Patellofemoral Joint Replacement Research Articles

Patellofemoral Joint Replacement and Nickel Allergy: An Unusual Presentation.

Metal allergy is an unusual complication of joint replacement that may cause aseptic loosening and necessitate joint revision surgery. We present the case of nickel allergy causing aseptic loosening following patellofemoral joint replacement (PFJR) in a 54-year-old male. Joint revision surgery to a nickel-free total knee replacement was performed with good results. Our literature review shows that there is no evidence to guide the management of metal allergy in PFJR. The evidence from studies of total knee replacement is limited to retrospective case series and case reports and gives contradictory recommendations. The optimal management strategy for metal allergy in PFJR is not clear. We recommend allergy testing in patients with history of metal allergy and use of an allergen-free implant in those with positive tests. As there is no gold standard test to establish metal allergy, the choice of test should be guided by availability and recommendation from the local unit of dermatology and allergy testing. We recommend investigation for metal allergy in patients with implant loosening where other causes have been excluded.

Patellofemoral joint replacement, an evolving concept

Isolated patellofemoral arthritis is a rare disease, whose management is challenging and controversial. Patellofemoral joint replacement can be an effective treatment for this condition. The very concept of a patellofemoral implant has evolved throughout the years, resulting in more anatomic designs and reproducible surgical techniques. The clinical outcomes of this procedure are strictly related to surgical indications, implant design and appropriate surgical technique.

Biomechanics of medial unicondylar in combination with patellofemoral knee arthroplasty

Modular bicompartmental knee arthroplasty (BKA) for treatment of medio-patellofemoral osteoarthritis (OA) should allow for close to normal kinematics in comparison with unicondylar knee arthroplasty (UKA) and the native knee. There is so far no data to support this. Six fresh frozen full leg cadaver specimens were prepared and mounted in a kinematic rig with six degrees of freedom for the knee joint. Three motion patterns were applied with the native knee and after sequential implantation of medial UKA and patellofemoral joint replacement (PFJ): passive flexion-extension, open chain extension, and squatting. During the loaded motions, quadriceps and hamstrings muscle forces were applied. Infrared cameras continuously recorded the trajectories of marker frames rigidly attached to femur, tibia and patella. Prior computer tomography allowed identification of coordinate frames of the bones. Strains in the collateral ligaments were calculated from insertion site distances. UKA led to a less adducted and internally rotated tibia and a more strained medial collateral ligament (MCL). Addition of a patellofemoral replacement led to a more posterior position of both femoral condyles, a more dorsally located tibiofemoral contact point and higher MCL strain with squatting. In comparison to UKA modular BKA leads to a more dorsal tibial contact point, a medial femoral condyle being located more posteriorly, and more MCL strain. Mainly the changes to the trochlear anatomy as introduced by PFJ may account for these differences.

Revision cartilage cell transplantation for failed autologous chondrocyte transplantation in chronic osteochondral defects of the knee

The management of failed autologous chondrocyte implantation (ACI) and matrix-assisted autologous chondrocyte implantation (MACI) for the treatment of symptomatic osteochondral defects in the knee represents a major challenge. Patients are young, active and usually unsuitable for prosthetic replacement. This study reports the results in patients who underwent revision cartilage transplantation of their original ACI/MACI graft for clinical or graft-related failure. We assessed 22 patients (12 men and 10 women) with a mean age of 37.4 years (18 to 48) at a mean of 5.4 years (1.3 to 10.9). The mean period between primary and revision grafting was 46.1 months (7 to 89). The mean defect size was 446.6 mm(2) (150 to 875) and they were located on 11 medial and two lateral femoral condyles, eight patellae and one trochlea. The mean modified Cincinnati knee score improved from 40.5 (16 to 77) pre-operatively to 64.9 (8 to 94) at their most recent review (p < 0.001). The visual analogue pain score improved from 6.1 (3 to 9) to 4.7 (0 to 10) (p = 0.042). A total of 14 patients (63%) reported an 'excellent' (n = 6) or 'good' (n = 8) clinical outcome, 5 'fair' and one 'poor' outcome. Two patients underwent patellofemoral joint replacement. This study demonstrates that revision cartilage transplantation after primary ACI and MACI can yield acceptable functional results and continue to preserve the joint.

The FPV patellofemoral joint replacement mid-term results from an independent district-general hospital

The FPV patellofemoral joint replacement mid-term results from an independent district-general hospital

Mid-term results of the FPV patellofemoral joint replacement

BackgroundIsolated patellofemoral joint osteoarthritis affects approximately 10% of patients aged over 40years and treatment remains controversial. The Femoro Patella Vialli (FPV) patellofemoral joint replacement (Wright Medical Technology, UK) has been shown to restore functional kinematics of the knee close to normal. Despite its increasing popularity in recent years, there are no studies evaluating the mid-term results with an objective scoring assessment. AimsTherefore, the aim of this study was to report the clinical and radiological outcomes of FPV patellofemoral joint replacement in patients with isolated patellofemoral arthritis. MethodsBetween 2006 and 2012, we performed 53 consecutive FPV patellofemoral arthroplasties in 41 patients with isolated patellofemoral joint osteoarthritis. The mean follow-up was 3years. ResultsMean Oxford Knee Scores improved from 19.7 to 37.7 at latest follow-up. The progression of tibiofemoral osteoarthritis was seen 12% of knees. Two knees required revision to TKR at 7months post-operatively, which we attribute to poor patient selection. We had no cases of maltracking patellae, and no lateral releases were performed. ConclusionOur findings suggest the FPV patellofemoral prosthesis provides good pain relief and survivorship with no significant maltracking patellae.

Outcomes of Total Knee Replacement after Patellofemoral Arthroplasty

There is increasing interest in the use of patellofemoral joint replacements and the cohort receiving them are the youngest of any of the groups of patients undergoing a knee arthroplasty. With more contemporary prostheses, progression of arthritis in other parts of the knee joint is becoming the predominant mechanism of failure. We conducted a multicenter retrospective comparative cohort study to discover whether the outcome of total knee replacement is compromised by prior patellofemoral joint arthroplasty. A total of 21 patients with a mean age of 61 years, who were revised from a patellofemoral joint replacement to a total knee replacement, were compared with a matched cohort of patients who underwent primary total knee replacement. At a mean follow-up of 2.4 years, the primary total knee replacement cohort had significantly better Oxford Knee Scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function scores, pain visual analog scores, and EQ-5D scores. There was no significant difference in patient satisfaction or EQ-5D visual analog scale.Our results indicate that although the revision of a patellofemoral joint replacement to a total knee replacement is a technically straightforward procedure, the eventual outcome may be less satisfactory when compared with a primary total knee replacement.

Patellofemoral Arthroplasty: A Systematic Review of the Literature

Identification and management of patients with isolated patellofemoral osteoarthritis are challenging. Many of these patients present at a young age and it is important to distinguish degenerative change in the patellofemoral articulation from the other various causes of anterior knee pain. Once the diagnosis of isolated patellofemoral arthrosis has been made non-operative and conservative surgical techniques should be exhausted fully before prosthetic arthroplasty is considered. This review focuses on the use of arthroplasty for isolated patellofemoral arthrosis, in particular comparing the use of total knee against selective patellofemoral joint replacements.

Differences in the stress distribution in the distal femur between patellofemoral joint replacement and total knee replacement: a finite element study

BackgroundPatellofemoral joint replacement is a successful treatment option for isolated patellofemoral osteoarthritis. However, results of later conversion to total knee replacement may be compromised by periprosthetic bone loss. Previous clinical studies have demonstrated a decrease in distal femoral bone mineral density after patellofemoral joint replacement. It is unclear whether this is due to periprosthetic stress shielding. The main objective of the current study was to evaluate the stress shielding effect of prosthetic replacement with 2 different patellofemoral prosthetic designs and with a total knee prosthesis.MethodsWe developed a finite element model of an intact patellofemoral joint, and finite element models of patellofemoral joint replacement with a Journey PFJ prosthesis, a Richards II prosthesis, and a Genesis II total knee prosthesis. For each of these 4 finite element models, the average Von Mises stress in 2 clinically relevant regions of interest were evaluated during a simulated squatting movement until 120 degrees of flexion.ResultsDuring deep knee flexion, in the anterior region of interest, the average Von Mises stress with the Journey PFJ design was comparable to the physiological knee, while reduced by almost 25% for both the Richards II design and the Genesis II total knee joint replacement design. The average Von Mises stress in the supracondylar region of interest was similar for both patellofemoral prosthetic designs and the physiological model, with slightly lower stress for the Genesis II design.ConclusionsPatellofemoral joint replacement results in periprosthetic stress-shielding, although to a smaller degree than in total knee replacement. Specific patellofemoral prosthetic design properties may result in differences in femoral stress shielding.

Medium term results of Avon patellofemoral joint replacement.

Background:Ten to fifteen percent of knee arthritis is reported to be isolated patellofemoral arthritis. Total knee arthroplasty is not recommended for isolated patella femoral arthritis particularly in young patients. We present the retrospective review of 45 consecutive patellofemoral replacements performed in 41 such patients, between June 2002 and January 2007.Materials and Methods:All patients were operated by single surgeon (SM) or under his supervision. All forty five patients had minimum three year followup and had the data collected prospectively. No patient was lost to followup. This data was later collated by review of notes, radiographs, and a clinical followup. The patients were assessed using knee function score and Melbourne patellofemoral score.Results:The average followup was 4.5 years. The preoperative average Melbourne (Bartlett) score was 10 (range 5-21). Preoperative knee functional score averaged 57 (range 23–95). The average range of movement was 116° (range 100°–140°). Postoperatively, the average Melbourne knee score improved to 25 (range 11–30), while the knee function score was 85 (range 28 – 100). The difference was statistically significant (P<0.05). Eighty-five percent rated the result as good or excellent, while 12% rated it as fair. Five percent thought the result was poor. The most common complaint was clicking at 40° of flexion (n=7). Six patients underwent arthroscopic lateral release, which improved the symptoms in four patients. Two knees were revised one due to progression of tibiofemoral arthritis and the other due to persistent clicking, yielding a survival rate of 95.6% at an average five year followup.Conclusion:The Avon patellofemoral joint replacement provides predictably good results and excellent survivorship in the medium term, for isolated patellofemoral arthritis. However, progression of tibiofemoral arthritis remains unpredictable and therefore patient selection is crucial to ensure success. Clicking remains a potential problem and can compromise the postoperative results in upto 15% of the cases.

The Avon patellofemoral joint replacement

Between May 1998 and May 2007 we carried out 50 Avon patellofemoral joint replacements in 32 patients with isolated patellofemoral osteoarthritis. There were no revisions in the first five years, giving a cumulative survival of 100% for those with a minimum follow-up of five years. The mean follow-up was 5.3 years (2.1 to 10.2). The median Oxford knee score was 30.5 (interquartile range 22.25 to 42.25). In patients with bilateral replacements the median Euroqol General health score was 50 which was significantly lower than that of 75 in those with a unilateral replacement (p = 0.047). The main complication was progression of disease, which was identified radiologically in 11 knees (22%). This highlights the need for accurate selection of patients. Our findings suggest that the Avon prosthesis survives well and gives a satisfactory functional outcome in the medium term.

The Avon patellofemoral joint replacement

We present a prospective review of the two-year functional outcome of 37 Avon patellofemoral joint replacements carried out in 29 patients with a mean age of 66 years (30 to 82) between October 2002 and March 2007. No patients were lost to follow-up. This is the first independent assessment of this prosthesis using both subjective and objective analysis of outcome. At two years the median Oxford knee score was 39 (interquartile range 32 to 44), the median American Knee Society objective score was 95 (interquartile range 90 to 100), the median American Knee Society functional score was 85 (interquartile range 60 to 100), and the median Melbourne Knee score was 28 (interquartile range 21 to 30). Two patients underwent further surgery. Only one patient reported an unsatisfactory outcome. We conclude that the promising early results observed by the designing centre are reproducible and provide further support for the role of patellofemoral joint replacement.

Patellar Button Dissociation in a Mobile-Bearing LCS Patellofemoral Joint Arthroplasty

Patellofemoral arthroplasty is an effective treatment for isolated patellofemoral arthritis. Midterm results reveal a success rate of approximately 80% to 90% with modern designs. The reported failure mechanisms associated with patellofemoral arthroplasty include progressive tibiofemoral arthritis, patellar pain, catching or subluxation caused by soft-tissue imbalance, component malposition, and problematic designs. We present a previously unreported new complication of patellar button dissociation in a mobile-bearing LCS Patellofemoral Joint Replacement Prosthesis.

La protesi femoro-rotulea: a che punto siamo?

The patellofemoral joint replacement is a surgical treatment which was introduced in the early 50′ but has recently experienced a revival, for indications and results, due to the development of new designs available on the market. The choice of the prosthesic model to employ is nowadays directed towards straight-cut models (onlay). At present research has moved further on, developing new designs with anatomical solutions, most recently with NexGen PFJ which, apart from adopting an anatomical solution, presents a specific design for females (Gender philosophy). Our case series from January 2004 to February 2007 includes 71 patellofemoral prostheses. We have had only two failures and preliminary results are very encouraging.

Pre-operative mental wellbeing and the outcome of knee replacement

This study aimed to determine if a difference exists between the mental well being of patients prior to total knee, medial unicompartmental and patellofemoral joint replacement and then assessed its effect on outcome. One hundred and thirteen patients were identified (41 TKR, 37 UKR and 35 PFJR). All patients had mental health assessed pre-operatively using SF-12. The reduced WOMAC (rWOMAC) score was used pre-operatively and then at 8 and 24 months post-operation to assess outcome. Reduced pre-operative mental wellbeing was found in 54% of the patients. There was no statistically significant difference demonstrated between the mean mental component scores (MCS) between the three operation groups. The mean rWOMAC at 24 months in the MCS < 40 group was 28 compared to 17 in those with high mental well being (MCS > 60). Pre-operative MCS had a significant effect, such that reduced mental wellbeing was associated with a worse 24 month outcome.

The use of a tantalum-based Augmentation Patella in patients with a previous patellectomy

Patients with previous patellectomies for anterior knee pain syndrome, can remain symptomatic and develop osteoarthrosis or instability. We report our experience of the use of a novel implant to substitute for the absent native patella.Seven patients, with previous patellectomies, were treated with the Augmentation Patella (Zimmer, Allendale, USA). This implant was sutured to the patellar tendon, as part of a patello-femoral joint replacement (four cases) or total knee replacement (three cases).In three patients, the implant loosened and failed within 15 months. Two patients remained symptomatic despite solid fixation. One patient developed wound complications due to the bulk of the implant, and the procedure was abandoned in one patient as wound closure was not possible.The results of this implant in our patients with previous patellectomies have been disappointing. Previous studies where this implant has been used, have also shown high loosening and failure rates. We do not recommend its use to substitute for the absent patella.

In vitro simulation and quantification of wear within the patellofemoral joint replacement

Quantification of the wear rate in vitro is now considered an essential step in the development of a new joint replacement prior to clinical trials. However, little research exists around in vitro simulation of wear in the patellofemoral joint (PFJ) despite over 200,000 being implanted annually within the European Union. A method to simulate wear in the laboratory using four input degrees of freedom within the PFJ of total knee replacement (TKR) has been developed. Wear simulation was validated through comparison of functional kinematics and patellar surface damage modes produced in vitro to clinical outcomes. The technique has been shown to replicate the prescribed in vivo kinematics in a reproducible and repeatable manner. The wear scar areas were similar to those found in vivo. However, geometrical measurements of wear were not reliable due to creep and geometry changes. As has been found previously with tibial inserts, geometrical determination of wear volume was not found to be an effective method of comparing wear from simulators and retrievals. Change in volume calculated gravimetrically was seen to be the most repeatable measure of patellar wear in vitro.

Patellofemoral Replacement Polymer Stress During Daily Activities: A Finite Element Study

Isolated, symptomatic patellofemoral arthritis, although uncommon, has been reported to affect 8% of women and 2% of men over the age of fifty-five years1. Both conservative and surgical nonarthroplasty interventions have been advocated; however, reports on such interventions have suggested limited success2. Patellofemoral joint replacement designs as an alternative solution are beginning to reemerge largely through an appreciation of design requirements and the importance of component placement, which have been major factors in earlier clinical disappointments3-6. This study describes the influence that three different patellofemoral implant design geometries have on stresses that are associated with polymer abrasion and delamination and suggests their efficacy in clinical use. The designs included the LCS PFJ (low-contact stress patellofemoral joint; DePuy, a Johnson and Johnson Company, Warsaw, Indiana), Vanguard (Biomet, Warsaw, Indiana), and Scout (Waldemar Link, Hamburg, Germany). The former two designs are available for clinical use in the United States. Geometries for a three-dimensional, finite element model of each patellofemoral design were created by measuring the articular surfaces of implantable quality parts with use of a point laser profilometer. Surgical procedure was followed when positioning the components into a virtual left knee (Fig. 1). The results of a kinematic analysis of a generic total …

Arthritis progression after patellofemoral joint replacement

Progressive symptomatic tibiofemoral osteoarthritis (OA) following patellofemoral joint replacement (PFJR) may necessitate revision to total knee arthroplasty. This study was designed to quantify this problem in a prospective series of 103 consecutive patients who underwent PFJRs undertaken at our institution.At a mean follow-up of 7.1 years (66–102 months), 14 knees (14%) have been revised, 12 of those (12%) because of the development of symptomatic tibiofemoral OA, with a mean time to revision of 55 months (range 14 to 95 months).Available radiographs of the 89 unrevised knees were subject to blinded and randomised assessment by two observers. Postoperative AP knee radiographs were scored to assess for tibiofemoral OA progression, with definite progression seen in a median of 7% of medial compartments but 0% of lateral compartments, over a mean period of 51 months. Sulcus angles on preoperative 30° skyline radiographs were measured to assess for trochlear dysplasia. Seventeen percent of the knees without preoperative trochlear dysplasia have been revised for progression of tibiofemoral OA, compared to none of the knees with preoperative trochlear dysplasia. Furthermore, in the unrevised knees, statistically significantly more radiographic progression of tibiofemoral OA was seen in those without preoperative trochlear dysplasia (p=0.01).Our results suggest that progressive tibiofemoral OA following PFJR is an important cause of failure, but it is seen significantly less frequently when the patellofemoral arthritis is secondary to dysplasia of the femoral trochlea, suggesting that these patients are the ideal candidates for PFJR.

Patellar clunk syndrome in patellofemoral arthroplasty—a case report

Patellar clunk syndrome is characterised by the formation of a fibrous nodule at the articular side of junction of superior pole of patella and the quadriceps tendon. Until now, it is only described in posterior cruciate substituting total knee replacements. We report the patellar clunk syndrome in a lady with patellofemoral joint replacement.