Abstract. Background. The primary objective of the study is to determine the function outcome and survivorship of patellofemoral replacement. The secondary aim is to find the determinants of successful/poor outcome. Methods. This retrospective study involved 45 patients who underwent AVON patellofemoral replacement between January 2015 to December 2020 with the minimal follow-up off for 12 months. The functional outcome was measured using Oxford Knee score (OKS), EuroQol five dimension (EQ-5D). IWANO and Kellgren-Lawrence classification was used to analyse radiographs. To identify determinants of outcome, the following subgroups the presence or absence of normal alignment, tibiofemoral arthritis, trochlear dysplasia and previous surgery. Complications and revision rates were also recorded. Results. The mean follow-up period was 41.7 +/− 8.3 months with no patients lost in follow-up. Patellofemoral replacement significantly improved the Oxford Knee score (OKS), EuroQol five dimension (EQ-5D) (p<0.001). Four out of 45(8.9%) patients underwent revision surgery. Patients with normal alignment preoperatively did worse than those with abnormal alignment with patellar instability. Patients with grade two tibiofemoral arthritis, history of previous surgery did significantly worse with poorer functional outcome. Conclusion. Patellofemoral arthroplasty is reliable treatment option which improves patient function and quality of life with good survivorship in isolated patellofemoral arthritis in mid-term follow-up

Since 1996 over 400 isolated patellofemoral replacements using the Avon prosthesis have been undertaken in Bristol. As a result of the usually gratifying outcomes seen in patients over 55 years old, the indications for this surgery were soon extended to include the many younger patients who have severely disabling patellofemoral disease. We present results from a prospective cohort study of patients under 55 years of age at the time of surgery. 110 knees in 86 patients (median age 47 years, range 24–54) have been treated with Avon patellofemoral replacement (88 in females and 22 in males). Diagnoses included lateral facet OA (59 knees), patella dislocation (25 knees), trochlear dysplasia (41 knees) and post patellectomy instability (7 knees). 79 knees had undergone previous surgery. 17 knees required additional intra-operative procedures including 11 lateral releases and 2 patella realignments. All patients were assessed pre-operatively and at regular intervals using the Oxford, Bristol and WOMAC scores. All knees were scored preoperative and only one knee has been lost to follow-up due to the patient’s death, which was unrelated to surgery. Post-operative Oxford knee scores have been obtained for 106 knees with follow-up between 8 months and 8 years (mean follow-up 24 months). The mean Oxford score improved from 18 preoperatively to 31 at latest review. Bristol and WOMAC scores showed similar improvements. 16 knees required post-operative additional procedures including 6 lateral releases, 3 patella realignments and 11 revisions. Of the revisions 5 were for progression of tibiofemoral OA but none of these were knees with trochlear dysplasia. Equally good mean scores were seen when comparing patients with the 3 main underlying pathologies (trochlear dysplasia, patellar dislocation and lateral facet OA). At least 37% of the patients studied had pre-existing trochlear dysplasia and the majority of these patients report onset of symptoms, often patellar dislocation, in the first three decades of life. More than 90% of patients were overweight or obese according to their BMI at the time of surgery. Many of this type of patient, with disabling symptoms, wish to “live now”. The short-term improvements are frequently dramatic. As yet there is no suggestion of prosthetic failure. Revision presents little difficulty since minimal bone is resected in the primary proceedure. Radiological deterioration of the tibio femoral joint is seen in some cases of primary OA but not with trochlear dysplasia

Aims: determine functional outcome of revision Avon patellofemoral replacements (PFR), converted from primary Lubinus PFR. Materials and Methods:. Prospective review of 11 knees (8 patients, 6 female). Average age at primary PFR – 64 years. Indication – isolated patellofemoral osteoarthritis (11), patellofemoral instability (3). 9 knees (7 patients) temporarily improved. Revision Avon PFR at average 83 months after primary procedure. Indication – polyethylene wear. polyethylene synovitis. femoral component malposition. At review:. average 61 months after revision. age – 70 years 10 months. fixed flexion contracture 1.7°. maximum flexion 111°. Bristol knee score improved from average of 54.5 to 77.2. Pain score component averaged 25, functional component averaged 16.9. No malalignment or instability. Average American Knee Society Score 132.8. Bartlett patellar score 19.8. Three patients (4 knees) had medical problems contributing to their functional incapacity. No radiological complications except minor polyethylene wear on lateral facet of one patella. Progression to tibiofemoral osteoarthritis (Ahlburgh grade 1) in 3 knees. Discussion: Primary Lubinus PFR temporarily improved 82% of knees. Maltracking/polyethylene wear was usual cause for failure. Revision to Avon PFR resulted in substantial improvement of pain and function. Conclusion: revision Avon PFR can provide a suitable alternative to revision to total knee replacement

Background. The cemented mobile bearing metal backed low contact stress patellofemoral arthroplasty (LCS PFA) is a newer design belonging to the second generation of inlay type implant, based on the more successful knee arthroplasty model. The advantage is the patella can articulate with the trochlear implant as well as the femoral component of a total knee replacement (TKR). Patients. This series is a cohort of 21 patients who underwent 24 (3 bilateral) unicompartmental PFA replacements for isolated patellofemoral osteoarthritis. We have used the mobile bearing LCS PFA in all of them. There were 3 males and 18 females. Average age was 51(40-58) years. The Oxford Knee score was used to assess the results. Results. At the latest follow-up averaging 2.7 (0.5 to 4) years, 9 patients showed excellent improvement in their knee scores, 5 patients showed fair improvement and 7 patients very little. There were 9 revisions in 7 patients either due to mechanical problems or with persistent symptoms. We had 4 patients with mechanical complications who underwent revision and 4 patients had a conversion to TKR. The revision rate at 2 years was 33%. There were no infections or loosening of trochlear implants. Conclusion. The revision rate for this implant seems to be very high and mainly with the patellar implant (at the metal polyethylene interface). The Australian Orthopaedic association annual joint registry report 2008 reported a higher revision rate for the same implant at 5% from a pool of 1057 patients. The young active patient having a patellofemoral replacement may put extreme force on their patellar implant. We strongly advocate patellofemoral arthroplasties to be analysed separately from the unicompartmental knees in the National Joint Registries to highlight any persistent issues with this implant

Despite the successful, durable results, concern remains for using TKA in patients with isolated patello-femoral OA, as it requires an extensive surgical exposure and bone resection, a long recovery time, and a potentially more complex revision than that required for a patient with a failed patello-femoral arthroplasty (PFA).

PFA was introduced in the late 1970s. While PFA was successful in providing pain relief, the procedure did not gain widespread use because of initial design limitations that predisposed to PF maltracking, catching, and subluxation. The mechanical complications associated with first-generation PFA offset the potential advantages of maintaining the knee's native soft tissues and spurred efforts to improve implant design, and to refine surgical techniques and patient selection.

Over the past two decades, second generation PFAs incorporated changes in implant design and instrumentation and have shown promising results when used in the properly selected patient population. In addition, with improved instrumentation and robotics, adequate implant alignment and rotation can be achieved in the majority of patients, including those with severe patellofemoral dysplasia.

Our meta-analysis of TKA and PFA for the treatment of isolated patello-femoral OA showed that the rate of complications of patients undergoing PFA was 30% after a median follow up of 5.3 years, which is significantly higher than the 7% rate of complications in patients who underwent TKA. The most frequent type of complication associated with PFA was mechanical (including loosening and instability), which is consistent with the malalignment and maltracking-related failures previously reported. The incidence of re-operation after PFA (21%) was significantly higher than that seen after TKA (2%). The most frequent indication for re-operation after PFA was mechanical failure (7%), followed by progression of OA (6%), and persistent pain or stiffness (5%). The most common re-operations after PFA were conversion to TKA, revision of PFA components, lateral releases, open or arthroscopic debridement, manipulations under anesthesia, and bony and/or soft tissue extensor mechanism re-alignment procedures. In our study, 11% of patients treated with PFA underwent a revision arthroplasty, with 4% undergoing revision PFA and 7% undergoing conversion to TKA.

Our comparison of patients who were treated with second-generation PFA designs versus TKA showed no difference in the rate of complications, re-operation, or revision arthroplasty. Additionally, length of follow-up did not significantly influence any of these outcomes when comparing second-generation PFA and TKA.

These observations provide support for the use of current PFA designs. The mechanical complications and subsequent re-operations that affected first-generation PFA designs appear to be of less concern with proper patient selection, meticulous surgical technique, current implant designs and peri-operative care. While it is difficult to predict the survivorship of current PFA designs, it is our expectation that patient selection will continue to be a critical component in determining long-term results. The potential benefit of providing pain relief while preserving the tibiofemoral articulations makes PFA a promising treatment option.

Introduction

Epidemiologic studies indicate that isolated patellofemoral (PF) arthritis affects nearly 10% of the population over 40 years of age, with a predilection for females. A small percentage of patients with PF arthritis may require surgical intervention. Surgical options include non-arthroplasty procedures (arthroscopic debridement, tibial tubercle unloading procedures, cartilage restoration, and patellectomy), and patellofemoral or total knee arthroplasty (PFA or TKA). Historically, non-arthroplasty surgical treatment has provided inconsistent results, with short-term success rates of 60–70%, especially in patients with advanced arthritis. Although TKA provides reproducible results in patients with isolated PF arthritis, it may be undesirable for those interested in a more conservative, kinematic-preserving approach, particularly in younger patients, who may account for nearly 50% of patients undergoing surgery for PF arthritis. Due to these limitations, patellofemoral arthroplasty (PFA) has become utilised more frequently over the past two decades.

Isolated patellofemoral arthritis is not an uncommon problem, with no clear consensus on treatment. Nonoperative and many forms of operative treatments have failed to demonstrate long-term effectiveness in the setting of advanced arthritis. Total knee arthroplasty (TKA) has produced excellent results, but many surgeons are hesitant to perform TKA in younger patients with isolated patellofemoral arthritis. In properly selected patients, patellofemoral arthroplasty (PFA) is an effective procedure with good long-term results. Contemporary PFA prostheses have eliminated many of the patellar maltracking problems associated with older designs, and short-term results, as described here, are encouraging. Long-term outcome and prospective trials comparing TKA to PFA are needed.

The aim of this study was to assess the increase in the anterior diameter of the knee and the impact of this increase on the range of motion and function of the knee.

Twenty-eight patients (34 knees) who underwent Patello-femoral replacement with FPV (Wright Medical) prosthesis between 2005 and 2009 who were identified retrospectively and analyzed using chart and radiological review. Oxford and AKSS knee-scores were gathered prospectively pre-operative and at follow-up.

Trochlear height was measured using lateral radiograph. Trochlear height was compared pre and postoperatively. Patellar height was also measured in preoperative and postoperative skyline view and was compared. The range of movement at six weeks and the Oxford and American knee society knee scores at six months postoperatively were noted. Association between increased anterior height and improved range of motion was studied.

All but three-knees regained full knee extension. Postoperative mean range of flexion of the knee joint was 116 degrees. The mean Oxford knee and the mean American Knee Society Knee Scores significantly improved post-operatively

The trochlear height was increased by 4mms. Patellar height was also increased by 3 mms resulting in average total increase of 7 mms in the anterior-posterior diameter of the knee. We found no relationship between range of motion of the knee and the increase in the anterior-posterior diameter. We found a negative correlation between increase in the antero-posterior and preoperative trochlear and patellar height.

We conclude that FPV Patello-femoral replacement results in correct anatomical reconstruction of the trochlear height rather than ‘overstuffing’ of the patellofemoral joint which can lead to stiffness and failure of resolution of pain post-operatively. This should in turn result in durable improvements in pain and function.

The aim of this study was to analyse the kneeling ability of patients before and at one and two years after total (TKR), unicompartmental (UKR) and selective patellofemoral (PFR) knee arthroplasty, for osteoarthritis. Method: Data was prospectively collected on 253 knees, which underwent either TKR, UKR or PFR. A kneeling score was obtained by analysis of the relevant section of the Oxford Knee Score questionnaire. Scores were obtained pre-operatively and at 1 and 2 years post-operatively (minimum score 0, maximum 4). Absolute values and change following arthroplasty were recorded. Correlations with pain and other knee functions were also made.

Results: Kneeling ability prior to surgery was poor in all three groups (mean score 0.7 out of 4) and improved significantly after surgery (mean score at one year 1.13 and at two years 1.46 out of 4) (P< 0.001). Kneeling ability at 1 year differed significantly with operation type (p = 0.02). Kneeling ability improved most in the first year post-operatively but continued to improve between one and two years although the final function was still not good. Kneeling ability was best in UKR and worst in PFR, with the difference between these prostheses being statistically significant (P< 0.001).

Conclusion: Kneeling ability in osteoarthritic knees is poor but improves with arthroplasty. However, the majority of patients will still have difficulty kneeling.

Introduction

The optimal treatment for isolated patello-femoral arthritis is unclear. Patello-femoral arthroplasty (PFA) may offer superior knee function in isolated patello-femoral osteoarthritis compare to TKA. The literature is controversial for patient outcomes in PFA. Some reports showed improved outcomes while others were disappointing. We assessed our outcomes to try to identify causes for poor outcomes.

Patellofemoral unicompartmental joint replacement is a controversial subject with a relatively small evidence base. Of the 50,000 total knee arthroplasties performed each year in the UK, approximately 10% are performed for predominantly patellofemoral arthritis. There are several patellofemoral unicompartmental prostheses on the market with the National Joint Registry recording 745 such prostheses used in 2007. Most evidence in favour of this procedure comes from experience with the Avon prosthesis (Stryker) predominantly from designer-surgeons. The FPV patellofemoral joint replacement (Wright Medical) has been in use in Europe for several years. The instruments have recently been redesigned and the device marketed in the UK. In 2007 the FPV had 5.9% market share (n=44). We present our early experience with the FPV patellofemoral joint replacement, which to our knowledge, is the first clinical outcome series for this prosthesis. 33 consecutive FPV joint replacements in 29 patients were performed between April 2007 and September 2009 for unicompartmental patellofemoral OA. All cases were performed or directly supervised by the senior author. Results are presented with a minimum follow-up of six months. Oxford and American Knee Society scores (AKSS) were obtained on all patients preoperatively and at subsequent outpatient visits. Mean preoperative AKSS knee score was 49.7 points and postoperative scores at 6 months and 1 year were 82.5 and 86.4 respectively. Mean Oxford score preoperatively was 30.4 (37%) and at 6 months and 1 year were 21.3 (56%) and 11.2 (77%) respectively. There were no complications related to the implant. One knee required a secondary open lateral release due to inadequate balancing at the index procedure. Further medium to long-term follow up data are required, but our initial experience with this device is encouraging

Patellofemoral unicompartmental joint replacement is a controversial subject with a relatively small evidence base. Of the 50,000 total knee arthroplasties performed each year in the UK, approximately 10% are performed for predominantly patellofemoral arthritis. There are several patellofemoral unicompartmental prostheses on the market with the National Joint Registry recording 745 such prostheses used in 2007. Most evidence in favour of this procedure comes from experience with the Avon prosthesis (Stryker) predominantly from designer-surgeons. The FPV patellofemoral joint replacement (Wright Medical) has been in use in Europe for several years. The instruments have recently been redesigned and the device marketed in the UK. In 2007 the FPV had 5.9% market share (n=44). We present our early experience with the FPV patellofemoral joint replacement, which to our knowledge, is the first clinical outcome series for this prosthesis. 33 consecutive FPV joint replacements in 29 patients were performed between April 2007 and September 2009 for unicompartmental patellofemoral OA. All cases were performed or directly supervised by the senior author. Results are presented with a minimum follow-up of six months. Oxford and American Knee Society scores (AKSS) were obtained on all patients preoperatively and at subsequent outpatient visits. Mean preoperative AKSS knee score was 49.7 points and postoperative scores at 6 months and 1 year were 82.5 and 86.4 respectively. Mean Oxford score preoperatively was 30.4 (37%) and at 6 months and 1 year were 21.3 (56%) and 11.2 (77%) respectively. There were no complications related to the implant. One knee required a secondary open lateral release due to inadequate balancing at the index procedure. Further medium to long-term follow up data are required, but our initial experience with this device is encouraging

The primary aim of this study was to compare the knee specific functional outcome of partial compared with total knee replacement (TKR) for the management of patellofemoral osteoarthritis. Fifty-four consecutive Avon patellofemoral replacements were identified and propensity score matched to a group of 54 patients undergoing a TKR with patella resurfacing for patellofemoral osteoarthritis. The Oxford knee score (OKS), the Short Form (SF-) 12 and patient satisfaction were collected (mean follow up 9.2 years). Survival was defined by revision or intention to revise. There was no significant difference in the OKS (p>0.60) or SF-12 (p>0.28) between the groups. The TKR group was significantly less likely to be satisfied with their knee (95.1% versus 78.3%, OR 0.18, p=0.03). Length of stay was significantly (p=0.008) shorter for the Avon group (difference 1.8 days, 95% CI 0.4 to 3.2). The 10 year survival for the Avon group was 92.3% (95% CI 87.1 to 97.5) and for the TKR group was 100% (95% CI 93.8 to 100). There was no statistical difference in the survival rate (Log Rank p=0.10). The Avon patellofemoral replacement have a shorter length of stay with a functional outcome and satisfaction rate that is equal to that of TKR. The benefits of the Avon need to be balanced against the increased rate of revision when compared with TKR

Abstract. Background. Recurrent patellar dislocation in combination with cartilage injures are difficult injuries to treat with confounding pathways of treatment. The aim of this study is to compare the clinical and functional outcomes of patients operated for patellofemoral instability with and without cartilage defects. Methods. 82 patients (mean age-28.8 years) with recurrent patellar dislocations, who underwent soft-tissue or bony procedures, were divided into 2 matched groups (age, sex, follow-up and type of procedure) of 41 each based on the presence or absence of cartilage defects in patella. Chondroplasty, microfracture, osteochondral fixation or AMIC-type procedures were done depending on the nature of cartilage injury. Lysholm, Kujala, Tegner and Subjective Knee scores of both groups were compared and analysed. Complications and return to theatre were noted. Results. With a mean follow-up of 8 years (2 years-12.3 years), there was a significant improvement observed in all the mean post-operative Patient Reported Outcome Measures (p<0.05) of both the groups, as compared to the pre-operative scores. Comparing the 2 groups, post-operative Lysholm, Kujala and Subjective knee scores were significantly higher in patients operated without cartilage defects (p<0.05). 3 patients operated for PFJ instability with cartilage defects had to undergo patellofemoral replacement in the long term. Odds ratio for developing complications is 2.6 for patients operated with cartilage defects. Conclusion. Although there is a significant improvement in the long term outcome scores of patients operated for recurrent patellar dislocation with cartilage defects, the results are significantly inferior as compared to those without cartilage defects, along with a higher risk of developing complications and returning to theatre. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Background. Recurrent patellar dislocation in combination with cartilage injures are difficult injuries to treat with confounding pathways of treatment. The aim of this study is to compare the clinical and functional outcomes of patients operated for patellofemoral instability with and without cartilage defects. Methods. 82 patients (mean age-28.8 years) with recurrent patellar dislocations, who underwent soft-tissue or bony procedures, were divided into 2 matched groups (age, sex, follow-up and type of procedure) of 41 each based on the presence or absence of cartilage defects in patella. Chondroplasty, microfracture, osteochondral fixation or Autologous Matrix-Induced Chondrogenesis(AMIC)-type procedures were done depending on the nature of cartilage injury. Lysholm, Kujala, Tegner and Subjective Knee scores of both groups were compared and analysed. Complications and return to theatre were noted. Results. With a mean follow-up of 8 years (2 years-12.3 years), there was a significant improvement observed in all the mean post-operative Patient Reported Outcome Measures (p<0.05) of both the groups, as compared to the pre-operative scores. Comparing the 2 groups, post-operative Lysholm, Kujala and Subjective knee scores were significantly higher in patients operated without cartilage defects (p<0.05). 3 patients operated for patellofemoral instability with cartilage defects had to undergo patellofemoral replacement in the long term. Odds ratio for developing complications is 2.6 for patients operated with cartilage defects. Conclusion. Although there is a significant improvement in the long term outcome scores of patients operated for recurrent patellar dislocation with cartilage defects, the results are significantly inferior as compared to those without cartilage defects, along with a higher risk of developing complications and returning to theatre

Introduction. The trochlea of a typical patellofemoral replacement or anterior flange of a total knee replacement usually extends past the natural trochlea and continues onto the femoral anterior cortex. One reason for this is that it allows a simple patella button to be permanently engaged in the trochlea groove in an attempt to ensure stability. On the natural patella, the apex helps to guide it into the trochlea groove as the knee moves from full extension into flexion. The aim is to study whether a generalised patella can be created that is close in form to a healthy patella. Method. MRI scans were taken of 30 patellae. Characteristics of these patellae (height, width, thickness, apex angle) were measured. The apex angle was found to be similar between patellae (mean=126 degrees, sd = 8.8), as were the ratios between height and width (mean width/height = 1.05, sd = 0.07) and between thickness and width (mean width/thickness = 1.8, sd = 0.19). These patellae were then segmented to create a surface including cartilage, resulting in 30 STL (stereolithography) files in which the surfaces are represented by triangle meshes. To design the average patella the individual patellae were aligned to a standard frame of reference by placing a set of landmarks on the proximal/distal, medial/lateral and anterior/posterior extents of each (fig.1). The vertical axis was defined as passing parallel to the proximal/distal points and the horizontal as passing parallel to the medial/lateral points when looking along the computed vertical axis. The origin centre of the frame of reference was chosen to be mid-way between these points. The mean width was then computed and each patella scaled linearly around the origin to give them all equal width. All the aligned patellae were then averaged together to provide a composite cartilaginous patella. The averaging process was achieved by taking one patella as a seed. The patella chosen for seed was that whose parameters were closest to the average width, height and thickness. An approximately normal vector was passed a point ‘P’ on the seeds, and the points at which these intersected the other models were then determined. The closest intersection point to ‘P’ on each model was chosen and these averaged together. ‘P’ is then replaced in the model with this average point. The averaging process then continues with all the remaining points on the seed model in the same manner to build the average models. Results and Discussion. The mean patella was compared with individual patellae. This comparison was performed by taking each point on the mean patella and finding the closest point on individual patellae - a colour coded map of differences was obtained (fig.2) along with a mean of the absolute difference for each patella. The absolute mean difference ranged from 0.56mm to 1.33mm, averaging at 0.85mm. This shows a reasonable fit between the average patella and each individual example, raising the possibility of using the average shape in future research to develop anatomical patellofemoral replacements and for planning patella resurfacing

INTRODUCTION. Patellofemoral joint (PFJ) replacement is a successful treatment option for isolated patellofemoral osteoarthritis. With this approach only the involved joint compartment is replaced and the femoro-tibial joint remains intact. Minimizing periprosthetic bone loss, which may occur due to the stress shielding effect of the femoral component, is important to insure long-term outcomes. The objective of this study was to investigate, using finite element analyses, the effects of patellofemoral replacement on the expected stress distribution of the distal femur eventually leading to changes in bone density. METHODS. MRI images of a healthy knee were acquired, segmented and reconstructed into a 3D physiological model of the bony and cartilaginous geometries of distal femur and patella with patellar tendon and insertion of the quadriceps tendon. This model was modified to include PFJ replacements with either a Journey PFJ or a Richards II PFJ prosthesis, and a Genesis II TKA (Smith&Nephew, Memphis, TN). The prosthetic components were incorporated in the intact model based on the manufacturer's instructions or previously described surgical techniques (Figure 1). Cortical bone was modeled with orthotropic properties, while homogeneous linear isotropic elasticity was assumed for trabecular bone, cartilage, cement and femoral components materials. The patellar tendon was given Neo-Hookean behavior. UHMWPE patellar buttons for all designs were assigned non-linear elasto-plastic material. The simulated motion consisted of a 10 second loaded squat, starting from 0° until a flexion angle of 120° matching experimental kinematics tests performed in previous in-vitro analysis on physiological cadaveric legs [1-2]. The patella model was constrained fixing the distal part of the patellar ligament and applying a quadriceps force distributed on the quadriceps insertion on the proximal surface of the patella. During the dynamic simulation the average Von Mises stress was calculated in two regions of interest (ROI) defined in the femoral bone: one anterior and one proximal. The location of the ROIs was defined to fit the same regions as used in a previous bone mineral density analysis following patellofemoral arthroplasty (height 1cm, length 1cm). RESULTS AND DISCUSSION. Overall, the average bone stresses in both ROIs increased with flexion angle. Maximal stresses during squat were reached at 90° flexion angle, (2.8–3.8 MPa for the anterior ROI and 1.4–1.6 MPa for the proximal ROI). Mean stresses in the proximal ROI were similar for both PFJ designs and the physiological model, and slightly lower for the TKA. Between 80° and 120°, anterior ROI bone stresses for Journey PFJ design were comparable to the physiological knee, while reduced by almost 25% for the other designs (Figure 1). These results suggest a different stress-shielding behavior depending on design geometry and material properties. CONCLUSIONS. This study evaluated periprosthetic bone stress distributions of different patellofemoral replacements. The numerical analyses of physiological and replaced knee models predicted a decrease in stress behind the anterior flange of the femoral component for some designs. This reduction was dependent on prosthesis design geometry and materials properties

It is important to remember that osteoarthritis is a noninflammatory condition that can affect 1, 2 or all 3 compartments of the knee. Moreover, this disease is a continuum from very mild to very severe involvement of the soft tissue, articular cartilage and bone. For this reason, a variety of nonsurgical and surgical options are indicated. The rheumatologist and/or orthopedist must understand the stage of the disease and fit that both to the pathology, age, activity level, and functional needs of the patient. For that reason, each of the options discussed today have an indication. The important issue about tricompartmental replacement is that we have improved technology and technique and the indications of today are broader than those of 20 years ago. Hopefully, they will continue to evolve both in terms of materials and instruments. The American Rheumatologic Association (ARA) has stated that joint replacement has been the major improvement in the care of the arthritic patient. The tricompartmental solution is the treatment of choice in patients with inflammatory arthritis such as rheumatoid arthritis as well as the solution in osteoarthritic patients with tricompartmental disease. There is an indication for osteotomy, unicompartmental replacement and perhaps patellofemoral replacement. I think the next frontier will be to find disease modifying osteoarthritic drugs (DMOADS) that will provide disease intervention as the DMARDs have done in rheumatoid arthritis. Moreover, cartilage repair combined with osteotomy will hopefully allow us to prevent progression of this disease

Background. Patellofemoral replacement is an established intervention in selected patients with severe isolated patellofemoral osteoarthritis. FPV (Wright Medical, UK) is a third generation patellofemoral arthroplasty implant and is the second most used after AVON in National Joint Registry for England and Wales. Reports of survivorship and functional of this implant are scarce in literature. Aim. Evaluation of functional outcome and survivorship following FPV patellofemoral arthroplasty. Methods. FPV patellofemoral arthroplasties performed by multiple surgeons in a teaching hospital between 2004- 2008 were followed up (mean 3.5 years) with radiographs and functional outcome scores (Oxford Knee Score, Kujala score and Fulkerson score) and survival analysis was performed. Results. One hundred consecutive FPV patellofemoral joint arthroplasties were performed during this period in 81 patients (70 female). The mean age at the time of the surgery was 62 years (Range 44-82 years). Latest functional outcome was Oxford Knee Score (mean 29 out of 48), Kujala score (mean54 out of 100) and Fulkerson score (mean 65 out of 100). Three patients were lost to follow up due to death, none of these had been revised. There were 14 revisions, twelve of which were converted to total knee replacement and two revised to further FPV. The cumulative five year survival analysis was 84.1%. Conclusion. Although inferior to total knee replacement results, the results from our study are comparable to those in the national joint registry. FPV patellofemoral arthroplasty gives satisfactory initial results and can be considered as a bone ligament sparing option in patients with isolated patellofemoral arthritis which can be readily be revised to total knee replacement if necessary

To progress to a same day surgery program for arthroplasty, it is important that we examine and resolve the issues of why patients stay in the hospital. The number one reason is fear and anxiety for the unknown and for surgical pain. The need for hospital stay is also related to risk arising from comorbidities and medical complications. Patients also need an extended stay to manage the side effects of our treatment, including after-effects of narcotics and anesthesia, blood loss, and surgical trauma. The process begins pre-operatively with an appropriate orthopaedic assessment of the patient and determination of the need for surgery. The orthopaedic team must motivate the patient, and ensure that the expectations of the patient, family and surgeon are aligned. In conjunction with our affiliated hospitalist group that performs almost all pre-admission testing, we have established guidelines for patient selection for outpatient arthroplasty. The outpatient surgical candidate must have failed conservative measures, must have appropriate insurance coverage, and must be functionally independent. Previous or ongoing comorbidities that contraindicate the outpatient setting include: cardiac – prior revascularization, congestive heart failure, or valve disease; pulmonary – chronic obstructive pulmonary disease, or home use of supplemental oxygen; untreated obstructive sleep apnea – BMI >40 kg/m2; renal disease – hemodialysis or severely elevated serum creatinine; gastrointestinal – history or post-operative ileus or chronic hepatic disease; genitourinary – history of urinary retention or severe benign prostatic hyperplasia; hematologic – chronic Coumadin use, coagulopathy, anemia with hemoglobin <13.0 g/dl, or thrombophilia; neurological – history of cerebrovascular accident or history of delirium or dementia; solid organ transplant. Pre-arthroplasty rehabilitation prepares the patient for peri-operative protocols. Patients meet with a physical therapist and are provided with extensive educational materials before surgery to learn the exercises they will need for functional recovery. Enhancement of our peri-operative pain management protocols has resulted in accelerated rehabilitation. The operative intervention must be smooth and efficient, but not hurried. Less invasive approaches and techniques have been shown to decrease pain, reduce length of stay, and improve outcomes, especially in the short term. In 2014, 385 primary partial knee arthroplasty procedures (7 patellofemoral replacement, 13 lateral, and 365 medial) were performed by the author and his 3 associates at an outpatient surgery center. Of those, 348 (95%) went home the same day while 17 (5%) required an overnight stay, with 11 for convenience related to travel distance or later operative time and 6 for medical issues. Outpatient arthroplasty is safe, it's better for us and our patients, and it is here now. In an outpatient environment the surgeon actually spends more time with the patients and family in a friendly environment. Patients feel safe and well cared for, and are highly satisfied with their arthroplasty experience