Current state and future of joint replacements in the hip and knee

Oxford Hip Scores, Floor-Sitting Score Trajectories, and Postoperative Satisfaction Rates at 10 Years After Primary Total Hip Arthroplasty

BACKGROUND

Available evidence on outcomes at 5 years and beyond for total hip arthroplasty (THA) is mainly limited to patient-reported outcome measures (PROMs). This study documented the trajectory of functional measurement using the Oxford hip score (OHS) and floor-sitting posture in Japan for up to 10 years post-THA and investigated predictors of dissatisfaction at 10 years with THA.

METHODS

Patients scheduled for primary THA at a university hospital in Japan between 2003 and 2006 were enrolled in this prospective study. Overall, 826 preoperative participants were eligible for follow-up, with response rates ranging from 93.6% to 69.4% at each postoperative survey point. The OHS and floor-sitting scores were calculated using a self-administered questionnaire 6 times up to 10 years postoperatively. Patient satisfaction, including general surgery, walking ability, and activities of daily living (ADL), was assessed in the 10-year survey.

RESULTS

The linear mixed-effects model demonstrated a postoperative improvement, peaking at 7 years for OHS and 5 years earlier for the floor-sitting score. The postoperative overall surgical dissatisfaction at 10 years with THA was very low (3.2%). No predictors of surgical dissatisfaction were identified in the logistic regression analyses. Predictors of walking ability dissatisfaction were older age, men, and worse OHS at 1 year postoperatively. Predictors of ADL dissatisfaction were poorer preoperative and 1-year postoperative floor-sitting scores and 1-year postoperative OHS.

CONCLUSION

The floor-sitting score is a simple PROM suitable for the Japanese population; other populations would require a scale suitable for their lifestyles.

Femoral Bowing Increases Early Postoperative Stress around the Femoral Stem in Humans: A Finite Element Analysis

Background

This study aimed to clarify the characteristics of stress distribution caused by the placement of tapered wedge stems in bowed femurs compared with that in normal femurs and the effect of varus stem placement.

Methods

Models with normal and enhanced bowing were created from the right-side computed tomography data of a 17-year-old woman with the least bowing among 40 participants who underwent anterior cruciate ligament reconstruction or operative treatment for trauma in our hospital between January 2017 and May 2018. Finite element analysis was performed, assuming the tapered wedge stem was placed in the neutral and varus positions.

Results

Varus stem placement on a femur with normal bowing showed a deviation and increase of von Mises stresses in the medial femur. Stem placement on a bowed femur, even when placed in the neutral position, increased stress across the periprosthetic bone. When the stem was placed in the varus position, von Mises stress across the periprosthetic bone increased. Zone 7, with strong bowing, demonstrated 3.6-fold increased stress compared with normal femurs. The maximum tensile principal stress was greatest in zone 6 and increased in zones 3 and 4.

Conclusions

Surgeons should assess femoral bowing preoperatively and pay particular attention to intraoperative stem alignment for femurs with high bowing.

Hesperidin Methyl Chalcone Reduces the Arthritis Caused by TiO2 in Mice: Targeting Inflammation, Oxidative Stress, Cytokine Production, and Nociceptor Sensory Neuron Activation

Arthroplasty is an orthopedic surgical procedure that replaces a dysfunctional joint by an orthopedic prosthesis, thereby restoring joint function. Upon the use of the joint prosthesis, a wearing process begins, which releases components such as titanium dioxide (TiO₂) that trigger an immune response in the periprosthetic tissue, leading to arthritis, arthroplasty failure, and the need for revision. Flavonoids belong to a class of natural polyphenolic compounds that possess antioxidant and anti-inflammatory activities. Hesperidin methyl chalcone's (HMC) analgesic, anti-inflammatory, and antioxidant effects have been investigated in some models, but its activity against the arthritis caused by prosthesis-wearing molecules, such as TiO₂, has not been investigated. Mice were treated with HMC (100 mg/kg, intraperitoneally (i.p.)) 24 h after intra-articular injection of 3 mg/joint of TiO₂, which was used to induce chronic arthritis. HMC inhibited mechanical hyperalgesia, thermal hyperalgesia, joint edema, leukocyte recruitment, and oxidative stress in the knee joint (alterations in gp91^phox, GSH, superoxide anion, and lipid peroxidation) and in recruited leukocytes (total reactive oxygen species and GSH); reduced patellar proteoglycan degradation; and decreased pro-inflammatory cytokine production. HMC also reduced the activation of nociceptor-sensory TRPV1⁺ and TRPA1⁺ neurons. These effects occurred without renal, hepatic, or gastric damage. Thus, HMC reduces arthritis triggered by TiO₂, a component released upon wearing of prosthesis.

Antibiotic Susceptibility of Staphylococcus aureus Plankton and Biofilm Forms Isolated in Implant-Associated Infection

Comparison of activity of antibiotics against Staphylococcus aureus strains in their plankton form and in biofilms of varying maturity showed that the concentrations of antibiotics causing death of 90% S. aureus strains (MIC₉₀) in their plankton form was 0.07-2.80 μg/ml and significantly (p<0.05) differed from MIC₉₀ concentrations (3-245 μg/ml) for the strains in 24 and 48 h biofilms. MIC₉₀ value was affected by the degree of biofilm maturity: microbial resistance in 48-h biofilms for all analyzed antibiotics was significantly (p<0.05) higher than in 24-h biofilms.

A clinical review of robotic navigation in total knee arthroplasty: historical systems to modern design

Robotic-assisted total knee arthroplasty (RA-TKA) has shown improved reproducibility and precision in mechanical alignment restoration, with improvement in early functional outcomes and 90-day episode of care cost savings compared to conventional TKA in some studies. However, its value is still to be determined.

Current studies of RA-TKA systems are limited by short-term follow-up and significant heterogeneity of the available systems.

In today’s paradigm shift towards an increased emphasis on quality of care while curtailing costs, providing value-based care is the primary goal for healthcare systems and clinicians. As robotic technology continues to develop, longer-term studies evaluating implant survivorship and complications will determine whether the initial capital is offset by improved outcomes.

Future studies will have to determine the value of RA-TKA based on longer-term survivorships, patient-reported outcome measures, functional outcomes, and patient satisfaction measures.

Cite this article: EFORT Open Rev 2021;6:252-269. DOI: 10.1302/2058-5241.6.200071

Hydroxyapatite-poly(d,l-lactide) Nanografts. Synthesis and Characterization as Bone Cement Additives

This paper reports the creation of hydroxyapatite/polyester nanografts by “graft-from” polymerization of d,l-lactide with [Ca₅(OH)(PO₄)₃]₂ as the initiator and tin(II)-2-ethylhexanoate as the catalyst. Model polymerizations were performed with cyclooctanol as initiator to confirm the grafting on the surface of the hydroxyapatite nanocrystals. Polymers with the highest molecular mass (M_n) between 4250 Da (cyclooctanol) and 6100 Da (hydroxyapatite) were produced. In both cases the molecular mass distributions of the polymers formed were monomodal. The materials obtained were characterized by size-exclusion chromatography, NMR and FT-IR spectroscopy, and thermal methods. Their suitability as additives for commercial bone cement (Simplex P Speedset, Stryker Orthopaedics) has been confirmed by thermal analysis techniques and mechanical testing. The results obtained show that addition of the hydroxyapatite/ polyester nanografts improved both thermal and mechanical properties of the bone cement.

Promotion of Osseointegration between Implant and Bone Interface by Titanium Alloy Porous Scaffolds Prepared by 3D Printing

Titanium alloy prostheses have been widely used for the treatment of orthopedic diseases, in which the interconnected porosity and appropriate pore size are crucial for the osseointegration capacity. Three-dimensional (3D) printing technology provides an efficient method to construct prosthesis scaffolds with controllable internal and surface structure, but printing high-porosity (>60%) scaffolds with pore diameters below 300 μm as implants structures has not yet been studied. In this work, four types of titanium alloy scaffolds with interconnected porosity more than 70% were successfully prepared by selective laser melting (SLM). The actual mean pore sizes of cylindrical scaffolds are 542, 366, 202, and 134 μm. Through the in vitro characterization of the scaffolds, in vivo experiments, and mechanical experiments, it is concluded that as the scaffold pore diameter decreases, the titanium alloy scaffold with diameter of 202 μm has the strongest osseointegration ability and is also the most stable one with the surrounding bone. These findings provide a reference for the clinical pore-size design of porous scaffolds with optimal bone growth stability on the surface of the titanium alloy implant.

In vivo osseointegration of a randomized trabecular titanium structure obtained by an additive manufacturing technique

The additive manufacturing techniques (AM) are able to realize three-dimensional trabecular structures that mimic the trabecular structure of the bone. An in vivo study in sheep was carried out with the aim of assessing the bone response and the trend of osteointegration of a randomized trabecular titanium structure produced by the AM technique. In 6 sheep were implanted 84 specimens with a trabecular titanium structure (4 implants in the femur distal epiphysis; 4 implants in the tibial plate; 6 implants in the tibial shaft). Sheep were sacrificed at 3 postoperative time-points: 6 weeks, 10 weeks, 14 weeks. Histomorphometric analysis was performed for the evaluation of Bone Implant Contact, and Bone Ingrowth. A standard push-out test was used to analyze the mechanical characteristics of the bone-implant interface. The histomorphometric data and biomechanical tests showed a fast osseointegration of the specimens both in the cancellous and in the cortical bone. The quantitative analysis of osseointegration data in cancellous bone showed the percentage of the surface of the implant in direct contact with the regenerated bone matrix significantly improved from 28% at 6 weeks to 54% at 14 weeks. An early osseointegration occurred in cortical bone showing that 75% of surface of implant was in direct contact with regenerated bone after 6 weeks; this value increased to 85% after 14 weeks. Mechanical tests revealed an early improvement of mean peak load of implants at 10 weeks (4486 N ± 528 N) compared to values at 6 weeks (2516 N ± 910 N) confirming the high rate of progression of osseointegration in the cortical bone. The non-mineralized matrix followed an increasing process of mineralization almost completely after 14 weeks. The results of this study have showed a rapid osseointegration and excellent biocompatibility for a randomized trabecular titanium structure that should be confirmed by clinical investigations.

Patients return to work sooner after unicompartmental knee arthroplasty than after total knee arthroplasty

PURPOSE

It is not yet known if unicompartmental knee arthroplasty (UKA) patients are more likely to return to work sooner or have improved ability to work (i.e., workability) than total knee arthroplasty (TKA) patients. The following questions were addressed: patients were assessed to determine: (1) whether they returned to work sooner following UKA compared to TKA; (2) whether UKA patients had better WORQ function scores compared to TKA patients; and (3) if UKA patients have higher workability scores and greater satisfaction regarding workability than TKA patients.

METHODS

A multicenter retrospective cohort study was performed that included patients at least 2 years after having undergone either UKA or TKA surgery and on the condition that patients had been in work in the 2 years prior to surgery. Time period between stopping work and returning to work was assessed; the WORQ scores (0 = worst-100 = best) and the Work Ability Index (WAI = 0-10) and reported satisfaction with work ability.

RESULTS

UKA patients (n = 157, median 60 years, 51% male) were compared to TKA patients (n = 167, median 60 years, 49% male) (n.s.). Of the 157 UKA patients, 115 (73%) returned to work within 2 years compared to 121 (72%) of TKA patients (n.s.). More UKA patients return to work within 3 months (73% versus 48%) (p < 0.01). WORQ scores improved similarly in both groups. The WAI was also comparable between the groups. Dissatisfaction with workability was comparable (UKA 15% versus TKA 18% (n.s.).

CONCLUSION

TKA and UKA patients have similar WORQ, WAI, and satisfaction scores. However, in this study population, UKA patients to return to work after surgery significantly sooner than TKA patients, which improves their quality of life and allows them to participate actively in society. This information can help health care providers and patients weigh-up the pros and cons and choose the best treatment and timing for patients in the working population.

LEVEL OF EVIDENCE

III.

Kinematic parameter analysis and pilot clinical trial of dual-mobility semi-Knee prosthesis

BACKGROUND

To address large tumor-related defects and lower limb-length discrepancies during limb-salvage surgery in children with malignant tumors in the distal femur, a new custom-made dual-mobility semi-knee prosthesis (DMK) was made. This study aimed to provide a theory and references for further clinical applications of this prosthesis.

METHODS

Based on computed tomography data from adult knee joint samples, we used Mimics/Geomagic/Pro-E software and computer numerical control milling technology to design and manufacture the DMK. An in vitro study was carried out to examine the related kinematic parameters in the normal knee, total knee arthroplasty and DMK groups of cadaveric specimens. Then, a pilot clinical trial was performed.

RESULTS

The in vitro study revealed that the kinematics of the novel custom-made DMK are more similar to those of the normal knee than the total knee prosthesis. The pilot clinical trial showed that patients recovered well, and postoperative serial X-ray films did not demonstrate any disfigurations, loosening, dislocations or breaks in the prosthesis after a follow-up period ranging from 11 months to 5 years.

CONCLUSION

The DMK is a novel concept and method for the treatment of malignant tumors in the distal femur in children, and the device used for ligament reattachment provides a solution for knee ligament reconstruction. However, DMK might be replaced by a total knee prosthesis after epiphyseal closure, because of incompatibility of tibial plateau with the prosthesis.

Enhanced antibacterial properties of orthopedic implants by titanium nanotube surface modification: a review of current techniques

Prosthesis-associated infections are one of the main causes of implant failure; thus it is important to enhance the long-term antibacterial ability of orthopedic implants. Titanium dioxide nanotubes (TNTs) are biomaterials with good physicochemical properties and biocompatibility. Owing to their inherent antibacterial and drug-loading ability, the antibacterial application of TNTs has received increasing attention. In this review, the process of TNT anodizing fabrication is summarized. Also, the mechanism and the influencing factors of the antibacterial property of bare TNTs are explored. Furthermore, different antibacterial strategies for carrying drugs, as well as modifications to prolong the antibacterial effect and reduce drug-related toxicity are discussed. In addition, antibacterial systems based on TNTs that can automatically respond to infection are introduced. Finally, the currently faced problems are reviewed and potential solutions are proposed. This review provides new insight on TNT fabrication and summarizes the most advanced antibacterial strategies involving TNTs for the enhancement of long-term antibacterial ability and reduction of toxicity.

Vascular endothelial growth factor pathway promotes osseointegration and CD31hiEMCNhi endothelium expansion in a mouse tibial implant model: an animal study

AIMS

It is increasingly appreciated that coordinated regulation of angiogenesis and osteogenesis is needed for bone formation. How this regulation is achieved during peri-implant bone healing, such as osseointegration, is largely unclear. This study examined the relationship between angiogenesis and osteogenesis in a unique model of osseointegration of a mouse tibial implant by pharmacologically blocking the vascular endothelial growth factor (VEGF) pathway.

MATERIALS AND METHODS

An implant was inserted into the right tibia of 16-week-old female C57BL/6 mice (n = 38). Mice received anti-VEGF receptor-1 (VEGFR-1) antibody (25 mg/kg) and VEGF receptor-2 (VEGFR-2) antibody (25 mg/kg; n = 19) or an isotype control antibody (n = 19). Flow cytometric (n = 4/group) and immunofluorescent (n = 3/group) analyses were performed at two weeks post-implantation to detect the distribution and density of CD31^hiEMCN^hi endothelium. RNA sequencing analysis was performed using sorted CD31^hiEMCN^hi endothelial cells (n = 2/group). Osteoblast lineage cells expressing osterix (OSX) and osteopontin (OPN) were also detected with immunofluorescence. Mechanical pull-out testing (n = 12/group) was used at four weeks post-implantation to determine the strength of the bone-implant interface. After pull-out testing, the tissue attached to the implant surface was harvested. Whole mount immunofluorescent staining of OSX and OPN was performed to determine the amount of osteoblast lineage cells.

RESULTS

Flow cytometry revealed that anti-VEGFR treatment decreased CD31^hiEMCN^hi vascular endothelium in the peri-implant bone versus controls at two weeks post-implantation. This was confirmed by the decrease of CD31 and endomucin (EMCN) double-positive cells detected with immunofluorescence. In addition, treated mice had more OPN-positive cells in both peri-implant bone and tissue on the implant surface at two weeks and four weeks, respectively. More OSX-positive cells were present in peri-implant bone at two weeks. More importantly, anti-VEGFR treatment decreased the maximum load of pull-out testing compared with the control.

CONCLUSION

VEGF pathway controls the coupling of angiogenesis and osteogenesis in orthopaedic implant osseointegration by affecting the formation of CD31^hiEMCN^hi endothelium. Cite this article: Bone Joint J 2019;101-B(7 Supple C):108-114.

Biofunctionalized peptide nanofiber-based composite scaffolds for bone regeneration

Bone tissue had moderate self-healing capabilities, but biomaterial scaffolds were required for the repair of some defects such as large bone defects. Peptide nanofiber scaffolds demonstrated important potential in regenerative medicine. Functional modification and controlled release of signal molecules were two significant approaches to increase the bioactivity of biofunctionalized peptide nanofiber scaffolds, but peptide scaffolds were limited by insufficient mechanical strength. Thus, it was necessary to combine peptide scaffolds with other materials including polymers, hydroxyapatite, demineralized bone matrix (DBM) and metal materials based on the requirement of different bone defects. As the development of peptide-based composite scaffolds continued to evolve, ultimate translation to the clinical environment may allow for improved therapeutic outcomes for bone repair.

Clinical Evaluation of Efficacy and Performance of All-Poly Tibial Freedom® Total Knee System for Treating Osteoarthritis Patients: Three-Year Follow Up Study

Introduction

Advancement in technology in terms of design and building materials has made Total Knee Replacement (TKR) a highly effective, safe, and predictable orthopedic procedure.

Aim

To review the clinical outcomes for efficacy and performance of Freedom Total Knee System for the management of Osteoarthritis (OA), at a minimum of three years follow up.

Materials and Methods

For this retrospective, post-marketing study, clinical data of patients treated with Freedom Total Knee System was retrieved from the clinical records after approval from the Institutional Ethics Committee . All the patients above the age of 18 years who completed at least three years after TKR were observed for the study purpose. Patients treated for OA were included while the patients who received the implant for treatment of rheumatoid arthritis and traumatic injury were excluded. Factors such as aseptic loosening, implant failure, and need for revision surgery were observed to evaluate implant performance. Cases were recruited for clinical assessment of primary efficacy endpoint in terms of post-surgery maximun range of motion. Secondary efficacy endpoint was to determine the clinical and social quality of life as per the American Knee Society Score (AKSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and stiffness scores.

Results

A total of 158 patients who had 191 TKR were observed for performance. The mean age of the patients was 67.67 years; mean BMI was 28.97±3.33, and the group comprised of 43% men and 57% women. Telephonic follow up at three years of 158 patients identified that none of them required revision surgery or had aseptic loosening suggesting excellent performance. Final clinical follow up at three years was available for only 35 patients (41 knee implants). The range of motion significantly improved from preoperative 104°±5.67° (range, 85°-119°) to 119.8°±11.05° (98°-123°) at follow-up (p<0.05). There was a significant improvement in clinical and functional AKSS score and WOMAC score at follow-up.

Conclusion

The evaluation of Freedom Total Knee System for TKR in treating OA, at a minimum of three years follow up showed excellent outcomes in terms of performance, range of motion, reduced postoperative stiffness and pain, and improved functionality.

Patient Satisfaction After Total Knee Arthroplasty: A Realistic or Imaginary Goal?

This article summarizes the current literature regarding patient satisfaction after total knee arthroplasty. In 10% to 15% of cases, the operation has not met the patients' expectations. The causes of this dissatisfaction are multifactorial, and include patient-related factors, details related to the surgical procedure and prosthesis chosen, perioperative factors, and factors associated with nursing and general medical care. However, surgeons must bear the brunt of patients' dissatisfaction. This dissatisfaction erodes the doctor-patient relationship, and may have implications in an emerging health care economy in which doctors and hospitals are reimbursed based on both clinical outcome and patient satisfaction.

Immunological Responses to Total Hip Arthroplasty

The use of total hip arthroplasties (THA) has been continuously rising to meet the demands of the increasingly ageing population. To date, this procedure has been highly successful in relieving pain and restoring the functionality of patients’ joints, and has significantly improved their quality of life. However, these implants are expected to eventually fail after 15–25 years in situ due to slow progressive inflammatory responses at the bone-implant interface. Such inflammatory responses are primarily mediated by immune cells such as macrophages, triggered by implant wear particles. As a result, aseptic loosening is the main cause for revision surgery over the mid and long-term and is responsible for more than 70% of hip revisions. In some patients with a metal-on-metal (MoM) implant, metallic implant wear particles can give rise to metal sensitivity. Therefore, engineering biomaterials, which are immunologically inert or support the healing process, require an in-depth understanding of the host inflammatory and wound-healing response to implanted materials. This review discusses the immunological response initiated by biomaterials extensively used in THA, ultra-high-molecular-weight polyethylene (UHMWPE), cobalt chromium (CoCr), and alumina ceramics. The biological responses of these biomaterials in bulk and particulate forms are also discussed. In conclusion, the immunological responses to bulk and particulate biomaterials vary greatly depending on the implant material types, the size of particulate and its volume, and where the response to bulk forms of differing biomaterials are relatively acute and similar, while wear particles can initiate a variety of responses such as osteolysis, metal sensitivity, and so on.

BMP-7 ameliorates cobalt alloy particle-induced inflammation by suppressing Th17 responses

Metal wear debris has been shown to activate an aseptic osteolytic process that causes failure in total joint arthroplasty (TJA). This osteolysis is characterized by a proinflammatory, self-propagating immune response involving primarily macrophages, dendritic cells, and activated osteoclasts, as well as T cells and B cells. The human bone morphogenic protein (BMP)-7, on the other hand, was shown to promote osteoblast survival, and reversed the downregulation of anabolic Smad proteins and Runx2 following cobalt injury. Therefore, we investigated the effect and mechanism of BMP-7 on the proinflammatory immune responses in osteoarthritis patients with previous TJA. Cobalt-treated monocytes/macrophages presented significantly elevated levels of interleukin 6 (IL-6) and tumor necrosis factor (TNF), both of which were suppressed by the addition of exogenous BMP-7. In patients with TJA, the serum BMP-7 level was inversely associated with the level of IL-6 and TNF secreted by monocytes/macrophages. Cobalt-treated monocytes/macrophages effectively supported Th17 inflammation, by an IL-6-dependent but not TNF-dependent mechanism. BMP-7, however, significantly suppressed cobalt-induced Th17 inflammation. In patients with TJA, the risk of osteolysis development was positively associated with the frequency of Th17 cells and negatively associated with the level of BMP-7. Together, these results demonstrated that BMP-7 could serve as a therapeutic agent in treating patients with metal wear debris-induced inflammation.

Poly (lactic acid)-based biomaterials for orthopaedic regenerative engineering

Regenerative engineering converges tissue engineering, advanced materials science, stem cell science, and developmental biology to regenerate complex tissues such as whole limbs. Regenerative engineering scaffolds provide mechanical support and nanoscale control over architecture, topography, and biochemical cues to influence cellular outcome. In this regard, poly (lactic acid) (PLA)-based biomaterials may be considered as a gold standard for many orthopaedic regenerative engineering applications because of their versatility in fabrication, biodegradability, and compatibility with biomolecules and cells. Here we discuss recent developments in PLA-based biomaterials with respect to processability and current applications in the clinical and research settings for bone, ligament, meniscus, and cartilage regeneration.

Selective etching of injection molded zirconia-toughened alumina: Towards osseointegrated and antibacterial ceramic implants

Due to their outstanding mechanical properties and excellent biocompatibility, zirconia-toughened alumina (ZTA) ceramics have become the gold standard in orthopedics for the fabrication of ceramic bearing components over the last decade. However, ZTA is bioinert, which hampers its implantation in direct contact with bone. Furthermore, periprosthetic joint infections are now the leading cause of failure for joint arthroplasty prostheses. To address both issues, an improved surface design is required: a controlled micro- and nano-roughness can promote osseointegration and limit bacterial adhesion whereas surface porosity allows loading and delivery of antibacterial compounds. In this work, we developed an integrated strategy aiming to provide both osseointegrative and antibacterial properties to ZTA surfaces. The micro-topography was controlled by injection molding. Meanwhile a novel process involving the selective dissolution of zirconia (selective etching) was used to produce nano-roughness and interconnected nanoporosity. Potential utilization of the porosity for loading and delivery of antibiotic molecules was demonstrated, and the impact of selective etching on mechanical properties and hydrothermal stability was shown to be limited. The combination of injection molding and selective etching thus appears promising for fabricating a new generation of ZTA components implantable in direct contact with bone.

STATEMENT OF SIGNIFICANCE

Zirconia-toughened alumina (ZTA) is the current gold standard for the fabrication of orthopedic ceramic components. In the present work, we propose an innovative strategy to provide both osseointegrative and antibacterial properties to ZTA surfaces: we demonstrate that injection molding allows a flexible design of surface micro-topography and can be combined with selective etching, a novel process that induces nano-roughness and surface interconnected porosity without the need for coating, avoiding reliability issues. These surface modifications have the potential to improve osseointegration. Furthermore, our results show that the porosity can be used for drug delivery and suggest that the etched surface could reduce bacterial adhesion.

Biomaterial strategies for engineering implants for enhanced osseointegration and bone repair

Bone tissue has a remarkable ability to regenerate and heal itself. However, large bone defects and complex fractures still present a significant challenge to the medical community. Current treatments center on metal implants for structural and mechanical support and auto- or allo-grafts to substitute long bone defects. Metal implants are associated with several complications such as implant loosening and infections. Bone grafts suffer from donor site morbidity, reduced bioactivity, and risk of pathogen transmission. Surgical implants can be modified to provide vital biological cues, growth factors and cells in order to improve osseointegration and repair of bone defects. Here we review strategies and technologies to engineer metal surfaces to promote osseointegration with the host tissue. We also discuss strategies for modifying implants for cell adhesion and bone growth via integrin signaling and growth factor and cytokine delivery for bone defect repair.

Analgesia for total knee arthroplasty: a meta-analysis comparing local infiltration and femoral nerve block

Patients frequently experience postoperative pain after a total knee arthroplasty; such pain is always challenging to treat and may delay the patient's recovery. It is unclear whether local infiltration or a femoral nerve block offers a better analgesic effect after total knee arthroplasty.We performed a systematic review and meta-analysis of randomized controlled trials to compare local infiltration with a femoral nerve block in patients who underwent a primary unilateral total knee arthroplasty. We searched Pubmed, EMBASE, and the Cochrane Library through December 2014. Two reviewers scanned abstracts and extracted data. The data collected included numeric rating scale values for pain at rest and pain upon movement and opioid consumption in the first 24 hours. Mean differences with 95% confidence intervals were calculated for each end point. A sensitivity analysis was conducted to evaluate potential sources of heterogeneity.While the numeric rating scale values for pain upon movement (MD-0.62; 95%CI: -1.13 to -0.12; p=0.02) in the first 24 hours differed significantly between the patients who received local infiltration and those who received a femoral nerve block, there were no differences in the numeric rating scale results for pain at rest (MD-0.42; 95%CI:-1.32 to 0.47; p=0.35) or opioid consumption (MD 2.92; 95%CI:-1.32 to 7.16; p=0.18) in the first 24 hours.Local infiltration and femoral nerve block showed no significant differences in pain intensity at rest or opioid consumption after total knee arthroplasty, but the femoral nerve block was associated with reduced pain upon movement.

Wear testing of total hip replacements under severe conditions

Controlled wear testing of total hip replacements in hip joint simulators is a well-established and powerful method, giving an extensive prediction of the long-term clinical performance. To understand the wear behavior of a bearing and its limits under in vivo conditions, testing scenarios should be designed as physiologically as possible. Currently, the ISO standard protocol 14242 is the most common preclinical testing procedure for total hip replacements, based on a simplified gait cycle for normal walking conditions. However, in recent years, wear patterns have increasingly been observed on retrievals that cannot be replicated by the current standard. The purpose of this study is to review the severe testing conditions that enable the generation of clinically relevant wear rates and phenomena. These conditions include changes in loading and activity, third-body wear, surface topography, edge wear and the role of aging of the bearing materials.

A resorbable antibiotic-eluting polymer composite bone void filler for perioperative infection prevention in a rabbit radial defect model

Nearly 1.3 million total joint replacement procedures are performed in the United States annually, with numbers projected to rise exponentially in the coming decades. Although finite infection rates for these procedures remain consistently low, device-related infections represent a significant cause of implant failure, requiring secondary or revision procedures. Revision procedures manifest several-fold higher infection recurrence rates. Importantly, many revision surgeries, infected or not, require bone void fillers to support the host bone and provide a sufficient tissue bed for new hardware placement. Antibiotic-eluting bone void fillers (ABVF), providing both osteoconductive and antimicrobial properties, represent one approach for reducing rates of orthopedic device-related infections. Using a solvent-free, molten-cast process, a polymer-controlled antibiotic-eluting calcium carbonate hydroxyapatite (HAP) ceramic composite BVF (ABVF) was fabricated, characterized, and evaluated in vivo using a bacterial challenge in a rabbit radial defect window model. ABVF loaded with tobramycin eliminated the infectious burden in rabbits challenged with a clinically relevant strain of Staphylococcus aureus (inoculum as high as 10⁷ CFU). Histological, microbiological, and radiographic methods were used to detail the effects of ABVF on microbial challenge to host bone after 8 weeks in vivo. In contrast to the HAP/BVF controls, which provided no antibiotic protection and required euthanasia 3 weeks post-operatively, tobramycin-releasing ABVF animals showed no signs of infection (clinical, microbiological, or radiographic) when euthanized at the 8-week study endpoint. ABVF sites did exhibit fibrous encapsulation around the implant at 8 weeks. Local antibiotic release from ABVF to orthopedic sites requiring bone void fillers eliminated the periprosthetic bacterial challenge in this 8-week in vivo study, confirming previous in vitro results.

Timeframe for return to driving for patients with minimally invasive knee arthroplasty is associated with knee performance on functional tests

Background

This study hopes to establish the timeframe for a safe return to driving under different speed conditions for patients after minimally invasive total knee arthroplasty and further explores how well various kinds of functional tests on knee performance can predict the patients’ braking ability.

Methods

14 patients with right knee osteoarthritis were included in the present study and instructed to perform three simulated driving tasks at preoperative, 2 weeks postoperative and 4 weeks postoperative.

Results

The results showed that the total braking time at 4 week postoperative has attained the preoperative level at the driving speed 50 and 70 km/hr but not at the driving speed 90 km/hr. It had significantly improving in knee reaction time and maximum isometric force at 4 weeks postoperative. Besides, there was a moderate to high correlation between the scores of the step counts and the total braking time.

Conclusions

Summary, it is recommended that driving may be resumed 4 weeks after a right knee replacement but had to drive at low or moderate speed and the best predictor of safety driving is step counts.

A reliable, valid and responsive questionnaire to score the impact of knee complaints on work following total knee arthroplasty: the WORQ

The Work, Osteoarthritis or joint-Replacement Questionnaire (WORQ) was developed to assess physical difficulty experienced in work before or following total knee arthroplasty (TKA). Thirteen questions were designed. The WORQ was tested for internal consistency by factor analysis, internal reliability (Crohnbach's α), and construct validity. A test-retest reproducibility was performed for analyzing standard error of measurement (SEM agreement), reliability (ICC) and smallest detectable change (SDC) in individuals and groups. Lastly responsiveness (standardized response means [SRM]), floor and ceiling effects and interpretability (minimal important change [MIC]) were analyzed. It is shown that the WORQ is a reliable, valid and responsive questionnaire that can be used to evaluate the impact of knee complaints following TKA on patients' ability to work.

Total knee arthroplasty and the unforeseen impact on return to work: a cross-sectional multicenter survey

The number of patients receiving a TKA during working life is increasing but little is known about the impact of TKA on patients' reintegration into the workplace. In this cross-sectional survey it was found that 173 of 480 responders worked within 2 years prior to surgery. Sixty-three percent of the working patients stopped within two weeks prior to surgery and 102 patients returned within 6 months. One third never returned to work. Activities that most improved were operating foot pedals, operating vehicles, standing and walking on level terrain. Activities that least improved were kneeling, crouching and clambering. Fifty patients scored 5 or less on the Work Ability Index. Thirty patients were dissatisfied. TKA significantly, but unequally, reduces difficulties in carrying out knee-burdening work activities.

Stro-1-positive BMSCs predict postoperative periprosthetic bone mineral density outcomes in uncemented total hip arthroplasty patients

Background

Bone marrow cell profiles are variable after total hip arthroplasty (THA), including variable levels of Stro-1⁺ and bone morphogenetic protein receptor (BMPRs)⁺ cells. We investigated the impact of bone marrow cell profiles on changes in periprosthetic bone mineral density (BMD) in uncemented THA patients.

Material/Methods

Bone marrow aspirates were collected from the metaphyseal region of discarded femoral heads from 24 consecutive THA patients (12 men and 12 women; mean age 66.7±11.0 years; range 52–87 years) treated from March 2009 to March 2011 at a single facility. Perioperative proportions of Stro-1⁺ and BMPR⁺ cells in femoral heads were assessed by flow cytometry. Follow-up examined the proximal femur Gruen zones R1 and R7 at 1 week and at 3, 6, and 12 months after THA, using dual-energy X-ray absorptiometry. Associations between BMD loss and age, gender, BMPRs⁺, and Stro-1⁺ were analyzed.

Results

At 3 months, R1 and R7 BMD decreased by 4.4% and 6.4%, respectively (P<0.05). At 12 months, the overall BMD decreases in R1 and R7 were 10.2% and 1%, respectively (P<0.05). Higher Stro-1⁺ cells proportion predicted R7 BMD increases at all time points (P<0.05) and R1 BMD increases at 6 and 12 months (P<0.05). BMPR1a⁺ proportion was associated with BMD increases at 6 months in the R1 region. BMPR2⁺ was not significantly associated with BMD (P>0.05).

Conclusions

Elevated Stro-1⁺ bone marrow cell profile may be a useful prognostic indicator for uncemented THA patients.

Toll-like receptors-2 and 4 are overexpressed in an experimental model of particle-induced osteolysis

Aseptic loosening secondary to particle-associated periprosthetic osteolysis remains a major cause of failure of total joint replacements (TJR) in the mid- and long term. As sentinels of the innate immune system, macrophages are central to the recognition and initiation of the inflammatory cascade, which results in the activation of bone resorbing osteoclasts. Toll-like receptors (TLRs) are involved in the recognition of pathogen-associated molecular patterns and danger-associated molecular patterns. Experimentally, polymethylmethacrylate and polyethylene (PE) particles have been shown to activate macrophages via the TLR pathway. The specific TLRs involved in PE particle-induced osteolysis remain largely unknown. We hypothesized that TLR-2, -4, and -9 mediated responses play a critical role in the development of PE wear particle-induced osteolysis in the murine calvarium model. To test this hypothesis, we first demonstrated that PE particles caused observable osteolysis, visible by microCT and bone histomorphometry when the particles were applied to the calvarium of C57BL/6 mice. The number of TRAP positive osteoclasts was significantly greater in the PE-treated group when compared to the control group without particles. Finally, using immunohistochemistry, TLR-2 and TLR-4 were highly expressed in PE particle-induced osteolytic lesions, whereas TLR-9 was downregulated. TLR-2 and -4 may represent novel therapeutic targets for prevention of wear particle-induced osteolysis and accompanying TJR failure.

Coaxial PCL/PVA electrospun nanofibers: osseointegration enhancer and controlled drug release device

The failure of prosthesis after total joint replacement is mainly due to dysfunctional osseointegration and implant infection. There is a critical need for orthopedic implants that promote rapid osseointegration and prevent bacterial colonization, particularly when placed in bone compromised by disease or physiology of the patients. The aim of this study was to fabricate a novel coaxial electrospun polycaprolactone (PCL)/polyvinyl alcohol (PVA) core-sheath nanofiber (NF) blended with both hydroxyapatite nanorods (HA) and type I collagen (Col) (PCL(Col)/PVA(HA)). Doxycycline (Doxy) and dexamethasone (Dex) were successfully incorporated into the PCL(Col)/PVA(HA) NFs for controlled release. The morphology, surface hydrophilicity and mechanical properties of the PCL/PVA NF mats were analyzed by scanning electron microscopy, water contact angle and atomic force microscopy. The PCL(Col)/PVA(HA) NFs are biocompatible and enhance the adhesion and proliferation of murine pre-osteoblastic MC3T3 cells. The release of Doxy and Dex from coaxial PCL(Col)/PVA(HA) NFs showed more controlled release compared with the blended NFs. Using an ex vivo porcine bone implantation model we found that the PCL(Col)/PVA(HA) NFs bind firmly on the titanium rod surface and the NFs coating remained intact on the surface of titanium rods after pullout. No disruption or delamination was observed after the pullout test. These findings indicate that PCL(Col)/PVA(HA) NFs encapsulating drugs have great potential in enhancing implant osseointegration and preventing implant infection.

Local inhibition of 5-lipoxygenase enhances bone formation in a rat model

Objectives

Recent studies have shown that modulating inflammation-related lipid signalling after a bone fracture can accelerate healing in animal models. Specifically, decreasing 5-lipoxygenase (5-LO) activity during fracture healing increases cyclooxygenase-2 (COX-2) expression in the fracture callus, accelerates chondrogenesis and decreases healing time. In this study, we test the hypothesis that 5-LO inhibition will increase direct osteogenesis.

Methods

Bilateral, unicortical femoral defects were used in rats to measure the effects of local 5-LO inhibition on direct osteogenesis. The defect sites were filled with a polycaprolactone (PCL) scaffold containing 5-LO inhibitor (A-79175) at three dose levels, scaffold with drug carrier, or scaffold only. Drug release was assessed in vitro. Osteogenesis was assessed by micro-CT and histology at two endpoints of ten and 30 days.

Results

Using micro-CT, we found that A-79175, a 5-LO inhibitor, increased bone formation in an apparent dose-related manner.

Conclusions

These results indicate that 5-LO inhibition could be used therapeutically to enhance treatments that require the direct formation of bone.

Hip resurfacing: not your average hip replacement

Hip resurfacing (HR) has become a widely used surgical intervention for younger patients requiring hip joint arthroplasty. While case reports have been published describing rehabilitation programs following HR, there has yet to be established rehabilitation guidelines. Through experience and clinical reasoning, the following guidelines have been developed based on the patients at the Hospital for Special Surgery. The demographics of the typical HR patient, along with the surgical process are described. Current published literature reporting rehabilitation for patients with arthritic hip pathologies has been incorporated into the guidelines and is presented. The guidelines are divided into three phases, with goals for each phase explained. A progression through phases by way of reaching certain milestones and goals is advocated.

Does a prefabricated gentamicin-impregnated, load-bearing spacer control periprosthetic hip infection?

INTRODUCTION

Treating deep infection following THA has been a challenge. While the standard treatment has remained a two-stage revision, spacer designs, incorporated antibiotics, and concentrations have varied. Since control of infection may relate to choice and concentration of antibiotics, it is important to report rates of control from various spacers.

QUESTIONS/PURPOSES

We therefore determined (1) the rate of infection control and (2) complications associated with a prefabricated, load-bearing, gentamicin-impregnated hip spacer in treating periprosthetic infections of the hip.

METHODS

We retrospectively reviewed 33 patients with periprosthetic THA infections treated with a prefabricated, partial load-bearing, gentamicin-impregnated hemiarthroplasty spacer. Thirty of the 33 patients underwent second stage reimplantation after a mean 15 weeks. We collected patient demographic data, laboratory values, infecting organism, size of spacer mold, antibiotic selection, complications, and infection control rates from two academic centers. Recurrent infection at last followup was determined by the presence of physical symptoms or signs or elevated serologic tests. The minimum followup was 24 months (mean, 43 months; range, 24-70 months).

RESULTS

Twenty-eight of the 30 patients who underwent reimplantation remained infection-free at last followup: one patient became reinfected with a different organism secondary to wound problems; one became reinfected with the same organism, but was restaged with the mold used in this study, reimplanted, and subsequently remained free of infection. Two of the 33 patients had persistently elevated inflammatory markers at the completion of their first stage and were restaged with this mold; both underwent reimplantation and remained free of infection at latest followup. One of the 33 patients was satisfied and ambulatory with their spacer mold. There were no major complications.

CONCLUSION

Our data supported the use of a partial load-bearing, gentamicin-impregnated hemiarthroplasty spacer in treating deep periprosthetic THA infections.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Mesenchymal stem cell transplantation to promote bone healing

An overall decline in the availability of osteogenic precursor cells and growth factors in the bone marrow microenvironment have been associated with impaired bone formation and osteopenia in humans. The objective of the current study was to determine if transplantation of mesenchymal stromal cells (MSC) from a healthy, young donor mouse into an osteopenic recipient mouse could enhance osseointegration of a femoral implant. MSC harvested from normal young adult mice differentiated into bone forming osteoblasts when cultured on implant grade titanium surfaces ex vivo and promoted bone formation around titanium-coated rods implanted in the femoral canal of osteopenic recipient mice. Micro computed tomographic imaging and histological analyses showed more, better quality, bone in the femur that received the MSC transplant compared with the contra-lateral control femur that received carrier alone. These results provide pre-clinical evidence that MSC transplantation promotes peri-implant bone regeneration and suggest the approach could be used in a clinical setting to enhance bone regeneration and healing in patients with poor quality bone.

Factors influencing range of motion after total knee arthroplasty

BACKGROUND

The range of motion after a total knee arthroplasty is an important clinical outcome affecting the life of the patient. The aim of this study was to determine the most important factors influencing the postoperative knee flexion in Tehran, Iran.

METHODS

Between July 2007 and January 2009, on 95 cases of total knee joint replacement (89 patients), who were followed for 1 year postoperatively, the risk factors were assessed. Patient demographics (sex, age, body mass index, previous surgery, preoperative Knee Society System score, and preoperative range of motion) as well as radiographic measurement for preoperative tibiofemoral angle were statistically analyzed and the probable predictors entered into a linear regression model.

RESULTS

Univariate analysis showed that age, preoperative flexion angle, preoperative flexion arc and preoperative tibiofemoral angle had significant correlation with the postoperative flexion angle. The linear regression model on the other hand revealed that preoperative flexion angle and preoperative tibiofemoral angle were the true predictors of the postoperative flexion angle with coefficients of 0.64 and -0.21, respectively.

CONCLUSION

Better range of motion before the surgery with a lower tibiofemoral varus/valgus angle were more likely to result in a better range of motion after the surgery, suggesting that an appropriate timing for the surgery when the knee joint is still in a better function can lead to a better outcome.

Minimally invasive total hip and knee arthroplasty-implications for the elderly patient

Overall, it can be concluded that because of the aging society, an increasing number of elderly people will be undergoing total joint arthroplasty. These elderly patients have an increased risk for serious complications after primary THA or TKA. However, the overall complication rates remain low. The use of MIS total joint arthroplasty is also increasing, although its risks and benefits are still an ongoing issue of debate in the orthopedic community. MIS total joint arthroplasty aims at decreasing the surgical incision and minimizing damage to the underlying soft tissue to accelerate postoperative recovery and an earlier return to normal function. A critical look at the literature on MIS shows that the term minimally invasive is often used for a conventional total joint arthroplasty performed through a smaller skin incision. Research has shown promising results of using MIS in elderly patients; it seems that compared with younger patients, elderly patients benefit more from a minimally invasive approach.

Does lateral release change patellofemoral forces and pressures?: a pilot study

BACKGROUND

One complication of TKA is postoperative anterior knee pain. Balancing retinacular tissue tension to improve patellar tracking is essential in preventing pain. Lateral release might help balance tension although the quantitative changes in patellofemoral force and pressure differentials after lateral release are unknown.

QUESTIONS/PURPOSES

We asked if there are differences in patellofemoral forces and pressures for knees resurfaced with standard and gender-specific components and whether lateral release changes these differentials.

METHODS

We studied six fresh-frozen cadaver knees with native knees and knees that had TKAs with patellofemoral resurfacing using traditional and gender-specific components. The knees were taken through passive ROM, and the means for medial and lateral peak pressure and maximum force were calculated before and after a lateral release was performed.

RESULTS

In traditional resurfaced knees, lateral peak pressure was greater than medial peak pressure by 727.6 ± 550.0 kPa and lateral maximum force was greater than medial maximum force by 29.6 ± 15.9 N. Lateral release decreased the pressure (71.4 ± 826.0 kPa) and force (10.0 ± 32.1 N) differentials in the traditional but not in the gender-specific design. In gender-specific resurfaced knees, lateral peak pressure was greater than medial peak pressure by 158.7 ± 360.0 kPa and lateral maximum force was greater than medial maximum force by 15.5 ± 10.4 N. Lateral release increased the pressure (285.7 ± 565.0 kPa) and force (16.8 ± 10.8 N) differentials.

CONCLUSIONS

Our preliminary data suggest lateral release is more effective in reducing peak pressure and maximum force differentials in knees resurfaced with traditional standard components than with gender-specific components.

CLINICAL RELEVANCE

The lateral release technique might help with tissue balancing when using standard components in TKA.

Cementless revision TKA with bone grafting of osseous defects restores bone stock with a low revision rate at 4 to 10 years

BACKGROUND

Addressing bone loss in revision TKA is challenging despite the array of options to reconstruct the deficient bone. Biologic reconstruction using morselized loosely-packed bone graft potentially allows for augmentation of residual bone stock while offering physiologic load transfer. However it is unclear whether the reconstructions are durable.

QUESTIONS/PURPOSES

We therefore sought to determine (1) survivorship and complications, (2) function, and (3) radiographic findings of cementless revision TKA in combination with loosely-packed morselized bone graft to reconstruct osseous defects at revision TKA.

PATIENTS AND METHODS

We retrospectively reviewed 56 patients who had undergone revision TKAs using cementless long-stemmed components in combination with morselized loose bone graft at our institution. There were 26 men and 30 women with a mean age of 68.3 years (range, 56-89 years). Patients were followed to assess symptoms and function and to detect radiographic loosening, component migration, and graft incorporation. The minimum followup was 4 years (mean, 7.3 years; range, 4-10 years).

RESULTS

Cumulative prosthesis survival, with revision as an end point, was 98% at 10 years. The mean Oxford Knee Scores improved from 21 (36%) preoperatively to 41 (68%) at final followup. Five patients (9%) had reoperations for complications.

CONCLUSIONS

Our observations suggest this technique is reproducible and obviates the need for excessive bone resection, use of large metal augments, mass allografts, or custom prostheses. It allows for bone stock to be reconstructed reliably with durable midterm component fixation.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Warfarin prophylaxis in patients after total knee or hip arthroplasty--international normalized ratio patterns and venous thromboembolism

OBJECTIVE

Warfarin is frequently used for the prevention of venous thromboembolism (VTE) after total hip or knee arthroplasty (THA/TKA). The current study was conducted to determine the association between international normalized ratio (INR) levels and VTE outcomes.

METHODS

Patients who received warfarin following THA/TKA were followed for up to 90 days using an electronic health record database. INR measurements were categorized based on American College of Chest Physicians (ACCP) guidelines. Cox proportional hazards models were used to compare the risk of VTE between patients with INR levels below and within the ACCP-recommended range in patients with ≥2 available INR level measurements.

RESULTS

On or after Day 5, 33.3% and 28.6% of INR levels fell within the ACCP-recommended range for THA and TKA, respectively. VTE was diagnosed in 3% of each cohort. INR levels varied over time and were frequently below the ACCP-recommended range. Below-range INR levels were associated with greater risk of VTE in both THA (hazard ratio [HR]: 5.29; 95% CI: 2.64-10.61) and TKA (HR: 4.64; 95% CI: 2.59-8.29).

CONCLUSIONS

In the current study, the majority of patients had INR levels below the ACCP-recommended range of 2.0-3.0 during warfarin exposure following orthopedic surgery. INR levels below 2.0 were associated with a four- to five-fold increase in the risk of VTE.

Mediators of the inflammatory response to joint replacement devices

Joint replacement surgery is one of the success stories of modern medicine, restoring mobility, diminishing pain and improving the overall quality of life for millions of people. Unfortunately, wear of these prostheses over time generates debris, which activates an innate immune response that can ultimately lead to periprosthetic resorption of bone (osteolysis) and failure of the implant. Over the past decade, the biological interactions between the particulate debris from various implant materials and the immune system have begun to be better understood. The wear debris induces a multifaceted immune response encompassing the generation of reactive oxygen species and damage-associated molecular patterns, Toll-like receptor signaling and NALP3 inflammasome activation. Acting alone or in concert, these events generate chronic inflammation, periprosthetic bone loss and decreased osteointegration that ultimately leads to implant failure.

Comparison of the reliability, responsiveness, and construct validity of 4 different questionnaires for evaluating outcomes after total knee arthroplasty

The study aimed to compare the reliability, responsiveness and construct convergent validity of four questionnaires (Western Ontario and McMaster Universities Osteoarthritis Index, Activities of Daily Living of the Knee Outcome Survey, Oxford Knee Score, and the 12-item Short Form Health Survey) in total knee arthroplasty patients. Seventy-nine patients completed the questionnaires before surgery and 6 months later. The reliability was high for all instruments with intraclass correlation coefficients from 0.81 to 0.96 and SEMs from 6.6% to 28.3% of mean scores. The score changes after surgery were three- to five-fold the instruments' measurement error. The responsiveness was large for all instruments. In conclusion most of the selected instruments were reliable and responsive. It was not possible to clearly identify a "best" or "better" tool and hence all can be considered useful, with the reported psychometric properties serving to guide the choice of instrument for a given purpose.

Recommendations of the OARSI FDA Osteoarthritis Devices Working Group

Osteoarthritis (OA) is the most common type of arthritis and a major cause of chronic musculoskeletal pain and functional disability. While both pharmacologic and non-pharmacologic modalities are recommended in the management of OA, when patients with hip or knee OA do not obtain adequate pain relief and/or functional improvement, joint replacement surgery or other surgical interventions should be considered. Total joint arthroplasties are reliable and cost-effective treatments for patients with significant OA of the hip and knee. Evidence from cohort and observational studies has confirmed substantial improvements in pain relief with cumulative revision rates at 10 years following total hip (THA) and total knee arthroplasties (TKA) at 7% and 10%, respectively. Joint replacements have been used in most every synovial joint, although results for joints other than hip and knee replacement have not been as successful. The evolution of new device designs and surgical techniques highlights the need to better understand the risk to benefit ratio for different joint replacements and to identify the appropriate methodology for evaluating the efficacy and optimal outcomes of these new devices, designed to treat OA joints.

Using outcome measure results to facilitate clinical decisions the first year after total hip arthroplasty

STUDY DESIGN

Variable-occasion, repeated-measures design.

OBJECTIVES

To model change in lower extremity functional status of patients 1 year after total hip arthroplasty (THA), using the Lower Extremity Functional Scale (LEFS) and the 6-minute walk test (6MWT), and, secondarily, to provide clinicians with useful data to guide practice.

BACKGROUND

Given the prevalence of THA and current resource pressures, standardized outcome measures play an important role in providing physical therapists with objective knowledge about postoperative recovery and prognosis.

METHODS

Seventy-five patients, with a mean age of 61 years and a diagnosis of hip osteoarthritis, consented to participate in the study. Assessments were conducted preoperatively and at multiple time points for up to 65 weeks postoperatively. Recovery was modeled using a nonlinear robust regression analysis for clustered data. The predictive ability of age, body mass index, and preoperative score was explored.

RESULTS

Gender-based recovery curves were generated to depict the rate and amount of change in LEFS scores and 6MWT distances over the first year. Preoperative baseline 6MWT distance was the only covariate predictive of postarthroplasty 6MWT distances for both males and females. None of the covariates examined were significantly associated with postarthroplasty LEFS scores.

CONCLUSION

Although there were variations in the recovery curves by measure, general patterns were noted. There was a rapid increase in both self-reported and physical performance measure scores for 12 to 15 weeks. Thereafter, we observed a slowing of recovery, with a plateau at 30 to 35 weeks for the 6MWT and later for the LEFS. These data can be used to make evidence-based decisions regarding prognosis and to guide the setting of measurable treatment goals.

LEVEL OF EVIDENCE

Prognosis, level 1b.

Aseptic lymphocyte-dominated vasculitis-associated lesion: a clinicopathologic review of an underrecognized cause of prosthetic failure

It is estimated that 35% of total hip arthroplasties (THAs) involve a second-generation metal-on-metal (MOM) prosthesis. A novel complication has appeared in a subset of patients with MOM THAs that is described as an aseptic, lymphocyte-dominated vasculitis-associated lesion (ALVAL). The clinical features of ALVAL are nonspecific, but patients complain of pain and may develop "pseudotumors." It is hypothesized that metal ions are released from the prosthesis and form haptens with native proteins that elicit a type IV hypersensitivity response in the local soft tissues. Histopathologic descriptions of ALVAL are similar to those of failed arthroplasty in general, with the addition of a dense perivascular inflammatory infiltrate that is the hallmark of ALVAL. We report 3 cases of ALVAL with clinical, radiographic, and histologic findings. Accurate assessment is crucial because an intraoperative diagnosis of chronic inflammation suggestive of ALVAL will necessitate a replacement of the prosthetic component surfaces.