.16); p=0.007), and total hip patients for ground reaction force (0.70(0.15); p=0.018) and impulse (0.72(0.16); p=0.011) symmetry ratios. By 12months after surgery total hip patients regained a symmetrical loading pattern for both ground reaction force (0.95(0.06); p=0.676) and impulse (1.00(0.06); p=0.702) symmetry ratios. Hip resurfacing patients, however, performed the task by overloading their operated hip, with impulse symmetry ratio being larger than normal (1.16(0.16); p=0.035). InterpretationPhysiotherapists should appreciate the need for early recovery of limb loading symmetry as well as subsequent differences in the responses observed with different prostheses.

UK temporal trends for time from diagnosis of hip/knee osteoarthritis to joint replacement

s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S214 and regional JRRs) members of the ISAR with publicly available annual reports in English. We compared definitions and reporting of common outcomes: mean age of patients; primary and revision procedures specific to total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA); definitions, coding, analysis, and reporting of revisions; documentation of reasons for revision; and the type, frequency, and reporting of PROMs. Results: Eight of 24 identified hip JRRs met our inclusion criteria: the Australian Orthopaedic Association National Joint Replacement Registry, the Canadian Joint Replacement Registry, the National Joint Registry of England and Wales, the New Zealand Joint Registry, the Norwegian Arthroplasty Register, the Scottish Arthroplasty Project, the Slovak Arthroplasty Register, and the Swedish Hip Arthroplasty Register. The annual number of primary and revision hip replacement procedures was reported by all JRRs. Six JRRs reported the annual number of primary procedures specific to HRAs, while just four JRRs reported the number of revision HRAs. Seven JRRs reported the mean age of THA patients, and two JRRs reported the mean age of HRA patients. The definition of revision was similar across all JRRs. Various units (hips, patients and components) and metrics (revision burden, person-time incidence rates and cumulative percent revised) were used to analyze and report revisions. Kaplan-Meier survival analysis was used among six JRRs that provided survivorship curves. Seven JRRs reported reasons for revision for all types of hip replacements, while only two JRRs provided reasons for revision for HRAs. Although three JRRs described the collection of PROMs, only one JRR reported PROMs (EQ-5D, pain and satisfaction visual analogue scales) in their annual report. Conclusions: Our review highlights considerable variability in the collection, analysis, and reporting of surgical and patient-reported outcomes among eight hip JRRs, which creates challenges when comparing outcomes across JRRs. Few JRRs currently collect and report PROMs, despite increased pressure among policy makers to use PROMs to assess appropriateness of care. Going forward, JRRs have the opportunity to collectively incorporate standardized PROMs into regular data collection and encourage their widespread use, though the choice of instrument and frequency of data collection, analysis, and reporting will require careful consideration. The integration of PROMs along with standardizedmetrics and analysis methods has the potential to improve the monitoring and comparability of joint replacement outcomes internationally, and ultimately improve care provided to patients requiring joint replacement surgery. 375 OUTCOMES AFTER TOTAL HIP REPLACEMENT R. Pinedo-Villanueva yz, D. Turner x, J.P. Raftery k, C. Cooper z, N.K. Arden y. yUniv. of Oxford, Oxford, United Kingdom; zMRC Lifecourse Epidemiology Unit, Southampton, United Kingdom; xUniv. of East Anglia, Norwich, United Kingdom; kUniv. of Southampton, Southampton, United

Editorial

Women do not benefit from medical research as much as men do [2, 5]. This problem stems both from research design (which scientists largely control), and from scientific reporting in journals (which editors can influence). Starting with the latter, we first must learn to talk about sex. Sex (female or male) refers to the genotype, while gender (woman or girl, man or boy) refers to the social constructs that overlie the genotype. Gender tends to be culturally laden, and as such, separating sex from gender in certain kinds of research is nearly impossible. Do women as a cultural norm have less pain after knee replacement, or is it a condition innate to the biology of the female sex? If the former, might this be driven by women reporting pain differently on standardized scoring instruments (or to their surgeons, who are more likely to be men)? Or are there important physiological differences in pain signaling between males and females? Other explanations are possible — for example, it is likely that women’s responses are interpreted differently by surgeons of either gender — and it is not always possible to know whether sex, gender, or both account for the observed effect. But when possible, we will seek clarity in authors’ explanations: Are the differences gender-driven, sex-driven, or is it not possible to tell? This is not just a semantic issue. It is a health issue, both for women and men. Women have been underrepresented in medical research, and therefore the evidence that drives their care is less robust [2, 5]. Pharmacokinetics and responses to important therapeutic interventions differ between men and women [3], and women are more likely to experience adverse drug reactions [6]. Surgeons may believe this is a “medical thing” and not a problem in orthopaedic surgery. That is wrong. Women consume approximately 85% of the Cox-II-specific NSAIDs that are prescribed and the side effect profiles of these drugs — including important, life-threatening side effects — differ between men and women [6]. Yet, the treatment of women with NSAIDs is based on Cox-II trials consisting disproportionately of men [1]. We learned only belatedly that women are at much greater risk of complications and failure after total hip resurfacing arthroplasty [4], and the result suggests that clearer scientific reporting would have prevented harm to many women. We probably do not know the full extent of the harm we may be causing because the reporting of results by gender is so inconsistently performed in medical and surgical trials in our specialty. This must change. Accordingly, we recommend that investigators writing for CORR®: Design studies that are sufficiently powered to answer research questions both for males and females (or men and women) if the health condition being studied occurs in both sexes/genders. Provide sex- and/or gender-specific data where relevant in all clinical, basic science, and epidemiological studies. Analyze the influence (or association) of sex or gender on the results of the study, or indicate in the Patients and Methods section why such analyses were not performed, and consider this topic as a limitation to cover in the Discussion section. Readers need to know whether the results generalize to both sexes/genders. Indicate (if sex or gender analyses were performed post-hoc) that these analyses should be interpreted cautiously because they may be underpowered (leading to a false conclusion of no difference). If there are many such analyses, indicate that they may lead to spurious significance, and an erroneous conclusion of a sex- or gender-related difference. We present these as recommendations, rather than requirements for publication because the topic is relatively new to the collective consciousness of our specialty. Our editorial board will continue to evaluate whether and when guidelines like these should become requirements. For now, we will consider the scientific reporting of sex- and gender-related findings an important element of the papers we consider for publication. Our research needs to reflect that we treat both men and women, and that both are equally entitled to the benefits of care based on good, applicable evidence.

Resurfacing hip arthroplasty in neuromuscular hip disorders – A retrospective case series

BackgroundManagement of the degenerate hip in patients with neuromuscular conditions should be aimed at improving quality of life and ease of nursing care. Arthroplasty poses a significant challenge with predisposition to dislocation and loosening due to anatomical abnormalities, soft tissue contractures and impaired muscle tone. MethodsWe present a series of 11 hips (9 patients) following total hip resurfacing arthroplasty for painful osteoarthritis in patients with differing neuromuscular conditions. Patients were assessed clinically and radiographically and also for satisfaction of their carers due to improved ability to provide nursing care.Mean patient age was 33.1 years (range 13–49 years) with mean follow up at publication 63.7 months (41–89 months). All patients were operated by a single surgeon (AHN) and received the required post operative care and physiotherapy. Soft tissue releases were performed when necessary. All hips were assessed clinically and radiographically at 6 weeks and 6 months and 1 year post-operatively. Six month follow-up also included a questionnaire with scoring of care-provider satisfaction. ResultsTen hips had good clinical results with improvement in pain and function and radiologically showed no signs of loosening. One hip required revision to proximal femoral excision due to dislocation and loose acetabular component with severe pain. None of the other hips dislocated.Analysis of care provider satisfaction assessing ability to provide personal care, positioning and transferring, comfort, interaction and communication scored excellent to good in 10 patients and satisfactory in one. ConclusionWe believe hip resurfacing arthroplasty to be a viable option in the treatment of the complex problem of osteoarthritis in the hips of patients with neuromuscular disease. The improved biomechanics confer greater stability when compared to conventional total hip arthroplasty. Although technically demanding, a successful result has been shown to improve patient pain, function and ease of nursing care. Level of evidenceLevel IV.

Hip Resurfacing Does Not Improve Proprioception Compared With THA

Proposed benefits of total hip resurfacing arthroplasty over total hip arthroplasty (THA) include better proprioception, but this has not been rigorously tested or validated. Our purpose was to apply an advanced testing device that objectively quantifies dynamic postural stability to determine if total hip resurfacing is associated with improved proprioception compared with standard or large-head THA. Three groups of 25 patients (total hip resurfacing, THA femoral head > 32 mm, THA femoral head ≤ 32 mm) and a matched control group were recruited. All participants had UCLA scores ≥ 5 and Harris hip scores ≥ 90 at the time of testing. Testing was conducted using a commercially available device that uses a multidirectional, powered platform to measure deviations of the center of mass and consisted of trials with both double- and single-limb support. Double-limb testing showed no differences between groups. In single-limb testing, the operative side performed better in patients who had undergone total hip resurfacing versus THA, but this difference disappeared when the operative side was normalized to the nonoperative side. When compared with control subjects who had not had arthroplasty, both operative and nonoperative sides showed significantly worse proprioception for all arthroplasty cohorts, suggesting that decreased proprioception is associated with arthritis of the hip in young adults. Total hip resurfacing arthroplasty did not result in improved proprioception compared with THA. These results tend to refute the concept that improved proprioception is a rationale for selecting total hip resurfacing over THA in young patients.

Hip Resurfacing and Conventional THA: Comparison of Acetabular Bone Stock Removal, Leg Length, and Offset

The purpose of this study was to compare total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) with regard to the amount of acetabular bone stock removed and the ability to restore leg length and offset. Anteroposterior pelvis radiographs of 153 consecutive THAs and 84 consecutive HRAs were compared. Excluded patients were those with prior hip surgery, those in which a best-fit circle could not be adequately matched to the femoral head, and those with preoperative radiographic findings that precluded consideration for HRA (ie, disease severity, deformity, leg-length discrepancy). A significant difference was found between THA and HRA with regards to age and sex but not primary diagnosis. Relative differences in acetabular bone removal were compared using a ratio of acetabular implant diameter to preoperative ipsilateral femoral head diameter measured with a best-fit circle. The ratio of acetabular cup diameter to preoperative ipsilateral femoral head diameter was significantly greater following THA than following HRA, indicating relatively more acetabular bone removal in THA procedures. Mean leg-length discrepancy was significantly greater following THA than following HRA. Offset was increased to a greater extent following THA than following HRA. Overall, HRA was associated with relatively less acetabular bone stock removal and less alteration in leg length and offset than was THA.

Changes in Bone Mineral Density of the Acetabulum and Proximal Femur After Total Hip Resurfacing Arthroplasty

Our aim was to investigate the changes in bone mineral density (BMD) of acetabulum and proximal femur after total hip resurfacing arthroplasty. A comparative study was carried out on 51 hips in 48 patients. Group A consisted of 25 patients (26 hips) who had undergone total hip resurfacing and group B consisted of 23 patients (25 hips) who had had large-diameter metal-on-metal total hip arthroplasty (THA). BMDs around the acetabulum and proximal femur were measured using dual-energy x-ray absorptiometry (DEXA) at 2 weeks, 6 months, 1 year and annually thereafter during the 3 years after surgery. At final follow-up, the acetabular net mean BMD decreased by 11% in group A and 10% in group B with no differences between two groups (P = .35). For the femoral side, in Gruen zone 1, the mean BMD increased by 4% in group A, whereas it decreased by 11% in group B (P = .029). In Gruen zone 7, the mean BMD increased by 8% at the final follow-up in group A, whereas it decreased by 13% in group B (P = .02). In both groups the mean BMD increased by 3% in Gruen zones 3, 4, 5, and 6. Stress-related bone loss of the acetabulum was comparable for MOM THA and resurfacing devices, but proximal femoral bone density increased in the resurfacing group and decreased in the THA group.

Patient Activity after Total Hip Arthroplasty: A Comparison of Three Different Bearing Surfaces

Patients who receive hip arthroplasty today desire prostheses that not only have great longevity, but are also suitable for a very active lifestyle. Advances in metallurgy, tribologic behavior, surgical technique, as well as improvements in strength and microstructure, have made ceramic-on-ceramic and metal-on-metal bearings available for young patients requiring a great deal of mobility. The purpose of this study was to assess if the bearing surface had an effect, if any, on postoperative activity levels and clinical outcomes in patients receiving three different types of hip arthroplasty. This study includes three groups of 30 patients who had each received conventional metal-on-polyethylene total hip arthroplasty (THA), ceramic-on-ceramic THA, or hip resurfacing arthroplasty. All groups were matched by men to women ratio, age, body mass index, diagnosis, preoperative activity levels, and length of follow-up. Clinical outcomes evaluated included weighted postoperative activity levels, Harris hip scores, patient satisfaction scores, revision rates, and complication rates. Patients who had received a metal-on-metal resurfacing had achieved significantly higher activity scores (mean 10.5 points; range, 1-28 points) compared to patients who had received ceramic-on-ceramic (mean 6.9 points; range, 0-34 points) or metal-on-polyethylene bearings (mean 5.6 points; range, 1-18 points). The mean postoperative Harris hip scores (94 vs 92 vs 91 points), patient satisfaction scores (9 vs 8.4 vs 8.3 points), aseptic revision (3% vs 0% vs 0%), and complication rates (3% vs 3% vs 3%) were similar between resurfacing, ceramic-on-ceramic, and metal-on-polyethylene bearing groups, respectively. This study showed that in cohorts of similarly matched arthroplasty patients in multiple demographics factors and preoperative activity levels, metal-on-metal resurfacing arthroplasty may offer higher postoperative activity levels. For patients with higher activity levels, resurfacing arthroplasty may be advantageous compared to other types of bearings.

Stair Ascending and Descending in Hip Resurfacing and Large Head Total Hip Arthroplasty Patients

Large head total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) are alternatives to standard THA that generally have head sizes larger than 36mm. This study examined 20 patients (10 large head THA and 10 HRA), at an average of 18months postoperatively, and 15 healthy control subjects during stair negotiation. Hip kinetic and kinematic variables and ground reaction forces were measured. The THA and HRA groups ascended the stairs with increased peak hip flexion angles and decreased hip extension angles as compared with controls. The operative groups also descended the stairs with decreased hip flexion moments. No differences between the operative groups were observed. Eighteen months postoperatively, patients with large head THA or HRA display abnormal flexion and extension during a physically-demanding task.

Large Diameter Metal on Metal Articulations. Comparison of Total Hip Arthroplasty and Hip Resurfacing Arthroplasty

The use of large diameter metal bearing total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) increased in popularity in the last decade. More recent literature has highlighted the effect of head size in patient outcomes. Data was obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOA-NJRR) to evaluate the Birmingham (MoM) bearing surface when used with THA and HRA. There is no difference in the overall rate of revision between the THA and HRA but head size has a significant effect on revision rate. The data show that small diameter metal bearings in HRA (below 50mm) have a higher rate of revision than large diameter metal bearings in HRA (equal to and above 50mm) (P<.001). Conversely the large diameter metal bearings in THA have a higher rate of revision than the small diameter metal bearings in THA (P=.027). The revision rate for large diameter HRA compared to small diameter THA is not significantly different P=.670. We recommend caution when choosing either a large diameter (≥50mm) metal on metal THA or small diameter (<50mm) HRA.

The Utility of MARS MRI in Patients with Metal-on-Metal Bearings

Metal-on-metal bearings for total hip arthroplasty have a long history of use that dates back to the introduction of the McKee-Farrar prosthesis in the 1960s. Metal-on-metal bearings ultimately fell out of favor because of the excellent clinical results of the Charnley low-friction arthroplasty concept, which employed metal-on-UHMWPE (ultra-high molecular weight polyethylene) bearing surfaces. However, the use of metal-on-metal bearings was revisited in the 1990s as polyethylene-associated periprosthetic osteolysis emerged as a major clinical problem limiting the longevity of hip reconstructions in high-demand patient populations. Within the last decade, numerous metal-on-metal designs for both total hip arthroplasty and hip resurfacing arthroplasty have been introduced into the marketplace. However, over the last several years it has become evident that contemporary metal-on-metal bearings are not immune to some of the problems, including periprosthetic osteolysis, that have plagued other bearing surface combinations. In addition, investigators described a distinct histological pattern, termed “aseptic lymphocyte-dominated vasculitis-associated lesion” (ALVAL), that was associated with symptomatic metal-on-metal bearings. More recently, investigators described local soft-tissue reactions termed “pseudotumors” in association with symptomatic metal-on-metal devices. Initially, studies of adverse local tissue reactions (including osteolysis, ALVAL, and pseudotumors) in retrospective studies of metal-on-metal implants did not indicate the prevalence. However, case-control studies and registries began to document that certain metal-on-metal bearing designs were associated with an unacceptably high failure rate, leading to high-profile device recalls that captured the attention of the worldwide media. In some cases, the adverse local tissue response …

Prevalence of Pseudotumor in Asymptomatic Patients After Metal-on-Metal Hip Arthroplasty

The cause of recently reported pseudotumor formation in patients with metal-on-metal hip replacements is unknown. It has been postulated that there is an association between elevated levels of serum metal ions and pseudotumor formation. The primary purpose of this study was to assess the prevalence of pseudotumor formation in asymptomatic patients with a metal-on-metal total hip replacement after a minimum duration of follow-up of two years. A secondary purpose was to assess whether a correlation exists between elevated serum metal ion levels and pseudotumor formation. In the present study, the prevalence of pseudotumor formation, as detected with ultrasound, was evaluated for thirty-one asymptomatic patients with a metal-on-metal total hip arthroplasty, twenty-four asymptomatic patients with a metal-on-polyethylene total hip arthroplasty, and twenty asymptomatic patients with a metal-on-metal hip resurfacing arthroplasty. Serum levels of cobalt and chromium were measured in the metal-on-metal total hip arthroplasty and hip resurfacing arthroplasty groups. Ten patients (32%) in the metal-on-metal total hip arthroplasty group had a solid or cystic mass, with another three patients (10%) having a substantial fluid collection. Five patients (25%) in the hip resurfacing arthroplasty group had a solid or cystic mass, with another patient (5%) having a fluid collection. Pseudotumor formation was significantly more frequent in the metal-on-metal total hip arthroplasty group compared with the metal-on-polyethylene total hip arthroplasty group (p = 0.015). We did not detect a significant correlation between the serum metal ion levels and the size of pseudotumor abnormality. The median serum metal ion level was greater in patients with pseudotumor formation than it was in those without pseudotumor formation, but the difference was not significant. We recommend high-resolution ultrasound surveillance of all asymptomatic patients with a metal-on-metal implant that is known to result in high serum metal ion levels. Once a metal-on-metal implant is known to be associated with high serum metal ions, the measurement of ion levels does not helpfully contribute to surveillance.

Patient Preferences and Willingness to Pay for Arthroplasty Surgery in Patients With Osteoarthritis of the Hip

Little is known about the economic value patients place on effective treatment of osteoarthritis (OA) of the hip. The purpose of this study was to evaluate the value of total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) to patients with advanced hip OA by measuring their preferences and willingness to pay (WTP) for either procedure. Seventy-three patients younger than 65 years with advanced hip OA reviewed information about the risks and benefits of THA and HRA and were asked which procedure they would choose and how much they would be willing to pay for it. Sixty-nine percent of patients chose THA (average WTP, $69 419) and 31% chose HRA (average WTP, $83 195). There was no correlation between WTP and annual income or total assets. However, patients with modest income and assets could have reported that they were willing and able to pay more than they could actually afford, and WTP dropped and correlation with income rose if we excluded high responses from the poorest respondents. These results may have important policy implications as patients are asked to share a greater burden of the cost of their care for chronic conditions such as OA.

Recovery in mechanical muscle strength following resurfacing vs standard total hip arthroplasty – a randomised clinical trial

To evaluate the effect of resurfacing vs standard total hip replacement on post-surgery hip and knee muscle strength recovery in a prospective randomised controlled trial at the Department of Orthopaedics, University Hospital, Odense, Denmark. Forty-three patients were randomised into (A) standard total hip arthroplasty (S-THA) and (B) resurfacing total hip arthroplasty (R-THA). Pre-surgery assessment and follow-up were conducted (8, 26 and 52wks). Maximal isometric muscle strength (Nm) and between-limb asymmetry for the knee extensors/flexors, hip adductors/abductors, hip extensors/flexors were analysed. Maximal knee extensor and hip abductor strength were higher in S-THA than R-THA at 52wks post-surgery (P≤0.05) and hip extensors tended to be higher in S-THA at 52wks (P=0.06). All muscle groups showed substantial between-limb strength asymmetry (7-29%) with the affected side being weakest (P≤0.05) and hip flexors being most affected. Asymmetry was present in half of the muscle groups at 26wks (P≤0.05), and remained present for the hip flexors and hip adductors at 52wks (P≤0.05). R-THA patients showed an attenuated and delayed recovery in maximal lower limb muscle strength (in 2/6 muscle groups) compared to S-THA. Notably, the attenuated strength recovery following R-THA was most markedly manifested in the late phase (1yr) of post-surgical recovery, and appeared to be due to the detachment of the lower half of the gluteus maximus muscle rather than implant design per se. Thus, the present data failed to support the hypothesis that R-THA would result in an enhanced strength rehabilitation compared to S-THA. Further, between-limb asymmetry remained present for hip flexors and adductors after 52wks. NCT01229293.

Amine-Rich Cell-Culture Surfaces for Research in Orthopedic Medicine

We report results of ongoing research relating to cell immobilization and cell culture on bioactive organic coatings deposited using three different techniques−two plasma assisted, the third based on vacuum-ultraviolet photo-polymerization. We start by briefly comparing those three methods and by describing some of the key characteristics of the resulting coatings; all are designed to be rich in primary amines, a functional group known to be highly bioactive. Next, we focus on two cell types of importance to long-term objectives in our orthopedic research laboratory: (i) The first, nonadherent human U937 monocytes, is a cell line that has been widely used as a model of the mammalian cellular response to various inflammatory stimuli, and in understanding the clinical relevance of elevated cobalt and chromium levels in patients with metal-on-metal total hip arthroplasty and hip resurfacing arthroplasty. (ii) The second cell type, adherent human mesenchymal stem cells (MSCs), derived from patients suffering from osteoarthritis (OA), is important in biological repair of cartilage and of the degenerate intervertebral disc (IVD) from the patients' autologous cells. Much progress has been achieved in both cases, as illustrated with results based to a considerable extent on real-time reverse-transcription (RT) polymerase chain reaction (PCR), a key methodology used in this type of research.

Design and Primary Application of Computer-Assisted, Patient-Specific Navigational Templates in Metal-on-Metal Hip Resurfacing Arthroplasty

Total hip resurfacing arthroplasty is increasingly being used. One of its goals is to closely mimic the normal anatomy and normal biomechanics of the hip joint. Prosthesis location has a large impact on implant survival and patient function; but in conventional hip resurfacing arthroplasty, precise positioning sometimes cannot be achieved. We describe a novel method for ensuring accurate prosthesis implantation in hip resurfacing arthroplasty by means of 3-dimensional reconstruction and reverse engineering.

Gait Symmetry: A Comparison of Hip Resurfacing and Jumbo Head Total Hip Arthroplasty Patients

Proponents of large femoral head total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) have touted the potential for restoration of more normal hip kinematics. This study examined 20 patients (10 THA and 10 HRA patients) approximately 18 months after surgery. Subjects were evaluated at a self-selected pace, while bilateral spatial-temporal gait variables, hip flexion/extension kinematics, and ground reaction forces were collected. For both groups, swing time was increased on the surgical side, whereas peak hip flexion, peak extension, and flexion at heel strike were decreased. Peak hip extension and peak vertical ground reaction forces were decreased in THA subjects compared with HRA subjects. After a large-diameter THA or HRA, subjects do not display symmetric gait approximately 18 months postoperatively. Total hip arthroplasty subjects demonstrated restricted hip extension and reduced limb loading when compared with HRA subjects.

A Systematic Review of Modern Metal-on-Metal Total Hip Resurfacing vs Standard Total Hip Arthroplasty in Active Young Patients

This systematic review compared 2 treatments for hip disease in active young patients: modern metal-on-metal total hip resurfacing and standard total hip arthroplasty. We conducted a literature search to identify relevant randomized and clinical controlled trials and included 968 patients from 4 trials in our analysis. Our results indicated increased rates of revision, femoral neck fractures, and component loosening among patients who received modern metal-on-metal hip resurfacing. No significant differences in the rates of mortality, dislocation, or deep hip joint infection were found between treatment groups. Hip function scores were similar between the 2 groups, but the resurfacing group showed higher activity levels. These results have provided insufficient evidence to determine whether modern metal-on-metal total hip resurfacing offers clinical advantages over standard total hip arthroplasty.

The Prevalence of Groin Pain After Metal-on-Metal Total Hip Arthroplasty and Total Hip Resurfacing

Groin pain after total hip arthroplasty (THA) or total hip resurfacing arthroplasty can be troubling for patients and surgeons. Potential sources of pain include infection, loosening, metal hypersensitivity, or impingement of bony structures or the iliopsoas tendon. We compared the rate of groin pain after THA or hip resurfacing using metal-on-metal to those of other bearing surfaces. We identified 347 (334 patients) primary total hip (n = 301) or resurfacing (n = 46) arthroplasties. Complete preoperative, operative, and postoperative data were available for 282 hips. We retrospectively reviewed the charts for the presence or absence of groin pain at a minimum of 1 year after surgery with a specific focus on etiologic factors. The minimum followup was 12 months (mean, 14 months; range 12 to 24 months). The rate of groin pain was 7% (15 of 217 patients) after THA with conventional bearing surfaces, 15% (4 of 26 patients) with metal-on-metal THA and 18% (7 of 39 patients) with total hip resurfacing. Younger patients were more likely to report groin pain postoperatively and more likely to have metal-on-metal bearing surfaces. Our data at short-term followup suggest increased rates of groin pain after metal-on-metal THA or resurfacing arthroplasty versus THA using polyethylene or ceramic bearing surfaces. The reasons are not clear but they appear to be associated with younger age. Potential factors include impingement, activity level and possibly higher expectations for patients receiving metal-on-metal bearing surfaces that may make those patients more likely to report postoperative pain. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.