Introduction. In 1976 the senior author presented to the Associations the results of patellectomy with satisfactory results in less than 50% of cases. In 1989 with the increasing success of TKR we started a prospective study of the Lubinus prosthesis for patellofemoral arthritis. After 4 years results were not satisfactory. The main causes of failure were mal-tracking and instability leading to polythene button wear, and arthritic disease progression. A new prosthesis was designed in 1996 to correct these problems. Methods. We have prospectively recorded the results of a consecutive cohort of 537 Avon arthroplasties. The outcomes have been assessed with survivorship, pain, Oxford and WOMAC scores. We have identified 24 patients from our own series and from tertiary referrals who have persistent pain, due to technical error rather than arthritic disease progression. Results. Survivorship for revision at 5 Years was 96% and overall there were 63 revisions. Results over 10 years show excellent and consistent improvement in both pain and function as judged by the median WOMAC score and are similar to patients with a TKR. The pain score improved from 45% (16) to 87% (7.5), the function score improved from 50% (21) to 80% (12.5). The Oxford score improved from 39.5% (19) to 69% (33). Symptomatic arthritic disease progression occurred in 12% of cases causing recurrent pain. Persistent non-arthritic pain was due to three main causes: minor misplacement of the femoral or patella components or over sizing, leading to retinacular impingement and over stuffing of the patellofemoral joint. Conclusion. This prosthesis has shown consistently good results with few problems over 14 years. New instruments will increase the accuracy of insertion and attention to detail in the performance of the operation will prevent problems. Disease progression remains the main cause of failure and strict pre-operative criteria are essential

Isolated patellofemoral osteoarthritis can be a disabling disease. When conservative treatment fails, surgical options can be unpredictable and may be considered too aggressive for middle-aged and active people. We analysed the clinical and radiological results of a new coronal osteotomy involving thinning of the patella in a selected group of patients with isolated patellofemoral osteoarthritis. Since 1991, 31 patients (35 knees) have been treated, of whom 34 were available for follow-up at a mean of 9.1 years. The Knee Society Score, the Patellar score and the Short-form-36 questionnaire were used for clinical evaluation. We also examined the radiological features to confirm bone consolidation and assess the progression of osteoarthritis. A significant improvement in the functional scores and radiological parameters was noted. All patients except one were satisfied with the operation. Radiological progression of the patellofemoral osteoarthritis was slowed but radiological femorotibial osteoarthritis progressed in 23 (65%) cases, with a total knee replacement becoming necessary in four cases without technical problems in resurfacing the patella. We compared the results with other forms of surgical treatment reported in the literature.

This treatment offers good clinical and radiological results, presenting an alternative method of managing patellofemoral osteoarthritis.

Background

The goal of patellofemoral arthroplasty (PFA) is to replace damaged cartilage, and to correct underlying deformities, to reduce pain and prevent maltracking. We aimed to determine how PFA modifies patellar height, tilt, and tibial tuberosity to trochlear groove (TT-TG) distance. The hypothesis was that PFA would correct trochlear dysplasia or extensor mechanism malalignment.

Patellofemoral osteoarthritis (PFOA) affects 32% men and 36% women over the age of 60years and is associated with anterior knee pain, stiffness, and poor mobility. Patellofemoral arthroplasty (PFA) is a bone-sparing treatment for isolated PFOA. This study set out to investigate the relationship between patient-related outcome measures (PROMs) and measurements obtained from gait analysis before and after PFA. There are currently no studies relating to gait analysis and PFA available in the literature

A prospective cohort study was conducted of ten patients known to have isolated PFOA who had undergone PFA compared to a gender and age matched control group. The patients were also asked to complete questionnaires (Oxford knee score (OKS), EQ-5D-5L) before surgery and one year after surgery. Gait analysis was done on an instrumented treadmill comparing Ground reaction force parameters between the control and pre and post-operative PFA patients

The average age 60 (49–69) years with a female to male ratio of 9:1. Patient and healthy subjects were matched for age and gender, with no significant difference in BMI. Post-op PFA improvement in gait seen in ground reaction force at 6.5km/h. Base support difference was statistically significant both on the flat P=0.0001 and uphill P=0.429 (5% inclination) and P=0.0062 (10% inclination). PROMS response rate was 70%(7/10) pre-operative and 60%(6/10) post-operative. EQ-5D-5L scores reflected patient health state was better post-operatively.

This study found that gait analysis provides an objective measure of functional gait and reflected by significant quality-of-life improvement of patients post PFA. Literature lacks studies relating to gait-analysis and PFA. Valuable information provided by this study highlights that PFA has a beneficial outcome reflected by PROMs and improvement in vertical ground reaction force and gait

Further research is needed to assess how care-providers may use gait-analysis as part of patient care plans for PFOA patients.

Isolated patellofemoral arthritis is a common condition and there are varying opinions on the most effective treatments. Non-operative and operative treatments have failed to demonstrate effective long-term treatment for those in an advanced stage of the condition. Newer designs and increased technology in patellofemoral replacement (PFR) have produced more consistent outcomes. This has led to a renewed enthusiasm for this procedure. Newer PFR prostheses have addressed the patellar maltracking issues plaguing some of the older designs. Short-term results with contemporary prostheses and new technology are described here. . Cite this article: Bone Joint J 2013;95-B, Supple A:124–8

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.

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.

Aims. A pragmatic, single-centre, double-blind randomized clinical trial was conducted in a NHS teaching hospital to evaluate whether there is a difference in functional knee scores, quality-of-life outcome assessments, and complications at one-year after intervention between total knee arthroplasty (TKA) and patellofemoral arthroplasty (PFA) in patients with severe isolated patellofemoral arthritis. Methods. This parallel, two-arm, superiority trial was powered at 80%, and involved 64 patients with severe isolated patellofemoral arthritis. The primary outcome measure was the functional section of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at 12 months. Secondary outcomes were the full 24-item WOMAC, Oxford Knee Score (OKS), American Knee Society Score (AKSS), EuroQol five dimension (EQ-5D) quality-of-life score, the University of California, Los Angeles (UCLA) Physical Activity Rating Scale, and complication rates collected at three, six, and 12 months. For longer-term follow-up, OKS, EQ-5D, and self-reported satisfaction score were collected at 24 and 60 months. Results. Among 64 patients who were randomized, five patients did not receive the allocated intervention, three withdrew, and one declined the intervention. There were no statistically significant differences in the patients’ WOMAC function score at 12 months (adjusted mean difference, -1.2 (95% confidence interval -9.19 to 6.80); p = 0.765). There were no clinically significant differences in the secondary outcomes. Complication rates were comparable (superficial surgical site infections, four in the PFA group versus five in the TKA group). There were no statistically significant differences in the patients’ OKS score at 24 and 60 months or self-reported satisfaction score or pain-free years. Conclusion. Among patients with severe isolated patellofemoral arthritis, this study found similar functional outcome at 12 months and mid-term in the use of PFA compared with TKA. Cite this article: Bone Joint J 2020;102-B(3):310–318

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. Incidence. Isolated patellofemoral arthritis occurs in as many as 11% of men and 24% of women older than age 55 years with symptomatic osteoarthritis (OA) of the knee; Isolated patellofemoral arthritis found in 9.2% of patients older than age 40 years; 7% to 19% of patients experience residual anterior knee pain when TKA is done for isolated patellofemoral arthritis. Imaging. Weight bearing AP radiographs as supine radiographs can underestimate the extent of tibiofemoral arthritis; Midflexion posteroanterior radiographs to rule out posterior condylar wear; Lateral radiographs to identify the presence or absence of patella alta or baja; Axial radiographs identify the presence of trochlear dysplasia, patellar tilt or subluxation, and extent of patellofemoral arthritis; Magnetic resonance imaging and arthroscopic photographs should be reviewed if available. Indications. Osteoarthritis limited to the patellofemoral joint; Symptoms affecting daily activity referable to patellofemoral joint degeneration unresponsive to lengthy nonoperative treatment; Posttraumatic osteoarthritis; Extensive Grade-III chondrosis; Failed extensor unloading surgical procedure; Patellofemoral malalignment/dysplasia-induced degeneration. Contraindications. No attempt at nonoperative care or to rule out other sources of pain; Arthritis of greater than Grade 1 involving tibiofemoral articulation; Systemic inflammatory arthropathy; Osteoarthritis/chondrosis of the patellofemoral joint of Grade 3 or less; Patella baja; Uncorrected patellofemoral instability or malalignment; Uncorrected tibiofemoral mechanical malalignment; Active infection; Evidence of chronic regional pain syndrome or evidence of psychogenic pain; Fixed loss of knee range of motion, minimum 10–110 degrees ROM. Results. Majority of failures related to patellar instability from uncorrected patellar malalignment, soft-tissue imbalance, or component malposition; With improved implant designs tibiofemoral arthritis has become the primary source of failure; Failure from component subsidence or loosening occurring in <1% of knees. Our Series. Retrospective review 34 patients, 40 knees average 30 month follow-up using Natural Knee II Patello-femoral Joint System (Zimmer, Warsaw, IN); Average age 61, ranging from 34–84 years of age; Average subset KOOS scores were 93 for pain, 94 for symptoms, 94 for ADL's, 70 for sports and recreation, 82 for quality of life; Average pre-operative Tegner score 2.6, increasing to 4.7 post-operatively; 38/40 survival over 30 months with the two failures undergoing revision for traumatic injuries; No revisions to TKA; At most recent follow-up no progression of OA to involve tibiofemoral compartments; No evidence of component loosening

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

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

Isolated patellofemoral arthritis is a common, often debilitating, condition with a number of treatment options available. Avon patellofemoral arthroplasty has been practiced in our district general hospital setting with favourable results. Previous studies have been mainly from the pioneering Bristol centre. We present the findings of the intermediate results of Avon patellofemoral arthroplasty (PFA) used in the treatment of isolated patellofemoral arthritis. From 1999 until August 2006, 63 Avon PFA were carried out in 46 patients by a single surgeon. We analysed retrospectively the patient case records and collected data regarding clinical, radiological findings along with patient satisfaction scores using the Oxford knee questionnaire. 45/46 (98%) patients had primary patellofemoral (PF) arthritis. 17/46 (36%) patients suffered from bilateral PF arthritis. The average duration of follow up was 5 years (3 months to 7 years). There were 7 males and 39 females with a median age of 63 years. The average range of movement was 120° (90°–140°). There was no observable radiological loosening. There was a reduction in the Oxford knee score from 33 (21–48) to 17 (1–44). Complications of the procedure included superficial infections (2/46), transient foot drop (1/46), and persistent pain (2/46). Further surgery requiring lateral release was carried out in 2/46 patients. To date, none of the cases have required revision due to progression of arthritis. Patients reported high level of satisfaction following the procedure. Avon PFA is an effective procedure for the treatment of isolated patellofemoral arthritis, with a low rate of complications and good functional results. To our knowledge, this is the first study in UK outside Bristol, presenting the findings of intermediate results of Avon PFA

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

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 low contact stress patellofemoral replacement consists of a trochlear component and a modular patellar component which has a metal-backed mobile polyethylene bearing. We present the early results of the use of this prosthesis for established isolated patellofemoral arthritis in 51 consecutive patellofemoral replacements in 35 patients. The mean follow-up was 25 months (5 to 60). The estimated survival rate at three years was 63% (95% confidence interval 47 to 80) with revision as the endpoint and 46% (95% confidence interval 30 to 63) with revision and ongoing moderate or severe pain as the endpoint. The early results of the use of the low contact stress patellofemoral replacement are disappointing with a high rate of revision. We cannot therefore recommend its use

We report the mid-term results of a new patellofemoral arthroplasty for established isolated patellofemoral arthritis. We have reviewed the experience of 109 consecutive patellofemoral resurfacing arthroplasties in 85 patients who were followed up for at least five years. The five-year survival rate, with revision as the endpoint, was 95.8% (95% confidence interval 91.8% to 99.8%). There were no cases of loosening of the prosthesis. At five years the median Bristol pain score improved from 15 of 40 points (interquartile range 5 to 20) pre-operatively, to 35 (interquartile range 20 to 40), the median Melbourne score from 10 of 30 points (interquartile range 6 to 15) to 25 (interquartile range 20 to 29), and the median Oxford score from 18 of 48 points (interquartile range 13 to 24) to 39 (interquartile range 24 to 45). Successful results, judged on a Bristol pain score of at least 20 at five years, occurred in 80% (66) of knees. The main complication was radiological progression of arthritis, which occurred in 25 patients (28%) and emphasises the importance of the careful selection of patients. These results give increased confidence in the use of patellofemoral arthroplasty

Aim. Patellofemoral Arthroplasty (PFA) prosthesis with asymmetric trochlear component was introduced as an improvement from existing designs for surgical treatment of symptomatic isolated patellofemoral arthritis. The purpose of this study was to evaluate midterm results in patients who underwent PFA procedure using such prosthesis. Methods. Our study involved a continuous retrospective cohort of patients who underwent PFA using Journey PFJ with asymmetric trochlear component, performed between June 2007 and October 2018 at a non-designer centre. The Patient Reported Outcome Measures and patient satisfaction questionnaires were collected for final evaluation. Results. A total of 128 PFA performed on 96 patients were evaluated. All patients were under regular follow up, and no patient was lost to follow up. Eighteen patients underwent simultaneous bilateral procedures, and 14 patients underwent PFA of the contralateral knee later. Median age at the time of surgery was 59 years (interquartile range 53 – 66 years); the median follow up period was 6 years (interquartile range 2.5 – 7 years). The Oxford Knee Score showed improvement from a median of 18 to 37. There were statistically significant improvements in functional outcome scores. Beverland satisfaction questionnaire revealed that 22.1 % (19/86) were ‘Very happy’ and 39.5% (34/86) were ‘Happy’ following the procedure. Four knees were revised to Total Knee Arthroplasty for reasons not related to the implant. The cumulative survival estimated by the Kaplan-Meier method was 95.2% (95% confidence interval: 90.4%– 99.9%). Conclusion. This series of patients who underwent PFA with the asymmetric trochlear component has shown promising mid-term results with no implant related complications

Objective. Open-wedge high tibial osteotomy (OWHTO) involves performing a corrective osteotomy of the proximal tibia and removing a wedge of bone to correct varus alignment. Although previous studies have investigated changes in leg length before and after OWHTO using X-rays, none has evaluated three-dimensional (3D) leg length changes after OWHTO. We therefore used 3D preoperative planning software to evaluate changes in leg length after OWHTO in three dimensions. Methods. The study subjects were 55 knees of 46 patients (10 men and 36 women of mean age 69.9 years) with medial osteoarthritis of the knee or osteonecrosis of the medial femoral condyle with a femorotibial angle of >185º and restricted range of motion (extension <–10º, flexion <130º), excluding those also suffering from patellofemoral arthritis or lateral osteoarthritis of the knee. OWHTO was simulated from computed tomography scans of the whole leg using ZedHTO 3D preoperative planning software. We analyzed the hip-knee-ankle angle (HKA), flexion contracture angle (FCA), mechanical medial proximal tibial angle (mMPTA), angle of correction, wedge length, 3D tibial length, 3D leg length, and 3D increase in leg length before and after OWHTO. We also performed univariate and multivariate analysis of factors affecting the change in leg length (preoperative and postoperative H-K-A angle, wedge length, and correction angle). Results. Mean HKA increased significantly from −4.7º ± 2.7º to 3.5º ± 1.3º, as did mean mMPTA from 83.7º ± 3.3º to 92.5º ± 3.0º (p <0.01). Mean FCA was 4.7º ± 3.6° preoperatively and 4.8º ± 3.3º postoperatively, a difference that was not significant (p = 0.725). The mean correction angle was 9.1º ± 2.8º and the mean wedge length was 9.4º ± 3.2º mm. Mean tibial length increased significantly by 4.7 ± 2.3 mm (p <0.01), and mean leg length by 5.6 ± 2.8 mm (p <0.01). The change in leg length was strongly correlated with wedge length (R = 0.846, adjusted R. 2. = 0.711, p <0.01). Discussion and Conclusion. Mean 3D leg length after OWHTO increased significantly by 5.4 ± 3.1 mm. A difference in leg length of >5 mm is believed to affect back pain and gait abnormalities, and changes in leg length must therefore be taken into consideration. The 3D dimensional change in leg length was strongly correlated with wedge length, and could be predicted by the formula (change in leg length in mm) = [(wedge length in mm) ×0.75) − 1.5]. For any figures or tables, please contact authors directly

To resurface or not to resurface the patella… that is the question. It all comes down to where you practice. It is controversial in that there is a risk of possible complications from resurfacing versus the potential for simply having complaints of pain which may supposedly arise from the anterior knee stemming from the unresurfaced patella. The evolution of more favorable anatomic femoral component designs which are very friendly to the patellofemoral articulation have resulted in lower patella resurfacing complications. The insertion of appropriately externally rotated tibial and femoral components, if not reducing anterior knee pain, have certainly minimised the risk of resurfaced patella complications. Also, with current surgical techniques of component insertion, the lateral release rate is extremely low, thus avoiding the possibility of avascularity developing in the resurfaced patella. This complication will almost completely be eliminated if the patella thickness is kept greater than 13 mm after patella resection. In my experience, patella complications from the resurfaced patella are extremely rare. Many unicompartmental knees require re-operation because of the development of progressive patellofemoral arthritis. Re-operation from anterior knee pain from progressive arthritis from the unresurfaced patella has given inferior results. Overall, meta-analysis data demonstrates decreased satisfaction, increased anterior knee pain and higher early revision rates in the unresurfaced group. National joint registries, especially the Australian registry support routine resurfacing; complications are low and outcomes are improved. Even though there exists controversy as to whether the patella should be resurfaced or not, there is an overwhelming consensus in the U.S. that there is little downfall nowadays with respect to resurfacing the patella

This talk reviews the topic of patellofemoral arthroplasty from a historical, technical, and clinical perspective. Emphasis is placed on the design rationale, surgical technique, and 11 year clinical results of so-called “patient-matched” or “patient-specific” patellofemoral arthroplasty in which the trochlear implant is matched to the anatomy of the individual patient through the use of pre-operative computerized imaging scans. The implants are inlayed into the articular cartilage without any intra-operative femoral bone resection. Clinical results involving patient-matched patellofemoral arthroplasty are presented with an average follow-up of 11 years. Case studies reviewing our experience with patient-matched trochlear implants in the setting of femoral trochlear dysplasia are also presented. Patient-specific patellofemoral arthroplasty is a safe and effective treatment for patients with isolated patellofemoral arthritis. The results compare favorably with off-the-shelf patellofemoral arthroplasties that have been reported on over the past thirty years and can be carried out more efficiently. We believe the key elements that contribute to the success of patient-matched patellofemoral arthroplasty are as follows: (a) a strict inclusion criteria based on pre-operative radiographic evaluation; (b) a meticulous attention to soft-tissue balance and patellofemoral tracking at the time of arthroplasty; and (c) a patient-specific design and manufacturing methodology that ensures accurate and precise anatomic fit while simultaneously providing proper patellofemoral alignment and medial-lateral constraint