Background: Structural hip deformities including developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) are thought to predispose patients to degenerative joint changes. However, the natural history of these malformations is not clearly delineated.

Methods: Seven-hundred twenty-two patients ≤55 years that received unilateral primary total hip arthroplasty (THA) from 1980–1989 were identified. Pre-operative radiographs were reviewed on the contralateral hip and only hips with Tönnis Grade 0 degenerative change that had minimum 10-year radiographic follow-up were included. Radiographic metrics in conjunction with the review of two experienced arthroplasty surgeons determined structural hip diagnosis as DDH, FAI, or normal morphology. Every available follow-up AP radiograph was reviewed to determine progression from Tönnis Grade 0–3 until the time of last follow-up or operative intervention with THA. Survivorship was analyzed by Kaplan-Meier methodology, hazard ratios, and multi-state modeling.

Results: One-hundred sixty-two patients met all eligibility criteria with the following structural diagnoses: 48 DDH, 74 FAI, and 40 normal. Mean age at the time of study inclusion was 47 years (range 18–55), with 56% females. Mean follow-up was 20 years (range 10 – 35 years). Thirty-five patients eventually required THA: 16 (33.3%) DDH, 13 (17.6%) FAI, 6 (15.0%) normal. Kaplan-Meier analysis demonstrated that patients with DDH progressed most rapidly, followed by FAI, with normal hips progressing the slowest. The mean number of years spent in each Tönnis stage by structural morphology was as follows: Tönnis 0: DDH = 17.0 years, FAI = 14.8 years, normal = 22.9 years; Tönnis 1: DDH = 12.2 years, FAI = 13.3 years, normal = 17.5 years; Tönnis 2: DDH = 6.0 years, FAI = 9.7 years, normal = 8.6 years; Tönnis 3: DDH = 1.6 years, FAI = 2.6 years, normal = 0.2 years.

Analysis of degenerative risk for categorical variables showed that patients with femoral head lateralization >10 mm, femoral head extrusion indices >0.25, acetabular depth-to-width index <0.38, lateral center-edge angle <25 degrees, and Tönnis angle >10 degrees all had a greater risk of progression from Tönnis 0 to Tönnis 3 or THA. Among patients with FAI morphology, femoral head extrusion indices >0.25, lateral center-edge angle <25 degrees, and Tönnis angle >10 degrees all increased the risk of early radiographic progression. Analysis of degenerative risk for continuous variables using smoothing splines showed that risk was increased for the following: femoral head lateralization >8 mm, femoral head extrusion index >0.20, acetabular depth-to-width index <0.30, lateral center-edge angle <25 degrees, and Tönnis angle >8 degrees.

Conclusions: This study defines the long-term natural history of DDH and FAI in comparison to structurally normal young hips with a presumably similar initial prognostic risk (Tönnis Grade 0 degenerative change and contralateral primary THA). In general, the fastest rates of degenerative change were observed in patients with DDH. Furthermore, risk of progression based on morphology and current Tönnis stage were defined, creating a new prognostic guide for surgeons. Lastly, radiographic parameters were identified that predicted more rapid degenerative change, both in continuous and categorical fashions, subclassified by hip morphology.

Osteoarthritis (OA) is a chronic degenerative joint disease with cartilage degeneration, subchondral bone sclerosis, synovial inflammation and osteophyte formation. Sensory nerves play an important role in bone metabolism and in the progression of inflammation. This study explored the effects of capsaicin-induced sensory nerve denervation on OA progression in mice. This study was approved by the Institutional Animal Care and Use Committee. OA was induced via destabilization of the medial meniscus (DMM). Sensory denervation was induced by subcutaneous injection of capsaicin (90mg/kg) one week prior to DMM. One week after capsaicin injection, sensory denervation in the tibia was confirmed by immunofluorescent staining with calcitonin gene-related peptide (CGRP)-specific antibodies. Four weeks after DMM, micro-CT scans, histological analysis and RT-PCR tests were performed to evaluate OA progression. Statistical analysis was performed using SPSS 13. P values of less than 0.05 were considered statistically significant. Subcutaneous injection of capsaicin successfully induced tibial sensory denervation (n=3), which aggravated OA by increasing subchondral bone resorption. The Osteoarthritis Research Society International (OARSI) score of the capsaicin+DMM group (n=8) (11.81±2.92) was significantly higher (P=0.003) than the score of the vehicle+DMM group (n=8) (8.31±1.80). The BV/TV of the tibial subchondral bone in the capsaicin+DMM group (n=8) was 55.67%±3.08, which was significantly lower (P < 0 .001) than in the vehicle+DMM group (n=8) (86.22%±1.92). In addition, the level of expression of somatostatin in the capsaicin+DMM group (n=8) was lower than in the vehicle+DMM group (n=8) (P=0.007). Capsaicin-induced sensory denervation increased tibial subchondral bone resorption, reduced the expression of somatostatin and eventually exacerbated the existing cartilage degeneration in mice. Despite capsaicin is often used clinically to relieve OA pain, its safety is still controversial according to the OARSI guidelines for the non-surgical management of knee osteoarthritis. The findings of our study suggest that application of capsaicin, although effective in relieving pain, may accelerate the progression of existing OA

Osteoarthritis (OA) is a chronic degenerative joint disorder that affects millions of people. There are currently no therapies that reverse or repair cartilage degradation in OA patients. Link N (DHLSDNYTLDHDRAIH) is a naturally occurring peptide that has been shown to increase both collagen and proteoglycan synthesis in chondrocytes and intervertebral disc cells [1,2]. Recent evidence indicates that Link N activates Smad1/5 signaling in cultured rabbit IVD cells presumably by interacting with the bone morphogenetic protein (BMP) type II receptor [3], however, whether a similar mechanism exists in chondrocytes remains unknown. In this study we determined whether Link N can stimulate matrix production and reverse degradation of human OA cartilage under inflammatory conditions. OA cartilage was obtained from donors undergoing total knee arthroplasty with informed consent. OA cartilage/bone explants and OA chondrocytes were prepared from each donor. Cells were prepared in alginate beads (2×106 cells/mL) for gene expression analysis using qPCR. Cells and cartilage explants were exposed to IL-1β (10ng/ml), human Link N (hLN) (1μg/ml) or co-incubated with IL-1β+hLN for 7 and 21 days, respectively. Media was supplemented every three days. Cartilage/bone explants were measured for total glycosaminoglycan (GAG) content (retained and released) using the dimethylmethylene blue (DMMB) assay. Western blotting was performed to determine aggrecan and collagen expression in cartilage tissue. To determine NFκB activation, Western blotting was performed for detection of P-p65 in chondrocytes cultured in 2D following 10 min exposure of IL-1β in the presence of 10, 100, or 1000 ng/mL hLN. Link N significantly decreased in a dose-dependent manner IL-1β-induced NFκB activation in chondrocytes. Gene expression profiling of matrix proteins indicated that there was a trend towards increased aggrecan and decreased collagen type I expression following hLN and IL-1β co-incubation. HLN significantly decreased the IL-1β-induced expression of catabolic enzymes MMP3 and MMP13, and the neuronal growth factor NGF (p < 0 .0001, n=3). In OA cartilage/bone explants, hLN reversed the loss of proteoglycan in cartilage tissue and significantly increased its synthesis whilst in the presence of IL-1β. Link N stimulated proteoglycan synthesis and decreased MMP expression in OA chondrocytes under inflammatory conditions. One mechanism for Link N in preserving matrix protein synthesis may, in part, be due to its ability in rapidly suppressing IL-1β-induced activation of NF-κB. Further work is needed to determine whether Link N directly inhibits the IL-1β receptor or interferes with NFκB activation through an independent pathway(s)

Objectives. For patients with Developmental Dysplasia of the Hip (DDH) who progress to needing total joint arthroplasty it is important to understand the morphology of the femur when planning for and undertaking the surgery, as the surgery is often technically more challenging in patients with DDH on both the femoral and acetabular parts of the procedure. 1. The largest number of male DDH patients with degenerative joint disease previously assessed in a morphological study was 12. 2. In this computed tomography (CT) based morphological study we aimed to assess whether there were any differences in femoral morphology between male and female patients with developmental dysplasia undergoing total hip arthroplasty (THA) in a cohort of 49 male patients, matched to 49 female patients. Methods. This was a retrospective study of the pre-operative CT scans of all male patients with DDH who underwent THA at two hospitals in Japan between 2006–2017. Propensity score matching was used to match these patients with female patients in our database who had undergone THA during the same period, resulting in 49 male and 49 female patients being matched on age and Crowe classification. The femoral length, anteversion, neck-shaft angle, offset, canal-calcar ratio, canal flare index, lateral centre-edge angle, alpha angle and pelvic incidence were measured for each patient on their pre-operative CT scans. Results. Significant differences were found in femoral anteversion with a mean male anteversion of 22 ˚ (±14.2), compared to 30˚ (±15.5), in females (p=0.02, Confidence Interval (C.I.) 1.6 to 14.9, Figure 1), offset, with a mean male offset of 31 mm (±6.2), compared to 29 mm (±6.1) in females, (p=0.04, C.I: 0.2 to 4.8), and femoral length with a mean femoral length of 434 mm in males (±22.2), compared to 407 mm in females (±23.9), (p<0.001, C.I: 19.2 to 34.3, Figure 2). No significant differences between male and female patients were found for the other measurements. Discussion. This was the first study of this size assessing femoral morphology in male patients with DDH undergoing THA. Significant differences were found between male and female patients in femoral anteversion, length and offset. This should be taken into account when planning and performing THA in these patients. Based on the findings from this study, a more anteverted femoral neck can be expected at the time of surgery in a female patient with DDH undergoing total hip arthroplasty, compared to a male patient

Purpose. To report clinical results and demonstrate any posterior femoral translation (PFT) in medial rotation total knee arthroplasty (TKA) of posterior cruciate ligament (PCL) retaining type. Materials and Methods. A prospective study was performed upon thirty consecutive subjects who were operated on with medial rotation TKA of PCL retaining type (Advance® Medial Pivot prosthesis with ‘Double High’ insert; Wright Medical Technology, Arlington, TN, USA) (Fig. 1). between March 2009 and March 2010 and had been followed up for a least 2 years. Inclusion criteria were age between 60 and 75 years and primary degenerative joint disease of knee graded as Kellgren Lawrence grade III or higher. Exclusion criteria were age under 60 years, any inflammatory joint disease including rheumatoid arthritis, early stage of primary degenerative joint disease of knee or any history of previous osteotomy around knee. Clinically, the knee society knee score and function score were used to evaluate pain and function. At last follow-up, all subjects performed full extension, thirty degree flexion and full active flexion sequentially under fluoroscopic surveillance. In each of these lateral radiographs, anteroposterior(AP) condylar position was pinpointed and the magnitude of PFT was determined by degree of transition of AP condylar position from full extension to full active flexion radiograph (Fig. 2 A–B). Statistical methods used were paired t-test, Pearson correlation, Steadman rank correlation and regression analysis. Component migration and radiolucent line were also observed. Results. At last follow-up, the mean knee society knee score and the mean function score improved significantly compared to preoperative scores (from 61.5 to 90.4 and from 57.8 to 84.7 respectively). The mean maximum flexion of knee increased postoperatively compared to preoperative one without any significant difference (105.5Ëš±11.2Ëšvs 109.3Ëš±9.8Ëš, p=0.051, β=0.387). Neverthless, regression analysis showed a good linear association (r = 0.53, p=0.0027) between the pre- and post-operative maximum flexions of knee. The AP condylar positions were consistently posterior to midline throughout the entire range of flexion. The mean maximum PFT was 10.5 mm (± 4.3 mm) and the magnitude of maximum PFT was greater in higher flexion cases (r = 0.57, p = 0.0009) (Fig. 3). There were no cases having either component migration or radiolucent line except for one case showing instability related to trauma. Conclusions. In medial rotation total knee arthroplasty of PCL retaining type, clinical outcomes were satisfactory and the maximum obtainable flexions tended to be in narrower ranges than those of preoperative ones and smaller than those of other TKA prostheses. Nonetheless, reliable posterior femoral translations were observed during progressive flexions of knees, which was considered to be one of important kinematic factors in increasing the level of knee flexion of medial-rotation TKA in longer follow-ups by providing greater posterior clearance and reduced femoro-tibial impingement

The etiology of the flexion contracture is related to recurrent effusions present in a knee with end-stage degenerative joint disease secondary to the associated inflammatory process. These recurrent effusions cause increased pressure in the knee causing pain and discomfort. Patients will always seek a position of comfort, which is slight flexion. Flexion decreases the painful stimulus by reducing pressure in the knee and relaxing the posterior capsule. Unfortunately, this self-perpetuating process leads to a greater degree of contracture as the disease progresses. Furthermore, patients rarely maintain the knee in full extension. Even during the gait cycle the knee is slightly flexed. As their disease progresses, patients limit their ambulation and are more frequently in a seated position. Patients often report sleeping with a pillow under their knee or in the fetal position. All of these activities increase flexion contracture deformity. Patients with excessive deformity >40 degrees should be counseled regarding procedural complexity and that increasing constraint may be required. Patients are seen preoperatively by a physical therapist and given a pre-arthroplasty conditioning program. Patients with excessive flexion contracture are specifically instructed on stretching techniques, as well as quadriceps rehabilitation exercises. The focus in the postoperative physiotherapy rehabilitation program continues toward the goal of full extension. Patients are instructed in appropriate stretching regimes. Patients are immobilised for the first 24 hours in full extension with plaster splints, such as with a modified Robert Jones dressing. This dressing is removed on postoperative day one. The patient is then placed in a knee immobiliser and instructed to wear it at bed rest, during ambulation and in the evening, only removing for ROM exercises. In cases of severe flexion deformity >30 degrees, patients are maintained in full extension for 3–4 weeks until ROM is begun. Patients are encouraged to use a knee immobiliser for at least the first 6 weeks postoperatively. Treating patients with flexion contracture involves a combination of bone resection and soft tissue balance. One must make every effort to preserve both the femoral and tibial joint line. In flexion contracture the common error is to begin by resecting additional distal femur, which may result in joint line elevation and mid-flexion instability. The distal femoral resection should remove that amount of bone being replaced with metal. Attention should be directed at careful and meticulous balance of the soft tissues and release of the contracted posterior capsule with re-establishment of the posterior recess, which will correct the majority of flexion contractures. Inability to achieve ROM after TKA represents a frustrating complication for both patient and surgeon. Non-operative treatments for the stiff TKA include shoe lift in contralateral limb, stationery bicycle with elevated seat position, extension bracing, topical application of hand-held instruments to areas of soft tissue-dysfunction by a trained physical therapist over several outpatient sessions, and use of a low load stretch device. Manipulation under anesthesia is indicated in patients after TKA having less than 90 degrees ROM after 6 weeks, with no progression or regression in ROM. Other operative treatments range from a downsizing exchange of the polyethylene bearing to revision with a constrained device and low-dose irradiation in cases of severe arthrofibrosis

The etiology of the flexion contracture is related to recurrent effusions present in a knee with end-stage degenerative joint disease secondary to the associated inflammatory process. These recurrent effusions cause increased pressure in the knee causing pain and discomfort. Patients will always seek a position of comfort, which is slight flexion. Flexion decreases the painful stimulus by reducing pressure in the knee and relaxing the posterior capsule. Unfortunately, this self-perpetuating process leads to a greater degree of contracture as the disease progresses. Furthermore, patients rarely maintain the knee in full extension. Even during the gait cycle the knee is slightly flexed. As their disease progresses, patients limit their ambulation and are more frequently in a seated position. Patients often report sleeping with a pillow under their knee or in the fetal position. All of these activities increase flexion contracture deformity. Patients with excessive deformity >40 degrees should be counseled regarding procedural complexity and that increasing constraint may be required. Patients are seen pre-operatively by a physical therapist and given a pre-arthroplasty conditioning program. Patients with excessive flexion contracture are specifically instructed on stretching techniques, as well as quadriceps rehabilitation exercises. Avoiding Pitfalls and Complications: Treating patients with flexion contracture involves a combination of bone resection and soft tissue balance. One must make every effort to preserve both the femoral and tibial joint line. In flexion contracture the common error is to begin by resecting additional distal femur, which may result in joint line elevation and mid-flexion instability. The distal femoral resection should remove that amount of bone being replaced with metal. Attention should be directed at careful and meticulous balance of the soft tissues and release of the contracted posterior capsule with re-establishment of the posterior recess, which will correct the majority of flexion contractures. Residual Flexion Contracture: Inability to achieve ROM after TKA represents a frustrating complication for both patient and surgeon. Non-operative treatments for the stiff TKA include shoe lift in contralateral limb, stationery bicycle with elevated seat position, extension bracing, topical application of hand-held instruments to areas of soft tissue-dysfunction by a trained physical therapist over several outpatient sessions, and use of a low load stretch device. Manipulation under anesthesia is indicated in patients after TKA having less than 90 degrees ROM after 6 weeks, with no progression or regression in ROM. Other operative treatments range from a downsizing exchange of the polyethylene bearing to revision with a constrained device and low-dose irradiation in cases of severe arthrofibrosis

Ceramic-on-ceramic bearings are considered in several European and Asian countries a reliable alternative to metal-on-polyethylene, ceramic-on-polyethylene, or metal-on-metal (with small diameter heads) for total hip arthroplasty (THA) management. Reduced joint wear and limited peri-prosthetic osteolytic changes are the main reasons supporting the use of ceramic. So far, the available observational data show a low rate of revision following the use of Ceramic-on-Ceramic bearings, but concern remains regarding the risk of fracture and the prevalence of squeaking noises from the joint. The objective of this study was to use a national arthroplasty registry to assess whether the choice of bearings – metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), ceramic-on-ceramic (CoC), or metal-on-metal (MoM) – is associated with differences in the risk of revision. Data from primary THAs were extracted from the New Zealand Joint Registry over a 15-year period. 97,889 hips were available for analysis. The mean age of patients was 68 years (SD +/− 11 years), and 52% were women. The median followup period in this patient population was 9 years (range, 1 to 15 years). The primary endpoint was revision for any reason. Inclusion criteria were degenerative joint disease (84,894), exclusion criteria were previous surgery, trauma, and any other diagnosis (12,566). We also excluded patients operated on with a Ceramic-on-Metal THA, because of the small recorded number (429). There were 54,409 (64.1%) MoP, 16,503 (19.4%) CoP, 9,051 (10.7%) CoC and 4,931 (5.8%) MoM hip arthroplasties. 3,555 hips were revised during the 15-year observation period. A multivariate assessment was carried out including the following risks factors available for analysis: age, gender, surgeon experience, use of cement. Analysis of bearing surface type and revision showed a statistically significant lower risk for CoC hips (265 THAs, p≤0.01) when compared with CoP (537 THAs, HR 1.07, CI 0,92–1,26), MoP (2186 THAs, HR 1.39, CI 1.19–1,62), and MoM (576 THAs, HR 2.15, CI 1.84–2.51). The 15-year follow-up Kaplan-Meier survival analysis shows a 92% revision-free rate for CoC THAs (Figure 1). In particular, CoC THAs showed the lowest rates of revision for dislocation and for deep infection, when compared with the other bearings. This registry study showed that the bearing surface is associated with the risk of revision. MoM bearing surfaces showed a high rate of revisions, while CoC THAs showed the lowest rate of revision compared to other bearing surfaces. Low wear and less osteolysis are the possible reasons for reduced risk of revision for aseptic loosening. We postulate that the healthy, fibrotic synovial-like pseudocapsule found in CoC THAs preserves the long-term stability of the joint and reduces the bio-burden for late deep infection. Future studies with larger data sets and longer follow-up should continue to investigate this query. For any figures or tables, please contact the authors directly

We live in an era where younger, fitter, more active patients are presenting with the symptoms and signs of degenerative joint disease and require total knee and total hip arthroplasty at a young age. At the same time, this population of patients is living longer and longer and is likely to create new and more complex failure modes for their implants. The ideal solution is a biological one, whereby we can either prevent joint degradation or catch it in its early stages and avoid further deterioration. There may also be advances along the way in terms of partial arthroplasty and focal resurfacing that will help us prevent the need for total joint arthroplasty. There are several tensions that need to be considered. Should we resurface / replace early, particularly now that we have access to navigation and robotics and can effectively customise the implants to the patient's anatomy and their gait pattern? This would allow good function at a young age. Or should we wait as long as possible and risk losing some function for the sake of preserving the first arthroplasty for the lifetime of the patient?. There are some key issues that we still do not fully understand. The lack of true follow-up data beyond 20 or 30 years is worrying. The data available tends to be from expert centers, and always has a dramatic loss to follow-up rate. We worry about bearing surfaces and how those materials will behave over time but we really do not know the effect of chronic metal exposure over several decades, nor do we really understand what happens to bone as it becomes more and more osteopenic and fragile around implants. We have largely recorded but ignored stress shielding, whereas this may become a very significant issue as our patients get older, more fragile, more sarcopaenic and more neurologically challenged. All the fixation debates that we have grappled with, may yet come back to the fore. Can ingrowth lead to failure problems later on? Will more flexible surfaces and materials be required to fit in with the elasticity of bone?. We have failed dramatically at translating the in vitro to the in vivo model. It seems that the in vitro model tells us when failure is going to occur but success in vitro does not predict success in vivo. We, therefore, cannot assume that long-term wear data from simulators will necessarily translate to the extreme situations in vivo where the loading is not always idealised, and can create adverse conditions. We must, therefore, consider further how to improve and enhance our interventions. There is no doubt that the avoidance of arthroplasty needs to be at the heart of our thinking but, ultimately, if arthroplasty is to be performed, it needs to be performed expertly and in such a way as to minimise later failure. It also, clearly, needs to be cost-effective. The next stage will no doubt involve close cooperation between surgeons, engineers and industry partners to identify individualised surgical targets, select an appropriate prosthesis to minimise soft-tissue strain and develop a reproducible method of achieving accurate implantation. An ideal outcome can only be achieved by an appropriately trained surgeon selecting the optimal prosthesis to implant in the correct position in the well-selected patient. In the longer term, our choice of implants and the way that they are inserted and fixed must take into account the evolving physiology of our patients, the nature of our devices and how to limit harm from them, and the long-term impact of the materials used which we sometimes still do not understand

INTRODUCTION. Shoulder arthroplasty (SA) is an effective procedure for managing patients with shoulder pain secondary to degenerative joint disease or end stage arthritis that has failed conservative treatment. Insurance status has been shown to be an indicator of patient morbidity and mortality. The objective of the current study is to evaluate the effect of patient insurance status on outcomes following shoulder replacement surgery. METHODS. Data was obtained from the Nationwide Inpatient Sample between 2004 and 2011. Analysis included patients undergoing shoulder arthroplasty procedures determined by ICD-9 procedure codes. Patient demographics and comorbidities were analyzed and stratified by insurance type. The primary outcome was medical and surgical complications occurring during the same hospitalization with secondary analysis of mortality. Pearson's chi¬squared test and multivariate regression were performed. RESULTS. A data inquiry identified 103,290 patients (68,578 Medicare, 27,159 private insurance, 3,544 Medicaid/uninsured, 4,009 Other) undergoing partial, total and reverse total shoulder replacements. The total number of complications was 17,810 (17.24%), and the top three complications included acute cardiac events (8,165), urinary tract infections (3,154), and pneumonia (1,635). The highest complication rate was observed in the Medicare population (20.3%), followed by the Medicaid/uninsured (16.9%), other (11.1%), and the privately-insured cohort (10.5%). Multivariate regression analysis indicated that having Medicare insurance, white race, increasing age, higher comorbidity, and urgent or emergent admissions was associated with medical complications. Black patients, increasing age and comorbities was associated with surgical complications. Overall mortality was 0.20% and was more common in total shoulder arthroplasty and surgeries done on emergent or urgent admissions. DISCUSSION. This data reveals that patients with Medicare, Medicaid or no insurance were more likely to have medical complications, most commonly cardiac complications, UTIs and pneumonia. Primary insurance payer status can be considered as an independent risk factor during preoperative risk stratification and planning

PURPOSE. Lateral osteoarthritis of the valgus knee is a challenging problem, especially for young and active patients, where prosthetic replacement is not indicated. The purpose of the present study is to evaluate clinically and radiographically 91 patients with valgus knee treated with distal femoral varus osteotomy in mid and long term follow-up. METHODS. A clinical retrospective evaluation based on IKDC, OXFORD and WOMAC scores of 91 patients at 4 to 10 years of follow-up was performed. Subjective evaluation was based on a VAS for pain self-assessment. Radiographic evaluation was performed by an independent observer of all 91 patients at 2 to 6 years of follow-up. A survival analysis was performed assuming revision for any reason as primary endpoint. RESULTS. The present study reported a marked improvement in clinical score at a mean 8,3 years of follow-up with statistical significance (p<0.005). The radiographic evaluation revealed a reduction of 7,0° and 4,2° of FTA and HKA angles respectively (p<0.05) at a mean follow up of 4,3 years, while small differences were observed with TPA and PTS angles. The 8-years treatment survivorship was 95,6%. CONCLUSIONS. The present study demonstrates that distal femoral varus osteotomy is an effective and reliable option to manage lateral tibio-femoral compartment early degenerative joint disease in young- to middle-age patients, providing a satisfactory clinical improvement at a mean follow-up of 8 years. Furthermore, its survivorship at 8-years follow-up is over 95%

Introduction. Geometric variations of the hip joint can give rise to abnormal joint loading causing increased stress on the articular cartilage, which may ultimately lead to degenerative joint disease. In-vitro simulations of total hip replacements (THRs) have been widely reported in the literature, however, investigations exploring the tribology of two contacting cartilage surfaces, and cartilage against metal surfaces using complete hip joint models are less well reported. The aim of this study was to develop an in-vitro simulation system for investigating and comparing the tribology of complete natural hip joints and hemiarthroplasties with THR tribology. The simulation system was used to assess natural porcine hip joints and porcine hemiarthroplasty hip joints. Mean friction factor was used as the primary outcome measure to make between-group comparisons, and comparisons with previously published tribological studies. Method. In-vitro simulations were conducted on harvested porcine tissue. A method was developed enabling natural acetabula to be orientated with varying angles of version and inclination, and natural femoral heads to be potted centrally with different orientations in all three planes. Acetabula were potted with 45° of inclination and in the complete joint studies, natural femoral heads were anatomically matched and aligned (n=5). Hemiarthroplasty studies (n=5) were conducted using cobalt chrome (CoCr) heads mounted on a spigot (Figure 1), size-matched to the natural head. Natural tissue was fixed using PMMA (polymethyl methacrylate) bone cement. A pendulum friction simulator (Simulator Solutions, UK), with a dynamic loading regime of 25–800N, ± 15° flexion-extension (FE) at 1 Hertz was used. The lubricant was a 25% (v/v) bovine serum. Axial loading and motion was applied through the femoral head and frictional torque was measured using a piezoelectric transducer, from which the friction factor was calculated. Results. The correct anatomical orientation and positioning was achieved enabling in-vitro simulation testing to be conducted on hemiarthroplasty and complete hip joint samples for two-hours. Mean friction increased rapidly followed by a continued gradual increase to ≈0.03 ± 0.00 in the complete joints, with the hemiarthroplasty group plateauing at ≈0.05 ± 0.01 (Figure 2). Mean friction factor was significantly lower (t-test; p < 0.05) in the complete natural joint group. Discussion. An in-vitro simulation system for the natural hip joint with controlled orientation of the femur and acetabulum was successfully developed and used to measure friction in complete porcine hip joints and porcine hip hemiarthroplasties. A non-linear increase in friction indicative of biphasic lubrication was observed in both groups with slower exudation of fluid from the complete joints compared to the hemiarthroplasties, inferring a quicker move towards solid-phase lubrication. Higher friction in the hemiarthroplasties, which was similar to that measured in-vitro in metal-on-polyethylene THRs, was most likely due to variable clearances between the non-conforming spherical metal head and aspherical acetabulum, causing poorer congruity and distribution of the load. This could in time lead to abrasive wear and cartilage degradation. This methodology could have an important role when investigating associations between hip geometric variations, interventions for hip disease/pathology, and risk factors for cartilage degeneration

INTRODUCTION. Bicompartmental knee arthroplasty (BKA) is an alternative to total knee arthroplasty (TKA) for degenerative joint disease when present in only two compartments. BKA spares the cruciate ligaments and preserves bone in the healthy compartment, possibly leading to better knee kinematics and clinical outcomes when compared to TKA. While BKA is a technically demanding procedure when performed with manual instrumentation, robotic assistance allows for accurate implant placement and soft tissue balancing of the joint. Robotic unicompartmental knee arthroplasty (UKA) has shown favorable clinical outcomes and survivorship at short term (2 year) follow up compared to manual UKA. The purpose of this study is to evaluate the short term functional outcomes and survivorship of patients undergoing robotically assisted BKA. METHODS. 45 patients (48 knees) were identified in an initial and consecutive single surgeon series receiving robotically assisted BKA to correct disease in the medial and patellofemoral compartments. As part of an IRB approved study, every patient in the series was contacted at a minimum two year (±2 months) follow up and asked a series of questions to determine implant survivorship and functional outcomes (using the patient portion of the Knee Society Score). 9 patients were lost to follow up and 1 patient was deceased. 35 patients (38 knees) at a minimum two year follow up enrolled in the study for an enrollment rate of 79%. There are 22 male patients and 13 female patients; the average age at time of surgery is 67.0 ± 6.8 and the average BMI is 29.5 ± 4.6. Five patients in this series also qualified for a 5 year follow up assessment. RESULTS. Only 1 BKA was reported as revised to a TKA at two year follow up. The revision was reported by the patient due to severe pain and occurred 25 months after the index BKA procedure. The patient did not return to the same surgeon for the revision procedure. The average pre-operative Knee Society Function Score was 58.1 ± 9.9 (n=18) and improved at 2 years post-operatively to 81.5 ± 15.9 (n = 36) (p<0.001). Of the 5 patients contacted at a minimum 5 year follow up, there were no reported revisions. CONCLUSIONS. Robotically assisted BKA shows good survivorship and functional outcomes at a short term 2 year follow up. This procedure may be a viable option to patients with only two diseased compartments, as sparing of healthy bone and cruciates may improve overall kinematics and outcomes of the joint. This study remains ongoing to include a larger cohort and longer follow up

INTRODUCTION. Total joint arthroplasty continues to gain acceptance as the standard of care for the treatment of severe degenerative joint disease, and is considered one of the most successful surgical interventions in the history of medicine. However, infection of these implants, called Periprosthetic Joint Infection (PJI), remains one of the biggest challenges facing orthopaedics today. PJI can lead to additional surgeries, revision, fusion and amputation. Diagnosis of PJI. It is important to accurately diagnose PJI because its management differs from that of other causes of arthroplasty failure. In acute infection, the local signs and symptoms (e.g., severe pain, swelling, erythema, and warmth at the infected joint) of inflammation are generally present. On the other hand, chronic infection usually has a more subtle presentation, with pain alone, and is often accompanied by loosening of the prosthesis at the bone-implant interface. The diagnosis of PJI has proven quite challenging, as both acute and chronic infections can be difficult to differentiate from other forms of inflammation. The reported literature on the diagnosis of PJI has focused on evaluated laboratory tests that were never developed specifically for the diagnosis of PJI. These include the erythrocyte sedimentation rate (ESR), the serum C-reactive protein (CRP), the synovial fluid white blood cell count and the leukocyte differential. Because these tests were not made for the purpose of diagnosing PJI, it has been the responsibility of the orthopaedic community to evaluate and recommend their interpretation. This has resulted in significant confusion regarding the appropriate thresholds and optimal combination of these tests. These difficulties were the motivation for the development of a specific test for the detection of PJI. The Synovasure® Test for Periprosthetic Joint Infection (PJI). The promising diagnostic capabilities of synovial fluid biomarkers for PJI have already been reported in the literature. These biomarkers include inflammatory proteins, cytokines, and microbicidal peptides / proteins that are known to be involved in the host response to infection. Studies have demonstrated that the alpha-defensin microbicidal peptide present in human neutrophils is an ideal biomarker for PJI due to the distinct separation it achieves between positive and negative results. A specific test allowing to measure the concentration of the alpha-defensin in the synovial fluid has been developed. The specificity and the sensitivity of this test for the detection of a PJI are respectively 96% and 97%. This test has been proven to have also a high reproducibility, its results not being influenced by antibiotics. DISCUSSION. A lateral flow version of this test (Synovasure PJI, distributed exclusively in Europe by Zimmer GmbH) has been recently developed. It allows reading the results in 10 minutes and it doesn't require any laboratories for its interpretation. Currently, this test device is in clinical evaluation in more than 200 European hospitals. CONCLUSIONS. In case that the clinical evaluation of this test device is positive, this method will be a new paradigm for the diagnosis of periprosthetic joint infection

Total joint arthroplasty continues to gain acceptance as the standard of care for the treatment of severe degenerative joint disease. However, the Periprosthetic Joint Infection (PJI) remains one of the biggest challenges facing orthopaedics today. It is important to accurately diagnose PJI because its management differs from that of other causes of arthroplasty failure. The most common symptom of PJI is pain. In acute infection, the local signs and symptoms (e.g., severe pain, swelling, erythema, and warmth at the infected joint) of inflammation are generally present. On the other hand, chronic infection usually has a more subtle presentation, with pain alone, and is often accompanied by loosening of the prosthesis at the bone-implant interface. The diagnosis of PJI has proven quite challenging, as both acute and chronic infections can be difficult to differentiate from other forms of inflammation. The reported literature on the diagnosis of PJI has focused on evaluated laboratory tests that were never developed specifically for the diagnosis of PJI. Because these tests were not made for the purpose of diagnosing PJI, it has been the responsibility of the orthopaedic community to evaluate and recommend their interpretation. This has resulted in significant confusion regarding the appropriate thresholds and optimal combination of these tests. These difficulties were the motivation for the development of a specific test for the detection of PJI. The promising diagnostic capabilities of synovial fluid biomarkers for PJI have already been reported in the literature. Studies have demonstrated that the alpha-defensin microbicidal peptide present in human neutrophils is an ideal biomarker for PJI due to the distinct separation it achieves between positive and negative results. A specific test allowing to measure the concentration of the alpha-defensin in the synovial fluid has been developed. The specificity and the sensitivity of this test for the detection of a PJI are respectively 96% and 97%. This test has been proven to have also a high reproducibility, its results not being influenced by antibiotics. A lateral flow version of this test (Synovasure PJI, distributed exclusively in Europe by Zimmer GmbH) has been recently developed. It allows reading the results in 10 minutes and it doesn't require any laboratories for its interpretation. Currently, this test device is in clinical evaluation in more than 200 European hospitals. In case that the clinical evaluation of this test device is positive, this method will be a new paradigm for the diagnosis of periprosthetic joint infection

Introduction. Bi-compartmental knee arthroplasty (BKA) is an alternative to total knee arthroplasty (TKA) for degenerative joint disease when present in only two compartments. BKA spares the cruciate ligaments and preserves bone in the healthy compartment, possibly leading to better knee kinematics and clinical outcomes when compared to TKA. While BKA is a technically demanding procedure when performed with manual instrumentation, robotic assistance allows for accurate implant placement and soft tissue balancing of the joint. Robotic unicompartmental knee arthroplasty (UKA) has shown favourable clinical outcomes and survivorship at short term (2 year) follow up compared to manual UKA. The purpose of this study is to evaluate the short term functional outcomes and survivorship of patients undergoing robotically assisted BKA. Methods. 45 patients (48 knees) were identified in an initial and consecutive single surgeon series receiving robotically assisted BKA to correct disease in the medial and patellofemoral compartments. As part of an IRB approved study, every patient in the series was contacted at a minimum two year (±2 months) follow up and asked a series of questions to determine implant survivorship and functional outcomes (using the patient portion of the Knee Society Score). 9 patients were lost to follow up and 1 patient was deceased. 35 patients (38 knees) at a minimum two year follow up enrolled in the study for an enrolment rate of 79%. There are 22 male patients and 13 female patients; the average age at time of surgery is 67.0 ± 6.8 and the average BMI is 29.5 ± 4.6. Five patients in this series also qualified for a 5 year follow up assessment. Results. Only 1 BKA was reported as revised to a TKA at two year follow up. The revision was reported by the patient due to severe pain and occurred 25 months after the index BKA procedure. The patient did not return to the same surgeon for the revision procedure. The average pre-operative Knee Society Function Score was 58.1 ± 9.9 (n=18) and improved at 2 years post-operatively to 81.5 ± 15.9 (n = 36) (p<0.001). Of the 5 patients contacted at a minimum 5 year follow up, there were no reported revisions. Conclusions. Robotically assisted BKA shows good survivorship and functional outcomes at a short term 2 year follow up. This procedure may be a viable option to patients with only two diseased compartments, as sparing of healthy bone and cruciates may improve overall kinematics and outcomes of the joint. This study remains ongoing to include a larger cohort and longer follow up

INTRODUCTION. Bicompartmental knee arthroplasty (BKA) is an alternative to total knee arthroplasty (TKA) for degenerative joint disease when present in only two compartments. BKA spares the cruciate ligaments and preserves bone in the healthy compartment, possibly leading to better knee kinematics and clinical outcomes when compared to TKA. While BKA is a technically demanding procedure when performed with manual instrumentation, robotic assistance allows for accurate implant placement and soft tissue balancing of the joint. Robotic unicompartmental knee arthroplasty (UKA) has shown favorable clinical outcomes and survivorship at short term (2 year) follow up compared to manual UKA. The purpose of this study is to evaluate the short term functional outcomes and survivorship of patients undergoing robotically assisted BKA. METHODS. 45 patients (48 knees) were identified in an initial and consecutive single surgeon series receiving robotically assisted BKA to correct disease in the medial and patellofemoral compartments. As part of an IRB approved study, every patient in the series was contacted at a minimum two year (±2 months) follow up and asked a series of questions to determine implant survivorship and functional outcomes (using the patient portion of the Knee Society Score). 9 patients were lost to follow up and 1 patient was deceased. 35 patients (38 knees) at a minimum two year follow up enrolled in the study for an enrollment rate of 79%. There are 22 male patients and 13 female patients; the average age at time of surgery is 67.0 ± 6.8 and the average BMI is 29.5 ± 4.6. Five patients in this series also qualified for a 5 year follow up assessment. RESULTS. Only 1 BKA was reported as revised to a TKA at two year follow up. The revision was reported by the patient due to severe pain and occurred 25 months after the index BKA procedure. The patient did not return to the same surgeon for the revision procedure. The average pre-operative Knee Society Function Score was 58.1 ± 9.9 (n=18) and improved at 2 years post-operatively to 81.5 ± 15.9 (n = 36) (p<0.001). Of the 5 patients contacted at a minimum 5 year follow up, there were no reported revisions. CONCLUSIONS. Robotically assisted BKA shows good survivorship and functional outcomes at a short term 2 year follow up. This procedure may be a viable option to patients with only two diseased compartments, as sparing of healthy bone and cruciates may improve overall kinematics and outcomes of the joint. This study remains ongoing to include a larger cohort and longer follow up

Aim. To assess if there is a reproducible relationship between the width and thickness of the normal patella. Method. 43 MRI scans of young adults, average age 27 (range 17–38) were studied. Exclusion criteria included a diagnosis of degenerative joint disease, patella-femoral pathology or age under 16/over 40 (102 patients). The bony thickness of the patella, the chondral thickness and patella width were measured, as was the location of maximal patella thickness. Inter/intra observer variability was calculated and correlation analysis performed. Results. There was a strong correlation between overall patella thickness (bone plus cartilage) and width (Pearson 0.75, P < 0.001). The width: thickness ratio is 1.8:1 (standard deviation 0.102, 95% confidence interval 1.6–2.0). The average patella cartilage thickness is 4.1mm (SD 1.3). The thickest region of the patella lies 54% (SD 2.32) from the lateral border and 54% (SD 7.9) from the superior pole. Conclusion. We propose that the normal “Index of Patella Width: Thickness” = 1.8:1. It can be used as a guide for restoring patella thickness during TKR or patella-femoral replacement to that of a knee free from age related wear and osteoarthritis. This maximal thickness should be slightly medial and distal in the patella. MULTIPLE DISCLOSURES

Patello-femoral arthritis can result in a considerable thinning of the patella. The restoration of an adequate patella thickness is key to the successful outcome of knee arthroplasty. The objectives were (1) to establish a reproducible patella width:thickness index including chondral surface and (2) to investigate whether there is a difference between bone alone and bone/chondral construct thickness as shown by MRI. Forty three MRI scans of young adults, mean age 27 (range 17–38), 34 male and 9 female, were studied. Exclusion criteria included degenerative joint disease, patello-femoral pathology or age under 16/over 40 (102 patients). The bony and chondral thickness of the patella and its width were measured. Inter/intra observer variability was calculated and correlation analysis performed. We found a strong correlation between patella plus cartilage thickness and width (Pearson 0.75, P < 0.001). The mean width:thickness ratio was 1.8 (SD 0.10, 95% CI 1.77–1.83). Without cartilage the ratio was 2.16 (SD 0.15, 95% CI 2.11–2.21), correlation was moderate (Pearson 0.68, P < 0.001). The average patella cartilage thickness was 4.1mm (SD 1.1, 95% CI 3.8–4.5). The narrow confidence intervals for the ratio of patella width:thickness suggest that patella width can be used as a guide to accurate restoration of patella thickness during total knee or patella-femoral replacement. We would recommend a ratio of 1.8:1

Introduction. The metal-backed patella was originally designed to address shortcomings found with cemented, all-polyethylene patellae. However, complications relating to an all-polyethylene patella were reported to account for up to half of all knee revisions. At the same time, good fixation with bone ingrowth was observed in both titanium and cobalt chromium porous-coated patellae. The advantages provided by using a metal-backed patella, such as uniform load sharing, decreased polyethylene deformation, and potential for biological fixation, may be unjustly outweighed by the fear of patellar component failure; high rates of failure have not been inherent to all metal-backed patella designs. Over the past decade, we have used a metal-backed patella design with excellent results that may be due largely to the design features of the component. Also, we believe there are certain selection criteria that should be strictly adhered to when implanting metal-backed patellae. Correct selection criteria and improved component design strongly indicate the use of press-fit metal-backed patellae. Methods. This single-center study was designed to conduct clinical and independent radiographic review of primary metal-backed, press-fit patella patients with a minimum five-year follow-up. Potential patients were recruited from a group of existing metal-backed patella patients within the principal investigator's medical practice. All patients recruited for this study were required to have undergone primary knee replacement surgery at least five years prior to clinical and radiographic evaluation. Patients were included if they had a diagnosis of noninflammatory degenerative joint disease. Patients with a BMI >40 were excluded from this study. Radiographic analysis was conducted by an independent reviewer according to the current Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Any radiographs that the reviewer deemed questionable were shown to a second independent orthopaedic surgeon for review, comment, and validation of observations. Kaplan-Meier survivorship was determined for all metal-backed patellae. For survival analysis, only knees with radiographic data were included (74 knees). KSS, WOMAC, and SF-36 scores were calculated also. Results. Seventy-four patients (88 knees) were enrolled in the study, 31 women (41.2%) and 43 men (58.1%). At the time of surgery, the average age was 59.7 years (range, 40–86 years), and the average BMI was 30.6 (range, 19.1–39.6). The breakdown of patients who completed the study and those who were lost to follow-up is shown in Table 1. One metal-backed patella was revised at 49 months for loosening at the bone/implant interface. Survivorship of the metal-backed patellae at minimum five-year follow-up was estimated to be 93.95% with bounds of 73.61% and 98.74%. No radiolucencies greater than 1 mm were observed in any radiographs (Fig. 1), with the exception of the one revision case. Conclusion. Our experience with this metal-backed patella design has been excellent. Failure does not occur due to dissociation of the plastic. As the porous coating is almost under constant compression, biological fixation is assured in most instances, as confirmed by our minimum five-year radiological results. Improved component design and adherence to the correct patient selection criteria absolutely indicate the use of press-fit metal-backed patellae