Excellent results of large-diameter ceramic-on-ceramic bearings in total hip arthroplasty: Is Squeaking Related to Head Size.

AIMS: This study reports the mid-term results of total hip arthroplasty (THA) performed using a monoblock acetabular component with a large-diameter head (LDH) ceramic-on-ceramic (CoC) bearing. PATIENTS AND METHODS: Of the 276 hips (246 patients) included in this study, 264 (96%) were reviewed at a mean of 67 months (48 to 79) postoperatively. Procedures were performed with a mini posterior approach. Clinical and radiological outcomes were recorded at regular intervals. A noise assessment questionnaire was completed at last follow-up. RESULTS: There were four re-operations (1%) including one early revision for insufficient primary fixation (0.4%). No hip dislocation was reported. The mean University of California, Los Angeles (UCLA) activity score, 12-Item Short-Form Health Survey (SF-12) Mental Component Summary (MCS) score, SF-12 Physical Component Summary (PCS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and Forgotten Joint Score (FJS) were 6.6 (2 to 10), 52.8 (25.5 to 65.7), 53.0 (27.2 to 66.5), 7.7 (0 to 63), and 88.5 (23 to 100), respectively. No signs of loosening or osteolysis were observed on radiological review. The incidence of squeaking was 23% (n = 51/225). Squeaking was significantly associated with larger head diameter (p < 0.001), younger age (p < 0.001), higher SF-12 PCS (p < 0.001), and UCLA scores (p < 0.001). Squeaking did not affect patient satisfaction, with 100% of the squeaking hips satisfied with the surgery. CONCLUSION: LDH CoC THAs have demonstrated excellent functional outcomes at medium-term follow-up, with very low revision rate and no dislocations. The high incidence of squeaking did not affect patient satisfaction or function. LDH CoC with a monoblock acetabular component has the potential to provide long term implant survivorship with unrestricted activity, while avoiding implant impingement, liner fracture at insertion, and hip instability. Cite this article: Bone Joint J 2018;100-B:1434-41.

Diagnostic validity and triage concordance of a physiotherapist compared to physicians' diagnoses for common knee disorders.

BACKGROUND: Emergence of more autonomous roles for physiotherapists warrants more evidence regarding their diagnostic capabilities. Therefore, we aimed to evaluate diagnostic and surgical triage concordance between a physiotherapist and expert physicians and to assess the diagnostic validity of the physiotherapist's musculoskeletal examination (ME) without imaging. METHODS: This is a prospective diagnostic study where 179 consecutive participants consulting for any knee complaint were independently diagnosed and triaged by two evaluators: a physiotherapist and one expert physician (orthopaedic surgeons or sport medicine physicians). The physiotherapist completed only a ME, while the physicians also had access to imaging to make their diagnosis. Raw agreement proportions and Cohen's kappa (k) were calculated to assess inter-rater agreement. Sensitivity (Se) and specificity (Sp), as well as positive and negative likelihood ratios (LR+/-) were calculated to assess the validity of the ME compared to the physicians' composite diagnosis. RESULTS: Primary knee diagnoses included anterior cruciate ligament injury (n = 8), meniscal injury (n = 36), patellofemoral pain (n = 45) and osteoarthritis (n = 79). Diagnostic inter-rater agreement between the physiotherapist and physicians was high (k = 0.89; 95% CI:0.83-0.94). Inter-rater agreement for triage recommendations of surgical candidates was good (k = 0.73; 95% CI:0.60-0.86). Se and Sp of the physiotherapist's ME ranged from 82.0 to 100.0% and 96.0 to 100.0% respectively and LR+/- ranged from 23.2 to 30.5 and from 0.03 to 0.09 respectively. CONCLUSIONS: There was high diagnostic agreement and good triage concordance between the physiotherapist and physicians. The ME without imaging may be sufficient to diagnose or exclude common knee disorders for a large proportion of patients. Replication in a larger study will be required as well as further assessment of innovative multidisciplinary care trajectories to improve care of patients with common musculoskeletal disorders.

Alignment options for total knee arthroplasty: A systematic review.

In spite of improvements in implant designs and surgical precision, functional outcomes of mechanically aligned total knee arthroplasty (MA TKA) have plateaued. This suggests probable technical intrinsic limitations that few alternate more anatomical recently promoted surgical techniques are trying to solve. This review aims at (1) classifying the different options to frontally align TKA implants, (2) at comparing their safety and efficacy with the one from MA TKAs, therefore answering the following questions: does alternative techniques to position TKA improve functional outcomes of TKA (question 1)? Is there any pathoanatomy not suitable for kinematic implantation of a TKA (question 2)? A systematic review of the existing literature utilizing PubMed and Google Scholar search engines was performed in February 2017. Only studies published in peer-reviewed journals over the last ten years in either English or French were reviewed. We identified 569 reports, of which 13 met our eligibility criteria. Four alternative techniques to position a TKA are challenging the traditional MA technique: anatomic (AA), adjusted mechanical (aMA), kinematic (KA), and restricted kinematic (rKA) alignment techniques. Regarding osteoarthritic patients with slight to mid constitutional knee frontal deformity, the KA technique enables a faster recovery and generally generates higher functional TKA outcomes than the MA technique. Kinematic alignment for TKA is a new attractive technique for TKA at early to mid-term, but need longer follow-up in order to assess its true value. It is probable that some forms of pathoanatomy might affect longer-term clinical outcomes of KA TKA and make the rKA technique or additional surgical corrections (realignment osteotomy, retinacular ligament reconstruction etc.) relevant for this sub-group of patients. Longer follow-up is needed to define the best indication of each alternative surgical technique for TKA. Level I for question 1 (systematic review of Level I studies), level 4 for question 2.

Preoperative Determinants of Patient-reported Pain and Physical Function Levels Following Total Knee Arthroplasty: A Systematic Review.

BACKGROUND: A sound knowledge of the determinants of total knee arthroplasty (TKA) outcomes could help in patient selection, preparation and education. We aimed to assess the current status of the literature evaluating preoperative determinants of early and medium term patient-reported pain and disability following TKA. METHOD: A search in Medline, Pubmed, Embase and CINAHL until October 2014 was undertaken. Selection criteria included: 1- participants undergoing primary unilateral TKA with a follow-up from 6 months to 2 years, 2- validated disease-specific patient-reported outcome measures assessing pain and/or function used as outcome measure and 3- identification of preoperative determinants obtained via multivariate analyses. Risk of bias was assessed using a modified version of the Methodology checklist for prognostic studies. RESULTS: Thirty-three prognostic explanatory studies were included. Mean total score of the methodological quality was 80.7±12.2 %. Sociodemographic and psychosocial determinants included greater socioeconomic deprivation (both studies), greater levels of depression and/or anxiety (7 out of 10 studies) and greater preoperative pain catastrophizing (all 3 studies). Significant clinical determinants included worse pre-operative knee related pain or disability (20 out of 22 studies), presence or greater levels of comorbidity (12 out of 23 studies), back pain (4 out of 5 studies) and lower general health (all 11 studies). CONCLUSION: Several significant determinants of short to medium-term pain and functional outcomes following TKA have been summarized by studies with moderate-to-high methodological quality. No conclusions can be reached regarding the strength of the associations between significant determinants and TKA results because of heterogeneity of study methodologies and results. Further high-quality research is required.

A systematic review of preoperative determinants of patient-reported pain and physical function up to 2 years following primary unilateral total hip arthroplasty.

UNLABELLED: Although generally considered successful, total hip arthroplasty (THA) can yield suboptimal results in terms of pain and function in up to one forth of patients suffering from hip osteoarthritis (OA). A thorough understanding of the determinants of patient-reported pain and function following THA can help plan interventions directed at improving surgical results. Previously published systematic reviews do not permit to confidently identify the determinants of THA outcomes because of unsatisfactory methodological designs. Therefore, we aimed to answer: (1) which preoperative factors are most consistently associated with postoperative patient-reported pain and function up to 2 years following primary unilateral THA for hip OA. Medline, Pubmed, Embase and CINAHL were screened from their respective inception dates until April 2015 using a combination of keywords and MESH terms. Criteria for inclusion were: (1) participants with primary unilateral THA for hip OA followed for at least 3 months with a maximal follow-up of 2 years; (2) validated disease-specific patient-reported outcome measures assessing pain and/or disability; (3) identification of determinants obtained via multivariate analyses. Methodological quality was assessed using a modified version of the methodology checklist for prognostic studies. Twenty-two manuscripts were included. Mean score of the methodological quality was 81.0±10.3% (66.7% to 100%). Among socioeconomic determinants, a lower educational level was significantly related to worse pain and function (3 out of 3 studies evaluating the relationship). Clinical determinants of poor outcomes included preoperative levels of pain and physical function (9 out of 12 studies), higher body mass index (6 out of 10 studies), presence/greater level of comorbidities (7 out of 8), worse general health (4 out of 4 studies) and lower radiographic OA severity (3 out of 4 studies). Study heterogeneity limited the pooled assessment of the strength of associations between the preoperative variables and THA outcomes. Studies with moderate-to-high methodological quality allowed to identify 6 preoperative variables consistently associated with medium term pain and function following THA. This knowledge may assist the management of patients at risk of poor results. Further research is required to clarify the force of associations between determinants and THA outcomes. LEVEL OF EVIDENCE: Level II. Systematic review of cohort studies.

Kinematic TKA using navigation: Surgical technique and initial results.

BACKGROUND: Kinematic alignment for total knee arthroplasty (TKA) may be one way of improving outcomes. Previous studies have either used patient-specific instrumentation, which adds cost, or standard instrumentation, which provides no intraoperative feedback on resection alignment. HYPOTHESIS: To determine if computer navigation could reproduce native patient anatomy and simplify ligament balance during TKA whilst giving satisfactory improvements in functional scores at early follow-up. MATERIALS AND METHODS: Computer navigation was used for kinematic distal femoral and proximal tibial cuts in 100 consecutive and unselected TKAs. Resections were modified only if measured angles fell outside a pre-defined safe range of combined coronal orientation within±3 degrees of neutral and/or independent femoral or tibial cuts within±5 degrees. Pre- and postoperative measurements of the hip-knee-ankle (HKA) angle, the lateral distal femoral angle (LDFA) and the medial proximal tibial angle (MPTA) were taken using long-leg standing radiographs. Clinical evaluation was with the WOMAC and KOOS scales. RESULTS: Mean follow-up was 2.4 years (range 1.0-3.7, SD 0.8). The mean pre-op LDFA was 2.1 degrees valgus (9.2 valgus to 3.7 varus, SD 2.5) and 1.8 degrees valgus post-op (5.7 valgus to 4.2 varus, SD 2.0) (P=0.41). The mean pre-op MPTA was 3.0 degrees varus (10.6 valgus to 10.2 varus, SD 3.2) and 2.4 degrees varus post-op (4.0 valgus to 6.8 varus, SD 2.2) (P=0.03). The mean WOMAC score improved from 49.4 (29-85, SD 12.8) to 24.7 (0-73, SD 16.5) (P<0.001) and the mean KOOS score from 37.1 (7.2-77.2, SD 13.0) to 65.1 (26.8-100, SD 16) (P<0.001). Five knees (5%) required additional ligament release, four with valgus OA and one with varus OA. Two knees (2%) required lateral retinacular release for patellar tracking. DISCUSSION: Computer navigation for kinematic TKA provides the operating surgeon with full control and feedback at each step, whilst also allowing partial correction of more extreme anatomy that might be unsuitable for recreation during TKA. This technique helps to preserve ligament isometry and produces satisfactory improvements in functional scores. LEVEL OF EVIDENCE: IV (retrospective case series review).

A randomised trial of all-polyethylene and metal-backed tibial components in unicompartmental arthroplasty of the knee.

This randomised trial evaluated the outcome of a single design of unicompartmental arthroplasty of the knee (UKA) with either a cemented all-polyethylene or a metal-backed modular tibial component. A total of 63 knees in 45 patients (17 male, 28 female) were included, 27 in the all-polyethylene group and 36 in the metal-backed group. The mean age was 57.9 years (39.6 to 76.9). At a mean follow-up of 6.4 years (5 to 9.9), 11 all-polyethylene components (41%) were revised (at a mean of 5.8 years; 1.4 to 8.0) post-operatively and two metal-backed components were revised (at one and five years). One revision in both groups was for unexplained pain, one in the metal-backed group was for progression of osteoarthritis. The others in the all-polyethylene group were for aseptic loosening. The survivorship at seven years calculated by the Kaplan-Meier method for the all-polyethylene group was 56.5% (95% CI 31.9 to 75.2, number at risk 7) and for the metal-backed group was 93.8% (95% CI 77.3 to 98.4, number at risk 16) This difference was statistically significant (p < 0.001). At the most recent follow-up, significantly better mean Western Ontario and McMaster Universities Arthritis Index Scores were found in the all-polyethylene group (13.4 vs 23.0, p = 0.03) but there was no difference in the mean Knee injury and Osteoarthritis Outcome scores (68.8; 41.4 to 99.0 vs 62.6; 24.0 to 100.0), p = 0.36). There were no significant differences for range of movement (p = 0.36) or satisfaction (p = 0.23). This randomised study demonstrates that all-polyethylene components in this design of fixed bearing UKA had unsatisfactory results with significantly higher rates of failure before ten years compared with the metal-back components.

Influence of the stem fixation scenario on load transfer in a hip resurfacing arthroplasty with a biomimetic stem.

Finite element (FE) analysis is a widely used tool for extensive preclinical testing of orthopaedic implants such as hip resurfacing femoral components, including evaluation of different stem fixation scenarios (cementation vs osseointegration, etc.). Most FE models use surface-to-surface contact elements to model the load-bearing interfaces that connect bone, cement and implant and neglect the mechanical effects of phenomena such as residual stresses from bone cement curing. The objective of the current study is to evaluate and quantify the effect of different stem fixation scenarios and related phenomena such as residual stresses from bone cement curing. Four models of a previously clinically available implant (Durom) were used to model different stem fixation scenarios of a new biomimetic stem: a cemented stem, a frictional stem, a partially and completely bonded stem, with and without residual stresses from bone cement curing. For the frictional stem, stem-bone micromotions were increased from 0% to 61% of the available surface subjected to micromotions between 10 and 40µm with the inclusion of residual stresses from bone cement curing. Bonding the stem, even partially, increased stress in the implant at the stem-head junction. Complete bonding of the stem decreased bone strain at step tip, at the cost of increased strain shielding when compared with the frictional stem and partially bonded stem. The increase of micromotions and changes in bone strain highlighted the influence of interfacial conditions on load transfer, and the need for a better modeling method, one capable of assessing the effect of phenomena such as interdigitation and residual stresses from bone cement curing.

Bone remodeling in the resurfaced femoral head: effect of cement mantle thickness and interface characteristics.

Metal-on-metal hip resurfacing prostheses were re-introduced during the last 10-15 years. These prostheses have the potential to better restore normal function with limited activity restriction, being an option for younger and more active patients. Resurfacing procedures have demonstrated high failure rates in national registers [1,2]. Multiple factors may affect early and long-term HR performance. The influence of femoral cement mantle thickness and different interface characteristics between the prosthesis components on the long-term performance of resurfacing prostheses is still unknown. In the present work, a model was used to predict bone remodeling with different mantle thicknesses and interface characteristics. A very thin cement mantle (0.25mm) increased bone resorption at the superior femoral head, while greater thickness (1 or 3mm) had a lesser effect. In all cases, bone apposition was predicted around the stem and at the stem tip. Bone formation and resorption were observed clinically in good agreement with the predictions calculated in simulations. Computed results showed that 1-mm cement mantle thickness combined with a bonded bone-cement interface and a debonded implant-cement interface was an appropriate configuration. Bone remodeling results and computed equivalent strains were correlated. In conclusion, we have been able to demonstrate the importance of choosing an adequate cement mantle thickness. Additionally, computational studies should consider realistic interface characteristics between the components in order to perform simulations closer to reality.

Metal-on-metal hip resurfacing compared with 28-mm diameter metal-on-metal total hip replacement: a randomised study with six to nine years' follow-up.

A total of 219 hips in 192 patients aged between 18 and 65 years were randomised to 28-mm metal-on-metal uncemented total hip replacements (THRs, 107 hips) or hybrid hip resurfacing (HR, 112 hips). At a mean follow-up of eight years (6.6 to 9.3) there was no significant difference between the THR and HR groups regarding rate of revision (4.0% (4 of 99) vs 5.8% (6 of 104), p = 0.569) or re-operation rates without revision (5.1% (5 of 99) vs 2.9% (3 of 104), p = 0.428). In the THR group one recurrent dislocation, two late deep infections and one peri-prosthetic fracture required revision, whereas in the HR group five patients underwent revision for femoral head loosening and one for adverse reaction to metal debris. The mean University of California, Los Angeles activity scores were significantly higher in HR (7.5 (sd 1.7) vs 6.9 (sd 1.7), p = 0.035), but similar mean Western Ontario and McMaster Universities Osteoarthritis Index scores were obtained (5.8 (sd 9.5) in HR vs 5.1 (sd 8.9) in THR, p = 0.615) at the last follow-up. Osteolysis was found in 30 of 81 THR patients (37.4%), mostly in the proximal femur, compared with two of 83 HR patients (2.4%) (p < 0.001). At five years the mean metal ion levels were < 2.5 µg/l for cobalt and chromium in both groups; only titanium was significantly higher in the HR group (p = 0.001). Although revision rates and functional scores were similar in both groups at mid-term, long-term survival analysis is necessary to determine whether one procedure is more advantageous than the other.

Durom hip resurfacing system: retrospective study of 644 cases with an average follow-up of 34 months.

INTRODUCTION: The performance of second-generation metal-on-metal bearings has led to the reintroduction of hip resurfacing. The goal of this multicentre study was to evaluate the short-term radiological and clinical outcomes with the Durom hip resurfacing system. HYPOTHESIS: The Durom hip-resurfacing system will have similar results to other hip resurfacing systems and traditional hip arthroplasty implants. MATERIALS AND METHODS: In the four participating centers, 580 patients (406 men, 174 women) and 644 hips were included. The average patient age was 48 years (range 16-77). A posterolateral surgical approach was used in 357 cases; a Hardinge-type approach was used in 182 cases and a Rottinger-type approach in 105. RESULTS: After an average follow-up of 34 months, 31 hips (4.8%) had been revised. The reasons for revision were the following: 10 (1.6%) neck fracture (seven with Rottinger operative approach, one with Hardinge approach and one with posterolateral approach); 12 (1.9%) femoral loosening (four with lateral approach and eight with posterolateral approach); four (0.6%) acetabular cup migration; three (0.5%) unexplained pain; one (0.2%) adverse reaction to metal debris; one (0.2%) infection. Four hips (0.6%) dislocated but without recurrence - all were operated using the Hardinge approach. The 613 hips that were not operated on again had satisfactory clinical results; the Merle d'Aubigné score was 17.2 (range 12-18) and the WOMAC score was 91 (range 20-100). The five-year survival rate was 91% (95% CI: 87-94%). Based on radiographs, the average cup inclination was 44.4° (range 30 to 70°). The femoral offset was reduced by an average of 2.4mm (-31 to 23 mm) and the leg length had increased by an average of 0.8mm (-15 to 19 mm) relative to the other side, which was prosthesis-free. None of the non-revised implants showed any signs of loosening. DISCUSSION: This multicentre evaluation revealed that the Durom revision rate was slightly higher than the rate with other hip resurfacing systems and traditional total hip arthroplasty. Although the Durom system displayed excellent tribological performance, the differences relative to other implants may be attributed to the challenges associated with impaction, related to the geometry and design of the cup, and to precarious primary fixation. The choice of surgical exposure and implantation technique was an important factor in the survival of the implant. LEVEL OF PROOF: Level IV - Retrospective study.

The influence of uncemented femoral stem length and design on its primary stability: a finite element analysis.

One of the crucial factors for short- and long-term clinical success of total hip arthroplasty cementless implants is primary stability. Indeed, motion at the bone-implant interface above 40 µm leads to partial bone ingrowth, while motion exceeding 150 µm completely inhibits bone ingrowth. The aim of this study was to investigate the effect of two cementless femoral stem designs with different lengths on the primary stability. A finite element model of a composite Sawbones(®) fourth generation, implanted with five lengths of the straight prosthesis design and four lengths of the curved prosthesis design, was loaded with hip joint and abductor forces representing two physiological activities: fast walking and stair climbing. We found that reducing the straight stem length from 146 to 54 mm increased the average micromotion from 17 to 52 µm during fast walking, while the peak value increased from 42 to 104 µm. With the curved stem, reducing length from 105 to 54 mm increased the average micromotion from 10 to 29 µm, while the peak value increased from 37 to 101 µm. Similar findings are obtained for stair climbing for both stems. Although the present study showed that femoral stem length as well as stem design directly influences its primary stability, for the two femoral stems tested, length could be reduced substantially without compromising the primary stability. With the aim of minimising surgical invasiveness, newer femoral stem design and currently well performing stems might be used with a reduced length without compromising primary stability and hence, long-term survivorship.

Joint perception after hip or knee replacement surgery.

INTRODUCTION: Knee and hip arthroplasties are recognized as being effective. However, subjects with a prosthetic joint rarely report returned sensation comparable to their native joint. HYPOTHESIS: Joint perception by patients following hip joint replacement is better than following knee replacement and in both cases this perception is directly related to the clinical results measured with currently validated scores. PATIENTS AND METHODS: Patient joint perception in prosthetic reconstruction was evaluated in 347 patients, 46 who underwent unicompartmental knee arthroplasty (UKA), 119 tricompartmental knee arthroplasty (TKA), 93 hip resurfacing (HR), and 89 total hip arthroplasty (THA). The subjects' joint perception, their satisfaction, and the WOMAC clinical score were recorded and compared. RESULTS: Joint perception was significantly worse for knee arthroplasties (TKA and UKA) compared to hip arthroplasties (THA or HR) (P<0.001). The WOMAC score was also significantly less favorable for knee arthroplasties than for hip arthroplasties (P<0.0001). However, there was no significant difference for the clinical scores between TKA and UKA as well as between HR and THA. Joint perception was strongly correlated with the WOMAC score for all groups (R(2)=0.951). DISCUSSION: No difference was found after more conservative surgeries such as HR or UKA compared to traditional arthroplasty procedures (THA or TKA). Demonstrating inferior results in comparison to the hip, knee arthroplasties deserve particular attention and can still be improved. The assessment of joint perception used in this study can be considered a valuable clinical tool that is strongly correlated to validated, but more complex to apply, clinical scores.

Anisotropic bone remodeling of a biomimetic metal-on-metal hip resurfacing implant.

Hip resurfacing (HR) is a highly attractive option for young and active patients. Some surgeons have advocated cementing the metaphyseal stem of the femoral component to improve fixation and survivorship of HR. However, extending component fixation to the metaphysis may promote femoral head strain shielding, which in turn may reduce survival of the femoral component. Replacing the metallic metaphyseal stem by a composite material with bone-matching properties could help to alleviate this phenomenon. This study uses finite element analysis to examine the strain state in the femoral head for three types of implant fixation: an unfixed metallic stem, an osseointegrated biomimetic stem and a cemented metallic stem. Bone remodeling is also simulated to evaluate long-term bone resorption due to strain shielding. Results show that the unfixed stem causes strain shielding in the femoral head, and that cementing the stem increases strain shielding. The biomimetic stem does not eliminate the strain shielding effect, but reduces it significantly versus the metallic cemented version. The current finite element study suggests that an osseointegrated metaphyseal stem made of biomimetic material in hip resurfacing implants could become an interesting alternative when fixation extension is desired.

Radiographic changes of the femoral neck after total hip resurfacing.

INTRODUCTION: Significant femoral neck narrowing following hip resurfacing arthroplasty has been observed. Several factors contributing to the physiopathology of femoral neck narrowing have been suggested. The aim of this study was to evaluate the femoral neck radiographic changes observed after hip resurfacing at a minimum follow-up period of 5 years and to determine their causes. PATIENTS AND METHODS: We conducted a prospective study of 57 hip resurfacing arthroplasties performed in 53 patients (30 men, 23 women) of mean age 49.2 years (32-65) at surgery. These patients were clinically reviewed (inguinal pain during walking, WOMAC and UCLA scores) at 2 years and radiographically examined at 1, 2 and 5 postoperative years. The accuracy of our computer-aided measurement method was 1mm. Measurement of femoral neck to implant ratio was performed to assess the amount of neck thinning at the femoral neck-implant junction (N/H) and midway between the implant and the inter-trochanteric line (N(1/2)H) on an AP radiograph. Neck-thinning greater than 10% was considered as significant. Any other radiographic morphologic change in the femoral neck was investigated. Metallic ion concentration in blood was measured. A uni- and multivariate analysis was performed to determine the correlation with radiographic changes. RESULTS: In one third of the patients, femoral neck narrowing was greater than 1mm at 2 and 5 postoperative years. Such result corresponds to a mean decrease in neck to implant ratio (N/H) of 5.9% (range, 2.3 to 9.4) at 2 years and 8.3% (range, 2.5 to 23.8) at 5 years. At 5 postoperative years, an overall neck thinning greater than 10% was reported in 3 patients (with a 10- to 17-% increase in femoral neck narrowing between the 2nd and the 5th postoperative year). In one case, neck thinning was associated with fracture of the femoral stem managed with revision surgery during which femoral neck necrosis was confirmed. Neck thinning was, in these cases, circumferential to the neck-implant junction. There was no significant negative impact on clinical scores and no relationship could be established between neck thinning and factors such as BMI or patient activity. Moreover, neck thinning greater than 10% was reported in two cases after 2 postoperative years through the appearance of a localized femoral neck notching which was absent in the postoperative period, secondary to a femoroacetabular impingement. DISCUSSION-CONCLUSION: Femoral neck narrowing used to be a common phenomenon after HR when polyethylene acetabular bearings were implanted thus inducing osteolysis secondary to PE wear debris. The incidence of such phenomenon has decreased but still occurs after HR when using a metal-on-metal bearing surface. It has an early occurence but stabilizes after 2 postoperative years. Changes in mechanical stress distribution in the neck region after hip resurfacing have been hypothesized to be a cause of neck thinning. Other aetiologies may be suggested. An overall evolutive femoral neck narrowing after 2 postoperative years should raise the suspicion of necrosis leading to a risk of loosening, fracture or implant failure. Therefore, radiographic monitoring should be conducted. The presence of femoral neck notching secondary to femoroacetabular impingement represents a differential diagnosis which conservative treatment is advocated in the absence of any associated symptoms.

Metal-on-metal bearings total hip arthroplasty: the cobalt and chromium ions release concern.

With certain concerns recently reported on metal-on-metal bearing couples in total hip arthroplasty, this study's objective is to review the current knowledge concerning release of metal ions and its potential consequences. Each metal-on-metal implant presents different tribological properties. The analytical techniques for metals are accurate and the Co ion rates seem acceptable up to 2 µg/L. A delayed type IV hypersensitivity reaction (atypical lymphocytic vasculitis-associated lesion [ALVAL]) may be the source of arthroplasty failure. Idiosyncratic, it remains unpredictable even using cutaneous tests and apparently is rare (0.3%). Today, there are no scientific or epidemiologic data supporting a risk of carcinogenesis or teratogenesis related to the use of a metal-on-metal bearings couple. Solid pseudotumors nearly exclusively are observed with resurfacing procedures, carrying a high annual revision rate in women under 40 years of age, occurring particularly in cases of acetabular malposition and with use of cast molded Cr-Co alloys. Osteolysis manifests through complete and progressive radiolucent lines or through cavitary lesions stemming from ALVAL-type alterations or impingement problems or implant incompatibility. The formation of wear debris exceeding the biological tolerance is possible with implant malposition, subluxation, and jamming of the femoral head in cases of cup deformity. Moreover, each implant presents different metal ion production; assessment of their performance and safety is required before their clinical use. With the knowledge available today, metal-on-metal bearing couples are contraindicated in cases of metal allergies or end stage renal dysfunction and small size resurfacing should cautiously be used.

Metal ion release from bearing wear and corrosion with 28 mm and large-diameter metal-on-metal bearing articulations: a follow-up study.

We have updated our previous randomised controlled trial comparing release of chromium (Cr) and cobalt (Co) ions and included levels of titanium (Ti) ions. We have compared the findings from 28 mm metal-on-metal total hip replacement, performed using titanium CLS/Spotorno femoral components and titanium AlloFit acetabular components with Metasul bearings, with Durom hip resurfacing using a Metasul articulation or bearing and a titanium plasma-sprayed coating for fixation of the acetabular component. Although significantly higher blood ion levels of Cr and Co were observed at three months in the resurfaced group than in total hip replacement, no significant difference was found at two years post-operatively for Cr, 1.58 microg/L and 1.62 microg/L respectively (p = 0.819) and for Co, 0.67 microg/L and 0.94 microg/L respectively (p = 0.207). A steady state was reached at one year in the resurfaced group and after three months in the total hip replacement group. Interestingly, Ti, which is not part of the bearing surfaces with its release resulting from metal corrosion, had significantly elevated ion levels after implantation in both groups. The hip resurfacing group had significantly higher Ti levels than the total hip replacement group for all periods of follow-up. At two years the mean blood levels of Ti ions were 1.87 microg/L in hip resurfacing and and 1.30 microg/L in total hip replacement (p = 0.001). The study confirms even with different bearing diameters and clearances, hip replacement and 28 mm metal-on-metal total hip replacement produced similar Cr and Co metal ion levels in this randomised controlled trial study design, but apart from wear on bearing surfaces, passive corrosion of exposed metallic surfaces is a factor which influences ion concentrations. Ti plasma spray coating the acetabular components for hip resurfacing produces significantly higher release of Ti than Ti grit-blasted surfaces in total hip replacement.

[Hip resurfacing: current state of knowledge]. / Resurfaçage de hanche: état actuel des connaissances.

SUMMARY: The tribologic quality of metal-on-metal bearings has enabled a second generation of hip resurfacing techniques. Compared with a conventional hip prosthesis, this type of arthroplasty has many advantages: sparing femoral (and acetabular) bone stock, preservation of hip joint biomechanics (femoral offset, leg length), better recovery for high-level sports activities, easier revision, less risk of dislocation, less risk of extension to the shaft in the event of osteolysis. Hip resurfacing can thus be considered as true "minimally invasive bone surgery". There are however specific complications of resurfacing, including femoral neck fracture and collapse of the femoral head. All of the conventional approaches can be used for hip resurfacing procedures, but a precise operative technique is mandatory. The key to success is a proper position of the femoral piece. Certain biomechanical rules for implantation are required in order to limit the cam effect, spare femoral bone, and maintain harmonious loading. Hip resurfacing can be indicated for young and/or active subjects for whom restoration of hip biomechanics offers a real advantage over conventional hip arthroplasty. The mid-term results have been encouraging, both clinically and radiographically.

[Return to sport after hip resurfacing or total hip arthroplasty: a randomized study]. / Activités sportives après resurfaçage et prothèse totale de hanche : une étude prospective randomisée.

PURPOSE OF THE STUDY: Since component wear of the prosthetic metal-polyethylene bearing is directly related to the level of patient activity, it would be logical, for patients with a total hip arthroplasty, to advise against long-term participation in activities with repeated movements The purpose of this prospective randomized study was to compare the type, intensity and frequency of sports activities performed after resurfacing hip arthroplasty (RH) or total hip arthroplasty (THA) using a metal-on-metal bearing. MATERIAL AND METHODS: This study concerned 205 hips, including 152 with a unilateral hip arthroplasty (71 THA and 81 RH). Three clinical scores were used: an overall activity score, the University of California, Los Angeles (UCLA) score and the Western Ontario McMaster Osteoarthritis Index (WOMAC) score, as well as patient satisfaction, return to sports activities (using a visual analog scale [VAS]) and frequency of factors limiting activity. Patients completed a questionnaire to determine the type, intensity and frequency of sports activities practiced pre- and postoperatively. RESULTS: The mean overall activity score immediately before surgery was not statistically different between the two groups (p=0.111). One year after surgery, the score was 17.9 in the RH group and 12.4 in the THA group (p=0.001). At last follow-up, the mean WOMAC score was 8.1 (range 0-73, S.D. 13.1) in the RH group and 9.8 (range 0-41, S.D. 10.9) in the THA group (p=0.409). The mean UCLA score was 7.17 in the RH group (range 2-10, S.D. 1.90) and 6.75 in the THA group (range 2-10, S.D. 1.71) (p=0.174). The mean satisfaction with return to sports activities as assessed on the VAS was 7.78 in the RH group and 7.43 in the THA group (p=0.313). DISCUSSION: The results of this study demonstrate that the degree and intensity of postoperative sports activities are greater in the RH group than in the THA group, although this difference was less pronounced than expected. The excellent joint stability after RH (big head effect) could be one of the main factors favoring a high activity level compared to conventional THA, by limiting the episodes of dislocation and increasing the suction effect between the joint components. It is nevertheless difficult to ascertain the long-term effect of intense sports activity on the fixation of osteo-integrated implants (cups) and cemented components (femoral stem).